INTEGRATED PROPULSION AND STEERING SYSTEM

Abstract

 An electrically driven propulsion system for a watercraft comprises an electric motor adapted to provide a mechanical power of at least 50 kW, a pulse inverter, a thrust bearing, and a transmission. The pulse inverter is electrically coupled to the electric motor and adapted to provide an electrical supply power of at least 50 kW to the electric motor. The transmission comprises a rotary shaft. The electrically driven propulsion system further comprises a common waterproof housing. The electric motor, the pulse inverter and an enclosed section of the transmission are arranged inside the common waterproof housing. An external section of the transmission is arranged outside of the common waterproof housing. The transmission is adapted to rotationally couple the external section of the transmission to the electric motor. The thrust bearing is mechanically coupled to the rotary shaft of said transmission and to the common waterproof housing. The thrust bearing is adapted to transfer a force applied to the transmission along an axial direction of said rotary shaft of the transmission to the common waterproof housing.

Description

TECHNICAL FIELD

[0001] The disclosure relates to a propulsion system for a watercraft, and more specifically to an electrically driven propulsion system, in particular to an integrated propulsion system.

BACKGROUND

[0002] A conventional propulsion system for motorized watercraft is based on an engine, such as a diesel or gasoline combustion engine, which maybe arranged inboard or outboard. Sometimes, a replacement of a component of the propulsion system, in particular of the motor, is desirable, for example to upgrade the system with a more silent and sustainable electric drive instead of the combustion engine, or because of a defect.

[0003] An inboard engine is overall well-protected by the hull from environmental influences such as seawater, weather conditions, damage in accidents, vandalism or theft. However, if the inboard engine fails, the motorized watercraft will typically need to visit a port or a shipyard for diagnostics of the failure and a subsequent repair or exchange of engine parts. In pleasure vessels such failures usually occur at random and are rarely detected ahead of time. Often the vessel needs to be craned out of the water and stored on land. Depending on the type of failure and the availability of replacement parts, this process may take several days or even longer.

[0004] In case of a failure of an outboard engine, diagnostics of the failure and a subsequent repair or exchange of engine parts in a harbor or a shipyard are also an option. The exposed arrangement of the outboard motor alternatively permits to change the engine as a whole quickly, if a replacement part is available. However, the exposed arrangement results in a stronger exposure to the environmental influences. Moreover, the exposed arrangement of the outboard engine may cause a significant noise level onboard and especially on deck. Also, in case of a high-power outboard engine, for example with a power of 50 kW and more, changing the engine as a whole may be complicated by its significant weight, for example in case of a diesel engine.

OVERVIEW

[0005] In view of the technical problems laid out above, there is a need for an improved propulsion system for a watercraft which facilitates installation and replacement.

[0006] On a conventional vessel, the propulsion system may be composed of individually selected, separate components, which a plethora of combinations on different boats. Consequently, installation, replacement and repair may require expert knowledge of each individual component.

[0007] In a first aspect, an electrically driven propulsion system for a watercraft comprises an electric motor adapted to provide a mechanical power of at least 50 kW, a pulse inverter, a thrust bearing, and a transmission. The pulse inverter is electrically coupled to the electric motor and adapted to provide an electrical supply power of at least 50 kW to the electric motor. The transmission comprises a rotary shaft. The electrically driven propulsion system further comprises a common waterproof housing. The electric motor, the pulse inverter and an enclosed section of the transmission are arranged inside the common waterproof housing. An external section of the transmission is arranged outside of the common waterproof housing. The transmission is adapted to rotationally couple the external section of the transmission to the electric motor. The thrust bearing is mechanically coupled to the rotary shaft of said transmission and to the common waterproof housing. The thrust bearing is adapted to transfer a force applied to the transmission along an axial direction of said rotary shaft of the transmission to the common waterproof housing.

[0008] The electrically driven propulsion system may serve to combine all essential electrical and electromechanical components in an integrated, monolithic unit defined by the common waterproof housing. Therefore, a user equipping the watercraft with the electrically driven propulsion system may implement a fully optimized system, without any need for modifications at the user's end. No expert skill of the user is required, as may be the case for conventional systems combining individually selected components. A risk of implementing a suboptimal system, for example related to a suboptimal combination of pulse inverter and electric motor, may be avoided.

[0009] Making use of an electric motor instead of a conventional combustion engine, the electrically driven propulsion system may improve the sustainability of the watercraft as well as the comfort on board. Vibrations and noise may be minimized using the electric motor. As it combines all essential components in a single component, the electrically driven propulsion system according to the invention may be ideal for replacing a conventional combustion engine, avoiding an effort of designing an individual electrical system for the boat.

[0010] Moreover, the electrically driven propulsion system may be replaced as a whole quickly, in particular in case of a failure of one of its components. The defective component may be diagnosed and replaced later off-site, for example in a dedicated facility, as the watercraft with the replaced propulsion system is already back in operation. In other words, the electrically driven propulsion system according to the description may be supplied to the user as a plug-n-play system, which may be installed and replaced quickly and easily.

[0011] Moreover, the electric motor may have a lower weight than a combustion engine adapted to provide a similar mechanical power, thus facilitating the installation or replacement of the electrically driven propulsion system.

[0012] The common waterproof housing may improve the electrical safety of the system and reduce a risk of an electric shock for a user. Water may be prevented from entering the electrical components and corroding them or causing unwanted shunts, which might otherwise pose a danger to the user.

[0013] The common waterproof housing may be composed of an electrically insulating material or comprise a layer of an electrically insulating material. The layer of the electrically conductive material may fully surround the electric motor and/or a motor inverter and/or any electrical connection between the electric motor, the inverter and/or a power inlet.

[0014] Alternatively, or in addition, the common waterproof housing may comprise a layer of an electrically conductive material, wherein the layer of the electrically conductive material fully surrounds the electric motor and/or the motor inverter and/or any electrical connection between the electric motor, the inverter and/or the power inlet. The layer of the electrically conductive material may be grounded.

[0015] The axial direction of the rotary shaft may refer to an axis of rotation the rotary shaft.

[0016] Alternatively, or in addition, the axial direction of the rotary shaft may refer to a thrust direction of the rotary shaft through the common waterproof housing.

[0017] The axial direction of the rotary shaft may refer to an axis of rotation of a rotary shaft thrusting through the common waterproof housing.

[0018] The axial direction of the rotary shaft may refer to a direction along which the rotary shaft extends.

[0019] The axial direction of the rotary shaft may refer to a line connecting the enclosed section of the transmission and the external section of the transmission, in particular to a line connecting a portion the enclosed section of the transmission closest to the external section and a portion of the external section of the transmission closest to the enclosed section.

[0020] The external section of the transmission may comprise a propeller coupling adapted for mounting a propeller.

[0021] Corresponding embodiments may comprise all essential electrical, electromechanical, and mechanical components for driving the propeller of the watercraft using the electric motor. The additional integration of the mechanical components may further facilitate a simple installation of a fully optimized system.

[0022] The watercraft may comprise a hull.

[0023] The hull may comprise an opening.

[0024] The electrically driven propulsion system may be adapted to be connected as a whole to the hull with the opening, such that at least a section of the electric motor is arranged on a first side of the opening and the propeller coupling and at least a portion of the common waterproof housing are arranged on a second side of the opening opposite to the first side, and such that a waterproof connection forms between the common waterproof housing and the hull.

[0025] When the electrically driven propulsion is connected to a hull, the electric motors may be located inside of the hull where they are protected from environmental influences and acoustically shielded to minimize a noise level on board and on deck.

[0026] The arrangement of the electrically driven propulsion system in the hull or transom, part inboard and part outboard, may further allow for a linear arrangement of the system, thus avoiding additional mechanisms to convert a vertical rotation into a rotation around a horizontal axis or vice versa. In particular, a known planetary gearing may be incorporated into the enclosed section of the transmission to optimize its optimum rotational speed (i. e., the rotational speed of the external section for which the overall efficiency of electrically driven propulsion system is the highest) to a given watercraft or propeller.

[0027] This arrangement further may further allow for incorporating a gearing mechanism (gear box) in the electrically driven propulsion system to provide a system with a maximized efficiency at a rotational speed matched to an optimum rotation speed of a propeller for accelerating the watercraft.

[0028] The electrically driven propulsion system may be adapted to be connected as a whole to the hull with the opening, such that the electric motor is arranged on the first side of the opening and/or such that at least a portion of the motor section is arranged on the first side of the opening, in particular the entire motor section.

[0029] The hull may comprise a transom. The opening may be arranged on the transom.

[0030] Alternatively, the opening may be arranged on a bottom side of the hull.

[0031] The propeller coupling may comprise a threading, a hub and/or a driving collar adapted for mounting a propeller.

[0032] The electrically driven propulsion system may be adapted to be connected as a whole to the watercraft, in particular to the hull with the opening, for example such that at least a portion of the enclosed section of the transmission is arranged on the second side of the opening.

[0033] The waterproof connection may be adapted to close the opening of the hull, in particular in a waterproof way.

[0034] The first side may correspond to an inside of the watercraft. The second side may correspond to an outside of the watercraft.

[0035] The electrically driven propulsion system may be adapted to be connected as a whole to the hull with the opening from the outside of the watercraft.

[0036] The transmission may be adapted to rotationally couple the propeller coupling to the electric motor and/or comprise any element adapted to rotationally couple the propeller coupling to the electric motor.

[0037] The transmission may comprise a gear ratio. The gear ratio may be selected according to the watercraft and mounting type within the craft.

[0038] The electrically driven propulsion system may be adapted to be mounted to a connecting frame connected to the hull with the opening. The connecting frame may be arranged between the hull with the opening and the electrically driven propulsion system.

[0039] The electrically driven propulsion system may further comprise a noise/vibration sensor arranged inside the common waterproof housing, in particular a plurality of noise/vibration sensors arranged inside the common waterproof housing.

[0040] The noise/vibration sensor may be adapted to generate an electronic signal corresponding to a sound or vibrational level at the noise/vibration sensor.

[0041] The noise/vibration sensor may be adapted to detect a change in a sound or vibrational level of the electrically driven propulsion system, in particular an increase in the sound or vibrational level of the electrically driven propulsion system, in particular of the electric motor and/or of the transmission.

[0042] The noise/vibration sensor may comprise a signal line extending from inside of the common waterproof housing out of the common waterproof housing. The signal line of the noise/vibration sensor may comprise a waterproof feedthrough through the common waterproof housing. The signal line may be adapted to transfer the electronic signal from inside of the common waterproof housing out of the common waterproof housing.

[0043] The electrically driven propulsion system may further comprise a processor for analyzing the electronic signal of the noise/vibration sensor.

[0044] The detected changes in the sound, noise or vibrational pattern of the electrically driven propulsion system or its components may serve as an indication of an upcoming failure of the system. The noise/vibration sensor may generate electronic signals representing the detected sound level, and send these electronic signals through a signal line for analysis by a processor to detect a change in the noise pattern characteristic of a failure. The processor maybe part of the electrically driven propulsion system or the noise/vibration sensor.

[0045] Alternative, or in addition, the signal line may transmit the electronic signal out of the common waterproof housing for analysis by an external processor. When the processor detects the change, an electronic report message recommending an exchange of the electrically driven propulsion system may be generated.

[0046] The noise/vibration sensor may be adapted to detect a contact or a collision of the electrically driven propulsion system or the hull with an obstacle. In particular, the noise/vibration sensor may be adapted to detect a change in the sound or vibrational level exceeding a critical value, in particular a critical value related to a collision of the electrically driven propulsion system or the hull with an obstacle. The noise/vibration sensor or a processor coupled to the noise/vibration sensor may be adapted to send an electronic warning message upon detection of a contact or a collision.

[0047] The noise/vibration sensor maybe arranged in a vicinity of the electric motor, in particular in direct physical contact with the electric motor.

[0048] Alternatively or in addition, the noise/vibration sensor may be arranged in a vicinity of the portion of the common waterproof housing arranged on the second side, in particular in the portion of the common waterproof housing arranged on the second side and/or in direct contact with an inner side of the portion of the common waterproof housing arranged on the second side.

[0049] The electric motor may be an axial flux motor.

[0050] A geometry of the axial flux motor may beneficially permit to add or remove an electric motor, and may thereby improve the modular design and the design flexibility of the electrically driven propulsion system. The axial flux motor may be constructed with higher power densities than conventional engines and electric motors, such as radial flux motors. As a revolution speed of the axial flux motor is similar to the optimal revolution speed of the propeller coupling or the propeller, the transmission may have a small gear ratio and thus a higher efficiency than a gearbox with a high gear ratio typically applied in combination with an engine or an electric motor with a higher revolution speed.

[0051] The transmission may comprise a first rotary shaft functionally coupled to the electric motor.

[0052] The transmission may comprise a second rotary shaft comprising the external section of the transmission, in particular the propeller coupling.

[0053] The transmission may comprise a gear ratio.

[0054] The transmission may comprise a gearing mechanism. The gearing mechanism may be adapted to comprise the gear ratio. The gearing mechanism may be adapted to rotationally couple the first rotary shaft to the second rotary shaft.

[0055] The gearing mechanism may be adapted to implement an offset between an axis of the first rotary shaft and an axis of the second rotary shaft.

[0056] Alternatively, the transmission may comprise a belt or a chain rotationally coupling the first rotary shaft and the second rotary shaft.

[0057] The belt or the chain may be adapted to implement an offset between an axis of the first rotary shaft and an axis of the second rotary shaft.

[0058] The gearing mechanism may comprise a spur gear adapted to implement the offset between the axis of the first rotary shaft and the axis of the second rotary shaft.

[0059] The gear ratio may refer to a revolution speed of the first rotary shaft per revolution speed of the second rotary shaft.

[0060] The spur gear may be adapted to implement the gear ratio.

[0061] Alternatively, or in addition, the gearing mechanism may comprise a planetary gearing. The planetary gearing or a combination of the planetary gearing with the spur gear may be adapted to implement the gear ratio.

[0062] The gear ratio of the gearing mechanism maybe at most 2, in particular at most 1.5 in particular at most 1.3 or at most 1.25.

[0063] A small gear ratio may improve the efficiency of the transmission and of the electrically driven propulsion system, for example as compared to a high gear ratio typically applied in combination with an engine or an electric motor with a higher revolution speed.

[0064] The thrust bearing maybe adapted to implement a waterproof feedthrough of the transmission through the common waterproof housing.

[0065] The thrust bearing may be rotationally coupled to a rotary shaft of the transmission, in particular to the second rotary shaft.

[0066] The thrust bearing may be rotationally coupled to the gearing mechanism.

[0067] The thrust bearing may form a section of the common waterproof housing or at least a section of the thrust bearing may be arranged in the common waterproof housing.

[0068] The thrust bearing may provide a waterproof connection between the transmission, in particular the rotary shaft, and the common waterproof housing.

[0069] The thrust bearing may comprise a first ring coupled to the rotary shaft and a second ring coupled to the common waterproof housing. The first ring and the second ring may be arranged on or around an axis of the rotary shaft at different positions along the axial direction.

[0070] The first ring may be arranged abaft at least a section of the second ring, in particular abaft the entire second ring.

[0071] The first ring and the second ring may be separated by roller elements, in particular only by the roller elements.

[0072] The electrically driven propulsion system may be adapted to rotate the propeller to generate the force applied to the transmission along the axial direction of the transmission.

[0073] The gear ratio may be selected for a revolution speed of the first rotary shaft to be at least 1700 revolutions per minute (rpm) when the electromotor is operated at a motor revolution speed adapted for a maximum efficiency of the electromotor.

[0074] The gear ratio may be selected for the revolution speed of the first rotary shaft to be at most 2500 revolutions per minute (rpm) when the electromotor is operated at the motor revolution speed adapted for the maximum efficiency of the electromotor.

[0075] The revolution speed of the first rotary shaft, or of the propeller coupling, or of the propeller, respectively, in the range of 1700-2500 rpm, may ensure a maximum efficiency of the propulsion system. In particular, a smaller revolution speed closer to 1700 rpm may be selected for a propulsion system for a larger watercraft, and a larger revolution speed closer to 2500 rpm may be selected for a propulsion system for a smaller watercraft.

[0076] The second rotary shaft may be displaced with respect to the first rotary shaft in the plane perpendicular to the longitudinal direction.

[0077] The second rotary shaft may be essentially parallel to the first rotary shaft, for example within an angle of 10° or within an angle of 8°.

[0078] The transmission may comprise a propeller shaft (second rotary shaft) comprising the propeller coupling and an axis, and an orientation of the axis of the second rotary shaft may be static.

[0079] A static second rotary shaft (propeller shaft) may improve the robustness and durability of the system and reduce a risk of a failure.

[0080] The electrically driven propulsion system may further comprise a propeller mounted to the propeller coupling.

[0081] The propeller may be a propeller for a surface drive.

[0082] A corresponding propeller may optimize the electrically driven propulsion system for an application as a surface drive. A surface drive may provide an improved energy efficiency as compared to a conventional drive, in particular at an elevated speed such as at least 20 knots.

[0083] The propeller may comprise a radial section, wherein the radial section extends radially from a center of the propeller.

[0084] The propeller may comprise an essentially flat section in direct physical contact with the radial section. The essentially flat section may extend from the radial section essentially along an azimuthal direction.

[0085] The essentially flat section may comprise an outer edge.

[0086] The outer edge may be essentially perpendicular to the radial section in a stern projection of the electrically driven propulsion system.

[0087] The transmission may be adapted to rotationally couple the propeller to the electric motor and/or comprise any element adapted to rotationally couple the propeller to the electric motor.

[0088] The propeller may comprise a diameter of at least 20 cm, in particular at least 25 cm, in particular at least 30 cm, in particular at least 35 cm or at least 40 cm.

[0089] The propeller may comprise a diameter of at most 70 cm, in particular at most 60 cm or at most 55 cm.

[0090] The propeller may comprise a pitch of at least 40 cm, in particular at least 45 cm, in particular at least 50 cm, or at least 55 cm.

[0091] The propeller may comprise a pitch of at most 110 cm, in particular at most 100 cm, in particular at most 90 cm, or at most 85 cm.

[0092] A ratio of the diameter of the propeller over the pitch of the propeller may be at least 1.2, in particular at least 1.3 or at least 1.4.

[0093] A ratio of the diameter of the propeller over the pitch of the propeller may be at most 1.8, in particular at most 1.7 or at most 1.6.

[0094] The pitch may be defined by angle of the outer edge with respect to a longitudinal direction. A tangent of the angle of the outer edge with respect to a longitudinal direction may be the diameter of the propeller per half the pitch of the propeller.

[0095] A weight of the electrically driven propulsion system per maximum power of the electric motor may not exceed 0.7 kg/kW, in particular not exceed 0.6 kg/kW, in particular not exceed 0.5 kg/kW, in particular not exceed 0.4 kg/kW or not exceed 0.3 kg/kW.

[0096] A weight of the electrically driven propulsion system per maximum torque at the propeller may not exceed 0.14 kg/Nm, in particular not exceed 0.12 kg/Nm, in particular not exceed 0.1 kg/Nm, in particular not exceed 0.08 kg/Nm or not exceed 0.06 kg/Nm.

[0097] The common waterproof housing may be adapted to fulfill at least IP65 standards.

[0098] The waterproof connection between the common waterproof housing and the hull may encircle the opening.

[0099] The common waterproof housing may comprise a motor section in which the electric motor is arranged.

[0100] The common waterproof housing may comprise a transmission section in which the enclosed section of the transmission is arranged. The transmission section may be different from the motor section.

[0101] The motor section may completely be arranged forward of the portion of the common waterproof housing arranged on the second side transmission section and/or of the transmission section. In particular, the motor section may fully be comprised in a volume defined by a forward translation of a cross section of the portion of the common waterproof housing arranged on the second side transmission section and/or a cross section of the transmission section.

[0102] Corresponding embodiments may provide an optimized geometry for mounting them to a transom of the watercraft. Therefore, the motor section may be introduced into the transom at least partially, preferably as a whole, such that the motor rests inside the hull. The portion of the common waterproof housing arranged on the second side transmission section and/or of the transmission section may be wider than the motor section and may serve as a stopper to ensure the predefined mounting depth. It may end up position abaft the motor section and the motor, at an ideal position e. g. for a surface drive.

[0103] The transmission section may be arranged abaft the motor section and/or below the motor section, for example on average, according to the respective centers of the sections, or completely.

[0104] The electrically driven propulsion system may comprise a longitudinal direction.

[0105] The longitudinal direction of the electrically driven propulsion system may refer to a direction perpendicular to the hull at the opening.

[0106] The transmission of the electrically driven propulsion system may be adapted to pass through the opening of the hull when the electrically driven propulsion system is connected to the hull.

[0107] The longitudinal direction of the transmission may refer to a direction at which the transmission passes through the opening of the hull.

[0108] An extension of the portion of the common waterproof housing arranged on the second side in a plane perpendicular to the longitudinal direction may exceed an extension of the motor section in a second plane perpendicular to the longitudinal direction.

[0109] An extension of the transmission section in a plane perpendicular to the longitudinal direction may exceed an extension of the motor section in a second plane perpendicular to the longitudinal direction.

[0110] A width of the portion of the common waterproof housing adapted to be arranged on the second side may exceed a width of the motor section.

[0111] This arrangement may support a quick and simple exchange of the electrically driven propulsion system to the ideal mounting depth by inserting the motor section into the hull and using the portion of the common waterproof housing adapted to be arranged on the second side as a stopper.

[0112] The width of the portion of the common waterproof housing adapted to be arranged on the second side may refer to a width of a cross section of the portion of the common waterproof housing arranged on the second side.

[0113] The width of the motor section may refer to a width of a cross section of the motor section.

[0114] The extension of the transmission section in the plane perpendicular to the longitudinal direction may refer to a width of the transmission section or to a height of the transmission section or to a maximum extension of the transmission section in the plane perpendicular to the longitudinal direction. For example, the extension of the transmission section in the plane perpendicular to the longitudinal direction may refer to a width or a height of the transmission section, whichever one is larger.

[0115] The extension of the motor section in the second plane perpendicular to the longitudinal direction may refer to a width of the motor section or to a height of the motor section or to a maximum extension of the motor section in the second plane perpendicular to the longitudinal direction. For example, the extension of the motor section in the second plane perpendicular to the longitudinal direction may refer to a width or a height of the motor section, whichever one is larger.

[0116] The extension of the motor section along any direction in the plane perpendicular to the longitudinal direction may be at most 80 cm, in particular at most 70 cm, or at most 60 cm.

[0117] The extension of the motor section along any direction in the plane perpendicular to the longitudinal direction may be at least 20 cm, in particular at least 25 cm, or at least 30 cm.

[0118] The motor section may be adapted to provide a motor upgrade space adapted to receive a motor power upgrade component.

[0119] The motor power upgrade component may be adapted to increase the mechanical power that the electric motor is adapted to provide. In particular, the motor power upgrade component may be adapted to increase the mechanical power that the electric motor is adapted to provide by at least 20 kW, in particular by at least 30 kW, in particular by at least 40 kW or by at least 50 kW.

[0120] The motor upgrade space may be arranged in direct contact with the transmission, in particular with the enclosed section of the transmission and/or the first rotary shaft.

[0121] A corresponding electric motor and the corresponding motor section may facilitate a modular design of the electrically driven propulsion system. The electrically driven propulsion system may easily be adapted to fulfill the requirements of a wide variety of ships or boats, for example in terms of propulsion power. Moreover, an electrically driven propulsion system held in readiness for repair may quickly be adapted to replace any other specimen of the electrically driven propulsion system in case of a failure.

[0122] The motor upgrade space may be comprised in the electric motor, and/or the electric motor may be adapted to receive the motor power upgrade component.

[0123] The motor upgrade space may be arranged in the electric motor or in direct physical contact with the electric motor.

[0124] The electric motor may comprise at least one stator adapted to generate an electric field in a field region, and at least one rotor arranged rotatably in the field region. The motor upgrade space maybe arranged in the field region. The motor power upgrade component may comprise or be at least one additional rotor adapted to be arranged rotatably in the field region.

[0125] The at least one rotor and the motor upgrade space and/or the at least one additional rotor may have a same shape, in particular a same cylindrical shape.

[0126] The at least one additional rotor may comprise or be at least one additional rotor disc.

[0127] The at least one rotor and the at least one additional rotor may have a same input voltage or a same input current.

[0128] The at least one additional rotor may be adapted to generate a second magnetic field. The at least one stator may comprise or be composed of a first stator and a second stator, and the motor upgrade space may be arranged between the first stator and the second stator.

[0129] Alternatively, the motor upgrade space and the at least one additional rotor may be arranged on opposite sides of the at least one stator.

[0130] Alternatively, or in addition, the motor power upgrade component may comprise or be at least one additional electric motor exchangeable with the electric motor, in particular at least two additional electric motors each exchangeable with the electric motor, in particular at least three additional electric motors each exchangeable with the electric motor.

[0131] The electric motor and the motor upgrade space and/or the additional electric motor exchangeable with the electric motor may have a same shape, in particular a same cylindrical shape.

[0132] The electric motor and the motor upgrade space and/or the additional electric motor exchangeable with the electric motor may have a same radius or a same extension along a radial direction of the respective electric motor. Alternatively, or in addition, the electric motor and the additional electric motor exchangeable with the electric motor may have a same length or a same extension along a longitudinal direction of the respective electric motor.

[0133] The electric motor and the additional electric motor exchangeable with the electric motor may have a same input voltage or a same input current.

[0134] The electric motor and the additional electric motor exchangeable with the electric motor may have a same maximum power.

[0135] All electric motors arranged in the common waterproof housing and/or the electric motor with the motor power upgrade component may together be adapted to provide a total mechanical power of at least 100 kW, in particular of at least 300 kW, in particular of at least 400 kW or of at least 500 kW.

[0136] The motor upgrade space may be arranged abaft the electric motor or the stator, or forward of the electric motor or the stator, in particular in direct physical contact.

[0137] The transmission may be adapted to transfer a mechanical power of at least 100 kW from the electric motor to the external section, in particular to the propeller coupling, in particular a mechanical power of at least 150 kW, in particular of at least 200 kW, in particular of at least 300 kW, in particular of at least 400 kW or of at least 500 kW.

[0138] Additional components, such as the transmission or a pulse inverter, may be predesigned to support the motor upgrade with the motor power upgrade component.

[0139] The common waterproof housing may comprise a ring-shaped seal face adapted to provide the waterproof connection.

[0140] The ring-shaped seal face may be adapted to encircle the opening of the hull.

[0141] The ring-shaped seal face may encircle the transmission, in particular the first rotary shaft or the second rotary shaft and/or a gearbox of the transmission.

[0142] The ring-shaped seal face may encircle a region comprising a projection of the motor section onto the region.

[0143] The longitudinal direction may refer to a direction perpendicular to the ring-shaped seal face.

[0144] The transmission may pass through the ring-shaped seal face.

[0145] The longitudinal direction may refer to a direction at which the transmission passes through the ring-shaped seal face.

[0146] The electrically driven propulsion system may comprise fixing means in direct physical contact with the ring-shaped seal face and adapted to provide the waterproof connection.

[0147] The fixing means of the electrically driven propulsion system may be adapted to couple to through holes of the hull with the opening or in a connecting frame.

[0148] The fixing means of the electrically driven propulsion system may comprise or be threaded holes and/or threaded studs.

[0149] The ring-shaped seal face maybe adapted to be arranged on the second side of the opening.

[0150] The electrically driven propulsion system may further comprise a heat exchanger arranged in the common waterproof housing.

[0151] A primary side of the heat exchanger may comprise at least one primary coolant opening.

[0152] The at least one primary coolant opening may be arranged outside of the common waterproof housing.

[0153] In particular, the at least one primary coolant opening may be adapted to be arranged on the second side of the opening.

[0154] A secondary side of the heat exchanger may comprise at least one secondary coolant opening arranged outside of the common waterproof housing.

[0155] In particular, the at least one primary coolant opening may be adapted to be arranged on the first side of the opening.

[0156] The heat exchanger may be adapted to transfer heat from its secondary side to its primary side, in particular from a coolant of the secondary side to a coolant of the primary side.

[0157] The heat exchanger may comprise a coolant pump adapted to generate a flow of the coolant of the primary side of the heat exchanger and/or the secondary side of the heat exchanger.

[0158] The primary side of the heat exchanger maybe adapted to receive and/or to release water from the second side of the opening, in particular (sea) water from the second side of the opening. In particular, the at least one primary coolant opening may be adapted to be below a water line of the watercraft when the electrically driven propulsion system is mounted to the watercraft.

[0159] The primary side of the heat exchanger may be adapted to use water taken up from the surrounding body of water via the at least one primary coolant opening as a coolant, in particular for cooling the secondary side of the heat exchanger.

[0160] The secondary side of the heat exchanger may comprise a cooling liquid of a selected composition and or a cooling liquid such as glycol.

[0161] The secondary side of the heat exchanger may be thermally coupled to at least one element of the electrically driven propulsion system such as the electric motor and/or the pulse inverter and/or the thrust bearing.

[0162] The secondary side of the heat exchanger, may comprise at least one secondary coolant channel thermally coupling the heat exchanger to the at least one element of the electrically driven propulsion system such as the electric motor and/or the pulse inverter and/or the thrust bearing and/or to the at least one secondary coolant opening.

[0163] The primary side of the heat exchanger may comprise at least one primary coolant channel thermally coupling the heat exchanger to the at least one primary coolant opening.

[0164] The electrically driven propulsion system may comprise an integrated heat exchanger for cooling the mechanical or electrical components of the system, such as the electric motor or the pulse inverter. The integration of the heat exchanger with the system may give direct access to a surrounding body of water, which may supply the coolant for the primary side of the heat exchanger, without requiring any further openings in the hull.

[0165] When the electrically driven propulsion system is mounted to a watercraft, the secondary coolant opening may be used to access the secondary side of the heat exchanger from inside of the watercraft and use it for cooling watercraft facilities such as a battery, additional electronics, or a cabin.

[0166] The at least one primary coolant opening and the at least one secondary coolant opening may refer to openings for a coolant in the common waterproof housing connecting to the heat exchanger and waterproof to any other component of the electrically driven propulsion system. The pulse inverter may comprise a power inlet functionally accessible from outside the common waterproof housing. The power inlet may be adapted to be arranged on the first side of the opening.

[0167] The pulse inverter may be adapted to provide an electrical output power of at least two times the mechanical power that the electric motor is adapted to provide, in particular of at least three times the mechanical power that the electric motor is adapted to provide or at least four times the mechanical power that the electric motor is adapted to provide.

[0168] The pulse inverter may be adapted to provide an electrical output power of at least 100 kW, in particular of at least 150 kW, in particular of at least 200 kW, in particular of at least 300 kW, in particular of at least 400 kW or of at least 500 kW.

[0169] As the pulse inverter is arranged in the common waterproof housing together with the electric motors, an optimized pulse inverter for the electric motors may be provided, for example to optimize an energy efficiency of the combination of pulse inverter and electric motors, thus optimizing a range of a watercraft using the electrically driven propulsion system.

[0170] The pulse inverter may be adapted to be coupled to the at least one additional electric motor and to provide an electrical supply current to the at least one additional electric motor. The pulse inverter may be adapted to be coupled to the at least two additional electric motors and to provide an electrical supply current to the at least two additional electric motors. The pulse inverter may be adapted to be coupled to the at least three additional electric motors and to provide an electrical supply current to the at least three additional electric motors.

[0171] The pulse inverter may comprise a pulse width modulator.

[0172] The electrically driven propulsion system may further comprise a rudder actuator, wherein at least a section of the rudder actuator is arranged inside the common waterproof housing, in particular wherein the entire rudder actuator is arranged inside the common waterproof housing.

[0173] The rudder actuator may comprise an electric input. The electric input may be functionally accessible from outside the common waterproof housing.

[0174] The rudder actuator may be adapted to convert the electric input into a mechanical movement.

[0175] The rudder actuator may further comprise a tiller arm adapted to couple to at least one rudder. In particular, the tiller arm may be adapted to transmit the mechanical movement to the at least one rudder.

[0176] The tiller arm may be adapted to couple to at least two rudders, in particular to exactly two rudders.

[0177] The rudder actuator may comprise a central tiller arm adapted to couple to a starboard rudder and a portside rudder. The central tiller arm may be adapted to couple to the starboard rudder via a starboard tiller arm. The central tiller arm may be adapted to couple to the portside rudder via a portside tiller arm.

[0178] The electrically driven propulsion system may further comprise at least one rudder, in particular at least two rudders, in particular exactly two rudders.

[0179] The at least one rudder maybe arranged portside and/or starboard the propeller coupling.

[0180] The electrically driven propulsion system may further comprise a data input functionally accessible from outside the common waterproof housing and coupled to the pulse inverter and/or the rudder actuator, in particular wherein the data input comprises a data input connector functionally accessible from outside the common waterproof housing and adapted to be arranged on the first side of the opening.

[0181] The data input may be adapted to control an output power of the pulse inverter and/or a position of a rudder.

[0182] The data input may allow for software updates of the electrically driven propulsion system, in particular to improve the energy efficiency of the electric motor, the transmission, and/or the pulse inverter even further.

[0183] The data input may be adapted to receive at least one controller parameter for the pulse inverter and/or the rudder actuator, and to update the electrically driven propulsion system with the at least one controller parameter.

[0184] The electrically driven propulsion system may further comprise a battery adapted to provide a supply power of at least 50 kW to the pulse inverter. The battery may be arranged outside of the common waterproof housing and be adapted to provide the supply power to the pulse inverter via the power inlet.

[0185] The battery may comprise a battery voltage matching an optimum input voltage of the pulse inverter. The optimum input voltage of the pulse inverter may correspond to an input voltage of the pulse inverter, at which a ratio between an output power of the pulse inverter and the supply power provided to the pulse inverter is maximum.

[0186] In a second aspect, a connecting frame for connecting a propulsion system to a hull with an opening comprises a first ring-shaped element, a second ring-shaped element, a first sealing face, and a second sealing face. The first ring-shaped element comprises a first opening, first connecting elements, and through holes. The second ring-shaped element comprises a second opening; second connecting elements, wherein the first connecting elements and the second connecting elements comprise a first common arrangement; and detachable connection elements adapted to couple to the fixing means of the propulsion system. The first sealing face is arranged on the first ring-shaped element and encircles the first opening. The second seal face is arranged on the first ring-shaped element opposite to the first sealing face and encircling the second opening. The first ring-shaped element and second ring-shaped element are adapted to be connected using the first connecting elements and the second connecting elements and with a relative orientation defined by the first common arrangement. According to the relative orientation, the first opening overlaps with the second opening to form an opening of the connecting frame; the through holes coincide with the detachable connection elements; and the first sealing face is arranged between the connected first ring-shaped element and second ring-shaped element and adapted to provide a waterproof connection between the connecting frame and the hull with the opening.

[0187] The connecting frame may allow for a quick and safe exchange of the electrically driven propulsion system as a whole. In particular, the risk of damaging the hull is reduced, as any physical contact between moving components and the hull may be prevented.

[0188] The first opening and the second opening may comprise a common shape. The common shape of the first opening and the second opening may coincide according to the relative orientation of the connected first ring-shaped element and second ring-shaped element.

[0189] The through holes and the detachable connection elements may comprise a second common arrangement. The second common arrangement of the through holes and the detachable connection elements may coincide according to the relative orientation of the connected first ring-shaped element and second first ring-shaped element.

[0190] The detachable connection elements may be adapted to couple to bolts as the fixing means. The detachable connection elements may comprise or be threaded holes.

[0191] The connecting frame may further comprise an outer sealing element with a shape corresponding to a shape of the second sealing face, adapted to be arranged between the connected second ring-shaped element and the propulsion system, and adapted to provide a waterproof connection between the second sealing face and the propulsion system.

[0192] The connecting frame may further comprise an inner sealing element with a shape corresponding to a shape of the first sealing face, adapted to be arranged between the connected first ring-shaped element and second ring-shaped element, and adapted to provide a waterproof connection between the second ring-shaped element and the hull with the opening.

[0193] The opening of the connecting frame may have a width of at least 20 cm, in particular of at least 25 cm or of at least 30 cm.

[0194] The first width and/or the second width may be at least 20 cm, in particular at least 25 cm or at least 30 cm.

[0195] A connecting system may comprise the connecting frame and a support element.

[0196] The support element may be adapted to mechanically support the propulsion system.

[0197] The support element may be adapted to define a position and/or an angle of the propulsion system relative to the connecting frame, in particular a distance of a motor and/or a far end of the propulsion system from the connecting frame.

[0198] The support element may be adapted to be connected to the connecting frame, in particular such that the support arm extends away from the connecting frame.

[0199] The support element may be connected to the connecting frame, in particular such that the support arm extends away from the connecting frame.

[0200] The support element may be connected to the connecting in direct physical contact with the connecting frame. The support element may be connected to the connecting frame permanently or with a detachable connection.

[0201] The support element and a portion of the connecting frame may form an integral piece.

[0202] The support element may comprise a support arm.

[0203] The support arm may comprise an elongated shape.

[0204] The support arm may extend away from the connecting frame.

[0205] The support arm may comprise an upper surface corresponding to a lower edge of the opening of the connecting frame and/or of the first opening.

[0206] The upper surface of the support arm may extend away from the lower edge of the opening of the connecting frame and/or of the first opening.

[0207] The support arm may be connected to the connecting frame and/or be in direct physical contact with the connecting frame.

[0208] The support element may further comprise a support column extending away from the support arm. The support column may be adapted to mechanically support the propulsion system and/or be in direct physical contact with the propulsion system. The support column may be connected to the support arm and/or be in direct physical contact with the support arm.

[0209] In a third aspect, a method is provided for connecting an electrically driven propulsion system as a whole to a hull with an opening. The electrically driven propulsion system comprises an electric motor adapted to provide a mechanical power of at least 50 kW; a transmission functionally coupled to the electric motor, the transmission comprising a propeller coupling adapted for mounting a propeller; and a common waterproof housing. The electric motor and a section of the transmission are arranged inside the common waterproof housing. The common waterproof housing comprises a motor section in which the electric motor is arranged. The method comprises providing the electrically driven propulsion system as a whole on a second side of the opening of the hull; moving, while keeping the electrically driven propulsion system assembled as a whole and while keeping the propeller coupling on the second side, the motor section through the opening to a first side of the opening opposite to the second side; and fixing the electrically driven propulsion system to the hull with the opening; and forming a waterproof connection between the hull and the common waterproof housing.

[0210] Thus, the electrically driven propulsion system as a whole may be connected to a hull quickly and reliably. The electrically driven propulsion system may be disconnected from the hull just as easily and quickly by performing the reverse of each step and in a reversed order of the steps. In case of a failure of the electrically driven propulsion system, the electrically driven propulsion system as a whole may be changed by disconnecting the defective electrically driven propulsion system and connecting a corresponding, functional electrically driven propulsion system. The modular design of the electrically driven propulsion system improves the flexibility and speed at which a replacement part may be provided. For example, multiple electrically driven propulsion systems may be kept in a central storage facility. In case of a failure of an electrically driven propulsion system installed on a boat, one of the electrically driven propulsion systems may be shipped from the central storage facility to a location of the boat and replace the electrically driven propulsion systems with the failure. The overall duration of the process from receiving the reporting of the failure at the central storage facility to finishing the replacement of the electrically driven propulsion systems 100 on the boat may be short, for example less than 36 hours.

[0211] In this process, no mechanical adjustment of the replacement electrically driven propulsion systems may be requirement. A software integration of the replacement electrically driven propulsion systems may be performed through an over-the-air-update.

[0212] The method may further comprise, prior to the moving the motor section through the opening, mounting a connecting frame to the hull with the opening; the fixing the electrically driven propulsion system to the hull with the opening may comprise fixing the electrically driven propulsion system to the connecting frame; and the forming the waterproof connection between the hull and the common waterproof housing may comprise forming the waterproof connection between the connecting frame and the common waterproof housing.

[0213] The common waterproof housing may comprise a ring-shaped seal face, and the forming the waterproof connection between the hull and the common waterproof housing may comprise forming the waterproof connection between the ring-shaped seal face and the hull such that the ring-shaped seal face encircles the opening.

[0214] The electrically driven propulsion system may further comprise fixing means in direct physical contact with the ring-shaped seal face, and the fixing the electrically driven propulsion system to the hull with the opening may comprise coupling the fixing means to the hull with the opening, in particular to through holes of the hull with the opening.

[0215] The forming the waterproof connection between the hull with the opening and the common waterproof housing comprise closing the opening of the hull, in particular in a waterproof way.

[0216] The fixing the electrically driven propulsion system to the hull with the opening may comprise fixing the electrically driven propulsion system as a surface drive to the hull with the opening.

[0217] A surface drive may provide a high efficiency, i.e., a strong forward propulsion per electric power supplied the propulsion system, for example through the power inlet. This may improve the efficiency of an electric watercraft comprising the electrically driven propulsion system. In particular, a propeller coupling, a propeller shaft or a propeller of a surface drive may have an optimum revolution speed similar to a revolution speed of an electric motor such as an axial flux motor. Installing the electrically driven propulsion system as a surface drive may therefore support the use of a transmission with a small gear ratio, which may improve the energy efficiency and thus the range further.

[0218] The opening of the hull may be adapted to be at a vertical position of a water line of the hull or of a watercraft comprising the hull.

[0219] The water line may refer to a static water line, in particular to a water line of the hull or the watercraft when the hull or the watercraft does essentially not move.

[0220] The water line may refer to a planing-speed water line, in particular to a water line of the hull or the watercraft when the hull or the watercraft moves forward at a planing speed and/or at a speed of 30 knots. The planing speed may refer to a speed of the hull or the watercraft, at which the hull or the watercraft is adapted to essentially lift above the static water line.

[0221] An upper edge of the opening of the hull may be arranged at a vertical position corresponding to the static water line of the hull or the watercraft.

[0222] A lower edge of the opening of the hull may be arranged at a vertical position corresponding to the planing-speed water line of the hull or the watercraft.

[0223] The fixing the electrically driven propulsion system to the hull with the opening may comprise generating the opening of the hull.

[0224] The fixing the electrically driven propulsion system to the hull with the opening may be performed from the second side. Alternatively, or in addition, the fixing the electrically driven propulsion system to the hull with the opening may comprise connecting the fixing means to the detachable connection elements through the through holes of the first ring-shaped element.

[0225] The method may comprise fixing the electrically driven propulsion system to the hull at a vertical position corresponding to a water line of the hull or of the watercraft, in particular, such that an upper end of the propeller coupling or the propeller is at most 30 cm below the static water line, in particular at most 20 cm below the static water line or at most 10 cm below the static water line.

[0226] Alternatively, or in addition, the method may comprise fixing the electrically driven propulsion system to the hull such that a first part of the propeller coupling or the propeller is below a planing-speed water line of a watercraft comprising the hull, and a remaining part of the propeller coupling or the propeller is above the planing-speed water line of the watercraft.

[0227] The electrically driven propulsion system of the method may be formed with any or all of the features described above in the context of the electrically driven propulsion system.

[0228] The electrically driven propulsion system may further comprise a propeller mounted to the propeller coupling.

BRIEF DESCRIPTION OF THE FIGURES

[0229] The techniques of the present disclosure and the advantages associated therewith will be best apparent from a description of exemplary embodiments in accordance with the accompanying drawings, in which:

Fig. 1a

shows an electrically driven propulsion system according to an embodiment;

Fig. 1b

shows an application example of the electrically driven propulsion system;

Fig. 1c

shows another application example of the electrically driven propulsion system;

Fig. 1d

shows another application example of the electrically driven propulsion system;

Fig. 2

shows an electrically driven propulsion system according to another embodiment;

Fig. 3

shows an electrically driven propulsion system according to another embodiment;

Fig. 4

shows an electrically driven propulsion system according to another embodiment;

Fig. 5a

shows an electrically driven propulsion system with a connecting from according to an embodiment;

Fig. 5b

shows an electrically driven propulsion system with a connecting from according to another embodiment;

Fig. 6

shows an electrically driven propulsion system according to another embodiment;

Fig. 7a

shows an electrically driven propulsion system according to another embodiment;

Fig. 7b

shows the electrically driven propulsion system according to the embodiment of Fig. 7a;

Fig. 7c

shows the electrically driven propulsion system according to the embodiment of Fig. 7a, Fig. 7b;

Fig. 7d

shows a propeller for surface drive;

Fig. 7e

shows an electrically driven propulsion system according to another embodiment;

Fig. 8a

shows an electrically driven propulsion system according to another embodiment;

Fig. 8b

shows the electrically driven propulsion system according to the embodiment of Fig. 8a;

Fig. 8c

shows an electric motor according to an embodiment;

8d

shows an electric motor according to a different embodiment;

Fig. 9a

shows a method for connecting an electrically driven propulsion system to a hull according to an embodiment;

Fig. 9b

shows a method for connecting an electrically driven propulsion system to a hull according to another embodiment;

Fig. 9c

shows a method for connecting an electrically driven propulsion system to a hull according to another embodiment;

Fig. 10a

shows a side view of a connecting frame;

Fig. 10b

shows a front view of the connecting frame; and

Fig. 11

shows a hull prepared for connecting the electrically driven propulsion system as a surface drive.

DETAILED DESCRIPTION OF EMBODIMENTS

[0230] Fig. 1a shows an electrically driven propulsion system 100 according to an embodiment. The propulsion system 100 forms a monolithic unit comprising the electric motor 102 and a transmission 106 coupled to the electric motor 102, as well as a pulse inverter 118 providing an electrical supply power to the electric motor 102. A corresponding electrically driven propulsion system 100 is also referred to as an integrated propulsion system 100.

[0231] The transmission 106 comprises an encased section 106e inside the housing 108, as well as an external section 106x outside of the waterproof housing 108 at its far end from the motor 102. The transmission 106 rotationally couples the external section 106x to the electric motor 102 via the encase section 106e, hence transferring a rotational movement of the electric motor 102 out of the housing 108. It comprises any component required for this purpose. According to the example depicted in Fig. 1a, this is a (rotary) shaft 106.

[0232] The electrically driven propulsion system 100 further comprises a thrust bearing 164. When the electric motor 102 is driven with electric output power from the pulse inverter 118 to rotate a rotary shaft 106 of the transmission, this movement causes a propeller of the watercraft to rotate. The propeller is coupled to the rotary shaft 106 directly or via a drive provided by the watercraft.

[0233] The rotation of the propeller results in a forward force 166, or a propulsion 166, respectively, of the rotary shaft 106 along its axial direction 168. The thrust bearing 164 transfers this force 166 onto the housing, thereby generating a propulsion 166' of the housing and ultimately of the watercraft. Therefore, the thrust bearing 164 is connected to the rotary shaft 106 and to the housing to couple the two rotationally, i. e. its inner ring is rigidly connected to the rotary shaft 106 and its outer ring of the bearing is rigidly connected to the housing 108.

[0234] The monolithic design of the electrically driven propulsion system 100 allows for equipping a watercraft with the electrically driven propulsion system 100 in a few simple steps. The components of the system 100, i. e. the electric motor 102, the inverter 118, the transmission 106, and the thrust bearing 164 are fully optimized with respect to each other. Therefore, by equipping his or her watercraft with the electrically driven propulsion system 100, a user installs a high-power, high-efficiency system for an optimized range of the watercraft. No further selection of additional components and no corresponding expert knowledge is required, and the risk of losing efficiency or range is eliminated.

[0235] Moreover, the integrated (monolithic) design allows for replacing it as a whole quickly and easily in case of a failure of one of the components, i. e. with all essential components mounted in their respective locations for operation. The defective component may be diagnosed and replaced later, for example in a dedicated facility, as the watercraft with the replaced propulsion system is already back in operation. The monolithic unit 100 may be mechanically sealed or locked to prevent a user from opening it and to permit access only in a controlled environment, such as a maintenance and repair facility.

[0236] Any need to disassemble or assemble any component of the electrically driven propulsion system 100 at the location of the watercraft is avoided. The installation or replacement may reliably be performed by a person without specialized skills and knowledge of any of the components of the electrically driven propulsion system 100.

[0237] In a preferred embodiment, the electric motor 102 is an axial flux motor. Axial flux motors are particularly light-weight and compact, for example compared to radial flux motors. Therefore, the use of an axial flux motor renders the installation and exchange of the integrated propulsion system 100 as a hole way more manageable and secure. The axial flux motors 102 operate at relatively low revolution speeds of 1500 to 3500 rounds per minute, similar to the optimal revolution speed of the propeller, for example for a surface drive. Consequently, the integrated propulsion system 100 may in principle be formed without any gearing mechanism or ratio between the electric motor 102 and its external section 106x.

[0238] Depending on the embodiment, it provides a mechanical power of 100 kW or 200 kW. The axial flux motor 102 adapted to provide the mechanical power of 100 kW has a weight of 25 kg, and the axial flux motor 102 adapted to provide the mechanical power of 200 kW has a weight of 50 kg.

[0239] The common waterproof housing 108 protects the components it surrounds from external influences, such as seawater or weather conditions, in particular on the watercraft. On the other hand, the housing 108 protects a user from electrical hazards related to the electric motor 102, in particular on the inside 216 of the hull 202. For this purpose, the housing 108 comprises a layer of insulating material or a layer of grounded, conductive material.

[0240] Moreover, the common waterproof housing 108 provides an acoustic shielding for the motor and the enclosed section 106e of the transmission, and reduces noise on board emerging from those components.

[0241] The integrated propulsion system 100 is compatible with various boat layouts, and optimized embodiments for a number of layouts will be presented throughout this description. Fig. 1b, Fig. 1c, and Fig. 1d illustrate application examples.

[0242] According to Fig. 1b, the integrated propulsion system 100 is installed in a watercraft with a fixed shaft. The transmission 106 of the integrated propulsion system 100 connects directly to the fixed shaft, and is optimized for this purpose with a planetary gearing 106b providing a gear ratio optimized for the watercraft. The system comes as a kit with a support structure 128 to adjust the integrated propulsion system 100 to the inclination angle of the fixed shaft.

[0243] According to Fig. 1c, the integrated propulsion system 100 is installed as a component of a sail drive for a sailing boat. The shaft 106 of the propulsion system 100 connects to an input gear of a spur gear of the sail drive. There, the electrically driven propulsion system 100 may replace a combustion engine to reduce the noise level on board and improve the sustainability of the sailing boat.

[0244] According to Fig. id, the integrated propulsion system 100 is installed at the transom 202 of the watercraft, preferably as a surface drive. The propulsion system 100 pierces through the transom 202 and is arranged part inside, part outside of the watercraft.

[0245] The external section 106e of the transmission comprises a propeller coupling 106c for mounting a propeller. The system 100 therefore includes any mechanical component required to couple the propeller shaft 106e, or the propeller coupling 106c, respectively (and ultimately a propeller mounted to the coupling 106c) rotationally to the electric motor 102. In the following, such a system 100 is referred to a fully mechanically integrated.

[0246] This option is particularly favorable for high-speed watercraft, for example with a cruising speed of 20 to 50 kn. The system comes as a kit with a support structure 128 to adjust the integrated propulsion system 100 to the optimum inclination angle of the surface drive.

[0247] Fig. 2 shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 2 is similar to the one of Fig. 1a. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of Fig. 2 is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0248] The integrated propulsion system comprises two noise/vibration sensors 152, which detect a sound level or a sound pattern of the system 100, generate a corresponding electronic signal, and send it through a signal line 154 out of the system and to a signal processor 156 of the system.

[0249] The signal processor 156 or an external processor connected to the signal line 154 detects changes in the sound level or sound pattern of the system 100.

[0250] When a permanent change is detected, it may be an indication for an upcoming failure, for example you to an increased friction between elements of the system 100. The processor 156 generates an electronic report message, indicating that the integrated propulsion system 100 may need to be replaced.

[0251] When a sudden change in the sound level or the sound pattern of the system 100 is detected and exceeds a critical level, this may be an indication of a contact or a collision of the watercraft with an obstacle. The processor 156 generates an electronic warning message, which may for example trigger an alarm or a transmission of an emergency message, for example via a long-distance network.

[0252] The signal line 154 is shown only for one of the sensors 152, but is equally formed for the second one.

[0253] Two signal lines 154 are shown, one leading to the processor 156 and one leading out of the housing 108, but according to different embodiments, only one of the two is formed.

[0254] One of the noise/vibration sensors 152 is arranged in direct contact with the electric motor 102, to specifically monitor changes in the sound level or sound pattern of the electric motor. The other noise/vibration sensor 152 is arranged at a far end of the housing 108 from the motor 102 in direct contact with the housing. In embodiments, wherein the far end of the housing 108 is in contact with a surrounding body of water, such as the embodiment of Fig. id, this noise/vibration sensor 152 monitors body sound transferred by the water. Additional noise/vibration sensors 152 may be provided, for example in the vicinity or in direct contact with individual components of the transmission 106, or only one of the noise/vibration sensors 152 maybe present.

[0255] Fig. 3 shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 3 is similar to the one of Fig. 1a and Fig. 2. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of Fig. 3 is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0256] The transmission 106 of the electrically driven propulsion system 100 of Fig. 3 comprises a planetary gearing 106b to implement a gear ratio between a second (rotary) shaft 106c and a first (rotary) shaft 106a of the transmission. The first shaft 106 a is coupled to the electric motor 102 and forms a motor shaft 106a. The second shaft 106c may carry a propeller 104 or propeller coupling 106c like in the example of Fig. 1d or be connected to an external transmission like in the embodiments of Fig. 1b, Fig. 1c.

[0257] The transmission serves to match the highest-efficiency rotation speed of the second shaft 106c to the highest-efficiency rotation speed of the propeller 104 or the external transmission. The highest efficiency rotation speed of the second shaft 106c refers to the rotation speed of the second shaft 106c, at which the overall electrical power to mechanical power conversion efficiency of the integrated propulsion system 100 is maximum. Mechanical power refers to the mechanical power generated at the second shaft 106c due to its rotational movement. The electrical power refers to an input power provided to the pulse inverter 118 via a power inlet of the pulse inverter from an external current source, such as a battery.

[0258] The electrically driven propulsion system 100 of Fig. 3 further comprises a heat exchanger 122.

[0259] The heat exchanger 122 is thermally coupled via its secondary side 126 to any component of the system 100 requiring cooling, in particular the electric motor 102, but also to the pulse inverter 118, the transmission 106 or a thrust bearing (not shown) as required. The secondary side 126 of the heat exchanger comprises cooling channels 126c filled with a coolant and connecting the heat exchanger 122 to the respective components. The coolant has an optimized composition comprises a sufficient amount of glycol to prevent freezing in any relevant situation. The heat exchanger further comprises a coolant pump (not shown) to generate a flow of the coolant in the channels 126c of its secondary side 126.

[0260] The secondary side 126 of the heat exchanger 122 further provides two openings 1260, namely an outlet and an inlet for coolant to an external device, such as a battery or a cabin. If not required, the openings 1260 are bridged.

[0261] A primary side 124 of the heat exchanger 122 connects to openings 1240 outside the housing 108. In operation, the openings 1240 are either directly exposed to a body of water surrounding the watercraft and take up water as a coolant therefrom. Alternatively, the openings 1240 are connected to the surrounding body of water using additional external tubing, for example through a feedthrough in the hull of the watercraft. A coolant pump (not shown) ensures a sufficient flow of water at the primary side 124 of the heat exchanger 122.

[0262] Fig. 4 shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 4 is similar to the one of Fig. 1a, Fig. 2, and Fi. 3. Similar elements are indicated by same reference numerals and will not be described again.

[0263] The integrated propulsion system 100 of Fig. 4 is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0264] According to the embodiment of Fig. 4, the housing 108 of the electrically driven propulsion system 100 comprises a fore (motor) section 108a wherein the motor is arranged and an aft (transmission) section 108b wherein the encased section 106e of the transmission 106 is arranged.

[0265] The transmission section 108b has a larger width w1 than the motor section w2. The widths w1, w2 refer to widths of the respective cross sections of the housing 108, for example in the planes 160, 162 perpendicular to the longitudinal direction 158 of the system 100 intersecting the housing 108 at different positions along the longitudinal direction 158.

[0266] The embodiment of Fig. 4 is preferably mounted to a transom 202 of a watercraft. The fore (motor) section 108a is located directly fore of the aft (transmission) section 108b and its cross section is completely comprised in a fore projection of the aft (transmission) section 108b. Therefore, when the integrated propulsion system 100 is inserted into the transom 202 through an opening 204, the motor section 108a is taken up completely by the watercraft, whereas the transmission section 108b serves as a stopper to define the depth to which the integrated propulsion system 100 is introduced. A portion of the transmission section 108b remains outside of the watercraft.

[0267] A seal (not shown) between the housing 108 and the hull 202 ensures a waterproof connection.

[0268] Thus, an ideal geometry is realized for a surface drive, with the propeller coupling 106c aft of the transom 202 and the entire hull. The surface drive is particularly energy efficient for high speeds exceeding 20 kn, making the integrated propulsion system 100 attractive for high-speed, electrically driven watercraft. The high efficiency of the surface drive helps to make best possible use of the charge capacity of the battery and to improve the range of the high-speed, electrically driven watercraft.

[0269] To further optimize the integrated propulsion system 100 of Fig. 4 for this purpose, it is designed with a linear arrangement along its longitudinal direction 158, which pierces through the opening 204 of the hull 202. In other words, the electric motor 102, the shaft 106 and the propeller coupling 106p are all intersected by a single line extending along the longitudinal direction 158. In this embodiment, the longitudinal direction of the integrated propulsion system coincides with the axis of the shaft 106 coupled to the motor 102, and with a horizontal axis x perpendicular to a vertical axis z and a second horizontal axis y.

[0270] Fig. 5a shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 5a is similar to the one of Fig. 1a, Fig. 2, Fig. 3, and Fi. 4. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of Fig. 5a is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0271] While the integrated propulsion system 100 of the embodiment of Fig. 4 is shown as mounted directly to the hull 202, a connecting frame 302 is provided between the integrated propulsion system 100 of Fig. 5a and the hull 202. The integrated propulsion system 100 is mounted to the connecting frame 302.

[0272] The connecting frame 302 comprises a first ring-shaped element 308 on the inside 216 of the hull 202 and second ring-shaped element 308 on the outside 210 of the hull 202.

[0273] Threaded holes 318 of the second ring-shaped element 308 and slightly larger through holes 316 of the first ring-shaped element 306 facilitate a connection between the two. Through holes similar to the ones 316 of the first ring-shaped element 306 are formed in the hull 202. Connecting the ring-shaped elements 306, 308 with bolts 322 clamps them to the hull 202, and sealing rings (not shown) between the ring-shaped elements 306, 308 and the hull 202 establish a waterproof connection between the connecting frame 302, 306, 308 and the hull 202.

[0274] The integrated propulsion system 100 of Fig. 5a comprises through holes 110a formed on a ring-shaped sealing face 110.

[0275] The ring-shaped elements 306, 308 further comprise through holes 320a and threaded holes 320b, which serve to establish a detachable connection. The arrangements of both the through holes 320a and the threaded holes 320b correspond to the arrangement of the through holes 110a of the ring-shaped sealing face 110. Therefore, inserting bolts 222 through the through holes 110a and the trough holes 320a and tightening them to the threaded holes 320b connects the integrated propulsion system 100 to the hull 202. A sealing ring (not shown) between the sealing face 110 and the second ring-shaped elements 306 ensures a waterproof connection between the two.

[0276] A corresponding connection using a connecting frame 302 is optionally and preferably also applied in any of the other embodiments. It ensures a reliably detachable connection between the electrically driven propulsion system 100 and the watercraft, without any risk of touching or damaging the watercraft, in particular its hull 204, in the process of attach or detaching the electrically driven propulsion system 100 from or to the watercraft.

[0277] The connecting frame 302 permits to install and remove the integrated propulsion system 100 from outside of the watercraft using a detachable connection, thus avoiding any need to work inside the typically narrow inside space of the watercraft, or its hull, respectively.

[0278] According to the embodiment of Fig. 5a, the thrust bearing 164 provides a waterproof connection between the housing 108 and the rotary shaft 106, and therefore forms a section of the common waterproof housing. In other words, a section of the thrust bearing 164 is arranged in a wall of the waterproof housing 108.

[0279] Fig. 5b shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 5b is similar to the one of Fig. 1a, Fig. 2, Fig. 3, Fig. 4, and Fig. 5a. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of Fig. 5b is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0280] According to the embodiment of Fig. 5b, a connecting system is established by combining the connecting frame 302 with a support element 128 connected to the frame 128.

[0281] The support element 128 comprises a support arm 128a which is connected to and extends away from the connecting frame 302. It further comprises a support column 128b, which is connected to and extends away from the support arm 128 in the vertical direction z. The support column is adapted to support the integrated propulsion system 100 at its housing 108.

[0282] The support element 128 reduces vibrations of the housing 108, of the integrated propulsion system 100, and in particular of the electric motor 102. This reduces undesired noise emerging from the unit and improves its reliability and lifetime. Moreover, the length of the support arm 128a is preselected according to the length of the portion of the integrated propulsion system 100 to be inserted into the hull 202, such that the support arm 128a helps to define a mounting depth of the integrated propulsion system 100 in the hull 202. The support element 128 therefore renders the mounting of the electrically driven propulsion system 100 more simple and reliable.

[0283] The support arm 128a extend away from the connecting frame 302, more specifically from the lower edge of the opening 304 of the connecting frame 302. Therefore, when the propulsion system 100 is inserted into the watercraft through the transom 202 with the opening 204 along the direction x, the support arm 128a serves to guide the movement of the propulsion system 100 and restrains it along both the vertical direction z and a horizontal sidewards direction y. Therefore, the system 100 may be inserted into the watercraft with a minimum of force, in particular with much less force than would be required to stabilize the position of the system 100 without the guiding arm 128 (e. g. along the vertical direction z). Moreover, the support arm 128a may guide the movement of the system 100 along a straight trajectory x and avoid unwanted movements along the sidewards direction y.

[0284] The integrated propulsion system 100 according to the embodiment of Fig 5b further comprises anti-mechanical-shock elements (not shown) to mechanically insulate the electric motor 102 from the housing 108. The anti-mechanical-shock elements are arranged inside the housing 108 and between the housing 108 and the motor 102. The comprise support elements made from a material with a high internal friction, for example comprising viton. They further improve the noise level, reliability, and lifetime of the electric motor 102. Corresponding anti-mechanical-shock elements are optionally and preferably applied in any of the other embodiments.

[0285] Fig. 6 shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 6 is similar to the one of Fig. 1a, Fig. 2, Fig. 3, Fig. 4, Fig. 5a and Fig. 5b. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of Fig. 6 is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0286] The electrically driven propulsion system 100 of Fig. 6 comprises a gearing mechanism 106b similar to the one described in the context of the embodiment of Fig. 3. However, as opposed to the gearing mechanism 106b of Fig. 3, which provides a coupling between the first shaft and the second shaft along a continuous line, the gearing mechanism 106b of Fig. 6 provides an offset 130, or a displacement 130, respectively, between the first shaft and the second shaft along a direction perpendicular to their respective axes.

[0287] The offset 130 in the embodiment of Fig. 6 is implemented by using a spur gear in the gearing mechanism 106b, alone or in combination with the planetary gear described above.

[0288] The offset 130 improves the design flexibility of the system 100. In particular, it helps to lower the propeller coupling 106c to the water line of the watercraft.

[0289] The electrically driven propulsion system 100 of Fig. 6 further comprises a noise/vibration sensor 152 arranged outside 210 of the watercraft and below the propeller shaft 106c and the propeller coupling 106p, and therefore below the water line of the watercraft. As described above, this arrangement of the noise/vibration sensor 152 allows for capturing body sound from a body of water surrounding the watercraft.

[0290] Fig. 7a, Fig. 7b, and Fig. 7c show an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 7a, Fig. 7b, and Fig. 7c is similar to the one of Fig. 1a, Fig. 2, Fig. 3, Fig. 4, Fig. 5a, Fig. 5b and Fig. 6. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of Fig. 7a, Fig. 7b, and Fig. 7c is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0291] The embodiment of Fig. 7a, Fig. 7b, and Fig. 7c uses two axial flux motors 102. An electric supply power is provided to the axial flux motors 102 by the pulse inverter 118. The pulse inverter 118 receives its input power from a power inlet 120 fed through the waterproof housing 108 in a waterproof manner to connect a battery outside of the housing 108. When the electrically driven propulsion system 100 is mounted to the watercraft, the power inlet 120 is located inside the watercraft and accessible there.

[0292] A watercraft battery providing a DC voltage may be connected to the power inlet 120. The pulse inverter 118 generates the AC electrical supply current for the electric motors 102 from the DC voltage. The pulse inverter 118 is also coupled to a data line 116 to receive control commands and software updates, such as updates of parameters related to the operation of the pulse inverter 118.

[0293] Axial flux motors may be constructed with higher power densities than conventional engines and electric motors, such as radial flux motors. As the revolution speed of the axial flux motors 102 is similar to the optimal revolution speed of the propeller 104, the gearbox 106b may have a small gear ratio, such as a gear ratio of 1.18, and thus a higher efficiency than a gearbox with a high gear ratio typically applied in combination with an engine or an electric motor with a higher revolution speed.

[0294] The common waterproof housing 108 provides a motor section 108a for the electric motor on a first side 216 of a sealing face 110, and a transmission section 108b on the opposite, second side 210 of the sealing face 110. Threaded holes 110a are formed on the sealing face 110. The transmission section 108b contains a section of the propeller shaft 106c and a section of the gearbox 106b. Other parts of the transmission 106, namely the motor shaft 106a and most of the gearbox 106b, are placed inside the motor section 108b.

[0295] Consequently, when the electrically driven propulsion system 100 is connected with its sealing face 110 to a hull 202, the electric motors 102 are located inside of the hull 202 where they are protected from environmental influences and acoustically shielded to minimize a noise level on board and on deck.

[0296] The electrically driven propulsion system 100 also comprises an electromechanical rudder actuator 112 arranged in the common waterproof housing 108. The electromechanical rudder actuator 112 actuates rudders 114b, 114s arranged portside and starboard of the propeller 104. Therefore, the electromechanical rudder actuator 112 receives an electrical signal from a data line 116. The data line 116 ends in a data input connector 116c.

[0297] The data input connector 116c is arranged on the common waterproof housing 108 to provide access from outside of the common waterproof housing 108. The data input connector 116c is sealed against the common waterproof housing 108 in a waterproof way. The data line 116 is also used for software update, such as updates of parameters related to the operation of the electromechanical rudder actuator 112.

[0298] The electrically driven propulsion system according to the embodiment of Fig. 7a, Fig. 7b, and Fig. 7c further comprises a propeller 104 optimized for a surface drive. Fig. 7c and Fig. 7d illustrate the design of the propeller 104 designed for the surface drive.

[0299] Referring to Fig. 7c, which shows a stern projection of the integrated propulsion system 100, the propeller 100 comprises a radial sections 144 extending away from the center of the propeller 104, which is mounted to the propeller coupling 106p.

[0300] An essentially flat section 146 extends away from the radial section 144 along the azimuthal direction of the propeller 104 with an angle β of essentially 90° between the radial section 144 and an outer edge of the essentially flat section 146e.

[0301] Referring to Fig. 7d, which shows a side view of the integrated propulsion system 100, the essentially flat section 146, or its outer edge 146e, respectively, are formed at an angle γ with respect to the longitudinal direction of the propeller 104. The angle γ is defined by the pitch 150 and the diameter 148 of the propeller 104. In particular, the tangent of the angle γ is the diameter 148 over half the pitch 150.

[0302] Fig. 7e shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 7e is similar to the one of Fig. 7a, Fig. 7b, and Fig. 7c. Similar elements are indicated by same reference numerals and will not be described again.

[0303] As compared to the embodiment of Fig. 7a, Fig. 7b, and Fig. 7c, the embodiment of Fig. 7e comprises a single electric motor of 102 instead of two electric motors. Instead of the second electric motor, the embodiment of Fig. 7e comprises a motor upgrade space 138 to receive an additional electric motor if required.

[0304] Such an embodiment improves the design flexibility of the integrated propulsion system 100, making use of the applied axial flux motor 102. The geometry of the axial flux motor 102 beneficially permits to add or remove an electric motor and thus improves the design flexibility and the modularity of the electrically driven propulsion system 100.

[0305] All other components, in particular the pulse inverter 118 and the transmission 106, are provided for with specification in terms of electrical and mechanical power corresponding to the integrated propulsion system 100 with the maximum number of electric motors 102.

[0306] According to the embodiment depicted in Fig. 7e, the motor section 108a has space for two electric motors. It comprises one electric motor 102 and an upgrade space 138 for one additional electric motor. However, according to alternative embodiments, the motor section 108a provides space for two, four or more electric motors 102. The motor section 108a may comprise a single electric motor 102, and additional electric motors maybe added in a modular way as needed to increase the overall maximum power of the electrically driven propulsion system 100. For maximum flexibility, any of the electric motors is preferably exchangeable with any other of the electric motors 102, i. e. the electric motors and the additional electric motors have similar physical dimensions and electrical characteristics.

[0307] Fig. 8a and Fig. 8b show an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of Fig. 8a and Fig. 8b is similar to the one of Fig. 7a, Fig. 7b, and Fig. 7c. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of Fig. 8a and Fig. 8b is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0308] The embodiment of Fig. 8a and Fig. 8b further comprises an electromechanical rudder actuator 112, which receives signals from the data input connector 116c. The rudder actuator 112 actuates a central tiller arm 134 in response to the received signals. The movement of the central tiller arm 134 actuates a starboard tiller arm 134s and a portside tiller arm (not shown), thereby actuating a starboard rudder 114s and a portside rudder (not shown).

[0309] According to a corresponding embodiment, the electrically driven propulsion system 100 does not only integrate the propulsion as such, but also the steering of the watercraft. The entire unit is provided as a monolithic and fully optimized system. Thus, it renders installing the electrically driven propulsion system 100 as easy as possible, for example as a surface drive.

[0310] As compared to the embodiment of Fig. 7a, Fig. 7b, and Fig. 7c, the embodiment of Fig. 8a and Fig. 8b comprises a single electric motor 102, i. e. an electric motor 102 with a single housing. Nevertheless, a motor upgrade is possible, namely making use of an upgrade space in the housing of the electric motor 102.

[0311] Figure 8c and Fig. 8d are detailed views of embodiments of electric motors 102 corresponding to the one of Fig. 8a and Fig. 8b.

[0312] The electric motor 102 of Fig. 8c comprises a stator 140 with windings of electric lines to drive the currents with windings and generate an electric field at the stator 140. The electric motor 102 further comprises rotors 142 with permanent magnets, arranged rotatably on an axis (not shown).

[0313] The electric motor 102 of Fig. 8d is similar to the electric motor of Fig. 8c. However, the electric motor of Fig. 8d comprises only one rotor 142 and a motor upgrade space 138 instead of the second motor. The rotor upgrade space 142 and hence the electric motor 102 may be upgraded with the second rotor 142.

[0314] According to the embodiments of Fig. 8c and Fig. 8d, the electric motor 102 provides space for two rotors 102, and two or one rotor(s) is (are) provided. However, according to alternative embodiments, the electric motor 102 is designed for three, four, five, six seven eight, or more rotors 142. It may initially comprise one, two, three, four, or more rotors 142.

[0315] According to a different embodiment (not shown), the electrically driven propulsion system comprises a motor space 108a for a plurality of motors 102, such as in Fig. 7a, Fig. 7e. Each single motor may have a modular design with a plurality of motors, as described in the context of Fig. 8c, Fig. 8d.

[0316] Fig. 9a and Fig. 9b illustrate a method 200 for connecting the electrically driven propulsion system 100 to a hull 202 with an opening 204, more specifically to the transom 202 of the hull. The electrically driven propulsion system 100 may be connected directly to the transom 202 with the opening 204. Optionally, a connecting frame 302 with an opening 304 matched to the opening 204 in the transom 202 may be mounted to the transom 202 prior to connecting the electrically driven propulsion system 100.

[0317] The connecting frame 302 allows for a quick, reliable and safe exchange of the electrically driven propulsion system 100 as a whole. In particular, the risk of damaging the hull 202 is reduced, as any physical contact between moving components and the hull 202 is prevented.

[0318] The connecting frame 302 according to the embodiment of Fig. 9a and Fig. 9b comprises a first ring-shaped element 306 mounted to the outside 210 of the watercraft, a second ring-shaped element 308 mounted to the inside 216 of the watercraft, and a seal 312 between a sealing face 310 of the first ring-shaped element 306 on the one side and the second ring-shaped element 308 as well as the transom 202 on the other.

[0319] In a first step, the electrically driven propulsion system 100 is placed on the outside 210 of the watercraft. A seal 212 is provided between the sealing face 110 and the hull 202.

[0320] In a second step 214, the motor section 108a of the electrically driven propulsion system 100 with the electric motors 102 is moved 214 through the opening 204 in the transom 202, and, if installed, through the opening 304 of the connecting frame 302, to the inside 216 of the watercraft. The propeller coupling 106p and the propeller 104 remain on the outside 210 of the watercraft.

[0321] In a third step 218a, 218b, the electrically driven propulsion system 100 is fixed 218 to the transom 202 and, if installed, to the connecting frame 302. To this end, through holes 110a, 220, 320a may be provided in the (sealing face 100 of the) propulsion system 100, transom 202 and the connecting frame 302. Via these through holes, bolts 222 are inserted 218a and screwed 218b into the threaded holes 320b in the (second ring-shaped element 308 of the) connecting frame 302 to implement the fixing 218. In embodiments without a connecting frame 302 (not shown), nuts on the inside 216 of the watercraft provide the threaded holes 320b.

[0322] In a fourth step, a waterproof connection is formed between the common waterproof housing 108 of the electrically driven propulsion system 100 and the transom 202 or, if installed, the connecting frame 302. Therefore, the bolts 222 are screwed 218b into the threaded holes 320a with a defined torque and with the seal 212 between the sealing face 110 and the transom 202 or the connecting frame 302, respectively.

[0323] Thus, the electrically driven propulsion system 100 may be connected to a watercraft in a few quick and simple steps. The electrically driven propulsion system 100 may be disconnected from the watercraft just as easily and quickly by performing the reverse of each step and in a reversed order of the steps. In case of a failure of the electrically driven propulsion system 100, for example related to the failure of one of the electric motors 102 or of the transmission 106, the electrically driven propulsion system 100 maybe changed as a whole by disconnecting the defective electrically driven propulsion system 100 and connecting a corresponding replacement part. The modular design of the electrically driven propulsion system 100 allows for providing the replacement part more quickly and efficiently.

[0324] For example, multiple electrically driven propulsion systems 100 may be kept in a central storage facility. In case of a failure of an electrically driven propulsion system 100 installed on a boat somewhere in the world, one of the multiple electrically driven propulsion systems 100 may be just slightly modified in the central storage facility for the use as a replacement part for the defective system, for example by installing a suitable number of electric motors 102. Subsequently, the replacement part may be shipped to a location of the boat and replace the electrically driven propulsion system 100 with the failure. The overall duration of the process from learning of the failure at the central storage facility to finishing the replacement of the electrically driven propulsion systems 100 on the boat may be short, for example less than 36 hours.

[0325] Fig. 9c summarizes the most important steps of the method 200.

[0326] In step 230, the electrically driven propulsion system 100 is provided as a whole on a second side 210 of the opening 204 of the hull 202.

[0327] In step 214, at least a section of the motor section 108a is moved, while keeping the electrically driven propulsion system 100 assembled as a whole and while keeping the propeller coupling 106p on the second side 210, through the opening 204 to a first side 216 of the opening 204 opposite to the second side 210.

[0328] In step 218, the electrically driven propulsion system 100 is fixed 218a, 218b to the hull 202 with the opening 204.

[0329] In step 232, a waterproof connection is formed between the hull 202 and the common waterproof housing 108.

[0330] Fig. 10a and Fig. 10b depict a connecting frame 302 according to an embodiment. Similar to the embodiment depicted in Fig. 9a and Fig. 9b, the connecting frame 302 comprises the first ring-shaped element 306 and the second ring-shaped element 308 with essentially identical shapes in a plane perpendicular to the longitudinal direction. The first ring-shaped element 306 and the second ring-shaped element 308 each comprise an opening 304a, 304b with an essentially identical shape. Threaded holes 316 in the first ring-shaped element 306 and through holes 318 in the second ring-shaped element 308 with identical arrangements serve as connecting means to connect the first ring-shaped element 306 and the second ring-shaped element 308 to each other using bolts 322. The first ring-shaped element 306 further comprises through holes 320a with a predefined arrangement, and the second ring-shaped element 308 comprises threaded holes 320b with the same arrangement.

[0331] When the first ring-shaped element 306 and the second ring-shaped element 308 are connected to each other using the through holes 318, the threaded holes 316, and the bolts 322, the openings 304a, 304b overlap to form an opening 304 of the connecting frame 302. For mounting the connecting frame 302 to the transom 202, the opening 204 of the transom 202 is formed to match the shape of the openings 304, 304a, 304b.

[0332] A first sealing face 310 is formed on the first ring-shaped element 306 to form a waterproof connection between the connecting frame 302 and the hull. Therefore, the first ring-shaped element 306 and the second ring-shaped element 308 are connected to each other with the hull 202 between them and the seal 312 between the hull 202 and the first sealing face 310.

[0333] When the first ring-shaped element 306 and the second ring-shaped element 308 are connected using the connecting means 316, 318, the through holes 320a and the threaded holes 320b overlap due to their identical arrangements. This allows for connecting the electrically driven propulsion system 100 to the connecting frame 302 by pushing 218a the bolts 222 through the (through holes 110a of the sealing face 110 of the electrically driven propulsion system 100 and the) through holes 320a and screwing 218b them into the threaded holes 320b. The first ring-shaped element 306 further comprises a second sealing face 320 on a face pointing away from the first sealing face 310. When the electrically driven propulsion system 100 is connected to the connecting frame 302 with the seal 212 between the sealing face 110 of the electrically driven propulsion system 100 and the second sealing face 320 of the first ring-shaped element, a waterproof connection may be formed by screwing the bolts 222 into the threaded holes 320b with a defined torque.

[0334] Figure 11 illustrates a transom 202 of a hull 404 prepared for connecting the electrically driven propulsion system 100 as a surface drive. Therefore, an opening 204 is generated in the hull 404, typically in the transom 202 in the lower region of the transom 202.

[0335] An upper edge 402 of the opening is formed in a proximity of a static water line 400 of the hull 404, or of a watercraft comprising the hull 404, respectively. The static water line 400 refers to the water line when the hull or watercraft is not moving.

[0336] Watercraft with a surface drive typically has a high cruising speed and a hull adapted for planing. When the watercraft moves at/above its planning speed, the transom 202 lifts up, resulting in a lower water line 400'. The opening 204 is formed with its lower edge at the level of this lower, planing-speed water line 400'.

[0337] Through holes 220 are formed around the opening 204 in an arrangement matching the arrangement of the through holes 110a on the sealing face 100 of the electrically driven propulsion system 100, or of the through holes 320a or the threaded holes 320b of the connecting frame 302, respectively. The electrically driven propulsion system 100 may be connected to the hull 202 by pushing 218a bolts 222 through the through holes 110a and 220 (and the through holes 320a of a connecting frame 302, if installed) and screwing 218a them into the threaded holes 320b as described in the context of Fig. 9a, Fig. 9b, and Fig. 9c.

[0338] When the electrically driven propulsion system 100 is connected to the hull 404 according to this embodiment, the propeller coupling 106c, or the propeller 104, respectively, is arranged in the proximity of the planing-speed water line 400'. When a propeller 104 is installed, part of the propeller 104 is below the planing-speed water line 400', whereas the remaining part of the propeller 104 is above the planing-speed water line 400', as is characteristic of a surface drive. However, with respect to the resting watercraft, propeller coupling 106c and propeller 104 are in a vicinity of the static water line 400 below the static water line 400, typically up to 10 or 20 cm below the static water line 400.

[0339] A surface drive may provide a high efficiency, i. e. a strong forward propulsion per electric power supplied by the propulsion system, for example through the power inlet. This may improve the efficiency of an electric watercraft comprising the electrically driven propulsion system. In particular, a propeller coupling 106p, a propeller shaft 106c or a propeller 104 of a surface drive has an optimum revolution speed similar to a revolution speed of an electric motor 102 such as an axial flux motor 102. Installing the electrically driven propulsion system 100 as a surface drive therefore supports the use of a transmission 106 with a small gear ratio, which improves the energy efficiency and thus the range further.

[0340] The description of the embodiments and the Figures merely serve to illustrate the teachings of the present disclosure, but should not be understood to imply any limitation. The scope of the present disclosure is to be determined from the appended claims.

LIST OF REFERENCE SIGNS

[0341] 

100

electrically driven propulsion system

102

electric motors

104

propeller

106

transmission

106a

motor shaft

106b

gearbox

106c

propeller shaft

106e

encased section of transmission

106p

propeller coupling

106x

external section of transmission

108

common waterproof housing

108a

motor section

108b

transmission section

110

sealing face of the electrically driven propulsion system

110a

through holes on the sealing face of the electrically driven propulsion system

112

rudder actuator

114b

buckboard rudder

114s

starboard rudder

116

data line

116c

data input connector

118

pulse inverter

120

power inlet

122

heat exchanger

124

primary side of the heat exchanger

124c

primary coolant channel

1240

primary coolant opening

126

secondary side of the heat exchanger

126c

secondary coolant channel

1260

secondary coolant opening

128

support element

128a

support arm

128b

support column

130

offset along the vertical direction

132

thrust bearing

134

common tiller arm

134s

starboard tiller arm

136

portion of the encased section of the transmission outside the watercraft

138

motor upgrade space

140

stator

142

rotor

144

radial section of propeller

146

essentially flat section of propeller

146e

outer edge of flat section of propeller

β

Angle between outer edge and radial direction

γ

Angle between outer edge and center line

148

diameter of propeller

150

pitch of propeller

152

noise/vibration sensor

154

signal line of noise/vibration sensor

156

processor for analyzing signal of noise/vibration sensor

158 160

longitudinal direction plane perpendicular to longitudinal direction

162

second plane perpendicular to longitudinal direction

164

thrust bearing

166

force/propulsion along axial direction

166'

transferred force/propulsion

168

axial direction

200

method for connecting the electrically driven propulsion system to a hull with an opening

202

hull, transom

204

opening of hull, transom

210

second side, outside

212

seal for the sealing face of the electrically driven propulsion system

214

moving the motor section through the opening

216

first side, inside

218

fixing the electrically driven propulsion system to the hull, transom

218a

inserting bolts, pushing bolts through through holes

218b

screwing bolts into threaded holes

220

through holes of hull, transom

222

bolts for the threaded holes on the sealing face of the electrically driven propulsion system

230

providing the electrically driven propulsion system

232

forming a waterproof connection

302

connecting frame

304

opening of the connecting frame

304a

opening of first ring-shaped element

304b

opening of second ring-shaped element

306

first ring-shaped element

308

second ring-shaped element

310

first sealing face of the connecting frame

312

seal for the first sealing face of the connecting frame

316

threaded holes as first connecting means of the first ring-shaped element

318

through holes as a second connecting means of the second ring-shaped element

320a

through holes of first ring-shaped element

320b

threaded holes of second ring-shaped element

322

bolts for the threaded holes of the first ring-shaped element

400

static water line

400'

planing-speed water line

402

lower edge of opening of hull, transom

404

hull, watercraft for surface drive

Claims

1. An electrically driven propulsion system (100) for a watercraft, the electrically driven propulsion system (100) comprising:

an electric motor (102) adapted to provide a mechanical power of at least 50 kW;

a transmission (106) comprising a rotary shaft;

a pulse inverter (118) electrically coupled to the electric motor (102) and adapted to provide an electrical supply power of at least 50 kW to the electric motor (102);

a thrust bearing (164); and

a common waterproof housing (108);

wherein the electric motor (102), the pulse inverter (118) and an enclosed section (106e) of the transmission (106) are arranged inside the common waterproof housing (108);

wherein an external section (106x) of the transmission (106) is arranged outside of the common waterproof housing (108);

wherein the transmission (106) is adapted to rotationally couple the external section (106x) of the transmission (106) to the electric motor (102); and

wherein the thrust bearing (164) is mechanically coupled to the rotary shaft of said transmission (106) and to the common waterproof housing (108) and adapted to transfer a force (166, 166') applied to the transmission (106) along an axial direction (168) of said rotary shaft to the common waterproof housing (108).

2. The electrically driven propulsion system (100) according to claim 1, wherein the external section (106x) of the transmission (106) comprises a propeller coupling (106p) adapted for mounting a propeller (104) thereto.

3. The electrically driven propulsion system (100) according to claim 2,

wherein the watercraft comprises a hull (202) with an opening (204); and

wherein the electrically driven propulsion system (100) is adapted to be connected as a whole to the hull (202) with the opening (204), such that at least a section of the electric motor (102) is arranged on a first side (216) of the opening (204) and the propeller coupling (106p) and at least a portion of the common waterproof housing (108) are arranged on a second side (210) of the opening (204) opposite to the first side (216), and such that a waterproof connection forms between the common waterproof housing (108) and the hull (202).

4. The electrically driven propulsion system (100) according to any of the preceding claims, wherein the electric motor (102) is an axial flux motor.

5. The electrically driven propulsion system (100) according to any of the preceding claims, wherein the common waterproof housing (108) is adapted to provide a motor upgrade space (138) for a motor power upgrade component, and wherein the pulse inverter (118) is adapted to provide an electrical output power of at least two times the mechanical power that the electric motor (102) is adapted to provide.

6. The electrically driven propulsion system (100) according to any of the preceding claims, which further comprises a noise/vibration sensor (152) arranged inside the common waterproof housing (108) and adapted to detect a change in a sound or vibrational level of the electrically driven propulsion system (100).

7. The electrically driven propulsion system (100) according to claim 3 and optionally any of claims 4 to 6,

wherein the common waterproof housing (108) comprises a motor section (108a) in which the electric motor (102) is arranged; and

wherein a width (w1) of the portion of the common waterproof housing (108) adapted to be arranged on the second side of the opening exceeds a width (w2) of the motor section (108a).

8. The electrically driven propulsion system (100) according to claim 3 and optionally any of claims 3 to 7, wherein the common waterproof housing (108) comprises a ring-shaped seal face (110) adapted to encircle the opening (204) of the hull (202) and to provide the waterproof connection.

9. The electrically driven propulsion system (100) according to claim 2 and optionally any of claims 3 to 8, wherein the transmission (106) comprises a shaft (106c) comprising the propeller coupling (106p) and an axis, and wherein an orientation of the axis of the shaft (106c) is static.

10. The electrically driven propulsion system (100) according to claim 3 and optionally any of claims 3 to 9, further comprising a heat exchanger (122) arranged in the common waterproof housing (108), wherein a primary side (124) of the heat exchanger (122) comprises at least one primary coolant opening (124c) adapted to be arranged on the second side (210) of the opening (204), and wherein a secondary side (126) of the heat exchanger (122) comprises at least one secondary coolant opening (1260) adapted to be arranged on the first side (216) of the opening (204).

11. The electrically driven propulsion system (100) according to any of the preceding claims, which further comprises a rudder actuator (112), wherein at least a section of the rudder actuator (112) is arranged inside the common waterproof housing (108).

12. A connecting frame (302) for connecting a propulsion system (100) to a hull (202) with an opening (204), wherein the connecting frame (302) comprises:

a first ring-shaped element (306) comprising a first opening (304a), first connecting elements (316), and through holes (320a);

a second ring-shaped element (308) comprising a second opening (304b); second connecting elements (318), wherein the first connecting elements (316) and the second connecting elements (318) comprise a first common arrangement; and detachable connection elements (320b) adapted to couple to fixing means (110a, 222) of the propulsion system (100);

a first sealing face (310) arranged on the first ring-shaped element (306) and encircling the first opening (304a); and

a second sealing face (320) arranged on the first ring-shaped element (306) opposite to the first sealing face (310) and encircling the first opening (304a);

wherein the first ring-shaped element (306) and second ring-shaped element (308) are adapted to be connected using the first connecting elements (316) and the second connecting elements (318) and with a relative orientation defined by the first common arrangement; and wherein, according to the relative orientation:

the first opening (304a) overlaps with the second opening (304b) to form an opening (304) of the connecting frame (302);

the through holes (320a) coincide with the detachable connection elements (320b); and

the first sealing face (310) is arranged between the connected first ring-shaped element (306) and second ring-shaped element (308) and adapted to provide a waterproof connection between the connecting frame (302) and the hull (202) with the opening (204).

13. A connecting system comprising the connecting frame (302) according to claim 12 and a support element (128) adapted to mechanically support the propulsion system (100) via a support arm (128a), wherein the support element (128) is adapted to be connected to the connecting frame (302) such that the support arm (128a) extends away from the connecting frame (302).

14. A method (200) for connecting an electrically driven propulsion system (100) as a whole to a hull (202) with an opening (204), wherein the electrically driven propulsion system (100) comprises:

an electric motor (102) adapted to provide a mechanical power of at least 50 kW;

a transmission (106) functionally coupled to the electric motor (102), the transmission (106) comprising a propeller coupling (106p) adapted for mounting a propeller (104); and

a common waterproof housing (108), wherein the electric motor (102) and an enclosed section (106e) of the transmission (106) are arranged inside the common waterproof housing (108), wherein the propeller coupling (106p) is arranged outside the common waterproof housing (108), wherein the transmission (106) is adapted to rotationally couple the propeller coupling (106p) to the electric motor (102), and wherein the common waterproof housing (108) comprises a motor section (108a) in which the electric motor (102) is arranged;

the method (200) comprising:

providing (230) the electrically driven propulsion system (100) as a whole on a second side (210) of the opening (204) of the hull (202);

moving (214), while keeping the electrically driven propulsion system (100) assembled as a whole and while keeping the propeller coupling (106p) on the second side (210), at least a section of the motor section (108a) through the opening (204) to a first side (216) of the opening (204) opposite to the second side (210), such that at least a portion of the common waterproof housing (108) remains on the second side (210); and

fixing (218) the electrically driven propulsion system (100) to the hull (202) with the opening (204); and

forming (232, 218b) a waterproof connection between the hull (202) with the opening (204) and the common waterproof housing (108).

15. The method according to claim 14, wherein the fixing (218) the electrically driven propulsion system (100) to the hull (202) with the opening (204) comprises fixing the electrically driven propulsion system (100) as a surface drive to the hull (202) with the opening (204).

Drawing