TECHNICAL FIELD
[0001] The present invention relates to a marine drive system in which the drive unit can
be extended out of and retracted into the hull of the vessel. The drive system is
positioned in a housing mounted inside the hull of a marine vessel, and the drive
unit can be lowered from a parking position to a drive position. The drive system
comprises a drive motor and a marine propulsion system provided with at least one
propeller.
BACKGROUND ART
[0002] Electric propulsion of vehicles is getting more and more common in order to replace
combustible fuels. Slowly, electrical propulsion of marine vehicles are also gaining
more interest. Electrical drive systems for slower boats, such as gigs or sailboats,
are relatively energy efficient when the boat travels at low speeds. A further advantage
for sailboats is that they normally do not need the motor, and that the motor is mostly
used in emergencies and when docking. In such cases, an electric drive may be plausible.
[0003] Smaller sailboats are often provided with an outboard combustion motor that is used
to drive the sailboat when there is no wind or when docking. Larger sailboats have
an inboard combustion engine that is either provided with a straight axle that drives
a propeller arranged at the rear of the sailboat, or is provided with a so called
saildrive mounted to the hull of the sailboat. The saildrive may be provided with
a fixed propeller or a foldable propeller. A foldable propeller will induce less drag
when sailing, but is not suitable for charging a battery when sailing. A fixed propeller
induce more drag when sailing but is more suited for charging a battery when sailing.
When charging a battery, the propeller is connected to a generator that is powered
by the propeller which will induce some drag. When not charging, the propeller is
disconnected from the generator and rotates more or less freely, but will still induce
a small amount of drag.
[0004] WO 2019160509 and
US 2014022097 show examples of a fixed propeller that can be retracted into the hull of a boat.
In a retracted position, drag is minimized and the propeller is less vulnerable.
[0005] Even if these systems functions well for their intended use, there is room for an
improved drive system for a marine vessel.
DISCLOSURE OF INVENTION
[0006] An object of the invention is therefore to provide an improved drive system for a
marine vessel. A further object of the invention is to provide a marine vessel comprising
such a drive system.
[0007] The solution to the problem according to the invention is defined by the features
of the main claims. The other claims contain advantageous further developments of
the drive system.
[0008] In a drive system for a marine vessel comprising a first housing provided with an
opening and being fixed to an opening inside a hull of the marine vessel, and a drive
unit arranged inside the first housing, where the drive unit comprises a second housing
comprising a drive motor and a marine propulsion system attached to the second housing,
where the marine propulsion system comprises a leg and a hub provided with at least
one propeller, where the drive system comprises an adjustment mechanism arranged to
adjust the position of the drive unit in the first housing, where the drive system
is provided with a parking position in which the marine propulsion system is positioned
inside the first housing and a drive position in which the marine propulsion system
is positioned outside of the first housing, the object of the invention is achieved
in that the first housing is provided with an inwardly extending flange having a flange
shape, where the inwardly extending flange is arranged around the circumference of
the opening, and that the second housing is provided with an edge at the circumference
of a lower side of the second housing, having an edge shape complementary to the flange
shape, such that the edge of the second housing bears on the flange of the first housing
when the drive system is in the drive position. The first housing is arranged to be
resiliently connected to a hull of the marine vessel.
[0009] By this first embodiment of the drive system for a marine vessel, the height position
of the propeller can be adjusted. In a parking position, the complete drive unit is
positioned within the first housing and thus within the hull of the marine vessel,
such that the propeller is completely concealed. In this position, the marine propulsion
system and the propeller will not induce any drag which is of advantage when sailing.
A further advantage is that the marine propulsion system is less prone to be subjected
to biofouling. By filling the space with a gas, such as air or exhaust gas, the biofouling
problem is further minimized. In a drive position, the lower side of the second housing
of the drive unit is aligned with the hull, and the marine propulsion system extends
completely into the water. This position is used when the boat is driven by the motor,
and can also be used when the battery needs to be charged when sailing. By having
the first housing arranged to be resiliently connected to a hull of the marine vessel,
any vibrations generated by the drive system will be dampened before reaching the
hull, leading to an improved driving experience.
[0010] The first housing may be arranged to be resiliently connected to the hull of the
marine vessel by means of O-rings arranged above and below a protrusion arranged at
a lower end of the first housing. With O-ring is meant a resilient annular member,
made in rubber or other resilient material. In general, it can be any form of resilient
gasket member.
[0011] The O-rings may have a material thickness of 3-50 mm.
[0012] The drive motor is in one example an electric drive motor, and in another example
a combustion engine.
[0013] The first housing is provided with an inwardly extending flange arranged around the
circumference of the opening in the first housing. The inner diameter of the flange
is smaller than the outer diameter of the second housing. In this way, the flange
will function as an end stop for the drive unit when the drive unit is positioned
in the drive position. Thus, the drive unit will not be able to fall out should the
adjustment mechanism fail. The shape of the flange may be straight or may be tapered
with an angle relative to the vertical axis of the drive unit. The angle may e.g.
be within 30 to 60 degrees. The flange may be provided with a seal of some type.
[0014] The second housing is provided with an edge at the circumference of the lower side
of the second housing. The shape of the edge is complementary to the flange of the
first housing, and may thus be straight or tapered. With a tapered edge, the drive
unit will also be centred by the cooperation between the flange and the edge when
the drive unit is in the drive position. The edge may be provided with a seal of some
type.
[0015] The height position of the drive unit may be controlled manually by a user. A user
may e.g. retract the drive unit when the boat is parked. The position of the drive
unit may also be controlled automatically by an ECU. In one example, the drive unit
is lowered when the electric motor is engaged, e.g. when a user selects the drive
mode of the boat, and the drive unit is retracted when the drive mode is deselected.
[0016] The position of the drive unit in the cylinder-shaped housing is controlled by an
adjustment mechanism that extends and retracts the drive unit out of and into the
first housing. The position may e.g. be set with a linear actuator of some kind, such
as a hydraulic cylinder or an electric linear actuator. The adjustment mechanism may
also comprise a locking means that fixates the drive unit in the selected position.
The locking means may e.g. be a self-locking gear of an electric motor that is used
to position the drive unit in the cylinder-shaped housing.
[0017] The first housing and the second housing have the same shape, and may be circular
or non-circular. A circular shape may be of advantage if the drive unit is to be rotated
in the first housing, e.g. for steering of the vessel. A non-circular shape may be
of advantage if the rotational orientation of the drive unit should be fixed. By using
a non-circular shape for the first housing and the second housing, there is no need
to use an anti-rotational means to hold the drive unit in a fixed position.
[0018] The drive unit is in on example rotationally fixed in the first housing, such that
it cannot rotate and such that the propeller is directed in a fixed orientation. In
another example, the drive unit can be rotationally adjustable such that the propeller
can be directed in any desired direction. In this example, the drive unit can be used
to steer the boat. The drive unit may be provided with a single propeller or with
two propellers that rotate in different directions.
BRIEF DESCRIPTION OF DRAWINGS
[0019] The invention will be described in greater detail in the following, with reference
to the attached drawings, in which
- Fig. 1
- shows a schematic marine vessel provided with a drive system according to the invention,
- Fig. 2
- shows the drive unit in the parking position,
- Fig. 3
- shows the drive unit in the drive position, and
- Fig. 4
- shows a detail of a flange and an edge.
MODES FOR CARRYING OUT THE INVENTION
[0020] The embodiments of the invention with further developments described in the following
are to be regarded only as examples and are in no way to limit the scope of the protection
provided by the patent claims.
[0021] Fig. 1 shows a schematic marine vessel 30, Fig. 2 shows the drive unit in a parking
position, Fig. 3 shows the drive unit in the in a drive position, and Fig. 4 shows
a detail of a flange of the first housing and an edge of the second housing.
[0022] Fig. 1 shows a schematic marine vessel 30 provided with a drive system 1 for propelling
the marine vessel or for generating electric energy. The drive system 1 comprises
a first housing 2 that is mounted to an opening 32 in the hull 31 of the marine vessel
30. The opening 16 of the first housing 2 is mounted flush with the hull such that
the first housing 2 does not extend out of the hull. The first housing is fixedly
mounted to the hull. The opening 16 of the first housing 2 is provided with a flange
17 extending inwards from the inner side of the first housing. The vessel is also
provided with a gas pressure source 14 that can supply pressurized gas, such as air
or another suitable gas.
[0023] The inwardly extending flange 17 is arranged around the circumference of the opening
16 in the first housing. The inner diameter of the flange is smaller than the outer
diameter of the second housing. In this way, the flange will function as an end stop
for the drive unit 3 when the drive unit is positioned in the drive position 21. In
this way, the drive unit will not be able to fall out should the adjustment mechanism
10 fail. The shape of the flange may be straight or may be tapered with an angle relative
to the vertical axis 19 of the drive unit. The angle is in one example within 30 to
60 degrees and in a further example within 40 to 50 degrees. The flange may be provided
with a seal of some type. The seal will seal the area between the first housing and
the second housing and may also function as a shock absorber when the drive unit is
positioned in the drive position.
[0024] A drive unit 3 is arranged inside the first housing 2. The drive unit 3 comprises
a second housing 4 that comprises a drive motor 5 that drives a drive shaft to the
propeller 9. The drive shaft may be driven directly by the electric motor and may
be directly attached to the drive motor, or may be driven through a transmission of
some type. The drive unit may also comprise an electronic control unit (ECU) 12 used
to control the drive motor. The second housing 4 is arranged to slide inside the first
housing 2 such that the height position of the drive unit in the first housing 2 can
be adjusted. The second housing is in one example watertight.
[0025] The drive motor 5 is in one example an electric motor powered by a battery 13. One
advantage of using an electric drive motor is that the motor can also be used to charge
the battery when the drive system is installed in a sailboat. The drive motor may
also be an internal combustion engine, either fuelled by petrol or diesel. In the
shown example, an electric motor is used as the drive motor.
[0026] A marine vessel 30 may be provided with one or more drive systems 1. A smaller regular
sailboat may e.g. be provided with a single drive system that is rotationally fixed
and that replaces a regular saildrive installation, where the sailboat is steered
with a rudder. Larger sailboats may also be provided with two or more drive systems,
which may be either rotationally fixed or rotatable. The drive system is also suitable
for motorboats. A smaller motorboat may e.g. be provided with a single drive system
where the boat is steered by rotating the drive unit. A larger motorboat may be provided
with two or more drive systems, where the steering may be performed by either driving
the propellers with different rotational speeds or by rotating the drive units.
[0027] The second housing 4 is provided with an edge 18 at the circumference of the lower
side 15 of the second housing. The shape of the edge 18 is complementary to the flange
17 of the first housing, and may thus be straight or tapered. With a tapered edge,
the drive unit 3 will also be centred by the cooperation between the flange and the
edge when the drive unit is in the drive position. The edge may be provided with a
seal of some type.
[0028] The edge 18 of the second housing 4 will cooperate with the flange 17 of the first
housing 2. The shape of the edge 18 and the flange 17 is preferably the same, such
that they can cooperate with each other with a form fit. In one example, the flange
is tapered with a 45 degrees angle, and the edge 18 is consequently provided with
a 45 degrees angle. Other angles or shapes are also possible.
[0029] A marine propulsion system 6 is attached to the lower side 15 of the second housing
4. The marine propulsion system 6 comprises a leg 7 and a hub 8 and may be provided
with a single propeller 9 or with two counter-rotating propellers 9, depending on
the drive installation. The drive shaft of the drive unit extends through the leg
and the hub is provided with a bevel gear which transfers the rotation of the motor
to the propeller. In a double propeller installation, concentric drive shafts are
used.
[0030] The position of the drive unit 3 is adjusted with an adjustment mechanism 10 which
is arranged at the upper part of the drive unit. The adjustment mechanism may e.g.
comprises one or more linear actuators, such as hydraulic cylinders or electric linear
actuators. The adjustment mechanism may also comprise a threaded pin running in a
threaded nut attached to the second housing.
[0031] The inwardly extending flange 17 and the edge 18 are metal surfaces and lock in the
drive position by means of friction. A gearbox connected to the adjustment mechanism
is used to lower the drive unit 3 and an electro-mechanic brake lock the drive unit
3 in the drive position 21 when the gearbox experiences a threshold torque.
[0032] The hull 31 comprises a protrusion 23 arranged at a lower end 24 of the hull 31.
At least one O-ring 25 is arranged above and below the protrusion 23 such that a first
O-ring abuts the first housing 2 and a second O-ring abuts a clamping ring 26. The
O-rings 25 are clamped together during assembly of the marine vessel 30 and may not
be shown to scale. In this way, the first housing 2 is arranged to be resiliently
connected to the hull 31 of the marine vessel 30.
[0033] During operation of the propulsion system 6, vibrations generated run from the hub
8 through the leg 7 to the lower side 15 of the second housing 4 and further to the
cooperating flange 17 and edge 18. Finally, all vibrations from the first housing
2 are dampened by the O-rings 25 before reaching the hull 31. This leads a reduction
of vibrations experienced by the hull 31.
[0034] The O-rings 25 have a material thickness of 3-50 mm, in order to provide the desired
vibration dampening effect.
[0035] The first housing 2 and the second housing 4 have the same shape, and may be circular
or non-circular. A circular shape may be of advantage if the drive unit 3 is to be
rotated in the first housing 2, e.g. for steering of the vessel. A non-circular shape
may be of advantage if the rotational orientation of the drive unit 3 should be fixed.
By using a non-circular shape for the first housing 2 and the second housing 4, there
is no need to use an anti-rotational means to hold the drive unit in a fixed position.
[0036] The drive unit 1 can be set in different positions. One position is a parking position
20, shown in Fig. 2, in which the drive unit 1 and the marine propulsion system 6
is positioned completely inside the first housing 2. In this position, the complete
drive unit is positioned within the first housing 2 and thus within the hull of the
marine vessel, such that the propeller is completely concealed. In this position,
the marine propulsion system and the propeller will not induce any drag which is of
advantage when sailing. This may also be an advantage when the vessel is transported.
A further advantage is that the marine propulsion system is less prone to be subjected
to biofouling. By filling the space with a gas, such as air or exhaust gas, the biofouling
problem is further minimized.
[0037] The drive unit 1 is also provided with a drive position 21, shown in Fig. 3, in which
the lower side 15 of the cylinder-shaped part 4 of the drive unit 1 is aligned with
the hull 31 of the vessel 30. In the drive position, the leg 7 extends completely
into the water. This position resembles a fixed, regular installation of a saildrive
in a sailboat. This position is used when the boat is driven by the drive motor, and
can also be used when the battery 13 needs to be charged when sailing.
[0038] The position of the drive unit 1 in the first housing 2 may be controlled manually
by a user, or may be automatically controlled. A user may e.g. retract the drive unit
to the parking position when the boat is parked, and may select the drive position
when driving the vessel with the motor.
[0039] The position of the drive unit may also be controlled automatically by an ECU 12.
In one example, the drive unit is lowered when the drive motor is engaged, e.g. when
a user selects the drive mode of the boat, and the drive unit is retracted when the
drive mode is deselected.
[0040] The drive unit 3 is intended to be either a primary propulsion system for the marine
vessel 30 or a secondary propulsion system that can function when a primary propulsion
system is not available, preferably for marine vessels with electric propulsion systems.
The drive unit 3 is not intended to be used as a steering assistance or to provide
additional propulsion to complement another drive unit, electric or otherwise.
[0041] The drive unit 3 and thereby the first and second housings 2, 4 are arranged at an
angle relative a vertical axis of the marine vessel. This means that when in the drive
position 21, the leg 7 and hub 8 with propellers 9 protrude out of the hull 31 at
an angle relative a bottom part of the hull 31.
[0042] The invention is not to be regarded as being limited to the embodiments described
above, a number of additional variants and modifications being possible within the
scope of the subsequent patent claims.
REFERENCE SIGNS
[0043]
- 1:
- Drive system
- 2:
- First housing
- 3:
- Drive unit
- 4:
- Second housing
- 5:
- Drive motor
- 6:
- Marine propulsion system
- 7:
- Leg
- 8:
- Hub
- 9:
- Propeller
- 10:
- Adjustment mechanism
- 11:
- Centre axis
- 12:
- Electronic control unit
- 13:
- Battery
- 14:
- Gas pressure source
- 15:
- Lower side
- 16:
- Opening
- 17:
- Flange
- 18:
- Edge
- 19:
- Vertical axis
- 20:
- Parking position
- 21:
- Drive position
- 22:
- Intermediate position
- 23:
- Protrusion
- 24:
- Lower end
- 25:
- O-rings
- 26:
- Clamping ring
- 30:
- Marine vessel
- 31:
- Hull
- 32:
- Opening
1. A drive system (1) for a marine vessel (30) comprising a first housing (2) provided
with an opening (16) and being fixed to an opening (32) inside a hull (31) of the
marine vessel (30), and a drive unit (3) arranged inside the first housing (2), where
the drive unit (3) comprises a second housing (4) comprising a drive motor (5) and
a marine propulsion system (6) attached to the second housing (4), where the marine
propulsion system (6) comprises a leg (7) and a hub (8) provided with at least one
propeller (9), where the drive system (1) comprises an adjustment mechanism (10) arranged
to adjust the position of the drive unit (3) in the first housing (2), where the drive
system (1) is provided with a parking position (20) in which the marine propulsion
system (6) is positioned inside the first housing (2) and a drive position (21) in
which the marine propulsion system (6) is positioned outside of the first housing
(2), wherein the first housing (2) is provided with an inwardly extending flange (17)
having a flange shape, where the inwardly extending flange (17) is arranged around
the circumference of the opening (16), and that the second housing (4) is provided
with an edge (18) at the circumference of a lower side (15) of the second housing
(4), having an edge shape complementary to the flange shape, such that the edge (18)
of the second housing (4) bears on the flange (17) of the first housing (2) when the
drive system (1) is in the drive position (21), characterized in that the first housing (2) is arranged to be resiliently connected to the hull (31) of
the marine vessel (30).
2. Drive system according to claim 1, wherein the first housing (2) is arranged to be
resiliently connected to the hull (31) of the marine vessel (30) by means of at least
one O-ring (25) arranged above and below a protrusion (23) arranged at a lower end
(24) of the first housing (2).
3. Drive system according to claim 2, wherein the O-rings (25) have a material thickness
of 3-50 mm.
4. Drive system according to any one of claims 1-3, wherein the drive motor (5) is an
electric drive motor.
5. Drive system according to any one of claims 1-3, wherein the drive motor (5) is an
internal combustion engine.
6. Drive system according to any one of the preceding claims, wherein the flange shape
and the edge shape is tapered.
7. Drive system according to claim 6, wherein the angle of the tapered flange (17) of
the first housing (2) and the edge (18) of the second housing (4) is between 30 to
60 degrees with respect to a vertical axis (19) of the drive system (1).
8. Drive system according to claim 7, wherein the angle of the tapered flange (17) of
the first housing (2) and the edge (18) of the second housing (4) is between 40 to
50 degrees with respect to a vertical axis (19) of the drive system (1).
9. Drive system according to any of claims 1 to 8, wherein the flange (17) of the first
housing (2) further comprises a seal and/or the edge (18) of the second housing (4)
further comprises a seal.
10. Drive system according to any of claims 1 to 9, wherein the outer shape of the first
housing (2) and the second housing (4) is circular.
11. Drive system according to any of claims 1 to 9, wherein the outer shape of the first
housing (2) and the second housing (4) is non-circular.
12. Drive system according to any of claims 1 to 10, wherein the second housing (4) is
rotationally adjustable in the first housing (2).
13. Drive system according to any of claims 1 to 10, wherein the second housing (4) is
rotationally fixed in the first housing (2).
14. Drive system according to any of claims 1 to 13, wherein the drive unit (3) is provided
with a locking means that is adapted to lock the adjustment mechanism (10) in the
selected position (20; 21; 22).
15. Marine vessel, comprising at least one drive system (1) according to any of claims
1 to 14.