IMPROVED SAIL-DRIVE PROPULSION SYSTEM FOR BOATS

Abstract

 A boat propulsion system equipped with sail-drive transmission is disclosed, comprising
a drive motor (M) coupled to a sail-drive transmission equipped with a drive shank (1) carrying a propeller shaft (3) for a propeller at a distal end, and
a supporting and sealing flange (2), apt to be engaged in a correspondingly shaped opening of a boat's hull, to which said drive shank (1) is attached,
wherein
said supporting and sealing flange (2) has an upper and a lower side and consists of a main portion (2a), to which said drive shank (1) is attached, and at least an extension portion (2b) provided with at least one through opening (6a, 6b) into which a corresponding nozzle (8) is engaged with
an ejection section (8b), arranged on the underside of said flange (2), with an exit channel having an axis oriented substantially horizontally so as to produce a thrust in a different direction from that produced by said propeller,
an inlet section (8a), located on the upper side of said flange (2), connected to a pressurized water supply pipe from at least a pressurization pump (9) connected to a water loading inlet.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of boat propulsion systems, in particular propulsion systems in sail-drive configuration.

STATE OF PRIOR ART

[0002] As it is well known, boat propulsion systems typically involve transferring a driving force from a main engine, housed inside the boat's hull, to a propeller outside the hull that is immersed in the water and transfers propulsion energy to this fluid.

[0003] To this end, countless different solutions for transmitting energy from the engine to the fluid in which the boat moves have been proposed over time.

[0004] In the context of this disclosure, reference will be made to the sail-drive or L-drive transmission configuration. This configuration has a drive shank running substantially vertically through the hull and transferring the driving force - coming from a horizontal or vertical drive shaft - to a propeller with a horizontal axis of rotation, by means of drive shafts and bevel gear pairs. The drive shank is attached to a support flange, with which the sail-drive is firmly fastened to the hull wall.

[0005] An example of a sail-drive is the one marketed under the sailmaster^® brand by BellMarine^®, which advantageously employs an electric motor. An exemplary support flange, equipped with a sealing gasket, is described for example in US2013/260622.

[0006] Other known configurations are, for example, described in US7387556, EP1646552, CN216185965 and US3924556, in which there is also provided a duct through the sail-drive transmission, arranged to convey a working fluid (e.g. exhaust gas from an endothermic engine) to the propeller.

[0007] The propeller of a sail-drive has usually a fixed rotation axis, although it can be set in forward or reverse rotation by reversing the propeller drive or gearbox. In this case, the boat's directional rudder is traditionally used to carry out steering manoeuvres.

[0008] Sail-drive (so-called azimuthal) configurations have also been proposed in which the vertical drive shank is mounted swiveling on the vertical axis relative to the support flange. In this case, the axis of rotation of the propeller can be oriented according to different angles in the horizontal plane, thus producing a somewhat vectorable thrust, which facilitates manoeuvring the boat.

[0009] However, this solution has not been widely adopted - at least for main propulsion systems - because it entails both construction difficulties, which are reflected in high production costs, and critical maintenance issues, because the relative rotational movement between shank and flange requires the presence of sliding seals that are subject to wear and malfunction.

[0010] To facilitate lateral manoeuvring of boats, overcoming the typical inefficiency of the rudder at low speed, it has also been proposed to install auxiliary propulsion systems on the sides of the hull or in the bow. These systems are inoperative during navigation, but can be activated to produce lateral thrust when manoeuvring. Auxiliary propulsion systems come in different configurations and can be either propeller-driven, e.g. with ducted propellers, or water-jet-driven.

[0011] Waterjets are particularly effective for this use, because although they do not express a high thrust (but still sufficient in manoeuvring), they have the advantage of having no moving parts under the boat's hull. Typically, they comprise a hydrodynamic pump on board the boat, which draws water from an inlet and ejects it under pressure to one or more nozzles on the side of the hull.

[0012] A particularly effective solution is the one marketed by Jet Thruster^™.

[0013] The disadvantage of these auxiliary propulsion systems is that additional openings, with associated watertight seals, must be provided in the hull walls.

[0014] The problem at the heart of the invention is therefore to provide a sail-drive propulsion configuration that does not have the economic disadvantages of azimuthal versions, nor the disadvantages of auxiliary water-jet propulsion, but allows for good manoeuvrability of the boat, overcoming the inefficiency of manoeuvring the rudder at low speed.

[0015] This is achieved by means of a sail-drive propulsion system as described in its essential features in the attached main claim.

[0016] Dependent claims describe preferential features of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Further features and advantages of the propulsion system according to the present invention will, however, be best illustrated by the following detailed description of an exemplary embodiment thereof, provided purely by way of example and not limitation and illustrated in the accompanying drawings, in which

Fig. 1 is a side elevation view of the propulsion system according to an embodiment of the invention;

Fig. 2 is a rear perspective view of the system in Fig. 1;

Fig. 3 is a rear perspective view from below of the system in Fig. 1;

fig. 4 is an enlarged detail view from a similar perspective to fig. 2;

Figs. 5A and 5B are views from another perspective of the system in Fig. 1 with and without nozzles, respectively;

Figs. 6 and 7 are views from other perspectives from below the system of Fig. 1 without nozzles and clamping sleeves; and

Fig. 8 is a view similar to fig. 1 of a hydraulic diagram associated with the system according to the embodiment of the invention in Fig. 1.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

[0018] An exemplary propulsion system according to the invention is illustrated in detail in Figs. 1-7.

[0019] In a way known per se, as it is also provided for in the sail-drive configuration marketed under the sailmaster^® brand name shown above, a propulsion system comprises a drive shank 1, attached to a supporting and sealing flange 2, provided at a lower/distal end with a propulsion shaft 3 for a propeller (not shown in the figures) and connected, above the flange, to a drive motor M.

[0020] The support and sealing flange 2 is intended to be fitted and fastened to an aperture of suitable size and shape in the lower wall of a boat hull. It is typically mounted with a reference plane P (perpendicular to the sheet in the representation of Fig. 1) that is substantially horizontal when the boat is in its non-heeled buoyancy attitude. The drive shank 1 is coupled to the flange 2 with its longitudinal axis L substantially orthogonal to the reference plane P of the flange 2.

[0021] The transmission shank 1 has suitable transmission shafts and gears (e.g. bevel gears) inside it to transfer the drive torque of the motor M from an input shaft (horizontal or vertical) to the horizontally arranged propulsion shaft 3. The external shape of shank 1 offers a traditional hydrodynamic cross-section suitable for reducing drag. Shank 1 is integral with a head plate 1a by means of which it is tightly coupled to flange 2.

[0022] Further details of the construction of transmission shank 1 will not be given here because they are well known to the skilled in the art.

[0023] In the embodiment illustrated in the figures, the drive motor M is an electric motor with a vertical drive shaft, directly engaged on the same axis as the input shaft of drive shank 1. In this case, motor M is advantageously supported not only by the coupling with flange 2, but also by retaining brackets 4 and 5, which are fixed by means of anti-vibration feet 4a and 5a respectively to flange 2 and to the wall (not illustrated) of the boat's hull.

[0024] According to the invention, the flange 2 consists of a substantially circular main portion 2a, to which the transmission shank 1 is attached, and an extension portion 2b which extends as a lobe (rectangular in the illustrated version) - but may also have a perimeter contour of a different shape - in which a pair of through openings 6a and 6b is cut.

[0025] In the lower part of the flange 2, gasket means are provided to seal against the wall of a hull boat. The latter must then be provided with an opening of a shape corresponding to the gasket means, so as to sealingly accommodate the flange 2 fitted with the extension portion 2b.

[0026] The gasket means may be represented by a single gasket element encircling both the head plate 1a of drive shank 1 and the openings 6a and 6b, or - as well depicted in Figs. 6 and 7 - they may preferably consist of two separate gaskets G1 and G2, respectively circular to circumscribe head plate 1a (i.e. the longitudinal axis of drive shank 1) and oval to circumscribe the pair of openings 6a and 6b.

[0027] Around the openings 6a and 6b, preferably on the upper side of the extension portion 2b, suitable lockable sleeves 7a and 7b are provided.

[0028] Tubular nozzles 8 of a generic L-shape, which have an inlet section 8a, arranged above the flange 2b, and an ejection section 8b, arranged below the flange 2b, are also engaged in the openings 6a and 6b. The tubular nozzles are locked in position by means of lockable sleeves 7a and 7b.

[0029] The inlet section 8a may be oriented as preferred, depending on the overall dimensions and arrangement of the other components inside the hull. The ejection section 8b, on the other hand, provides an exit channel with an axis arranged substantially horizontally, so as to be able to produce an effective thrust in a lateral direction to the boat, as will be illustrated later on. In particular, the exit apertures of the two ejection sections 8b of the nozzles 8 are oriented in directions which provide at least one component facing away a vertical median plane passing through the axis of the propeller shaft 3. In this way, the thrust exerted by each of the two nozzles can be directed to at least the two side parts of the boat.

[0030] A delivery line (not shown) of a hydraulic circuit is connected to the inlet section 8a of the nozzle pair 8 as shown schematically in Fig. 8.

[0031] According to the invention, in fact, by means of the delivery lines the two nozzles 8 are supplied with a flow of pressurized water from a pressurization pump 9 (see Fig. 8), which in turn draws water from a loading pipe (not illustrated) connected to a respective water inlet provided in the hull of the boat. According to the preferred scheme, the same pressurization pump 9 supplies pressurized water alternately to the two nozzles 8 by means of a three-way valve 10 suitably controlled by means of a control logic unit (not illustrated) integrated in the boat's control panel.

[0032] As can be understood, the presence of the two nozzles 8, capable of directing a jet of pressurized water in a controlled manner to either side of the boat, provides the boat with excellent manoeuvring capability, particularly at low speed. The integration of nozzles 8 in the extension portion 2a of flange 2 of the sail-drive system ensures excellent watertightness and completely eliminates the need for additional openings in the hull to install the water jets of the auxiliary thrusters of known technology. The integration of the nozzles on the sail-drive propulsion system thus results in production and maintenance economies, which make the system of the invention particularly advantageous.

[0033] The illustrated propulsion system is representative of a simplified conceptual solution, in which the two nozzles 8 are oriented in a fixed position. However, it is not ruled out the possibility of providing a control drive that allows the two nozzles 8 to be oriented either to change the direction of the water jet or to be able to orient the two nozzles in a hydrodynamically more advantageous position during straight navigation.

[0034] In the case of a nozzle orientation control drive, the possibility of still being able to achieve good manoeuvrability even if only one nozzle can be swivelled through at least 180° is not ruled out either.

[0035] It is understood, however, that the invention is not to be considered limited to the particular arrangements illustrated above, which are only illustrative embodiments of it, but that several variations are possible, all within the reach of a person skilled in the art, without thereby going beyond the scope of protection of the invention itself, as defined by the following claims.

[0036] In particular, it shall be noted that the illustrations show an electric motorization, but it is expected that the motorization can be provided by an endothermic or other motor.

[0037] In addition, on the same extension portion 2b of the flange 2 or on another extension portion (e.g. opposed to the first one) an additional opening can be provided to which the pump's loading pipe can be engaged. According to an advantageous variant, the two opposed nozzles shown in the figures can operate alternately as a loading port or an ejection nozzle; in this instance, the pressure pump is connected by means of a solenoid valve which connects one nozzle to a pump suction port and the other nozzle to the pump delivery port when thrust is required on one side and vice versa when thrust is required on the opposite side.

[0038] Again, the water pressurization pump directed to the nozzles can be a self-powered electrically-driven pump, conveniently installed in the bilge area of the boat, or it can be advantageously connected to an auxiliary power take-off of the sail-drive main engine itself.

Claims

1. A boat propulsion system equipped with sail-drive transmission comprising

a drive motor (M) coupled to a sail-drive transmission equipped with a drive shank (1) carrying a propeller shaft (3) for a propeller at a distal end, and

a supporting and sealing flange (2), apt to be engaged in a correspondingly shaped opening of a boat's hull, to which said drive shank (1) is attached,
characterized by that

said supporting and sealing flange (2) has an upper and a lower side and consists of a main portion (2a), to which said drive shank (1) is attached, and at least an extension portion (2b) provided with at least one through opening (6a, 6b) into which a corresponding nozzle (8) is engaged, which nozzle is provided with

an ejection section (8b), arranged on the underside of said flange (2), with an exit channel having an axis oriented substantially horizontally so as to produce a thrust in a different direction from that produced by said propeller,

an inlet section (8a), located on the upper side of said flange (2), connected to a pressurized water supply pipe from at least a pressurization pump (9) connected to a water loading inlet.

2. The boat propulsion system as in claim 1, wherein said extension portion (2b) is provided with a pair of through openings (6a, 6b) into which are engaged corresponding nozzles (8a, 8b) with ejection sections (8b) oriented in directions having at least opposed components.

3. The boat propulsion system as in claim 2, wherein a single pressurization pump (9) which supplies pressurized water alternately to said nozzles (8a, 8b) by means of a three-way valve (10) controlled by means of a logic control unit is provided.

4. The boat propulsion system as in claims 2 or 3, wherein one of said nozzles (8a, 8b) alternately serves as said water loading inlet.

5. The boat propulsion system as in any one of the preceding claims, wherein said drive motor (M) has a power take-off to which said pressurization pump (9) is coupled.

6. The boat propulsion system as in any one of the preceding claims, wherein said drive motor (M) is an electric motor.

7. The boat propulsion system as in any one of the preceding claims, wherein sealing means are provided on said lower side of said flange (2).

8. The boat propulsion system as in claim 7, wherein said sealing means consist of two separate seals (G1, G2) on said main portion (2a) to circumscribe a longitudinal axis of said drive shank (1) and on said extension portion (2b) to circumscribe said openings (6a, 6b), respectively.

Drawing