TECHNICAL FIELD

The present invention relates to a marine drive system comprising an interceptor assembly integrated in the drive system. The drive system is positioned in a housing mounted inside the hull of a marine vessel, and the propeller can be lowered from a parking position to a drive position. In the drive position, the interceptor can be extended out of the housing in order to stabilize the marine vessel.

BACKGROUND ART

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. It is however possible to design hulls that are relatively easy to drive, such that it is possible to use electrical drive systems also on faster motor boats.

It is known to provide a boat with an interceptor system that is arranged to stabilize the boat and to help when the boat accelerates. The interceptor system will adjust both pitch and roll of the boat. Normally, at least two interceptors are mounted at the rear of a motor boat.

Even if such systems functions well for their intended use, there is room for an improved drive system for a marine vessel.

DISCLOSURE OF INVENTION

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. 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.

In a drive system for a marine vessel comprising a first housing fixed to an opening in 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 drive system is provided with an interceptor comprising an interceptor blade arranged in the first housing.

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. This may be of advantage when transporting and handling the boat. A further advantage is that the marine propulsion system is less prone to be subjected to biofouling, since less light can reach the concealed propeller. 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. The marine vessel is a motorboat. The drive motor is in one example an electric drive motor, and in another example a combustion engine. The drive system is provided with an interceptor comprising an interceptor blade arranged in the first housing. The extension out of the first housing of the interceptor blade can be adjusted either automatically or manually, depending on driving mode. The height adjustment of the interceptor blade is made with a height adjustment mechanism that in one example is driven by an electric motor, but may also be hydraulic. The height adjustment mechanism is preferably provided with a position sensor that can detect the position of the interceptor blade.

The interceptor blade is arranged in the first housing, at the rear side pointing towards the stem of the boat, away from the propeller. One advantage of arranging the interceptor in the first housing of the drive system is that a complete unit can be delivered to a boat builder, which simplifies the installation of the drive unit and the interceptor. Normally, an interceptor is a separate part that is installed separately at the stern of a boat. With the inventive drive system, a simplified installation is provided. By integrating the interceptor in the drive system, the same installation can be used for drive systems with or without an interceptor, such that the same drive unit may be used for both types.

The size and shape of the interceptor blade is dependent on the size and power output of the drive system and on the size of the marine vessel. The total area of the interceptor blade is the maximal extension out of the first housing times the width of the interceptor blade. The shape of the interceptor blade follows in one example the shape of the first housing and may be slightly curved. The interceptor blade is controlled by an adjustment mechanism that may be integrated in the interceptor blade, or the drive means of the interceptor blade may be arranged externally, e.g. at the upper part of the first housing. This will save some space at the lower part of the first housing.

The adjustment mechanism can in one example adjust the interceptor blade in a linear manner. In this example, the interceptor blade comprises a position sensor such that the position of the interceptor blade can be detected and used for feedback. In another example, the interceptor blade has only two positions, a retracted position and an extended position. In this case, the interceptor is only used when accelerating the boat.

A drive system comprising an interceptor is not used alone. At least two drive systems are mounted on a marine vessel, symmetrically mounted in parallel on each side of the marine vessel. It is also possible to use more than two drive systems if the hull allows such an installation.

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 noncircular 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.

The height position of the drive unit may be controlled manually by a user. A user may e.g. retract the drive unit in shallow waters. A user may further retract the drive unit when the boat is parked. The height position of the drive unit may also be controlled automatically by an ECU. 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. The ECU may also control the extension of the interceptor blade in dependency of a speed signal, a roll signal and a pitch signal.

The height position of the drive unit in the first 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 selflocking gear of an electric motor that is used to position the drive unit in the first housing.

In one example, the first housing and the second housing are circular. The drive unit is in one 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 is 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. A drive unit may be provided with a single propeller or with two propellers that rotate in different directions.

BRIEF DESCRIPTION OF DRAWINGS

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 two drive systems according to the invention,

Fig. 2 shows the drive unit in the parking position, and

Fig. 3 shows the drive unit in the drive position.

MODES FOR CARRYING OUT THE INVENTION

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.

Fig. 1 shows a schematic marine vessel 30 provided with two drive systems 1 (only one shown) arranged symmetrically on each side of the hull for propelling the marine vessel. Each drive system 1 is provided with an interceptor 22 having an interceptor blade 23. The marine vessel may be provided with more than two drive systems if the hull allows such an installation. For a marine vessel having a relatively flat hull, four drive systems would e.g. be plausible. It is important that the drive systems are mounted in a symmetrical manner in parallel to each other on the hull, in order to allow the interceptors to function optimal when adjusting roll and pitch of the marine vessel.

A 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 is provided with a flange 17 extending inwards from the inner side of the first housing. The flange 17 may be straight or angled. The vessel may also be provided with a gas pressure source 14 that can supply pressurized gas, such as air or another suitable gas.

An interceptor is used to stabilize the marine vessel during forwards travel, and are used as a replacement to trim tabs that are mounted at the stern of a boat. An interceptor system creates a hydrodynamic lift force by intercepting the water flow underneath the hull. In that way the interceptor creates a lift force acting on the hull instead of on the trim-device itself, such as normal trim tabs. By having one interceptor blade on each side of the boat, the interceptor allows the boat to quickly move up on the plane and stay stable and more upright in sharp turns. This means significantly improved visibility ahead, excellent visibility in sharp turns, and enhanced on-board safety. An interceptor may be used for both planing and semiplaning boats. By maintaining the best trim angle, fuel consumption is minimized, meaning reduced costs and lower environmental impact. By controlling the roll of the boat, a more stable travel is obtained.

The interceptor is integrated in the first housing 2 of the drive system. The interceptor blade 23 is arranged in the first housing, at the rear side of the first housing, towards the stem and pointing away from the propeller. One advantage of arranging the interceptor in the first housing of the drive system is that a complete unit can be delivered to a boat builder, which simplifies the installation of the drive unit and the interceptor. Normally, an interceptor is a separate part that is installed separately at the stern of a boat. For larger interceptors, the adjustment mechanism is normally installed inside the hull, with a control axle running through the hull to the interceptor blade. With the inventive drive system, a simplified installation is provided. By integrating the interceptor in the drive system, the same installation can be used for drive systems with or without an interceptor, such that the same drive unit may be used for both types.

The drive system 1 is provided with an interceptor 22 comprising an interceptor blade 23 arranged in the first housing. The extension out of the first housing of the interceptor blade can be adjusted either automatically or manually, depending on driving mode. The height adjustment of the interceptor blade is made with a height adjustment mechanism 24 that in one example is driven by an electric motor, but may also be hydraulic. The height adjustment mechanism 24 is preferably provided with a position sensor that can detect the position of the interceptor blade. If a stepper motor is used, it is also possible to count the control pulses to the motor, since the interceptor can be calibrated every time the blade is retracted.

The interceptor blade 23 is arranged in the rear side of the first housing 2. The shape of the interceptor blade follows in one example the shape of the first housing and may be slightly curved, but a plane interceptor blade is also possible to use. The interceptor blade is controlled by an adjustment mechanism 24 that may be integrated in the interceptor blade, or the drive means of the interceptor blade may be arranged externally of the interceptor blade, e.g. at the upper part of the first housing. This will save some space at the lower part of the first housing. The adjustment mechanism may also be arranged externally of the first housing.

The adjustment mechanism can in one example adjust the interceptor blade in a linear manner. In this example, the interceptor blade may comprise a position sensor such that the position of the interceptor blade can be detected and used for feedback. In another example, the interceptor blade has only two positions, a retracted position and an extended position. In this case, the interceptor is only used when accelerating the boat.

An ECU 12 is arranged to control the interceptor. The ECU uses different signals to control the interceptor, depending on the selected drive mode of the interceptor. One drive mode may e.g. be to automatically control only pitch, another may be to automatically control both pitch and roll. The speed of the boat is also used as one control parameter. The position of the interceptor blade may also be dependent on the height position of the drive unit 3 in the first housing 2. In one example, the interceptor blade is completely retracted when the drive unit is in the parking mode. When the drive unit is in the driving mode, and the speed is above a predefined speed, the interceptor blade may extend out of the first housing by a predefined amount. In this mode, the interceptor blade may also be adjusted to control pitch and/or roll.

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 drive 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. The edge 18 of the lower side 15 of the second housing 4 is provided with a taper of some kind, arranged to cooperate with the flange 17 of the first housing 2.

The drive motor 5 is in one example an electric motor powered by a battery

13. 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.

A marine vessel 30 is provided with at least two drive systems 1 . 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.

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 noncircular 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.

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 drive motor to the propeller. In a double propeller installation, concentric drive shafts are used.

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.

The drive unit 3 can be set in different positions. One position is a parking position 20, shown in Fig. 2, in which the drive unit 3 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 be damaged when mooring in shallow waters. 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. In this position, the interceptor blade may be completely retracted.

The drive unit 3 is also provided with a drive position 21 , shown in Fig. 3, in which the lower side 15 of the second housing 4 of the drive unit 3 is aligned with the hull 31 of the vessel 30. In the drive position, the leg 7 extends completely into the water. This position is used when the boat is driven by the motor. In this position, the interceptor can be used to stabilize the boat for pitch and/or roll.

The height position of the drive unit 3 may be controlled manually by a user, or may be automatically controlled. The height position of the drive unit may also be controlled automatically by an ECU 12.

The drive unit 3 is in one example rotationally fixed in the first housing 2, such that it cannot rotate and such that the propeller is directed in a fixed orientation. In another example, the drive unit is 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. By using at least two rotationally controllable drive systems 1 , the direction control of the vessel is improved.

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

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

20: Parking position

21 : Drive position

22: Interceptor

23: Interceptor blade

24: Adjustment mechanism

30: Marine vessel

31 : Hull

32: Opening