DRIVE FOR A VEHICLE, WATER VEHICLE WITH SUCH A DRIVE, METHOD FOR OPERATING A WATER VEHICLE, AND CONTROL DEVICE FOR SUCH A WATER VEHICLE

Description

[0001] The invention relates to a drive for a vehicle, a watercraft with such a drive, a method for operating such a watercraft, and a control unit for such a watercraft.

[0002] The fundamental problem with vehicles, especially watercraft, is decelerating them quickly and with the shortest possible deceleration distance, particularly from full speed. Specifically, such a watercraft should be able to stop within the shortest possible time and distance to avoid collisions whenever possible. Therefore, there is a general need to improve deceleration performance.

[0003] The invention is based on the objective of creating a drive for a vehicle, a watercraft with such a drive, a method for operating a watercraft, and a control unit for such a watercraft, wherein the aforementioned objectives are at least partially achieved, preferably achieved.

[0004] The problem is solved by providing the present technical teaching, in particular the teaching of the independent claims as well as the embodiments disclosed in the dependent claims and the description.

[0005] The problem is solved, in particular, by providing a drive system, especially a motor drive, for a vehicle, especially a watercraft, comprising an internal combustion engine and a freewheel mechanism. The internal combustion engine is effectively connected to a drive shaft of the drive system via the freewheel mechanism. The freewheel mechanism is designed to decouple the internal combustion engine from the drive shaft, i.e., to disconnect the drive connection, when the rotational speed of the drive shaft exceeds the rotational speed of the internal combustion engine. The fact that the internal combustion engine is effectively connected to the drive shaft via the freewheel mechanism means, in particular, that the drive connection between the internal combustion engine and the drive shaft can be engaged and disengaged by the freewheel mechanism.In particular, the internal combustion engine can be decoupled from the drive shaft by means of the freewheel device.

[0006] In this configuration, particularly when the drive is used in a vehicle, especially a watercraft, it results in the following situation: for example, in an operating situation where, starting from forward motion, the direction of rotation of a propeller shaft connected to the drive shaft is to be reversed, for example, to decelerate the vehicle, the internal combustion engine is idling or switched off in order to first reduce the rotational speed of the propeller shaft (hereinafter also referred to as propeller shaft speed) by the acting water forces before the propeller shaft is then driven in the opposite direction. In this case, during the reduction of the propeller shaft speed, a rotational speed associated with the propeller shaft—that is, in particular, the rotational speed of the drive shaft—exceeds the rotational speed of the internal combustion engine, so that the internal combustion engine is decoupled from the propeller shaft.

[0007] The drive system is now designed to include a bypass device configured to couple the internal combustion engine to the drive shaft in at least one operating situation of the drive system, particularly in at least one operating situation of the vehicle, when the internal combustion engine is disconnected from the drive shaft by the freewheeling device. Specifically, when used in a watercraft, the transmission device is configured to couple the internal combustion engine to the propeller shaft in at least one operating situation of the watercraft when the internal combustion engine is disconnected from the propeller shaft by the freewheeling device.

[0008] Thus, it is now particularly advantageous to use the bypass device to couple the internal combustion engine to the drive shaft even in operating situations where the drive shaft speed exceeds the engine speed. This can be used in a vehicle, in particular, to reduce the drive shaft speed more quickly, especially the propeller shaft speed in a watercraft, particularly when changing from one direction of rotation to a second, opposite direction of rotation of the propeller shaft, in which case the propeller shaft is driving the internal combustion engine. A torque reducing the engine's speed is thus advantageously introduced from the internal combustion engine into the drive shaft, especially the propeller shaft.The proposed design thus allows for faster deceleration of the vehicle, particularly because it enables a quicker switch from one direction of propeller shaft rotation to the opposite direction, in order to actively decelerate the vehicle. This significantly reduces the time and distance required to stop the vehicle, thereby improving the prevention of collisions.

[0009] The drive shaft is in particular an output or driven shaft of the drive, that is to say in particular a shaft from which the mechanical power of the drive can be taken or from which the drive provides mechanical power for taking.

[0010] A freewheeling device is generally understood to be a device that allows the drive shaft to be decoupled from the internal combustion engine when the rotational speed of the drive shaft exceeds the rotational speed of the internal combustion engine. The freewheeling device does not necessarily have to be a mechanical freewheel; rather, it is sufficient for the freewheeling device to provide the corresponding function, regardless of the specific design of this function. From the perspective of the internal combustion engine, the freewheeling device acts like an overrunning gear: as soon as the rotational speed of the internal combustion engine is lower than the rotational speed of the drive shaft, the internal combustion engine is in freewheel mode.

[0011] The bypass device is specifically designed to bypass the freewheel device. This means, in particular, that the bypass device can then couple the internal combustion engine to the drive shaft when the internal combustion engine is actually decoupled from the drive shaft by the freewheel device. The drive system includes the bypass device in addition to the freewheel device; that is to say, the bypass device is not identical to the freewheel device. According to a preferred embodiment, the drive system includes the bypass device separately from the freewheel device.

[0012] The at least one operating state of the propulsion system, in particular of the watercraft, in which the bypass device couples the internal combustion engine to the drive shaft, is – as already explained – according to a preferred embodiment, a switching from a first direction of rotation of the watercraft's propeller shaft to a second direction of rotation of the propeller shaft, in particular a switching from forward travel to reverse travel – or vice versa – preferably, in particular, a switching from a full-power forward operating state to a full-power reverse operating state – or vice versa – or a switching from any operating state with respect to travel in a certain direction to a full-power operating state with respect to travel in the opposite direction, for example, from forward travel – regardless of whether this is without propulsion, at quarter power,at half power or at full power - to return at full power.

[0013] Particularly preferred is at least one operating situation, a braking situation of the vehicle, especially the watercraft, in which the vehicle is to be decelerated – preferably with maximum power. In a particularly preferred embodiment, at least one operating situation is an emergency stop situation in which the vehicle is to be stopped in the shortest possible time and over the shortest possible distance due to a hazardous situation.

[0014] The fact that an element can be connected to another element in a drive-effective manner or is connected in a drive-effective manner means in particular that a torque-transmitting connection can be formed or is formed between the one element and the other element.

[0015] According to a further development of the invention, the drive system additionally comprises an electric machine, wherein the internal combustion engine and the electric machine can be connected to the drive shaft via the freewheel mechanism, such that only the internal combustion engine, only the electric machine, or the internal combustion engine and the electric machine together can drive the drive shaft. In particular, the drive system is preferably configured such that in a first operating state of the drive system only the internal combustion engine, in a second operating state of the drive system only the electric machine, and in a third operating state of the drive system the internal combustion engine and the electric machine together can drive the drive shaft. The drive system is preferably designed as a hybrid drive system.In particular, the internal combustion engine and the electric machine act on the same drive shaft, especially on the same propeller shaft of the watercraft.

[0016] The freewheeling device is specifically designed to decouple the internal combustion engine from the drive shaft when the rotational speed of the drive shaft driven by the electric motor exceeds the rotational speed of the internal combustion engine. This advantageously achieves the functionality of decoupling the internal combustion engine from the drive shaft when the primary drive load is supplied by the electric motor.

[0017] Preferably, in at least one operating situation in which the internal combustion engine is coupled to the drive shaft via the bridging device, the electric machine is controlled in order to actively decelerate the speed of the drive shaft.

[0018] A hybrid drive enables special types of deceleration for the vehicle. The presence of two drive systems—the internal combustion engine on the one hand and the electric motor on the other—allows the advantages of both to be combined. In particular, the high torque of the electric motor at low speeds enables significantly more efficient braking than with the internal combustion engine alone. The design proposed here utilizes the potential of both drive systems for optimal braking performance.

[0019] Preferably, the drive system includes an electrical storage device configured to selectively store or release electrical energy. The electrical storage device is preferably operatively connected to the electric machine in order to store – depending on the operating state of the drive system, and in particular depending on the operating state of the vehicle – the kinetic energy of the vehicle converted into electrical energy by the electric machine operating as a generator, i.e., in particular to store recuperated energy, or to use the stored energy for operating the electric machine as a motor.

[0020] According to a further development of the invention, the freewheel device is designed as a mechanical freewheel. This represents a particularly simple embodiment of the freewheel device.

[0021] Alternatively, it is preferably provided that the freewheel device is designed as a transmission unit or as part of a transmission unit. This represents a more complex design of the freewheel device, which advantageously enables the realization of a larger number of operating states. In particular, the freewheel device can be designed as a planetary gear unit. Preferably, two electric motors are operatively connected to the planetary gear unit. In this configuration, where the internal combustion engine and two electric motors interact with a planetary gear unit, a particularly wide variety of operating states can be realized.

[0022] In particular, the freewheel device can be designed as an intermediate gearbox or as part of an intermediate gearbox, or arranged in front of an intermediate gearbox - on the input side, on the side of the internal combustion engine.

[0023] According to a further development of the invention, the bridging device is arranged on the freewheel mechanism. Alternatively, it is preferably provided that the bridging device is integrated into the freewheel mechanism. Alternatively, it is also preferably provided that the bridging device is arranged parallel to the freewheel mechanism. Each of these alternatives allows for a particularly compact and at the same time effective arrangement of the bridging device within the drive.

[0024] According to a further development of the invention, the bridging device is designed as a coupling. This represents a particularly simple and effective design of the bridging device. In a preferred embodiment, the bridging device is designed as a magnetic coupling. This represents an equally simple and reliable design of the bridging device.

[0025] The problem is also solved by creating a watercraft that has a drive according to the invention or a drive according to one of the previously described embodiments, wherein the drive shaft is a propeller shaft of the watercraft, or wherein the drive shaft is connectable to or effectively connected to the propeller shaft of the watercraft. In connection with the watercraft, the advantages already explained in connection with the drive system become particularly apparent.

[0026] In particular, a watercraft is preferred in which the internal combustion engine of the propulsion system can be effectively connected to the propeller shaft via the freewheeling device. The freewheeling device is configured to decouple the internal combustion engine from the propeller shaft when the rotational speed associated with the propeller shaft exceeds the rotational speed of the internal combustion engine. The bypassing device is configured to couple the internal combustion engine to the propeller shaft in at least one operating situation of the watercraft when the internal combustion engine is disconnected from the propeller shaft by the freewheeling device.

[0027] A watercraft is understood to be, in particular, a vehicle designed for movement on or in water. Specifically, the watercraft has its own propulsion system and is therefore self-propelled. In a preferred embodiment, such a watercraft is, in particular, a ship, a boat, or a raft. However, the watercraft can also be an amphibious vehicle, a personal watercraft, an aquascooter, or the like. In a particularly preferred embodiment, the watercraft is a yacht.

[0028] The rotational speed associated with the propeller shaft is understood to be, in particular, a rotational speed that, from the perspective of the internal combustion engine, is characteristic of a given angular velocity of the propeller shaft and / or is uniquely related to the angular velocity of the propeller shaft. Specifically, the rotational speed associated with the propeller shaft is the rotational speed of the drive shaft, which is either directly connected to the propeller shaft – possibly via at least one gearbox – or which is identical to the propeller shaft. The drive shaft is, in particular, a shaft that, when the internal combustion engine is coupled to the propeller shaft via the freewheel mechanism, has the same rotational speed as the internal combustion engine.If the drive shaft is connected to the propeller shaft via at least one gearbox, it is possible that the rotational speed of the drive shaft, and thus also the rotational speed associated with the propeller shaft, differs from the rotational speed of the propeller shaft, also referred to as propeller shaft speed, with the difference being determined by the at least one gearbox. If, on the other hand, the drive shaft is identical to the propeller shaft, and thus the internal combustion engine is directly coupled to the propeller shaft in the coupled state, the rotational speed associated with the propeller shaft is identical to the rotational speed of the propeller shaft and thus also of the drive shaft; that is, the rotational speed associated with the propeller shaft is, in this case, the propeller shaft speed.

[0029] The propeller shaft is preferably coupled to a propeller of the watercraft, wherein the propeller is preferably connected to the propeller shaft in a rotationally fixed manner.

[0030] According to a further development of the invention, a gearbox is arranged between the freewheel mechanism and the propeller of the watercraft. This gearbox is configured to reverse the direction of rotation of the propeller relative to the direction of rotation of the internal combustion engine when the gearbox is engaged. This allows for a particularly simple change in the direction of rotation of the propeller while maintaining the direction of rotation of the internal combustion engine. Therefore, it is not necessary to reverse the direction of rotation of the internal combustion engine to change the propeller's direction of rotation.

[0031] In particular, the gearbox allows two operating states for the watercraft to be represented, namely forward travel and reverse travel.

[0032] The freewheeling device is designed as an intermediate gearbox or as part of an intermediate gearbox, particularly when the watercraft also has such a transmission. The transmission is preferably arranged between the freewheeling device, especially the intermediate gearbox, on the one hand, and the propeller on the other.

[0033] Preferably, a clutch is provided between the freewheel mechanism and the transmission, in particular between the intermediate gearbox and the transmission. This clutch allows the internal combustion engine and the electric motor to be decoupled from the transmission and thus also from the propeller, making it possible to switch the transmission particularly smoothly and quickly.

[0034] The drive shaft is preferably a transmission input shaft of the gearbox. Alternatively, the drive shaft is preferably an input shaft of the clutch. The term "input" always refers to a side facing the internal combustion engine. Accordingly, a side facing the propeller is referred to as the "output".

[0035] Preferably, the watercraft has two propeller shafts and two drives according to the invention, preferably identical, or more specifically, drives according to one of the previously described embodiments, with each propeller shaft having a separate drive. It is also possible for the watercraft to have more than two propeller shafts and more than two drives, particularly of the same design. It is especially advantageous for larger or more powerful watercraft to have more than one propeller shaft and more than one drive.

[0036] The problem is also solved by providing a method for operating a watercraft according to the invention or a watercraft according to one of the previously described embodiments, wherein, during a braking maneuver to reduce the propeller shaft speed, the bypass device is closed so that the internal combustion engine is coupled to the propeller shaft and driven by the propeller shaft. Within the framework of this method, the advantages already explained in connection with the propulsion system and the watercraft are realized in particular.

[0037] The braking maneuver is preferably an emergency stop maneuver. Preferably, during the braking maneuver – especially after reducing the propeller shaft speed – the drive is operated at full power in the direction opposite to the previous direction of travel, for example, full power in reverse after previously traveling forward – or vice versa.

[0038] According to a further development of the invention, it is provided that the watercraft is propelled before the braking maneuver solely by the internal combustion engine, or by the electric motor and the internal combustion engine together, wherein the following steps are carried out for the braking maneuver: a) the fuel supply to the internal combustion engine is stopped; b) the bypass device – which was previously opened – is closed; and c) the electric motor is activated to reduce the propeller shaft speed, preferably at maximum power. This means, in particular, that the electric motor is activated in such a way that the propeller shaft speed is reduced as a result of the activation of the electric motor.Using the procedure described here, the propeller shaft speed can be reduced particularly efficiently and quickly, which allows the braking maneuver to be carried out more quickly, thereby shortening the time and distance to a danger point, especially a possible collision.

[0039] The internal combustion engine has, in particular, at least one combustion chamber. The cessation of the fuel supply to the internal combustion engine means, in particular, that no more fuel is supplied to the at least one combustion chamber of the internal combustion engine. Specifically, in the case of an internal combustion engine designed as a diesel engine, the injection is stopped.

[0040] The approach proposed here utilizes in particular the drag torque of the internal combustion engine and the torque of the electric machine – especially at maximum power – together to advantageously brake the propeller shaft particularly quickly.

[0041] When the propeller shaft speed is reduced and the internal combustion engine reaches its idle speed, the clutch is preferably opened. Simultaneously, in a particularly preferred embodiment, the fuel supply to the internal combustion engine is resumed, allowing it to idle. This avoids a time delay associated with restarting the internal combustion engine for the subsequent, reverse drive of the propeller. While it is theoretically possible to resume the fuel supply to the internal combustion engine only after shifting the transmission and closing the clutch, this introduces a time delay, which is particularly disadvantageous during emergency maneuvers. If the fuel supply to the internal combustion engine is resumed with the clutch open, the electric motor preferably also rotates at the idle speed of the internal combustion engine without delivering any power.

[0042] The gearbox is preferably switched with respect to the propeller's direction of rotation. Once this has occurred, the clutch is preferably re-engaged, and the internal combustion engine and the electric motor, preferably each operating at full power, accelerate the propeller in the opposite direction to the previous rotation to enhance the braking process. Overall, this achieves a particularly effective deceleration of the watercraft.

[0043] According to a further development of the invention, an alternative embodiment of the method provides that, prior to the braking maneuver, the watercraft is propelled solely by the electric motor, with the internal combustion engine preferably stopped, meaning the fuel supply to the at least one combustion chamber—in particular to all combustion chambers—is stopped; the internal combustion engine is not running. In this operating state, the internal combustion engine is decoupled from the propeller shaft, in particular by the freewheeling device. The following steps are then carried out for the braking maneuver: The electric motor is activated—in particular at maximum power—a) to reduce the propeller shaft speed. This means, in particular, that the electric motor's direction of rotation is reversed compared to the previous propulsion situation. Then, b) the bypass device is engaged.Subsequently, the internal combustion engine also brakes the propeller shaft with its frictional torque.

[0044] If the rotational speed of the propeller shaft falls below the idle speed of the internal combustion engine, the clutch is preferably opened. Preferably, fuel is simultaneously supplied to the internal combustion engine, i.e., the engine is started, running at idle. As explained above, this is particularly useful for avoiding delays, especially in emergency maneuvers. In this case, the electric motor rotates at the idle speed of the internal combustion engine, even without delivering power.

[0045] The gearbox is now preferably shifted, and as soon as this process is complete, the clutch is engaged. The internal combustion engine and the electric motor then jointly accelerate the propeller – preferably each at maximum power – in the opposite direction of rotation to the previous one, in order to intensify the braking process.

[0046] The problem is also solved by creating a control unit for a watercraft that is configured to carry out a method according to the invention or a method according to one of the embodiments described above. In connection with the control unit, the advantages described above in connection with the drive, the watercraft, and the method become particularly apparent.

[0047] According to a further development of the invention, the watercraft has a control unit according to the invention or a control unit according to one of the previously described embodiments, which is operatively connected to the bridging device.

[0048] The invention will be explained in more detail below with reference to the drawing.

[0049] This shows: Figure 1 is a schematic representation of an embodiment of a drive system and an embodiment of a watercraft; Figure 2 is a schematic representation of a first embodiment of a method for operating the watercraft, and Figure 3 is a schematic representation of a second embodiment of the method for operating the watercraft.

[0050] Fig. 1Figure 1 shows a schematic representation of an embodiment of vehicle 2, in particular a watercraft 1, which has an embodiment of a drive 3. The drive 3 has an internal combustion engine 5, preferably a diesel engine, wherein the internal combustion engine 5 can be connected to a propeller shaft 9 via a freewheel device 7. The freewheel device 7 is configured to decouple the internal combustion engine 5 from the propeller shaft 9 when the rotational speed associated with the propeller shaft 9 exceeds the rotational speed of the internal combustion engine 5. The drive 1 also has a bypass device 11, which is configured to couple the internal combustion engine 5 to the propeller shaft 9 in at least one operating situation of the watercraft 1 when the internal combustion engine 5 is disconnected from the propeller shaft 9 by the freewheel device 7.This advantageously allows the internal combustion engine 5 to be dragged by the propeller shaft 9 when the propeller shaft 9 is decelerated, with the frictional torque of the internal combustion engine 5 contributing to the deceleration of the propeller shaft 9. This allows braking maneuvers, particularly emergency stops, of the watercraft 1 to be accelerated, i.e., the time and distance over which the watercraft 1 is stopped to be reduced.

[0051] A propeller 13 is preferably connected to the propeller shaft 9 in a rotationally fixed manner.

[0052] The drive 3 additionally includes an electric machine 15. The internal combustion engine 5 and the electric machine 15 are both driveably connected to the propeller shaft 9 via the freewheeling device 7, such that in a first operating state only the internal combustion engine 5, in a second operating state only the electric machine 15, and in a third operating state the internal combustion engine 5 and the electric machine 15 together can drive the propeller shaft 9. The drive 3 is thus designed in particular as a hybrid drive.

[0053] An electrical storage device 17, in particular an accumulator or a battery, is operatively connected to the electrical machine 15. Depending on the respective operating state of the drive 3, the electrical machine 15 can be operated as a motor or as a generator, whereby, in particular when operated as a motor, it draws electrical energy from the electrical storage device 17, and when operated as a generator, it feeds electrical energy into the electrical storage device 17.

[0054] The freewheel device 7 is preferably designed as a mechanical freewheel, as a gear unit, or as part of a gear unit. In particular, the freewheel device 7 can also be designed as a planetary gear unit to which an additional electric machine is connected.

[0055] A transmission 19 is preferably arranged between the freewheel device 7 and the propeller 13. This transmission is configured to reverse the direction of rotation of the propeller 13 relative to the direction of rotation of the internal combustion engine 5 when the transmission 19 is engaged. In particular, the transmission 19 can enable two operating states, i.e., it can switch between two operating states of the drive 3, namely between forward and reverse travel of the watercraft 1. Furthermore, the transmission 19 may have a plurality of different gears, i.e., different gear ratios between the rotational speed, in particular of the internal combustion engine 5, on the one hand, and the rotational speed of the propeller 13 on the other.

[0056] A clutch 21 is preferably arranged between the freewheeling device 7 and the transmission 19. This clutch is configured to selectively connect or disconnect the freewheeling device 7, and thus in particular the internal combustion engine 5, from the transmission 19. The clutch 21 can be designed, in particular, as a hydraulic or electric clutch, which allows for particularly convenient and, in particular, automated control of the clutch 21.

[0057] The rotational speed associated with the propeller shaft 9, which ultimately determines, in comparison to the rotational speed of the internal combustion engine 5, whether the internal combustion engine 5 is coupled to the propeller shaft 9 via the freewheeling device 7 or not, is in particular the rotational speed of a drive shaft 22, which in the embodiment shown here is an input shaft of the shift clutch 21. Depending on the design of the transmission 19, this rotational speed of the drive shaft 22 can coincide with the rotational speed of the propeller shaft 9, i.e., the propeller shaft speed. However, it can also differ from it, especially if the transmission 19 is designed as a reduction or step-down transmission.In another embodiment of the watercraft 1, it is possible that the propeller shaft 9 can be coupled to the internal combustion engine 5, particularly without an intermediate gearbox, such that the propeller shaft 9 and the internal combustion engine 5 have identical rotational speeds when coupled. In this case, the drive shaft 22 is the propeller shaft 9, and the rotational speed associated with the propeller shaft 9 is directly the propeller shaft speed.

[0058] In a preferred embodiment, the freewheel device 7 is designed as an intermediate gear.

[0059] The bridging device 11 is preferably arranged on or integrated into the freewheeling device 7. However, according to the embodiment of the watercraft 1 and the drive 3 shown here, the bridging device 11 is arranged parallel to the freewheeling device 7.

[0060] Preferably, the bridging device 11 is designed as a coupling, in particular as a magnetic coupling.

[0061] It is possible that the watercraft 1 has two drives 3, preferably of identical design, which are arranged parallel to each other and separately from one another, for example one drive on the port side and one on the starboard side. Accordingly, the watercraft 1 then also has two propellers 13, each propeller 13 being assigned its own separate drive 3.

[0062] The watercraft 1 preferably also has a control unit 23 which is operatively connected to the bridging device 11 and configured to carry out a method described in more detail below. Preferably, the control unit 23 is also operatively connected to the clutch 21 and preferably to the transmission 19. In a manner not shown, the control unit is preferably also operatively connected to the internal combustion engine 5 and to the electric motor 15.

[0063] In a method for operating the watercraft 1, it is provided that during a braking maneuver to reduce the propeller shaft speed, the bypass device 11 is closed, so that the internal combustion engine 5 is coupled to the propeller shaft 9 and towed by the propeller shaft 9. In this way, the propeller shaft speed is reduced particularly quickly and effectively. Such a braking maneuver is preferably an emergency stop maneuver.

[0064] Fig. 2 Figure 1 shows a first implementation form of such a procedure for operating a watercraft.

[0065] In a first step S1, the watercraft 1 – abbreviated WFZ – is propelled before the braking maneuver either solely by the internal combustion engine 5 – abbreviated BKM – or jointly by the internal combustion engine 5 and the electric motor 15 – abbreviated EM. To initiate the braking maneuver, in a second step S2, the fuel supply to the internal combustion engine 5 is terminated, specifically, the injection for the diesel engine is stopped. In a third step S3, the bypass device 11 is closed, so that the internal combustion engine 5 is towed by the propeller shaft 9.

[0066] In a fourth step S4, the electric machine 15 is activated to decelerate the propeller shaft 9. Depending on whether the electric machine 15 was previously used to propel the watercraft 1 or whether it was at rest, its direction of rotation is reversed or it is newly activated. Preferably, the electric machine 15 is operated at full power to decelerate the propeller shaft 9 as quickly as possible, i.e., to reduce its rotational speed. The internal combustion engine 5 and the electric machine 15 then work together to reduce the propeller shaft speed, with the electric machine 15 actively introducing torque into the propeller shaft 9, while the internal combustion engine 5 is passively driven by the propeller shaft 9.

[0067] Once the internal combustion engine 5 reaches an idle speed, the clutch 21 is opened in a fifth step S5. Subsequently, in a sixth step S6, the internal combustion engine 5 is operated at idle.

[0068] In a seventh step S7, the gearbox 19 is now switched to the opposite direction of rotation to the previous direction of rotation, for example from forward to reverse - or vice versa.

[0069] Once the transmission 19 is engaged, the clutch 21 is closed in an eighth step S8, and in a ninth step S9 the propeller shaft 9 – now rotating in the opposite direction – is accelerated jointly by the internal combustion engine 5 and the electric motor 15, preferably each at maximum power. In this way, the braking process for the watercraft 1 can be carried out very effectively, quickly, and over a short distance.

[0070] Fig. 3Figure 1 shows a schematic representation of a second embodiment of the method. In this case, prior to the braking maneuver in a first step S1, the watercraft 1 is propelled only by the electric machine 15. The internal combustion engine 5 – in particular, the fuel supply to combustion chambers, especially to all combustion chambers of the internal combustion engine 5 – is stopped.

[0071] To initiate the braking maneuver, in a second step S2 the electric machine 15 is reversed, that is, its direction of rotation is changed, in order to decelerate the propeller shaft 9. Preferably, the electric machine 15 is operated at its maximum power to decelerate the propeller shaft 9 as quickly as possible. In a third step S3, the bypass device 11 is closed, so that the internal combustion engine 5 is also dragged by the propeller shaft 9. This reduces the propeller shaft speed further and more quickly than if it were decelerated solely by the electric machine 15.

[0072] Once the idle speed of the internal combustion engine 5 is reached, the clutch 21 is opened in a fourth step S4. In a fifth step S5, the internal combustion engine 5 is started, and in a sixth step S6 it is operated at idle.

[0073] In a seventh step S7, the transmission 21 is reversed to the opposite direction of rotation. Once this has occurred, in an eighth step S8 the clutch 21 is engaged, and in a ninth step S9 the propeller shaft – now in the opposite direction – is accelerated jointly by the internal combustion engine 5 and the electric motor 15 – preferably each at maximum power. With this embodiment of the method, a particularly rapid deceleration of the watercraft 1 over the shortest possible distance can also be achieved.

[0074] In the first embodiment of the method according to Figure 2 Steps S3 and S4 can also be performed simultaneously. Likewise, the second step S2 can be performed simultaneously with the third step S3 and the fourth step S4. In the second embodiment of the method according to Figure 3The second step S2 and the third step S3 can be performed simultaneously.

[0075] In the sixth step S6, according to both embodiments of the method, the Figures 2 and 3 When the internal combustion engine 5 is operated at idle, the electric machine 15 also rotates at the idle speed of the internal combustion engine 5 without outputting power, since it is connected to it via the freewheel device 7, in particular the intermediate gear.

Claims

1. Propulsion device (3) for a vehicle (2), in particular for a watercraft (1), with an internal combustion engine (5) und a freewheel device (7), wherein the internal combustion engine (3) can be connected in a drive-effective manner to a drive shaft (22) of the propulsion device (3) via the freewheel device (7), wherein the freewheel device (7) is adapted to decouple the internal combustion engine (5) from the drive shaft (22) when a rotational speed of the drive shaft (22) exceeds a rotational speed of the internal combustion engine (5), characterised in that the propulsion device comprises a bridging device (11) which is adapted to couple the internal combustion engine (5) to the drive shaft (22) in at least one operating situation of the propulsion device (3) when the internal combustion engine (5) is disconnected from the drive shaft (22) by the freewheel device (7).

2. Propulsion device (3) according to claim 1, characterised in that the propulsion device (3) additionally comprises an electric machine (15), wherein the internal combustion engine (5) and the electric machine (15) can be connected in a drive-effective manner to the drive shaft (22) via the freewheel device (7) in such a way that only the internal combustion engine (5), only the electric machine (15), or the internal combustion engine (5) and the electric machine (15) together can drive the drive shaft (22).

3. Propulsion device (3) according to one of the preceding claims, characterised in that the freewheel device (7) is designed a) as a mechanical freewheel, or b) as a gear device or as part of a gear device.

4. Propulsion device (3) according to one of the preceding claims, characterised in that the bridging device (11) a) is arranged on the freewheel device (7), or b) is integrated into the freewheel device (7), or c) is arranged parallel to the freewheel device (7).

5. Propulsion device (3) according to one of the preceding claims, characterised in that the bridging device (11) is designed as a clutch, in particular as a magnetic clutch.

6. Watercraft (1) with a propulsion device (3) according to one of claims 1 to 5, wherein the drive shaft (22) a) is a propeller shaft (9) of the watercraft (1), or wherein b) the drive shaft (22) can be connected or is connected to a propeller shaft (9) of the watercraft (1) in a drive-effective manner.

7. Watercraft (1) according to claim 6, characterised in that a shift gearbox (19) is arranged between the freewheel device (7) and the propeller (13) of the watercraft (1), wherein the shift gearbox (19) is adapted to reverse a direction of rotation of the propeller (13) relative to a direction of rotation of the internal combustion engine (5) when the shift gearbox (19) is shifted.

8. Method for operating a watercraft (1) according to one of claims 6 or 7, wherein, during a braking manoeuvre to reduce a rotational speed of the propeller shaft (9), the bridging device (11) is closed, wherein the internal combustion engine (5) is coupled to the propeller shaft (9) and is towed by the propeller shaft (9).

9. Method according to claim 8, characterised in that, prior to the braking manoeuvre, the watercraft (1) is driven only by the internal combustion engine (5) or by the electric machine (15) and the internal combustion engine (5) together, wherein the following steps are performed for the braking manoeuvre: a) stopping a fuel supply to the internal combustion engine (5), b) closing the bridging device (11); c) activating the electric machine (15) to decelerate the propeller shaft (9).

10. Method according to claim 8, characterised in that, prior to the braking manoeuvre, the watercraft (1) is driven only by the electric machine (15), wherein preferably the internal combustion engine (5) is stopped, wherein the following steps are performed for the braking manoeuvre: a) reversing the electric machine (15) to decelerate the propeller shaft (9), and b) closing the bridging device (11).

11. Control device (23) for a watercraft (1) which is adapted to carry out a method according to one of claims 8 to 10.

12. Watercraft (1) according to one of claims 6 and 7, with a control device (23) according to claim 11, wherein the control device (23) is operatively connected to the bridging device (11).