Method to carry out an emergency stop of a water vessel, control unit and water vessel

Abstract

The invention relates to a method for an emergency stop of a water vessel (100), wherein the water vessel comprises a propulsion system (1) with a combustion engine (2) as a first prime mover and an electric machine (3) as a second prime mover. The method comprising the following steps: • receiving (S1) an emergency stop request signal, • checking (S2) an on / off status of the combustion engine (2) and o if the combustion engine (2) is on, slowing down (S2a) combustion engine (2) to an idle mode and disengage the forward transmission clutch (6), o if the combustion engine (2) is off, starting (S2b) the combustion engine (2), • pivoting (S3) the propeller shaft (5) by approximately 180 degrees in a reverse direction, • engaging (S4) the forward transmission clutch (6), • setting (S5) the electric machine (3) to maximum drive power and the combustion engine (2) to full throttle. The invention is further related to a control unit (110), a propulsion system (1) and a water vessel (100) being configured to carry out such a method.

Description

Field of the Invention

[0001] The present invention relates to an emergency stop method for a water vessel with a propulsion system and to a control unit which is configured to carry out such a method. Besides the invention relates to a corresponding water vessel with such a propulsion system.Related Prior Art

[0002] Several solutions have been described in prior art to carry out an emergency stop or a crash stop of a water vessel, aiming at a stop of the water vessel within a short time and short distance, especially from high speed. In US 2022 / 0306259 A1 an emergency stop procedure is described, wherein a drag torque of an internal combustion engine and the torque of an electric machine are utilized together to brake a forward rotation of a propeller shaft especially quickly and to subsequently drive the propeller with full power of the internal combustion engine and the electric machine in the opposite direction of the previous direction of rotation.Objects of the Invention

[0003] It is an object of the present invention to provide an improved method for an emergency stop of a water vessel with a propulsion system and a control unit which is configured to carry out such a method.Disclosure of the Invention

[0004] The present invention provides a method to carry out an emergency stop of a water vessel, wherein the water vessel comprises a propulsion system with a combustion engine as a first prime mover and an electric machine as a second prime mover. Such a propulsion system is also called a hybrid propulsion system. The propulsion system further comprising at least one propeller which is mounted to a propeller shaft which is pivotable by at least 180 degrees about a vertical axis. In other words the underwater part of the propulsion system can be turned by 180 degrees about the vertical axis. Said at least one propeller can be driven by the combustion engine in a forward and reverse direction by selectively engaging a corresponding forward transmission clutch or a reverse transmission clutch. The electric machine can be permanently connected to the propeller shaft. The proposed method comprising the following steps: receiving an emergency stop request signal, for example from an HMI-device, disengaging the forward transmission clutch and the reverse transmission clutch, if any of these two clutches is engaged, pivoting the propeller shaft by approximately 180 degrees in a reverse direction, setting the electric machine to maximum drive power.

[0005] A first aspect of the invention is the fact, that the electric machine can start and effect the emergency stop very quick. When both transmission clutches are disengaged, it is ensured that the electric machine can act on the propeller shaft independent of the status of the combustion engine. The proposed method is particularly beneficial, if the propulsion system is a saildrive of a sailing ship. A sailing ship often sails with high speed during a sail cruising, typically up to 20-30 knots. In such condition the combustion engine is usually switched off. Preferably, the forward transmission clutch and the reverse transmission clutch are already disengaged during sail cruising, so that in case of an emergency stop request, the transmission clutches need not to be disengaged during the stop maneuver.

[0006] The emergency stop thrust can be provided from the electric machine in a very short time after the propeller shaft had been pivoted by 180 degrees to the reverse direction. The acceleration of an electric motor is generally greater than the acceleration of a combustion engine, due to the minor inertia of the rotation parts in an electric motor. Unlike combustion engines electric motors are not affected from any engine lag or turbo lag during acceleration and electric motors typically have a high starting torque. This way, the emergency stop thrust in the reverse direction can be provided within a few seconds after receiving the emergency stop request signal. That is much quicker compared to an emergency stop method in a classic application using a combustion engine for the emergency stop.

[0007] The invention relates to a method to carry out an emergency stop of a water vessel with a propulsion system including at least one steerable propeller, for example a Z-drive, an azimuth thruster, or a POD-drive. In such a propulsion system the steering is effected by pivoting the propeller about a substantially vertical axis through an azimuth angle which determines the main travelling direction. The pivoting of the propeller shaft by approximately 180 degrees in a reverse direction allows to use a maximum thrust efficiency at the propeller in its forward direction of rotation. Compared to the conventional methods to carry out an emergency stop which use the reverse the direction of rotation of the propeller, the efficiency can be increased by around 20%. The reversal of the direction of thrust without changing the rotational direction of the propeller uses effective conversion of mechanical energy into energy of flow at the propeller. The reason for this is that the optimal configuration of the propeller blade geometry is designed for only one direction of rotation. In an opposite direction of rotation of the propeller, the efficiency of energy conversation is lower than in the rotational direction for which the propeller blade geometry was designed and optimized. Accordingly, the propulsive force is greater compared to the propulsive force of a steerable propeller which is directed in a forward travelling direction and the propeller shaft is rotated in the reverse rotation direction.

[0008] One other aspect of the invention is the finding, that even so the water vessel is configured to be propelled during normal operation in a reverse gear by driving the propeller shaft in the opposite rotational direction by means of a reverse transmission clutch, in the case of an emergency stop it is more efficient to pivot the propeller shaft by 180 degrees around a vertical axis and to drive the propeller shaft in the same rotational direction as during the normal forward operation. In some electric or hybrid propulsion systems the electric machine is configured to drive the propeller shaft during normal operation in a forward or in a reverse rotational direction. However, during the emergency stop procedure the electric machine shall drive the propeller shaft in the same rotational direction as during the normal forward operation.

[0009] Although one aspect of the invention is the quick reaction time of the electric machine, the emergency stop can be supported by the combustion engine according to one embodiment of the invention. Therefore an on / off status of the combustion engine can be checked after receiving the emergency stop request signal. If the combustion engine is on, the combustion engine shall be slowed down to an idle mode. If the combustion engine is off, the combustion engine shall be started. These measures put the combustion engine in a state, where it can quickly build up an additional emergency stop thrust after the propeller shaft has been pivoted in the reverse direction.

[0010] Consecutively, the forward transmission clutch can be engaged in a next step, thereby connecting the combustion engine to the propeller shaft, and the combustion engine is set to full throttle after pivoting the propeller shaft by approximately 180 degrees in the reverse direction.

[0011] In other words, the emergency stop procedure can be initiated in a first phase very quick only by the electric machine, while the steps regarding the ICE can start at the same point in time but may take some more time to have effect. Hence, the combined power of the combustion engine and the electric motor provide a booster effect which increases the torque and propeller thrust and enables a very high-performance emergency stop.

[0012] In many cases the pivoting of the propeller shaft about the vertical axis in the reverse direction can be a turn of exactly 180 degrees. However, in some cases it may be a turn of the propeller shaft with a few degrees more or less than 180 degrees. Such an angular range of some degrees allows for corrections of the yaw angle and / or the heading of the water vessel during the emergency stop procedure.

[0013] According to a preferred implementation the pivoting of the propeller shaft by approximately 180 degrees is effected only if a rotation speed of the propeller shaft is below a preset threshold value. The preset threshold value can be at or near zero rpm of the propeller shaft. The rotation speed of the propeller shaft shall be reduced to avoid a significant or detrimental lateral thrust during the pivoting of the propeller shaft to the reverse direction. This way, a reduction of propeller speed or stop of the propeller rotation before the 180 degree pivoting shall ensure that a desired yaw angle of the water vessel can be maintained during the emergency stop procedure.

[0014] According to a further preferred method a braking torque is applied to the propeller shaft or to another shaft which is connected to the propeller shaft by the electric machine before the rotation speed of the propeller shaft has fallen under said preset threshold value. This way it is possible to stop the water vessel even quicker and in a shorter distance because the pivoting of the propeller shaft by approximately 180 degrees can be carried out earlier and propulsion in the reverse direction can be provided a short time after the emergency stop request signal has been received.

[0015] After the ground speed of the water vessel has been reduced to zero or to a value near zero, the electric machine can be switched off. For this a preferred method may comprise a step, wherein the electric machine is switched off, after the ground speed of the water vessel falls under a preset ground speed threshold which is at least approximately zero knots.

[0016] According to another preferred method the combustion engine is set to the idle mode and the forward transmission clutch is disengaged after the ground speed of the water vessel falls under a preset ground speed threshold which is at least approximately zero knots. A control unit may effect to switch off the electric machine, to set the combustion engine to idle mode and / or to disengage the forward transmission clutch, after the ground speed below the preset ground speed threshold has been determined.

[0017] One aspect of the present invention is related to a control unit being configured to carry out a method as described above. Such a control unit is configured to receive an emergency stop request signal, for example from the HMI device. The control unit is configured to carry out the other steps of the method described above, including the generation of appropriate command signals to command corresponding actions of the combustion engine, the electric machine, the forward transmission clutch. The control unit may comprise electronic components like a processor, data memory, communication interfaces for carrying out the method.

[0018] The invention is further related to a propulsion system for a water vessel comprising a combustion engine as a first prime mover and an electric machine as a second prime mover. Preferably the water vessel is a sailing ship or sailing boat. Hence, the propulsion system can be a saildrive. The propulsion system can be driven either by solely one of the first and second prime mover or by both together, depending on the corresponding operating mode. In a combustion mode the water vessel can be driven solely by the power of the combustion engine. In an electric propulsion mode the water vessel can be propelled solely by the electric machine at zero noise and zero emissions, especially during low-speed cruising and docking. In a combined mode the driven shaft may be driven by the combustion engine and the electric drive motor simultaneously.

[0019] The proposed propulsion system comprises at least one propeller mounted to a propeller shaft which is pivotable by at least 180 degrees about a vertical axis by means of a steering drive. The propulsion system further comprising a transmission with a forward transmission clutch and a reverse transmission clutch, wherein the at least one propeller can be driven either by the first prime mover, the second prime mover or by both prime movers together in a forward and reverse direction by selectively engaging forward transmission clutch or a reverse transmission clutch. The propulsion system further comprising a steering drive with a steering motor and a control unit which is configured to carry out a method for an emergency stop. Said control unit can generally be used to control the propulsion and steering of the water vessel.

[0020] An HMI-device, for example a button, control wheel, a control lever, a touch screen and / or a joystick, can be used for inputting the desired emergency stop maneuver. In one embodiment the emergency stop signal can also be received from a collision avoidance system instead of the HMI-device. An emergency stop signal would be initiated automatically from such such a collision avoidance system, when the system identifies an emergency stop as appropriate mean to avoid a collision with another water vessel or any other object.

[0021] Eventually the invention is related to a water vessel with a hybrid propulsion system, including a control unit which is configured to carry out a method as described above. The proposed emergency stop method can be applied particularly beneficial on a sailing ship which needs to be crash stopped during high-speed sailing.Brief Description of the Drawings

[0022] Figur 1schematically illustrates a propulsion system according to the invention and Figur 2shows a scheme of a method according to the invention. Detailed Description

[0023] The propulsion system 1 as shown in Fig. 1 comprises a combustion engine 2 as a first prime mover and an electric machine 3 as a second prime mover. An upper part of the propulsion system 1 including the combustion engine 2, an upper transmission 9 and the electric machine 3 is mounted in an engine room inside a hull 101 of a water vessel 100 which is a sailing ship in this embodiment. A lower part 12 of the propulsion system 1 including a propeller shaft 5 is mounted beneath the hull 101 in a pivotable manner with regard to the upper part of the propulsion system 1. Said lower part 12 is pivotable by at least 180 degrees about a vertical axis 24.

[0024] The propulsion system 1 comprising an input shaft 8 to the upper transmission 9. The input shaft 8 can be permanently connected to a crank shaft of the combustion engine 2. In alternative embodiments, there might be an additional input clutch to selectively connect and disconnect the crank shaft of the combustion engine 2 from the input shaft 8 of the upper transmission 9. The upper transmission 9 of the propulsion system 1 transmits propulsion power from the input shaft 8 to a vertical shaft 10, which is connected to a propeller shaft 5 via a lower transmission 11. A propeller 4 is fastened to the trailing end of the propeller shaft 5. Input shaft 8 and propeller shaft 5 are both essentially oriented in a horizontal direction. Each of the upper transmission 9 and the lower transmission 10 is comprising a set of bevel gears. The upper transmission 9 comprising a transmission housing 14 which encloses the corresponding set of bevel gears, a forward transmission clutch 6 and a reverse transmission clutch 7. The input shaft 8 can be selectively connected to the vertical shaft 10 by engaging either the forward transmission clutch 6 or the reverse transmission clutch 7. The forward transmission clutch 6 and the reverse transmission clutch 7 are pressure operated multi-disk clutches.

[0025] The propulsion system 1 further comprising an electric machine 3 with a motor shaft 13. The electric machine 3 is mounted on top of the transmission housing 14. The motor shaft 13 is arranged coaxial to the vertical shaft 10, so that the electric machine 3 is oriented in a vertical direction. The motor shaft 13 is rigidly connected to one of the bevel gears of the upper transmission 9. The motor shaft 13 of the electric machine 3 is permanently connected to the propeller shaft 5 via the upper transmission 9, the vertical shaft 10 and the lower transmission 11.

[0026] A steering unit 20 is provided to actuate a pivoting of the lower part 12 of the propulsion system 1 which is mounted beneath the hull 101 about the vertical axis 24. Hence, the propeller shaft 5 will pivot together with the lower part 12. The steering unit 20 comprises a steering motor 21 which is connected to a steering shaft 23 via a steering gear 22. The steering gear 22 comprises a planetary gear and two spur gear sets in order to transmit the relatively high rotation speed from the electric steering motor 21 to a lower rotation speed at the steering shaft 23. The steering shaft 23 is fixed to an underwater housing of the lower part 12. The propeller shaft 5 is supported in said underwater housing. The steering shaft 23 is a hollow shaft, wherein the vertical shaft 10 is arranged coaxial to the steering shaft 23 and the vertical shaft 10 is extending through a central bore of the steering shaft 23.

[0027] A control unit 110 of the propulsion system 1 is configured to control the operation of the combustion engine 2, the electric machine 3 and the forward transmission clutch 6 and the reverse transmission clutch 7. For this, the control unit 110 is connected to appropriate control elements of the combustion engine 2, the forward and reverse transmission clutch 6 and 7 and to the electric machine 3.

[0028] Said control unit 110 is configured to control operation of the propulsion system 1 in several operating modes. In a first operating mode solely the combustion engine 2 is used for propulsion, i.e. to drive the propeller shaft 5 with the propeller 4. In a second operating mode solely the electric machine 3 is used for propulsion. In a third operating mode the combustion engine 2 and the electric machine 3 are simultaneously used for propulsion. In a fourth operating mode the combustion engine 2 is used for propulsion and for driving the electric machine 3 to generate electric energy. The control unit 110 is configured to carry out a method for an emergency stop of the water vessel 100 as described above. The control unit 110 is connected to an HMI-device 111 which is installed on board of the water vehicle 100 to receive requests and commands from a steersman or any other member of a ship's crew.

[0029] Fig. 2 schematically shows a method for carrying out an emergency stop of a water vessel 100. The method comprises a first step S1 wherein an emergency stop signal is received from an HMI-device 111. Such an emergency stop signal may be initiated by means of the HMI-device 111 by a steersman or another member of a ship's crew. The method shown in Fig. 2 includes a step S1a, wherein a braking torque is applied to the propeller shaft 5 or a connected shaft by the electric machine 3 before and until the rotation speed of the propeller shaft 5 has fallen under a preset threshold value. This can be effected by operating the electric machine 3 in a generator mode, generating electric energy which can be used to charge a battery on board of the water vessel 100.

[0030] In step S2 the forward transmission clutch 6 and the reverse transmission clutch 7 are disengaged, if one of these clutches 6 and 7 was engaged at that time. This way is ensured, that the connection between the combustion engine 2 and the propeller shaft 5 is disconnected and the electric machine 3 can drive the propeller shaft 5 independent from the status of the combustion engine 2. Steps S1a and S2 can be carried out simultaneously or in either order.

[0031] In a next step S3 the lower part 12 of the propulsion system 1 together with the propeller shaft 5 is pivoted by approximately 180 degrees in a reverse direction. In a preferred version of the method, the step S3 can be carried out only, if a rotation speed of the propeller shaft 5 has been detected to be below a preset threshold value.

[0032] After the propeller shaft 5 has been pivoted around the vertical axis 24 to the reverse direction, the electric machine 3 is set to maximum drive power in the following step S4, to provide thrust in reverse direction at the propeller 4.

[0033] The method as shown in Fig. 2 further comprises a step S5 of checking a status of the combustion engine 2. This step S5 can be initiated immediately after receiving the emergency stop request signal in step S1, so that the following steps S5a, S5b, S6 and S7 may run in parallel with the steps S2, S3 and S4. The abbreviation ICE in Fig. 2 means an internal combustion engine and is used for combustion engine 2. The combustion engine 2 may be running, i.e. in an on-status or it may be switched off, i.e. in an off-status. Depending on the status of the combustion engine either a step S5a or a step S5b will be initiated. If the combustion engine 2 is on, the combustion engine 2 shall be slowed down to an idle mode in step S5a. If, in the other case, the combustion engine 2 is off, it shall be started in step S5b and operated in an idle mode.

[0034] A further step S6 the forward transmission clutch 6 is engaged, so that the combustion engine 2 is drivingly connected to the propeller shaft 5. Step S6 shall only be carried out after S3, so that the propeller shaft 5 has already been pivoted in the reverse direction before the forward transmission clutch 6 is engaged.

[0035] In a further step S7 the combustion engine 2 is set to full throttle to support the electric machine 3 with its power to drive the propeller 4 in the desired direction to stop the water vessel 100 as quick as possible.

[0036] Eventually the electric machine 3 is switched off and the combustion engine 3 is set to idle mode in Step S8, after the water vehicle is stopped, i.e. after the ground speed of the water vessel 100 falls under a preset ground speed threshold which is close to zero knots or exactly zero knots.

[0037] By carrying out the steps of the proposed method, the combined power of the first and second prime mover can be used to propel the water vessel 100 in the reverse direction and to stop it very quickly, after an emergency stop request signal has been initiated.Bezuqszeichen

[0038] 1propulsion system 2combustion engine 3electric machine 4propeller 5propeller shaft 6forward transmission clutch 7reverse transmission clutch 8input shaft 9upper transmission 10vertical shaft 11lower transmission 12lower part 13motor shaft 14transmission housing 20steering unit 21steering motor 22steering gear 23steering shaft 24vertical axis 100water vessel 101hull 110control unit 111HMI device S1Receiving emergency stop signal S1aApplying a braking torque to the propeller shaft by the electric machine S2disengaging the forward or reverse transmission clutch S3Pivoting the propeller shaft by approximately 180 degrees S4Setting electric machine to maximum drive power S5Checking status of combustion engine S6Engaging forward transmission clutch S7setting ICE to full throttle S8switching off the electric machine and setting the combustion engine to idle mode

Examples

Embodiment Construction

[0023]The propulsion system 1 as shown in Fig. 1 comprises a combustion engine 2 as a first prime mover and an electric machine 3 as a second prime mover. An upper part of the propulsion system 1 including the combustion engine 2, an upper transmission 9 and the electric machine 3 is mounted in an engine room inside a hull 101 of a water vessel 100 which is a sailing ship in this embodiment. A lower part 12 of the propulsion system 1 including a propeller shaft 5 is mounted beneath the hull 101 in a pivotable manner with regard to the upper part of the propulsion system 1. Said lower part 12 is pivotable by at least 180 degrees about a vertical axis 24.

[0024]The propulsion system 1 comprising an input shaft 8 to the upper transmission 9. The input shaft 8 can be permanently connected to a crank shaft of the combustion engine 2. In alternative embodiments, there might be an additional input clutch to selectively connect and disconnect the crank shaft of the combustion engine 2 from t...

Field of the Invention

[0001] The present invention relates to an emergency stop method for a water vessel with a propulsion system and to a control unit which is configured to carry out such a method. Besides the invention relates to a corresponding water vessel with such a propulsion system.Related Prior Art

[0002] Several solutions have been described in prior art to carry out an emergency stop or a crash stop of a water vessel, aiming at a stop of the water vessel within a short time and short distance, especially from high speed. In US 2022 / 0306259 A1 an emergency stop procedure is described, wherein a drag torque of an internal combustion engine and the torque of an electric machine are utilized together to brake a forward rotation of a propeller shaft especially quickly and to subsequently drive the propeller with full power of the internal combustion engine and the electric machine in the opposite direction of the previous direction of rotation.Objects of the Invention

[0003] It is an object of the present invention to provide an improved method for an emergency stop of a water vessel with a propulsion system and a control unit which is configured to carry out such a method.Disclosure of the Invention

[0004] The present invention provides a method to carry out an emergency stop of a water vessel, wherein the water vessel comprises a propulsion system with a combustion engine as a first prime mover and an electric machine as a second prime mover. Such a propulsion system is also called a hybrid propulsion system. The propulsion system further comprising at least one propeller which is mounted to a propeller shaft which is pivotable by at least 180 degrees about a vertical axis. In other words the underwater part of the propulsion system can be turned by 180 degrees about the vertical axis. Said at least one propeller can be driven by the combustion engine in a forward and reverse direction by selectively engaging a corresponding forward transmission clutch or a reverse transmission clutch. The electric machine can be permanently connected to the propeller shaft. The proposed method comprising the following steps: receiving an emergency stop request signal, for example from an HMI-device, disengaging the forward transmission clutch and the reverse transmission clutch, if any of these two clutches is engaged, pivoting the propeller shaft by approximately 180 degrees in a reverse direction, setting the electric machine to maximum drive power.

[0005] A first aspect of the invention is the fact, that the electric machine can start and effect the emergency stop very quick. When both transmission clutches are disengaged, it is ensured that the electric machine can act on the propeller shaft independent of the status of the combustion engine. The proposed method is particularly beneficial, if the propulsion system is a saildrive of a sailing ship. A sailing ship often sails with high speed during a sail cruising, typically up to 20-30 knots. In such condition the combustion engine is usually switched off. Preferably, the forward transmission clutch and the reverse transmission clutch are already disengaged during sail cruising, so that in case of an emergency stop request, the transmission clutches need not to be disengaged during the stop maneuver.

[0006] The emergency stop thrust can be provided from the electric machine in a very short time after the propeller shaft had been pivoted by 180 degrees to the reverse direction. The acceleration of an electric motor is generally greater than the acceleration of a combustion engine, due to the minor inertia of the rotation parts in an electric motor. Unlike combustion engines electric motors are not affected from any engine lag or turbo lag during acceleration and electric motors typically have a high starting torque. This way, the emergency stop thrust in the reverse direction can be provided within a few seconds after receiving the emergency stop request signal. That is much quicker compared to an emergency stop method in a classic application using a combustion engine for the emergency stop.

[0007] The invention relates to a method to carry out an emergency stop of a water vessel with a propulsion system including at least one steerable propeller, for example a Z-drive, an azimuth thruster, or a POD-drive. In such a propulsion system the steering is effected by pivoting the propeller about a substantially vertical axis through an azimuth angle which determines the main travelling direction. The pivoting of the propeller shaft by approximately 180 degrees in a reverse direction allows to use a maximum thrust efficiency at the propeller in its forward direction of rotation. Compared to the conventional methods to carry out an emergency stop which use the reverse the direction of rotation of the propeller, the efficiency can be increased by around 20%. The reversal of the direction of thrust without changing the rotational direction of the propeller uses effective conversion of mechanical energy into energy of flow at the propeller. The reason for this is that the optimal configuration of the propeller blade geometry is designed for only one direction of rotation. In an opposite direction of rotation of the propeller, the efficiency of energy conversation is lower than in the rotational direction for which the propeller blade geometry was designed and optimized. Accordingly, the propulsive force is greater compared to the propulsive force of a steerable propeller which is directed in a forward travelling direction and the propeller shaft is rotated in the reverse rotation direction.

[0008] One other aspect of the invention is the finding, that even so the water vessel is configured to be propelled during normal operation in a reverse gear by driving the propeller shaft in the opposite rotational direction by means of a reverse transmission clutch, in the case of an emergency stop it is more efficient to pivot the propeller shaft by 180 degrees around a vertical axis and to drive the propeller shaft in the same rotational direction as during the normal forward operation. In some electric or hybrid propulsion systems the electric machine is configured to drive the propeller shaft during normal operation in a forward or in a reverse rotational direction. However, during the emergency stop procedure the electric machine shall drive the propeller shaft in the same rotational direction as during the normal forward operation.

[0009] Although one aspect of the invention is the quick reaction time of the electric machine, the emergency stop can be supported by the combustion engine according to one embodiment of the invention. Therefore an on / off status of the combustion engine can be checked after receiving the emergency stop request signal. If the combustion engine is on, the combustion engine shall be slowed down to an idle mode. If the combustion engine is off, the combustion engine shall be started. These measures put the combustion engine in a state, where it can quickly build up an additional emergency stop thrust after the propeller shaft has been pivoted in the reverse direction.

[0010] Consecutively, the forward transmission clutch can be engaged in a next step, thereby connecting the combustion engine to the propeller shaft, and the combustion engine is set to full throttle after pivoting the propeller shaft by approximately 180 degrees in the reverse direction.

[0011] In other words, the emergency stop procedure can be initiated in a first phase very quick only by the electric machine, while the steps regarding the ICE can start at the same point in time but may take some more time to have effect. Hence, the combined power of the combustion engine and the electric motor provide a booster effect which increases the torque and propeller thrust and enables a very high-performance emergency stop.

[0012] In many cases the pivoting of the propeller shaft about the vertical axis in the reverse direction can be a turn of exactly 180 degrees. However, in some cases it may be a turn of the propeller shaft with a few degrees more or less than 180 degrees. Such an angular range of some degrees allows for corrections of the yaw angle and / or the heading of the water vessel during the emergency stop procedure.

[0013] According to a preferred implementation the pivoting of the propeller shaft by approximately 180 degrees is effected only if a rotation speed of the propeller shaft is below a preset threshold value. The preset threshold value can be at or near zero rpm of the propeller shaft. The rotation speed of the propeller shaft shall be reduced to avoid a significant or detrimental lateral thrust during the pivoting of the propeller shaft to the reverse direction. This way, a reduction of propeller speed or stop of the propeller rotation before the 180 degree pivoting shall ensure that a desired yaw angle of the water vessel can be maintained during the emergency stop procedure.

[0014] According to a further preferred method a braking torque is applied to the propeller shaft or to another shaft which is connected to the propeller shaft by the electric machine before the rotation speed of the propeller shaft has fallen under said preset threshold value. This way it is possible to stop the water vessel even quicker and in a shorter distance because the pivoting of the propeller shaft by approximately 180 degrees can be carried out earlier and propulsion in the reverse direction can be provided a short time after the emergency stop request signal has been received.

[0015] After the ground speed of the water vessel has been reduced to zero or to a value near zero, the electric machine can be switched off. For this a preferred method may comprise a step, wherein the electric machine is switched off, after the ground speed of the water vessel falls under a preset ground speed threshold which is at least approximately zero knots.

[0016] According to another preferred method the combustion engine is set to the idle mode and the forward transmission clutch is disengaged after the ground speed of the water vessel falls under a preset ground speed threshold which is at least approximately zero knots. A control unit may effect to switch off the electric machine, to set the combustion engine to idle mode and / or to disengage the forward transmission clutch, after the ground speed below the preset ground speed threshold has been determined.

[0017] One aspect of the present invention is related to a control unit being configured to carry out a method as described above. Such a control unit is configured to receive an emergency stop request signal, for example from the HMI device. The control unit is configured to carry out the other steps of the method described above, including the generation of appropriate command signals to command corresponding actions of the combustion engine, the electric machine, the forward transmission clutch. The control unit may comprise electronic components like a processor, data memory, communication interfaces for carrying out the method.

[0018] The invention is further related to a propulsion system for a water vessel comprising a combustion engine as a first prime mover and an electric machine as a second prime mover. Preferably the water vessel is a sailing ship or sailing boat. Hence, the propulsion system can be a saildrive. The propulsion system can be driven either by solely one of the first and second prime mover or by both together, depending on the corresponding operating mode. In a combustion mode the water vessel can be driven solely by the power of the combustion engine. In an electric propulsion mode the water vessel can be propelled solely by the electric machine at zero noise and zero emissions, especially during low-speed cruising and docking. In a combined mode the driven shaft may be driven by the combustion engine and the electric drive motor simultaneously.

[0019] The proposed propulsion system comprises at least one propeller mounted to a propeller shaft which is pivotable by at least 180 degrees about a vertical axis by means of a steering drive. The propulsion system further comprising a transmission with a forward transmission clutch and a reverse transmission clutch, wherein the at least one propeller can be driven either by the first prime mover, the second prime mover or by both prime movers together in a forward and reverse direction by selectively engaging forward transmission clutch or a reverse transmission clutch. The propulsion system further comprising a steering drive with a steering motor and a control unit which is configured to carry out a method for an emergency stop. Said control unit can generally be used to control the propulsion and steering of the water vessel.

[0020] An HMI-device, for example a button, control wheel, a control lever, a touch screen and / or a joystick, can be used for inputting the desired emergency stop maneuver. In one embodiment the emergency stop signal can also be received from a collision avoidance system instead of the HMI-device. An emergency stop signal would be initiated automatically from such such a collision avoidance system, when the system identifies an emergency stop as appropriate mean to avoid a collision with another water vessel or any other object.

[0021] Eventually the invention is related to a water vessel with a hybrid propulsion system, including a control unit which is configured to carry out a method as described above. The proposed emergency stop method can be applied particularly beneficial on a sailing ship which needs to be crash stopped during high-speed sailing.Brief Description of the Drawings

[0022] Figur 1schematically illustrates a propulsion system according to the invention and Figur 2shows a scheme of a method according to the invention. Detailed Description

[0023] The propulsion system 1 as shown in Fig. 1 comprises a combustion engine 2 as a first prime mover and an electric machine 3 as a second prime mover. An upper part of the propulsion system 1 including the combustion engine 2, an upper transmission 9 and the electric machine 3 is mounted in an engine room inside a hull 101 of a water vessel 100 which is a sailing ship in this embodiment. A lower part 12 of the propulsion system 1 including a propeller shaft 5 is mounted beneath the hull 101 in a pivotable manner with regard to the upper part of the propulsion system 1. Said lower part 12 is pivotable by at least 180 degrees about a vertical axis 24.

[0024] The propulsion system 1 comprising an input shaft 8 to the upper transmission 9. The input shaft 8 can be permanently connected to a crank shaft of the combustion engine 2. In alternative embodiments, there might be an additional input clutch to selectively connect and disconnect the crank shaft of the combustion engine 2 from the input shaft 8 of the upper transmission 9. The upper transmission 9 of the propulsion system 1 transmits propulsion power from the input shaft 8 to a vertical shaft 10, which is connected to a propeller shaft 5 via a lower transmission 11. A propeller 4 is fastened to the trailing end of the propeller shaft 5. Input shaft 8 and propeller shaft 5 are both essentially oriented in a horizontal direction. Each of the upper transmission 9 and the lower transmission 10 is comprising a set of bevel gears. The upper transmission 9 comprising a transmission housing 14 which encloses the corresponding set of bevel gears, a forward transmission clutch 6 and a reverse transmission clutch 7. The input shaft 8 can be selectively connected to the vertical shaft 10 by engaging either the forward transmission clutch 6 or the reverse transmission clutch 7. The forward transmission clutch 6 and the reverse transmission clutch 7 are pressure operated multi-disk clutches.

[0025] The propulsion system 1 further comprising an electric machine 3 with a motor shaft 13. The electric machine 3 is mounted on top of the transmission housing 14. The motor shaft 13 is arranged coaxial to the vertical shaft 10, so that the electric machine 3 is oriented in a vertical direction. The motor shaft 13 is rigidly connected to one of the bevel gears of the upper transmission 9. The motor shaft 13 of the electric machine 3 is permanently connected to the propeller shaft 5 via the upper transmission 9, the vertical shaft 10 and the lower transmission 11.

[0026] A steering unit 20 is provided to actuate a pivoting of the lower part 12 of the propulsion system 1 which is mounted beneath the hull 101 about the vertical axis 24. Hence, the propeller shaft 5 will pivot together with the lower part 12. The steering unit 20 comprises a steering motor 21 which is connected to a steering shaft 23 via a steering gear 22. The steering gear 22 comprises a planetary gear and two spur gear sets in order to transmit the relatively high rotation speed from the electric steering motor 21 to a lower rotation speed at the steering shaft 23. The steering shaft 23 is fixed to an underwater housing of the lower part 12. The propeller shaft 5 is supported in said underwater housing. The steering shaft 23 is a hollow shaft, wherein the vertical shaft 10 is arranged coaxial to the steering shaft 23 and the vertical shaft 10 is extending through a central bore of the steering shaft 23.

[0027] A control unit 110 of the propulsion system 1 is configured to control the operation of the combustion engine 2, the electric machine 3 and the forward transmission clutch 6 and the reverse transmission clutch 7. For this, the control unit 110 is connected to appropriate control elements of the combustion engine 2, the forward and reverse transmission clutch 6 and 7 and to the electric machine 3.

[0028] Said control unit 110 is configured to control operation of the propulsion system 1 in several operating modes. In a first operating mode solely the combustion engine 2 is used for propulsion, i.e. to drive the propeller shaft 5 with the propeller 4. In a second operating mode solely the electric machine 3 is used for propulsion. In a third operating mode the combustion engine 2 and the electric machine 3 are simultaneously used for propulsion. In a fourth operating mode the combustion engine 2 is used for propulsion and for driving the electric machine 3 to generate electric energy. The control unit 110 is configured to carry out a method for an emergency stop of the water vessel 100 as described above. The control unit 110 is connected to an HMI-device 111 which is installed on board of the water vehicle 100 to receive requests and commands from a steersman or any other member of a ship's crew.

[0029] Fig. 2 schematically shows a method for carrying out an emergency stop of a water vessel 100. The method comprises a first step S1 wherein an emergency stop signal is received from an HMI-device 111. Such an emergency stop signal may be initiated by means of the HMI-device 111 by a steersman or another member of a ship's crew. The method shown in Fig. 2 includes a step S1a, wherein a braking torque is applied to the propeller shaft 5 or a connected shaft by the electric machine 3 before and until the rotation speed of the propeller shaft 5 has fallen under a preset threshold value. This can be effected by operating the electric machine 3 in a generator mode, generating electric energy which can be used to charge a battery on board of the water vessel 100.

[0030] In step S2 the forward transmission clutch 6 and the reverse transmission clutch 7 are disengaged, if one of these clutches 6 and 7 was engaged at that time. This way is ensured, that the connection between the combustion engine 2 and the propeller shaft 5 is disconnected and the electric machine 3 can drive the propeller shaft 5 independent from the status of the combustion engine 2. Steps S1a and S2 can be carried out simultaneously or in either order.

[0031] In a next step S3 the lower part 12 of the propulsion system 1 together with the propeller shaft 5 is pivoted by approximately 180 degrees in a reverse direction. In a preferred version of the method, the step S3 can be carried out only, if a rotation speed of the propeller shaft 5 has been detected to be below a preset threshold value.

[0032] After the propeller shaft 5 has been pivoted around the vertical axis 24 to the reverse direction, the electric machine 3 is set to maximum drive power in the following step S4, to provide thrust in reverse direction at the propeller 4.

[0033] The method as shown in Fig. 2 further comprises a step S5 of checking a status of the combustion engine 2. This step S5 can be initiated immediately after receiving the emergency stop request signal in step S1, so that the following steps S5a, S5b, S6 and S7 may run in parallel with the steps S2, S3 and S4. The abbreviation ICE in Fig. 2 means an internal combustion engine and is used for combustion engine 2. The combustion engine 2 may be running, i.e. in an on-status or it may be switched off, i.e. in an off-status. Depending on the status of the combustion engine either a step S5a or a step S5b will be initiated. If the combustion engine 2 is on, the combustion engine 2 shall be slowed down to an idle mode in step S5a. If, in the other case, the combustion engine 2 is off, it shall be started in step S5b and operated in an idle mode.

[0034] A further step S6 the forward transmission clutch 6 is engaged, so that the combustion engine 2 is drivingly connected to the propeller shaft 5. Step S6 shall only be carried out after S3, so that the propeller shaft 5 has already been pivoted in the reverse direction before the forward transmission clutch 6 is engaged.

[0035] In a further step S7 the combustion engine 2 is set to full throttle to support the electric machine 3 with its power to drive the propeller 4 in the desired direction to stop the water vessel 100 as quick as possible.

[0036] Eventually the electric machine 3 is switched off and the combustion engine 3 is set to idle mode in Step S8, after the water vehicle is stopped, i.e. after the ground speed of the water vessel 100 falls under a preset ground speed threshold which is close to zero knots or exactly zero knots.

[0037] By carrying out the steps of the proposed method, the combined power of the first and second prime mover can be used to propel the water vessel 100 in the reverse direction and to stop it very quickly, after an emergency stop request signal has been initiated.Bezuqszeichen

[0038] 1propulsion system 2combustion engine 3electric machine 4propeller 5propeller shaft 6forward transmission clutch 7reverse transmission clutch 8input shaft 9upper transmission 10vertical shaft 11lower transmission 12lower part 13motor shaft 14transmission housing 20steering unit 21steering motor 22steering gear 23steering shaft 24vertical axis 100water vessel 101hull 110control unit 111HMI device S1Receiving emergency stop signal S1aApplying a braking torque to the propeller shaft by the electric machine S2disengaging the forward or reverse transmission clutch S3Pivoting the propeller shaft by approximately 180 degrees S4Setting electric machine to maximum drive power S5Checking status of combustion engine S6Engaging forward transmission clutch S7setting ICE to full throttle S8switching off the electric machine and setting the combustion engine to idle mode

Examples

Embodiment Construction

[0023]The propulsion system 1 as shown in Fig. 1 comprises a combustion engine 2 as a first prime mover and an electric machine 3 as a second prime mover. An upper part of the propulsion system 1 including the combustion engine 2, an upper transmission 9 and the electric machine 3 is mounted in an engine room inside a hull 101 of a water vessel 100 which is a sailing ship in this embodiment. A lower part 12 of the propulsion system 1 including a propeller shaft 5 is mounted beneath the hull 101 in a pivotable manner with regard to the upper part of the propulsion system 1. Said lower part 12 is pivotable by at least 180 degrees about a vertical axis 24.

[0024]The propulsion system 1 comprising an input shaft 8 to the upper transmission 9. The input shaft 8 can be permanently connected to a crank shaft of the combustion engine 2. In alternative embodiments, there might be an additional input clutch to selectively connect and disconnect the crank shaft of the combustion engine 2 from t...

Claims

1. Method for an emergency stop of a water vessel (100), wherein the water vessel comprises a propulsion system (1) with a combustion engine (2) as a first prime mover and an electric machine (3) as a second prime mover, at least one propeller (4) which is mounted to a propeller shaft (5) which is pivotable by at least 180 degrees about a vertical axis (24), and wherein the at least one propeller (4) can be driven by the combustion engine (2) in a forward and reverse direction by selectively engaging a corresponding forward transmission clutch (6) or a reverse transmission clutch (7), the method comprising the following steps: • receiving (S1) an emergency stop request signal, • if one of the forward transmission clutch (6) and the reverse transmission clutch (7) is engaged, disengaging (S2) the corresponding forward or reverse transmission clutch (6, 7), • pivoting (S3) the propeller shaft (5) by approximately 180 degrees in a reverse direction, • setting (S4) the electric machine (3) to maximum drive power.

2. Method according to claim 1, wherein an on / off status of the combustion engine (2) is checked (S5) after receiving (S1) the emergency stop request signal and ∘ if the combustion engine (2) is on, slowing down (S5a) the combustion engine (2) to an idle mode, ∘ if the combustion engine (2) is off, starting (S5b) the combustion engine (2).

3. Method according to claim 1 or 2, wherein the forward transmission clutch (6) is engaged (S6) and the combustion engine (2) is set to full throttle (S7) after pivoting (S3) the propeller shaft (5) by approximately 180 degrees in the reverse direction.

4. Method according to one of the preceding claims, wherein the pivoting (S3) of the propeller shaft (5) by approximately 180 degrees is effected, when a rotation speed of the propeller shaft (5) is below a preset threshold value.

5. Method according to claim 4, wherein a braking torque is applied (S1 a) to the propeller shaft (5) or a connected shaft by the electric machine (3) before the rotation speed of the propeller shaft (5) has fallen under the preset threshold value.

6. Method according to one of the preceding claims, wherein the electric machine (3) is switched off (S8), after the ground speed of the water vessel (100) falls under a preset ground speed threshold which is at least approximately zero knots.

7. Method according to one of the preceding claims, wherein the combustion engine (2) is set to the idle mode (S9) and the forward transmission clutch (6) is disengaged, after the ground speed of the water vessel (100) falls under a preset ground speed threshold which is at least approximately zero knots.

8. Control unit (110) being configured to carry out a method according to one of the preceding claims.

9. Propulsion system (1) for a water vessel (100) comprising • a combustion engine (2) as a first prime mover, • an electric machine (3) as a second prime mover, • at least one propeller (4) mounted to a propeller shaft (5) which is pivotable by at least 180 degrees about a vertical axis (24), • a steering unit (20) comprising a steering motor (21) • an upper transmission (9) with a forward transmission clutch (6) and a reverse transmission clutch (7), wherein the at least one propeller can be driven either by the first prime mover, the second prime mover or by both prime movers together in a forward and reverse direction by selectively engaging forward transmission clutch (6) or a reverse transmission clutch (7), and the propulsion system (1) further comprising a control unit (110) according to claim 8.

10. Water vessel (100) with a propulsion system (1) according to claim 9.

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