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The present invention relates to a marine hybrid transmission and to a marine hybrid drive unit.
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Conventional marine drives comprise a combustion engine, which can be mounted inside a hull of a ship. The power from the combustion engine is transmitted via a drive train with shafts and transmission elements to one or two propellers, which are fixed to a propeller shaft. Typically a forward and a reverse clutch are arranged in the drive train, to realize forward and reverse rotation directions of the propeller shaft.
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In recent years there is an increasing demand for marine drive units with electric drive machines for environmental and efficiency reasons. For these reasons several marine drive units have been proposed in form of hybrid drives comprising a combustion engine and an electric machine for driving the water vessel.
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In the
EP 2 396 219 A1 a hybrid marine power train with a combustion engine and an electric motor has been disclosed. A transmission input shaft can be driven by the combustion engine or by the electric motor and the drive power is transmitted from a first input shaft via a clutch to a main shaft and further to an output shaft. The electric motor can be connected to the first input shaft via a second input shaft.
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The purpose of the present invention is to provide an improved marine hybrid transmission with a high level of reliability and a broad range of applicability.
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This purpose is achieved by a marine hybrid transmission according to claim 1 and by a marine hybrid drive unit according to claim 5. Further embodiments are claimed in dependent claims.
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The present invention provides a marine hybrid transmission comprising a housing, a first input shaft to be connected to a combustion engine, a second input shaft to be connected to an electric machine and an output shaft to be connected to a propeller shaft. All three shafts can be supported in the housing and be enclosed at least partially by the housing. The first input shaft is arranged coaxially to the second input shaft. The first input shaft may as well be arranged coaxial to a motor shaft of the electric machine. The electric machine can be fastened to the marine hybrid transmission on the opposite side of the combustion engine, wherein the motor shaft of the electric machine is coaxial to a crank shaft of the combustion engine. With other words the combustion engine and the electric motor are aligned to each other in an axial direction. This arrangement allows a very slim layout in axial direction, which is a compact design and beneficial especially to be installed in boats with a slim outline of the hull. The current invention can be used for a hybrid sail drive with an optimal integration of the combustion engine and the electric machine inside the hull of a sailboat.
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The marine hybrid transmission further comprising a first clutch and a second clutch to transmit driving power from the first input shaft to the output shaft. The driving power will be further transmitted via the propeller shaft to a propeller and effect the propulsion of the water vessel in a forward or reverse direction. The driving power of the combustion engine can therefore be transmitted selectively in a forward or reverse direction by engaging either the first clutch or the second clutch. Engaging the first clutch may effect a rotation of the output shaft in a forward direction and an engagement of the second clutch may effect a rotation of the output shaft in a reverse direction. However, the rotating directions can also be related vice versa.
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The first clutch comprises a first clutch input part and a first clutch output part and the second clutch comprises a second clutch input part and a second clutch output part. Both clutches are preferably pressure actuated multi-disk clutches. Hence, the first and second input parts and output parts can be disk carriers. The first and second clutch input parts can be outer disk carriers and the first and second clutch output parts can be inner disk carriers.
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The first input shaft is permanently connected to the first clutch input part and the second clutch input part, while the first clutch output part and the second clutch output part are permanently connected to the output shaft. According to the invention the second input shaft is permanently connected to the second clutch output part.
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This means, that the electric machine is connected to the output shaft and can drive the output shaft and the propeller shaft independent from the status of the first and second clutch. In other words, the driving power from the electric machine can be transmitted directly from the second input shaft via the second clutch output part and to the output shaft. There is no power flow through the first or the second clutch, when the marine hybrid drive is driven electrically, i.e. solely by the electric machine.
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For example in case of a failure in the pressure supply to such the pressure actuated first and second clutch, the power from the first input shaft cannot be transmitted to the output shaft. The present invention enables to drive the output shaft in such a situation solely by the electric machine via the second input shaft. This way, the electric machine provides for a backup solution in case of failure or lack of the main propulsion from the combustion engine or a failure of the clutch. Hence, the reliability of the marine hybrid transmission and the corresponding marine hybrid drive is increased.
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The electric machine alone can drive the output shaft in a forward or in a reverse direction when the first clutch and the second clutch are disengaged. This way an electric cruising is enabled, especially to cruise protected areas with low noise and zero emission. It is possible to operate the marine hybrid drive in an Eco-mode, wherein the combustion engine only runs when power requirements exceed the renewable sources and available battery capacity.
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Another mode of operation is a booster-mode, which adds the output power of the electric machine to the combustion engine power output. This is possible during operation in full power and in intermediate power output. In intermediate power output it is possible to get the best efficiency and fuel saving of the combustion engine by using the electric machine for small accelerations or changes in speed.
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Another possible operation mode is a first generating mode. Therefore the electric machine is operated in a mode to generate electric energy for charging a battery or to provide electric energy to other consumers on the water vessel. If the marine hybrid transmission is installed on a sailboat, the output shaft can rotate for the effect of the propeller and effect a so-called hydrogeneration during sailing. Such a first generating mode requires that a sailboat speed is greater than 3-4 knots to comport a rotation of the propeller for the drag effect at the propeller. A second electric generating mode will be described further below with regard to a third and a fourth clutch.
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An appropriate power rating of the electric machine may be in a range between 15 and 100 kW. The electric machine can be operated on low voltage, for example on 48 Volt, or on high voltage, for example in a range between 360 to 400 Volt.
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Another aspect of the invention is related to the general layout of the corresponding marine drive. The invention may be preferably be applied in so-called Z-drives, POD-drives or thrusters. In such marine drives the driving power of the drive machines typically is transmitted via an upper bevel gear set, a vertical shaft and a lower bevel gear set to a propeller shaft. At a trailing end of the propeller shaft a rear propeller of a POD can be fastened, as one example. The input shaft and the propeller shaft of such marine drives are oriented in a horizontal direction. The terms horizontal and vertical refer to a marine hybrid transmission operably installed in a water vessel in calm sea, wherein the vertical and horizontal directions are to be understood as approximate directions. For an application in such a marine drive, the first clutch output part can be rigidly connected to a first bevel gear and the second clutch output part can be rigidly connected to a second a second bevel gear, wherein the first bevel gear and the second bevel gear are meshing with a crown gear, which is fastened to the output shaft. The output shaft of the corresponding marine hybrid transmission is a vertical shaft, which is connected to the propeller shaft by a lower bevel gear set.
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The word connected in the context of this document means that a driving power in form of torque and rotation can be transmitted via the corresponding connection. A connection can or cannot be permanent. Permanently connected means, that the connection cannot be disconnected during operation. Permanent connections for example can be rigid connections, splined or welded connections, connections via a coupling or connections of two elements which are produced as one integral piece, just to name a few examples. Connection via a set of gears which cannot be disconnected during operation are permanent connections, as well. Non-permanent connections include a clutch which can be engaged for power transmission and disengaged to cut off the power transmission during operation.
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Another embodiment provides a very compact and solid design. The second input shaft can therefore be a hollow shaft. At least a part of the first input shaft can extend into or through the second input shaft, which is a hollow shaft. In one more specific embodiment the first input shaft is supported in the housing of the marine hybrid transmission by a first bearing. An engine connection is arranged at a first end of the first input shaft and a second bearing is arranged at a second end of the first input shaft to support the first input shaft inside the second input shaft. A third bearing is arranged to support the second input shaft in the housing.
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The invention further refers to a marine hybrid drive unit comprising the electric machine and a marine hybrid transmission as described above. According to one embodiment of this marine hybrid drive unit the electric machine comprises a third and a fourth clutch to selectively connect the electric machine either to the first input shaft or to the second input shaft. The third clutch, when engaged, connects the electric machine to the second input shaft for torque transmission. The fourth clutch, when engaged, connects the electric machine to the first input shaft for torque transmission. The third and fourth clutches can be used to operate the marine hybrid drive in a second generating mode, wherein the electric machine is driven by the combustion engine and the propeller is not rotating. For this, the third clutch must be disengaged and the fourth clutch must be engaged.
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The third clutch and the fourth clutch can be enclosed by an intermediate housing, which is mounted between the housing of the marine hybrid transmission and the electric machine, and which is also part of the marine hybrid drive unit. The electric machine can be fastened to the housing of the marine hybrid transmission by means of the intermediate housing, so that the intermediate housing carries the weight of the electric machine. Alternatively the electric machine can be supported by a supporting frame which is mounted to the housing of the marine hybrid transmission or directly to the supporting structure of the hull of the water vessel.
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The third and the fourth clutch can be actuated in a way to engage either the third or the fourth clutch at a time. However, the third and the fourth clutch can be arranged together in one constructional unit.
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In one embodiment the third clutch and the fourth clutch are pressure actuated multi-disc clutches. In view of a compact design of the marine drive unit the third clutch in such an embodiment can be nested, i.e. located, inside the fourth clutch. This means that the third clutch and the fourth clutch are not located one behind the other in axial direction, so that the axial length of the marine drive unit is reduced. Preferably the third clutch in this embodiment does not extend over the axial dimensions of the fourth clutch. Both clutches can be supplied by one pressure supply system including a pump, appropriate pressure valves and connections.
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In another embodiment the third clutch and the fourth clutch are positive locking clutches. The third clutch and the fourth clutch in form of positive locking clutches can be both part of one clutch assembly.
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In one embodiment a clutch assembly of the third and the fourth clutch comprises a sliding bushing which can be moved in at least two different switch positions to engage either the third clutch or the fourth clutch.
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In a first switch position the third clutch is engaged and the electric machine is connected to the second input shaft, while the fourth clutch is disengaged, and the electric machine is not connected to the first input shaft. This first switch position can be applied to operate the marine hybrid drive solely by the electric machine or in the booster mode as described above. The first switch position can also be used to operate the marine hybrid drive in the first generating mode, when the propeller is driven by the water and the propeller drives the electric machine via the second input shaft.
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In a second switch position of the sliding bushing the third clutch is disengaged and the electric machine is not connected to the second input shaft, while the fourth clutch is engaged, and the electric machine is connected to the first input shaft. This second switch position can be used to operate the marine hybrid drive in the second generating mode, wherein the electric machine is driven by the combustion engine. In order to avoid the rotation of the propeller in the second generating mode, the first, second and third clutch can be disengaged.
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Additionally there may be third switch position of the sliding bushing, a so-called neutral position. In the third switch position of the sliding bushing the third clutch and the fourth clutch are disengaged. The third switch position can be applied during operation, when the propeller shall be driven solely by the combustion engine. The disengaged third and fourth clutches allow for a standstill of the motor shaft of the electric machine.
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The invention will be further and more particularly described in the following, by way of example only, and with reference to the accompanying figures.
- Fig. 1
- shows a schematic drawing of a marine hybrid drive unit according to the invention and a combustion engine together in a marine hybrid drive;
- Fig. 2
- shows a sectional view of a marine hybrid transmission according to the invention;
- Fig. 3
- shows a schematic drawing of a further marine hybrid drive unit according to the invention and a combustion engine together in a marine hybrid drive with a third and a fourth clutch in form of multi-disk clutches;
- Fig. 4
- shows a sectional view of a marine hybrid drive unit with positive locking third and fourth clutches in a first switch position; and
- Fig. 5
- shows a sectional view of a marine hybrid drive unit with positive locking third and fourth clutches in a second switch position.
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The marine hybrid drive as shown in Fig. 1 comprises a combustion engine 10, an electric machine 20 and a marine hybrid transmission 1. The marine hybrid drive is mounted in an engine room inside a hull 101 of a water vessel. A marine hybrid drive unit 100 comprises the electric machine 20 and the marine hybrid transmission 1.
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The marine hybrid transmission 1 comprising a first input shaft 11 which is permanently connected to a crank shaft 19 of the combustion engine 10 and a second input shaft 21 which is permanently connected to a motor shaft 20 of the electric machine 20. The motor shaft 22 of the electric machine 20 runs coaxial to the first input shaft 11 and to the second input shaft 21. The electric machine 20 is installed in horizontal position in the back of the marine hybrid drive unit 100, i.e. on the opposite side of the marine hybrid transmission 1 with regard to the combustion engine 10. At a first end of the first input shaft 11 there is an engine connection 18 arranged to connect the first input shaft 11 to the crank shaft 19 of the combustion engine 10. Said engine connection can be a flanged connection, a splined connection, or a coupling.
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The first input shaft 11 is supported in the housing 2 by a first bearing 3. At a second end of the first input shaft 11 there is a second bearing 4 arranged to support the first input shaft 11 inside the second input shaft 21. The second input shaft 21 is a hollow shaft. The second bearing 4 in this embodiment is a roller bearing. It is arranged between the central first input shaft 11 and the hollow second input shaft 21. A third bearing 5 is arranged to support the second input shaft 21 in the housing 2.
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A first clutch 12 and a second clutch 15 are arranged inside the housing 2 for a selective transmission of the driving power from the first input shaft 11 to the output shaft 30 in a forward or reverse direction. The forward direction can be selected by engaging the first clutch 12, while the second clutch 15 is disengaged. The reverse direction can be selected by engaging the second clutch 15, while the first clutch 12 is disengaged. The first clutch 12 comprises a first clutch input part 13 and a first clutch output part 14. The second clutch 15 comprises a second clutch input part 16 and a second clutch output part 17. Both clutches 12 and 15 are multi-disk clutches. The clutch input parts 13 and 16 of both clutches 12, 15 are outer disk carriers. The clutch output parts 14 and 17 are inner disk carriers.
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The first input shaft 11 is permanently connected to the first clutch input part 13 and to the second clutch input part 16, i.e. to both outer disk carriers. The second clutch output part 17 is rigidly connected to the second input shaft 21. In this embodiment, the second input shaft 21 and with it the electric machine 20 are permanently connected to the output shaft 30 via the second clutch output part 17. Said permanent connection between the electric machine 20 and the output shaft 30 allows for forward and reverse maneuvers without any interaction with the first and second clutch 12, 15. The electric machine 20 can be operated in the requested rotational direction to propel the water vessel forward or reverse. With other words, the electric machine 20 can be operated independently from the drive train of the combustion engine 10. The electric machine 20 may be controlled by a separate control system without interaction or interfaces with control systems of the combustion engine 10 or the hybrid marine transmission 1.
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The first and second clutch output parts 14, 17 are permanently connected the output shaft 30 via an upper bevel gear set 34, comprising a first bevel gear 31, a second bevel gear 32 and a crown gear 33. The first clutch output part 13 is rigidly connected to the first bevel gear 31 and the second clutch output part 16 is rigidly connected to the second a second bevel gear 32. The first bevel gear 31 and the second bevel gear 32 are both meshing with crown gear 33, which is fastened to the output shaft 30. The output shaft 30 runs in a vertical direction and transmits the driving power from the upper bevel gear set 34 to the lower bevel gear set 41, which is located inside a POD beneath the hull 101. The propeller 42 can be driven via another bevel gear 43 which is fastened to a propeller shaft 40.
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Fig. 2 shows the marine hybrid transmission 1 of Fig. 1 with the electric machine 20 in a more detailed sectional view. The same components are indicated with the same referals as in Fig. 1.
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The engine connection 18 is done in form of a spline at the first end of the first input shaft 11. The second end of the first input shaft 11 is supported by the second bearing 4, inside the second input shaft 21, which is a hollow shaft. The first bearing 3 and the second bearing 4 are tapered roller bearings, which are arranged in a X-type application to appropriately support the first input shaft 11. The second bearing 4 is located inside the second input shaft 21. The second input shaft 21 is connected to the motor shaft 22 of the electric machine 20 by means of a splined connection. The second input shaft 21 is supported in the housing 2 by means of the third bearing 5, which is a double angular ball bearing. The output shaft 30 with crown gear 33 is supported in the housing 2 by a bearing arrangement 6 comprising two tapered roller bearings in an O-type application.
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Fig. 3 shows a marine hybrid drive comprising a further marine hybrid drive unit 102 together with a combustion engine 10. The further hybrid drive unit 102 includes a marine hybrid transmission 1 as shown in Fig. 1 and Fig. 2 and the electric machine 20. The same components are therefore indicated with the same referals as in Fig. 1 and Fig. 2.
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The differences between the marine hybrid drive unit 102 in Fig. 3 and the marine hybrid drive unit 100 in Fig 1 are a third clutch 23 and a fourth clutch 24 arranged in an intermediate housing 28 between the electric machine 20 and the marine hybrid transmission 1. The third clutch 23 is arranged to connect and disconnect the electric machine 20 and the second input shaft 21. The fourth clutch 24, when engaged, connects the electric machine 20 to the first input shaft 11. The possibility to disconnect the second input shaft 21 from the electric machine 20 by the third clutch 23 and, at the same time, to connect the electric machine 20 to the first input shaft 11 by the fourth clutch 24, provides for a generation mode, wherein the electric machine 20 can be driven by the combustion engine 10 without a rotation of the propeller 42. The electric machine 20 can generate electric energy when the fourth clutch 24 is engaged to connect the motor shaft 22 of the electric machine 20 with the first input shaft 11. When, at the same time, the first clutch 12, the second clutch 15 and the third clutch 23 are disengaged, the propeller does not rotate during this generating mode.
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The third clutch 23 and the fourth clutch 24 are enclosed by the intermediate housing 28, which is mounted between the housing 2 of the marine hybrid transmission 1 and the electric machine 2.
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The third clutch 23 is in radial direction arranged inside the fourth clutch 24. In other words the third clutch 23 is nested inside the fourth clutch 24, what is very beneficial in view of the compact design of the marine hybrid drive unit 102. The third clutch 23 and the fourth clutch 24 are pressure actuated multi-disc clutches.
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Another embodiment of the marine hybrid drive unit 102 with a third clutch 23 and a fourth clutch 24 is shown in Fig. 4 and Fig. 5. The difference of the embodiments in Fig. 3 to Fig. 4 and Fig. 5 is the layout of the third clutch 3 and the fourth clutch 24. While in Fig. 3 these two clutches 23, 24 are multi-disk friction clutches, in Fig. 4 and Fig. 5 the two clutches 23, 24 are form-fitting positive locking clutches. The third clutch 23 and the fourth clutch 24 in this embodiment are both part of a clutch assembly 25.
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The clutch assembly 25 comprising a sliding bushing 26 which is permanently connected to the electric machine 20 to rotate with the motor shaft 22. However, the sliding bushing 26 is movable in axial direction. The axial direction regards to the rotation axis of the motor shaft 22. Therefore the sliding bushing 26 has an inner spline which is engaged with an outer spline on the motor shaft 22. An actuation plate 27 is mounted to the sliding bushing 26 via an actuator bearing 29. The actuation plate 27 can be moved in axial direction by a pressure actuated actuator to push the sliding bushing 26 in a selected switch position.
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The sliding bushing 26 can be moved in a first switch position to engage the third clutch 23 and to disengage the fourth clutch 24. The first switch position is shown in Fig. 4. In the first switch position the third clutch 23 is engaged, and the electric machine 20 is connected to the second input shaft 21, while the fourth clutch 24 is disengaged, and the electric machine 20 is disconnected from the first input shaft 11. The third clutch 23 comprises an outer spline on the outer surface of the sliding bushing 26 which is engaged with an inner spline of the second input shaft 21 in the first switch position. In the second switch position the output shaft 30 can be driven by the electric machine 20 for driving the propeller or vice versa.
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Besides, the sliding bushing 26 can be moved in a second switch position to engage the fourth clutch 24 and to disengage the third clutch 23. The second switch position is shown in Fig. 5. In the second switch position the electric machine 20 is connected to the first input shaft 11 and disconnected from the second input shaft 21. The fourth clutch 24 comprises an inner spline at the inner surface of the sliding bushing 26 which is engaged with an outer spline at the second end of the first input shaft 11 in the second switch position. In the second switch position the combustion engine 10 can drive the electric machine 20 in a second generating mode without driving the propeller at the same time.
Referals
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- 1
- marine hybrid transmission
- 2
- housing
- 3
- first bearing
- 4
- second bearing
- 5
- third bearing
- 10
- combustion engine
- 11
- first input shaft
- 12
- first clutch
- 13
- first clutch input part
- 14
- first clutch output part
- 15
- second clutch
- 16
- second clutch input part
- 17
- second clutch output part
- 18
- engine connection
- 19
- crank shaft
- 20
- electric machine
- 21
- second input shaft
- 22
- motor shaft
- 23
- third clutch
- 24
- fourth clutch
- 25
- clutch assembly
- 26
- sliding bushing
- 27
- actuation plate
- 28
- intermediate housing
- 29
- actuator bearing
- 30
- output shaft
- 31
- first bevel gear
- 32
- second bevel gear
- 33
- crown gear
- 34
- upper bevel gear set
- 40
- propeller shaft
- 41
- lower bevel gear set
- 42
- propeller
- 43
- bevel gear
- 100
- marine hybrid drive unit
- 101
- hull
- 102
- marine hybrid drive unit