-
The present invention relates to a marine hybrid drive assembly and to a marine hybrid drive comprising a combustion engine and two electric machines.
-
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.
-
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 marine vessel.
-
In the
EP 1 426 287 A1 a power generating and propelling system of a vessel has been disclosed with a combustion engine, an electric motor and a generator. Said components being connected to a propeller shaft via a power transmission device. The generator is provided between the combustion engine and the power transmission device. An output shaft of the electric motor can be coaxially to any of the rotary shafts of the power transmission device.
-
The purpose of the present invention is to provide an improved marine hybrid drive assembly with a high level of reliability and a broad range of applicability.
-
This purpose is achieved by a marine hybrid drive assembly according to claim 1 and by a marine hybrid drive according to claim 8. Further embodiments are claimed in dependent claims.
-
The present invention provides a marine hybrid drive assembly comprising a first electric machine, a second electric machine, a first input shaft, a second input shaft and an output shaft. The first input shaft is to be connected to a combustion engine. The second input shaft is connected to the first electric machine. The first electric machine is preferably used as a driving machine for driving the output shaft. The output shaft is to be connected to a propeller shaft. The second electric machine is permanently connected to the first input shaft. The second electric machine can preferably be used as an electric generator.
-
The first input shaft is arranged coaxially to the second input shaft. Such a coaxial arrangement of the first and second input shaft is beneficial to a compact outline of the marine hybrid drive assembly what makes it applicable for a wide range of different layouts of boats.
-
The marine hybrid drive assembly further comprising a first clutch and a second clutch to transmit driving power from the first input shaft to the output shaft selectively in a forward or reverse direction by engaging the first clutch or the second clutch. So the combustion engine can be used to propel the water vessel in a forward or in a reverse direction, depending on the corresponding clutch engagement. Clutches in marine transmissions are typically pressure operated clutches. In case of a failure in the pressure supply to one of said clutches, the power from the combustion engine cannot be transmitted to the output shaft via the first input shaft. The present invention enables to drive the output shaft in such a situation by the first electric machine via the second input shaft. This way, the first 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 drive assembly and the corresponding marine hybrid drive is increased.
-
A disengagement of both clutches further allows for a complete disconnection between the first input shaft and the output shaft, this means a disconnection between the combustion engine and the propeller. The permanent connection of the first input shaft with the second electric machine enables the recharging of batteries by operating the combustion engine to drive the second electric machine in a generator mode, while the propeller is not rotating, when the first clutch and the second clutch are both disengaged. This way the assembly can work like a so-called Genset recharging a battery from the combustion engine power without the propeller rotation. Beside, the power of the combustion engine can also be used to generate electric energy with the second electric machine, when one of the clutches is engaged and the propeller shaft is driven by the combustion engine at the same time.
-
Another possible operation mode is a generating mode during sailing. Therefore the first 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 drive assembly is installed on a sailboat, the output shaft can rotate driven by the propeller shaft for the effect of the propeller and effect a so-called hydrogeneration during sailing. Such a 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.
-
The second input shaft is permanently connected to the output shaft. The effect of the permanent connection between the second input shaft and the output shaft is, that the output shaft and a propeller connected to the propeller shaft can be controlled and driven by the electric machine, independent of a status of the combustion engine or components of the marine hybrid drive assembly, especially independent of the status of the first and second clutch. Therefore it is possible to establish independent control systems for the electric machines and the marine hybrid drive assembly.
-
In an electric operating mode the first 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.
-
Another operating mode is a booster-mode, which adds the output power of the first electric machine to the combustion engine power output. The power of the first electric machine can be used additionally to the power of the combustion engine during full power operation and in intermediate power operation where it is possible to get the best efficiency and fuel saving of the combustion engine by using the first electric machine for small accelerations or changes in speed.
-
The present invention provides a marine hybrid drive assembly with an optimal integration between the combustion engine and the two electric machines. The described design of different proposed embodiments provide that the electric machines are installed in the limited space of an engine room.
-
To further reduce the required space of the marine hybrid drive assembly, the second input shaft can be a hollow shaft and the first input shaft can be arranged to, at least partially, extend through the second input shaft. With other words the first input shaft runs through the inner space of the second input shaft in form of the hollow shaft.
-
The marine hybrid drive assembly may further comprise a first gear to transmit driving power to the output shaft in a first direction of rotation and a second gear to transmit driving power in an opposing second direction of rotation. First and second directions of rotations may be a forward and a reverse direction. The second input shaft can be permanently connected to the output shaft via the first gear or via the second gear. Said first and second gears can be spur gears, to connect the input shaft with an output shaft which is at least nearly parallel to the input shaft. For the implementation of the reverse direction an additional reversing gear can be installed to mesh with the corresponding first or second gear.
-
In one embodiment the first input shaft and the second input shaft both arranged on an input side of a housing. The output shaft is horizontally oriented, as well. The output shaft can be arranged on an output side opposed to the input side. The input side may be the side where the combustion engine is positioned.
-
Said first and second gears can also be bevel gears, to connect a horizontal first input shaft to a vertical output shaft. Hence, in such an embodiment the output shaft is a vertical shaft, which is connected to the first input shaft via an upper bevel gear unit. The first and the second input shafts may be arranged on opposite sides of a housing of the upper bevel gear unit. The upper bevel gear unit operatively connects the first input shaft to the output shaft, when the first or the second clutch is engaged. The vertical output shaft can be connected to the horizontal propeller shaft by a lower bevel gear unit. The latter may be arranged in a pod underneath the hull of the water vessel. The terms horizontal and vertical refer to a marine hybrid drive assembly mounted in an operating position on a water vessel in calm water, with the water surface being a horizontal plane. However, the terms horizontal and vertical do not limit the corresponding direction to an exact direction but include deviations from an exact horizontal or vertical direction up to an angle of 15 degrees.
-
The permanent connection between the second input shaft and the output shaft can also be realized via said upper bevel gear unit. For this embodiment, the second input shaft can be fixed to the first or to the second gear in form of bevel gears of the upper bevel gear unit. A crown gear which is fastened to the vertical output shaft permanently meshes with the first gear and the second gear, wherein the first gear is rigidly connected to the output part of the first clutch, and wherein the second gear is rigidly connected to the output part of the second clutch. Such an assembly is typically used for so-called Z-drives, for example in thrusters or pod-drives. The second input shaft can be directly connected to the first gear, i.e. without any other element between them.
-
A further aspect of the invention are preferred assembly positions of the electric machines to enable beneficial implementation of the marine hybrid drive assembly into a limited space of an engine room in the hull of a boat or ship. In one embodiment the first electric machine comprises a drive shaft which is arranged parallel to the first input shaft and to the second input shaft. For clarity, the word parallel means not coaxial. Such a parallel position of the first electric machine enables different layouts of the marine hybrid drive assembly to fit it inside an engine room. The drive shaft of the first electric machine can be connected to the parallel second input shaft by means of a belt drive with a pulley on each shaft or by a set of gears, especially spur gears.
-
In one embodiment the marine hybrid drive assembly comprises a housing to enclose the first clutch and the second clutch and to support the first input shaft, the second input shaft and the output shaft. Hence, the first input shaft, the second input shaft and the output shaft are at least partially enclosed by the housing, as well. The first gear and second gear are also arranged inside the housing. This way the marine hybrid drive assembly forms a compact and robust structural unit. Besides, the housing protects the components inside from harmful influence of the surrounding, like humidity, water or dust and keeps lubrication fluid inside the housing. The first and/or the second electric machine can be attached to the housing and might be supported by the housing.
-
The invention further comprises a marine hybrid drive with a combustion engine and with a marine hybrid drive assembly as described above. Depending on the requirements of the specific application, the electric machines can be a low voltage machine to be operated for example on 48 Volt or it can be a high voltage machine to be operated in a range between 360 and 400 Volt. The proposed marine hybrid drive can be used for thrusters, pod drives, saildrives or marine shaft devices, just to name a few exemplary applications.
-
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 marine hybrid drive with a combustion engine and with a marine hybrid drive assembly according to a first embodiment of the invention;
- Fig. 2
- shows a sectional view of the marine hybrid drive assembly in Fig. 1;
- Fig. 3
- shows a sectional view of a second embodiment of the invention and
- Fig. 4
- shows a third embodiment of the invention.
-
The marine hybrid drive 100 as shown in Fig. 1 comprises a combustion engine 7 and a marine hybrid drive assembly 1 with a first electric machine 2 and a second electric machine 3. The marine hybrid drive 100 is mounted inside the hull 101 of a water vessel. Fig. 2 shows, with some more details, only the components of the marine hybrid drive 100 from Fig. 1 which are located inside the hull 101. The first electric machine 2 is preferably operated as an electric driving machine to drive a propeller shaft 18 via an output shaft 6. A propeller 19 is fastened to one end of the propeller shaft 18. The second electric machine 3 is preferably operated as a generator to recharge a battery of the corresponding water vessel.
-
Further components of the marine hybrid drive assembly 1 are a first input shaft 4, a second input shaft 5 and an output shaft 6 which are all supported in a housing 22. The housing 22 encloses the components of an upper bevel gear unit 16 which enable the desired power distribution between the horizontal first input shaft 4, the horizontal second input shaft 5 and the vertical output shaft 6. The first input shaft 4 is connected to a crank shaft 24 of the combustion engine 7 by means of an engine coupling 20. The engine coupling 20 may include elastic elements to compensate for radial, axial or angular offset and effect damping.
-
The second input shaft 5 is connected to the first electric machine 2. The second input shaft 5 is arranged coaxially to the first input shaft 4. The second input shaft 5 is a hollow shaft. One end of the first input shaft 4 centrally extends through the second input shaft 5. Hence, the first input shaft 4 is partially arranged inside the second input shaft 5. Such a coaxial arrangement of the first input shaft 4 and the second input shaft 5 allows for a particularly compact layout of the marine hybrid drive assembly 1. The first input shaft 4 and the second input shaft 5 protrude from the housing 22 on opposite sides of the housing 22.
-
In this embodiment the first electric machine 2 is positioned parallel to the first and second input shafts 4 and 5. The second electric machine 3 is coaxially positioned with regard to the first input shaft 4. This means that the first and second electric machines 2 and 3 can be positioned side by side. In other words the rotation axis of a drive shaft 12 of the first electric machine 2 is not arranged coaxially to the first and second input shaft 4 and 5, but with such an offset in radial direction that the first electric machine 2 can be positioned at least partially in the same axial space as the second electric machine 3. This is a beneficial layout for applications, where the available space in axial direction is limited. The terms axial and radial are used with regard to the rotation axis of the first input shaft 4, if not explicitly defined different.
-
The drive shafts 12, 13 of both electric machines 2 and 3 are both oriented in a horizontal direction. The drive shaft 12 of the first electric machine 2 is connected to the second input shaft 5 by means of a belt drive 21. The drive shaft 13 of the second electric machine 3 is permanently connected to the first input shaft 4 by means of a splined connection.
-
The marine hybrid drive assembly 1 further comprising a first clutch 8 and a second clutch 9 to transmit driving power from the first input shaft 4 to the output shaft 6. The driving power from the combustion engine 7 can thus be selectively transmitted in a forward or reverse direction to the output shaft 6 by engaging the first clutch 8 or the second clutch 9. The first clutch 8 and a second clutch 9 are both arranged inside the housing 22.
-
The second input shaft 5 is permanently connected to the output shaft 6. The effect of the permanent connection between the second input shaft 5 and the output shaft 6 is, that the output shaft 6 together with the propeller shaft 18 can be controlled and driven by the electric machine, independent of a status of the combustion engine 7 and independent of the status of the first and second clutch 8 and 9. Therefore it is possible to establish independent control systems for the first electric machine 2 and for combustion engine 7.
-
The marine hybrid drive assembly 1 further comprises a first gear 10 to transmit driving power to the output shaft 6 in a first direction of rotation and a second gear 16 to transmit driving power in an opposing second direction of rotation. First and second directions of rotations are a forward and a reverse direction. The second input shaft 5 is permanently connected to the output shaft 6 via the second gear 11.
-
Said first and second gears 10 and 11 are bevel gears which connect the horizontal first input shaft 4 to the vertical output shaft 6. The first and second gears 10 and 11 are components of an upper bevel gear unit 16 and mesh permanently with a crown gear 17 which is fastened to the vertical output shaft 6. The upper bevel gear unit 16 is enclosed by the housing 22. The upper bevel gear unit 16 operatively connects the first input shaft 4 to the output shaft 6, when the first clutch 8 or the second clutch 9 is engaged. For this, an output part of the first clutch 8 is rigidly connected to the first gear 10 and an output part of the second clutch 9 is rigidly connected to the second gear 11. The vertical output shaft 6 is connected to the horizontal propeller shaft 18 by a lower bevel gear unit 23 which is arranged in the lower part of the marine hybrid drive assembly 1 beneath the hull 101.
-
The marine hybrid drives 300 and 400 as shown in Fig. 3 and Fig. 4 comprise several of the same components as the marine hybrid drive 100 in Fig. 1 and Fig. 2, however in a different arrangement. The same components have the same referals in Fig. 1, Fig. 2, Fig. 3 and Fig. 4.
-
The marine hybrid drive 300 comprises a combustion engine 7 and a marine hybrid drive assembly 30 with a first electric machine 2 and a second electric machine 3. Further components of the marine hybrid drive assembly 30 are a first input shaft 4, a second input shaft 5 and an output shaft 6 which are all supported in a housing 22. The housing 22 encloses the components of a spur gear transmission 37 which enables the desired power distribution between the first input shaft 4, the second input shaft 5 and the output shaft 6. The first input shaft 4 is connected to a crank shaft 24 of the combustion engine 7 by means of an engine coupling 20. The engine coupling 20 may include elastic elements to compensate for radial, axial or angular offset and effect damping.
-
The second input shaft 5 is connected to the first electric machine 2. The second input shaft 5 is arranged coaxially to the first input shaft 4. The second input shaft 5 is a hollow shaft. The first input shaft 4 centrally extends through the second input shaft 5. Such a coaxial arrangement of the first input shaft 4 and the second input shaft 5 allows for a particularly compact layout of the marine hybrid drive assembly 30. The first input shaft 4 and the second input shaft 5 protrude from the housing 22 on an input side 14 of the housing 22. The combustion engine 7 is also positioned on the input side 14 of the transmission 22. In other words the first input shaft 4 and the second input shaft 5 are arranged on the input side 14 of the housing 22 and the output shaft 6 is arranged on the output side 15 which is opposed to the input side 14.
-
In this embodiment the first electric machine 2 is positioned parallel to the first and second input shafts 4 and 5. The first electric machine 2 is positioned on top of a housing 22. The second electric machine 3 is positioned coaxially to the first input shaft 4 at the output side 15 of the housing 22. The first electric machine 2 is preferably operated as an electric driving machine to drive a propeller shaft via an output shaft 6. The second electric machine 3 is preferably operated as a generator to recharge a battery of the corresponding water vessel. The drive shafts 12, 13 of both electric machines 2 and 3 are both oriented in a horizontal direction. The drive shaft 12 of the first electric machine 2 is connected to the second input shaft 5 by means of gear step comprising a first spur gear 31 and a second spur gear 32. The drive shaft 13 of the second electric machine 3 is permanently connected to the first input shaft 4.
-
The spur gear transmission 33 comprises a first gear 10 to transmit driving power from the first input shaft 4 to the output shaft 6 in a forward direction of rotation and a second gear 11 to transmit driving power from the first input shaft 4 to the output shaft 6 in a reverse direction of rotation. For this the first gear 10 is meshing with a first output gear 34 which is fastened to output shaft 6 and the second gear 11 is meshing with a reversing gear 36. Reversing gear 36 is further meshing with a second output gear 35 which is fastened to output shaft 6.
-
The marine hybrid drive assembly 30 further comprising a first clutch 8 and a second clutch 9 to transmit driving power from the first input shaft 4 to the output shaft 6 selectively in a forward or reverse direction by engaging one of the two clutches 8, 9. The driving power from the combustion engine 7 can thus be selectively transmitted to the output shaft 6 in a forward direction by engaging the first clutch 8 and in a reverse direction by engaging the second clutch 9. The first clutch 8 and a second clutch 9 are both arranged inside the housing 22. The input parts of the first clutch 8 and the second clutch 9 are rigidly fixed to the first input shaft 4. The output part of the first clutch 9 is rigidly connected to the first gear 10 and to the second input shaft 5. The output part of the second clutch 9 is rigidly connected to the second gear 11.
-
An output flange 37 is fastened at an end of the output shaft 6. The output flange 37 can be connected to a propeller shaft of the corresponding water vessel. The marine hybrid drive 300 enables the same functions and operating modes as the marine hybrid drive 100 and as described above.
-
The marine hybrid drive 400 as shown in Fig. 4 comprises a combustion engine 7 and a marine hybrid drive assembly 40 with a first electric machine 2 and a second electric machine 3. Further components of the marine hybrid drive assembly 30 are a first input shaft 4, a second input shaft 5 and an output shaft 6 which are all supported in the housing 22. The housing 22 encloses the components of an upper bevel gear unit 16 which enables the desired power distribution between the first input shaft 4, the second input shaft 5 and the output shaft 6. The first input shaft 4 is connected to a crank shaft 24 of the combustion engine 7 by means of an engine coupling 20. The engine coupling 20 may include elastic elements to compensate for radial, axial or angular offset and effect damping.
-
The first electric machine 2 is preferably operated as an electric driving machine to drive a propeller shaft 18 via an output shaft 6. A propeller 19 is fastened to one end of the propeller shaft 18. The second electric machine 3 is preferably operated as a generator to recharge a battery of the corresponding water vessel.
-
Further components of the marine hybrid drive assembly 40 are a first input shaft 4, a second input shaft 5 and an output shaft 6 which are all supported in a housing 22. The housing 22 encloses the components of an upper bevel gear unit 16 which enable the desired power distribution between the horizontal first input shaft 4, the horizontal second input shaft 5 and the vertical output shaft 6. The first input shaft 4 is connected to a crank shaft 24 of the combustion engine 7 by means of an engine coupling 20. The engine coupling 20 may include elastic elements to compensate for radial, axial or angular offset and effect damping.
-
The second input shaft 5 is connected to the first electric machine 2. The second input shaft 5 is arranged coaxially to the first input shaft 4. The second input shaft 5 is a hollow shaft. One end of the first input shaft 4 centrally extends through the second input shaft 5. Hence, the first input shaft 4 is partially arranged inside the second input shaft 5. Such a coaxial arrangement of the first input shaft 4 and the second input shaft 5 allows for a particularly compact layout of the marine hybrid drive assembly 40. The first input shaft 4 and the second input shaft 5 protrude from the housing 22 on opposite sides of the housing 22.
-
Insofar, the marine hybrid drive 400 enables the same functions and operating modes described above with regard to the marine hybrid drive 100. The main difference is the positions of the first and second electric machines 2 and 3. In the embodiment shown in Fig. 4 the first electric machine 2 is positioned coaxial to the first and second input shafts 4 and 5. Hence, the first electric machine 2 is positioned also coaxial to the second electric machine 3. This means that the first and second electric machines 2 and 3 can be positioned in a row in axial direction. In other words the rotation axis of a drive shaft 12 of the first electric machine 2 is coaxially to the rotation axis of the drive shaft 13 of the second electric machine 3, wherein the drive shaft 12 is a hollow shaft and the drive shaft 13 extends through the drive shaft 12. The second electric machine 3 is installed in the back of the first electric machine 2. Such a configuration can be used for applications, where the available space in axial direction is less limited with regard to the available space in vertical or radial direction.
Referals
-
- 1
- marine hybrid drive assembly
- 2
- first electric machine
- 3
- second electric machine
- 4
- first input shaft
- 5
- second input shaft
- 6
- output shaft
- 7
- combustion engine
- 8
- first clutch
- 9
- second clutch
- 10
- first gear
- 11
- second gear
- 12
- drive shaft
- 13
- drive shaft
- 14
- input side
- 15
- output side
- 16
- upper bevel gear unit
- 17
- crown gear
- 18
- propeller shaft
- 19
- propeller
- 20
- engine coupling
- 21
- belt drive
- 22
- housing
- 23
- lower bevel gear unit
- 24
- crank shaft
- 30
- marine hybrid drive assembly
- 31
- first spur gear
- 32
- second spur gear
- 33
- spur gear transmission
- 34
- first output gear
- 35
- second output gear
- 36
- reversing gear
- 37
- output flange
- 40
- marine hybrid drive assembly
- 100
- marine hybrid drive
- 101
- hull
- 300
- marine hybrid drive
- 400
- marine hybrid drive