MARINE HYBRID DRIVE UNIT AND METHOD TO DRIVE SUCH A MARINE HYBRID DRIVE UNIT

Abstract

A marine hybrid drive unit (100) has an electric motor (2) and a transmission (3). The transmission (3) has an input shaft (4), an output shaft (5), and a pressure actuated transmission clutch (6) configured to selectively connect the input shaft (4) to the output shaft (5). The input shaft (4) can selectively be driven solely by a combustion engine (1), solely by the electric motor (2), or by both the combustion engine (1) and the electric motor (2) simultaneously. The transmission (3) further includes a main oil pump (7), driven by the input shaft (4) to provide oil pressure for actuating the pressure actuated transmission clutch (6). An auxiliary oil pump (8) provides oil pressure to the pressure actuated transmission clutch (6) during operation in a low-speed range. Also disclosed is a method for driving such a marine hybrid drive unit.

Claims

1. A marine hybrid drive unit (100), comprising: an electric motor (2); a transmission (3), comprising an input shaft (4), an output shaft (5), and a pressure actuated transmission clutch (6) configured to selectively connect the input shaft (4) to the output shaft (5), wherein the input shaft (4) is configured to selectively be driven solely by a combustion engine (1), solely by the electric motor (2), or by the combustion engine (1) and the electric motor (2) simultaneously; a main oil pump (7) driven by the input shaft (4) and configured to provide oil pressure for actuating the pressure actuated transmission clutch (6); and an auxiliary oil pump (8) configured for providing oil pressure to the pressure actuated transmission clutch (6) during operation in a low-speed range.

2. The marine hybrid drive unit (100) according to claim 1, comprising a control unit (101) configured to actuate the auxiliary oil pump (8) when a speed control signal is below 5 knots.

3. The marine hybrid drive unit (100) according to claim 1, comprising a control unit (101) configured to actuate the auxiliary oil pump (8) when a rotation speed of the input shaft (4) is below a preset threshold in a range between 500 and 700 rpm.

4. The marine hybrid drive unit (100) according to claim 3, wherein control unit (101) is configured to actuate the auxiliary oil pump (8) when the input shaft (4) is driven solely by the electric motor (2).

5. The marine hybrid drive unit (100) according to claim 1, comprising: a pressure actuated input clutch (15) configured to connect and disconnect the combustion engine (1) to the input shaft (4), wherein the main oil pump (7) and the auxiliary oil pump (8) are arranged to provide oil for the actuation of the pressure actuated input clutch (15).

6. The marine hybrid drive unit (100) according to claim 1, comprising an oil lubrication system, wherein the main oil pump (7) and the auxiliary oil pump (8) are connected to the oil lubrication system to supply oil to the oil lubrication system.

7. The marine hybrid drive unit (100) according to claim 1, wherein the auxiliary oil pump (8) is positioned outside of a transmission housing (9) of the transmission (3).

8. A method for driving the marine hybrid drive unit (100) according to claim 1, comprising: driving the input shaft (4) in a low-speed range solely by the electric motor (2) while providing the pressure for the pressure actuated transmission clutch (6) by an auxiliary oil pump (8).

9. The method according to claim 8, wherein the low-speed range is defined to boat speeds between 0 and 5 knots.

10. The method according to claim 8, wherein the low-speed range is defined to rotation speeds of the input shaft (4) below a preset threshold in a range between 500 and 700 rpm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention will be further and more particularly described in the following, by way of example only, and with reference to the sole accompanying FIGURE.

[0019] FIG. 1 shows a marine hybrid drive unit according to the invention in a schematic drawing.

DETAILED DESCRIPTION

[0020] The marine hybrid drive unit 100 as shown in FIG. 1 can be mounted inside the hull of a boat. The marine hybrid drive unit 100 comprises a combustion engine 1 and an electric motor 2 for propelling the boat in different operation modes.

[0021] The marine hybrid drive unit 100 further comprises a transmission 3 with an input shaft 4 and an output shaft 5. The input shaft 4 can selectively be driven solely by the combustion engine 1, solely by the electric motor 2 or by the combustion engine 1 and the electric motor 2 simultaneously. The output shaft 5 in this embodiment being arranged with a downward angle with regard to the input shaft 4. The output shaft 5 being connected to a propeller shaft of the boat either directly or via further transmitting elements.

[0022] The combustion engine 1 includes a crankshaft 20 which is connected to a drive shaft 14 of a hybrid module 10. The connection between the crankshaft 20 and the drive shaft 14 may comprise a flywheel and/or a torsional damper which are not shown in the scheme of FIG. 1.

[0023] In this embodiment the drive shaft 14 can be connected and disconnected to an input shaft 4 by means of a pressure actuated input clutch 15. The crankshaft 20 and the input shaft 4 are arranged coaxial to each other. The crankshaft 20 is fastened to an input element 12 of the input clutch 15 whereas the input shaft 4 is fastened to an output element 13 of the input clutch 15. The input clutch 15 in this embodiment is a multi-disk-friction-clutch with inner and outer friction disks. The input element 12 being designed as an inner disk-carrier, whereas the output element 13 is designed as an outer disk-carrier. The inner and outer friction disks are pressed against each other to provide for the required transmission of torque.

[0024] The input clutch 15 and the electric motor 2 are part of the hybrid module 10 which is mounted in between the combustion engine 1 and the transmission 3. The electric motor 2 is mounted to a module housing 11 of the hybrid module 10 such, that a motor shaft 21 of the electric motor 2 is arranged in parallel to the input shaft 4. The electric motor 2 is permanently connected to the input shaft 4 and to the output element 13 of the input clutch 15. The input shaft 4 is permanently connected to the electric motor 2 via gear steps 16, wherein a gear ratio of the gear steps 16 is set to drive the input shaft 4 with the main oil pump 7. The gear ratio of the gear steps 16 is in a range between 2 and 3 which allows for efficient operation when the electric motor 2 is driving the input shaft 4 and when the electric motor 2 is driven as a generator to recharge an electric battery 22 which is connected to the electric motor 2. The gear steps 16 are part of the hybrid module 10 and arranged inside the module housing 11. The gear steps 16 comprise a first spur gear 17 which is fastened to the motor shaft 21. The first spur gear 17 meshes with a second spur gear 18 which is supported in the module housing 11. The second spur gear 18 further meshes with a toothing 19 which is an integral part of the output element 13 of the input clutch 15. The pressure actuated input clutch 15 is also a part of the hybrid module 10.

[0025] The transmission 3 further includes a pressure actuated transmission clutch 6 to selectively connect the input shaft 4 to the output shaft 5. The pressure actuated transmission clutch 6 is arranged inside a transmission housing 9. The pressure actuated transmission clutch 6 is a hydraulically actuated multi-disk clutch. The input shaft 4 is fastened to an outer disk carrier of the transmission clutch 6, whereas an inner disk carrier of the transmission clutch 6 is rigidly fastened to a pinion 23. Pinion 23 is permanently meshing with an output gear 24 which is fastened to the output shaft 5.

[0026] The pressure actuated transmission clutch 6 can be fully engaged, fully disengaged or it can be operated in slipping operation. The slipping operation of the transmission clutch 6 can be used to adjust the speed of the output shaft 5 continuously in a range between 100% and 25% with regard to the speed of the input shaft 4. However, the present invention provides an arrangement and a method to avoid the energy consuming slipping operation of the transmission clutch 6 in the low-speed range, by using only the electric motor 2 for generating the required drive torque and speed, while the transmission clutch 6 is fully engaged.

[0027] The transmission 3 comprises a main oil pump 7 and an auxiliary oil pump 8. The main oil pump 8 is driven by the input shaft 4 to provide oil to the oil lubrication system, for actuating the pressure actuated input clutch 15 and for actuating the pressure actuated transmission clutch 6. An auxiliary oil pump 8 is positioned outside of the transmission housing 9 and shall be actuated during operation in the low-speed range. The auxiliary oil pump 8 is an electric pump and comprises an electric pump motor.

[0028] A control unit 101 of the marine hybrid drive unit 100 is arranged to control the propulsion in different operating modes. Especially for operations in the low-speed range, the control unit 101 is configured to actuate the auxiliary oil pump 8 and to generate signals for driving the input shaft 4 solely by the electric motor 2. The control unit 101 contains electronic components and hydraulic components like valves for the control of oil flow and oil pressure in the oil supply system. The control unit 101 further includes interfaces to be connected to a control unit of the combustion engine 1 and/or to other control units of the boat. In other embodiments the control unit 101 may be located at another position in the boat and the control unit 101 may comprise several separate control boxes or devices.

[0029] The auxiliary oil pump 8 can be actuated by a control unit 101, which is configured to actuate the auxiliary oil pump 8 when a speed control signal is below 5 knots. The speed control signal can be generated by a human machine interface like a control or command lever at the helmstand of the boat. The control unit 101 will receive the speed control signal and generate corresponding command signals to the combustion engine 1, the electric motor 2 and to the auxiliary oil pump 8, depending on the position of the control or command lever. In alternative embodiments the low-speed range can be defined to rotation speeds below a preset threshold in a range between 500 and 700 rpm at the input shaft 4, so that the control unit 101 can actuate the auxiliary oil pump 8 when a sensor signal from an input shaft speed sensor signals a speed of the input shaft 4 below 700 rpm.

[0030] The oil supply system includes the main oil pump 7, the auxiliary oil pump 8, as well as all required connecting ducts and/or pipes, valves and further hydraulic components to provide and to control an appropriate oil pressure for the actuation of the transmission and the input clutches 6, 15 and for the oil lubrication system.

REFERENCES

[0031] 1 combustion engine [0032] 2 electric motor [0033] 3 transmission [0034] 4 input shaft [0035] 5 output shaft [0036] 6 transmission clutch [0037] 7 main oil pump [0038] 8 auxiliary oil pump [0039] 9 transmission housing [0040] 10 hybrid module [0041] 11 module housing [0042] 12 input element [0043] 13 output element [0044] 14 drive shaft [0045] 15 input clutch [0046] 16 gear steps [0047] 17 first spur gear [0048] 18 second spurgear [0049] 19 toothing [0050] 20 crankshaft [0051] 21 motor shaft [0052] 22 electric battery [0053] 23 pinion [0054] 24 output gear [0055] 100 marine hybrid drive unit [0056] 101 control unit