Hybrid drive system for an at least partially electrically driven motor vehicle

Abstract

A hybrid drive system (1) for an at least partially electrically driven motor vehicle, comprising an electric drive motor (10) and an output device (31) for transmitting a torque provided by the electric drive motor (10) to driven vehicle wheels (34) of a motor vehicle, and comprising a torque converter (20) arranged in the torque transmission path between a rotor (11) of the electric drive motor (10) and the output device (31) for adapting the torque provided by the electric drive motor (10) to a respective torque requirement, wherein the hybrid drive system (1) further comprises an internal combustion engine (40) for converting chemical energy into kinetic energy for at least indirectly utilizing the kinetic energy to apply a torque to the output device (31),wherein the internal combustion engine (40) is coupled to the output device (31) in the torque transmission path between the torque converter (20) and the output device (31), characterized in that the internal combustion engine (40) is coupled to the output device (31) in the torque transmission path between the torque converter (20) and the output device (31) to a transmission gear (30) for transmitting the torque provided by the torque converter (20), wherein the transmission gear (30) combines continuously or stepwise shiftable transmission ratios with fixed transmission ratios.

Description

[0001] The invention relates to a hybrid drive system for a motor vehicle that can be driven at least partially electrically.

[0002] From DE 11 2015 006 681 T5 a hybrid drive system is known which can be read from the preamble of claim 1.

[0003] Electric drive units are also known from the prior art, which can be integrated into hybrid drive systems and comprise electric drive motors. However, these electric drive motors usually have a relatively small spread.

[0004] Various approaches are known to solve this problem. For example, it is known to design the electric drive motor very large, thereby expanding the torque range that can be achieved by the electric drive motor. However, this results in correspondingly increased installation space requirements, higher weight, and increased investment, including in terms of power electronics.

[0005] Furthermore, it is known to connect a transmission unit to the electric drive motor, wherein the transmission unit implements multiple gear ratios so that an output torque can be achieved according to the required torque requirements. However, due to the necessary separation of the torque transmission path during gear shifting, such transmission units usually involve a loss of comfort for a driver of a motor vehicle equipped with the known electric drive unit or involve a relatively complex design.

[0006] Continuously variable transmission units are also relatively complex in their design and require a lot of space.

[0007] When using a hybrid drive unit according to the state of the art, it is also known to decouple the electric drive motor if its speed range no longer meets the speed requirements, and to have an internal combustion engine provide the required speed. However, this consequently leads to a restriction in the use of the torque provided by the electric motor.

[0008] Based on this, the present invention is based on the object of providing a hybrid drive system which makes it possible to combine a wide range of applications of the electric drive unit with optimal driving operation of a motor vehicle equipped therewith with low investment requirements.

[0009] The object is achieved by the hybrid drive system according to the invention as defined in claim 1. Advantageous embodiments of the hybrid drive system are specified in subclaims 2 to 4.

[0010] The features of the claims can be combined in any technically reasonable manner, whereby the explanations from the following description as well as features from the figures can also be used to comprise additional embodiments of the invention.

[0011] The invention relates to a hybrid drive system for an at least partially electrically driven motor vehicle, comprising an electric drive motor and an output device for transmitting a torque provided by the electric drive motor to driven vehicle wheels of a motor vehicle. Furthermore, the electric drive unit comprises a torque converter arranged in the torque transmission path between a rotor of the electric drive motor and the output device for the purpose of adapting the torque provided by the electric drive motor to a respective torque requirement. The hybrid drive system further comprises an internal combustion engine for converting chemical energy into kinetic energy for the purpose of at least indirectly utilizing the kinetic energy to apply a torque to the output device.

[0012] Due to the arrangement of the torque converter, it is possible to operate it in what is known as slip mode, whereby the speed on the pump side is higher than the speed on the turbine side. This makes it relatively easy to increase the speed on the pump side and to provide a correspondingly increased torque on the turbine side. In this way, an increased torque requirement can be responded to easily by adjusting the torque converter, or an increased torque can be guaranteed even at higher speeds of the electric drive motor. Likewise, sufficient torque can be achieved even at very low speeds of the electric drive motor, for example when starting off. Accordingly, the hybrid drive system according to the invention can cover a wider torque range than that provided by the electric drive motor alone.

[0013] According to a further aspect of the invention, a clutch for disconnecting and opening the torque transmission path between the electric drive motor and the output device is arranged parallel to the torque converter. In particular, this clutch is designed as a frictionally engaged clutch, a so-called lock-up clutch, with which, when closed, a rotationally fixed connection between both clutch sides and, consequently, both sides of the torque transmission path to be connected to one another can be realized. This clutch is advantageously designed as a normally closed clutch, since, in particular, it can be provided that the clutch should be predominantly closed during operation of the electric drive unit.Depending on the application, however, the use of a normally open clutch, or even a clutch that remains in its respective clutch position when not actuated, i.e. a so-called normally-stay clutch, should not be excluded.

[0014] In an advantageous embodiment of the invention, a transmission gear for transmitting the torque provided by the torque converter is arranged in the torque transmission path between the torque converter and the output device.

[0015] In particular, it is provided that this transmission realizes a fixed gear ratio, i.e. is not designed as a manual transmission, although this embodiment should not be excluded from the realization of the invention.

[0016] In one embodiment of the invention, the torque converter is a Trilock converter.

[0017] In such a converter, the stator is mounted on a freewheel, allowing the converter to automatically switch to a purely hydrodynamic clutch. It is designed so that the stator rotates freely after switching, so that no more torque can be supported and the input and output torques are equal.

[0018] This design of the torque converter has the additional advantage that only a small installation space is required for the torque converter, especially if a torsional vibration damper is not used.

[0019] In an alternative embodiment, instead of a Trilock converter, a so-called Föttinger converter in the Lysholm design with a turbine flowing from the inside to the outside, or a counter-rotating converter, also known as a DIWA converter, can be used.

[0020] Furthermore, the hybrid drive system according to the invention can comprise an electrically driven pump that is fluidly connected to the flow chamber of the torque converter for the purpose of ensuring a minimum fluid pressure in the flow chamber of the torque converter or for supporting the realization of a minimum fluid pressure in the flow chamber of the torque converter. In this embodiment, the pump is accordingly driven by a specially provided electric pump motor.

[0021] Additionally or alternatively, it is provided that the hybrid drive system further comprises a mechanically drivable pump which is mechanically coupled to the impeller or the turbine wheel of the torque converter and is fluidly connected to the flow chamber of the torque converter in order to ensure a minimum pressure of a fluid in the flow chamber of the torque converter or to support the realization of a minimum pressure of a fluid in the flow chamber of the torque converter.

[0022] This means that in an alternative embodiment to the electrically driven pump or in addition to the torque converter itself, a pump is mechanically connected to the pump wheel or the turbine wheel of the torque converter to ensure a minimum pressure of a fluid in the flow chamber of the torque converter or to support the realization of a minimum pressure of a fluid in the flow chamber of the torque converter and is consequently driven by the torque converter.

[0023] The pump serves to supply the torque converter with fluid, particularly oil, which simultaneously cools the torque converter. Furthermore, the electric drive unit can be designed such that the pump can be used to actuate the clutch.

[0024] Furthermore, the hybrid drive system may comprise a cooling circuit configured to dissipate heat from the electric drive motor as well as from the torque converter.

[0025] This means that the electric drive motor and the torque converter are part of the same cooling circuit, allowing for efficient use of other components in the cooling circuit. Furthermore, this shared cooling circuit has the advantage that operational heating occurs alternately in the electric drive motor and the torque converter, ensuring reliable cooling of both components with minimal equipment complexity.

[0026] In a further advantageous embodiment, the hybrid drive system further comprises a first cooling circuit configured to dissipate heat from the electric drive machine and / or a second cooling circuit configured to dissipate heat from the torque converter.

[0027] In this embodiment, the performance of a respective cooling circuit can be optimally adapted to the thermal conditions prevailing on or in the hybrid drive system and to the thermal conditions prevailing in or on the torque converter.

[0028] The pump, also known as the oil pump, can be part of the cooling circuit in which the torque converter is integrated. If the electric drive motor is also integrated into this cooling circuit, the pump also indirectly serves to cool the electric drive motor.

[0029] In addition, the hybrid drive system can further comprise a lubrication system with which lubricant can be supplied to the transmission gear, wherein the pump for generating a lubricant volume flow is a component of the lubrication system.

[0030] This means that in this embodiment, the pump assigned to the torque converter has a multiple function, namely supplying the torque converter, possibly supporting the cooling function and also supplying the transmission gear with lubricant.

[0031] In addition, it is advantageously provided that the hybrid drive system also has an axle mechanically coupled to the output device.

[0032] The output device is designed in particular as an output shaft, the rotational axis of which essentially corresponds to the torque transmission path of the hybrid drive system according to the invention from the electric drive motor to the output device.

[0033] In an advantageous embodiment of the hybrid drive system, this further comprises a differential gear which is mechanically coupled on the one hand to the output device of the electric drive unit and on the other hand to the axle for the purpose of transmitting torque from the electric drive unit to the axle.

[0034] According to a further advantageous embodiment, the internal combustion engine is coupled to the output device in the torque transmission path between the torque converter and the output device, in particular to a transmission gear for transmitting the torque provided by the torque converter.

[0035] In this embodiment, the torque provided by the internal combustion engine is therefore used directly at the output device.

[0036] The hybrid drive system can have an additional transmission gear associated with the internal combustion engine, which enables a continuously variable or stepped, variable or fixed transmission of the torque provided by the internal combustion engine.

[0037] According to a further embodiment, the hybrid drive system further comprises a generator which is mechanically coupled to the internal combustion engine and electrically conductively coupled to the electric drive machine for the purpose of being driven by the internal combustion engine, converting mechanical energy into electrical energy and supplying generated electrical energy to the electric drive machine.

[0038] Here, it is particularly provided that the mechanical coupling of the internal combustion engine with the torque transmission path between the torque converter and the output device takes place behind a power split of the torque transmission path from the internal combustion engine to the generator.

[0039] In addition, the hybrid drive system can further comprise a planetary gear system, by means of which the mechanical coupling of the internal combustion engine to the output device is realized. Accordingly, it is provided that both the electric drive motor and the internal combustion engine are connected to the planetary gear system, which is part of the respective torque transmission path from the electric drive motor to the output device and also from the internal combustion engine to the output device.

[0040] The planetary gear can be switchable, stepped or continuously variable, realizing a variable gear ratio.

[0041] Here, too, the hybrid drive system can have an additional transmission gear associated with the internal combustion engine, which enables a continuously variable or stepped, variable or fixed transmission of the torque provided by the internal combustion engine.

[0042] In one embodiment of the hybrid drive system according to the invention, this additional transmission gear can also be supplemented or replaced by a second electric drive motor in order to vary the torque present in the drive train of the internal combustion engine.

[0043] According to a further advantageous embodiment, the internal combustion engine with the output device is coupled in the torque transmission path between the torque converter and the output device to a transmission gear for transmitting the torque provided by the torque converter, wherein the transmission gear combines continuously or stepwise switchable transmission ratios with fixed transmission ratios.

[0044] According to a further embodiment, the output device comprises a driven axle coupled to the torque converter, and the hybrid drive system has a further driven axle, with the internal combustion engine coupled to the further driven axle. In this case, too, the torque provided by the internal combustion engine is used directly at the output device.

[0045] Here, the output device thus comprises two driven axles: one driven axle driven by the electric drive motor and another driven axle driven by the internal combustion engine. Both driven axles are components of the output device.

[0046] However, it should not be excluded that the drive train formed by the internal combustion engine and the further driven axle comprises a further electric machine and a further torque converter, which can also implement the general function of the present invention in this drive train.

[0047] In a further embodiment according to the invention, the hybrid drive system further comprises a generator which is mechanically coupled to the internal combustion engine and electrically conductively coupled to the electric drive machine for the purpose of being driven by the internal combustion engine, converting mechanical energy into electrical energy and supplying generated electrical energy to the electric drive machine.

[0048] In this embodiment of the hybrid drive system according to the invention, no mechanical coupling of the internal combustion engine with the output device is provided.

[0049] Accordingly, the torque provided by the internal combustion engine is not used directly by the output device, but is converted into electrical energy, which in turn can be used by the electric drive motor to drive the output device. In a further variation, this design can additionally include a mechanical bridging device between the generator and the electric drive motor to create a mechanical bridge between the internal combustion engine and the electric drive motor, and consequently with the output device, thus enabling direct drive by the internal combustion engine if necessary.

[0050] In the torque transmission paths of the present embodiments that are directly coupled to the internal combustion engine, a separating clutch can optionally be arranged in each case in order to enable the operation of the internal combustion engine to be coupled or uncoupled as required.

[0051] Furthermore, in particular the embodiments which comprise a generator can also comprise an electrical energy storage device in the form of one or more batteries in which generated electrical energy can be stored and used by the electrical drive device when required.

[0052] The invention described above will be explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, and it should be noted that the embodiments shown in the drawings are not limited to the dimensions shown. It is shown in Fig. 1: a hybrid drive arrangement with a hybrid drive system according to the invention, according to a first embodiment, Fig. 2: a hybrid drive arrangement with a hybrid drive system according to the invention, according to a second embodiment, Fig. 3: a hybrid drive arrangement with a hybrid drive system according to the invention, according to a third embodiment, Fig. 4: a hybrid drive arrangement with a hybrid drive system according to the invention, according to a fourth embodiment, Fig. 5: a hybrid drive arrangement with a hybrid drive system according to the invention, according to a fifth embodiment and Fig. 6: a hybrid drive arrangement with a hybrid drive system according to the invention, according to a sixth embodiment.

[0053] In Fig. 1 shows a hybrid drive arrangement 2 with a hybrid drive system 1 according to the invention, according to a first embodiment.

[0054] The hybrid drive arrangement 2 comprises the hybrid drive system 1, a differential gear 32 mechanically coupled to the hybrid drive system 1, and an axle 33 coupled to the differential gear 32, on which axle vehicle wheels 34 are arranged in a rotationally fixed manner.

[0055] The hybrid drive system 1 comprises an electric drive machine 10, which is essentially an electric motor, a torque converter 20, an internal combustion engine 40 and an output device 31, which realizes the mechanical coupling of the hybrid drive system 1 with the differential gear 32, so that torque provided by the electric drive machine 10 can be transmitted to the vehicle wheels 34.

[0056] A clutch 25 is arranged parallel to the torque converter 20. The clutch 25 is preferably designed as a normally closed clutch, but can alternatively also be a normally open clutch or a so-called normally stay clutch. A torque transmission path between the electric drive motor 10 and the output device 31 can be realized via the clutch 25 and / or the torque converter 20, depending on the circuit or the state of the clutch 25.

[0057] The electric drive machine 10 has a rotor 11 and a stator 12, wherein the rotor 11 is arranged rotatably relative to the stator 12 and is mechanically coupled to the torque converter 20 and the clutch 25 for transmitting torque.

[0058] In the torque transmission path between the electric drive motor 10 and the output device 31, a transmission gear 30 is arranged after the torque converter 20 or after the clutch 25, for transmitting the torque provided by the torque converter 20 and / or by the clutch 25.

[0059] The torque converter 20 comprises a pump impeller 21, a turbine impeller 22, a stator 23, and a freewheel 24. In its design and function, the torque converter 20 is thus essentially similar to a so-called Trilok converter. The stator 23 is mounted on the freewheel 24, so that the torque converter 20 automatically switches to the purely hydrodynamic coupling. It is designed such that the stator 23 rotates freely after switching, so that no more torque can be supported and the input and output torques are equal. The pump impeller 21 is mechanically coupled to the rotor 11 of the electric machine 10, and the turbine impeller 22 is mechanically coupled to the transmission gear 30.

[0060] The torque converter 20 can be operated in a so-called slip mode, whereby the speed of the pump wheel 21 can be increased due to torque differences occurring between the two wheels 21, 22. Accordingly, a correspondingly increased torque can be made available at the turbine wheel 22. A torque demand at the output device 31 or at the vehicle wheels 34 can thus be easily responded to by adjusting the torque converter 20, or an increased torque can be made available by increasing the speed of the electric drive motor 10.

[0061] Also shown is the internal combustion engine 40, which is mechanically coupled to the output device 31 to apply torque to the latter. The torque transmission path between the internal combustion engine 40 and the output device 31, just like the torque transmission path between the electric drive device 10 and the output device 31, includes the transmission gear 30. The transmission gear 30 is thus configured to transmit the torque provided by the electric drive device 10 and the internal combustion engine 40.

[0062] In the embodiment shown here, a further transmission gear 41 is also arranged in the torque transmission path between the internal combustion engine 40 and the output device 31.

[0063] The transmission gear 30 realizes a fixed transmission ratio of the torque provided by the electric drive device 10 or the torque converter 20, wherein the further transmission gear 41 realizes a variable transmission ratio of the torque provided by the internal combustion engine 40 in a continuously variable or stepped manner.

[0064] During operation of a motor vehicle comprising the hybrid drive system 1 according to the invention, torque provided by the electric drive machine 10 can be transmitted via the torque converter 20 or the clutch 25 to the transmission gear 30 and then through the output device 31 to the differential gear 32 and from there to the axle 33 and finally to vehicle wheels 34, wherein torque provided by the internal combustion engine 40 can be transmitted via the further transmission gear 41 and the transmission gear 30 and then also through the output device 31 to the differential gear 32 and from there to the axle 33 and finally to vehicle wheels 34.

[0065] Because the torque provided by the electric drive machine 10 can be transmitted via the torque converter 20, the electric drive unit 1 according to the invention can cover a wider torque range than that provided by the electric drive machine 10 alone, due to the torque variation by means of the torque converter 20.

[0066] Fig. 2 shows a hybrid drive arrangement 2 with a hybrid drive system 1 according to the invention according to a second embodiment. The second embodiment in Fig. 2 is essentially in accordance with the Fig. 1, with the difference that no further transmission gear 41 is arranged in the torque transmission path between the internal combustion engine 40 and the output device 31. The transmission gear 30 here also combines a continuously variable or stepped shiftable transmission ratio with a fixed transmission ratio. Thus, in contrast to the first embodiment, the second embodiment does not allow a fixed transmission ratio for the torque provided by the electric drive motor 10 via the clutch 25 or the torque converter 20, but rather a shiftable transmission ratio.

[0067] In Fig. 3 shows a hybrid drive arrangement 2 with a hybrid drive system 1 according to the invention according to a third embodiment.

[0068] The structure of a part of the hybrid drive arrangement 2 shown here essentially corresponds to that of Fig. 1, however, the two drive machines, electric drive machine 10 and internal combustion engine 40, are designed here to drive different axles 33, 38.

[0069] The torque transmission path shown here between the electric drive unit 10 and the output device 31 as well as the subsequent transmission of the torque via a differential gear 32 to the driven axle 33, on which vehicle wheels 34 are arranged, corresponds to the transmission path of the torque from the electric drive unit 10 to the vehicle wheels 34 from Fig. 1.

[0070] The torque transmission path from the internal combustion engine 40 runs in Fig. 3 initially as in Fig. 1 also has another transmission gear 41, but different to Fig. 1 then via a transmission gear 35 to a further driven axle 38, via a further drive device 36, to a further differential gear 37 and from there to a further driven axle 38 and to further vehicle wheels 39. The hybrid drive system 1 according to the invention thus enables a drive of several vehicle axles 33, 38 in this embodiment.

[0071] Fig. 4 shows a hybrid drive arrangement 2 with a hybrid drive system 1 according to the invention according to a fourth embodiment.

[0072] The hybrid drive system 1 according to Fig. 4 corresponds to a large extent to the hybrid drive system 1 according to Fig. 1.

[0073] The embodiments according to the Fig. 4 and Fig. 1 differ only in the arrangement of an additional planetary gear 42 in the embodiment according to Fig. 4 compared to the embodiment according to Fig. 1.

[0074] The planetary gear 42 is arranged in the torque transmission path between the electric drive unit 10 and the output device 31, and also between the torque converter 20 or the clutch 25 and the transmission gear 30. Thus, the planetary gear 42 is also arranged in the torque transmission path between the internal combustion engine 40 and the output device 31, or between the additional transmission gear 41 and the transmission gear 30.

[0075] The planetary gear 42 here implements a switchable, variable transmission ratio. The torque provided by the drive motors 10, 40 of the hybrid drive system 1 is thus transmitted in the planetary gear 42, instead of Fig. 1 in the transmission gear 30.

[0076] Fig. 5 shows a hybrid drive arrangement 2 with a hybrid drive system 1 according to the invention according to a fifth embodiment.

[0077] It is evident that the illustrated hybrid drive system 1 is at least partially similar to the hybrid drive system 1 from Fig. 1 corresponds.

[0078] The structure, arrangement and functioning of the elements electric drive device 10, torque converter 20, transmission gear 30, output device 31, differential gear 32, axle 33 and vehicle wheels 34 are essentially identical to the embodiment according to Fig. 1, so that for its explanation refer to the description Fig. 1 is referred to.

[0079] Also shown here is a generator 44, which is connected to the electric drive motor 10 via electrical lines 45 for transmitting electrical energy. An inverter 46 is integrated into the electrical line 45 and is configured to provide alternating voltage or alternating current for an electrical consumer when operated by a direct voltage source. The generator 44 is also mechanically connected to the internal combustion engine 40 for the purpose of being driven by the internal combustion engine 40, converting mechanical energy into electrical energy, and supplying the generated electrical energy to the electric drive motor 10.

[0080] In addition, a mechanical bridging device 47 is included in the hybrid drive system 1, which is mechanically connected to the generator 44 and the electric drive machine 10 in order to realize a mechanical bridging between the internal combustion engine 40 and the electric drive machine 10 and consequently with the output device 31 in order to enable a direct drive by the internal combustion engine 40 if required.

[0081] Shown in Fig. 6 is a hybrid drive arrangement 2 with a hybrid drive system 1 according to the invention according to a sixth embodiment.

[0082] The hybrid drive arrangement 2 from Fig. 6 largely corresponds to the hybrid drive arrangement 2 according to Fig. 5.

[0083] The only difference is that in the embodiment according to Fig. 6 no mechanical bridging device 47 is present. Instead, a power split 43 is arranged in the torque transmission path between the internal combustion engine 40 and the generator 44. The power split 43 directs the torque provided by the internal combustion engine 40 to the generator 44 on the one hand and directly to the transmission gear 30 on the other hand. In this way, the hybrid drive system 1 combines Fig. 6 similar to Fig. 5, an operation of the electric drive machine 10 with an operation of the internal combustion engine 40 and the possibility of increasing the range by generating electrical energy through the operation of the internal combustion engine 40.

[0084] The inventive design of the electric drive system proposed here makes it possible to combine a wide range of applications of the electric drive motor with optimal driving operation of a motor vehicle equipped therewith with low investment requirements.

Claims

[1] Hybrid drive system (1) for an at least partially electrically driven motor vehicle, comprising an electric drive motor (10) and an output device (31) for transmitting a torque provided by the electric drive motor (10) to driven vehicle wheels (34) of a motor vehicle, and comprising a torque converter (20) arranged in the torque transmission path between a rotor (11) of the electric drive motor (10) and the output device (31) for adapting the torque provided by the electric drive motor (10) to a respective torque requirement, wherein the hybrid drive system (1) further comprises an internal combustion engine (40) for converting chemical energy into kinetic energy for at least indirectly utilizing the kinetic energy to apply a torque to the output device (31),wherein the internal combustion engine (40) is coupled to the output device (31) in the torque transmission path between the torque converter (20) and the output device (31), , characterized by that the internal combustion engine (40) with the output device (31) is coupled in the torque transmission path between the torque converter (20) and the output device (31) to a transmission gear (30) for transmitting the torque provided by the torque converter (20), wherein the transmission gear (30) combines continuously or stepwise switchable transmission ratios with fixed transmission ratios. [2] Hybrid drive system (1) according to claim 1, characterized by that a clutch (25) for separating and opening the torque transmission path between the electric drive machine (10) and the output device (31) is arranged parallel to the torque converter (20). [3] Hybrid drive system (1) according to one of claims 1 and 2, characterized by that a transmission gear (30) for transmitting the torque provided by the torque converter (20) is arranged in the torque transmission path between the torque converter (20) and the output device (31). [4] Hybrid drive system (1) according to one of the preceding claims, characterized by that the torque converter (20) is a Trilock converter.

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