Powertrain for a hybrid vehicle

Abstract

Powertrain for a hybrid vehicle, comprising an internal combustion engine (12) having a motor shaft (18) for providing torque to drive the hybrid vehicle, and an electric machine (30) for providing torque to drive the hybrid vehicle, wherein the motor shaft (18) can be coupled to a motor vehicle transmission (16) for shifting gears (1 to 8) via a transmission clutch (14), and the motor vehicle transmission (16) has a transmission output shaft (28), wherein a ring gear (62) of a differential gear (29) of the hybrid vehicle can be driven by means of the transmission output shaft (28), and the electric machine (30) can be coupled to a drive shaft (60) by means of a clutch (K3), and the ring gear (62) can be driven by means of the drive shaft (60), characterized in that the ring gear (62) meshes with a connecting gear (64).and the connecting gear (64) meshes with the drive shaft (60) via a crown gear transmission, the crown gear transmission comprising a spur gear (66) and a crown gear (68), wherein the spur gear (66) is connected to the drive shaft (60) and the crown gear (68) is part of the connecting gear (64), which has a spur tooth (70) for meshing with a spur tooth (72) of the ring gear (62).

Description

[0001] The invention relates to a drive train for a hybrid motor vehicle, with the aid of which a torque generated by an internal combustion engine and / or an electric machine can be transmitted.

[0002] US 2010 / 0 216 584 A1 discloses a drive train for a hybrid motor vehicle in which an electric motor has a rotor configured as a ring gear of a planetary gear. The ring gear is coupled to a sun gear via planetary gears supported by a planet carrier. The sun gear is connected in a rotationally fixed manner to a transmission output shaft of a motor vehicle transmission in order to electrically drive the hybrid motor vehicle. The planet carrier is connected to a shaft, which is connected via a gearing to a motor shaft of an internal combustion engine in order to start the internal combustion engine with the aid of the electric motor.

[0003] There is a constant need to reduce the space required for a powertrain.

[0004] DE 10 2010 006 043 A1 discloses a drive train for a hybrid motor vehicle according to the preamble of claim 1.

[0005] DE 10 2013 105 026 A1, DE 10 2007 029 610 A1 and DE 10 2011 077 590 A1 disclose further prior art.

[0006] The object of the invention is to demonstrate measures that enable a drive train with a small installation space requirement.

[0007] The object is achieved according to the invention by a drive train having the features of claim 1 and by a drive train having the features of claim 2.

[0008] Preferred embodiments of the invention are specified in the subclaims, which may each individually or in combination represent an aspect of the invention.

[0009] The drivetrain for the hybrid vehicle comprises an internal combustion engine with a motor shaft for providing torque to drive the hybrid vehicle, and an electric motor for providing torque to drive the hybrid vehicle. The motor shaft can be coupled to a motor vehicle transmission via a transmission clutch for shifting gears. The motor vehicle transmission has a transmission output shaft by means of which a ring gear of a differential gear of the hybrid vehicle can be driven. The electric motor can be coupled to a drive shaft by means of a clutch, and the ring gear can be driven by means of this drive shaft.

[0010] When the electric motor is operating and the clutch associated with the drive shaft is engaged, the differential's crown gear is driven via the drive gear, thereby providing electric motor torque to drive the hybrid vehicle. The electric motor therefore acts directly on the drivetrain on the output side of the vehicle's transmission. Consequently, the electric motor can be connected to the combustion engine and the vehicle's transmission with minimal structural resources and minimal installation space.

[0011] According to claim 1, the ring gear meshes with a connecting gear, and the connecting gear meshes with the drive shaft via a crown gear. The connecting gear thus represents the connection between the ring gear and the crown gear of the drive shaft. The connecting gear functions as an intermediate gear and is therefore not connected to a torque-transmitting shaft in the area of ​​its axis. This variant is characterized by a compact design and thus requires very little installation space.

[0012] According to claim 1, the crown gear transmission is designed and arranged such that it comprises a spur gear and a crown gear, wherein the spur gear is connected to the drive shaft, and the crown gear is a component of the connecting gear, which has a spur toothing for engagement with a spur toothing of the ring gear. The connecting gear thus performs both the function of the crown gear, which is assigned to the electric drive, and the function of a spur gear, wherein the connecting gear meshes with a spur toothing of the ring gear in the region of the spur toothing to enable a torque flow between the spur gear, connecting gear, and ring gear.

[0013] According to claim 2, an intermediate shaft is arranged between the drive shaft and the ring gear, with the intermediate shaft and / or the intermediate shaft meshing with the ring gear via a crown gear. In this embodiment, therefore, no connecting gear is provided, but rather an intermediate shaft. This design enables an extremely space-saving arrangement of the elements for transmitting the movement between the electric drive and the ring gear of the differential gear.

[0014] The variant according to claim 2 is preferably further developed in such a way that, with regard to the crown gear transmission on the drive shaft side, the drive shaft is connected to a crown gear, and a spur gear meshes with the crown gear, which is connected to the intermediate shaft. Furthermore, it is advantageously provided that, with regard to the crown gear transmission on the ring gear side, the crown gear is a component of the ring gear, and a spur gear meshes with this crown gear, which is connected to the intermediate shaft.

[0015] The last-mentioned development of the variant according to claim 2 allows a particularly space-saving design of the drive train in the area between the electric drive, specifically the area between the clutch and the ring gear of the differential gear, due to the crown gear assigned to the respective end or both ends of the intermediate shaft.

[0016] Preferably, the spur gear of each of the aforementioned crown gears is designed as a straight spur gear. This design enables simple, cost-effective production of the crown gear in the area of ​​the spur gear.

[0017] According to a preferred development, it is provided that the electric machine, in particular for starting the internal combustion engine, can be coupled to the motor shaft via a switchable planetary gear to provide at least two different gear ratios, wherein an intermediate shaft drivable by the electric machine is connected in a rotationally fixed manner to a sun gear of the planetary gear and can be coupled to the drive shaft by means of the coupling.

[0018] The planetary gear and a connection to the motor shaft following the planetary gear, for example via a toothed chain or a roller chain, provide a gear ratio that, in particular, leads to a reduction in the speed of the electric machine, so that a correspondingly high torque can be introduced to start the combustion engine. For a cold start of the combustion engine, the planetary gear can, for example, provide a gear ratio of 1:3. If the electric machine does not engage the planetary gear directly, but is initially coupled to the intermediate shaft via a gear transmission, an additional gear ratio can be achieved with the help of the gear transmission, which, in particular, leads to an additional reduction in the speed of the electric machine.This allows a correspondingly high torque to be introduced into the planetary gear at a lower speed. The planetary gear can thus be designed for lower speeds and thus lower centrifugal loads, reducing the design requirements for the planetary gear and lowering manufacturing costs. By arranging the electric motor at a distance from the planetary gear, as made possible by the intermediate shaft, and by additionally reducing the speed of the electric motor with the transmission gear, the electric motor can be dimensioned smaller, enabling a drive train with a small installation space requirement.

[0019] The engine shaft of the internal combustion engine can, for example, be a crankshaft or cardan shaft, which can be driven directly or indirectly by combustion of a fuel mixture in the internal combustion engine.

[0020] It is particularly advantageous if the electric machine can be coupled to the at least one auxiliary unit of the hybrid motor vehicle via a secondary shaft arranged radially to the motor shaft of the electric machine. This makes it possible to drive auxiliary units, such as an oil pump, water pump, air conditioning compressor of an air conditioning system, or the like, mechanically, in particular via a belt drive, with the aid of the electric machine, even when the combustion engine is switched off. In addition, the combustion engine can have a torque output, for example a pulley or sprocket connected to the motor shaft, in order to mechanically drive the auxiliary units via the same mechanical connection used by the secondary shaft.In particular, the auxiliary units driven via the auxiliary shaft can be positioned on a side of the internal combustion engine facing away from the motor vehicle transmission, while the electric motor can be coupled to the motor shaft via the planetary gear on a side facing the motor vehicle transmission. The axial distance between the connection to the motor shaft and a connection to the auxiliary units, particularly via the belt drive, can be easily bridged by the auxiliary shaft and the intermediate shaft, preferably outside the internal combustion engine.

[0021] Preferably, the electric machine is positioned at an axial height of the internal combustion engine, radially spaced from the internal combustion engine, with the intermediate shaft and / or the auxiliary shaft, in particular, being positioned radially between the internal combustion engine and the electric machine. The electric machine can thus be positioned radially next to the internal combustion engine, eliminating the need to provide axial space for the electric machine between the internal combustion engine and the vehicle transmission. The axial space requirement of the drive train can thus be kept low, ideally length-neutral.

[0022] The invention will be explained below with reference to the accompanying drawings using two preferred embodiments, wherein the features presented below can represent an aspect of the invention both individually and in combination. It shows: Fig. 1 is a schematic diagram of a first embodiment of a drive train for a hybrid motor vehicle, Fig. 2 a schematic diagram of a second embodiment of a drive train for a hybrid motor vehicle

[0023] The Fig. The drive train for a hybrid motor vehicle shown in Figure 1 comprises an internal combustion engine 12, which can be coupled to a motor vehicle transmission 16 via a transmission clutch 14 configured as a dual clutch. The transmission clutch 14 comprises a first partial clutch C1 for coupling a motor shaft 18 of the internal combustion engine 12 to a first transmission input shaft 20 configured as a solid shaft, and a second partial clutch C2 for coupling the motor shaft 18 to a second transmission input shaft 22 configured as a hollow shaft. Within the motor vehicle transmission 16, the transmission input shafts 20, 22 mesh via shiftable gear stages with a first shift shaft 24 for gears 3, 4, 7, and 8, and with a second shift shaft 26 for gears 1, 2, 5, and 6.The first shift shaft 24 meshes via an output gear Ko1 with an input gear K of a transmission output shaft 28, which is coupled via a differential gear 29 to drive wheels (not shown) of the hybrid vehicle to move the hybrid vehicle. The second shift shaft 26 meshes via an output gear Ko2 with the input gear K of the transmission output shaft 28, which is coupled via the differential gear 29 to the drive wheels (not shown) of the hybrid vehicle to move the hybrid vehicle. The torque introduced into the second shift shaft 26 is transmitted to the input gear K or the transmission output shaft 28 via a connection 78, as illustrated by the dashed line.

[0024] The internal combustion engine 12 can be started with the aid of an electric machine 30. For this purpose, the motor shaft 18 of the internal combustion engine 12 has a pulley or sprocket 32, which is coupled to a planetary carrier 36 of a planetary gear 38 via a first belt drive or chain drive 34. The planetary carrier 36 supports planetary gears 40, which mesh with a sun gear 42 and a ring gear 44. The sun gear 42 is connected to an intermediate shaft 46, by means of which the electric machine 30 is connected to the planetary gear 38 via a transmission gear 48, axially spaced apart. The planetary gear 38 has a first clutch K1, with the aid of which the ring gear 44 can be held fixed to the housing, so that, for example, for a cold start of the internal combustion engine, a gear ratio different from 1.0 is set, by means of which the speed of the intermediate shaft 46 can be changed and the corresponding torque on the motor shaft 18 can be increased.With the aid of a second clutch K2, the ring gear 44 can be connected to the intermediate shaft 46 in a rotationally fixed manner, so that, for example, for a warm start of the internal combustion engine 12, a gear ratio of 1.0 is set via the planetary gear when the first clutch K1 is open.

[0025] A coaxial auxiliary shaft 50 is connected to the intermediate shaft 46 in a rotationally fixed manner, in particular in one piece. With the aid of the auxiliary shaft 50, auxiliary units, in particular an air conditioning compressor 54 of a vehicle air conditioning system and a water pump 56, can be driven by the electric motor 30 via a second belt drive 52 when the internal combustion engine 12 is switched off. Furthermore, an oil pump 58 is provided, which in the illustrated embodiment is connected to the motor shaft 18 and can alternatively be driven via the second belt drive 52.

[0026] For purely electric operation of the hybrid vehicle, a drive shaft 60 running coaxially with the intermediate shaft 46 can be rotationally coupled to the intermediate shaft 46 with the aid of a third clutch K3. Via the drive shaft 60, the torque of the electric motor 30 can be introduced past the transmission clutch 14 and the transmission input shafts 20, 22 and, if both the first clutch K1 and the second clutch K2 are disengaged, also past the planetary gear 38 and the motor shaft 18, directly into a ring gear 62 of the differential gear 29. This ring gear 62 meshes with a connecting gear 64, which meshes with the drive shaft 60 via a crown gear. The crown gear has a spur gear 66, designed as a straight spur gear, and a crown gear 68. The spur gear 66 is connected to the drive shaft 60 and the crown gear 68 is part of the connecting gear 64.The connecting gear 64 has a spur toothing 70 for engagement with a spur toothing 72 of the ring gear 62.

[0027] The torque transmission between the transmission output shaft 28 and the crown gear 62 also takes place via a crown gear. This comprises a spur gear 74 and a crown gear 76. The spur gear 74 is designed as a straight spur gear and is connected to the transmission output shaft 28. The crown gear 76 is a component of the crown gear 62.

[0028] For a partial start of the internal combustion engine 12, the first clutch K1 can be closed, while the second clutch K2 and the third clutch K3 are open, so that the additional gear ratio of the planetary gear 38 enables a cold start with high torque requirements and, at the same time, the auxiliary units 54, 56 can be driven. After the internal combustion engine 12 has started, with the clutches K1, K2, K3 in this position, the electric machine 30 can be operated as a motor in order to perform a boost and / or assist function through the additional power input, whereby an additional gear ratio can be provided by the planetary gear 38.The electric machine 30 can also be operated as a generator, so that part of the power of the internal combustion engine 12 can be fed into the electric machine 30, for example, to charge a motor vehicle battery, with an additional gear ratio being provided by the planetary gear 38. In this case, the auxiliary units 54, 56 are driven by the internal combustion engine 12 via the intermediate shaft 46 and the auxiliary shaft 50.

[0029] If the first clutch K1 and the third clutch K3 are disengaged while the second clutch K2 is engaged, a gear ratio of 1.0 is established in the planetary gear set 38, at which, in particular, a warm start of the internal combustion engine 12 can take place. After the internal combustion engine 12 has been started, with the clutches K1, K2, K3 in this position, the electric machine 30 can be operated as a motor in order to perform a boost and / or assist function through the additional power input, wherein in this case no additional gear ratio is provided by the planetary gear set 38. The electric machine 30 can also be operated as a generator, so that part of the power of the internal combustion engine 12 can be introduced into the electric machine 30, wherein in this case no additional gear ratio is provided by the planetary gear set 38.In this case, the auxiliary units 54, 56 are driven by the combustion engine 12 via the intermediate shaft 46 and the auxiliary shaft 50.

[0030] For purely electric operation, the first clutch K1 and the second clutch K2 are disengaged, while the third clutch K3 is engaged. Consequently, the electric machine 30 directly drives the ring gear 62 of the differential gear 29. The internal combustion engine 12 is switched off in purely electric operation and can be started simply by engaging the first clutch K1 or the second clutch K2. The third clutch K3 can remain engaged until the internal combustion engine 12 has started and / or the transmission clutch 14 is to be engaged. When the first clutch K1, the second clutch K2, and the third clutch K3 are disengaged, the power flow from the electric machine 30 to the motor shaft 18 and to the ring gear 62 of the differential gear 29 is interrupted, so that the auxiliary units 54, 56 can be driven by the electric machine 30 even when the internal combustion engine 12 is switched off.

[0031] The auxiliary units 54, 56 can therefore be operated independently of the engine speed. At low speeds, the auxiliary units can rotate faster than the engine and at high speeds, slower than the engine. This can have a positive impact on the design of the auxiliary units and their efficiency. Furthermore, recuperative operation is possible by directing the power flow from a wheel of the hybrid vehicle via the crown gear 62 to the electric motor 30, bypassing the vehicle transmission 16.

[0032] The second embodiment as shown in Fig. 2 differs from that according to the Fig. 1 only by connecting the drive shaft 60 to the ring gear 62. In this respect, identical elements are designated with the same reference numerals for both embodiments of the drive train and the operation of the drive train according to Fig. 2 to the above-described description of Fig. 1.

[0033] In the embodiment according to Fig. 2, an intermediate shaft 80 is arranged between the drive shaft 60 and the ring gear 62. This intermediate shaft 80 meshes with the drive shaft 60 and with the ring gear 62, respectively, via a crown gear transmission. The drive shaft 60 is connected to a crown gear 82, and a spur gear 84, designed as a straight spur gear and connected to the intermediate shaft 80, meshes with the crown gear 82. A component of the ring gear 62 is a crown gear 86. A spur gear 88, designed as a straight spur gear and connected to the intermediate shaft 80, meshes with this.

Claims

[1] Drive train for a hybrid motor vehicle, comprising an internal combustion engine (12) having a motor shaft (18) for providing a torque for driving the hybrid motor vehicle, and an electric machine (30) for providing a torque for driving the hybrid motor vehicle, wherein the motor shaft (18) can be coupled to a motor vehicle transmission (16) for shifting transmission gears (1 to 8) via a transmission clutch (14), and the motor vehicle transmission (16) has a transmission output shaft (28), wherein a ring gear (62) of a differential gear (29) of the hybrid motor vehicle can be driven by means of the transmission output shaft (28), and the electric machine (30) can be coupled to a drive shaft (60) by means of a clutch (K3), and the ring gear (62) can be driven by means of the drive shaft (60), characterized byin that the ring gear (62) meshes with a connecting gear (64), and the connecting gear (64) meshes with the drive shaft (60) via a crown gear, wherein the crown gear has a spur gear (66) and a crown gear (68), wherein the spur gear (66) is connected to the drive shaft (60) and the crown gear (68) is a component of the connecting gear (64), which has a spur toothing (70) for engaging a spur toothing (72) of the ring gear (62). [2] Drive train for a hybrid motor vehicle, comprising an internal combustion engine (12) having a motor shaft (18) for providing a torque for driving the hybrid motor vehicle, and an electric machine (30) for providing a torque for driving the hybrid motor vehicle, wherein the motor shaft (18) can be coupled to a motor vehicle transmission (16) via a transmission clutch (14) for shifting transmission gears (1 to 8), and the motor vehicle transmission (16) has a transmission output shaft (28), wherein a ring gear (62) of a differential gear (29) of the hybrid motor vehicle can be driven by means of the transmission output shaft (28), and the electric machine (30) can be coupled to a drive shaft (60) by means of a clutch (K3), and the ring gear (62) can be driven by means of the drive shaft (60), characterized bythat an intermediate shaft (80) is arranged between the drive shaft (60) and the ring gear (62), wherein the intermediate shaft (80) meshes with the drive shaft (60) and / or the intermediate shaft (80) meshes with the ring gear (62) via a crown gear transmission. [3] Drive train according to claim 2, wherein, with regard to the drive shaft-side crown gear transmission, the drive shaft (60) is connected to a crown gear (82) and a spur gear (84) meshes with the crown gear (82), which is connected to the intermediate shaft (80). [4] Drive train according to claim 2 or 3, wherein, with regard to the crown gear transmission on the crown gear side, the crown gear (86) is a component of the crown gear (62) and a spur gear (88) meshes with this crown gear (86), which is connected to the intermediate shaft (80). [5] Drive train according to one of claims 1, 3 or 4, wherein the spur gear (66, 84, 88) of the respective crown gear is designed as a straight spur gear. [6] Drive train according to one of claims 1 to 5, wherein the electric machine (30), in particular for starting the internal combustion engine (12), can be coupled to the motor shaft (18) via a switchable planetary gear (38) to provide at least two different gear ratios, wherein an intermediate shaft (46) drivable by the electric machine (30) is connected in a rotationally fixed manner to a sun gear (42) of the planetary gear (38) and can be coupled to the drive shaft (60) by means of the clutch (K3). [7] Drive train according to one of claims 1 to 6, wherein the electric machine (30) can be coupled to at least one auxiliary unit (52, 54, 56, 58) of the hybrid vehicle via a secondary shaft (50) arranged radially to the motor shaft of the electric machine (30). [8] Drive train according to one of claims 1 to 7, wherein the electric machine (30) is positioned at an axial height of the internal combustion engine (12) at a radial distance from the internal combustion engine (12). [9] Drive train according to claim 8, wherein the intermediate shaft (80) and / or the auxiliary shaft (50) is positioned in the radial direction between the internal combustion engine (12) and the electric machine (30).

Images