Drive train for a hybrid motor vehicle

Abstract

A drive train for a hybrid motor vehicle is disclosed. The drive train includes a drive shaft for introducing a torque produced in an internal combustion engine, a transmission input shaft, which can be coupled to the drive shaft by a first clutch, and a steplessly adjustable variator coupled to the transmission input shaft for converting and transmitting the torque to an output shaft. The drive train also includes an electric machine for introducing an electrically produced torque, wherein the electric machine has a rotor, which can be made to interact with a stator, and the rotor can be coupled to the transmission input shaft by a second clutch. A direct drive stage is provided, which can be coupled to the rotor of the electric machine by a third clutch, for transmitting the torque produced in the electric machine past the variator to the output shaft. The first clutch, the second clutch and the third clutch are arranged radially on the inside in relation to the rotor.

Claims

1. A drive train for a hybrid motor vehicle, comprising: a drive shaft for introducing a torque produced in an internal combustion engine, a transmission input shaft, which can be coupled to the drive shaft by a first clutch, a steplessly adjustable variator coupled to the transmission input shaft for converting and transmitting the torque to an output shaft, an electric machine for introducing an electrically produced torque, wherein the electric machine has a rotor, which can be made to interact with a stator, and the rotor can be coupled to the transmission input shaft by a second clutch, and a direct drive stage, which can be coupled to the rotor of the electric machine by a third clutch, for transmitting the torque produced in the electric machine past the variator to the output shaft, wherein the first clutch, the second clutch and the third clutch are arranged radially on the inside in relation to the rotor and are at least partially overlapped by the rotor in an open state or a closed state, when viewed in a radial direction.

2. The drive train as claimed in claim 1, wherein the second clutch and/or the third clutch are designed as wedge clutches.

3. The drive train as claimed in claim 2, wherein the rotor has a transmission disk which projects radially inward from the rotor, for introducing the torque produced in the electric machine, wherein the transmission disk has a second transmission element for transmitting the torque in the second clutch designed as a wedge clutch, and/or has a third transmission element for transmitting the torque in the third clutch designed as a wedge clutch.

4. The drive train as claimed in claim 1, wherein a motor housing covering the electric machine is provided, wherein the motor housing has an oil supply channel for supplying the third clutches with hydraulic oil, wherein the hydraulic oil is passed via an axially movable actuating element of the third clutch.

5. The drive train as claimed in claim 1, wherein the variator has an input-side driving cone pulley pair and a driven cone pulley pair, which is coupled to the driving cone pulley pair, wherein the driving cone pulley pair has an adjustable input pulley, which can be moved axially to a limited extent with aid of an input-side axial retaining element, and the driven cone pulley pair has an adjustable output pulley, which can be moved axially to a limited extent with the aid of an output-side axial retaining element, wherein an input bearing for an input-side support of the variator at least partially overlaps the input-side axial retaining element, when viewed in a radial direction, and/or an output bearing for an output-side support of the variator at least partially overlaps the output-side axial retaining element, when viewed in the radial direction.

6. The drive train as claimed in claim 1, wherein a variator housing, which covers the variator, is provided, wherein the variator housing and/or a motor housing covering the electric machine at least partially overlaps the direct drive stage, wherein the direct drive stage is fastened to the variator housing.

7. The drive train as claimed in claim 1, wherein the variator has an input-side variator drive shaft coupled to the transmission input shaft, wherein the variator drive shaft is arranged substantially coaxially with the transmission input shaft, and the first clutch and/or the second clutch are/is coupled for conjoint rotation to the variator drive shaft on an output side, by a plug-and-socket connection, or wherein the variator drive shaft is arranged laterally offset with respect to the transmission input shaft by an intermediate gearwheel pair.

8. The drive train as claimed in claim 1, wherein the direct drive stage has an intermediate wheel, which meshes with the third clutch, wherein the intermediate wheel meshes with a variator output wheel mounted on an output-side variator output shaft, wherein the variator output wheel is coupled to the output shaft by a differential.

9. The drive train as claimed in claim 1, wherein the direct drive stage has an intermediate shaft, which meshes with the third clutch, wherein the intermediate shaft is coupled to the output shaft by a differential.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure is explained below by way of example by means of preferred illustrative embodiments with reference to the attached drawings, wherein the features presented below can each form an aspect of the present disclosure both individually and in combination. In the drawings:

(2) FIG. 1: shows a schematic basic illustration of a first embodiment of a drive train,

(3) FIG. 2: shows a schematic sectional view of the drive train from FIG. 1,

(4) FIG. 3: shows a schematic basic illustration of a second embodiment of a drive train, and

(5) FIG. 4: shows a schematic basic illustration of a fourth embodiment of a drive train.

DETAILED DESCRIPTION

(6) The drive train 10 illustrated in a developed side view and in a plan view in FIG. 1 and illustrated in more detail in FIG. 2 has a drive shaft 12, which is a hub that can be coupled to a crankshaft of an internal combustion engine via a torsional vibration damper 14 designed as a dual-mass flywheel. The drive shaft 12 can be coupled to a transmission input shaft 18 by means of a first clutch 16 designed as a multiplate clutch. The drive train 10 additionally has an electric machine 20, which has a stator 22, which has an electromagnet, and a rotor 24, which has a permanent magnet that can be made to interact with the stator 22. Connected to the rotor 24 for conjoint rotation is a transmission disk 26, which is supported and mounted on the transmission input shaft 18. With the aid of a second clutch 28 designed as a hydraulically actuable wedge clutch, the transmission disk 26 and hence the rotor 24 of the electric machine 20 can be coupled to the transmission input shaft 18 for conjoint rotation in order to introduce electric power generated in the motor mode in the electric machine 20 into the drive train 10 or to convert mechanical power taken from the drive train into electrically storable energy in the electric machine 20 operated in the generator mode.

(7) The speed and torque of the transmission input shaft 18 can be converted in a variator 30 designed as a belt-driven CVT. For this purpose, a variator drive shaft 32 is coupled to the transmission input shaft 18. In the embodiment illustrated, the variator drive shaft 32 and the transmission input shaft 18 can be combined to form an integral common shaft. The variator drive shaft 32 drives an input-side driving cone pulley pair 34, which is coupled by a traction means 36 designed as a belt drive to an output-side driven cone pulley pair 38. Depending on the position of the driving cone pulley pair 34 and of the driven cone pulley pair 38, the transmission ratio of the variator 30 can be adjusted in a stepless manner. The driven cone pulley pair 38 drives a variator output shaft 40, which can have a modified speed and a modified torque in comparison with the transmission input shaft 18. A variator output wheel 42 is mounted on the variator output shaft 40. The variator output wheel 42 can be coupled to the variator output shaft 40 for conjoint rotation with the aid of a variator clutch 44. Particularly for reversal of the direction of rotation and/or additional ratio conversion, the variator output wheel 42 can be coupled via a connecting wheel 46 to a differential 48, which, in turn, has output shafts 50 leading to driven wheels.

(8) With the aid of a direct drive stage 52, the power flow coming from the transmission input shaft 18 can be directed past the variator 30 to the differential 48 and the output shaft 50. For this purpose, the transmission disk 26 of the rotor 24 can be coupled to the direct drive stage 52 by means of a third clutch 54 designed as a hydraulically actuable wedge clutch. In the illustrative embodiment shown, the direct drive stage 52 is coupled to the variator output wheel 42 via an intermediate wheel 56, and therefore only minimal installation space is required for the implementation of the direct drive stage 52.

(9) As illustrated in FIG. 2, the intermediate wheel 56 is mounted on a shaft 58 screwed to the variator 30, thus enabling the direct drive stage 52 to be preassembled with the variator 30. As a result, the first clutch 16, the second clutch 28 and the third clutch 54 can be mounted on the drive shaft 18, in particular by way of a plug-and-socket connection designed as splines, and can be connected to the variator 30 together with the electric machine 20 and a motor housing 60 covering the electric machine 20. During this process, the motor housing 60 can be fastened to a variator housing 62 covering the variator 30. In the motor housing 60 it is possible to provide an oil supply channel 64, via which hydraulic oil provided for the actuation of the third clutch 54 can be fed to the third clutch 54. To supply additional hydraulic loads in the drive train 10, e.g. for actuating the first clutch 16 and/or for actuating the second clutch 28 and/or for actuating the driving cone pulley pair 34 of the variator 30 and/or for actuating the driven cone pulley pair 38 of the variator 30, the transmission input shaft 18 and the variator drive shaft 32 can be of hollow design and/or can be provided with corresponding supply channels. The transmission input shaft 18 and/or the variator drive shaft 32 can preferably be coupled to a pump 66, which can build up the hydraulic pressure required for this purpose. In particular, the pump 66 is provided on the side of the variator 30 which faces away from the electric machine 20.

(10) In order to change the transmission ratio of the variator 30, one of the cone pulleys of the driving cone pulley pair 34 is designed as a hydraulically axially movable adjustable input pulley 67. Depending on the axial relative position of the adjustable input pulley 67, the traction means 36 moves to a different radius. At the same time, one of the cone pulleys of the driven cone pulley pair 38 is designed as an axially movable adjustable output pulley 68, which, for its part, changes its relative position when the relative position of the adjustable input pulley 67 changes in order to ensure that the tension belt 36 remains tensioned. During this process, provision can be made for the adjustable output pulley 68 to be moved axially by hydraulic means in a manner corresponding to the adjustable input pulley 67. In addition or as an alternative, a return spring 70 acting on the adjustable output pulley 68 can be provided, against the spring force of which a hydraulic pressure must be built up at the adjustable input pulley 67.

(11) The variator drive shaft 32 can be mounted on the variator housing 62 by means of an input bearing 72, while the variator output shaft 40 can be mounted on the variator housing 62 by means of an output bearing 74. The most distant position of the driving cone pulley pair 34 can be limited by an input-side axial retaining element 76 designed as a retaining ring, while the most distant position of the driven cone pulley pair 38 can be limited by an output-side axial retaining element 78 designed as a retaining ring. The input-side axial retaining element 76 can be inserted in a groove in the variator drive shaft 32, while the output-side axial retaining element 78 can be inserted in a groove in the variator output shaft 40. In the illustrative embodiment shown, the input-side axial retaining element 76 is provided radially on the inside in relation to the input bearing 72 and, for this purpose, is inserted into a corresponding recess in the input bearing 72. In corresponding fashion, the output-side axial retaining element 78 is provided radially on the inside in relation to the output bearing 74 and, for this purpose, is inserted into a corresponding recess in the output bearing 74. The axial installation space requirement of the variator 30 and thus of the drive train 10 is thereby reduced. Likewise, the axial installation space requirement of the drive train 10 is reduced by the fact that the first clutch 16, the second clutch 28 and the third clutch 54 are arranged at least partially, preferably completely, radially within the electric machine 20, in particular radially within the rotor 24. When viewed in the radial direction, the rotor 24 can overlap the first clutch 16, the second clutch 28 and the third clutch 54 at least partially, preferably completely.

(12) In the embodiment of the drive train 10 illustrated in FIG. 3, compared with the embodiment of the drive train 10 illustrated in FIG. 1 and FIG. 2, the intermediate wheel 56 meshing with the variator output wheel 42 is replaced by an intermediate shaft 80 meshing with the differential 48. As a result, a particularly small number of gearwheel pairs is used for a power flow directed past the variator 30.

(13) In the embodiment of the drive train 10 illustrated in FIG. 4, in comparison with the embodiment of the drive train 10 illustrated in FIG. 3, the variator drive shaft 32 is not arranged coaxially with the transmission input shaft 18 but is arranged laterally offset. Here, the variator drive shaft 32 is coupled to the transmission input shaft 18 by an intermediate gearwheel pair 82, thereby making it possible to eliminate the connecting wheel 46. The intermediate gearwheel pair 82 can assume the function of the connecting wheel 46 and can thereby replace the connecting wheel 46. In the illustrative embodiment shown, a range change unit 84 is furthermore provided, which couples the variator output shaft 40 to a coaxial connecting shaft 86 via a planetary transmission. The range change unit 84 can have a brake, which can optionally fix a ring gear of the planetary transmission, for example, in order to modify the transmission ratio and/or the direction of rotation between the variator output shaft 40 and the connecting shaft 86. In this case, the sun wheel of the planetary transmission can be connected to the variator output shaft 40, while the planet carrier of the planetary transmission can be connected to the connecting shaft 86 by means of the variator clutch 44. The connecting shaft 86 can be mounted to allow relative rotation on the variator output shaft 40. Moreover, the variator output wheel 42 can be connected to the connecting shaft 86 for conjoint rotation.

LIST OF REFERENCE SIGNS

(14) 10 drive train 12 drive shaft 14 torsional vibration damper 16 first clutch 18 transmission input shaft 20 electric machine 22 stator 24 rotor 26 transmission disk 28 second clutch 30 variator 32 variator drive shaft 34 driving cone pulley pair 36 traction means 38 driven cone pulley pair 40 variator output shaft 42 variator output wheel 44 variator clutch 46 connecting wheel 48 differential 50 output shaft 52 direct drive stage 54 third clutch 56 intermediate wheel 58 shaft 60 motor housing 62 variator housing 64 oil supply channel 66 pump 67 adjustable input pulley 68 adjustable output pulley 70 return spring 72 input bearing 74 output bearing 76 input-side axial retaining element 78 output-side axial retaining element 80 intermediate shaft 82 intermediate gearwheel pair 84 range change unit 86 connecting shaft