CVT drive train

Abstract

A CVT drive train includes a gearbox input shaft, a secondary drive, a differential, and a continuously adjustable variator. The gearbox input shaft is arranged on a motor side. The secondary drive has a starting device and an electric motor, both arranged coaxially to the gearbox input shaft. The electric motor has a stator, and a rotor arranged radially inside of the stator. The differential has a differential output gear. The continuously adjustable variator has a drive-side disc set, and an output-side disc set coupled to the differential and arranged directly adjacent to the differential output gear in a plan view. The drive-side disc set has a drive-side adjustable disc, and a drive-side fixed disc facing away from the motor side. The output-side disc set has an output-side fixed disc, and an output-side adjustable disc facing away from the motor side.

Claims

1. A continuously variable transmission (CVT) drive train comprising: a gearbox input shaft arranged on a motor side; a secondary drive comprising: a starting device arranged coaxially to the gearbox input shaft; and, an electric motor arranged coaxially to the gearbox input shaft and comprising: a stator; and, a rotor arranged radially inside of the stator; a differential comprising a differential output gear; and, a continuously adjustable variator comprising: a drive-side disc set comprising: a drive-side adjustable disc; and, a drive-side fixed disc located further away from the motor side than the drive-side adjustable disc; and, an output-side disc set, rotatable about a rotation axis, coupled to the differential and arranged directly adjacent to the differential output gear such that a portion of the drive-side disc set at least partially overlaps the differential output gear when viewed in a direction of the rotation axis, the output-side disc set comprising: an output-side fixed disc; and, an output-side adjustable disc located further away from the motor side than the drive-side adjustable disc.

2. The CVT drive train of claim 1, wherein the drive-side disc set comprises a main bearing arranged radially inside of and axially overlapping the electric motor.

3. The CVT drive train of claim 1 further comprising a rotor carrier, wherein: the drive-side disc set comprises a variator drive shaft; and, the rotor is supported on the variator drive shaft by the rotor carrier.

4. The CVT drive train of claim 3 wherein: the rotor carrier is fixedly connected to the gearbox input shaft; and, the gearbox input shaft is connected to the variator drive shaft by: a push-fit toothing; and, a centering seat or a press fit.

5. The CVT drive train of claim 1 further comprising: a housing; a variator output gear; an intermediate shaft; a connecting gear on the intermediate shaft between the variator output gear and the differential; and, an intermediate shaft bearing for the intermediate shaft comprising: a bearing plate fixed to the housing; and, a bearing journal integrally connected to the bearing plate.

6. The CVT drive train of claim 1, further comprising a planetary gear set for forming a reverse gear arranged radially inside of and axially overlapping the electric motor.

7. The CVT drive train of claim 6 further comprising: a braking device for the planetary gear set; and, a device for detecting a circumferential position or a rotation speed arranged radially inside of the electric motor between the starting device and the braking device.

8. The CVT drive train of claim 1 further comprising a clutch arranged radially inside of and axially overlapping the electric motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, features and details of the invention arise from the description below in which various exemplary embodiments are described in detail with reference to the drawing. The drawings show:

(2) FIG. 1 is a partially opened, longitudinal sectional depiction through a drive-side and an output-side disc set of a CVT drive train;

(3) FIG. 2 is a cross-sectional depiction of the CVT drive train in FIG. 1, to illustrate the actual positions of rotation axes; and

(4) FIG. 3 is an enlarged extract from FIG. 1 with an additional planetary gear set for forming a mechanical reverse gear.

DETAILED DESCRIPTION

(5) FIG. 1 shows, in a partially angled longitudinal section, a CVT drive train 10 of a motor vehicle with a drive shaft 12. The drive shaft 12 is rotatable about a rotation axis 13. The drive shaft 12 is a hub which can be coupled to a crankshaft of an internal combustion engine via a torsional vibration damper 14, here configured as a dual mass flywheel. The internal combustion engine constitutes a primary drive in the CVT drive train 10.

(6) The drive shaft 12 may be coupled to a gearbox input shaft 18 via a starting device 16 configured as a multiplate clutch. The CVT drive train 10 has, as a secondary drive, an electric motor 20 which is also known as an electric machine 20. The electric motor 20 comprises a stator 22 having an electromagnet, and a rotor 24 cooperating with the stator 22 and equipped with permanent magnets.

(7) A rotor carrier 26 carries the permanent magnets of the rotor 24 and, in the exemplary embodiment shown, is formed from multiple pieces. Radially inwardly, the rotor carrier 26 is fixedly connected to the gearbox input shaft 18.

(8) The rotation speed and torque of the gearbox input shaft 18 may be converted in a variator 30. A variator drive shaft 32 is to this end connected rotationally fixedly to the gearbox input shaft 18. The variator drive shaft 32 drives a drive-side disc set 34 which is configured as a conical drive disc pair.

(9) The drive-side disc set 34 is coupled via traction means 36 (e.g., a CVT chain) to an output-side disc set 38 which is configured as a conical output disc pair. Depending on the position of the conical drive disc pair 34 and the conical output disc pair 38, the translation ratio of the variator 30 can be varied continuously. The conical output disc pair 38 drives a variator output shaft 40 which may have a modified rotation speed and modified torque in comparison with the gearbox input shaft 18.

(10) A variator output gear 42 is mounted on the variator output shaft 40. The variator output gear 42 can be coupled rotationally fixedly to the variator output shaft 40 by means of a variator clutch 44. The variator output gear 42 is coupled via a connecting gear 46 to a differential gear mechanism 48, known in brief as a differential 48. The differential gear mechanism 48 comprises output shafts 50 leading to drive wheels (not shown).

(11) The drive-side disc set 34 and the variator drive shaft 32 are arranged coaxially to the drive shaft 12 with the rotation axis 13. The output-side disc set 38 and the variator output gear 42 are rotatable about a rotation axis 39 which is arranged parallel to the rotation axis 13. The connecting gear 46 with an intermediate shaft 47 is rotatable about a rotation axis 45 which is arranged parallel to the rotation axes 13 and 39. The output shaft 50 of the differential 48, and the differential output gear 49, are rotatable about a rotation axis 51 which is arranged parallel to the rotation axes 13, 39 and 45.

(12) FIG. 1 shows a portion of differential output gear 49 in dotted lines depicting differential output gear 49 directly adjacent to output side fixed disc 65 as would be shown in another cross-sectional views not visible in the open longitudinal sectional depiction of FIG. 1. FIG. 2 shows the actual axial positions of the rotation axes 13, 39, 45 and 51 as they are really arranged. A comparison of FIGS. 1 and 2 shows that no further component is arranged between the relatively large differential output gear 49 and the output-side fixed disc 65 of the output-side disc set 38.

(13) FIG. 1 shows that the end of the gearbox input shaft 18 facing away from the drive shaft 12 is connected rotationally fixedly to the variator drive shaft 32 by means of a push-fit connection configured as a push-fit toothing 52. The push-fit connection comprises, in addition to the push-fit toothing 52, a centering seat and/or press fit 53 between the gearbox input shaft 18 and the variator drive shaft 32.

(14) The electric motor 20 is accommodated in a motor housing 60. The variator is accommodated in a variator housing 62. The variator housing 62 and the motor housing 60 are assembled into a common housing for the drive train 10.

(15) The drive-side disc pair 34 comprises a fixed disc 64 and an adjustable disc 67. The output-side disc pair 38 comprises a fixed disc 65 and the adjustable disc 68. A return spring 70 is assigned to the adjustable disc 68.

(16) The drive-side disc set 34 is mounted via a drive bearing 71 in the variator housing 62. By means of a drive bearing 72, also known as a main bearing, the primary-side disc set 34 is mounted in the motor housing 60.

(17) The output-side disc set 38 is mounted in the variator housing 62 via an output bearing 73, also known as a main bearing. The motor-side shaft end of the variator output shaft 40 is mounted in the motor housing 60 via an output bearing 74.

(18) The intermediate shaft 47 is mounted in the motor housing 60 by means of an intermediate shaft bearing 82. The intermediate shaft bearing 82 comprises a bearing plate 84 from which a bearing journal 85 protrudes. The bearing plate 84 and the bearing journal 85 are formed integrally from a steel material. The bearing plate 84 is attached to the motor housing 60 via bolts 86, 87. The intermediate shaft 47, at its left end in FIG. 1, has a ring body 88. The ring body 88 is integrally connected to the intermediate shaft 47 and surrounds the bearing journal 85 with the interposition of roller bodies 89.

(19) According to a further exemplary embodiment (not shown), an additional clutch may be arranged in a free space 90 radially inside the electric machine 20, to replace the variator output clutch 44. The additional clutch, like the variator output clutch 44, serves to separate a force transfer connection to a driven wheel, in order to charge a vehicle battery via the electric motor 20 using the internal combustion engine when the vehicle is stationary.

(20) The rotor 24 of the electric motor 20 rests via the rotor carrier 26 directly on the variator drive shaft 32 without a further intermediate mounting by means of the push-fit connection described above. The associated bearing forces are transmitted from the rotor carrier 26 to the drive bearing 72—also known as a main bearing—by the centering seat and/or press fit 53 of the gearbox input shaft 18.

(21) FIG. 3 shows in enlargement an extract from FIG. 1 according to a further exemplary embodiment. In the exemplary embodiment shown in FIG. 3, a planetary gear set 100 is arranged in the free space (90 in FIG. 1) and serves to create a mechanical reverse gear. The planetary gear set 100 comprises a sun gear 101 which is connected rotationally fixedly to the drive shaft 12. A ring gear 102 is connected rotationally fixedly to an inner plate carrier 107 of a braking device 106 configured as a multiplate clutch. Planet gears 103, which intermesh with both the sun gear 101 and the ring gear 102, are arranged between the sun gear 101 and the ring gear 102. The planet gears 103 are arranged rotatably on a planet carrier 105. The planet carrier 105 is connected rotationally fixedly to the rotor carrier 26. Radially inwardly, the planet carrier 105 is fixedly connected to the gearbox input shaft 18.

(22) The braking device 106, configured as a multiplate clutch, comprises—in addition to the inner plate carrier 107—an outer plate carrier 108 which is connected rotationally fixedly to the motor housing 60. A hydraulic actuation device 109 for actuating the braking device 106, configured as a multiplate clutch, is arranged axially adjacent to the rotor 24 of the electric motor 20 and radially outside a wall, which delimits a compression chamber, of the drive-side adjustable disc.

(23) A device 110, known as a resolver, for detecting a circumferential position and/or a rotation speed is arranged radially inside the electric motor 20, between the starting device 16 and the braking device 106 for the planetary gear set 100. The resolver 110 comprises a first function part 111 and a second function part 112. The first function part 111 is arranged radially inside the second function part 112 and is also known as an inner function part 111. Similarly, the second function part 112 is also known as an outer function part 112. The radially inner function part 111 is connected rotationally fixedly to the rotor carrier 26. The radially outer function part 112 comprises windings for example, and is connected rotationally fixedly to the motor housing 60. In the radial direction, the device 110 is arranged between the planetary gear set 100 and the motor 24 of the electric machine 20.

REFERENCE SYMBOLS

(24) 10 Drive train

(25) 12 Drive shaft

(26) 13 Rotation axis

(27) 14 Torsional vibration damper

(28) 16 Starting device

(29) 18 Gearbox input shaft

(30) 20 Electric motor

(31) 22 Stator

(32) 24 Rotor

(33) 26 Rotor carrier

(34) 30 Variator

(35) 32 Variator drive shaft

(36) 34 Drive disc pair

(37) 36 Traction means

(38) 38 Output disc pair

(39) 39 Rotation axis

(40) 40 Variator output shaft

(41) 42 Variator output gear

(42) 44 Variator clutch

(43) 45 Rotation axis

(44) 46 Connecting gear

(45) 47 Intermediate shaft

(46) 48 Differential

(47) 49 Differential output gear

(48) 50 Output shaft

(49) 51 Rotation axis

(50) 52 Push-fit toothing

(51) 53 Centering seat

(52) 60 Motor housing

(53) 62 Variator housing

(54) 64 Fixed disc

(55) 65 Fixed disc

(56) 67 Adjustable disc

(57) 68 Adjustable disc

(58) 70 Return spring

(59) 71 Drive bearing

(60) 72 Drive bearing

(61) 73 Output bearing

(62) 74 Output bearing

(63) 82 Intermediate shaft bearing

(64) 84 Bearing plate

(65) 85 Bearing journal

(66) 86 Bolt

(67) 87 Bolt

(68) 88 Ring body

(69) 89 Roller bearing

(70) 90 Free space

(71) 100 Planetary gear set

(72) 101 Sun gear

(73) 102 Ring gear

(74) 103 Planet gears

(75) 105 Planet carrier

(76) 106 Braking device

(77) 107 Inner plate carrier

(78) 108 Outer plate carrier

(79) 109 Hydraulic actuating device

(80) 110 Resolver

(81) 111 First function part

(82) 112 Second function part