TORQUE TRANSMISSION DEVICE FOR A MOTOR VEHICLE

Abstract

A torque transmission device for a motor vehicle includes at least one motor, a first output shaft rotationally coupled to an output element of a first clutch and to an output element of a second clutch, the first output shaft to drive a first wheel of the vehicle, a second output shaft rotationally coupled to an output element of a third clutch and to an output element of a fourth clutch, the second output shaft to drive a second wheel of the vehicle, opposite the first wheel, a torque transfer mechanism to transmit the torque from the motor to an input element of the first clutch and to an input element of the fourth clutch with a first gear ratio, and to transmit the torque from the motor to an input element of the second clutch and to an input element of the third clutch with a second gear ratio.

Claims

1. A torque transmission device for a vehicle comprising at least one motor, the torque transmission device comprising: a first output shaft rotationally coupled to an output element of a first clutch and to an output element of a second clutch, the first output shaft being intended to drive a first wheel of the vehicle, a second output shaft rotationally coupled to an output element of a third clutch and to an output element of a fourth clutch, the second output shaft being intended to drive a second wheel of the vehicle, opposite the first wheel, a torque transfer mechanism designed to transmit the torque from the motor to an input element of the first clutch and to an input element of the fourth clutch with a first gear ratio, and to transmit the torque from said at least one motor to an input element of the second clutch and to an input element of the third clutch with a second gear ratio.

2. The device as claimed in claim 1, further comprising: control means for controlling the slip of the first clutch and of the fourth clutch, and/or, of the second clutch and of the third clutch, said control means being able to control the torque split between the first and second wheels of the vehicle, through slippage of the corresponding clutches.

3. The device as claimed in claim 1, wherein the first clutch and the second clutch are concentric with the first output shaft, the third clutch and the fourth clutch being concentric with the second output shaft, the clutches being offset axially relative to one another.

4. The device as claimed in claim 1, wherein each clutch is operated via a source of hydraulic pressure and hydraulic directional control valves controlled by a control unit.

5. The device as claimed in claim 1, wherein each clutch is actuated by a rotary hydraulic receiver.

6. The device as claimed in claim 1, wherein the input element of each clutch is rotationally driven by a gear wheel concentric with the clutch and driven by a pinion of which the axis is parallel to the gear wheel.

7. The device as claimed in claim 6, wherein the axes of said pinions are concentric.

8. The device as claimed in claim 1, wherein the second clutch and the third clutch comprise a common input member rotationally driven by a gear wheel common to the second clutch and to the third clutch.

9. The device as claimed in claim 1, wherein the first clutch and the fourth clutch each comprise a respective input element driven by a respective gear wheel.

10. The device as claimed in claim 9, wherein the gear wheels associated with the first clutch and with the fourth clutch and/or the gear wheels associated with the second clutch and with the third clutch have opposite helix angles.

11. The device as claimed in claim 1, comprising a locking device for locking the first and second wheels, wherein each clutch is of the normally open type, each wheel locking device comprises a gear wheel rotationally coupled to the corresponding output shaft, each gear wheel being associated with a locking lever that is controlled and able to move between a locking position in which it engages in the toothset of the corresponding gear wheel so as to prevent the corresponding output shaft from rotating, and a released position in which it is disengaged from the toothset of the gear wheel so as to allow the output shaft to rotate.

12. The device as claimed in claim 1, wherein the gear ratio of the input elements of the first clutch and of the fourth clutch is lower than the gear ratio of the input elements of the second clutch and of the third clutch; and the output elements of the second clutch and of the third clutch being positioned axially between the output elements of the first clutch and of the fourth clutch.

13. The device as claimed in claim 1, wherein the transmission device comprises at least one fluid supply duct and at least one of the output elements of the clutches comprises a tubular body and said at least one duct passes inside the tubular body.

14. A torque transmission module for a torque transmission device as claimed in claim 1, the module comprising: a first output shaft rotationally coupled to an output element of a first clutch and to an output element of a second clutch, the first output shaft being intended to drive a first wheel of the vehicle, a second output shaft rotationally coupled to an output element of a third clutch and to an output element of a fourth clutch, the second output shaft being intended to drive a second wheel of the vehicle, opposite the first wheel, an input element of the first clutch and an input element of the fourth clutch which are configured to transmit a torque in a first operating range, an input element of the second clutch and an input element of the third clutch which are configured to transmit a torque in a second operating range, the second operating range corresponding to conditions at higher speeds.

15. A torque transmission system for a vehicle comprising an electric motor and a torque transmission device as claimed in claim 1, the transmission mechanism being designed to be driven by the motor.

16. The device as claimed in claim 2, wherein the first clutch and the second clutch are concentric with the first output shaft, the third clutch and the fourth clutch being concentric with the second output shaft, the clutches being offset axially relative to one another.

17. The device as claimed in claim 2, wherein each clutch is operated via a source of hydraulic pressure and hydraulic directional control valves controlled by a control unit.

18. The device as claimed in claim 2, wherein each clutch is actuated by a rotary hydraulic receiver.

19. The device as claimed in claim 2, wherein the input element of each clutch is rotationally driven by a gear wheel concentric with the clutch and driven by a pinion of which the axis is parallel to the gear wheel.

20. The device as claimed in claim 2, wherein the second clutch and the third clutch comprise a common input member rotationally driven by a gear wheel common to the second clutch and to the third clutch.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0116] FIG. 1 is a perspective view of a torque transmission device according to one embodiment of the invention,

[0117] FIG. 2 is a side view of the device,

[0118] FIG. 3 is a view in section of the device,

[0119] FIG. 4 is a schematic view in section of the device according to another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0120] FIGS. 1 to 3 depict a torque transmission system 1 for a hybrid or fully electric motor vehicle. The transmission system comprises a motor 2 and a transmission device 1 designed to transmit torque between the motor and the wheels of the vehicle.

[0121] The transmission device comprises a first output shaft 14 intended to drive a first wheel of the vehicle, and a second output shaft 17 intended to drive a second wheel of the vehicle, opposite to the first wheel.

[0122] The electric motor 2 comprises a stator, and a rotor coupled to a rotary shaft 3 of the motor 2. The rotary shaft 3 of the motor 2, of axis X3, is guided in rotation via ball bearings 4. The shaft 3 drives a transmission mechanism comprising a gear wheel R1 borne by the shaft 3. The transmission mechanism further comprises a first rotary shaft 5, of axis X5, guided in rotation by ball bearings 6. The first rotary shaft 5 bears a gear wheel R2 and a gear wheel R3. The gear wheel R2 meshes with the gear wheel R1. The diameter of the gear wheel R3 is less than the diameter of the gear wheel R2. The gear wheel R3 is situated to the right of the gear wheel R2 in FIG. 3, namely on the opposite side to the electric motor 2.

[0123] The transmission mechanism further comprises a second rotary shaft 7, of axis X7, guided in rotation by ball and/or roller bearings 8. The bearings 4, 6, 8 are supported by a fixed casing, not depicted.

[0124] The second shaft 7 bears a gear wheel R4 meshing with the gearwheel R3, two pinions R5 and R6 associated with a first gear ratio and a pinion R7 associated with a second gear ratio.

[0125] The pinions R5, R6 and R7 have teeth. The diameter of the gear wheel R4 is greater than the diameter of the gear wheel R3.

[0126] The pinion R7 is situated axially, namely along the axis of the second shaft 7, between the pinion R5, situated to the left in FIG. 3, and the pinion R6, situated to the right in that same figure. The gear wheel R4 is situated to the right of the pinion R6.

[0127] The axes X3, X5 and X7 of the shafts 3, 5, 7 are mutually parallel. The gear wheels and pinions R1 to R7 have helical teeth.

[0128] The pinion R5 and the pinion R6 mesh respectively with a ring gear or a gear wheel R8 and with a ring gear or a gear wheel R9.

[0129] The pinions R5 and R6 have opposite helix angles. Likewise, the ring gears R8 and R9 have opposite helix angles.

[0130] The ring gear R8 is borne by an annular input element 9 of a clutch E1.

[0131] The ring gear R9 is borne by an annular input element 10 of a clutch E4.

[0132] The pinion R7 meshes with a ring gear or with a gear wheel R10 borne by an annular input element 11, and common to a clutch E2 and to a clutch E3.

[0133] The toothsets of the ring gears R8, R9, R10 are helical. The ring gears are also coaxial, their axis X being parallel to the axes X3, X5 and X7. Their axis X is also coaxial with the output shafts 16, 17.

[0134] The clutches E1 and E2 respectively comprise output elements 12, 13 rotationally coupled to the output shaft 14 of axis X.

[0135] The clutches E3 and E4 respectively comprise output elements 15, 16 rotationally coupled to the output shaft 17 of axis X.

[0136] Each clutch E1 to E4 further comprises a first series of disks 18 which are rotationally coupled to the input element and a second series of disks 19 which are rotationally coupled to the output element, the disks 19 being interleaved between the disks 18. The disks 18, 19 are caused to be pressed against one another by an annular piston 20 actuated by a hydraulic fluid opening into a pressure chamber 21 of the corresponding input element 9, 10, 11, in which element the piston 20 is mounted.

[0137] The movement of each piston 20 is controlled by control means. It will be noted that, in this embodiment, the pistons 20 are able to rotate with the input elements 9, 10, 11.

[0138] The input elements 9, 10, 11 of the clutches E1 to E4 are guided in rotation by roller bearings 22.

[0139] Each output shaft 14, 17 comprises a first end 23 coupled in rotation to a wheel of the vehicle, via a constant-velocity joint such as a Cardan joint for example, and a second end 24 opposite to the first end 23.

[0140] The output shafts 14, 17 are coaxial with one another, with the input elements 9, 10, 11 and output elements 12 to 16 of the clutches E1 to E4, and with the ring gears R8, R9 and R10.

[0141] Each output shaft 14, 17 comprises a first cylindrical part 25 having a first diameter, situated on the first-end 23 side, and a second cylindrical part 26 having a second diameter, situated on the second-end 24 side, the first diameter being greater than the second diameter. Each output shaft 14, 17 is thus a stepped shaft.

[0142] The output elements 12, 16 of the clutches E1 and E4 are situated near the first end 23 of each output shaft 14, 17. The output elements 13, 15 of the clutches E2 and E3 are situated near the second end 24 of each output shaft 14, 17.

[0143] The ratio of the rotational speed of the input elements 9, 10 of each of the clutches E1 and E4 to the rotational speed of the shaft 3 of the motor 2, referred to as the first gear ratio, is, for example, comprised between 1/20 and 1/10 when the clutches E1 and E4 are in the engaged position, namely when a torque can be transmitted to the output shafts 14, 17 through said clutches E1 and E4.

[0144] The ratio of the rotational speed of the input element 11 of the clutches E2 and E3 to the rotational speed of the shaft 3 of the motor 2, referred to as the second gear ratio, is, for example, comprised between 1/10 and 1/5 when the clutches E2 and E3 are in the engaged position, namely when a torque can be transmitted to the output shafts 14, 17 through said clutches E2 and E3.

[0145] In general, the first gear ratio is lower than the second gear ratio. The clutches dedicated to the first gear ratio are closer to the wheels than the clutches dedicated to the second gear ratio.

[0146] The clutches are of the normally open type in the embodiment depicted in the figures.

[0147] Each output shaft 14, 17 is equipped with a system for locking the corresponding wheel, intended to allow the vehicle to be immobilized. Each locking system comprises a gear wheel 27 rotationally coupled to the corresponding output shaft 14, 17, each gear wheel 27 being associated with a locking lever that is controlled and able to move between a locking position in which it engages in the toothset of the corresponding gear wheel 27 so as to prevent the corresponding output shaft 14, 17 from rotating, and a released position in which it is disengaged from the toothset of the gear wheel 27 so as to allow the corresponding output shaft 14, 17 to rotate.

[0148] In operation, the clutches E1 to E4 are actuated according to the gear ratio selected. In other words, if the first gear ratio is to be used, the clutches E1 and E4 are actuated so as to move into the engaged or closed position, while the clutches E2 and E3 are not actuated, so that they are moved into the disengaged or open position. The torque is thus transmitted from the motor 2 to each of the output shafts 14, 17 notably via the clutches E1 and E4.

[0149] Each clutch is of the multidisk type and the input elements form radially outer disk carriers of the clutches, and the output elements form the radially inner disk carriers of the clutches. The radial dimension is considered with respect to the axes of the output shafts.

[0150] Conversely, if the second gear ratio is to be used, the clutches E2 and E3 are actuated so as to move into the engaged or closed position, while the clutches E1 and E4 are not actuated, so that they are moved into the disengaged or open position. The torque is thus transmitted from the motor 1 to each of the output shafts 14, 17 notably via the clutches E2 and E3.

[0151] Furthermore, the torque vectoring function may be obtained by controlling the torque is applied to each wheel and for each speed by regulating, as required, the slipping of each clutch E1 to E4 concerned. Regulation can be achieved by calculating the torque transmitted to each wheel, for example from information regarding the speed of the output shafts 14, 17 and regarding the pressure in the clutches. To do that, each output shaft 14, 17 may be equipped with a sensor, not depicted, able to detect the rotational speed thereof.

[0152] Another embodiment is illustrated in FIG. 4. This embodiment differs from the preceding one notably in terms of the features set out hereinbelow.

[0153] The shaft 3 may be formed as one piece with the gear wheel R1. Likewise, the shaft 5 can be formed as one piece with the gear wheel R3.

[0154] The second shaft of the transmission mechanism is made up of two coaxial sections 7a and 7b coupled to one another. For example, a portion of the end of the section 7a is centered in a portion of the end of the section 7b, and another portion of the end of the section 7a is engaged with splines in another portion of the end of the section 7b. One of the sections 7a is associated with the first clutch E1 and with the second clutch E2, and the other section 7b is associated with the third clutch E3 and with the fourth clutch E4.

[0155] The pinions R5, R6, R7 and R11 may also be formed as one piece with the corresponding section 7a, 7b of shaft.

[0156] The clutches each comprise a respective input element 9, 11, 31, 10 driven by a respective gear wheel. Each section 7a, 7b therefore bears, unable to rotate independently of it, two pinions which each mesh with a gear wheel.

[0157] The input elements 9, 11, 31, 10 form radially inner disk carriers of the clutches and the output elements 12 and 16 form the radially outer disk carriers of the clutches.

[0158] The first clutch E1 and the second clutch E2 share a common output element 12. Likewise, the third clutch E3 and the fourth clutch E4 share a common output element 16. The output elements 12 and 16 comprise a body of tubular cross section extending axially in the continuation of the first and second output shafts.

[0159] A space axially separates the common output element 12 of the first and second clutches and the common output element 16 of the third and fourth clutches. It is thus possible to use this space to run through it at least one duct 40 that supplies the clutches with fluid. FIG. 4 schematically indicates just one duct for supplying the second clutch E2. Of course, each clutch may be supplied with fluid in the way schematically indicated in respect of the second clutch E2.

[0160] Because the output elements 12 and 16 of the clutches have a body that is tubular, each duct 40 can pass inside the tubular body of the output element of the clutch it is to supply. This output element 12, 16 further comprises a drilling that causes the inside of the tubular body and the outside of the tubular body to communicate, at the level of an actuating chamber of the clutch that is to be supplied. The duct can therefore communicate with the drilling or enter this drilling.

[0161] Each output element 12, 16 comprises a connecting disk respectively connecting: [0162] a portion of the output element forming the radially outer disk carrier of a clutch, [0163] a portion of the output element forming the radially outer disk carrier of another clutch, the disk being arranged axially between these two disk carriers, [0164] the tubular body of said output element positioned radially on the inside of these disk carriers.

[0165] The input elements of the clutches are mounted with the ability to pivot about the corresponding output elements of the clutches, notably the tubular body thereof.

[0166] So far as the first clutch and the second clutch are concerned, the first wet clutch E1 comprising a first radially outer disk carrier, a first radially inner disk carrier and a first multidisk assembly with at least one friction disk rotationally coupled with the first radially outer disk carrier, and at least one other disk rotationally coupled with the first radially inner disk carrier. The second wet clutch E2 comprising a second radially outer disk carrier, a second radially inner disk carrier and a second multidisk assembly with at least one friction disk rotationally coupled with the second radially outer disk carrier, and at least one other disk rotationally coupled with the second radially inner disk carrier.

[0167] The transmission gear wheel R8 is rotationally coupled with the first radially inner disk carrier and the transmission gear wheel R10 is rotationally coupled with the second radially inner disk carrier.

[0168] The first radially outer disk carrier and the second radially outer disk carrier as well as the tubular body connected rigidly in terms of rotation to the first radially outer disk carrier and to the second radially outer disk carrier together form a transmission member which in this instance is an output element 12. The tubular body extends along the axis X.

[0169] The first radially inner disk carrier and the second radially inner disk carrier are rotationally coupled with the torque transmission mechanism via the two wheels R8 and R10 respectively. The two wheels R8 and R10 have different diameters. The pinions R5 and R7 meshing with the gear wheels R8 and R10 also have different diameters.

[0170] The first clutch E1 has a first actuating piston and the second clutch E2 has a second actuating piston (not depicted), the first piston and the second piston being arranged axially between the multidisk assembly of the first clutch and the multidisk assembly of the second clutch. The first piston moves axially away from the second clutch in order to compress the multidisk assembly of the first clutch, and the second piston moves axially away from the first clutch in order to compress the multidisk assembly of the second clutch.

[0171] It may be seen that the first and second clutches are arranged symmetrically with respect to a plane extending radially between the first piston and the second piston.

[0172] The first radially inner disk carrier is mounted with the ability to rotate on the tubular body via a first rolling bearing. The second radially inner disk carrier is mounted with the ability to rotate on the tubular body via a second rolling bearing.

[0173] The transmission member comprises a connecting portion which extends radially and which connects the first radially outer disk carrier and the second radially outer disk carrier to the tubular body.

[0174] A first actuating chamber is formed between the first piston and the connecting portion, and a second actuating chamber is formed between the second piston and the connecting portion.