DE102005059832B4 - System for torque distribution - Google Patents

Abstract

Multi-plate clutch (54) having: a clutch basket (90) which rotates about a first axis (A, B) and is connected to a first set of plates (94); and a clutch hub (92) which rotates about a second axis (A, B) and is connected to a second set of disks (96), the disks of the second set of disks (96) and the disks of the first set of disks (94) meshing with one another ; wherein the lamellae of the lamellae sets (94, 96) can be pressed against one another in order to transmit a torque, characterized in that the first axis (A, B) and the second axis (A, B) are fixed and offset from one another.

Description

The present invention relates to a multi-plate clutch.

Modern drive trains (eg, four-wheel drive trains) are known as "active-yaw" or "torque vectoring" (TV) systems. With a TV system, the yaw rate of the vehicle is actively controlled, the drive torque can be unevenly distributed to the wheels. As a result, more drive torque can be directed to the outside wheel, for example, so that an oversteering behavior can be set under normal driving conditions.

Conventional differential units include a differential or differential that compensates for speed differences. The differential can not increase existing speed differences alone. In particular, the differential unit requires additional components to increase the speed differential (i.e., transmit more drive torque to a particular wheel).

The publication GB 426 407 A discloses a friction clutch for on-demand coupling of a drive shaft to an output shaft. The clutch comprises intermeshing sets of disks, wherein the disks of the one set are annular and rotationally fixedly connected to the output shaft, while the blades of the other set are freely rotatably mounted on eccentrically mounted on a drive element pin and rotate along the circumference of the annular disks.

In the DE 1 425 216 B is also disclosed a friction clutch. When engaging the clutch, a disc which is rotatably mounted on a crank portion of the output shaft, pressed against a rotatably connected to the drive shaft pressure plate.

The invention has for its object to provide a multi-plate clutch, which is used in a TV system to form a simplified TV system.

The solution of this object is achieved by a multi-plate clutch with the features of claim 1, and in particular in that a first axis and a second axis of the components of the multi-plate clutch are stationary and offset from one another.

The multi-plate clutch according to the invention has a clutch basket and a clutch hub. The clutch basket rotates about a first axis and is connected to a first set of blades. The clutch hub rotates about a second axis and is connected to a second set of blades, wherein the blades of the disk sets interlock. The fins of the plate sets are pressed against each other for transmitting a moment to transmit a force between the fins of the plate sets having a tangential component at the mutual contact points and additionally a radial component when the plate sets are pressed against each other. As a result, the tangential components cause the torque transmission, while additionally in the contact point, a radial force arises, which ultimately results from the fact that the first axis and the second axis are offset from each other. By targeted mutual pressing of the disk sets allows such a coupling in a TV system actively influencing the torque transfer.

Advantageous embodiments of the invention are described in the description, the drawings and the subclaims.

In a first preferred embodiment of the multi-plate clutch, a first shaft is non-rotatably connected to the clutch basket, and a second shaft is rotationally coupled to the clutch hub. A ring gear is rotatably connected to the clutch hub and rotates about the second axis. A gear is rotatably connected to the second shaft and rotates about the first axis, wherein the ring gear and the gear mesh.

In a second preferred embodiment of the multi-plate clutch, a first shaft is rotatably coupled to the clutch basket, and a second shaft is rotatably connected to the clutch hub. A ring gear is rotatably connected to the clutch basket and rotates about the first axis. A gear is rotatably connected to the first shaft and rotates about the second axis, wherein the ring gear and the gear mesh.

A differential unit is provided which, for use in a TV system, comprises at least one multi-plate clutch according to the invention and a corresponding actuator. The actuator generates a contact force on the disk sets of the multi-plate clutch to enable the TV operation.

Further, according to the invention, a drive train is provided, which has a differential unit which comprises at least one multi-disc clutch according to the invention and a corresponding actuator. The actuator generates a contact force on the disk sets of the multi-plate clutch to allow the TV operation. The powertrain further includes a control unit that is electronically connected to at least one sensor and preferably a plurality of sensors, at least to detect an operating condition of the vehicle. The control unit generates control signals based on the operating state of the vehicle to adjust the actuator while controlling the pressing force and the transmitted driving torque.

Finally, the invention also relates to the use of a multi-plate clutch or a differential unit of the type described for the active control of torque transfer to various wheels of a motor vehicle, but the invention is not limited to such use.

The invention will now be described by way of example only with reference to the drawings; in these shows:

1 a schematic representation of a motor vehicle powertrain, which is equipped with a differential unit constructed in accordance with the present invention;

2 a schematic sectional view of the differential unit comprising multi-plate clutches according to an embodiment of the invention;

3 a schematic partial sectional view of the differential unit comprising multi-plate clutches according to another embodiment of the invention;

4 a vector diagram illustrating the force vectors around a friction diameter between the disks of the multi-plate clutch; and

5 a diagram showing the drive torque on the speed ratio of the clutch basket and clutch hub.

In 1 is a schematic representation of a vehicle drive train 10 shown a drive 12 comprising which a power transmission line 16 , a motor 18 and a gearbox 20 includes. The power transmission line 16 includes a propeller shaft 28 passing through the gear 20 is driven, and a pair of axle shafts 30 that with a pair of wheels 32 connected, as well as a differential unit 34 that is effective to drive torque from the cardan shaft 28 to one or both axle shaft (s) 30 transferred to.

A tax unit 40 controls the operation of the differential unit 34 based on a variety of vehicle parameters to enable a so-called "torque vectoring" (TV operation). The tax unit 40 is electronically connected to at least one sensor and preferably a plurality of sensors. Exemplary sensors include a yaw rate sensor 42 , Wheel speed sensors 44 , a steering wheel angle sensor (not shown) and / or a steering angle sensor 46 , Other sensors include side and longitudinal acceleration sensors (not shown). The sensors detect a variety of operating conditions, eg. As the yaw rate of the vehicle, the speed of each wheel 22 . 32 , the steering wheel angle and / or the steering angle (α) of the front wheels 22 , The tax unit 40 processes the signal or signals and generates a differential control signal, wherein at least one actuator is driven based on the differential control signal to drive more torque to the corresponding wheel 32 transferred to.

With reference to 2 now become the components of the differential unit 34 described. The differential unit 34 includes a differential case 50 that is a differential 52 , two multi-plate clutches 54 and two corresponding actuators 56 . 58 includes. A drive shaft 60 , which are non-rotatable with the cardan shaft 28 is connected, is in the differential case 50 through bearing arrangements 62 rotatably supported and by a sealing arrangement, not shown, relative to the differential housing 50 sealed. Two output shafts 64 , the rotation with the axle shafts 30 are connected in the differential case 50 rotatably supported by bearing assemblies and by not shown sealing arrangements relative to the differential housing 50 sealed. The output shafts 64 rotate about an axis A. A drive bevel gear 70 is at one end of the drive shaft 60 educated.

The differential 52 is in the differential case 50 through bearing arrangements 72 rotatably mounted and includes a carrier drum 74 , two bevel gear sets (bevel gears 76A . 76B ; 78A . 78B ), and a crown wheel 80 that is attached to the carrier drum 74 is attached and with the drive bevel gear 70 engaged, so that a driven rotation of the propeller shaft 28 a rotation of the differential gear 52 causes. The bevel gears 76A . 76B are with a corresponding output shaft 64 rotatably connected. At the differential 52 the drive is via the carrier drum 74 on the opposite bevel gears 76A . 76B ; 78A . 78B , When driving straight ahead, the bevel gears turn 76A . 76B ; 78A . 78B not relative to each other. The entire differential 52 runs as a block and transmits the torque evenly to the two output shafts 64 , Only at speed differences (eg when cornering) between the two output shafts 64 the two bevel gears turn 76A . 76B opposite in the carrier drum 74 in order to distribute the torque basically evenly on both output shafts 64 to distribute.

As will be explained in more detail below, by actuating at least one of the multi-plate clutches 54 according to the invention additional torque on one of the two output shafts 64 be transferred to the drive torque uneven on the wheels 32 to distribute. This will be on the carrier drum 74 and the respective multi-plate clutch 54 (with clutch basket 90 and clutch hub 92 ) A drive torque targeted to the actual differential gear 52 (Bevel gears 76A . 76B ) over to the respective output shaft 64 transfer. Of course, the mentioned differential gear 52 also be replaced by another differential (eg a planetary differential).

The multi-plate clutches 54 comprise a respective clutch basket 90 and a respective clutch hub 92 , The clutch basket 90 turns around the axis A and is with a first set of blades 94 connected. The clutch hub 92 rotates about an axis B and is with a second set of blades 96 connected, wherein the fins of the second plate set 96 and the fins of the first plate set 94 mesh. The axis A and the axis B are offset by an axial distance .DELTA.x to each other, wherein the fins of the plate sets 94 . 96 for transmission of a torque in particular so as to be pressed against each other, that between the slats of the plate sets 94 . 96 a force is transmitted which has a tangential component and a radial component when the plate sets 94 . 96 pressed against each other.

In a first embodiment ( 2 ) are the clutch baskets 90 through corresponding hollow shafts 98 rotatably with the carrier drum 74 connected. The hollow shafts 58 are coaxial with the output shafts 64 arranged. The output shafts 64 are as follows with the clutch hubs 92 rotationally coupled: A respective ring gear 100 is non-rotatable with the associated clutch hub 92 connected and rotates about the axis B. A respective gear 102 is non-rotatable with the associated output shaft 64 connected and rotates about the axis A, wherein the ring gear 100 and the gear 102 comb to form a rotation ratio.

In an otherwise similar acting second embodiment ( 3 ) the clutch baskets rotate 90 about the axis B and the clutch hubs 92 about the axis A. The clutch baskets 90 are rotationally effective with corresponding hollow shafts 98 ' coupled and the clutch hubs 92 are non-rotatable with the output shafts 64 connected. A respective ring gear 100 ' is non-rotatable with the associated clutch basket 90 connected and rotates about the axis B. A respective gear 102 ' is about the respective hollow shaft 98 ' rotatably with the carrier drum 74 of the differential gear 52 connected and rotates about the axis A, wherein the ring gear 100 ' and the gear 102 ' comb to form a rotation ratio.

In the two embodiments mentioned, the actuators 56 . 58 For example, hydraulic pistons include. The pistons generate corresponding contact forces to the slats of the plate sets 94 . 96 to press against each other and thereby in addition to the power transmission through the carrier drum 74 and the bevel gears 76A . 76B ; 78A . 78B a power transmission directly over the carrier drum 74 and the multi-plate clutches 54 to the output shafts 64 to reach. As mentioned above, the actuators 56 . 58 based on the control signals from the control unit 40 controllable to enable TV operation.

In an exemplary embodiment, the lamellae can be pressed against one another with a contact pressure that is along the respective circumference of the lamination sets 94 . 96 can be distributed unequally. In particular, it is dispensed with actuator rings, which are arranged in known multi-plate clutches between the actuator and the relevant plate set and ensure a substantially uniform force transmission along the circumference. For example, it is provided that the contact force in a first angle segment WS _{1 of} the respective set of slats (left half of 4 ) is higher than in a second angle segment WS _{2 of} the respective plate set (right half of 4 ), wherein in the example shown here, the mutual overlap of the plate sets 94 . 96 is greater in the first angle segment WS ₁ than in the second angle segment WS. ₂

As 4 shows, resulting in a multi-disc clutch assembly additional shares in the radial direction, depending on the size of the axial offset and the speed ratio of input and output speed. In 4 is a pair of lamellae of the lamella sets 94 . 96 shown with a center distance Δx. The lamella A of the lamella set 94 is the drive plate and turns slightly faster than the plate B of the plate set 96 which is to be driven. In 4 Dotted is a friction circle with the friction diameter d _REIB on the _blade B, which is about the axis B (see. 2 ) turns. The lamella A rotates about the axis A (see. 2 ).

By vectorial subtraction of the respective velocity vectors of the slats A and B at different points of contact along said friction circle, the vector of the velocity difference can be determined. This speed difference vector (v-difference) comprises a tangential component and a radial component, wherein only the tangential component yields a drive torque at the fin B. The direction and the length of the speed difference vector vary along the friction track. In the first angle segment WS ₁ (left side according to FIG 4 ), the speed difference vector is the longest and in the second angle segment WS ₂ (right side) the shortest. For the transmission of the drive torque, only the direction of the speed difference vector, but not its length is important. In general, the contact pressure in such an angular segment WS _{1 of} the respective scope of the plate sets 94 . 96 higher than the contact force in another angle segment WS ₂ , in which the speed difference vector of the two sets of plates 94 . 96 pointing in the direction in which a moment between the two sets of plates 94 . 96 to be transferred. This is especially true at a differential speed of the disk sets 94 . 96 from zero or approximately zero.

In fact, if the differential speed between the clutch basket speed and the clutch speed becomes almost zero, all the speed difference vectors will point in the same direction. According to the right side 4 (ie in the second angle segment WS ₂ ) the output plate is then braked and on the left side (ie in the first angle segment WS ₁ ), the output plate is driven. In sum, no drive torque is transferable. It can only be transmitted drive torque when the contact pressure on the sets of plates is not equal, but is greater on the left side here. This can be done mechanically and / or hydraulically by appropriately designed actuators 56 . 58 realize (eg with different sized piston cross sections).

Nevertheless, since friction work is done, a drive torque is still present. If the axial distance Δx relative to the friction diameter d _{REIB is} small, then this drive torque is low (eg, if correctly _dimensioned , approximately 5% to 10% of the maximum transmissible drive torque at high speed differential speed or small deflection). The conditions are only slightly different when the friction circle is placed around the axis A.

In 5 is the drive torque over the speed ratio of the clutch basket 90 and the clutch hub 92 applied. The kink, in which the transmitted drive torque drops sharply, is dependent on the ratio of friction diameter to axial offset. The smaller the axial offset or the larger the friction diameter, the more drive torque can be transmitted at a low speed ratio. An advantage results in the better Einregelbarkeit a differential speed, z. For example, you can calculate a wheel slip and therefrom a desired differential speed via the setpoint drive torque. Due to the distinctive sloping characteristic, this speed can be set well. In addition or as an alternative to the known control of the transmitted torque, the clutch according to the invention thus permits a self-regulating adjustment of the differential rotational speed.

Although in 1 By way of example, a drive train with rear-wheel drive is shown, the multi-plate clutch according to the invention can be used in various drive trains. For example, the multi-plate clutch can be installed in a drive train with front-wheel drive and / or an all-wheel / four-wheel drive train. Furthermore, the multi-plate clutch can not only distribute an additional torque on an output shaft of an axle differential unit, but it can also be provided between the axle differentials in a central differential (transfer case) of an all-wheel / four-wheel drive train to selectively add an additional torque to the Vorderachsdifferential- Unit or the rear axle differential unit.

Claims (18)

Multi-plate clutch ( 54 ) with: a clutch basket ( 90 ), which rotates about a first axis (A, B) and with a first plate set ( 94 ) connected is; and a clutch hub ( 92 ), which rotates about a second axis (A, B) and with a second plate set ( 96 ), the lamellae of the second lamella set ( 96 ) and the lamellae of the first lamella set ( 94 ) mesh; the lamellae of the lamella sets ( 94 . 96 ) are pressed against one another for transmitting a torque, characterized in that the first axis (A, B) and the second axis (A, B) are fixed and offset from each other. Multi-plate clutch ( 54 ) according to claim 1, wherein the lamellae of the second lamella set ( 96 ) and the lamellae of the first lamella set ( 94 ) engage each other along the entire circumference. Multi-plate clutch ( 54 ) according to claim 1, wherein the first axis (A, B) and the second axis (A, B) are offset relative to one another such that between the lamellae of the lamella sets ( 94 . 96 ) a force is transferable, which has a tangential component and a radial component, when the plate sets ( 94 . 96 ) are pressed against each other. Multi-plate clutch ( 54 ) according to claim 1, further comprising: a first wave ( 98 ), which rotatably with the clutch basket ( 90 ) connected is; and a second wave ( 64 ) with the clutch hub ( 92 ) is rotationally coupled. Multi-plate clutch ( 54 ) according to claim 4, further comprising: a ring gear ( 100 ), the non-rotatably with the clutch hub ( 92 ) and rotates about the second axis (B); and a gear ( 102 ), which is non-rotatable with the second shaft ( 64 ) and rotates about the first axis (A); the ring gear ( 100 ) and the gear ( 102 ) comb. Multi-plate clutch ( 54 ) according to claim 1, further comprising: a first wave ( 98 ' ) connected to the clutch basket ( 90 ) is rotationally coupled; and a second wave ( 64 ), the non-rotatably with the clutch hub ( 92 ) connected is. Multi-plate clutch ( 54 ) according to claim 6, further comprising: a ring gear ( 100 ' ), the non-rotatably with the clutch basket ( 90 ) and rotates about the first axis (B); and a gear ( 102 ' ), which is non-rotatable with the first shaft ( 98 ' ) and rotates about the second axis (A); the ring gear ( 100 ' ) and the gear ( 102 ' ) comb. Multi-plate clutch ( 54 ) according to one of the preceding claims, further comprising: at least one clutch actuator ( 56 . 58 ), which generates a contact force to the lamellae of the plate sets ( 94 . 96 ) to press against each other. Multi-plate clutch ( 54 ) according to claim 8, wherein the lamellae can be pressed against one another with a contact pressure, which along the respective circumference of the lamella sets ( 94 . 96 ) is unevenly distributed. Multi-plate clutch ( 54 ) according to claim 9, wherein the contact pressure in such an angular segment (WS ₁ ) of the circumference of the plate sets ( 94 . 96 ) is increased in terms of the contact force in another angle segment (WS ₂ ), in which a speed difference vector of the two sets of plates ( 94 . 96 ) in the direction in which a moment between the two sets of plates ( 94 . 96 ) is to be transmitted. Differential unit ( 34 ) for actively adjusting a transmitted torque in a drive train ( 10 ) of a motor vehicle, with at least one multi-plate clutch ( 54 ) according to any one of the preceding claims. Differential unit ( 34 ) according to claim 11, further comprising: a differential ( 52 ) and at least one actuator ( 56 . 58 ) for adjusting the contact pressure of the multi-plate clutch ( 54 ). Differential unit ( 34 ) according to claim 12, wherein the differential gear ( 52 ) a carrying drum ( 74 ), which with the clutch basket ( 90 ) of the multi-plate clutch ( 54 ) is rotationally fixed or rotationally connected. Differential unit ( 34 ) according to one of claims 12 or 13, wherein the differential gear ( 52 ) two bevel gear sets ( 76A . 76B ; 78A . 78B ), wherein the bevel gears ( 76A . 76B ) of a bevel gear set rotatably with corresponding output shafts ( 64 ) are connected. Differential unit ( 34 ) according to one of claims 12 or 13, wherein the differential gear ( 52 ) is a planetary gear differential, the outputs rotatably with corresponding output shafts ( 64 ) are connected. Powertrain ( 10 ) of a vehicle with a differential unit ( 24 ), the at least one multi-plate clutch ( 54 ) according to one of claims 1 to 10, wherein the drive train ( 10 ) further comprises: a control unit ( 40 ) for generating a control signal, wherein the contact pressure of the multi-plate clutch ( 54 ) based on the control signal. Drive train according to claim 16, wherein the control unit ( 40 ) for setting a predetermined differential speed of the clutch hub ( 92 ) relative to the clutch basket ( 90 ) is trained. Drive train according to one of claims 16 or 17, further comprising at least one sensor ( 42 . 44 . 46 ) for detecting an operating condition of the vehicle, the control signal based on the operating condition.

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