DE102019202600B4 - Axle differential with variable locking device - Google Patents

Abstract

Drive arrangement for a vehicle axle (VA) of a motor vehicle, in which a drive axle torque can be transmitted to the vehicle wheels (6) via an axle differential (5) during driving operation, the axle differential (5) having a drive-side differential cage (13) on which at least one Balance gear (11) is rotatably mounted, and a first axle gear (7) and a second axle gear (7), which are arranged at right angles to the balance gear (11) and coaxially at a distance from one another and are each non-rotatably on an axle half shaft leading to the vehicle wheel (6). 9) are arranged, with each of the axle gears (7) meshing with the compensating gear (11), the drive arrangement having a locking clutch (23) as a differential lock, by means of which the compensating gear (11) rotatably mounted on the differential cage (13) is rotationally fixed on the differential cage (13) can be coupled, and wherein the clutch (23) with respect to the vehicle axis (VA) radially on the outside of the differential k orb (13), characterized in that the clutch (23) has a clutch housing (25) which is fastened to a peripheral wall (21) of the differential cage (13) and into which the balancer shaft (17) projects, and in that between the clutch housing ( 25) and the balancer shaft (17) there is a clutch pack in which the inner discs (27) and outer discs (29) are stacked axially one on top of the other, and that the inner discs (27) can be moved axially, but are non-rotatable in the circumferential direction, with internal teeth on the balancer shaft (17) are arranged, and that the outer disks (29) are axially displaceable, but non-rotatable in the circumferential direction, are arranged with external teeth on the clutch housing (25).

Description

The invention relates to a drive arrangement for a vehicle axle according to the preamble of claim 1.

In such a drive arrangement, a drive axle torque is generated during driving operation, for example by an electric machine, which can be transmitted to the vehicle wheels of a two-track vehicle via an axle differential. The axle differential can be a bevel gear differential with a drive-side differential cage on which at least one pinion gear is rotatably mounted. The bevel gear differential also has a first axle bevel gear and a second axle bevel gear. These are arranged at right angles to the pinion gear and coaxially at a distance from one another.

The two axle bevel gears are each arranged in a rotationally fixed manner on an axle half shaft leading to the respective vehicle wheel. Each of the side gears meshes with the pinion gear.

In a multi-track vehicle, such an axle differential is used on the driven vehicle axle in order to allow a speed difference between the two vehicle wheels, for example when cornering. Another property of a simple axle differential is that torque is distributed to both output sides. At the axle differential, the same torque is transmitted to both vehicle wheels. This is disadvantageous if there is a different traction capacity on the two vehicle wheels, for example on a surface that is slippery on one side or when the vehicle wheel on the inside of the curve is relieved during dynamic cornering. In this case, the vehicle wheel with the lower traction capacity also limits the wheel torque of the other vehicle wheel, which actually could transmit more torque. This disadvantage is eliminated by means of a differential lock, in which the output shafts of the differential can be coupled to the differential housing to a greater or lesser extent by means of friction clutches or completely by means of a positive-locking clutch. This generates an additional friction or coupling torque, which increases the wheel torque of the vehicle wheel with the greater traction capacity. The axle torque as the sum of the two wheel torques thus increases. Variable locking devices are generally implemented by providing a multi-plate clutch between an output shaft and the differential case. This is acted upon by an axial clutch actuation, that is to say with a variable axial force, so that a variable blocking value can be set if necessary.

Such a clutch actuation in the axial direction can be problematic with regard to the space available in the vehicle axle. In addition, due to the comparatively high drive torques acting on the half-axle shafts, a correspondingly large clutch is required.

From the DE 10 2016 203 970 A1 a drive train of a motor vehicle is known. From the DE 10 2016 221 016 A1 a differential gear for a motor vehicle is known.

the U.S. 6,354,978 B1 discloses a generic differential and method for variable traction control. From the DE 35 35 339 A1 a differential gear with compensating brake is known. the DE 38 24 060 A1 discloses a self-locking differential and transfer case as a simultaneous anti-lock braking system for all driven wheels. the U.S. 2019/0 120 362 A1 discloses a superposition type torque distribution differential.

The object of the invention is to provide a drive arrangement in which, in comparison to the prior art, the locking clutch can be arranged in the vehicle axle in a space-saving manner and with a reduced space requirement.

The object is solved by the features of claim 1. Preferred developments of the invention are disclosed in the dependent claims.

According to claim 1, the drive arrangement has a clutch as a differential lock, by means of which the compensating gear wheel, which is rotatably mounted on the differential carrier, can be coupled to the differential carrier in a rotationally fixed manner. The invention is implemented by the at least one compensating gear in the axle differential being designed to be significantly smaller in diameter than the axle gears, with the locking clutch coupling the compensating gear to a greater or lesser extent with the differential carrier or the differential housing. Since the differential gear is significantly smaller than the axle gears, only a smaller torque has to be coupled to the differential cage in locking mode. Accordingly, the locking clutch can be made smaller, which reduces the space required for the clutch. The differential gear can be coupled to the differential carrier by means of a friction clutch or a claw clutch. The locking clutch can preferably be controlled with the aid of a radial clutch actuation. This can be implemented via an axially displaceable, wedge-shaped switching element.

Further aspects of the invention are described below: For example, the differential gearwheel can be arranged on a differential shaft in a rotationally fixed manner for the purpose of pivoting on the differential cage. The balancer shaft can be guided to the outside through a bearing opening of the differential cage, in particular with the interposition of a rotary bearing.

In this case, the clutch can be positioned on the outside on a peripheral wall of the differential carrier. In a comparative form not covered by the invention, the clutch can be a dog clutch that can only be shifted in a load-free manner. As an alternative to this, the clutch can also be implemented as a friction clutch that can be shifted under load. The locking clutch can be controlled electrically by a clutch control unit between a locked position, in which a compensating rotary movement of the compensating gear is locked, and a release position, in which the compensating rotary movement of the compensating gear is enabled without a clutch locking effect. In particular, a locking clutch implemented as a friction clutch can be controlled by a clutch control unit in a slip control area in order to set clutch slip. In this way, a degree of locking or the locking effect of the clutch can be varied. According to the invention, the clutch is arranged radially on the outside of the differential cage in relation to the vehicle axis in a space-saving manner, ie no longer on an end face of the differential cage that is axial in relation to the vehicle axis.

According to the invention, the locking clutch, in particular a multi-plate clutch, has a clutch housing which is fastened to a peripheral wall of the differential carrier and into which the balancer shaft protrudes. A clutch pack is arranged between the clutch housing and the balancer shaft, in which the inner disks and outer disks are stacked axially one above the other. The inner disks can be moved axially, but are non-rotatable in the circumferential direction, and are arranged on the balancer shaft with internal teeth. Similarly, the outer disks are axially displaceable, but non-rotatable in the circumferential direction, and are arranged with external teeth on the clutch housing. The clutch pack of the locking clutch can be acted upon in a radial direction with increasing contact pressure up to a complete locking effect, in which the inner and outer disks are braced against each other.

The clutch pack of the clutch can be subjected to the contact pressure via a contact pressure element. The pressing element (pressure piece) can preferably be adjusted with respect to the vehicle axis in the radial direction over a radial adjustment path between the radially outer release position and the radially inner locking position. The pressing element can be adjusted between the release position and the locked position by means of a switching element. In addition, the radial clutch actuation can have a switching element that can be adjusted with respect to the vehicle axis over an axial adjustment path between the release position and the locked position. The axially adjustable shifting element can be designed with a shifting gate which interacts with a corresponding counter-contour of the radially adjustable pressing element.

The shift gate of the shift element can preferably be in sliding contact with the counter-contour of the clutch-side pressure element. In this case, the shifting element shifting gate can have a ramp section which, with respect to the vehicle axis, runs in a wedge shape in the direction of a radially inner blocking section of the shifting gate. For clutch slip control, the shift gate can press against the pressure element on the clutch side in the area of the ramp section. In contrast, the shift gate blocking section presses against the clutch-side pressure element if a complete blocking effect is to be generated.

With regard to mechanically simple actuation, the switching element can have a sliding sleeve which is arranged on a switching body so that it can be adjusted axially via internal teeth. The switching body is preferably arranged in a rotationally fixed manner on the differential cage. In this case, the sliding sleeve can be axially adjustable by means of an actuator that can be controlled by the clutch control device, in particular a shift fork.

An exemplary embodiment of the invention is described below with reference to the accompanying figures.

• 1 in grob schematischer Darstellung eine Antriebsanordnung für eine Fahrzeugachse eines Kraftfahrzeugs;
• 2 ein Achsdifferenzial mit integrierter Differenzialsperre, die sich in einer Freigabestellung befindet; und
• 3 eine Ansicht entsprechend der 2, in der sich die Differenzialsperre in ihrer Sperrstellung befindet.

Show it:

• 1 in a roughly schematic representation of a drive arrangement for a vehicle axle of a motor vehicle;
• 2 an axle differential with integrated differential lock, which is in a release position; and
• 3 a view according to the 2 , in which the differential lock is in its locked position.

In the 1 shows a drive arrangement for, for example, a front axle VA of a two-track motor vehicle, in which an electric machine EM is drivingly connected via a countershaft 1 to an input-side external gear 3 of a front-axle differential 5 . On the output side of the front axle differential 5 are axle bevel gears 7 connected to the two axle half shafts 9. The axle bevel gears 7 and a pinion gear 11 toothed therewith are positioned within a differential cage 13 of the axle differential 5 . The two axle bevel gears 7 are positioned coaxially with one another at a distance within the differential carrier 13 and are aligned at right angles to the pinion gear 11 . In the 1 the two axle half-shafts 9 are each guided through bearing openings in axial end walls 15 of the differential carrier 13, optionally with the interposition of a rotary bearing (not indicated). Analogously to this, the differential bevel gear 11 is arranged in a rotationally fixed manner on a balancing shaft 17 which, if necessary with the interposition of a rotary bearing, is guided to the outside through a bearing opening 19 in a peripheral wall 21 of the differential cage 13 . In the 2 and 3 the pinion gear 11 is designed to be significantly smaller than the axle bevel gears 7 .

As can be seen from the figures, the differential lock is implemented as a locking clutch 23, by means of which the pinion gear 11, which is rotatably mounted on the differential cage 13, can be coupled to the differential cage 13 in a rotationally fixed manner. The locking clutch 23 is implemented as a multi-plate clutch that can be shifted under load, the clutch housing 25 of which is fastened radially on the outside to the peripheral wall 21 of the differential carrier 13 . The balancing shaft 17 of the differential bevel gear 11 protrudes into the clutch housing 25 . Between the balancer shaft 17 and the clutch housing 25, a clutch pack is connected, which is made up of inner disks 27 and outer disks 29 stacked axially one on top of the other. The inner disks 27 are axially displaceable, but non-rotatably in the circumferential direction with internal teeth on the balancer shaft 17 . Similarly, the outer disks 29 are axially displaceable, but non-rotatable in the circumferential direction, and are arranged with external teeth on the inner circumference of the clutch housing 25 . The clutch pack can in the 2 via clutch actuation in the radial direction with increasing contact pressure F ( 3 ) are applied up to a complete blocking effect, in which the inner and outer disks 27, 29 are braced against each other. For this purpose, the locking clutch 23 has a radially outer pressing element 31 ( 3 ), which in the radial direction has a radial travel r ( 2 ) between the radially outer release position FR ( 2 ) and a radially inner blocking position S ( 3 ) is adjustable. The radially adjustable pressing element (ie pressure piece) 31 acts in the 2 with an axially adjustable switching element 33 together. The switching element 33 is over an axial travel a ( 3 ) between the release position FR ( 2 ) and the locked position S ( 3 ) adjustable.

In the 2 or 3 the axially adjustable shifting element 33 is designed with a shifting gate which interacts with a counter-contour of the pressing element 31 . The shift gate has in the 2 or 3 a ramp section 37 which, with respect to the vehicle axis VA, tapers in the direction of a radially inner blocking section 39 of the shift gate in a wedge shape. In the case of clutch slip control, the axially adjustable shifting element 33 is controlled by the clutch control device in such a way that the shifting element 33 is in sliding contact with the clutch-side pressure element 31 in the region of its ramp section 37 . If a complete blocking effect is to be achieved, the switching element 33 is axially displaced until its shift gate blocking section 39 presses against the clutch-side pressure element 31, as shown in FIG 3 is shown.

With regard to an actuator system that is simple in terms of components, the switching element can have a sliding sleeve 41 which is arranged on a switching body 43 in an axially adjustable manner via internal teeth. The switching body 43 is in turn integrally formed on the differential carrier 13 in a rotationally fixed manner. The sliding sleeve 41 of the axially adjustable shift element 33 can be adjusted axially with respect to the differential carrier 13 by means of an actuator, for example a shift fork 45 .

Reference List

1

transmission

3

external teeth

5

axle differential

7

side gears

9

axle half shafts

11

pinions

13

differential cage

15

axial end wall

17

balance shaft

19

warehouse opening

21

perimeter wall

23

locking clutch

25

clutch housing

27

inner slats

29

outer slats

31

radially adjustable pressure element

33

axially adjustable switching element

37

ramps

39

lockdown section

41

sliding sleeve

43

switch body

45

actuator

EM

electric machine

v.a

vehicle axle

right

radial travel

a

axial travel

f

pressing force

S

locked position

FR

release position

Claims (9)

Drive arrangement for a vehicle axle (VA) of a motor vehicle, in which a drive axle torque can be transmitted to the vehicle wheels (6) via an axle differential (5) during driving operation, the axle differential (5) having a drive-side differential cage (13) on which at least one Balance gear (11) is rotatably mounted, and a first axle gear (7) and a second axle gear (7), which are arranged at right angles to the balance gear (11) and coaxially at a distance from one another and are each non-rotatably on an axle half shaft leading to the vehicle wheel (6). 9) are arranged, with each of the axle gears (7) meshing with the differential gear (11), the drive arrangement having a locking clutch (23) as a differential lock, by means of which the differential gear (11) rotatably mounted on the differential cage (13) is rotationally fixed on the differential cage (13) can be coupled, and wherein the clutch (23) with respect to the vehicle axis (VA) radially on the outside of the differential orb (13), characterized in that the clutch (23) has a clutch housing (25) which is fastened to a peripheral wall (21) of the differential cage (13) and into which the balancer shaft (17) projects, and in that between the clutch housing ( 25) and the balancer shaft (17) there is a clutch pack in which the inner discs (27) and outer discs (29) are stacked axially one on top of the other, and that the inner discs (27) can be moved axially, but are non-rotatable in the circumferential direction, with internal teeth on the balancer shaft (17) are arranged, and that the outer disks (29) are axially displaceable, but non-rotatable in the circumferential direction, are arranged with external teeth on the clutch housing (25). Drive arrangement according to claim 1 , characterized in that for the pivot bearing on the differential cage (13), the balancer gear (11) is arranged in a rotationally fixed manner on a balancer shaft (17), and in that the balancer shaft (17) passes through a bearing opening (19) of the differential cage (13) with a pivot bearing interposed is guided outside. Drive arrangement according to claim 1 or 2 , characterized in that the clutch is a friction clutch that can also be shifted under load, and/or that the clutch (23) moves between a locked position (S), in which a compensating rotary movement of the compensating gear (11) is blocked, and a release position (FR ) can be switched, in which the compensatory rotary movement is made possible without a clutch locking effect, and that the clutch (23) can be controlled by a clutch control device in a slip control range in order to set a clutch slip, whereby a degree of locking or the locking effect of the clutch ( 23) is variable. Drive arrangement according to claim 1 , characterized in that the clutch (23) is a multi-plate clutch and in that the clutch pack can be acted upon by a clutch actuation in the radial direction with a contact pressure force (F) up to a complete blocking effect, in which the inner and outer plates (27, 29 ) can be braced against each other. Drive arrangement according to one of the preceding claims, characterized in that the clutch (23) has a pressure element (31) which is part of a radial clutch actuation, and that the pressure element (31) with respect to the vehicle axis (VA) in the radial direction via a radial Travel (r) between the radially outer release position (FR) and the radially inner locked position (S) is adjustable. Drive arrangement according to claim 5 , characterized in that the radial clutch actuation has a shifting element (33), that the shifting element (33) has a shifting gate which is in sliding contact with a counter-contour of the pressing element (31), and that the shifting element (33) with respect to the vehicle axis (VA) can be adjusted via an axial travel (a) between the release position (FR) and the locked position (S). Drive arrangement according to claim 6 , characterized in that the shifting gate of the shifting element (33) has a ramp section (37) which, with respect to the vehicle axis (VA), tapers in the direction of a radially inner blocking section (39) of the shifting gate, and that for clutch slip control the shift gate ramp section (37) presses against the clutch-side pressure element (31), and that in the locked position (S) the shift gate locking section (39) presses against the clutch-side pressure element (31). Drive arrangement according to claim 6 or 7 , characterized in that the switching element (33) has a sliding sleeve (41) which is arranged on a switching body (43) so that it can be adjusted axially via internal teeth, and in that the switching body (43) is arranged on the differential carrier (13) in a rotationally fixed manner, and/ or that the sliding sleeve (41) can be adjusted axially by means of an actuator that can be controlled by the clutch control unit. Drive arrangement according to one of the preceding claims, characterized in that the compensating gear (11) is designed to be significantly smaller than the axle gears (7).

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