DE102007059531A1 - Self-locking crown gear differential for use as center differential of motor vehicle, has pressure rings subjected with axial force actuating multi-disk brake by actuators arranged at gear housing, where rings work on multi-disk units - Google Patents

Abstract

The gear differential (10) has compensating gears (20) designed as front toothed gears, and axle drive bevel gears (22a, 22b) designed as crown toothed gears. The bevel gears are connected with a set of multi-disk units (28a, 28b) of a multi-disk brake in a torque proof manner. Another set of multi-disk units (30a, 30b) are arranged at a differential cage (14) in a torque proof manner. The brake has pressure rings (32a, 32b) working on the units (30a, 30b) axially arranged on the cage. The rings are subjected with an axial force actuating the brake by actuators (38) arranged at a gear housing.

Description

Field of the invention

• – einen in einem Getriebegehäuse um eine Längsachse drehend antreibbaren Differentialkorb,
• – eine Mehrzahl von radial zu der Längsachse drehbar an dem Differentialkorb gelagerten und mit diesem umlaufenden Ausgleichsrädern,
• – zwei mit den Ausgleichsrädern kämmende, relativ zu dem Differentialkorb um die Längsachse drehbare Achswellenräder, wobei die miteinander kämmenden Räder als kronen- und stirnverzahnte Räder ausgebildet sind und die kronenverzahnten Räder bei einer Drehmomentübertragung entsprechend dem Betrag des übertragenen Drehmomentes entlang ihrer Lagerachsen, auf denen sie axial verschieblich gelagert sind, gegen eine Reibungsbremse auflaufen.

The invention relates to a self-locking crown gear, comprising

• A differential case rotatably drivable in a transmission housing about a longitudinal axis,
• - A plurality of radially to the longitudinal axis rotatably mounted on the differential carrier and rotating with this differential gears,
• - Two meshing with the differential gears, rotatable relative to the differential carrier about the longitudinal axis of the axle shaft gears, wherein the intermeshing wheels are formed as crown and spur gears and the crown gears at a torque transmission according to the amount of torque transmitted along their bearing axes on which they mounted axially displaceable, accrue against a friction brake.

State of the art

Such a differential is known from the DE 103 08 081 B3 , This document discloses a Kronenraddifferential whose Achswellenräder are designed as spur gears and whose differential gears are formed as meshing with the spur gears crown wheels. Upon transmission of a torque, the crown wheels, which are rotatably mounted on differential carrier bearing pin bearing, due to the growing meshing forces along its bearing axis to the outside, that is moved perpendicular to the longitudinal axis of the differential cage. The backs of the crown-toothed differential gears interact via a friction layer with the differential carrier, which slows down their rotation. This inhibition of the rotational movement of the differential gears leads to a relative locking of the Achswellenräder each other. Note that the terms "inhibit,""brake," and "lock," as used herein and throughout the application, are not to be construed in any way as "any movement inhibiting," but rather to indicate gradual obstruction and deceleration of the affected motion , This type of blocking effect leads to a symmetrization of transmitted to the non-rotatably connected to the axle gears output shafts moments. In order to achieve a targeted asymmetric torque distribution, said document proposes an additional axial displaceability of the axle-spur gears, which is actuated by actuators which are integrated in the output shafts. With axial displacement of the axle shaft along the longitudinal axis of the differential cage these run with their backs each against a arranged in the differential carrier disk brake. Also between their facing front sides friction body are provided, so that by appropriate actuation of the actuators the Achswellenräder can be locked individually against the differential carrier or against each other.

These Arrangement has the significant disadvantage that two separate Brake mechanisms, namely for the end-toothed Axle shaft gears on the one hand and for the crown gears On the other hand, differential gears have to be installed, which leads to space and cost disadvantages. In addition, require the output shafts that carry the axle shaft wheels, one complicated construction, which integrates the actuators, which of outside of the rotating shafts by means of housing-resistant Elements must be controllable. Such a complicated one Construction is expensive and error-prone.

From the DE 10 2004 001 019 B4 Another crown gear differential is known in which, in contrast to the aforementioned DE 103 08 081 B3 the axle-mounted gears are crown-toothed and the differential gears are spur-toothed. The front-toothed differential gears are fixed in a rotationally fixed manner perpendicular to the longitudinal axis of the differential cage on Ausgleichsradwellen, which are mounted in the differential carrier and enforce this to the outside. Outside the differential cage, the Ausgleichsradwellen wear annular brake body, which interact with a differential carrier encompassing and axially displaceable along its longitudinal axis brake bell in the manner of a friction brake. The axial displacement of the brake bell is actuated by external actuators. Upon actuation, the rotation of the differential gears is blocked, which causes a locking of the crowned axle shaft relative to each other. A targeted increase in the asymmetry of the transmitted to the output shafts moments is not possible with this device. Also, a self-locking effect of the differential is not given.

task

It is the object of the present invention, a generic Further develop crown gear differential such that in addition to the self-locking effect also a specific influencing of the torque distribution on the Output shafts on inexpensive and technically uncomplicated Way becomes possible.

Presentation of the invention

This object is achieved in conjunction with the features of the preamble of claim 1, characterized in that the differential gears as forehead ver toothed wheels are formed,
in that the axle-shaft gears are designed as crown-toothed wheels which are in each case non-rotatably connected to a first disk set of a multi-disk brake, whose second disk set intermittently arranged with the first disk set is rotatably mounted on the differential carrier, and
in that each multi-disc brake has a pressure ring acting axially outward on its set of disks arranged on the differential carrier, wherein at least one of the pressure rings can be acted upon by means of an axial drive which actuates the associated multi-disc brake by means of an actuator fixed to the transmission housing.

The The invention initially provides that the teeth of the Balancing and axial shaft gears reversed than the generic State of the art are formed, d. H. the differential gears are designed as spur gears and the axle gears as crown wheels. In this way, both the self-locking feature as well as the externally controlled blocking function on the axle shaft gears attack. For the differential gears and their bearings On the other hand, a simple construction that does not suffice required interactions with brake elements complicates becomes. As with the generic Kronenraddifferential tilt the crown wheels during torque transmission thereto, to be displaced axially outwards on its bearing axis, what here as well as in the prior art for a self-locking effect exploited by interaction with a friction brake. at However, the present invention is additionally provided that the friction brake can also be controlled externally. It can therefore by a double loading of the brake of the invention Differentials are spoken, namely on the one hand the passive application by the torque-related axial displacement the axle and on the other hand, the active loading by externally and arbitrarily activatable braking of the axle shaft gears.

Around To achieve this, the friction brakes are as multi-disc brakes educated. Rotationally connected to each axle shaft is a Inner disc carrier carrying an inner disc pack, which is nested with an outer plate set, which rotatably on a rotatably connected to the differential carrier Outer plate carrier is arranged. At the passive Locking of the differential, d. H. self-locking, moves At least one Achswellenrad torque due to axially outward, thereby clamped the disk sets of the associated multi-disc brake with each other and create a braking effect. For active blocking is each multi-disc brake with one on the outer disc pack provided acting pressure ring. The pressure ring rotates at least in Actuation case in which it is in frictional contact with the outer disk set, with the differential carrier with. To operate the pressure ring a transmission housing fixed actuator is provided, the axially displaces the thrust ring and thus the disc packs of associated multi-disc brake clamped together, creating a braking force is exerted on the associated axle shaft. hereby can be independent of the current moment transmission, additional blocking effect can be controlled externally.

Of the Advantage of the present invention is that on constructive simple manner an actively controllable limited slip differential available is made, which in addition or in case of failure active control shows only a self-locking effect.

When constructively critical can be considered the interface between the typically with the differential carrier co-rotating pressure ring and the actuator or in the case that only one pressure ring by means of a Actuator is displaceable, the transmission housing. Here is provided in a preferred embodiment of the invention, that each pressure ring by means of a thrust bearing against the gear housing is supported. The support against the gearbox can be done directly or indirectly. In the case of a means Actuator actuated pressure ring is the support conveniently indirectly via the actuator, d. H. the thrust bearing is between an axially movable lifting element arranged the actuator and the pressure ring.

The The present invention includes two basic variants. At a first variant of the differential carrier is relative to the transmission housing axially slidably arranged. This means in particular that the drive connection between the Axialkorb and its drive shaft rotatably but axially is designed movable. In this embodiment it is sufficient to provide only one of the pressure rings with an actuator. The other pressure ring is supported directly, preferably over a thrust bearing, on the gearbox from. By operation of the actuator, the disk packs are immediately applied Multi-disc brake braced against each other. At the same time, however, gives way the entire differential carrier in the loading direction, whereby the another pressure ring is subjected to a counterforce, which is the Disk packs of its associated multi-disc brake clamped together. On This way, both axle gears are in addition to the passive, possibly asymmetric self-locking effect with a active, controllable via the actuator, symmetrical blocking effect applied.

In an alternative variant of the invention, the differential carrier is relative to the Getriebegehäu se axially fixed and each pressure ring is acted upon separately by means of a transmission housing fixedly arranged actuator with an associated axial disc brake actuating axial force. In this variant, the differential carrier can not avoid the axial forces applied via the pressure rings. Thus, the actuation of an actuator, ie the tension of the disk sets of a multi-disc brake by means of the associated pressure ring has no effect on the second multi-disc brake, which is designed substantially identical. In this variant, the axle gears can therefore be applied independently of each other with an active blocking effect, which acts in addition to the passive self-locking.

Prefers is such a differential as the center differential of a motor vehicle used, although a use as an axle differential conceivable is. In the preferred use as a center differential, it is in particular favorable when a differential carrier driving drive shaft Coaxial within a non-rotatable with one of the axle gears connected and arranged as a hollow shaft output shaft arranged is. For example, in a motor vehicle with a front engine a drive torque from the engine via the drive shaft transmitted to the differential carrier and the front axle Deducted part of the torque on the hollow shaft, which drives the shaft axially enclosing, again forward to a Vorderachsdifferential be passed while the part of the rear axle intended to contribute the other output shaft fed to the rear differential becomes.

Further Features and advantages of the invention will become apparent from the following, special description and the drawings.

Brief description of the drawings

It demonstrate:

1 a first embodiment of a crown gear according to the invention.

2 a second embodiment of a crown gear according to the invention.

Preferred embodiments

1 shows a first embodiment of a crown gear according to the invention 10 , In the installed state, the introduction of a moment takes place from an upstream, in 1 not shown engine via a drive shaft 12 , which is preferably designed as a central solid shaft. Of course, the training as a hollow shaft is conceivable if, for example, in the drive shaft 12 an oil channel out or another wave to be stored. The drive shaft 12 is rotatable with a differential carrier 14 connected. The connection can, for example, as a spline 16 be formed, wherein at the in 1 illustrated first embodiment of the invention, an axial displaceability of the differential cage 14 on the drive shaft 12 preserved. This is in 1 by means of the movement arrow 18 indicated. The differential carrier 14 carries a plurality of differential gears 20 , which are formed as spur gears and are rotatably mounted about radially aligned axes. Of course it is also possible, the differential gears 20 rotatably attached to radially aligned shafts, which in turn rotatable in the differential carrier 14 are stored. However, this embodiment is not preferred due to the higher mechanical complexity. The differential gears 20 combing with crown-toothed axle-shaft gears 22a . 22b , The axle shaft wheels 22a . 22b are each with an associated output shaft 24a . 24b rotatably connected. At the in 1 illustrated embodiment, the output shaft 24a designed as a hollow shaft, which is coaxial with the drive shaft 12 is arranged. As can be seen in the figure, have the teeth of the crown wheels 22a . 22b different radii in the preferred embodiment of the invention. This results in straight-ahead driving an asymmetrical distribution of the transmitted moments, which makes the illustrated differential particularly suitable for use as a center differential. Of course, symmetrical variants are also conceivable, which can then be used, for example, as axle differentials in motor vehicles. Every crown wheel 22a . 22b is fixed to a plate carrier associated with it 26a . 26b connected, each with a set of friction plates 28a . 28b wearing a friction brake. With the plate sets 28a . 28b nested are corresponding lamella sets 30a . 30b arranged rotatably with the differential carrier 14 or connected to this one plate carrier are connected.

For passive operation of the differential 10 the axle shaft gears shift 22a . 22b in accordance with the transmitted moment axially on their respective associated shaft 24a . 24b , causing the disk packs 28a . 30a respectively. 28b . 30b be braced together so that the respective axle shaft 22a . 22b undergoes a braking action. It is at the differential 10 therefore a self-locking differential.

In order to enable an active control of the blocking effect, each multi-disc brake with an additional pressure ring 32a . 32b provided on the axially outer lamella of the outer disk pack 30a respectively. 30b acts. The pressure ring 32a . 32b is supported by a thrust bearing 34a . 34b against the case 36 from. On the in 1 left side of the Dif ferentials 10 , this support is immediate; on the in 1 on the right side, the support is indirectly via an externally controllable actuator 38 , The actuator 38 can, as by the movement arrow 40 shown to be adjusted in the axial direction. When extending the actuator 38 becomes the pressure ring 32a subjected to an inwardly directed axial force, which he attached to the outer disk set 30a transfers, which in this way with the inner disc pack 28a is strained. As a result, an externally controlled braking effect on the axle shaft 22a exercised. At the same time the entire differential carrier shifts 14 against the opposite pressure ring 32b , which is about its counterforce effect on the outer disc package 30b its tension with the inner disc pack 28b causes, so that the second axle shaft 22b undergoes a braking action. This symmetrical additional braking effect, which is actively controllable, adds to the passive self-locking effect explained above.

2 shows a second embodiment of a differential according to the invention 100 which has the same structure in essential parts as the part in 1 shown differential 10 , Like or analogous parts and elements are designated by like reference numerals. With regard to the effect of each element is to the above description of 1 directed. Unlike the embodiment of 1 is at the in 2 shown variant of the differential carrier 14 not only rotatable but also axially fixed to the drive shaft 12 connected. An axial displaceability of the differential cage 14 is thus not given in this embodiment. Corresponding to both axle-shaft wheels 22a and 22b to actively brake, a pair of actuators 38a . 38b required, over which the pressure rings 32a . 32b indirectly against the case 36 support. For rotational decoupling, as well as in the embodiment of 1 , each a thrust bearing 34a . 34b intended. As by the movement arrows 40a . 40b indicated, both actuators, preferably independently, axially deflectable. As a result, the multi-disc brakes of both axle gears 22a . 22b be confirmed independently. In this way, a symmetrical or asymmetric active barrier effect can be generated in addition to the symmetrical, passive self-locking effect explained above.

As actuators 38 . 38a . 38b In principle, all known or still to be developed actuators can be used which have a controlled deflectable lifting element. Purely by way of example, mechanical systems (eg ball ramp), electromagnetic, piezoelectric, electromotive, hydraulic, pneumatic actuators or combinations thereof can be realized.

Naturally put those discussed in the special description and in the Figures shown embodiment only illustrative embodiments The expert is in the light of the local Revelation a wide range of possible variations given by. In particular, the interpretation of the teeth, z. B. Radii, numbers of teeth etc. as well as the concrete control or Control of the actuators is the expert on the basis of his expertise adapt to the specific case.

For example The actuators can also be used simultaneously if suitably designed as sensors for a force acting on the pressure ring work whose sensor signal is used to control the blocking effect can be. The name chosen here "Lamella Set" does not necessarily have to name a plurality of lamellae. There are Also variants of multi-disc brakes with only one friction plate each Slat set conceivable.

10

differential

100

differential

12

drive shaft

14

differential carrier

16

splines

15 '

axial fixed spline

18

movement arrow

20

Compensation spur

22a, b

Axle shaft crown

24a, b

output shaft

26a, b

plate carrier

28a, b

Inner disc package

30a, b

External disk pack

32a, b

pressure ring

34a, b

axial bearing

36

casing

38 a, b

actuator

40 a, b

movement arrow

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10308081 B3 [0002, 0004]
• - DE 102004001019 B4 [0004]

Claims (6)

Self-locking crown gear differential, comprising - one in a transmission housing ( 36 ) about a longitudinal axis rotationally driven differential carrier ( 14 ), - a plurality of radially to the longitudinal axis rotatable on the differential carrier ( 14 ) and with this revolving balancing wheels ( 20 ), - two with the differential gears ( 20 ) meshing, relative to the differential carrier ( 14 ) about the longitudinal axis rotatable axle ( 22a , b) the intermeshing wheels ( 20 ; 22a , b) are formed as crown and end-toothed wheels and the crown-toothed wheels ( 22a , b) at a torque transmission according to the amount of transmitted torque along its bearing axes ( 24a , b) on which they are mounted axially displaceable, against a friction brake ( 30a , b) accumulate, characterized in that the differential gears ( 20 ) are designed as front-toothed wheels, that the axle-shaft wheels ( 22a , b) are formed as crown-toothed wheels, each non-rotatably with a first plate set ( 28a , b) a multi-disc brake, with the first set of blades ( 28a , b) intermittently arranged second plate set ( 30a , b) rotationally fixed to the differential carrier ( 14 ), and that each multi-disc brake has an axially outward on its at the differential carrier ( 14 ) arranged plate set ( 30a , b) acting pressure ring ( 32a , b), wherein at least one of the pressure rings ( 32a , b) by means of a gear housing fixedly arranged actuator ( 38 ; 38a , b) can be acted upon with an axial force which actuates the associated multi-disc brake. Crown gear differential according to claim 1, characterized in that each pressure ring ( 32a , b) by means of a thrust bearing ( 34a , b) the transmission housing ( 36 ) is supported. Crown gear differential according to one of the preceding claims, characterized in that the differential carrier ( 14 ) relative to the transmission housing ( 36 ) Is arranged axially displaceable. Crown gear differential according to one of claims 1 to 2, characterized in that the differential carrier ( 14 ) relative to the transmission housing ( 36 ) is axially fixed and each pressure ring ( 32a , b) separately by means of a gear housing fixedly arranged actuator ( 38a , b) can be acted upon by an axial force which actuates the respective associated multi-disc brake. Crown gear differential according to one of the preceding claims, characterized in that a differential carrier ( 14 ) driving drive shaft ( 12 ) coaxially within a rotationally fixed with one of the axle ( 22a ) and formed as a hollow shaft output shaft ( 24a ) is arranged. Use of a crown gear differential ( 10 ; 100 ) according to one of the preceding claims as a center differential of a motor vehicle, wherein a first axle ( 22b ) with a first output shaft ( 24b ), which directs an output torque to a rear differential, is rotatably connected and a second axle ( 22a ) with a second output shaft ( 24a ), which directs an output torque to a Vorderachsdifferential rotatably connected.