EP2663789A1

EP2663789A1 - Locking device for differential gearing

Info

Publication number: EP2663789A1
Application number: EP11793674.0A
Authority: EP
Inventors: Alexander Martin; Karsten Fabian; Lothar Wolf; Daniela Kern
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 2011-01-14
Filing date: 2011-12-09
Publication date: 2013-11-20
Also published as: WO2012095134A1; DE102011002709A1

Abstract

The invention relates to a locking device for a differential gearing (10), comprising an actuator (16, 17, 18, 19) and at least one connecting element (20, 21). The at least one connecting element (20, 21) can be moved by means of the actuator (16, 17, 18, 19) between a respective open position and a respective braking position, and an output shaft (12b) of the differential gearing (10) can be connected to a housing (13) of the differential gearing (10) in a rotationally fixed manner by means of a first connecting element (21) of the at least one connecting element (20, 21) in the corresponding braking position of said connecting element. The invention further relates to a differential gearing comprising at least one locking device, wherein the locking device (15) is designed in a corresponding manner and an output shaft (12b) of the differential gearing (10) is connected to a housing (13) of the differential gearing (10) in a rotationally fixed manner by means of the first connecting element (21) of the at least one connecting element (20, 21) in the braking position.

Description

Locking device for differential

The invention relates to a locking device for a differential, in particular a locking device for a differential gear of a motor vehicle.

Locking devices are used in particular for motor vehicles and are provided for selectively locking the vehicle at a standstill, so that it can be secured against unintentional movement. There are various embodiments of locking devices are known, which are used in dependence on the type of transmission provided in the vehicle.

For manual transmissions so-called parking brakes or parking brakes are known. These have, for example, a arranged in the passenger compartment lever for actuating a rear wheel brake of the vehicle, wherein a force transmission, for example via a Bowden cable or the parking brake as an electromechanical parking brake with additional elektrpmechanischen components for actuating the

Rear brake is formed.

However, the known parking brakes have the disadvantage that they provide only a small slope holding force. Also, the effect of the parking brake is negatively influenced by environmental factors, such as corrosion or frost. In addition, the parking brake usually offers only a small anti-theft function.

In automatic transmissions comes in addition to the manual transmission

described parking brake usually a so-called parking brake used. This is usually done by inserting a speed dial The automatic transmission is activated in the "P" position and is designed as a mechanical lock, whereby a pawl, which is moved by actuating a locking member, engages in a parking lock wheel which is connected in a rotationally fixed manner to an output shaft Another blocking element prevents self-locking by releasing the pawl under load To open the parking brake, an additional release device is required with which the parking brake can be unlocked.

From DE 10 2004 021 981 A1, for example, such a parking brake for an automated motor vehicle transmission with at least one spring accumulator for engaging the parking brake is known. This includes one

Release device for opening the parking brake and one of the spring force from at least one spring memory counteracting arranged holding device for holding the parking brake in the open state, wherein the release device can be actuated by a gear actuator.

The well-known parking barriers generally have the disadvantage that when the parking brake is released, in particular on gradients, a shift of the parking brake occurs, which is perceived by a user as unpleasant and annoying. In addition, due to its mode of operation, the parking brake can not be provided alone in the vehicle, since it offers no possibility to brake the vehicle while driving and therefore does not meet the legal requirements.

Thus, it is particularly necessary for vehicles with automatic transmission in addition to a parking brake additionally provide a parking brake or a parking brake. However, this means that two identically acting and thus redundant arrangements are provided for securing the vehicle and therefore, in particular, operating elements, actuators, control devices and wiring must be provided in duplicate, which results in a high material requirement, an increased weight of the vehicle. how high material and manufacturing costs arise. Moreover, in the case of electrified components of the locking devices, a high degree of crosslinking increases, which results in a high complexity of the arrangements.

Also for the user of the vehicle, the complexity of the operation increases with the number of systems to be operated. This is in accordance with the above description with two locking devices confronted, which have a same principle of operation, so that an intuitive operation is difficult.

However, not only for vehicles with automatic transmission but also for those with manual parking brakes are known as additional locking devices from the prior art. For example, in DE 197 10 975 A1 a parking brake for motor vehicles with manual transmission is described, which comprises a driven-side component of the differential gear, which is positively lockable with an operable from the driver's seat, movably supported on the vehicle locking member. Here is the

Differential housing fixed to the vehicle when the parking brake is in the actuated state. However, this has the consequence that the two output shafts of the differential gear still remain rotatable against each other via the differential. Furthermore, a shield turns out to be particularly difficult of moving elements of the parking brake against dirt and damage.

Against the above background, it is therefore an object of the invention a

Provide locking device, in particular for motor vehicles, which is as independent as possible used by a gear type used and prevents redundancy of different, gleichwirkender systems and eliminates the disadvantages described or at least reduced.

This object is achieved by a locking device according to the invention for differential gear according to the subject of claim 1 or a differential with a corresponding locking device according to claim 11. Advantageous embodiments are described in the subclaims.

It is therefore provided a locking device for a differential with an actuator and at least one connecting element. The at least one connecting element is movable by means of the actuator between a respective open position and a respective braking position. An output shaft of the differential gear is rotatably connected by means of a first connecting element of the at least one connecting element in the associated braking position with a housing of the differential gear.

This means that the actuator is intended to act on the at least one connecting element in such a way and to act on this so that the connecting element can be selectively moved between the two positions mentioned by means of the actuator. The first of the at least one connecting element is in its open position, the output shaft is released and freely rotatable relative to the housing. Operation of the vehicle is possible without restrictions. On the other hand, if the first connecting element is in its braking position, then the output shaft is non-rotatably connected to the housing, so that a relative movement of the two components is blocked or braked relative to one another. For this purpose, the first connecting element can be arranged either as a link between the housing and the output shaft and thus connect the two components together or act on at least one of the two components, that they are directly related to each other and thus the relative movement is blocked. If a plurality of connecting elements are provided, then each of these connecting elements can have its individual open position or its own braking position. If the first connecting element is in the braking position, the vehicle is consequently secured against unintentional movement. Since the locking device provides a connection of the output shaft to the housing of the differential gear, this is thus independent of a selected gear shape and can also be provided both for differential gear on a front and on a rear axle. The locking device is therefore also independent of a drive form of the vehicle and therefore suitable for both front and / or rear wheel drives.

Preferably, the first connecting element is non-rotatably connected to the output shaft. This means that the first connecting element is fixed at least in the circumferential direction of the output shaft and allows transmission of torque from the output shaft to the connecting element. If the connecting element is moved into its braking position in which it is additionally connected in a rotationally fixed manner to the housing, then the output shaft is prevented from moving relative to the housing via the first connecting element.

Also preferably, the first connecting element is arranged in spite of its rotationally fixed connection with the output shaft in an axial direction of the output shaft displaceable thereto. This can be done by means of a positive connection, such as an axial longitudinal groove. Alternatively, however, the first connecting element can also be arranged rigidly on the output shaft by means of a positive, cohesive and / or frictional connection. In order to achieve the above-described mobility of the connecting element between an open position and a braking position despite the rigid connection, in this case, the connecting element is formed, for example to the extent necessary elastically deformable for movement between the open position and the braking position. Preferably, the at least one connecting element is rotationally symmetrical, wherein the connecting element extends substantially in the radial direction away from the output shaft. For example, the connecting element can thus be substantially disc-shaped, conical or cup-shaped and arranged coaxially on the output shaft. Also preferably, the described movement between the open position and the braking position takes place coaxially with the drive shaft.

According to a further embodiment, the locking device comprises a second connecting element, which is movable by means of the actuator between an open position and a braking position of the second connecting element. A differential carrier of the differential gear is rotatably connected to the housing by means of the second connecting element in its braking position.

Preferably, the second connection element is designed in accordance with the described first connection element, so that with regard to possible embodiments reference is made to the description given above. The second connecting element differs only in its arrangement and connects in the braking position the differential carrier with the housing of the differential gear, so that then no relative movement between these two components is possible. In conjunction with the output shaft which can be blocked by the first connecting element, a second output shaft of the differential gear can thus be prevented from rotating by the simultaneously blocked differential basket. A compound of the differential cage with the housing is to be understood such that it is designed either directly as a connection between the differential carrier and the housing or via the second connecting element as a link between the two components. It is also possible that the connection can be made indirectly via a connection of the second connecting element with the first connecting element, which is brought into connection with the housing. According to a further embodiment, the second connecting element can be non-rotatably connected to the differential carrier. The connection of the two components may be formed according to the above-described rotationally fixed connection of the first connecting element with the output shaft and thus be correspondingly rigid or slidably connected in the axial direction. With regard to possible embodiments, reference is therefore also made to the above description. Preferably, the first and the second connecting element are arranged coaxially one behind the other on the output shaft and in the axial direction to each other.

Furthermore, the actuator may comprise an electric drive and / or a hydraulic drive. Preferably, as an electric drive, an actuator with an electric motor, such as a servomotor or a servomotor, is used, which provides a corresponding application of the one or more connecting elements (s) to effect a corresponding movement of the at least one connecting element. For this purpose, the actuator may for example comprise a linear drive, which is arranged such that this allows an axial movement of the at least one connecting element. Alternatively or additionally, the actuator can be actuated hydraulically by means of a hydraulic drive.

Preferably, the actuator also comprises an axially movable in an axial direction of the output shaft axial nut for moving the at least one connecting element between the respective open position and the respective braking position. This means that the driven actuator comprises a displaceable axial nut, which is operatively coupled to the at least one connecting element to move it.

Preferably, the axial nut, the first and the second connecting element are arranged coaxially in series on the output shaft, so that a displacement of the axial nut, a displacement of the second connecting element and its movement in turn causes a displacement of the first connecting element. Of course, another sequence is possible as well.

Preferably, the displaceable axial nut is displaceable in the axial direction by means of a ball screw. A ball screw is a possible embodiment of the linear drive described above and allows a smooth and simple relative movement of the components connected thereto, so that the axial nut described by the corresponding drive axially between its open position and its braking position is displaced.

According to a further embodiment, the at least one connecting element each comprises a friction lining for providing a rotationally fixed connection by means of a frictional connection. Thus, a rotationally fixed connection to a component acted upon thereby, for example the housing, can be provided via the friction lining in order to fix the connecting element or the output shaft or the differential carrier relative thereto.

According to another embodiment, the at least one connecting element in each case comprises positive connection means for providing a rotationally fixed connection by means of a positive connection. Thus, a fixation of the output shaft and the differential cage can be achieved relative to the transmission housing also. For this purpose, the at least one connecting element engages by means of the positive connection means, for example, in correspondingly configured portions of the transmission housing. The positive connection may be provided in addition to the frictional connection and additionally increase a maximum holding force of the frictional connection. According to a further embodiment, the locking device may be wet or dry.

In addition, the actuator may comprise a number of carriers for releasing the at least one connecting element from its respective braking position. The drivers are for example provided to release a connection element located in connection with another component, for example the transmission housing, and thus to release a rotationally fixed connection therewith. Preferably, the at least one connecting element can be moved by means of the driver from the braking position back into the released position. For this purpose, the drivers can be operatively coupled or connected to the displaceable axial nut, so that they follow the movement of the axial nut.

Furthermore, a differential with at least one locking device is proposed, wherein the locking device is designed according to the given description. Here is an output shaft of the

Differential gear by means of the first connecting element of the at least one connecting element in the braking position rotatably connected to a housing of the differential gear.

According to a further embodiment, the differential comprises a plurality of output shafts, each output shaft is associated with a respective locking device. This allows a particularly simple embodiment of the individual locking devices, since they only require a connecting element for connecting the respective output shaft to the transmission housing. In this way, each output shaft is blocked directly by the associated locking device and secured the vehicle as soon as the locking devices are in each case in the actuated state. An additional connection of the differential carrier with the gear housing for blocking the other drive shafts is no longer necessary in this case. An embodiment of the invention is illustrated in the drawing and will be explained in more detail below. It shows:

1 is a schematic representation of a differential gear with a locking device according to the invention,

Fig. A sectional side view of an inventive

Locking device in the installed state and

3 is a sectional perspective view of the locking device according to the invention in the installed state of FIG. 2nd

Fig. 1 shows a schematic representation of a differential gear 10 with a locking device 15 according to the invention. The differential 10 includes a drive shaft 11 and two output shafts 12a and 12b, which are operatively coupled to each other via a arranged in a differential carrier 14 differential gear. The differential 10 thus corresponds to a conventional and well-known differential gear, so that no explanation is given to its construction and operation. The additionally provided locking device 15 is arranged in the illustrated embodiment on the output side in the region of an output shaft 12b on the transmission housing 13 or integrated into this and includes an actuator for actuating the locking device. The actuator comprises an electric motor as electric drive 16, which drives an axial nut 19 via a linear drive which comprises a gear stage 17 and a ball screw 18 operatively coupled thereto. This is arranged coaxially with the output shaft 12b and in the axial extension direction between an open position (shown in Figure 1) and a braking position (not shown) displaceable. The displaceable axial nut 19 is displaced in the direction of the second connecting element 20 during a displacement in the braking position in order to act on this. The second connection The transmission element 20 is rotatably and axially displaceably connected to the differential carrier 14. If the displaceable axial nut 19 continues in the

displaced described axial direction, it presses the second connecting element 20 against a first connecting element 21 which is rotatably and axially slidably connected to the output shaft 12b. If the first connecting element 21 is now likewise acted upon indirectly by the axial nut 19 via the second connecting element 20, then the first connecting element 21 is pressed against a wall section 22 of the differential housing 10. The first and the second connecting element 20, 21 each have a pot shape or a conical shape in the illustrated embodiment, wherein in each case a friction lining 20a, 21a is arranged in the region of an outer edge of each connecting element, which is used to improve a friction fit or a mutual frictional connection is used.

In the braking position (not shown) of the axial screw 19 this acts directly on the second connecting element 20 and indirectly via this the first connecting element 21, which in turn is pressed against a portion 9 of the gear housing. As a result, both the differential carrier 14 and the output shaft 12b are thus frictionally connected to the housing of the differential gear 10. This causes not only the output shaft 12b but also an opposite second output shaft 12a (not shown) to be locked. This thus makes it possible to park and secure the vehicle on a ground with different characteristics for the respective wheel, a so-called μ-split.

As shown in Fig. 1, it is possible to arrange the locking device 15 inside the differential gear 10. The locking device is thus part of the differential gear and therefore represents a completely encapsulated arrangement which requires only one lead for controlling the drive. Moreover, the arrangement offers the advantage that its moving components are protected against environmental influences. In addition, the encapsulated arrangement provides improved theft protection.

2 shows a sectional side view of an inventive

Locking device in the installed state, was waived on a representation of the complete differential gear. As already explained with reference to Fig. 1, the gear stage 170 is driven by the drive 160 (see Fig. 3) and rotated relative to the gear housing 130. By means of the ball screw 240, an axial longitudinal displacement of the axial nut 190 takes place in the axial direction of the output shaft 120b. This acts on the second connecting element 200 directly, so that it is also displaced in the axial direction against the first connecting element 210. Consequently, the first connecting element 210 is indirectly pressed by the axial nut 190 in the axial direction against the wall section 220 of the gear housing 130. In the braking position, the axial nut 190 presses or braces the second connecting element 200 against the first connecting element 210, which in turn is pressed against the wall section 220 and thus frictionally blocks the output shaft 120b and the differential carrier 140 against a respective rotational movement. For this purpose, the first and the second connecting element as described rotatably and slidably to be arranged on the differential carrier 140 and on the output shaft 120 b.

In Fig. 3 is a sectional perspective view of the locking device in the installed state shown in FIG. 2, so that reference is made to the above description. In addition, an exemplary arrangement of a designed as an electric motor drive 160 for the rotary drive of the gear stage 170 is shown. Alternatively (not shown) may also be provided a hydraulic drive for providing the rotational movement of the gear stage 170 or for providing the axial linear movement of the axial nut 190. LIST OF REFERENCE NUMBERS

10 differential

11 drive shaft

12a output shaft

12b output shaft

13 gearbox housing

14 differential carrier

15 locking device

16 drive

17 gear stage

18 ball screw

19 Axial nut

20 second connecting element 20a friction lining

21 first connecting element 21a friction lining

22 wall section

120b output shaft

130 gearbox

140 differential carrier

150 locking device

160 drive

170 gear stage

190 Axial nut

200 second connecting element

210 first connecting element

220 wall section

230 drivers

240 ball screw

Claims

claims

1.) locking device for a differential (10), with

an actuator (16, 17, 18, 19) and

at least one connecting element (20, 2),

wherein the at least one connecting element (20, 21) is movable between a respective open position and a respective braking position by means of the actuator (16, 17, 18, 19) and an output shaft (12b) of the differential gear (10) is connected by means of a first connecting element (21 ) of the at least one connecting element (20,21) in its associated braking position rotatably connected to a housing (3) of the differential gear (10) is connectable.

2.) locking device according to claim 1, wherein the first connecting element (21) rotatably connected to the output shaft (12b) is connected.

3.) Locking device according to claim 1 or 2, wherein the locking device (15) comprises a second connecting element (20) which by means of the actuator (16, 17,18,19) between an open position and a braking position of the second connecting element (20). is movable, wherein a differential carrier (14) of the differential gear (10) by means of the second connecting element (20) in its braking position rotatably connected to the housing (13) is connectable.

4.) locking device according to claim 3, wherein the second connecting element (20) rotatably connected to the differential carrier (14) is connected.

5.) locking device according to one of claims 1 to 4, wherein the

Actuator (16, 17, 18, 19) comprises an electric drive (16) and / or a hydraulic drive.

6.) locking device according to one of claims 1 to 5, wherein the

Actuator (16, 17, 18, 19) also comprises an axial nut (19) displaceable in an axial direction of the output shaft (12b) for moving the at least one connecting element (20, 21) between the respective open position and the respective braking position.

7.) Locking device according to claim 6, wherein the displaceable axial nut (19) by means of a ball screw (18) is displaceable in the axial direction.

8.) locking device according to one of claims 1 to 7, wherein the at least one connecting element (20,21) each comprise a friction lining (20a, 21a) for providing a rotationally fixed connection by means of a frictional connection.

9.) Locking device according to one of claims 1 to 8, wherein the at least one connecting element (20,21) each comprise positive connection means for providing a rotationally fixed connection by means of a positive connection.

10.) locking device according to one of claims 1 to 9, wherein the

Actuator (16, 17, 18, 19) comprises a number of drivers (230) for releasing the at least one connecting element (20, 21, 200, 210) from its respective braking position. Differential with at least one locking device, wherein the locking device (15) is designed according to one of claims 1 to 10, and wherein an output shaft (12b) of the differential gear (10) by means of the first connecting element (21) of the at least one connecting element (20,21) in the braking position rotatably connected to a housing (13) of the differential gear (10).

A differential according to claim 11, wherein the differential (10) comprises a plurality of output shafts (12a, 12b) and each output shaft (12a, 12b) is associated with a respective locking device (15).