DE3707106A1 - Self-locking differential - Google Patents

Abstract

The invention relates to a self-locking differential 1, which is designed especially as a bevel gear differential and is intended for motor vehicles. The locking action can be obtained by way of a fluid friction clutch 9. The fluid friction clutch can be activated in the event of a speed differential occurring, but can also be shifted by way of a clutch into a position in which no torque transmission can occur. The transmission 1 then acts as an entirely normal differential. <IMAGE>

Description

The invention relates to an automatically locking Differential gear, in particular bevel gear compensation gearbox, for motor vehicles, consisting of one driven and rotatably mounted in a housing Differential cage, in the differential cage coaxially these driven bevel gears, which have at least one in the differential cage on an axis perpendicular to the The axis of rotation of the differential carrier is rotatable mounted differential bevel gear with each other exist, as well as a fluid friction clutch two sets of alternately arranged couplings slats, each with one on the differential Movement participating part are connected.

Starting from such a solution, it is known that second set of clutch plates rotatably with one an output bevel gear connected to the output shaft connect. With relative movement builds up in the liquid keitsreibkupplung a reaction torque, so that the Output shaft is taken.

A disadvantage of these known designs is that the fluid friction clutch regardless of how  a speed difference arises when a occurs such passes to the torque transmission position. This is, however, if the vehicle that with such automatically locking differential gear is, in addition, an automatic anti-lock device has disadvantageous.

Furthermore, also in the event that the fluid friction clutch is used to the not constantly driven wheels of the normally trailed axle of the Switching on the vehicle disadvantageous that when braking gear the wheels z. B. the normally not driven The rear axle can also be locked could cause the vehicle to break out can.

Based on this, the present invention is the Task based on that the automatically locking Differ ential gear so that none mutual negative influence of liquid friction clutch to lock the differential gear and an automatic anti-lock device or otherwise is given when braking the motor vehicle.

This object is achieved according to the invention in that the second set of clutch plates rotatably with the on Output bevel gear connected output shaft via a Clutch is connectable.

Via the clutch, the effect of the liquid friction clutch can be switched on or off. Through the Switching function becomes a mutual influence possibility of fluid friction clutch and automatic  anti-lock brake or a negative influence on the behavior of the vehicle when braking avoided.

It is preferably provided that the clutch at Actuation of the service brake of the motor vehicle Relative movement of the output shaft and the second set of Allowing clutch plates and otherwise a non-rotating Connection via a frictional connection between the two effecting or automatically in such a Relative movement is formed.

Because of such a design, the clutch is normally in the torque transmission position, so that a direct response to a relative movement too is executable. The same effect is achieved when the clutch, for example, in an off however, ready for torque Transfer position is and with relative movement automatically into the torque transmission position is transferable.

According to a further feature of the invention Clutch provided that consists of a with a Driver flange provided and with the second set Clutch plates rotatably connected driving sleeve, one rotatably connected to the output shaft and also there is a flange hub, the Driver flange with the flange of the push-on hub Locking balls, which rest in non-rotating connection held by a switching ring or automatically in this are transferable and those for lifting the non-rotating Connection from the rest areas of one of the flanges except Intervention in a disengagement position can be transferred.  

The flange of the push-on hub is preferably axial running, circumferentially distributed through holes provided, in which the locking balls are axially movable are included. Their diameter is larger dimensioned as the thickness of the flange. You attack in indented state on the one hand in accordingly circumferentially distributed spherical caps of the driving flange and on the other hand are against a radial surface of the Switch rings supported. They are in the disengaged state Through holes and thus the locking balls Rotation of the switching ring in a matching position with recesses provided in the switching ring, so that they can dodge into it.

It is provided that the switching ring compared to the Flange of the hub is limited relatively rotatable.

For returning the switching ring or for holding the same in the engaged position is the switching ring against the flange via effective in the circumferential direction Supported spring means.

For turning the switching ring into the starting position and to hold it in this position is one Brake provided. For example, it can be a act as a non-contact brake.

The relative movements of the flange are limited in a further embodiment with a pin that the flange is assigned and in an over an arch in the switching ring. engaging extending groove. The on and off switching function in the two possible directions of rotation further achieved according to the invention in that Resting point in the driver flange in both turning or  Circumferential directions, evenly, but in opposite directions circumferentially offset, two recesses in the switching ring featured are seen.

A slotted approximately is preferably used as the spring means held concentrically to the flange of the push-on hub Ring spring provided with bent ends. Their ends lie on the stop when the clutch is engaged areas of attacks of the same circumference on Flange of the push-on hub and on the switching ring. The Ring spring is also between the radial surface guided by the driver flange and switching ring.

A preferred embodiment according to the invention of the shown schematically in the drawing.

It shows:

Fig. 1 is a half of an auto-lock the differential gear according to the invention is schematic diagram,

Fig. 2 is a more detailed illustration of the clutch in section,

Fig. 3 is a section AA of Fig. 2,

Fig. 4 shows a detail of the clutch in a simplified form in the developed state, with a locking ball located in the torque transmission position and

Fig. 5 shows the detail corresponding to Fig. 4 with the locking ball in the disengaged state.

The differential gear 1 has a housing 3 . The differential carrier 2 is rotatably mounted in the housing 3 . The storage takes place via the warehouse 39 . The differential piston 2 has a ring gear 7 mounted on its outside coaxially with its axis of rotation 6 . This ring gear 7 is driven by a drive bevel gear 41, for example, from the engine of the vehicle via the transmission and the connected drive shafts. The axis of rotation 5 for differential bevel gears 8 is perpendicular to the axis of rotation 6 of the differential cage 2 . The driven bevel gear 4 is rotatably arranged coaxially with the axis of rotation 6 of the differential cage 2 in the differential cage. Another output bevel gear 4 is attached in mirror image to the axis of rotation 5 of the differential bevel gear. The output bevel gears 4 mesh with the differential bevel gears 8 . With the driven bevel gear 4 shown in the drawing figure 1 , the push-on hub 17 is connected in a rotationally fixed manner. The driving sleeve 15 is arranged coaxially to the push-on hub 17 and can be moved relative thereto. The bearing 39 is arranged on the outer surface of the driving sleeve 15 on the one hand and on the other hand with its other bearing ring in the housing 3 . The fluid friction clutch 9 has two clutch plate sets 10 and 11 . The first set of clutch plates 10 is rotatably connected to the differential carrier 2 . The connection takes place via a toothing attached to the outer contour of the lamellae 10 , which are received in corresponding toothing of the housing, which extend axially to the axis of rotation 6 . The second set of fins 11 is non-rotatably engaged with a corresponding outer toothed inner sleeve 42 via a toothed bore. The output bevel gear 4 to the side directed towards the fluid friction clutch 9 is closed by a cap 42 and a seal abge. On the side facing away from the driven bevel gear 4 , the interior of the fluid friction clutch 9 is delimited by a cover of the differential carrier 2 itself. The two clutch plates 10 and 11 are each arranged alternately in the axial direction. The remaining cavity of the fluid friction clutch 9 is filled with a viscous fluid. When the two clutch plates 10 and 11 move relative to one another, a shear effect occurs in the liquid and a torque can be transmitted between the two sets of plates. The inner sleeve 37 of the fluid friction clutch 9 is connected in terms of torque to the clutch 13 via a drive sleeve 15 inserted into its cavity. A seal 38 is arranged between the outer surface of the driving sleeve 15 and the receiving bore through which the driving sleeve is led out of the housing 3 . In the area of the clutch 13 , the driver sleeve 15 is provided with a flange-like enlargement in the form of the driver flange 14 . The push-on hub 17 is also provided with a flange 16 , which axially adjoins the driving flange 14 . Furthermore, the push-on hub 17 has an extension 43 with a cylindrical outer surface. A switching ring 19 is rotatably mounted on this cylindrical outer surface of the extension 43 . The push-on hub 17 has a bore with a toothing into which the output shaft 12 or, for example, a pin of an output joint can be inserted. The shaft 12 is then optionally connected to a wheel of a vehicle with the interposition of a constant velocity universal joint shaft. Driving bottle 14 and flange 16 are connected in terms of torque via locking balls 18 arranged around the circumference. This torque connection can be generated or canceled by the switching ring 19 .

The function of the clutch is explained with reference to FIGS. 2 to 5.

In the event that there are different friction conditions on the wheels of an axle of the vehicle and, for example, the vehicle wheel driven by the output bevel gear 4, not shown, is on a surface with an adhesion coefficient that is substantially less than that associated with the output shaft 12 Rades, a vehicle with a normal differential can no longer move. The vehicle wheel connected to the output shaft 12 is stationary because of the compensating effect of the differential gear. In this case, there is also a relative movement between the clutch plates 10 , which are assigned to the differential carrier 2 and are moved on, and the plates 11 , which are assigned to the output shaft 12 . During this differential movement, a torque builds up in the fluid friction clutch 9 and the clutch plates 11 are moved. Since the clutch plates 11 are non-rotatably connected to the inner sleeve 37 and this is connected to the driving sleeve 14 , the driving flange 14 also moves.

The driving flange 14 is in a rotationally fixed connection via the locking balls 18 with the flange 16 of the push-on hub 17 and transmits the torque to the output shaft 12 . The corresponding vehicle wheel is also driven due to the torque connection.

In certain driving conditions, for example when braking, in particular if the vehicle is provided with an automatic anti-lock device, it is desirable that, despite a relative movement between the slats 10 and 11, no torque is transferred to the output shaft 12 . To achieve this, the clutch 13 can be moved into an engaged position and a disengaged position, wherein in the disengaged position, no torque is transmitted from the fluid friction clutch 9 to the output shaft 12 . The function of the clutch 13 results from FIGS. 2 to 5. As can be seen from FIG. 2, the flange 16 has through holes 20 distributed around the circumference. In the through holes 20 , the locking balls 18 are taken up. The axial extent or thickness of the flange 16 and the size of the bores 20 and the locking ball 18 are coordinated with one another in such a way that the diameter of the locking balls 18 is greater than the axial extent of the flange 16 . The driving flange 14 is provided with a radial surface 36 . With this, it bears against a corresponding radial surface 44 of the flange 16 . Push-on hub 17 and driving sleeve 15 are rotatable relative to one another, but are fixed in the axial direction. The flange 16 is provided with a plurality of circumferentially distributed bores 20 and locking balls 18 . Four such bores 20 with locking balls 18 are preferably provided. The driving flange 14 is provided with spherical caps 21 distributed according to the bores 20 , which are designed as locking points for the locking balls 18 . There are also four such spherical caps 21 in a circumferential distribution and arrangement corresponding to the bores 20 . The spherical caps 21 are adapted to the ball surface of the locking balls 18 . Its depth starting from the radial surface 36 is such that the locking balls 18 are flush with the other flat surface 45 of the flange 16 , ie do not protrude. The switching ring 19 rests with its radial surface 22 against the flat surface 45 of the flange 16 . The switching ring 19 can be rotated with a bore on the extension 43 of the push-on hub and can be rotated to a limited extent, as will be explained below. As can be seen from FIGS . 4 and 5, the switching ring 19, the locking ball 18 has two escape recesses 23 . In the case of the torque transmission position, that is the position shown in FIGS . 2 and 4, these Ausweichaus recesses 23 are arranged offset right and left with the same circumferential distance to the associated spherical cap 21 in the driving flange 14 . For each spherical cap 21 , two alternative recesses 23 are arranged in the switching ring 19 . Switch ring 19 and flange 16 are supported opposite one another in the circumferential direction by an annular spring 27 . The ring spring has two bent ends 28 and 29 . In its ring part, the ring spring 27 is arranged on the outer circumference of the flange 16 . The flange 16 has a flange 35 that extends radially. The stop 35 has two stop surfaces 31 and 33 , the bent end 29 of the ring spring 27 coming into contact with the stop surface 33 at least temporarily and the other end 28 of the ring spring 27 coming into contact with the stop surface 31 . The switching ring 19 is also provided with a stop 34 which axially covers the flange 16 and is formed in the circumferential direction in accordance with the extent of the stop 35 of the flange 16 . The stop 34 of the switching ring 19 is also provided with two stop surfaces 30 and 32 , the end 33 of the ring spring 27 resting against the stop surface 32 and the end 28 of the ring spring 27 against the stop surface 30 . In the torque transmission position, the annular spring 27 holds the switching ring 19 and the flange 16 in the corresponding circumferential position of the stops 34 and 35 shown in FIG. 3. The corresponding position of the two parts relative to one another can also be seen from FIG. 4. For reasons of simplification, the annular spring 27 is shown as a tension spring. From this it can be seen that the preferred position is the torque transmission position, in which the locking ball 18 is located between the two escape recesses 23 in the circumferential direction. It is supported on the one hand against the radial surface 22 of the switching ring 19 and on the other hand in the spherical cap 21 of the driving flange 14 . In this position there is a torque connection between the slave flange 14 and the flange 16 and thus to the output shaft 12 . The rotational movement of the switching ring 19 and flange 16 relative to one another is limited. For this purpose, a pin 25 extending axially from its flat surface 45 is provided in the flange 17 .

As can be seen from FIG. 3, the pin 25 is located between two bores 20 . An arcuate groove 26 is arranged in the radial surface 22 opposite the flat surface 45 . The pin 25 engages in the groove 26 . In the torque transmission position, ie in the position shown in FIGS . 2 to 4, the pin 25 is in a central position in relation to the circumferential extent of the groove 26 . The circumferential extent of the groove 26 and thus the possibility of relative movement of the switching ring 19 to the flange 16 corresponds to the circumferential circumferential offset of the escape recesses 23 in the switching ring 19 to the spherical cap 21 in the torque transmission position. In the case of relative adjustment of the switching ring 19, for example from the position shown in FIG. 3 to the left, ie counterclockwise, when the escape recesses 23 are in the same position as the through-hole 20 , the blocking ball 18 is able to move into the escape recesses. The driving flange 14 can then be moved freely with its radial surface 36 past the through hole 18 . The torque connection of the driver flange 14 and flange 16 and thus the fluid friction clutch 9 to the output shaft 12 is interrupted.

The disengaged position is shown in Fig. 5. In this position, differential gear 1 behaves like a differential without a locking function and is only subject to internal friction. From Fig. 5 it can be seen that the annular spring 27 is tensioned. The end 29 of the ring spring 27 is lifted in this state by abutment against the stop surface 33 of the stop 35 clockwise from the stop surface 32 of the stop 34 . Conversely, the stop surface 31 lifts off the end 28 . This lifting takes place by braking the switching ring 19 , which normally rotates with the flange 16 in the position shown in FIG. 4. If the end position is reached by striking the pin 15 at the end of the groove 26 , it remains in this position as long as the brake 24 exerts a braking force on the switching ring 19 . The switching ring 19 thus rotates with the flange 16 , but in an angularly rotated position to that according to FIGS. 2 to 4. It therefore assumes a position, for example according to FIG. 5. The application of a braking force can be triggered, for example, by operating the brake. For this purpose, for example, the brake can be activated by the vehicle's brake light switch. In the switched-off position, due to the torque interruption, there can also be no negative influence or mutual interference between the fluid friction clutch 9 and an automatic anti-lock device. The brake 24 for the control ring 19 can be, for example, shoe brakes, but also eddy current brakes or hydraulically actuated brakes.

In addition, the switching ring 19 is held in its axial position relative to the flange 16 on the shoulder 43 by a locking ring 40 .

If the brake 24 is brought back into its inactive operating state, so that no force retaining the switching ring is effective in the circumferential direction, the case can occur that the clutch remains in the switched-off position over a longer distance. However, this is without harmful consequences, since immediately when a differential effect occurs, that is to say a speed difference between the driving flange 14 and the flange 16 and the resultant passing of the spherical caps 21 on the locking balls 18 , these are pushed back into the switch-on position by the force of the annular spring 27 are, ie the switching ring is returned to the position shown in FIGS. 2 to 4.

In addition to using the brake light switch to trigger the switching function, i.e. activating the brake 24 , it is also possible to derive the switch-off function from the position of the accelerator pedal and to attach a switch contact such that the clutch 13 is already in the idle position of the accelerator pedal in the position shown in FIG. 5 position is transferred by activating the brake 24 . When the accelerator pedal is actuated, the brake 24 is immediately released again and the clutch 13 is brought into the switched-on position or into a standby position for switching on again.

• 1 differential gear
  2 differential cages
  3 housing
  4 output bevel gear
  5 axis differential bevel gear
  6 rotary axis differential cage
  7 ring gear
  8 differential bevel gear
  9 Fluid friction clutch
  10 clutch plates of the differential cage
  11 clutch plates of the inner sleeve
  12 output shaft
  13 clutch
  14 drive flange
  15 drive sleeve
  16 Flange of the push-on hub
  17 push-on hub
  18 locking ball
  19 switching ring
  20 through holes
  21 spherical caps
  22 Radial surface switching ring
  23 alternative recesses in the switching ring
  24 brake
  25 pen
  26 groove
  27 ring spring
  28, 29 bent ends of the ring spring
  30 b - 33 contact surfaces
  34 Stop switching ring
  35 Stop hub
  36 radial surface of the driving flange
  37 inner sleeve
  38 seals
  39 bearings
  40 circlip
  41 drive bevel gear
  42 sealing cover
  43 approach
  44 radial surface
  45 flat surface

Claims (11)

1. Automatically locking differential gear, in particular bevel differential, for motor vehicles, consisting of a driven and rotatably mounted in a housing differential cage, in the differential cage axially coaxial with this output gearbox, which has at least one in the differential cage on an axis perpendicular to the axis of rotation of the differential cage, rotatably mounted differential bevel gear are in engagement with one another, such as a fluid friction clutch with two sets of alternately arranged clutch plates, each of which is connected to a part participating in the differential movement, characterized in that the second set of clutch plates ( 11 ) rotatably with the output shaft ( 12 ) connected to an output bevel gear ( 4 ) can be connected via a clutch ( 13 ). 2. Differential gear according to claim 1, characterized in that the clutch ( 13 ) when actuating the Be service brake of the motor vehicle a Relativbewe supply of output shaft ( 12 ) and the second set of clutch plates ( 11 ) permitting and otherwise causing a force fit between the two or this is automatically designed to convert into such with relative movement. 3. Differential gear according to claim 1 or 2, characterized in that the clutch ( 13 ) from a with a slave flange ( 14 ) and with the second set of clutch plates ( 11 ) rotatably connected driver sleeve ( 15 ), one with the output shaft ( 12 ) non-rotatably connected and having a flange ( 16 ) on the plug-in hub ( 14 ), the driver flange ( 14 ) with the flange ( 16 ) of the plug-on hub ( 17 ) via locking balls ( 18 ) which are arranged in locking points ( 21 ) for rotation Connection held by a switching ring ( 19 ) or can be automatically transferred into this and to remove the rotationally fixed connection from the locking points ( 21 ) one of the flanges ( 14 ) except a handle can be transferred to a disengaged position. 4. Differential gear according to claim 3, characterized in that the flange ( 16 ) of the plug-on hub ( 17 ) is provided with axially extending circumferentially distributed through holes ( 20 ) in which locking balls ( 18 ) are axially movably received, which are larger in diameter, as the thickness of the flange ( 16 ) and in the engaged state on the one hand engage in correspondingly circumferentially distributed spherical caps ( 21 ) of the driver flange ( 14 ) and on the other hand are supported against a radial surface ( 22 ) of the switching ring ( 19 ) and in the disengaged state in one with the Through the bores ( 20 ) and the locking balls ( 18 ) in a matching position by twisting and durable escape recesses ( 23 ) are partially movable. 5. Differential gear according to claim 3, characterized in that the switching ring ( 19 ) relative to the flange ( 16 ) of the push-on hub ( 17 ) is relatively rotatable to a limited extent. 6. Differential gear according to claim 3, characterized in that the switching ring ( 19 ) with respect to the flange ( 16 ) via spring means ( 27 ) which is effective in the circumferential direction is held in the engaged position or can be transferred into this. 7. Differential gear according to claim 3, characterized in that the switching ring ( 19 ) via a brake ( 24 ) can be rotated into the disengaged position and in this a rotation together with the push-on hub ( 17 ) is permitted. 8. Differential gear according to claim 5, characterized in that to limit the relative movement of the flange ( 16 ) with a pin ( 25 ) engages in an arc extending groove ( 26 ) in the switching ring ( 19 ). 9. Differential gear according to claims 3 and 5, characterized in that each locking point ( 21 ) in the driving flange ( 14 ) in both directions of rotation evenly, but ent opposite circumferentially offset two alternative recesses ( 23 ) are provided in the switching ring ( 19 ). 10. Differential gear according to claim 6, characterized in that a slotted, approximately conically to the flange ( 16 ) of the plug-on hub ( 17 ) held annular spring ( 27 ) with bent ends ( 28 , 29 ) is provided as spring means, and that the ends ( 28 , 29 ) in the engaged state of the coupling on stop faces ( 30 , 31 , 32 , 33 ) of stops ( 34 , 35 ) of the same extent on the flange ( 16 ) of the push-on hub ( 17 ) and on the shift ring ( 19 ). 11. Differential gear according to claim 10, characterized in that the annular spring ( 27 ) is additionally guided between the radial surface ( 36 ) of the driving flange ( 14 ) and the radial surface ( 22 ) of the switching ring ( 19 ).