FR2574885A1 - ADJUSTING DEVICE FOR DISC BRAKE - Google Patents

Abstract

ADJUSTING DEVICE FOR DISC BRAKES, IN PARTICULAR FOR MOTOR VEHICLES, INCLUDING A PUSH ELEMENT ADJUSTABLE IN LENGTH INCLUDING AN ADJUSTING SPINDLE AND AN ADJUSTING NUT COOPERATING TOGETHER THROUGH A SELF-ROTATING THREAD, A , A DEVICE ALLOWING TO TRANSFORM A ROTATIONAL MOVEMENT INTO AN AXIAL MOVEMENT, AN AXIAL MOVEMENT PART OF THE SAID DEVICE ACTING ON THIS LENGTH-ADJUSTABLE PUSH ELEMENT TO BRING IT AXIALLY IN SUPPORT AGAINST A BRAKE ACTUATION ELEMENT, '' ROTARY DRIVE COOPERATING WITH ITS ACTUATION ELEMENT VIA A DEAD STROKE COUPLING DEVICE, AND A UNIDIRECTIONAL COUPLING DEVICE, IN PARTICULAR A FREE-WHEEL COUPLING DEVICE, ALLOWING THE ROTATION OF TRANSMISSION DRIVING DEVICE TO THE DUDIT MOBILE PART PUSH ELEMENT, CHARACTERIZED IN THAT BETWEEN THESE UNIDIRECTI COUPLING DEVICE ONNEL 52 AND THESE PUSH ELEMENT 23 IS PROVIDED FOR A FRICTION COUPLING DEVICE 57 WHICH TRANSMITS TORQUES, UP TO A DEFINED VALUE, AUDIT PUSH ELEMENT 23, AND WHICH, BEYOND THIS TORQUE VALUE, IS INOPERABLE.

Description

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  The present invention relates to an adjustment device for a disc brake, in particular for a motor vehicle, comprising a thrust element adjustable in length comprising an adjustment pin and an adjustment nut cooperating together by means of a self-locking thread, a rotary actuator, a provision

  to transform a rotational movement into a movement

  axially, a part with axial movement of this device acting on the thrust element adjustable in length to bring it axially in

  support against a brake actuating element, a device for

  rotary drag cooperating with the actuating element by the

  through a dead travel coupling device, and a

  unidirectional coupling device, in particular a device

  freewheel coupling, allowing the rotation to be transmitted

  tion of the drive device to the moving part of the element

thrust.

  An adjustment device of this type, allowing the compensation

  automatic play due to wear of the brake linings, is de-

  Crit in German patent application no. 2.507.012. In this dispo-

  If there is, there is provided, inside a boot forming part of a brake caliper, a two-part sleeve designed in the form of a cylindrical helical sleeve and housed in a bore of the

  bootmaker. One of the parts of the bushing is fixed to the boot

  of an anchor bolt placed in a rear wall of the case and the second part of the sleeve is adjustable in the axial direction by

  compared to the first one due to the helical configuration com-

  of the two ends facing the two parts of the socket. A two-piece roller bearing is provided between the two parts of the sleeve. A radially extending heel

  of the adjustable socket part crosses the side wall of the box

  tier. The head heel is connected to an actuating device via a linkage link. By moving the head heel in the circumferential direction, the adjustable bushing part can be rotated relative to the other bushing part and, due to

  the helical configuration of the ends facing each other

  sleeve ties, it is itself adjusted axially on and

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  relative to the fixed bushing part, which allows the brake linings to be applied against the opposite front faces of a disc

  of brake. For this purpose, the front end of the bushing part

  glable acts, by means of a roller bearing, on a set of thrust element comprising two parts (spindle of

  setting and adjusting nut) placed on the same axis. The pin of re-

  glage is screwed into the adjusting nut and, being immobilized in rotation, it can push a brake lining against a disc

of brake.

  The known device also comprises a socket of com-

  which is placed between the two-part socket and the nut

  adjustment and which is connected to it by means of a device

  unidirectional coupling device. In an extreme radial flange

  of the control element are provided axially oriented notches

  between which spaces are provided in the circumferential direction

  profitable. A drive element fixed to the rotating bush part.

  tive is housed in one of these notches. If, when the brake is actuated, the rotation of the bushing part is not sufficient for the drive element to travel through the entire

  adjustment stroke permitted by a notch, there is no

  glage. However, when the friction linings are worn, the

  the drive element is applied against one side of the notch and, by means of the unidirectional coupling device, rotates the control element relative to the external part of the element assembly thrust. When the brake is released, the

  return spring provided in the actuating device causes the e-

  drive element against the other side of the notch and turns

  the control element with the external part of the

  push element. This rotation results in an extension of the effective length of the thrust element assembly because the adjustment spindle is immobilized in the axial direction, since it is,

  for example, pressing against a brake lining.

  In this known device, it is necessary to provide a special device for returning the adjustment device to the initial position, this operation being essential, for example, to

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  change the brake linings. To this end, the control element,

  which is linked in rotation relative to the actuating element during -

  normal operation, slides axially, so that after a

  axial movement of the control element, the drive pin

  ment ensuring the rotational connection engages in a circumferential groove, which allows the control element to rotate relative to the actuating element. The adjusting nut can thus

  be turned in the return direction, which is impossible, depending on

  normal operation, due to the unidirectional coupling device

  the fact that the control element and the action element

  ment are linked in rotation to each other. Since the element

  slide axially against the force of a res-

  comes out, it is necessary to simultaneously apply an axial force and a rotational movement to recall the adjuster, this

  which makes the recall operation relatively complicated.

  The object of the present invention is therefore to provide a device

  adjustment type of the type indicated above, in which the operation

  back to the initial position is simplified. In addition, the

  adjustment according to the invention eliminates the influence-

  unfavorable elasticity of the stirrup part forming the bridge and the fittings. According to the present invention, this object is achieved in that between the unidirectional coupling device and the thrust element is provided a friction coupling device which transmits torques, up to a defined value, to the 'thrust element, and which, beyond this torque value, is inoperative. An adjustment device is thus obtained in which the rotational movement necessary for adjustment is transmitted in the direction of tightening, by means of a unidirectional coupling device.

  locked and a friction coupling device, to a fixed spindle

  so that the adjustment takes place while the brake is applied.

  During the establishment of the clamping force, there occurs in the thread of the pushing element a friction torque which exceeds

  that of the coupling device and under the effect of which the device

  friction coupling slip slides and does not continue to transmit

  be the induced rotational movement. The adjustment operation is therefore transposed into the range of application of the brake before the start of

  elongation, which prevents the adjustment of the elongation stroke.

  When the linings need to be changed, the threaded spindle can then be recalled simply by turning the adjusting spindle. In accordance with advantageous embodiments of the

  present invention, the coupling element of the coupling device

  friction friction can be designed as a cone of friction

  tion or may have a flat friction surface if the torques

  friction to be transmitted are reduced.

  Appropriately, a spring is provided, in particular

  tie a washer I spring 'Belleville', to apply the force

  coupling in the axial direction, this spring being designed to

  stain the necessary friction torque of the coupling device

friction.

  In an improvement of the present invention, a shaft is provided for transmitting the rotational movement of the element

  actuating the rotating part of the thrust element by the

  intermediate coupling devices, the adjusting pin being hollow and linked in rotation I this shaft with respect to which it can slide axially. Suitably, this tree can

  have a bearing portion on which a rotating sleeve rotates

  part of the drive system.

  To facilitate the transmission of the rotational movement of

  the actuating element to this socket, the latter comprises

  a flange portion which extends radially and in the

  what is a recess receiving an ankle, or a means

  equivalent, attached to the actuator. In loccurence, the di-

  mensions of this recess in the circumfirential direction are calculated so that the actuating element can rotate sufficiently

  so that the device ensuring the conversion of a rotational movement

  tion in an axial movement moves forward in accordance with the normal stroke of application and wear of the brake, without

  cause a rotation of the bushing nor therefore a repair operation

glage.

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  In accordance with the present invention, the delivery device

  freewheeling is placed on the bushing to obtain an agency-

very compact.

  In other embodiments of the invention, it is provided that the coupling piece is linked in rotation to the rotating piece of the pushing element. For this purpose, it is placed on

the tree appropriately.

  A cage surrounding the freewheel coupling device can be provided to immobilize the coupling element in the

axial direction.

  In another embodiment of the invention, the arrangements

  coupling devices are placed in a recess of the element

  actuation to obtain a design as short as possible.

  The various objects and characteristics of the invention are-

  will now be detailed in the description which follows, made to

  by way of nonlimiting example, referring to the appended figure.

  The one and only figure represents a longitudinal section of a part of a disc brake housing 1 in which is housed an actuating device provided with an adjustment device intended for a brake piston 2. The brake piston 2, designed as a pot, slides axially in an axial bore 3 of the brake shoe

  1, the bottom 4 of the brake piston 2 facing an intermediate element

  diary 5 against which it is applied. The intermediate element 5 is, for its part, applied against the rear plate 6 of a gasket

  brake 7, so that when the brake piston 2 slides axially,

  Lement, the brake lining 7 is also moved in the axial direction, by means of the intermediate element 5 to be pushed against

  a brake disc (not shown in the figure). When the garni-

  brake shoe 7 is applied against the brake disc, it pro-

  produces a reaction force which moves the brake shoe 1 in the opposite direction, a branch (not shown) of the brake shoe

  1 then pushing a brake lining (not shown in the fig-

  re), provided on the other side of the brake disc, against this other side

  brake disc. To avoid the intrusion of dirt into the

  sage 3, a protective cap-8 is provided which is housed in

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  grooves in the brake shoe 1 and the brake piston 2.

  In the brake shoe 1 is screwed a pin 9 which extends radially in an axial recess 10 of the brake piston 2,

  the latter being thus linked in rotation with the brake shoe 1.

  To actuate the brake, an actuating element 12 is mounted rotating in a bore 11 of the end of the brake shoe

  1. The actuating element 12 comprises a portion of cy-

  lindrique 13 and an actuation lever 14. This portion of roller

  cylindrical ment 13 passes through bore 11 and ends in bore 3

  o its front face is applied against a device 15 serving to con-

  vertise the rotational movement of the actuating element 12 in an axial movement. In this case, this device 15 consists of a

  roller ramp comprising two ramp parts 16, 17 between the

  which are placed rollers 18. The ramp part 16 making

  this to the actuating element 12 is linked in rotation thereto to the

  screw means 19, which means that any movement of ro-

  tation of this actuating element 12 directly causes a rotation

  of the ramp piece 16. The other ramp piece 17 is immobilized

  rotated by the pin 9 which engages in a corresponding recess 20 of this ramp piece 17. This recess 20 is oriented axially, so that the ramp piece 17 can perform an axial movement, but not rotary. A roller bearing 22 is

  housed between the bottom 21 of the bore 3 and the rail part 16.

  By means of its ramp part 17, this roller ramp 15 acts on a thrust element 23 which is adjustable in

  length and which consists of an adjusting nut 24 and a pin

  adjustment che 25 which cooperate together by means of a

  self-locking let 26. The adjusting nut 24 includes a portion of

  axially extending rod 27 and a portion of flange extending radially

  dialing 28. The adjustment pin 25 also comprises an axial rod portion 29 and a radial flange portion 30. These flange portions 28, 30 of the adjustment nut and of the adjustment pin are turned towards the bottom 4 of the brake piston 2. The front face 31 of the flange portion 30 of the adjustment pin 25 is thus applied against the bottom 4 of the brake piston 2 and is connected to the piston of

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  brake via a retaining ring 32. The portions of

  rod 27, 29 of the adjustment nut and of the adjustment pin 25

  tend, in the direction of the actuating element 12, through central bores 33, 34 formed in the ramp parts 16, 17, their ends being housed in a cylindrical recess 35 of the actuating element 12. On the outer circumference of the rod portion 27 of the adjusting nut 24, there is provided a circular groove 36 in which is placed a ring 37. On this ring is supported a compression spring 38 whose other end takes

  support against a shoulder 39 of the ramp piece 16. One of the fa-

  these before the flange portion 28 of the adjusting nut 24 is therefore

  pushed against one of the front faces of the ramp piece 17 and

which it is in abutment.

  The coupling devices provided as part of:

  present invention are also housed in the recess 35 of the element

  actuation ment 12. In the hollow adjustment spindle 25 is housed a fluted shaft 40 which comprises a fluted portion 41, essentially housed in the hollow adjustment spindle 25 to link this

  splined shaft 40 to the adjusting pin 25 'so that they

  be to slide axially with respect to each other, and a door

  bearing 42 protruding from the hollow adjustment spindle 25 di-

  rection of the actuating element 12. A socket 43 is mounted

  tative in the rolling portion 42 of the splined shaft 40. This bushing 43 comprises a cylindrical portion extending axially 44 and a flange portion extending radially 45. In the flange portion 45 of this bushing 43 is provided a recess 46 which extends over part of the circumference of the flange portion 45 and which

  receives a dowel 47 fixed to the actuating element 12.

  To ensure its positioning in the axial direction, a shoulder

  Lement 48 of the sleeve 43 bears against a shoulder 49 of the grooved shaft 40 which is provided in the connection zone between the grooved portion 41 and the bearing portion 42, and the sleeve 43 is fixed on the other side by means of a ring 50 housed in a groove

  51 of the rolling portion 42. On the cylindrical portion

  that 44 of the socket 43 is provided a coupling device in ro-

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  unidirectional station 52 constitutes, in this case, by a device

  free wheel with needles. The external coupling ring 53 of the coupling device 52 comprises a c8ne 54 which cooperates with a

  c8ne 55 provided on a coupling piece 56 to form, with this

  the latter, a friction friction coupling device 57. The coupling piece 56 is slidably mounted axially on the splined shaft 40

  by means of a toothing 58 which links the two elements in ro-

  tation. The coupling part 56 is held in the axial direction by a cage 59 whose flange portions 60, 61 engage in

  corresponding recesses provided, on the one hand, on the coupling part

  plement 56 and, on the other hand, in the socket 43. Between the flange portion 45 of the socket 43 and the coupling ring 53 is provided a spring washer 'Belleville' 62 which pushes the coupling ring 53 against the coupling part 56 so that the c8ne 54 and the cone cooperate by friction. A compression spring 63 is housed in a recess 64 formed on the inner side of the adjusting nut and bears, on the one hand, on a shoulder of the adjusting nut and, on the other hand, on the pillar of coupling 56. At the end of the rolling portion 42 of the splined shaft 40 is provided a recess

  provided with a hexagonal hole allowing the insertion of a cor-

  corresponding to rotate the splined shaft 40.

  The mode of operation of the device will now be described.

  tif of actuation and of the adjustment device allowing the compensation

  automatic wear of the brake linings.

  During the rotation of the actuating element 12 and the ramp piece 16 which is integral therewith, the two ramp pieces 16 and 17 rotate relative to each other because the ramp piece 17

  is immobilized in rotation. The ramp piece, non-rotating, 17 ef-

  thus performs an axial movement which is transmitted to the adjusting nut 24 which is, in turn, linked in rotation to the ramp piece 17 by means of a pin 66. The axial movement is then transmitted by the adjusting nut 24, via the self-locking thread 26, to the adjusting pin 25 which acts on the brake lining 7 to push it against the brake disc (not shown). This movement

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  is carried out against the force of the compression spring 38. If,

  due to wear of the brake linings, the rotation of the

  actuation ment 12 exceeds a defined angle of rotation, the

  city 47 is then applied against a wall delimiting the recess 46, which causes the bushing 43 to rotate. By means of the locked freewheel device 52 and the friction coupling device 57, the rotational movement is transmitted to the grooved tree

  which rotates the adjusting pin 25 by a corresponding angle.

  A friction torque is produced on the sides of the adjusting thread 26 when the brake application force is established. For a defined clamping force, which may for example be between 3,000 and 5,000 N, this friction torque exceeds that of the friction coupling device 57, so that it slides. Thus, no other movement exceeding the lengthening stroke is no longer transmitted. After the brake has been actuated, the actuating element 12

  is turned in the opposite direction. This rotational movement has no inci-

  dence on the adjustment device insofar as the unidirectional coupling device 52 rotates freely in this direction. To return the mechanical actuation device to the initial position in the event of a change of the brake linings, it suffices, after having deposited the threaded plug 68 ensuring the sealing of the opening 67

  practiced in the actuating element 12, to introduce a he-

  xagonal in the recess 65 provided at the end of the splined shaft

  to bring it back to the stop.

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Claims (11)

  1. An adjustment device for a disc brake, in particular for a motor vehicle, comprising a thrust element adjustable in length comprising an adjustment pin and an adjustment nut cooperating together by means of a self-locking thread, an rotary actuation, a device for transforming   sea a rotational movement in an axial movement, a piece has   axial bearing of said device acting on said pushing element   adjustable in length to bring it axially to bear against an element   brake actuation ment, a rotary drive device cooperating with said actuation element by means of a   dead travel coupling device, and a coupling device   unidirectional position, in particular a freewheel coupling device, allowing the rotation of said device to be transmitted   for driving the moving part of said thrust element,   in that between said one-way coupling device   (52) and said thrust element (23) is provided with a device for   friction coupling (57) which transmits torques, up to a   their defined, said thrust element (23), and which, beyond this torque value, is inoperative.   2. Adjustment device according to claim 1, ca-   characterized in that said friction coupling device (57)   comprises a coupling element comprising a friction cone.   3. Adjustment device according to claim 1, ca-   characterized in that said friction coupling device comprises   takes a coupling member having a flat friction surface.   4. Adjustment device according to any of the   previous sales, characterized in that provision is made for a   pulls out, in particular a spring washer "Belleville '(62), to   apply the coupling force in the axial direction.   5. Adjustment device according to any of the   previous vendications, characterized in that a tree (40) is pre- -11- - h 0 - 2574885   seen to transmit the rotational movement of said action element-   ment (12) to said pushing element (23) by means of said coupling devices (52, 57), said adjustment pin (25) being hollow and being linked in rotation to said shaft (40) with respect to which it can slide axially.   6. Adjusting device according to claim 5, ca-   fact that said shaft (40) has a bearing portion   (42) on which rotates a rotary sleeve (43) forming part of the said drive device.   7. Adjustment device according to claim 6, ca-   characterized in that said socket (43) comprises a portion of bri-   of (45) which extends radially and in which is practiced a   recess (46) receiving a dowel (47) fixed to said element of ac- operation (12).   8. Adjustment device according to claim 6 or 7, characterized in that said freewheel coupling device   (52) is placed on said socket (43).   9. Adjustment device in accordance with any of the   previous claims, characterized in that the coupling piece   ment (56) is placed on said shaft (40).   10. Adjustment device according to any of the   previous claims, characterized in that said access piece   coupling (56) is axially immobilized by a cage (59) which   turns said freewheel coupling device (52).   11. Adjustment device according to any one of   previous claims, characterized in that said devices   coupling (52, 57) are placed in a recess (35) of said element actuation.