CN110914572B

CN110914572B - Disc brake and brake actuator

Info

Publication number: CN110914572B
Application number: CN201880047516.8A
Authority: CN
Inventors: S·桑德伯格
Original assignee: Haldex Brake Products AB
Current assignee: Haldex Brake Products AB
Priority date: 2017-05-26
Filing date: 2018-05-24
Publication date: 2022-03-22
Anticipated expiration: 2038-05-24
Also published as: CN110914572A; DE202017002779U1; WO2018215632A1

Abstract

The invention relates to a brake actuator for a disc brake, comprising an adjusting device (B) which is rotatable on a lever (1) and is guided at least partially axially displaceably. The invention also relates to a disc brake comprising such a brake actuator.

Description

Disc brake and brake actuator

Technical Field

The invention relates to a brake actuator for a disc brake and a disc brake with such a brake actuator, in particular for trucks.

The invention comprises a disc brake having either sliding callipers or fixed callipers, and overlapping one or more brake discs. The present invention relates generally, but not exclusively, to a partially lined disc brake.

Background

Disc brakes, in particular for heavy trucks, are disclosed in different embodiments, not only with regard to the type of brake actuator, the way in which the braking force is transmitted to one or more brake discs, but also with regard to the adjustment way for compensating for brake lining wear.

A special embodiment of a brake actuation device for use in a disc brake is disclosed, for example, by the applicant's international application WO2011/113554a 2. The brake actuator known from this application is distinguished by an extremely compact construction, with the consequent low space requirement and low weight in the housing of the brake caliper. All components of the brake actuator are mounted in a functionally cooperating manner in the brake caliper by means of a rod mounted axially in the housing of the brake caliper, so that they work parallel to the axis of rotation of the brake disc. Because of the displacement movement of the force amplification means, the pressure piece performs a translational movement together with the adjusting device towards the brake disk in order to transmit the pressing force.

The adjusting device for compensating wear has a torque clutch, which is torque-controlled and serves to selectively transmit a rotation dependent on the direction of rotation between components of the torque clutch. The adjusting device also has a one-way clutch, wherein two components which are rotatably mounted on the lever, namely an inner mounting sleeve and a hollow shaft, are connected to one another by means of a free-running spring, wherein the one-way clutch is designed in such a way that it transmits a rotational movement between the two components during the actuation of the brake and slips during the release of the brake.

With regard to the exact operating mode and the control movement in connection with the supply and transmission of the braking force in the brake actuators known from the prior art, reference is made explicitly to the disclosure of WO2011/113554a 2. Other similarly designed brake actuators are disclosed, for example, by the applicant's WO2013/083857a2, WO2014/106672a2 or WO2015/140225a2, to which reference is also explicitly made.

When replacing a worn brake lining, at least the adjusting device of the brake actuator, but generally the entire mechanism, must be reset in order to be able to remove or detach the brake lining or the brake lining fastening plate from the pressure plate of the pressure piece.

For this purpose, in the prior art, a gearwheel is provided which is arranged radially on the outside, facing away from the brake disk, on the adjusting shaft and is connected thereto in a torque-transmitting manner. The gear is rotated by a separate mechanism operable from outside the caliper to return the adjustment shaft, i.e. pull it back into the caliper housing. In this regard, reference is made, for example, to the illustrations and accompanying description paragraphs of fig. 5 and 11 of the above-mentioned WO2011/113554a 2.

In a different embodiment of the prior art described above, the gear wheel is in direct contact with the bearing seat of the lever, so that the pressing force is transmitted axially through the gear wheel into the adjusting shaft.

Disclosure of Invention

In view of this, the invention proposes the task of providing an improved brake actuator in which the gear wheel for the resetting device is decoupled from the force flow of the contact pressure for the lining change in the operating state. In addition, it is an object to provide a disc brake which uses such a brake actuator.

The core of the invention is to provide a brake actuator for a disc brake, comprising:

a force-increasing means for introducing a pressing force into the pressure piece, which transmits the pressing force to the brake disk,

-wherein the pressure piece comprises an adjustment shaft in threaded engagement with a pressure pad cooperating with a brake pad, such that rotation of the adjustment shaft causes axial movement of the pressure pad;

an adjusting device, which is designed to rotate the adjusting shaft in the operating state of the disc brake in order to compensate for lining wear; and

a drive designed to put the adjusting shaft in rotation as required outside the operating state of the disc brake;

wherein the drive element is decoupled from the contact pressure flow by the brake actuator.

Outside the operating state, all cases in which the vehicle and thus the disc brake are subjected to maintenance, repair or inspection are included here.

The drive element is preferably designed as a toothed wheel, which is arranged radially on the outside on the adjusting shaft.

Due to the fact that the gear wheel is not placed in the force flow of the contact pressure during braking operation of the disc brake, it can be made lighter or thinner overall or of less more resistant material. At the same time, some parts of the brake actuator and thus the entire brake actuator can be designed more rigidly in order to transmit forces.

In one embodiment, the gear is provided in an annular groove of the adjustment shaft.

In a preferred embodiment, the gear wheel has a mechanism which, together with a complementary mechanism of the adjusting shaft, effects a torque-transmitting engagement. The means are preferably designed as radially inwardly directed projections which engage in complementary radially inwardly shaped recesses on an end face of the adjusting shaft.

In addition, the gear wheel may preferably be divided radially in the raised area. This separation makes it easier to mount the gearwheel in the annular groove of the adjusting shaft, since the ring of the gearwheel can thus easily be pulled apart.

In order to transmit the pressing force directly from the force amplifier into the adjusting shaft, it can have a radially inwardly and coaxially outwardly projecting ring on the end face, which ring cooperates with a complementary-shaped recess of the force amplifier. In the ring itself, a plurality of recesses can be provided radially on the inside, which recesses are designed to achieve torque-transmitting and axially displaceable engagement with corresponding projections of the output part of the adjusting device.

The invention further relates to a disk brake having a brake actuator according to at least one of the above-described embodiments. In particular, the invention relates to a disc brake in which a brake actuator according to at least one of the above-described designs can be mounted in the housing of the brake caliper of the disc brake at least in the form of a module or as a self-supporting unit overall by means of a lever.

Drawings

Further advantages and features of the invention result from the following description of an embodiment thereof in conjunction with the drawings, in which:

fig. 1 shows a lateral longitudinal section in the axial direction of a brake actuator according to the invention;

FIG. 2a shows a partially exploded view of the brake actuator;

FIG. 2b shows an exploded view of another portion of the brake actuator;

FIG. 3a shows a cross-section along M-M of FIG. 1;

FIG. 3b shows a cross-section along L-L of FIG. 1;

fig. 4 shows a perspective view of only the adjusting shaft of the adjusting device with a gear;

FIG. 5 shows a front view of the adjustment shaft with gears;

fig. 6 shows an axial cross section of an adjusting shaft with a gear.

Detailed Description

Fig. 1 to 3b show all the components of the brake actuator according to the invention in general. With regard to the exact mounting position of such a brake actuator according to the invention in the brake caliper housing, reference should be made, for example, to WO2011/113554a2 of the applicant, the disclosure of which is hereby expressly referred to.

The brake actuator according to the invention is essentially composed of four modules which cooperate in function, namely a force amplification means a, an adjustment device B, a pressure piece C and a restoring device D, wherein the brake actuator can be mounted as a self-supporting unit on itself by means of a central rod 1 and thus in the housing of the brake caliper.

The force booster a serves to transmit the actuating force as a contact force from a hydraulic, pneumatic or electromechanical actuator (not shown here) into the brake actuator and to increase it according to a transmission ratio determined by its design. A lever 2 is rotatably mounted in a rear housing of a brake caliper (also not shown here), which lever 2 is rotatably mounted relative to a roller 3, wherein the roller 3 is eccentrically positioned relative to the axis of rotation of the lever 2. A needle bearing or needle bearing cage 4 is provided between the respective faces of the roller 3 and the lever 2.

On the side opposite the roller 3, the lever 2 is mounted rotatably on a corresponding bearing surface of a preferably one-piece bearing seat 6 by means of a corresponding needle bearing or needle bearing cage 5.

The force amplification means a is designed such that the lever 2 performs an eccentric displacement movement relative to it by rotation about the roller 3, which displacement movement results in a corresponding increase in the operating force acting on the lever 2, which operating force is then transmitted as a pressing force to the adjusting device B and the pressure piece C by the movement of the brake disk through the alignment (not shown here) of the bearing block 6, which can be guided linearly, indirectly or directly, in the housing of the brake caliper for this purpose.

The adjusting device B follows the bearing seat 6 for the lever 2, seen in the axial direction in relation to the brake disc.

The adjusting device B has a plurality of functionally cooperating components.

An input element 7 in the form of a hollow shaft for the adjusting device B is rotatably mounted on the lever 1. The hollow shaft 7 has an integral journal 8, which is received in a recess 9 in the lever 2, as is shown by way of example in fig. 3 a. The rotational movement of the lever 2 brings the input element 7 into rotation by the engagement of the journal 8 with the groove 9, as will be explained in more detail below in connection with fig. 3 a.

The input part 7 is connected to the output part 10 by a free-running spring 11, which thus forms a first torque clutch. The output element 10 is also mounted rotatably on the rod 1 and is designed as a radial bearing bush having an axial longitudinal groove 12 in which the balls 13 of a ball bearing cage 14 are guided for movement.

In this way, the output element 10, which is driven in rotation by the input element 7 via the free-running spring 11, can transmit the rotary motion to the first front clutch ring 15 of the second torque clutch, but is also arranged axially displaceable relative to this clutch ring 15, the clutch ring 15 also having on the inside a longitudinal groove 12' for receiving and guiding the balls 13.

The second torque clutch is designed such that the front clutch ring 15 cooperates with a second rear clutch ring 17 via a ball bearing ring 16. In this case, the balls 18 are guided in the ball race 16 on respective ramps 19 which are arranged circumferentially in the mutually facing end faces of the first clutch ring 15 and the second clutch ring 17, as can be seen from fig. 1, so that a respective roller ramp mechanism which is dependent on the torque is formed.

The rear clutch ring 17 then transmits the rotary motion caused to this point to the hollow adjusting shaft 20 by means of a pin-and-slot connection, and to achieve this, the rear clutch ring 17 has radially projecting uniformly distributed pins 21 which are inserted into corresponding slots 22 of complementary design on the radially inner side of the adjusting shaft 20, as is exemplarily seen in fig. 3 b.

The adjusting shaft 20 engages by means of a threaded engagement with a pressure plate 23 of the pressure piece C, which pressure plate is guided in a linearly displaceable, but non-rotatable manner in the housing of the brake caliper, so that a rotational movement for the adjustment of the adjusting shaft 20 results in a linear offset of the pressure plate 23. As can be seen, the adjusting shaft 20 completely surrounds the other components of the adjusting device B. The pressure plate 23 of the pressure piece C, which is in the form of a plunger or cup, cooperates at its front face with a brake pad holder (not shown here) in order to transmit the pressing force to the brake pad.

The pressing force is introduced into the pressure plate 23 by directly supporting the adjusting shaft 20 on the bearing seat 6 of the lever 2. That is to say, the pressing force introduced into the bearing seat 6 by the pivoting movement of the lever 2 is transmitted into the adjusting shaft 20 and, by means of the screw joint, into the pressure plate 23 and then, upon braking action, from there into the brake disk via the brake lining.

In addition, the rear clutch ring 17 is supported on the bearing housing 6 by a low-friction support bearing 24. The bearing seat 6 is in direct force-transmitting contact with the adjusting shaft 20, wherein a radially partially circumferential axial projection 25 of the adjusting shaft 20 is inserted into a correspondingly designed annular groove 26 of the bearing seat 6. The main force flow of this pressing force is thus achieved from the bearing block 6 directly into the adjusting shaft 20 and through the threaded engagement to the pressure-receiving plate 23, while the rear clutch ring 17 and thus the adjusting device B as a whole remain substantially axially decoupled from the pressing force because of the low-friction support bearing 24.

On the side opposite to the support bearing 24, the front clutch ring 15 is rotatably guided on a bearing race 28 by means of a further low-friction support bearing 27.

The spring 29 of the return device D rests against the bearing race 28. The return spring 29, which is designed in the form of a helical spring, is in turn supported with a sliding ring 30 interposed on a bearing cap 31, which is attached to the end of the rod 1 facing the brake disk. The restoring spring 29 is designed to exert a defined pretension on the second torque clutch, which pretension determines the limit transmission torque between the clutch rings.

In this case, the bearing cap 31 is held on the bar 1 in a rotatably arranged manner by means of a bearing ring 32 and fasteners 33, as will be described further below.

In the front end region of the lever 1, a bearing bush 34 is provided, which bears directly on the end face of the output part 10 on the side facing away from the brake disk.

The bearing sleeve 34 accommodates a spring element 35 which is in turn supported on the bearing ring 32. In this way, according to the invention, a defined pretensioning force is applied by the spring element 35 via the output element 10 to the input element 7.

At the end facing the brake disk, the bearing bush 34 has a distance X from the bearing ring 32, wherein the spring element 35 passes through an opening 36 in the bearing cap 31.

It is clear that this makes it possible to move the input element 7 and thus also the output element 10 together with the bearing bush 34 at most axially by this distance X towards the brake disk, whereby the bearing bush 34 is moved through the opening 36 in the bearing cap 31 until it abuts against the bearing ring 32.

As the lever 2 pivots, the groove 9 in the lever 2 moves forward along a circular trajectory towards the brake disc. Until the upper edge of the recess 9 comes into contact with the journal 8, a gap a is first of all bridged, which corresponds to an unadjustable wear-independent air gap of the actuator.

The groove 9 then carries the journal 8 and thus the input 7 on the lever 1 in rotation along a circular path corresponding to the rotational movement.

At the same time, the feed caused by said circular trajectory due to the rotary movement of the groove 9 or the lever 2 applies a force to the journal 8 towards the brake disc. Since the input element 7 and in principle also the entire actuating device B are mounted on the rod 1 so as to be axially displaceable, the input element 7 together with the actuating device B executes an axial forward movement on the rod 1, which is oriented counter to the biasing force of the spring element 35.

When the bearing sleeve 34 abuts the bearing ring 32 after the distance X is crossed, the forward movement is to the head.

Due to the fact that the journal 8, in addition to rotation, can be moved forward by the maximum length X together with the groove 9, the forces acting at the contact point between the groove 9 and the journal 8 are reduced in the axial direction and the contact friction is thereby minimized, whereby the service life of the device can be considerably extended with reduced wear.

According to the invention, the distance X is selected such that the functional safety of the transmission of force between the lever 2 and the journal 8 for any wear state is always ensured for actuating the adjusting device B, while the force can be sufficiently reduced.

The bearing cap 31 is engaged with the adjusting shaft 20 in a torque-transmitting manner, by the projections 37 of the bearing cap 31 being guided in axially elongated grooves 38 on the inner surface of the adjusting shaft 20.

Since the bearing cap 31 rotates with the adjustment shaft 20, the end of the return spring 29 facing the brake disk is disengaged by means of a slide ring 30 mounted in the bearing cap 31.

The fastening element 33 and the bearing ring 32, which are fitted around the annular groove 39 of the rod 1, can thus rotate together with the bearing cap 31. According to the invention, during such a rotation, the friction conditions between the fastening element 33 and the rod 1 in the annular groove 39 are determined by corresponding dimensioning of the components and/or determination of the surface conditions in the contact surfaces in such a way that, in response, a defined counter-torque is applied to the entire brake actuator, which makes it possible to reduce wear, in particular between the parts of the adjusting device B which are movably mounted relative to one another.

As shown in fig. 1, the entire brake actuator is held on the brake disk side by the fastening elements 33 rotatably mounted on the lever 1 and on the opposite side of the brake disk by the fastening ring 40 on the lever 1, by the force amplifier a, the adjusting device B, the pressure piece C and the restoring device D being arranged in a functionally coordinated manner, the hollow adjusting shaft 20 here completely accommodating the remaining components of the adjusting device B and the restoring device D. The brake actuator may be mounted and fixed as a unit within the housing of the caliper by means of the lever 1.

Fig. 4 to 6 show only the combination of the adjusting shaft 20 and the gearwheel 41 for resetting the adjusting device B when the brake lining has to be replaced. It cooperates for this purpose with a mechanism (not shown) that can be operated from outside the caliper.

The toothed wheel 41 is seated on the adjusting shaft 20 at an axial distance Y from the bearing seat 6, so that no pressing force is directly transmitted into the toothed wheel 41.

In the illustrated embodiment, the gear 41 is also decoupled from the rear clutch ring 17, which is the output of the second torque clutch. It is also conceivable, however, for the clutch ring 17 to drive the gearwheel 41 located thereon and thus indirectly the adjusting shaft 20 instead of driving the adjusting shaft 20 directly, for which purpose the adjusting shaft can have a radially inwardly directed projection which passes through a corresponding opening in the adjusting shaft 20 and, together with the clutch ring 17, effects a corresponding torque-transmitting wedge-groove engagement or the like.

The toothed wheel 41 is continuously divided in the region of the radially inwardly directed projections 42 by a gap 43 which enables the toothed wheel 41 to be pulled apart in the radial direction for mounting. The projection 42 is inserted in a torque-transmitting manner into a preferably complementarily shaped recess 44 in the adjusting shaft 20. In addition, the two halves of the projection 42 have radial recesses 45. Thereby, the gearwheel 41 can be mounted in its entirety easily in the circumferential annular groove 46 of the adjusting shaft 20.

The bearing seat 6 of the force amplification means a acts directly on the front bearing surface 47 of the adjusting shaft 20, whereby the gear wheel 41 is kept decoupled from the contact pressure introduced via this bearing surface 47 by the distance Y.

Claims

1. A brake actuator for a disc brake, the brake actuator comprising:

-a force-increasing mechanism (A) for transmitting a pressing force into a pressure piece (C) which transmits the pressing force to a brake disc,

-wherein the pressure piece (C) comprises an adjustment shaft (20) in threaded engagement with a pressure piece (23) cooperating with a brake pad, such that rotation of the adjustment shaft (20) causes axial movement of the pressure piece (23);

-an adjustment device (B) designed to rotate the adjustment shaft (20) during an operating condition of the disc brake to compensate for lining wear; and

-a drive (41) designed to put in rotation the adjustment shaft (20) when required outside the operating state of the disc brake;

the brake actuator is characterized in that the drive element (41) is decoupled from the contact pressure force flow by the brake actuator, wherein the drive element (41) is seated on the adjusting shaft (20) at an axial distance (Y) from a bearing seat of the force multiplier (A), and the bearing seat of the force multiplier (A) acts directly on a front bearing surface of the adjusting shaft (20), whereby the drive element (41) is kept decoupled from the contact pressure force introduced via the bearing surface by the distance (Y).

2. The brake actuator according to claim 1, wherein the drive is formed as a gear wheel which is arranged radially on the outside of the adjusting shaft (20).

3. The brake actuator according to claim 2, wherein the gear wheel is received in an annular groove (46) of the adjustment shaft (20).

4. A brake actuator according to claim 2 or 3, wherein the gear wheel comprises a member (42) in torque transmitting connection with a member of the adjusting shaft (20).

5. Brake actuation mechanism according to claim 4, wherein the component torque-transmitting connection with the component of the adjustment shaft (20) is formed as a radially inward projection which engages in a complementary-shaped recess (44).

6. The brake actuator according to claim 5, wherein the gears are separated in radial direction by a gap (43).

7. The brake actuator according to claim 1, wherein the adjusting shaft (20) has at its end face at least one ring (25) which projects radially inwardly and coaxially outwardly and which is matched to a complementary-shaped groove (26) of the force amplifier (a).

8. Brake actuator according to claim 7, wherein a plurality of recesses (22) are provided radially on the inside in the ring element (25), which recesses are designed to be connected in a torque-transmitting and axially displaceable manner with corresponding projections (21) of the output member (17) of the adjusting device (B).

9. A disc brake comprising a brake actuator according to any one of claims 1 to 8.

10. The disc brake of claim 9, in which the brake actuator according to any one of claims 1 to 8 is mountable as a self-loading unit in a housing of a brake caliper of the disc brake by means of a lever (1).