JPH022987Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic braking gap adjustment device for a disc brake.

[Prior Art] In a disc brake equipped with an automatic braking gap adjustment device disclosed in Japanese Patent Publication No. 29-27597, the braking gap decreases due to compression deformation of the friction pads and expansion deformation of the caliper during excessive brake operation. may be adjusted unnecessarily, causing the friction pads to remain engaged with the brake disc even after the brake is released, resulting in dragging.

For example, as disclosed in Japanese Patent Application Laid-Open No. 49-133770, the maximum adjustment amount of the braking gap obtained by one brake operation is set to a value much smaller than the amount of wear of the friction pads caused by one brake operation. If set to , the above-mentioned braking gap adjustment is prevented.
However, this has the problem that it is time-consuming and the mechanism is complicated because it is necessary to repeat the brake operation many times to adjust the braking gap at the initial stage when the brake is assembled into the vehicle.

[Problems to be solved by the invention] In view of the above-mentioned problems, the purpose of the invention is to have a simple configuration, no variation in performance, and to adjust the braking gap in response to brake fluid pressure in response to excessive brake operation force. An object of the present invention is to provide an automatic braking gap adjustment device for a disc brake whose operation is interrupted.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention is such that a non-rotatable adjustment bolt that protrudes from the proximal wall of the cylinder into the inner space of the hollow piston fitted in the cylinder has a hollow An adjusting nut facing the tip wall of the piston is screwed together, one end of a clutch spring that only allows the adjusting nut to screw toward the tip of the adjusting bolt is wrapped around the adjusting nut, and the other end is locked to the hollow piston. , a spring is interposed between the seat plate of the thrust bearing that is in contact with the base end of the adjustment nut and the base end of the hollow piston, so that the large diameter part is liquid-tight on the distal end side of the hollow piston, and the base end side The seat plate is brought into contact by the force of the spring with the small diameter end portions of the stepped pistons, the small diameter portions of which are fitted through seal rings.

[Operation] When pressure fluid is supplied to the cylinder 6, the hollow piston 17 moves to the left, and the spring 14a exerts a thrust on the adjusting nut 20 via the seat plate 33 and the thrust bearing 11. An adjustment nut 20 is screwed to the left along the adjustment bolt 18 to adjust the braking clearance. At this time, the clutch spring 15 receives a force in the direction of unwinding, and does not prevent the adjusting nut 20 from threading.

When excessive hydraulic pressure is applied to the cylinder 6, the pressure receiving area at the tip of the stepped piston 12, which is isolated from each other by the seal rings 5 and 4, is wider than the pressure receiving area at the base end, so the stepped piston 12 33, the spring 14a is deflected and retreated relative to the hollow piston 17. The thrust exerted on the adjusting nut 20 is cut off, and over-adjustment of the braking gap is prevented.

When the hydraulic pressure in the cylinder 6 is released, the hollow piston 17 is returned to the right by the restoring force based on the shearing deformation of the seal ring 16, while the stepped piston 1
2 is pressed against the tip wall of the hollow piston 17 by the force of the spring 14a.

As the hollow piston 17 returns, the hollow piston 17 hits the tip of the adjusting nut 20 and when it tries to push back, the clutch spring 15 wraps tightly around the adjusting nut 20, and the adjusting nut 20 is fixed to the immovable adjusting bolt 18. The hollow piston 17 is prevented from moving back.

[Embodiment of the invention] As shown in FIG. 1, a general disc brake to which the invention is applied has a fixing member 44 made of a flat plate bent in an inverted U-shape across the outer periphery of a brake disc 43. Each notch 46 in the wall surfaces 44a and 44b is formed by cutting out the upper periphery in a U-shape when viewed from the side.
A pair of friction pads 47 and 42 are slidably supported, a caliper 3 is slidably supported on a fixed member 44, and the caliper 3 is fitted into a cylinder 6 integral with the caliper 3 via a seal ring 16. The tip of the hollow piston 17 is brought into contact with the back plate 48 of the friction pad 47, and the caliper 3 rubs the bifurcated reaction force piece 1 that straddles the outer periphery of the brake disc 43 and hangs down on the opposite side of the brake disc 43. It is constructed by abutting against the back plate 41 of the pad 42.

Wall surfaces 44a and 44b of the fixed member 44 that are parallel to the brake disc 43 are reinforced by reinforcing plates 45, respectively. The outer end of the hollow piston 17 and the caliper 3
A dustproof boot 28 is attached between the two.

As shown in FIG. 2, in the automatic braking gap adjustment device according to the present invention, the base end of the adjustment bolt 18 is penetrated and supported through the through hole 29 provided in the base end wall 36 of the cylinder 6 via the seal ring 24. , and head 18a
A disc spring 23 is interposed between the base end wall 36 and the base end wall 36 .
A pair of brackets 8 from the proximal wall 36 of the cylinder 6
is extended, and a camshaft 26 is connected to this via a bearing 27.
is supported. A cam 9 having an oval cross section is engaged between a notch provided on the circumferential surface of the camshaft 26 and a notch provided in the head 18a of the adjustment bolt 18 by the force of the disc spring 23. With this configuration, the adjustment bolt 18 does not rotate and its movement in the axial direction is restricted. In other words,
The adjustment bolt 18 does not move when the brake is operated using hydraulic pressure. The camshaft 26 and cam 9 at the base end of the cylinder 6 are covered by a dustproof cover 7.

An adjustment nut 20 is screwed onto the tip of the adjustment bolt 18 protruding into the inside of the cylinder 6 via a thread groove with a large lead, and the tip of the adjustment nut 20 is opposed to the closed end wall of the hollow piston 17. A one-way clutch spring 15 made of a coil spring is wound around the outer periphery of the adjustment nut 20, and one end 19 is locked in an axial hole provided in the tip wall of the hollow piston 17, and the other end is connected to the center portion of the adjustment nut 20. It abuts against the flange 20a formed on the flange 20a.

A seat plate 33 is abutted against the flange 20a via a thrust bearing 11. Seat plate 33 and hollow piston 1
A spring 1 is inserted between the retaining ring 10 that is locked to the base end of the spring 1
4a is interposed. A small-diameter cylindrical portion 34 is formed on the distal side of the stepped portion 31 of the inner hollow portion of the hollow piston 17, and a large-diameter cylindrical portion 38 is formed on the proximal side.
The large diameter portion of the stepped piston 12 is fitted into the cylindrical portion 34 via the seal ring 5, and the large diameter end abuts against the end wall of the hollow piston 17. Stepped piston 12
The small diameter end of the seat plate 33 abuts against the seat plate 33. Cylindrical part 38
A back-up spring 13 and a seal ring 4 are fitted between the small diameter portion of the stepped piston 12 and the seal ring 4 is protected by a seat plate 33. The cylindrical portion 34 and the inner peripheral surface of the seal ring 4 constitute a stepped cylinder into which the stepped piston 12 is fitted.

Next, the operation of the automatic braking gap adjustment device for disc brakes according to the present invention will be explained. When pressurized fluid is supplied to the cylinder 6 during braking, the hollow piston 17 moves to the left, frictionally engages the friction pad 47 (Fig. 1) with the right surface of the brake disc 43, and at the same time the caliper 3 receives a reaction force. moves to the right with respect to the fixed member 44, and the friction pad 42 is moved by the reaction force piece 1.
is frictionally engaged with the left surface of the brake disc 43 to generate braking force.

When the hollow piston 17 moves to the left, the spring 1
4a pushes the adjustment nut 20 to the left via the seat plate 33 and the thrust bearing 11, and the adjustment bolt 18
Spiral to the left (towards the tip) along the At this time, the clutch spring 15 receives a force in the direction of unwinding and does not prevent the adjusting nut 20 from threading. In this way, as the friction pad 42 wears, the adjusting nut 20 moves toward the distal end of the stationary adjusting bolt 18.

When excessive hydraulic pressure is applied to the cylinder 6 to the extent that the friction pad 42 is compressed and deformed or the reaction piece 1 of the caliper 3 is expanded due to an excessive brake operation force, the pressure receiving area at the tip of the stepped piston 12 becomes larger than the base end. Since the stepped piston 12 bends the spring 14a and retreats to the right with respect to the hollow piston 17, the seat plate 33 is pushed back and the adjusting nut 20
cut off the thrust that was exerting on the The adjusting nut 20 is therefore no longer screwed in, and over-adjustment of the braking gap is interrupted.

When the brake action is released, the hydraulic pressure in the cylinder 6 is released, and the hollow piston 17 returns to the right due to the restoring force based on the shearing deformation of the seal ring 16, while the stepped piston 12 is moved back to the right by the force of the spring 14a. Pressed against the tip wall. With the return movement of the hollow piston 17, the hollow piston 1
7 hits the tip of the adjustment nut 20, and when you try to screw it to the right, the clutch spring 15 wraps tightly around the adjustment nut 20, so the adjustment nut 2
0 is fixed to the immovable adjustment bolt 18, and prevents the hollow piston 17 from returning.

As mentioned above, when the brake is applied, the adjusting nut 20 follows the movement of the hollow piston 17 and screws toward the tip of the adjusting bolt 18, but when the brake is released, the clutch spring 15 prevents the adjusting nut 20 from moving backward, and the hollow piston 17 It acts as a stopper to limit the return movement of the piston 17. In this way, each time the brake is operated, the hollow piston 17 is damaged as the friction pads wear out.
is pushed outward from the cylinder 6 little by little, and the braking gap between the friction pad 42 and the brake disc 43 is always maintained at an appropriate value.

Note that the disc brake according to the present invention can also be used as a parking brake. When the camshaft 26 is remotely rotated counterclockwise from the driver's seat, the cam 9 is pushed to the left, and the adjustment bolt 18 is pushed against the disc spring 2.
Move to the left against the force of 3. At this time, the adjusting nut 20 cannot be screwed due to the action of the clutch spring 15, so it moves to the left together with the adjusting bolt 18, collides with the tip wall of the hollow piston 17, and moves the hollow piston 17 to the left. This generates braking force in the same way as hydraulic braking, but does not adjust the braking gap.

When the camshaft 26 is rotated clockwise to release the brake, the hollow piston 17 closes to the seal ring 16.
The adjusting bolt 18 is returned to its original position by the elastic restoring force of the adjusting bolt 18 and by the force of the disc spring 23.

[Effects of the invention] As described above, the present invention includes a non-rotatable adjustment bolt that protrudes from the base end wall of the cylinder into the inner space of the hollow piston fitted into the cylinder, and an adjustment nut that faces the tip wall of the hollow piston. One end of the clutch spring that only allows the adjustment nut to screw toward the tip of the adjustment bolt is wound around the adjustment nut, and the other end is locked to the hollow piston, and the clutch spring is brought into contact with the base end of the adjustment nut. A spring is interposed between the seat plate of the thrust bearing and the proximal end of the hollow piston, which are in contact with each other. The seat plate is brought into contact with the small-diameter end of each fitted stepped piston by the force of the spring, and when the brake fluid pressure is below a predetermined value,
The movement of the hollow piston is transmitted via the spring and the thrust bearing to the adjusting nut, which screws distally along the adjusting bolt so that the braking gap is adjusted.

When the brake fluid pressure exceeds a predetermined value, the fluid pressure acting on the stepped piston becomes greater than the spring force.
The stepped piston moves back and interrupts the spring force acting on the adjusting nut, so that the automatic braking gap adjustment action is interrupted. Therefore, in the event of an excessive braking action that deforms the friction pad or expands the space between the caliper cylinder and the reaction piece, the braking clearance adjustment action is interrupted and over-adjustment of the braking clearance is prevented. A proper braking gap is always maintained and dragging of the friction pad against the brake disc is avoided.

Compared to the system in which the adjusting nut follows the piston when the brake is applied, and when the brake is released, the adjusting nut is moved back by a predetermined amount (initial deflection amount of the spring) relative to the adjusting bolt to limit the return amount of the piston. It is not affected by variations in spring characteristics, has a simple structure, is easy to assemble, and is highly reliable because the operation of the adjusting nut is limited by the hydraulic pressure acting on the stepped piston.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of a general disc brake to which the present invention is applied, and FIG. 2 is a longitudinal sectional view of an automatic brake gap adjustment device for a disc brake according to the present invention. 3: Caliper, 5: Seal ring, 6: Cylinder, 11: Thrust bearing, 12: Stepped piston,
14a: Spring, 15: Clutch spring, 17: Hollow piston, 18: Adjustment bolt, 20: Adjustment nut.

Claims (1)

[Scope of utility model registration request] An adjustment nut facing the tip wall of the hollow piston is screwed onto a non-rotatable adjustment bolt that protrudes from the base end wall of the cylinder into the inner space of the hollow piston fitted into the cylinder, and the adjustment bolt is moved toward the tip side of the adjustment nut. One end of a clutch spring that allows only the screw movement is wound around an adjustment nut, and the other end is locked to a hollow piston, and the seat plate of the thrust bearing and the base end of the hollow piston are in contact with the base end of the adjustment nut. A spring is inserted between the
The seat plate is brought into contact by the force of the spring with the small diameter end of the stepped piston, the large diameter part of which fits liquid-tightly into the distal end of the hollow piston, and the small diameter part of which fits into the proximal end of the hollow piston through a seal ring. Automatic braking gap adjustment device for disc brakes.