JPS6340666Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an automatic braking gap automatic disc brake of the type in which at least one friction pad is directly frictionally engaged with the brake disc by a piston of a hydraulically actuated device. This invention relates to an adjustment device.

[Prior Art] In disc brakes equipped with conventional automatic braking gap adjustment devices, the braking gap is adjusted unnecessarily due to deformation of the friction pads or expansion deformation of the caliper, and even when the brake is released, the friction pads do not maintain the braking circle. It may remain engaged with the plate and cause dragging.

There is a method disclosed in Japanese Unexamined Patent Publication No. 133770/1983 as a solution to such problems.
This is because when the brake is applied, the adjusting nut screwed onto the fixed adjusting bolt follows the piston to adjust the braking gap, and when the brake is released, the adjusting nut is returned by a predetermined amount to the fixed adjusting bolt, and the piston It acts as a stopper to prevent the return of Since this adjustment action is activated by the deflection of the disc spring, it is not only greatly affected by variations in the spring characteristics of the disc spring, but also has a very complex structure and is not reliable for long-term use. I have a sexual problem.

Furthermore, in the system disclosed in Japanese Patent Publication No. 39-27597, the adjusting nut follows the piston with respect to the adjusting bolt when the brake is applied, and when the brake is released, the adjusting nut is adjusted by a predetermined amount, that is, the initial deflection of the disc spring. It spirals backward and limits the amount of return of the piston, and the spring characteristics of the disc spring affect its performance, which tends to cause variations in the braking gap.

[Problems to be solved by the invention] Therefore, in view of the above-mentioned problems, the purpose of the invention is to provide a system that has a simple configuration, has consistent performance, and detects brake fluid pressure to perform braking against excessive braking force. An object of the present invention is to provide an automatic braking gap adjustment device for a disc brake in which the gap adjustment action is interrupted.

[Means for Solving the Problems] In order to achieve the above object, the configuration of the present invention includes an adjustment bolt which is supported on the end wall of the cylinder in which the piston is fitted, and which is non-rotatable and capable of stopping axial movement. an adjusting nut that is screwed onto the adjustment bolt and whose tip faces the end wall of the piston; a helical clutch spring that is fitted together to allow the adjusting nut to screw forward but prevent it from sliding backward; and a stepped shaft portion formed on the outer circumferential surface of the adjusting nut and having a base end with a small diameter that slides on the clutch spring. a stepped sleeve movably fitted onto the outside and having a disc spring interposed between the stepped sleeve and the flange;
A thrust bearing is provided between a seat plate coupled to the piston and a proximal end surface of the stepped sleeve.

[Operation] When pressure fluid is applied to the cylinder 6, the piston 1
With the leftward movement of 7, the seat plate 25 and the thrust bearing 1
1. Thrust is applied to the adjusting nut 20 via the stepped sleeve 12 and the disc spring 14, and the adjusting nut 20 follows the piston 17 and threads against the stationary adjusting bolt 18. The clutch spring 15 only receives a force that causes it to unwind, and does not prevent the adjusting nut 20 from threading.

When a high pressure liquid is applied to the cylinder 6 to the extent that the caliper 3 is deformed, the stepped sleeve 12 and the adjusting nut 20 move toward each other against the disk spring 14 due to the difference in pressure receiving area at both ends of the stepped sleeve 12 and the adjusting nut 20. 20 retraction (movement to the right) is clutch spring 1
5, the stepped sleeve 12 moves to the left, and the retaining ring 22 and seat plate 25
The thrust exerted by the piston 17 on the adjusting nut 20 is released, so that the adjusting nut 20 stops in that position and the braking gap adjusting action is interrupted. This prevents the friction pads from approaching the brake disc abnormally and maintains a proper brake clearance.

When the hydraulic pressure in the cylinder 6 is released, the piston 17
When the piston 17 returns to the right and the end wall of the piston 17 hits the adjusting nut 20 and the adjusting nut 20 is moved backward, the clutch spring 15 wraps tightly around the adjusting nut 20 and prevents the adjusting nut 20 from sliding backward. , the piston 17 stops in its return position.

[Embodiment of the invention] The configuration of the invention will be explained based on the illustrated embodiment. First, to explain a general disc brake to which the present invention is applied, as shown in FIG. A pair of friction pads 42 and 47 are slidably supported in notches 46 of wall surfaces 44a and 44b, which are formed by cutting out a U-shaped peripheral edge when viewed from the side surface of the brake disc, and are also supported with respect to the fixed member 44. The back plate 48 of the friction pad 47 is connected to the tip of the piston 17 which is fitted into the cylinder 6 integral with the caliper 3 via the seal ring 16.
Further, the caliper 3 is constructed by abutting against the back plate 41 of the friction pad 42 a 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. Ru.

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. A dustproof boot 28 is attached between the outer end of the piston 17 and the caliper 3.

As shown in FIG. 2, the automatic braking gap adjustment device according to the present invention includes a through hole 29 provided in the end wall of the caliper 3, into which the base end of the adjustment bolt 18 is supported via a seal ring 24. Katsuko's head 18
A disc spring 23 is interposed between a and the end wall of the cylinder 6. A pair of brackets 8 extend from the end wall of the cylinder 6, on which a camshaft 26 is supported via a bearing 27, and a notch provided on the circumferential surface of the camshaft 26 and a head 18a of the adjustment bolt 18 A cam 9 having an oval cross section is inserted between the notch provided in the end face of the disc spring 2
As a result, the adjusting bolt 18 does not rotate and its movement in the axial direction is restricted. In other words, the adjustment bolt cannot move in the axial direction when the hydraulic brake is applied. Note that the camshaft 26 and the cam 9 are covered with a dustproof cover 7.

The tip of the adjusting bolt 18 extends into the interior of the cylinder 6, and an adjusting nut 20 is screwed onto this via a thread groove with a large lead, and this tip approaches the closed end wall of the piston 17. Adjustment nut 20
A one-way clutch spring 15 made of a coil spring is wound around the outer periphery of the piston 17 , and the end 19 is connected to the piston 17
It is engaged with a hole in the same direction as the adjustment bolt 18 provided in the end wall of. A flange 20a is formed at the center of the adjustment nut 20, and a step 2 is formed at the right side of the flange 20a.
A stepped shaft portion having a large diameter portion and a small diameter portion is formed with the stepped sleeve 12 as a boundary, and a stepped sleeve 12 is slidably fitted onto this portion via seal rings 4 and 5.
Then, back up spring 1 of seal ring 4
A disc spring 14 is interposed between the flange 3 and the flange 20a. The axial movement of the stepped sleeve 12 is restricted by a retaining ring 22 attached to an adjusting nut 20. A seat plate 25 is secured to the open end, that is, the right end, of the piston 17 via a retaining ring 10, and a thrust bearing 11 is interposed between the seat plate 25 and the stepped sleeve 12 described above.

Next, the operation of the automatic braking gap adjustment device for disc brakes according to the present invention will be explained. When pressure fluid is supplied to the inside of the cylinder 6 during braking, the piston 17 moves to the left and the friction pad 4
7 (Fig. 1) is frictionally engaged with the right side surface of the brake disc 43, and at the same time receives a reaction force, the caliper 3 is attached to the fixed member 4.
4, and the reaction piece 1 frictionally engages the friction pad 42 with the left side surface of the brake disc 43 to generate braking force. As the piston 17 moves to the left, thrust acts on the adjustment nut 20 via the seat plate 25, thrust bearing 11, stepped sleeve 12, and disc spring 14, and the adjustment nut 20 rotates with respect to the stationary adjustment bolt 18. At this time, the clutch spring 15 receives a force such that it is unwound and does not prevent the adjusting nut 20 from rotating forward.

If an excessively high pressure fluid is applied to the cylinder 6 to the extent that the friction pad is deformed or the reaction piece 1 of the caliper 3 expands and deforms relative to the cylinder portion, the hydraulic pressure at both ends of the stepped sleeve 12 and the adjusting nut 20 will be reduced. Based on the difference in area, a force acts against the force of the disc spring 14 and causes the two to approach each other. In this case, the backward screw movement of the adjusting nut 20 to the right is prevented by the winding action of the clutch spring 15, and only the stepped sleeve 12 moves to the left. That is, the stepped sleeve 12 separates from the retaining ring 22 and the seat plate 25, releasing the thrust that was being transmitted from the piston 17 to the adjusting nut 20. Therefore, the braking gap adjusting action by the forward screw movement of the adjusting nut 20 is prevented.

The disc spring 14 has an axial force that loosens the clutch spring 15 and rotates the adjustment nut 20, and a hydraulic pressure that acts on the stepped sleeve 12 based on the difference in the hydraulic pressure acting area of the stepped sleeve 12 (normal brake fluid). A load corresponding to the sum of (pressure) is set.
This prevents the friction pads from approaching the brake disc abnormally and ensures a proper brake clearance.

When the brake is released, the hydraulic pressure in the cylinder 6 is released, the piston 17 returns to the right due to the restoring force based on the shearing deformation of the seal ring 16, and the caliper 3 is moved back due to the frictional vibration between the brake disc 43 and the friction pad. returns to the left. Then, when the end wall of the piston 17 hits the adjusting nut 20 and the adjusting nut 20 is to be screwed, the clutch spring 15 tightly wraps around the adjusting nut 20 and prevents the adjusting nut 20 from rotating. Therefore, while the adjustment nut 20 is fixed to the immovable adjustment bolt 18,
Further return of the piston 17 is prevented.

As mentioned above, when the brake is applied, the adjustment nut 20 follows the piston 17 and spirals toward the tip of the adjustment bolt 18, and conversely, when the brake is released, the clutch spring 15 prevents the adjustment nut 20 from sliding backward, and the piston It acts as a stopper to prevent the return movement of 17. Therefore, each time the brake is applied, the piston 17 is pushed out of the cylinder 6 little by little.
The braking gap between the friction pad and the brake disc is always maintained properly.

Note that the disc brake according to the present invention can also be used as a brake for parking. That is, 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 moved to the left against the force of the disc spring 23. At this time, adjust nut 2
0 cannot be screwed due to the action of the clutch spring 15, but moves integrally with the adjustment bolt 18, collides with the end wall of the piston 17 and pushes the piston 17 to the left, and brakes by hydraulic pressure. Braking force is generated as in the case of action, but no braking gap adjustment action is performed. Then, when the camshaft 26 is rotated clockwise to release the brake, the piston 17 is moved by the elastic restoring force of the seal ring 16 and the adjustment bolt 1
8 is returned to its old position by the force of the disk spring 23.

[Effects of the invention] As described above, the present invention is an automatic braking gap adjustment device for a disc brake, in which an adjustment bolt is supported on the end wall of a cylinder of a caliper so as to prevent rotation and axial movement. Screw the adjustment nut onto the tip that protrudes into the inside of the piston,
A clutch spring is installed between the adjusting nut and the piston, and a stepped sleeve is fitted onto the stepped shaft of the adjusting nut, and the force of the disc spring interposed between the stepped sleeve and the adjusting nut is The stepped sleeve is brought into contact with the piston via the thrust bearing, so when the brake fluid pressure is below a predetermined value, the stepped sleeve transmits the movement of the piston to the adjusting nut and moves it toward the tip of the adjusting bolt. When the brake fluid pressure exceeds a predetermined value while the brake fluid is being screwed, the stepped sleeve moves away from the piston while deflecting the disc spring 14 under the fluid pressure, thereby blocking the thrust of the piston from acting on the adjusting nut.

In this way, when the brake is applied excessively, the braking gap adjusting action is interrupted to prevent over-adjustment of the braking gap, maintaining an appropriate braking gap at all times, and preventing the friction pad from dragging against the brake disc.

Then, as in the conventional example, when the brake is applied, the adjusting nut follows the piston, and when the brake is released, the adjusting nut is screwed back against the adjusting bolt by a predetermined amount (the initial deflection amount of the spring) to adjust the return amount of the piston. Compared to a restrictor, it is not affected by variations in spring characteristics, and the adjusting nut is operated by the hydraulic pressure acting on the stepped shaft, resulting in superior operational reliability.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing the general structure of a disc brake to which the present invention is applied, and FIG. 2 is a side sectional view of an automatic braking gap adjustment device in the disc brake according to the present invention. 3: Caliper, 4, 5: Seal ring, 6: Cylinder, 11: Thrust bearing, 12: Stepped sleeve, 13: Backup spring, 14: Disc spring,
15: Clutch spring, 17: Piston, 18: Adjustment bolt, 20: Adjustment nut, 23: Belleville spring.

Claims (1)

[Claims for Utility Model Registration] An adjustment bolt that is non-rotatable and supported on the end wall of a cylinder into which a piston is fitted so as to be able to stop its axial movement; and an adjustment bolt that is screwed onto the adjustment bolt and whose tip is attached to the end wall of the piston. an adjusting nut that is wound around the adjusting nut and has one end locked to the piston and the other end abutted against the flange of the adjusting nut, allowing the adjusting nut to move forwardly but not backwardly; a helical clutch spring that prevents screwing; and a disc spring that is slidably fitted onto a stepped shaft portion formed on the outer peripheral surface of the adjustment nut and whose base end has a small diameter, and between the flange and the stepped shaft portion. automatic braking gap adjustment for a disc brake, comprising: a stepped sleeve interposed therein; and a thrust bearing interposed between a seat plate coupled to the piston and a base end surface of the stepped sleeve. Device.