JPS6182026A - Disc brake - Google Patents

Abstract

PURPOSE:To prevent the one-sided abrasion of a friction pad by forming the convex part having a high center part onto the piston contact part of the back plate of a friction pad and reducing the shift of the contact position between the piston and the back plate. CONSTITUTION:On the piston side 20 of the both back plates 22 and 22, the convex parts 25 and 25 in spherical surface form are formed so that the top parts form the point contact nearly at the center of the cover body 24 of the piston 20. Therefore, when a caliper 17 is spread by a strong input, the shift of the pressing point of the piston 20 which contacts onto the back plate of a friction pad 21 is little. Therefore, the pushed friction pad 21 always press- attaches with a brake disc by a uniform surface pressure, and brake action is generated, and the one-sided abrasion can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulically operated disc brake.

[Prior art] In conventional hydraulically operated disc brakes, the entire end surface of a piston inserted into the cylinder of a caliper comes into contact with the rear surface of the back plate of a friction pad, and the pressure fluid introduced into the cylinder during braking is applied to the piston. Generally, braking was performed by driving a piston and causing the piston to press a friction pad against a disk via a back plate.

[Problem that the invention seeks to solve]

Therefore, the pressure force of the piston operated by hydraulic pressure during braking exerts a force that forces the action and reaction parts of the caliper to expand in the direction of separation from each other. Therefore,
When the action and reaction parts of the caliper expand, the piston comes into contact with the back plate of the friction pad at an angle, and the surface pressure of the friction pad against the brake disc becomes uneven, reducing braking efficiency. , an extra stream of hydraulic fluid is required to drive the piston, and the brake lever stroke [
As the distance increases, the part of the friction pad in contact with the peripheral edge of the brake disk is likely to suffer a=S damage. It is common practice to prevent this. In particular, in zero-pressure boost type or self-servo type brake systems that use braking torque to drive a hydraulic pressure generating device, the input force is strong, so the caliper needs to be especially rigid, and the caliper becomes larger. However, there were problems such as an increase in weight.

The present invention was developed in view of the above points, and allows smooth braking even if the caliper is slightly expanded and the contact angle of the piston to the S+ pad is tilted, and the friction pad is also improved! The purpose of the present invention is to provide a disc brake that does not wear out and also allows the caliper to be made smaller and lighter in weight.

(Means for Solving the Problems) As a means for solving the above problems, the present invention drives a piston with pressure fluid introduced into a cylinder formed in a caliper, and the piston drives a friction pad onto a brake disc. A disc brake that performs braking by pressing, characterized in that a convex portion with a high center portion is provided on either the piston contact portion of the friction pad back plate or the pad contact portion of the piston. There is.

[For production]

With this configuration, when the caliper expands due to a strong input, there is little movement of the pressure point of the piston that contacts the back plate of the friction pad, and the pressed friction pad always brakes with uniform surface pressure. It presses against the disc and performs braking action.

〔Example〕

Hereinafter, an embodiment in which the present invention is applied to a disc brake equipped with a piston-opposed caliper that operates by introducing pressure fluid from a mask cylinder driven by braking torque will be described based on FIGS. 1 to 6. explain.

A front wheel 2 is rotatably supported by a front axle 3 between the lower ends of front forks 1 and 1 disposed at the front of the vehicle body, and a first brake device 4 and a second brake are provided on both sides of the front wheel 2. A device 5 is provided. That is, the brake disc 6 of the first brake device δ4 is placed on one side of the front wheel 2, and the brake disc 7 of the second brake device 5 is placed on the other side of the front wheel 2, sandwiching the hub 2a of the front wheel 2. A bracket portion 9 is provided at the base end of a first brake liper 8 which is arranged to rotate together and which is opposed to the screws 1 to 8 which clamps the brake disc 6 of the first brake device 4 to perform braking. The first caliper 8 is rotatably supported by the lower part of the front flap 4'1, and a second mask cylinder 1°, which has an open disk protruding side of the first caliper 8, is integrated with the tip side of the first caliper 8. A piston 11 is inserted into the second mask cylinder 10 so as to be pushable by a tip of a bushing rod 12 whose base end is rested in the front fork 1.

This second mask cylinder 10 has a protrusion 10a on the outside as shown in FIG. An external region formed on the brake disc 6 side and on the bottom side of the cylinder from the forward limit during braking of the piston 11 fitted into the second mask cylinder 10, and outside the sliding portion of the piston 11 of the second mask cylinder 10. Make sure that it does not come into direct contact with other objects.

Moreover, there are two
One of the pieces? Friction pads (not shown) sandwich the brake disc 6 and are disposed so as to be movable in the disc axial direction.
The first caliper 8 is supplied with pressurized fluid generated by braking a first mask cylinder 13 with a reservoir attached to a handle par 12 provided at the upper end of the front nozzle 1 with a brake lever 14. 1 Pregi Horse 1
5 and a reserve hose 16 for replenishing the working fluid from the reservoir portion to the second mask cylinder are connected.

On the other hand, a piston-opposed second caliper 17 performs braking by pinching the brake disc 7 of the second brake device 5.
is fixed to the front fork 1 on the brake disc 7 side via a bracket part 18, and is disposed with the brake disc 7 loosely fitted, and the second caliper 17 receives pressure from the first mask cylinder 13. When the first caliper 8 operated by liquid rotates around the bracket part 9 due to braking torque, the piston 11 is rotated by the bushing rod 12.
The pressure dk generated in the second mask cylinder 10 driven by
is introduced via the second brake hose 19, and braking is performed by the second brake device 5.

Further, this second caliper 17 is formed with 45 cylinder parts 17b, 17b each having a cup-shaped piston 20 and 20 inserted thereinto on both sides of the bridge part 17a, and there is no friction between the pistons 20 and 20. 1! ! Pad 21.21
attaches the upper part of each back plate 22 and 22 to the hanger bin 23
The friction pad 2 is suspended movably in the axial direction of the disk.
1. The brake disc 7 is disposed between the brake discs 7 and 7.

Then, J is attached to the second caliper 17 of this embodiment shown in FIG.
5, the openings on the friction pad 21 side of the cup-shaped pistons 20, 20 are closed by fitting disc-shaped attachments 24, respectively, and the openings of the two back plates 22, 22 are closed. Spherical convex portions 25.25 are formed on the piston 20 side, and the top portions of the convex portions 25.25 are in point contact with approximately the center of each lid body 24 of both pistons 20. .

Further, in the second caliper 17 of another embodiment shown in FIG. Arc-shaped convex portions 28. are provided on two positions of the pad 27 corresponding to approximately the center in the radial direction of the brake disc 7.
28 (one not shown) are formed facing each other, and each piston 26 has a top portion of each convex portion 28.28 on the back surface of a flat back plate 29 of each friction pad 27. It is designed to come into contact with each other in two places.

Next, the operation of the present invention will be explained with reference to the embodiment shown in FIG. When the brake lever 14 is operated for braking while driving, IE fluid is supplied from the first mask cylinder 13 to the first caliper ε3 via the first brake hose 15, and the 1'1! Braking is performed by the first brake device 4 by pinching the brake disc 6 rotating together with the front wheel between the In pads.

Due to the action of the braking torque, the first brake lever 8 which has compressed the brake eye cross rotates in the direction of rotation of the brake disc 6 using the mounting part of the bracket part 9 as a fulcrum and approaches the front fork 1, so that the first brake lever 8 The piston 11 of the second mask cylinder 10 integrally formed with the V-ribber 8 is driven by the tip of a bushing rod 12 whose base end is locked to the front fork 1 to increase the pressure in the hydraulic pressure chamber of the second mask cylinder 1o. Become.

The pressurized fluid pressurized in the second mask cylinder 10 is sent to the second caliper 17 via the second brake hose 19, actuating the opposing pistons 26.26, respectively, and forming a At the tops of the convex portions 28.28, the friction pads 27.27 are respectively attached to the back plate 29.
29 to the brake disc 7 side, both 1! j
lE! The brake disc 7 is pressed between the bands 27 and 27 to perform braking by the second brake device 5.

This second mask cylinder 10, which is driven by the braking torque, operates by the pressure fluid generated in the second mask cylinder 10.
The caliper 17 is operated by the pistons 26, 26 that push the friction pads 27 and 27 that press the brake disc 7, because a strong hydraulic pressure is suddenly supplied to the caliper 17, especially when sudden braking is applied during high-speed driving. The actuation becomes particularly large, and the cylinder parts 17b, 17b connected by the bridge part 17a are pushed apart in the direction of separation due to the reaction force of the piston 26° 26, and the opposite side of the cylinder parts 17b, 17b tends to expand. However, there is an arc-shaped convex portion 28.2 at the end of the piston 26 that comes into contact with each back plate 29 of the friction pad 27.27.
8, as shown in FIG. 6, the opposite side of the bridge part of the second gripper 17 expands, and the normal line of the abutment position of the back plate 29 and the axis of the cylinder part 17b are slightly inclined b. There is little change in the contact state, and the braking action is performed in substantially the same manner as during normal operation of the second caliper 17.

Fig. 7 is a graph showing the relationship between braking force and hydraulic fluid volume, with the horizontal axis representing the braking force and the vertical axis representing the hydraulic fluid m. Line A represents the caliper of a conventional disc brake. Indicates the characteristics of a model in which the entire piston end surface contacts the back plate,
Line A shows the characteristics of the second caliper 17 of the disc brake according to the present invention. In the disc brake of the present invention, even when the caliper expands, the braking force increases in proportion to the increase in the amount of hydraulic fluid. However, the conventional disc brake requires more hydraulic fluid than the disc brake of the present invention in order to achieve the same braking force of 1q.

Note that both of the embodiments described above are applied to the second caliper of a disc brake having a second brake chamber operated by pressure fluid from a second mask cylinder driven using braking torque. Even when the present invention is applied to a general disc brake that does not have a second I rake device, similar actions and effects can be obtained, and in particular, the stroke amount of the brake lever during braking operation can be made constant.

〔Effect of the invention〕

As explained above, the disc brake according to the present invention is
A convex portion with a high central portion is provided on either the piston abutting portion of the friction pad back plate or the pad back plate abutting portion of the piston, so that when the caliper of the disc brake is expanded by a strong input, Since the movement of the contact position between the 1- and 15-wheels is reduced, it is possible to prevent uneven wear of the friction pad, and the bridge part of the caliper does not require as much rigidity, making the 21 caliper smaller.・It has effects such as being able to reduce weight.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is a perspective view showing the front part of a motorcycle having a second brake device, and FIG. 2 is an enlarged explanation of the brake device portion. Fig. 3 is a sectional view taken along the line ■-■ in Fig. 2, Fig. 4 is a sectional view of a main part showing the second caliper of this embodiment, and Fig. 5 is a main part showing a second caliper of another embodiment. The cross-sectional view and FIG. 6 are graphs showing the relationship between the braking force and the amount of hydraulic fluid in the caliper of the expansion brake of the second caliper and the second caliper of the disc brake of this embodiment. 1...Front fork 2...Front wheel 4...
・First brake fitting 5...Second brake device 6.
7...Brake disc 8...1st caliper 1
0...Second mask cylinder 11...Piston 1
2... Bush rod 13... First master cylinder 14... Brake lever 17... Second
Kiselipa 20...Piston 21...Friction pad 22...Back plate 23...Hanger bin 2
4... Lid body 25... Convex part 26... Piston 27... Friction pad 28... Convex part 2
9... Back plate patent applicant Honda Motor Co., Ltd. Funa 2 Tomoe Q ~

Claims (1)

[Claims] 1. In a disc brake in which a piston is driven by a pressure fluid introduced into a cylinder formed in a caliper, and the piston presses a friction pad against a brake disc to perform braking, the piston contact portion of the friction pad back plate or the A disc brake characterized in that a convex part with a high central part is provided on one of the pad contact parts of the piston.