JPH0218831Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a hydraulic disc brake with a stepped piston.

[Conventional technology]

A conventional hydraulic disc brake of this type will be explained based on FIGS. 2 to 4. A caliper body 1 has an actuating part 3 and a counteracting part 4 integrally formed on both sides of a bridge part 2. An actuating section 3 and a counter-actuating section 4 are arranged on both sides of the disk 5, which rotates integrally with the wheel.

The actuating portion 3 has a large diameter portion 6a on the disk 5 side.
A stepped cylinder 6 in which a small diameter part 6b is formed in a stepped manner via a stepped part 6c is formed in the rear part following this, and a large diameter part is formed in the front on the disk 5 side within this stepped cylinder 6. 7a, a small diameter portion 7c is connected to the rear through a stepped portion 7b, and the stepped piston 7 is fluid-tight and movable, with the rear end on the inner wall 6d side of the stepped cylinder 6 being closed by the rear end wall 7d. It can be inserted easily.

A piston seal seals the pressure fluid into a seal groove 8 provided around the large diameter portion 6a of the stepped cylinder 6 and a seal groove 9 provided around the small diameter portion 6b, and also causes the stepped piston 5 to roll back when the brake is released. 10 and 11 respectively, and the large diameter portion 6
A first hydraulic pressure supply port 12 is provided near the stepped portion 6c of a.
A second hydraulic pressure supply port 13 is opened in the vicinity of the inner wall 6d of the small diameter portion 6b, and hydraulic pressure is supplied from a hydraulic pressure supply device (not shown) of a separate system through both ports 12 and 13, respectively. The fitted piston 7 is actuated, thereby creating a first hydraulic pressure between the piston seals 10 and 11, that is, between the large diameter portion 6a and the stepped portion 6c of the stepped cylinder 6 and the stepped portion 7b and the small diameter portion 7c of the stepped piston 7. The chamber 14 is connected to the rear of the piston seal 11 of the small diameter portion 7c, that is, by the inner wall 6d of the stepped cylinder 6, the small diameter portion 6b, and the rear end wall 7d of the stepped piston 7.
A hydraulic chamber 15 is defined respectively.

Further, on both sides of the disk 5, friction pads 17, 17 fixed to a pair of pad back plates 16, 16 are arranged, and the friction pad 17 on the actuating part side is pushed by the stepped piston 7 to prevent the disk 5 from moving. At the same time, the friction pad 17 on the non-actuating part side slides into contact with one side.
is also pushed by the reaction part 4 and comes into sliding contact with the other end surface of the disk 5, and the disk 5 is pressed against both friction pads 17, 17.
Braking is performed by being compressed by the

However, due to the hydraulic fluid supplied to the hydraulic pressure chamber 14 during braking, the piston seal 10 on the large diameter side deforms toward the disk 5 side, and the piston seal 11 on the small diameter side deforms in the opposite direction to the piston seal 10. , when the brake is released, the piston seal 10 on the large diameter side
The rollback force acts in the direction of arrow A in FIG. 6, the rollback force acts on the piston seal 11 on the small diameter side in the direction of arrow B in FIG. 7, and the rollback force of both piston seals 10 and 11 acts in the opposite direction. Therefore, the rollback amount of the piston seal 10 on the large diameter side is determined by the rollback amount of the piston seal 11 on the small diameter side.
The rollback of the stepped piston 7 is performed by setting the rollback amount to be larger than the rollback amount of the stepped piston 7.

[Problem that the invention attempts to solve]

However, even with the above arrangement, the rollback force of the piston seal 10 on the large diameter side is weakened due to the rollback force in the opposite direction by the piston seal 11 on the small diameter side, and the rollback of the stepped piston 7 is reduced. There was a problem.

Therefore, an object of the present invention is to provide a hydraulic disc brake in which the stepped piston can be quickly and reliably rolled back.

[Means for solving problems]

As a means to solve the above problems, in the present invention, a stepped cylinder having a large diameter part on the disk side and a small diameter part following it has a large diameter part in the front of the disk side and a small diameter part in the rear. The formed stepped piston is fitted in a liquid-tight and movable manner, and a first hydraulic pressure chamber is formed between the stepped portion of the stepped cylinder and the stepped portion of the stepped piston. A second hydraulic pressure chamber is defined between the attached piston and the rear end wall of the attached piston, and a first hydraulic pressure supply port and a second hydraulic pressure supply port are respectively connected to a hydraulic pressure supply device of a separate system to both hydraulic pressure chambers. In a hydraulic disc brake in which a port is opened, a stepped piston is actuated by hydraulic pressure from both ports to push a friction pad, and the disc is compressed by the friction pad to perform braking, the stepped cylinder Square seal grooves are provided around the large diameter portion and small diameter portion of the stepped cylinder, and a square piston seal is fitted into each of the seal grooves, and the piston seal of the small diameter portion of the stepped cylinder and the first liquid The piston is characterized in that a seal groove is provided around the outer periphery of the small diameter portion of the stepped piston between the pressure chamber and a liquid-tight piston seal is fitted into the seal groove.

[Effect]

By configuring as described above, the rollback directions of the piston seals provided in the large diameter portion and the small diameter portion are made to coincide with each other.

〔Example〕

An embodiment of the present invention will be described below based on FIG.

FIG. 1 shows an embodiment in which the present invention is applied to a two-system disc brake that performs braking by supplying hydraulic fluid from separate systems of hydraulic pressure supply devices. The disk 2 has a portion 22 and a reaction portion 23 integrally formed, and rotates together with the wheel by the bridge portion 21.
An actuating part 22 and a counter-actuating part 23 are disposed on both sides of the disk 24 across the disk 24, and are supported by a bracket 25 fixed to the vehicle body so as to be slidable in the disk axial direction with a sliding pin (not shown).

The actuating portion 22 is formed with a stepped cylinder 26, which has a large diameter portion 26a on the side of the disk 24 and a small diameter portion 26b in the rear portion following the large diameter portion 26a, which is stepped through a stepped portion 26c. A large diameter portion 27a is provided in front on the disk 24 side, and a small diameter portion 27c is provided in succession through a stepped portion 27b at the rear, and the rear end on the inner wall 26d side of the stepped cylinder 26 is closed with the rear end wall 27d. A stepped piston 27 is fitted in a liquid-tight and movable manner. Further, the stepped portion 26 of the large diameter portion 26a
A first hydraulic pressure supply port 28 is located near the small diameter portion 2
Second hydraulic pressure supply ports 29 are respectively opened near the inner wall 26d of 6b, and the hydraulic fluid supplied from hydraulic pressure supply devices (not shown) of separate systems through both ports 28 and 29, respectively, The stepped piston 27 is moved to the disk 24 side, and the stepped cylinder 26
The stepped portion 26c of the stepped piston 27 and the stepped portion 27 of the stepped piston 27
Similarly, the first hydraulic chamber 30 is located between the rear wall 26 and the rear wall 26.
d and the rear end wall 27d define a second hydraulic chamber 31, respectively.

Friction pads 33, 33 fixed to a pair of pad back plates 32, 32 are arranged on both sides of the disc 24, and the stepped piston 27 is moved to the disc 24 by the hydraulic fluid supplied to both the hydraulic pressure chambers 30, 31. The pad back plates 32, 32 are moved to the side, and the friction pads 33, 33 are thereby pressed against the disk 24.
Braking is performed by squeezing the

The stepped cylinder 26 has rectangular seal grooves 34 and 35 provided around the large diameter portion 26a and the small diameter portion 26b, respectively, and rectangular piston seals 36 and 37 are fitted into both seal grooves 34 and 35, respectively. On the other hand, in the stepped piston 27, a piston seal 39 such as an O-ring is fitted into a seal groove 38 provided around the small diameter portion 27c between the first hydraulic chamber 30 and the piston seal 37. The piston seals 36, 37 perform rollback of the stepped piston 27, and the piston seals 36, 37, 39 seal the hydraulic fluid.

Therefore, this two-system disc brake performs braking by supplying hydraulic fluid to the first hydraulic pressure chamber 30 and the second hydraulic pressure chamber 31 from the two hydraulic pressure supply ports 28 and 29 by hydraulic pressure supply devices of separate systems, respectively. When this is done, the piston seal 37 on the small diameter side closes both the hydraulic pressure chambers 30 and
1 is sealed, the pressure of the hydraulic fluid supplied to the second hydraulic pressure chamber 31 deforms toward the disk 24, and the piston seal 36 on the large diameter side deforms toward the disk 24 due to the pressure of the hydraulic fluid. Because it deforms,
When the brake is released, the stepped piston 27 is quickly and reliably rolled back by the rollback force caused by the deformation of both piston seals 36 and 37.

In addition, if the hydraulic pressure supply device or piping system that supplies hydraulic fluid to the first hydraulic pressure chamber 30 fails, the hydraulic fluid supplied from the second hydraulic pressure supply port 29 to the second hydraulic pressure chamber 31 The stepped piston 20 moves to perform braking, and the piston seal 3 on the small diameter side
7 is deformed toward the disk 24, so when the movement is released, the stepped piston 27 reliably rolls back due to the rollback force of the piston seal 37.

Furthermore, if the hydraulic pressure supply device or piping system that supplies hydraulic fluid to the second hydraulic pressure chamber 31 fails, the braking operation will cause the first hydraulic pressure supply port 28 to flow to the first hydraulic pressure chamber 30.
The stepped piston 27 is actuated by the hydraulic fluid supplied to perform braking. At this time, the piston seal 3 provided on the small diameter portion 27c of the stepped piston 27
9 deforms toward the second hydraulic pressure chamber 31 and seals the hydraulic fluid. Further, the piston seal 36 provided on the large diameter portion 26a of the stepped cylinder 26 is deformed toward the disk 24 by the pressure of the hydraulic fluid. Then, when the brake is released, the piston seal 37
This ensures that the stepped piston 27 rolls back while assisting the rollback of the piston seal 36.

[Effect of idea]

As described above, the present invention provides a two-system hydraulic disc brake equipped with a stepped piston, in which rectangular seal grooves are provided around the large diameter part and the small diameter part of the stepped cylinder, and each of the seal grooves is A square piston seal is fitted into the stepped cylinder, and a seal groove is provided around the outer periphery of the small diameter portion of the stepped piston between the piston seal of the small diameter portion of the stepped cylinder and the first hydraulic chamber, and a seal groove is provided around the outer periphery of the small diameter portion of the stepped piston. Since the liquid-tight piston seals are fitted, the deformation of the two square piston seals fitted in the square seal grooves during braking will occur when the braking is released.
This acts as a rollback force that urges the stepped piston in the return direction, allowing the stepped piston to be rolled back quickly and reliably, and the square piston seal and liquid-tight piston seal reliably seal the working fluid. be able to.

[Brief explanation of drawings]

Fig. 1 is a sectional front view showing an embodiment in which the present invention is applied to a two-system disc brake, Fig. 2 is a sectional front view of a conventional hydraulic disc brake, and Fig. 3 is a large diameter section of a stepped cylinder. FIG. 4 is a cross-sectional front view showing the piston seal fitted into the small diameter portion of the stepped cylinder. 20... Caliper body, 21... Bridge part, 22... Actuation part, 23... Reaction part, 24...
...Disc, 26...Stepped cylinder, 26a...
Large diameter part, 26b... Small diameter part, 27... Stepped piston, 27a... Large diameter part, 27c... Small diameter part, 33
...Friction pad, 34, 35...Seal groove, 3
6, 37... Piston seal, 38... Seal groove, 39... Piston seal.

Claims (1)

[Scope of utility model registration request] A stepped piston having a large diameter portion at the front of the disk side and a small diameter portion at the rear is fluid-tightly and movably inserted into a stepped cylinder having a large diameter portion on the disk side and a small diameter portion following the large diameter portion, A first hydraulic pressure chamber is provided between the stepped portion of the stepped cylinder and the stepped portion of the stepped piston, and a second hydraulic chamber is provided between the inner wall of the small diameter portion of the stepped cylinder and the rear end wall of the stepped piston. A first hydraulic pressure supply port and a second hydraulic pressure supply port, each of which is connected to a hydraulic pressure supply device of a separate system, are opened in both hydraulic pressure chambers, and the stepped piston is driven by the hydraulic pressure from both ports. In the hydraulic disc brake, a friction pad is actuated to push a friction pad, and the disc is compressed by the friction pad to perform braking. A square piston seal is fitted into each of the seal grooves, and a seal groove is provided on the outer periphery of the stepped piston small diameter portion between the piston seal of the stepped cylinder small diameter portion and the first hydraulic chamber. A hydraulic disc brake is characterized in that a liquid-tight piston seal is fitted into the seal groove.