JP2002250379A - Disc brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a pulsation damping effect (damper effect) of brake fluid pressure in a disc brake. SOLUTION: In this disc brake for braking a disc rotor 11 by frictional engagement of a pad 13 to the disc rotor 11 by pressing the pad 13 because a pressing piston 16 assembled to a cylinder bore 15a of a caliper 15 is pushed in the cylinder shaft direction by the brake fluid pressure supplied to a fluid pressure chamber R1, a second fluid pressure chamber R2 communicated with the fluid pressure chamber R1 and a sealed air pressure chamber Ro are formed within the pressing piston 16, a differential piston 21 capable of reducing the sealed air pressure chamber Ro according to a rise in fluid pressure within the fluid pressure chamber R1 is assembled to the pressing piston 16 and an energizing means (spring 22) for energizing the differential piston 21 toward a fixed position within the pressing piston 16 is assembled to the pressing piston 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk brake used as a wheel brake of a vehicle, and more particularly to a disk rotor having an axial deflection and a disk rotor thickness when a brake pedal is lightly depressed during high-speed running of the vehicle. The axial direction of the piston (ie, the pressing piston that is pushed in the cylinder axis direction by the brake fluid pressure supplied to the hydraulic pressure chamber that is attached to the cylinder bore of the caliper and that presses the pad) due to the variation in height The present invention relates to a disc brake capable of reducing vibration.

[0002]

2. Description of the Related Art The pulsation of brake fluid pressure caused by the above-mentioned axial vibration of a pressing piston is transmitted to a brake pedal through a brake pipe to give a driver discomfort,
Axial vibration of the pressing piston may cause fluctuations in the rotational torque of the disk rotor, causing vehicle vibration.

In order to solve such a problem, Japanese Patent Laid-Open Publication No.
In the disc brake disclosed in Japanese Patent No. 87159, a stepped piston is axially movable in a stepped inner hole formed in a pressing piston and communicated with a hydraulic chamber at a small diameter portion. A seal ring is interposed between the small-diameter portion of the piston and the small-diameter portion of the stepped inner hole, and a stopper that defines the axial movement amount of the stepped piston is assembled to the large-diameter portion of the stepped inner hole, A damper configuration is employed in which a stepped piston is urged by a damper spring toward the step of the stepped inner hole.

[0004]

In the damper configuration disclosed in the above publication, the damper effect is obtained by the axial movement of the stepped piston, but the axial movement of the stepped piston is controlled only by the damper spring. Therefore, the pulsation damping effect (damper effect) of the brake fluid pressure is small and there is room for improvement.

[0005]

According to the present invention, in order to solve the above-mentioned problems, a pressing piston attached to a cylinder bore of a caliper is pushed in the cylinder axial direction by brake hydraulic pressure supplied to a hydraulic chamber. By pressing the pad, the pad frictionally engages with the disk rotor to brake the disk rotor.
A second hydraulic chamber communicating with the hydraulic chamber and a sealed air pressure chamber are formed in the pressing piston, and the differential piston capable of decreasing the sealed air pressure chamber in response to an increase in the hydraulic pressure in the hydraulic chamber presses the differential piston. A biasing means for biasing the differential piston toward a fixed position in the pressing piston is mounted on the pressing piston while being mounted on the piston (the invention according to claim 1).
There is a feature.

In this case, a throttle is provided in a communication passage for communicating the two hydraulic chambers (the invention according to claim 2).
In these cases, it is desirable that the differential piston has a plurality of hydraulic pressure receiving surfaces (the invention according to claim 3), and in these cases, the differential piston is arranged in the cylinder axial direction of the differential piston. (The invention according to claim 4) is desirably set to the set value.

[0007]

In the disk brake according to the present invention (the invention according to claim 1), the axial movement of the pressing piston due to the axial runout of the disk rotor and the variation in the thickness of the disk rotor during braking is caused. Vibration occurs,
When the brake fluid pressure in the hydraulic chamber fluctuates and pulsates, the brake fluid pressure in the second hydraulic chamber also fluctuates and pulsates, and the differential piston moves in the axial direction under the action of the urging means, and the differential piston moves. The volume of the sealed pneumatic chamber changes with the axial movement of the moving piston. Therefore, a damper effect is obtained by the differential piston moving in the axial direction under the action of the biasing means, and a damper effect by the volume change of the sealed air pressure chamber accompanying the axial movement of the differential piston is obtained. As a result, the damper effect can be enhanced.

In implementing the present invention, when a throttle is provided in the communication passage for communicating the two hydraulic chambers (in the case of the invention according to claim 2), the differential piston is operated under the action of the urging means. In addition to the damper effect due to the axial movement of the differential piston and the damper effect due to the volume change of the sealed air pressure chamber due to the axial movement of the differential piston, a communication path for communicating both hydraulic pressure chambers is provided. The damper effect by the aperture can be obtained, and the damper effect can be further enhanced.

Further, when the present invention is carried out, the differential piston has a plurality of hydraulic pressure receiving surfaces.
In the case of the invention according to (1), the degree of freedom is increased when setting the dimensions of each part of the differential piston, so that the damper effect can be set optimally. Further, when implementing the present invention, if the amount of movement of the differential piston in the cylinder axis direction is defined as a set value (in the case of the invention according to claim 4), the hydraulic pressure range in which a damper effect can be obtained. Can be set accurately.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a disk brake according to the present invention. The disk brake according to this embodiment has a disk rotor 11 that rotates integrally with wheels (not shown), and is disposed on both sides of the disk rotor 11, respectively. And an inner pad 13 supported on a mounting 12 (fixed by bolts to a non-rotating portion (not shown) of the vehicle at the right side of the disk rotor 11 in the figure) so as to be slidable in the rotor axis direction and capable of receiving a brake torque. And outer pad 14 and mounting 12
The caliper 15 includes a caliper 15 slidably mounted in the rotor axis direction via a pair of pin slide means (not shown), and a pressing piston 16 mounted to a cylinder bore 15 a formed in the caliper 15. Note that the mounting 12 and the caliper 15 are formed so as to straddle the disk rotor 11.

The caliper 15 has a bottomed cylinder bore 15a on the inner side (right side in FIG. 1) and an arch-shaped reaction arm 15b on the outer side for pressing the outer pad 14 toward the disk rotor 11. I have. Cylinder bore 1
5a is open toward the disk rotor 11, and a pressing piston 16 for pressing the inner pad 13 toward the disk rotor 11 is inserted therein through a seal ring 17 so as to be slidable in the axial direction. A hydraulic chamber R1 is formed at the bottom of the cylinder bore 15a. A boot 18 is mounted between the open end of the cylinder bore 15a and the outer periphery of the protruding portion of the piston 16.

The hydraulic pressure chamber R1 communicates with a hydraulic pressure chamber (not shown) of the master cylinder via a brake pipe (not shown) at a port (not shown) provided in the caliper 15.
Therefore, when the brake pedal (not shown) is depressed and brake fluid pressure is supplied from the master cylinder to the hydraulic chamber R1 through the brake pipe, the pushing piston 16 is pushed toward the disk rotor 11 and the inner pad 13 is pushed. Is pressed toward the disk rotor 11, and the caliper 15 is moved by the reaction force, and the reaction force arm 15 b presses the outer pad 14 toward the disk rotor 11. 11
And frictionally engage with the disk rotor 11 to pinch and brake the disk rotor 11.

By the way, in the first embodiment,
A differential piston 21 and a spring 22
And the bush 23 are assembled. Differential piston 21
Has a first large-diameter portion 21a, a second large-diameter portion 21b, and a small-diameter portion 21c, and has an annular groove 21d and a communication passage 21e.
The bush 23 and the pressing piston 16
A second hydraulic chamber R2 communicating with the hydraulic chamber R1 and a sealed atmospheric pressure chamber Ro are formed therein. The differential piston 21 has an annular stopper stepped portion 21f. The stopper stepped portion 21f abuts on the annular projection 16c of the pressing piston 16, whereby the differential piston 21 is shown in the cylinder axial direction. The movement to the right is regulated, and the movement amount of the differential piston 21 is regulated to a set value.

The first large diameter portion 21a is fitted in the large diameter inner hole 16a of the pressing piston 16 via a seal ring 24 so as to be slidable in the axial direction. The second large-diameter portion 21b is fitted to the inner hole 23a of the bush 23 via a seal ring 25 so as to be slidable in the axial direction. The small diameter portion 21c is fitted to the small diameter inner hole 16b of the pressing piston 16 via a seal ring 26 so as to be slidable in the axial direction. Annular groove 21d
Communicates with the hydraulic chamber R1 through the communication passage 21e,
The pressing piston 16 and the bush 23 form a second hydraulic chamber R2.

The spring 22 is an urging means for urging the differential piston 21 toward a fixed position in the pressing piston 16 (a position where the differential piston 21 contacts the bush 23). And a predetermined assembly load (preliminary load) is applied to them. The bush 23 is liquid-tightly fitted and fixed to an opening end (left end in the drawing) of the large-diameter inner hole 16a of the pressing piston 16, and the diameter of the inner hole 23a is large-diameter inner hole of the pressing piston 16. The diameter of the differential piston 21 is smaller than the diameter of the differential piston 16a and also has a function of preventing the differential piston 21 from coming off.

In the above-described differential piston 21, the first large diameter portion 21a, the second large diameter portion 21b, and the small diameter portion 21c are hydraulic pressure receiving surfaces, and the first large diameter portion 21a is also an air pressure receiving surface. Therefore, the differential piston 21 is (D1-D2) ×
By satisfying Pf2−D3 × Pf1> Fs + (D1−D3) × Pa, it is possible to move to the right in the drawing and decrease the sealed pressure chamber Ro in accordance with an increase in the hydraulic pressure in the hydraulic chambers R1 and R2. D1 described above is a cross-sectional area of the first large diameter portion 21a,
D2 is the cross-sectional area of the second large-diameter portion 21b, D3 is the cross-sectional area of the small-diameter portion 21c, Pf1 is the hydraulic pressure in the hydraulic chamber R1, and Pf2 is the hydraulic pressure in the second hydraulic chamber R2. Pressure and Pa
Is the pressure in the sealed pressure chamber Ro, and Fs is the spring 2
2 is the assembly load.

In the first embodiment configured as described above, the axial vibration of the disk rotor 11 and the thickness of the disk rotor 11 during braking while the disk rotor 11 is rotating (running state of the vehicle). When the axial vibration of the pressing piston 16 occurs due to the variation in the hydraulic pressure and the brake hydraulic pressure in the hydraulic pressure chamber R1 fluctuates and pulsates, the second hydraulic pressure chamber R2
The brake fluid pressure in the inside also fluctuates and pulsates, and the differential piston 21 starts to move at a fluid pressure exceeding the assembly load of the spring 22 and the stopper step 21f provided on the differential piston 21 causes the annular projection 16c of the pressing piston 16 to move. When the differential piston 21 moves within the set hydraulic pressure range until the differential piston 21 contacts the differential piston 21 in the axial direction under the action of the spring 22, the sealed air pressure chamber Ro is Change. Accordingly, a damper effect is obtained by the differential piston 21 moving in the axial direction under the action of the spring 22, and the sealed air pressure chamber Ro changes in volume (increases and decreases in pressure) with the axial movement of the differential piston 21. )
Accordingly, the damper effect can be obtained, and the damper effect can be enhanced.

In the first embodiment, the differential piston 21 has a plurality of hydraulic pressure receiving surfaces (the first large-diameter portion 21a,
Since the second large-diameter portion 21b and the small-diameter portion 21c) are provided, the degree of freedom in setting the dimensions of the differential piston 21 is increased, and the damper effect can be optimally set. Further, since the acting force for moving the differential piston 21 in the axial direction is obtained by the difference between the plurality of hydraulic pressure receiving surfaces, it is easy to reduce the assembly load of the spring 22.
Further, the operation of the differential piston 21 can be easily changed by changing the assembly load or the spring constant of the spring 22, so that only specific brake hydraulic vibration can be accurately suppressed.

Further, in the first embodiment, the stopper step 21f provided on the differential piston 21 abuts on the annular projection 16c of the pressing piston 16, so that the differential piston 21 is moved rightward in the cylinder axis direction in the figure. In the cylinder axis direction of the differential piston 21 is regulated to a set value, so that the upper limit of the hydraulic pressure range in which the damper effect can be obtained (high pressure value) Can be set accurately. Note that the lower limit of the hydraulic pressure range in which the damper effect can be obtained can be accurately set by the load of the spring 22 being assembled.

In the first embodiment, the hydraulic chamber R1
And the second hydraulic chamber R2 are communicated through the communication passage 21e so that the hydraulic pressures of the hydraulic chamber R1 and the second hydraulic chamber R2 are always substantially equal to each other, as shown in FIG. As in the second embodiment, a throttle 21e1 is provided in the communication passage 21e,
It is also possible to carry out the embodiment in such a manner that a difference can be generated between the hydraulic pressure of the hydraulic chamber R1 and the hydraulic pressure of the second hydraulic chamber R2.

In the second embodiment, the damper effect caused by the axial movement of the differential piston 21 under the action of the spring 22, and the sealed air pressure chamber Ro associated with the axial movement of the differential piston 21 are reduced. In addition to the damper effect due to the volume change, the damper effect by the throttle 21e1 provided in the communication passage 21e that connects the two hydraulic chambers R1 and R2 can be obtained, and the damper effect can be further enhanced.

In each of the above embodiments, the communication path 21e is provided in the differential piston 21 and the communication path 21e is provided.
The hydraulic pressure chamber R1 and the second hydraulic pressure chamber R2 are communicated with each other, but instead of providing the communication passage 21e in the differential piston 21 as in the third embodiment shown in FIG. It is also possible to provide a communication passage 16d in the piston 16 and to communicate the hydraulic chamber R1 and the second hydraulic chamber R2 through the communication passage 16d.

[Brief description of the drawings]

FIG. 1 is a central vertical sectional side view showing a first embodiment of a disc brake according to the present invention.

FIG. 2 is a central longitudinal sectional side view showing a second embodiment of the disc brake according to the present invention.

FIG. 3 is a central vertical sectional side view showing a third embodiment of the disc brake according to the present invention.

[Explanation of symbols]

11 ... disk rotor, 12 ... mounting, 13 ...
Inner pad, 14 ... outer pad, 15 ... caliper,
15a ... Cylinder bore, 16 ... Pressing piston, 16a ...
Large-diameter inner hole, 16b: small-diameter inner hole, 16c: annular projection, 21
... differential piston, 21a ... first large diameter part, 21b ... second large diameter part, 21c ... small diameter part, 21d ... annular groove, 21e ... communication path, 21e1 ... throttle, 21f ... stopper step part, 22 ... spring ( 23: bush, R1: hydraulic chamber, R2: second hydraulic chamber, Ro: sealed pressure chamber.

Claims (4)

[Claims] 1. A pressing piston mounted on a cylinder bore of a caliper is pushed in the cylinder axial direction by brake hydraulic pressure supplied to a hydraulic pressure chamber to press a pad.
In a disc brake in which a pad frictionally engages with a disc rotor to brake the disc rotor, a second hydraulic chamber communicating with the hydraulic chamber and a sealed air pressure chamber are formed in the pressing piston to form the hydraulic pressure. A biasing means for assembling a differential piston capable of reducing the sealed air pressure chamber in response to a rise in the hydraulic pressure in the chamber to the pressing piston and biasing the differential piston toward a fixed position in the pressing piston. A disc brake which is assembled to the pressing piston. 2. The disc brake according to claim 1, wherein a throttle is provided in a communication passage that connects the two hydraulic pressure chambers. 3. The disc brake according to claim 1, wherein said differential piston has a plurality of hydraulic pressure receiving surfaces. 4. The disc brake according to claim 1, wherein an amount of movement of the differential piston in a cylinder axis direction is set to a set value.