JPH0617701B2 - Actuator for disk break - Google Patents

Abstract

PURPOSE:To enable miniaturization by constituting an actuator utilizing an elastic bag and making a cylinder in a noncircular shape so that the pressure receiving area of fluid pressure can be increased to the maximum in a limited space. CONSTITUTION:A caliper body 1 is composed of a base 3 provided with a noncircular cylinder 2 and a cover 4 bolted thereto. An actuator 10 consists of a cylinder 2, a bag 11 of membranous elastic body inserted therein, and a retainer 12 being covered on the outer surface of this bag. Being opened at one end, the bag 11 is held so as to be inserted in the recess of the cylinder all around the periphery. Since the sectional shape of the cylinder can be made in a rectangular form by the adoption of the bag 11, the pressure receiving area of fluid pressure can be increased in a limited space, enabling the miniaturization.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator for a disc brake that operates by fluid pressure, and more particularly to an actuator that can increase the braking force without increasing the size of the brake.

[Conventional technology and its problems]

For a disc brake that generates a braking force by pressing a disc rotor (hereinafter simply referred to as a disc) from both sides, a braking force proportional to (1) input is obtained. (2) Since the muddy water is shaken off by the centrifugal force of the disk, it has good water recovery properties. (3) There is an advantage that maintenance such as replacement of the friction material is easy.

By the way, as an actuator for a disc brake, a combination of a circular cylinder and a hydraulically actuated piston has been traditionally adopted, but this actuator has a limited radial space because the fluid pressure receiving surface is circular. It is difficult to obtain a large output in a vehicle, and therefore, a vehicle with a narrow installation space where a conventional disc brake is used as a drum brake, such as a wheel size is small, and a part of the steering mechanism is built in. If you want to take advantage of the above advantages by mounting it on a vehicle such as a small forklift truck that replaces the drum brake, and due to space limitations, arrange several small-diameter pistons on the same circumference to obtain the required braking force. Will be secured. However,
When several pistons are assembled in one caliper body, the size of the caliper body in the disk circumferential direction becomes large, and it may be impossible to use a disk brake in terms of space.

Also, the connection path of hydraulic fluid between cylinders becomes complicated,
The effect on the manufacturing cost that the number of parts increases cannot be ignored.

SUMMARY OF THE INVENTION In order to eliminate such problems, an object of the present invention is to provide an actuator that maximizes the annular space between the wheel and the hub, which can increase the braking force without increasing the size of the caliper body.

[Means for solving problems]

In order to achieve the above object, in the present invention, the cylinder formed on the caliper body has a non-circular shape. In addition, a bag made of a film-like elastic body with one end opened was inserted into the cylinder along the inner wall, and one side wall of this bag was held in the inner part of the cylinder in a slidable manner over the entire circumference. Furthermore, the bag of the elastic body, the peripheral wall is inserted between the inner wall of the cylinder, the bottom wall connected to the peripheral wall is covered with a cup-shaped retainer interposed between the back plate of the friction material,
The expansion force of the bag, which receives the fluid pressure on the inner surface, is transmitted to the friction material through the retainer, and the friction material advances the friction material to make sliding contact with the disc.

In the actuator configured as described above, the cross-sectional shape of the cylinder can be made rectangular, so that the fluid pressure receiving area is larger than that of the circular pressure receiving surface having the same radial and circumferential dimensions of the disk. The braking force determined by the pressure receiving area also increases. Therefore, the required braking force can be secured without dividing the actuator into a plurality, and the limitation of the assembling space is eased.

〔Example〕

The attached drawings show an example of application of the present invention to a floating disc brake.

Reference numeral 1 in FIGS. 1 to 3 denotes a caliper body that straddles the disk D (FIG. 1). The body includes a base 3 having a non-circular cylinder 2 on one side of the disk and a cover 4 bolted to the base 3. Become. Reference numeral 5 denotes a friction material 7, 7 that holds a caliper body slidably in the disc axial direction via slide portions 6, 6'provided on the disc inflow side and the outflow side, and that is opposed to both sides of the disc. ′ Is also a torque member for slidably holding it in the same direction, and 8 is a friction material gap adjusting mechanism including a retraction plate 9.

The actuator 10 of the present invention includes the cylinder 2 and
It comprises a bag 11 made of a film-like elastic body inserted therein and a retainer 12 for covering the outer surface of the bag.

As shown in FIG. 2, the cylinder 2 has a rectangular shape, and a large-diameter portion 13 is formed in the inner portion of the cylinder 2 so as to extend to the cover mounting surface of the base portion.

The bag 11 has one end opened, and the flange 1 is attached to the opening side end of the peripheral wall 11a along the inner wall of the cylinder 2 as shown in the figure.
1b is attached, and a cup-shaped one in which a bottom wall 11c for closing the opening of the cylinder is continuously provided at the end opposite to the peripheral wall is preferable.
The flange 11b is inserted between the end surface of the large diameter portion 13 and the large diameter portion and sandwiched between the sealing plate 14 pressed by the cover 4.

The retainer 12 has a cup shape in which a bottom wall 12b is connected to one end of a peripheral wall 12a inserted between the bag 11 and the cylinder inner wall, and the bottom wall 12b is located between the bag 11 and the back plate 7a of the friction material 7. To cover the bag. If the retainer is provided with rigidity that is not deformed by the pressure of the working fluid, and a metal plate is press-molded, the requirement can be met.

Reference numeral 15 is a fluid pressure introduction hole provided in the cover 4, and this hole communicates with the inner chamber of the cylinder 2 through a through hole 16 provided in the sealing plate 14 that closes one end of the cylinder 2. Further, in order to remove air from the cylinder, the sealing plate 14 is provided with a groove 19 communicating with a communication hole 18 to the bleeder valve 17. Further, at the joint interface of the cover 4, in order to prevent leakage of fluid pressure, a seal 20 surrounding the connecting portion of the communication hole 18,
An O-type seal 21 is provided between the cover 4 and the chamfered outer periphery of the sealing plate 14 to seal the cylinder portion. Therefore, the inside of the cylinder 2 is kept in a sealed state, and When pressure is introduced, the bag 11 becomes a balloon and swells toward the disk side where movement is not restricted, and presses the friction material.

Next, the gap adjusting mechanism 8 for the friction material will be described. This adjusting mechanism is provided at two positions on the inflow side and the outflow side of the disk with reference to the cylinder 2. The two adjusting mechanisms have the same structure, and as shown in FIG. 3, the retractor plate 9 sandwiched between the friction material 7 and the retainer 12, and the retractor in the disc axial direction held by the carrier body 1. The pin 22, a sleeve 23 having one end fixed to the plate 9 and surrounding the pin 22, and an outer end fitted to the tip of the pin 22 so as to generate a sliding resistance slightly larger than the biasing pressure of the retractor spring described later. It comprises a retraction bush 24 abutting against the plate 9, and a retractor spring 28 suspended between a housing 25 covered by the bush and a seat plate 27 supported by a snap ring 26 on the inner surface of the sleeve 23. The seat plate 27 that follows 9 contacts the housing 25 and slides the bush against the pin 22 by an amount corresponding to the wear amount of the linings 7b and 7b '. Is it de, to automatically separate the always constant quantity △ X only friction material from the disk to the removal pressure time. In the case of a floating disc brake, ΔX is the sum of the amounts by which the pair of friction materials 7, 7 ′ are separated from the disc, and the gap between each friction material and the disc is kept at ΔX / 2. Reference numeral 29 is a sealing material that seals the outer circumference of the sleeve.

In the floating disc brake, the slide parts 6 and 6'press one friction material with an actuator and the other friction material with the outer claw of the caliper moved by the reaction force.
Since it is necessary to move the caliper body to the actuator side in order to transmit the reaction force to the other friction material and to absorb the wear amount of the lining, a known structure may be used as the moving guide. In the figure, both are constructed as shown in FIG. 4, that is, the stem 30a of the slide pin 30 screwed to the caliper body 1 is slidably inserted into the rubber pin boot 32 incorporated in the through hole 31 of the torque member 5. One of them is configured as shown in FIG. 4, and the other is provided with a guide sleeve which is directly inserted into the hole of the torque member on the stem of the slide pin and whose both ends are sealed with boots.

Reference numeral 33 is a guide groove for the wear members 7 and 7'provided on the torque member, and 34 is a torque receiving surface for abutting the side surface of the back plate of the wear member.

In addition, the actuator of the present invention is a carrier floating type,
Regardless of fixed type, it can be applied to all disc brakes that use fluid pressure as an operation source.

〔effect〕

As described above, according to the present invention, the fluid pressure introduced into the non-circular cylinder is applied to the inner surface of the elastic bag, and the expansion force of the bag is used to bring the friction material into sliding contact with the disk. As a result, it becomes possible to increase the braking force by maximizing the fluid pressure receiving area within a limited space. That is, a large output can be obtained with a small disc brake, and therefore, the space limitation when incorporating the brake is relaxed.

Further, the pressure receiving body (bag) formed by the elastic body is easy to mold, the material is cheaper than the piston, and the friction material is pressed by utilizing the expansion and storage of the pressure receiving body, so that the piston is No need for precision machining of the sliding surface when using it, the casting cylinder can be used as it is, there is no need to process the working fluid pressure communication path because there is only one cylinder, and the number of other parts is also Since it can be reduced in number, it is advantageous in terms of manufacturing and cost of the brake.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a disc brake adopting the actuator of the present invention taken along a line in the disc axial direction, FIG. 2 is a partially cutaway front view thereof, and FIG. A plan view of the notched state, FIG. 4 is A of FIG.
It is a sectional view taken along the line A. DESCRIPTION OF SYMBOLS 1 ... Caliper body, 2 ... Cylinder, 3 ... Base part, 4 ... Cover, 5 ... Torque member, 6, 6 '... Slide part, 7,
7 '... Friction material, 8 ... Friction material gap adjusting mechanism, 10 ... Actuator, 11 ... Elastic bag, 12 ... Retainer, 14
… Sealing plate, 21… O type seal

Claims (1)

[Claims] 1. A non-circular cylinder formed in a carrier body, and a film-like member which is inserted into the cylinder along the inner wall thereof and which holds an open edge wall at the inner part of the cylinder in the depth direction of the cylinder. An elastic bag and a cup-shaped retainer that covers the bag and inserts the peripheral wall between the inner wall of the cylinder and the bottom wall connected to the peripheral wall with the back plate of the friction material. An actuator for a disc brake configured to receive the fluid pressure introduced into the cylinder on its inner surface, press the friction material through a retainer forward, and bring it into sliding contact with the disc rotor.