JPH0319622Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a brake actuator that uses fluid pressure, specifically, a non-circular cylinder, an elastic bag inserted into the cylinder, and an elastic bag inserted into the cylinder. This invention relates to a proposal for increasing the protective effect of an elastic bag in an actuator which is configured with a cup-shaped retainer placed over the bag, and in which a friction material is brought into sliding contact with a disk rotor (hereinafter simply referred to as a disk) by the expansion force of the bag. .

[Technical background]

As a disc brake actuator, it presses the disc from both sides to generate braking force.
Traditionally, a combination of a circular cylinder and a hydraulically actuated piston is used.

However, in disc brakes using such actuators, the pressure receiving surface of the piston is circular, so it is difficult to obtain a large output within the limited radial space of the disc using one piston. If several small-diameter pistons are arranged on the same circumference, the disc circumferential dimension of the caliper body becomes large, and there are problems such as the hydraulic fluid communication path between the cylinders becomes complicated or the number of parts increases. It arises.

Therefore, the present applicant has proposed a technology that can solve these problems by simultaneously filing a patent application. As shown in FIGS. 2 to 5, this technique involves inserting an actuator 1 into a non-circular cylinder 3 formed in a carrier body 2, along the inner wall of the cylinder, and then inserting the actuator 1 into the cylinder along the inner wall thereof. It is composed of a membrane-like elastic bag 4 that clamps and holds a flange 4a deep inside the cylinder around the entire circumference, and a cup-shaped protective metal retainer 5 that covers the bag.
The friction material 6 is brought into sliding contact with the disk D by the expansion force of the elastic bag 4 due to the working fluid pressure introduced into the cylinder, and has the following features. Its features are: (1) Increases the pressure receiving area within a limited space;
It is possible to increase the braking force, and therefore the restrictions on the brake installation space are relaxed.

(2) It is easy to mold a bag made of elastic material, and the material cost is lower than that of a piston.

(3) There is no need for precision machining of the sliding surface, which is required when using a piston, and the cast cylinder can be used as is.

(4) Since the desired output can be secured without increasing the number of cylinders, there is no need to process a working fluid pressure communication path and the number of parts can be reduced.

Note that FIGS. 2 to 5 show disk D (second
This represents a floating type disc brake in which an actuator presses one side 6 of the friction materials facing each other with the center of the figure 6, and the other friction material 6' is pressed by the outer claw of a caliper that moves in the direction of the disk axis due to reaction force. 7 is a sealing plate that clamps the flange 4a of the bag 4 in the inner part of the cylinder 3, and 8 is a fluid pressure introduction port 9.
A through hole 10 is provided in the sealing plate to communicate the internal chamber of the cylinder with the communication port 12 to the bleed valve 11.
14 is a sealing material that seals around the joint part of the communication hole, 14 is a sealing material that seals around the sealing plate insertion part, and 15 in FIG.
1 is a friction material gap adjustment mechanism including a retraction plate 15a interposed between the back plate of the friction material 6 and the retainer 5, and 16 in FIGS. 3 and 5 guides the movement of the caliper in the disk axial direction. The slide part is shown. The gap adjustment mechanism 15 is connected to the cylinder 3
A housing 15d and a sleeve 15 are placed on retraction bushes 15c, which are provided at two locations on the retraction side and the retraction side of the disk, and slide on the retractor pin 15b following wear of the friction material.
A gap equal to the gap Δ× provided between the housing 15d and the seat plate 15f is secured between the disk and the friction material by the force of the spring 15g suspended between the disk and the seat plate 15f supported by the disk. It's becoming like that. The slide portions 16 are also provided on the rotation side and the rotation side of the disk with the cylinder 3 as a reference. As shown in FIG.
Rubber boot 1 is inserted into the through hole provided in torque member 17.
This is a well-known structure inserted through 8.

[Issues of this invention]

Now, moving on to the main topic, in order to reliably protect the bag 4 from fluid pressure regardless of the wear status of the friction material, the actuator 1 has a peripheral wall 5a of the retainer 5 as shown in FIG. It is necessary to insert the retainer between the peripheral wall 4b of the bag 4 and the inner wall of the cylinder 3, and further to interpose the bottom wall 5d of the retainer between the bottom wall 4c of the bag 4 and the back plate of the friction material 6. However, when fluid pressure is introduced into the inner chamber of the cylinder in this state, a gap a is created between the inner wall of the cylinder 3, the bag 4, and the retainer 5 due to the thickness of the retainer. There is a risk that a stress concentration zone will be formed in the area A and the bag 4 will be damaged by the edge 5c of the open end of the retainer.

Furthermore, when the pressure is removed, the retainer 5 is forcibly pulled back while sliding on the peripheral wall of the bag 4 due to the action of the gap adjustment mechanism 15, but even during this movement, the edge 5
c causes damage to the bag 4, which poses a problem in the durability of the actuator.

The present invention aims to eliminate this problem.

[Means to solve the problem]

As a means to eliminate the above-mentioned problems, this invention provides the above-mentioned disc brake actuator which is composed of a non-circular cylinder, a membrane-like elastic bag inserted into the cylinder, and a cup-shaped retainer placed over the bag. As shown in FIG. 1, in the space defined by the inner wall of the cylinder 3, the retainer 5, and the elastic bag 4, one end along the edge of the peripheral wall of the retainer has at least the same thickness as the peripheral wall of the retainer. ,
The other end is characterized by providing a back-up spring 20 with a corner edge removed on the inner surface. It is desirable that this ring 20 be glued to the open end of the retainer 5, but even if it is not glued, when fluid pressure is introduced into the cylinder, it will be pushed by the bag that expands due to the pressure and move forward together with the retainer. On the other hand, when the pressure is removed, it is pushed back by the retainer, so no particular problem arises.

Note that the back-up spring 20 may be made of metal, but considering the protection of the inner wall of the cylinder, it is preferable to select plastic, hard rubber, etc. rather than metal.

Also, the thickness _H1 of the side in contact with the retainer is
It is desirable that the thickness be slightly larger than the thickness _H2 of the retainer peripheral wall 5a.

In addition, as shown in the figure, the corner edge on the inner surface of the other end is removed by adding a curved surface 21 that expands in diameter on the inner side of the cylinder 3, and a straight inclined surface is added to replace the curved surface 21. May be removed.

〔effect〕

As mentioned above, when the gap created between the inner wall of the cylinder, the retainer, and the elastic bag is filled with a back-up spring, the expansion of the bag into the gap due to fluid pressure is eliminated, so that the part to the bag is Also, since the bag does not come into direct contact with the edge of the retainer, there is no fear that the bag will be damaged by the retainer during braking or depressurization. Therefore, according to this invention, a large output can be obtained in a small space, and the practicality of a highly durable disc brake can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the main parts of the actuator of this invention, FIG. 2 is a cross-sectional view of a disc brake equipped with the actuator to be improved by this invention, cut at the center along the disc axis, and FIG.
The figure is a partially cutaway front view, Figure 4 is a partially cutaway plan view, Figure 5 is a cross-sectional view of the caliper slide, and Figure 6 explains problems with the actuator used in the example disc brake. FIG. 1... Actuator, 2... Caliper body, 3... Non-circular cylinder, 4... Elastic bag,
5...Cup-shaped retainer, 7...Sealing plate, 14...
... Sealing material, 20 ... Backup spring, 21
……curved surface.

Claims (1)

[Scope of utility model registration request] A non-circular cylinder formed in a carrier body, and a membrane-like elastic bag inserted into the cylinder along its inner wall and clamped and held in the depths of the cylinder around the entire circumference of the open end wall. and a cup-shaped retainer whose peripheral wall is inserted over the bag and between the inner wall of the cylinder and whose bottom wall connected to the peripheral wall is interposed between a back plate of the friction material, and when the bag is introduced into the cylinder. In a disc brake actuator configured to receive fluid pressure on the inner surface and press the friction material through the retainer to move forward and come into sliding contact with the disc rotor, the inner wall of the cylinder, the retainer,
A back-up spring is provided in the gap defined by the three parts of the elastic bag, and one end along the peripheral wall of the retainer has at least the same thickness as the peripheral wall of the retainer, and the other end has a corner edge on the inner surface side removed. An actuator for disc brakes characterized by: