JPS5913381Y2 - Automotive drum brake - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a drum brake for an automobile.

In detail, when removing and installing the shoe return spring, a tool is used to remove the wheel cylinder dust-proof boots (hereinafter simply referred to as "dust-proof boots").

) It is an object of the present invention to provide a drum brake for an automobile that can prevent damage to the drum brake.

Drum brakes for automobiles have one end of the brake shoe in contact with an anchor and the other end in contact with a piston of a wheel cylinder, and the actuation of this piston causes the brake shoe to slide against the inner peripheral surface of the brake drum. be.

In this drum brake, a shoe return spring is usually provided to prevent the brake shoe from remaining in sliding contact with the brake drum even after the brake is released.

Therefore, when it becomes necessary to replace the brake shoes due to wear of the brake lining or the like, the shoe return spring must be removed and attached.

However, this shoe return spring is generally not hooked to the end of the brake shoe on the wheel cylinder side, and moreover, the shoe return spring can be installed and removed from the gap between the hub and the wheel cylinder while the hub for mounting the brake drum, etc. is still attached. Conventionally, the removal/detachment tool tends to interfere with the wheel cylinder, and in this case, the dust-proof boot is caught between the wheel cylinder body and the removal/detachment tool and is damaged. The shoe return spring is inserted into the mounting hole where the shoe return spring is hung, and the removal tool is rotated around the mounting hole, but at that time, the removal tool comes into contact with a nearby dustproof boot and damages it. There were times when I was forced to do so.

Shoe return springs generally have a large spring constant and are quite difficult to attach and detach, so care is often taken to avoid interference between the tool and the wheel cylinder.

If the dust-proof boot is damaged, it will require unnecessary time and money to replace it, and if the damage is overlooked, dust and dirt may form in the fitting part between the wheel cylinder and the piston.
This poses a serious problem in that dust, muddy water, etc. may enter the wheel piston and interfere with normal operation of the wheel piston.

The purpose of this invention is to solve the above-mentioned problems in conventional automobile drum brakes, and it consists of a backing plate, a brake shoe movably attached to the backing plate, and a brake shoe attached to one end of the brake shoe. The contacting pistons are slidably fitted,
a wheel cylinder that presses the brake shoe against a brake drum that rotates with the wheel; a dustproof boot that is installed between an end of the wheel cylinder and the piston and covers a fitting portion of the wheel cylinder and the piston; In a drum brake for an automobile including a return spring that is hung in a mounting hole formed at the end of the shoe on the wheel cylinder side and returns the brake shoe to its original position, the dustproof boot is located farthest from the backing plate. In the vicinity of the part,
a guard portion extending from the rim portion of the brake shoe toward the inner circumferential side in the radial direction of the backing plate and crossing substantially the entire width of the dustproof boot in the axial direction of the wheel cylinder;
It is characterized in that it is provided integrally with the rim portion.

Hereinafter, the configuration and effects of the present invention will be explained in more detail based on examples.

In FIG. 1, a pair of brake shoes, a reaching shoe 1 and a trailing shoe 2, are attached to a backing plate 4 by a hold down spring 3.

The brake shoes 1 and 2 have one end in contact with the anchor 5 and the other end in contact with a piston slidably fitted in the wheel cylinder 6, and are formed at the end on the side of the wheel cylinder 6. A shoe return spring 7 is hung in the mounting hole 1b and urged in a direction toward each other.

Therefore, when brake fluid pressure is not supplied to the wheel cylinder 6, the brake shoes 1 and 2 are returned to their original positions according to the urging force of the return spring 7.

As shown in FIG. 2, the leading shoe 1 is attached to a rim 1a.
The wheel cylinder side end of the leading shoe 1 is extended in the longitudinal direction of the leading shoe 1, and the part that interferes with the wheel cylinder 6 is cut out, and the wheel cylinder 6 side end of the rim 1a of the leading shoe 1 is a dustproof boot. A guard portion 1C is formed to extend so as to be located on the hub side 10 near 8.

That is, the guard portion 1C extends from the rim 1a of the leading shoe 1 toward the inner circumferential side in the radial direction of the backing plate 4 at a position near the part of the dust-proof boot 8 farthest from the backing plate 4, and extends from the rim 1a of the leading shoe 1 toward the inner circumferential side in the radial direction of the backing plate 4. The rim 1
When the return spring 7 is attached or detached, the rod-shaped attachment/detachment tool 9 is brought into contact with the guard portion 1C before coming into contact with the dustproof boot 8.

Note that a ledge surface 1d is attached to the rim 1a.

To remove the shoe return spring 7 from the drum brake configured as described above, as shown in FIG. A rod-shaped tool 9 is inserted between the periphery of the spring mounting hole 1b and the hook 7a is slid along the tool 9.

In addition, its installation is almost the reverse operation, that is, the tool 9
At the same time, hook the hook 7a of the shoe return spring 7 onto the middle part of the spring, insert the tip of the tool 9 into the spring mounting hole 1b, and insert the tool 9 into the spring mounting hole 1b.
This is done by rotating the shoe return spring 7 around the periphery of the tool 9 as a fulcrum, extending the shoe return spring 7, and sliding the hook 7a along the tool 9 to engage the spring attachment hole 1b.

The method of attaching and detaching the shoe return spring 7 is the same as the conventional one, but in the drum brake of this embodiment, in the unlikely event that the tool 9 is improperly operated, the tool 9 may approach the dustproof boot 8. Even if there is a shoe return spring 7, the rim guard part 1C completely prevents it from actually coming into contact with the dustproof boot 8, and it is possible to completely avoid the risk of damage to the dustproof boot 8 that occurs in the conventional work of attaching and removing the shoe return spring 7. be.

FIG. 4 shows a perspective view of a pleixine distal end in another embodiment of the present invention.

This is made by extending the wheel cylinder 6 side end of the rim 1'a of the brake shoe 1' in the width direction of the brake shoe 1', and bending the guard part 1'c to cover the dustproof boot 8. Therefore, this embodiment can also provide the same effects as those of the previous embodiment.

A ledge surface 1'd is attached to the rim 1'a.

In this embodiment, the guard portion 1'c and the ledge surface I'd are separated, but they may be integrated.

In the above embodiment, two guard parts are provided for each brake shoe, but this is for the purpose of making the left and right brake shoes common, and even if there is only one guard part, it does not meet the purpose of the present invention. In short, a part of the rim of the brake shoe is extended and its guard part is bent so that it is located at least on the side opposite to the backing plate of the dustproof boot attached to the wheel cylinder. Accordingly, it is sufficient to form a guard portion 1C located near the dustproof boot 8 on the hub 10 side to which the brake drum is attached.

As described in detail above, the present invention simply extends the rim portion of the brake shoe toward the inner circumferential side in the radial direction of the backing plate 4 to a position near the part farthest from the backing plate 4 of the dust-proof boot. , by integrally providing the guard portion 1C that traverses substantially the entire width of the wheel cylinder 6 in the axial direction of the dustproof boot 8 on the rim 1a,
This has the effect of completely preventing damage to the dustproof boots that would otherwise occur when attaching and detaching the shoe return spring.

[Brief explanation of the drawing]

FIG. 1 is a front view of one embodiment of the present invention, and FIG. 2 is a perspective view of the rim tip of the brake shoe in FIG. 1. FIG. 3 is a diagram showing the operation of attaching and detaching the shoe return spring in the drum brake shown in FIG. 1. FIG. 4 is a perspective view of the rim tip of a brake shoe in another embodiment of the present invention. 1.1': Leading shoe, 2: Trailing shoe, la, l'a: Rim, 1b spring mounting hole, 1c, 1'c: Guard part, 1 d, I'd: Registration surface, 3: Hold down spring, 4: Backing plate, 5: Anchor, 6: Wheel cylinder, 7:
Shoe return spring, 8: dustproof boots, 9 spring removal tool, 10: hub.

Claims (1)

[Claims for Utility Model Registration] A backing plate, a brake shoe movably attached to the backing plate, and a piston that abuts one end of the brake shoe are slidably fitted, and the brake shoe is attached together with the wheel. A wheel cylinder that presses against a rotating brake drum; a dustproof boot that is installed between an end of the wheel cylinder and the piston and covers a fitting portion of the wheel cylinder and the piston; and a wheel cylinder side end of the brake shoe. In the drum brake for an automobile, the shoe return spring is fixed to a mounting hole formed in the part and returns the brake shoe to its original position, and the dustproof boot is located at a position near a part of the dustproof boot farthest from the backing plate. , extending from the rim portion of the brake shoe toward the inner peripheral side in the radial direction of the backing plate;
A guard portion that traverses substantially the entire width in the axial direction of the wheel cylinder of the dust-proof boot is integrally provided with the rim portion, and when the shoe return spring is attached and detached, a rod-shaped detachment tool is rotated around the mounting hole. A drum brake for an automobile, characterized in that the guard portion prevents a tool from coming into contact with the dustproof boot.