JPH0440034Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is an inwardly expanding type vehicle drum brake in which the lining slides into contact with the inner peripheral surface of the brake drum to perform braking action by expanding the brake shoe. In particular, the present invention relates to the attachment of a shoe hold pin that supports a brake shoe and the ledge surface structure of a back plate that guides movement of a brake shoe.

[Conventional technology]

In conventional internally expanding drum brakes, a pair of brake shoes are each supported by shoe hold pins installed upright on the back plate. The web of the brake shoe is inserted into the shaft that locks onto the outer surface of the hole and projects inside the back plate, and a shoe hold spring is compressed between the tip of the shaft and the web to make the brake shoe elastic. I have it.

The brake shoe has a lining fixed to its outer circumferential surface, and the lower surface of the brake shoe rim is supported by the ledge surface of the back plate.When the brake shoe expands or contracts,
The seal rim slides on the ledge surface, and this ledge surface is integrally formed when the back plate is molded.

[The problem that the idea attempts to solve]

However, in the above-mentioned devices, external dust and water may enter through the locking holes in the back plate, causing stains and rust, so a technique in which a sealing material is provided in the locking holes has not been provided. However, because the shoe hold pin is long and tends to be dragged and tilted by the operation of the brake shoe, sufficient sealing performance could not be obtained.

Therefore, in the present invention, a shoe-hold plate with a holding part for the shoe-hold pin is formed separately, and the locking hole of the back plate is eliminated to improve dustproof and waterproof properties. The object of the present invention is to provide an inwardly expanding drum brake for a vehicle that is integrally provided with a surface portion.

[Means to solve the problem]

In order to achieve the above-mentioned purpose, this invention is for an internally expanding type vehicle in which the brake shoe supported by the shoe hold pin installed upright on the back plate is expanded and the lining on the outer periphery of the shoe rim slides into contact with the brake drum. In the drum brake, a pin holding part that holds the shoe hold pin, a ledge surface part that faces the shoe rim and supports it and guides movement of the brake shoe, and a fixing part that is joined to the back plate. A shoe-hold plate is formed separately from the back plate, and the shoe-hold plate is fixed to the inner surface of the back plate at a fixing portion, and the proximal end of the shoe-hold pin is attached to the pin holding portion. The brake shoe is locked and the brake shoe is elastically supported by the shoe hold pin via a shoe hold spring.

[Effect]

According to the above configuration, since there is no locking hole for the brake shoe pin in the back plate, staining and rust due to the intrusion of dust and water are prevented, and the brake shoe pin can be formed short. It is less susceptible to drag caused by the operation of the brake shoe, and the brake shoe can be reliably supported for smooth operation.

Furthermore, since the rest surface part is provided separately from the back plate, a high-hardness member can be used to prevent scratches and grooves from occurring due to sliding contact with the brake shoe rim, thereby reducing the sliding resistance of the brake shoe. .

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the drawings, Fig. 1 is a front view of the back plate to which the shoe hold plate is fixed, Fig. 2 is a cross-sectional view taken from Fig. 1, and Fig. 3 is the back plate with brake components such as brake shoes attached. FIG. 4 is a front view of the drum brake arranged and configured, and FIG.

The drum brake 1 is a two-leading type in which arch-shaped brake shoes 4, 4 are arranged in an expandable manner between wheel cylinders 3, 3 with anchors arranged oppositely inside a back plate 2.
Each brake shoe 4, whose both ends are supported by the piston 5 of the wheel cylinder 3 and the adjuster bolt 7 of the anchor 6, has a substantially middle portion of the web 4a,
It is elastically supported by a show-hold pin 8 and a show-hold spring 9 to a show-hold plate 10 fixed inside the back plate 2.

Between the webs 4a, 4a, return springs 11, 12 are tensioned inside the wheel cylinders 3, 3 and are supplied to the wheel cylinders 3. When the piston 5 advances due to hydraulic pressure, one end of the web 4a that comes into contact with the piston 5 is pressed against the adjuster bolt 7.
The lining 4c, which is spread out using the other end supported by the rim 4b as a fulcrum and is fixed to the outer periphery of the rim 4b, slides into contact with the inner circumferential surface of a brake drum (not shown) to perform a braking action.

The back plate 2 is formed by press forming a rolled steel plate or the like with excellent formability, and has four vehicle body mounting holes 2b provided on the outer periphery of a central axle insertion hole 2a, and on both sides of the insertion hole 2a. , a positioning hole 2c into which the boss portion 3a of the wheel cylinder 3 is fitted is provided with mounting holes 2d for the wheel cylinder above and below, respectively;
These holes 2a to 2d are hermetically closed with a sealing material such as packing when mounted on the vehicle body.

Further, the shoe-hold plate 10 includes a pin holding portion 10a that holds the shoe-hold pin 8.
and the brake shoe 4 while supporting the shoe rim 4b.
The ledge surface portion 10b that guides the movement of the brake shoe 4 and the fixed portion 10c that is joined to the back plate 2 are made of a material harder than the brake shoe 4 and are formed into a substantially arched shape. Four fixing parts 10c provided between the two are fixed to the inner surface of the back plate 2 by spot welding.

The pin holding part 10a is connected to the central registration surface part 10b.
A shoe hold pin 8 is provided in the inner part of a guide hole 13a formed between a pair of retaining pieces 10d, 10d that are provided in a stepped manner to protrude toward the side opposite to the back plate 2 and that are inclined toward the back plate 2 side. A circular locking hole 13b for locking is provided in series.

The shuhold pin 8 has a shaft portion 8a inserted into the pin holding portion 10a through the guide hole 13a, a large diameter base end portion 8b being locked to the outer surface of the locking hole 13b, and the shaft portion 8a through the insertion hole 4d of the web 4a of the brake shoe 4, and insert the U-shaped shoe hold spring 9 into the shaft portion 8a protruding from the web 4a.
Rotate 90 degrees, and the tip 8c of the pin 8 and the web 4
A brake shoe 4 is elastically supported on a shoe-hold plate 10 by a shoe-hold pin 8 and a shoe-hold spring 9, and a shoe rim 4b is , the three cut and bent portions 4e formed on the back plate 2 side are connected to the ledge surface portion 10, respectively.
Supported by b.

As mentioned above, the shoe hold plate 10 including the ledge surface portion 10b is made of a material with higher hardness than the brake shoe 4, whereas in the conventional type in which the ledge surface is integrally formed with the back plate, the moldability is poor. Since the material is a rolled steel plate that is rich in hardness but not very hard, the sliding contact with the brake shoe may cause scratches or steps on the recess surface, which may cause sliding resistance such as catching. However, although the ledge surface portion 10b of this embodiment uses the same rolled steel plate as the conventional one for the back plate 2, there are no scratches or stepped portions in sliding contact with the cut and bent portion 4e, and the sliding resistance is reduced. As a modification, only the registration surface portion 10b may be formed of a high hardness material and incorporated into the shoe hold plate 10.

As described above, in this embodiment, the shoe-hold pin 8 is held in the pin holding portion 10a of the shoe-hold plate 10, so the locking hole is eliminated from the back plate 2 to prevent dust and water from entering. Therefore, it is particularly suitable as a full-shield drum brake for buggy vehicles that travel on rough roads such as muddy areas, rivers, and coastlines.

Furthermore, since the length of the shoe hold pin 8 can be reduced, it is less likely to be dragged by the operation of the brake shoe 4, and the shoe 4 can be held securely, resulting in smoother operation.

The pin holding portion 10a has a plurality of recessed surface portions 10b.
and fixed portions 10c are integrally formed on the long arcuate hold plate 10,
The attachment strength to the back plate 2 is high, and the brake shoe 4 has sufficient rigidity to withstand external forces caused by the operation of the brake shoe 4.

Since the locking hole 13b of the pin holding part 10a is connected with the guide hole 13a which opens on the side, it is easy to attach and remove the shuhold pin 8, and the pin 8 locked in the locking hole 13b is , retaining piece 10
d and 10d will not fall off accidentally.

Furthermore, since the shoe hold plate 10 is made of a material with higher hardness than the brake shoe 4, it is possible to prevent scratches and steps on the registration surface portion 10b, thereby reducing sliding resistance.

[Effect of idea]

As explained above, the present invention has a pin holding part that holds the shoe hold pin, a leg surface part that faces the shoe rim and supports it and guides the movement of the brake shoe, and is joined to the back plate. A shoe-hold plate having a fixing portion is formed separately from the back plate, and the fixing portion fixes the shoe-hold plate to the inner surface of the back plate, and the proximal end of the shoe-hold pin is attached to the pin holding portion. Since the brake shoe is held resiliently by the shoe hold pin via the shoe hold spring, the locking hole for the shoe hold pin on the back plate is eliminated, and the sealing performance is high and dust-free. We can provide a full-shield type drum brake that is difficult for water to enter. Furthermore, because the shoe hold pin length is shortened, it is less susceptible to drag caused by brake shoe operation, and the brake shoe can be supported reliably. Enables smooth operation.

In addition, the shoe hold plate, which faces the shoe rim and has a leg surface that supports it and guides the movement of the brake shoe, is formed separately from the back plate and is fixed to the back plate. If the rigidity of the back plate is increased and the shoe hold plate is made of a material with higher hardness than the brake shoe, it is possible to prevent scratches and steps caused by the sliding of the brake shoe. Dynamic resistance can be reduced.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a front view of a back plate to which a shuffle plate is fixed, Fig. 2 is a cross-sectional view taken from Fig. 1, and Fig. 3 shows a brake shunt attached to the back plate. FIG. 4 is a front view of a drum brake constructed by arranging brake component members such as a brake lever, and FIG. 4 is a sectional view taken along the line taken from FIG. 1...Drum brake, 2...Back plate, 4...Brake shoe, 4a...Web, 4
b...Shaw rim, 4d...Through hole, 4e...Cut and bend portion, 8...Shaft pin, 8a...Shaft, 8b...Proximal end, 8c...Tip, 9...Shaw Hold spring, 10...Show hold plate, 10a...Pin holding part, 10b...
Registration surface part, 10c...fixing part, 10d...retaining piece, 13a...guide hole, 13b...locking hole.

Claims (1)

[Scope of utility model registration request] In an internal expansion type vehicle drum brake in which a brake shoe supported by a shoe-hold pin provided upright on a back plate is expanded and a lining on the outer periphery of the shoe rim slides into contact with a brake drum, the shoe-hold pin is held. A shoe hold plate including a pin holding portion, a ledge surface portion facing the shoe rim and supporting it to guide movement of the brake shoe, and a fixing portion joined to the back plate is called a back plate. The shu-hold plate is formed separately, and the shu-hold plate is fixed to the inner surface of the back plate at the fixing part, and the proximal end of the shu-hold pin is locked to the pin holding part, and the shu-hold plate is fixed to the inner surface of the back plate with the fixing part. An internally expanding drum brake for vehicles characterized by a brake shoe that is held elastically through a hold spring.