JPH0312978Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is an inwardly expanding type vehicle drum brake that performs braking by sliding the lining on the inner peripheral surface of the brake drum 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 aims 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, the present invention is an inward expansion type in which the brake shoe whose web is 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 for a vehicle, a pin holding portion having elasticity extending inward of the back plate, a leg surface portion supporting the shoe rim and guiding movement of the brake shoe, and a leg surface portion joined to the back plate. forming a show-hold plate having a fixing part, fixing the show-hold plate to an inner surface of the back plate at the fixing part, and locking a show-hold pin between the pin holding part and the web; The feature is that the brake shoe is made to last longer.

[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 resiliently supported by a show-hold pin 8 to a show-hold plate 9 fixed inside the back plate 2.

Between the webs 4a, 4a, return springs 10, 11 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 9 includes a pin holding portion 9a that holds the shoe-hold pin 8;
The ledge surface portion 9b that supports the brake rim 4b and guides the movement of the brake shoe 4, and the fixed portion 9c that is joined to the back plate 2 are formed into a substantially arched shape, and the three ledge surface portions 9b are alternately sandwiched between The four fixing parts 9c provided are fixed to the inner surface of the back plate 2 by welding or the like, and the material of the shoe hold plate 9 is generally a brake shoe made of the same rolled steel plate as the back plate 2. For example, a material having a hardness higher than 4 is used, such as spring steel.

The pin holding portion 9a is provided so as to protrude from the inside of the central ledge surface portion 9b in the axial direction, and has an edge cut by a protrusion 9d formed between the pin holder portion 9a and the ledge surface portion 9b to provide elasticity. , the pin holding portion 9a has a locking hole 12 for locking the shoe hold pin 8.
are installed in succession.

The shoe-hold pin 8 is constructed by inserting the shaft portion 8a into the insertion hole 4d of the web 4a and the locking hole 12 of the pin holding portion 9a from the side opposite to the back plate, and inserting the large-diameter base end portion 8b into the insertion hole. 4d, the tip portion 8c projects from the locking hole 12 toward the back plate 2, and the shuhold pin 8 is
By rotating the pin 8 by 90 degrees and locking it in the pin holding part 9a, the brake shoe 4 is elastically held on the shoe hold plate 9 by the elastic force of the pin holding part 9a. The rim 4b has three bent portions 4e formed on the side of the back plate 2, each of which is supported by the ledge surface portion 9b.

As mentioned above, the shoe hold plate 9 including the ledge surface portion 9b is made of a material with higher hardness than the brake shoe 4, whereas the conventional type in which the ledge surface is integrally formed with the back plate has poor formability. 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 ledge surface, which may cause sliding resistance such as catching. However, although the ledge surface portion 9b 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 9b may be formed of a high-hardness material and incorporated into the shoe hold plate 9.

As described above, in this embodiment, the shoe-hold pin 8 is attached to the pin holding portion 9 of the shoe-hold plate 9.
Since it is held at position a, the locking hole from the back plate 2 can be eliminated and the intrusion of dust and water can be prevented.
It is particularly suitable as a full-shield drum brake for buggies that travel on rough roads such as muddy areas, rivers, and coastlines.

In addition, since the pin holding portion 9a has elasticity, the conventional shew-hold spring can be omitted, improving ease of assembly. Since it can be attached from the inner surface of the brake shoe 2 and its length can be reduced, it is less susceptible to drag due to the operation of the brake shoe 4, and the shoe 4 can be held securely, resulting in smoother operation.

Since the pin holding part 9a is integrally formed with the long arcuate shoe hold plate 9 which is provided with a plurality of locking surface parts 9b and fixing parts 9c alternately, the pin holding part 9a has a high attachment strength to the back plate 2, and the pin holding part 9a is attached to the back plate 2 with high strength. It has sufficient rigidity to withstand the external force caused by the operation of 4.

Furthermore, since the shoe hold plate 9 is made of a material with higher hardness than the brake shoe 4, scratches and stepped portions on the registration surface portion 9b can be prevented, and sliding resistance can be reduced.

[Effect of idea]

As explained above, the present invention has a pin holding part with elasticity that extends inward of the back plate, a leg surface part that supports the shoe rim and guides the movement of the brake shoe, and a pin holding part that is joined to the back plate. forming a shoe-hold plate having a fixing portion, fixing the shoe-hold plate to the inner surface of the back plate at the fixing portion, and engaging a shoe-hold pin between the pin holding portion and the web; By stopping the brake shoe and allowing the brake shoe to be held in place, we can eliminate the locking hole for the shoe hold pin on the back plate and provide a full-shield type drum brake that is highly airtight and prevents dust and water from entering. .

Furthermore, since the shoe hold spring can be omitted and the length of the shoe hold pin is shortened, it is less susceptible to drag due to the operation of the brake shoe, and the brake shoe can be supported reliably to ensure smooth operation.

Further, if the shoe hold plate is made of a material with higher hardness than the brake shoe, it is possible to prevent scratches and step portions from occurring due to sliding on the registration surface portion, and reduce the sliding resistance of the brake shoe.

[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 plate, 9a...Pin holding part, 9
b...Register surface portion, 9c...Adhering portion, 9d...Protrusion, 12...Locking hole.

Claims (1)

[Scope of utility model registration request] In an internally expanding type vehicle drum brake in which a brake shoe whose web is supported by a shoe hold pin set 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, the inner part of the back plate is A shoe hold plate is formed that includes a pin holding portion with elasticity that extends to the brake shoe, a ledge surface portion that supports the shoe rim and guides movement of the brake shoe, and a fixing portion that is joined to the back plate. The brake shoe is held resiliently by fixing the shoe hold plate to the inner surface of the back plate at a fixing portion, and locking a shoe hold pin between the pin holding portion and the web. An internally expanding vehicle drum brake featuring: