JPH027314Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement of a wheel cylinder for a drum brake.

(Prior Art) As shown in FIG. 3, generally, a drum brake 1 is provided with a wheel cylinder 4A for a pair of brake shoes 3, 3 pivotally mounted on the inside of a brake drum 2. The wheel cylinder 4
Brake shoes 3 and 3 are activated by pistons 5 and 6 of A.
The area is starting to expand and narrow.

As shown in FIG. 4, the wheel cylinder 4A includes a cylinder body 7.
A pair of pistons 5, 6 are fitted into the pistons 5, 6, and the outer ends 5a, 6a of each piston 5, 6 are connected to the brake shoes 3, 3, and the pistons 5, 6 are connected to the brake shoes 3, 3, respectively.
6 between the inner ends 5b, 6b of each piston 5, 6
Disc-shaped cup members 8, 8 facing each other are provided,
Each of the cup members 8, 8 is biased outwardly by a positioning spring 10 via filling blocks 9, 9, which improve the ability of the cup members 8, 8 to fit in and release air. It is now held in place.

In addition, 14 indicates the cylinder body 7 and the pistons 5 and 6.
The boot member 14 has an outer peripheral part 14a fitted into a boot groove 7a formed in the cylinder body 7, and an inner peripheral part 14b which seals between the outer ends of the pistons 5 and 6. It is fitted into boot grooves 5d and 6d formed in 5a and 6a.

(Problem to be solved by the invention) By the way, the above conventional wheel cylinder 4A
Since the filling blocks 9, 9 and the spring 10 are required for the cup members 8, 8, the number of parts is large and assembly is time-consuming, resulting in high costs.

The present invention was made to solve the above-mentioned conventional problems, and aims to reduce the number of parts by eliminating the need for filling blocks and springs, thereby contributing to cost reduction.

(Means for Solving the Problems) Therefore, the present invention includes a cylinder body in which a piston that operates a brake shoe is fitted,
A cup member facing the piston is provided on the inner end side of the piston, a cup part for fitting the cup member into the cylinder body, a protrusion part protruding inward from the cup part, and a rear part of the protrusion part. The holding part protrudes radially from the cylinder body and fits into the cylinder body, and holds the cup part through the protrusion so that it does not fall down.

(Operations and Effects of the Invention) According to the invention, the protruding portion acts as a filling block on the cup portion of the cup member;
Since it is equipped with a holding part that acts as a spring, it eliminates the need for filling blocks and springs while maintaining the same performance as before, reducing the number of parts and making assembly easier, reducing costs. You will be able to figure it out.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a wheel cylinder 17A of the type using a dish-shaped cup member 16, which is provided with a horizontally long cylinder body 18, into which a pair of pistons 19 and 20 are fitted.

Each piston 19, 20 has an outer end portion 19a, 20a having a small diameter straight shaft, and an inner end portion 19b, 20b having a flat inner end portion.

Inner end portions 19b, 2 of each of the pistons 19, 20
Dish-shaped cup members 16, 16 facing each piston 19, 20 are provided between the pistons 0b, respectively.

Each cup member 16 includes a cup portion 16a that fits into the cylinder body 18, a protrusion 16b that protrudes inward from the cup portion 16a and acts as a filling block, and a protrusion 16b that extends radially from the rear of the protrusion 16b. It is constructed by integrally molding a holding portion 16c that protrudes toward the cylinder body 18, fits into the cylinder body 18, and acts as a spring.

As shown in FIG. 2, air notches 16d, . . . , 16d are formed on the outer periphery of the holding portion 16c.

The outer end shaft portion 19a of each of the pistons 19, 20,
The inner peripheral part 21b of the boot member 21, the outer peripheral part 21a of which is fitted into the boot groove 18a formed in the cylinder body 18, is fitted into the inner peripheral part 20a.

If the inner peripheral part 21b of the boot member 21 is set to have a long shape in the axial direction as shown in the figure, the outer end shaft part 1
9a, 20a is reliable, and there is no need to form boot grooves on the pistons 19, 20 as in the past, so the trouble of post-processing the pistons is saved, and the pistons 19, 20 can be forged or sintered. It can be manufactured only by

With the above configuration, the cup part 16a and the holding part 16c of the cup member 16 fit into the cylinder body 18, and the holding part 16c holds the cup part 16a through the protruding part 16b so that it does not fall down. have the effect of

Therefore, the protrusion 16b acts as a conventional filling block, and the holding part 16c acts as a conventional spring, so that the same performance as in the past can be maintained.

In the above embodiment, a so-called dual-effect type drum brake is used as an example, which is provided with a pair of pistons 19 and 20 that widen and narrow the pair of brake shoes 3 and 3. Needless to say, the present invention can also be applied to a so-called single-effect type drum brake that operates a brake shoe.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a type of wheel cylinder using a dish-shaped cup member according to the present invention, and FIG. 2 is a side view of the cup member viewed from the - direction in FIG.
FIG. 3 is a front view of a drum brake, and FIG. 4 is a sectional view of a wheel cylinder of a type using a conventional dish-shaped cup member. 16...Cup member, 16a...Cup portion, 1
6b...Protrusion part, 16c...Holding part, 17A...
Wheel cylinder, 18... Cylinder body, 1
9, 20... Piston, 19a, 20a... Outer end shaft portion, 19b, 20b... Inner end portion, 21... Boot member.

Claims (1)

[Scope of utility model registration request] The cylinder body includes a cylinder body into which a piston for operating a brake shoe is fitted, and a cup member facing the piston is provided on the inner end side of the piston,
The cup member includes a cup portion that fits into the cylinder body, a protrusion portion that protrudes inward from the cup portion,
A wheel cylinder for a drum brake, comprising a holding part that protrudes radially from the rear of the protrusion, fits into the cylinder body, and holds the cup part through the protrusion so that it does not fall down.