JPH1037994A - Wheel brake cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily carry out machining at a low cost by supporting a ring type seal member arranged in the major diameter part of a cylinder by means of a plug which is provided with a hole and is inserted into the cylinder major diameter part and assembling a boot to a piston and to the plug. SOLUTION: A D-ring 4 is inserted into the inside of a major diameter part 2b in a cylinder 2, while a plug 5 is fitted to the major diameter part 2b from the truncated conical bottom part side, and the D-ring 4 is held in the cylinder 2 by means of a stepped part 2e between the major diameter part 2b and a minor diameter part 2c and one end side of the plug 5. A snap ring 7 is elastically engaged in a groove 2d in the major diameter part 2b and is locked in a locking part 5c in the plug 5 at the same time so as to be fixed in the cylinder 2. A piston 3 is inserted slidably into an inner hole 5a of the plug 5, the D-ring 4 inner circumference, and the minor diameter part 2c, while a pressure chamber 8 is formed on the right end face side. Subsequently, an inner circumference part 6a of a boot 6 is installed in a groove 3a in the piton 3 while its outer circumference part 6b is installed in a groove 5b in the plug 5. In this way, polishing of the cylinder 2 inner circumferential face is not needed, and polishing of the piston 3 outer circumferential face can be easily carried out at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel brake cylinder, and more particularly to a wheel brake cylinder used for a vehicle drum brake.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional wheel brake cylinder includes a cylinder 31, a piston 32 slidably inserted into the cylinder 31, and a pressure chamber 33 formed at one end thereof. Groove 3 provided on the outer periphery of
2a, a seal member 34 for sealing between the inner circumference of the cylinder 31 and the outer circumference of the piston 32, and the outer circumference thereof is fitted to the outer circumference of the cylinder 31, and the inner circumference thereof is fitted to the piston 32. And a boot 35 to be combined.

In general, the wheel brake cylinder is in contact with the other end of the piston 32 by sliding the piston 32 outward from the cylinder 31 due to the flow of the brake fluid into the pressure chamber 33 due to the operation of the brake pedal. The shoe is urged so as to contact the inner peripheral surface of the brake drum, and a braking force is generated by the contact between the brake shoe and the brake drum rotating integrally with the wheel.

[0004]

However, in the conventional wheel brake cylinder described above, the sliding surface of the seal member 34 is the inner peripheral surface of the cylinder 31, and the inner peripheral surface of the cylinder 31 having a small diameter but having a large surface area. It took time and effort to grind the surface.

Further, in the configuration in which the seal member 34 is provided in the groove 32a of the piston 32, air is accumulated in the groove 32a when the wheel brake cylinder is filled with the brake fluid. In order to remove the air, the air vent hole 32 is formed in the land 32b of the piston 32.
The trouble of providing c was required.

As a result, the cost of the wheel brake cylinder has been increased.

An object of the present invention is to provide a wheel brake cylinder which can be easily processed and is inexpensive.

[0008]

In order to solve the above-mentioned technical problems, a cylinder having a large diameter portion and a small diameter portion continuous from an opening toward the inside is provided, and a ring arranged in the large diameter portion is provided. A plug having a hole having the same diameter as the small-diameter portion of the cylinder, being inserted into the large-diameter portion of the cylinder, and supporting the seal member at one end thereof; and a small-diameter portion of the cylinder and the seal. A piston which is slidably inserted into the inner periphery of the member and the hole of the plug and forms a pressure chamber on one end surface side, and an outer peripheral portion thereof is attached to the plug, and an inner peripheral portion thereof is attached to the piston. Wheel brake cylinder with boots to be assembled. Preferably, a wheel brake cylinder in which the outermost peripheral portion of the boot is within the range of the outer peripheral diameter of the cylinder is desirable.

[0009] Preferably, a wheel brake cylinder is provided at a large diameter portion of the cylinder and has a support member for fixing the plug to the cylinder.

[0010] The wheel brake cylinder of claim 1 is
Since the seal member is provided on the cylinder side, the inner periphery of the seal member and the outer periphery of the piston are sealed.

[0011] The wheel brake cylinder of claim 2 is
In addition to the effect of the first aspect, since the outermost peripheral portion of the boot is within the range of the diameter of the cylinder, the outermost peripheral portion of the boot does not protrude to the outer peripheral side of the cylinder.

According to the third aspect of the present invention, in addition to the function of the second or third aspect, the support member is disposed on the cylinder, and the support member fixes the plug.

[0013]

Embodiments of the present invention will be specifically described below.

FIG. 1 is a sectional view of a wheel brake cylinder according to one embodiment of the present invention, and FIG. 2 is a front view showing a main part of a vehicle drum brake provided with the wheel brake cylinder of the present invention. is there.

As shown in FIG. 1, reference numeral 1 denotes a wheel brake cylinder, which includes a cylinder 2, a piston 3, a D-ring 4, which is a seal member, a plug 5, a boot 6, and a snap ring 7, which is a support member. And

The cylinder 2 is connected to the cylinder 2 through the opening 2a.
It has a large diameter portion 2b and a small diameter portion 2c continuous with the large diameter portion 2b toward the inside.

On the opening 2a side of the large diameter portion 2b of the cylinder 2, a groove 2d for assembling the snap ring 7 is formed.

At the left end of the piston 3 in FIG.
A groove 3a into which the inner peripheral portion 6a is fitted is formed.

The plug 5 has an inner hole 5a having the same diameter as the small-diameter portion 2c of the cylinder 2, the outer periphery thereof is substantially the same as the diameter of the large-diameter portion 2b of the cylinder 2, and has a substantially truncated conical shape as a whole. Present. An outer peripheral portion of the boot 6 is provided on an outer peripheral portion of the plug 5.
A groove 5b into which b is assembled and a locking portion 5c for locking the snap ring 7 are formed.

The assembly of the wheel brake cylinder 1 will be described. First, the D-ring 4 is the large-diameter portion 2b of the cylinder 2.
Is inserted into.

Next, the plug 5 is assembled to the cylinder 2 from the bottom of the truncated cone, and fitted to the large diameter portion 2b of the cylinder 2. When the plug 5 is attached to the cylinder 2, the D-ring 4 moves in the axial direction of the cylinder 2 (in FIG. 1) at the step 2 e between the large-diameter portion 2 b and the small-diameter portion 2 c and one end of the plug 5. The movement is regulated, and is held in the cylinder 2.

The snap ring 7 is resiliently engaged with a groove 2 d provided in the large diameter portion 2 b of the cylinder 2, and is also fixed to the cylinder 2 by being locked by a locking portion 5 c of the plug 5. You. By attaching the snap ring 7 to the cylinder 2, the plug 5 is fixed to the cylinder 2.

The piston 3 has an inner hole 5a of the plug 5 and D
The pressure chamber 8 is slidably inserted into the inner circumference of the ring 4 and the small-diameter portion 2c of the cylinder 2, and forms a pressure chamber 8 on the right end face side.

Next, the inner peripheral portion 6a of the boot 6
The outer peripheral portion 6b of the boot 6 is attached to the groove 5b of the plug 5.

Similarly, the piston 2, the O-ring 4, the plug 5, the snap ring 7, and the boot 6 are arranged on the right side (not shown) of the cylinder 2. That is, the wheel brake cylinder 1 includes two opposed pistons 3. On the left end side of the piston 2,
A brake shoe 12 described below is brought into contact with the brake shoe.

As shown in FIG. 2, reference numeral 10 denotes a vehicle drum brake (leading trailing brake).
An arc-shaped brake shoe 1 is provided in the brake drum 11.
2, 12 and the wheel brake cylinder 1 are provided.

The brake shoes 12, 12 are connected by an anchor 13 at one opposing end, a wheel brake cylinder 1 is interposed at the other opposing end, and brake drums are returned by return springs 14, 14. 11 is urged inward in the radial direction.

As shown in FIGS. 1 and 2, when the driver of the vehicle depresses a brake pedal (not shown), the brake fluid flows through the hydraulic passage (not shown) into the cylinder of the wheel brake cylinder 1, that is, the pressure chamber 8 Flows into.

When the brake fluid flows into the pressure chamber 8, the piston 3 is pressed and urged to the outside of the cylinder 2, and as the piston 3 moves, the brake shoe 12 also expands radially outward. .

When the brake shoe 12 is expanded outward in the radial direction, the brake shoe 12 abuts on the inner peripheral side surface of the brake drum 11 which rotates integrally with the wheels of the vehicle. The contact with 11 causes a braking force to act on the wheels.

When the brake is no longer necessary and the driver releases the brake pedal, the brake fluid in the cylinder 2, that is, the pressure chamber 8 flows out of the cylinder 2 via the hydraulic path, and the return spring 14 The brake shoe 12 is returned to the initial position by the urging force, and the piston 3 is urged into the cylinder 2 and moved with the return of the brake shoe 12 to the initial position, so that the piston 3 also returns to the initial position.

As described above, according to the wheel brake cylinder 1 of the present embodiment, the D ring 4 is disposed on the cylinder 2 side, and the inner periphery of the D ring 4 and the outer periphery of the piston 3 are sealed. Therefore, it is not necessary to grind the inner peripheral surface of the cylinder 2, and it is sufficient to grind the outer peripheral surface of the piston 3 having a smaller area than the inner peripheral surface of the cylinder 2. Can be easily polished, so that the wheel brake cylinder 1 can be easily polished.

Further, since the D-ring 4 is arranged on the cylinder 2 side, processing and work for air bleeding become unnecessary, and the wheel brake cylinder 1 can be processed more easily. In addition, since the outer peripheral portion 6b, which is the outermost peripheral portion of the boot 6, is attached to the plug 5 and its outer peripheral diameter is substantially the same as the large diameter portion 2b of the cylinder 2,
The boot 6 exists within the range of the outer diameter of the cylinder 2.
Does not protrude to the outer peripheral side of the cylinder 2. Therefore, it is possible to provide the wheel brake cylinder 1 in which the space is effectively used in a vehicle drum brake device in which the installation space is particularly restricted in the outer peripheral portion of the wheel brake cylinder 1. Further, the provision of the snap ring 7 prevents the plug 5 from coming off the cylinder 2 and ensures the holding of the D ring 4.

Accordingly, it is possible to provide an inexpensive wheel brake cylinder that can be easily processed.

In the present embodiment, the plug 5 has a substantially frusto-conical shape, but it goes without saying that the present invention is not particularly limited to this shape.

Needless to say, the wheel brake cylinder of the present invention is not only effective for the drum brake 10 of the present embodiment.

As described above, the present invention has been described based on the above embodiments. However, the present invention is not limited to only the above embodiments, but includes various embodiments according to the principle of the present invention.

[0038]

As described above, according to the first aspect of the present invention, the seal member is provided on the cylinder side, and the inner periphery of the seal member and the outer periphery of the piston are sealed. There is no need to grind the inner peripheral surface of the cylinder, and it is only necessary to grind the outer peripheral surface of the piston with a smaller area than the inner peripheral surface of the cylinder. Processing of the brake cylinder can be facilitated.

Further, since the seal member is provided on the cylinder side, processing and work for bleeding air become unnecessary, and the wheel brake cylinder can be processed more easily. Therefore, it is possible to provide an inexpensive wheel brake cylinder that can be easily processed.

According to the second aspect of the invention, in addition to the effect of the first aspect, the outermost peripheral portion of the boot does not protrude to the outer peripheral side of the cylinder. Therefore, it is possible to provide a wheel brake cylinder in which the space is effectively used, for example, in a vehicle drum brake device in which the mounting space is severely restricted particularly in the outer peripheral portion of the wheel brake cylinder.

According to the third aspect of the present invention, in addition to the effects of the first or second aspect of the present invention, the provision of the support member prevents the plug from coming off the cylinder and retains the seal member. We are sure.

[Brief description of the drawings]

FIG. 1 is a sectional view of a wheel brake cylinder 1 according to an embodiment.

FIG. 2 is a front view of a drum brake 11 to which the wheel brake cylinder 1 of FIG. 1 is assembled.

FIG. 3 is a sectional view of a conventional wheel brake cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wheel brake cylinder 2 Cylinder 2a Opening 2b Large diameter part 2c Small diameter part 3 Piston 4 D ring 5 Plug 5a Inner hole 6 Boot 6a Inner peripheral part 6b Outer peripheral part 7 Snap ring 8 Pressure chamber

Claims (3)

[Claims] 1. A cylinder having a large-diameter portion and a small-diameter portion continuous from an opening to the inside, an annular seal member disposed in the large-diameter portion, and a cylinder having the same diameter as the small-diameter portion of the cylinder. A plug having a hole, which is inserted into a large-diameter portion of the cylinder and supports the seal member at one end thereof; A wheel brake cylinder comprising: a piston inserted into the piston to form a pressure chamber on one end surface side; and a boot having an outer peripheral portion attached to the plug and an inner peripheral portion attached to the piston. 2. The wheel brake cylinder according to claim 1, wherein an outermost peripheral portion of the boot is within a range of an outer peripheral diameter of the cylinder. 3. The wheel brake cylinder according to claim 1, further comprising a support member disposed on a large-diameter portion of the cylinder and fixing the plug to the cylinder.