JPS627004Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic shoe gap adjustment device of a type that does not increase the rigidity of the drum in a drum brake.

In drum brakes, an automatic shoe gap adjustment device is used to properly maintain the gap between the drum and the shoe (hereinafter referred to as the shoe gap), and an adjusting screw built into the wheel cylinder is gradually screwed out. Devices that adjust the shoe gap are known. As this type of automatic shoe gap adjustment device, there are those that have a built-in wheel cylinder and have a bush or the like fitted to the outer circumference of the piston, and those that have an adjustment lever pivoted on the outer circumference of the wheel cylinder. The wheel cylinder has a large diameter, and depending on the model of the drum brake, the drum,
It has the drawback that it interferes with the hub, various mounting bolts, etc., and is difficult to adopt due to storage space considerations. Furthermore, some automatic shoe gap adjustment devices have a phenomenon in which the deformation of the drum caused by braking torque is compensated for during shoe gap adjustment, that is, a phenomenon in which the rigidity of the drum is increased. This is a type of over-adjustment and causes brake drag.

Therefore, the present invention aims to provide an automatic shoe gap adjustment device that can prevent the above-mentioned over-adjustment by using a link device provided on the backing plate separately from the wheel cylinder.

Embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 designates a wheel cylinder fixed to a bucking plate 2, and an adjuster steering screw 3, which abuts a brake shoe 20 on a leading end cut-in portion 3a, is screwed into an adjuster steering nut 4 at its threaded portion 3b. A flange portion 4a is fixed to the tip of the cylindrical adjusting nut 4, and the flange portion 6a is engaged with the wheel cylinder body 5 to determine the return position, and rotation resistance is provided at the bottom of the piston 6 to be fitted. A washer 7 for reducing the amount is inserted and inserted. One-way teeth 4b that engage with an adjuster lever 15, which will be described later, are formed on the outer edge of the flange-like portion 4a of the adjuster steering nut 4. 8 is a dustproof boot fitted between the wheel cylinder main body 5 and the piston 6, and 9 is an oil packing fitted around the piston 6.

Next, a link device installed on the bucking plate 2 that engages with the wheel cylinder 1 configured as described above to perform an adjusting action will be described.

10 is a connection link that rotatably engages with a support pin 11 installed upright on the bucking plate 2;
Bracket 1 fixed to bucking plate 2
A tension coil spring 13 is tensioned between 2 and 2 to provide rotational behavior in the clockwise direction. Connection link 1
0, an adjuster lever 15 is pivotally supported at the other end by a connecting pin 14. One end of the adjuster lever 15 is formed of a two-layered protrusion, and the short protrusion 15a of the upper layer is connected to the flanged portion 4a of the adjuster staying nut 4.
The long protruding edge 15b on the lower layer that comes into contact with the end flat portion forms a feed pawl, and the one-way tooth 4b on the outer edge of the brim portion 4a
It is engaged to allow feeding in only one direction. The other end of the adjuster lever 15 forms a bent edge 15c serving as a locking means, and the support pin 1 of the connecting link 10
It is locked on the side edge of the first side. In addition, connection pin 14
A ring 16 is attached to the ring 16, and a disc spring 17 is inserted between the ring 16 and the connecting link 10 to bring the connecting link 10 and the adjuster lever 15 into close contact with each other. Furthermore, a torsion spring 1 is attached to the connecting pin 14.
8 is wound, and the torsion spring 18 has one end locked to the adjuster lever 15 and the other end locked to the connecting link 10 to give the adjuster lever 15 a counterclockwise rotational habit. be. Reference numeral 19 denotes a support pin installed on the backing plate 2, and supports the connection link 10 from the back side.

Therefore, when the brake is not applied, the link device is set as follows. That is, the connection link 1 is supported from the back side by a support pin 19, and is given the ability to rotate clockwise by a weak tension coil spring 13 using the support pin 11 that engages with the side edge as a fulcrum.
0, an adjuster lever 15 is pivotally supported by a connecting pin 14, and one end is locked to the side edge of the connecting link 10 by a bent edge 15c serving as a locking means, and a strong torsion spring 18 is used to apply force to the connecting link 10. is provided to give it a rotational habit in the counterclockwise direction. The adjuster lever 15 is positioned with its short flange 15a abutting against the flat end of the flanged portion 4a of the adjuster staying nut 4, and its long flange 15b is engaged with the one-way tooth 4b so as to be able to feed in only one direction. .

Next, the operation will be explained.

During braking, when pressure oil is introduced into the wheel cylinder body 5 from the outside and the piston 6 operates, the adjuster steering nut 4 and the brake shoe 20 are activated.
The adjusting screws 3 that are in contact with each other stroke together. At this time, the connecting link 10 and the adjuster lever 15 rotate together around the support pin 11 as a fulcrum against the force of the tension coil spring 13 due to the action of the torsion spring 18, and the long protrusion of the adjuster lever 15 rotates as a fulcrum. One-way tooth 4 due to edge action
Rotate b to screw out the adjusting screw 3. When the shoe clearance is within the appropriate range, the one-way tooth 4 is controlled by the adjuster lever 15.
Before the feed amount b exceeds 1 pitch, the brake shoe 20 comes into sliding contact with a drum (not shown), the axial force of the adjusting screw 3 increases, and the rotation of the adjusting nut 4 stops. Thereafter, the action of the shoe gap adjustment device is stopped and the torsion spring 18 is compressed to absorb the action of the piston 6, so that the phenomenon of the drum becoming stiffer is avoided.

If the brake shoe 20 is worn and the shoe clearance exceeds the appropriate range, use the adjuster lever 15 to move the one-way tooth 4b one pitch before the brake shoe 20 comes into sliding contact with a drum (not shown) during braking. When the brake shoe 20, and eventually the piston 6, returns to its position, the long protrusion of the adjuster lever 15 15b passes over the one-way tooth 4b by one tooth and engages with the next tooth.

Manual adjustment of the shoe gap is performed by inserting a screwdriver or the like from the back side of the adjustment window (not shown) of the bucking plate 2 and rotating the adjusting nut 4 with the one-way teeth 4b, as in the conventional shoe gap adjustment device. It is done.

Since the present invention is constructed and operates as described above,
As an automatic shoe gap adjustment device that prevents over-adjustment due to the rigidity of the drum, it is suitable for use in drum brakes that are limited by the mounting space of the wheel cylinder. There is no movement, so the durability of the adjuster lever is also good.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of the shoe gap automatic adjustment device according to the present invention, FIG. 2 is a view taken in the direction of the - arrow in FIG. 1,
FIG. 3 is a view taken along the - arrow in FIG. 1...Wheel cylinder, 2...Bucking plate, 3...Adjusting screw, 3b
……Screw rod part, 4……Asia retaining nut, 4
a...Brim portion, 4b...One-way tooth, 5...Wheel cylinder body, 6...Piston, 10...
Connection link, 11... Support pin, 13... Tension coil spring, 14... Connection pin, 15... Adjuster lever, 15a... Short ridge, 15b... Long ridge, 15c... Bent edge ( locking means), 18...
Torsion spring.

Claims (1)

[Scope of utility model registration request] In a wheel cylinder, an adjuster steering screw, which contacts a brake shoe, is screwed into an adjuster stayer nut at its threaded portion, and the adjuster stayer nut is rotatably inserted into a piston that fits into the wheel cylinder body. A one-way tooth is formed on the outer edge of the flange fixed to the adjusting nut, and a weak spring is applied to one end of the connecting link, which is rotatably supported by a support pin set up on the bucking plate, to rotate clockwise. Gives movement,
Pivot the adjuster lever to the other end of the connection link,
A strong torsion spring is applied between the connecting link and the adjuster lever to give the adjuster lever a counterclockwise rotational habit, and the locking means is used to lock the connecting link, so that the adjuster lever's second Among the flanges of the layers, the short flanges of the upper layer are brought into contact with the flat end of the flanged portion of the adjusting nut, and the long flanged edges of the lower layer are engaged with the one-way teeth on the outer edge of the flanged portion. Shu gap automatic adjustment device.