JPH0440033Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a leading-trailing type vehicle drum brake equipped with an automatic braking gap adjustment device. The present invention relates to a shoe return mechanism for releasing a brake shoe from digging into the brake shoe.

[Conventional technology]

Leading/trailing type drum brakes, which are used for the rear wheels of four-wheeled vehicles and the front and rear wheels of motorcycles, have leading and trailing brakes facing each other on the back plate. One end is supported on the side wall of the anchor and the other end is supported on the actuator, and both brake shoes are expanded by operation of the actuator, and the lining of the shoe is brought into sliding contact with the brake drum to perform braking action. Some drum brakes of this type are equipped with an automatic braking gap adjustment device.

This automatic braking gap adjustment device regulates the return position of the brake shoe after it has been expanded in order to automatically compensate for the braking gap between the brake drum and the brake drum due to lining wear. When a groove is formed on the inner peripheral surface of the brake drum and the brake shoe is adjusted into the groove, the groove and the brake shoe may interfere when the brake drum is removed for maintenance. May inhibit withdrawal.

For this reason, for example, as disclosed in Japanese Utility Model Application Publication No. 56-90519, a strut for regulating the backward position of the brake shoe is provided between the webs of both brake shoes, and a groove is provided at the end of the strut. There is one in which the bottom of the web and the inner edge of the web are connected with a bolt with a gap, and the shoe can be returned to its original state by removing the bolt.

[Problem that the invention attempts to solve]

However, since the above-mentioned automatic braking gap adjusting device utilizes a strut, the embodiments are limited, and an automatic braking gap adjusting device that does not use a strut is used, for example, by providing an adjuster on a wheel cylinder serving as an actuator to adjust the braking gap. It was not possible to implement the method using a formula that adjusts the

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a shoe return mechanism for a vehicle drum brake that allows easy return of the brake regardless of the form of the automatic braking gap adjustment device.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention has one end of the same side of the leading and trailing brake shoes disposed opposite to the back plate supported by an anchor, and the other end supported by an actuator for expansion. , a drum brake for a vehicle equipped with an automatic braking gap adjustment device that biases both brake shoes in the diametrical direction with a return spring and automatically compensates for the amount of wear on the lining of the brake shoes, A shoe return member is formed separately from the anchor and includes a pair of retainer pieces that hold the side wall on the brake shoe side and support one end of each brake shoe, and the shoe return member is inserted from the back of the back plate. The retainer is rotatably supported or screwed onto the inserted set bolt, and is disposed so as to be movable in the axle direction by rotating the set bolt, and the retainer pieces can be removed from each of the brake shoes by rotating the set bolt. It is characterized by

[Effect]

According to the above configuration, by rotating the set bolt, the shoe return member is pulled or pushed from the back surface of the back plate, and both retainer pieces are moved between the support surface of the anchor and one end of the brake shoe. When the shoe is slid away from the shaft in the axle direction, one end of the shoe comes into contact with the side wall of the anchor, causing both brake shoes to contract in diameter, allowing the brake drum to be removed from interference with the brake shoe. It becomes possible.

〔Example〕

Hereinafter, a first embodiment in which the present invention is applied to a drum brake equipped with a strut-type automatic braking gap adjustment device will be described with reference to FIGS. 1 to 3.

In the drum brake 1, leading and trailing brake shoes 2 and 3 are connected to approximately central portions of arcuate webs 2a and 3a, respectively, by a shoe hold down pin 4 and a shoe hold spring 5.
It is supported by a back plate 6 fixed to the vehicle body.

One end portion 2b, 3b on the same side of the web 2a, 3a
is the retainer piece 2 of the shoe return member 21 which will be described later.
It is supported by the anchor 7 via 1b, 21b, and the other end portions 2c, 3c are supported by pistons 9, 9 of a wheel cylinder 8, which corresponds to the actuator of the present invention.

Between the webs 2a and 3a, near the anchor 7 and the wheel cylinder 8, both brake shoes 2,
Return spring 1 that urges 3 in the diameter reduction direction
0 and 11 are tensioned, and an automatic braking gap adjustment device 12 is provided between the wheel cylinder 8 and the upper return spring 11, and the brake shoes 2 and 3 are operated by hydraulic pressure. By pushing the pistons 9, 9 of the wheel cylinder 8, the wheels are expanded using one end 2b, 3b on the anchor 7 side as a fulcrum, and the outer linings 13, 13 are slid into contact with the inner peripheral surface of a brake drum (not shown). and perform braking action.

The braking gap automatic adjustment device 12 connects a strut 14 to the leading brake shoe 2 and a bell crank lever 15 to the trailing brake shoe 3. The rearward position of both brake shoes 2 and 3 is regulated by meshing with serrations 17 carved on the outer periphery.

Additionally, when the linings 13, 13 are worn out and the braking gap with the brake drum expands beyond a predetermined value,
The meshing position between the pinion 16 and the serration 17 is changed, the return position of the expanded brake shoes 2 and 3 is restricted to the expanded side, and a predetermined braking gap is automatically set.

The anchor 7 has an anchor block 1 attached to a back plate 6 formed from a material such as an aluminum alloy.
8 and an anchor plate 19 are integrally molded, and a shoe return member 21 is attached to the anchor block 18, which is held by a set bolt 20 screwed onto the back plate 6.

The shoe return member 21 projects in parallel from both sides of the base plate 21a toward the wheel cylinder 8, and
Holding the side walls 18a, 18a of the anchor block 18 on the brake shoe side, the brake shoe 2,
A pair of retainer pieces 21b, 21b supporting one end portions 2b, 3b of 3, and holding pieces 21c, 21c with elastic force extending in a wave shape from the lower edge of each retainer piece 21b to the lower surface of the one end portions 2b, 3b. and a connecting piece 21d that is bent from the lower edge of the base plate 21a parallel to the back plate surface.

As described above, this shoe return member 21 has the connecting piece 21d supported by the set bolt 20 connected to the back plate 6, and the base plate 21a and the retainer pieces 21b, 21b form a U-shape on the side wall of the anchor block 18. One end portion 2b, 3b of the brake shoe 2, 3
are abutted and supported by the retainer pieces 21b, 21b,
Further, vertical movement is restrained by the anchor plate 19 and the restraining pieces 21c, 21c.

Set bolt 2 that supports the shoe return member 21
0 is screwed into the female screw hole 6a of the back plate 6 from the back side, and the tip 20a protruding inside is inserted into the connecting piece 21d and is supported by a U clip 22 to prevent it from coming off. head 2
0b is designed to prevent dust and water from entering the drum brake through the female screw hole 6a.
covered with.

The present embodiment is constructed as described above, and when the linings 13, 13 are worn out due to repeated braking, the brake shoes 2, 3 are automatically moved to the expansion side by the braking gap automatic adjustment device 12. A predetermined braking gap is set.

When removing the brake drum, if both brake shoes 2 and 3 are interfering with the groove on the inner peripheral surface of the brake drum, remove the boot 23,
When the set bolt 20 is rotated in the retracting direction from the back side of the back plate 6, the shoe return member 21
is gradually pulled back toward the back plate 6 side together with the set bolt 20, and the retainer pieces 21b, 21b
is detached from one end portions 2b, 3b of the brake shoes 2, 3.

One end portions 2b and 3b of the brake shoes 2 and 3 that have come out of contact with the retainer piece 21b are reduced in diameter by the urging force of the return springs 10 and 11, and are supported in contact with the side wall 18a of the anchor block 18, respectively. ,
As a result, interference between the brake shoes 2 and 3 and the concave groove is released, and the brake drum can be removed.

As described above, according to this embodiment, the retainer pieces 21b, 21b can be removed from the one ends 2b, 3b of the brake shoes 2, 3 by simply rotating the set bolt 20 from the back surface of the back plate 6. , reduce the diameter of both brake shoes 2 and 3 at the same time,
It is possible to perform a show return.

4 to 6 show a second embodiment of the present invention,
The first part that pulls back the shoe return member toward the back plate.
In contrast to the embodiment, this embodiment shows an example of pushing up toward the opposite side of the back plate.

Anchor block 32 is fixed to back plate 30 with bolts 31, and a rectangular frame 33 having wavy restraining pieces 33a on both sides is press-fitted and fixed thereto. A shoe return member 35 is attached with a set bolt 34 that is inserted into the housing.

The shoe return member 35 is attached to the anchor block 32
Anchor plate 35 arranged on the upper surface 32b of
A pair of retainer pieces 35b, 35b that sandwich the brake shoe side side walls 32c, 32c of the anchor block 32 are extended on the lower surface of the anchor plate 35a, and a nut 36 is inserted into the insertion hole 35c for the set bolt on the upper surface of the anchor plate 35a. The show return member 35 is attached to the anchor block 32 by screwing a set bolt 34 into a nut 36, and the set bolt 34 protrudes from the nut 36.
A stop ring 37 for preventing removal is fitted to the tip.

One end portions 2b and 3b of the brake shoes 2 and 3 are
is abutted and supported by the retainer pieces 35b, 35b,
Further, the upper and lower surfaces are restrained by both ends of the anchor plate 35a and the restraining pieces 33a, 33a, and the set bolt 34 can be inserted from the back of the back plate 30.
When the shoe return member 35 is rotated in the direction of removing the shoe return member 35, the shoe return member 35 moves to the tip side of the set bolt 34, which is the side opposite to the back plate.
Both retainer pieces 35b, 35b are separated from one end portions 2b, 3b of the brake shoes 2, 3, the diameter of the shoes 2, 3 is reduced, and the brake drum can be removed.

As described above, the detachment of the shoe return member from the brake shoe is as shown in both of the above embodiments.
It may be carried out either toward the back plate side or toward the opposite side of the back plate.

In addition, since the anchor supports both ends of the leading and trailing shoes on the same side, shoe return can be performed with one shoe return member, and since the show return member is provided using the anchor, As long as it is a leading-trailing type drum brake, a wide range of implementations are possible regardless of the form of the automatic braking gap adjustment device.

Furthermore, in both embodiments, the restraining piece together with the anchor plate restrains the vertical movement of one end of the brake shoe, so that the fulcrum is prevented from shifting when the brake shoe is expanded, and the operation can be performed smoothly and reliably.

[Effect of idea]

As explained above, the present invention includes a shoe return member that is separate from the anchor and includes a pair of retainer pieces that support one end of the leading and trailing brake shoes by sandwiching the side wall of the anchor on the brake shoe side. The shoe return member is rotatably supported or screwed onto a set bolt inserted from the rear side of the back plate, and is disposed so as to be movable in the axle direction by rotation of the set bolt,
Since the retainer pieces are removed from each of the brake shoes by rotating the set bolts, both brake shoes can be returned to the shoe position at the same time with one member, and moreover, only the simple operation of rotating the set bolts is required. Moreover, it becomes possible to reliably perform the shoe return without requiring excessive force, and the brake drum can be easily removed.
Further, since the shoe return member is provided using an anchor, it can be implemented in a wide variety of leading-trailing type drum brakes, regardless of the form of the automatic braking gap adjustment device.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, FIG. 1 is a front view of a drum brake, FIG. 2 is a cross-sectional view of FIG. 1, and FIG. 4 to 6 show the second embodiment, FIG. 4 is a front view of the drum brake, FIG. 5 is a cross-sectional view of FIG. 4, and FIG. It is an exploded perspective view of a return member. 1... Drum brake, 2... Brake shoe for leading, 3... Brake shoe for trailing, 2a, 3a... Web, 2b, 3b
... One end, 6 ... Back plate, 7 ... Anchor, 8 ... Wheel cylinder corresponding to actuator, 10, 11 ... Return spring,
12... Braking gap automatic adjustment device, 13... Lining, 18... Anchor block, 18a... Brake shoe side wall, 19... Anchor plate, 20... Set bolt, 21... Shoe return member, 21a... ...Base plate, 21b... Retainer piece, 21c... Holding piece, 21d... Connection piece, 22
...U clip.

Claims (1)

[Scope of utility model registration request] One end of the leading and trailing brake shoes placed opposite to the back plate on the same side is supported by an anchor, the other end is supported by an actuator for expansion, and both brake shoes are reduced in diameter by a return spring. In a vehicle drum brake equipped with an automatic braking gap adjustment device that automatically compensates for the amount of wear on the lining of the brake shoe, the side wall of the anchor on the brake shoe side is held between the A shoe return member having a pair of retainer pieces that supports one end of the brake shoe is formed separately from the anchor, and the shoe return member is rotatably supported or screwed onto a set bolt inserted from the rear surface of the back plate. for a vehicle with an automatic braking gap adjustment device, characterized in that the retainer pieces are disposed so as to be movable in the axle direction by rotating a set bolt, and the retainer pieces are detached from each brake shoe by rotating the set bolt. Drum brake shoe return mechanism.