JPH0249400Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic braking gap adjustment device for a vehicle drum brake that automatically adjusts the braking gap between a brake shoe and a brake drum.

[Conventional technology]

In drum brakes, a pair of brake shoes arranged opposite to each other on a back plate are expanded, and the lining on the outer periphery of the brake shoes is brought into sliding contact with the inner peripheral surface of a brake drum that rotates together with the wheels to perform a braking action. Due to repeated braking, the lining wears out and the braking gap between the lining and the brake drum widens.This automatic braking gap adjustment device automatically compensates for this amount of wear and keeps the braking gap constant. There are some that are equipped with.

Various types of automatic adjustment devices are known; among these, the ones whose main configuration is a combination of struts and quadrants are as follows:
For example, there is one shown in Japanese Utility Model Publication No. 62-43146.

This technology places a plate-shaped strut and a quadrant pivoted on one side of the strut between a pair of brake shoes arranged opposite to each other on a back plate, and the arcuate surfaces of the strut and quadrant are opposed to each other. When the lining on the outer periphery of the brake shoe wears and the braking gap widens beyond a specified level, the meshing position with both serrations is automatically changed to prevent the brake shoes from widening. By regulating the return position of the Y, a predetermined braking gap is set.

The strut is also provided with a protrusion that engages with the web of one brake shoe, a flat surface that makes sliding contact with the web, and an arm that slidably supports the quadrant. A first spring that biases both serrations in a direction to engage them is tensioned between the two serrations, and
A second spring that biases the strut toward one brake shoe side is stretched on the back plate side of the flat part, and the above protrusion, flat part, and spring force the strut to be perpendicular to the web of the brake shoe. The strut is held in place to prevent the strut from tilting during braking.

[Problem that the invention attempts to solve]

However, in the above-mentioned structure, the meshing of both serrations is temporarily disengaged when adjusting the amount of wear to compensate for the amount of wear, resulting in an unavoidable lack of stability due to the distance between the strut and the quadrant. In the type with a brake, when the parking brake is used, the parking lever, which is pivoted to one brake shoe, operates the strut and quadrant, so it is necessary to improve the rigidity in the strut axial direction. A structure with even higher levels of performance was desired.

The present invention was developed against the background of the above circumstances, and the purpose is to provide an automatic braking gap adjustment device for vehicle drum brakes that has high rigidity in the strut axial direction and can perform more stable and reliable operation. There is.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention arranges a strut and a quadrant in mesh between a pair of opposing brake shoes, and automatically changes the meshing position of both during braking operation, thereby improving the brake shoe. In an automatic braking gap adjustment device for a vehicle drum brake that adjusts the braking gap between the lining and the brake drum to a predetermined amount, a pair of pinions are provided facing each other on both sides of the strut, and a serration is carved on the outer peripheral surface. A quadrant member is formed by connecting one end of a pair of quadrants at a bridge portion, the strut is straddled by the bridge portion, each serration is engaged with the pinion, and the quadrant member is pivotally supported on the strut. It is characterized by:

〔Example〕

Below, an example in which the present invention is applied to a drum brake with a parking brake is shown in Figures 1 to 3.
This will be explained based on the diagram.

The drum brake 1 has a pair of left and right arch-shaped brake shoes 3, 4 arranged inside a back plate 2 fixed to the vehicle body.
4, the outer linings 3a, 4a
is rubbed against the inner circumferential surface of a brake drum (not shown) that rotates together with the wheel to perform a braking action.

A wheel cylinder 5 that hydraulically operates the brake shoes 3 and 4 is provided at the upper part of the back plate 2, supporting the upper ends of the webs 3b and 4b, and a wheel cylinder 5 supporting the lower ends of the webs 3b and 4b at the lower part thereof. An anchor 6 is fixedly provided to serve as a fulcrum when the brake shoes 3 and 4 are expanded and contracted.

Between the webs 3b and 4b, return springs 7 and 8 are tensioned near the wheel cylinder 5 and the anchor 6, and which constantly bias both brake shoes 3 and 4 in the direction of contraction. An automatic braking gap adjustment device 9 is interposed between the brake shoe 5 and the return spring 7 on the upper side, and a parking lever 10 is connected to one brake shoe 3 side.

The automatic braking gap adjustment device 9 includes a lining 3
Due to the wear of the brake shoes a and 4a, the return position of the brake shoes 3 and 4 that have been expanded is restricted, and the lining 3
This adjustment device 9 automatically compensates the braking gap between a and 4a and the brake drum to a predetermined amount.
is a plate-shaped strut 11, and the strut 11
The main components are a quadrant member 12 that is slidably supported by a quadrant member 12 and two coil springs 13 and 14.

The strut 11 has a shaft hole 11a at one end on the brake shoe 3 side, and a wide and relatively short elongated insertion hole 11b at the other end on the brake shoe 4 side in the axial direction. is formed, and the insertion hole 1
1b is connected with a narrow and long spring insertion groove 11e extending toward the locking recess 11d that is connected to the upper locking protrusion 11c, and a square hole 11f is formed in the lower part of the insertion groove 11e. and this square hole 11f
A pair of pinions 16, 16 are caulked and fixed to opposite sides of the strut 11 by a fixing square pin 15 inserted through the strut 11.

The quadrant member 12 is the brake shoe 4
The first arm 17a is locked to the web 4b of the
A pair of quadrants 17, 17 each having an arm 17c and a shaft hole 17d formed in the middle of these arms 17a, 17c are connected to the first arm 17a, 17 with a gap equal to the thickness of the strut 11. The upper ends of the quadrant members 17a are connected by a bridge portion 17e, and the quadrant member 12 of this embodiment is formed by cutting a material such as a cast block or a shaped steel.

Further, the parking lever 10 is of a crank shape, and has an engaging arm 10a that engages with an engaging hole 3c formed in the web 3b of the brake shoe 3 at one end, and a connecting hole 10b that connects a brake cable at the other end. The intermediate portion is held by a stopper plate 18 fixed to the back plate 2, and the web 3b
One end of the strut 11 is pivotally supported at the bottom of the strut 11 .

The quadrant member 12 is connected to the strut 1
1 by the bridge part 17e, the strut 11 is inserted between the second arms 17c, 17c, and the shaft 19 is inserted by aligning the shaft holes 17d, 17d with the insertion hole 11b of the strut 11. ,
A U-clip 20 is engaged with the tip of the support shaft 19 protruding from the shaft hole 17d on the opposite side, and the support shaft 19 is rotatably and slidably attached to the strut 11.

Further, the coil spring 13 has a coil portion 13a.
is arranged in the spring insertion groove 11e of the strut 11, and both ends are inserted into the locking recess 1 of the strut 11.
1d and the support shaft 19, the serrations 17b, 17b of the quadrant member 12 are engaged with the pinions 16, 1 by the biasing force of the coil spring 13.
6, and the coil spring 13 is installed inside the strut 11 in the axial direction.
An unbalanced load is not generated in the biasing force between the strut 11 and the quadrant member 12.

Then, the strut 11 is pivotally supported on the parking lever 10 by a support shaft 21 inserted into the shaft hole 11a, and a coil spring 14 is stretched between the locking protrusion 11c of the strut 11 and the web 3b of the brake shoe 3. both first and second quadrant members 12.
The arms 17a, 17a are engaged with the engagement holes 4c of the web 4b of the brake shoe 4, and the strut 11 and the quadrant member 12 are placed between the brake shoes 3, 4.

The present embodiment is constructed as described above, and in normal hydraulic operation, both brake shoes 3 and 4 are expanded using the anchor 6 as a fulcrum in the wheel cylinder 5, and the outer linings 3a and 4a are expanded. slides on the inner periphery of the brake drum to perform braking action.

Furthermore, when the parking brake is activated, the parking lever 10 is pulled in the direction of arrow A in FIG. As the strut 11 and quadrant member 12 of No. 9 move together to the right in FIG. 3, the other brake shoe 4 is expanded.

Each serration 17 of the automatic braking gap adjustment device 9
When the braking gap between the linings 3a, 4a and the brake drum is a predetermined amount, the pinion 16 and the pinion 16 are in the same meshing position and operate in the meshed state. When the braking gap widens beyond a predetermined amount, the brake shoes 3 and 4 are expanded by the amount of wear due to hydraulic pressure.

At this time, each serration 17b and pinion 16
The quadrant member 12 rotates around the support shaft 19 to change the meshing position with the pinion 16 and engage again. As a result, both brake shoes whose hydraulic operation is released The contraction positions of 3 and 4 are regulated to the outside, and the linings 3a and 4a
A predetermined braking gap is set between the brake drum and the brake drum.

As described above, in this embodiment, since the combination of the pinion 16 and the serration 17b is arranged on both sides of the strut 11, the quadrant member 12 rotates out of mesh during the adjustment operation.
The struts 11 prevent side wobbling and ensure reliable and stable operation.

In addition, when the parking brake is activated, a high load thrust is applied from the parking lever 10 to the strut 11 and the quadrant member 12, but the axial thrust transmitted from the strut 11 is transmitted to the pinions arranged on the same surface on both sides. 16 and the quadrant member 12 through the engagement of the serrations 17b.
Since the load is transmitted to the strut 11 and the quadrant member 12, no unbalanced load is generated, and the axial rigidity of the strut 11 and the quadrant member 12 is increased to prevent deformation and to withstand long-term use.

Furthermore, the coil spring 13 that biases the pinion 16 and the serration 17b in the meshing direction is arranged on the axis of the strut 11 to prevent the generation of unbalanced loads, thereby increasing the stability of the adjustment operation or parking brake operation. , more reliable and smooth, and the quadrant member 12
is a pair of quadrants 17, 17 of the same shape.
Since it is an integral piece connected by the bridge portion 17e, it has good moldability and can improve the accuracy of meshing with the pinion 16.

FIG. 4 shows another embodiment of the quadrant member. The quadrant member 30, which has the same partial structure as the embodiment described above, is made by cutting out a plate material into a developed shape, and inserting it into a central bridge portion 17e. It is formed by bending, and has superior moldability and manufacturing cost compared to the above embodiments.

[Effect of idea]

As explained above, the automatic braking gap adjustment device of the present invention has a gap between a pair of opposing brake shoes.
The struts and quadrants are arranged in mesh,
A pair of pinions are provided facing each other on both sides of the strut, and a quadrant member is formed by connecting one end of a pair of quadrants having serrations carved on the outer peripheral surface with a bridge portion, and straddling the strut at the bridge portion. Since the quadrant member is pivotally supported on the strut and each serration is arranged so as to mesh with the pinion, the strut can prevent the quadrant member from being loose in the side direction when it rotates out of mesh during the adjustment operation. can be regulated to ensure reliable and stable operation.

In addition, in the case of a drum brake equipped with a parking brake, the axial thrust transmitted from the strut is transmitted to the quadrant member through the engagement of the pinion and serration arranged on the same surface on both sides. There is no occurrence of unbalanced loads, the axial rigidity of the strut and quadrant members is increased, their deformation is prevented, and they can withstand long-term use.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention, in which Figure 1 is an exploded perspective view of an automatic braking gap adjustment device, Figure 2 is a front view of a drum brake, and Figure 3 is a FIG. 4 is a perspective view showing another embodiment of the quadrant member. 1... Drum brake, 2... Back plate, 3, 4... Brake shoe, 3a, 4a...
Lining, 3b, 4b...web, 9...braking gap automatic adjustment device, 10...parking lever,
10a...Engagement arm, 11...Strut, 11
b...Insertion hole, 11e...Spring insertion groove, 1
2... Quadrant member, 13, 14... Spring, 16... Pinion, 17... Quadrant, 17a... First arm, 17b... Serration, 17c... Second arm, 17d... Shaft hole, 17e
... Bridge Department.

Claims (1)

[Scope of utility model registration request] A strut and a quadrant are arranged in mesh between a pair of opposing brake shoes, and the meshing position of both is automatically changed during braking operation to create a predetermined braking gap between the brake shoe lining and the brake drum. In this automatic braking gap adjustment device for vehicle drum brakes, a pair of pinions are provided facing each other on both sides of the strut, and a bridge section is used to connect one end of a pair of quadrants with serrations carved on the outer peripheral surface. A braking gap automatic braking gap automatic drum brake for a vehicle, characterized in that connected quadrant members are formed, the struts are straddled at bridge parts, each serration is meshed with the pinion, and the quadrant members are pivotally supported on the struts. Adjustment device.