JPS6243146Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an automatic braking adjustment device for a vehicle drum brake having a strut.

[Prior art] Conventionally, an automatic adjustment device for braking of a vehicle drum brake in which a quadrant is supported on a plate-like strut is arranged between one end of a pair of opposing brake shoes, and A coil spring was installed between the strut and the brake shoe to maintain the engaged state.

However, since this coil spring is installed on the side of the strut on the wheel cylinder side or the anchor side, when the strut moves due to braking, the strut tilts toward the side where the coil spring is tensioned, giving an unbalanced load to the strut. Problems may arise, such as interference with surrounding components.

[Purpose of invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide an automatic braking interval adjustment device for a vehicle drum brake that can prevent the inclination of the strut.

[Structure of the idea]

In order to achieve the above object, in the present invention, a braking interval of a drum brake for a vehicle is provided with a plate-shaped strut disposed between a pair of opposing brake shoes and a quadrant pivotally supported by the strut. In the automatic adjustment device, the strut includes a protrusion that engages with the web of one brake shoe, and a first member that extends in the direction of the other brake shoe and supports the quadrant so that it can rotate and slide by a predetermined amount. an arm, a second arm branching from the first arm to form a serration on an arcuate surface, and a surface portion slidingly contacting the back plate side surface of the web of one brake shoe; The strut has an operating arm that engages with the show web, and a cam surface formed with serrations that engages with the arc surface of the second arm, and a first spring that biases the arc surface and the cam surface in a direction that engages the strut. A second spring is disposed on the back plate side of the plane portion, and is stretched between the strut and the quadrant, and between the strut and one brake shoe, and biases the strut in the direction of one brake shoe. It is characterized by what it did.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 and 2.

A pair of left and right bow-shaped brake shoes 2 and 3 are disposed on the inside of a back plate 1 fixed to the vehicle body, and brake shoes are braked by sliding against the inner peripheral surface of a brake drum (not shown) that rotates together with the wheels. It's powered.

A known wheel cylinder 4 for hydraulically operating the brake shoes 2 and 3 is disposed at the upper part of the back plate 1, and a wheel cylinder 4 for hydraulically operating the brake shoes 2 and 3 is disposed at the lower part thereof, and supports the lower ends of the brake shoes 2 and 3 to allow their expansion. An anchor block 5 is fixedly installed to serve as a fulcrum during contraction. In addition, the webs 2a of the brake shoes 2 and 3,
An upper return spring 6 and a lower return spring 7 are tensioned at the upper and lower parts of the foil cylinder 4 to constantly bias them in the direction of contraction.
There is a braking distance between adjacent brake shoes 2 and 3.
An automatic adjustment device 8 is interposed.

During braking: The automatic adjustment device 8 has a plate-shaped strut 9 and a quadrant 10 pivotally supported by the strut 9. The strut 9 has one end inserted into an engagement hole 2b drilled in the web 2a of the brake shoe 2. Engaging protrusion 9
a, two arms are formed separately at the other end, the arm on the back plate 1 side has a step approximately equivalent to the plate thickness, and the first arm 9b is bent toward the anchor block 5 side, and the arm on the brake drum side is The second arm 9d has a serration on the arcuate surface 9c at the end, and on the drum side of the strut 9, one end is bent at a right angle over the middle part and makes sliding contact with the side surface of the back plate of the web 2a.
is formed. At the end of the first arm 9b, a quadrant 10 having an operating arm 10a is rotatably attached to the strut 9 by a pivot pin 11 and slidably by a predetermined amount, and a back of the web 3a of the brake shoe 3 is attached to the tip. A bent surface 9f that is in contact with the side surface of the plate 1 is formed. Then, the serrations formed on the cam surface 10b of the quadrant 10 are applied to the strut 9 by the first spring 12 stretched between the strut 9 and the pivot pin 11.
The second arm 9d is engaged with the serrations of the second arm 9d.

The thus assembled automatic braking adjustment device 8 is disposed between the webs 2a and 3a of the brake shoes 2 and 3. That is, the protrusion 9a of the strut 9 is engaged with the engagement hole 2b of the web 2a, and the quadrant 10 is inserted into the adjustment hole 3b formed in the other web 3a.
The working arm 10a of the strut 9 is inserted through the strut 9, and a second spring 13 is tensioned between the strut 9 and the hooking portion 2c of the web 2a, which is disposed along the side surface of the back plate 1 of the flat portion 9e of the strut 9. As a result, the working arm 10a of the quadrant 10 and the web 3
A distance C corresponding to an appropriate shoe clearance is formed between the adjustment hole 3b and the adjustment hole 3b.

Note that although the flat portion 9e of the strut 9 is provided by bending a plate material, it may be similarly provided by welding or the like.

When the serrations are engaged with each other, rotation of the quadrant 10 is prevented, but when the braking distance exceeds a predetermined amount, the working arm 1 of the quadrant 10 is stopped by the edge of the adjustment hole 3b of the web 3a.
0a is pushed and the pivot pin 11 is moved to the first position of the strut 9.
The arm 9b is slid into the elongated hole (not shown), and the serrations of the strut 9 and the quadrant 10 are disengaged, and the quadrant 10 is attached to the stopper pin 1.
Turn around 1 to change the engagement position of the serrations and adjust the braking distance.

The braking distance automatic adjustment device 8 adjusts the braking distance as described above.
e and the bent piece 9f are in sliding contact with the side surfaces of the back plate 1 of the webs 2a, 3a, and the second spring 13 is stretched along the width of the flat portion 9e, so the strut 9 is attached to the web 2a. , 3a, and there is no risk of it tilting or falling due to braking operations or the like.

[Effect of idea]

As described above, in the present invention, the strut is provided with a flat part that comes into sliding contact with the side surface of the back plate of the web, and the second spring stretched between the strut and the web is arranged along the side surface of the back plate of the flat part. The deflection of the strut by the spring is reduced, and the strut can always be held at right angles to the web. Also, there is no interference with wheel cylinders, axle shafts, etc. due to strut deflection, and the braking period is reduced. This has effects such as being able to make adjustments reliably.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the present invention. Figure 1 is a front view of a drum brake equipped with the device of the present invention, and Figure 2 is a view of the device of the present invention seen from the quadrant side. FIG. 1 is the back plate, 2 and 3 are the brake shoes, 4 is the wheel cylinder, 5 is the anchor block, 6 and 7 are the return springs, and 8 is the brake
Automatic adjustment device, 9 is a strut, 9a is a stopper projection, 9b is a first arm, 9d is a second arm, 9e is a plane part, 9f is a bent piece, 10 is a quadrant, 10
a is an operating arm, 11 is a pivot pin, and 13 is a second spring.

Claims (1)

[Scope of utility model claims] In an automatic braking gap adjustment device for a vehicle drum brake, which includes a plate-shaped strut disposed between a pair of opposing brake shoes and a quadrant pivotally supported by the strut, the strut is connected to one brake shoe. a first arm that extends in the direction of the other brake shoe and supports the quadrant in a rotatable and slidable manner by a predetermined amount; The quadrant has a second arm formed with a serration and a flat surface that slides into contact with the back plate side surface of the web of one brake shoe, and the quadrant has an operating arm that engages with the other brake shoe web, and a cam surface formed with serrations that meshes with an arc surface of the strut, and a first spring that biases the arc surface and the cam surface in a direction that meshes with each other is stretched between the strut and the quadrant; Braking of a drum brake for a vehicle, characterized in that a second spring, which is stretched between one brake shoe and biases the strut in the direction of one brake shoe, is disposed on the back plate side of the flat portion. Automatic gap adjustment device.