JPH034840Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic operating gap adjustment device for an internal expansion type brake such as a friction type brake.

An example of an automatic drum brake operating gap adjustment device will be described with reference to FIG. 1. A pair of brake shoes 3 each having a lining 2 facing the inner surface of a brake drum 1 are arranged on a back plate 4 so as to be expandable and retractable. , a long hole 6 extending in the expansion/contraction direction of each brake shoe 3 is formed in the web 5 of each brake shoe 3, and a hole 7 extending in the expansion/contraction direction of each brake shoe 3 is formed in the back plate 4.
An adjuster stud 9 is provided in which a buckle 8 having a diameter is fixed, and an adjuster stud 9 has one end frictionally engaged with the web 5 and the other end fitted into the hole 7 with a predetermined gap δ.

By the way, in this type of automatic adjustment device for the operating gap of an internal expansion type brake, the adjuster stud 9 is a straight rod-shaped body as shown in FIG. When the adjuster stud 9 and the butt 8 are tilted relative to each other due to the floating of the brake shoe 3 and the elastic deformation of the back plate 4, a predetermined gap δ is created.
became smaller, and there was a risk of over-adjustment.

The present invention is intended to solve the above problem, and its purpose is to prevent over-adjustment.

In order to achieve this object, in the present invention, an elongated hole extending in the direction of expansion and contraction of the brake shoe is bored in the web of the brake shoe, and one end of the adjuster stud is inserted into this elongated hole to attach a leaf spring. A back plate is provided in the vicinity of the web, the batch is fixed to the back plate, a hole is formed in the batch that extends in the expansion/contraction direction of the brake shoe, and the ajar is inserted into the hole. A spherical protrusion formed at the other end of the star stud is inserted into the star stud.

From the above-mentioned configuration, even if the adjuster stud and the bat are relatively inclined in any direction, the change in the predetermined gap can be kept extremely small due to the spherical protruding surface of the adjuster stud, thereby preventing over-adjustment. can do. Further, since the change in the predetermined gap is extremely small, the shoe clearance is stable, and by setting the shoe clearance small, the pedal feel can be improved. Furthermore, since the onset of braking on the left and right wheels is synchronized, there is no difference in unilateral braking or lining wear.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 2, 10 is a back plate fixed to the vehicle body side, and 11 is a brake drum fixed to the wheel side. The back plate 10 is provided with a wheel cylinder and an anchor (not shown), and one end of the web 13 of the pair of brake shoes 12 engages with a piston rod protruding from both ends of the wheel cylinder. The other end engages with both ends of the anchor (in the figure, only one brake shoe 12 and web 13 are shown, and one side will be explained below). ) has a lining 14 attached thereto, and the lining 14 faces the inner surface of the brake drum 11. A return spring (not shown) is stretched between each web 13, and each web 13 is urged in a direction away from the inner surface of the brake drum 11 by the return spring.

A long hole 15 is bored in the web 13.
This elongated hole 15 extends in the expansion/contraction direction of the brake shoe 12 (in the left-right direction in FIG. 2). In FIG. 2, approximately below the elongated hole 15 is a back plate 1.
A button 16 fixed at 0 is located, and a hole 17 is formed in the button 16, which extends in the direction of expansion and contraction of the brake shoe 12.

Reference numeral 18 designates an adjuster stud, and one end of the adjuster stud 18 is provided with a threaded portion 19, and a seat portion 20 is formed closer to the threaded portion 19 and the other end of the adjuster stud 18. There is. The adjuster star stud 18 is inserted into the elongated hole 15 from the threaded portion 19 side with the flat washer 21 received at the seat portion 20. 2
Two and a plurality of leaf springs 23 are fitted, and are fixed by screwing a nut 24 into the threaded portion 19. As a result, the web 13 and the adjuster stud 18 are frictionally engaged. The frictional force resulting from this frictional engagement is greater than the tension of the return spring, but is set to be sufficiently smaller than the pressing force of the wheel cylinder. On the other hand, the other end of the adjuster stud 18 has a spherical protrusion 25.
is formed, and this adjuster stud 1
The other end of 8 is fitted into the hole 17 of the bat 16. At this time, a predetermined gap δ is formed between the protruding surface 25 and the inner surface of the brake shoe 12 in the expansion/contraction direction (in the left-right direction in FIG. 2) of the batch 16 (FIG. 2 shows the state when the brake is not activated). This predetermined gap δ is a shoe clearance between the brake drum 11 and the lining 14.

Next, the effect will be explained.

When the lining 14 is not yet worn, when the driver performs a brake operation, the brake shoe 12 is expanded by the wheel cylinder, the lining 14 is pressed against the brake drum 11, and the brake is activated.

When the wear of the lining 14 exceeds the predetermined gap δ, the protruding surface 25 comes into contact with the inner surface of the batch 16 (on the right side in FIG. 2) due to brake operation, but when the brake operation is continued, the brake shoe 12
overcomes the frictional force between the adjuster star stud 18 and the web 13 in the radial direction of the brake drum 11,
By sliding between the washers 21 and 22, the lining 14 is brought into pressure contact with the inner surface of the brake drum 11. Then, when you release the brake,
The return spring causes the brake shoe 12 to return by a predetermined gap δ. Therefore, even if the lining 14 wears out, a constant shoe clearance is always maintained.

In such an automatic operating clearance adjustment device for an internal expansion type brake, there are many problems such as manufacturing tolerances of the brake shoe 12, lifting of the brake shoe 12 during braking, and positional movement of the brake shoe 12 due to wear of the lining 14. Furthermore, due to the elastic deformation of the back plate 10, there is a risk that the adjuster stud 18 and the butt 16 may be tilted relative to each other. , the change in the predetermined gap δ is kept extremely small, and the brake drum 11
Thus, the shoe clearance of the lining 14 becomes stable. Additionally, generally, the cylinder that presses the opposing brake shoes 12 in the expansion direction is provided between the upper ends of the two opposing brake shoes 12, and an anchor is provided between the lower ends. , when braking is applied when moving forward, which is much more common than when reversing, lining 1 on the front side in the direction of vehicle movement
As a result, the front brake shoe 12 will move within the brake drum 11 by the amount of wear. This movement is caused by the deformation of the back plate 10, the web 13, or the adjuster stud 18.
According to the present invention, the spherical protrusion 2 formed at the other end of the adjuster stud 18 disturbs the relative positional relationship between the adjuster stud 5 and the inner wall of the hole 17.
Part 5 acts to align these positions,
This means that the relative positions of the spherical protruding surface 25 and the inner wall of the hole 17 do not shift. This results in uniform wear of the lining 14.

Although one embodiment has been described above, the present invention has the following features:
One end of the adjuster stud is fixed to the back plate, a cylindrical body is loosely fitted to the other end of the adjuster stud at a predetermined interval, and the cylindrical body is attached to the length of the shaft drilled in the web of the brake shoe. Also in an automatic operating interval adjustment device for an internally expanding brake in which the cylindrical body and the web are inserted into a hole and frictionally engaged, and a return spring is connected to the cylindrical body, the adjuster stud is inserted into the inside of the cylindrical body. This can be implemented by having a spherical protruding surface in the direction of displacement of the brake shoe.

Since the present invention is an automatic operating gap adjustment device for an internally expanding brake configured as described above, the protruding surface 25 of the adjuster stud 18 is formed in a spherical shape, so that the inner surface of the hole 17 of the butt 16 can be adjusted. Changes over time in the relative positional relationship between the two in contact with the circumferential surface, such as deformation of the back plate 10 to which the buckle 16 is attached or the web 13 to which the adjuster stud 18 is attached, and positional deviation due to lifting of the brake shoe 12. regardless of,
Point contact is always made, and changes in the gap δ can be reduced.

As a result, there is no over-adjustment. Clearance can be set small and pedal feeling can be improved. Since the change in clearance is small, the left and right brakes start to apply in synchronization, eliminating one-sided brake effect. In addition, Asia star stud 18 and batch 1
6 and on the same straight line, the change in relative position between the two can be reduced, and the influence on the contact point can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view showing an example of a drum brake, and FIG. 2 is an enlarged sectional view of a main part of the drum brake according to the present invention. 10... Back plate, 12... Brake shoe, 13... Web, 14... Lining, 1
6...Batsuchi, 18...Asia Star Stud,
25...Protrusion.

Claims (1)

[Scope of utility model registration request] An elongated hole extending in the expansion/contraction direction of the brake shoe is bored in the web of the brake shoe, one end of an adjuster stud is frictionally engaged with the elongated hole via a leaf spring, and a back plate is provided near the web. and fixing a batch to the back plate, forming a hole in the batch that extends in the direction of expansion and contraction of the brake shoe, and fitting a spherical protrusion formed at the other end of the adjuster stud into the hole. An automatic operating clearance adjustment device for internally expanding brakes.