JPS5856435Y2 - Drum brake return spring holding device - Google Patents

Description

[Detailed description of the invention] ・Technical field The present invention relates to a retaining device for a U-shaped return spring of a drum brake, and in particular, it has a structure that allows displacement of the return spring due to wear of brake shoes, and facilitates assembly work. The present invention relates to a holding device.

- Conventional technology One type of shoe return spring in drum brakes is a return spring (hereinafter referred to as a U-spring), which is made by curving a spring wire into a substantially U-shape.

This is widely used because it has a simple structure and does not interfere with other parts. It is desired that the intermediate portion be maintained in the proper spatial position.

For this reason, a holding device fixed to the shoe web of the brake shoe, which has little relative movement with the U spring, allows
The middle part of the spring was held.

However, according to such a holding device, the U spring is held by the shoe web which has little relative movement with respect to the movement of the U spring when the brake is applied, so the U spring is reliably held despite the relative movement. However, since the retaining device is fixed in position with the shoe web, the retaining device is forced to deform due to displacement of the U spring due to wear of the brake shoe, and this retaining device also prevents the U spring from moving naturally. There is a problem in that the movement is obstructed and the magnitude and direction of the biasing force applied to the brake shoe changes significantly.

On the other hand, the holding device is provided with a U-shaped fixed part so that the fixed part grips the shoe web so as to be slidable in a direction parallel to the surface of the shoe web, thereby solving the above-mentioned disadvantage. It is possible that

However, according to a holding device with a cutting fixing part,
The fixed part may move relative to the shoe web due to deformation of the U spring due to brake operation, severe vibrations caused by shaft running, etc., and the holding position of the U spring may change or the fixed part may fall off from the shoe web. there were.

・Purpose of the invention The present invention was developed against the background of the above-mentioned circumstances, and its purpose is to allow the displacement of the U-spring due to wear of the brake shoes, and to adjust the middle part of the U-spring to an appropriate position. It is an object of the present invention to provide a holding device that securely holds a U-spring in a spatial position and does not change its holding position with respect to the U-spring regardless of vibration or operation of the U-spring.

・Structure of the invention In order to achieve the above object, the shoe return spring retaining device of the drum brake of the invention is provided with a hook between a pair of brake shoes facing the inner peripheral surface of the brake drum,
A U-spring holding device for a drum brake that holds an intermediate portion of a substantially U-shaped U spring that urges the brake shoe in a direction away from the inner circumferential surface at an appropriate spatial position, the device comprising: (1) the brake; (2) an engagement hole formed in the vicinity of the portion between the U springs in the shoe web of the shoe; The shoe web is elastically gripped in a state in which the protrusion fits into the engagement hole with a predetermined play, and within a range allowed by the predetermined play. a fixed portion fixed to the shoe web so as to be slidable in a direction parallel to the surface of the shoe web; (3) a rising portion extending from one end of the fixed portion toward the U-spring; and (4) the rising portion. The spring gripping portion is bent into a substantially U-shape following the spring gripping portion and elastically gripping the middle portion of the U spring.

・Effects of the invention By doing this, sliding in a direction parallel to the surface of the shoe web of the holding device is achieved by the above-mentioned movement between the inwardly protruding protrusion on the U-shaped fixing part and the retaining hole into which the protrusion is fitted. Since the play is allowed by a predetermined clearance, the intermediate portion of the U spring can be easily held in response to the displacement of the U spring, and the biasing force applied to the brake shoe from the U-shaped U spring is maintained regardless of wear of the brake shoe. Its size and direction do not change.

At the same time, no excessive force is applied to the holding device itself, so
Problems such as deformation and breakage of the holding device can be prevented.

Moreover, the engagement between the protrusion and the retaining hole prevents the fixed part from sliding beyond the range allowed by the predetermined play, thereby preventing deformation of the U-spring due to brake operation and the movement of the vehicle. Despite the severe vibrations caused by this, there is no fear that the holding position with respect to the U-spring will change or that the fixed part will fall off the shoe web.

-Example Hereinafter, an example of the present invention will be explained in detail based on the drawings.

FIG. 1 shows a duo-servo type drum brake, in which a brake drum 10 that rotates together with the wheels has been removed to show the internal structure of the drum brake, and its position is indicated by a chain double-dashed line.

A pair of arc-shaped brake shoes 14 and 16 are slidably held on a backing plate 12 fixed to a non-rotating member (not shown) while being applied with a constant pressing force by shoe hold-downs 1B and 20.

The brake shoes 14.16 include shoe webs 22.24, which are arcuate plates, and shoe webs 22, 2.
A band-shaped shoe rim 26 fixed at right angles to the outer peripheral edge of 4
．． 28, and a lining 30.32 fixed to the outer peripheral surface of the shoe rim 26.28.

One end of the shoe webs 22.24 is interconnected by a link 36 containing an adjusting wheel 34, and the other end abuts a piston 40.42 projecting in the opposite direction from a wheel cylinder 38 fixed to the backing plate 12. ing.

Further, a spring 44 is tensioned at the end of the shoe web 22, 24 on the link 36 side, and a strut 46 is hung on the end of the shoe web 22, 24 on the wheel cylinder 38 side to maintain a constant distance between them. ing.

A U-shaped U spring 48 is provided between the brake shoes 14 and 16 and biased in a direction away from the inner peripheral surface of the brake drum 10, that is, in a direction toward each other.

The U-spring 48 is formed by bending a rod-like spring material into a substantially U-shape, and each end of the U-spring 48 has a concave portion at a bent portion that is bent at right angles to the plane containing the U-spring 48. .24 notch, U
The intermediate portion of the spring 4B other than both ends is spaced apart from the shoe web 22, 24 and the link 36.

A holding device 50 is disposed between the intermediate device of the U spring 48 and the end of the shoe web 22 on the link 36 side.

As shown in FIG. 2, the holding device 50 is made of an elastic metal plate, and is bent into a substantially U-shape and extends from one opposing inner wall surface of the U-shape to the other. A fixing part 54 having a protrusion 52 protruding in the direction, a rising part 56 extending from one end of the fixing part 54 toward the U spring 48, and a substantially U-shaped part following the rising part 56. It consists of a spring gripping part 58 that is bent and opens in the same direction as the fixing part 54.

Note that the protrusion 52 is formed by extruding a part of the fixing part into a semicircular shape.

As shown in FIG. 3, the holding device 50 configured in this manner elastically grips the shoe web 22 by pushing the fixing portion 54 from the edge of the shoe web 22, and also holds the shoe web 22 in an elastic manner. The protrusion 52 is fitted into the formed retaining hole 60 with a predetermined clearance B,
Shoe web 2 within the range allowed for its predetermined play B
It is fixed to the surface of 2 so that it can slide in the parallel direction.

Then, the middle portion of the U spring 4B is pushed into the spring gripping portion 58, thereby gripping the U spring 4B.
The middle portion of spring 48 is held in the proper spatial position.

As described above, the holding device 50 of this embodiment can be assembled to the drum brake by a simple push-in operation without requiring any fixing devices such as bolts, so the assembly has the advantage of reducing the number of man-hours and effort required. be.

The effects of this embodiment will be explained below.

When the pistons 40.42 are pushed out as braking fluid pressure is supplied to the wheel cylinders 3B, the brake shoes 14.16 are spread apart and pressed against the inner circumferential surface of the brake drum 10, and the wheels (not shown) are pressed against the inner surface of the brake drum 10. The rotation of the brake drum 10, which rotates at the same time, is suppressed.

At this time, the U spring 48 is also connected to the brake shoe 14.1.
It will be expanded along with 6.

Next, when the brake fluid pressure in the wheel cylinder 38 decreases,
The piston 4 mainly follows the biasing force of the U spring 48.
0.42 is pushed in, and the brake shoe 14.16 is separated from the inner peripheral surface of the brake drum 10 until it abuts the strut 46.

In such an operating state of the drum brake, the portion of the shoe web 22 to which the holding device 50 is attached and the middle portion of the U spring 48 held by the holding device 50 move in the same direction, so there is almost no relative movement.
No excessive force is applied to the holding device 50 and the U spring 48.

Moreover, as described above, since the intermediate portion of the U-spring 4B is elastically held by the rising portion 56 at a spatial position spaced apart from the shoe webs 22, 24 and the link 36, severe vibrations of the vehicle are not applied to the intermediate portion of the U-spring 4B. Also, the U spring 4B does not hit other parts and cause abnormal noise or wear.

Note that although the protrusion 52 is engaged with the engagement hole 60 with a clearance B, since the fixed portion 54 elastically grips the shoe web, it will not be held even if such vibrations are applied. device 50
No wobbling occurs in the fixed portion 54 of.

Next, lining 30 due to repeated brake operations.
When the position of the brake shoes 14 and 16 is displaced toward the outer circumference due to wear of the brake shoes 32, the holding device 50 is moved in response to the displacement.
A relative movement occurs between the intermediate portion of the U-spring 48 held by the shoe web 22.

In such a case, since the holding device 50 is allowed to slide within the range of the above-mentioned play gap B, the holding device 50 slides in accordance with the relative displacement of the U spring 48.

Therefore, regardless of the relative movement between the U-spring 4B and the shoe web 22, no unreasonable force is applied to the holding device 50 or the natural movement of the U-spring 48 is inhibited, and no force is applied to the brake shoe 14.16. This eliminates the need to change the magnitude and direction of the biasing force.

In other words, the relative displacement between the U spring 4B and the shoe web 22 due to the wear of the lining 30° 32 is the clearance B.
This is absorbed by the sliding movement of the fixed part 52 within the range allowed by the above.

Therefore, no excessive force is applied to the holding device 50, thereby preventing its deformation or breakage.

Furthermore, since sliding between the fixed portion 54 and the shoe web 22 beyond the range allowed by the predetermined play B is prevented, deformation of the U spring 48 due to brake operation,
U-spring 4
This completely eliminates the possibility that the holding device for B changes or that the fixing part 54 falls off from the shoe web 22.

Here, the drum brake may be of not only the type of the above-described embodiment but also of other types, and the holding device 50 may be attached to the shoe web 24 on the opposite side.

Please note that the above is just one embodiment of the present invention.
The present invention can be modified in various ways without departing from its spirit.

[Brief explanation of the drawing]

FIG. 1 is a front view of a drum brake including an embodiment of the present invention. FIG. 2 is a perspective view showing the embodiment of FIG. 1. 3 is a partial sectional view taken along line II-III of FIG. 1. FIG. 10 Ni brake drum, 14.16 Ni brake shoe, 48: U spring (U-shaped shoe return spring), 50: Holding device, 52: Projection, 54: Fixed part,
56: rising portion, 58 spring gripping portion, 60: engagement hole.

Claims (1)

[Claim for Utility Model Registration] A roughly U-shaped shoe return spring that is applied to a pair of brake shoes facing the inner peripheral surface of a brake drum and biases the brake shoes in a direction away from the inner peripheral surface. A shoe return spring holding device for a drum brake that holds an intermediate portion in a proper position, the retaining hole being formed near the intermediate portion of the shoe return spring in the shoe web of the brake shoe; and a protrusion that is bent in a direction and protrudes from one side of the opposing inner wall surfaces of the U-shape toward the other, and the protrusion fits into the retaining hole with a predetermined clearance. a fixing part that elastically grips the shoe web in the state and is fixed to the shoe web so as to be slidable in a direction parallel to the surface of the shoe web within a range allowed by the predetermined play;
a rising portion extending from one end of the fixing portion toward the shoe return spring; and a spring gripping portion that is bent into a substantially U-shape following the rising portion and elastically grips an intermediate position of the not-turn spring. A shoe return spring holding device for a drum brake, comprising: