JPH0647742U - Brake shoe return spring assembly structure for drum brakes - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain an effective structure when a brake shoe return spring is installed in a drum brake with little room. [Structure] Two brake shoes 1, 1a webs 2, 2
One end of the return spring 22 that locks both ends to a is positioned on the backing plate side of the web 2 of the first brake shoe 1 and locked to the web 2. The other end of this spring 3 is
The brake shoe 1a is positioned on the side opposite to the backing plate of the web 2a and locked to the web 2a.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an assembling structure of a return spring which is incorporated in a drum brake of an automobile and pulls back a brake shoe when releasing a brake.

[0002]

[Prior art]

 A drum brake is provided with two brake shoes that are loosely supported on a backing plate fixed to the vehicle body and can be expanded in a drum that interlocks with wheels, and when braking, a drive device such as a wheel cylinder is pressurized with hydraulic oil. Is supplied to push the piston to push the lining of the brake shoe against the inner peripheral surface of the drum, and the friction is applied to brake the wheel through the drum. When the brake is released, the pressure oil is discharged from the wheel cylinder to release two pieces. The brake shoe is pulled over from the drum and returned to the non-braking position by the return spring mounted on the brake shoe.

4 to 6 exemplify a conventional return spring assembling structure, FIG. 4 is a front view schematically showing a drum brake excluding the drum, and FIG. 5 is a view schematically showing a return spring assembling portion. 4 is a sectional view taken along line aa, and FIG. 6 is a similar sectional view schematically showing another structure of the return spring assembly portion.

There have conventionally been two types of assembling the return spring to the brake shoe.

As shown in FIGS. 4 and 5, the first type is a first mold in which the first and second return springs 3 are in the same plane as the webs 2 and 2a of the first and second brake shoes 1, 1a. 3a is located respectively, and hooks 4, 4a formed at both ends of both springs are engaged with holes 5, 5a of each web. The brake shoes 1, 1 a are movably held by the hole down device 6 with respect to the backing plate 7 in a small range. Numerals 8 and 8a are wheel cylinders, and numeral 9 is a slack adjuster attached to the wheel cylinder 8 to automatically adjust the clearance between the lining 10 of the brake shoe and the inner peripheral surface of the drum (not shown). A shaft hole 11 is provided at the center of the backing plate 7, and a plurality of bolt holes 12 for fixing the backing plate to the vehicle body are formed around the shaft hole 11.

As shown in FIG. 6, the second type has two return springs 3 (3a) on the backing plate side of the webs 2 and 2a of the first and second brake shoes 1 and 1a, respectively. The hook portions 13 and 13a, which are positioned on the surfaces 19 and 20 of FIG. 1 and bent laterally, are locked in the holes 5 and 5a of the web.

The assembly structure of the first type return spring has a small shaft hole 11 and a small bolt hole 12 and small bolts and nuts for fixing the backing plate to the vehicle body, so that the space on the backing plate is large. Although it can be used when there is a hole, the shaft that passes through the shaft hole 11 is thick, the fixing bolts and nuts are large, there is not enough space, and the return spring hits the slack adjuster and other internal parts. Then, the second type of assembly must be done. In recent years, this margin has tended to decrease gradually, and the need to assemble the second type has increased. Contrary to the example shown in FIG. 6, if a return spring is provided on the second surface 19a, 20a of the web opposite to the backing plate, the brake performance is adversely affected, for example, by tightening the brake shoe restraint by the hole down device 6. Therefore, this structure cannot be used.

[0008]

[Problems to be solved by the device]

 Recently, the space between the drum and the backing plate has become smaller, so the return spring must be tensioned to avoid interference with the parts such as the slack adjuster and wheel cylinder provided in the drum. In addition, it is also necessary to prevent the return spring from inclining the brake shoe to reduce the efficiency of drum assembly work.

What must be considered here is that when the second mold is assembled, the brake shoes 1 and 1a are eccentrically pulled as shown in FIG. This is to cause a phenomenon of falling in the Y direction. If the brake shoe was mounted on the backing plate so that the shoe clearance would be appropriate when the brake shoe fell like this, the lining 10 would hit the edge of the drum when the drum was overlaid on the backing plate and assembled. Since it becomes impossible to assemble, the adjustment gear 21 of the wheel cylinder 8 is turned to preliminarily retract the piston of the wheel cylinder 8 so that the shoe gap becomes excessively large, and after the drum assembly is completed, the adjustment is performed. The gear 21 is rotated to bring the brake shoe to the proper position, and work is done so that the shoe clearance is proper. Such work is extremely inefficient because a fine tool is inserted through a small hole in the backing plate and the adjustment gear 21 is manually rotated little by little.

[0010]

[Means for Solving the Problems]

 According to this invention, one end of the return spring is positioned on the first surface of the web of one brake shoe on the backing plate side and is locked to this web, and the other end is connected to the backing plate of the web of the other brake shoe. The above-mentioned inconvenience is eliminated by the return spring assembly structure which is located on the opposite second surface and is locked to this web.

[0011]

[Action]

 The action of the return spring to draw the two brake shoes when releasing the brake is the same as the conventional one. Since the return spring is mounted on both ends of the web of the two brake shoes by changing the positions of the first surface and the second surface, it is possible to reduce the chance of interference with the parts in the drum. At the same time, since the two brake shoes are tilted in the same direction, there is no need to increase the clearance between the brake lining and the lining. Further, by using a return spring in which coils are formed at both ends and a middle portion is formed by a wire-like connecting portion having no coil, it is possible to further avoid interference with parts. Further, one end of each of the two return springs is attached to one web separately from the first surface and the second surface, and the other ends of both return springs are attached to both sides of the other web with the first surface. If the two springs are assembled in a crossed manner by changing the second surface, the directions in which the springs try to incline the brake shoes are opposite to each other, and this action balances the brake shoes. It does not tilt and can be assembled without increasing the shoe clearance when assembling the drum.

[0012]

【Example】

 1 to 3 show an embodiment of the present invention, FIG. 1 is a sectional view similar to FIG. 5 showing the relationship between a brake shoe and a return spring, and FIG. 2 is a front view of a backing plate excluding a drum. 3 is a bb sectional view of FIG. The same parts as those of the conventional device are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows the basic structure of the return spring assembly structure of the present invention. The one end portion 22a of the return spring 22 having the entire coil formed thereon is located on the surface (the first surface in the present specification) 19 of the web 2 of the first brake shoe 1 on the backing plate 7 side. Then, the other end 22b of the return spring is positioned on the surface of the web 2a of the second brake shoe 1a on the side opposite to the backing plate (this is referred to as the second surface in this specification) 20a. To the web as shown in FIG. Therefore, the middle portion of the spring 22 crosses the planes of the webs 2 and 2a obliquely.

When the return spring 22 is assembled in this way, the both brake shoes 1, 1a receive a force for tilting them in the directions of arrows A, A. However, the direction in which the brake shoe is tilted is the same, and since the linings 10 and 10 of both brake shoes do not open the gap, it is not necessary to retreat the brake shoes significantly when the drum is assembled, and the shoe clearance after the drum is assembled. The adjustment work can be streamlined.

Next, an embodiment of the return spring incorporated in the two-leading type drum brake shown in FIGS. 2 and 3 will be described. The first return spring 15 (the upper one in FIG. 2) is provided at both ends. A first coil portion 15a and a second coil portion 15b are formed, and both coil portions 15a and 15b are connected by a wireless connecting portion 15c having no coil. As shown in FIG. 3, the coil portions 15a and 15b are assembled on the upper and lower surfaces of the two webs with their axes eccentric, so that the connecting portion 15c is inclined with respect to the axis lines of both coil portions. .

The second return spring 16 (the lower one in FIG. 1) is also formed of eccentric coil portions 16a and 16b at both ends and a coilless coupling portion 16c that couples both coil portions. The connecting portion 16c is inclined with respect to the eccentric coil portions 16a and 16b. Since both return springs are assembled to the web as described later, the inclination direction thereof is opposite to that of the connecting portion 15c of the first return spring 15.

The coil portions 15a and 15b of the first return spring 15 are provided with hook portions 17a and 17b whose ends are bent laterally, as in the conventional example shown in FIG. Also in the second return bar 16, the ends of the coil portions 16a, 16b are bent laterally to form hook portions 18a, 18b.

The first return spring 15 positions the first coil portion 15 a on the second surface 19 a side of the web 2 of the first brake shoe 15 and locks the hook portion 17 a in the hole of the web 2. The second coil portion 15b at the other end is located on the side of the first surface 20 of the web 2a of the second brake shoe, and the hook portion 17b is locked in the hole of the web 2a.

Contrary to the first return spring 15, the second return spring 16 has the coil portion 16a on the first surface 19 side of the web 2 and the coil portion 16b on the second surface 20a side of the web 2a. The hook portions 18a and 18b are locked in the holes of the webs 2 and 2a, respectively.

The first return spring 15 tries to incline the lining of the first brake shoe 1 inward (direction B in FIG. 3), and the second brake shoe 1a moves its lining outward (also B Direction) to add force to try to bring it down. The second return spring 16, on the contrary, exerts a force that tends to tip the lining of the first brake shoe 1 outwards and the tip of the second brake shoe 1a inward. However, the actions of the two springs are opposite to each other and their elastic forces are equal, so that both brake shoes cannot fall to either side. Therefore, when assembling the drum, the drum can be assembled even if the lining is sufficiently close to the inner peripheral surface of the drum, and the amount of adjustment of the gap between the lining and the inner peripheral surface of the drum after assembly is small. . Even if the return spring is assembled in this way, the action of returning the brake shoe remains unchanged.

Although the embodiment of the two-leading type drum brake has been described above, the return spring mounting structure of the present invention is not limited to this type of drum brake, but other types of drum brakes (duo servo type, It is also applicable to the leading trailing type, etc.).

[0021]

[Effect of device]

 (1) The return spring is stretched from the first surface of the web of one brake shoe on the backing plate side to the second surface of the other brake shoe on the side opposite to the backing plate, so it is Interference can be avoided easily.

(2) When the coil portions at both ends are connected by a wire-like thin connecting portion, the effect of avoiding interference with the above components can be further improved.

(3) If the two return springs are locked to the opposite surfaces of the webs of the two brake shoes, the mounting surface of the two springs will be reversed for one web. The force of each return spring to try to fall the brake shoes is balanced and the brake shoes cannot fall.

(4) Since it operates as described above, it is not necessary to previously make the shoe gap excessive when assembling the drum and to adjust the gap small after the drum is assembled.

(5) The return action of the brake shoe by the return spring is the same as the conventional one.

(6) Since the parts are provided on the backing plate, the spring can be assembled with a margin even if the place for installing the return spring is narrow.

[Brief description of drawings]

FIG. 1 is a side view showing a basic structure for assembling a return spring from a first surface to a second surface of a web of two brake shoes.

FIG. 2 is a front view of a drum brake without a drum, showing an embodiment of the present invention.

3 is a sectional view taken along line bb of FIG.

FIG. 4 is a front view of a drum brake schematically showing a conventional return spring mounting structure.

FIG. 5 is a schematic side view showing a conventional first type return spring assembled state.

FIG. 6 is a schematic side view showing a state where a conventional second type return spring is assembled.

[Explanation of symbols]

 1 1st brake shoe 1a 2nd brake shoe 2, 2a web 3 1st return spring 3a 2nd return spring 4, 4a Hook part 5, 5a hole 6 Hole down device 7 Backing plate 8, 8a Wheel cylinder 9 Slack adjuster 10 Lining 11 Shaft hole 12 Bolt hole 13, 13a Hook part 14 Return spring 15 First return spring 15a, 15b Coil part 15c Connecting part 16 Second returning spring 16a, 16b Coil part 16c Connecting part 17a, 17b, 18a, 18b Hook part 19 1st surface 19a 2nd surface 20 1st surface 20a 2nd surface 21 Adjustment gear 22 Return spring 22a One end 22b The other end

Claims (3)

[Scope of utility model registration request] 1. A pair of brake shoes supported by a backing plate fixed to a vehicle body so as to be capable of expanding, a drive device for pressing these brake shoes against an inner peripheral surface of a brake drum, and both brake shoes. In a drum brake having a return spring for returning to a braking position, one end of the return spring is positioned on the first surface of the web of one brake shoe on the backing plate side of the web and is locked to this web, and the other end is A structure for assembling a brake shoe return spring for a drum brake, wherein the brake shoe return spring is mounted on a second surface of the brake shoe opposite to the backing plate of the web and locked to the web. 2. The return spring is formed of coil parts at both ends and a part without a coil connecting both coil parts, and each coil part is formed by a hook part laterally bent from the end part of the web. The brake shoe return spring assembly structure for a drum brake according to claim 1, wherein the brake shoe return spring is attached to the brake shoe return spring. 3. The ends of the two return springs are separately mounted on the same brake shoe web on a first surface and a second surface, and two end portions are mounted on the two brake shoes. 2. The brake shoe return spring assembly structure for a drum brake according to claim 1, wherein the return springs are arranged in a cross shape.