JPH0710110Y2 - Drum brake - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a drum brake incorporating a parking brake.

(Prior Art) Some of the drum brakes have a built-in parking brake used during parking. As this type of drum brake, there is a conventional one having a structure as shown in FIGS. 5 to 7. .

This is a leading / trailing type drum brake, and a back plate 3 with a pair of brake shoes (leading side brake shoe 1 and trailing side brake shoe 2) is fixed to a non-rotating part (not shown) of the vehicle. Has been done. Each brake shoe 1, 2 has a lining material 4, 5 on the outer circumference.
Are affixed respectively, and webs 1a and 2a are projected inside. Anchor 8 is fixed to rivet 7 on anchor mounting portion 6 protruding from the front side of back plate 3, and anchor 8 is composed of anchor body 8a and anchor plate 8b fixed to anchor body 8a. On the other hand, one end of each brake shoe 1, 2 is in sliding contact with the anchor body 8a.
The other ends of the brake shoes 1 and 2 are engaged with respective piston rods 11 and 12 of a wheel cylinder 10 having two pistons (one of which is not shown) 9. In addition, each brake shoe
Two return springs 13,1 that urge the brake shoes 1,2 in the direction of contracting (non-braking side) near both ends of 1,2.
4 is mounted. With this configuration, when hydraulic pressure is supplied to the wheel cylinders 10, the brake shoes 1 and 2 expand with the anchor 8 as a fulcrum. In addition, in the figure 15,16
Is a shoe hold spring, which is supported by shoe hold pins 17 and 18 erected on the back plate 3 to bias the brake shoes 1 and 2 toward the back plate 3. 16a is the web of the shoe hold spring 16 and the brake shoe 2.
The retainer is interposed between 2a (the same retainer is also interposed between the shoe hold spring 15 and the web 1a of the brake shoe 1).

A vehicle rotary shaft S such as an axle shaft penetrates through the center of the back plate 3, and a brake drum 19 is rotatably mounted around the shaft S together with wheels (wheels, not shown). The inner surface of the brake drum 19 has brake shoes 1,
Since the brake shoes 1 and 2 are located outside with a predetermined clearance, the brake shoes 1 and 2 are brought into pressure contact with the inner peripheral surface of the brake drum 19 to generate a braking force.

Next, the structure of the parking brake will be explained. In the vicinity of the other end side of each brake shoe 1, 2, the brake shoe 1, 2
Struts 20 having an automatic adjustment mechanism for adjusting the clearance between the brake drum 19 and the brake drum 19 are suspended.
Also, on the other end side of the trailing side brake shoe 2,
One end of the parking lever 21 is rotatably attached to the shaft, and the parking lever 21 is engaged with the strut 20. The other end of the parking lever 21 is connected to a parking brake lever in a vehicle compartment (not shown) via a cable 23 guided by a guide member 22. Parking lever 21
Between the guide member 22 and the guide member 22, a return spring member 24 composed of a coil spring for returning the parking lever 21 to the original position is inserted with the cable 23 inserted, and the return position of the parking lever 21 is returned. Then, parking lever 21
It is positioned by the projection 21a formed integrally with the.

With this configuration, when the parking brake lever is operated, the parking lever 21 rotates via the cable 23 and presses the strut 20 toward the leading side brake shoe 1 side to bring the leading side brake shoe 1 into pressure contact with the brake drum 19. The trailing brake shoe 2 is pressed against the brake drum 19 by the reaction force.

The automatic clearance adjustment mechanism, as shown in FIG.
Adjust screw on one rod 25 of strut 20
25a is provided, an adjusting gear 26a that meshes with the adjusting screw is provided on the other rod 26, and the strut 20 can be extended by rotating the adjusting gear 26a.
An adjustment lever 28 is provided which moves when the brake shoes 1 and 2 are widened by (shown in FIG. 7) and engages with the adjusting teeth formed on the outer circumference of the adjusting gear 26a to rotate. Is.

(Problems to be solved by the invention) However, in a conventional drum brake incorporating a parking brake, a member (protrusion 21a in the above-mentioned conventional example) for restricting the return position of the parking lever 21 is provided. No member for restricting the maximum rotation position of the parking lever 21 is provided. Therefore, when the parking brake lever is pulled too hard, there is a risk that the parking lever 21 will rotate and hit the rotating shaft S as a shaft that penetrates through the center of the back plate 3, thus damaging the rotating shaft S. There was a problem that rust was generated and the parking lever 21 was bent, resulting in malfunction.

The present invention has been made in view of the above problems, and its purpose is to prevent damage to the shaft penetrating the center of the back plate and the parking lever by regulating the maximum rotation position of the parking lever. To provide the drum brakes.

(Means for Solving the Problems) A drum brake of the present invention is provided on a back plate side by a back plate attached to a non-rotating portion of a vehicle and a shoe hold spring supported by a pin erected on the back plate. A pair of brake shoes that are urged and mounted on the back plate so that they can expand and contract, and a pair of brake shoes that are rotatably provided together with the vehicle around an axis that penetrates the back plate and that are pressed by the brake shoes. A drum brake comprising: a brake drum that generates power; and a parking lever that opens the brake shoe via a cable by operating a parking brake lever, wherein a pin that supports the shoe hold spring is provided on the parking lever. A stopper hole that engages with the pin when the parking lever rotates and restricts the maximum rotation position. It is characterized in that the digits.

A back plate attached to a non-rotating portion of the vehicle and a shoe hold spring supported by a pin standing on the back plate are urged toward the back plate and attached to the back plate so as to be expandable and contractible. A pair of brake shoes, a brake drum that is rotatably provided with a wheel around an axis that penetrates the back plate, and that generates a braking force when the brake shoes are pressed, and a parking brake lever is operated. In a drum brake comprising a parking lever for expanding the brake shoe via a cable, one end is held by a pin supporting the shoe hold spring, and the other end regulates the maximum rotation position of the parking lever. It is characterized in that a stopper member provided with a restriction portion is provided.

(Operation) In the case where the pin supporting the shoe hold spring is inserted into the stopper hole formed in the parking lever, the stopper hole engages with the pin when the parking lever rotates, and the maximum rotation position of the parking lever is restricted. Therefore, the parking lever does not rotate too much and hit the shaft that penetrates the center of the back plate.

Further, in the case where the stopper member held by the pin supporting the shoe hold sping is provided, the maximum rotation position of the parking lever is restricted by engaging the restriction portion of the stopper member when the parking lever rotates. , The parking lever will not rotate too much and will not hit the shaft passing through the center of the back plate.

(Example) Next, the Example of this invention is described based on drawing. In this embodiment, the same members as those of the conventional drum brake shown in FIGS. 5 to 7 are designated by the same reference numerals and detailed description thereof will be omitted.

First, a first embodiment of the present invention will be described with reference to FIGS.

The parking lever 29 is provided with a stopper hole 30 through which the pin 18 supporting the shoe hold spring 16 is inserted. The stopper hole 30 is an arc-shaped elongated hole centered on the rotation center of the parking lever 29. Before the stopper hole 30 hits the rotation axis S as a shaft that penetrates the center of the back plate when the parking lever 29 rotates. Is set to a length at which the parking lever 29 can be stopped, and this stop position is the maximum rotation position of the parking lever 29.

According to this structure, even if the parking brake lever is pulled too much, the rotation of the parking lever 29 is restricted by the pin 18 supporting the shoe hold spring 16 engaging with the stopper hole 30 of the parking lever 29. The rotary shaft S is not scratched, and the parking lever 29 is not bent to cause a malfunction.

Further, the conventional parking lever 21 has a shape so as to escape the pin 18 that supports the shoe hold spring 16 (A portion in FIG. 6).
Since it is not necessary to escape the parking lever 29, the strength of the parking lever 29 is improved. Further, since a separate component is not used to regulate the maximum rotation position of the parking lever 29, the product cost will not be higher than that of the conventional drum brake.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4.

The stopper member 31, which is bent in a substantially U-shape, has a pin 18 supporting the shoe hold spring 16 inserted and held at one end thereof. The bent other end of the stopper member 31 serves as a restricting portion 31a that restricts the maximum rotation position of the parking lever 21, and the restricting portion 31a contacts the rotating shaft S before the parking lever 21 rotates. The parking lever 21 is set at a position where it can be stopped. Further, the stopper member 31 is formed with a bent portion 31b that presses the parking lever 21 toward the web 2a side of the brake shoe 2.

According to the above configuration, since the rotation of the parking lever 21 is restricted by the restriction portion 31a of the stopper member 31 even if the parking brake lever is pulled too much, the rotation shaft S is not hit and the rotation shaft S is damaged. , The parking lever 21 will not bend and malfunction will not occur. In addition, the bent portion 31b formed on the stopper member 31 is attached to the parking lever 21.
Is pressed against the web 2a side of the brake shoe 2,
Vibration of the parking lever 21 during traveling is suppressed, abnormal noise is generated and the parking lever 21 is prevented from loosening, and performance in terms of strength and life is improved.

In the present embodiment, the retainer that is conventionally interposed between the shoe hold spring 16 and the web 2a of the brake shoe 2.
Since the stopper member 31 also serves as 16a, the product cost does not increase significantly.

In addition, in the present embodiment, an example in which the present invention is applied to a drum brake in which a pair of brake shoes 1 and 2 are mounted so as to be expandable and contractible by a fixed anchor 8 is shown, but the present invention is not limited to this. Instead, any type of drum brake can be applied as long as the drum brake incorporates a parking brake that operates a parking lever by a cable.

(Effects of the Invention) As described in detail above, according to the present invention, the maximum rotation position of the parking lever is regulated by inserting the pin supporting the shoe hold spring into the stopper hole formed in the parking lever and restricting the maximum rotation position of the parking lever. It can be prevented from hitting a shaft passing through the center of the back plate.

Further, according to the present invention, the parking lever penetrates the center of the back plate by restricting the maximum rotation position of the parking lever by the restriction portion on the other end side of the stopper member holding the pin supporting one end of the shoe hold spring. It can be prevented from hitting the shaft.

Therefore, it is possible to prevent the parking lever from hitting the rotary shaft, damaging the rotary shaft, and bending the parking lever to cause malfunction.

[Brief description of drawings]

1 is a front view of a first embodiment of a drum brake of the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a second view of the drum brake of the present invention. A plan view of the embodiment, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a sectional view of a conventional drum brake (V in FIG. 6).
-V line sectional view), FIG. 6 is a front view of the conventional drum brake shown in FIG. 5, and FIG. 7 is a VII-VII line sectional view of FIG. 1,2 …… Brake shoe 3 …… Back plate 19 …… Brake drum 21,29 …… Parking lever 30 …… Stopper hole 31 …… Stopper member 31a …… Regulator S …… Rotary shaft

Claims (2)

[Scope of utility model registration request] 1. A back plate attached to a non-rotating portion of a vehicle, and a shoe hold spring supported by a pin erected on the back plate, urged toward the back plate and expandable / contractible to the back plate. A pair of brake shoes mounted on the vehicle, a brake drum that is rotatably provided with a wheel around an axis that penetrates the back plate, and that generates a braking force by pressing the brake shoes, and a parking brake lever. In a drum brake comprising: a parking lever for expanding the brake shoe via a cable by the operation of, and a pin supporting the shoe hold spring is inserted into the parking lever and the parking lever is rotated. A drum brake, characterized in that a stopper hole that engages with the pin and restricts a maximum rotation position is provided in the. 2. A back plate attached to a non-rotating portion of a vehicle, and a shoe hold spring supported by a pin standing upright on the back plate, urged toward the back plate and expandable / contractible to the back plate. A pair of brake shoes mounted on the vehicle, a brake drum that is rotatably provided with a wheel around an axis that penetrates the back plate, and that generates a braking force by pressing the brake shoes, and a parking brake lever. In a drum brake comprising: a parking lever for expanding the brake shoe through a cable by the operation of, and one end held by a pin supporting a shoe hold spring, the other end of the parking lever has a maximum rotation position. A drum brake, which is provided with a stopper member having a regulating portion for regulating.