JPS6410695B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a shun hold down device for a drum brake.

BACKGROUND TECHNOLOGY A pin-type shunt-down device has conventionally been used for drum brakes. This pin-type shoe hold-down device has locking heads at both ends, and includes a pin that passes through the back plate and the web of the brake shoe, and a locking head that is located between the web and the web side of the pin. two cups provided between the cups and having the pin passed through the center; and a cup provided between the two cups, one end of which is fitted into the cup on the locking head side and the other end fitted into the cup on the web side. The pin, compression spring, and two cups protrude from the front side of the web, and the pin protrudes from the back side of the web all the way to the back plate.

Problems to be Solved by the Invention However, in a drum brake equipped with such a shoe hold-down device, when a parking lever, an adjustment lever, etc. are arranged on the web of the brake shoe on the back plate side of the web, However, since it is necessary to prevent these from interfering with the portion located between the web of the pin and the back plate, there is a problem in that the installation space for the parking lever, adjustment lever, etc. is limited. This becomes particularly noticeable when drum brakes are downsized in line with recent trends in vehicle weight reduction.

On the other hand, as described in Japanese Utility Model Publication No. 54-41914, for example, a linear spring member is disposed between both brake shoes with its intermediate portion fixed to the back plate, and the linear spring member is If both ends of the spring member are used to press both brake shoes against the back plate, there will be no shoe hold-down device between the brake shoes and the back plate. It is thought that sufficient space can be secured for installation of parking levers etc.

However, in this case, since the intermediate portion of the linear spring member is located on the inner circumferential side of the back plate, when assembling the drum brake to the non-rotating member on the inner circumferential side of the back plate, the linear spring member This may get in the way and interfere with the drum brake assembly work.

The present invention has been made against the background of the above-mentioned circumstances, and its object is to create a system that can secure sufficient installation space for parking levers, etc. without causing any hindrance to the assembly work of drum brakes. An object of the present invention is to provide a u-hold down device.

Means for Solving the Problems In order to achieve the above object, the present invention has a plate-shaped and arc-shaped web, and the web is disposed on the back plate in a state substantially parallel to the back plate. A drum brake comprising a pair of brake shoes and an anchor block fixed on a back plate thereof and in contact with one end of the brake shoes to receive braking torque generated in the brake shoes. A shoe hold-down device for movably supporting the brake shoe along the back plate, the shoe hold down device being fixed to the anchor block in a cantilevered manner and facing the surface of the web of the brake shoe opposite to the back plate side. a leaf spring extending from the anchor block along the arc of the web, the free end of the leaf spring being brought into contact with the web by the elastic force of the leaf spring itself;
It is characterized in that the brake shoe is pressed against the back plate.

Operation and Effects of the Invention According to the shoe hold-down device configured as described above, the leaf spring fixed to the anchor block in a cantilevered manner is positioned on the side of the web of the brake shoe opposite to the back plate side. The elastic force of the leaf spring itself forces the brake shoe against the back plate via the free end of the leaf spring. Therefore, there is no shoe hold-down device between the brake shoe and the back plate, making it possible to secure sufficient installation space for the parking lever, etc. disposed between the brake shoe and the back plate. .

Furthermore, since the leaf spring extends from the anchor block along the arc of the web while facing the surface of the web of the brake shoe on the side opposite to the back plate side, the space on the inner peripheral side of the back plate is As a result, the above-mentioned effects can be obtained without hindrance to the work of assembling the drum brake to the non-rotating member.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

In FIGS. 1 and 2, a pair of brake shoes 2 and 4 are disposed on a back plate 20. As shown in FIGS. One ends of the brake shoes 2 and 4 are respectively engaged with a pair of pistons (not shown) of a wheel cylinder 8 fixed on a back plate 20 by the biasing force of a shoe return spring 6. The other ends of the wheels 2 and 4 are brought into contact with an anchor block 12 fixed on a back plate 20 by the biasing force of a retainer spring 10, respectively. Brake show 2,
4 is configured to have webs 14 and 16 that are plate-shaped and arc-shaped, and the webs 14 and 16 are disposed substantially parallel to the back plate 20. A bulging portion 18 that bulges out toward the center of the drum brake is formed in the longitudinal center portion of the webs 14, 16.

A parking lever 2 is provided on the surface of the web 14 of the brake shoe 2 located on the back plate 20 side.
2 and an adjustment lever 24 are rotatably attached by a common pin 26 near the wheel cylinder 8, with the parking lever 22 sandwiched between the adjustment lever 24 and the web 14. The adjustment lever 24 is biased in the rim direction (clockwise direction in FIG. 1) by a tension spring 28, and has a claw portion 3 at the end.
0, the movement of the parking lever 22 is followed. This parking lever 22
A strut 32 is spanned between one web 14 and the other web 16,
The gap between the brake shoes 2, 4 and the drum shown by the two-dot chain line in FIG. 2 is adjusted to a constant value.

On the surface of the anchor block 12 opposite to the back plate 20 side, a plate spring 34 having a generally U-shape is provided at two locations in the center for fixing the anchor block 12 to the back plate 20. It is fixed in a cantilevered manner by rivets 36. Both arms of the leaf spring 34 are made to extend in opposite directions from the anchor block 12 along the arcs of the webs 14 and 16 while facing the surfaces of the webs 14 and 16 on the side opposite to the back plate 20 side. . The leaf spring 34 is provided with a holding portion 40 that presses the retainer spring 10 toward the back plate 20, and the leaf spring 34 also serves as a retainer plate. The free ends of both arms of the leaf spring 34 form an elliptical dish-shaped pressing part 42, and the elastic force of the leaf spring 34 contacts the bulges 18 of the webs 14, 16 to push the brake shoes 2, 4. is pressed against the back plate 20.

As shown in FIG. 3, a concave portion 44 is provided in the center of the pressing portion 42 of the leaf spring 34, and a concave portion 44 is formed between the concave portion 44 and the web 14 (the same applies to the web 16 side). The space is filled with grease 46. The pressing portion 42 of the leaf spring 34 further has a handle 48 formed in an arc shape by once extending away from the edge of the pressing portion 42 and then curving toward the pressing portion 42 again.
is provided.

In the shoe hold-down device configured as described above, the brake shoes 2 and 4 are pressed against the back plate 20 only from the front side (the side opposite to the back plate 20 side), and the brake shoes 2 and 4 are pressed against the back plate 20 only from the front side (the side opposite to the back plate 20 side), and the brake shoes 2, 4 are pressed against the back plate 20 only from the front side (the side opposite to the back plate 20 side), and the brake shoes 2 and 4 are pressed against the back plate 20 only from the front side (the side opposite to the back plate 20 side). Since there is no space at all, sufficient installation space is secured for the parking lever 22, adjuster lever 24, etc., which are disposed on the back side of the web 14, that is, between the web 14 and the back plate 20. This makes it easier to downsize.

Moreover, both arms of the leaf spring 34 are attached to the back plates 20 of the webs 14, 16 of the brake shoes 2, 4.
The webs 14, 16 face the opposite side.
are extended from the anchor block 12 along the circular arcs of the back plate 20, and are housed in the space formed by the webs 14, 16 and the seal rim. can be secured. As a result, when assembling the drum brake to a non-rotating member such as an axle pipe using bolts or the like on the inner circumferential side of the back plate 20, the shew hold-down device does not interfere with the assembly work of the drum brake. be.

Further, according to this embodiment, since the space formed between the concave portion 44 of the pressing portion 42 of the leaf spring 34 and the webs 14, 16 is filled with the grease 46, the pressing portion 42 and the web 14, There is an advantage that the coefficient of friction during sliding with the brake shoes 16 is reduced, and the movement of the brake shoes 2 and 4 can be achieved smoothly.

Further, according to the present embodiment, since a handle 48 is provided on the pressing portion 42 of the leaf spring 34, when assembling the brake shoes 2 and 4 to the back plate 20, the handle 48 must be hooked. By simply pulling up against the elastic force of the leaf spring 34, the brake shoe 2,
A sufficient space for inserting the brake shoes 2 and 4 can be easily secured, and the assembly work of the brake shoes 2 and 4 can be performed efficiently.

In the above-mentioned embodiment, the case where the shew hold down device of the present invention is applied to the LT type drum brake has been described, but the present invention can also be applied to the 2L type drum brake. In this case, anchor blocks are usually provided integrally with each of the pair of wheel cylinders, so one leaf spring is cantilevered at one end of each anchor block, and the other end of each leaf spring is fixed to each anchor block in a cantilevered manner. The pair of brake shoes are configured to be pressed separately against the back plate.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a state in which a shuffle down device according to an embodiment of the present invention is assembled to a drum brake. FIG. 2 is a cross-sectional view taken in FIG. FIG. 3 is an enlarged view showing a main part of a cross section taken along the line - in FIG. 1. 2, 4... Brake shoe, 12... Anchor block, 14, 16... Web, 20... Back plate, 34... Leaf spring, 42... Pressing portion.

Claims (1)

[Scope of Claims] 1. A pair of brake shoes having plate-shaped and arc-shaped webs and disposed on the back plate in a state where the webs are substantially parallel to the back plate;
In the drum brake, the drum brake is provided with an anchor block fixed on the back plate and in contact with one end of the brake shoe to receive braking torque generated in the brake shoe, in which the brake shoe is moved along the back plate. A shoe hold-down device movably supported, which is fixed to the anchor block in a cantilevered manner, and faces a surface of the web of the brake shoe opposite to the back plate side, and extends the arc of the web. a leaf spring extending from the anchor block along the web, the free end of the leaf spring being brought into contact with the web by the elastic force of the leaf spring itself to press the brake shoe against the back plate. A drum brake show hold down device characterized by: