JP2017110799A - Drum brake for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum brake for vehicle which reduces cost by reducing the number of components, and which improves assembly workability.SOLUTION: In the case where a parking brake is released, a parking lever 60 is returned to an initial position by an energization force applied to the parking lever 60 from a return spring 40, and a brake shoe 18 is returned to the initial position as well via a lever pin 62. Thus, a drum brake 10 for vehicle can be constituted by using one component having a plurality of functions of the function of the return spring of the brake shoe 18 and the function of the return spring of the parking lever 60. Thereby, the number of components for constituting the drum brake 10 for vehicle is reduced, so that the cost of the drum brake 10 for vehicle can be reduced, and the assembly workability can be improved.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drum brake for a vehicle, and more particularly to a return spring of a brake shoe.

  In general, a pair of brake shoes that can be expanded on the backing plate and a lever pin positioned at one end of the brake shoe in a state of being overlapped with one backing plate side of the pair of brake shoes. A parking lever having a base end portion provided movably and a tip end portion to which an operating force is applied, a strut spanned between the end portions of a pair of brake shoes, and a spring portion wound around the outer periphery of the strut And a return spring having a pair of latching portions protruding from both ends of the spring portion and directly or indirectly latching on one end portion of the pair of brake shoes are known. For example, the vehicular drum brake described in Patent Document 1 is this.

JP2012-1410112A

  However, the technique disclosed in Patent Document 1 requires a lever return spring for returning the parking lever to the initial position in addition to the shoe return spring latched between the pair of brake shoes. The number of parts related to the brake is large, and the management and assembling work of the parts is complicated.

  The present invention has been made against the background of the above circumstances. The object of the present invention is to reduce the number of parts by configuring the shoe return spring and the lever return spring as one part, thereby reducing the cost. Another object is to provide a vehicular drum brake that improves assembly workability.

  The gist of the present invention is that a pair of brake shoes provided on the backing plate so as to be expandable, and one end portion of one of the pair of brake shoes in a state of being overlapped with one of the backing plates. A parking lever having a base end portion rotatably provided around a lever pin and a tip end portion to which an operating force is applied, a strut spanned between the end portions of the pair of brake shoes, and the strut And a return spring having a spring portion wound around the outer periphery and a pair of hook portions protruding from both ends of the spring portion and hooked directly or indirectly to one end portions of the pair of brake shoes, respectively. In the vehicular drum brake, one of the pair of latching portions of the return spring is the parking brake. The said tip than the bar of the lever pin lies in that hold hung on the opposite side.

  In this way, one of the pair of latching portions of the return spring is latched on the opposite side of the tip from the lever pin of the parking lever, so when the parking brake is released, the return spring Because the parking lever is returned to the initial position by the biasing force acting on the parking lever from the brake pin, the brake shoe is also returned to the initial position via the lever pin, so that the brake shoe return spring function and the parking lever return spring function A vehicle drum brake can be configured by using one component having a plurality of functions. This eliminates the need for the parking lever return spring, which is a compression coil spring that is conventionally mounted on the outer periphery of the parking brake cable, and reduces the number of parts that constitute the vehicle drum brake, thereby reducing the cost of the vehicle drum brake. It can be reduced and the assembly work can be improved.

It is a front view which shows the drum brake for vehicles of an example of this invention. It is a figure which expands and shows the return spring of the Example of FIG. 1, and respond | corresponds to the II-II sectional view taken on the line of FIG.

  An embodiment of the present invention will be described below with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a front view showing a leading trailing type vehicle drum brake 10 according to an example of the present invention. The vehicle drum brake 10 has a substantially disk shape, and includes, for example, a backing plate 16 that is integrally fixed to a non-rotating member such as an axle tube, an axle housing, and a suspension device (not shown), and left and right sides of the backing plate 16. A pair of the outer peripheral portions of the backing plate 16 are arranged symmetrically with respect to the center line C of the backing plate 16 so as to be able to approach and separate from each other with the arcuate convex side facing outward. Between the brake shoes 18, 20 and one end of the pair of brake shoes 18, 20, that is, between the upper ends in FIG. 1, and between the other ends of the pair of brake shoes 18, 20, that is, the figure. 1 and the pair of brake shoes 18 and 20 in addition to an anchor 22 provided in a fixed position by a rivet between the lower ends of Their other ends are stretched between parts and a spring 24 which abuts constantly anchor 22. The center line C is a line passing through the center of the wheel cylinder 26 in the longitudinal direction, the center of the anchor 22 in the longitudinal direction, and the center of the backing plate 16 in the front view of FIG.

  Each of the brake shoes 18 and 20 has a flat plate shape substantially parallel to the plate surface of the backing plate 16, and the shoe webs 28 and 30 that are entirely curved in an arc shape in the front view shown in FIG. Arc-shaped shoe rims 32, 34 that are integrally fixed so that the cross-sections of the brake shoes 18, 20 form a substantially T-shape along the outer peripheral side edge forming the arc shape, and the outer peripheries of these shoe rims 32, 34 The linings 36 and 38 are made of friction materials that are integrally fixed to the surface with an adhesive or the like.

  The brake shoes 18, 20 are pressed toward the backing plate 16 by shoe hold-down devices 52, 54 disposed near the center in the longitudinal direction of the shoe webs 28, 30, so that the backing plate 16 can be expanded. It is arranged.

  A base end portion of a flat parking lever 60 is rotatably connected to the one end portion of the brake shoe 18 around the lever pin 62 by a lever pin 62 so as to overlap the backing plate 16 side. The tip of the parking lever 60 is connected to the parking brake cable 64. When the parking brake is operated by operating a parking brake lever (not shown), the tip of the parking lever 60 is connected to the parking lever 60 via the parking brake cable 64. An operating force is applied, and the tip of the parking lever 60 is rotated toward the center of the backing plate 16. When the front end of the parking lever 60 is rotated, the brake shoe 20 is pushed by the strut 42 and moved to the outer circumferential side, and at the same time the brake shoe 18 is pushed by the lever pin 62 and moved to the outer circumferential side. The brake shoes 18 and 20 are expanded so that the inner peripheral surface of the rotating drum (not shown) and the linings 36 and 38 are brought into sliding contact with each other to generate a braking force.

  A strut 42 is bridged between the one end portions of the brake shoes 18 and 20, that is, between the end portions on the wheel cylinder 26 side. 2 is a sectional view taken along line II-II in FIG. As shown in FIGS. 1 and 2, a spring portion 44 in which a wire having a circular cross section is wound around the outer periphery of the strut 42, and latching portions 46 a and 46 b are provided at respective ends of the spring portion 44. A return spring 40 made of a single spring material bent integrally is stretched between the pair of brake shoes 18 and 20.

  Specifically, the hooking portion 46 a is a hook through which one end of the spring portion 44 is bent toward the outer peripheral side of the vehicle drum brake 10 and passes through the notch 70 provided at the one end of the brake shoe 18. It is turned into a shape. Further, the latching portion 46 a is latched by a latching notch 72 provided on the parking lever 60. That is, the latching portion 46 a is indirectly latched on the one end portion of the brake shoe 18. This notch 70 is formed larger than the latching notch 72 so as not to interfere with the latching part 46 a latched by the latching notch 72. The notch 70 and the latching notch 72 are provided on the opposite side of the tip of the parking lever 60 from the lever pin 62. Therefore, the latching portion 46 a is latched to the parking lever 60 on the opposite side of the tip of the parking lever 60 from the lever pin 62, that is, on the one end side of the brake shoe 18 from the lever pin 62. The latching portion 46b is formed by projecting the other end of the spring portion 44 toward the outer peripheral side of the vehicle drum brake 10, and rotates in a hook shape through which a notch 74 provided in the brake shoe 20 is passed. It is bent and latched in the notch 74.

  Since the parking lever 60 is latched by the latching hole 72 and the latching portion 46a of the return spring 40, the parking lever 60 is returned to the position before the parking brake is actuated by the urging force of the return spring 40, that is, the so-called initial position. Under the moment of For this reason, when the parking brake is released, the parking lever 60 is returned to the initial position by the urging force of the return spring 40 acting on the one end side of the brake shoe 18 with respect to the lever pin 62, and at the same time, the brake shoe 18. Is returned to the initial position via the connected lever pin 62.

  According to the vehicle drum brake 10 of the present embodiment, when the parking brake is released, the parking lever 60 is returned to the initial position by the biasing force acting on the parking lever 60 from the return spring 40, and at the same time, the lever pin 62 Since the brake shoe 18 is also returned to the initial position via the brake, the vehicle drum brake 10 is configured by using a single component having a plurality of functions including a return spring function of the brake shoe 18 and a return spring function of the parking lever 60. can do. As a result, the parking lever return spring, which is a compression coil spring conventionally mounted on the outer periphery of the parking brake cable 64, becomes unnecessary, and the number of parts constituting the vehicle drum brake 10 is reduced. Cost can be reduced, and the assembly work can be improved.

  It should be noted that the above description is merely an embodiment, and other examples are not illustrated. However, the present invention is implemented in variously modified and improved modes based on the knowledge of those skilled in the art without departing from the spirit of the present invention. Can do.

10: vehicle drum brake 16: backing plate 18, 20: brake shoe 40: return spring 42: strut 44: spring portion 46a, 46b: latching portion 60: parking lever 62: lever pin

Claims (1)

A pair of brake shoes provided on the backing plate so as to be expanded;
A base end portion provided to be rotatable around a lever pin positioned at one end portion of the one brake shoe in a state of being overlapped with one backing plate side of the pair of brake shoes, and a tip end portion to which an operating force is applied A parking lever having
Struts spanned between the ends of the pair of brake shoes;
A return spring having a spring portion wound around the outer periphery of the strut and a pair of hook portions protruding from both ends of the spring portion and hooked directly or indirectly to one end portion of the pair of brake shoes; In a vehicle drum brake equipped with
One of the pair of latching portions of the return spring is latched on the opposite side of the tip from the lever pin of the parking lever.

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