Improved structure of drum brake

Abstract

The invention discloses an improved structure of a drum brake. A pair of brake shoes is arranged in a drum brake shell, one ends of the brake shoes are rotationally positioned in the shell, an elastic reset element is connected between the brake shoes, a brake cam is arranged in an end gap of the other ends of the brake shoes, bearings are propped between the brake cam and the end surfaces of the brake shoes on the two sides correspondingly, and rotating shafts for the bearings are arranged in shaft holes of the pair of brake shoes. When a brake rocker arm assembly drives the brake cam to rotate, the two bearings are driven to rotate and move, then the pair of brake shoes is driven to form opening and closing movement, and therefore the brake function is achieved; and the outer contour surface of the brake cam is composed of two pairs of curved surfaces and four connecting cylindrical surfaces, the cross section lines of one pair of curved surfaces are convex circular involutes, the other pair of curved surfaces are concave cylindrical surfaces, and four corners formed by the two pairs of curved surfaces are connected through a section of convex cylindrical surface which is tangent to the two curved surfaces at the same time.

Description

technical field [0001] The invention belongs to the technical field of brake devices for motorcycles and electric vehicles. Background technique [0002] Drum brakes have been used as brake components on motorcycles and electric vehicles for nearly a century. Their structure generally consists of a housing, a pair of brake shoes, a brake cam, a brake rocker arm, and elastic reset elements. When braking, the brake rocker arm drives the brake cam to rotate, and the brake cam forces the brake shoe to expand and contact the housing to generate friction and then brake. After braking, rely on the elastic return element to pull the brake shoe back to its original position. During the braking process, in addition to the wear between the brake shoe and the housing, there will also be wear between the brake cam and the brake shoe, and the wear is always concentrated on several points or surfaces of the brake cam, which greatly shortens the brake life. In addition, the existing drum ...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide an improved structure of the drum brake, which changes the working mode of the original drum brake which uses the cam to directly drive the expansion of the brake shoe, and effectively improves the poor braking effect of the existing drum brake, the large sliding distance of the vehicle brake, and the large braking distance of the brake cam. Disadvantages of wear and tear

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