JPH0718041U - Brake shoe for drum brake - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a brake shoe for a drum brake that produces less noise during braking and does not weaken the strength of the brake shoe end. [Structure] A brake shoe 4 has a T-shaped cross section, which is formed by connecting a web 4a and a rim 4b, and is lined up on the rim 4b.
Is stuck. The end of the lining 4c has a central portion 12
Is left, and both sides thereof are chamfered to form the side chamfered portion 11.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a brake shoe for a drum brake that is pressed against the inner peripheral surface of the drum during braking, and has a brake shoe that generates less noise during braking and that does not reduce the strength of the ends. .

[0002]

[Prior art]

 There are various types of drum brakes, but as an example, a two-leading type drum brake schematically shown in FIG. 6 will be described. An immovable backing that is fixed to the vehicle body overlaps the drum 1 that rotates with the wheels. There is a plate 2 on which two wheel cylinders 3 are fixed, one end of a web 4a of two brake shoes 4 arranged in a circle is pivotally attached to the backing plate 2 by a pin 5, The other end of the web 4a is supported by a piston rod 6 protruding from the wheel cylinder 3.

During braking, when pressure oil is fed from the oil feed pipe 7 to the wheel cylinder 3, one end of the web 4a is pushed by the piston rod 6 and the brake shoe 4 rotates about the pin 5 as an axis to reach the web 4a. The lining 4c, which is superposed and fixed on the rim 4b coupled to the T-shaped cross section, is pressed against the inner peripheral surface of the drum 1, and the wheels are braked via the drum by the friction between the lining and the drum inner peripheral surface.

When the pressure oil is removed from the wheel cylinder 3 in order to release the braking, the brake shoe is separated from the inner peripheral surface of the drum by the return spring 8 and the drum and the wheels are freely rotated.

In the drum brake that operates in this way, as shown in FIG. 7, if the end 4d of the lining 4c of the brake shoe 4 on the drum turning-in side is cut up at a right angle without chamfering, noise ( Noise).

[0006] The reason is that it is difficult to manufacture the inner peripheral surface of the drum in a strict circular shape, so that the frictional action between the end 4d of the lining cut at a right angle and the inner peripheral surface of the drum is small, but the difference in strength is small. It is considered that the vibration of the end portion 4d caused by this causes the vibration force of the entire brake shoe.

In order to avoid such noise generation, as shown in FIGS. 8 and 9, the end portion of the lining is chamfered uniformly in the width direction at an angle of about 15 °.

[0008]

[Problems to be solved by the device]

 When chamfering the lining end as described above, when the distance a (FIG. 8) between the position 9 where the lining end contacts the inner peripheral surface of the drum and the fulcrum 10 of the web 4a supported by the piston rod 6 is not chamfered. It becomes larger than the distance b in (Fig. 7) and weakens the strength of the brake shoe end.

[0009]

[Means for solving the problem]

 This invention eliminates the above-mentioned drawbacks by forming a side chamfer at the end of the lining, which is chamfered so as to be inclined toward the side surface of the lining, leaving a central portion where the web is located.

[0010]

[Action]

 Since the end of the lining leaves the central portion where the web is located, the distance between the fulcrum 10 and the position 9 where the inner peripheral surface of the drum contacts the lining end is equal to the distance b in FIG. Since it can be made as small as the above, and can be made smaller than the distance a in the case of the shapes of FIGS. 8 and 9, the strength of the brake shoe end is not weakened.

When the lining end is chamfered so as to incline toward the side surface of the lining, leaving only the narrow central portion where the web is located, the sharp central portion vibrates, but this vibration can be ignored. Since it is so small, there is no danger of inducing vibration of the entire brake shoe.

Japanese Utility Model Laid-Open No. 62-71422 discloses a structure in which an edge of the lining that is cut up at a right angle is inclined with respect to the turning direction of the drum. Since it is orthogonal to the drum inner peripheral surface over the entire direction, the lining end easily vibrates during braking as in the case of Fig. 7, and the width of the cut end is large. The risk of inducing overall vibration is great.

[0013]

【Example】

 1 to 5 show two embodiments of the brake shoe of the present invention, FIG. 1 is a side view of an end portion of the brake shoe with a part cut away, and FIG. 2 is a plan view of the same. 3 is a perspective view of the same as above, FIG. 4 is a side view of the end of the brake shoe with a part cut away, and FIG. 5 is a plan view of the same. In each figure, the same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

In the first embodiment of FIGS. 1 to 3, the end portion of the lining 4c is a side chamfered portion 11, 11 which is chamfered to be inclined toward the side surface of the lining, and a central portion without chamfering therebetween. 12 are left. The arrow indicates the direction of inclination of the side chamfer 11. The central portion 12 is cut off at a right angle so that it contacts the drum 1 at the position 9.

Since the lining end is formed in this way, when the brake shoe is pressed against the inner peripheral surface of the drum 1 during braking, the position 9 where the lining end contacts the inner peripheral surface of the drum and the fulcrum 10 of the web. The distance is b as in FIG. 7, and it is possible to avoid weakening the ends of the brake shoes. Further, since the side chamfered portions 11 are formed on both sides, the width of the position 9 where the end of the central portion 12 contacts the inner peripheral surface of the drum becomes smaller than that in the case of FIGS. 8 and 9, and this end vibrates. Even if it does, the vibration force is too weak to induce vibration of the entire brake shoe.

According to a sensory evaluation by an actual vehicle test, in the case of the brake shoe having the structure shown in FIG. 7, noise was always generated, and the degree thereof was large. Was small, and the size was remarkably small.

The second embodiment of FIGS. 4 and 5 is similar to the first embodiment, and the lining end portion is further chamfered at an angle of approximately 20 ° in the tangential direction of the lining. The distance c between the position 9 where the end of the lining contacts the inner peripheral surface of the drum and the fulcrum 10 at the end of the web is larger than the distance b in the case of FIGS. 1 to 3, but the chamfering angle is relatively large. The distance is smaller than the distance a in the case of the conventional structure of FIG. 9, and it is possible to avoid weakening the strength of the end portion of the brake shoe almost similarly to the case of the first embodiment, and the effect of reducing noise is great.

[0018]

[Effect of device]

 (1) Since the position of the center of the lining end that contacts the drum inner peripheral surface is close to the fulcrum of the web, the end of the brake shoe can be prevented from becoming weak.

(2) Since the width of the central part of the lining end is made small enough to correspond to the thickness of the web, even if this end contacts the inner peripheral surface of the drum, it does not cause noise.

[Brief description of drawings]

FIG. 1 is a side view of an end portion of a brake shoe with a part cut away, showing a first embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a perspective view of the same.

FIG. 4 is a side view of a brake shoe end portion with a part cut away, showing a second embodiment of the present invention.

FIG. 5 is a plan view of the above.

FIG. 6 is a schematic diagram of a two-leading type drum brake shown as an example of a drum brake.

FIG. 7 is a side view of an end portion of a brake shoe having a lining with the end portion cut up at a right angle.

FIG. 8 is a side view of an end of a brake shoe having a lining with a chamfered end.

FIG. 9 is a plan view of the above.

[Explanation of symbols]

 1 Drum 2 Backing Plate 3 Wheel Cylinder 4 Brake Shoe 4a Web 4b Rim 4c Lining 4d End 5 Pins 6 Piston Rod 7 Oil Pipe 8 Return Spring 9 Contact with Inner Drum Surface 10 Support 11 Lateral Chamfer 12 Center

Claims (1)

[Scope of utility model registration request] 1. A brake shoe of a drum brake, which is arranged in a circular shape inside a drum and which presses a lining against the inner peripheral surface of the drum during braking to brake wheels via the drum, has a T-shaped cross section on a web (4a). Combined rim (4
At the end of the lining (4c) attached to b), a side chamfered portion (11) that is chamfered to be inclined toward the side surface of the lining is formed, leaving a central portion (12) where the web (4a) is located. Brake shoes for drum brakes.