JPH0219633Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is a drum brake used in motorcycles, automobiles, etc., and the gap between the brake shoe and the inner circumference of the drum is reduced by using a rotational protrusion mechanism of a screw. The present invention relates to a brake shoe clearance adjustment device for a drum brake to be adjusted.

[Conventional technology]

A brake shoe gap adjustment device that has a screw rotating protrusion mechanism consisting of a male threaded member and a female threaded member between the leading and trailing side brake shoe end faces of a drum brake generally has The brake shoe is pushed out evenly to reduce the gap between the brake shoe and the inner circumference of the drum.

[Problem that the invention attempts to solve]

This type of brake shoe gap adjustment device for drum brakes adjusts the gap size between the inner circumference of the drum and the brake shoe by pushing out the end faces of the leading and trailing brake shoes equally. It is.

By the way, in the case of a mechanical leading/trailing type drum brake that is expanded by a cam, the braking force is mainly provided by the brake shoe on the leading side, and therefore the wear of the brake shoe is also greater on the leading side. It is large and the trailing side is small and uneven. On the contrary,
Because the leading side and trailing side are pushed out equally, even if the gap is adjusted, the trailing side brake shoe will contact the brake drum first, and the leading side brake shoe will not be able to handle the braking force. The problem was that the initial braking force could not be maintained.

In view of these points, the present invention improves the braking force of the leading side brake shoe by appropriately adjusting the gap size between the leading side brake shoe and the trailing side brake shoe according to the amount of wear. It is an object of the present invention to provide a brake shoe clearance adjustment device for a drum brake that can be maintained for a long period of time.

[Means for solving problems]

In order to achieve the above object, the present invention provides male threaded members 3, 4, 27 and female threaded members 5, 30, between the end faces of the leading side brake shoes 1, 24 and the trailing side brake shoes 2, 25. 31 is provided, and the male threaded members 3, 4, 27 or the female threaded members 5, 30, 31 of the rotational protrusion mechanisms 6, 26 are rotated to rotate the leading side brake shoe 1, 24 and the trailing side brake shoes 2 and 25,
In the brake shoe gap adjustment device for a drum brake that increases the distance between the end faces of the brake shoe, the externally threaded members 3, 4, 2 of the rotary protrusion mechanism 6, 26
7 and the thread pitch of the female thread members 5, 30, 31,
The side that pushes out the brake shoes on the leading side is made larger than the side that pushes out the brake shoes 2 and 25 on the trailing side.

[Effect]

Male thread members 3, 4, 27 and female thread members 5, 3
The male screw members 3, 4, 27 or the female screw members 5, 30, 3 of the rotary protrusion mechanism 6, 26 consisting of 0, 31
1, the male threaded members 3, 4, 27 and female threaded members 5, 30, 31 which are in contact with the leading and trailing side brake shoes are rotated and protruded, respectively. At this time, the amount of rotational protrusion T for pushing out the brake shoes 1 and 24 on the leading side is larger than the amount of rotational protrusion t for pushing out the brake shoes 2 and 25 on the trailing side. By increasing the distance l between the end faces of the brake shoe in this way, the gap size between the brake shoe and the inner circumference of the drum on the leading and trailing sides is reduced, and the gap size a on the leading side and the trailing side are reduced. Adjust the gap dimension b.

〔Example〕

An example of the present invention will be described.

FIG. 1 shows a device that adjusts the gap between the brake shoes 12 by rotating a cam 7 between the end faces of the leading brake shoe 1 and the trailing brake shoe 2. 8 is a brake drum, which rotates together with a wheel attached to an axle 9. 10 is a main body of the brake, which is fixed to a fixed member. Reference numerals 1 and 2 denote leading side and trailing side brake shoes, which are half-moon shaped and are disposed facing each other with their back sides facing the inner periphery of the drum 8. Friction members 11, 11 are attached to the back sides of the brake shoes 1, 2, and are set so as to have a small gap between them and the inner circumference of the drum 8. An anchor pin 12 is connected to the axle 9 in the main body 10.
brake shoes 1 and 2.
It supports one end of. As a result, the brake shoes 1 and 2 rotate about the anchor pin 12 as a fulcrum. Return springs 13, 13 are stretched between the opposing brake shoes 1, 2, and urge the brake shoes 1, 2 toward each other. As shown in FIGS. 2 and 3, the cam 7 is formed into a bifurcated shape, and its branches 14, 14 are provided with through holes 15, 15. and a male threaded member 3 that comes into contact with the end surfaces of the brake shoes 1 and 2;
4 are slidably inserted into the through holes 15, 15 of the branch pieces 14, 14, respectively. This male screw member 3,
4 is formed with threaded portions 16 and 17 in mutually opposite directions to be screwed into the female threaded member 5, that is, one has a left-handed thread and the other has a right-handed thread. A first gear 18 is formed on the outer periphery of the female threaded member 5. The cam 7
On the inner side, the female threaded member 5 and the threaded portions 16 and 17 of the male threaded member are screwed together, respectively, and a rotating protrusion mechanism 6 is thus constructed. The rotary protruding mechanism 6 has a threaded portion 16 of a male threaded member that pushes out the leading side brake shoe 1.
The thread pitch between the threaded part 19 of the female threaded member and the threaded part 17 of the male threaded member that pushes out the brake shoe 2 on the trailing side is made larger than the threaded pitch between the threaded part 20 of the female threaded member and the leading side male thread. The rotational protrusion amount T of the member 3 was made larger than the rotational protrusion amount t of the male threaded member 4 on the trailing side.

Note that the rotational protrusion amount T of the male threaded member 3 on the leading side and the rotational protrusion amount t of the male threaded member 4 on the trailing side should be set at a ratio of 3 to 1 based on the characteristics of the leading-trailing type drum brake. is preferred.

The first gear 18 of the female threaded member is connected to the second gear 21 provided on the brake body 10 as shown in FIG.
meshes with The second gear 21 is the brake body 1
It is attached via a one-way clutch 23 to a bolt member 22 screwed onto the bolt 22. The second gear 21 is only allowed to rotate clockwise by a one-way clutch 23. Brake shoe 1,
When the friction members 11, 11 of 2 wear out and the gap size between the brake shoes 1, 2 and the inner circumference of the drum increases, the rotation angle of the cam 7 increases and the cam 7 rotates beyond a predetermined angle. do. At this time, the first gear 18 and the second gear 21 are in regular meshing,
The first gear 18 rotates the second gear 21 clockwise in FIG. 1 by the rotational force of the cam 7. and,
Since the second gear 21 is prevented from rotating counterclockwise by the one-way clutch 23 when the cam 7 returns, the first gear 18 is prevented from rotating counterclockwise by the one-way clutch 23.
rotated slightly by 1. This first gear 18
By slight rotation of the screws 16 and 17,
The male threaded members 3 and 4 screwed together project outward due to their respective thread pitches, and the male threaded members 3 and 4 push and spread the end faces of the brake shoes 1 and 2, increasing the distance l between the end faces of the brake shoes 1 and 2. Make it bigger. This reduces the gap between the inner peripheral portion of the drum and the brake shoe.

Next, another embodiment will be explained with reference to FIG. A rotary protrusion mechanism 26 is provided on the anchor pin side between the end faces of the leading side brake shoe 24 and the trailing side brake shoe 25, and a ratchet wheel 2 is provided integrally with a male threaded member 27 by manual operation at appropriate times.
8 in one direction to adjust the gap between the brake shoes. Female thread members 30, 3 are attached to the male thread member 27 rotatably held in the brake body 29.
1 is screwed together, and has grooves 36, 36 at one end of the female thread members 30, 31, and the ends of the brake shoe are brought into contact with the grooves 36, 36, so that the female thread members 30, 31 rotation is regulated. The rotary protrusion mechanism 26 adjusts the thread pitch between the threaded portion 32 of the female threaded member that pushes out the brake shoe 24 on the leading side and the threaded portion 33 of the male threaded member, and the female threaded member that pushes out the brake shoe 25 on the trailing side. The thread pitch between the threaded portion 34 of the male threaded member and the threaded portion 35 of the male threaded member is made larger. By rotating the ratchet wheel 28 of the male threaded member 27, the male threaded member 27 of the rotating protrusion mechanism 26 rotates and pushes out the female threaded members 30, 31. At this time, the female threaded member 30 on the leading side has a larger protrusion amount than the female threaded member 31 on the trailing side.

[Effect of idea]

The present invention adjusts the gap between the leading side and trailing side brake shoes of a drum brake and the inner circumferential portion of the drum using a rotary protruding mechanism of a screw, in which a male threaded member of the rotary protruding mechanism and a female threaded member of the rotary protruding mechanism This drum brake brake shoe gap adjustment device has a screw pitch of the member that is larger on the side where the leading side brake shoe is pushed out than the side where the trailing side brake shoe is pushed out, so the leading side brake shoe has better braking efficiency. The gap size can be adjusted well,
The braking force of the leading side brake shoe with good braking efficiency can be maintained over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a front view of one embodiment of the present invention, Fig. 2 is a perspective view of its rotary protrusion mechanism, Fig. 3 is an enlarged sectional view of the rotary protrusion mechanism, and Fig. 4 is another embodiment of the present invention. FIG. Explanation of symbols: 1, 24... Brake shoe on the leading side, 2, 25... Brake shoe on the trailing side, 3, 4, 27... Male thread member,
5, 30, 31...Female screw member, 6, 26...Rotary protrusion mechanism, T, t...Rotary protrusion amount.

Claims (1)

[Scope of utility model registration request] Between the end faces of the leading side brake shoes 1, 24 and the trailing side brake shoes 2, 25, there are male threaded members 3, 4, 27 and female threaded members 5, 3.
A rotary protrusion mechanism 6, 26 consisting of a rotary protrusion mechanism 6, 26 consisting of
4, 27 or female threaded members 5, 30, 31 to connect the leading side brake shoe 1, 24.
In the drum brake brake shoe gap adjusting device for expanding the distance between the end faces of the brake shoes by pushing out the brake shoes 2 and 25 on the trailing side, 27 and the thread pitch of the female thread members 5, 30, 31, the side that pushes out the leading side brake shoe 2,
A brake shoe clearance adjustment device for a drum brake, characterized in that a diameter of 25 is larger than that on the pushing side.