JPH0135081Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic adjustment device for a drum brake used in a motorcycle or the like, which automatically adjusts the gap between the drum and the brake shoe, and particularly relates to a safety device thereof.

In mechanical drum brakes that widen the brake shoe using a cam, there are various automatic adjustment devices that use one-way clutches to adjust the gap between the drum and the brake shoe depending on the rotation angle of the camshaft. Proposed. For example, when the cam rotates over a certain angle, the ratchet mechanism displaces the cam's initial position to adjust the gap between the inner circumference of the drum and the brake shoe, and the brake lever that rotates the cam. A one-way clutch is provided between the brake levers and the brake lever is automatically adjusted to return to its initial position in response to rotational displacement of the cam.

This type of drum brake automatic adjustment device is
If the one-way clutch fails, there is a problem that the brake may not work, such as the actuating part spinning or not being able to rotate at all.

In view of these points, it is an object of the present invention to provide an automatic drum brake adjustment device that can reliably apply the brakes even if the one-way clutch fails.

In order to achieve the above object, the present invention provides an automatic drum brake adjustment device for adjusting the gap between the drum and the brake shoe depending on the rotation angle of the camshaft, in which a first gear 2 is provided on the camshaft 1; A second gear 3 that meshes with the first gear 2 in the form of a threaded gear is provided on the brake body 5 via a one-way clutch 4, and the one-way clutch 4 is rotatably inserted into the support shaft 6. It was supported by being pressed against the stopper part 8 by the member 7.

Here, the operation of the present invention will be explained.

The first gear 2 and the second gear 3 do not normally mesh with each other, but when the camshaft 1 rotates beyond a predetermined angle, they become properly meshed. When the camshaft 1 is rotated by a brake operation and the rotation angle exceeds a predetermined angle due to wear of the brake shoe, the first gear 2 engages with the second gear 3 provided on the brake body 5. At the same time, the second gear 3 is rotated by the rotational force of the camshaft 1. When the camshaft 1 returns, the second gear 3 is held in a non-rotating state by the one-way clutch 4, and as a result, the first gear 2 is rotated and the screw is pulled out between the end faces of the brake shoes 9. Increase the distance l. This reduces the gap between the inner peripheral portion of the brake and the brake shoes 9, 9. Also,
Even if the one-way clutch 4 is locked, if the camshaft 1 is strongly rotated using the brake lever, the rotational force of the camshaft 1 will exceed the load of the spring member 7 supporting the one-way clutch 4. Then, the inner portion 28 of the one-way clutch 4 and the support shaft 6 slip, causing the second gear 3 and the one-way clutch 4 to rotate together, and the camshaft 1 to rotate, thereby operating the brake. When the camshaft 1 returns, the one-way clutch 4 and the second gear 3 are rotated as the first gear 2 rotates together with the camshaft 1, and the brake operation is released. Next, when the one-way clutch 4 is idling, the second gear 3 becomes idling, and the first gear 3, which is rotated together with the rotation of the camshaft 1,
The gear 2 meshes with the second gear 3, and the camshaft 1 rotates while rotating the second gear 3, thereby operating the brake. When the camshaft 1 returns, the first gear 2, which rotates together with the camshaft 1, rotates the second gear 3 in the opposite direction, and the camshaft 1 rotates to release the brake operation.

Next, one embodiment of the present invention will be described.

In FIG. 1, 10 is a brake drum, which rotates together with a wheel attached to an axle 11. Reference numeral 5 indicates a main body of the brake, which is fixed to a fixed member. Brake shoes 9, 9 are half-moon shaped and are disposed facing each other with their back sides facing the inner periphery of the drum 10. Friction members 12, 12 are attached to the back sides of the brake shoes 9, 9, and the drum 10
It is set so that there is a slight gap between it and the inner circumferential part of. An anchor pin 13 is fixed to the main body 5 in parallel with the axle 11, and supports one end of the brake shoes 9, 9. As a result, the brake shoes 9, 9 rotate about the anchor pin 13 as a fulcrum. Return springs 14, 14 are stretched between the opposing brake shoes 9, 9, and urge the brake shoes 9, 9 toward each other. 1 is the camshaft, the second
As shown in FIG. 3, a bifurcated portion 15 is provided at the shaft end on the brake shoe side, and a collar portion 16 and a shaft portion 17 are integrally formed below the bifurcated portion 15. A serration 19 on which a lever 18 is mounted is formed at the other shaft end. The camshaft 1 is inserted into a through hole 20 formed at a predetermined position in the main body 5, and the flange 16 of the camshaft 1 comes into contact with the inner end surface of the through hole 20, and the camshaft 1 comes out to the outside of the main body. It prevents The camshaft 1 is rotatable in the through hole 20 of the main body 5, and the shaft portion 1
A grease reservoir groove 21 is formed at 7. A through hole 2 is formed in the branch pieces 22, 22 of the bifurcated portion 15 of the camshaft 1.
3 and 23 are provided. The shaft portions 25, 25 of the contact members 24, 24, which come into contact with the end surfaces of the brake shoe, are slidably inserted into the through holes 23, 23 of the branch pieces 22, 22, respectively. The shaft portions 25, 25 of the abutting members 24, 24 are formed with threaded portions 26, 27 in mutually opposite directions that thread into the first gear 2, that is, one has a left-hand thread and the other has a right-hand thread. On the inside of the bifurcated portion 15 of the camshaft 1, the first gear 2 is screwed into the threaded portions 26 and 27 of the abutment member, respectively.
will be established. A second gear 3 that meshes with the first gear 2 in the form of a screw gear is attached to a support shaft 6 fixed to the brake body 5 via a one-way clutch 4. The first gear 2 and the second gear 3 are arranged so that they are not in regular meshing under normal conditions, but are in regular meshing when the camshaft rotates beyond a predetermined angle. The one-way clutch 4 is inserted between the support shaft 6 and the inner side 28 of the one-way clutch 4 with a very small gap therebetween, making the one-way clutch 4 freely rotatable.
The second gear 3 can only be rotated clockwise in FIG. The second gear 3 is supported by pressing the inner side 28 of the one-way clutch 4 against a flange-shaped stopper portion 8 provided approximately at the center of the support shaft 6 by a disc spring 7. 29 is a stopper member for the disc spring 7. The one-way clutch 4 presses and supports the inner part 28 of the one-way clutch with a predetermined load by the disc spring 7, so that the inner part 28 of the one-way clutch 4 is pressed against the inner part 28 of the one-way clutch 4 under normal meshing between the first gear 2 and the second gear 3. Do not rotate. With the above configuration, when the camshaft 1 rotates beyond a predetermined angle due to wear of the brake shoes 9, 9, the first gear 2 meshes with the second gear 3 provided on the brake body 5, and the camshaft rotates. The second gear 3 is rotated by the rotational force. When the camshaft 1 returns, the second gear 3 is in the non-rotating direction due to the one-way clutch, so the first gear 2 is rotated and the screws of the abutment members 24, 24 are pulled out and the brake shoes 9, The distance l between the end faces of the drums 9 is increased to reduce the gap between the inner circumference of the drum and the brake shoes 9, 9. Furthermore, when the one-way clutch 4 is locked, since the inner part 28 of the one-way clutch 4 is rotatably supported by the spring member 7, the rotational force of the camshaft 1 outweighs the load of the spring member 7. When the force of the gear 2 to rotate the second gear 3 becomes stronger, the inner part 28 of the one-way clutch 4 and the support shaft 6 slip, causing the camshaft 1 to rotate and perform a brake operation. In addition, when the camshaft 1 idles, the first gear 2 rotating together with the camshaft 1 rotates the second gear 3 by the rotational force of the camshaft 1, and the camshaft 1 rotates to perform a brake operation. As mentioned above, if the one-way clutch becomes locked or slips, the adjustment device will become completely inoperable.
The brake can be operated reliably.

As mentioned above, the present invention ensures that even if the one-way clutch in the drum brake automatic adjustment device becomes locked or slips, the brake operating section will not slip or become unable to rotate, and the brakes will be operated reliably. can be done.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a perspective view showing the relationship between the camshaft and the first gear, and FIG. 3 is an enlarged sectional view taken along line A--A in FIG. Explanation of symbols, 1...Camshaft, 2...First gear,
3...Second gear, 4...One-way clutch, 5
... Brake body, 6 ... Support shaft, 7 ... Spring member, 8 ... Stopper part.

Claims (1)

[Scope of utility model registration request] In an automatic drum brake adjustment device that adjusts the gap between the drum and the brake shoe depending on the rotation angle of the camshaft, a first gear 2 is provided on the camshaft 1 and meshes with the first gear 2 in the form of a screw gear. Second
The gear 3 is installed on the brake body 5 via the one-way clutch 4, and the one-way clutch 4 is rotatably inserted into the support shaft 6, and the one-way clutch 4 is pressed against the stopper part 8 by the spring member 7 and supported. Automatic adjustment device for drum brakes.