JPH0354987Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Purpose of the invention (industrial application field)
This brake device can be used to quickly adjust the gap between the lining and the drum (shoe gap) when a newly manufactured brake is installed on an automobile or when a brake shoe is replaced.

(Prior Art) Drum brakes for automobiles use hydraulic pressure to drive a piston to press against a brake shoe that rotates with the wheels, and brake the automobile via the drum due to friction between the lining of the brake shoe and the drum. Therefore, the lining gradually wears out and the shoe gap gradually increases. If this happens, the distance the brake pedal must be pressed becomes large, which is dangerous, so adjustments must be made to reduce the shoe clearance.

Many auto-slack adjusters have been invented, devised, and put into practice in order to link this adjustment with brake operation and adjust the shoe gap as it increases little by little.

For example, such an auto-slack adjuster is shown in Publication No. 60-25659,
There is also an auto-slack adjuster such as that disclosed in Japanese Patent Application No. 130212/1986 filed by the present applicant.

The auto-slack adjuster shown on the left side of the drawing is similar to the auto-slack adjuster according to the earlier application filed by the applicant.Next, the structure and operation of this adjuster will be explained. In this description, left and right refer to the drawings.

A hollow first piston 2 that does not rotate with respect to the cylinder 1 is fitted into one end of the cylinder 1.
A threaded cylinder 5 having a multiple thread 3 and a single thread 4 formed on its inner surface is fitted into the first piston. Since the multi-thread screw 3 has a large helical angle, moving the adjusting piece 6 screwed thereon relatively in the axial direction rotates the threaded cylinder 5 (reversible engagement), and the single-thread screw 4 has a small helical angle. Therefore, even if the rod 7 fitted thereto is pushed in the axial direction, the threaded cylinder 5 is not rotated (irreversible engagement) and is driven only in the axial direction. Rod 7
does not rotate because it protrudes to the left of the threaded cylinder 5 and engages the web 8 of the brake shoe with the forked portion 7a at the outer end. The inner end 2a of the first piston 2 has a through hole 2b
The auxiliary piston 9 is fitted into this through hole 2b in an oil-tight manner, and the small diameter portion 9 at the right end of the auxiliary piston 9 is inserted into the through hole 2b.
A stopper 10 is locked to a. stoppa 10
and a stepped portion 9c formed by the large diameter portion 9b of the auxiliary piston.
The spring seat 11 is fitted between the small diameter portion 9a so as to be movable in the direction of the center line of the small diameter portion 9a. A set spring 12 is compressed and inserted between the spring seat 11 and the inner end 2a of the first piston 2. At the left end of the auxiliary piston 9, a conical protrusion 13 is formed which is attached to and detached from the conical recess 6a formed in the adjustment piece 6 to act as a clutch. Spring seat 14 and screw tube 5 that come into contact with adjustment piece 6 at central protrusion 14a
An adjustment spring 15 is compressed and inserted between the two.

The base portion of the conical protrusion 13 of the auxiliary piston 9 is formed into a square shape, and is fitted into a square hole bored in the center of a plate 16 that is fixed to the first piston 2 and does not rotate, so that the auxiliary piston 9 rotates. It is recommended not to do so.

The autoslack adjuster of the previous invention constructed in this way operates as follows.

(a) When lining wear is small.

At this time, the center portion of the spring seat 11 that fits into the small diameter portion 9a of the auxiliary piston 9 is separated from the stopper 10.

When pressure oil is supplied to the cylinder 1, the first piston 2 moves to the left and the auxiliary piston 9 is pushed to the left to move the conical protrusion 13 at the left end into the conical recess 6 of the adjustment piece 6.
a, the clutch is in a connected state, and the adjustment piece 6 is made non-rotatable. In this state, the first piston 2 moves to the left and pushes the threaded cylinder 5, causing the rod 7 to move to the left via the single thread screw 4 and extruding the web 8 toward the drum. Since the second piston 17 is fitted to the right end of the cylinder 1, the second piston 17 also moves to the right at the same time as the first piston 2 moves to the left, and the right side is moved through the female screw tube 18 and the rod 19. Push the web 8a to apply the brake.

When the hydraulic pressure pushing on both pistons 2, 17 is removed, both pistons 2, 17 return to their positions due to return springs (not shown) that pull the brake shoe away from the drum.
During this movement, the spring seat 11 moves in the area between the stop 10 and the step 9c of the auxiliary piston 9.

(b) When the shoe clearance increases Pressure oil is supplied to the cylinder 1 and the first piston 2
When the second piston 17 is expanded, the auxiliary piston 9 also moves to the left together with the first piston 2 due to the hydraulic pressure.
At this point, it is supported by the set spring 12 and cannot move to the left, and only the first piston 2 and the screw cylinder 5 move to the left. As a result, the conical projection 13 of the auxiliary piston separates from the conical recess 6a of the adjustment piece 6, and the clutch becomes disengaged. As mentioned above, the screw tube 5 moves to the left, but the adjustment piece 6 is pushed by the adjustment spring 15 and the spring seat 14 and is prevented from moving to the left, so the screw tube 5 moves toward the center line of the adjustment piece 6. The adjusting piece 6 rotates due to the multi-thread screw 3.

When the brake is released and the pressure oil pushing both pistons 2 and 17 is removed, the rod 7 and the screw tube 5 move to the right by a return spring (not shown), and the adjustment spring 15,
Pushed by the spring seat 14, the adjusting piece 6a moves to the right, and the conical protrusion 13 comes into contact with the conical recess 6a of the adjusting piece 6, so that the clutch is in a connected state. As a result, the adjustment piece 6 becomes unrotatable, so the screw tube 5 moving to the right rotates, and the rod 7 is slightly tightened through the single thread screw 4.
protrude from Therefore, during the next braking, the stopper 10 will stop at a position where it does not hit the stepped portion 9c of the auxiliary piston 9. In other words, it will operate in the state of (a) with less wear.

In this way, the auto slack adjuster adjusts the gap every time the brake lining wears down a little, but when installing the brake during car assembly or when replacing the brake shoe and reassembling the brake, In order to avoid damaging the lining and make the work easier, the shoe gap is widened during assembly, so by the time the shoe gap is adjusted to the normal size after assembly,
You will have to depress the brake pedal many times, resulting in poor work efficiency.

For this purpose, the brake device described in the above-mentioned Japanese Patent Publication No. 60-25659 has a manual gap adjustment mechanism attached to an auto-slack adjuster that automatically adjusts the gap, so that the gap can be shortened manually during assembly. I'm trying to get it done quickly.

(Problems to be solved by the invention) However, the brake device described in the above publication,
During manual adjustment, the boots that prevent dust and water from entering the cylinder are twisted, which can easily damage the boots.If the boots are loosely fitted to avoid damaging the boots, the waterproof and dustproof effects will be incomplete. There is a weakness in becoming.

(Means for Solving the Problems) In the present invention, a first piston 2 incorporating an auto-slack adjuster is fitted into one end of a cylinder 1 which is open at both ends, and a second piston 2 is fitted into the other end of the cylinder. The piston 17 is fitted, and the female threaded cylinder 18 is rotatably fitted into the cylindrical recess 17a formed in the center of the second piston 17, and the female threaded cylinder 18 has teeth 20a connected to its outer periphery. A driving part 20 is integrally provided outside the cylinder, and is engaged with the web of the brake shoe at the forked part 19a at the outer end, and has a male thread 1.
9b is screwed into the female threaded cylinder 18, and this male thread 19b is irreversibly engaged so that the female threaded cylinder 18 is not rotated by pressing the rod 19 in the center line direction. This solves the above problems.

(Function) When the drive unit 20, which has teeth 20a connected to its outer periphery, is rotated with a tool such as a screwdriver, the female threaded cylinder 18
rotates within the second piston 17 and causes a non-rotatable rod 19 to protrude from the female threaded cylinder 18 by means of a threaded web 8a. This operation allows the shoe gap to be quickly adjusted to a normal amount.

According to this brake device, the second piston 17
Since the boot 21 does not rotate, the boot 21 is not twisted, and the inside of the cylinder can be effectively protected against dust and water.

The auto-slack adjuster combined with this brake device may be of any type.

(Embodiment) In the drawings, a first piston 2 is fitted into the left portion of a cylinder 1, in which an auto-slack adjuster mechanism similar to that of the earlier application described above is incorporated.

A second piston 17 is fitted into the right portion of the cylinder 1, and a female thread 18 is rotatably fitted into a cylindrical recess 17a open to the outside of the second piston 17. This female screw tube 18 has a male screw 1.
9b is screwed together (external thread 19
b is of irreversible engagement with a small helical angle that does not rotate the female threaded cylinder 18 even if the rod 19 is pushed in the direction of its center line), and the right brake shaft is attached to the forked part 19a at the outer end. The web 8a is engaged. Therefore, the rod 19 does not rotate, and the second piston 17, like the first piston 2, is prevented from protruding outside the cylinder by the web 8a. Female screw tube 1
A driving part 20 made of a sheet metal with teeth 20a formed on the outer periphery is fixed to the end of the drive part 8. code 21
prevents dust between the cylinder 1 and the second piston 17,
These boots are waterproof.

With this structure, when a tool such as a screwdriver is engaged with the toothed portion 20a on the outer periphery of the drive portion 20 to rotate the female threaded cylinder 18, the rod 19 which is screwed together and cannot be rotated is pushed out. The shoe gap can be quickly shortened.

C. Effect of the invention Even if the gap between the drum and the brake shoe is increased during assembly to make the work easier, the shoe gap can be quickly reduced by manually operating the drive unit 20. The auto slack adjuster eliminates the need to repeatedly press the brake pedal to reduce the shoe gap.
Assembling the drum brake and reassembling when replacing the brake shoe can be performed efficiently.

[Brief explanation of drawings]

The drawing is a longitudinal cross-sectional view of the brake device of the present invention shown in combination with an example of a conventional auto slack adjuster. 1... Cylinder, 2... First piston, 2a...
Inner end, 2b... through hole, 3... multi-thread screw, 4...
...single thread screw, 5...screw tube, 6...adjustment piece, 6a...
... Conical recess, 7... Rod, 7a... Forked part,
8, 8a...Web, 9...Auxiliary piston, 9a
...Small diameter part, 9b...Large diameter part, 9c...Step part, 1
0...Stopper, 11...Spring seat, 12...Set spring, 13...Conical projection, 14...Spring seat, 1
4a... Protrusion, 15... Adjustment spring, 16... Plate, 17... Second piston, 17a... Cylindrical recess, 18... Female screw cylinder, 19... Rod, 19a
...Forked portion, 19b...Male thread, 20...Drive portion, 20a...Tooth portion, 21...Boot.

Claims (1)

[Scope of utility model registration request] A first piston 2 incorporating an auto-slack adjuster is fitted into one end of a cylinder 1 whose both ends are open, and a second piston 17 is fitted into the other end of the cylinder. A female screw tube 18 is rotatably fitted into a cylindrical recess 17a formed in the cylinder, and a drive section 20 having teeth 20a connected to the outer periphery is integrally provided on the female screw tube 18 outside the cylinder. The rod 19 is engaged with the web of the brake shoe at the forked portion 19a at the outer end and is formed with a male thread 19b, which is screwed into the female threaded cylinder 18. A brake device with irreversible engagement that prevents the female screw cylinder 18 from rotating due to pressure.