JPS6325398Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic braking gap adjustment device for a hydraulically operated brake.

The invention is particularly applicable to, but not limited to, drum brakes. As is well known, a drum brake has a pair of arcuate brake shoes on a back plate, one end of which is a fulcrum, and the other end of which is expandable by the operation of a wheel cylinder. Braking is achieved by pressing the brake lining against the circumferential surface. When the brake lining wears out due to this braking, the braking gap between the brake lining and the inner peripheral surface of the brake drum increases.
An automatic braking gap adjustment device provided separately from the wheel cylinder is operated to expand the brake shoe so that the braking gap is always constant.

The applicant previously proposed that the automatic braking gap adjustment device, which is provided separately from the wheel cylinder that expands the brake shoe, is built into the wheel cylinder, has a simple structure, can be manufactured at low cost, and has a spring retainer. By using this, we have provided an automatic braking gap adjustment device for hydraulically operated brakes that ensures the screwing out of the adjustment bolt, has a simple locking structure for the adjustment nut, and is easy to assemble. −148121).

The structure of this device is that a piston is slidably inserted into a cylinder, a hydraulic chamber is defined in the cylinder by the piston and an opposing part of the piston, and a hydraulic pressure chamber is formed between the piston and this opposing part. An adjusting nut and an adjusting bolt which are threaded together are arranged, the clutch part of the adjusting bolt is brought into contact with the clutch surface of the opposing part, and the adjusting nut is attached to a spring having a spring seat part and a plurality of leg parts. The legs of the retainer are fitted into the notches formed in the adjustment nut, and the retainer is further engaged and installed in the communication holes formed in the piston, and the spring is compressed between the spring seat and the adjustment nut. As a result, when the piston is brought into contact with the piston and a braking gap greater than a predetermined value is generated, the adjustment bolt is screwed to move the piston forward, so that the braking gap is always constant.

However, in the automatic braking gap adjustment device configured as described above, it is necessary to remove burrs caused by the threading of the female thread of the adjustment nut, and for this purpose, the area around the opening end of the screw hole on the contact surface of the adjustment nut with the piston is scraped off, and a recess is created around the opening end of the screw hole. It is formed. When the above-mentioned device is assembled and brake fluid is introduced into the hydraulic pressure chamber in the wheel cylinder, air remains in the recess due to the contact between the adjuster nut and the piston, and it is extremely difficult to remove the residual air. .

The present invention has been made to solve this problem, and includes an adjusting nut and an adjusting nut screwed together with a multi-thread screw in a hydraulic pressure chamber defined by a piston slidably inserted into a cylinder and its opposing part. A bolt is arranged in series with the piston, and the clutch surface of the adjusting bolt is brought into contact with the clutch surface of the opposing part, while the adjusting nut is held on the piston, and when a braking gap of more than a predetermined value is generated, the adjusting bolt is In an automatic braking gap adjustment device for a hydraulically operated brake that moves a piston forward by screwing a stop bolt, a spring retainer having a spring seat and a plurality of legs is provided with a notched spring retainer whose legs are formed into adjuster nuts. Insert into the notch and attach by locking the latch claw at the tip of the leg to the communication hole formed in the piston collar that connects the hydraulic pressure chamber on the piston cup side and the hydraulic pressure chamber on the adjustment bolt side. At the same time, a spring is compressed between the spring seat and the adjusting nut to bring the adjusting nut into contact with the piston. This is an automatic braking gap adjustment device for a hydraulically operated brake, characterized in that a concave portion is formed that extends in the same direction as the engagement groove of the shew web formed and communicates with the communication hole, and its purpose is to An object of the present invention is to provide an automatic braking gap adjustment device for a hydraulically operated brake that reliably prevents rotation of an adjuster nut, prevents the above-mentioned air from remaining, and always has good braking performance.

An embodiment in which the present invention is applied to a two-leading drum brake will be described below with reference to the drawings.

Back plate fixed to the vehicle body (not shown)
A pair of upper and lower wheel cylinders 1 are installed on the inner surface of the
(the lower part is not shown), and a pair of left and right brake shoes 2, 2 are respectively arranged symmetrically around the center of the back plate.

The wheel cylinder 1 is composed of a cylinder body 3 having a cylinder hole 3a with only one end open, and a single piston 5 that slides into the cylinder hole 3a to define a hydraulic chamber 4.The cylinder body 3 has a back plate. is fixed to. A retainer 6 is provided at the outer end of the cylinder body 3, and an engagement groove 5a is formed at the outer end of the piston 5, with which the corresponding ends of the brake shoes 2, 2 are engaged. ing. This retainer 6 and the engagement groove 5
Relative rotation between the cylinder body 3 and the piston 5 is prevented by the engagement between the cylinder body 3 and the brake shoes 2, 2.

The wheel cylinder 1 is provided with a hydraulic pressure introduction port 7 for introducing the output hydraulic pressure of a brake master cylinder (not shown) into the hydraulic pressure chamber 4 thereof.

In the hydraulic chamber 4 of the wheel cylinder 1, an automatic braking gap adjustment device A of the present invention is arranged in series with the piston, which will be described in detail below.

The piston 5 has a collar portion 9 at the tip of the small diameter portion 8, and this collar portion 9 defines a hydraulic pressure chamber 4 on the piston cup 11 side and a hydraulic pressure chamber 4 on the adjuster bolt 19 side, which will be described later. A piston cup 11 is fitted into a cup groove 10 formed in the small diameter portion 8. A recess 12 is formed in the collar 9 at the tip of the piston 5, and the recess has a substantially circular center and extends from the center in the same direction as the engagement groove 5a formed at the outer end of the piston 5. Each of them has an extended shape, and one of them is fan-shaped. By forming this recess 12, large and small arc-shaped communication holes 13, 13' are formed in the collar 9.
The adjusting nut 15 is disposed so that its collar 15a is in contact with the contact surface 14 of the piston 5 so as to be able to separate from it. It is held under pressure. This adjuster nut 15 has a collar portion 1.
5a has notches 18 at three locations corresponding to the large and small communicating holes 13 and 13' formed in the collar portion 9 of the piston, namely, the position corresponding to the small communicating hole 13' and the both side walls of the large communicating hole 13. 13a, formed near 13a. Also, aziasto nut 1
5, a recess 15d is formed around the open end of a screw hole 15c into which an adjusting bolt (to be described later) is screwed, for scraping off burrs generated when the screw hole is threaded. ing. On the other hand, the spring retainer 16
three legs 16 having locking claws 16b at the ends of the legs 16a;
It is composed of c.

The piston 5, adjuster nut 15, spring retainer 16 and spring 17 are assembled as follows. First, attach the collar 15 of the adjuster nut 15 to the contact surface 14 of the piston 5.
A is brought into contact with the communicating holes 13, 13' and the cutout portion 18 by aligning them. Next, attach the spring 17 to the adjuster nut 15 and spring retainer 16.
The leg portion 16c of the spring retainer 16 is inserted between the notch portion 1 of the adjuster nut 15.
8, and its locking claws 16b are locked in the communication holes 13, 13' of the piston 5. The spring 17 is connected to the collar portion 15a of the adjuster nut 15 and the spring seat portion 16 of the spring retainer 16.
It is compressed between a.

The adjuster nut 15 assembled in this way resists this spring 17 and is attached to the piston 5.
Although it can be separated from the abutting surface 14 of
It is stopped from rotating.

An adjustment bolt 19 is screwed into the shaft portion 15e of the adjustment nut 15 via a multi-start thread portion 19a so as to pass through a screw hole 15c at the center thereof. The threaded portion between the adjusting nut 15 and the adjusting bolt 19 is provided with an appropriate braking gap between each brake shoe 2, 2, that is, an appropriate gap between each brake shoe 2, 2 and a brake drum (not shown). An axial backlash is set. A clutch portion 19b is formed at the end of the adjusting bolt 19.
9b is rotatably fitted into the cylinder small diameter section 20 provided on the inner end wall of the cylinder body 3, and faces a conical clutch surface 21 formed on the back wall of the cylinder small diameter section 20. A seal member 22 is fitted into the seal groove 19c of the adjusting bolt 19 to prevent the hydraulic pressure in the hydraulic chamber 4 from acting on the clutch surface 21.

Next, the operation of this embodiment will be explained.

When brake fluid is introduced from the hydraulic pressure introduction port 7 into the hydraulic pressure chamber 4 in the wheel cylinder 1 which incorporates the automatic braking gap adjustment device A assembled as described above, as the brake fluid fills the hydraulic pressure chamber, the hydraulic pressure increases. The air in the pressure chamber is discharged from the brewer (not shown),
At this time, the air in the recess 15d formed in the above-mentioned adjusting nut 15, although the adjusting nut 15 comes into contact with the collar 9 of the piston 5, the center portion 12a of the collar 9 is in contact with the recess of the adjusting nut 15. 15d and communicates with the hydraulic pressure chamber 4 via its extension 12b, the liquid is guided to the hydraulic pressure chamber 4 through the recess 12 and discharged from the brewer. becomes. Moreover, since the extending direction of the recessed portion 12 is the same as the groove direction of the engagement groove 5a of the piston 5, when the piston is engaged with the shew web and assembled, one of the extending portions 12b will always face upward of the vehicle body. It will be located at Therefore, the air remaining in the recess 15d of the adjusting nut 15 is more easily guided to the hydraulic pressure chamber 4, and the air removal performance is significantly improved.

When braking is not performed, the return spring force is applied to the piston 5 via the brake shoe 2.
This is transmitted to the adjusting nut 15 and the adjusting bolt 19, and enters the clutch surface 21 of the clutch portion 19b, generating clutch torque. At this time, since the adjusting nut 15 and the adjusting bolt 19 are threaded together with a multi-thread thread, rotational torque is generated in the adjusting bolt 19, but the clutch torque is set to be larger than this adjusting bolt rotational torque. Therefore, the adjuster bolt 19 does not rotate and the piston 5 maintains its position.

Next, in order to perform braking, a master cylinder (not shown) is actuated to introduce pressure fluid from the hydraulic pressure introduction port 7 into the hydraulic pressure chamber 4. When the piston 5 moves forward in the axial direction, the brake shoe 2 is transferred to the wheel. The braking action is performed by pressing against the inner peripheral surface of the brake drum, which rotates together with the brake drum.

By the way, when the brake lining is not worn to a predetermined level or during braking immediately after adjusting the braking gap, as the piston 5 moves forward, the adjuster nut 15 is brought into contact with the collar portion 9 by the elastic force of the spring 17 via the spring retainer 16. It moves together with the piston 5 while maintaining its state. Since the amount of movement of the adjusting nut 15 is the amount of movement corresponding to back crushing, no rotational torque is generated in the adjusting bolt 19 which is threaded with a multi-thread screw, and the adjusting nut 15 is not adjusted. When the brake is released, the piston 5 and adjustment nut 15 return to their original positions together.

In this normal braking state, the hydraulic pressure in the hydraulic pressure chamber 4 is relatively low, and therefore the frictional coupling force between the clutch portion 19b of the adjusting bolt 19 and the clutch surface 21 of the cylinder small diameter portion 20 is relatively small. Therefore, if the piston 5 moves further outward due to wear of the brake linings of the brake shoes 2, 2, the adjustment nut 15 will be brought into contact with the contact surface 14 by the elastic force of the spring 17 via the spring retainer 16. Piston 5 while maintaining contact state.
move with

This amount of movement is equal to the amount of wear on the brake lining added to the backlash, and since the movement is greater than the backlash, the adjusting bolt 19 moves together with the adjusting nut 15, and the clutch portion 19b of the adjusting bolt 19 is connected to the cylinder. away from the clutch face 21 of the small diameter portion 20. The adjustment nut 15 is pressed against the contact surface 14 of the piston 5 by the elastic force of the spring 17, and its rotation is restricted by the legs 16c of the spring retainer 16. Rotational torque is generated at the threaded part of the multi-thread screw. This allows the adjustment bolt 19
moves toward the clutch surface 21 while twisting around the adjuster nut 15, and engages with the clutch surface 21 again. In this way, a self-adjusting action is carried out to compensate for wear on the brake linings of the brake shoes 2,2. Here, if the pressure inside the hydraulic chamber 4 is reduced to release the brake, the brake shoe 2,
2 contracts in response to the returning force of the return spring, and this returning force acts on the piston 5, the adjusting nut 15, and the clutch part 19b of the adjusting bolt 19 as a thrust toward the clutch surface 21, and as a result, the clutch part 19b It is frictionally coupled to the clutch surface 21, making it impossible for the adjustment bolt 19 to rotate. Therefore, the piston 5 and the adjusting nut 15 can only move backward by the stroke corresponding to the backlash of the threaded portion of the adjusting bolt 19, and as a result, the brake lining of each brake shoe 2 and the inside of the brake drum are An appropriate braking gap corresponding to the bump lash is created between the brake and the circumferential surface.

In addition, when strong braking is performed, the hydraulic pressure in the hydraulic chamber 4 increases to a predetermined value that causes elastic deformation in the brake shoes 2, 2, brake drum, etc., as described above. A self-adjusting action is performed. When the hydraulic pressure exceeds the predetermined value,
The thrust due to the hydraulic pressure of the clutch portion 19b of the adjusting bolt 19 increases, and the clutch portion 19b
Since the adjusting bolt 19 is held in a frictionally connected state with the clutch surface 21, the adjusting bolt 19 cannot rotate. Therefore, the unrotatable adjusting nut 15 is fastened on the adjusting bolt 19 by the legs 16c of the spring retainer 16, so that when the piston 5 moves further outward due to elastic deformation of the brake drum or the like, the spring 17 By deflecting, the adjusting nut 15 maintains its position together with the adjusting bolt 19, and the abutment surface 14 of the piston 5 is separated from the adjusting nut 15. In this way, the automatic adjustment effect is stopped.

In this embodiment, the spring is compressed between the adjuster nut and the retainer, but the separate spring can be omitted by providing the retainer itself with spring properties.

As described above, the present invention includes a spring retainer having a spring seat and a plurality of legs, the legs of which are fitted into notches formed in an adjuster nut, and inserted into communication holes formed in the collar of a piston. In addition to being locked and installed, the spring is compressed between the spring receiving seat and the adjusting nut to bring the adjusting nut into contact with the piston, so the adjusting nut and adjusting bolt can be assembled easily and reliably. Furthermore, the piston cup side hydraulic pressure chamber defined by the piston collar and the adjustment bolt side hydraulic pressure chamber are communicated between the opening end of the screw hole for the piston side adjusting bolt of the adjusting nut and the communication hole. Since a recess is formed and the recess is always located upward,
When brake fluid is introduced and filled into the hydraulic pressure chamber in the wheel cylinder, it is possible to prevent air from remaining in the recesses that inevitably occur due to the screw hole forming process of the adjuster nut, allowing for more complete and quick air release. In addition, since the adjuster nut is reliably prevented from rotating, it is possible to provide a brake that always has good braking ability while being equipped with a sophisticated and excellent braking gap automatic adjustment device. In addition, the recessed portion, together with the communication hole formed in the piston, further improves the communication between the adjusting bolt side hydraulic pressure chamber and the piston cup side hydraulic pressure chamber, and the air removal from the piston cup side hydraulic pressure chamber is also significantly improved. do. Furthermore, the structure is simple, and the piston, adjuster nut, etc. can be easily formed, and in particular, the recess formed in the piston can be formed by forging, making it extremely easy to implement. Furthermore, the concave portion formed in the piston's collar does not reduce the connection strength between the piston and the piston, so it has various effects such as no damage during manufacturing or use. It is something that you have.

[Brief explanation of drawings]

Figures 1, 2, and 3 show an embodiment of the present invention, with Figure 1 being a cross-sectional front view of the main part, Figure 2
The figure is an exploded perspective view of the components of the automatic braking gap adjustment device, and FIG. 3 is a right side view of the piston. 1 is the wheel cylinder, 2 is the brake shoe,
3 is the cylinder body, 4 is the hydraulic chamber, 5 is the piston,
9 is a collar portion, 12 is a recessed portion, 13 is a connecting hole, 15 is an adjustment nut, 16 is a spring retainer,
17 is a spring, 18 is a notch, 19 is an adjustment bolt, 19b is a clutch, 20 is a cylinder small diameter portion, and 21 is a clutch surface.

Claims (1)

[Scope of utility model registration request] An adjustment nut and an adjustment bolt screwed together with a multi-start thread are arranged in series with the piston in a hydraulic pressure chamber defined by a piston slidably inserted into the cylinder and its opposing part. The clutch surface of the bolt is brought into contact with the clutch surface of the opposing portion, while the adjusting nut is held on the piston, and when a braking gap of a predetermined value or more is generated, the adjusting bolt is screwed to move the piston forward. In an automatic braking gap adjustment device for a type brake, a spring retainer including a spring seat and a plurality of legs is fitted into a notch formed in an adjustment nut, and the legs are fitted into a notch formed in a piston collar. The latch claw at the tip of the leg is engaged with the communication hole connecting the hydraulic pressure chamber on the piston cup side and the hydraulic pressure chamber on the adjusting bolt side, and the latch is attached to the connecting hole between the spring seat and the adjusting nut. A spring is compressed to bring the adjustment nut into contact with the piston, and the spring is extended from the center of the contact surface of the piston toward the circumferential edge of the collar and in the same direction as the engagement groove of the shew web formed at the other end of the piston. 1. A braking gap automatic adjustment device for a hydraulically operated brake, characterized in that a recessed portion is formed to communicate with the communication hole.