JPS6221794Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is based on the braking interval in hydraulically operated brakes.
This invention relates to an automatic adjustment device.

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 distance between the brake lining and the inner peripheral surface of the brake drum increases.
An automatic braking time adjustment device provided separately from the wheel cylinder is operated to expand the brake shoe so that the braking time is always constant. Therefore, the applicant has previously built an automatic braking adjustment device into the wheel cylinder, which is provided separately from the wheel cylinder that expands the brake shoe, so that its structure is simple and can be manufactured at low cost. An automatic braking interval adjustment device for hydraulically operated brakes is provided.

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 prevented from rotating around the piston. This is between the brake and the multi-thread threaded part with the adjustment bolt.
The distance 〓 is set to be equal to 〓, and even if the adjuster nut moves together with the piston during normal braking, the amount of movement is within the range that fills this period 〓. However, when the braking distance exceeds a predetermined value due to wear of the brake lining, the amount of movement of the adjustment nut increases and the distance disappears, producing rotational torque at the threaded portion of the multi-thread screw, which causes the adjustment bolt to thread. It operates by moving the piston forward so that the braking time is always constant.

The purpose of the present invention is to adjust the distance equal to the braking distance that allows movement of the piston by adjusting the multi-thread screw between the adjustment nut and the adjustment bolt in the automatic braking distance adjustment device built into a vehicle brake cylinder. By eliminating the need to set the adjustment bolt at the joint, the adjustment nut and adjustment bolt are tightly engaged with the multi-thread screw, and the braking distance is reduced due to the adjustment bolt falling down.
To provide an automatic braking time adjustment device for a hydraulically operated brake, which prevents instability or malfunction, and allows easy and reliable setting of a braking time equal to the braking time.

In accordance with the above object, the present invention arranges an adjustment nut and an adjustment bolt 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, The clutch portion of the adjustment bolt is brought into contact with the clutch surface of the opposing portion, while the adjustment nut is prevented from rotating on the piston, and the braking period is set to a predetermined value or more.
When this occurs, a rotational torque is generated in the threaded part of the multi-thread screw, which screws the adjuster bolt and moves the piston forward. A spring retainer that is fitted into a notch formed in the flange of the piston and locked in a hole formed in the flange of the piston, and a leg that is inserted into a hole formed in the flange of the adjusting nut. A spring is compressed between the collar of the adjuster nut and a spring retainer, which is placed in contact with the contact surface of the piston and with a gap equal to the braking gap, so that the braking gap is equal to or greater than a predetermined value. When this happens, a rolling torque is generated in the threaded portion of the multi-threaded screw, causing the adjustment bolt to screw.

Hereinafter, an embodiment in which the present invention is applied to a two-leading type drum brake will be described in detail with reference to the drawings.

First, an embodiment shown in FIGS. 1 and 2 will be described. On the inner surface of a back plate (not shown) fixed to the vehicle body, there are a pair of upper and lower wheel cylinders 1 (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 piston 5 that slides into the cylinder hole 3a to define a hydraulic chamber 4.The cylinder body 3 is attached to a back plate. Fixed. 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. When these engage with the brake shoes 2, the cylinder body 3 and the piston 5 are Relative rotation with is prevented.

The wheel cylinder 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, and is further provided with a hydraulic pressure output port 8 so as to supply it to the lower wheel cylinder. It's summery.

The hydraulic chamber 4 of the wheel cylinder 1 is provided with an automatic brake adjustment device A of the present invention, which will be described in detail below.

The piston 5 has a collar portion 10 at the tip of the small diameter portion 9.
A piston cup 12 is fitted into a cup groove 11 formed in the small diameter portion 9.
Three circular counterbore holes 13 are formed at the tip of the piston 5, and by forming these holes 13, a crescent-shaped communication hole 14 is formed in the collar 10, and the inside of the hydraulic chamber 4 is formed. It is designed to supply pressurized fluid to the The adjuster nut 15 has a collar portion 1.
5a is placed in contact with the contact surface 5b of the piston 5 so as to be able to separate from the contact surface 5b. A notch 16 is formed in the collar 15a of the adjusting nut 15 at a position corresponding to the communication hole 14 formed in the collar 10 of the piston. Then, the spring retainer 17 attaches its leg portion 17a to the adjuster nut 15.
The locking claw 17b at the tip is inserted into the notch 16 of the
is attached to the communication hole 14 of the piston 5,
As a result, the adjustment nut 15 can move in the piston axial direction and separate from the contact surface 5b, but is prevented from rotating by the piston 5. The spring 18 is
The spring retainer 17 is compressed between the spring seat part 17c and the spring seat part 19b of the spring retainer 19, the leg part 19a of which is inserted into a hole 20 formed in the collar part 15a of the adjuster nut 15. This spring retainer 19 has legs 19a whose tips are connected to the contact surface 5 of the piston 5.
a, and between the spring seat portion 19b and the collar portion 15a of the adjuster nut 15, there is a proper braking distance between each brake shoe 2, 2, that is, a brake (not shown) between each brake shoe 2, 2 and a brake (not shown). A time interval 〓C corresponding to an appropriate interval 〓 between drums is set.

These piston 5, adjuster nut 15, spring retainers 17, 19 and spring 1
8 is assembled as follows. First, attach the collar 1 of the adjuster nut 15 to the collar 9 of the piston 5.
5a is brought into contact with the communicating hole 13 and the notch 18 so that they are aligned. Next, spring retainer 19
The leg 19a of the adjusting nut 15 is inserted into the hole 20 of the adjuster nut 15.
The spring 18 is interposed between the spring retainer 19 and the spring retainer 17, and the leg portion 1 of the spring retainer 17 is inserted into the spring retainer 19 and assembled.
7a is inserted into the notch 16 of the adjuster nut 15, and its locking pawl 17b is locked into the communication hole 14 of the piston 5. As a result, the spring 18
Spring seat portion 19 of spring retainer 19
b and the spring seat portion 17c of the spring retainer 17.
A distance C is set between the flange portion 15a of the adjusting nut 15 and the flange portion 15a of the adjusting nut 15.

The adjuster nut 15 assembled in this manner engages with the leg portion 17a of the spring retainer 17 and is prevented from rotating.
can be separated from the contact surface 5b of.

An adjustment bolt 21 is screwed into the shaft portion of the adjustment nut 15 via a multi-start thread portion 21a so as to pass through the center thereof. A clutch portion 21b is formed at the end of the adjusting bolt 21, and this clutch portion 21b is rotatably fitted into a cylinder small diameter portion 22 provided on the inner end wall of the cylinder body 3, It faces a conical clutch surface 23 formed on the back wall of the portion 22. A seal member 24 is fitted to the adjuster bolt 21 to prevent the hydraulic pressure in the hydraulic chamber 4 from acting on the clutch surface 23.

Next, the operation of this embodiment will be explained.

When braking is not performed, the return spring force acts in the direction of retracting the piston 5 via the brake shoe 2, which causes the adjustment nut 15,
It is transmitted to the adjuster bolt 21, and the clutch part 21
b and the clutch surface 23, and clutch torque is generated. At this time, since the adjustment nut 15 and adjustment bolt 21 are threaded together with a multi-thread screw,
Rotational torque is generated in the adjusting bolt 21, but since the clutch torque is set to be larger than the adjusting bolt rotating torque, the adjusting bolt 21 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 into the hydraulic chamber 4 from the hydraulic pressure introduction port 7, and the piston 5 moves forward in the axial direction to integrate the brake shoe 2 with the wheel. Braking action is performed by pressing against the inner peripheral surface of the rotating brake drum.

By the way, when the brake lining is not worn to a certain level or during braking immediately after adjusting the braking interval, the spring retainer 17, spring 18, and spring retainer 19 move together as the piston 5 moves forward, but the adjuster nut 1
5 is held at that position without moving, and the abutment surface 5b of the piston 5 is separated from the adjuster nut 5. In other words, since the amount of movement of the piston 5 at this time is only the distance C, the adjustment nut 15
No axial force acts on. Therefore, no rotational torque is generated in the adjusting bolt 21 due to the threaded engagement, and the adjusting bolt 21 is not adjusted. When the brake is released, the piston 5, spring retainer 17, spring 18, and spring retainer 19 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 21b of the adjusting bolt 21 and the clutch surface 23 of the cylinder small diameter portion 22 is relatively low. Since the adjustment nut 15 is small, 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 close to the spring retainer 1.
It moves together with the piston 5 by the elastic force of the spring 18 via the piston 9.

This amount of movement is equal to the distance C plus the wear of the brake lining, and since it moves more than the distance C, the adjustment bolt 21 is the same as the adjustment nut 1.
Adjustment bolt 21 moves in unison with 5.
The clutch portion 21b is separated from the clutch surface 23 of the cylinder small diameter portion 22. When the clutch portion 21b of the adjusting bolt 21 separates from the clutch surface 23, the adjusting nut 15 is urged toward the piston 5 via the spring retainer 19 by the elastic force of the spring 18, and the leg portion of the spring retainer 17 Since the rotation is restricted by the adjustment bolt 17a, rotational torque is generated at the multi-start screw threaded portion of the adjustment nut 15 and adjustment bolt 21. As a result, the adjuster bolt 21 screws around the adjuster nut 15 and the clutch surface 2
3 and re-engages the clutch surface 23. In this way, an automatic adjustment effect is carried out to compensate for wear of the brake linings of the brake shoes 2,2. If the pressure inside the hydraulic chamber 4 is reduced to release the brake, the brake shoes 2, 2 will contract in response to the return force of the return split, but this return force will be applied to the piston 5, the adjuster nut 15, and the adjuster. A thrust acts on the clutch portion 21b of the bolt 21 in the direction of the clutch surface 23, whereby the clutch portion 21b is frictionally coupled to the clutch surface 23, making it impossible for the adjusting bolt 21 to rotate.
Therefore, the piston 5 and the adjusting nut 1
5 can only retreat by a stroke of distance 〓C, and as a result, there is an appropriate distance between the brake lining of each brake shoe 2, 2 and the inner peripheral surface of the brake drum corresponding to the distance 〓C. A braking gap is created.

In addition, when strong braking is performed, the hydraulic pressure in the hydraulic chamber 4 rises 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 21b of the adjusting bolt 21 increases, and the clutch portion 21b
Since the adjusting bolt 21 is held in a frictionally connected state with the clutch surface 23, the adjusting bolt 21 becomes unable to rotate. Therefore, the non-rotatable adjuster nut 15 is held on the adjuster bolt 21 by the legs 17a of the spring retainer 17, so that when the piston 5 moves further outward due to elastic deformation of the brake drum, etc., the spring 18 Further flexing occurs, the adjuster nut 15 and spring retainer 19 are held in their positions, and the piston 5 is separated from the adjuster nut 15 by a distance of more than C. In this way, the automatic adjustment effect is stopped.

Next, the embodiment shown in FIGS. 3 and 4 will be explained. This embodiment has a spring retainer 1
Spring seat portion 19b and leg portion 19 that constitute 9
are formed separately, and the leg portion 19a is press-fitted into the hole 19c of the spring seat portion 19b.

As described above, according to the present invention, the braking distance automatic adjusting device built in the hydraulic pressure chamber of the wheel cylinder adjusts the braking distance corresponding to the braking distance between the brake shoe and the brake drum by adjusting the adjustment nut and the adjusting nut. Since it is provided between the spring retainer that receives the spring that applies rotational torque to the adjusting bolt through the spring retainer, there is no need to set the above-mentioned distance at the multi-thread threaded joint between the adjusting nut and the adjusting bolt, and the two are tightly connected. When screwed together, there is no risk that the adjusting bolt will fall down and become stuck, which will hinder proper operation, and when a predetermined axial force is applied between the two, the adjusting bolt will properly rotate and adjust. Further, since the distance is set between the adjuster nut and the spring retainer, the setting is easy and reliable, and the adjustment of the braking distance can be further improved.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the present invention, with Figure 1 being a sectional front view of the main parts, Figure 2 being an exploded perspective view of the components of the automatic braking adjustment device, and Figure 3 being an exploded perspective view of the components of the automatic braking adjustment device. Figures 3 and 4 show other embodiments of the present invention. Figure 3 is a cross-sectional front view of the main parts, and Figure 4 is an exploded perspective view of the adjustment nut, spring retainer, and spring of the automatic braking adjustment device. be. 1 is the wheel cylinder, 2 is the brake shoe,
3 is the cylinder body, 4 is the hydraulic chamber, 5 is the piston,
15 is an adjustment nut, 17 and 19 are spring retainers, 18 is a spring, and 21 is an adjustment bolt.

Claims (1)

[Scope of utility model registration request] An adjustment nut and an adjustment bolt screwed together with a multi-thread screw are arranged in a hydraulic chamber defined by a piston slidably inserted into the cylinder and its opposing part, and the clutch part of the adjustment bolt is When the adjusting nut is brought into contact with the clutch surface of the opposing part and the piston is prevented from rotating, and a braking interval of more than a predetermined value occurs, rotational torque is generated in the threaded part of the multi-thread screw, thereby causing the adjusting nut to stop rotating on the piston. During braking in a hydraulically operated brake that moves a piston forward by screwing a bolt, in an automatic adjustment device, the legs are inserted into the notches formed in the collar of the adjuster nut, and the legs are inserted into the notches formed in the collar of the piston. The spring retainer that is fitted into the hole and the leg that is inserted through the hole formed in the collar of the adjusting nut are brought into contact with the contact surface of the piston to create a gap between the collar of the adjusting nut and the brake.
A spring is compressed between a spring retainer arranged with a gap equal to , and when a braking gap of a predetermined value or more occurs, a rotational torque is generated in the multi-thread threaded part, An automatic braking interval adjustment device for a hydraulically actuated brake, characterized by a screw adjustment bolt.