JPS62278327A - Wheel cylinder for leading brake - Google Patents

Abstract

PURPOSE:To prevent adjustment of shoe clearance, which follows the deformation of a brake drum, from becoming excessive, by providing an adjusting gear screwed in a piston put in a cylinder chamber and a sub-gear in a space connected to said cylinder chamber, said sub-gear meshing with said adjusting gear. CONSTITUTION:When a shoe clearance increases due to the wear of a brake shoe, a piston 2 moves to recover determined shoe clearance. After that, an adjusting gear 3 rotates to make said piston 2 move on a male screw 3a' because a sub-gear 10 is not rotatable due to a clutch spring 12, the movement causing the brake shoe to rub the drum to generate braking force. While, when said piston 2 moves forewards following the deformation of the drum in braking, the shaft 3a of said adjusting gear 3 can not rotate because the axial force to said shaft 3a is large, and so both gears 3 and 10 move forewards together, said sub-gear 10 compressing a cone spring 11. Due to the above construction, the adjustment of shoe clearance is prevented from becoming excessive.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a wheel cylinder for a two-leading brake that has an auto-adjuster device built into the cylinder.

(Prior art) Conventional examples of two leading brake wheel cylinders with an auto-adjuster device 8 built into the cylinder are shown in the second and third examples.
This will be explained based on the diagram.

20 is a wheel cylinder for two leading brakes, and 21 is a cylinder body. In FIG. 2, the wheel cylinder 20') will be explained in detail.

A piston 22 is fitted inside the cylinder body 21 and has a large diameter hole 22c formed through a small diameter hole 22a and a stepped portion 22b. 23 is a! It's an i4 M nut. Reference numeral 24 designates a coil spring, one end of which is fixed to the tip of the piston 22, and the other part of which is inserted through a hole or bamboo provided at the periphery of the adjustment nut 23 and bored into the stepped portion 22b of the piston. hole 22
b, and presses the adjustment nut 23 against the stepped portion 22h and suppresses its rotation. 25 is an adjustment rod, one end of which is connected to the adjustment nut 23 with a multi-threaded portion 25m.
The other end has a clutch surface 2 consisting of a truncated conical surface.
A clutch body 25b having a diameter of 5b8 is provided.

When hydraulic oil is introduced into the cylinder body 21 from the outside, the hydraulic oil is supplied into the large diameter hole 22c from the outer circumference of the small diameter hole 22a of the piston.

The two-leading brake wheel cylinder 20 as described above is connected to a backing plate 30 as shown in FIG.
The brake shoes 4 and 4' are disposed in the same direction between the two brake shoes 4 and 4' which are disposed facing each other on the top, thereby forming a two-leading brake. Note that 31° and 32 are shoe return springs.

Next, the effect will be explained.

Brake shoe 4. In the picture where the shoe gap has exceeded the set shoe gap due to wear, if hydraulic oil is poured into the cylinder body 21 from the outside, the piston 22 will be pushed to the right according to the force 5 in Fig. 2, and the adjustment will be made. The nut 23 is a coil spring 24
The clutch surface 25b separates from the wall surface of the cylinder body 21 while being pressed by the stepped portion 22b. Then, the hydraulic oil acting on the back surface of the clutch body 25b of the adjustment rod presses it against the wall surface of the cylinder body 21, and the adjustment rod 25 is guided by the multi-thread screw of the adjustment nut 23, which is prevented from rotating. or turn the screw to adjust the shoe gap.

(Problems that the invention attempts to address with the I pressing method) Therefore, the amount of shoe gap adjustment is determined by the pitch of the multi-threaded thread portion 25a, and since it is a one-shot type in which adjustment is completed in - times of operation, the final amount is determined by the drum. sensitive to thermal expansion pressure. Furthermore, the structure of the piston 22 was complicated.

(Means for Solving the Problems) The present invention provides a wheel cylinder for a two-leading brake that has an auto-adjuster device inside the cylinder and does not over-adjust the shoe gap even if the drum crab deforms. The structure is as follows.

The cylinder body is provided with a cavity that communicates with the cylinder chamber, a bottomed cylindrical piston is housed in the cylinder chamber, an engaging part for locking the web of the brake shoe is provided at the tip of the piston, and a female thread is installed in the cylinder. A male screw is screwed into the shaft at the other end of the adjusting gear, and a male screw is screwed into the female screw of the piston, and the shaft at the one end of the adjusting gear is slidably supported on the cylinder cover. A sub-gear that is keyed with the adjusting gear using a multi-thread screw is placed in the empty chamber that communicates with the chamber, allowing rotation of the sub-gear in only one direction between the other end of the sub-gear and the inner wall of the cylinder body. This is a two-leading brake wheel cylinder in which a clutch spring and a spring having a predetermined resiliency are arranged, and one end of which is supported by a cylinder cover.

(Function) During the time when hydraulic oil is applied to the cylinder chamber from the outside,
If the brake shoes are worn and the shoe gap is larger than the set shoe gap [8] given by the backlash between the adjusting gear and the sub gear, the piston will move and fill the set shoe gap of 8 (well, the sub gear The clutch spring placed between one end of the clutch spring and the inner wall of the cylinder body is given a rotational force in the direction of tightening, so it cannot rotate, and the adjusting gear rotates.
The piston is slightly threaded onto the male thread of the adjusting gear shaft and slides into contact with a brake shoe or a drum (not shown) to generate braking force. When the piston moves backward due to brake release, the sub gear is rotated in the direction that loosens the clutch spring, and the adjusting gear is returned to its original position, and the shoe gap is adjusted by the amount that the piston is sent out by the rotation of the adjusting gear during braking. Ru.

Also, when the piston moves forward in response to the deformation of the drum during braking, the axial force applied to the shaft of the adjusting gear increases, so no rotation occurs, and the sub gear compresses the cone spring with a predetermined repulsive force. The adjusting gear and the sub-gear move forward together to prevent over-adjustment of the shoe gap.

(Example) An example of a wheel cylinder for a two-leading brake according to the present invention will be described based on FIG. 1.

1 is the cylinder body, and la is the cylinder clasp. Reference numeral 2 denotes a cylindrical piston with a bottom, and a female screw 2 a provided inside the cylinder is screwed into a male screw 3 a provided on a gear shaft 31 of the adjusting gear 3 . The tip of the piston 2 is formed with an engaging portion 2b') of a groove or hole. 4 is one brake shoe. One brake shoe 4 and the piston 2 are engaged with the tip of a web 4a of the brake shoe, and are coupled to an engaging portion 2b of the piston with a coupling member 5 so as to be relatively rotatable. 6 is a manual piston rotation lever, 7 is a stopper for preventing blind movement of the lever 9-6, and 8 is a dust cover between the cylinder body 1 and the piston 2. Thus, the piston 2 is restrained from rotating due to engagement between the rotary lever 6 and the stopper 8.

10 is a vacant space A that communicates with the cylinder chamber of the cylinder body 1.
This is a sub-gear that accommodates internal pressure and is screwed together with the adjusting gear 3 using a multi-thread screw. The sub-gear lO is rotatably and axially movably supported by a shaft 10m on one end side in a through hole 1a provided in the cylinder cover 1a, and the other end side is supported by a hollow chamber A (interposed between it and the 04 surface). A cone spring 11 having a predetermined elastic force is biased toward the cylinder clasp-1a.The cone spring 12 is housed in an adult provided on the side wall of the vacant room, and one end is attached to the cylinder body. The clutch spring is inserted and locked into a hole provided in the clutch spring 1, and its other end is wound around the shaft 10b on the other end side of the sub-gear 10.Therefore, the sub-gear 10 cannot rotate in the direction that tightens the clutch spring 12. Yes, it can be rotated only in the loosening direction.

13 is a plug.

The set shoe gap is given by the backlash of the dark multi-thread screw between the adjusting gear 3 and the sub-gear 10.

Note that the cylinder cover 1a is provided with an engaging portion to which a web of the other brake shoe (not shown) is engaged.

Next, the effect will be explained.

If the shoe clearance force S1 is within the set shoe clearance given by the backlash of the multi-thread screw between the adjusting gear 3 and the sub gear 10, when hydraulic oil is introduced into the cylinder body l during service braking, The brake shoe 4 is pushed out by the piston 2 and comes into sliding contact with a drum (not shown) to generate braking force.

If the brake shoes are worn and the shoe gap is larger than the set shoe gap, the piston 2 or set shoe gap 1
After filling #, sub gear 10 is clutch spring 1
Since it cannot rotate due to the action of 2, the adjusting gear 3 rotates, and the piston 2 (well, the top of the male thread 3a' of the shaft of the adjusting gear is slightly screwed out, and the brake shoe slides into contact with a drum (not shown). and generates braking force.

When the piston 2 moves back due to the action of a shoe return spring (not shown) when the brake is released, the adjusting gear 3 also moves back together, or at that time, the sub gear 10 is rotated in a direction that loosens the clutch spring 12. Adjusting gear 3 does not rotate in reverse,
This means that the clearance between the pistons 2 and 12 is adjusted by the amount that the piston 2 is released from the shaft of the adjusting gear when it moves forward. This value is the multi-thread thread of the adjusting gear and the male thread 3m'
This is a very slight difference in pitch based on the difference in pitch between the two.

Further, when the piston 2 moves forward in response to the deformation of the drum during braking, the axial force applied to the shaft 3a of the adjusting gear increases, so that no rotation occurs and the sub gear 1
0 compresses the cone spring 11, and the adjusting gear 3 and sub-gear 10 move forward together to prevent over-adjustment of the shoe gap.

A two-leading brake wheel cylinder having the above-mentioned configuration and operation is mounted on a backing plate 30 on both brake shoes 4, 4' as in the conventional example shown in FIG.
placed in the same direction between the two leading brakes.

(Effects of the Invention) As understood from the above explanation, the two-leading brake wheel cylinder according to the present invention has an auto-adjuster device for the shoe gap that can prevent over-adjustment of the shoe gap due to the diamond shape of the drum. The structure is simply built into the wheel cylinder, eliminating the possibility of functional problems caused by rust or dust.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a rush example of a wheel cylinder for a two-leading brake according to the present invention, and FIG. 2 is a cross-sectional view of a conventional example of a wheel cylinder for a two-leading brake.
FIG. 3 is a diagram of a two-lead/g brake in which conventional two-lead brake wheel cylinders are arranged. 1 Niji cylinder body, 1a Niji cylinder cover, 11: Through hole, 2: Piston, 2a: Female thread, 2b: Engagement part, 3 Near gear steering gear, 3a: Gear shaft, 3a: Male thread, 4
D: one brake shoe, 41: web, 5: coupling member, lO: sub gear, 10a: shaft (on one end side), 11:
Cone spring, 12: Clutch spring, 9th chamber communicating with A Niji cylinder chamber Agent Patent attorney front 1) Toshiyuki Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] The cylinder body is provided with an empty chamber communicating with the cylinder chamber, a bottomed cylindrical piston is housed in the cylinder chamber, an engaging part for locking the web of the brake shoe is provided at the tip of the piston, and a female thread is installed in the cylinder. A male thread is screwed into the shaft at the other end of the adjusting gear, and a male thread is screwed into the female thread of the piston, and the shaft at the one end of the adjusting gear is slidably supported on the cylinder cover. A sub-gear that is connected to the azimuth steering gear using a multi-thread screw is arranged in a vacant chamber that communicates with the chamber, and rotation of the sub-gear in only one direction is allowed between the other end of the sub-gear and the inner wall of the cylinder body. A wheel cylinder for a two-leading brake, characterized in that a clutch spring and a spring having a predetermined elastic force are arranged, and a shaft on one end side is supported by a cylinder cover.