JPS6240190Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic shoe gap adjustment device built into a wheel cylinder that does not increase the rigidity of a drum in a drum brake.

In drum brakes, an automatic shoe gap adjustment device is adopted to maintain an appropriate gap between the drum and the brake shoe (hereinafter referred to as the shoe gap), and to prevent the formation of rust and the influence of rainwater, the wheel A cylinder built-in automatic shoe gap adjustment device is known.

The automatic shoe clearance adjustment device adjusts the shoe clearance in order to prevent excessive pedal stroke and deterioration of braking performance due to wear of the lining fixed to the brake shoe. The phenomenon in which the drum deforms due to the brake torque and fills the shoe gap, that is, the rigidity of the drum is reduced, is a type of overadjustment and causes brake drag.

The object of the present invention is to provide a new automatic shoe gap adjustment device that is built into a wheel cylinder and prevents the above-mentioned over-adjustment.

The present invention will be specifically described with reference to illustrated embodiments.

1 and 2 show a first embodiment of the present invention.

Reference numeral 1 denotes a wheel cylinder body, into which a piston 2 is fitted so that it can move freely forward and backward, with the maximum retraction amount being restricted by its flange 2a, and a threaded groove is screwed into the inner circumferential surface of the piston 2. A carved adjusting nut 3 is rotatably fitted with a bearing 4 interposed between the inner end surfaces. Reference numeral 5 denotes an adjuster gear fixed to the front end surface of the adjuster staying nut 3, and one-way teeth 5a are formed on the outer peripheral edge of the adjuster gear. Reference numeral 6 denotes a stopper, which, as shown in FIG. 2, has an angular shape and is rotatably supported by a pin 6a fixed to the wheel cylinder body 1 at the middle, and has one end in contact with the cylinder body 1. The other end is biased by a tension coil spring 6b whose one end is hooked to the cylinder body 1, and its tip is locked to the one-way tooth 5a to adjust the feed of the adjuster gear 5 in one direction, that is, the shoe gap. Only feed in the direction is allowed. Further, an adjusting screw 7 is screwed onto the tip end side of the adjusting nut 3 with a single thread. A brake shoe (not shown) is supported on the forked tip portion 7a. Reference numeral 8 denotes a screw member that is screwed onto the rear end side of the adjusting nut 3 with a multi-thread screw. Generally, the multi-thread thread of the screw member 8 and the single thread thread of the adjusting screw 7 are formed with opposite threads, and if the screw member 8 is fixed and the adjusting nut 3 is rotated, the adjusting screw 7 is configured to move back and forth. The screw member 8 is interposed with an oil seal to maintain oil tightness, and the piston 2
The annular seat 8a that penetrates the bottom of the screw member 8 and is provided at the tail of the screw member 8 and the small diameter stepped surface 1a of the wheel cylinder 1.
A positioning member 9 having a shape in which a large-diameter ring and a small-diameter ring are connected by a short tube is connected to the small-diameter stepped surface 1 at its outer edge.
a, the outer edge is fixed to the wheel cylinder body 1, and a first coil spring 11 is compressed and interposed between a fixed spring seat 10 and a fixed spring seat 10 that is ring-mounted on the screw member 8, The positioning member 9 is urged toward the small diameter stepped surface 1a. The positioning member 9 and the first coil spring 11 are connected to the screw member 8 until the brake shoe moves as the drum (not shown) deforms during braking, that is, until the pressure oil introduced into the wheel cylinder 1 reaches the set pressure. It constitutes a means of restricting movement. A second coil spring 13 having a smaller spring load than the first coil spring 11 is provided via a bearing 12 between the annular seat 8a of the screw member that contacts the back surface of the positioning member 9 and the inner bottom 1b of the wheel cylinder body 1. It is compressed and inserted.

Next, the effect will be explained. When pressure oil is introduced into the wheel cylinder body 1, the piston 2 strokes and the adjusting nut 3 also strokes at the same time. At this time, since the screw member 8 is in contact with the positioning member 9 pressed by the first coil spring 11 at its annular seat 8a, the rotational resistance exceeds the rotational resistance of the adjusting nut 3. The nut 3 rotates and the adjusting screw 7 is screwed out, so that a brake shoe (not shown) held by the forked portion 7a of the adjusting screw comes into sliding contact with the drum. When the brake shoe is in sliding contact with the drum, the hydraulic pressure is further increased, and the set pressure becomes a step ring that exerts braking force. When the drum deforms slightly due to its rigidity and the piston 2 strokes, As the axial force of the adjusting screw 7 increases, the rotational resistance of the adjusting nut 3 increases as well.
The multi-thread screw cannot be rotated by the rotational torque, and the piston 2, adjusting nut 3, adjusting screw 7, and screw member 8 work together to compress the first coil spring 11 and generate sufficient braking force. When the brake is released, the piston 2 is
is returned until it abuts against the wheel cylinder body 1 at its flange 2a. During this time, the screw member 8 supported by the second coil spring 13 is
The positioning member 9 receives a stronger pressing force from the first coil spring 11 and comes into contact with the small diameter step surface 1a of the wheel cylinder body, and the adjusting nut 3 is rotated back to its original position with the multi-thread screw.
The Asian steering screw 7 is also returned to its original position. In this way, without increasing the rigidity of the drum,
Further, the stopper 6 returns to the original state in which it is locked to the one-way tooth 5a of the adjuster gear 5 without adjusting the shoe gap.

Next, if the lining of the brake shoe is worn and the shoe clearance exceeds the appropriate range, when pressure oil is introduced into the wheel cylinder body 1 and the piston 2 is stroked, the screw member 8 and the multi-thread screw The one-way tooth 5a of the adjuster gear is the stopper 6 of the adjuster staying nut 3 which is screwed together.
The adjusting screw 7 is rotated beyond one tooth, and the adjusting screw 7 is screwed out that much to fill the shoe gap and exert a braking force in the same manner as described above. Then, as described above, when the brake is released without losing rigidity, the adjuster steering screw 7, screw member 8, and adjuster steering nut 3 return to their original positions, but the adjuster stay gear 5 engages the stopper 6 with the one-way tooth 5a advanced by one tooth. Since it is stopped, one-way tooth 5a 1
The adjusting screw 7 is screwed out by the amount of rotation of the teeth, and the shoe gap is automatically adjusted.

FIG. 3 shows a second embodiment. This embodiment differs from the first embodiment in the means for restraining the movement of the screw member until the drum becomes distorted due to its rigidity and the pressure oil reaches a high set pressure. The same reference numerals as in the first embodiment indicate the same parts, 1 is a wheel cylinder body, 2 is a piston whose flange 2a regulates the maximum retraction amount, and inside the piston 2 is an adjusting nut 3 for its rotation. In order to reduce dynamic resistance, a washer 14 is interposed and is rotatably inserted. 5 is an adjuster gear, 5a is a one-way tooth carved on the outer periphery of the adjuster gear, 6 is a stopper, 6a is a pin fixed to the wheel cylinder body 1, and 6b is a tension coil spring, which has the same structure as the first embodiment shown in FIG. has been done. 7 is Asia Steing Skriyu,
It is screwed into the adjusting nut 3 with a single thread. 7a supports a brake shoe (not shown) at a forked portion. Reference numeral 8' denotes a screw member, the tip of which is screwed into the adjusting nut 3 with a multi-thread screw, and the small diameter body part 8'a is fitted with an oil seal to maintain oil tightness and is attached to the bottom of the piston 2. The main body 8'c is connected to a large-diameter body part 8'c which has a flange part 8'b and forms a cavity. A bearing 18 is interposed between the back surface of the flange portion 8'b and the annular stepped portion 1c of the wheel cylinder body 1, and a coil spring 15 is compressed so that the front surface of the flange portion 8'b is located inside the cylinder body 1. Normally, it is biased so as to come into contact with the positioning member 16 of the screw member which is fixed and protrudes from the screw member. The large-diameter body 8'c is fitted with an oil seal and fitted into the wheel cylinder body 1, and has a bearing 17 interposed at its tail end and a gap δ between it and the inner bottom 1b of the wheel cylinder body 1. It is provided.

Next, the effect will be explained. cylinder body 1
When pressure oil is introduced from the outside, the piston 2 strokes. The screw member 8' has its flange portion 8'b fixed to the positioning member 1 by means of a coil spring 15.
6, the adjusting nut 3 is rotated by the action of the multi-thread screw of the screw member 8', causing the adjusting screw 7 to be screwed out. At this time, if the shoe gap is appropriate, the adjuster gear 5 maintains the locked state with the stopper 6 using the original one-way teeth 5a, and if the shoe gap exceeds the appropriate value, the one-way teeth 5a
A is advanced by one tooth and engages with the stopper 6, and the shoe gap is automatically adjusted accordingly. When the brake shoe (not shown) comes into contact with the drum, the hydraulic pressure becomes higher and reaches the set pressure, forming a stage ring that exerts braking force.The drum deforms slightly due to its rigidity, and when the piston 2 strokes, the screw The screw member 8' overcomes the repulsive force of the coil spring 15 by the high pressure oil applied to the difference in cross-sectional area between the large diameter body part 8'c and the small diameter body part 8'a of the member, fills the gap δ, and moves the positioning member 16. The rotational resistance decreases as the screw member 8' rotates, and the adjustment screw 7 does not rotate, so that the rotational resistance of the adjusting nut 2 and the adjusting screw 7 decreases. Over-adjustment due to the stiffness of is avoided. Then, when the brake is released, the screw member 8' is moved to the coil spring 1.
It is rotated in the opposite direction by the repulsive force of 5 and is screwed into the adjusting nut 3 and comes into contact with the positioning member 16,
The piston 2 is also returned to its original position by the action of a shoe return spring (not shown).

The automatic shoe gap adjustment device built into a wheel cylinder according to the present invention fits the piston into the wheel cylinder body so that it can move forward and backward while regulating the amount of return.
an adjuster stay nut is rotatably inserted into the piston, and an adjuster gear fixed to the adjuster stay nut is engaged with a stopper supported on a wheel cylinder body so as to be able to feed in only one direction;
The adjusting screw is screwed onto the front part of the adjusting nut, the piston is inserted therethrough while maintaining oil tightness, and the screw member which is screwed onto the rear part of the adjusting nut with a multi-thread screw is installed inside the wheel cylinder body. Then, the movement of the screw member is restrained by pressing the screw member with a spring interposed with a bearing against the positioning member on the wheel cylinder body side until a set load in the axial direction inward of the wheel cylinder body is applied. We have provided means.

Therefore, it was possible to provide an automatic shoe gap adjustment device that prevents the occurrence of rust and the influence of rainwater, has a built-in wheel cylinder, does not increase the rigidity of the drum, and is advantageous against thermal expansion. Further, since the amount of screwing out of the adjusting screw is determined by a one-way gear, there is a large degree of freedom in setting the shoe gap and the amount of adjustment during one braking.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the first embodiment of the wheel cylinder built-in automatic shoe gap adjustment device according to the present invention, Fig. 2 is a diagram showing the relationship between the adjuster gear and the stopper, and Fig. 3 is the same as the second embodiment. FIG. 3 is an example cross-sectional view. 1: Wheel cylinder body, 1a: Small diameter stepped surface, 1c: Annular step, 1b: Inner bottom, 2: Piston, 3: Adjuster stay nut, 5: Adjuster star gear, 5a: One-way tooth, 6: Stopper, 6
b: tension coil spring, 7: adjusting screw, 8: screw member, 8a: annular seat,
8': Screw member, 8'a: Small diameter body, 8'b:
Flange part, 8'c: Large diameter body part, 9: Positioning member, 10: Fixed spring seat, 11: First coil spring, 12: Second coil spring, 15: Coil spring, 16: Positioning member, 17: Bearing .

Claims (1)

[Scope of Claim for Utility Model Registration] 1. An adjuster gear in which a piston is fitted into a wheel cylinder body so that it can move forward and backward while regulating the amount of return, an adjuster staying nut is rotatably inserted into the piston, and the adjuster gear is fixed to the adjuster staying nut. is engaged with a stopper supported on the wheel cylinder body so as to be able to feed in only one direction, an adjuster steering screw is screwed into the front part of the adjuster stayer, the piston is inserted while maintaining oil tightness, and the adjuster stayer is inserted into the adjuster stayer. A screw member that is screwed into the rear part of the wheel cylinder body with a multi-thread screw is installed inside the wheel cylinder body, and the screw member is attached to the positioning member on the wheel cylinder body side until a set load in the axial direction toward the inside of the wheel cylinder body is applied. An automatic shoe gap adjustment device with a built-in wheel cylinder, characterized in that it is provided with means for restraining the movement of a screw member by pressing with a spring interposed in a bearing. 2. A fixed spring seat whose outer edge is fixed to the wheel cylinder body and surrounded by the screw member, and a first coil spring seated on the fixed spring seat that is biased to lock the outer edge to the wheel cylinder body. a positioning member that is ring-mounted on the positioning member; and a first member that presses and biases the annular seat of the screw member that contacts the positioning member through a bearing.
The second spring has a smaller spring load than the coil spring.
An automatic shoe gap adjustment device built into a wheel cylinder according to claim 1, which has means for restricting movement of a screw member comprising a coil spring. 3 A screw member consisting of a small-diameter body, a flange, and a large-diameter body connected to a multi-threaded thread carved in the tip, and which fits into the wheel cylinder body while keeping the large-diameter body oil-tight. , a positioning member protruding and fixed inward of the wheel cylinder body, a coil spring that biases the flange against the positioning member via a bearing, and between the end surface of the large diameter body and the inner bottom surface of the wheel cylinder body. An automatic shoe gap adjustment device built into a wheel cylinder according to claim 1, which has means for restricting movement of a screw member consisting of a bearing interposed with a gap therebetween.