JPH0346263Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a disc brake with a parking brake mechanism, and in particular, a cup-shaped piston slides in the axial direction through a piston seal in a cylinder formed in a caliper. The present invention relates to a disc brake with a parking brake mechanism, in which the piston is pushed by the parking brake mechanism or pressurized fluid supplied into the cylinder to press the pad.

[Conventional technology]

As a parking brake mechanism for this type of disc brake, the applicant has disclosed various advantages (automatic adjustment of pad clearance, good workability during pad replacement, and prevention of piston seal damage) in Japanese Patent Application Laid-open No. 166733/1983. We have proposed a mechanism that can efficiently discharge the air inside the cylinder.

[Problem that the invention attempts to solve]

In the conventional parking brake mechanism described above, a toggle, a pusher, a plate, and an adjustment mechanism are used between the camshaft rotated by the parking brake operation and the piston mechanically pushed by the camshaft. Since five members, the bolt and the adjustment nut, are involved, the distance from the piston to the camshaft is long, and a large installation space is required. Furthermore, in the conventional parking brake mechanism described above, when the parking brake is not activated, a small gap is formed between the head of the adjustment bolt and the pusher, and this gap is used to prevent the backlash between the adjustment bolt and the adjustment nut. Together with the return stroke obtained by the restoring action of the piston seal, this becomes an invalid stroke when the parking brake is activated, and the invalid stroke becomes larger.

[Means for solving problems]

The present invention was developed to solve this problem, and allows the parking brake mechanism to slide in the axial direction through a seal ring within a mounting hole provided coaxially with the piston in the bottom wall of the cylinder formed in the caliper. and a bottomed cylindrical adjustment nut which is fitted in a fluid-tight manner and whose open end protrudes into the cylinder; an adjusting bolt constituting a clutch; a spring interposed between the head of the adjusting bolt and the peripheral wall of the piston to bias the adjusting bolt toward the top wall of the piston; A thrust bearing that guarantees rotation, and a through hole provided in the top wall of the piston that prevents it from falling out of the cylinder and are movable in the axial direction and are assembled in a liquid-tight manner. a pushing member that faces the central top surface of the head and engages with the central top surface of the head when pushed into the cylinder to constitute a second thrust bearing; a camshaft rotatably supported by a support portion formed in the camshaft, the camshaft having a cam groove facing the closed end of the adjustment nut and rotated by a parking brake operation; The toggle is interposed between the closed ends of the cam groove to move the adjusting nut in the axial direction according to the rotational displacement of the cam groove, and always restricts the rotation of the adjusting nut.

[Effect of invention]

According to the above configuration, when the piston is pushed toward the pad by the pressure fluid supplied into the cylinder, the adjusting nut is pushed toward the opposite side, and as the lining of the pad wears out, the piston The top wall of the piston moves away from the head of the adjusting bolt, and due to the cooperative action of the spring and thrust bearing, the adjusting bolt rotates and protrudes relative to the adjusting nut until it engages the top wall of the piston, and when the hydraulic pressure is removed, the piston As the piston seal is returned by the restoring action, the adjusting bolt is returned together by a predetermined amount (an amount corresponding to the backlash between the adjusting bolt and the adjusting nut), and the pad clearance is automatically adjusted.

Furthermore, when the parking brake is activated, the piston is pushed toward the pad via the toggle, adjustment nut, and adjustment bolt as the camshaft rotates, and the parking brake is activated. At this time, the backlash between the adjusting bolt and the adjusting nut has been eliminated by the return stroke obtained by the restoring action of the piston seal, so the ineffective stroke is obtained by the restoring action of the piston seal. There is only a return stroke.

On the other hand, when replacing the pad, push the pushing member into the cylinder, engage the inner end of the pushing member with the center top surface of the head of the adjustment bolt, and then move the piston with the head of the adjustment bolt separated from the top wall of the piston. When pushed into the cylinder, the adjustment bolt rotates and toggles due to the cooperative action of the central top surface of its head, the thrust bearing of the chamber 2 which is a pushing member, and the thrust bearing interposed between the head and the peripheral wall of the piston. Since the piston enters the adjusting nut whose rotation is restricted by the piston, the piston is returned to its initial state without rotating.

[Effect of idea]

As is clear from the above-mentioned operation, in the disc brake with parking brake mechanism according to the present invention, the pad clearance is automatically adjusted in accordance with normal brake operation in which pressurized fluid is supplied to and removed from the cylinder. I can do it. Further, since the invalid stroke when the parking brake is activated can be limited to only the return stroke obtained by the restoring action of the piston seal, the invalid stroke can be reduced and the amount of operation can be reduced. Furthermore, when replacing pads, by pushing the pushing member into the cylinder and pushing the piston into the cylinder, it is possible to return to the initial state without rotating the piston. Damage to the seal can be prevented.

In addition, in the disc brake with parking brake mechanism according to the present invention, as is clear from its structure, there are only three members, the toggle, the adjustment nut, and the adjustment bolt, between the camshaft and the piston, so The dimensions can be shortened, and it can be easily installed even in a small installation space.

〔Example〕

An embodiment of the present invention will be described below based on the drawings. In the disc brake shown in the figure,
Pads 12 and 13 are arranged on both sides of the disc rotor 11 on a torque member 10 that is assembled to a part of the vehicle body (for example, a knuckle arm) (not shown).
is assembled so as to be slidable in the left and right directions in the figure.
Further, a caliper 20 is attached to the torque member 10 by a known means so as to be slidable in the left and right directions in the drawing. Caliper 20 is disk rotor 11
It is formed in a shape that surrounds both pads 12 and 13 by straddling a part of the outer periphery of the pad, and is formed in a bifurcated shape at the right end in the figure to form a back metal 12a of the pad 12 on the right side in the figure.
A push arm 20a that comes into contact with the back surface is formed, and a cylinder 20b is formed on the left side in the figure. The cylinder 20b is formed in the left-right direction in the figure, and a cup-shaped piston 21 is attached to the seal ring 2.
2 so as to be slidable in the axial direction, and is in contact with the back surface of the back metal 13a of the pad 13. This piston 21 is configured to be pushed by pressure fluid supplied into the cylinder 20b or by a parking brake mechanism, and its outer periphery and the cylinder 20b
A dust boot 29 is attached between the outer ends of the dust boot 29 . In addition, the piston 21 is the back metal 13 of the pad 13.
Rotation is prevented by a protrusion 13b provided at a.

The parking brake mechanism includes a bottomed cylindrical adjustment nut 31, an adjustment bolt 32, a spring 33, a thrust bearing 34, a pushing member 35, a camshaft 36, a toggle 37, and the like. The adjustment nut 31 is slidably and liquid-tightly inserted in the axial direction through a seal ring 38 into the mounting hole 20e of the boss portion 20d formed at the center of the bottom wall 20c of the cylinder 20b, and the opening end thereof 31a protrudes into the cylinder 20b. The adjustment bolt 32 is screwed into the adjustment nut 31 with a large pitch screw so that it can move forward and backward, and its head 32a is formed into a tapered shape and engages in a taper hole 21b formed in the top wall 21a of the piston 21. This makes up the clutch. Further, a conical projection 32b (a spherical projection can also be used) is integrally formed on the central top surface of the head 32a of the adjustment bolt 32.

The spring 33, together with the thrust bearing 34, is connected to the peripheral wall of the piston 21 and the head 32a of the adjustment bolt 32.
The adjustment bolt 32 is biased toward the right in the figure (towards the piston 20). The thrust bearing 34 is located between the head 32a of the adjusting bolt 32 and the spring 33 to ensure smooth rotation of the adjusting bolt 32. The pushing member 35 is disposed coaxially with the adjustment bolt 32, and is slidably and liquid-tightly assembled in the through hole 21c provided in the top wall 21a of the piston 21 in the axial direction via a seal ring 39. The annular flange 35a prevents the cylinder from falling off to the right (outside the cylinder). Further, the pushing member 35 faces the head protrusion 32b of the adjustment bolt 32 with a slight gap at its inner end, and when pushed to the left, engages with the head protrusion 32b and generates a second thrust. Configure the bearing.

The camshaft 36 is rotated by the operation of the parking brake, is rotatably inserted into a support hole 20f provided perpendicularly to the mounting hole 20e, and is supported by the support portion 20g of the caliper 20. The recess 31b at the left end of the adjustment nut 31 in the illustration
It has a cam groove 36a in the axial direction facing the support hole 20f, and a parking lever (not shown) is integrally provided at the end projecting outside the support hole 20f. The camshaft 36 is biased counterclockwise in the drawing by a torsion spring (not shown) interposed between the lever and the caliper 20, so that the lever comes into contact with a protrusion (not shown) provided on the caliper 20. It is positioned at the original position shown in the drawing, with rotation in the counterclockwise direction shown in the drawing being regulated. toggle 37
is flat and has an egg-shaped cross section as shown in the figure, and has a cam groove 36a and a recess 3 of the adjustment nut 31.
1b, and has the function of moving the adjusting nut 31 in the left-right direction (axial direction) in the drawing according to the rotational displacement of the cam groove 36a, and the function of always regulating the rotation of the adjusting nut 31.

In this embodiment configured as described above, when pressurized fluid is supplied into the cylinder 20b, the piston 21 moves to the right and presses the pad 13 against the left side of the disc rotor 11, and at the same time the caliper 20 moves to the right. Since it moves to the left and presses the pad 12 against the right side surface of the disc rotor 11 with its pushing arm 20a, normal braking operation can be obtained. At this time,
In the parking brake mechanism, the adjusting nut 31 is pressed toward the right, and both pads 1
As the linings 2 and 13 wear out, the top wall 21a of the piston 21 separates from the head 32b of the adjustment bolt 32, and the adjustment bolt 32 moves away from the top of the piston 21 due to the cooperative action of the spring 33 and the thrust bearing 34. Engages with the wall 21a (head 32a
is rotated relative to the adjusting nut 31 until it tapers into the tapered hole 21b and protrudes from the adjusting nut 31. Further, when the hydraulic pressure in the cylinder 20b is removed, the piston 21 is returned to the left by the restoring action of the piston seal 22, and the caliper 20 is returned to the right by the frictional vibration between the disc rotor 11 and the pad 12. At this time, in the parking brake mechanism, as the piston 21 is returned by the restoring action of the piston seal 22, the adjustment bolt 32 is integrally moved by a predetermined amount (corresponding to the backlash between the adjustment bolt 32 and the adjustment nut 31). amount) returned. Therefore, in this embodiment, the lining 12 of both pads 12, 13
Regardless of the wear of the disc rotor 11 and the pads 12 and 13, the pad clearance between the disc rotor 11 and both pads 12 and 13 during non-operation is always maintained substantially constant.

In addition, in this embodiment configured as described above, the camshaft 36 is
When the cam groove 36a is rotated clockwise in the figure, the cam groove 36a is rotationally displaced to the right, and the toggle 37 and adjustment nut 31 are rotated.
The piston 21 is pushed to the right via the adjusting bolt 32, and the pad 13 is moved to the disk rotor 11.
The caliper 20 is pushed to the left by the reaction force, and the pad 12 is pressed against the right side of the disc rotor 11 to activate the parking brake. At this time, the toggle 37 restricts the rotation of the adjustment nut 31, and the head 32a of the adjustment bolt 32 and the piston 21
The tapered hole 21b of the adjustment bolt 32 is frictionally engaged with the adjustment bolt 32.
In order to restrict the rotation of the adjusting bolt 32 and the adjusting nut 31, neither the adjusting bolt 32 nor the adjusting nut 31 rotates, and the amount of protrusion of the adjusting bolt 32 from the adjusting nut 31 does not change. Also, at this time, the backlash between the front adjustment bolt 32 and the adjustment nut 31 is caused by the piston seal 22.
Since the return stroke obtained by the restoring action of the piston seal 22 is eliminated, the only invalid stroke is the return stroke obtained by the restoring action of the piston seal 22.

In the parking brake mechanism in such a state (when the parking brake is activated), the camshaft 3
6 is rotated counterclockwise in the figure, the cam groove 36
a is rotationally displaced to the left, and the toggle 37, adjustment nut 31, adjustment bolt 32, and piston 21 are returned to the left to their original positions in the drawing by the restoring action of the piston seal 22, and the caliper 20 is returned to the right. The parking brake will be released.
At this time as well, the toggle 37 restricts the rotation of the adjustment nut 31, and the head 3 of the adjustment bolt 32
2a and the tapered hole 21b of the piston 21 frictionally engage with each other to restrict the rotation of the adjustment bolt 32, so the adjustment bolt 42 and the adjustment nut 41 do not rotate together.
The amount by which the adjustment bolt 32 protrudes from the adjustment nut 31 remains unchanged.

Furthermore, in this embodiment configured as described above, when replacing the pad, the pushing member 35 is pushed to the left and its inner end is inserted into the head protrusion 32 of the adjustment bolt 32.
b and the head 3 of the adjustment bolt 32.
If the piston 21 is pushed into the cylinder 20b with the piston 2a separated from the taper hole 21b of the piston 21, the adjustment bolt 32 will move between the second thrust bearing consisting of the head protrusion 32b and the pushing member 35, and the thrust bearing 34. Adjusting nut 3 rotates by cooperative action and whose rotation is regulated by a toggle 37
1, the piston 21 is returned to its initial state without rotating.

As is clear from the above description, in the disc brake with parking brake mechanism of this embodiment, the pad clearance is automatically adjusted in accordance with normal brake operation in which pressurized fluid is supplied to and removed from the cylinder 20b. can do. Further, since the invalid stroke when the parking brake is activated can be limited to only the return stroke obtained by the restoring action of the piston seal 22, the invalid stroke can be reduced and the amount of operation can be reduced. Furthermore, when replacing the pad, push the pushing member 35 to the left to remove the piston 21.
By pushing the piston 21 into the cylinder 20b, the piston 21 can be returned to its initial state without rotating, which not only improves workability but also prevents damage to the piston seal 22 due to the rotation of the piston 21. Note that since the adjustment nut 31 and the pushing member 35 only move in the axial direction and do not rotate, the seal rings 38 and 39 are not damaged by the rotation of the adjusting nut 31 and the pushing member 35.

On the other hand, in the disc brake with parking brake mechanism of this embodiment, only three members, the toggle 37, the adjustment nut 31, and the adjustment bolt 32, are interposed between the camshaft 36 and the piston 21 as shown in the figure. The dimension up to the camshaft 36 can be shortened, and it can be easily implemented even in a small installation space.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of the present invention. Explanation of symbols, 13...Pad, 20...Caliper, 20b...Cylinder, 20c...Bottom wall, 20
d...Boss part, 20e...Mounting hole, 20f...Support hole, 20g...Support part, 21...Piston, 2
1a...Top wall, 21b...Tapered hole, 21c...
Through hole, 22... Piston seal, 31... Adjustment nut, 31a... Open end, 31b... Recess, 3
2...adjustment bolt, 32a...head, 32b...
Projection (top surface), 33... Spring, 34... Thrust bearing, 35... Pushing member, 36... Camshaft, 36a... Cam groove, 37... Toggle, 38,
39... Seal ring.

Claims (1)

[Scope of utility model registration request] A cup-shaped piston is fitted into a cylinder formed in the caliper so as to be slidable in the axial direction via a piston seal, and this piston is pushed by a parking brake mechanism or pressurized fluid supplied into the cylinder. In the disk brake with a parking brake mechanism, the parking brake mechanism is slid in the axial direction through a seal ring into a mounting hole provided coaxially with the piston in the bottom wall of the cylinder. a bottomed cylindrical adjustment nut that is movably and fluid-tightly fitted and whose open end protrudes into the cylinder; An adjusting bolt which together constitutes a clutch, a spring interposed between the head of the adjusting bolt and a circumferential wall of the piston to bias the adjusting bolt toward the top wall of the piston, and a spring for urging the adjusting bolt toward the top wall of the piston. A thrust bearing that ensures smooth rotation, and a through hole provided in the top wall of the piston prevent it from falling out of the cylinder, and are movable in the axial direction and are assembled in a liquid-tight manner, and the adjustment is performed at the inner end. a pushing member that faces the central top surface of the head of the bolt and engages with the central top surface of the bolt head when pushed into the cylinder to constitute a second thrust bearing; and on the closed end side of the adjustment nut. a camshaft that is rotatably supported by a support portion formed on the caliper and has a cam groove facing the closed end of the adjustment nut and is rotated by a parking brake operation; The present invention is characterized by a toggle interposed between the closed ends of the adjustment nut to move the adjustment nut in the axial direction in response to rotational displacement of the cam groove and to always restrict rotation of the adjustment nut. Disc brake with parking brake mechanism.