JPH075305Y2 - Piston assembly for disc brake with parking brake mechanism - Google Patents

Description

TECHNICAL FIELD The present invention relates to a piston assembly used in a disc brake with a parking brake mechanism.

2. Description of the Related Art A piston body having a bottomed cylindrical shape, an adjustment nut provided inside the piston body, and an adjustment nut that is inserted between the adjustment nut and the piston body on the outer peripheral side of the adjustment nut in a preloaded state. There is known a piston assembly for a disc brake with a parking brake mechanism, which is provided with a compression coil spring that urges a nut toward the bottom side of the piston body to press it against the piston body, for example, in Japanese Patent Laid-Open No. 60-53229. An example is shown.

In such a piston assembly, an adjustment nut, in which a compression coil spring is fitted on the outer peripheral surface, is usually arranged inside the piston body, and the compression coil spring is preloaded with the adjustment nut to form an annular shape. It is assembled by fixing the spring seat to the inner peripheral surface of the piston body.

However, the fixing of the above-mentioned spring seat to the inner peripheral surface of the piston body is usually performed with the spring seat abutting the stepped surface formed on the inner peripheral surface of the piston body. This is done by caulking the stepped part formed on the inner peripheral surface of the main body, and since the fixing work due to this caulking must be performed with the compression coil spring preloaded, the spring seat is attached to the inner peripheral surface of the piston main body. Since the work of fixing to the surface is relatively troublesome and time-consuming, there is a problem that the assemblability of the piston assembly cannot be obtained properly.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an adjust nut between a piston body and an adjust nut arranged inside the piston body. (EN) Provided is a piston assembly in which a compression coil spring biased to a side can be easily and quickly assembled in a preloaded state, and the assemblability can be suitably obtained.

Means for Solving the Problems In order to achieve the above object, the present invention provides a piston assembly for a disc brake with a parking brake mechanism of the type described above, which has one end in a direction parallel to the axial center of the compression coil spring. A spring seat for receiving the portion is integrally formed on the inner peripheral surface of the piston body, and the outer diameter of the portion other than one end of the compression coil spring is set to be smaller than the inner diameter of the spring seat.

With this configuration, the spring seat that receives one end of the compression coil spring in the direction parallel to the axial center is integrally formed on the inner peripheral surface of the piston body, so that it can be separated from the conventional one. Since it is not necessary to fix the prepared spring seat to the inner peripheral surface of the piston body by crimping etc., the outer diameter of the portion other than one end of the compression coil spring is set smaller than the inner diameter of the spring seat. By pressing the part of the compression coil spring other than one end toward the inner circumference of the spring seat and compressing the compression coil spring while reducing the diameter of one end of the compression coil spring, the entire compression coil spring becomes the inner circumference of the spring seat. It can be passed relatively easily. As a result, the compression coil spring can be assembled relatively easily and quickly between the spring seat integrally provided on the inner peripheral surface of the piston body and the adjustment nut in a preloaded state. It can be ensured more suitably than

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a view showing a main part of a disc brake with a parking brake mechanism equipped with a piston assembly to which the present invention is applied. In the figure, a caliper 12 is laid across the outer peripheral portion of a disk rotor 10 that is rotatably provided with wheels, and the caliper 12 is not shown in a support member 14 fixed to a non-rotating member (not shown). It is movably supported in a direction parallel to the axis of the disk rotor 10 via a slide pin or the like. The curiper 12 has a first cylinder bore 16, and a piston body 18 having a cylindrical shape with a bottom as a whole is fitted in the first cylinder bore 16 so as to be capable of protruding in one direction in a state where the piston body 18 cannot rotate relative to its axis. Cylinder portion 20, a protruding portion 22 integrally provided on the cylinder portion 20 at an end of the cylinder portion 20 opposite to the protruding direction of the piston body 18, and an end portion of the cylinder portion 20 in the protruding direction of the piston body 18. And a bifurcated claw portion 24 opposed to the cylinder portion 20 with the disc rotor 10 interposed therebetween. Inside the caliper 12, namely the piston body 18
A pair of pads 26 and 28 are arranged between the claw portion 24 and the claw portion 24 with the disc rotor 10 sandwiched therebetween.
6, 28 are movably supported by the support member 14 in a direction parallel to the axis of the disk rotor 10.

A second cylinder bore 30 is formed inside the protrusion 22 so as to be adjacent to and substantially concentric with the first cylinder bore 16, and the second cylinder bore 30 has a male screw portion 32 and a head portion 34 having a larger diameter than that. The adjust bolt 36 having the above is fitted in the head portion 34 so that the male screw portion 32 is located inside the piston body 18 so as to be relatively movable in the axial direction and non-rotatable around the axial center. The adjustment bolt 36 has its head 34
And a washer 38 integrally provided on the inner peripheral surface of the first cylinder bore 16 are constantly urged in a direction away from the piston body 18 by a spring 40 interposed therebetween.
An adjust nut 42 is screwed onto the 32 in a state having a predetermined rattling in the axial direction. A flange portion 44 protruding in the outer peripheral direction is provided at an end portion of the adjustment nut 42 located on the tip side of the male screw portion 32.

On the inner peripheral surface of the opening side end of the piston body 18, an annular protrusion 46 protruding to the inner peripheral side by a predetermined size is integrally formed by cutting, and the thrust nut is formed on the outer peripheral surface of the cylindrical portion of the adjust nut 42. A bearing 48 and a plain washer 50 are fitted so as to be adjacent to the flange portion 44. A compression coil spring 52 is inserted between the flat washer 50 and the annular projection 46 in a predetermined preload state, and the adjusting nut 42 is attached to the outer peripheral surface of the flange portion 44 according to the biasing force of the compression coil spring 52. The formed tapered surface is brought into pressure contact with the tapered inner wall of the piston body 18 in the protruding direction of the piston body 18. As a result, during non-braking, the adjustment nut 42 is prevented from rotating in the direction opposite to the parking brake operation stroke adjusting direction, which will be described later, due to vehicle vibration or the like. In this embodiment, the piston body 18, the adjusting nut 42, the thrust bearing 48, the flat washer 50, the compression coil spring 52 and the like constitute a piston assembly. The biasing force of the compression coil spring 52 is set to be smaller than the biasing force of the spring 40, and the compression coil spring 52 is configured such that its diameter becomes smaller as it is separated from the annular protrusion 46, and The outer diameter of one winding located at one end in the direction parallel to the axis of the coil spring 52 and at the end on the side of the annular protrusion 46 is set to be larger than the inner diameter of the annular protrusion 46. The outer diameter of the portion of the spring 52 other than the one-roll portion is set to be smaller than the inner diameter of the annular protrusion 46. Incidentally, 54 is the piston body 18 and the first cylinder bore 16
Is a piston seal that seals a liquid-tight space between the piston and the piston body and that returns the piston body.

Inside the protruding portion 22, the first cylinder bore 30 of the second cylinder bore 30 is further provided.
The second cylinder bore 30 on the side opposite to the cylinder bore 16 side
A mounting hole 56 is provided so as to communicate with the second cylinder bore 30 in a direction perpendicular to the axis center of the mounting hole.
Within 56, a cam shaft 58 is provided via a needle roller bearing 60 so as to be rotatable about its axis. A crank lever 62, to which the parking brake operating force is transmitted, is attached to one end of the cam shaft 58 and located outside the protruding portion 22 so as to be relatively unrotatable, and an intermediate portion in the longitudinal direction of the cam shaft 58. The engaging recess 64 is formed in the engaging recess 64.
A rod-shaped toggle 68 is provided between the engaging recess 66 formed on the tip surface of the head 34 of the adjusting bolt 36 and the needle roller bearing.
It is inserted with 60 inserted. The crank lever 62 is constantly urged in the parking brake non-operating direction (clockwise direction in FIG. 1) by a return spring (not shown).

In the disc brake configured as described above,
When the cam shaft 58 is rotated counterclockwise in FIG. 1 by the crank lever 62, a thrust is generated in the toggle 68, and the thrust is transmitted to the piston body 18 via the adjustment bolt 36 and the adjustment nut 42. Piston body 18
The pads 26, 28 are narrowed by the claw portion 24 of the caliper 12 and the parking brake is applied. on the other hand,
When hydraulic pressure is supplied into the first cylinder bore 16, the piston body 18 is pushed out, and braking is performed in the same manner as in the above case. At this time, the amount of wear of the pads 26, 28 becomes large, and when the piston body 18 protrudes, the piston body 18
When slippage occurs between the piston seal 54 and the piston seal 54 and the protrusion amount of the piston body 18 exceeds a predetermined constant amount, the adjustment nut 42 is moved when the piston body 18 moves forward.
The parking brake operation stroke is automatically adjusted based on the rotation of the vehicle in one direction. The above-mentioned brake operation and adjustment operation are not always necessary for understanding the present invention, and thus detailed description thereof will be omitted.

Thus, according to this embodiment, the compression coil spring 52
Since the annular protrusion 46 that functions as a spring seat for receiving one end of the piston body 18 is integrally formed on the inner peripheral surface of the piston body 18, separately prepared spring seats are crimped on the inner peripheral surface of the piston body as in the conventional case. It is not necessary to fix one by one, and
Since the outer diameter of the portion other than one turn located at one end of the compression coil spring 52 is set smaller than the inner diameter of the annular protrusion 46, when assembling the piston assembly, for example, the thrust bearing 48 and the flat washer are used.
After arranging the adjustment nut 42, in which 50 is fitted on the outer peripheral surface, inside the piston body 18, the compression coil spring
A portion other than one turn of the one end of 52 is pushed into the inner peripheral side of the annular projection 46, and the one turn of the one end of the compression coil spring 52 is reduced in diameter by using a predetermined tool. By compressing 52, the entire compression coil spring 52 can pass through the inner peripheral side of the annular protrusion 46 relatively easily. As a result, the compression coil spring 52 can be assembled relatively easily and quickly between the annular protrusion 46 and the flange portion 44 of the adjustment nut 42, which are integrally provided on the inner peripheral surface of the piston body 18, in a preloaded state. As a result, the assemblability of the piston assembly can be obtained more favorably than the conventional one. Moreover, there is an advantage that the number of parts is reduced because a separate part as a spring seat is not required as in the conventional case.

Further, according to the present embodiment, the outer diameter of the portion of the compression coil spring 52 other than one turn located at one end is set to be smaller than the inner diameter of the annular protrusion 46, so that the compression coil spring 52 can be relatively easily manufactured. There is an advantage that the piston assembly can be suitably disassembled if necessary.

In the above-described embodiment, the annular protrusion 46 that functions as a spring seat is formed on the inner peripheral surface of the opening-side end of the piston body 18, but is formed at a portion located a predetermined distance inside from the opening end. Good.

Further, in the above-described embodiment, the spring seat is formed by the annular protrusion 46, but it may be formed by a plurality of protrusions formed on the inner peripheral surface of the piston body at predetermined circumferential intervals.

Further, in the above-described embodiment, the annular protrusion 46 as the spring seat is configured to have a rectangular cross section, but it is not always necessary. For example, as shown in FIG. 2 and FIG.
A spring seat may be formed by an annular protrusion 72 having a tapered inner peripheral surface 70 whose diameter becomes smaller toward the bottom of the piston body 18. In this way, one end of the compression coil spring 52 can be suitably guided along the tapered inner peripheral surface 70 of the annular projection 72 as shown by the chain double-dashed line in FIG.
The inner peripheral side of the can be passed more easily. 2 and 3
In the figure, the annular protrusion 72 is further provided with four notches 74 at predetermined intervals in the circumferential direction. These notches 74 are 4
Compression coil spring with a jig that has two rod-shaped pressing parts
When one end of 52 is pressed against the tapered inner peripheral surface 70 of the annular projection 72 and reduced in diameter so as to pass through the inner peripheral side of the annular projection 72, it is avoided that those rod-shaped pressing portions are abutted against the annular projection 72. As a result, the assembling work of the compression coil spring 52 is further facilitated, and the assemblability of the piston assembly is more suitably obtained. Further, by providing such a notch 74, there is an advantage that the air bleeding property in the piston body 18 can be suitably obtained.

Further, in the above-described embodiment, the outer diameter of the portion other than one turn of the compression coil spring 52 is set to be smaller than the inner diameter of the annular protrusion 46, but it is not always necessary. The effect of the present invention can be obtained even if the outer diameter of the portion other than the two turns on the one end side of 52 is set smaller than the inner diameter of the annular protrusion 46. That is, the one end in the direction parallel to the axis of the compression coil spring in the claims does not necessarily mean only one turn.

Further, in the above-described embodiment, the compression coil spring 52 is configured to have a smaller diameter as it is separated from the annular protrusion 46, but this is not necessarily required, and for example, only the outer diameter of one end of the compression coil spring is provided. The effect of the present invention can be obtained even when the inner diameter of the spring seat is set to be larger and the other portion has an outer diameter smaller than the inner diameter of the spring seat and is configured in a cylindrical shape.

Besides, the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a disc brake with a parking brake mechanism equipped with a piston assembly according to an embodiment of the present invention. FIG. 2 is a view showing a piston body of a piston assembly which is another example of the present invention, and is a view corresponding to the piston body of FIG. Third
The figure is a view of the piston body of FIG. 2 as seen from its opening side. 18: Piston body 42: Adjust nut 46,72: Annular protrusion (spring seat) 48: Thrust bearing 50: Plain washer 52: Compression coil spring

Claims (1)

[Scope of utility model registration request] 1. A piston body having a cylindrical shape with a bottom, an adjustment nut provided inside the piston body, and a preload state interposed between the adjustment nut and the piston body on the outer peripheral side of the adjustment nut. And a compression coil spring for urging the adjustment nut toward the bottom side of the piston main body to bring it into pressure contact with the piston main body, the piston assembly for a disc brake with a parking brake mechanism being parallel to the axis of the compression coil spring. A spring seat that receives one end in the opposite direction is integrally formed on the inner peripheral surface of the piston body, and the outer diameter of the portion other than the one end of the compression coil spring is set to be smaller than the inner diameter of the spring seat. Piston assembly for disc brake with parking brake mechanism.