JPH10252787A - Wire connection section structure for parking brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the breakage of a screw section and improve reliability by providing a collar member outwardly coupled with the screw section of a brake wire, slidably inserted into the hollow hole of a ball stud, and prohibiting the contact between the screw section and the hollow hole of the ball stud. SOLUTION: The tip section of a collar member 76 is set to the size to be fully inserted into the hollow hole 48 of a ball stud 44 in the operating state that a center brake, i.e., a parking brake, applies the required braking force. When the required tensile force is applied to a brake wire 36 to compress a return spring 72 and a sensor spring 56 and a cam shaft lever 26 is rotated to operate the parking brake, the collar member 76 is kept in contact with an opening edge on the cam shaft lever 28 side of the hollow hole 48 of the ball stud 44, and a screw section 38 is kept in no contact with the opening edge of the hollow hole 48. The breakage of the screw section 38 is surely prevented, and reliability and durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use as a so-called center brake disposed at an output end of a transmission as a parking brake device for a vehicle having a large inertial mass such as a truck, particularly a wire connecting portion structure of a parking brake. The present invention relates to a wire connection structure of a simple parking brake.

[0002]

2. Description of the Related Art An example of a schematic structure of a center brake in a conventional truck or the like and an example of a structure of a connecting portion of a wire for operating the brake will be described with reference to FIGS. First, in FIGS. 3 and 5, reference numeral 10 generally indicates a center brake provided on a truck or the like. The center brake 10 is fixed to a housing of a transmission (not shown) by bolts or the like, and a dustproof cover 12 and Support plate 1 for supporting brake shoes
1 and brake tram.

[0003] The support plate 11 and the cover 12
A pair of notched arcuate brake shoes 14 are housed in the assembly of the above, and a cam 18 formed at one end of a camshaft 16 is provided between one end 14a of the brake shoes 14 adjacent in the circumferential direction. It is sandwiched. A screw / nut type adjuster 20 for adjusting a shoe interval is interposed between the other ends 14b of the pair of brake shoes 14 which are adjacent in the circumferential direction.

An anchor pin brace 22 provided on the support plate 11 and cover 12 assembly
A shoe return spring 24 is mounted between the brake shoe 14 and each of the brake shoes 14.
It is always elastically biased toward the side 8. The base of the camshaft lever 26 is tightly fixed to the end of the camshaft 16 penetrating the support plate 11 and cover 12 and protruding from the rear surface on the transmission housing side by bolts 28. As shown in FIG. 3, a handbrake bracket 30 is fixed to a wall surface of the assembly of the support plate 11 and the cover 12 on the camshaft lever 26 side.

[0005] The other end of the outer cable 32a of the brake cable 32, one end of which is connected to a handbrake lever in a cab (not shown), is fixed to the handbrake bracket 30 via a mounting member 34, and the other end of the outer cable 32a. An inner wire or brake wire 36 extending from the end is connected to the free end 26a of the camshaft lever 26 in a manner described in detail below.

The free end 2 of the camshaft lever 26
As shown in the enlarged cross-sectional view of FIG. 6, a threaded portion 38 formed at the end of the brake wire 36 is provided at 6a.
Is provided, and a spherical seat 42 communicating with the conical hole 40 is provided. A spherical portion 46 of a ball stud 44 abuts on the spherical seat 42 in a slidable manner. The ball stud 44 is provided with a hollow hole 48 through which the screw portion 38 of the brake wire 36 is inserted.

As best shown in FIGS. 3 and 5,
A bottom plate 50a of a U-shaped spring cage 50 is fitted on the shaft of the ball stud 44, and a pair of stopper pins 52 are mounted near the ends of both legs 50b of the spring cage 50. The spring cage 5
The spring retainer 54 is inserted into the ball stud 44 so as to freely slide in the axial direction of the ball stud 44, and the spring retainer 54 and the bottom plate 50 of the spring cage 50 are inserted.
a, a brake F auto sensor spring (hereinafter abbreviated as a sensor spring) 56 is contracted.

A nut 58 and a lock nut 60 that come into contact with the spring retainer 54 are screwed to the end of the threaded portion 38 of the brake cable 36 to form a locking member. Spring retainer 54 for threaded portion 38 of 36
Is defined. Further, the camshaft lever 26 is provided on the bottom plate 50a of the spring cage 50.
An extension 50c extending in the longitudinal direction is provided in a protruding manner, and a switch device 62 is mounted on the extension 50c.

A switch operating arm 64 projects from the spring retainer 54 substantially in parallel with the extension 50c.
2 is in contact with the second working end 62a. Further, the bottom plate 50a of the spring cage 50 has a rotation preventing projection 50d.
Is provided.

The free end 2 of the camshaft lever 26
A nut 68 and a lock nut 7 for supporting a spring retainer 66 are provided on the screw portion 38 of the brake wire 36 between the hand brake bracket 30 and the hand brake bracket 30.
The return spring 72 is contracted between the spring retainer 66 and the mounting member 34. The return spring 72 is connected to the brake wire 3
6 is always elastically urged in the brake release direction.

In the center brake 10 described above, when the hand brake lever (not shown) in the cab is operated to pull the inner cable 36 of the brake cable 32 rightward in FIG. 3, the return spring 72 is compressed. At the same time, the sensor spring 56 in the spring cage 50 is compressed via the spring retainer 54 and the camshaft lever 2 is compressed via the ball stud 44.
6 is rotated clockwise in the above figure.

The clockwise rotation of the camshaft lever 26 causes the camshaft 16 and thus the cam 18 to rotate in the same direction. It is expanded radially outward and pressed against a brake drum 74, which is schematically indicated by a two-dot chain line in FIG. Same brake drum 74
Is connected to the output shaft of the transmission and the propeller shaft, as is well known in the art. Therefore, when the brake shoe 14 is pressed against the brake drum 74, the parking brake is operated. .

When the traction force of the brake wire 36 in the brake operation direction exceeds a set value, the spring cage 5
0, the compression amount of the sensor spring 56 exceeds the set amount, and the switch operating arm 64 protruding from the spring retainer 54 is connected to the operating end 6 of the switch device 62.
3a is displaced rightward by more than the set amount in FIG. 3, and the switch device 62 is closed. By closing the switch device 62, a display device (not shown) such as a parking brake lamp indicating that the parking brake is operating to a sufficient degree for safety is energized.

The main cause of the circular movement of the cam shaft lever 26 in response to the linear displacement of the brake wire 36 when the parking brake is operated and released is shown by a two-dot chain line circle A in FIG. As shown, the hollow hole 4 in the spherical portion 46 of the ball stud 44 is
8 and the screw portion 38 interfere with each other, and it is assumed that the screw portion 38 is damaged and the screw thread is crushed by a large number of operation and release of the parking brake. There was a fear of giving a feeling of distrust.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been developed in view of the above circumstances. When a parking brake is applied, a screw portion of a brake wire interferes with an opening edge of a hollow hole of a ball stud. It is an object of the present invention to provide a parking brake wire connection structure capable of reliably preventing damage to a vehicle portion and improving reliability and durability.

[0016]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a camshaft lever connected to a camshaft for operating a brake shoe of a drum brake and driving the camshaft; A ball stud provided with a hollow hole interposed at a free end, a screw member formed at one end is inserted into the hollow hole of the ball stud, and a locking member screwed into the screw portion and the ball stud are formed. A brake wire that transmits a rotational force to the camshaft lever via the screw portion of the brake wire, and is slidably fitted in a hollow hole of the ball stud, and is slidably fitted in the hollow hole of the ball stud. A parking brake wire connecting portion structure comprising a collar member that prohibits contact with the hole.

With the above configuration, when the parking is operated and released, the opening edge of the hollow hole of the ball stud interposed at the free end of the camshaft lever and the screw portion of the brake wire inserted into the hollow hole are provided. Are not directly in contact with each other, and the collar member externally fitted to the screw portion slides in contact with the opening edge of the hollow hole, so that damage to the screw portion is reliably prevented.

In the present invention, the collar member is coaxially arranged on the brake wire and is engaged with the screw portion to lock a return spring for urging the brake wire in a brake releasing direction. Preferably, it is formed integrally with the nut. According to this configuration, in order to lock one end of the return spring provided for returning the brake wire to the brake release position, the collar member is integrally formed with the lock nut screwed into the screw portion. Thus, the number of parts can be reduced, and the labor required for assembling the collar member can be omitted.

Further, in the present invention, the elastic member compressed between the ball stud and the engaging member screwed to the threaded portion of the brake wire in accordance with a tensile force applied to the brake wire. It is preferable that a switch device that is closed when a compression amount of the elastic member exceeds a set value is supported on the ball stud while a member is interposed. With this configuration, the pulling force of the brake wire can be directly detected at the connection with the camshaft lever closest to the parking brake, which affects the friction loss of the brake wire on the way from the brake lever to the parking brake. The switch device can be operated without being operated, and as a result, a necessary braking force can be reliably generated.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS. (Note that FIG.
In addition, members that are substantially the same as or correspond to those of the conventional structure shown in FIG. 6 are denoted by the same reference numerals, and redundant description is omitted. According to the present invention, one end of the return spring 72 that is screwed to the screw portion 38 of the brake wire 36 and cooperates with the nut 68 to constantly elastically urge the brake wire 36 in the brake release direction is locked. As shown in FIG. 2, a hollow tubular collar member 76 is integrally formed with the lock nut 70.

The collar member 76 has an end remote from the lock nut 70 slidably fitted in the hollow hole 48 of the ball stud 44 as shown in FIG. The depth of insertion of the collar member 76 into the hollow hole 48 is such that the brake wire 36 is pulled downward from the brake release state shown in FIG. In a state where the sensor spring 56 is compressed and the switch device 62 is closed, in other words, in an operating state in which the center brake or the parking brake 10 is generating a required braking force, the tip of the collar member 76 is still ball stud. 44 hollow holes 48
It is set to the size that it is sufficiently inserted in.

Accordingly, the hand brake lever in the cab is operated to apply a required pulling force to the brake wire 36, so that the return spring 72 and the sensor spring 56
When the camshaft lever 26 is rotated and the parking brake 10 is actuated, the collar member 76 abuts the opening edge of the hollow hole 48 of the ball stud 44 on the camshaft lever side. Since the screw 38 does not contact the opening edge of the hollow hole, damage to the screw portion 38 is reliably prevented, and the reliability and durability are improved.

The collar member 76 is hardened,
It is preferable that a tempering heat treatment is performed so as to have a surface hardness substantially equal to that of the ball stud 44, thereby ensuring the durability of the collar member 76 itself. Furthermore, it is desirable to apply zinc plating or chrome plating to the outer peripheral surface of the collar member 76 mainly from the viewpoint of rust prevention.

In the preferred embodiment of the present invention, the collar member 76 is used to lock the lock nut 7 of the spring retainer 66 that supports one end of the return spring 72 that urges the brake wire 36 in the brake release direction.
However, the collar member 76 is formed separately from the lock nut 70, and is screwed or fitted to the screw portion 38 of the brake wire 36 and fixed by any fixing means, for example, caulking or the like. You may. Further, in the above embodiment, the sensor spring 56 composed of a coil spring is employed as a brake auto sensor for operating the switch device 62 by detecting a pulling force applied to the brake wire 36 when the brake is operated. Obviously, an elastic member such as a plate spring, a disc spring, or rubber can be appropriately used instead of the coil spring.

[0025]

As described above, the wire connection structure of the parking brake according to the present invention includes a camshaft lever connected to a camshaft for operating a brake shoe of a drum brake and driving the same. A ball stud interposed at a free end of the camshaft lever and having a hollow hole, a screw portion formed at one end inserted into the hollow hole of the ball stud and screwed to the screw portion; A brake wire that transmits a rotational force to the camshaft lever via a ball stud; and a brake wire that is externally fitted to a screw portion of the brake wire and slidably fitted in a hollow hole of the ball stud. And a collar member for inhibiting contact with the hollow hole of the ball stud. Damage threaded portion formed on the coupling portion can be reliably prevented that, there is an advantage capable of improving the reliability and durability.

In the present invention, the collar member is screwed to the screw portion to lock a return spring disposed coaxially with the brake wire and biasing the brake wire in a brake releasing direction. By being formed integrally with the lock nut, there is an advantage that the number of parts can be reduced, the labor required for assembling the collar member to the brake wire thread portion can be omitted, and the manufacturing cost can be reduced.

Further, in the present invention, an elastic member compressed between the ball stud and the engaging member screwed to the threaded portion of the brake wire in accordance with a tensile force applied to the brake wire. It is preferable that a switch device that is closed when the amount of compression of the elastic member exceeds a set value is supported on the ball stud, and with this configuration, a position closest to the parking brake is provided. Thus, the switch device can be operated by detecting the pulling force of the brake wire, so that the necessary braking force can be reliably generated, which is beneficial for safety.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a preferred embodiment of the present invention.

FIG. 2 is a side view of a lock nut 70 integrally formed with a collar member 76 of FIG.

FIG. 3 is a front view showing a structure of a brake wire connecting portion in a conventional parking brake.

FIG. 4 is a schematic configuration diagram showing an internal structure of the parking brake shown in FIG.

FIG. 5 is a partial side view as viewed in the direction of arrow V in FIG. 3 (however, the switch device 62 is removed and shown).

FIG. 6 is a cross-sectional view of a main part of the parking brake shown in FIG. 3, showing a connecting portion between the cam shaft lever 26 and the brake wire 36 when the brake is operated.

[Explanation of symbols]

10 ... Center brake (parking brake), 11 ...
Support plate, 12 ... Cover, 14 ... Brake shoe, 16 ... Cam shaft, 18 ... Cam, 26 ... Cam shaft lever, 30 ... Hand brake bracket, 32 ...
Brake cable, 36 ... Brake wire, 38 ... Screw, 44 ... Ball stud, 48 ... Hole of ball stud, 50 ... Spring cage, 56 ... Brake F auto sensor spring, 58 and 60 ... Nut and lock nut (locking) 62) Switch device, 66 ... Spring retainer, 70 ... Lock nut, 72 ... Return spring, 76 ... Collar member.

Claims (3)

[Claims] 1. A camshaft lever connected to a camshaft for driving a brake shoe of a drum brake and driving the camshaft; and a ball stud provided at a free end of the camshaft lever and having a hollow hole. And a brake wire that transmits a rotational force to the camshaft lever through the locking member and the ball stud, wherein the threaded portion formed at one end is inserted into the hollow hole of the ball stud and screwed into the threaded portion and the ball stud. A collar member which is fitted externally to the threaded portion of the brake wire and slidably fitted in the hollow hole of the ball stud, and prohibits contact between the threaded portion and the ball stud hollow hole. A parking brake wire connection structure. 2. A lock nut threadedly engaged with the screw portion for locking a return spring disposed coaxially with the brake wire and biasing the brake wire in a brake releasing direction. The wire connecting portion structure for a parking brake according to claim 1, wherein the wire connecting portion structure is formed in a uniform manner. 3. An elastic member, which is compressed according to a tensile force applied to the brake wire, is interposed between the ball stud and the engaging member screwed to the thread portion of the brake wire. 3. A wire for a parking brake according to claim 1, wherein said ball stud supports a switch device which is closed when a compression amount of said elastic member exceeds a set value. Connection part structure.