JPH0135072Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an internally expanding drum brake for a vehicle equipped with a parking brake.

[Conventional technology]

In conventional general vehicle drum brakes equipped with a parking brake, one end of the leading and trailing brake shoe, which is slidably supported on the back plate, is supported by an anchor, and the other end, which is the rotating side, is supported by an anchor. The proximal end of a parking brake lever, which is pulled by a parking cable, is pivotally supported near the other end of one brake shoe, in contact with pistons protruding from both ends of the wheel cylinder.

In addition, this parking brake mechanism has been improved,
As a technology for even more reliable operation,
There is one shown in Publication No. 18247.

In this technology, a generally fan-shaped pulley that changes the direction of the parking cable is rotatably supported in a back plate, and a cylindrical engagement member is placed approximately in the center of a groove formed along the outer periphery to prevent it from separating. Attach it with the parts, wrap the parking cable in the groove, and
It is inserted into the engaging member to prevent the parking cable from slipping off from the pulley.

[Problem that the invention attempts to solve]

However, in the latter case, the pulley that rotates when the parking cable is pulled acts as a resistance force to change direction, so a stronger pulling force is required.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a drum brake for a vehicle in which the direction of the parking cable can be easily changed and the lever traction force can be reduced.

[Means for solving problems]

This invention was made in view of the above-mentioned purpose,
Parking of a drum brake for a vehicle in which a pair of brake shoes are supported on a back plate so as to be expandable, and the base end of a parking brake lever towed by a parking cable is pivotally supported at the rotating end of one brake shoe. In the device, a movable pulley is pivotally supported at the tip of the parking brake lever, and a fixed pulley is pivotally supported near the parking cable insertion hole inside the back plate, and the parking cable inserted into the back plate from the insertion hole is inserted into both sides. It is characterized in that it is wound around a pulley and its tip is locked to the back plate side.

[Effect]

By configuring as described above, the parking wire can be easily routed, and the direction change and lever pulling force can be reduced.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

The drum brake 1 has a pair of brake shoes 5 and 6 that are supported by shoe hold down pins 3 and 4 on the left and right inner surfaces of a back plate 2 that is fixed to the vehicle body. Show 5, 6
The lower ends of the webs 5a, 6a are supported by anchors 7, and the upper ends on the rotation side are brought into contact with pistons 9, 9 protruding from both sides of the wheel cylinder 8, and the brake shoes 5, 6 are , a return spring 10 stretched between the lower ends of both webs 5a, 6a, and return springs 12, 13 that are locked to an automatic adjustment device 11 located at the bottom of the wheel cylinder 8, so that the brake is constantly reduced. biased in the direction.

Near the upper end of one brake shoe 6, a base end 15a of a parking brake lever 15 pulled by a parking cable 14 is pivotally supported by a support shaft 16.

A movable pulley 1 is provided on the back plate 2 side of the rotating end 15b of the parking brake lever 15, with a guide groove 17a having an arcuate cross section recessed in the outer periphery.
7 is pivotally supported by a support shaft 18 parallel to the lever 15, and an insertion hole 1 bored in the back plate 2.
A fixed pulley 20 is erected near the lever 15 side of the lever 9 by means of a bracket 21 and a support shaft 22, with its outer peripheral surface facing toward the movable pulley 17 of the lever 15.

A guide groove 20a is formed on the outer peripheral surface of the fixed pulley 20 in the same way as the movable pulley 17, and the parking cable 14 inserted into the back plate 2 through the insertion hole 19 is inserted into each guide groove 20a, 17a of the pulleys 20, 17. They are wound one after another, and their tips 14a are locked to locking protrusions 7a protruding from the top of the anchor 7.

Further, both the pulleys 17 and 20 are the pulley 1
The parking cable 14 between 7 and 20 is on the same plane as the guide groove 20a of the fixed pulley 20, and each parking cable 14 between the pulleys 17 and 20 and between the locking protrusion 7a and the pulley 17 The guide groove 17a is disposed so as to be flush with the guide groove 17a.

When the operating lever is operated from the driver's seat of the vehicle, the parking cable 14 is pulled, and the brake lever 15 is rotated via both pulleys 17 and 20, thereby opening both brake shoes 5,
The linings 5b and 6b of No. 6 are brought into sliding contact with the inner circumferential surface of the brake drum to perform a braking action.

As explained above, in this embodiment, movable and fixed pulleys are used as the means for changing the direction of the parking cable 14, and the rolling of the pulleys 17 and 20 can reduce frictional resistance and allow smooth operation. , and the pulling direction of the parking cable 14,
Since the guide grooves 17a and 20a of both pulleys 17 and 20 are made to coincide with each other, there is no loss due to unbalanced load during direction change, and the traction force can be used effectively, and the parking cable 14 can be detached from the guide grooves 17a and 20a. can be reliably prevented.

Further, since the movable pulley 17 provided on the parking brake lever 15 becomes a movable pulley, the traction force can be halved and the operating effectiveness of the parking brake lever 15 can be improved.

[Effect of idea]

As explained above, the parking device for a vehicle drum brake according to the present invention has a parking brake lever towed by a parking cable at one rotating end of the brake shoe that is expandably supported on the back plate. A movable pulley is pivotally supported at the tip of the parking brake lever, and a fixed pulley is pivotally supported near the parking cable insertion hole inside the back plate, and the parking cable is inserted into the back plate from the insertion hole. Since the cable is wound around both pulleys and its ends are locked on the back plate side, the direction of the parking cable can be changed by rolling the pulleys, making it easy to handle and reducing frictional resistance. Therefore, the braking operation can be performed smoothly.

In addition, since the movable pulley installed on the parking brake lever becomes a movable pulley, the traction force is only about half that of the conventional one, improving the operating effectiveness of the parking brake lever and providing even more reliable braking force. can.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a front view of a drum brake, and Fig. 2 is a cross-sectional view taken from the side of Fig. 1. 1... Drum brake, 2... Back plate, 5, 6... Brake shoe, 5a, 6a...
Web, 5b, 6b... lining, 7... anchor, 7a... locking protrusion, 8... wheel cylinder, 9... piston, 14... parking cable, 14a... tip, 15... parking brake lever, 15a...base end, 15b...rotating side tip, 17...movable pulley, 20...fixed pulley,
17a, 20a...Guide groove, 19...Insertion hole.

Claims (1)

[Scope of utility model registration request] Parking of a drum brake for a vehicle in which a pair of brake shoes are supported on a back plate so as to be expandable, and the base end of a parking brake lever towed by a parking cable is pivotally supported at the rotating end of one brake shoe. In the device, a movable pulley is pivotally supported at the tip of the parking brake lever, and a fixed pulley is pivotally supported near the parking cable insertion hole inside the back plate, and the parking cable inserted into the back plate from the insertion hole is inserted into both sides. A parking device for a drum brake for a vehicle, characterized in that it is wound around a pulley and its tip is locked on a back plate side.