JP2795066B2 - Hydraulic drum brake - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drum brake used for a vehicle or the like.

[0002]

2. Description of the Related Art In conventional hydraulic drum brakes for trucks and the like, the wear of the brake shoe lining has been visually checked to see if it has reached its limit. This may cause inadequate wear checks, etc., leading to a decrease in brake performance or, in extreme cases, breakage of the brakes, which may cause a great danger especially when traveling on a truck or the like on which a heavy object is mounted. Was.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to automatically detect when wear of a lining of a brake shoe reaches a limit in a hydraulic drum brake.

[0004]

SUMMARY OF THE INVENTION Therefore, a hydraulic drum brake according to the present invention has a brake shoe.
Non-contact type wear detection that is installed between the wheel cylinder side end and the wheel cylinder and that operates according to the displacement of the brake shoe when the brake is not activated when the wear of the lining of the brake shoe reaches near its limit. And a warning device connected to the wear detecting unit, and the warning device is configured to be activated by the operation of the wear detecting unit.

[0005]

Therefore, when the wear of the lining of the brake shoe reaches near the limit, the non-contact type wear detector operates in accordance with the displacement of the brake shoe when the brake is not operated, and is connected to the wear detector. The alarm device can automatically and immediately warn that the wear of the brake shoe lining has reached a dangerous area.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention shown in the drawings will be specifically described below. In an air-over hydraulic drum brake for a truck or the like, a piston 2 in a wheel cylinder 1 opens a brake shoe 4 via a push rod 3 by a brake fluid pressure, and presses a lining 5 of the brake shoe 4 against a brake drum (not shown). When the brake is not operated, the clearance between the brake drum and the lining 5 is adjusted to be constant when the brake is not operated.

On the other hand, a conductor 8 connected to a harness 7 is mounted on a thin plate-shaped non-magnetic body 6 fixed to an end of the wheel cylinder 1, and a harness 9 is connected on the conductor 8. A magnetic body 10 is attached with an insulator 11 interposed therebetween. Both harnesses 7 and 9 are connected to an alarm device 13 of an alarm buzzer and / or an alarm lamp installed in the cabin through a relay 12, and the relay 12 is turned on when the brake is operated. The circuit is shut off and a delay circuit for an appropriate time is built in.

The end 14 of the brake shoe 4
The permanent magnet 15 is fixed so as to separate the small gap from the non-magnetic material 6, and if the brake shoe 4 expands outward in accordance with the wear of the lining 5, the permanent magnet 15 moves substantially along the non-magnetic material 6. As described later, the non-contact type wear detecting section 16 is displaced together with the conductor 8, the magnetic body 10, and the like.
Is composed.

Therefore, when the lining 5 is greatly worn due to many braking operations and reaches near the wear limit, the permanent magnet 15 becomes large outwardly in accordance with the large outward expansion of the brake shoe 4 when the brake is not operated. As a result of the displacement, as shown by the two-dot chain line in FIG.
By elastically attracting the tip of the relay, the magnetic body 10 comes into contact with the electric conductor 8 and the electric circuit of the wear detecting section 16 is closed, so that the delay circuit in the relay 12 prevents the fluttering and the alarm device. By activating the motor 13, the occupant is warned that the lining 5 has reached a dangerous wear area, and appropriate measures can be taken promptly to ensure the running safety of the vehicle.

The magnet at the end of the brake shoe and its magnet
It is also possible to arrange the mounting point of the switch mechanism operated by the stone in the reverse of the above-described embodiment, and furthermore, the relay is operated even when the brake is operated, and the brake is applied when the lining wear approaches the limit. Each time the wear detecting section activates the alarm device to notify the advance of the wear of the lining in advance, the safety can be further improved.

[0011]

In the hydraulic drum brake according to the present invention, when the wear of the lining of the brake shoe reaches near its limit, the alarm device connected to the non-contact type wear detector detects the wear of the lining of the brake shoe. Can be automatically and instantaneously warned that the vehicle has reached the dangerous area, so that the reliability of the brakes can be enhanced and the safe traveling of the vehicle can be always ensured.

[Brief description of the drawings]

FIG. 1 is a schematic layout view of a main part in an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wheel cylinder 3 Push rod 4 Brake shoe 5 Lining 8 Conductor 10 Magnetic body 12 Relay 13 Alarm device 15 Permanent magnet 16 Wear detector

Claims (1)

(57) [Claims] 1. A corresponding to the displacement of the brake shoes during braking inoperative when wear of the installed in the brake shoe lining has reached near the limit between the brake shoe in the wheel cylinder side end portion and the wheel cylinder A hydraulic drum brake, comprising: a non-contact type wear detecting unit that operates by a manual operation; and an alarm device connected to the wear detecting unit, wherein the alarm device is configured to operate by operating the wear detecting unit.