JPS58131438A - Abrasion loss detector for brake lining - Google Patents

Abstract

PURPOSE:To detect abrasion loss ever so accurately, by calculating the value of output stroke of an actuator on a basis of the detected value of a feed of pressurized fluid for the actuator, while finding the abrasion loss out of the calculated value. CONSTITUTION:When a brake pedal 8 is stepped on, a brake valve 5 is opened and thereby compressed air inside a tank 3 is fed to the within of an air cylinder 7 whereby a piston 9 is rendered going to the right. Accordingly, a cam 12 is rotated clockwise around a shaft 13 via a rod 10 and lever 11 while a brake shoe 14 gets expanded via a roller 15 and braking force is therefore produced. At this time, pressure variation inside the air tank 3 is detected by a sensor 19 and also a state of pressure inside the air cylinder 7 is detected by a pressure sensor 20 in the same manner respectively, inputting these output values into a microcomputer 22, and the travel of the piston 9 is thus calculated. Then, abrasion loss 11 is found out of this calculated value, and when it arrives at more than the desired abrasion loss, a lamp 26 and a buzzer 28 give the alarm.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for detecting the amount of wear on a brake lining in a brake mechanism that supplies pressurized fluid to an actuator and moves a brake shoe to perform braking using the output stroke of the actuator.

A brake mechanism for an automobile is configured to press the lining of a brake shoe onto a drum or the like, thereby braking the vehicle. If this brake lining is worn beyond its usable limit, not only will the braking force be significantly reduced, but it will also cause damage to the drum and brake shoes. Conventionally, brake linings were inspected for wear after a certain distance or period of time, and replaced if necessary. Therefore, there is a drawback in that in order to determine the amount of wear on the brake lining, it is necessary to carry out regular periodic inspections.

However, as the brake lining gradually wears out,
The gap between the surface of the lining and the braking surface of the drum gradually increases, and the stroke of the actuator for operating the brake increases accordingly. That is, the stroke of the actuator has a correlation with the amount of wear on the brake lining. Therefore, it is considered to provide this actuator J with means for directly detecting the stroke of the actuator. However, since the actuator is installed closer to the wheel than the car's chassis spring, it is subject to direct vibration from the road surface.
It has been difficult to directly electrically detect the exit stroke of the actuator.

In view of these problems, the present invention provides a brake lining wear amount detection device in which a detection means for determining the output stroke of an actuator that moves a brake shoe can be added to a part that is not directly exposed to vibration. The purpose is to

The present invention will be described below with reference to an illustrated embodiment.

FIG. 1 shows an embodiment in which the present invention is applied to an air brake for an automobile, and the device of this embodiment is equipped with a compressor 1 driven by an engine. Air compressed by the compressor 1 is supplied to an air tank 3 via a vibrator 2 and stored there. Air in the air tank 3 is supplied to the air cylinder 7 via a pipe 4, a brake valve 5, and a vibro. The brake valve 5 is configured to be opened and closed by a brake pedal 8.

Rod 1 fixed to piston 9 of air cylinder 7
0 is connected to lever 1]. The base end of this lever 11 is fixed to a shaft 13 which is fixed to an S-shaped cam 12. The cam 12 is in contact with rollers 15 respectively attached to a pair of brake shoes 14. Further, the pair of brake shoes 14 are rotatably supported by fixing pins 16 on the opposite side from the rollers 15, respectively. A brake lining 17 is attached to the outer surface of the brake shoe 14 and can come into contact with the inner surface of the brake drum 18.

Pressure sensors 1 and 2 are provided on the right side of the air tank 3 and the vibro, respectively, and the pressure in the tank 3 and the pressure in the air cylinder 7 are detected by these sensors 19 and the pressure. The sensor 9 is located closer to the chassis than the chassis spring, and is buffered by the chassis spring so that it does not receive direct vibration from the road surface. Furthermore, the compressor is provided with a rotation speed detection sensor 21 for detecting its rotation speed. The detection outputs of these sensors 9, 20, and 21 are supplied to the microcombi user n. The microcomputer η is for calculating and determining the output stroke of the air cylinder 7 based on the detection signal, and stores the capacity of the tank 3, the effective cross-sectional area of the air cylinder 7, and the like.

The output side of this microcomputer η is connected via a drive circuit Z3.24%δ to a warning lamp, a warning buzzer, and a warning lamp path. The lamp path and buzzer M are configured to issue an alarm when the amount of wear on the lining 17 reaches a usage limit, and the ramp path is configured to issue an alarm if there is an abnormality in the pressurized air supply system. It has become.

In the above configuration, when the pedal 8 is depressed to brake the vehicle, the brake valve 5 opens and the tank 3
The compressed air inside is supplied into the air cylinder 7. Therefore, the piston 9 moves to the right in FIG. This movement is caused by the cam 1 via the rod 10, lever 11 and shaft 13.
2, and the cam 12 rotates clockwise about the shaft 13 in FIG. Therefore, the brake shoe 14 is rotated by the cam 12 via the rollers 15, and the lining 17 on the surface of the shoe 14 is pressed against the inner peripheral surface of the drum 18.

This creates a frictional force between the lining 17 and the drum 18, resulting in a braking action.

The amount of movement of the piston 9 within the air cylinder 7 during this braking operation is proportional to the distance of the gap between the surface of the brake lining 17 and the surface of the drum 18. Therefore, by keeping the initial gap between the lining 17 and the drum 18 to a certain value, it becomes possible to determine the amount of wear on the brake lining 17 from the amount of movement of the piston 9, that is, the output stroke of the air cylinder 7. The output stroke of the air cylinder 7 is determined by the amount of air supplied into the cylinder 7 when the brake valve 5 is opened.

Therefore, the sensor 19 detects the change in pressure inside the tank 3 as information for determining the amount of air sent from the air tank 3.
This detection output is given to the microcomputer B as input information.

Also, since air is a compressible fluid, the pressure inside the air cylinder 7 is detected by a pressure sensor (a),
This detection output is also given to the microcomputer ρ as input information. Furthermore, when the compressor 1 is rotating, compressed air is being filled into the air tank 3 from moment to moment, so the amount of air filling from the compressor 1 to the tank 3 is also input to the computer B by the sensor 21. I try to give it as a signal. Since the constants necessary for calculating the capacity of the tank 3, the effective cross-sectional area of the cylinder 7, etc. are stored in advance in the computer B, the constants necessary for calculating the capacity of the tank 3, the effective cross-sectional area of the cylinder 7, etc. are stored in advance. , the microcomputer ρ calculates the amount of movement of the piston 9 from the amount and pressure of air supplied into the air cylinder 7. Then, the amount of wear of the lining 17 is determined from this calculated value.

If the wear amount of the lining 17 determined by the microcomputer 4 exceeds the usage limit, the microcomputer ρ outputs an output signal for the rotation circuit. Then, these drive circuits 23 and 24 cause the lamp and buzzer n to issue an alarm. This allows the driver to minimize wear on the lining 17. Note that the movement stroke of the piston 9 or the brake shoe 14 determined by the microcomputer η may be displayed using a display device. Furthermore, the output of the rotation speed detection sensor 21 of the compressor l is input to this microcomputer η, and based on this value and the detection output of the sensor 19, it is possible to judge whether there is any abnormality in the air supply system of the air brake. It is supposed to be done. If the microcomputer determines that there is an abnormality, it sends signals to the drive circuits 5 and 5, respectively. As a result, the buzzer and the lamp will alert you to the above-mentioned abnormality.

As described above, according to this embodiment, there is no need to stop the vehicle, remove some parts, and check the amount of wear on the brake lining 17 through periodic inspection. Further, the brake lining 17 can be used up to its maximum usage limit. That is, there is no need to replace the lining 17 early in consideration of the amount of wear until the next inspection, and the brake lining 17 can be saved. Also, in Figure 1, point l
The part on the right side of lI29 is provided on the wheel side with respect to the chassis spring, and the left side is provided on the chassis side. Therefore, since the sensors 19, 21 are both located on the compressed air supply source side and above the chassis spring, they are not directly affected by vibrations from the road surface.

Therefore, damage and malfunction of the sensors 19, 20, and 21 are reduced, reliability is improved, and the wear amount of the brake lining can be detected accurately.

Next, a modification of the above embodiment will be explained with reference to FIG. In this modification, the air cylinder 7 is not directly controlled by opening and closing the brake valve 5, but the relay valve is controlled by the brake valve 5. Therefore, the relay valve (9) is connected between the air tank 3 and the vibrator 4, which supplies compressed air to the air cylinder 7. The rest of the structure is the same as that of the above embodiment. The pressure of the air tank 3 and the air cylinder 7 is detected by the sensor 14.2+1, and based on this, the amount of wear of the lining 17 is determined by the microcomputer η. . Therefore, this modification also provides the same effects as the above embodiment.

Although the present invention has been described above with reference to embodiments and modified examples, the present invention is not limited to these embodiments and modified examples, and various changes can be made based on the technical idea of the present invention. For example, in the above embodiment, an air cylinder is used as the actuator, but the present invention is also applicable to an air brake using an air booster. Furthermore, the present invention is also applicable to oil brakes. In the case of oil brakes, since oil is incompressible,
It is only necessary to know the inflow amount of oil supplied to the oil cylinder, and the configuration is simpler than the above embodiment. Furthermore, in the above embodiment, the output stroke of the actuator is calculated by a microcomputer, but since this calculation is relatively simple, it may be replaced with a normal electronic circuit using an operational amplifier or the like. It is possible.

As described above, according to the present invention, the amount of MI wear on the brake lining is determined by calculation from the amount of pressurized fluid supplied to the brake actuator, so the amount of MI wear on the brake lining can be determined directly. There is no need to check the amount of wear.

In addition, since the sensor is located on the pressurized fluid supply source side, it can be placed above the chassis spring and is not affected by vibrations from the road surface, improving reliability and providing accurate The amount of wear can be detected.

[Brief explanation of the drawing]

In addition, in the symbols used in the drawings, 7... Air cylinder 14... Brake shoe 17...
. . . Brake lining 19, pressure sensor ρ . . . Microcomputer. Applicant Hino Motors Co., Ltd.

Claims (1)

[Claims] Detection means for detecting the amount of pressurized fluid supplied to the actuator by supplying pressurized fluid to the actuator and moving a brake shoe to perform braking according to the output stroke of the actuator. is provided on the supply source side of the pressurized fluid, and includes a calculation means for calculating the output stroke of the actuator based on the detection output of the detection means, and supplies the detection output of the detection means to the calculation means to perform the above-mentioned operation. 1. A brake lining wear amount detection device, characterized in that the output stroke value of one actuator is calculated, and the wear amount of the brake lining is determined from this calculated value.