JPH0694579A - Roller drive type brake tester - Google Patents

Abstract

PURPOSE:To simply measure a friction coefficient by measuring change quantities of oil pressure of a brake and a rotating speed of a roller and calculating the friction coefficient therefrom. CONSTITUTION:A tire 6 of a wheel of a test car is mounted on a roller 4, a motor 1 is started and the tire 6 is rotated. When a rotating shaft 3 reaches a predetermined speed, the power source of the motor 1 is shut off and a braking device within the tire 6 is actuated. At this time rotational speed of the roller 4 is measured with a tachometer 7 on a shaft end of the shaft 3 and in addition, oil pressure for actuating a cylinder within the braking device is measured with an oil sensor 8. Signals measured with the tachmeter 7 and the sensor 8 are input to an operation device 9 at regular intervals. The operation device 9 serves to find a change of the rotational speed between n-th and (n+1)-th times and an average value of the oil pressure and calculate a friction coefficient therefrom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction tester for a brake lining generally used in automobiles.

[0002]

2. Description of the Related Art Friction materials for automobiles are required to have stable friction characteristics such as friction coefficient and wear. These characteristics are
Constant speed friction tester such as JIS D 4411, J
It was measured by a brake dynamometer like ASOC 406. Among them, the roller type brake tester is a roller drive type brake tester in which one wheel of a vehicle is placed on a roller, as shown in an automobile technology handbook, and the roller for rotating a tire of the vehicle and the moment of inertia of the vehicle. It is composed of a rotary shaft composed of an inertial disc having a rotor and a motor for driving the rotary shaft, and is generally used for a noise test of an automobile.

[0003]

In order to measure the friction coefficient with the conventional roller type brake tester, a wheel torque meter is attached to the wheels of the vehicle, and the friction coefficient is calculated by the braking torque obtained by the wheel torque meter and the hydraulic pressure. It was calculated. However, since the wheel torque meter is made according to the tire size of the vehicle, a wheel torque meter had to be made for each vehicle of a different model.

[0004]

SUMMARY OF THE INVENTION The present invention provides a roller type brake tester for measuring a friction coefficient without measuring a braking torque with a wheel torque meter or the like. The present invention relates to a roller that rotates a tire of a vehicle, a rotary shaft composed of an inertial disk having a moment of inertia of the vehicle, a motor that drives the rotary shaft, a tachometer that measures the rotation of the roller, and a hydraulic pressure that measures the hydraulic pressure of a brake. A sensor is a roller drive type brake tester having at least an arithmetic unit for performing measurement processing of the sensors, wherein the arithmetic unit is an apparatus for calculating a friction coefficient from a hydraulic pressure of the brake and a change amount of the rotational speed of the roller. To do.

A roller type brake tester of the present invention is shown in FIG. Reference numeral 1 is a driving motor, which is connected to a rotating shaft 3 by a belt 2. The rotating shaft 3 has a roller 4 and an inertial disk 5
Is stuck. One tire 6 of the test vehicle is placed on the roller 4, and the tire 6 rotates in accordance with the rotation of the roller 4. When the motor 1 is started and the rotating shaft 3 reaches a specified rotation speed, the power of the motor 1 is cut off and the tire 6
A brake test is performed by operating the internal braking device 7. A tachometer 7 is fixedly attached to the shaft end of the rotating shaft 3, and the number of rotations of the roller is measured. The hydraulic pressure for operating the cylinder inside the brake device 7 is measured by the hydraulic pressure sensor 8. There are some tachometers that use a photoelectric or magnetoelectric pulse generator, and either one may be used, but it is not of a type that generates at least 60 or more pulses each time the rotary shaft makes one revolution. Therefore, the rotational speed cannot be accurately measured, and the friction coefficient cannot be accurately obtained.

Each measured value is input as a voltage value into the analog-digital converter of the arithmetic unit, and the arithmetic unit 9
Calculate the friction coefficient at. The friction coefficient is calculated by the following procedure. The signals of the tachometer 7 and the hydraulic sensor 8 are input to the arithmetic unit 9 at regular intervals. Input n of the number of rotations to R _n ,
The hydraulic pressure input is P _n , the n + 1th rotation speed input is R _{n + 1} ,
The hydraulic pressure input is P _{n + 1} . First, the amount of change in the rotational speeds P _n and P _{n + 1} is obtained. The value obtained by dividing this value by the signal acquisition time interval is the tire deceleration. The product of this value and the moment of inertia of the rotary shaft 3 is the braking torque of the brake. On the other hand, the pressing force of the brake is obtained by multiplying the average value of the hydraulic pressures P _n and P _{n + 1} by the cylinder area of the brake device. The friction coefficient is a value obtained by dividing the braking torque by the pressing force. A personal computer may be used as the arithmetic unit 9 for these cases. The friction coefficient can be obtained with the above structure.

[0007]

In the roller drive type brake tester having the above structure, since the braking torque is measured by detecting the change in the number of revolutions, it is not necessary to install the wheel torque meter according to the tire and measure the braking torque. . As a result, the friction coefficient can be easily calculated from the measured values of the tachometer and the hydraulic sensor.

[0008]

EXAMPLE A roller type brake tester of an example will be described below with reference to FIG. 1 is a driving motor,
A KW DC motor was used. The motor 1 is connected to the rotating shaft 3 and the belt 2. The roller 4 is attached to the rotary shaft 3.
And the inertial disk 5 is fixed. At this time, the moment of inertia of the rotating shaft was set to 45 kgm ² according to the model vehicle. One tire 6 of the test vehicle was placed on the roller 4, and the tire 6 was rotated according to the rotation of the roller 4. Motor 1
When the rotating shaft 3 reaches the specified rotation speed,
The power of the motor 1 was cut off, and the brake device 7 inside the tire 6 was operated to perform a brake test. In addition, the test brake pad in the brake device 7 has a JASO C
As shown at 427, a K thermocouple was embedded and a brake test was conducted at a constant sliding temperature. A rotation meter 7 was fixed to the shaft end of the rotation shaft 3, and the number of rotations of the roller was measured. The tachometer used a photoelectric pulse generator, and the pulse signal was converted into a voltage value by an FV converter. A strain gauge type pressure transducer was used for the hydraulic pressure sensor of the cylinder inside the brake device 7.

Each measured value is input as a voltage value of 0 to 10 V into the analog-digital converter of the arithmetic unit,
The friction coefficient was calculated by the arithmetic unit 9. The signals of the tachometer 7 and the oil pressure sensor 8 were input to the arithmetic unit at intervals of 0.1 seconds, and the tire deceleration was obtained from the difference in the number of revolutions taken in the nth time and the (n + 1) th time. This value was multiplied by the moment of inertia of the rotary shaft 3 to obtain the braking torque of the brake. On the other hand, the nth time and n +
The average value of the hydraulic pressure taken in the first time was multiplied by the cylinder area of the brake device to obtain the pressing force of the brake. And
The friction coefficient was a value obtained by dividing the braking torque by the pressing force.
A personal computer was used for the arithmetic unit 9.
As a result, the friction coefficient of the brake was easily examined.

[0010]

As described above, according to the present invention, the friction coefficient of the brake lining can be easily measured without using a device for measuring the braking torque such as a wheel or a torque meter, which is economical. In addition, the friction characteristics can be investigated quickly.

[Brief description of drawings]

FIG. 1 is a front view of a roller brake tester according to the present invention.

[Explanation of symbols]

 1 Motor 2 Belt 3 Rotating Shaft 4 Roller 5 Inertial Disk 6 Tire 7 Tachometer 8 Oil Pressure Sensor 9 Computing Device

Claims (1)

[Claims] 1. A roller-driving brake tester on which one wheel of a vehicle is mounted, the roller rotating a tire of the vehicle, a rotary shaft composed of an inertial disk having a moment of inertia of the vehicle, and a motor driving the rotary shaft. Also, in a roller drive type brake tester having at least a tachometer for measuring the rotation of the roller, an oil pressure sensor for measuring the oil pressure of the brake, and an operation device for performing those measurement processes, the operation device calculates the oil pressure of the brake and the rotation speed of the roller. A roller drive type brake tester, which is a device for calculating a friction coefficient from a change amount.