JPH0210370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a squeal measuring device for disc brake pads (hereinafter referred to as disc pads).

<Prior Art> Disc brakes have excellent stability during high-speed braking, but disc pad materials are now required to have an extremely high performance level compared to conventionally used friction materials. The main performance requirements for disc pad materials include a high and stable coefficient of friction (μ), low wear, low compressive deformation due to pedal stroke, and no squeal.

Measurement of friction coefficient and wear among friction characteristics
Constant speed friction tester such as JISD4411,
This could easily be done with a brake dynamometer such as JASOC406. However, the current method of measuring noise characteristics is mainly by driving an actual vehicle, but the disadvantages are that the noise characteristics differ depending on the type of car being used, and that it takes a lot of effort and time to measure a single disc pad. It was hot. Therefore, a simple measurement method has been proposed that uses the brake mechanism, wheels, tires, and suspension mechanisms to perform braking operations (Noise Dynamometer: Chikamori: Research on Brake Squeal: Mitsubishi Heavy Industries Technical Report Vol. 14, No. 5). However, it had the same drawbacks as the actual vehicle. In order to perform product inspection of disc pads and develop materials and manufacturing methods for disc pads, it is necessary to quickly and quantitatively understand the noise characteristics of the disc pads themselves. It has become a key point in testing and the development of high-performance disk pads.

<Problem to be solved by the invention> The squeal of a disc brake is caused by frictional vibration (self-excited vibration) between the disc pad and the disc, which excites the disc, the caliper, and the suspension mechanism, which have a high natural frequency, and is amplified by resonance. It is thought that this action causes air compression waves, resulting in the squeaking noise. Therefore, brake squeal can be divided into issues such as frictional vibration between the pad surface and disc surface, and issues such as the stiffness, damping performance, and natural frequency of the pad material, disc, and caliper suspension mechanism.

The present invention relates to a device for independently measuring the former problem, and provides a device that can quantitatively measure the squeal characteristics related to the friction surface of a disk pad in a short period of time.

<Means for Solving the Problems> The present inventors have discovered that the squeal (key sound) generated at the friction surface between the disc pad and the disc can be quantitatively understood by measuring the amplitude of the friction vibration of the disc pad. We have discovered what is possible and have arrived at the present invention.

That is, the disc brake pad squeal measuring device of the present invention includes a disc that is rotatably driven by power, and is disposed opposite to one side of the disc, and is rotatable coaxially with the rotation axis of the disc, but does not measure the rotation of the disc. A sample mounting jig made of a pad material that is held by a spring member that can be biased in a braking direction and that can be pressed against a disk surface, and a vibration detection means that detects the amplitude of frictional vibrations generated in the jig. It is characterized by the following:

Hereinafter, the present invention will be explained in detail with reference to the drawings showing embodiments.

FIG. 1 shows a perspective view of a disc brake pad squeal measuring device according to the present invention, in which a gray cast iron disc 3 is rotatably mounted on a chuck 1 of a rotary lathe. Reference numeral 7 denotes a measurement sample mounting jig, which is disposed facing the surface of the disk 3 and is connected and fixed to a shaft 8 coaxial with the rotation axis of the disk 3. Shaft 8
is supported by a slide bearing,
The sample mounting jig 7 can be rotated around the rotation axis of the disk 3, and can also be moved along the rotation axis. The other end of the shaft 8 is pressed by a piston of an air cylinder 31 via a load cell 9.
Further, a steel ball 10 is provided between the air cylinder piston and the sample mounting jig 7 so that the sample mounting jig 7 can rotate even when pressed. Reference numeral 11 is an arm fixed to the shaft 8, and its tip end is connected to the rod cell 16 and the ball joint 1 as shown in FIG.
The coil spring 12 is attached to the bolt 14 attached to the
12'. coil spring 12,
12' is the sample 5 attached to the sample attachment jig 7;
Jig 7 due to sliding friction between 5' and the surface of disk 3.
Brake the rotation.

Further, 17 is a vibration detector (acceleration pickup) for measuring the amplitude of frictional vibration.

It is observed that the disk pad vibrates through friction when the squeal is actually occurring, and the squeaking of the disk pad and frictional vibration can be considered to be physically the same phenomenon. Moreover, the magnitude of the squeal strength can be measured as the magnitude of the amplitude of frictional vibration.

As the rotatable disk in the measuring device of the present invention, it is desirable to use the same disk as is used in an actual brake, or to use a disk made of the same material. Although it is desirable that the disc rotational speed can be changed smoothly from the maximum disc rotational speed in an actual vehicle to a standstill, the purpose can be achieved even if the rotational speed can be changed in stages.

Samples used for testing are full size (20cm ² - 200cm ² )
However, in order to reduce the required horsepower of the test machine power, 1 cm ² to 20 cm ² may be used. Basically, a pair of samples should be arranged symmetrically on the disk diameter so that the center of the sample is approximately on the same diameter of the disk.
Several pairs of samples may be arranged symmetrically on the same diameter so that no force that would tilt the disk is applied. The sample mounting jig can be rotated coaxially with the rotation axis of the disk, and if it is structured so that it can move smoothly along the axis, measurements can be made regardless of sample wear. In addition, the sample mounting jig and sample are attached using screws or adhesive so that there is no looseness. As a method of braking the rotation of the sample mounting jig via a panel, a spring may be attached directly to the jig, or an arm may be protruded from the rotating surface of the jig and fixed via a spring. . Suitable springs include torsion springs, leaf springs, coil springs, and spiral springs. When frictional torque is applied, vibration measurement becomes easier if the amount of deformation of the spring is greater than the total amount of deformation of the sample, sample mounting jig, arm, etc. The frequency of friction vibration is from 1Hz to 100
It is most preferable to set it to around Hz.

The vibration measurement location may be any suitable location such as the sample, sample mounting jig, or the unfixed end or arm of a spring.Measurement methods include acceleration measurement using an acceleration pick-up and vibration displacement measurement using an optical device. However, it is most desirable to use an acceleration pickup, especially a piezo type, since acceleration and velocity displacement can be determined electrically.

Using such a measuring device, attach a full-size disk pad or a sample cut out to reduce the friction area, and measure the disk rotation speed at a surface pressure in the range of 0.1 Kg/cm ² to 50 Kg/cm ² to the maximum rotation speed of the actual vehicle (100 rpm). When the vibration is measured by slowly changing the rotation speed from ~2000 rpm) to rest, or from rest to the maximum rotation speed, frictional vibrations occur within a certain rotation speed range. Disc pads that tend to squeal generate large vibrations over a wide range of rotational speeds, but pads that do not squeal have a narrower range of frictional vibrations or smaller vibrations.

The level of magnitude at which this frictional vibration occurs can be selected within a range that is easy to measure by selecting the spring constant and appropriately selecting the damping due to the viscosity and friction of the part that contacts the sample mounting jig. can. It is also possible to measure frictional vibrations over a wide range by installing a damper such as an oil damper in parallel with the spring to saturate the frictional vibrations that tend to diverge to an appropriate level.

The disk may be heated by frictional heat or may be heated and controlled by something such as an electric heater. Furthermore, since the occurrence of frictional vibrations is often affected by the thermal history of the sample, more accurate results can be obtained by appropriately determining the test codes for heating and cooling.

<Operation> By pressing a jig with a pad sample attached onto the surface of the rotating disk 3 with a predetermined pressure, frictional torque is generated between the disk and the pad material. This friction torque is applied to the arm 11 attached to the shaft 8.
and is guided to the load cell 16 by coil springs 12, 12'.

The electrical signal from the piezo type acceleration pickup 17 attached to the arm 11 is sent to the charge amplifier 1.
8 and a detector 19, and is input to the Y axis of an XY recorder 20 as an amplitude.

The rotational speed of the disk 3 is determined by detecting the striped pattern on the chuck 1 as a pulse using the phototransistor probe 21, and converting it through the F-V converter 22 into XY.
It is input to the X axis of the recorder 20. The XY recorder 20 can draw an amplitude-per-rotation curve of frictional vibration.

On the other hand, the pressing force signal from the load cell 9 and the friction force signal from the load cell 16 are transmitted to the amplifier 2.
3 and 24 and the arithmetic circuit 25 as a friction coefficient signal to the Y axis of the XY recorder 26, and the pressing force and friction force at that time are recorded. The temperature of the disk was measured without contact with an infrared thermometer 27.
A temperature setting relay 28 and a timer 29 are used to control the temperature of the disk surface.

FIG. 3 shows the measurement results using the apparatus shown in the drawing. Figure 3 shows pressing pressure 15Kg/cm ² and take temperature
In the graph showing the measurement results at 100°C, a shows a disk pad of good quality that does not make noise when running on an actual vehicle and has no complaints in the market, and b shows a disk pad that makes noise when running on an actual vehicle and has many complaints about squeaking in the market.
It can be seen that the good disk pad does not cause any frictional vibration, but the defective disk pad causes frictional vibration with a maximum amplitude of 1.8 mm between 40 rpm and 200 rpm.

There was a correlation between the amplitude of frictional vibration measured by the device of the present invention, actual vehicle running, and market complaints.

<Effects of the Invention> As is clear from the above description, the present invention has made it possible to quantitatively grasp the disk pad squealing phenomenon in a short period of time.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the disk brake pad squeal measuring device of the present invention, and FIG. 2 is a partial view showing how a sample mounting jig is fixed via a spring. FIGS. 3a and 3b show graphs of measurement results by the testing apparatus of the present invention, and a shows a non-defective disk pad. Explanation of symbols, 1...chuck, 2...disk, 3...disc, 4...bolt, 5,5'...sample, 6,6'...
Plate, 7...sample mounting jig, 8...shaft,
9...Load cell, 10...Steel ball, 11...
Arm, 12, 12'...Coil spring, 13, 1
3'...Coil pressure plate, 14...Bolt, 1
5...Ball joint, 16...Load cell, 17
...Acceleration pickup, 18...Charge amplifier,
19...Detector, 20...XY recorder, 21...Phototransistor probe, 22...F-V converter, 23...Amplifier, 24...Amplifier, 25...Arithmetic circuit, 26...XY recorder, 27...Infrared thermometer, 28...Temperature Setting relay, 29...Timer, 30
... Solenoid valve, 31 ... Air cylinder, 3
2...Air regulator.

Claims (1)

[Claims] 1 A disk that is rotationally driven by power, and a spring member that is disposed opposite to one side of the disk and that is rotatable coaxially with the rotational axis of the disk but that is biased in a direction that brakes the rotation of the disk. What is claimed is: 1. An apparatus for measuring pad squeal for a disc brake, comprising: a sample mounting jig for a pad material that can be pressed against a disc surface; and means for measuring the amplitude of frictional vibration generated in the jig.