JPH06288872A - Evaluation method of braking vibration - Google Patents

Abstract

PURPOSE:To evaluate a braking vibration extremely simply by a method wherein a braking device and a vibration accelererometer are provided, a functional evaluation point is found from a correlative diagram between the braking vibration and the functional evaluation point and a vibration state is evaluated. CONSTITUTION:A braking device 10 is installed on a dynamo. A vibration accelerometer 5 is attached to the device 10, its output (which has converted an accelerating waveform into a voltage) is input 6, the magnitude of a vibration at this time is operated by an FET high-speed Fourier transform operation, and an operated value is stored 8. When the magnitude of a braking vibration in various states is obtained in this manner, to which functional evaluation point the magnitude of the braking vibration corresponds is found from a graph obtained on the basis of an actual vehicle. The functional evaluation point which has been found and the occurrence frequency of the functional evaluation point are plotted on the graph. When all the points are situated inside a slant, the braking device is judged to be suitable for the vehicle of this type. In addition, since various components for the braking device can be replaced simply, the braking device which is optimun for a specific type of vehicle can be evaluated simply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides an objective evaluation of vehicle low frequency squeal (so-called brake squeal).
The present invention relates to a brake vibration evaluation method capable of taking effective measures against a low frequency squeal phenomenon.

[0002]

2. Description of the Related Art Conventionally, brake squeal is high-frequency squeal (called squeal, 1000 Hz to tens of KHz) to low-frequency squeal (slow frequency, called Hz).
It is known that there are various squeaking phenomena. Among such brake squeal phenomenon, there is a low frequency squeal in which the rotor cooling fin emits a sound of a frequency matching the frequency of passing through the pad every second. An example thereof is shown in FIG. 10 as a three-dimensional display of frequency-time-sound pressure level. The frequency of this brake squeal almost coincides with the frequency at which the fins pass through the pad every second. Therefore, when the brake is applied and the speed decreases, the frequency of the brake squeal also decreases. The frequency of this low frequency squeal can be expressed by the following equation.

[0003]

[Equation 1] f: Squeal frequency (Hz) V: Vehicle speed (km / h) D: Tire diameter (m) n: Number of rotor fins That is, the vibration source of the brake squeal is when the pad and the rotor rub. This is because the vibration indicated by the above equation is generated, but in a dynamo where an experiment is performed with the brake alone, such vibration of the brake device cannot be heard as sound. The reason for this is that in an actual vehicle, the vibration generated by the brake is transmitted to the vehicle body, and the vehicle body having a large area serves as a sounding body to generate sound, whereas there is no vehicle body that resonates on the dynamo. Fig. 11 shows the vibration of the pad when this brake squeal occurs.
Shown in. As is clear from the figure, it is clear that one vibration is generated for each fin.

By the way, it has been recognized that the brake squeal as described above does not make a sound on a dynamo from the past (it was conventionally considered that the brake squeal only occurs in an actual vehicle), so let's reproduce the brake squeal. In that case, it was necessary to rely on the actual vehicle test, and therefore, a great deal of man-hours were required for the experiment for clarifying the brake squeal.
For example, all conditions such as weather, temperature, and humidity on the day of the experiment affect the braking device, making it difficult to repeat the experiment under certain conditions. It was extremely difficult to evaluate the brake squeal by installing a pickup or replacing various parts of the brake system.

[0005]

From the background described above, the present inventors have proceeded with the development of a brake vibration evaluation method that can obtain the same result as the experimental result of the brake device equipped in the actual vehicle even in the laboratory. As a result, when attaching the vibration accelerometer to the braking device installed on the dynamo, inputting the output from the vibration accelerometer (converting the acceleration waveform into voltage) to the amplifier at the time of braking, listening to the loudness speaker, We have found that a sound with a tone color equivalent to the low-frequency squeal that occurs in an actual vehicle can be reproduced. Further examination of this vibration has revealed that the frequency holds in the above equation. Fig. 8 shows a three-dimensional display of frequency-time-vibration acceleration of vibration generated by a dynamo.
Fig. 9 shows how one vibration per piece occurs. From this, the braking device generates vibration that is the source of sound on the dynamo, but there is no vehicle body that plays the role of the sounding body, and the correlation between the above vibration magnitude and the squeal generated in the actual vehicle Therefore, it was found that this kind of squeal can be evaluated even with a dynamo because of the magnitude of this vibration. Further, the correlation between the brake vibration of a certain specific vehicle model and a certain type of braking device and the sensory evaluation point is that substantially the same correlation is established even when the braking device is replaced with another type of braking device, and It has also been confirmed that a similar correlation is established for each brake component. The present invention has been made on the basis of such new knowledge, and since the brake vibration can be evaluated extremely easily by this brake vibration evaluation method, it is very effective in developing a new brake device.

[0006]

Therefore, according to the present invention, a vibration accelerometer is attached to a braking device arranged on a dynamo, and the magnitude of vibration of the braking device during braking is determined by the vibration accelerometer, and the vibration is measured in advance. Using the correlation diagram between the magnitude of the vibration of the brake device during the braking operation and the sensory evaluation point obtained by using the, the sensory evaluation point corresponding to the magnitude of the vibration is obtained, and from the obtained evaluation point This is characterized in that the vibration state of the brake device is evaluated, and this is used as means for solving the problem.

[0007]

The brake vibration measuring device is attached to the brake device of a vehicle of a specific vehicle type (for example, an A type car), and the brake vibration generated during braking is measured while the actual vehicle is running. That is, the magnitude of the vibration when the brake vibration is generated is measured by the FFT based on the signal from the vibration accelerometer 5, and the vibration acceleration at that time is obtained. At the same time, a human determines a sensory evaluation point for the brake vibration at that time. In this way, while the actual vehicle is running, the brake vibrations and sensory evaluation points of the A-type vehicle and a certain type of braking device are measured, and the correlation between them is graphed as shown in FIG.
At the same time, FIG. 3 shows the relationship between the sensory evaluation points and the frequency of brake vibration, which is a reference when evaluating the brake device.
As shown in the graph, an objective evaluation of the braking device is obtained by checking whether or not the braking device to be tested falls within the shaded area in FIG.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of an experimental device for evaluating brake vibration according to the present invention. In FIG. 1, reference numeral 10 is a brake device, and the brake device 10 is installed on a vehicle body or a dynamo (not shown). The brake device is composed of a caliper 1, a pad 2, a support 3, a rotor 4, etc., and a vibration accelerometer 5 is provided at an appropriate portion of the brake device (the caliper in this embodiment, but it may be another portion). It is installed. FF is connected to the vibration accelerometer 5 via the charge amplifier 6.
T7 is connected. The FFT is an abbreviation for Fast Fourier Transform, which mathematically processes a signal waveform observed in the time domain and transforms it into the frequency domain (August 1991, monthly tribology, pages 71-74). reference). The FFT measures the magnitude of the highest vibration of the signals output from the vibration acceleration 5, and the result is stored in the data recorder 8.

A method for evaluating brake vibration in the experimental apparatus having the above-mentioned structure will be described below. This evaluation evaluates which type of brake device should be attached to a specific vehicle type. First, a brake vibration measuring device having the same configuration as described above is attached to a brake device of a vehicle of a specific vehicle type (for example, model A vehicle), and the brake vibration generated during braking is measured while the actual vehicle is running. That is, the magnitude of the vibration when the brake vibration is generated is measured by the FFT based on the signal from the vibration accelerometer 5, and the vibration acceleration at that time is obtained. At the same time, a human determines a sensory evaluation point for the brake vibration at that time. In this way, the brake vibrations and sensory evaluation points of the type A vehicle and a certain type of brake device are measured while the actual vehicle is running, and the correlation between them is graphed as shown in FIG. In this graph, the vertical axis represents acceleration based on the magnitude of vibration, and the horizontal axis represents sensory evaluation points. At the same time,
The relationship between the sensory evaluation points and the frequency of brake vibration, which is a reference when evaluating the brake device, is graphed, and it is determined whether the brake device under test falls within the shaded area in FIG. 3, for example. Be prepared so that an objective evaluation of the braking system can be obtained. The correlation diagram shown in FIG. 2 has a certain width, for example, a relational diagram (a in the figure) between the vibration acceleration of the brake device most suitable for the actual vehicle and the sensory evaluation point, and the non-brake device that is the least suitable for the actual vehicle. It may be set as having a width based on the relational diagram (b in the figure) between the vibration acceleration and the sensory evaluation point.

After collecting data of a state in which a certain type of braking device is attached to a certain vehicle type as described above, the laboratory determines the braking device for this vehicle type based on this data. Evaluation of various braking devices is performed as follows. In addition, the correlation between the brake vibration and the sensory evaluation point of a certain type of vehicle and a certain type of braking device is substantially the same even when the braking device is replaced with another type of braking device, and It has been confirmed by experiments that a similar correlation is established for each brake component. First, as shown in FIG. 1, a braking device is installed on the dynamo. A vibration accelerometer is attached to this brake device, and its output (acceleration waveform converted to voltage) is input to an amplifier, and FF
At T, the magnitude of vibration at that time is calculated, and this value is stored in the data recorder. When the magnitudes of the brake vibrations in various states are obtained in this way, which sensory evaluation point the magnitude of the brake vibrations corresponds to is obtained from the graph FIG. 2 obtained based on the actual vehicle.

The sensory evaluation points thus obtained and the frequency of occurrence of the sensory evaluation points are further plotted on the graph of FIG. 3. If all these points fall within the shaded area of FIG. Judge that it is suitable for the vehicle type. It should be noted that the shaded area in FIG. 3 is merely an example, and may be in another range. In this way, it is possible to easily determine, in the laboratory, a braking device suitable for a specific model vehicle from among various braking devices. In addition, this method uses the weather and temperature. Since the reproducibility is high regardless of humidity and the like, and various parts of the brake device can be easily replaced, the optimum brake device for a specific vehicle type can be easily evaluated.

The results of sensory evaluation of brake vibration of the present invention will be shown below. 4 and 5 show the relationship between the low-frequency squeal and the sensory evaluation points in the actual vehicle of the caliper of the brake device and the support. FIG. 4 is an example of the correlation between the vibration of the caliper and the sensory evaluation point, and FIG. 5 is an example of the correlation between the vibration of the support and the sensory evaluation point. In addition to this, the correlation coefficient of any brake portion (part) such as the correlation between the vibration of the pad and the sensory evaluation point is 0.
Over 84, it was found that a sensory evaluation of low frequency squeaking could be substituted. Also, it is desirable to attach a vibration accelerometer to the pad when evaluating the low-frequency squeal of the pad, but it is necessary to attach the vibration accelerometer to the next pad again when evaluating the next pad after the experiment is completed. Since it takes time and effort, it may be attached to another suitable place.

FIGS. 6 and 7 show the results of the actual evaluation of the brake pads and the results of the dynamo evaluation. Both results are almost the same, and the dynamo should be used when evaluating the vibration of the brake device pads. Is possible. In addition, since the present invention enables automatic driving and automatic evaluation by a computer, it takes about 1 week (7
The evaluation of the brake vibration can be shortened to 3 days, and the evaluation of the brake vibration can be evaluated numerically from sensory, so-called objective evaluation, so that the evaluation accuracy is also improved.

[0014]

As described in detail above, according to the present invention, it is possible to easily determine, in a laboratory, a braking device suitable for a specific type vehicle from among various braking devices. In addition, this method uses the weather and temperature. Since the reproducibility is high regardless of humidity and the like, and various parts of the brake device can be easily replaced, the optimum brake device for a specific vehicle type can be easily evaluated. It has excellent effects such as.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an experimental device for evaluating brake vibration according to the present invention.

FIG. 2 is a correlation diagram between accelerations that generate brake vibrations and sensory evaluation points corresponding to the accelerations.

FIG. 3 is a relationship diagram between a frequency of occurrence of brake vibration and a sensory evaluation point.

FIG. 4 is a diagram illustrating a relationship between a low-frequency squeal and a sensory evaluation point of a caliper of a brake device in an actual vehicle.

FIG. 5 is a diagram in which a relationship between a low-frequency squeal and a sensory evaluation point in an actual vehicle supporting a brake device is obtained.

FIG. 6 is a diagram showing an evaluation result of an actual vehicle test of a brake pad.

FIG. 7 is a diagram showing an evaluation result of a dynamo test of a brake pad.

FIG. 8 is a three-dimensional view of frequency-time-vibration acceleration of vibration generated by a dynamo.

[Figure 9] 1 per fin on the dynamo
It is a figure showing how a number of vibrations occur.

FIG. 10 is a diagram showing a state in which the cooling fins of the rotor exhibit low-frequency squeal that emits a sound of a frequency that matches the frequency of passing through the pad every second.

FIG. 11 is a diagram showing vibration of a pad when brake squeal occurs.

[Explanation of symbols]

 1 caliper 2 pad 3 support 4 rotor 5 vibration accelerometer 6 charge amplifier 7 FFT 8 data recorder (computer)

Claims (2)

[Claims] 1. A vibration accelerometer is attached to a brake device arranged on a dynamo, the magnitude of vibration of the brake device during braking is determined by the vibration accelerometer, and the magnitude of vibration of the brake device is experimentally obtained in advance using an actual vehicle. The sensory evaluation point corresponding to the magnitude of the vibration is obtained from the correlation diagram between the magnitude of the vibration of the brake device during the operation of the brake and the sensory evaluation point, and the vibration state of the brake device is evaluated from the obtained evaluation point. A brake vibration evaluation method characterized in that 2. The vibration state of the brake device is evaluated by
2. The brake vibration evaluation method according to claim 1, wherein the combination of various parts of the brake device is changed or is performed for each brake part.