JPH06294710A - Vibration measuring method for vehicle - Google Patents

Abstract

PURPOSE:To highly accurately evaluate the vibration by detecting the vibration around a steering wheel when four wheels rotate individually, evaluating the phase and the vibration of each wheel through frequency analysis, matching the phases of four wheels through regulation, detecting a maximum vibration and comparing with a reference value. CONSTITUTION:Motors 9a-9d rotate rollers 7a-7b through belts 8a-8d and the acceleration being applied to a steering 3 and the rotational phases of tires 1a-1d are measured based on the outputs from sensors 2a-2d and 4. Order ratio analysis is then conducted for each tire 1a-1d thus evaluating the vibration value of each wheel. Subsequently, the motors 9a-9d are controlled to match the phases of all wheels and then the acceleration of the steering 3 is measured. The acceleration is multiplied by a vehicle correction factor and compared with a vibration reference value. When the reference value is not exceeded, OK is indicated and the residual unbalance of each wheel is evaluated together with the previously measured vibration value of each wheel. When the reference value is exceeded, NG is indicated thus evaluating the vibration of car body highly accurately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle vibration measuring method, and more particularly to a method capable of measuring so-called shimmy with high accuracy.

[0002]

2. Description of the Related Art In an automobile, when there is an imbalance in the rotating part where tires and wheels are assembled,
Steering wheel vibration (shimmy) or vehicle sideways vibration may occur. This is a phenomenon that automobiles have never experienced.

Therefore, as a conventional method of measuring the vibration of such a vehicle, there is a method of measuring the vibration around the steering wheel (shimmy) using a shimmy meter in a stationary traveling test as shown in FIG. In this method, as shown in the same figure, first, a rotation sensor 2 is attached to one tire 1 of a vehicle, and an acceleration sensor 4 is attached to a steering wheel 3, and the vehicle travels in this state. Each output is input to the shimmy meter 5, only the rotational primary component of the vibration of the steering wheel 3 is extracted, and it is output to the XY recorder 6 for evaluation.

Here, the order ratio analysis used in the above vehicle vibration measurement will be briefly described. In frequency analysis, 1 Hz is a component that completes one cycle per second.
On the other hand, the first-order rotation in the order-ratio analysis is a component that completes one cycle for one rotation of the reference rotating body. The rotation secondary is a component that completes two cycles for one rotation, and is twice the rotation primary. FIG. 5 (A) is a conceptual diagram showing sampling on a time pulse basis in frequency analysis. From this figure, it can be seen that in this case, the number of samples per revolution changes depending on the number of revolutions. On the other hand, FIG. 5B is a conceptual diagram showing sampling on the basis of the rotation pulse in the order ratio analysis. From this figure, in this case, sampling is performed n times per rotation even if the rotation speed changes. It is understood that (n is an integer). in this way,
In order ratio analysis, if the vibration component is normalized as the order,
This makes it easier to focus on a certain component without being affected by the rotation fluctuation.

[0005]

However, in such a conventional vibration measuring method, first, the rotation sensor 2 is attached to only one tire 1 and the rotation pulse is taken in only from this one wheel. It is not possible to determine how much vibration is caused by which tire. Therefore, it is impossible to estimate the cause of the vibration.

Further, in the conventional method, due to the shimmy cycle due to the phase change (rotation) of the tire, the evaluation cannot be performed in a short time, there is no reproducibility, and accurate data is obtained even in actual driving. There is a problem that I can not take it. This point will be explained in more detail below.

The vibration generated in the vehicle due to the tire failure changes depending on the tire phase of the four wheels. Here, only two wheels are considered for the sake of clarity. Fig. 6 shows the rotational vibration (L) (R) of the left and right tires and their combined vibration.
(CV) is a graph showing the case where the phase of each wheel is different by 30 degrees, and the figure (B) is a case where the phase of each wheel is different by 60 degrees. As shown in the figure, even for tires with the same defect level, the combined vibration level changes due to the change in the rotational phase of the left and right wheels. Therefore, in order to perform highly accurate measurement, it is necessary to change the phase difference between the left and right wheels from 0 degree to 180 degrees. In actual driving, cornering is done to deal with it. Further, when the vibration level generated from each tire is 1, the combined vibration level at the phase difference of each wheel is as shown in FIG. As shown in the figure, the synthetic vibration, that is, the malfunction becomes maximum when the phase difference is 0 degree, and therefore, it is necessary to evaluate the vehicle vibration at this point. However, conventionally, this phase matching has been extremely difficult even in actual traveling, and it has been impossible to evaluate the vehicle vibration with high accuracy in the bench evaluation in which cornering cannot be performed in the first place.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a vehicle vibration measuring method capable of performing vehicle vibration evaluation in a stationary traveling test with extremely high accuracy. To do.

[0009]

The present invention for achieving the above object is a method for measuring vibrations around a steering wheel caused by rotation of a tire in a stationary running test, wherein four wheels are different from each other. Rotate at the number of rotations, detect the vibration around the steering wheel at that time, perform frequency analysis, adjust the phase and vibration of each wheel, and adjust the phase to match the phase of all four wheels. And a step of detecting a maximum value of vibration and comparing it with a reference value of vibration.

[0010]

In the present invention having such a process, since the phase / vibration evaluation of all the wheels and the vibration evaluation by the phase control of all the wheels are performed, the quantitative evaluation of the vibration defect caused by the tire in the stationary running test is performed. Therefore, the vehicle body vibration can be evaluated with high accuracy (reproducibility).

[0011]

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 plan view showing a device configuration for carrying out a vehicle vibration measuring method according to the present invention, FIG. 2 is a schematic side view of the device shown in FIG. 1, and FIG. 3 is a flowchart showing a measuring procedure according to the embodiment. 1 and 2, the same parts as those in FIG. 4 are designated by the same reference numerals.

The stationary running tester shown in FIGS. 1 and 2 is a device for measuring the vibration of the vehicle, especially the shimmy around the steering wheel. In this device, four rollers 7a-d for rotating each tire 1a-d are independently driven by electric motors 9a-d via belts 8a-d, respectively, and four tires 1a-d of the vehicle are also provided. Signals from the rotation sensors 2a to 2d respectively attached to the steering wheel 3 and the acceleration sensor 4 attached to the steering wheel 3 are input to the computer 10 to be calculated. A vehicle type table is stored in advance in the computer 10, and various types of processing are executed based on the input data.
In this embodiment, the computer 10 uses, for example, vibration frequency analysis, order ratio analysis / rpm tracking analysis, 4
Rotation control of each roller 7 of each wheel, tire phase measurement of each wheel, tire phase matching control, input acceptance control of vehicle type information from host and keyboard, development of vehicle type table, retrieval of vehicle type table, measurement of vibration data / rotation data , The process of displaying the measurement status is performed.

Next, before explaining an application example of the vehicle vibration measuring method according to the present embodiment, an order ratio analysis and an rpm tracking analysis used in the present embodiment, and an outline of a vibration measuring procedure by the above-mentioned device for realizing the order analysis. Will be briefly explained.

First, the order ratio analysis is a method of analyzing the vibration at the number of revolutions as a reference as described above. For example, when the tire is rotating at 20 Hz, one vibration per revolution (for example, the tire) is performed. Vibration due to unbalance of
If this occurs, the frequency of this vibration will be 20 Hz. Thus, in the state where all vibration frequencies exist, such as when the vehicle is traveling, it is possible to detect the vibration due to a specific cause by analyzing the vibration component based on the rotation reference of the vibration system. Especially in the case of tires, the primary component of tire rotation (one vibration per rotation)
Is due to the imbalance of the tire, and the n-th order component of the tire rotation is due to the non-uniformity (RFV) of the tire surface. Therefore, since the cause of vibration can be estimated by performing such order ratio analysis, this embodiment uses this order ratio analysis when performing cause analysis for an NG vehicle.

In the rpm tracking analysis whose concept is shown in FIG. 8, in contrast to the above-mentioned order ratio analysis in which measurement is performed by focusing on a certain fixed number of rotations, attention is paid to vibration of a certain order and a change in the number of rotations is performed. This is a method of determining at which rotation speed (speed) the vibration reaches its maximum level by measuring the change in the vibration level, and in this embodiment, the rotation speed at which the vibration level of each order becomes maximum. It is used to detect (speed), reproduce the most prominent NG phenomenon, and make a quantitative judgment.

Then, vibration measurement is performed by the above-mentioned apparatus using such order ratio analysis / rpm tracking analysis. It consists of vibration evaluation and high-precision vibration measurement by phase adjustment of all wheels.

First, an outline of all-wheel independent phase / vibration evaluation at the time of measuring vibration caused by tire rotation will be described. In this embodiment, as described above, tire rotation of four wheels can be controlled independently. When evaluating the vibration due to the tire unbalance of the wheels, the tire rotational speed of each wheel is, for example, the front wheel right tire 1a = 20 Hz, the front wheel left tire 1b = 25 Hz,
Rear right tire 1c = 30Hz, rear left tire 1d = 35Hz
Then, by performing a frequency analysis of the vibration component at this time, it is possible to easily evaluate that the vibration level at, for example, 20 Hz is due to the imbalance of the front right tire 1a, and the imbalance occurs. The phase (position on the tire) can also be easily detected. This point was found in conventional running tests and stationary running tests where it was difficult to evaluate how much the vibration components of each wheel contributed to the overall vibration because the rotation speed of each wheel was almost the same. There is no feature.

Further, in the case of highly accurate vibration measurement by adjusting the phase of all wheels, when trying to evaluate OK / NG of vibration, even if the vehicle has the same defect level due to the phase change, the vibration of the tire will be affected by the phase of the tire. Since the level changes (see Fig. 6), it is not possible to make a quantitative evaluation in either actual driving or stationary driving tests. Therefore, using the tire independent rotation mechanism as in this embodiment, the roller 7 is rotated so as to match the tire phase of each wheel, and all four wheels have a phase of 0 degrees, that is, the vibration level is the highest. Produces
Perform a quantitative evaluation.

In determining OK / NG of vibration, since the OK / NG level of vibration is different depending on the vehicle type, vehicle type, etc., the determination value G, which is a vibration reference value, is previously set for each vehicle type.
₀ (f) is set and entered in the vehicle type table of the microcomputer 10. Then, the vehicle type table is searched by inputting the vehicle type information, the determination value G ₀ (f) is taken out, and the measurement after setting is started. The determination is made individually for each vibration frequency f.

The outline of the vibration measuring procedure by the above apparatus having the above contents is as follows. First, the electric motor 9a-
Each of the rollers 7a to 7d is rotated at a slightly different rotation speed by d, and each of the four wheels is rotated at a different rotation speed. Then, the steering wheel vibration at this time is taken in from the acceleration sensor 4 and the order ratio analysis is performed (see FIG. 8 (A)).
For each of a to d, it is detected how much vibration is occurring and in which phase the maximum value of vibration is present (
See FIG. 8 (B) and (C)). Then computer 1
The electric motors 9a to 9d are controlled by 0, and the rotation speed is controlled so that the phases of all the wheels match. Then, the maximum vibration value at this time is detected, and the vibration is determined. At the same time, how much residual unbalance each wheel has is evaluated by the magnitude and phase of the vibration of each wheel. Here, the residual unbalance is the unbalance that remains even if a mass weight is installed on the wheel to correct it when the tire is unbalanced, and usually the measurement accuracy is poor. This residual imbalance cannot be completely eliminated due to improper installation of weights or weights.

The phase adjustment of all wheels is performed in the above procedure because, as described above, the actually measured synthetic vibration greatly changes due to the different rotational phases of the tires 1a to 1d. This is because it is necessary to evaluate the phase of all wheels in the sense of taking. Maximum vibration is generated by matching the phases.

Therefore, as an application example of the vehicle vibration measuring method according to the present embodiment, the procedure of the vibration measurement by the apparatus shown in FIGS. 1 and 2 is carried out according to the flow chart of FIG.

First, as a preparation for measurement, after the vehicle 11 is entered, the rotation sensors 2a to 2d are installed on the four tires 1a to 1d of the vehicle 11, respectively, and the acceleration sensor 4 is installed on the steering 3 (S1). . Then, the vehicle type information is input to the computer 10 (S2), the vehicle type table is searched (S3), and the vibration reference value G ₀ (f) is set (S).
4).

Then, the belt 8 is driven by the electric motors 9a to 9d.
Each roller 7a-d is rotated via a-d to rotate each wheel (S5), the values from the respective sensors 2a-d, 4 are taken in, and the acceleration applied to the steering wheel 3 and each tire 1a-d are acquired.
The rotational phase of each is measured (S6). As described above, the rotation speed of each wheel is different at this stage, and the order ratio analysis is performed for each tire 1a to 1d to determine how much vibration is occurring and what phase the vibration is. The vibration value of each wheel, such as whether the maximum value exists, is evaluated.

Then, it is judged whether or not the phases of all the wheels are aligned (S7), and if the phases of all the wheels are aligned as a result of this determination, immediately proceed to the next step 9, but otherwise, If the phases of the rings are different,
Control for matching the phases of the wheels is performed by the electric motors 9a to 9d. That is, the electric motors 9a to 9d are controlled to control the number of revolutions so that the phases of all the wheels match (S8). At this time, since all the wheels are in phase, the combined vibration becomes maximum.

Then, the acceleration P of the steering wheel 3 is measured (S9) and G _P (f) is calculated (S10). This G
The calculation of _P (f) is performed by the following equation G _P (f) = P × A. Here, P is the measured acceleration and A is the vehicle correction coefficient. Then, G _P (f) is set to the vibration reference value G ₀ (f)
Then, the vibration value is judged whether or not it exceeds the reference value (S11). If it is confirmed as a result of this determination that the reference value is not exceeded, a message indicating OK is displayed (S12), and further, according to the magnitude and phase of the vibration of each wheel measured in step 6, each wheel is Evaluate how much residual unbalance you have (S1
3). On the other hand, if the result of determination in step 11 exceeds the reference value, it is displayed that the vibration is above the reference value and is NG (S14). These results are output from a printer (not shown). (S1
5).

When the above measurement is completed, the sensors 2a to d, 4 attached to the vehicle 11 are removed and the vehicle 11 is exited (S16).

Therefore, according to this embodiment, all four tires 1a to 1d can be independently rotated,
Since all wheels independent phase / vibration measurement evaluation and all-wheel phase control are performed, it is possible to quantitatively evaluate vibration problems due to tires, which was extremely difficult in actual driving and stationary driving tests, and vehicle body vibration. The evaluation can be performed with high accuracy (reproducibility).

Also, so-called tire-on-the-car imbalance can be evaluated. That is, at present, the tire balance correction is performed in a state before the tire is attached to the vehicle (off-the-car), but even if the residual unbalance is completely set to 0 and the tire is attached to the vehicle in the off-the-car state, the tire of the axle is The unbalance may remain in the vehicle state due to the accuracy of the mounting portion and the residual unbalance of the disc plate and the drive shaft. This unbalance of the vehicle state is called tire-on-the-car unbalance, and in the present embodiment, such tire-on-the-car unbalance can be evaluated.

Further, according to this embodiment, the stationary evaluation can be performed with higher accuracy than the actual traveling test, and the actual traveling man-hour can be eliminated.

[0031]

As described above, according to the present invention, the four wheels can be independently rotated so that all-wheel independent phase / vibration measurement evaluation and all-wheel phase control are performed. In the above, it becomes possible to quantitatively evaluate the vibration defect caused by the tire, and the vehicle body vibration evaluation can be performed with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an apparatus configuration for carrying out a vehicle vibration measuring method according to the present invention.

2 is a schematic side view of the device of FIG.

FIG. 3 is a flowchart showing a measurement procedure according to the embodiment.

FIG. 4 is a diagram showing a device configuration for implementing a conventional vehicle vibration measuring method.

FIG. 5 is a diagram for explaining the concept of order ratio analysis.

FIG. 6 is a diagram showing rotational vibrations of two wheels and their combined vibrations.

FIG. 7 is a diagram showing a relationship between a phase difference between two wheels and a combined vibration level.

FIG. 8 is a diagram for explaining the concept of rpm tracking analysis used in the example.

[Explanation of symbols]

 1 ... Tire 2 ... Rotation sensor 3 ... Steering 4 ... Acceleration sensor 7 ... Roller 8 ... Belt 9 ... Electric motor 10 ... Computer

Claims (1)

[Claims] 1. A method for measuring vibrations around a steering wheel due to rotation of a tire in a stationary running test, wherein four wheels are rotated at different rotational speeds and vibrations around the steering wheel at that time are detected. Performing frequency analysis and performing phase / vibration evaluation for each wheel and phase adjustment to match the phase of all four wheels, detect the maximum value of vibration at this time and compare with the reference value of vibration A method for measuring vehicle vibration, comprising: