JP3052655B2 - Vehicle vibration measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In a car, if there is an imbalance in a rotating part where a tire and a wheel are assembled, for example,
The steering wheel vibration (shimmy) and the lateral vibration of the vehicle body may occur. This is a phenomenon that cars have never experienced.

Therefore, as a conventional method of measuring the vibration of a vehicle, there is a method of measuring the vibration around the steering wheel (shimmy) using a shimmy meter in a stationary running test as shown in FIG. In this method, as shown in the 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 3, and the vehicle travels in this state. Each output is input to the shimmy meter 5 to extract only the primary rotation component of the vibration of the steering 3 and output it to the XY recorder 6 for evaluation.

Here, an order ratio analysis used in the above-described 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 of rotation in the order ratio analysis is a component that completes one cycle for one rotation of the reference rotating body. The secondary rotation is a component that completes two cycles for one rotation, and is twice as large as the primary rotation. FIG. 5A is a conceptual diagram showing sampling on the basis of a time pulse in frequency analysis. It can be seen from FIG. 5A that in this case, the number of samples per rotation changes depending on the number of rotations. 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 fluctuates. (N is an integer). in this way,
In order ratio analysis, if the vibration component is normalized as the order,
It is easy 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 one wheel. It cannot be determined how much vibration is caused by which tire. Therefore, it is impossible to estimate the cause of the vibration.

Further, in the conventional method, the evaluation cannot be performed in a short time due to the shimmy cycle caused by the phase change (rotation) of the tire. In addition, there is no reproducibility and accurate data can be obtained even in actual running. There is a problem that can not be taken. This will be described in more detail below.

[0007] Vibrations generated in the vehicle due to tire failures vary according to the tire phases of the four wheels. Here, only two wheels are considered to make the story easier to understand. Fig. 6 shows the rotational vibrations (L) and (R) of the left and right tires and their combined vibrations.
(A) shows the case where the phases of the respective wheels differ by 30 degrees, and FIG. 2 (B) shows the case where the phases of the respective wheels differ by 60 degrees. As shown in the figure, even if the tires have the same trouble level, the combined vibration level changes due to the change in the rotational phases 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 degrees to 180 degrees. In actual driving, cornering is performed. Assuming that the vibration level generated from each tire is 1, the composite vibration level at the phase difference of each wheel is as shown in FIG. As shown in the figure, the combined vibration, that is, the trouble, becomes maximum when the phase difference is 0 degree. Therefore, it is necessary to evaluate the vehicle vibration at this point. However, conventionally, this phase adjustment is extremely difficult even in actual running, and in the case of bench evaluation where cornering cannot be performed in the first place, it has been impossible to evaluate vehicle vibration with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a vehicle vibration measuring method capable of performing a vehicle vibration evaluation in a stationary running test with extremely high accuracy. I do.

[0009]

According to the present invention, there is provided a method for measuring vibration around a steering wheel caused by rotation of a tire in a stationary running test. Rotating at the number of revolutions, detecting vibration around the steering wheel at this time, performing frequency analysis, and detecting a phase indicating a position where the vibration is maximum for each wheel; And controlling the rotation speed of the four wheels to adjust the phase so that the phases match, detecting the maximum value of the vibration at this time, and comparing the detected value with the reference value of the vibration.

[0010]

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

[0011]

An embodiment of the present invention will be described below with reference to the 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, FIG. 2 is a schematic side view of the apparatus shown in FIG. 1, and FIG. 3 is a flowchart showing a measuring procedure according to the embodiment. 1 and 2 are denoted by the same reference numerals in common with FIG.

The stationary traveling tester shown in FIGS. 1 and 2 is an apparatus for measuring the vibration of a vehicle, particularly the shimmy around a steering wheel. In this device, four rollers 7a to 7d for rotating the respective tires 1a to 1d are independently driven by electric motors 9a to 9d via belts 8a to 8d, respectively. The signals from the rotation sensors 2a to 2d attached to the steering wheel 3 and the acceleration sensor 4 attached to the steering wheel 3 are input to the computer 10 and calculated. The computer 10 stores a vehicle type table in advance, and executes various processes based on input data.
In this embodiment, the computer 10 includes, for example, frequency analysis of vibration, order ratio analysis / rpm tracking analysis,
Rotation control of each roller 7 of the wheel, tire phase measurement of each wheel, tire phase matching control, input control of vehicle type information from the host and keyboard, development of vehicle type table, search of vehicle type table, measurement of vibration data and rotation data , And performs processing including display of the measurement status.

Next, before describing 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-described apparatus for realizing the same will be described. Will be briefly described.

First, the order ratio analysis is a method of analyzing vibration at a reference rotation speed as described above. For example, when a tire is rotating at 20 Hz, one vibration per rotation (for example, Vibration due to imbalance of
Appears, the frequency of this vibration is 20 Hz. Thus, in a state where all vibration frequencies are present, such as when the vehicle is running, it is possible to detect a vibration caused by a specific cause by analyzing the vibration component on the basis of the rotation of the vibration system that causes the vibration component. Especially in the case of tires, the primary component of tire rotation (one vibration per rotation)
Is caused by tire imbalance, and the n-order component of tire rotation is caused by poor tire surface non-uniformity (RFV). Therefore, the cause of the vibration can be estimated by performing such order analysis. In this embodiment, the order analysis is used when performing the cause analysis on the NG vehicle.

The rpm tracking analysis whose concept is shown in FIG. 8 is different from the above-described order ratio analysis in which measurement is performed by focusing on a certain rotation speed. This is a method of determining the rotation speed (speed) at which the vibration reaches the maximum level by measuring the change in the vibration level. In this embodiment, the rotation speed at which the vibration level of each order is the maximum is determined. (Speed) is detected, the most remarkable NG phenomenon is reproduced, and it is used to make a quantitative judgment.

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

First, the evaluation of the independent phase and vibration of all the wheels at the time of measuring the vibration caused by the rotation of the tires will be outlined. In this embodiment, the rotation of the tires of the four wheels can be controlled independently as described above. When evaluating the vibration due to the tire unbalance of the wheels, the tire rotation speed of each wheel is set to, for example, the front wheel right tire 1a = 20 Hz, the front wheel left tire 1b = 25 Hz,
Rear wheel right tire 1c = 30Hz, rear wheel left tire 1d = 35Hz
Then, by analyzing the frequency of the vibration component at this time, the vibration level at, for example, 20 Hz can be easily evaluated as being due to the imbalance of the front right tire 1a, and the imbalance has occurred. The phase (position on the tire) can also be easily detected. This point is based on the conventional actual running test and stationary running test, in which it was difficult to evaluate how much the vibration component of each wheel contributed to the overall vibration because the rotation speed of each wheel was almost the same. There is no feature.

As for high-precision vibration measurement by all-wheel phase adjustment, when the OK / NG of the vibration is to be evaluated, as described above, even if the vehicle has the same trouble level due to the change in the phase, the vibration of the vehicle is determined by the tire phase. Because the level changes (see FIG. 6), quantitative evaluation cannot be performed in both actual running and stationary running tests. Then, using the tire independent rotation mechanism as in the present embodiment, the roller 7 is rotated so that the tire phase of each wheel matches, and the condition that the relative phase of the four wheels becomes 0 degree, that is, the condition that the vibration level becomes the highest And perform quantitative evaluation.

In determining whether the vibration is OK or NG, the OK or NG level of the vibration differs depending on the type of vehicle or the type of vehicle.
₀ (f) is set, and this is input in the vehicle type table of the microcomputer 10. Then, the vehicle type table is searched according to the input of the vehicle type information, the determination value G ₀ (f) is taken out, and the measurement is started after setting. The determination is made individually based on each vibration frequency f.

The outline of the procedure for measuring vibrations by the above-described apparatus having the above contents is as follows. First, the electric motors 9a-
The rollers 7a to 7d are rotated by slightly changing the rotation speed by d, and the four wheels are rotated at different rotation speeds. Then, the steering wheel vibration at this time is taken from the acceleration sensor 4 and an order ratio analysis is performed (see FIG. 8A), and how much vibration is generated for each of the tires 1a to 1d.
Further, it is detected at which phase the maximum value of the vibration exists (see FIGS. 8B and 8C). Then, the electric motors 9a to 9d are controlled by the computer 10 so that the phases of all four wheels match, that is, the phase
The number of rotations of the four wheels is controlled so that (the phase where the maximum value of the vibration exists) matches . When all four wheels are in phase, the rotation speed of all four wheels is, of course, the same. And
The maximum value of the vibration value at this time is detected to determine the vibration.
At the same time, how much residual imbalance each wheel has is evaluated based on the magnitude and phase of the vibration of each wheel. Here, the residual unbalance is the unbalance that remains even though the mass weight is installed on the wheel to correct the unbalance in the tire when it occurs. This residual imbalance cannot be completely eliminated due to the weight or poor installation of the weight.

The reason why the phase adjustment of all wheels is performed in the above procedure is that, as described above, the actually measured synthetic vibration changes greatly due to the difference in the rotational phase of each of the tires 1a to 1d. This is because it is necessary to evaluate the phase of all wheels together. Maximum vibration occurs by matching the phases.

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

First, as a preparation for measurement, after the vehicle 11 enters, 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 (S2).
4).

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

Then, whether the phases of all the wheels are uniform , that is, the maximum value of the vibration exists for all the wheels
It is determined whether the phases are the same (S7). If the result of this determination is that the phases of all the wheels are the same, the process immediately proceeds to the next step 9, but if not, the phases of the respective wheels are different. , The control to adjust the phase of each wheel by the electric motors 9a to 9d is performed. That is, the electric motors 9a to 9d
To control the rotation speeds of the four wheels so that the phases of all four wheels match (S8). For example, the rotation speed of the wheel whose phase is to be changed is temporarily changed (increased or decreased), and when the phases match, the change in the rotation speed is stopped to obtain the same rotation speed. At this time, since all the wheels are in phase, the combined vibration is maximized.

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 according to the following equation _GP (f) = P × A. Here, P is a measured acceleration, and A is a vehicle correction coefficient. Then, G _P (f) is changed to the vibration reference value G ₀ (f).
Then, it is determined whether the vibration value exceeds the reference value (S11). If it is confirmed that the value does not exceed the reference value as a result of the determination, a message indicating OK is displayed (S12). Further, each wheel is determined by the magnitude and phase of the vibration of each wheel measured in step 6. Evaluate how much residual imbalance it has (S1
3). On the other hand, if the result of the determination in step 11 exceeds the reference value, a message indicating that the vibration is NG is displayed as exceeding the reference value (S14). These results are output from a printer (not shown). (S1
5).

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

Therefore, according to this embodiment, all four tires 1a to 1d can be independently rotated,
Since all-wheel independent phase / vibration measurement evaluation and all-wheel phase control are performed, quantitative evaluation of vibration problems caused by tires, which has been extremely difficult in actual running and stationary running tests, becomes possible. The evaluation can be performed with high accuracy (reproducibility).

Also, it is possible to evaluate so-called tire-on-the-car imbalance. That is, at present, the tire balance is corrected in a state before the tire is mounted on the vehicle (off-the-car). Even if the residual unbalance is completely set to 0 and the tire is mounted on the vehicle in this off-the-car state, the tire of the axle is The imbalance may remain in the vehicle state due to the accuracy of the mounting portion, the residual imbalance of the disc plate and the drive shaft, and the like. This imbalance of the vehicle state is called a tire-on-the-car imbalance. In this embodiment, such a tire-on-the-car imbalance can be evaluated.

Further, according to the present embodiment, the stationary evaluation can be performed with higher accuracy than in the actual running test, and the actual man-hours can be eliminated.

[0031]

As described above, according to the present invention, all wheels independent phase / vibration measurement evaluation and all wheel phase control are performed by enabling the four wheels to rotate independently, so that the stationary running test is performed. In this case, it is possible to quantitatively evaluate a vibration defect caused by a tire, and to perform a vehicle body vibration evaluation with high accuracy.

[Brief description of the drawings]

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

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

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

FIG. 4 is a diagram showing an apparatus 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 embodiment.

[Explanation of symbols]

 Reference Signs List 1 tire 2 rotation sensor 3 steering 4 acceleration sensor 7 roller 8 belt 9 electric motor 10 computer

Claims (1)

(57) [Claims] 1. A method for measuring vibration around a steering wheel caused by rotation of a tire in a stationary running test, wherein four wheels are rotated at different rotation speeds, and vibration around the steering wheel at this time is detected. Te performed frequency analysis, for each wheel, vibration controls and detecting a phase indicating the position of the maximum, the rotational speed of the four wheels so that the phase match for all four wheels and phase adjustment, Detecting a maximum value of the vibration at this time and comparing the detected value with a reference value of the vibration.