JPH01253630A - Measurement of high speed uniformity of tire - Google Patents

Abstract

PURPOSE:To make it possible to measure the peak values of the high degree components of the high speed uniformity of a tire accurately in a short time, by rotating the tire at a speed which is continuously changed, continuously measuring the rotating speed and the fluctuating component of the axial force, and carrying out the degree analysis. CONSTITUTION:A tire 1 is rotated. Then, the driving force of a drum 3 is made to be zero, and the tire is made to rotate by inertia. When the speed reaches the intended speed range, a trigger pulse is generated in a reference position detector 5. Sampling in sampling circuits 8 and 9 is started. In this way, the time series data of fluctuation in the radial direction (RFV), fluctuation in the lateral direction (LFV) and fluctuation in the tangential direction (TFV) are obtained. The data are stored in a disk memory. Then, the data are used, unbalance is corrected, and the characteristics of each degree component of high speed uniformity are obtained by fast Fourier transform analysis. Thus, the peak position can be measured accurately in a short time without missing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for measuring tire properties, in particular high-speed uniformity of passenger car tires.

(Prior Art) Conventionally, when measuring the high-speed uniformity of a tire, the tire is rotated at a speed level with a predetermined load applied, and the radial force fluctuation (RFV) that occurs at that time is measured.
), lateral force variation (LFV, ) and tangential force variation (TFV) are being measured. These force fluctuations are generally referred to as axial force fluctuation components.

(Problem to be Solved by the Invention) As mentioned above, high-speed uniformity was conventionally measured while rotating the tire at a predetermined speed level.
High-speed uniformity has the characteristic that its characteristics vary significantly with subtle changes in speed. In particular, higher-order components of uniformity, which have a relatively large effect on tire performance, tend to vary greatly depending on rotational speed. The reason for this is that when a tire rolls at high speed, the frequency of the components included in uniformity tends to increase, and the vibration characteristics (natural vibration) of the tire come into play. Therefore, there is a possibility that characteristics at speeds that cause problems may be missed. To prevent this, increase the number of speed levels,
Uniformity can be measured at many different rotational speeds, but this has the drawback of requiring a great deal of effort and time.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such drawbacks and to provide a method capable of accurately measuring the peak of high-order components of high-speed uniformity of a tire in a short period of time.

(Means and effects for solving the problem) In measuring the high-speed uniformity of a tire, the present invention rotates the tire at a continuously changing speed, and almost continuously measures the rotational speed and axial force fluctuation components. It is characterized by:

In such a measuring method of the present invention, for example, a diamond is rotated to a speed slightly higher than the maximum speed of the target speed range, and then the tire is coasted to continuously reduce the rotational speed of the tire. Rotation speed information and R11V
By substantially continuously measuring at least one of , LFV, and TI'V and further performing order analysis, it is possible to accurately grasp the high-order components of the tire's high-speed uniformity.

(Example) The first part shows the overall configuration of an apparatus for carrying out a method for measuring high-speed uniformity of a tire according to the present invention δ. Mount the tire 1 whose high-speed uniformity is to be measured on the rotatable rim 2 7, and press it against the drum 30 with a predetermined load;
] I want to be able to do it. Each time the ram 3 is rotated in the direction shown by the arrow B, the tire 1 is rolled in the direction shown by the arrow B. A wheel component force meter 4 is installed on the support part of the ring 2, which measures the load applied to the tire 1 and also measures the radial force fluctuation 1? It is configured so that three of FV, lateral force variation LFV, and tangential force variation TFV can be measured simultaneously. Since such wheel component force d1 itself is the same as that used when implementing the conventional measurement method, detailed explanation will be omitted. Further, the tire support portion has high rigidity so that the distance between the rotation axis of the tire 1 and the rotation axis of the drum 3 does not vary from a set value. Furthermore, a reference position detector 5 detects when any one point of the tie V1-L passes through the reference position, and a sampling pulse generator ηE detects the rotational speed of the tire and generates a sampling pulse having a repetition frequency corresponding to the rotational speed of the tire. , RN6 are provided. In this example, the sampling pulse generator 6 is configured to generate 128 ramp link pulses per rotation of the tire. The sampler pulses are supplied to a frequency/voltage (F/V) converter 7 to generate a voltage proportional to the frequency of the sampling pulses;
This is supplied to the sampling circuit 8. - side, RFV, LFV and T F measured with wheel component force meter 4
V is supplied to the →J coupling circuit 9. The reference position detector 5 generates a trigger pulse when a predetermined reference position on the circumference of the tire 1 comes into contact with, for example, the drum 3.
- Supply the trigger pulse to the sampling circuits 8 and 9 to start sampling. The takes sampled by these sampling circuits 8 and 9 are sent to the central processing unit]
0 and stored in the disk memory provided there.

Next, the measuring method of this example will be explained with reference to the signal waveform diagrams shown in FIGS. 2 and 3 and the flowchart shown in FIG. 4.

In the present invention, instead of measuring uniformity while rotating the tire 1 at a constant speed, high-speed uniformity is measured by detecting the axial force fluctuation component without continuously changing the rotation speed. I have to. For this purpose, the vehicle is accelerated or decelerated over a wide range including the target speed range. In this example, after rotating the tire 1 to a speed slightly higher than the target speed range, the driving force from the drum 3 is reduced to zero, the vehicle is driven by inertia, and data sampling is started when the target speed range is entered. Make it. The sampling method is such that when any one point of the tire 1 touches the drum 3, the reference position detector 5
A trigger pulse is generated from , and this trigger pulse causes the sampling circuits 8 and 9 to start sampling. Therefore, at any rotational speed, sampling starts when one point of the tire touches the ground, and 128 pieces of time-series data for one rotation are obtained, and at each sampling point, RFV.

Four sets of data are obtained: LFV and TFV data and rotational speed data at that time. These data are supplied to CPU10 and stored in disk memory. In this case, if pulse-like noise is mixed into the axial force fluctuation component data, the measurement accuracy will deteriorate, so the data corresponding to each point on the tire circumference is averaged over 2 to 3 rotations of the tire. , and store the results in disk memory.

FIG. 2 shows a trigger pulse generated from the reference position detector 5 every rotation of the tire, a sampling pulse generated from the sampling pulse generator 6, and RFV. In this way the RFV.

This means that we have been able to measure the so-called high-speed uniformity of LFV and TFV, but these data include unbalance caused by the tire assembly and unbalance caused by errors in the installation of the rim and machine. It is. Since these imbalances are essentially unrelated to the characteristics of the tire, they need to be removed. For this purpose, unbalance correction as described below is performed.

After the tire 1 is pressed against the drum 3 and the drum 3 is rotated to the same rotational speed as when loaded, the tire load is made zero and the tire is idled. Tire 1 decelerates,
When the target speed range is reached, data sampling is performed in exactly the same way as when under load. Once the unloaded data is measured in this way, it is subtracted from the unloaded data at the same speed to obtain unbalance-corrected data. However, since unbalance affects only RFV and TFV, there is no need to correct unbalance for LPV.

FIG. 3A shows RFV measurement data under load and during idling using solid lines and broken lines, respectively, and FIG. 3B shows RFV data after unbalance correction.

Frequency analysis is performed using fast Fourier transform using data with unbalance corrected as described above, and it is possible to measure the characteristics of each order component of high-speed uniformity in the target speed range. In this case, the speed step will be significantly thinner than before,
Therefore, it is possible to measure all the peak positions of high-speed uniformity, which were missed by conventional wide speed steps.

FIGS. 5 and 6 compare and show the measurement results of the conventional method and the method of the present invention. FV,
FIG. 6 shows the fifth-order components of LFV.

In FIG. 5, the solid line indicates R measured by the method of the present invention.
The fifth-order component of FV is shown, and the broken line shows what was measured by the conventional method. Here, the conventional method is O~150km
Data was collected at eight speed levels in a speed range of /h.

Looking at RFV, the conventional method has 1201an/
The peak appears at a speed of about 130 km/h, whereas the method of the invention makes it possible to reliably detect a true peak appearing at a speed of about 130 km/h. Similarly, for TFV, the method of the present invention can accurately detect the true peak that appears at approximately 110 km/h, whereas in the conventional method, this 110 km/h is not the measurement speed.
An erroneous measurement would be made as if there was a peak at a speed of 120 km/h.

FIG. 7 shows the fifth order component of RFV of two tires of the same type measured by a conventional method, and the measurement speed is five points. FIG. 8 shows the fifth order component of RFV measured by the method of the present invention for the same tire. In FIGS. 7 and 8, the solid line shows the characteristics of tire A, and the broken line shows the characteristics of tire B. These tires are 1
Although it is the same type as 75/70SR13, the rigidity of the tire site' portion is different and the natural frequency is different, so the peak position is different. In the conventional method shown in FIG. 7, the data measurement speed points are coarse, so peaks are detected at the same speed, whereas in the method of the present invention shown in FIG. 8, shifts in peak positions cannot be accurately detected. can. In order to accurately detect such deviations in peak position using conventional methods, it is necessary to set the measurement speed level at extremely fine intervals, which requires a considerable amount of time and effort. In the method of the invention, for example, 1.60 km/h
It is possible to complete all data acquisition within a short period of time by rotating the vehicle to a speed of approximately 401 an/h, coasting, and continuously decelerating to a speed of approximately 401 an/h.

In the embodiment described above, I'lFV is the axial force fluctuation component.

Although LFV and TFV were measured, it is not always necessary to measure all of them, and it is sufficient to measure at least one of them.

(Effects of the Invention) As described above, the method of the present invention measures tll'V, Lt'V, and TFV in a wide speed range while continuously changing the rotational speed of the tire. Uniformity can be measured accurately and in a short time, and peaks of high-order components of high-speed uniformity, which were previously overlooked, can be detected with high accuracy.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an example of a device for implementing the high-speed tire uniformity measurement method according to the present invention, Fig. 2 is a signal waveform diagram for explaining its operation, and Fig. 3 A and B are the same. Figure 4 is a flowchart showing the sequential steps of high-speed uniformity measurement; Figures 5 to 8 are actual measurement examples using the method of the present invention and the conventional method. This is a graph showing. X... Tire 2... Rim 3... Drum 4... Wheel component force meter 5... Reference position detector 6... Sampling pulse generator 7... Frequency/voltage converter 8. 9...Zumbling circuit 10...Central processing unit patent applicant: Patent attorney representing Bridesl Co., Ltd.
Akira Sugimura Inquiry Patent Attorney Written by Oki Sugimura

Claims (1)

[Claims] 1. When measuring high-speed uniformity of tires,
A method for measuring high-speed uniformity of a tire, which comprises rotating the tire at a continuously changing speed and measuring the rotational speed and axial force fluctuation components almost continuously.