JP6267588B2 - Tire force variation measuring method and tire sorting method using the same - Google Patents

Description

  The present invention relates to a tire force variation measuring method that increases measurement accuracy while increasing measurement efficiency, and a tire sorting method using the method.

  In order to reduce vibrations during vehicle travel, tires with excellent uniformity are required. The uniformity of the tire is quantitatively grasped by, for example, force variation which is a fluctuation component of force generated by the running tire. Therefore, it is important to accurately measure force variation.

  The force variation is obtained, for example, by running a tire on a drum testing machine and measuring a fluctuation component of a force generated by the tire. On the other hand, the force variation tends to vary greatly depending on the temperature of the tire. Therefore, in order to accurately measure the force variation, it is necessary to run the tire continuously (warm-up running) until the temperature of the tire becomes constant on the drum testing machine. On the other hand, such work has a problem that it takes a long time for measurement.

  In response to such a problem, for example, Patent Document 1 described below causes a tire to run at a constant speed on a drum testing machine, and records force variations as needed according to the running time. A method for estimating the final convergence value is proposed. This method can shorten the measurement time of force variation.

  However, since the method of Patent Document 1 merely estimates force variation by calculation, there is room for improvement in terms of accurate measurement.

JP 2002-55026 A

  The present invention has been devised in view of the above circumstances, and measures the force variation by continuously changing the running speed of the tire, and measures the force variation while running the tire at a constant speed. The main object is to provide a method for accurately measuring the tire force variation while increasing the measurement efficiency, and a method for selecting a tire using the same.

  The present invention is a method for measuring force variation, which is a fluctuation component of force generated by a running tire, by running the tire on a drum testing machine, and the running speed of the tire is set in advance. A first step of measuring the force variation by continuously changing in a defined first measurement speed range, and obtaining a relationship between the traveling speed and the force variation in the first measurement speed range; and the relationship A second step of examining a peak speed at which a force variation to be measured shows a peak based on the above, a third step of determining a second measurement speed range that includes the peak speed and is narrower than the first measurement speed range, and A fourth step of measuring the force variation within a second measurement speed range, and in the fourth step, the tire is driven at a constant speed. It is characterized by measuring the force variation while.

  In the tire force variation measuring method of the present invention, it is desirable that the first step is to change the running speed of the tire at a constant acceleration.

  In the tire force variation measuring method of the present invention, it is desirable that the first step is to reduce the running speed of the tire at 0.4 to 2.0 km / h per second.

  In the tire force variation measuring method of the present invention, it is desirable that the fourth step measures the force variation at each step of the running speed by changing the running speed of the tire stepwise.

  In the method for measuring force variation of a tire according to the present invention, in the fourth step, it is desirable that the force variation is measured after the tire is run at the constant speed for 10 to 30 minutes.

  According to a second aspect of the present invention, a tire is run on a drum tester to measure a force variation that is a fluctuation component of a force generated by the running tire, and the tire is measured based on the force variation. A method for sorting, wherein the force variation is measured by continuously changing a running speed of the tire in a predetermined first measurement speed range, and the running speed in the first measurement speed range is measured. And the force variation, and based on the relationship, a first selection step of selecting tires having a force variation peak equal to or less than a predetermined threshold as non-defective products, and the non-defective product in the first selection step For tires that were not selected, the peak speed at which the force variation to be measured based on the above relationship showed a peak A second measurement speed range that includes the peak speed and is narrower than the first measurement speed range is determined, and the force variation is performed while running the tire at a constant speed within the second measurement speed range. And a second selection step for determining the quality of the tire based on the obtained force variation.

  The method for measuring a force variation of a tire according to the present invention measures the force variation by continuously changing the tire traveling speed within a predetermined first measurement speed range, and determines the traveling speed within the first measurement speed range. A first step of obtaining a relationship with the force variation, a second step of examining a peak speed at which the force variation to be measured shows a peak based on the relationship, and including the peak speed and being narrower than the first measurement speed range. A third step of determining a second measurement speed range of the range; and a fourth step of measuring the force variation within the second measurement speed range. Moreover, the fourth step is characterized by measuring force variation while running the tire at a constant speed.

  In the measuring method of the present invention, the force variation is measured by continuously changing the tire traveling speed in the first step, and therefore, in which speed range an approximate peak of the force variation occurs is efficiently measured. be able to. In addition, in the fourth step, the force variation is narrowed down to a narrower range and the force variation is measured with a constant tire running speed, so the force variation is measured with high accuracy in a short time. Can do.

  In the tire selection method of the present invention, the tire traveling speed is continuously changed in a predetermined first measurement speed range to measure force variation, and the tire traveling speed in the first measurement speed range is A first selection step of acquiring a relationship with the force variation and selecting a tire in which the peak of the force variation is equal to or less than a predetermined threshold value as a non-defective product. Since the first selection step measures force variation by continuously changing the running speed of the tire, it is possible to select a tire that becomes a good product efficiently in a short time. At this time, since the value of the force variation depends on the temperature of the tire, for example, it is desirable to set a larger safety factor with respect to the threshold value for selecting non-defective products.

  According to the tire sorting method of the present invention, for tires that are not sorted as non-defective products in the first sorting step, the approximate peak speed at which the force variation to be measured shows a peak based on the relationship is examined, the peak speed is included, and A second measurement speed range narrower than the first measurement speed range is determined, a force variation is measured while running the tire at a constant speed within the second measurement speed range, and the obtained force is obtained. A second selection step of determining whether the tire is good or bad based on the variation; In such a second selection process, the tire variation is measured at a constant speed within a limited speed range, and the force variation is measured, so that a highly accurate measurement result can be obtained in a short time, and consequently high precision. Thus, the quality of the tire can be determined.

It is the schematic of a drum testing machine. It is a perspective view which shows the force which generate | occur | produces in the tire 1 during driving | running | working. (A) And (b) is a graph showing the relationship between the running speed Vt of a tire, and time t. It is a graph which shows the relationship between the running speed Vt of the tire acquired at the 1st process, and the force variation FV. It is a graph showing the relationship between the running speed Vt of a tire, and time t when measuring the force variation FV at a 4th process. It is a graph which shows the relationship between the running speed Vt of a tire, and the several high order component of RFV. It is a graph which shows the relationship between the running speed Vt of a tire, and the 27th-order component of RFV. It is a graph which shows the relationship between the frequency f1 of a tire, and the force variation FV. It is a flowchart of the sorting method of the tire of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of a drum testing machine 2 for measuring a force variation (hereinafter sometimes referred to as “FV”). As shown in FIG. 1, FV is measured as a fluctuation component of force generated by the running tire 1 by running the tire 1 on the drum 3 of the drum testing machine 2. The FV is measured by, for example, the tire support 4 and output to the recording device 5. This FV is measured, for example, according to JASOC 618: 2003 “Tyre / Wheel Uniformity Test Method at High Speed”.

  FIG. 2 is a perspective view showing the force generated in the running tire 1. As shown in FIG. 2, the force generated in the running tire 1 includes a tire radial force F1 (not shown, hereinafter the same), a tire axial force F2, and a tire longitudinal direction. The force F3 can be decomposed. FV is a fluctuation component of the force in each direction, a radial force variation (hereinafter sometimes abbreviated as “RFV”) that is a fluctuation component of the force F1 in the tire radial direction, and a force F2 in the tire axial direction. Lateral force variation (hereinafter sometimes abbreviated as “LFV”) which is a fluctuation component and tangential force variation (hereinafter abbreviated as “TFV”) which is a fluctuation component of the force F3 in the longitudinal direction of the tire. Is included.)

  RFV, LFV, and TFV are obtained by Fourier transforming the fluctuation waveform when the tire makes one revolution, respectively, and the primary component that becomes the fundamental frequency component of the fluctuation waveform and the higher-order frequency component of the fluctuation waveform. Can be broken down into higher order components.

  The tire 1 is assembled on a regular rim (not shown), for example, and filled with an internal pressure 0.8 to 1.2 times the normal internal pressure, for example, and set on the drum testing machine 2.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, and “ETRTO” If there is "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “highest air pressure”, TRA is the table “TIRE LOAD LIMITS AT” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  For example, the tire 1 travels on the drum 3 in a state where a load that is 0.8 to 1.2 times the normal load is applied.

  “Regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The tire FV measurement method of the present embodiment includes a first step of measuring the FV by changing the running speed of the tire in an arbitrary range, and a second method of narrowing down the measurement range based on the measurement result obtained in the first step. A process and a third process, and a fourth process for measuring FV within the narrowed measurement range. Hereinafter, each process will be described in detail.

[First step]
In the first step, the FV is measured by continuously changing the running speed Vt of the tire 1 within a predetermined first measurement speed range R1. Thereby, the relationship between the running speed Vt and FV of the tire 1 in the first measurement speed range R1 is acquired.

  FIG. 3A is a graph showing the relationship between the running speed Vt of the tire 1 (shown in FIG. 1 and the same applies hereinafter) and the elapsed time t at the time of measurement in the first measurement speed range R1. Is shown. In the graphs of FIGS. 3A and 3B, the horizontal axis represents time t, and the vertical axis represents tire running speed Vt.

  The first measurement speed range R1 is arbitrarily determined in consideration of, for example, a speed region where there are many opportunities for the tire to actually travel. The minimum speed Vmin in the first measurement speed range is, for example, 10 to 50 km / h, and in this embodiment, 30 km / h. The maximum speed Vmax in the first measurement speed range R1 is, for example, 120 to 200 km / h, and is 130 km / h in the present embodiment. FV is measured from time ts to time tf.

  The running speed Vt of the tire 1 continuously changes at least from the minimum speed Vmin to the maximum speed Vmax in the first measurement speed range R1. In the embodiment of FIG. 3 (a), the running speed Vt of the tire 1 decreases as the time t elapses.

  For example, the traveling speed Vt of the tire according to the present embodiment is preferably changed at a constant acceleration within the first measurement speed range R1. As a result, the FV is accurately measured over the entire first measurement speed range R1.

  The running speed Vt of the tire is desirably decreased at 0.4 to 2.0 km / h per second, for example. When the amount of change in the tire running speed Vt is smaller than 0.4 km / h per second, the measurement time may increase. When the amount of change in the tire traveling speed Vt is larger than 2.0 km / h per second, there is a possibility that an error included in the relationship between the tire traveling speed Vt and the FV increases.

  As shown in FIG. 3B, the traveling speed Vt of the tire 1 may be reduced as time t elapses. In the case of FIG. 3A, after the traveling speed Vt of the tire 1 is previously set to be greater than the maximum speed Vmax, FV is measured while decreasing the speed of the tire 1. As an example of a specific aspect, it is desirable that the driving force is stopped while the drum is rotating, and the FV is measured. Thereby, for example, even when the drum testing machine 2 does not have a function of continuously adjusting the traveling speed of the tire, the relationship between the traveling speed Vt and the FV of the tire 1 can be obtained.

  FIG. 4 shows a graph G3 showing the relationship between the tire running speed Vt and FV acquired in the first step. In FIG. 4, the horizontal axis represents the tire running speed Vt, and the vertical axis represents FV. In this embodiment, the primary component of RFV is shown as FV.

[Second step]
In the second step, the peak speed to be measured is examined based on the relationship between the tire running speed Vt and FV obtained in the first step.

  The peak speed is a speed at which FV shows a peak. In the present embodiment, a speed P1 indicating the largest FV in the first measurement speed range R1 is selected as the peak speed. The peak speed is not limited to this, and may include, for example, a speed at which the FV exhibits a peak within an arbitrary speed range. For example, in FIG. 4, the speed P2 at which the FV has a peak in the speed region where the tire traveling speed Vt is 80 km / h or less may be selected as the peak speed. Thus, the peak speed is variously determined according to the FV to be evaluated.

[Third step]
In the third step, a second measurement speed range R2 that includes the peak speed obtained above and is narrower than the first measurement speed range R1 is determined. The second measurement speed range R2 of the present embodiment is determined so as to include the peak speed P1 having the largest FV within the first measurement speed range R1. Thereby, FV of the range where a peak appears is measured in detail.

  The magnitude | size of 2nd measurement speed range R2 is arbitrarily determined as needed. When the second measurement speed range R2 is large, the measurement time may be long. When the second measurement speed range R2 is small, the measurement accuracy may be reduced. For this reason, it is desirable that the second measurement speed range R2 is determined within a range of −5 km / h to +5 km / h of the peak speed P1, for example. The second measurement speed range R2 of the present embodiment is a range of −2 km / h to +2 km / h of the peak speed P1.

[Fourth step]
In the fourth step, the FV is measured again within the second measurement speed range R2. In the fourth step, FV is measured while running the tire at a constant speed. That is, in the fourth step, one or a plurality of tire traveling speeds Vt are selected from the second measurement speed range R2 having a certain range, and the selected traveling speed Vt is maintained constant. Is measured.

  In the measurement method including the first step to the fourth step as described above, the FV is measured by continuously changing the tire traveling speed in the first step. Can be measured efficiently. Moreover, in the fourth step, the FV is measured in a narrow speed range where the FV peak appears, with the tire running speed being constant, so that the temperature change of the tire can be minimized and the FV can be measured with higher accuracy. .

  FIG. 5 shows a graph G4 representing the relationship between the tire running speed Vt and the time t when the FV is measured in the fourth step of the present embodiment. As shown in FIG. 5, in the fourth step of the present embodiment, while keeping the tire traveling speed constant, the speed is changed stepwise (in this example, rising), and the FV is set at each stage traveling speed. Is measured. In the present embodiment, the FV is, for example, a speed V1 at a peak speed P1-2 km / h, a speed V2 at a peak speed P1-1 km / h, a peak speed P1, a speed V3 at a peak speed P1 + 1 km / h, and a peak speed P1 + 2 km. It is measured at a speed V4 of / h. Thereby, even when an error is included in the peak speed acquired in the first process, an accurate peak speed can be acquired in the fourth process.

  At each speed V1 to V4, it is desirable that the tire 1 is sufficiently warmed up until the temperature of the tire 1 becomes constant. For this reason, it is desirable to measure FV after running the tire 1 at a constant speed for at least 10 to 30 minutes at each speed V1 to V4.

  In the fourth step, the tire may not be sufficiently warmed up at the speed V1 at the start of measurement. For this reason, it is desirable to run the tire 1 for 30 minutes or more at the speed V1. Thereby, FV is measured with higher accuracy.

  In the first step of the present embodiment, as shown in FIG. 4, the relationship between the tire running speed and the primary component of RFV is acquired. A 1st process is not limited to such an aspect, For example, you may acquire the relationship between the running speed Vt of a tire, and several high order component of RFV.

  FIG. 6 shows a graph showing the relationship between the tire traveling speed Vt and a plurality of higher-order components of RFV. In FIG. 6, the horizontal axis represents the tire running speed Vt, and the vertical axis represents RFV. Graphs G5, G6, and G7 in FIG. 6 correspond to the 11th-order component, the 12th-order component, and the 13th-order component of RFV, respectively.

  As shown in FIG. 6, the peak velocities P5, P6, and P7 of the graphs G5 to G7 are different from each other. In this case, the second measurement speed range R2 may be determined for each of the peak speeds P5 to P7, and the FV of each order component may be measured within each second measurement speed range R2.

  In the first step, when acquiring the relationship between the tire running speed Vt and the higher order component of FV, the order n of the higher order component of FV is arbitrarily determined from various viewpoints.

  For example, when a mold formed by vulcanizing a tire is formed of N segments divided in the tire circumferential direction, N irregularities are generated in the tire circumferential direction on the outer or inner surface of the tire, There is a possibility that the Nth order component of FV and the higher order component of integer multiples of N are deteriorated. For example, a tire molded with a mold composed of nine segments may deteriorate the 9th, 18th, or 27th order components of FV. Therefore, it is desirable that the order n of the higher order component of FV to be obtained is an integer multiple of the number N of mold segments for vulcanizing and molding the tire.

  In the relationship between the tire running speed Vt and FV acquired in the first step, when a plurality of peak speeds are obtained, in the second step, for example, the tire running speed Vt is converted into the tire frequency f1, The peak speed may be selected based on the tire frequency f1. Hereinafter, in the second step, a method of selecting the peak speed based on the tire frequency f1 will be described.

FIG. 7 shows a graph G8 showing the relationship between the running speed Vt of the tire and the 27th-order component of RFV. As shown in FIG. 7, the graph G8 includes the following peak velocities P2, P3, and P4.
P2: Vt ≒ 63km / h
P3: Vt ≒ 81km / h
P4: Vt ≒ 117km / h

On the other hand, the tire frequency f1 (Hz) is represented by the product of the higher order component order n (27th order in FIG. 7) and the tire rotational speed Nt per second. I know I can represent it.
f1 = n × Nt (1)

Since the tire rotation speed Nt is proportional to the tire running speed Vt, the tire vibration frequency f1 can be expressed by the following equation (2).
f1 = n × a × Vt (2)
(Where a is a proportional constant determined by the circumference of the outer surface of the tire.)

  Therefore, the running speed Vt of the tire represented by the horizontal axis in FIG. 7 can be represented by the tire frequency f1. FIG. 8 shows a graph G9 in which the horizontal axis of FIG. 7 is converted from the tire running speed Vt to the tire frequency f1. As shown in FIG. 7, in the second step, the relationship between the tire running speed Vt and FV acquired in the first step is converted into the relationship between the tire frequency f1 and FV, and the tire frequency is changed. The peak speed may be selected using f1.

  In this case, the selection of the peak speed can be arbitrarily determined from various viewpoints. For example, it has been found that tire noise is greatly amplified when the frequency f1 of a running tire matches the natural vibration frequency fc of the tire. The natural vibration frequency fc of the tire varies depending on the size and shape of the tire, but it is known that the conventional tire is in the range of 230 to 270 Hz. Therefore, when the FV of the tire is measured, it is desirable that the FV in the range where the tire frequency f1 is 230 to 270 Hz is measured in detail.

  For this reason, when the peak speed is selected based on the tire frequency f1, it is desirable to select the peak speed that is closest to the natural vibration frequency fc of the tire. For example, in the case of the graph G9 in FIG. 8, it is desirable that the peak speed P2 with the tire frequency f1 closest to the natural vibration frequency fc is selected and the second measurement speed range R2a is determined in the third step. Thereby, the measurement range is limited, and the working efficiency of measurement is effectively enhanced.

  Next, a tire selection method using the above-described FV measurement method will be described. FIG. 9 shows a flowchart of the tire sorting method of the present embodiment.

  As shown in FIG. 9, the tire sorting method of the present invention includes a first sorting step S1 and a second sorting step S2. Hereinafter, each process will be described in detail.

[First sorting step]
In the first sorting step S1, FV is measured by continuously changing the tire running speed within a predetermined first measurement speed range R1, and the relationship between the running speed Vt and FV in the first measurement speed range R1. To get. These steps are performed in the same manner as in the first step of the tire FV measurement method described above.

  In the first sorting step S1, based on the above relationship, tires whose FV peak is equal to or less than a predetermined threshold T1 within the first measurement speed range R1 are sorted as non-defective products. The tire whose peak exceeds the threshold value T1 is sent to the second sorting step S2. At this time, since the value of FV depends on the temperature of the tire, for example, it is desirable to set a larger safety factor with respect to the threshold value for selecting good products.

[Second sorting step]
In the second sorting step S2, the tires that have not been sorted as non-defective products in the first sorting step S1 are further sorted by measuring the FV in more detail.

  In the second sorting step S2, the peak speed at which the FV to be measured has a peak is determined based on the relationship between the running speed Vt and the FV in the first measurement speed range R1 acquired in the first sorting step S1 for the tire. A second measurement speed range R2 including the peak speed and narrower than the first measurement speed range R1 is determined. These steps are performed in the same manner as the second step and the third step of the tire FV measurement method described above.

  In the second sorting step S2, FV is measured while running the tire at a constant speed within the second measurement speed range R2. These steps are performed in the same manner as the fourth step of the tire FV measurement method described above.

  In the second selection step S2, the quality of the tire is determined based on whether the FV exceeds a predetermined threshold value T2.

  In order to increase the safety factor in the first sorting step, the threshold T1 in the first sorting step S1 is preferably smaller than the threshold T2 in the second sorting step. Thereby, a tire with a large FV is reliably sorted in the first sorting step S1.

  As mentioned above, although the measuring method of FV of the tire of this invention and the method for classifying a tire based on FV were demonstrated in detail, this invention is not limited to said specific embodiment, Various. The embodiment is changed to the embodiment.

The force variation (primary component of RFV) of a plurality of sample tires is the measurement method of the present invention and the measurement method performed with the tire running speed Vt constant (120 km / h) (hereinafter referred to as “conventional measurement method”) Is measured by). The common specifications of sample tires are as follows.
Tire size: 215 / 50R17
Internal pressure: 250kPa
Load applied during running: 4.9kN

The value of force variation in the conventional measuring method, the peak value and peak speed of the force variation obtained in the first step of the measuring method of the present invention, and the force variation obtained in the second step of the measuring method of the present invention. The peak value and the peak speed were compared.
The test results are shown in Table 1.

  As shown in Table 1, when RFV was measured by a conventional measurement method, the average value of RFV of samples 1 to 5 was 53.8 (N). On the other hand, the measurement method of the present invention shows a higher peak value than the conventional measurement method. That is, in the conventional measurement method, since RFV was measured with the tire running speed Vt kept constant, it was confirmed that the peak value of RFV was not obtained.

As shown in Table 1, in the measurement method of the present invention, the peak velocity and peak value of RFV can be obtained in a short time in the first step. Moreover, in the measurement method of the present invention, accurate RFV peak velocity and peak value can be obtained in the fourth step. That is, it was confirmed that the measurement method of the present invention has superior work efficiency and measurement accuracy as compared with the conventional measurement method.

1 Tire 2 Drum Testing Machine R1 First Measurement Speed Range R2 Second Measurement Speed Range Vt Tire Travel Speed

Claims (6)

A method for measuring a force variation which is a fluctuation component of a force generated by the running tire by running the tire on a drum testing machine,
The force variation is measured by continuously changing the running speed of the tire in a predetermined first measurement speed range, and the relationship between the running speed and the force variation in the first measurement speed range is acquired. A first step of
Based on the relationship, the second step of examining the peak speed at which the force variation to be measured exhibits a peak;
A third step of determining a second measurement speed range that includes the peak speed and is narrower than the first measurement speed range;
A fourth step of measuring the force variation within the second measurement speed range,
In the fourth step, the force variation is measured while the tire is running at a constant speed.   The tire first variation measuring method according to claim 1, wherein the first step changes a running speed of the tire at a constant acceleration.   The tire first variation measuring method according to claim 1 or 2, wherein the first step reduces the running speed of the tire at 0.4 to 2.0 km / h per second.   4. The method of measuring a tire force variation according to claim 1, wherein in the fourth step, the running speed of the tire is changed in a stepwise manner, and the force variation is measured at the running speed of each step. 5.   5. The method of measuring a tire force variation according to claim 1, wherein the fourth step measures the force variation after running the tire at the constant speed for 10 to 30 minutes. 6. A method for measuring a force variation that is a fluctuation component of a force generated by the tire during traveling by running the tire on a drum testing machine, and selecting the tire based on the force variation,
Measure the force variation by continuously changing the running speed of the tire within a predetermined first measurement speed range,
Obtaining a relationship between the travel speed and the force variation in the first measurement speed range;
Based on the relationship, a first selection step of selecting tires for which the peak of the force variation is equal to or less than a predetermined threshold value as non-defective products,
For tires that were not selected as non-defective products in the first selection step, the peak speed at which the force variation to be measured based on the relationship indicated a peak was examined,
Determining a second measurement speed range that includes the peak speed and is narrower than the first measurement speed range;
A second selection step of measuring the force variation while running the tire at a constant speed within the second measurement speed range, and determining the quality of the tire based on the obtained force variation. A tire sorting method characterized by the above.

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