Uniformity estimation method and uniformity testing device

Abstract

To provide a uniformity estimation method and a uniformity testing device capable of highly accurately estimating uniformity at a first revolution speed greater than a second revolution speed based on a measurement result of the uniformity at the second revolution speed.SOLUTION: An arithmetic unit of a uniformity testing device includes: Fourier transforming medium-speed time-domain waveform data acquired by a measurement part into a medium-speed frequency-domain waveform data and decomposing it into first to seventh order components (S3: an analysis step); correcting amplitudes of the decomposed first to seventh order components by using correction amplification ratios individually determined for the respective first to seventh order components (S4: a correction step); and synthesizing the corrected first to seventh order components to create high-speed frequency-domain waveform data, inverse Fourier transforming the created high-speed frequency-domain waveform data, and calculating a high-speed time-domain waveform data (S5: a component synthesis step, S6: inverse Fourier transformation, S7: high-speed time-domain waveform data calculation step).SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a method for estimating the uniformity of a tire or a tire on a wheel, and to a testing device for performing a uniformity test on a tire or a tire on a wheel. [Background technology]

[0002] In order to improve vehicle vibration caused by tires or wheels with tires, uniformity tests are performed during tire manufacturing and the like. In recent years, vibration, noise, and the like caused by automobiles traveling at high speeds (e.g., 100 km / h, etc.) have become a problem, and it is known that uniformity at high speeds is strongly involved in these problems. It takes a long time to measure high-speed uniformity in a uniformity test, and high-speed uniformity may not be measured depending on the performance of the test equipment. Therefore, it is difficult to measure high-speed uniformity for all tires or wheels with tires that are inspected. In other words, it is difficult to perform 100% measurement inspection for high-speed uniformity. On the other hand, for uniformity tests at speeds other than high speeds, that is, uniformity tests at low speeds (e.g., 10 km / h or less) and medium speeds (e.g., 45 km / h to 60 km / h), 100% measurement inspection is often performed.

[0003] It has been proposed to measure the uniformity of a tire or a tire-equipped wheel under inspection at a rotation speed other than a high speed, and to estimate the uniformity at a high rotation speed based on the measurement results (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7188010 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desired to estimate the uniformity at the first rotation speed (high speed) with even higher accuracy based on the measurement result of the uniformity at the second rotation speed (speed other than high speed).

[0006] An object of the present invention is to provide a uniformity estimation method and uniformity testing apparatus that can estimate uniformity at a first rotation speed that is higher than a second rotation speed with high accuracy based on the uniformity measurement results at the second rotation speed. [Means for solving the problem]

[0007] An embodiment of the present invention provides a uniformity estimation method and a uniformity testing apparatus having the following features.

[0008] 1. a second rotation speed time domain waveform data acquisition step of measuring a tire or a wheel with a tire rotating at a second rotation speed lower than the first rotation speed, and acquiring second rotation speed time domain waveform data corresponding to the second rotation speed, which is waveform data in the time domain of uniformity of the tire or the wheel with a tire; an analysis step of converting the acquired second rotation speed time domain waveform data into second rotation speed frequency domain waveform data, which is data in the frequency domain of the waveform data, and analyzing the data; a correction step of correcting the second rotation speed frequency domain waveform data by multiplying the amplitudes of 1st to nth order components (n: a predetermined natural number equal to or greater than 4) included in the second rotation speed frequency domain waveform data by correction amplitude ratios that are individually determined for each of the 1st to nth order components and that correspond to both the second rotation speed before correction and the first rotation speed after correction; and a first rotation speed time domain waveform data calculation step of converting first rotation speed frequency domain waveform data created by combining the corrected 1st order components to nth order components into a time domain, and calculating first rotation speed time domain waveform data which is waveform data in the time domain of uniformity of the tire or the tire-equipped wheel and corresponds to the first rotation speed.

[0009] The present inventors discovered that in uniformity testing of tires or tires on wheels, the amplitude of each of the first to nth order components of the waveform in the frequency domain depends on the rotation speed of the tire or tires on wheels being tested.

[0010] According to this configuration, the second rotation speed time domain waveform data obtained by measuring the tire or the tire-equipped wheel is converted into the frequency domain, and the amplitudes of the first to nth order components at that time are corrected using the correction amplitude ratios determined for each component. The corrected frequency domain waveforms are then synthesized to calculate first rotation speed time domain waveform data in the time domain. Based on the calculated first rotation speed time domain waveform data, the uniformity when the tire or the tire-equipped wheel is rotated at the first rotation speed is obtained.

[0011] As described above, the amplitude of each of the first to nth order components of the waveform in the frequency domain depends on the rotation speed of the tire or wheel with tire as the test object. Therefore, by setting each of the correction amplitude ratios of the first to nth order components to a correction amplitude ratio determined for correction from the second rotation speed to the first rotation speed, the first rotation speed time domain waveform data in the time domain can be estimated based on the second rotation speed time domain waveform data.

[0012] This allows the uniformity at the first rotation speed to be estimated with high accuracy based on measurements of the tire or wheel with a tire rotating at the second rotation speed.

[0013] 2. a first rotation speed waveform data acquisition step of acquiring waveform data of uniformity when a tire of the same type as the tire or a wheel with a tire of the same type as the wheel with a tire is rotated at the first rotation speed; a second rotation speed waveform data acquisition step of acquiring waveform data of uniformity when the same type of tire or the same type of tire mounted wheel is rotated at the second rotation speed; and an amplitude ratio calculation step of calculating an amplitude ratio for each of the first to n-th order components based on the waveform data acquired in the first rotation speed waveform data acquisition step and the waveform data acquired in the second rotation speed waveform data acquisition step, the ratio of the amplitude corresponding to the first rotation speed to the amplitude corresponding to the second rotation speed, 2. The uniformity estimation method according to item 1, wherein the amplitude ratios for the first to nth order components are used as the correction amplitude ratios for the first to nth order components in the correction step, respectively.

[0014] 3. 3. The uniformity estimation method according to item 1 or 2, wherein the amplitude ratio calculation step fixes the correction amplitude ratios of first to third order components to 1.0, changes the amplitude ratios of fourth to nth order components, and sets the amplitude ratios of the fourth to nth order components when the waveform data acquired in the second rotation speed waveform data acquisition step approximates the waveform data acquired in the first rotation speed waveform data acquisition step as the correction amplitude ratios of the fourth to nth order components. Generally, there is no difference in the amplitudes of the first to third order components between the uniformity of a first rotation speed (e.g., high speed) and the uniformity of a second rotation speed (e.g., medium speed). Therefore, the correction amplitude ratios corresponding to the first to third order components are all fixed to 1.0. Since the number of parameters can be kept small, it is possible to calculate the correction amplitude ratios corresponding to each of the fourth to nth order components with high accuracy. Since correction is performed using a highly accurate correction amplitude ratio, the first rotation speed time domain waveform data can be estimated with higher accuracy.

[0015] 4. The first rotation speed is a high speed, 4. The uniformity estimation method according to any one of items 1 to 3, wherein the second rotation speed is a medium speed. The first rotation speed is a high speed, 3. The uniformity estimation method according to claim 1, wherein the second rotation speed is a medium speed.

[0016] 5. A holding and rotating device that holds and rotates a tire or a wheel with a tire; a measurement unit that measures the tire or the tire-equipped wheel rotating at a second rotation speed lower than the first rotation speed by the holding and rotating device, and obtains waveform data in the time domain of uniformity of the tire or the tire-equipped wheel, the second rotation speed time domain waveform data corresponding to the second rotation speed; a calculation device that calculates first rotation speed time domain waveform data corresponding to the first rotation speed, which is waveform data in the time domain of uniformity of the tire or the tire-equipped wheel, based on the second rotation speed time domain waveform data acquired by the measurement unit, a correction step of multiplying amplitudes of 1st to nth order components (n: a predetermined natural number equal to or greater than 4) included in the second rotation speed frequency domain waveform data by correction amplitude ratios that are individually determined for each of the 1st to nth order components and that correspond to both the second rotation speed before correction and the first rotation speed after correction; and a first rotation speed time domain waveform data calculation step of converting first rotation speed frequency domain waveform data created by combining the corrected 1st to nth order components into a time domain to calculate first rotation speed time domain waveform data that is waveform data in the time domain of uniformity of the tire or the tire-equipped wheel and corresponds to the first rotation speed.

[0017] 6. 5. The uniformity estimation method according to any one of items 1 to 4, wherein the uniformity is at least one of RFV, LFV, and TFV.

[0018] 7. The correction amplitude ratios of the first to third order components are all 1.0, 7. The uniformity estimation method according to any one of items 1 to 4 and 6, wherein the correction amplitude ratio of at least one of the fourth-order component to the nth-order component is a real number other than 1.0. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram for explaining a schematic configuration of a uniformity testing device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view for explaining a holding frame included in the uniformity testing apparatus. [Diagram 3] FIG. 3 is a block diagram for explaining the electrical configuration of the measurement unit shown in FIG. [Figure 4] FIG. 4 is a block diagram for explaining the electrical configuration of the arithmetic device shown in FIG. [Diagram 5] FIG. 5 is a diagram for explaining the contents stored in the first correction amplitude ratio group in the correction amplitude ratio storage unit shown in FIG. [Figure 6] FIG. 6 is a diagram for explaining the stored contents of the second correction amplitude ratio group in the correction amplitude ratio storage unit. [Figure 7] FIG. 7 is a diagram for explaining the stored contents of the third correction amplitude ratio group in the correction amplitude ratio storage unit. [Figure 8] FIG. 8 is a diagram for explaining the stored contents of the fourth correction amplitude ratio group in the correction amplitude ratio storage unit. [Figure 9] FIG. 9 is a diagram for explaining the stored contents of the fifth correction amplitude ratio group in the correction amplitude ratio storage unit. [Figure 10] FIG. 10 is a flow chart showing the calculation contents by the calculation device. [Figure 11]11 is a diagram showing an example of uniformity waveform data before correction. Fig. 11(a) is a diagram showing an example of medium-speed time domain waveform data of uniformity (RFV, LFV). Fig. 11(b) is a diagram showing an example of medium-speed frequency domain waveform data of uniformity (RFV). [Figure 12] 12A and 12B are diagrams showing an example of uniformity waveform data after correction. FIG. 12A is a diagram showing an example of uniformity (RFV, LFV) high-speed time domain waveform data. FIG. 12B is a diagram showing an example of uniformity (RFV) high-speed time domain waveform data. [Figure 13] FIG. 13 is a flowchart for explaining the determination of the correction amplitude ratio. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0021] FIG 1 is a diagram for explaining a schematic configuration of a uniformity testing apparatus 1 according to one embodiment of the present invention. In FIG 1, a direction perpendicular to the paper surface is defined as a first direction X, and a left-right direction in FIG 1 is defined as a second direction Y. The first direction X and the second direction Y are included in the horizontal direction of the uniformity testing apparatus 1. The up-down direction in FIG 1 is the vertical direction of the uniformity testing apparatus 1.

[0022] The uniformity test device 1 is a device for performing a uniformity test on a tire 2 or a wheel 3 (tired wheel 4) on which the tire 2 is mounted. The uniformity test is a test in which the tire 2 or the tire-equipped wheel 4 is rotated at a predetermined number of revolutions while receiving a predetermined load, and the uniformity of the force generated by the tire 2 or the tire-equipped wheel 4 at this time is measured. In the uniformity test using the uniformity test device 1, three values ​​are mainly inspected at the tire contact surface: Radial Force Variation (hereinafter simply referred to as "RFV"), Lateral Force Variation (hereinafter simply referred to as "LFV"), and Tractive Force Variation (hereinafter simply referred to as "TFV"). RFV is the magnitude of the force variation in the radial direction of the tire 2 or the tire-equipped wheel 4. LFV is the magnitude of the force variation in the width direction of the tire 2 or the tire-equipped wheel 4. TFV is the magnitude of the force fluctuation in the forward direction of the tire 2 or the tire wheel 4.

[0023] The uniformity testing apparatus 1 includes a holding device 5 for rotatably holding the tire 2 or tired wheel 4 (tired wheel 4 in the example of Figure 1) as the test specimen, a load device 6 for applying a ground load from a second direction Y to the tire 2 or tired wheel 4 (tired wheel 4 in the example of Figure 1) rotatably held by the holding device 5, a measuring unit 7 for measuring the uniformity of the tire 2 or tired wheel 4 (tired wheel 4 in the example of Figure 1) rotating in the holding device 5, and a calculation device 8 for calculating the uniformity of the tire 2 or tired wheel 4 (tired wheel 4 in the example of Figure 1) as the test specimen based on the measurement results by the measuring unit 7.

[0024] The holding device 5 supports the tired wheel 4 so that it can rotate while lying horizontally. The holding device 5 includes a support device 9 that supports the tired wheel 4, and a rotating shaft 10 that extends vertically downward from the support device 9. The central axis of the rotating shaft 10 is a rotation axis J that is set to extend vertically. A first pulley 11 is coaxially fitted onto the rotating shaft 10. The holding device 5 further includes a first base 12 fixed to the machine base B, and a holding frame 13 fixed to the upper end of the first base 12 and holding the rotating shaft 10 so that it can vibrate.

[0025] FIG. 2 is a plan view for explaining the holding frame 13 included in the uniformity testing apparatus 1. As shown in FIG.

[0026] 2, the holding frame 13 includes a shaft holding frame 16 that holds the rotating shaft 10 in a vertical direction, a first holding frame 18 that holds the shaft holding frame 16 via a first spring 17 so that the shaft holding frame 16 can vibrate in a horizontal first direction X, and a second holding frame 20 that holds the first holding frame 18 via a second spring 19 so that the first holding frame 18 can vibrate in a horizontal second direction Y perpendicular to the first direction X. The second holding frame 20 is fixed to the first base 12 (see FIG. 1). The holding frame 13 has a known configuration disclosed, for example, in JP 2016-45048 A and the like.

[0027] The rotating shaft 10 is fixed to a shaft holding frame 16. The second holding frame 20 is fixed to a first base 12 (see FIG. 1). Therefore, the rotating shaft 10 can vibrate in a total of three directions, namely, a first direction X, a second direction Y, and a torsional direction N around an axis extending in the second direction Y, relative to the first base 12. Therefore, the tire-equipped wheel 4 (see FIG. 1) attached to a support device 9 (see FIG. 1) arranged on the upper end of the rotating shaft 10 can vibrate in a total of three directions, namely, the first direction X, the second direction Y, and the torsional direction N, relative to the first base 12.

[0028] With reference to FIG. 1, the holding device 5 further includes a driving device 21 fixed to the machine base B. The driving device 21 includes a first motor 22. A first output shaft 23 of the first motor 22 protrudes upward along the vertical direction. A second pulley 24 is fixed to the first output shaft 23, and the second pulley 24 and the first pulley 11 of the rotating shaft 10 are connected by a first belt 25. When the first motor 22 is driven to rotate the first output shaft 23, the rotation of the first output shaft 23 is transmitted to the rotating shaft 10 via the first belt 25. As a result, the rotating shaft 10 rotates, and the tire-equipped wheel 4 can rotate at a predetermined rotation speed.

[0029] 1, the load device 6 is arranged next to the holding device 5 in the second direction Y. The load device 6 includes a second base 26, a pair of guide rails 27, and a sliding mechanism 28. The second base 26 is a block elongated in the second direction Y, installed on the machine base B. The pair of guide rails 27 are fixed to an upper surface of the second base 26. The pair of guide rails 27 extend in the second direction Y while being aligned in the first direction X.

[0030] 1, the sliding mechanism 28 includes a mounting plate 29 extending horizontally above the guide rail 27, and a plurality of slide legs 30 provided on the lower surface of the mounting plate 29 and engaging with the guide rail 27 from above. The sliding mechanism 28 further includes a feed nut 31 fixed to the mounting plate 29, a feed screw 32 assembled to the feed nut 31, and a feed motor 33 connected to the feed screw 32. The feed motor 33 is fixed to the second base 26 by an attachment member 34. When the feed motor 33 is driven, the feed screw 32 rotates, and the feed nut 31 slides together with the mounting plate 29 along the guide rail 27 in the second direction Y.

[0031] 1, a spindle 35 extending in the vertical direction is fixed to the mounting plate 29. A rotating drum 36 is mounted on the upper end of the portion of the spindle 35 that protrudes upward from the mounting plate 29. The rotating drum 36 is cylindrical with the spindle 35 as its center, and its outer circumferential surface functions as a substitute road surface for applying a ground contact load to the tire-equipped wheel 4. The rotating drum 36 slides in the second direction Y together with the mounting plate 29.

[0032] Referring to FIG. 1, the load device 6 further includes a second motor 37. A second output shaft 38 of the second motor 37 extends along the vertical direction, and a third pulley 39 is fixed to the second output shaft 38. A fourth pulley 40 is also fixed to the spindle 35, and the third pulley 39 and the fourth pulley 40 are connected by a second belt 41. When the second motor 37 is driven to rotate the second output shaft 38, the rotation of the second output shaft 38 is transmitted to the spindle 35 via the second belt 41. As a result, the spindle 35 rotates, and the rotating drum 36 rotates at a predetermined rotation speed. The second motor 37, the rotating drum 36, and the holding device 5 constitute a holding and rotating device.

[0033] 1 and 2, the measurement unit 7 includes a measurement sensor 70. The measurement sensor 70 includes a plurality of force sensors. In this embodiment, the measurement sensor 70 includes a first sensor 71, a second sensor 72, and a third sensor 73. The first sensor 71, the second sensor 72, and the third sensor 73 independently detect vibrations in any of the above-mentioned three directions in which the rotating shaft 10 can vibrate relative to the first base 12. The first sensor 71 detects vibrations in the first direction X of the rotating shaft 10. The second sensor 72 detects torsional vibrations of the rotating shaft 10 (for example, vibrations in a torsional direction N around an axis extending in the second direction Y). The third sensor 73 detects vibrations in the second direction Y of the rotating shaft 10. The first sensor 71, the second sensor 72, and the third sensor 73 are all, for example, acceleration sensors. The first sensor 71, the second sensor 72, and the third sensor 73 are fixed to the holding frame 13 (more specifically, the second holding frame 20).

[0034] 2, the first sensor 71 detects the vibration of the shaft holding frame 16 in the first direction X through the first vibration transfer rod 43 that extends from the first sensor 71 in the first direction X and contacts the shaft holding frame 16. In relation to the second sensor 72, one end of the first vibration transmission rod 44 that extends from the shaft holding frame 16 in the first direction X is fixed to the shaft holding frame 16. The second sensor 72 detects the torsional vibration of the shaft holding frame 16 through the second vibration transfer rod 45 that extends vertically upward from the second sensor 72 and contacts the other end of the first vibration transmission rod 44. The third sensor 73 detects the vibration of the first holding frame 18 in the second direction Y through the third vibration transfer rod 46 that extends from the third sensor 73 in the second direction Y and contacts the first holding frame 18. The vertical vibration of the axle holding frame 16 is calculated based on the torsional vibration of the axle holding frame 16 detected by the second sensor 72 and the vibration in the first direction X detected by the first sensor 71. The first sensor 71, the second sensor 72, and the third sensor 73 output detection signals in response to a reaction force generated in the tire-equipped wheel 4, which is the test object. The first sensor 71, the second sensor 72, and the third sensor 73 are of known configuration, for example, as disclosed in JP 2016-45048 A and the like.

[0035] The calculation device 8 is configured by a computer including a CPU, ROM, RAM, etc. In the uniformity test, the calculation device 8 calculates the uniformity (RFV, LFV, and TFV) of the tired wheel 4 based on the detection outputs from the first sensor 71, the second sensor 72, and the third sensor 73.

[0036] FIG. 3 is a block diagram for explaining the electrical configuration of the measurement unit 7. As shown in FIG.

[0037] The measurement unit 7 includes a plurality of sensors 71, 72, 73, a plurality of amplifier filters, a plurality of low-pass filters, an analog-digital converter 87, and a pulse generator 88. The plurality of amplifier filters include a first amplifier filter 81, a second amplifier filter 82, and a third amplifier filter 83. The first amplifier filter 81, the second amplifier filter 82, and the third amplifier filter 83 receive detection signals from the first sensor 71, the second sensor 72, and the third sensor 73, respectively. The detection signals received by the amplifier filters 81, 82, and 83 include DC components indicating the magnitude of the forces acting in the above three directions in which the rotating shaft 10 can vibrate relative to the first base 12, and AC components of the forces that vary with the rotation of the tire-equipped wheel 4. Each of the amplifier filters 81, 82, and 83 separates the DC components from the detection signals received by the amplifier filters. Each of the amplifier filters 81, 82, and 83 amplifies the component signals of the AC components included in the detection signals received by the amplifier filters.

[0038] The multiple low-pass filters include a first low-pass filter 84, a second low-pass filter 85, and a third low-pass filter 86. The first low-pass filter 84, the second low-pass filter 85, and the third low-pass filter 86 receive the component signals amplified by the first amplifier filter 81, the second amplifier filter 82, and the third amplifier filter 83, respectively. Each of the low-pass filters 84, 85, and 86 extracts a necessary frequency component from the amplified component signal. The extracted signal is provided to an analog-to-digital converter 87.

[0039] A pulse generator (PG) 88 is disposed in the holding frame 13. The pulses generated by the pulse generator 88 are input to an analog-digital converter 87. The analog-digital converter 87 performs AD conversion processing using the pulses generated by the pulse generator 88 as a sampling clock. The signal data (digital data) digitized by the analog-digital converter 87 is provided to the calculation device 8.

[0040] FIG. 4 is a block diagram for explaining the electrical configuration of the arithmetic device 8. FIG. 5 is a diagram for explaining the storage contents of the first correction amplitude ratio group 97A in the correction amplitude ratio storage unit 94. FIG. 6 is a diagram for explaining the storage contents of the second correction amplitude ratio group 97B in the correction amplitude ratio storage unit 94. FIG. 7 is a diagram for explaining the storage contents of the third correction amplitude ratio group 97C in the correction amplitude ratio storage unit 94. FIG. 8 is a diagram for explaining the storage contents of the fourth correction amplitude ratio group 97D in the correction amplitude ratio storage unit 94. FIG. 9 is a diagram for explaining the storage contents of the fifth correction amplitude ratio group 97E in the correction amplitude ratio storage unit 94.

[0041] As shown in Fig. 4, the arithmetic device 8 is configured using, for example, a microcomputer. The arithmetic device 8 has a calculation unit 91 consisting of a processor such as a CPU, a fixed memory device (not shown), a storage unit 92 such as a hard disk drive, and an input / output unit (not shown). The storage unit 92 stores a program 93 executed by the calculation unit 91 and a recipe that specifies the contents of the measurement process for the tired wheel 4. The storage unit 92 also has a correction amplitude ratio storage unit 94 for storing a correction amplitude ratio, which will be described later. The correction amplitude ratio storage unit 94 is made of a non-volatile memory that is electrically rewritable.

[0042] The arithmetic device 8 functions as a control device that manages the measurement operation of the uniformity test equipment 1. The arithmetic device 8 controls the operations of the first motor 22, the feed motor 33, the second motor 37, etc. An input device 96 such as a mouse or a keyboard is connected to the arithmetic device 8. Contents input through the input device 96 are input to the arithmetic device 8. A display device 95 such as a monitor is connected to the arithmetic device 8. The arithmetic device 8 controls the display operation of the display device 95.

[0043] A detection signal is input to the arithmetic unit 8 from the analog-digital converter 87 of the measurement unit 7. The arithmetic unit 8 corrects the gain delay of the low-pass filters 84, 85, and 86 for the data digitized by the analog-digital converter 87. The arithmetic unit 8 acquires waveform data in the time domain and waveform data in the frequency domain based on the input detection signal.

[0044] The uniformity of the tested tire wheel 4 depends on the rotation speed. The uniformity at medium speed (a predetermined speed of 45 km / h to 60 km / h) and the uniformity at high speed (a predetermined speed of 80 km / h or more) are different from each other. Furthermore, even at the same high speed, the uniformity at 80 km / h, the uniformity at 100 km / h, and the uniformity at 120 km / h are different from each other.

[0045] It is generally believed that the change in uniformity of the test object (tire 2 or tire-equipped wheel 4) with the rotation speed is caused by a plurality of natural frequencies of the holding device 5, the test object, etc. That is, it is believed that the change is caused by vibration due to runout, etc. being amplified according to the rotation speed by the natural frequencies of the holding device 5 and the test object. Therefore, the amplitude of each order component in the frequency domain of the uniformity of the test object depends on the rotation speed of the test object. That is, the amplitude of each order component in the 1st order component to the nth order component (n: a predetermined natural number equal to or greater than 4) of the waveform in the frequency domain depends on the rotation speed of the test object (tire 2 or tire-equipped wheel 4). In addition, the amplitude of each order component in the 4th order component and above among the 1st order component to the nth order component of the waveform in the frequency domain depends particularly on the rotation speed of the test object.

[0046] In the uniformity test apparatus 1, the uniformity (RFV, LFV) of the medium-speed frequency domain waveform data 101B (see FIG. 11(b) described later) is decomposed into 1st to 7th order components, and the amplitudes of the decomposed 1st to 7th order components are corrected using individually determined correction amplitude ratios AR1, AR2, AR3, AR4, AR5, AR6, and AR7 (see FIG. 5). Then, the uniformity test apparatus 1 calculates the high-speed time domain waveform data 102A (see FIG. 12(a) described later) based on the medium-speed time domain waveform data 101A (see FIG. 11(a) described later).

[0047] The correction amplitude ratio storage unit 94 stores a plurality of correction amplitude ratio groups (correction amplitude ratios AR1 to AR7). In the example of Fig. 4, the stored correction amplitude ratio groups are exemplified by a first correction amplitude ratio group 97A (see Fig. 5), a second correction amplitude ratio group 97B (see Fig. 6), a third correction amplitude ratio group 97C (see Fig. 7), a fourth correction amplitude ratio group 97D (see Fig. 8), and a fifth correction amplitude ratio group 97E (see Fig. 9). Each of the correction amplitude ratio groups 97A to 97E corresponds to both the type of test object (in this embodiment, the type of the tire-equipped wheel 4) and the rotation speed before correction (medium rotation speed) and the rotation speed after correction (high rotation speed). As shown in FIGS. 5 to 9, each of the correction amplitude ratio groups 97A to 97E includes a first correction amplitude ratio AR1 for the first order component, a second correction amplitude ratio AR2 for the second order component, a third correction amplitude ratio AR3 for the third order component, a fourth correction amplitude ratio AR4 for the fourth order component, a fifth correction amplitude ratio AR5 for the fifth order component, a sixth correction amplitude ratio AR6 for the sixth order component, and a seventh correction amplitude ratio AR7 for the seventh order component.

[0048] The correction amplitude ratios AR1 to AR7 included in the first correction amplitude ratio group 97A shown in Fig. 5 are correction amplitude ratios corresponding to the type of the test object corresponding to the tire wheel 4A and the rotation speed before correction and the rotation speed after correction corresponding to 45km / h and 120km / h, respectively. The tire wheel 4A is a tire wheel in which a specific type of tire from a specific manufacturer is combined with a specific wheel (e.g., made of steel). The correction amplitude ratios AR1, AR2, AR3, AR4, AR5, AR6, and AR7 included in the first correction amplitude ratio group 97A are, for example, 1.0, 1.0, 1.0, 2.0, 1.0, 9.0, and 1.0, respectively.

[0049] The correction amplitude ratios AR1 to AR7 included in the second correction amplitude ratio group 97B shown in Fig. 6 are correction amplitude ratios corresponding to the type of the test object corresponding to the tire wheel 4A and the rotation speed before correction and the rotation speed after correction corresponding to 45 km / h and 100 km / h, respectively. The correction amplitude ratios AR1, AR2, AR3, AR4, AR5, AR6, and AR7 included in the second correction amplitude ratio group 97B are, for example, 1.0, 1.0, 1.0, 1.0, 6.0, 8.0, and 1.0, respectively.

[0050] The correction amplitude ratios AR1 to AR7 included in the third correction amplitude ratio group 97C shown in FIG. 7 are correction amplitude ratios corresponding to the type of the test object corresponding to the tire wheel 4B, and corresponding to the rotation speed before correction and the rotation speed after correction of 45 km / h and 120 km / h, respectively. The tire wheel 4B is a tire wheel that combines a specific type of tire of a specific manufacturer with a specific wheel (e.g., made of aluminum). The tire wheel 4B is a tire wheel that combines the above-mentioned specific type of tire with a specific aluminum wheel. The correction amplitude ratios AR1, AR2, AR3, AR4, AR5, AR6, and AR7 included in the third correction amplitude ratio group 97C are, for example, 1.0, 1.0, 1.0, 1.0, 10.0, 5.0, and 3.0, respectively.

[0051] 8, the correction amplitude ratios AR1 to AR7 included in the fourth correction amplitude ratio group 97D are correction amplitude ratios corresponding to the type of the test object corresponding to the tire wheel 4B and the rotation speed before and after correction corresponding to 45 km / h and 100 km / h, respectively. The correction amplitude ratios AR1, AR2, AR3, AR4, AR5, AR6, and AR7 included in the fourth correction amplitude ratio group 97D are, for example, 1.0, 1.0, 1.0, 2.0, 10.0, 1.0, and 2.0, respectively.

[0052] 9, the correction amplitude ratios AR1 to AR7 included in the fifth correction amplitude ratio group 97E are correction amplitude ratios corresponding to the type of the test object corresponding to the tire wheel 4B and the rotation speed before correction and the rotation speed after correction corresponding to 45 km / h and 80 km / h, respectively. The correction amplitude ratios AR1, AR2, AR3, AR4, AR5, AR6, and AR7 included in the fifth correction amplitude ratio group 97E are, for example, 1.0, 1.0, 1.0, 1.0, 11.0, 1.0, and 1.0, respectively.

[0053] In the multiple correction amplitude ratio groups 97A to 97E, the correction amplitude ratios AR1, AR2, and AR3 are all 1.0. At least one of the correction amplitude ratios AR4, AR5, AR6, and AR7 may be a real number other than 1.0. At least one of the correction amplitude ratios AR4, AR5, AR6, and AR7 may include a fraction after the decimal point. At least one of the correction amplitude ratios AR4, AR5, AR6, and AR7 may be greater than 1.0 or less than 1.0.

[0054] All of the correction amplitude ratios AR1 to AR7 may be 1.0.

[0055] 1, in a uniformity test performed in the uniformity test apparatus 1, the calculation device 8 drives the second motor 37 to rotate the rotating drum 36, and also rotates the feed motor 33 to slide the rotating drum 36 along the second direction Y so as to approach the support device 9. Then, the outer circumferential surface of the rotating drum 36 is pressed against the outer circumferential surface of the tire 2 of the tired wheel 4 attached to the support device 9 from the second direction Y (which is also the radial direction of the tire 2). Then, as the rotating rotating drum 36 presses against the outer circumferential surface of the tire 2 of the tired wheel 4 attached to the support device 9, the tired wheel 4 is rotated at a predetermined number of rotations.

[0056] That is, the tired wheel 4 rotates steadily while receiving a predetermined load (for example, approximately 5000 N to 10000 N) in the radial direction of the tired wheel 4. A uniformity test is performed by detecting vibrations of the tired wheel 4 in this state by the measuring unit 7. The following describes an example in which a uniformity test is performed by rotating the tired wheel 4 (more specifically, a steel tired wheel 4A) at a medium speed (for example, 45 km / h).

[0057] The measuring unit 7 measures the uniformity of the tired wheel 4 rotating at a medium speed. Specifically, the vibrations in the above three directions are detected by the measuring sensors 70 (first sensor 71, second sensor 72, and third sensor 73). Then, the detection signals from the measuring sensors 70 are provided to the computing device 8. The load in the second direction Y that the rotating drum 36 applies to the tired wheel 4 is detected by a sensor 42 provided between the feed nut 31 and the mounting plate 29.

[0058] FIG. 10 is a flow chart showing the calculation contents by the calculation device 8. FIG. 11(a) is a diagram showing an example of medium-speed time domain waveform data 101A of uniformity (RFV, LFV). FIG. 11(b) is a diagram showing an example of medium-speed frequency domain waveform data 101B of uniformity (RFV). FIG. 12(a) is a diagram showing an example of high-speed time domain waveform data 102A of uniformity (RFV, LFV). FIG. 12(b) is a diagram showing an example of high-speed frequency domain waveform data 102B of uniformity (RFV). In FIG. 11(b) and FIG. 12(b), LFV is omitted for convenience of illustration. The calculation contents by the calculation device 8 will be described with reference to FIG. 1, FIG. 3, and FIG. 10 to FIG. 12.

[0059] With the tire wheel 4A under test rotating at a medium speed (for example, 45 km / h), the calculation device 8 acquires medium-speed time domain waveform data 101A (see FIG. 11(a)) of uniformity (RFV, LFV) based on the signal data (digitized data) provided from the analog-digital converter 87 (S1 in FIG. 10: medium-speed time domain waveform data acquisition step (second rotation speed time domain waveform data acquisition step)). In response to an operation by an operator of the uniformity test apparatus 1, the calculation device 8 may display the medium-speed time domain waveform data 101A of uniformity (RFV, LFV) on the display device 95.

[0060] The calculation device 8 also converts the acquired medium-speed time domain waveform data 101A of the uniformity (RFV, LFV) into the frequency domain by Fourier transform. As a result, the calculation device 8 acquires medium-speed frequency domain waveform data 101B (see FIG. 11(b)) of the uniformity (RFV, LFV) (S2 in FIG. 10: medium-speed frequency domain waveform data acquisition step). In response to an operation by an operator of the uniformity test apparatus 1, the calculation device 8 may display the medium-speed frequency domain waveform data 101B on the display device 95.

[0061] The calculation device 8 analyzes the medium-speed frequency domain waveform data 101B of the acquired uniformity (RFV, LFV). Specifically, the calculation device 8 analyzes (decomposes) the medium-speed frequency domain waveform data 101B of the acquired uniformity (RFV, LFV) into 1st-order components to 7th-order components, and calculates the amplitudes and phases of the 1st-order components to 7th-order components (S3 in FIG. 10: analysis step).

[0062] Next, the calculation device 8 multiplies the calculated amplitudes of the 1st to 7th order components by the individually determined correction amplitude ratios AR1 to AR7 (see Figs. 5 to 9), respectively. As a result, the medium speed frequency domain waveform data 101B of the uniformity (RFV, LFV) is corrected to frequency domain waveform data corresponding to a predetermined high speed (S4 in Fig. 10: correction step).

[0063] 10, if the type of the test object supported by the support device 9 is a tired wheel 4A and the pre-correction medium speed (second rotation speed) and the post-correction high speed (first rotation speed) are 45 km / h and 120 km / h, respectively, the calculation device 8 reads out the correction amplitude ratios AR1 to AR7 (see FIG. 5) for 45 km / h to 120 km / h from the correction amplitude ratio storage unit 94. Then, the calculation device 8 multiplies the amplitude of each order component included in the medium speed frequency domain waveform data 101B of the uniformity (RFV, LFV) by the corresponding correction amplitude ratios AR1 to AR7. The amplitudes of the first, second, third, fourth, fifth, sixth and seventh order components included in the medium speed frequency domain waveform data 101B are multiplied by the first correction amplitude ratio AR1 (1.0 in the example of FIG. 5), the second correction amplitude ratio AR2 (1.0 in the example of FIG. 5), the third correction amplitude ratio AR3 (1.0 in the example of FIG. 5), the fourth correction amplitude ratio AR4 (2.0 in the example of FIG. 5), the fifth correction amplitude ratio AR5 (1.0 in the example of FIG. 5), the sixth correction amplitude ratio AR6 (9.0 in the example of FIG. 5) and the seventh correction amplitude ratio AR7 (1.0 in the example of FIG. 5). As a result, the amplitudes of the respective order components included in the medium speed frequency domain waveform data 101B are changed (S4 in FIG. 10: correction step).

[0064] Next, the arithmetic unit 8 synthesizes the corrected 1st- to 7th-order components (S5 in FIG. 10: component synthesis step), thereby generating high-speed frequency domain waveform data 102B (see FIG. 12(b)).

[0065] Next, the calculation device 8 converts the synthesized waveform data into the time domain by inverse Fourier transform. This results in waveform data obtained by converting the high-speed frequency domain waveform data 102B (see FIG. 12(b)) of the uniformity (RFV, LFV) into the time domain (S6 in FIG. 10: inverse Fourier transform).

[0066] As a result, high speed time domain waveform data 102A (see FIG. 12(a)) of the uniformity (RFV, LFV) is calculated (S7 in FIG. 10: high speed time domain waveform data calculation step (first rotation speed time domain waveform data calculation step)).

[0067] Thereafter, the calculation device 8 calculates the uniformity (RFV, LFV) based on the calculated high-speed time domain waveform data 102 A. The calculated uniformity (RFV, LFV) is displayed on the display device 95.

[0068] The uniformity test ends when the measurement of the uniformity of the tired wheel 4 rotating at a medium speed (for example, 45 km / h) is completed. After the uniformity test is completed, the calculation device 8 controls the feed motor 33 to slide the rotating drum 36 away from the tired wheel 4. As a result, the tired wheel 4 is switched to a state in which it rotates without receiving a load. The rotation of the second motor 37 then stops.

[0069] Thereafter, the calculation device 8 drives the first motor 22 of the holding device 5 to cause the first motor 22 to function as a brake. This causes the rotation of the tired wheel 4 to be decelerated. Thereafter, the rotation of the tired wheel 4 stops.

[0070] As described above, according to this embodiment, the medium speed time domain waveform data 101A obtained by measuring the tire wheel 4 is converted into the frequency domain, and the amplitudes of the first to seventh order components at that time are corrected using the correction amplitude ratios AR1 to AR7 determined for each component. Then, the corrected waveforms of the first to seventh order components are synthesized to calculate high speed frequency domain waveform data 102B. Then, based on this, high speed time domain waveform data 102A is calculated. Based on the calculated high speed time domain waveform data 102A, the uniformity (RFV and LFV) when the tire 2 or the tire wheel 4 is rotated at high speed is calculated.

[0071] As described above, the amplitude of each of the first to nth order components of the waveform data in the frequency domain depends on the rotation speed of the tire wheel 4 under test. Therefore, by using the correction amplitude ratios AR1 to AR7 determined for correction from medium speed to high speed, the high speed time domain waveform data 102A can be estimated based on the medium speed time domain waveform data 101A.

[0072] This makes it possible to estimate uniformity (RFV and LFV) at high speeds with high accuracy based on measurements of the tired wheel 4 rotating at medium speeds by the uniformity testing device 1.

[0073] Fig. 13 is a flow chart for explaining the determination of the correction amplitude ratios AR1 to AR7. The correction amplitude ratios AR1 to AR7 are determined and set as follows. Below, a case where the correction amplitude ratios AR1 to AR7 included in the correction amplitude ratio group 97A (see Fig. 5) are determined will be described as an example. Of course, the determination of the correction amplitude ratios AR1 to AR7 shown in Fig. 13 is performed before the start of the uniformity test.

[0074] First, the operator acquires waveform data in the time domain of RFV and LFV when a homogeneous tire or homogeneous tired wheel of the same type as the tire 2 or tired wheel 4 being the test specimen (in this example, a homogeneous tired wheel of the same type as the tired wheel 4A) is rotated at 45 km / h (S11: medium speed waveform data acquisition step (second rotation speed waveform data acquisition step)). The medium speed waveform data acquisition step (S11) is performed by an experiment using, for example, the uniformity test apparatus 1.

[0075] Next, the operator acquires waveform data in the time domain of the RFV and LFV when the same type of tire or the same type of tire-equipped wheel (in this example, a same type of tire-equipped wheel as the tire-equipped wheel 4A) is rotated at 120 km / h (high speed) (S12: high speed waveform data acquisition step (first rotation speed waveform data acquisition step)). The high speed waveform data acquisition step (S12) is performed, for example, by an experiment using the uniformity test apparatus 1. If it is difficult to rotate the same type of tire-equipped wheel at high speed in the uniformity test apparatus 1, for example, waveform data in the time domain of the tire-equipped wheel at 120 km / h (high speed) published by the tire manufacturer or the like may be acquired.

[0076] Then, the operator uses a calculation device to calculate correction amplitude ratios AR1 to AR7 from the time domain waveform data obtained in the medium speed waveform data acquisition process (S11) and the time domain waveform data obtained in the high speed waveform data acquisition process (S12) (S13: amplitude ratio calculation process).

[0077] Specifically, the waveform data obtained in the medium-speed waveform data acquisition step (S11) is Fourier transformed and decomposed into first to seventh order components. Each of the decomposed first to seventh order components is multiplied by an amplitude ratio to change the amplitude ratio. Then, the amplitude ratios of the first to seventh order components when the waveform data obtained in the medium-speed waveform data acquisition step (S11) approximates the waveform data obtained in the high-speed waveform data acquisition step (S12) are set as the correction amplitude ratios of the first to seventh order components (correction amplitude ratios AR1 to AR7), respectively.

[0078] At this time, only the amplitude ratios of the fourth to seventh order components are changed among the amplitude ratios of the first to seventh order components. Then, the calculation device 8 calculates the values ​​of the correction amplitude ratios AR4, AR5, AR6, and AR7 so ​​that the RFV and LFV waveform data obtained by multiplying the fourth to seventh order components by the amplitude ratios are approximate to the RFV and LFV waveform data obtained in the high-speed waveform data acquisition step (S12). More specifically, the values ​​of the correction amplitude ratios AR4, AR5, AR6, and AR7 are changed in a round-robin manner in a predetermined unit (for example, 0.5 unit) within the range from 0 to 12.0, and optimal values ​​of the correction amplitude ratios AR4, AR5, AR6, and AR7 are calculated. This makes it possible to obtain the correction amplitude ratios AR4, AR5, AR6, and AR7 with high accuracy.

[0079] Then, the correction amplitude ratios AR4, AR5, AR6, and AR7, which are the calculation results, are stored in the correction amplitude ratio storage unit 94 as a correction amplitude ratio group 97A.

[0080] By fixing the correction amplitude ratios AR1, AR2, and AR3 corresponding to the 1st to 3rd order components to 1.0, the number of parameters can be reduced to four, making it possible to calculate the correction amplitude ratios AR4, AR5, AR6, and AR7 corresponding to the 4th to 7th order components with high accuracy. Correction is performed using the highly accurate correction amplitude ratios AR4, AR5, AR6, and AR7, so the high-speed time domain waveform data 102A of the uniformity (RFV and LFV) can be estimated with higher accuracy.

[0081] Although one embodiment of the present invention has been described above, the present invention can be embodied in other forms.

[0082] Although the uniformity calculated by the calculation device 8 has been described taking RFV and LFV as an example, this uniformity may include TFV. In this case, the values ​​of the correction amplitude ratios AR1 to AR7 (correction amplitude ratios AR4 to AR7) may be calculated as the values ​​of the correction amplitude ratios AR4, AR5, AR6, and AR7 when the waveform data of RFV, LFV, and TFV obtained by multiplying the correction amplitude ratios are approximate to the waveform data of RFV, LFV, and TFV obtained in the high-speed waveform data acquisition step (S12), respectively.

[0083] Furthermore, in the above description, the Fourier transform (inverse Fourier transform) is used for the conversion between the time domain and the frequency domain, but instead, the wavelet transform (inverse wavelet transform) may be used.

[0084] Furthermore, the test object to be measured may be a tire 2 instead of the wheel 4 with a tire.

[0085] In the above description, the 1st to 7th order components decomposed based on the frequency domain data are corrected by multiplying them by the correction amplitude ratio, but the upper limit of the order of the components may be any of the 4th to 6th orders, or may be 8th order or higher.

[0086] In addition, various modifications are possible within the scope of the claims. [Explanation of symbols]

[0087] 1: Uniformity test equipment 2: Tires 4: Wheels with tires 5: Holding device (holding rotation device) 7: Measuring part 8: Arithmetic device 36: Rotating drum (holding and rotating device) 37: Second motor (holding and rotating device) 71: First sensor (sensor) 72: Second sensor (sensor) 73: 3rd sensor (sensor) 84: 1st low-pass filter (low-pass filter) 85: Second low-pass filter (low-pass filter) 86: 3rd low-pass filter (low-pass filter) 101A: Medium speed time domain waveform data (second rotation speed time domain waveform data) 101B: Medium speed frequency domain waveform data (second rotation speed frequency domain waveform data) 102A: High speed time domain waveform data (1st RPM time domain waveform data) 102B: High-speed frequency domain waveform data (first rotation speed frequency domain waveform data) AR1: 1st correction amplitude ratio (correction amplitude ratio) AR2: Second correction amplitude ratio (correction amplitude ratio) AR3: Third correction amplitude ratio (correction amplitude ratio) AR4: 4th correction amplitude ratio (correction amplitude ratio) AR5: 5th correction amplitude ratio (correction amplitude ratio) AR6: 6th correction amplitude ratio (correction amplitude ratio) AR7: 7th correction amplitude ratio (correction amplitude ratio)

Claims

1. a second rotation speed time domain waveform data acquisition step of measuring a tire or a wheel with a tire rotating at a second rotation speed lower than the first rotation speed to acquire second rotation speed time domain waveform data of the uniformity of the tire or the wheel with a tire in the time domain, the second rotation speed time domain waveform data corresponding to the second rotation speed; an analysis step of converting the acquired second rotation speed time domain waveform data into second rotation speed frequency domain waveform data, which is data in a frequency domain of the waveform data, and analyzing the data; a correction step of correcting the second rotation speed frequency domain waveform data by multiplying the amplitudes of 1st to nth order components (n: a predetermined natural number equal to or greater than 4) included in the second rotation speed frequency domain waveform data by correction amplitude ratios that are individually determined for each of the 1st to nth order components and that correspond to both the second rotation speed before correction and the first rotation speed after correction; and a first rotation speed time domain waveform data calculation step of converting first rotation speed frequency domain waveform data created by combining the corrected first order components to nth order components into a time domain, and calculating first rotation speed time domain waveform data which is waveform data in the time domain of uniformity of the tire or the tire-equipped wheel and corresponds to the first rotation speed.

2. a first rotation speed waveform data acquisition step of acquiring waveform data of uniformity when a tire of the same type as the tire or a wheel with a tire of the same type as the wheel with a tire is rotated at the first rotation speed; a second rotation speed waveform data acquisition step of acquiring waveform data of uniformity when the same type of tire or the same type of tire mounted wheel is rotated at the second rotation speed; and an amplitude ratio calculation step of calculating an amplitude ratio for each of the first to nth order components based on the waveform data acquired in the first rotation speed waveform data acquisition step and the waveform data acquired in the second rotation speed waveform data acquisition step, the ratio being a ratio of an amplitude corresponding to the first rotation speed to an amplitude corresponding to the second rotation speed, 2. The uniformity estimation method according to claim 1, wherein the amplitude ratios for the first to nth order components are used as the correction amplitude ratios for the first to nth order components in the correcting step, respectively.

3. 3. The uniformity estimation method according to claim 1, wherein the amplitude ratio calculation step fixes the correction amplitude ratios of first to third order components to 1.0, varies the amplitude ratios of fourth to nth order components, and determines the amplitude ratios of fourth to nth order components when the waveform data acquired in the second rotation speed waveform data acquisition step approximates the waveform data acquired in the first rotation speed waveform data acquisition step as the correction amplitude ratios of the fourth to nth order components.

4. The first rotation speed is a high speed, The uniformity estimation method according to claim 1 , wherein the second rotation speed is a medium speed.

5. A holding and rotating device that holds and rotates a tire or a wheel with a tire; a measurement unit that measures the tire or the wheel with a tire rotating at a second rotation speed lower than the first rotation speed by the holding and rotating device, and obtains waveform data in the time domain of uniformity of the tire or the wheel with a tire, the waveform data being second rotation speed time domain waveform data corresponding to the second rotation speed; a calculation device that calculates first rotation speed time domain waveform data corresponding to the first rotation speed, which is waveform data in the time domain of uniformity of the tire or the tire-equipped wheel, based on the second rotation speed time domain waveform data acquired by the measurement unit, a correction step of correcting the second rotation speed frequency domain waveform data by multiplying amplitudes of first to n-th order components (n: a predetermined natural number equal to or greater than 4) included in the second rotation speed frequency domain waveform data by correction amplitude ratios that are individually determined for each of the first to n-th order components and that correspond to both the second rotation speed before correction and the first rotation speed after correction; and a first rotation speed time domain waveform data calculation step of converting first rotation speed frequency domain waveform data created by combining the corrected first to n-th order components into a time domain to calculate first rotation speed time domain waveform data that is waveform data in the time domain of uniformity of the tire or the tire-equipped wheel and corresponds to the first rotation speed.

Images