JP2020085621A - Method for estimating high-rate uniformity of tire - Google Patents

Abstract

To estimate a high-rate FV and more particularly a high-rate TFV more accurately.SOLUTION: The method for estimating high-rate uniformity of tire includes a setting step S1, a measurement step S2, and an estimation step S3. The setting step S1 sets an estimation formula for estimating a high-rate FV, using a low-rate parameter including a low-rate RFV, a low-rate RRO, a static unbalance SB, and a tire rotation radius variation IRR, for the same type of tire. In the measurement step S2, for the above type of tire for which high-rate FV is unknown, the low-rate RFV, the low-rate RRO, the static unbalance SB, and the tire rotation radius variation IRR are measured. In the estimation step S3, the high-rate FV is estimated on the basis of the result of measurement and the estimation formula.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tire high speed uniformity estimation method for estimating high speed uniformity from low speed uniformity.

In order to improve vehicle vibrations caused by tires, conventionally, a 100% low-speed uniformity inspection is often performed during tire manufacturing. For low speed uniformity, uniformity factors such as RFV (radial force variation), TFV (tangential force variation), LFV (lateral force variation) and RRO (radial runout) are measured at low speeds of about 10 km/h or less. It

On the other hand, in recent years, it has been revealed that uniformity at high speeds of, for example, 100 km/h or more (high speed uniformity) is strongly related to vibration and noise during high-speed traveling. However, high-speed uniformity tends to require a long time for measurement, and it is extremely difficult to perform 100% inspection.

Therefore, Patent Document 1 below proposes estimating high-speed uniformity using a low-speed parameter including a low-speed RFV, a low-speed RRO, a static unbalance SB, and an LRO (lateral runout).

However, as a result of the inventor's study, when the above-mentioned low-speed RFV, low-speed RRO, SB, and LRO were used as parameters, as shown in FIGS. It was found that the correlation with Therefore, it is desired to improve the prediction accuracy especially in high-speed TFV.

Japanese Patent No. 5080882

An object of the present invention is to provide a high-speed uniformity estimation method for a tire, which can estimate a high-speed FV, particularly a high-speed TFV with higher accuracy.

The present invention is a high-speed uniformity estimation method for a tire,
For a tire of the same type, a setting step of setting an estimation formula for estimating a high speed FV using low speed parameters including a low speed RFV, a low speed RRO, a static unbalance SB, and a tire rolling radius variation IRR,
A measurement step of measuring a low speed RFV, a low speed RRO, a static unbalance SB, and a tire rolling radius fluctuation IRR for the tire of the above-mentioned type whose high speed FV is unknown.
An estimation step of estimating a fast FV based on the result of the measurement and the estimation formula.

In the tire high-speed uniformity estimation method according to the present invention, it is preferable that the tire rolling radius variation IRR is obtained based on the following equation (1).
IRR = (RD × .omega.D _Average / .omega.T _average) × {1+ (.omega.D _difference / .omega.D _average) - (.omega.T _difference / .omega.T _average)} --- (1)
(In the formula,
RD: drum radius [m],
ωT _average : _Average tire angular velocity [rad/s],
ωT _difference : difference from the average value of tire angular velocity [rad/s],
ωD _average : _Average drum angular velocity [rad/s],
ωD _difference : difference from the average value of drum angular velocity [rad/s],
Is. )

In the tire high-speed uniformity estimation method according to the present invention, it is preferable that the high-speed FV is a high-speed RFV or a high-speed TFV.

In the tire high-speed uniformity estimation method according to the present invention, the first-order estimation equation of the high-speed FV is represented by the following equation (2), and the n-th order (n>1) estimation equation is the following equation (3). ) Is preferable.
High-speed FV (primary)=a ₁ ×low-speed RFV (primary)+b ₁ ×low-speed RRO (primary)
+c ₁ ×static unbalance SB+d ₁ ×tire rolling radius variation IRR (primary) +e ₁
--- (2)
High-speed FV (n-th order)=a _n ×low-speed RFV (n-th order)+b _n ×low-speed RRO (n-th order)
+ _{D n} × tire rolling radius variation IRR (n order) + _{e n}
--- (3)
_{(Wherein, a 1, b 1, c} 1, d 1, a n, b n, d n is the coefficient of each of the _{parameters, e 1,} e _n is the bias.)

In the present invention, the estimation formula for estimating the high speed FV such as the high speed RFV or the high speed TFV is set by using the low speed parameter. In particular, as the low speed parameter, the tire rolling radius variation IRR is used instead of the conventional LRO.

Here, when there is a diameter variation in the tire circumferential direction, this results in a change in the angular acceleration (dωT/dt) that is a differential coefficient of the tire angular velocity ωT, which, together with the inertia moment I of the tire, causes a variation component of the longitudinal force TF. Yields a TFV of That is, there is a relationship of the following formula (a). h is the distance between the axes.
TFV=I×(dωT/dt)/h ---(a)
Further, the tire angular velocity ωT, the tire radius RT, and the velocity V have a relation of ωT=V/RT, and when differentiated with respect to time t, the following equation (b) is obtained.
(DωT/dt)=(V/RT ² )×(dRT/dt) ---(b)
Further, the relationship of the following expression (c) is obtained from the expressions (a) and (b).
TFV={(I×V)/(h×RT ² )}×(dRT/dt) -----(c)
The differential value dRT/dt in the equation (c) is a temporal variation of the tire radius RT, and therefore it can be seen that TFV is related to the tire rolling radius variation IRR.

Therefore, by using the IRR as the low speed parameter instead of the LRO, it becomes possible to further improve the estimation accuracy of the high speed TFV.

It is a flowchart explaining the procedure of the high-speed uniformity estimation method of this invention. (A)-(c) is a graph which shows the correlation of the estimated value and the measured value of the 1st-3rd order of high-speed TFV in this invention. (A)-(c) is a graph which shows the correlation of the estimated value of the 1st-3rd order of the high-speed TFV in the conventional method, and the measured value.

Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, the high speed FV of the tire is estimated, and the shipping management of the tire is performed based on the estimated value. In this example, the high-speed RFV or the high-speed TFV is estimated as the high-speed FV.

FIG. 1 is a flowchart for explaining the procedure of the high-speed uniformity estimation method of the present invention (hereinafter sometimes simply referred to as “estimation method”). As shown in FIG. 1, the estimation method of the present invention includes a setting step S1, a measurement step S2, and an estimation step S3.

In the setting step S1, an estimation formula for estimating the high speed FV is set for low speed RFV, low speed RRO, static imbalance SB, and low speed parameters including the tire rolling radius variation IRR for the same type of tire.

The same type of tire means a group of tires having the same size, the same internal structure, and the same tread pattern. Such tires of the same type have substantially the same specifications and characteristics except for slight manufacturing variations.

In the setting step S1, specifically, first, the low speed parameter and the high speed FV are respectively measured for a plurality of tires of the same type (step S1A). After that, an estimation formula for estimating the high speed FV is set based on the measured value of the low speed parameter and the measured value of the high speed FV (step S1B).

In step S1A, the high speed FV is measured using a high speed uniformity measuring machine as in the conventional case, for a tire rotating at a speed at which centrifugal force can sufficiently act on the tire, for example, a high speed of 100 km/h or more. The measured high-speed FV data is subjected to order analysis using a computer or the like, and a necessary high-speed FV order component is calculated. Each order component of this fast FV is obtained as a vector quantity having a magnitude and a phase angle. The phase angle is an angle from a reference position set at an arbitrary position of the tire.

In step S1A, the low speed RFV and the low speed RRO are measured using a low speed uniformity measuring machine as in the conventional case, for a tire rotating at a speed at which centrifugal force does not substantially act on the tire, for example, a low speed of 10 km/h or less. To be done. The measured low speed RFV and low speed RRO data are subjected to order analysis using a computer or the like, similarly to the high speed FV data, and the necessary low speed RFV order component and low speed RRO order component are calculated. The order component of the low speed RFV and the order component of the low speed RRO are also obtained as a vector quantity having a magnitude and a phase angle (angle from the reference position).

In step S1A, for the static unbalance SB, the unbalance amount and the phase angle of the peak position (angle from the reference position) are measured using, for example, an unbalance measuring machine as in the conventional case.

Further, in step S1A, the tire rolling radius variation IRR is calculated by ) Is used to calculate.
IRR = (RD × .omega.D _Average / .omega.T _average) × {1+ (.omega.D _difference / .omega.D _average) - (.omega.T _difference / .omega.T _average)} --- (1)
(In the formula,
RD: drum radius [m],
ωT _average : _Average tire angular velocity [rad/s],
ωT _difference : difference from the average value of tire angular velocity [rad/s],
ωD _average : _Average drum angular velocity [rad/s],
ωD _difference : difference from the average value of drum angular velocity [rad/s],
Is. )

The rotation speed measuring device includes, for example, an encoder that is attached to the drum shaft and that generates a pulse signal according to the drum rotation angle, and a modulator. The modulator extracts the fluctuation of the tire rotation frequency fT over the circumference of the tire and the fluctuation of the drum rotation frequency fD over the circumference of the drum from the pulse signal.

Then, from the tire rotation frequency fT and the drum rotation frequency fD, the tire angular velocity ωT and the drum angular velocity ωD at an arbitrary phase position can be obtained by the following equations (4) and (5).
ωT=2π.(fT/PT)---(4)
ωD=2π·(fD/PD) −−−(5)

"PT" is the number of pulse signals in one rotation of the tire. The tire circumference varies depending on the rolling radius. Therefore, it is preferable to set the PT by rotating the tire a plurality of times, measuring the number of pulse signals counted during one rotation of the reference point on the tire for each rotation, and averaging them. Further, "PD" is the number of pulse signals in one rotation of the drum. The drum circumference is constant, and the pulse signal PD for one rotation of the drum is preset according to the encoder.

Average .omega.T _average tire angular velocity, obtained as an average value over the tire circumference of the tire angular velocity .omega.T. In particular, it is preferable to rotate the tire a plurality of times, calculate the average value of the tire angular velocities for each rotation, and average them to obtain the ωT _average . The average .omega.D _average drum angular velocity is also similar, obtained as an average value over the drum circumference of the drum angular velocity .omega.D.

The difference ωD _difference from the average value of the differences ωT _difference, and the drum angular velocity from the mean value of the tire angular velocity, the following equation (6), obtained from (7).
ωT _difference =ωT−ωT _average −−−(6)
ωD _difference =ωD−ωD _average −−−(7)

In the above formula (1), a brief description will be given.
Between the tire and drum, RT = RD × ωD _Average / .omega.T _average relationship is established. Then, the right side of the equation (1) is obtained by multiplying both sides by the following equation (8).
1+ (.omega.D _difference / .omega.D _average) - (.omega.T _difference / .omega.T _average) --- (8)

Expression (8) means the rate of change of the tire angular velocity corrected by the rate of change of the drum angular velocity. The left side obtained by multiplying the tire radius RT by the equation (8) can be substituted for the tire rolling radius variation IRR.

Here, the tire rolling radius variation IRR obtained in step S1A may include an error component other than the tire, such as an eccentric component of the tire shaft. Therefore, in this example, it is preferable to perform a correction step for correcting the error component.

In the correction step, for example, one of the tires used in the setting step S1 is mounted with a tire mounting angle different from the machine, for example, 0°, 90°, 180°, 360°, In, the tire rolling radius variation IRR is calculated respectively. Then, the tire-side component can be removed by averaging the obtained waveforms of the tire rolling radius variation IRR for four times, and the error component other than the tire can be extracted. It should be noted that the number of divisions of the mounting angle may be any integer other than 4 as long as it is an equal division of 360 degrees.

By subtracting the error component obtained in this correction step from each tire rolling radius variation IRR obtained in step S1A, the tire rolling radius variation IRR can be obtained with higher accuracy.

Further, the data of the tire rolling radius variation IRR thus obtained is subjected to order analysis using a computer or the like, and the order component is calculated. The order component of the tire rolling radius variation IRR is also obtained as a vector quantity having a magnitude and a phase angle (angle from the reference position).

Next, in step S1B, an estimation formula for estimating the high speed FV is set based on each measurement value of the low speed parameter and the measurement value of the high speed FV obtained in step S1A. Specifically, the order component of the high speed FV has a correlation with the order component of the low speed RFV, the order component of the low speed RRO, the order component of the static unbalance SB, and the order component of the tire rolling radius variation IRR. Therefore, in the estimation formula, the fast FV is estimated by the sum of the vector amounts obtained by multiplying the parameters by the coefficients, as shown in the following formulas (2) and (3).

High-speed FV (primary)=a ₁ ×low-speed RFV (primary)+b ₁ ×low-speed RRO (primary)
+c ₁ ×static unbalance SB+d ₁ ×tire rolling radius variation IRR (primary) +e ₁
--- (2)
High-speed FV (n-th order)=a _n ×low-speed RFV (n-th order)+b _n ×low-speed RRO (n-th order)
+ _{D n} × tire rolling radius variation IRR (n order) + _{e n}
--- (3)

In the above equations (2) and (3), subscripts "1" and "n" indicate orders. Further, reference numeral _{a 1, b 1, c 1} , d 1, a n, b n, are both _{d n} is a coefficient. Since the static unbalance SB is a first-order vector, this term is removed in the equation (3) for estimating the high-speed FV of the second or higher order. Further, reference numeral _e 1, _{e n} is the bias, to compensate for such measurement errors.

A coefficient and a bias are set for each order in each estimation formula of the high-speed FV (RFV, TFV).

The coefficient and bias are determined by performing a multiple regression analysis so that the difference {Σ|Xmi-Xpi|} between the vector amount Xmi of the measured value of the high-speed FV and the vector amount Xpi of the estimated value of the high-speed RFV is minimized. (I is the number of samples).

Next, in the measuring step S2, the low speed RFV, the low speed RRO, the static unbalance SB, and the tire rolling radius variation IRR are measured for the tires of the above-mentioned type of which the high speed FV is unknown, and the required orders of these are measured. Component data is prepared.

The measurement of the low speed RFV, the low speed RRO, the static unbalance SB, and the tire rolling radius variation IRR can be performed by the same method as the measurement in step S1A of the setting step S1.

After that, the estimation step S3 estimates the high-speed FV based on the measurement result of the measurement step S2 and the estimation formula.

Although the particularly preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the illustrated embodiments and can be modified into various modes.

Based on the high-speed uniformity estimation method of the present invention, high-speed RFV and high-speed TFV were estimated for 10 pneumatic radial tires for passenger cars (size: 225/60R18, rim size 18×6.5J) of the same type.

In the setting step S1, ten tires of the same type were used for setting the estimation formula. In the measuring step S2, the low speed RFV, the low speed RRO, the static unbalance SB, and the tire rolling radius variation IRR are measured, and in the estimating step S3, the high speed RFV and the high speed TFV of the tire are measured based on the measurement results. Was estimated.

As a comparative example, the high speed RFV and the high speed TFV are estimated by using LRO instead of the tire rolling radius variation IRR in the low speed parameter.

The measurement conditions of each parameter are as follows.
・Tire internal pressure: 200 kPa
・Tire running speed when measuring low speed RFV, low speed RRO, and tire rolling radius fluctuation IRR: 7 km/h
・Traveling speed when measuring high-speed FV (RFV, TFV): 120km/h
・Vertical load when measuring RFV and TFV: 5.0kN

As shown in Table 1, in the estimation method of the embodiment, the correlation coefficient between the estimated value of the high-speed TFV and the measured value is larger than that of the estimation method of the comparative example in at least the first to third orders. It can be confirmed that high estimation accuracy can be exhibited.

Note that FIG. 2 is a graph in which the first to third estimated values of the high-speed TFV estimated by the estimation method of the embodiment are plotted on the horizontal axis and the measured values are plotted on the vertical axis. In addition, FIG. 3 is a graph in which the first to third estimated values of the high-speed TFV estimated by the estimation method of the comparative example are plotted on the horizontal axis and the measured values are plotted on the vertical axis.

S1 setting step S2 measurement step S3 estimation step

Claims (4)

A setting step for setting an estimation formula for estimating a high speed FV using low speed parameters including low speed RFV, low speed RRO, static unbalance SB, and tire rolling radius variation IRR for tires of the same type;
A measurement step of measuring a low speed RFV, a low speed RRO, a static unbalance SB, and a tire rolling radius fluctuation IRR for the tire of the above-mentioned type whose high speed FV is unknown.
A high speed uniformity estimation method for a tire, comprising: an estimation step of estimating a high speed FV based on a result of the measurement and the estimation formula. The tire high-speed uniformity estimation method according to claim 1, wherein the tire rolling radius variation IRR is obtained based on the following equation (1).
IRR = (RD × .omega.D _Average / .omega.T _average) × {1+ (.omega.D _difference / .omega.D _average) - (.omega.T _difference / .omega.T _average)} --- (1)
(In the formula,
RD: drum radius [m],
ωT _average : _Average tire angular velocity [rad/s],
ωT _difference : difference from the average value of tire angular velocity [rad/s],
ωD _average : _Average drum angular velocity [rad/s],
ωD _difference : difference from the average value of drum angular velocity [rad/s],
Is. ) The high speed uniformity estimation method for a tire according to claim 1, wherein the high speed FV is a high speed RFV or a high speed TFV. The high speed FV of the tire according to claim 3, wherein the first-order estimation formula of the high-speed FV is represented by the following formula (2), and the n-th order (n>1) estimation formula is represented by the following formula (3). Uniformity estimation method.
High-speed FV (primary)=a ₁ ×low-speed RFV (primary)+b ₁ ×low-speed RRO (primary)
+c ₁ ×static unbalance SB+d ₁ ×tire rolling radius variation IRR (primary) +e ₁
--- (2)
High-speed FV (n-th order)=a _n ×low-speed RFV (n-th order)+b _n ×low-speed RRO (n-th order)
+ _{D n} × tire rolling radius variation IRR (n order) + _{e n}
--- (3)
_{(Wherein, a 1, b 1, c} 1, d 1, a n, b n, d n is the coefficient of each of the _{parameters, e 1,} e _n is the bias.)

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