JP7355628B2 - System, method and program for evaluating high-speed straight running stability of tires - Google Patents

Description

The present disclosure relates to a system, method, and program for evaluating the high-speed straight running stability of a tire.

In order to maintain good straight-line performance and ensure stability during high-speed driving, development of tires with excellent high-speed straight-line stability is underway. High-speed straight-line stability is also called on-center feel or high-speed neutral feel.

Conventionally, high-speed straight-line stability has been evaluated by the driver's sensory evaluation in actual driving tests using actual vehicles. However, in actual driving tests, it is not possible to efficiently evaluate a large number of test tires, and there are only a limited number of test courses where high-speed straight-line stability can be evaluated, so it is desirable to use quantitative evaluations using bench tests instead. There is.

Although Patent Document 1 describes a method for evaluating the straight-line stability of a vehicle, it does not specifically disclose a method for quantitatively evaluating the high-speed straight-line stability of a tire using a bench test.

Japanese Patent Application Publication No. 2006-234774

An object of the present disclosure is to provide a system, method, and program for quantitatively evaluating the high-speed straight running stability of a tire using a bench test.

The system for evaluating the high-speed straight running stability of a tire according to the present disclosure includes:
an acquisition unit that acquires measured values by the bench test device;
a cornering stiffness calculation unit that uses the measured value to calculate a cornering stiffness CS (f) that takes into account a delay angle δ _CF of the cornering force CF with respect to the slip angle SA;
a steady gain calculation unit that calculates a yaw rate steady gain G _ψ (0) or a lateral acceleration steady gain G _A (0) using the cornering stiffness CS (f) calculated for each of the front tire and the rear tire;
an aligning torque stiffness calculation unit that calculates an aligning torque stiffness ATS(f) for the front tire using the measured value, taking into account a delay angle δ _SAT of the self-aligning torque SAT with respect to the slip angle SA;
Calculating a quantitative evaluation value G AT _/ ψ (s) as a ratio ATS (f)/G _ψ (0) of the aligning torque stiffness ATS (f) to the yaw rate steady gain G _ψ (0), or , quantitative evaluation value calculation of calculating a quantitative evaluation value G _{AT /A} (s) as the ratio ATS (f) of the aligning torque stiffness ATS (f) to the lateral acceleration steady gain G _A (0); It is equipped with a section and a section.
Note that "ψ・" represents the character "." attached above "ψ", and means the time differentiation of the yaw angle ψ.

The method of evaluating the high-speed straight running stability of the tire of the present disclosure includes:
The test tire is rolled on a bench test device to obtain the required measurement value,
Using the measured value, calculate the cornering stiffness CS (f) that takes into account the delay angle δ _CF of the cornering force CF with respect to the slip angle SA,
Using the cornering stiffness CS (f) calculated for each of the front tires and the rear tires, calculate the yaw rate steady gain G _ψ (0) or the lateral acceleration steady gain G _A (0),
Using the measured value, calculate the aligning torque stiffness ATS(f) for the front tire, taking into account the delay angle _δSAT of the self-aligning torque SAT with respect to the slip angle SA,
Calculating a quantitative evaluation value G AT _/ ψ (s) as a ratio ATS (f)/G _ψ (0) of the aligning torque stiffness ATS (f) to the yaw rate steady gain G _ψ (0), or , a quantitative evaluation value G _AT /A (s) is calculated as the ratio ATS (f)/G _A (0) of the aligning torque stiffness ATS (f) to the lateral acceleration steady gain G _A (0).

A block diagram showing a system for evaluating high-speed straight running stability of a tire in the present disclosure Flowchart showing an example of an evaluation processing routine executed by the system Flowchart showing another example of the evaluation processing routine executed by the system Graph showing an example of cornering force time series data Graph showing the correlation between sensory evaluation values and substitute quantitative evaluation values from actual driving tests

Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings.

[System for evaluating tire high-speed straight running stability]
The system 1 shown in FIG. 1 receives measured values measured by the bench test device 20, and calculates a quantitative evaluation value of high-speed straight running stability based on the measured values. The quantitative evaluation value calculated by System 1 is a substitute quantitative evaluation value that can be substituted for the sensory evaluation in the actual driving test. The quantitative evaluation values calculated by the system 1 include a quantitative evaluation value G _AT/ψ・(s) regarding the yaw rate of the vehicle, and/or a quantitative evaluation value G _AT/A ( s) is included. For convenience of notation, the character ``.'' above ``ψ'' is expressed as ``ψ・'', which means the time differential of the yaw angle ψ.

High-speed straight-line stability is understood as the response of the steering to the movement of the vehicle, and therefore can be evaluated as the steering torque relative to the yaw rate of the vehicle or the steering torque relative to the lateral acceleration of the vehicle. The quantitative evaluation value _GAT/ψ・(s) can be substituted for the evaluation value of the former (steering torque/yaw rate), and the quantitative evaluation value _GAT can be substituted for the evaluation value of the latter (steering torque/lateral acceleration). _/A (s). The higher these evaluation values, the more responsive the steering is to the vehicle's ease of movement, and the better the high-speed straight-line stability. Either method may be used, but for example, if the direction of the vehicle tends to change easily during actual driving tests, the quantitative evaluation value GAT _/ψ・(s) may be used to determine if the vehicle moves slightly laterally ( If there is a tendency to be swayed, it may be possible to adopt the quantitative evaluation value G _AT/A (s).

As described later, the quantitative evaluation value G _AT/ψ (s) is calculated as the ratio ATS (f)/G _ψ (0) of the aligning torque stiffness ATS (f) to the steady yaw rate gain G _ψ (0). be done. The quantitative evaluation value G _AT/A (s) is calculated as the ratio ATS(f)/G _A (0) of the aligning torque stiffness ATS(f) to the lateral acceleration steady gain G _A (0). This is because the yaw rate steady gain G _ψ・(0) or lateral acceleration steady gain G _A (0) is used as a measure of vehicle movement, and the aligning torque stiffness ATS(f) is used as a measure of steering response. .

As will be explained in detail later, the yaw rate steady gain G _ψ・(0) and the lateral acceleration steady gain G _A (0) respectively represent the cornering stiffness CS(f) of the front tire and the rear tire, and the vehicle characteristic value. It can be found using By considering both the front tires and the rear tires, quantitative evaluation values that are in relatively good agreement with actual driving tests can be obtained. The cornering stiffness CS(f) is calculated using the delay angle δ _CF , which will be described later, and is a measure of the responsiveness of the cornering force CF. The aligning torque stiffness ATS(f) is determined using the self-aligning torque SAT of the front tires. The aligning torque stiffness ATS(f) is calculated using the delay angle δ _SAT , which will be described later, and is a measure of the responsiveness of the self-aligning torque SAT.

The system 1 includes an acquisition unit 10 that acquires measured values by the bench test device 20, a cornering stiffness calculation unit 11, a steady gain calculation unit 12, an aligning torque stiffness calculation unit 13, and a quantitative evaluation value calculation unit 14. , an acquisition unit 15 that acquires vehicle characteristic values and the like. These units 10 to 15 are installed in software and hardware by the processor 2 executing a pre-stored evaluation processing routine (see FIGS. 2 and 3) in a computer equipped with a processor 2, a memory 3, various interfaces, etc. will be realized through collaboration.

The acquisition unit 10 acquires the measured value by the bench test device 20 through a user's operation or via a network. The acquisition unit 10 stores the acquired measurement value data (measurement data) in the memory 3. The bench test device 20 is configured as a cornering test device that drives the tire shaft while applying a predetermined test load and slip angle, and rolls the test tire on the test road surface. The bench testing device 20 is preferably a flat belt type cornering tester, but is not limited thereto, and may be other types of cornering testers such as a drum type or a flat plate type (flat table type).

The cornering stiffness calculation unit 11 uses the measurement value acquired by the acquisition unit 10 to calculate a cornering stiffness CS(f) that takes into account the delay angle δ _CF of the cornering force CF with respect to the slip angle SA. The steady gain calculation unit 12 calculates the yaw rate steady gain G _ψ (0) or the lateral acceleration steady gain G _A (0) using the cornering stiffness CS(f) calculated for each of the front tires and the rear tires. . The aligning torque stiffness calculation unit 13 uses the measurement value acquired by the acquisition unit 10 to calculate the aligning torque stiffness ATS(f), which takes into account the delay angle δ _SAT of the self-aligning torque SAT with respect to the slip angle SA. The quantitative evaluation value calculation unit 14 calculates the quantitative evaluation value G _AT/ψ· (s) as the ratio ATS(f)/G _ψ ·(0), or the ratio ATS(f)/G _A (0). Quantitative evaluation value G _AT/A (s) is calculated.

In the bench test (cornering test) using the bench test device 20, time series data of the cornering force CF and self-aligning torque SAT can be acquired. For the evaluation speed of the cornering test, the evaluation speed (traveling speed) of the actual running test, which is a substitute, such as 120 km/h or 160 km/h, is applied. FIG. 4 is a graph showing an example of time series data of cornering force CF. In this example, the slip angle SA is input as a sine wave. More specifically, one cycle includes steering to the left (or right) from a neutral state where the slip angle SA is zero, then steering to the right (or left) through the neutral state, and then returning to the neutral state again. Due to the continuous left and right steering, the slip angle SA changes continuously along a sine wave (sinusoidal curve). The magnitude of the input slip angle SA (amplitude of the slip angle SA) is preferably 1 degree or less, and more preferably about 0.5 degree.

ＳＡａｍｐ［ｒａｄ］は、スリップ角ＳＡの振幅である。ＣＦａｍｐ［Ｎ］は、コーナリングフォースＣＦの振幅である。遅れ角δ_ＣＦ［ｒａｄ］は、例えば正弦波のピーク間隔に基づいて取得される。 As shown in FIG. 4, the cornering force CF is delayed in phase with respect to the slip angle SA, and the phase shift of the cornering force CF with respect to the slip angle SA can be obtained as a delay angle δ _CF. The cornering stiffness calculation unit 11 can calculate the cornering stiffness CS(f) [N/rad] in which the delay angle δ _CF with respect to the slip angle SA is taken into account using the following equation (1). In this specification, units are shown in curly brackets.

SAamp[rad] is the amplitude of the slip angle SA. CFamp[N] is the amplitude of cornering force CF. The delay angle δ _CF [rad] is obtained, for example, based on the peak interval of the sine wave.

In this way, the cornering stiffness calculation unit 11 uses time-series data of the cornering force CF when the slip angle SA is input as a sine wave, and calculates the delay angle δ _CF based on the phase shift with respect to the slip angle SA. In the range shown in FIG. 4, the frequency of the slip angle SA (steering frequency) is constant, and the cornering stiffness CS(f) at that predetermined frequency (for example, 0.2 Hz) is determined. Such a frequency is preferably 0.5 Hz or less, more preferably 0.1 to 0.5 Hz, and still more preferably 0.1 to 0.3 Hz. This is because there are many frequency components of 0.5 Hz or less, and in particular, the level of frequency components of 0.1 to 0.3 Hz is high. This can be confirmed from the power spectrum of the steering angle when high-speed straight-line stability was evaluated in actual driving tests.

Ｌ［ｍ］は、車両のホイールベースである。Ｋ［ｒａｄ／ｍ］は、遅れ角δ_ＣＦを加味したスタビリティファクタであり、下記の式（３）によって算出される。Ｖ［ｍ／ｓｅｃ］は、台上試験の評価速度である。

ＣＳ_ｆ［Ｎ／ｒａｄ］は、前輪タイヤのコーナリングスティフネスＣＳ（ｆ）である。Ｆ_ｆ［Ｎ］は、前輪タイヤに作用するフロント荷重である。ＣＳ_ｒ［Ｎ／ｒａｄ］は、後輪タイヤのコーナリングスティフネスＣＳ（ｆ）である。Ｆ_ｒ［Ｎ］は、後輪タイヤに作用するリア荷重である。 The cornering stiffness calculation unit 11 calculates cornering stiffness CS(f) for each of the front tires and the rear tires. The steady gain calculation unit 12 uses the cornering stiffness CS(f) to calculate the yaw rate steady gain G _ψ· (0) or the lateral acceleration steady gain G _A (0). The steady gain calculation unit 12 can calculate the yaw rate steady gain G _ψ (0) using the following equations (2) and (3).

L[m] is the wheelbase of the vehicle. K [rad/m] is a stability factor that takes into account the delay angle δ _CF , and is calculated by the following equation (3). V [m/sec] is the evaluation speed of the bench test.

CS _f [N/rad] is the cornering stiffness CS (f) of the front tire. F _f [N] is the front load acting on the front tires. CS _r [N/rad] is the cornering stiffness CS (f) of the rear tire. F _r [N] is the rear load acting on the rear tires.

Further, the steady gain calculation unit 12 can calculate the lateral acceleration steady gain G _A (0) using the following equation (4) and the above equation (3). The steady gain calculation unit 12 may calculate at least one of the yaw rate steady gain G _ψ· (0) and the lateral acceleration steady gain G _A (0).

In this specification, the wheelbase L, speed V, front load _Ff , and rear load _Fr are collectively referred to as "vehicle characteristic values." Vehicle characteristic values can be obtained prior to bench testing. In this embodiment, vehicle characteristic values are obtained in advance and stored in the memory 3. The acquisition unit 15 acquires vehicle characteristic values through a user's operation or via a network, and stores the measurement data in the memory 3. Although the acquisition unit 15 is shown separately from the acquisition unit 10 in FIG. 1, they may be integrated into one, and therefore the acquisition unit 10 may also serve as the acquisition unit 15.

Although the frequency of the slip angle SA is constant in the range shown in FIG. 4, the cornering stiffness CS(f) may be calculated for each of a plurality of frequencies by changing this frequency. The preferred frequency range in this case is as described above, and is therefore preferably 0.5 Hz or less. The cornering stiffness calculation unit 11 can calculate the cornering stiffness CS(f) for each of a plurality of frequencies, weighted average it, and provide it to the steady-state gain calculation unit 12. Thereby, a quantitative evaluation value can be calculated using the cornering stiffness CS(f) that takes into account a plurality of frequencies, and high-speed straight running stability can be evaluated with higher accuracy.

The weighted average described above is preferably weighted according to the proportion of frequency components. As an example, five frequencies of 0.1Hz, 0.2Hz, 0.3Hz, 0.4Hz, and 0.5Hz are taken in 0.1Hz increments, the cornering stiffness CS (f) of each of them is calculated, and the steering angle is calculated. It is conceivable to calculate the final cornering stiffness CS(f) used by the steady-state gain calculation unit 12 by performing a weighted average process weighted with a weight according to the level of the power spectrum. The power spectrum of the steering angle can be obtained using an FFT (Fast Fourier Transform) analyzer or the like through an actual driving test.

ＳＡａｍｐ［ｒａｄ］は、式（１）と同じく、スリップ角ＳＡの振幅である。ＳＡＴａｍｐ［Ｎｍ］は、セルフアライニングトルクＳＡＴの振幅である。遅れ角δ_ＳＡＴ［ｒａｄ］は、例えば正弦波のピーク間隔に基づいて取得される。 The aligning torque stiffness calculation unit 13 calculates the aligning torque stiffness ATS(f) for the front tire, taking into account the delay angle δ _SAT of the self-aligning torque SAT with respect to the slip angle SA. The aligning torque stiffness calculation unit 13 uses time series data of the self-aligning torque SAT to calculate the delay angle δ _SAT based on the phase shift with respect to the slip angle SA. Time series data (not shown) of self-aligning torque SAT shows the same tendency as in FIG. 4, and aligning torque stiffness ATS(f) is calculated in the same manner as cornering stiffness CS(f). The aligning torque stiffness calculation unit 13 can calculate the aligning torque stiffness ATS(f) [Nm/rad] using the following equation (5).

SAamp[rad] is the amplitude of the slip angle SA, as in equation (1). SATamp[Nm] is the amplitude of the self-aligning torque SAT. The delay angle δ _SAT [rad] is obtained, for example, based on the peak interval of the sine wave.

式（６）の右辺において、分母にスリップ角ＳＡを乗じるとヨーレートと近い値になり、分子にスリップ角ＳＡを乗じると操作トルクと近い値になる。このように、定量評価値Ｇ_{ＡＴ／ψ・}（ｓ）は、ヨーレート（車両の動き）に対する操舵トルク（ステアリングの手応え）の比に相応するものとして、実走試験の評価に代用できる。 As described above, the quantitative evaluation value calculation unit 14 calculates the quantitative evaluation value G _AT/ψ· (s) regarding the yaw rate or the quantitative evaluation value G _AT/A (s) regarding the lateral acceleration. The quantitative evaluation value calculation unit 14 can calculate the quantitative evaluation value _GAT/ψ· (s) using the following equation (6).

On the right side of equation (6), multiplying the denominator by the slip angle SA results in a value close to the yaw rate, and multiplying the numerator by the slip angle SA results in a value close to the operating torque. In this way, the quantitative evaluation value G _AT/ψ· (s) can be used as a substitute for the evaluation in the actual driving test, as it corresponds to the ratio of the steering torque (steering response) to the yaw rate (movement of the vehicle).

式（７）の右辺において、分母にスリップ角ＳＡを乗じると横加速度と近い値になり、分子にスリップ角ＳＡを乗じると操作トルクと近い値になる。このように、定量評価値Ｇ_ＡＴ／Ａ（ｓ）は、横加速度（車両の動き）に対する操舵トルク（ステアリングの手応え）の比に相応するものとして、実走試験の評価に代用できる。 Further, the quantitative evaluation value calculation unit 14 can calculate the quantitative evaluation value G _AT/A (s) using the following equation (7).

On the right side of equation (7), multiplying the denominator by the slip angle SA results in a value close to the lateral acceleration, and multiplying the numerator by the slip angle SA results in a value close to the operating torque. In this way, the quantitative evaluation value G _AT/A (s) corresponds to the ratio of steering torque (steering response) to lateral acceleration (movement of the vehicle) and can be used as a substitute for evaluation in actual driving tests.

Although an example has been described in which time-series data is used when the slip angle SA is input as a sine wave, it is also possible to use time-series data when the slip angle SA is input as a triangular wave. In this case, the cornering stiffness calculation unit 11 calculates a frequency response function using time series data of the cornering force CF when the slip angle SA is input as a triangular wave, and calculates the cornering stiffness CS(f) as the real part of the frequency response function. Calculate. The calculated cornering stiffness CS(f) is provided to the steady gain calculation unit 12 in the same manner as described above.

When inputting the slip angle SA as a triangular wave in a bench test, it is preferable to include both steering to the left (left turn) and steering to the right (right turn) from the perspective of suppressing variations. It is more preferable to perform left and right steering multiple times and average them. Since various frequency components are included by inputting the slip angle SA as a triangular wave (impulse input), multiple frequency components (for example, 0.1Hz, 0.2Hz, 0.3Hz, 0.4Hz) are , 0.5Hz) frequency response functions are determined.

According to the time series data of the cornering force CF when the slip angle SA is input as a triangular wave, a frequency response function H(f) expressed by the following equation (8) can be obtained.
H(f)=CF(f)×SA ^* (f)/SA(f)×SA ^* (f)...(8)
CF(f) is the Fourier spectrum of the corner lifting force CF. SA(f) is the Fourier spectrum of the slip angle SA. SA ^* (f) is the complex conjugate of SA(f).
When this frequency response function H(f) is expressed as a complex number, the following equation (9) is obtained.
H _amp e ^iδ = Hr + Hi × i = H _amp × cos δ + H _amp × sin δ × i (9)
H _amp is the amplitude, Hr is the real part, Hi is the imaginary part, and i is the imaginary unit. The real part Hr corresponds to cornering stiffness, which is the product of the amplitude H _amp and cos δ. Therefore, this real part Hr becomes the cornering stiffness CS(f) in which the delay angle δ _CF is taken into account. Similarly, when using time-series data of the self-aligning torque SAT, the aligning torque stiffness ATS(f) can be calculated by adding the delay angle δ _SAT as the real part of the frequency response function.

When the slip angle SA is input as a triangular wave, the cornering stiffness CS(f) is calculated for each of a plurality of frequencies, so that the weighted average of these can be provided to the steady-state gain calculation unit 12. The weighted average is as described above. In addition, it is not always necessary to perform weighted averaging; similarly to the case where the slip angle SA is input as a sine wave, the cornering stiffness CS (f) at a predetermined frequency (for example, 0.2 Hz) is determined and it is calculated as the steady-state gain. It may also be provided to the calculation unit 12.

[Method of evaluating tire high-speed straight running stability]
A method for evaluating the high-speed straight running stability of a tire, which is performed by the system 1 of this embodiment, will be described with reference to FIGS. 2 and 3. FIG. 2 shows a processing routine when the slip angle SA is input as a sine wave. FIG. 3 shows a processing routine when the slip angle SA is input as a triangular wave. These methods are executed by one or more processors included in the system 1.

In the processing routine shown in FIG. 2, first, a test tire is rolled by the bench testing device 20 to obtain a required measurement value (step S1). Specifically, a cornering test is performed in which the test tire is rolled while giving a slip angle SA, and time series data of the cornering force CF and self-aligning torque SAT are obtained. This step is performed by the acquisition unit 10 of the system 1.

Next, using the measurement value obtained in step S1, cornering stiffness CS(f) is calculated using the above equation (1), taking into account the delay angle δ _CF of cornering force CF with respect to slip angle SA (step S2). . This step is performed by the cornering stiffness calculation unit 11 of the system 1. The cornering stiffness calculation unit 11 calculates cornering stiffness CS(f) for each of the front tires and the rear tires. As described above, the cornering stiffness CS(f) at a predetermined frequency may be calculated, or the cornering stiffness CS(f) may be calculated for each of a plurality of frequencies and weighted averaged.

Next, using the cornering stiffness CS(f) calculated for each of the front tires and the rear tires, the yaw rate steady gain G _ψ・(0) or lateral acceleration steady gain is determined by the above equations (2) to (4). G _A (0) is calculated (step S3). These calculations use vehicle characteristic values (wheelbase L, speed V, front load F _f and rear load F _r ) that can be obtained in advance. This step is performed by the steady-state gain calculation unit 12 of the system 1.

In addition, using the measured value obtained in step S1, the aligning torque stiffness ATS(f) is calculated using the above equation (5) for the front tire, taking into account the delay angle δ _SAT of the self-aligning torque SAT with respect to the slip angle SA. is calculated (step S4). This step is performed by the aligning torque stiffness calculation unit 13 of the system 1. Step S4 may be performed prior to step S2 and/or step S3.

Then, using the calculated values calculated in step S3 and step S4, the quantitative evaluation value G _AT/ψ (s) is calculated as the ratio ATS (f)/G _ψ (0) using the above equation (6). Alternatively, the quantitative evaluation value G _AT/ A (s) is calculated as the ratio ATS (f)/G _A (0) using the above equation (7) (step S5). This step is performed by the quantitative evaluation value calculation unit 14 of the system 1.

In the processing routine shown in FIG. 3, the frequency response functions of the slip angle SA and cornering force CF are determined using the measured values obtained in step S1, and the cornering stiffness CS(f) is calculated as the real part of the frequency response function ( Step S2'). Further, a frequency response function of the slip angle SA and self-aligning torque SAT is determined, and an aligning torque stiffness ATS(f) is calculated as the real part of the frequency response function (step S4'). The other steps S1, S3, and S5 are the same as the processing routine shown in FIG. 2, so their explanation will be omitted.

FIG. 5 is a graph showing the correlation between the sensory evaluation value and the substitute quantitative evaluation value based on the actual running test. The test tire is a pneumatic passenger car tire with a tire size of 225/50VR16. The horizontal axis is the quantitative evaluation value G _AT/ψ· (s) (=ATS(f)/G _ψ· (0)) calculated by the process shown in FIG. The vertical axis shows the sensory evaluation of high-speed straight-line stability in an actual driving test as the difference between the score and the standard tire (control) indicated by one of the plots (for example, a black triangle). Another difference is the sensory evaluation difference. By creating the regression formula RF, it is possible to predict the score of the actual driving test based on the results of the bench test (ie, the quantitative evaluation value G _{AT /ψ·} (s)). The same applies to the case where the quantitative evaluation value G _AT/A (s) is calculated.

As described above, the system 1 for evaluating the high-speed straight running stability of the tire of this embodiment is as follows:
an acquisition unit 10 that acquires measured values by the bench test device 20;
a cornering stiffness calculation unit 11 that uses the measured value to calculate a cornering stiffness CS (f) that takes into account the delay angle δ _CF of the cornering force CF with respect to the slip angle SA;
A steady gain calculation unit 12 that calculates a yaw rate steady gain G _{ψ (} 0) or a lateral acceleration steady gain G _A (0) using the cornering stiffness CS (f) calculated for each of the front tires and the rear tires;
an aligning torque stiffness calculation unit 13 that uses the measured values to calculate an aligning torque stiffness ATS(f) for the front tire, taking into account a delay angle δ _SAT of the self-aligning torque SAT with respect to the slip angle SA;
Calculate the quantitative evaluation value G AT _/ψ (s) as the ratio ATS (f)/G _ψ (0) of the aligning torque stiffness ATS (f) to the steady yaw rate _{gain G ψ} (0), or a quantitative evaluation value calculation unit 14 that calculates a quantitative evaluation value G AT/ _A (s) as a ratio ATS (f)/G _A (0) of aligning torque stiffness ATS (f) to acceleration steady gain G _A (0); , is provided.
This makes it possible to quantitatively evaluate the high-speed straight running stability of the tire through a bench test.

In one aspect, the cornering stiffness calculation unit 11 uses time series data of the cornering force CF when the slip angle SA is input in the form of a sine wave, and calculates the delay angle δ _CF based on the phase shift with respect to the slip angle SA. In another aspect, the cornering stiffness calculation unit 11 calculates a frequency response function using time series data of the cornering force CF when the slip angle SA is input as a triangular wave, and calculates the cornering stiffness as the real part of the frequency response function. Calculate CS(f).

The cornering stiffness calculation unit 11 may calculate the cornering stiffness CS(f) at a predetermined frequency (for example, 0.2 Hz) and provide it to the steady-state gain calculation unit 12. Further, the cornering stiffness calculation unit 11 calculates cornering stiffness CS(f) for each of a plurality of frequencies (for example, 0.1 Hz, 0.2 Hz, 0.3 Hz, 0.4 Hz, 0.5 Hz) and weighted averages the calculated cornering stiffness CS(f). , it may be provided to the steady-state gain calculation section 12. In this case, a quantitative evaluation value is calculated using cornering stiffness CS(f) that takes into account a plurality of frequencies, and high-speed straight running stability can be evaluated with higher accuracy.

Furthermore, the method for evaluating the high-speed straight running stability of the tire of this embodiment is as follows:
The test tire is rolled by the bench test device 20 to obtain the required measurement value,
Using the measured value, calculate the cornering stiffness CS (f) that takes into account the delay angle δ _CF of the cornering force CF with respect to the slip angle SA,
Using the cornering stiffness CS (f) calculated for each of the front tires and the rear tires, calculate the yaw rate steady gain G _ψ (0) or the lateral acceleration steady gain G _A (0),
Using the measured values, calculate the aligning torque stiffness ATS(f) for the front tire, taking into account the delay angle _δSAT of the self-aligning torque SAT with respect to the slip angle SA,
Calculate the quantitative evaluation value G AT _/ψ (s) as the ratio ATS (f)/G _ψ (0) of the aligning torque stiffness ATS (f) to the steady yaw rate _{gain G ψ} (0), or A quantitative evaluation value G AT/ _A (s) is calculated as the ratio ATS (f)/G _A (0) of aligning torque stiffness ATS (f) to acceleration steady gain G _A (0).
This makes it possible to quantitatively evaluate the high-speed straight running stability of the tire through a bench test.

In one aspect, when calculating the cornering stiffness CS(f), time series data of the cornering force CF when the slip angle SA is input as a sine wave is used to calculate the delay angle based on the phase shift with respect to the slip angle SA. Find δ _CF. In another aspect, when calculating the cornering stiffness CS (f), a frequency response function is obtained using time series data of the cornering force CF when the slip angle SA is input as a triangular wave, and the frequency response function is The cornering stiffness CS(f) is calculated as a real part.

When calculating the cornering stiffness CS (f), calculate the cornering stiffness CS (f) at a predetermined frequency (for example, 0.2 Hz) and apply it to the next step (yaw rate steady gain G _ψ (0) or lateral The step of calculating the acceleration steady-state gain G _A (0)) may be performed. Furthermore, when calculating the cornering stiffness CS(f), the cornering stiffness CS(f) is calculated for each of multiple frequencies (for example, 0.1Hz, 0.2Hz, 0.3Hz, 0.4Hz, 0.5Hz). It may be calculated, weighted averaged, and used in the next step. In this case, a quantitative evaluation value is calculated using cornering stiffness CS(f) that takes into account a plurality of frequencies, and high-speed straight running stability can be evaluated with higher accuracy.

The program according to this embodiment is a program that causes one or more processors to execute the above method. By executing this program, it is also possible to obtain the effects of the above method. In other words, it can be said that the above method is used.

Although the embodiments of the present disclosure have been described above based on the drawings, it should be understood that the specific configuration is not limited to these embodiments. The scope of the present disclosure is indicated not only by the description of the embodiments described above but also by the claims, and further includes all changes within the meaning and scope equivalent to the claims.

For example, the execution order of each process, such as the operation, procedure, step, and stage of the apparatus, system, program, and method shown in the claims, specification, and drawings, is based on the output of the previous process and the subsequent process. They can be implemented in any order unless used in Even if the claims, specification, and flows in the drawings are explained using "first" or "next" for convenience, this does not mean that the steps must be executed in this order.

For example, each of the units 10 to 15 shown in FIG. 1 is realized by executing a predetermined program on a CPU of a computer, but each unit may be configured with a dedicated circuit. In this embodiment, the processor in one computer implements each unit 10 to 15, but they may be distributed and implemented in at least one or more processors.

It is possible to apply the structure adopted in each of the above embodiments to any other embodiment. The specific configuration of each part is not limited to the embodiment described above, and various modifications can be made without departing from the spirit of the present disclosure.

DESCRIPTION OF SYMBOLS 1... System, 10... Acquisition part, 11... Cornering stiffness calculation part, 12... Steady-state gain calculation part, 13... Aligning torque stiffness calculation part, 14... Quantitative evaluation value calculation Part, 20...Bench test device

Claims (9)

an acquisition unit that acquires time-series data of slip angle SA, cornering force CF, and self-aligning torque SAT when the slip angle SA is continuously changed, which are measured values using a bench testing device;
a cornering stiffness calculation unit that uses the measured value to calculate a cornering stiffness CS (f) that takes into account a delay angle δCF of cornering force CF with respect to slip angle SA;
a steady gain calculation unit that calculates a yaw rate steady gain Gψ(0) or a lateral acceleration steady gain GA(0) using the cornering stiffness CS(f) calculated for each of the front tire and the rear tire;
an aligning torque stiffness calculation unit that calculates an aligning torque stiffness ATS(f) for the front tire using the measured value, taking into account a delay angle δSAT of the self-aligning torque SAT with respect to the slip angle SA;
A quantitative evaluation value GAT/ψ(s) is calculated as the ratio ATS(f)/Gψ(0) of the aligning torque stiffness ATS(f) to the yaw rate steady gain Gψ(0), or the lateral a quantitative evaluation value calculation unit that calculates a quantitative evaluation value GAT/A(s) as a ratio ATS(f)/GA(0) of the aligning torque stiffness ATS(f) to acceleration steady-state gain GA(0);
A system that evaluates the high-speed straight-line stability of tires. The cornering stiffness calculation unit calculates the delay angle δCF based on the phase shift with respect to the slip angle SA using time series data of the cornering force CF when the slip angle SA is continuously changed along a sine wave. 2. The system of claim 1, wherein the system determines. The cornering stiffness calculation unit calculates a frequency response function using time series data of cornering force CF when the slip angle SA is continuously changed along a triangular wave, and calculates the cornering stiffness as a real part of the frequency response function. The system of claim 1, which calculates CS(f). When the acquisition unit acquires a plurality of the time series data by changing the frequency of the slip angle SA, the cornering stiffness calculation unit calculates and weights the cornering stiffness CS(f) for each of the plurality of frequencies. The system according to any one of claims 1 to 3, wherein the average is averaged and the average is provided to the steady-state gain calculation unit. Obtain time-series data of slip angle SA, cornering force CF, and self-aligning torque SAT when the test tire is rolled on a bench test device and the slip angle SA is continuously changed as required measurement values. death,
Using the measured value, calculate the cornering stiffness CS (f) that takes into account the delay angle δCF of the cornering force CF with respect to the slip angle SA,
Using the cornering stiffness CS (f) calculated for each of the front tires and the rear tires, calculate the yaw rate steady gain Gψ (0) or the lateral acceleration steady gain GA (0),
Using the measured value, calculate the aligning torque stiffness ATS(f) for the front tire, taking into account the delay angle δSAT of the self-aligning torque SAT with respect to the slip angle SA,
A quantitative evaluation value GAT/ψ(s) is calculated as the ratio ATS(f)/Gψ(0) of the aligning torque stiffness ATS(f) to the yaw rate steady gain Gψ(0), or the lateral Calculating a quantitative evaluation value GAT/A(s) as a ratio ATS(f)/GA(0) of the aligning torque stiffness ATS(f) to acceleration steady gain GA(0);
A method to evaluate the high-speed straight-line stability of tires. When calculating the cornering stiffness CS (f), time series data of the cornering force CF when the slip angle SA is continuously changed along a sine wave is used to calculate the cornering stiffness CS (f) based on the phase shift with respect to the slip angle SA. 6. The method according to claim 5, wherein the delay angle δCF is determined by When calculating the cornering stiffness CS (f), a frequency response function is obtained using time series data of the cornering force CF when the slip angle SA is continuously changed along a triangular wave, and the frequency response function is 6. The method according to claim 5, wherein the cornering stiffness CS(f) is calculated as a real part. When calculating the cornering stiffness CS (f) by changing the frequency of the slip angle SA and acquiring a plurality of the time series data, the cornering stiffness CS (f) is calculated for each of the plural frequencies. The method according to any one of claims 5 to 7, comprising weighted averaging. A program that causes one or more processors to execute the method according to any one of claims 5 to 8.

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