JP2007278917A - Method and device for evaluating cornering dynamic characteristics of tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for evaluating cornering dynamic characteristics of a tire for quantitatively and precisely evaluating inherent cornering dynamic characteristics of the tire in a distance frequency of a comparatively wide range expressed by the frequency of a slip angle input in the tire and a moving speed of the tire. <P>SOLUTION: In a plurality of input distance frequencies PF(rad/m) expressed by a rolling speed (m/s) of the tire and a plurality of slip angle frequencies f(rad/m) input in the tire, the minimum value PF<SB>1</SB>of at least the input distance frequency satisfies PF<SB>1</SB>≤0.03(rad/m), and obtained dynamic characteristic frequency information is obtained by finding the dynamic characteristic frequency information of the cornering dynamic characteristics to the distance frequency expressed by the frequency of the slip angle and the rolling speed of the tire in a state where the rolling speed and the frequency of the slip angle are set so that the maximum value PF<SB>2</SB>of at least the input distance frequency satisfies 10.0(rad/m)≤PF<SB>2</SB>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tire cornering dynamic characteristic evaluation method and apparatus, and more particularly to a method and apparatus for quantitatively evaluating a transient response characteristic of a cornering force generated in a tire when a slip angle input is given to the tire. .

  Nowadays, in response to the improvement in the performance of automobiles, the driving performance required for the mounted tire is also required to be improved. The tire cornering dynamic characteristic, which is a characteristic related to the response characteristic at the time of early steering of the automobile, greatly contributes to the steering performance of the tire when the tire is mounted on the vehicle. The cornering dynamic characteristics of a tire are frequency response characteristics such as tire lateral force, cornering force, and self-aligning torque with respect to inputs to the tire such as load, slip angle, camber angle, and slip ratio when the tire is steered quickly. It is a characteristic represented. In recent years, with the demand for the development of high-performance tires, there is a need for a method and apparatus that can quantitatively and accurately evaluate cornering dynamic characteristics unique to tires.

  High-performance tires, for example, when the tire is steered quickly while the vehicle is traveling at low speed, or when the tire is steered quickly while the vehicle is traveling at high speed, or when the vehicle is traveling at low speed, Therefore, it is required to obtain desired steering stability in all steering states during traveling of any vehicle, such as when the vehicle is steered at a high speed or when the tire is gently steered while the vehicle is traveling at high speed. When developing a high-performance tire, it is required to quantitatively and accurately evaluate the tire cornering dynamic characteristics in all the steering states in all vehicle traveling conditions.

  Conventionally, evaluation of such cornering dynamic characteristics has been performed using a known indoor cornering tester having a tire contact surface of a drum type or a flat belt type, for example. As an evaluation of the cornering dynamic characteristics performed using such a cornering tester, for example, the tire is rolled on the ground surface at a constant rolling speed, and a plurality of different slip angle inputs are given to the tire. The cornering force frequency response characteristic at this rolling speed was obtained, and the cornering dynamic characteristic unique to the tire was evaluated from the frequency response characteristic of the cornering force at this rolling speed.

In addition, for example, when a vehicle is driven on an actual road surface (actual road) and steering input is given, time series data of tire slip angles associated with steering input and time series data of tire cornering force (lateral force) are provided. Patent Literature 1 below describes a method of obtaining the cornering force frequency response characteristic with respect to slip angle input and calculating the cornering power of the tire using the cornering force frequency response characteristic.
JP 2004-276632 A

  In the method of rolling the tire at a constant speed using the above-described indoor cornering tester and evaluating the cornering dynamic characteristic unique to the tire from the frequency response characteristic of the cornering force at this rolling speed, Since the frequency range of steering (ie, slip angle) that can be input to the tire is determined according to the specific conditions, only the range of the driving state that is reproduced at this constant speed and the limited frequency range is the cornering force. Frequency response characteristics could not be obtained. Further, in the method of obtaining the cornering force frequency response characteristic for the slip angle input by driving the vehicle on the actual road surface (actual road) and giving the steering input, the driver himself / herself driving the vehicle gives the steering input. It is difficult to accurately input the slip angle at a desired frequency, and there is a limit to the frequency range of the slip angle that can be input. In addition, it was difficult to always maintain an accurate traveling speed. Also in this case, it has been difficult to accurately evaluate the entire steering state in all vehicle traveling conditions and quantitatively evaluate the cornering dynamic characteristics in each case.

  Accordingly, in order to solve the above-described problems, the present invention provides a tire cornering motion capable of quantitatively and accurately evaluating tire-specific cornering dynamic characteristics in all steering states in all vehicle traveling conditions. It is an object to provide a characteristic evaluation method and apparatus.

In order to solve the above problems, the present invention provides a method for evaluating cornering dynamic characteristics of a tire, wherein the tire is grounded on a contact surface and the tire is rolled at a predetermined rolling speed. A plurality of slip angle inputs having different frequencies are sequentially given to obtain a plurality of cornering dynamic characteristic output signals corresponding to the slip angle inputs, time series data of the slip angles inputted in the measurement step, and the measurement Using the time-series data of the output signal obtained in step, the dynamic characteristic frequency information of the cornering dynamic characteristic with respect to the distance frequency represented by the frequency of the slip angle and the rolling speed of the tire, An analysis step for outputting the obtained dynamic characteristic frequency information, and in the measurement step, the predetermined rolling speed V (m / s) of the tire; Serial slip angle input of a plurality of said frequency f and (rad / s), in the plurality of input distance frequencies PF (rad / m) represented, at least the input distance frequency minimum value PF ₁ is the following formula (1) And the plurality of frequencies of the predetermined rolling speed and the slip angle are set so that at least the maximum value PF ₂ of the input distance frequency satisfies the following formula (2): The present invention provides a tire cornering dynamic characteristic evaluation method characterized by obtaining a cornering dynamic characteristic output signal.
PF ₁ ≦ 0.03 (rad / m) (1)
10.0 (rad / m) ≦ PF ₂ (2)

In the present invention, prior to the measuring step, the input distance frequency range is expressed by the above formula (1) in a state where the frequencies of the plurality of slip angle inputs given to the tire are all set within a certain frequency range. And a setting step of setting a plurality of rolling speeds of the tire so as to satisfy the above formula (2),
In the measurement step, the tire is rolled at each of the plurality of rolling speeds set in the setting step, and slip angle inputs of the plurality of frequencies are sequentially given for each of the rolling speeds. A plurality of cornering dynamic characteristic output signals corresponding to the slip angle input are obtained, and in the analysis step, the time series data of the slip angle and the time series data of the output signal obtained in the measurement step, respectively, at each rolling speed And obtaining the dynamic characteristic frequency information of the cornering dynamic characteristic corresponding to the distance frequency in each rolling speed, and integrating the dynamic characteristic frequency information of each rolling speed, thereby obtaining the above equation (1). And dynamic characteristic frequency information expressed over the input distance frequency range satisfying the above expression (2).

  Further, when setting a plurality of rolling speeds of the tire in the setting step, at least a part of each range of the distance frequency at each rolling speed is at least a range of the distance frequency at one different rolling speed. It is preferable to set a plurality of rolling speeds so as to overlap.

  In addition, when integrating the dynamic characteristic frequency information of each rolling speed in the analysis step, the gain value of the dynamic characteristic frequency information of the cornering dynamic characteristic of each rolling speed is within the overlapping range of the distance frequency. It is preferable that the dynamic characteristic frequency information of each rolling speed is integrated so as to substantially match.

  In addition, when integrating the dynamic characteristic frequency information of each rolling speed in the analysis step, based on the cornering dynamic characteristic information when the distance frequency is 0 (rad / m), It is preferable to integrate the dynamic characteristic frequency information.

  And a parameter identification step of identifying a parameter of a transfer function representing a response of the cornering dynamic characteristic with respect to the distance frequency as a first-order lag system based on the dynamic characteristic frequency information obtained in the analyzing step. preferable.

ｓ：ラプラス演算子
ＣＦ：コーナリングフォース（Ｎ）
β：スリップ角（ｒａｄ）
Ｖ：タイヤの転動速度（ｍ／ｓ）
Ｋ：タイヤの等価横剛性（Ｎ／ｍ）
ＣＰ：コーナリングフォースの応答（Ｎ／ｒａｄ） The cornering dynamic characteristic output signal is a signal representing a cornering force of the tire corresponding to the slip angle input, and in the parameter identification step, a response of the cornering force with respect to the distance frequency is represented as a first-order lag system below. It is preferable to identify a parameter of the transfer function based on the dynamic characteristic frequency information obtained in the analysis step using a transfer function G (s) shown in Expression (3).

s: Laplace operator CF: Cornering force (N)
β: slip angle (rad)
V: Rolling speed of tire (m / s)
K: Equivalent lateral stiffness of tire (N / m)
CP: Cornering Force Response (N / rad)

  Furthermore, it is preferable to obtain a time constant of the transfer function representing a transient response characteristic of the cornering dynamic characteristic as an evaluation value of the cornering dynamic characteristic.

The present invention is also a tire cornering dynamic characteristic evaluation apparatus, wherein a plurality of slips having different frequencies are applied to the tire in a state where the tire is grounded on a contact surface and the tire is rolled at a predetermined rolling speed. Measuring means for sequentially giving angular inputs to obtain a plurality of cornering dynamic characteristic output signals corresponding to the slip angle input, time-series data of the slip angles inputted by the measuring means, and the output obtained by the measuring means Analyzing means for obtaining and outputting dynamic characteristic frequency information of the cornering dynamic characteristic with respect to a distance frequency represented by the frequency of the slip angle and the rolling speed of the tire, using time series data of the signal, And the measurement means includes a plurality of the rolling speed V (m / s) of the tire and a plurality of the frequencies f (rad / s) of the slip angle input. About the power distance frequencies PF (rad / m), the lowest value PF ₁ of at least the input distance frequencies satisfies the above formula (1), and the maximum value PF ₂ of at least the input distance frequencies satisfies the above formula (2) The tire cornering dynamic characteristic evaluation apparatus is characterized in that the plurality of cornering dynamic characteristic output signals are obtained in a state where the predetermined rolling speed and the plurality of slip angles are set. To provide.

  According to the tire cornering dynamic characteristic evaluation method and apparatus of the present invention, the cornering motion specific to the tire is detected in a relatively wide range of distance frequencies represented by the frequency of the slip angle input to the tire and the rolling speed of the tire. Characteristics can be evaluated quantitatively with high accuracy. This makes it possible to quantitatively and accurately evaluate tire-specific cornering dynamics for various steering states in various vehicle driving conditions.

  Hereinafter, a tire cornering dynamic characteristic evaluation method and apparatus will be described in detail based on a preferred embodiment shown in the accompanying drawings.

  FIG. 1 is a schematic configuration diagram illustrating a cornering force characteristic evaluation apparatus 10 (apparatus 10) that is an example of the cornering dynamic characteristic evaluation of a tire according to the present invention. FIG. 1 uses the apparatus 10. The case where the transient response characteristic of the cornering force is quantitatively evaluated for the tire 12 as the measurement target tire is shown. The apparatus 10 includes a cornering tester 14 and a measurement / evaluation unit 16. A display 18 is connected to the measurement / evaluation unit 16.

  The cornering tester 14 grounds the tire 12 rotatably supported on the tire shaft 22 on the substitute road surface 24 that is the surface of the belt 20 and rotates the belt 20 to thereby cause the tire 12 to rotate on the substitute road surface of the belt 20. 24 is a well-known flat belt type indoor testing machine that travels (rolls) on 24. In the cornering tester 14 of this embodiment, a plurality of slip angle inputs having different frequencies are sequentially given to the tire 12 traveling on the substitute road surface 24, and a plurality of cornering forces corresponding to the slip angle input are measured. To do. In the present embodiment, the slip angle is input in a relatively small slip angle range, and the cornering force transient response characteristic of the measurement target tire 12, particularly in the vicinity of the so-called steering neutral, where the slip angle is relatively small is quantitatively determined. The evaluation value represented by is calculated.

  The belt 20 is wound around the roller pair 28. The roller pair 28 is connected to a drive unit 26 having a motor (not shown). The roller pair 28 is rotated by the motor of the drive unit 26 and the substitute road surface 24 of the belt 20 moves. It has become. The drive unit 26 is connected to the measurement means 40 described later of the measurement / evaluation unit 16.

  The tire shaft 22 is provided on the tire shaft support member 32. The tire shaft support member 32 is configured to be rotationally driven around the Z axis in FIG. 1 by a slip angle adjusting actuator 29 (hereinafter referred to as slip angle adjusting means 29) which is a slip angle adjusting means. The Z axis in FIG. 1 is a straight line on the equator plane of the tire 12 that is perpendicular to the rotation center axis of the tire 12 (that is, the center of the tire axis 22). The tire shaft support member 32 is driven to rotate around the Z axis in FIG. 1, so that the slip angle of the rolling tire 12 (the rolling direction of the tire 12, that is, the moving direction of the substitute road surface 24, and the equator plane of the tire 12). The angle formed by the angle is changed. The slip angle adjusting means 29 is connected to the measuring means 40 described later of the measurement / evaluation unit 16.

  The tire shaft support member 32 is also provided with a sensor 34 that can measure the force applied to the tire shaft 22. The sensor 34 measures force in the direction perpendicular to the tire equatorial plane on the tire shaft 22 (force in the Y-axis direction in FIG. 1), that is, tire lateral force. Since the cornering tester 14 inputs the slip angle in a relatively small slip angle range, the lateral force generated in the tire 12 is the cornering force generated in the tire 12 (force in a direction perpendicular to the moving direction of the substitute road surface 24). Is almost equal to Hereinafter, the lateral force generated in the tire 12 measured by the sensor 34 is treated as equivalent to the cornering force generated in the tire 12. The sensor 34 may be any device that can measure at least the cornering force applied to the tire shaft 22 such as a device using a piezoelectric element or a strain gauge, and is not particularly limited. The tire shaft support member 32 is connected to load load means (not shown), and a tire supported by the tire shaft 22 by applying a predetermined load from the load load means during rolling of the tire 12. 12 is grounded to the substitute road surface 24 of the drum 20 with a predetermined ground load. The sensor 34 is connected to the measurement means 40 described later of the measurement / evaluation unit 16.

  The measurement / evaluation unit 16 includes a measurement unit 40 and an evaluation unit 50. FIG. 2 is a schematic configuration diagram for explaining the measurement / evaluation unit 16. The measurement / evaluation unit 16 includes a measurement unit 40, an evaluation unit 50, a CPU 17, and a memory 19. The measurement / evaluation unit 16 is a computer in which the units shown in the measurement unit 40 and the evaluation unit 50 function by the CPU 17 executing a program stored in the memory 19.

  The measuring unit 40 includes a condition setting unit 42, an operation control unit 44, and a data acquisition unit 46. The evaluation unit 50 includes a data processing unit 52, a data integration unit 54, a parameter identification unit 56, and an evaluation value calculation unit 58.

  The condition setting unit 42 of the measuring unit 40 is a part for setting a plurality of different slip angle input frequencies and rolling speed conditions of the tire 12 which are sequentially given to the tire 12 running on the substitute road surface 24.

When a small slip angle is given to a stopped tire and this tire is made to go straight slowly, the lateral force (ie, cornering force) generated in the tire generally changes as shown in the graph of FIG. Known to. That is, when is rolled on a road surface by applying a slip angle to the tire, cornering force generated in the tire, cornering force output response in accordance with the rolling distance, eventually it reaches a steady value CF _c such order lag It is represented by a system model. That is, when a slip angle that changes periodically is input to a tire that rolls at a predetermined rolling speed, the time frequency f (Hz = cycle / s = 2π rad / s) of the slip angle that is input to the tire and the tire rotation. The response of the cornering force generated in the tire to the distance frequency PF = f / v (cycle / m = 2π rad / m) represented by the dynamic speed v (m / s) can also be expressed as a first-order lag system. The measuring means 40 controls the operation of each part of the cornering tester 14 to input a periodically changing slip angle to the tire 12 that rolls at a predetermined rolling speed, and represents such a first-order lag system. Obtain an output signal of a cornering force that can be approximated.

The condition setting unit 42 is a part that sets the rolling speed of the tire 12 and the frequency of the slip angle that is input to the tire 12 when the cornering force output signal is acquired. The condition setting unit 42, the range of the distance frequency PF to be inputted, a minimum value PF ₁ of at least the input distance frequencies satisfies the following formula (1), and at least the maximum value PF ₂ is represented by the following formula in the input distance frequency (2 ) To set the rolling speed of the tire 12 and a plurality of frequencies of slip angles. The input distance frequency range is set so as to satisfy the following formula (1) and the following formula (2), for example, when the tire is steered quickly while the vehicle is traveling at a low speed and when the vehicle is traveling at a high speed. In addition to steering the tires quickly, in addition to slowly steering the tires while the vehicle is traveling at low speeds, and when gently steering the tires while the vehicle is traveling at high speeds, This is to obtain information on the response characteristics of the cornering force in any steering state while the vehicle is running, which can reproduce the output of the cornering force in the steering state.
PF ₁ ≦ 0.03 (rad / m) (1)
10.0 (rad / m) ≦ PF ₂ (2)

  Here, the slip angle input frequency is controlled by the slip angle adjusting means 29, but there is a limit to the frequency that can be input due to the ability of the actuator of the slip angle adjusting means 29. Therefore, in the condition setting unit 42, the frequency range of a plurality of slip angle inputs given to the tire is set to a frequency range (for example, 0.1 Hz to 5.0 Hz) that can be controlled with relatively high accuracy by the slip angle adjusting means 29. A plurality of rolling speeds of the tire 12 are set so that the range of the input distance frequency PF satisfies the above formula (1) and the above formula (2). At this time, the rolling speeds of the plurality of tires 12 may be set so that at least a part of each range of the distance frequency PF at each rolling speed overlaps at least a range of the distance frequency at one different rolling speed. preferable. For example, when the frequency range of the slip angle to be input is, for example, 0.1 Hz to 4.8 Hz, two rolling speeds of the tire 12 are set, for example, 10 km / h and 100 km / h. In this case, the range of the distance frequency of 0.2 rad / m to 1.0 rad / m overlaps when the rolling speed is 10 km / h and when the rolling speed is 100 km / h.

  The operation control unit 44 is a part that controls the operation of each unit of the cornering tester 14 based on the rolling speed of the tire 12 and a plurality of slip angle frequencies set by the condition setting unit 42. The operation control unit 44 is connected to the drive unit 26 and the slip angle adjusting means 29. The operation control unit 44 controls the operation of the drive unit 26 (such as the rotation speed of the motor) so that the tire 12 rolls at the rolling speed set by the condition setting unit 42. Further, the operation of the slip angle adjusting means 29 is also controlled so that the slip angle of the tire 12 changes at a plurality of slip angle frequencies set by the condition setting unit 42. Specifically, with the tire 12 rolling at the first rolling speed (for example, 10 km / h) set by the condition setting unit 42, a plurality of slip angular frequencies are sequentially input to the tire 12, and thereafter The cornering tester 44 repeats the operation of sequentially inputting a plurality of slip angular frequencies to the tire 12 while the tire 12 is rolling at the second rolling speed (for example, 100 km / h). Note that the time-series data of the slip angle to be input is also sequentially sent to the data processing unit 52 of the evaluation means 50.

  When the tire 12 is rolled at the set rolling speed, the data acquisition unit 46, when sequentially giving a plurality of slip angle inputs having different frequencies to the tire 12, the cornering force corresponding to the slip angle input. This is a part for obtaining a time-series output signal. The data acquisition unit 46 is connected to the sensor 34 and acquires the output signal of the cornering force generated in the tire output from the sensor 34 in time series. The acquired cornering force time-series output signal is sent to the data processing unit 52 of the evaluation means 50. 4A and 4B are examples of a plurality of slip angle input data input to the tire 12 and cornering force output time-series data acquired by the data acquisition unit 46, respectively. In the apparatus 10, slip angles of a plurality of such different frequencies are sequentially input to the tire 12, and cornering force output time-series data at each input frequency is acquired. In the present invention, the output signal to be acquired is not limited to the cornering force output signal, and for example, an output signal of a tire self-aligning torque may be acquired.

  The data processing unit 52 of the evaluation means 50 performs frequency analysis using the time series data of the input slip angle and the time series data of the output signal of the cornering force, and information on the frequency response of the cornering force with respect to the distance frequency. It is the part which asks. The data processing unit 52 uses, for example, a well-known FFT (Fast Fourier Transformation) method or the like with a predetermined frequency resolution (distance frequency resolution), for example, as shown in the Bode diagrams in FIGS. 5 (a) and 5 (b). The information of the amplitude ratio (gain) between the input slip angle information and the output cornering force information and the phase angle (phase delay) is obtained. In the data processing unit 52, the time series data of the input slip angle and the time series data of the output signal of the cornering force in the state where the tire 12 is rolling at the first rolling speed (for example, 10 km / h). The frequency analysis of the cornering force with respect to the distance frequency in a state where the tire 12 is rolled at the first rolling speed (for example, 10 km / h) (FIG. 5A) Ask for. Then, the time series data of the input slip angle and the time series data of the output signal of the cornering force in the state where the tire 12 is rolled at the second rolling speed (for example, 100 km / h) are used. The frequency analysis is performed, and information on the frequency response of the cornering force with respect to the distance frequency in a state where the tire 12 is rolled at the second rolling speed (for example, 100 km / h) is obtained (FIG. 5B). Repeat the above operations. Information on the frequency response of each rolling speed is sequentially stored in the memory 19. As an output signal to be acquired, for example, when an output signal of a tire self-aligning torque is acquired, information on the frequency response of the self-aligning torque may be obtained as in the case of the cornering force. In the present invention, the method for obtaining the frequency response information of the cornering force is not limited to FFT. For example, the amplitude ratio (gain) of the output cornering force information and the information on the phase angle (phase delay) may be obtained using a known sine curve fitting method.

  The data integration unit 54 of the evaluation means 50 determines the cornering force of each rolling speed so that the amplitude ratio (gain) of the frequency response of each cornering force of each rolling speed substantially matches in the overlapping range of distance frequencies. Integrate frequency response information. In the integration unit 54, each rolling is performed based on the frequency response information of the cornering force when the distance frequency is 0 (rad / m), in particular, the amplitude ratio (gain) information stored in advance in the memory 19. By integrating the frequency response information of the cornering force for each speed, the frequency response information (amplitude ratio) of the cornering force expressed over the range of the input distance frequency PF that satisfies the above formulas (1) and (2). (Gain) and phase angle (phase delay) information).

  As described above, the slip angle frequency that can be input has a limit due to the ability of the slip angle adjusting means 29, and in the condition setting unit 42, the range of the input distance frequency PF is the above formula (1) and the above formula ( 2) In order to satisfy 2), the rolling speeds of the plurality of tires 12 are set so that at least a part of the range of the distance frequency PF at each rolling speed overlaps the range of the distance frequency at at least one different rolling speed. did. For example, when the frequency range of the slip angle to be input is 0.1 Hz to 4.76 Hz, for example, when the rolling speed of the tire 12 is 10 km / h, the range of the input distance frequency PF is 0.226 rad. / M to 10.769 rad / m. When the rolling speed of the tire 12 is 100 km / h, for example, the range of the input distance frequency PF is 0.023 rad / m to 1.077 rad / m. The data integration unit 54 integrates the frequency response information of the cornering forces in different distance frequency ranges obtained at such different rolling speeds, and satisfies the above expression (1) and the above expression (2). Deriving information on the frequency response of the cornering force expressed over the range of the PF.

  The frequency response information (amplitude ratio (gain) and phase angle (phase lag)) of the cornering force at the same distance frequency, even if the frequency response information is obtained at different rolling speeds, If the tire characteristics do not change according to the speed, it should ideally be the same. However, the amplitude ratio (gain) and the phase angle (phase lag) differ depending on the rolling speed due to different tire speeds and different tire surface properties due to different rolling speeds. . In the integration unit 54, the frequency response of the cornering force obtained at each rolling speed based on the information on the cornering force when the distance frequency is 0 (rad / m), particularly the information on the amplitude ratio (gain) of the cornering force. Integrate information.

  FIG. 6 is a diagram for explaining information used in the data integration unit 54. The information is generated in the tire 12 with respect to the rolling speed of the tire 12 in a state where the input slip angle is 1 °, for example, and the load is fixed at 4200N. It is a scatter diagram showing the magnitude | size of a cornering force (CF) and a self-aligning torque (SAT). As shown in the graph of FIG. 6, the cornering force generated in the tire 12 and the self-aligning are greater when the rolling speed is 100 km / h than when the rolling speed is 10 km / h. The magnitude of torque is increasing. The magnitude of the cornering force at each speed shown in FIG. 6 is the gain when the frequency is 0 Hz of the frequency characteristic of the amplitude ratio (gain) of the cornering force at each speed shown in FIGS. 5 (a) and 5 (b). It corresponds to (steady gain). Similarly, the magnitude of the self-aligning torque at each speed shown in FIG. 6 is the frequency characteristic of the amplitude ratio (gain) of the self-aligning torque at each speed (the same amplitude characteristic as the above-mentioned cornering force). Corresponds to a gain (steady gain) when 0 is 0 Hz. Such fluctuations in gain based on changes in rolling speed at the same frequency (0 Hz) are caused by different tire temperatures and different tire surface physical properties at different rolling speeds. Is.

  Such steady gain information shown in FIG. 6 may be acquired in advance by the apparatus 10 and stored in the memory 19 of the measurement / evaluation unit 16 in advance. For example, in a state where the tire 12 is rolled at each set rolling speed, the tire 12 is rolled while maintaining a constant slip angle before inputting the variation of the slip angle to the tire 12, and the acquired tire 12. It is only necessary to memorize the size of the cornering force generated in the. The data integration unit 54 derives such a gain fluctuation rate that represents the ratio of the steady gain at each rolling speed. Then, using the value of the gain fluctuation rate, information on the frequency response of the amplitude ratio (gain) of the cornering force obtained at each rolling speed is integrated. For example, the gain fluctuation rate S / R, which is the ratio of the steady gain S (see FIG. 6) at the rolling speed of 10 km / h to the steady gain R (see FIG. 6) at the rolling speed of 100 km / h, is obtained. Ask. Then, the gain fluctuation rate S / R is respectively multiplied by the information on the frequency response of the cornering force at the rolling speed of 100 km / h shown in FIG. Then, the frequency when the rolling speed is 100 km / h after multiplying the frequency characteristic of the amplitude ratio (gain) of the cornering force and the gain fluctuation rate S / R when the rolling speed is 10 km / h. And the characteristics are integrated on the same axis (distance frequency axis).

  FIG. 7A is a graph showing the frequency response information of the cornering force at each rolling speed shown in FIGS. 5A and 5B on the same distance frequency axis. If each information of the frequency response of the cornering force at each rolling speed is simply represented on the same distance frequency axis, a shift corresponding to a difference in rolling speed at the time of measurement in the overlapping range of the distance frequency (FIG. 7). Δ shown in (a) occurs. FIG. 7B shows a state after integration by using the value of the gain fluctuation rate in the integration unit 54 (after integrating after multiplying the frequency characteristics when the rolling speed is 100 km / h by the gain fluctuation rate). ()) Frequency characteristics of cornering force. In the case shown in FIG. 7B, the gains of the overlapping frequency portions are almost the same regardless of the difference in rolling speed. In this way, by integrating based on the gain (steady gain) when the frequency is 0 Hz, the frequency characteristic information acquired at each rolling speed is handled as data in one linear system. Can do. The information of the frequency response of the cornering force (FIG. 7B) expressed over the range of the input distance frequency PF that satisfies the above formulas (1) and (2) derived by the integration unit 54 is parameter identification. Sent to the unit 56.

  As described above, when the output signal to be acquired is, for example, the output signal of the tire self-aligning torque, the frequency response information of the self-aligning torque at each rolling speed is the same. Can be represented on the distance frequency axis. FIG. 8A is a graph showing the frequency response information of the self-aligning torque at each rolling speed on the same distance frequency axis. FIG. 8 (b) shows the case (when the rolling speed is 100 km / h) after integration using the gain fluctuation rate value expressed using the steady gain value of the self-aligning torque, as in the case of the cornering force. This is the frequency characteristic of the self-aligning torque (after integration after multiplying the frequency characteristic in) by the gain fluctuation rate. Also in the case shown in FIG. 8B, the gains of the overlapping frequency portions are almost the same regardless of the difference in the respective rolling speeds.

ｓ：ラプラス演算子
ＣＦ：コーナリングフォース（Ｎ）
β：スリップ角（ｒａｄ）
Ｖ：タイヤの転動速度（ｍ／ｓ）
Ｋ：タイヤの等価横剛性（Ｎ／ｍ）
ＣＰ：コーナリングフォースの応答（Ｎ／ｒａｄ） In the parameter identification unit 56, the cornering force as shown in FIG. 7B expressed in the range of the input distance frequency PF that satisfies the above formula (1) and the above formula (2) derived by the integration unit 54 is obtained. Based on the information on the frequency response, the parameters of the transfer function expressing the response of the cornering force with respect to the input distance frequency PF as a first-order lag system are identified. Specifically, the frequency response information of the cornering force expressed over the range of the input distance frequency PF is expressed by the transfer function shown in the following equation (3) in which the response of the cornering force to the input distance frequency PF is expressed as a first-order lag system. By fitting (see FIG. 8), parameters (K, CP) of a transfer function shown in the following formula (3) are obtained. Such fitting may be performed using a known method such as a least square method. K corresponds to the equivalent lateral stiffness which is a characteristic value of the tire, and CP is a gain constant (CF gain) of a transfer function (transfer function expressed by Expression (3)) indicating a first-order lag element. Thus, in a range where the slip angle is very small, it can be said that it corresponds to the cornering power. The parameters K and CP thus identified are sent to the evaluation value calculation unit 58.

s: Laplace operator CF: Cornering force (N)
β: slip angle (rad)
V: Rolling speed of tire (m / s)
K: Equivalent lateral stiffness of tire (N / m)
CP: Cornering Force Response (N / rad)

  The evaluation value calculation unit 58 uses the parameters K and CP, which are parameters sent from the parameter identification unit 56, as the evaluation value of the frequency response of the cornering force when the transfer function (transfer function represented by the expression (3)) is used. A constant T (= CP / K) is obtained. As is well known, this time constant affects the rise time in the transition period of the response waveform behavior in the time response of the first-order lag element expressed by the above transfer function, and determines the time delay to the steady value. Yes. It can be said that the time constant T (= CP / K) quantitatively represents the transient response characteristic of the cornering force. In the present invention, the frequency characteristic of the tire self-aligning torque may be obtained as the cornering dynamic characteristic of the tire. In this case, the information on the frequency response of the self-aligning torque is used, and the transient response of the self-aligning torque is used. What is necessary is just to derive the time constant that quantitatively represents the characteristic.

  The display 18 displays and outputs a time constant T (= CP / K) obtained quantitatively by the evaluation value calculation unit 58 and representing the transient response characteristic of the cornering force. In addition, the display 18 has an amplitude ratio between the input slip angle information and the output cornering force information derived from the measurement / evaluation unit 16 as shown by the Bode diagrams in FIGS. 4 (a) and 4 (b). (Gain) and phase angle (phase delay) information, cornering force frequency response information expressed over the range of the input distance frequency PF satisfying the above formulas (1) and (2) shown in FIG. Various information such as the fitting result information shown in FIG. 8 and the parameters K and CP can also be displayed and output.

  FIG. 9 is a flowchart of a cornering force characteristic evaluation method, which is an example of the tire cornering dynamic characteristic evaluation method of the present invention, implemented in such an apparatus 10. First, the condition setting unit 42 sets the rolling speed of the tire 12 and the frequency of the slip angle input to the tire 12 when the cornering force output signal is acquired (step S102). As described above, the condition setting unit 42 sets the frequency range of a plurality of slip angle inputs given to the tire to a frequency range (for example, 0.1 Hz to 5.0 Hz) that can be controlled with relatively high accuracy by the slip angle adjusting means 29. In such a state, the rolling speeds of the two tires 12 are set, for example, 10 km / h and 100 km / h so that the range of the input distance frequency PF satisfies the above formula (1) and the above formula (2).

  Then, the operation control unit 44 controls the operation of the drive unit 26 (rotational speed of the motor, etc.) and rolls the tire 12 at the first rolling speed (for example, 10 km / h) set by the condition setting unit 42. (Step S104). Then, in the state of rolling at the first rolling speed, the operation control unit 44 controls the operation of the slip angle adjusting means 29 and sets the plurality of slip angular frequencies set by the condition setting unit 42 to the tire. 12 (step S106). The tire is output from the sensor 34 when the data acquisition unit 46 sequentially gives a plurality of slip angle inputs having different frequencies to the tire 12 while rolling the tire 12 at the set rolling speed. The output signal of the cornering force generated at the time is acquired in time series (step S108).

  Then, the data processing unit 52 of the evaluation means 50 uses the time series data of the slip angle to be inputted and the time series data of the output signal of the cornering force, and the cornering force with respect to the distance frequency at the first rolling speed. Frequency response characteristics (amplitude ratio (gain) and phase angle (phase lag) frequency characteristics) are obtained and stored in the memory 19 (step S110).

  When the frequency response characteristics of the cornering force with respect to the distance frequency at the first rolling speed are stored in the memory 19, the frequency response characteristics of the cornering force are derived and stored for all the rolling speeds set by the condition setting unit 42. It is determined whether or not (step S112). When the frequency response characteristic of the cornering force for the first rolling speed is stored, the determination in step S112 is negative (No), and the set rolling speed of the tire 12 is set by the condition setting unit 42. The speed is changed to another rolling speed (in this case, the second rolling speed, for example, 100 km / h) (step S114). Then, the tire 12 is rolled at the second rolling speed (for example, 100 km / h) (step S104), and then the processing of steps S106 to S112 is repeated, and cornering with respect to the distance frequency at the second rolling speed. Force frequency response characteristics (amplitude ratio (gain) and phase angle (phase lag) frequency characteristics) are stored in the memory 19.

  When the characteristics of the frequency response of the cornering force with respect to the distance frequency at the second rolling speed (frequency characteristics of the amplitude ratio (gain) and phase angle (phase lag)) are stored in the memory 19, the determination in step S112 is OK. (Yes), and the integration unit 54 integrates the frequency response characteristics of the cornering force acquired at each rolling speed based on the amplitude ratio (gain) of the cornering force when the distance frequency is 0 (rad / m). (Step S116). Thereby, the frequency characteristic (refer FIG. 7) of the cornering force represented over the range of the input distance frequency PF which satisfy | fills said Formula (1) and said Formula (2) is derived | led-out.

  Next, based on the frequency response characteristic of the cornering force expressed by the parameter identification unit 56 over the range of the input distance frequency PF that satisfies the above formula (1) and the above formula (2) derived by the integration unit 54. The parameters of the transfer function expressing the response of the cornering force with respect to the input distance frequency PF as a first-order lag system are identified (step S118). Then, the evaluation value calculation unit 58 uses K and CP, which are parameters sent from the parameter identification unit 56, as the evaluation value of the frequency response of the cornering force, and the transfer function (transfer function represented by the expression (3)). A time constant T (= CP / K) is obtained (step S120). Then, the time constant T (= CP / K) quantitatively representing the transient response characteristic of the cornering force obtained by the evaluation value calculation unit 58 is displayed on the display 18 (step S122). The cornering force characteristic evaluation method which is an example of the tire cornering dynamic characteristic evaluation method of the present invention is performed in this way.

  According to such a tire cornering dynamic characteristic evaluation method and apparatus, tire-specific cornering is achieved in a relatively wide range of distance frequencies represented by the slip angle frequency input to the tire and the rolling speed of the tire. Dynamic characteristics can be evaluated quantitatively with high accuracy. The cornering dynamic characteristics under various load conditions may be evaluated by variously changing the load applied to the tire from a load loading means (not shown) of the tire shaft support member 32. As described above, the present invention can quantitatively and accurately evaluate the cornering dynamic characteristics inherent to tires in various steering states in various vehicle traveling conditions.

  In the cornering force characteristic evaluation method of the present invention, not only the slip angle is input to the tire, but, for example, a load, a camber angle, a slip ratio, and the like may be input at a plurality of different frequencies.

  The tire cornering dynamic characteristic evaluation method of the present invention and the tire cornering dynamic characteristic evaluation apparatus of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiment and is within the scope of the present invention. Of course, various improvements and changes may be made.

It is a schematic block diagram explaining the cornering force characteristic evaluation apparatus which is an example of the cornering dynamic characteristic evaluation apparatus of the tire of this invention. It is a schematic block diagram explaining the measurement and evaluation unit of the cornering force characteristic evaluation apparatus shown in FIG. It is a graph which shows the change of the lateral force which generate | occur | produces a tire when a small slip angle is attached to the tire which has stopped and this tire is made to go straight slowly. (A) And (b) is an example of the time series data of the some slip angle input data input into a tire, and the cornering force output which a data acquisition part acquires in the cornering force characteristic evaluation apparatus shown in FIG. (A) and (b) are board lines representing amplitude ratio (gain) between input slip angle information and output cornering force information and phase angle (phase delay) information in the cornering force characteristic evaluation apparatus shown in FIG. It is an example of a figure. It is a figure explaining the information used in the data integration part of the cornering force characteristic evaluation apparatus shown in FIG. 1, and represents the magnitude of the cornering force and the self-aligning torque with respect to the rolling speed of the tire in a state where the input slip angle is fixed. It is a scatter diagram. (A) and (b) are graphs representing the frequency response information of the cornering force at each rolling speed obtained on the cornering force characteristic evaluation apparatus shown in FIG. 1 on the same distance frequency axis. (A) is a graph in which cornering force information at each rolling speed is simply represented on the same distance frequency axis, and (b) is information on the cornering force at each rolling speed and the gain fluctuation rate value. It is the graph integrated using. (A) And (b) is the graph which represented each information of the frequency response of the self-aligning torque in each rolling speed on the same distance frequency axis | shaft acquired with the cornering force characteristic evaluation apparatus shown in FIG. Yes, (a) is a graph in which the information on the self-aligning torque at each rolling speed is simply represented on the same distance frequency axis, and (b) is the information on the self-aligning torque at each rolling speed. It is the graph integrated using the value of the gain fluctuation rate. It is a flowchart figure of the cornering force characteristic evaluation method which is an example of the cornering dynamic characteristic evaluation method of the tire of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cornering force characteristic evaluation apparatus 12 Tire 14 Cornering testing machine 16 Measurement / evaluation unit 17 CPU
DESCRIPTION OF SYMBOLS 18 Display 19 Memory 20 Belt 22 Tire shaft 24 Substitute road surface 26 Drive unit 28 Roller pair 29 Slip angle adjustment actuator 32 Tire shaft support member 34 Sensor 40 Measuring means 42 Condition setting part 44 Operation control part 46 Data acquisition part 50 Evaluation means 52 Data Processing unit 54 Data integration unit 56 Parameter identification unit 58 Evaluation value calculation unit

Claims (16)

A method of evaluating cornering dynamic characteristics of a tire,
In a state where the tire is grounded on the ground surface and the tire is rolled at a predetermined rolling speed, a plurality of slip angle inputs having different frequencies are sequentially given to the tire, and a plurality of cornering corresponding to the slip angle input is performed. A measurement step for obtaining a dynamic characteristic output signal;
Using the time-series data of the slip angle input in the measurement step and the time-series data of the output signal obtained in the measurement step, the slip angle is represented by the frequency of the slip angle and the rolling speed of the tire. Obtaining the dynamic characteristic frequency information of the cornering dynamic characteristic with respect to the distance frequency, and outputting the obtained dynamic characteristic frequency information; and
In the measurement step, a plurality of input distance frequencies PF () represented by the predetermined rolling speed V (m / s) of the tire and the plurality of frequencies f (rad / s) of the slip angle input. rad / m), the predetermined value PF ₁ of at least the input distance frequency satisfies the following formula (1), and at least the maximum value PF ₂ of the input distance frequency satisfies the following formula (2): A method for evaluating cornering dynamic characteristics of a tire, wherein the plurality of cornering dynamic characteristic output signals are obtained in a state where a rolling speed and a plurality of frequencies of the slip angle are set.
PF ₁ ≦ 0.03 (rad / m) (1)
10.0 (rad / m) ≦ PF ₂ (2) Prior to the measurement step, in the state where the frequencies of the plurality of slip angle inputs given to the tire are all set within a certain frequency range, the range of the input distance frequency is expressed by the following formula (1) and the following formula ( 2) a setting step of setting a plurality of rolling speeds of the tire so as to satisfy 2),
In the measurement step, the tire is rolled at each of the plurality of rolling speeds set in the setting step, and slip angle inputs of the plurality of frequencies are sequentially given for each of the rolling speeds. Obtaining multiple cornering dynamic characteristic output signals corresponding to slip angle input,
In the analysis step, using the time series data of the slip angle and the time series data of the output signal obtained in the measurement step, corresponding to the distance frequency in each of the rolling speeds. By obtaining dynamic characteristic frequency information of the cornering dynamic characteristics to be integrated and integrating the dynamic characteristic frequency information of each rolling speed, it is expressed over the input distance frequency range satisfying the following formula (1) and the following formula (2). 2. The tire cornering dynamic characteristic evaluation method according to claim 1, wherein the obtained dynamic characteristic frequency information is obtained.
PF ₁ ≦ 0.03 (rad / m) (1)
10.0 (rad / m) ≦ PF ₂ (2)   When setting a plurality of rolling speeds of the tire in the setting step, at least a part of each range of the distance frequency at each rolling speed overlaps at least the range of the distance frequency at one different rolling speed. The method of evaluating cornering dynamic characteristics of a tire according to claim 2, wherein a plurality of the rolling speeds are set.   When integrating the dynamic characteristic frequency information of each rolling speed in the analysis step, the gain value of the dynamic characteristic frequency information of the cornering dynamic characteristic of each rolling speed is substantially the same in the overlapping range of the distance frequency. The tire cornering dynamic characteristic evaluation method according to claim 2, wherein the dynamic characteristic frequency information of each rolling speed is integrated.   When integrating the dynamic characteristic frequency information for each rolling speed in the analysis step, the dynamic speed information for each rolling speed is based on the cornering dynamic characteristic information when the distance frequency is 0 (rad / m). 5. The tire cornering dynamic characteristic evaluation method according to claim 4, wherein characteristic frequency information is integrated.   And a parameter identification step for identifying a transfer function parameter representing a response of the cornering dynamic characteristic with respect to the distance frequency as a first-order lag system based on the dynamic characteristic frequency information obtained in the analyzing step. The tire cornering dynamic characteristic evaluation method according to any one of claims 1 to 5. The cornering dynamic characteristic output signal is a signal representing a cornering force of the tire corresponding to the slip angle input,
In the parameter identification step, a transfer function G (s) represented by the following formula (3) representing a response of the cornering force with respect to the distance frequency as a first-order lag system is used.
The tire cornering dynamic characteristic evaluation method according to claim 6, wherein a parameter of the transfer function is identified based on the dynamic characteristic frequency information obtained in the analysis step.

s: Laplace operator CF: Cornering force (N)
β: slip angle (rad)
V: Rolling speed of tire (m / s)
K: Equivalent lateral stiffness of tire (N / m)
CP: Cornering Force Response (N / rad)   8. The tire cornering dynamic characteristic evaluation method according to claim 6, wherein a time constant of the transfer function representing a transient response characteristic of the cornering dynamic characteristic is obtained as an evaluation value of the cornering dynamic characteristic. A tire cornering dynamic characteristic evaluation device,
In a state where the tire is grounded on the ground surface and the tire is rolled at a predetermined rolling speed, a plurality of slip angle inputs having different frequencies are sequentially given to the tire, and a plurality of cornering corresponding to the slip angle input is performed. Measuring means for obtaining a dynamic characteristic output signal;
Using the time-series data of the slip angle input in the measurement step and the time-series data of the output signal obtained in the measurement step, the slip angle is represented by the frequency of the slip angle and the rolling speed of the tire. Analysis means for obtaining dynamic characteristic frequency information of the cornering dynamic characteristic with respect to a distance frequency, and outputting the obtained dynamic characteristic frequency information;
The measurement means includes a plurality of input distance frequencies PF () represented by the predetermined rolling speed V (m / s) of the tire and the plurality of frequencies f (rad / s) of the slip angle input. rad / m), the predetermined value PF ₁ of at least the input distance frequency satisfies the following formula (1), and at least the maximum value PF ₂ of the input distance frequency satisfies the following formula (2): An apparatus for evaluating cornering dynamic characteristics of a tire, wherein the plurality of cornering dynamic characteristic output signals are obtained in a state where a rolling speed and a plurality of the frequencies of the slip angle are set.
PF ₁ ≦ 0.03 (rad / m) (1)
10.0 (rad / m) ≦ PF ₂ (2) In a state where the frequencies of the plurality of slip angle inputs given to the tire are all set within a certain frequency range, the input distance frequency range satisfies the following formula (1) and the following formula (2). Having a setting unit for setting a plurality of rolling speeds of the tire;
The measuring means rolls the tire at each of the plurality of rolling speeds set by the setting unit, and sequentially provides slip angle inputs of the plurality of frequencies for each of the rolling speeds. Obtaining multiple cornering dynamic characteristics output signals corresponding to angular input,
The analysis means includes
The cornering dynamic characteristics corresponding to the distance frequency at each rolling speed using the time series data of the slip angle at each rolling speed and the time series data of the output signal obtained by the measuring means. By integrating the dynamic characteristic frequency information of each rolling speed and the analysis unit for obtaining the dynamic characteristic frequency information of the above, the input distance frequency range satisfying the following formula (1) and the following formula (2) is expressed. The tire cornering dynamic characteristic evaluation apparatus according to claim 9, further comprising an integration unit that obtains dynamic characteristic frequency information.
PF ₁ ≦ 0.03 (rad / m) (1)
10.0 (rad / m) ≦ PF ₂ (2)   The setting unit sets a plurality of rolling speeds so that at least a part of each of the distance frequency ranges at each rolling speed overlaps the distance frequency range at at least one different rolling speed. 11. The tire cornering dynamic characteristic evaluation apparatus according to claim 10, wherein   When integrating the dynamic characteristic frequency information of each rolling speed in the integration unit, the gain value of the dynamic characteristic frequency information of the cornering dynamic characteristic of each rolling speed is substantially the same in the overlapping range of the distance frequency. The tire cornering dynamic characteristic evaluation device according to claim 10 or 11, wherein the dynamic characteristic frequency information of each rolling speed is integrated.   When integrating the dynamic characteristic frequency information of each rolling speed in the integration unit, based on the cornering dynamic characteristic information when the distance frequency is 0 (rad / m), the dynamic characteristics information of each rolling speed is obtained. 13. The tire cornering dynamic characteristic evaluation apparatus according to claim 12, wherein characteristic frequency information is integrated.   The analysis means further identifies a parameter of a transfer function representing a response of the cornering dynamic characteristic with respect to the distance frequency as a first-order lag system based on the dynamic characteristic frequency information obtained in the analyzing step. The tire cornering dynamic characteristic evaluation device according to claim 9, further comprising a step. The cornering dynamic characteristic output signal obtained by the measuring means is a signal representing a cornering force of the tire corresponding to the slip angle input,
The parameter identification unit of the frequency analysis unit uses a transfer function G (s) represented by the following formula (3) that represents a response of the cornering force with respect to the distance frequency as a first-order lag system,
15. The tire cornering dynamic characteristic evaluation device according to claim 14, wherein a parameter of the transfer function is identified based on the dynamic characteristic frequency information obtained by the analysis unit.

s: Laplace operator CF: Cornering force (N)
β: slip angle (rad)
V: Rolling speed of tire (m / s)
K: Equivalent lateral stiffness of tire (N / m)
CP: Cornering Force Response (N / rad) The tire cornering motion according to claim 14 or 15, wherein the analysis means further obtains a time constant of the transfer function representing a transient response characteristic of the cornering dynamic characteristic as an evaluation value of the cornering dynamic characteristic. Characteristic evaluation device.

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