Tire performance measuring method and tire performance measuring device

Abstract

To perform a tire performance evaluation more easily by using a new method different from a conventional real vehicle driving test and a drum-type bench test.SOLUTION: A tire performance measuring method for measuring the performance of a tire for a test vehicle includes: a step of installing in-wheel motors (12-1 to 12-4) on the inside of tire wheels of tires (11-1 to 11-4); a driving force generation step of generating driving forces (F1 to F4) equally in the in-wheel motors (12-1 to 12-4) so that the test vehicle does not move forward or rearward and stays at the place; a step of gradually and equally increasing the driving forces, and when any of the tires slips, determining the driving force at the start of slip of the tire; and a calculation step of calculating a coefficient of friction in the direction of travel or the direction of revolution from the driving force at the start of slip.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tire performance measuring method and a tire performance measuring device. [Background technology]

[0002] Conventionally, actual vehicle running tests have been conducted to evaluate tire performance, but this requires a large area for running on a test course, and the running speed is so fast that the vehicle's trajectory becomes unstable and dangerous after exceeding the tire's performance limit. Therefore, tire performance evaluation is also being conducted using a drum-type bench test device.

[0003] For example, Patent Document 1 discloses a tire performance measuring device comprising a cylindrical drum with its rotation axis positioned horizontally, a replica road surface of an actual road surface that is replaceably attached and fixed to the inner surface of the drum, a drum holding means for rotatably holding the drum, a tire holding means for rotatably supporting the test tire around a horizontal central axis while bringing the outer surface of the test tire into contact with the replica road surface of the drum at a required load, a rotational drive means for rotating the drum and / or the tire holding means, and a means for measuring the performance of the test tire while it is rotated by the rotational drive means. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-82709 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the drum-type bench test device can evaluate tire performance in the forward direction, it cannot evaluate tire performance in the cornering direction.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to enable easy evaluation of tire performance by a new method different from the conventional actual vehicle running test and drum-type bench test. [Means for solving the problem]

[0007] The gist of the present invention for solving the above problems is as follows.

[0008] (1) A tire performance measurement method for measuring the performance of tires of a test vehicle, comprising the steps of: installing an in-wheel motor inside the tire wheel of each tire; a driving force generation step of causing each of the in-wheel motors to generate driving forces evenly so that the test vehicle remains in place without moving forward or backward; a step of gradually increasing the driving forces evenly until one of the tires slips, determining the driving force at the start of slip; and a calculation step of calculating the friction coefficient in the direction of travel or the direction of turning from the driving force at the start of slip.

[0009] (2) A tire performance measurement method as described in (1), wherein the driving force generation step equally generates forward driving forces of the in-wheel motors installed on the tires of the two front or rear wheels and backward driving forces of the in-wheel motors installed on the tires of the remaining two wheels, and the calculation step calculates a friction coefficient in the forward direction.

[0010] (3) A tire performance measurement method as described in (1), wherein the driving force generation step uniformly generates forward driving forces of the in-wheel motors installed on the tires of two wheels positioned in a straight line or diagonally with respect to the direction of travel, and reverse driving forces of the in-wheel motors installed on the tires of the remaining two wheels, and the calculation step calculates the friction coefficient in the cornering direction.

[0011] (4) A tire performance measuring device for measuring the performance of tires of a test vehicle, comprising an in-wheel motor installed in the tire wheel of each tire, and a control unit for controlling an inverter connected to the in-wheel motor, wherein the control unit generates driving force evenly in each of the in-wheel motors so that the test vehicle stays in place without moving forward or backward, and gradually increases the driving force evenly, and when any tire slips, determines the driving force at the start of slip, and calculates the friction coefficient in the direction of travel or cornering from the driving force at the start of slip.

[0012] (5) A tire performance measurement method for measuring the performance of a tire of a test vehicle, comprising the steps of: installing an in-wheel motor inside each tire wheel of a front or rear tire; generating a step-like driving force in the in-wheel motor and acquiring a waveform of a damped vibration of the speed of the in-wheel motor; determining the spring constant of the tire from the vibration frequency of the damped vibration, the moment of inertia of the tire and the in-wheel motor, and the moment of inertia of the body of the test vehicle, and determining the damping coefficient of the tire from the characteristics of the damped vibration.

[0013] (6) A tire performance measurement method for measuring the performance of tires of a test vehicle, comprising the steps of: installing an in-wheel motor inside each tire wheel of a front or rear tire; generating a sinusoidal driving force with a gradually changing frequency in the in-wheel motor, and obtaining gain characteristics and phase characteristics from the speed of the in-wheel motor, the applied frequency, and the amplitude of the driving force; and calculating the spring constant and damping coefficient of the tire from the gain characteristics and phase characteristics using the moment of inertia of the tire and the in-wheel motor, and the moment of inertia of the body of the test vehicle.

[0014] (7) A tire performance measuring device for measuring the performance of tires of a test vehicle, the tire performance measuring device comprising an in-wheel motor installed inside each tire wheel of a front or rear tire, and a control unit for controlling an inverter connected to the in-wheel motor, wherein the control unit generates a step-like driving force in the in-wheel motor, acquires a waveform of damped oscillation of the speed of the in-wheel motor, determines a spring constant of the tire from the oscillation frequency of the damped oscillation, the moment of inertia of the tire and the in-wheel motor, and the moment of inertia of the body of the test vehicle, and determines a damping coefficient of the tire from the characteristics of the damped oscillation, or generates a sinusoidal driving force with a gradually changing frequency in the in-wheel motor, acquires gain characteristics and phase characteristics from the speed of the in-wheel motor, the applied frequency, and the amplitude of the driving force, and determines the spring constant and damping coefficient of the tire from the gain characteristics and phase characteristics using the moment of inertia of the tire and the in-wheel motor, and the moment of inertia of the body of the test vehicle. [Effects of the Invention]

[0015] According to the present invention, tire performance can be easily evaluated by a new method that differs from the conventional on-board running test and drum-type bench test. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing a schematic configuration of a test vehicle according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a first measuring method of the tire performance measuring device according to the first embodiment. [Figure 3] FIG. 4 is a diagram showing a second measuring method of the tire performance measuring device according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing a third measuring method of the tire performance measuring device according to the first embodiment. [Figure 5] FIG. 6 is a diagram showing a fourth measuring method of the tire performance measuring device according to the first embodiment. [Figure 6]FIG. 10 is a diagram showing a schematic configuration of a test vehicle according to a second embodiment. [Figure 7] FIG. 6 is a diagram showing a first measuring method of the tire performance measuring device according to the second embodiment. [Figure 8] FIG. 10 is a diagram showing an example of a waveform of damped vibration obtained by a first measurement method of a tire performance measuring device according to a second embodiment. [Figure 9] FIG. 6 is a diagram showing a second measuring method of the tire performance measuring device according to the second embodiment. [Figure 10] 10A and 10B are diagrams showing examples of gain characteristics and phase characteristics obtained by a second measurement method of the tire performance measurement device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same reference numerals indicate the same or equivalent components. For convenience of illustration, the scales in each drawing are different from the actual scale.

[0018] First Embodiment A test vehicle according to the first embodiment will be described below. Fig. 1 is a diagram showing a schematic configuration of the test vehicle according to the first embodiment. The test vehicle 1 shown in Fig. 1 includes a tire performance measuring device 10a, tires 11-1 to 11-4, in-wheel motors (IWM) 12-1 to 12-4, and speed sensors 13-1 to 13-4.

[0019] Speed ​​sensors 13-1 to 13-4 are attached to in-wheel motors 12-1 to 12-4, respectively, to detect the speeds of in-wheel motors 12-1 to 12-4 and output the detected speeds to tire performance measuring device 10a.

[0020] The in-wheel motors 12-1 to 12-4 are installed inside the tire wheels of the tires 11-1 to 11-4, respectively.

[0021] Tires 11-1 to 11-4 come into contact with the road surface and transmit driving forces F1 to F4 generated by in-wheel motors 12-1 to 12-4 to the road surface.

[0022] The tire performance measurement device 10a includes an inverter connected to the in-wheel motors 12-1 to 12-4, a control unit that controls the inverter, and a driving force detection unit that estimates driving force from the output current of the inverter. Note that the inverter and the driving force detection unit may be provided outside the tire performance measurement device 10a.

[0023] The control unit of tire performance measuring device 10a controls the inverter to uniformly generate driving force from in-wheel motors 12-1 to 12-4 so that test vehicle 1 remains stationary without moving forward or backward, and then gradually increases the driving force uniformly.When any of tires 11-1 to 11-4 slips, the control unit determines the driving force at the start of slip and calculates the coefficient of friction in the forward or turning direction from the driving force at the start of slip.The control unit of tire performance measuring device 10a determines that slip has occurred when the speed detected by speed sensors 13-1 to 13-4 exceeds a predetermined value.A specific tire performance measuring method will be described below.

[0024] <<First measurement method>> FIG. 2 shows a first measurement method of the tire performance measuring device 10a. In the first measurement method, the tire performance measuring device 10a uniformly generates, on any road surface, a driving force F1 in the reverse direction of the in-wheel motor 12-1, a driving force F2 in the reverse direction of the in-wheel motor 12-2, a driving force F3 in the forward direction of the in-wheel motor 12-3, and a driving force F4 in the forward direction of the in-wheel motor 12-4. In other words, the tire performance measuring device 10a uniformly generates a driving force in the forward direction of the in-wheel motors installed on the two rear tires and a driving force in the reverse direction of the in-wheel motors installed on the remaining two tires. During this control, the test vehicle 1 remains in place without moving forward or backward.

[0025] Next, the tire performance measuring device 10a gradually increases each of the driving forces F1 to F4 uniformly, and when any of the tires 11-1 to 11-4 slips (spins), the driving force F at the start of slip is calculated. slip Ask for.

[0026] The tire performance measuring device 10a calculates the driving force F slip For example, as described in 2.2 of Reference 1 below, the driving force F slip The slip ratio λ of the tire can be calculated from the slip ratio λ, and the friction coefficient μ can be calculated from the slip ratio λ. [Reference 1] Kenta Maeda and two others, "Front and rear wheel driving force distribution method for electric vehicles equipped with in-wheel motors for maintaining driving force on instantaneous low friction roads," Transactions of the Japan Society of Mechanical Engineers (C series), October 2012, Vol. 78, No. 794

[0027] As described above, the first tire performance measurement method includes the steps of installing the in-wheel motors 12-1 to 12-4 in the tire wheels of the tires 11-1 to 11-4, respectively; using the tire performance measurement device 10a to uniformly generate a driving force F1 in the reverse direction of the in-wheel motor 12-1, a driving force F2 in the reverse direction of the in-wheel motor 12-2, a driving force F3 in the forward direction of the in-wheel motor 12-3, and a driving force F4 in the forward direction of the in-wheel motor 12-4; and using the tire performance measurement device 10a to uniformly and gradually increase each of the driving forces F1 to F4, so that when any of the tires 11-1 to 11-4 slips, the driving force F1 at the start of slippage is calculated. slip and calculating the driving force F at the start of slip by the tire performance measuring device 10a. slip and calculating the coefficient of friction μ in the direction of travel from the coefficient of friction μ in the direction of travel. This makes it possible to measure the coefficient of friction μ in the direction of travel.

[0028] <<Second measurement method>> 3 shows a second measurement method of the tire performance measuring device 10a. In the second measurement method, the tire performance measuring device 10a uniformly generates, on any road surface, a forward driving force F1 of the in-wheel motor 12-1, a forward driving force F2 of the in-wheel motor 12-2, a reverse driving force F3 of the in-wheel motor 12-3, and a reverse driving force F4 of the in-wheel motor 12-4. In other words, the tire performance measuring device 10a uniformly generates forward driving forces of the in-wheel motors installed on the two front tires and reverse driving forces of the in-wheel motors installed on the remaining two tires. During this control, the test vehicle 1 remains in place without moving forward or backward.

[0029] Next, the tire performance measuring device 10a gradually increases each of the driving forces F1 to F4 uniformly, and when any of the tires 11-1 to 11-4 slips, the driving force F at the start of slip is calculated. slip Ask for.

[0030] The tire performance measuring device 10a calculates the driving force F slip The friction coefficient μ in the direction of travel is calculated from

[0031] As described above, the second tire performance measurement method includes the steps of installing the in-wheel motors 12-1 to 12-4 in the tire wheels of the tires 11-1 to 11-4, respectively; using the tire performance measurement device 10a to uniformly generate a forward driving force F1 of the in-wheel motor 12-1, a forward driving force F2 of the in-wheel motor 12-2, a reverse driving force F3 of the in-wheel motor 12-3, and a reverse driving force F4 of the in-wheel motor 12-4; and using the tire performance measurement device 10a to uniformly and gradually increase each of the driving forces F1 to F4, so that when any of the tires 11-1 to 11-4 slips, the driving force F1 at the start of slippage is calculated. slip and calculating the driving force F at the start of slip by the tire performance measuring device 10a. slip and calculating the coefficient of friction μ in the direction of travel from the coefficient of friction μ in the direction of travel. This makes it possible to measure the coefficient of friction μ in the direction of travel.

[0032] <<Third measurement method>> FIG. 4 shows a third measurement method of the tire performance measuring device 10a. In the third measurement method, the tire performance measuring device 10a uniformly generates, on any road surface, a forward driving force F1 of the in-wheel motor 12-1, a forward driving force F3 of the in-wheel motor 12-3, a reverse driving force F2 of the in-wheel motor 12-2, and a reverse driving force F4 of the in-wheel motor 12-4. In other words, the tire performance measuring device 10a uniformly generates forward driving forces of the in-wheel motors installed on the tires of two wheels located on a straight line (right or left) with respect to the direction of travel, and reverse driving forces of the in-wheel motors installed on the remaining two wheels. During this control, the test vehicle 1 remains in place without moving forward or backward.

[0033] Next, the tire performance measuring device 10a gradually increases each of the driving forces F1 to F4 uniformly, and when any of the tires 11-1 to 11-4 slips, the driving force F at the start of slip is calculated. slip Then, the tire performance measuring device 10a calculates the driving force F slip The friction coefficient μ in the turning direction is calculated from

[0034] As described above, the third tire performance measurement method includes the steps of installing the in-wheel motors 12-1 to 12-4 in the tire wheels of the tires 11-1 to 11-4, respectively; using the tire performance measurement device 10a to uniformly generate a forward driving force F1 of the in-wheel motor 12-1, a forward driving force F3 of the in-wheel motor 12-3, a reverse driving force F2 of the in-wheel motor 12-2, and a reverse driving force F4 of the in-wheel motor 12-4; and using the tire performance measurement device 10a to uniformly and gradually increase each of the driving forces F1 to F4, so that when any of the tires 11-1 to 11-4 slips, the driving force F1 at the start of slippage is calculated. slip and calculating the driving force F at the start of slip by the tire performance measuring device 10a. slipand calculating the coefficient of friction μ in the direction of travel from the coefficient of friction μ in the direction of travel. This makes it possible to measure the coefficient of friction μ in the turning direction.

[0035] <<Fourth measurement method>> FIG. 5 shows a fourth measurement method of the tire performance measuring device 10a. In the fourth measurement method, the tire performance measuring device 10a uniformly generates, on any road surface, a driving force F1 in the reverse direction of the in-wheel motor 12-1, a driving force F4 in the reverse direction of the in-wheel motor 12-4, a driving force F2 in the forward direction of the in-wheel motor 12-2, and a driving force F3 in the forward direction of the in-wheel motor 12-3. In other words, the tire performance measuring device 10a uniformly generates a driving force in the forward direction of the in-wheel motors installed on the two tires diagonally opposite to the direction of travel, and a driving force in the reverse direction of the in-wheel motors installed on the remaining two tires. During this control, the test vehicle 1 remains in place without moving forward or backward.

[0036] Next, the tire performance measuring device 10a gradually increases each of the driving forces F1 to F4 uniformly, and when any of the tires 11-1 to 11-4 slips, the driving force F at the start of slip is calculated. slip Then, the tire performance measuring device 10a calculates the driving force F slip The turning direction friction coefficient μ is calculated from

[0037] As described above, the fourth tire performance measurement method includes the steps of installing the in-wheel motors 12-1 to 12-4 in the tire wheels of the tires 11-1 to 11-4, respectively; equally generating a reverse direction driving force F1 of the in-wheel motor 12-1, a reverse direction driving force F4 of the in-wheel motor 12-4, a forward direction driving force F2 of the in-wheel motor 12-2, and a forward direction driving force F3 of the in-wheel motor 12-3; and gradually increasing each of the driving forces F1 to F4 equally by the tire performance measurement device 10a, so that when any of the tires 11-1 to 11-4 slips, the driving force F1 at the start of slippage is calculated. slip and calculating the driving force F at the start of slip by the tire performance measuring device 10a.slip and calculating the coefficient of friction μ in the direction of travel from the coefficient of friction μ in the direction of travel. This makes it possible to measure the coefficient of friction μ in the turning direction.

[0038] <Second embodiment> Next, a test vehicle according to a second embodiment will be described. Fig. 6 is a diagram showing a schematic configuration of the test vehicle according to the second embodiment. The test vehicle 2 shown in Fig. 6 includes a tire performance measuring device 10b, tires 11-1 to 11-4, in-wheel motors (IWM) 12-1 to 12-2, and speed sensors 13-1 to 13-2.

[0039] In-wheel motors 12-1 and 12-2 are installed inside the tire wheels of tires 11-1 and 11-2, respectively. Similarly, in-wheel motors may be installed inside the tire wheels of tires 11-3 and 11-4, respectively.

[0040] Speed ​​sensors 13-1 and 13-2 are attached to in-wheel motors 12-1 and 12-2, respectively, to detect the speeds of in-wheel motors 12-1 and 12-2 and output the detected speeds to tire performance measuring device 10b.

[0041] The tire performance measurement device 10b includes an inverter connected to the in-wheel motors 12-1 to 12-2, a control unit that controls the inverter, and a driving force detection unit that estimates driving force from the output current of the inverter. Note that the inverter and the driving force detection unit may be provided outside the tire performance measurement device 10b.

[0042] A control unit of the tire performance measurement device 10b controls an inverter to generate a step-like or sinusoidal driving force with a variable frequency in the in-wheel motors 12-1 to 12-2, and calculates the spring constant and damping coefficient of the tires 11-1 to 11-2 from information obtained from the change in speed of the in-wheel motors 12-1 to 12-2, the moments of inertia of the tires 11-1 to 11-2 and in-wheel motors 12-1 to 12-2, and the moment of inertia of the vehicle body. A specific tire performance measurement method will be described below.

[0043] <<First measurement method>> A first measurement method of the tire performance measurement device 10b is shown in Fig. 7. The tire performance measurement device 10b causes the in-wheel motors 12-1 and 12-2 to generate step-like driving forces Fs1 to Fs2 as shown in Fig. 7.

[0044] The speed sensors 13-1 and 13-2 detect the speeds S1 and S2 of the in-wheel motors 12-1 and 12-2 while the step-like driving forces Fs1 and Fs2 are applied, respectively, and output the detected speeds to the tire performance measurement device 10b. The tire performance measurement device 10b records the changes in the speeds S1 and S2 and obtains the waveform of the damped oscillation as shown in Fig. 8.

[0045] Next, the tire performance measuring device 10b calculates the spring constants of the tires 11-1 to 11-2 from the vibration frequency of the damped vibration, the moments of inertia of the in-wheel motors 12-1 to 12-2, and the moment of inertia of the vehicle body, and calculates the damping coefficients (damping coefficients) of the tires 11-1 to 11-2 from the damping characteristics. The method of calculating the spring constant k and the damping coefficient c is well known, and for details, see, for example, Reference 2 below. [Reference 2] Ono Sokki Co., Ltd., "Technical Report: Coefficients Representing Damping Characteristics," [online], [Retrieved April 30, 2024], Internet <URL: https: / / www.onosokki.co.jp / HP-WK / c_support / newreport / dampingfactor / damping_factor.pdf>

[0046] The tire performance measuring device 10b may correct the spring constant and the damping coefficient in consideration of the fact that a suspension is provided between the vehicle body and the in-wheel motors 12-1 to 12-2.

[0047] Thus, the first tire performance measurement method includes the steps of installing the in-wheel motors 12-1 to 12-2 inside the tire wheels of the tires 11-1 to 11-2, respectively, generating step-like driving forces Fs1 to Fs2 in the in-wheel motors 12-1 to 12-2 using the tire performance measurement device 10b and acquiring waveforms of damped oscillation of the speeds S1 to S2 of the in-wheel motors 12-1 to 12-2, and using the tire performance measurement device 10b to determine the spring constants of the tires 11-1 to 11-2 from the oscillation frequency of the damped oscillation, the moments of inertia of the in-wheel motors 12-1 to 12-2 of the tires 11-1 to 11-2, and the moment of inertia of the body of the test vehicle 2, and determining the damping coefficients of the tires 11-1 to 11-2 from the damping characteristics. In this way, the spring constants and damping coefficients of the tires 11-1 to 11-2 can be measured. Although the measurements are made on the front tires 11-1 and 11-2 in the above, the measurements on the rear tires 11-3 and 11-4 may be made in the same manner.

[0048] <<Second measurement method>> A second measurement method of tire performance measurement device 10b is shown in Fig. 9. Tire performance measurement device 10b causes in-wheel motors 12-1 and 12-2 to generate sinusoidal driving forces Ff1 and Ff2 whose frequencies change gradually as shown in Fig. 9.

[0049] The speed sensors 13-1 and 13-2 detect speeds S1 and S2 of the in-wheel motors 12-1 and 12-2 while the sinusoidal driving forces Ff1 and Ff2 with varying frequencies are applied, respectively, and output the speeds to the tire performance measuring device 10b.

[0050] The tire performance measuring device 10b records the speeds S1 to S2 while the driving forces Ff1 to Ff2 are being applied, the applied frequency, and the amplitude of the driving forces Ff1 to Ff2, draws a Bode diagram from the driving force Ff1 to the speed S1, and a Bode diagram from the driving force Ff2 to the speed S2, and obtains the gain characteristics and phase characteristics as shown in FIG. 10 from the Bode diagrams.

[0051] Next, the tire performance measurement device 10b calculates the spring constants and damping coefficients of the tires 11-1 to 11-2 from the gain characteristics and phase characteristics of the Bode diagram, using the moments of inertia of the tires 11-1 to 11-2 and the in-wheel motors 12-1 to 12-2 and the moment of inertia of the vehicle body. The tire performance measurement device 10b may correct the spring constants and damping coefficients in consideration of the presence of suspensions between the vehicle body and the in-wheel motors 12-1 to 12-2.

[0052] As described above, the second tire performance measurement method includes the steps of installing in-wheel motors 12-1 to 12-2 inside the tire wheels of tires 11-1 to 11-2, respectively, generating sinusoidal driving forces Ff1 to Ff2 with gradually changing frequencies in the in-wheel motors 12-1 to 12-2 using tire performance measurement device 10b, recording speeds S1 to S2 of the in-wheel motors 12-1 to 12-2, the applied frequencies, and the amplitudes of the driving forces Ff1 to Ff2, and acquiring gain and phase characteristics, and determining, using tire performance measurement device 10b, the spring constants and damping coefficients of the tires 11-1 to 11-2 from the gain and phase characteristics using the moments of inertia of the tires 11-1 to 11-2 and in-wheel motors 12-1 to 12-2, and the moment of inertia of the body of test vehicle 2. In this way, the spring constants and damping coefficients of the tires 11-1 to 11-2 can be measured. Although the measurements are made on the front tires 11-1 and 11-2 in the above, the measurements on the rear tires 11-3 and 11-4 may be made in the same manner.

[0053] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications or alterations can be made without departing from the scope of the claims. For example, it is possible to integrate multiple building blocks shown in the block diagrams of the embodiments, or to divide one building block. [Explanation of symbols]

[0054] 1,2 Test vehicle 10a, 10b Tire performance measuring device 11-1, 11-2, 11-3, 11-4 Tires 12-1, 12-2, 12-3, 12-4 In-wheel motor 13-1~13-2, 13-3, 13-4 Speed ​​sensors

Claims

1. A tire performance measurement method for measuring the performance of a tire of a test vehicle, comprising: installing an in-wheel motor within the tire wheel of each tire; a driving force generating step of causing each of the in-wheel motors to generate driving forces equally so that the test vehicle remains in place without moving forward or backward; a step of gradually increasing the driving force evenly and determining the driving force at the start of slip when any tire slips; a calculation step of calculating a friction coefficient in a traveling direction or a turning direction from the driving force at the time of slip start; A tire performance measurement method, including:

2. the driving force generating step uniformly generates driving forces in a forward direction of the in-wheel motors installed on the tires of the two front or rear wheels and driving forces in a backward direction of the in-wheel motors installed on the tires of the remaining two wheels; 2. The tire performance measuring method according to claim 1, wherein the calculation step calculates a friction coefficient in a traveling direction.

3. the driving force generating step uniformly generates driving forces in a forward direction of the in-wheel motors installed on two tires positioned on a straight line or a diagonal line with respect to the traveling direction, and driving forces in a backward direction of the in-wheel motors installed on the remaining two tires, 2. The tire performance measuring method according to claim 1, wherein the calculation step calculates a coefficient of friction in a turning direction.

4. A tire performance measuring device for measuring the performance of a tire of a test vehicle, An in-wheel motor is installed inside each tire wheel. a control unit that controls an inverter connected to the in-wheel motor, The control unit causes each of the in-wheel motors to generate driving force evenly so that the test vehicle remains in place without moving forward or backward, gradually increases the driving force evenly, determines the driving force at the start of slippage of any of the tires, and calculates the friction coefficient in the direction of travel or the direction of turning from the driving force at the start of slippage.

5. A tire performance measurement method for measuring the performance of a tire of a test vehicle, comprising: installing an in-wheel motor in each of the tire wheels of the front wheels or the rear wheels; generating a step-like driving force in the in-wheel motor and acquiring a waveform of damped oscillation of the speed of the in-wheel motor; determining a spring constant of the tire from the vibration frequency of the damped vibration, the moment of inertia of the tire and the in-wheel motor, and the moment of inertia of the body of the test vehicle, and determining a damping coefficient of the tire from the characteristics of the damped vibration; A tire performance measurement method, including:

6. A tire performance measurement method for measuring the performance of a tire of a test vehicle, comprising: installing an in-wheel motor in each of the tire wheels of the front wheels or the rear wheels; generating a sinusoidal driving force whose frequency gradually changes in the in-wheel motor, and obtaining gain characteristics and phase characteristics from a speed of the in-wheel motor, the applied frequency, and an amplitude of the driving force; determining a spring constant and a damping coefficient of the tire from the gain characteristic and the phase characteristic using a moment of inertia of the tire and the in-wheel motor, and a moment of inertia of a body of the test vehicle; A tire performance measurement method, including:

7. A tire performance measuring device for measuring the performance of a tire of a test vehicle, An in-wheel motor is installed in each tire wheel of the front or rear wheel, a control unit that controls an inverter connected to the in-wheel motor, the control unit generates a step-like driving force in the in-wheel motor, acquires a waveform of a damped vibration of the speed of the in-wheel motor, calculates a spring constant of the tire from a vibration frequency of the damped vibration, a moment of inertia of the tire and the in-wheel motor, and a moment of inertia of a body of the test vehicle, and calculates a damping coefficient of the tire from the characteristics of the damped vibration; or a tire performance measuring device that generates a sinusoidal driving force with a gradually changing frequency in the in-wheel motor, obtains gain characteristics and phase characteristics from the speed of the in-wheel motor, the applied frequency, and the amplitude of the driving force, and determines a spring constant and a damping coefficient of the tire from the gain characteristics and the phase characteristics using the moments of inertia of the tire and the in-wheel motor, and the moment of inertia of the body of the test vehicle.

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