JP7412984B2 - System, method and program for estimating tire plysteer residual cornering force - Google Patents

Description

The present disclosure relates to a system, method, and program for estimating plysteer residual cornering force of a tire.

It is known that the straightness of a vehicle such as an automobile and the drift phenomenon are affected by the residual cornering force of the tires (for example, see Patent Document 1). The residual cornering force is composed of two components: plysteer residual cornering force and conicity residual cornering force. In this specification, the ply steer residual cornering force may be referred to as "PRCF (Ply steer Residual Cornering Force)." PRCF mainly occurs due to the tread pattern and belt angle.

PRCF can be measured using a known tire testing machine. However, even when the PRCF of the same tire is measured using the same type of testing machine, the results may vary between the testing machines. That is, the PRCF measured using a certain tester (first tester) may be different from the PRCF measured using another tester (second tester). Therefore, it is not possible to simply compare the PRCF obtained with the first test machine with the PRCF obtained with the second test machine, which impairs convenience in evaluating tire characteristics.

Such variations in PRCF between test machines were unavoidable even if some adjustment (alignment) was made for machine differences. Considering the size relationship between price steer cornering force (PS) and cornering stiffness (CS), it is thought that a slight (for example, 0.01° level) angular deviation of the tire installed on the test machine will affect PRCF. This is one of the reasons. Therefore, if the angle is adjusted at a level of 0.001°, this problem cannot be solved, but it is not practical because it requires very complicated work.

Japanese Patent Application Publication No. 6-294709

An object of the present disclosure is to provide a system, method, and program for estimating the PRCF obtained with a second test machine based on the measured values obtained with the first test machine.

A system for estimating plysteer residual cornering force of a tire according to the present disclosure includes:
an acquisition unit that acquires measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the main test tire by the first testing machine;
Using the angle difference Dc between the test machines in the slip angle at which the cornering force becomes zero, and the angle difference Ds between the test machines at the slip angle at which the self-aligning torque becomes zero, according to equation (1), and an estimator for estimating the plysteer residual cornering force PRCF of the main test tire using a second tester.
PRCF=PS-CS(AP/ATS)-CS(Ds-Dc)...(1)

A method for estimating plysteer residual cornering force of a tire according to the present disclosure includes:
Obtaining the measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the test tire by the first testing machine;
Using the angle difference Dc between the test machines in the slip angle at which the cornering force becomes zero, and the angle difference Ds between the test machines at the slip angle at which the self-aligning torque becomes zero, according to equation (1), The plysteer residual cornering force PRCF of the test tire is estimated using two test machines.
PRCF=PS-CS(AP/ATS)-CS(Ds-Dc)...(1)

Block diagram illustrating a system for estimating tire PRCF in the present disclosure Flowchart showing the PRCF estimation processing routine executed by the system SA-CF, SA-SAT diagram showing tire cornering characteristics SA-CF, SA-SAT diagram showing cornering characteristics of preliminary test tires by (A) first test machine and (B) second test machine Graph showing the relationship between the PRCF measurement value by the first testing machine and the PRCF measurement value by the second testing machine Graph showing the relationship between the estimated value of PRCF obtained by the second testing machine and the measured value of PRCF by the second testing machine

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

[System for estimating tire PRCF]
A system 1 shown in FIG. 1 receives measured values from a certain testing machine (first testing machine), and based on the measured values, calculates the tire PRCF (Price Steer) obtained by another testing machine (second testing machine). (residual cornering force).

The system 1 includes an acquisition unit 10 that externally acquires the measurement value obtained by the first test machine in the main test, and an estimation unit 11 that estimates the PRCF obtained by the second test machine based on the measurement value. . The system 1 of the present embodiment also includes a PRCF calculation unit 12 that calculates the PRCF based on the measured value obtained by the first testing machine, and an acquisition unit 13 that externally obtains the measured value obtained in the preliminary test. , and an angular difference calculation unit 14 that calculates the angular differences Dc and Ds based on the measured values acquired by the acquisition unit 13. These units 10 to 14 are installed in software and hardware by the processor 2 executing a pre-stored PRCF estimation processing routine (see FIG. 2) in a computer equipped with a processor 2, a memory 3, various interfaces, etc. Realized through collaboration.

The acquisition unit 10 acquires the measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the main test tire by the first testing machine through user operation or via the network. get. The acquisition unit 10 stores the acquired measurement value data (measurement data) in the memory 3. These measured values are measured by a cornering test using the first testing machine. The cornering test is conducted by driving the tire shaft while applying a predetermined test load and slip angle, and rolling the tire on the test road surface.

FIG. 3 shows an example of the SA-CF curve and SA-SAT curve obtained in the cornering test. This diagram shows a range in which cornering force CF [N] and self-aligning torque SAT [Nm] are each approximately proportional to slip angle SA [°], for example, slip angle SA is -0.5° to +0.5°. can be obtained within the range of . In order to obtain the cornering force CF without the conicity component, the tire rotation direction is measured in both normal rotation (for example, left rotation) and reverse rotation (for example, right rotation), and the average value thereof is taken. In FIG. 3, the cornering force CF including the conicity component is shown by a broken line. The same applies to the self-aligning torque SAT. In this specification, units are shown in curly brackets.

The plysteer cornering force PS[N] is the cornering force CF when the slip angle SA is zero. Cornering stiffness CS [N/°] is the rising slope of cornering force CF, and is determined as cornering force CF when slip angle SA is 1°. The plysteer aligning torque AP [Nm] is the self-aligning torque SAT when the slip angle SA is zero. The aligning torque stiffness ATS [Nm/°] is the rising slope of the self-aligning torque SAT, and is determined as the self-aligning torque SAT when the slip angle is +1° where the self-aligning torque SAT becomes zero.

The plysteer residual cornering force PRCF [N] is determined as the cornering force CF at the slip angle θs (=-AP/ATS) where the self-aligning torque SAT becomes zero. The PRCF calculation unit 12 calculates the PRCF of the main test tire by the first testing machine using the measured value acquired by the acquisition unit 10 according to equation (2).
PRCF=PS-CS(AP/ATS)...(2)

Although the PRCF of the main test tire can be obtained using the first test machine in this way, when the PRCF of the main test tire is measured using the second test machine, the results may vary between test machines (see Figure 5). . Therefore, it is not possible to simply compare PRCFs obtained with multiple test machines, which impairs convenience in evaluating tire characteristics. In addition, such variations in PRCF between test machines were unavoidable even if some adjustment (alignment) was made for machine differences. Therefore, in this system 1, the PRCF obtained by the second test machine is estimated based on the measured value obtained by the first test machine.

After repeated research by the present inventor, the distance L from the slip angle θc (=-PS/CS) to the slip angle θs (that is, the cornering force CF becomes zero) in the SA-CF, SAT diagram shown in FIG. The sum of the slip angle θc at which the self-aligning torque SAT becomes zero and the slip angle θs at which the self-aligning torque SAT becomes zero) should remain unchanged regardless of the test machine, but in reality, the machine difference ( It was found that there was some variation between test machines due to individual differences between test machines. It was also discovered that this change in distance L (angular difference between test machines) increases or decreases plysteer cornering force PS and plysteer aligning torque AP, causing variations in PRCF between test machines.

The estimation unit 11 calculates the angular difference Dc between the test machines in the slip angle at which the cornering force becomes zero (slip angle θc in FIG. 3), and the slip angle at which the self-aligning torque becomes zero (slip angle θs in FIG. 3). ) is used to estimate the plysteer residual cornering force PRCF of the main test tire obtained by the second test machine using equation (1).
PRCF=PS-CS(AP/ATS)-CS(Ds-Dc)...(1)
This equation (1) corresponds to the above-mentioned equation (2) plus a correction term "-CS (Ds-Dc)". By adding such a correction term, the influence of a change in distance L (angular difference between test machines) can be suppressed, and the PRCF of the main test tire obtained by the second test machine can be estimated with high accuracy. If the distance L does not change between test machines, the value in parentheses of the correction term will be zero.

The angular difference Dc and the angular difference Ds have been obtained in advance through a preliminary test and are stored in the memory 3. That is, the angular difference Dc and the angular difference Ds are obtained in advance prior to the PRCF estimation process of the main test tire obtained by the second testing machine. As described later, the angular difference Dc and the angular difference Ds are the plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the preliminary test tires by the first and second test machines. Calculated based on. The acquisition unit 13 acquires these measurement values through a user's operation or via a network, and stores the measurement data in the memory 3. Although the acquisition unit 13 is shown separately from the acquisition unit 10 in FIG. 1, they may be integrated into one, and therefore the acquisition unit 10 may also serve as the acquisition unit 13.

The angle difference Dc is the difference (θ1c- θ2c). The angle difference Ds is a slip angle θ1s at which the self-aligning torque of the preliminary test tire by the first test machine becomes zero, and a slip angle θ2s at which the self-aligning torque of the preliminary test tire by the second test machine becomes zero. The difference is (θ1s−θ2s). The estimation unit 11 estimates the PRCF using the angular difference Dc as the difference (θ1c−θ2c) and the angular difference Ds as the difference (θ1s−θ2s).

The slip angle θ1c, the slip angle θ2c, the slip angle θ1s, and the slip angle θ2s are shown in the SA-CF and SAT curves from which the conicity component is removed, respectively, as shown in FIG. The slip angle θ1c at which the cornering force CF becomes zero can be obtained as the ratio (-PS/CS) of the plysteer cornering force PS to the cornering stiffness CS of the preliminary test tire using the first test machine. The slip angle θ1s at which the self-aligning torque SAT becomes zero can be obtained as the ratio (-AP/ATS) of the plysteer aligning torque AP to the aligning torque stiffness ATS of the preliminary test tire using the first testing machine. The slip angle θ2c and the slip angle θ2s can be obtained in the same manner as the slip angle θ1c and the slip angle θ1s, respectively, in the preliminary test tire using the second testing machine.

The angular difference calculation unit 14 calculates the difference in the manner described above based on the measurement values acquired by the acquisition unit 13 (that is, the measurement values of PS, CS, AP, and ATS measured in the preliminary test using the first and second test machines). Calculate the angular differences Dc and Ds. The angular difference calculation unit 14 stores the obtained calculation data in the memory 3. If the angular differences Dc and Ds are known, by acquiring the information and storing it in the memory 3, the process of calculating the angular difference can be omitted. As long as the test conditions such as load and air pressure do not change with the test machine whose correlation is being examined, the data on the angular differences Dc and Ds can be reused from next time onwards.

In the preliminary test, it is desirable to use a plurality of (for example, five or more) preliminary test tires with different PRCFs. It is preferable that the estimating unit 11 uses the angular difference Dc and the angular difference Ds determined based on the average value of the plurality of preliminary test tires. For example, the differences (θ1c−θ2c) between a plurality of preliminary test tires may be calculated, and the average value thereof may be taken and used as the angular difference Dc. Alternatively, the average value of each slip angle θ1c and the average value of slip angle θ2c of a plurality of preliminary test tires may be calculated, and the difference between them (θ1c−θ2c) may be taken and used as the angle difference Dc. The same applies to the angular difference Ds.

The formats of the first and second testing machines are not particularly limited. In the examples described below, a flat belt type cornering tester is used as the first and second tester, but the present invention is not limited to this. It is possible to use a cornering test machine. In order to accurately estimate PRCF, it is desirable that the second test machine whose correlation with the first test machine is examined be of the same type as the first test machine, but is not limited thereto.

[Method of estimating tire PRCF]
The method of estimating the tire PRCF performed by the system 1 of this embodiment will be described with reference to FIG. 2. This method is executed by one or more processors included in the system 1. As the main test, a cornering test of the main test tire will be conducted using the first testing machine. At this time, the measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the main test tire by the first testing machine are obtained (step S1). This step S1 is performed by the acquisition unit 10 of the system 1.

If necessary, the PRCF of the main test tire is calculated by the first testing machine based on the measured values obtained in the main test (step S2). This step S2 is performed by the PRCF calculation unit 12 of the system 1. Step S2 is not essential and can be omitted.

Next, using the angle difference Dc between the test machines in the slip angle at which the cornering force becomes zero and the angle difference Ds between the test machines at the slip angle at which the self-aligning torque becomes zero, the above formula ( 1), the PRCF of the main test tire by the second test machine is estimated (step S3). The calculation result of step S2 may be applied to equation (1). This estimation step S3 is performed by the estimation unit 11 of the system 1.

A preliminary test for obtaining the angular difference Dc and the angular difference Ds is carried out prior to the main test, and further prior to step S3. In the preliminary test, cornering tests will be conducted on the preliminary test tires using the first and second testing machines. At that time, the measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the preliminary test tire are obtained by each of the first and second testing machines (step S11). This step S11 is performed by the estimation unit 13 of the system 1.

Next, angular differences Dc and Ds between the test machines are calculated based on the measured values obtained in the preliminary test (step S12). Specifically, the slip angle θ1c as a ratio (-PS/CS) is obtained from the measured value in the first test machine, the slip angle θ1s is also obtained as a ratio (-AP/ATS), and the second test Obtain slip angle θ2c as a ratio (-PS/CS) from the measured value on the machine, obtain slip angle θ2s as ratio (-AP/ATS), and calculate the difference between slip angle θ1c and slip angle θ2c. An angular difference Dc, which is (θ1c-θ2c), is calculated, and an angular difference Ds, which is the difference (θ1s-θ2s) between the slip angle θ1s and the slip angle θ2s, is calculated. This step S12 is performed by the angular difference calculation unit 14 of the system 1.

[Example]
In order to concretely demonstrate the effects of this embodiment, an example will be shown in which PRCF was measured using a plurality of test tires with different PRCFs. FIG. 5 is a graph of a reference example showing the relationship between the measured value of PRCF by testing machine A as the first testing machine and the measured value of PRCF by testing machine B as the second testing machine. FIG. 6 is a graph of an example showing the relationship between the estimated value of PRCF obtained by test machine B and the measured value of PRCF by test machine B. The estimated value on the horizontal axis in FIG. 6 was calculated using equation (1) based on the measured value of test machine A. This estimated value is also a correction value obtained by correcting the measured value of PRCF by test machine A (that is, the value on the horizontal axis in FIG. 5) using the above correction term. The vertical axis in FIG. 6 is the same as in FIG. 5.

In the reference example shown in FIG. 5, the PRCF varies between testing machine A and testing machine B, and the regression equation (regression line) does not pass through the origin, causing an offset shift. On the other hand, in the embodiment shown in FIG. 6, such offset deviation is eliminated. Furthermore, in the example, the variation σ of the regression equation is smaller than in the reference example, and the coefficient of determination ^R2 is large (close to 1). This variation σ was determined as the average value of the distance from the regression equation to each plot. In this way, in the example, the PRCF obtained by test machine B can be estimated with high accuracy based on the measured value obtained by test machine A.

As described above, the system 1 for estimating the tire PRCF of the present embodiment is as follows:
an acquisition unit 10 that acquires measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the main test tire by the first testing machine;
Using the angle difference Dc between the test machines in the slip angle at which the cornering force becomes zero, and the angle difference Ds between the test machines at the slip angle at which the self-aligning torque becomes zero, according to equation (1), and an estimation unit 11 that estimates the PRCF of the main test tire using the second test machine.
PRCF=PS-CS(AP/ATS)-CS(Ds-Dc)...(1)
Thereby, the PRCF obtained with the second test machine can be estimated based on the measured value obtained with the first test machine.

Furthermore, the method of estimating the PRCF of the tire of this embodiment is as follows:
Obtain the measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the test tire by the first testing machine,
Using the angle difference Dc between the test machines in the slip angle at which the cornering force becomes zero, and the angle difference Ds between the test machines at the slip angle at which the self-aligning torque becomes zero, according to equation (1), Estimate the plysteer residual cornering force PRCF of this test tire using two test machines.
PRCF=PS-CS(AP/ATS)-CS(Ds-Dc)...(1)
Thereby, the PRCF obtained with the second test machine can be estimated based on the measured value obtained with the first test machine.

In this embodiment, the angular difference Dc is defined as the slip angle θ1c at which the cornering force of the preliminary test tire by the first test machine becomes zero and the slip angle θ2c at which the cornering force of the preliminary test tire by the second test machine becomes zero. is the difference (θ1c - θ2c),
The angle difference Ds is the difference between the slip angle θ1s at which the self-aligning torque of the preliminary test tire by the first test machine becomes zero and the slip angle θ2s at which the self-aligning torque of the preliminary test tire by the second test machine becomes zero. (θ1s−θ2s) is preferable.

In this embodiment, the slip angle θ1c is preferably obtained as a ratio of plysteer cornering force to cornering stiffness of the preliminary test tire by the first tester,
It is preferable that the slip angle θ1s is obtained as a ratio of the plysteer aligning torque to the aligning torque stiffness of the preliminary test tire using the first tester,
The slip angle θ2c is preferably obtained as a ratio of plysteer cornering force to cornering stiffness of the preliminary test tire using the second test machine,
It is preferable that the slip angle θ2s is obtained as a ratio of the plysteer aligning torque to the aligning torque stiffness of the preliminary test tire using the second tester.

In the present embodiment, it is preferable that the angular difference Dc and the angular difference Ds are each calculated based on average values of a plurality of preliminary test tires. According to this configuration, the angular difference Dc and the angular difference Ds can be determined with high precision, and the PRCF obtained by the second testing machine can be estimated more accurately.

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

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

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

For example, each of the units 10 to 14 shown in FIG. 1 is realized by executing a predetermined program on a CPU of a computer, but each unit may be configured with a dedicated circuit. In this embodiment, the processor in one computer implements each unit 10 to 14, but they may be distributed and implemented in at least one or more processors.

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

DESCRIPTION OF SYMBOLS 1... System, 10... Acquisition part, 11... Estimation part, 12... PRCF calculation part

Claims (3)

an acquisition unit that acquires measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the main test tire by the first testing machine;
Using the angle difference Dc between the test machines in the slip angle at which the cornering force becomes zero, and the angle difference Ds between the test machines at the slip angle at which the self-aligning torque becomes zero, according to equation (1), an estimation unit that estimates the plysteer residual cornering force PRCF of the main test tire using a second test machine;
Equipped with
The angle difference Dc is the difference between the slip angle θ1c at which the cornering force of the preliminary test tire by the first test machine becomes zero and the slip angle θ2c at which the cornering force of the preliminary test tire by the second test machine becomes zero. (θ1c−θ2c),
The angle difference Ds is a slip angle θ1s at which the self-aligning torque of the preliminary test tire by the first testing machine becomes zero, and a slip angle at which the self-aligning torque of the preliminary test tire by the second testing machine becomes zero. The difference from the angle θ2s is (θ1s - θ2s),
The slip angle θ1c is obtained as a ratio of plysteer cornering force to cornering stiffness of the preliminary test tire by the first testing machine,
The slip angle θ1s is obtained as a ratio of ply steer aligning torque to aligning torque stiffness of the preliminary test tire by the first testing machine,
The slip angle θ2c is obtained as a ratio of plysteer cornering force to cornering stiffness of the preliminary test tire by the second testing machine,
The slip angle θ2s is obtained as a ratio of plysteer aligning torque to aligning torque stiffness of the preliminary test tire by the second testing machine,
The angular difference Dc and the angular difference Ds are obtained based on average values of the plurality of preliminary test tires having different plysteer residual cornering forces, respectively, in a system for estimating plysteer residual cornering force of a tire.
PRCF=PS-CS(AP/ATS)-CS(Ds-Dc)...(1) Obtain the measured values of plysteer cornering force PS, cornering stiffness CS, plysteer aligning torque AP, and aligning torque stiffness ATS of the test tire by the first testing machine,
Using the angle difference Dc between the test machines in the slip angle at which the cornering force becomes zero, and the angle difference Ds between the test machines at the slip angle at which the self-aligning torque becomes zero, according to equation (1), Estimating the plysteer residual cornering force PRCF of the test tire using two test machines,
The angle difference Dc is the difference between the slip angle θ1c at which the cornering force of the preliminary test tire by the first test machine becomes zero and the slip angle θ2c at which the cornering force of the preliminary test tire by the second test machine becomes zero. (θ1c−θ2c),
The angle difference Ds is a slip angle θ1s at which the self-aligning torque of the preliminary test tire by the first testing machine becomes zero, and a slip angle at which the self-aligning torque of the preliminary test tire by the second testing machine becomes zero. The difference from the angle θ2s is (θ1s - θ2s),
The slip angle θ1c is obtained as a ratio of plysteer cornering force to cornering stiffness of the preliminary test tire by the first testing machine,
The slip angle θ1s is obtained as a ratio of ply steer aligning torque to aligning torque stiffness of the preliminary test tire by the first testing machine,
The slip angle θ2c is obtained as a ratio of plysteer cornering force to cornering stiffness of the preliminary test tire by the second testing machine,
The slip angle θ2s is obtained as a ratio of plysteer aligning torque to aligning torque stiffness of the preliminary test tire by the second testing machine,
A method for estimating plysteer residual cornering force of a tire, wherein the angular difference Dc and the angular difference Ds are determined based on average values of the plurality of preliminary test tires having different plysteer residual cornering forces.
PRCF=PS-CS(AP/ATS)-CS(Ds-Dc)...(1) A program that causes one or more processors to execute the method according to claim 2 .

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