JP7347187B2 - Tire cornering characteristics evaluation method - Google Patents

Description

The present invention relates to a method for evaluating the cornering characteristics of a tire mounted on a vehicle.

Conventionally, various attempts have been made to quantitatively evaluate the cornering characteristics of tires mounted on vehicles. For example, Patent Document 1 listed below proposes a method for determining the equivalent cornering power of a tire based on a vehicle slip angle, lateral acceleration, and vehicle speed at an arbitrary point on the vehicle.

Japanese Patent Application Publication No. 2018-084551

However, the method of Patent Document 1 does not clearly evaluate the stability factor, steady yaw gain, and yaw resonance frequency, which are vehicle dynamic characteristic indicators, and the equivalent cornering coefficient related to the yaw resonance frequency, and an evaluation based on the equivalent cornering coefficient is desired. was.

The present invention was devised in view of the above-mentioned circumstances, and its main purpose is to provide a method by which the cornering characteristics of a tire can be easily evaluated based on an equivalent cornering coefficient.

The present invention provides a method for evaluating cornering characteristics of a tire, which includes a first step of determining cornering power and self-aligning torque power of the tire, and determining the cornering power and self-aligning torque power, and the equivalent cornering coefficient of the tire. and a third step of displaying the cornering power, the self-aligning torque power, and the equivalent cornering coefficient on one graph.

The method for evaluating cornering characteristics of a tire according to the present invention further includes a fourth step of evaluating the cornering characteristics of the tire to be evaluated, and the third step is performed by displaying contour lines of the equivalent cornering coefficient of the tire. It is desirable that the fourth step evaluates the cornering characteristics of the tire based on the region to which the tire belongs.

In the tire cornering characteristic evaluation method of the present invention, it is preferable that the contour lines are displayed in a straight line.

In the method for evaluating cornering characteristics of a tire according to the present invention, it is preferable that the second step calculates the relational expression based on coefficients related to suspension characteristics of a vehicle on which the tire is mounted.

In the tire cornering characteristic evaluation method of the present invention, it is preferable that the coefficients related to the suspension characteristics include a first coefficient related to roll steer, a second coefficient related to lateral force compliance steer, and a third coefficient related to torsional rigidity.

In the tire cornering characteristic evaluation method of the present invention, it is preferable that the coefficient regarding the suspension characteristic is determined by actual measurement or calculation.

In the method for evaluating cornering characteristics of a tire according to the present invention, it is preferable that in the first step, the cornering power and the self-aligning torque power are determined by performing a bench test on the tire to be evaluated.

The tire cornering characteristic evaluation method of the present invention includes a third step of displaying cornering power, self-aligning torque, and equivalent cornering coefficient in one graph. Such a method can evaluate the cornering characteristics of the tire with respect to the stability factor, steady yaw gain, and equivalent cornering coefficient related to the yaw resonance frequency, which are indicators of the dynamic characteristics of the vehicle. Therefore, the tire cornering characteristic evaluation method of the present invention can easily evaluate tire cornering characteristics based on the equivalent cornering coefficient.

1 is a flowchart showing an embodiment of a method for evaluating cornering characteristics of a tire according to the present invention. It is a flowchart which shows a 2nd process. It is a flowchart which shows a 3rd process. It is a graph which shows an example when a tire is used for a front wheel. It is a graph which shows an example when a tire is used for a rear wheel.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.
FIG. 1 is a flowchart showing a method for evaluating cornering characteristics of a tire according to the present embodiment. As shown in FIG. 1, the method for evaluating cornering characteristics of a tire according to the present embodiment is a method for quantitatively evaluating the cornering characteristics of a tire.

In the tire cornering characteristic evaluation method of the present embodiment, first, a first step S1 is performed to obtain tire cornering power CP and self-aligning torque power SATP. In the first step S1, it is preferable that the cornering power CP and self-aligning torque power SATP of the tire are determined by actual measurement or calculation. Such a first step S1 can accurately determine the cornering power CP and self-aligning torque power SATP of the tire.

In the tire cornering characteristic evaluation method of the present embodiment, after the first step S1, a second step S2 is performed to obtain a relational expression F1 between the cornering power CP, self-aligning torque power SATP, and the equivalent cornering coefficient C of the tire. It will be done. Here, the equivalent cornering coefficient C is a coefficient related to the stability factor, steady yaw gain, and yaw resonance frequency, which are indicators of vehicle motion characteristics. In such a second step S2, the cornering characteristics of the tire can be evaluated in consideration of the dynamic characteristics of the vehicle.

In the tire cornering characteristic evaluation method of this embodiment, after the second step S2, a third step S3 is performed in which cornering power CP, self-aligning torque power SATP, and equivalent cornering coefficient C are displayed in one graph. .

Such a method can evaluate the cornering characteristics of the tire with respect to the stability factor, steady yaw gain, and equivalent cornering coefficient C related to the yaw resonance frequency, which are indicators of the dynamic characteristics of the vehicle. Therefore, the tire cornering characteristic evaluation method of the present embodiment can easily evaluate the tire cornering characteristics based on the equivalent cornering coefficient.

More preferably, in the tire cornering characteristic evaluation method, after the third step S3, a fourth step S4 of evaluating the cornering characteristics of the tire to be evaluated is performed. In the fourth step S4, for example, the cornering characteristics of the tire are evaluated based on the position of the tire to be evaluated on the graph. Such fourth step S4 is useful for easily evaluating the cornering characteristics of the tire.

In the first step S1 of the present embodiment, cornering power CP and self-aligning torque power SATP are determined by performing a bench test on the tire to be evaluated. In the first step S1, for example, the cornering power CP and self-aligning torque power SATP of the tire to be evaluated are determined using a flat belt testing machine. In such a first step S1, the tire cornering power CP and self-aligning torque power SATP can be obtained by actual measurement.

The first step S1 may be calculated using simulation, for example. In such a first step S1, there is no need to make a prototype even when a new tread pattern is adopted, and the time required for evaluating the cornering characteristics of the tire can be shortened.

FIG. 2 is a flowchart showing the second step S2 of this embodiment. As shown in FIG. 2, the second step S2 of the present embodiment includes a first equation calculation step S21 for calculating a relational equation F1 between the cornering power CP and self-aligning torque power SATP and the equivalent cornering coefficient C of the tire. It will be done. In the first equation calculation step S21, it is desirable to obtain the relational equation F1 based on the coefficient a related to the suspension characteristics of the vehicle on which the tire is installed.

ここで、係数ａは、サスペンション特性に関する係数である。 The relational expression F1 is expressed, for example, as Equation 1 below.

Here, the coefficient a is a coefficient related to suspension characteristics.

It is desirable that the coefficient a relating to suspension characteristics includes a first coefficient a1 relating to roll steer, a second coefficient a2 relating to lateral force compliance steer, and a third coefficient a3 relating to torsional rigidity. The relational expression F2 in this case is expressed as Equation 2 below, for example.

It is preferable that the first coefficient a1, second coefficient a2, and third coefficient a3 regarding the suspension characteristics are respectively determined by actual measurement or calculation. The first coefficient a1, second coefficient a2, and third coefficient a3 of this embodiment are determined by actual measurements using a suspension characteristic testing machine. Such a first equation calculation step S21 can accurately determine the coefficient a regarding the suspension characteristics.

In the second step S2, a second equation calculation step S22 is performed in which a relational expression F3 expressed by the following equation 3 is obtained by solving the relational expression F2 expressed by the equation 2 for the self-aligning torque power SATP.

ここで、各係数は、以下のとおりである。
Ｗｆ ： フロント軸重
ｇ ： 重力加速度
ａ１ｆ ： フロントロールステア係数
ａ２ｆ ： フロント横力コンプライアンスステア係数
ａ３ｆ ： フロントねじり剛性係数
ＣＴ ： キャスタートレール For example, when the tire is used for the front wheel, Equation 3 is expressed as Equation 4 below as a relational expression among front cornering power FrCP, front self-aligning torque power FrSATP, and front equivalent cornering coefficient Cf.

Here, each coefficient is as follows.
Wf: Front axle load g: Gravity acceleration a1f: Front roll steer coefficient a2f: Front lateral force compliance steer coefficient a3f: Front torsional rigidity coefficient CT: Caster trail

ここで、各係数は、以下のとおりである。
Ｗｒ ： リア軸重
ｇ ： 重力加速度
ａ１ｒ ： リアロールステア係数
ａ２ｒ ： リア横力コンプライアンスステア係数
ａ３ｒ ： リアねじり剛性係数 For example, when the tire is used for the rear wheel, Equation 3 is expressed as Equation 5 below as a relational expression among rear cornering power RrCP, rear self-aligning torque power RrSATP, and rear equivalent cornering coefficient Cr. .

Here, each coefficient is as follows.
Wr: Rear axle load g: Gravitational acceleration a1r: Rear roll steer coefficient a2r: Rear lateral force compliance steer coefficient a3r: Rear torsional rigidity coefficient

Note that Equation 3 is not limited to Equation 4 or Equation 5, and can be expressed using a first coefficient a1 related to roll steer, a second coefficient a2 related to lateral force compliance steer, a third coefficient a3 related to torsional rigidity, etc. Various formulas may be employed as appropriate.

Further, in the second equation calculation step S22 described above, Equation 2 was solved for self-aligning torque power SATP, but in the second equation calculation step S22, Equation 2 may be solved for cornering power CP, for example. In this case, the second equation calculation step S22 calculates a relational equation F4 expressed by the following equation 6.

FIG. 3 is a flowchart showing the third step S3, and FIG. 4 is a graph showing an example when the tire is used for the front wheel. As shown in FIGS. 3 and 4, in the third step S3 of this embodiment, first, a vertical axis/horizontal axis display step S31 for displaying the vertical axis and horizontal axis of the graph is performed. In the vertical axis/horizontal axis display step S31 of this embodiment, the cornering power CP is displayed on the horizontal axis and the self-aligning torque power SATP is displayed on the vertical axis.

It is desirable that the third step S3 is followed by a contour line display step S32 of displaying contour lines of the equivalent cornering coefficient C on the graph. The contour line display step S32 displays contour lines when the equivalent cornering coefficient C is a certain value Ca, using, for example, the relational expression F3. In such a third step S3, since the first coefficient a1, second coefficient a2, and third coefficient a3 are constant coefficients, it is easy to display the contour line when the equivalent cornering coefficient C is a certain value Ca. It is.

Here, the relational expression F3 can express SATP as a linear function of CP when the equivalent cornering coefficient C is a certain value Ca. Therefore, the contour lines in this embodiment are displayed in a straight line. In FIG. 4, five contour lines when the equivalent cornering coefficient C has values C1 to C5 are illustrated using a relational expression based on Equation 4.

In the third step S3, it is desirable that a region dividing step S33 is then performed in which the graph is divided into a plurality of regions Ra by displaying contour lines of the equivalent cornering coefficient C. In FIG. 4, six regions R1 to R6 defined by five contour lines are illustrated. In FIG. 4, one region R4 is colored for easy understanding. Each of the regions Ra has a range in which the equivalent cornering coefficient C is the same or similar. Such region dividing step S33 is useful for easily evaluating the cornering characteristics of the tire based on the equivalent cornering coefficient C.

In the third step S3, next, a target tire display step S34 is performed in which tires to be evaluated are displayed. In the target tire display step S34, it is desirable to display a different mark for each tire to be evaluated. In FIG. 4, tire A and tire B are illustrated. Such target tire display step S34 makes it easy to visually grasp the cornering characteristics of the tire to be evaluated.

FIG. 5 is a graph showing an example when the tire is used for the rear wheel. In FIG. 5, six contour lines when the equivalent cornering coefficient C has values C6 to C11 are displayed using the relational expression based on Equation 5, and seven regions R7 to R13 partitioned by these contour lines are illustrated. ing.

As shown in FIGS. 1, 4, and 5, in the fourth step S4 of this embodiment, the cornering characteristics of the tire are evaluated based on the region Ra to which the tire belongs. In FIG. 4, a state is illustrated in which tire A belongs to region R3 and tire B belongs to region R5. In FIG. 5, a state is illustrated in which tire A belongs to region R11 and tire B belongs to region R9. In this fourth step S4, since the evaluation is performed based on the region Ra to which the tire belongs, the cornering characteristics of the tire can be easily evaluated based on the equivalent cornering coefficient C.

Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and can be implemented in various forms.

Tire A and Tire B were evaluated using the graphs obtained from Equations 4 and 5 using the methods shown in FIGS. 1 to 3. In this example, cornering power CP and self-aligning torque power SATP of Tire A and Tire B were determined using a flat belt testing machine. In addition, the first coefficient a1, second coefficient a2, and third coefficient a3 regarding suspension characteristics were determined using a suspension characteristics tester. The results of the test are shown in FIGS. 4 and 5.

As a result of the test, whether the tire is used for the front wheel or the rear wheel, the equivalent cornering coefficient C of tire A is higher than the equivalent cornering coefficient C of tire B. It was confirmed that it was high. Furthermore, it was confirmed that when the tire is used for the rear wheel, the influence of the self-aligning torque power SATP on the equivalent cornering coefficient C is smaller than when the tire is used for the front wheel. Therefore, it was confirmed that the evaluation method of the example can easily evaluate the cornering characteristics of a tire based on the equivalent cornering coefficient C.

S1 1st process S2 2nd process S3 3rd process CP Cornering power SATP Self-aligning torque power C Equivalent cornering coefficient

Claims (7)

A method for evaluating cornering characteristics of a tire, the method comprising:
a first step of determining cornering power and self-aligning torque power of the tire;
a second step of determining a relational expression between the cornering power and the self-aligning torque power and an equivalent cornering coefficient of the tire;
a third step of displaying the cornering power, the self-aligning torque power, and the equivalent cornering coefficient in one graph;
Method for evaluating tire cornering characteristics. further comprising a fourth step of evaluating cornering characteristics of the tire to be evaluated,
The third step divides the graph into a plurality of regions by displaying contour lines of the equivalent cornering coefficient,
The method for evaluating cornering characteristics of a tire according to claim 1, wherein in the fourth step, the cornering characteristics of the tire are evaluated based on the region to which the tire belongs. The tire cornering characteristic evaluation method according to claim 2, wherein the contour line is displayed in a straight line. 4. The method for evaluating cornering characteristics of a tire according to claim 1, wherein in the second step, the relational expression is determined based on coefficients related to suspension characteristics of a vehicle to which the tire is mounted. The tire cornering characteristic evaluation method according to claim 4, wherein the coefficients related to the suspension characteristics include a first coefficient related to roll steer, a second coefficient related to lateral force compliance steer, and a third coefficient related to torsional rigidity. The tire cornering characteristic evaluation method according to claim 4 or 5, wherein the coefficient regarding the suspension characteristic is obtained by actual measurement or calculation. The cornering characteristic evaluation of a tire according to any one of claims 1 to 6, wherein the first step is to obtain the cornering power and the self-aligning torque power by performing a bench test on the tire to be evaluated. Method.

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