JP7095285B2 - Evaluation method of tire vibration characteristics - Google Patents

Description

The present invention relates to a method for evaluating the vibration characteristics of a tire.

Conventionally, as a method for evaluating the vibration characteristics of a tire, for example, a method of running a vehicle equipped with a tire and evaluating the vibration generated during the running by the sensuality of an evaluator is known.

Japanese Unexamined Patent Publication No. 2009-250766

However, since the above-mentioned method is based on the subjectivity of the evaluator, there is a problem that the result cannot be evaluated quantitatively.

The present invention has been devised in view of the above problems, and an object of the present invention is to provide a method for quantitatively evaluating the vibration characteristics of a tire.

The present invention is a method for evaluating the vibration characteristics of a tire, the first step of making a vehicle equipped with the tire run in a steady circular turn at a limit speed of a predetermined turning radius, and the first step. Following the steps, the second step of turning the vehicle at a speed equal to or higher than the limit speed and making the steering angle of the handle of the vehicle larger than the steering angle during the steady circular turning running, and the second step. It includes a third step of acquiring parameters related to the vibration characteristics of the tire in the step, and a fourth step of determining the quality of the vibration characteristics based on the parameters.

In the evaluation method according to the present invention, it is desirable that the second step includes a step of gradually increasing the steering angle.

In the evaluation method according to the present invention, it is desirable that the steering angle increases at 20 to 40 degrees / sec.

In the evaluation method according to the present invention, it is desirable that the parameter includes at least one of the acceleration acting on the tire, the steering angle or the slip angle.

It is desirable that the evaluation method according to the present invention further includes a step of detecting the acceleration in a plan view of the vehicle by using an acceleration sensor substantially arranged at the center of gravity of the vehicle.

In the evaluation method according to the present invention, a four-wheeled vehicle is used as the vehicle, and the acceleration is substantially arranged at the axle position of the front wheel of the vehicle or the driver's seat position in the plan view of the vehicle. It is desirable to further include a step of detecting using a sensor.

In the method for evaluating the vibration characteristics of a tire of the present invention, the vibration characteristics are evaluated based on the parameters related to the vibration characteristics of the tire in the second step. In such an evaluation method of the present invention, vibrations that have been evaluated by sensory in the past, in particular, vibrations derived from so-called stick slip, in which adhesion and slip are repeated on the contact surface between the tire and the road surface that occurs during unsteady turning, are generated. It can be evaluated quantitatively.

It is a flowchart which shows the processing procedure of the evaluation method of this invention. It is a schematic diagram explaining the 1st process and the 2nd process. It is a conceptual diagram which shows an example of the vehicle used in this invention. It is a graph which shows an example of acceleration data and steering angle data. It is a graph which shows an example of acceleration data and steering angle data. It is a graph which showed an example of the relationship between acceleration and steering angle. It is a graph which showed an example of the relationship between acceleration and steering angle. It is a graph which showed an example of the relationship between the acceleration and the slip angle of the front wheel on the outside of a turn. It is a graph which showed an example of the relationship between the acceleration and the slip angle of the front wheel inside a turn.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The present invention is a method for evaluating the vibration characteristics of a tire (hereinafter, may be simply referred to as an "evaluation method"). INDUSTRIAL APPLICABILITY The present invention evaluates vibration characteristics by running a vehicle equipped with tires.

As the tires evaluated by the evaluation method of the present embodiment, tires of various categories such as pneumatic tires for passenger cars, motorcycles, heavy loads, and non-pneumatic tires that are not filled with air are adopted. To. Therefore, as the vehicle used in the present embodiment, various vehicles suitable for the tires are selected. In this specification, for example, an evaluation method using a pneumatic tire for a passenger car (four-wheeled vehicle) is described.

FIG. 1 is a flowchart showing a processing procedure of the evaluation method of the present embodiment. As shown in FIG. 1, the evaluation method of the present embodiment includes a first step S1, a second step S2, a third step S3, and a fourth step S4.

FIG. 2 is a schematic diagram illustrating the first step S1 and the second step S2 of the present embodiment. As shown in FIG. 2, in the first step S1 of the present embodiment, the vehicle 1 equipped with the tire 2 is made to run in a steady circular turn at a limit speed of a predetermined turning radius r. In the present specification, the "limit speed" is the speed immediately before the vehicle 1 starts skidding. "Steady circular turn" is to turn a substantially constant turning radius at a constant speed. Further, the turning radius r is preferably, for example, about 30 to 50 m in order to evaluate the vibration characteristics with high accuracy. As used herein, the term "substantially" means a radius that is constant within a range that can solve the problem of the present invention, and includes a range that is not constant in a strict sense.

FIG. 3 is a conceptual diagram showing the vehicle 1 of the present embodiment. As the vehicle 1, rear-wheel drive or all-wheel drive is adopted, but front-wheel drive is preferably adopted. The vehicle 1 includes, for example, a tire 2 and a steering wheel 3 for steering the vehicle 1. In the present embodiment, the tire 2 has a front wheel side tire 2F and a rear wheel side tire 2R, which are driving wheels. The vehicle 1 further includes, for example, an axle 4 connecting the front wheel side tire 2F and the steering wheel 3.

In the present embodiment, the tire 2 is mounted on all the wheels of the vehicle 1 by assembling the rim to a regular rim (not shown) and applying the regular internal pressure. The tire 2 is loaded with, for example, a load of about 45 to 70% of the normal load.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, JATMA is a standard rim, TRA is "Design Rim", or ETRTO. If there is, it means "Measuring Rim".

"Regular internal pressure" is the air pressure specified for each tire by the above standard. For JATMA, the maximum air pressure, for TRA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", ETRTO. If there is, it is "INFLATION PRESSURE", but in the case of passenger car tires, it is 180 kPa.

"Regular load" is the load specified for each tire by the above standard. If it is JATMA, it is the maximum load capacity. If it is TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", ETRTO. If so, it is "LOAD CAPACITY".

In the first step S1, for example, since the vehicle 1 travels to the limit, the steering angle H, which is the rotation angle of the steering wheel 3, travels at an angle within a certain range. The first step S1 is a necessary condition for quantitatively evaluating the vibration characteristics of the tire 2. In the evaluation method of the present embodiment, the evaluation accuracy can be improved by unifying this condition.

The second step S2 of the present embodiment is performed following the first step S1. In the second step S2, in the present embodiment, the vehicle 1 is driven at a speed equal to or higher than the limit speed and at an angle larger than the steering angle H at the time of the first step S1. As a result, the vehicle 1 starts skidding. When the vehicle 1 is understeer, the vehicle 1 skids in the same direction as the steering direction of the steering wheel 3. When the vehicle 1 is oversteered, the vehicle 1 skids in a direction different from the steering direction of the steering wheel 3. In this embodiment, the understeer vehicle 1 is preferably adopted. In the oversteer vehicle 1, spin is likely to occur, and it is difficult to increase the steering angle until vibration due to stick slip is generated.

In the present embodiment, the second step S2 includes a step of gradually increasing the steering angle H. As a result, the sudden skidding of the vehicle 1 is suppressed, so that the turning running can be continued for a relatively long time. Therefore, since the parameter P described later can be accurately acquired, the vibration characteristics can be evaluated accurately. From this point of view, it is desirable that the steering angle H increases at 20 to 40 degrees / sec. If the steering angle H is increased to exceed 40 degrees / sec, the vibration generation time may become excessively short, and the measurement accuracy may decrease. For such turning running in the second step S2, for example, it is desirable that the steering angle H is gradually increased by an automatic steering device having a well-known structure.

The third step S3 of the present embodiment acquires the parameter P related to the vibration characteristics of the tire 2 during traveling in the second step S2.

The parameter P includes at least one of the acceleration A acting on the vehicle, the steering angle H, or the slip angle S of the tire 2. In the present specification, the "slip angle S" means the angle difference between the traveling direction of the vehicle 1 and the direction of the tire 2.

Accelerometer A is detected by an acceleration sensor 6 having a well-known structure. As the acceleration sensor 6, for example, it is desirable that the accelerometer 6 is a piezoelectric type accelerometer capable of measuring accelerations in three orthogonal axes. The piezoelectric accelerometer can detect, for example, only the acceleration associated with vibration. The orthogonal three-axis directions are the front-rear direction x of the vehicle 1, the left-right direction y of the vehicle 1, and the vertical direction z of the vehicle 1.

The acceleration sensor 6 is substantially arranged at the center of gravity G of the vehicle 1 in a plan view of the vehicle 1, for example. As a result, the acceleration A can be detected accurately, so that the vibration characteristics can be evaluated accurately. From this point of view, the acceleration sensor 6 may be provided, for example, substantially at the axle 4 position of the front wheel (front wheel side tire 2F) of the vehicle 1 or at the driver's seat (steering wheel 3) position. By arranging the acceleration sensors 6 at a plurality of locations and adopting, for example, the average value of the accelerations A detected from these, the vibration characteristics can be evaluated more accurately.

The steering angle H is detected by a steering angle sensor 7 having a well-known structure. It is desirable that the steering angle sensor 7 is, for example, a well-known steering force angle meter capable of measuring the steering angle H of the steering wheel 3 and the steering torque applied to the steering wheel 3. The steering angle sensor 7 of the present embodiment is provided between the steering wheel 3 and the axle 4. The steering angle sensor 7 is not limited to such an embodiment, and may be, for example, a well-known steering wheel type (not shown) having the same shape as the steering wheel 3.

The slip angle S is detected by a slip angle sensor (not shown) having a well-known structure. Examples of the slip angle sensor include a sensor that detects a slip angle S based on the speed of the vehicle 1 in the front-rear direction x and a speed in the left-right direction y, a sensor that detects the slip angle S by an optical sensor, and a yaw rate of the vehicle 1. Those that detect the slip angle S based on the above are suitable. The slip angle sensor is provided, for example, on the front wheel side tires 2F on both sides. By measuring the slip angle S, for example, the slip angle S at the time of vibration generation can be specified. Further, by measuring the slip angle S, it can be confirmed that the slip angle of the tire in which vibration is generated is equal to or less than the slip angle of the tire in which vibration is not generated.

The accelerometer 6, steering angle sensor 7, and slip angle sensor are connected to control means (not shown, for example, including a well-known computer). The control means stores and outputs data sent from the acceleration sensor 6, the steering angle sensor 7, and the slip angle sensor, for example, time-series data.

In the third step S3, for example, the parameter P relating to the vibration characteristic of the tire 2 in the first step S1 may be acquired. As a result, the transition of the parameter P from the running in the state where the vehicle 1 does not cause skidding to the running in the state where the skid occurs can be acquired, so that the change in the parameter P can be grasped in detail, and the evaluation is made more accurately. can do.

The parameter P acquired in the third step S3 is not limited to such a parameter P, and may include, for example, a speed, a running time in the second stroke, and a tire yaw rate.

In the fourth step S4 of the present embodiment, the quality of the vibration characteristics is determined based on the parameter P. In such an evaluation method, vibrations that have been evaluated by sensuality in the past, in particular, vibrations caused by so-called stick slip, in which adhesion and slip are repeated on the contact surface between the tire 2 and the road surface that occurs during unsteady turning, are quantitatively evaluated. Can be evaluated.

In the fourth step S4 of the present embodiment, for example, at least one of the acceleration A, the steering angle H, and the slip angle S is used to determine the quality of the vibration characteristics.

In the fourth step S4, for example, the quality of the vibration characteristic is determined by using the maximum value of the acceleration A in the second step S2. Preferably, the absolute value of the acceleration A is adopted. For example, a tire having a small maximum acceleration A is evaluated to have better vibration characteristics than a tire having a large acceleration A. When the determination is made by the acceleration A in this way, for example, the time series data of the acceleration A is used. As the acceleration A, for example, it is desirable to use a lateral acceleration Ay in the left-right direction y.

Further, in the fourth step S4, for example, the quality of the vibration characteristic is determined by using the maximum value of the steering angle H. The maximum value of the steering angle H is generated, for example, in the second step S2 when the vehicle 1 becomes unable to make a circular turn due to a large skid. For example, a tire having a large maximum steering angle H is evaluated to have better vibration characteristics than a tire having a small steering angle H. When the determination is made based on the steering angle H in this way, for example, time-series data of the steering angle H is used.

Further, in the fourth step S4, for example, the acceleration A with respect to the slip angle S in the second step S2 is used to determine the quality of the vibration characteristics. In the present embodiment, the maximum value of the acceleration A with respect to the slip angle S in the second step S2 is used. As the acceleration A, it is particularly desirable to use the lateral acceleration Ay. For example, the quality of the vibration characteristic is determined based on the magnitude relationship of the acceleration A at a certain slip angle S and the threshold value of the acceleration A at a certain slip angle S. When the determination is made based on the slip angle S in this way, for example, time-series data of the slip angle S is used.

Further, the fourth step S4 is not limited to such an aspect, and for example, the quality of the vibration characteristic is determined by using the relationship between the steering angle H and the slip angle S in the second step S2. May be good. Further, for example, the quality of the vibration characteristic may be determined by using the time-series data of the yaw rate Y of the grip state of the tire 2 in the second step S2.

Further, in the fourth step S4, there are two or more types of time-series data of the acceleration A in the second step S2, the maximum value of the steering angle H, the acceleration A with respect to the slip angle S, and the relationship between the steering angle H and the slip angle S. The vibration characteristics may be evaluated using. Thereby, it is possible to determine the quality of the vibration characteristics based on the lateral acceleration Ay, the turning speed, the vehicle behavior based on the slip angle, and the vehicle motion characteristics based on the grip.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments.

The effect of the present invention will be described by determining the vibration characteristics of the tire based on the flowchart shown in FIG. Lateral acceleration Ay and steering angle H were used as the parameters P. As the test tires, the same two types of tires were used, which were previously turned and run, and the presence or absence of vibration due to stick slip was determined by the sensuality of the evaluator (test driver). The common specifications are as follows.
Turning radius r: 50m
Vehicle: Front-wheel drive vehicle with a displacement of 1600cc Tire size: 225 / 45R17
Tire internal pressure: 230kPa (front wheels), 220kPa (rear wheels)
Change in steering angle H during the second step: 30 degrees / sec Road surface: Flat and non-gradient dry asphalt road surface test tire 2A (hereinafter, simply referred to as "tire 2A") has good vibration characteristics depending on the evaluator (hereinafter, simply referred to as "tire 2A"). It was determined that there was no vibration), and the test tire 2B (hereinafter, simply referred to as “tire 2B”) was determined to have poor vibration characteristics (large vibration).

Graphs using the parameters acquired in the third step are shown in FIGS. 4 and 5. The left vertical axis of FIGS. 4 and 5 is the value of the lateral acceleration Ay, the horizontal axis is the time, and the right vertical axis is the value of the steering angle H. FIG. 4 is a graph of time-series data of lateral acceleration Ay and steering angle H acquired from the tire 2A. FIG. 5 is a graph of time-series data of the lateral acceleration Ay and the steering angle H acquired from the tire 2B. “V” in FIG. 5 indicates the time when the vibration occurred. “K” in FIGS. 4 and 5 indicates a boundary between the first step and the second step.

From FIGS. 4 and 5, the maximum absolute value of the lateral acceleration Ay of the tire 2A is about 1.5 m / s ² , and the maximum absolute value of the lateral acceleration Ay of the tire 2B is about 10 m / s ² . Is understood to be. That is, the tire 2A has a smaller absolute value of the lateral acceleration Ay than the tire 2B. As described above, based on the lateral acceleration Ay, it can be determined that the tire 2A has better vibration characteristics than the tire 2B.

Further, from FIGS. 4 and 5, it is understood that the maximum value of the steering angle H of the tire 2A is about 180 degrees, and the maximum value of the steering angle H of the tire 2B is about 160 degrees. That is, the tire 2A has a larger maximum steering angle H than the tire 2B. As described above, based on the steering angle H, it can be determined that the tire 2A has better vibration characteristics than the tire 2B.

As described above, according to the evaluation method of the present embodiment, the vibration characteristics, particularly the vibration characteristics derived from the stick slip, can be quantitatively evaluated by acquiring the parameters related to the vibration characteristics of the tire in the second step.

The tires 2A and 2B were tested multiple times, but the same results were obtained. Further, the same test was performed for tires having different tire sizes and rubber formulations, but the evaluation results were the same between the sensory evaluation by the evaluator and the evaluation method according to the present embodiment. Further, the same test was performed even when the parameter was the slip angle, but the evaluation results were the same between the sensory evaluation by the evaluator and the evaluation method according to the present embodiment. Therefore, it is understood that the evaluation method according to the present invention evaluates the vibration characteristics accurately and quantitatively.

Further, graphs using other parameters acquired in the third step are shown in FIGS. 6 and 7. The vertical axis of FIGS. 6 and 7 is the value of the lateral acceleration Ay, and the horizontal axis is the value of the steering angle H. FIG. 6 is a graph showing the relationship between the lateral acceleration Ay acquired from the tire 2A and the steering angle H. FIG. 7 is a graph showing the relationship between the lateral acceleration Ay acquired from the tire 2B and the steering angle H. “V” in FIG. 7 indicates that vibration has occurred. As is clear from FIGS. 6 and 7, since the maximum value of the steering angle H of the tire 2A is smaller than the maximum value of the steering angle of the tire 2B, it can be determined that the tire 2A has better vibration characteristics than the tire 2B. Further, it is possible to consider the tire 2 and the vibration generation by using such FIGS. 6 and 7.

Further, graphs using still other parameters acquired in the third step are shown in FIGS. 8 and 9. The vertical axis of FIGS. 8 and 9 is the value of the lateral acceleration Ay, and the horizontal axis is the value of the slip angle S. FIG. 8 is a graph showing the relationship between the lateral acceleration Ay and the slip angle S when the tire 2B is used as the front wheel side tire on the outer side of the turn during turning. FIG. 9 is a graph showing the relationship between the lateral acceleration Ay and the slip angle S when the tire 2B is used as the front wheel side tire inside the turn during turning. With reference to FIG. 8 or FIG. 9, it is possible to consider the tire 2 and the vibration generation.

1 Vehicle 2 Tire 3 Handle H Steering angle r Turning radius S1 1st process S2 2nd process S3 3rd process S4 4th process

Claims (6)

It is a method for evaluating the vibration characteristics of tires.
The first step of making the vehicle equipped with the tires run in a steady circular turn at a limit speed of a predetermined turning radius, and
Following the first step, the second step of turning the vehicle at a speed equal to or higher than the limit speed and making the steering angle of the steering wheel of the vehicle larger than the steering angle during the steady circular turning.
In the third step of acquiring parameters related to the vibration characteristics of the tire in the second step,
Including a fourth step of determining the quality of vibration characteristics based on the above parameters,
The parameter is the maximum value of acceleration acting on the tire.
A four-wheeled vehicle is used as the vehicle.
In the plan view of the vehicle, the acceleration is measured by using an acceleration sensor arranged at the center of gravity of the vehicle, an acceleration sensor arranged at the axle position of the front wheel of the vehicle, or an acceleration sensor arranged at the driver's seat position. Further including the step of detecting,
Evaluation method of vibration characteristics. It is a method for evaluating the vibration characteristics of tires.
The first step of making the vehicle equipped with the tires run in a steady circular turn at a limit speed of a predetermined turning radius, and
Following the first step, the second step of turning the vehicle at a speed equal to or higher than the limit speed and making the steering angle of the steering wheel of the vehicle larger than the steering angle during the steady circular turning.
In the third step of acquiring parameters related to the vibration characteristics of the tire in the second step,
Including a fourth step of determining the quality of vibration characteristics based on the above parameters,
The parameter is the maximum value of the steering angle.
Evaluation method of vibration characteristics. The evaluation method according to claim 1 or 2 , wherein the second step includes a step of gradually increasing the steering angle . The evaluation method according to any one of claims 1 to 3, wherein the steering angle increases at 20 to 40 degrees / sec . The evaluation method according to any one of claims 1 to 4 , wherein the vehicle is a front-wheel drive four-wheeled vehicle . The evaluation method according to any one of claims 1 to 5 , wherein the vehicle is understeer .

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