JP2017150986A - Tire performance testing method and on-table testing device for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire performance testing method capable of evaluating tire performance with high accuracy, and to provide an on-table testing device for a tire.SOLUTION: A tire performance evaluation method is to measure axial force of a tire T using a rotatable drum 2A having a travel face 3 allowing the tire T to travel, and then evaluate tire performance. The tire performance evaluation method includes an acquisition step to acquire the axial force acting on the tire T when, on a cross section of the drum 2A in the drum circumferential direction, the tire T travels on the travel face 3 including an equal-radius portion 6 with a constant radius, a standing portion 8 that stands from the equal-radius portion 6, and a gradually decreasing portion 9 where a height in the drum radius direction smoothly and gradually decreases from the standing portion 8 in order of the equal-radius portion 6, the standing portion 8 and the gradually decreasing portion 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire performance evaluation method capable of evaluating tire performance with high accuracy and a tire bench test apparatus used therefor.

  Conventionally, an evaluation method using an actual vehicle is known as a method for evaluating the ride performance based on hardness, for example, tire performance. As an actual vehicle evaluation method, for example, a test driver sensory evaluation method (hereinafter sometimes simply referred to as “sensory evaluation method”) or an evaluation method based on tire acceleration (hereinafter simply referred to as “acceleration evaluation method”). There is a case). The sensory evaluation method is based on the subjectivity of the test driver with respect to input (impact) when, for example, a tire to be evaluated is mounted on a vehicle and the vehicle runs on a step (projection) protruding from the road surface. The acceleration evaluation method is, for example, a vertical line direction acting on the tire when the tire to be evaluated is mounted on the vehicle and running on a protrusion protruding from the road surface (hereinafter simply referred to as “vertical direction”). It may be based on acceleration). These sensory evaluation methods and acceleration evaluation methods are known to have high correlation.

  However, such an evaluation method requires the vehicle to be driven by a test driver, which may cause a large test cost, for example. From such a viewpoint, a tire performance evaluation method using a bench test apparatus including a drum having a running surface on which a tire can travel is known. The evaluation method of the riding comfort performance based on the hardness using this bench test apparatus is, for example, that the protruding height from the running surface and the length in the drum circumferential direction are both 10 to 20 mm on the running surface of the drum. There has been known a method in which a rectangular protrusion is provided and evaluation is performed based on the axial force of the tire when the tire gets over the protrusion.

  However, the evaluation method using such a bench test apparatus has a problem that the correlation with the sensory evaluation method and the acceleration evaluation method is small and the evaluation cannot be performed with high accuracy.

JP 2012-137419 A

  The present invention has been devised in view of the above problems, and based on improving the running surface of the drum, the riding comfort performance is highly accurate based on the performance of the tire, for example, the hardness. The main purpose is to provide an evaluation method for tire performance that can be evaluated and a test apparatus for testing a tire.

  The present invention relates to a tire performance evaluation method for evaluating tire performance by measuring a tire axial force using a rotatable drum having a running surface on which the tire can travel, and in a drum circumferential section of the drum The running surface including an equal-diameter portion having a constant radius, a rising portion rising from the equal-diameter portion, and a gradually decreasing portion whose height in the drum radial direction gradually decreases from the rising portion. It has an acquisition process which acquires the axial force which acts on the tire when a tire runs in order of a diameter part, the starting part, and the taper part.

  In the tire performance evaluation method according to the present invention, it is desirable that the drum circumferential length of the gradually decreasing portion is larger than the drum circumferential length of the ground contact surface of the tire at the equal diameter portion.

  In the method for evaluating tire performance according to the present invention, it is desirable that the gradually decreasing portion has an arc shape in the cross section.

  In the tire performance evaluation method according to the present invention, in the cross section, it is desirable that the radius of curvature Ra of the gradually decreasing portion is 60% or more of the radius R of the equal diameter portion.

  The present invention is a tire bench test apparatus including a rotatable drum having a running surface on which a tire can run, wherein the running surface has a constant radius in the drum circumferential section of the drum. An equal-diameter portion, a rising portion rising from the equal-diameter portion, and a gradually decreasing portion in which the height in the drum radial direction gradually decreases gradually from the rising portion, the equal-diameter portion, the rising portion, and The tire is in contact with the tire in the order of the gradually decreasing portion.

  The tire performance evaluation method of the present invention measures the axial force of a tire using a rotatable drum having a running surface on which the tire can travel. In a cross section in the drum circumferential direction of the drum, an equal-diameter portion having a constant radius, a rising portion rising from the equal-diameter portion, and a gradually decreasing portion whose height in the drum radial direction gradually decreases gradually from the rising portion. An acquisition step of acquiring an axial force acting on the tire when the tire travels in the order of the equal-diameter portion, the rising portion, and the gradually decreasing portion on the traveling surface including In such an acquisition process, the tire can acquire a large input by climbing the rising portion from the equal-diameter portion, and the gradual decreasing portion can reduce the input by the lowering from the rising portion. Thereby, in the tire performance evaluation method of this invention, the performance of a tire, for example, the riding comfort performance based on hardness, can be evaluated with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view conceptually showing a tire bench test apparatus according to an embodiment of the present invention. It is sectional drawing of the circumferential direction of a drum. It is a correlation diagram of the axial force acquired by the evaluation method of Example 1, and the acceleration acquired by the acceleration evaluation method. It is a graph showing the time change of the axial force acquired by the evaluation method of Example 1, and the time change of the acceleration acquired by the acceleration evaluation method. It is a graph showing the time change of the axial force acquired by the evaluation method of a prior art example, and the time change of the acceleration acquired by the acceleration evaluation method.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The tire performance evaluation method of the present embodiment (hereinafter sometimes simply referred to as “evaluation method”) includes an acquisition step of acquiring the axial force of the traveling tire T. The tire performance evaluated by the evaluation method of the present embodiment is a performance related to tire traveling, and includes, for example, riding comfort performance, steering stability performance, rough road traveling performance, vibration performance, and the like.

  The tire T used in the evaluation method of the present embodiment is not particularly limited. Examples of the tire T include various categories of pneumatic tires such as heavy duty tires, passenger tires, and motorcycle tires, and pneumatic tires. An airless tire or the like having a different structure is employed.

  As shown in FIG. 1, in the acquisition process of the present embodiment, a bench test apparatus (hereinafter simply referred to as “apparatus”) 1 that can travel a tire T without using a vehicle is used. The device 1 used in the acquisition process is not limited to such a device, and for example, a well-known drum testing device (not shown) having a running surface 3 on which a tire T attached to a vehicle can run. May be used.

  In the present embodiment, the device 1 includes a drum 2 that is rotatable in the circumferential direction, a tire holding means 4 that rotatably holds the tire T, and a measuring means 5 that measures the axial force of the tire T.

  In this embodiment, the drum 2 includes a cylindrical drum body 2A having a running surface 3 on the outer peripheral surface on which the tire T can continuously travel in the drum circumferential direction, and a drum rotation shaft 2B that rotates the drum body 2A. Yes. The running surface 3 of the drum body 2A is formed of, for example, a material (not shown) that conforms to the ISO road surface standard particle size curve (see the asphalt mixture particle size curve allowable range described in the Annex C design guidelines of ISO 10844). Yes.

  The running surface 3 includes a constant diameter portion 6 having a constant radius (shown in FIG. 2) R in the cross section in the drum circumferential direction of the drum 2, a rising portion 8 rising from the constant diameter portion 6, and a height in the drum radial direction. The length H includes a gradually decreasing portion 9 that gradually decreases from the rising portion 8. That is, the running surface 3 is formed with a projecting portion 7 that protrudes outward in the drum radial direction from the equal diameter portion 6 by the rising portion 8 and the gradually decreasing portion 9. The radius R of the equal diameter portion 6 is the length in the drum radial direction from the rotation axis c of the drum 2 to the outer surface of the equal diameter portion 6.

  The equal diameter part 6 and the protrusion part 7 are formed of the same material in this embodiment. In addition, the equal diameter part 6 and the protrusion part 7 may be formed with a different material, for example, only the protrusion part 7 may be formed with a metal material or a cured resin material.

  In the present embodiment, two protrusions 7 are provided on the traveling surface 3. In the case where there is one protrusion 7, the rotational axis c of the drum 2 and the center of gravity (not shown) of the drum 2 are displaced in the cross section, so that the running of the tire T becomes unstable and the tire performance is improved with high accuracy. There is a possibility that it cannot be evaluated. For this reason, it is desirable that 2 to 8 protrusions 7 are formed at equal pitches in the drum circumferential direction.

  The rising portion 8 extends linearly and parallel to the rotational axis c of the drum 2 in the width direction. Thereby, since the starting part 8 and the tread surface Ta of the tire T can contact almost simultaneously over the width direction, axial force can be acquired accurately.

  The width Wa in the drum shaft direction of the protrusion 7 is preferably larger than the maximum width W of the tire T, for example, in order to evaluate the riding comfort performance of the tire T with high accuracy, and is 110% of the maximum width W of the tire T. About 150% is more desirable.

  As shown in FIG. 2, the rising portion 8 extends in the drum radial direction in the cross section in the present embodiment. The rising portion 8 may be inclined with respect to the drum radial direction, for example. In this case, the rising portion 8 is inclined in the direction opposite to the direction of the gradually decreasing portion 9 with respect to the drum radial direction in the cross section in order to suppress the strength of the protrusion 7 and damage to the tire T. desirable.

  The rising portion 8 preferably has a height H in the drum radial direction of, for example, about 10 to 30 mm, and a length L1 in the drum circumferential direction of 2 mm or less. Thereby, for example, when the tire T travels from the equal-diameter portion 6 to the rising portion 8 without passing through the gradually decreasing portion 9, when the rising portion 8 contacts the tire T, the tire T contacts the upper portion of the rising portion 8. Therefore, it is possible to acquire a large axial force by riding on the rising portion 8. In addition, the axial force acquired in this way has a big correlation with the evaluation method by a real vehicle run, as described in the below-mentioned Example.

  The gradually decreasing portion 9 is formed in an arc shape in the cross section. Thereby, the drum circumferential direction length L2 of the gradual reduction part 9 is ensured large. In the present embodiment, the gradually decreasing portion 9 is a circular arc that protrudes outward in the drum radial direction. As a result, the input to the tire T traveling through the gradually decreasing portion 9 is kept small.

  The length L2 of the gradually decreasing portion 9 in the drum circumferential direction is preferably larger than the drum circumferential length La of the contact surface of the tire T at the equal diameter portion 6. Thereby, since the change in the height of the gradually decreasing portion 9 in the drum radial direction becomes gentle, the change in input when getting on and off from the rising portion 8 can be reduced.

  The contact surface is a shape of the tire T in a normal load state. In this specification, “normal load load state” means a state in which a normal load is applied to a tire that is assembled with a normal rim and filled with a normal internal pressure, and the tire is grounded to the constant diameter portion 6 at a camber angle of 0 °. Say. The “regular rim” is a rim determined for each tire in a standard system including a standard on which a tire is based. For example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO Then means "Measuring Rim". The “regular internal pressure” is the air pressure defined by the standard for each tire. The maximum air pressure for JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for ETRA, Means "INFLATION PRESSURE". The “regular load” is a load determined by the standard for each tire, and if it is JATMA, the maximum load capacity, and if it is TRA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” If it is ETRTO, it is "LOAD CAPACITY".

  The gradually decreasing portion 9 preferably has a curvature radius Ra of 60% or more of the radius R of the equal diameter portion 6. When the radius of curvature Ra of the gradually decreasing portion 9 is less than 60% of the radius R of the equal-diameter portion 6, there is a possibility that the change in input when getting on and off the rising portion 8 cannot be reduced. If the radius of curvature Ra of the gradually decreasing portion 9 is excessively large, the gradually decreasing portion 9 becomes linear, and conversely, the drum circumferential length L2 of the gradually decreasing portion 9 cannot be ensured to be large. From this point of view, the radius of curvature Ra of the gradually decreasing portion 9 is desirably about 150% or less of the radius R of the equal-diameter portion 6.

  Note that the gradually decreasing portion 9 has an end portion 9 a on the contact side with the constant diameter portion 6 that is connected to the constant diameter portion 6 substantially smoothly. “Substantially” includes those in which the end portion 9a has a height h in the drum radial direction of 1.5 mm or less.

  The drum rotating shaft 2B is rotationally driven by driving means (not shown) including an electric motor provided with an inverter or the like that can freely adjust the rotational speed.

  The tire holding means 4 includes a support shaft 4A that rotatably holds the tire T, and a moving device (not shown) that moves the support shaft 4A up and down or laterally. As a result, the tire T held by the support shaft 4 </ b> A is pressed against the running surface 3 of the drum 2 and runs.

  The measuring means 5 includes, for example, a well-known six-component load cell such as a load cell that can detect the input received by the tire T from the running surface 3 by decomposing the input into three orthogonal component forces (axial force) and three moments. . In this embodiment, the measuring means 5 is attached to the bearing of the support shaft 4A.

  The measuring means 5 of this embodiment is connected to a processing device (not shown) having a known structure that displays the axial force measured by a 6-component force load meter for each traveling time. Note that the processing device may further include, for example, a function of analyzing the axial force frequency.

  In the acquisition process of the present embodiment, the axial force acting on the tire T is acquired when the tire T travels in the order of the equal diameter portion 6, the rising portion 8, and the gradually decreasing portion 9 along the drum circumferential direction. Is done. In the acquisition process, such traveling may be repeated a plurality of times.

  In the present embodiment, the acquired axial force of the tire T is a load (input) in the Z-axis direction that acts on the tire T. The axial force acquired by the evaluation method of the present invention may be a load in either the X-axis direction or the Y-axis direction, or may be a total load or average load in the X-axis, Y-axis, and Z-axis directions. good. In this specification, the Z-axis direction is the vertical direction. The Y-axis direction is a direction parallel to the tire rotation axis. The X axis direction is a direction orthogonal to the Y axis and the Z axis.

  Next, an evaluation process for evaluating tire performance is performed based on the axial force acquired in the acquisition process. In this embodiment, the axial force peak-to-peak value P (shown in FIG. 4) acquired in the acquisition process is evaluated. For example, a tire T having a large peak toe peak value P is evaluated as being harder in ride comfort performance based on hardness than a tire T having a small peak toe peak value P. Conversely, the tire T having a small peak toe peak value P is evaluated as being softer in terms of riding comfort performance based on the hardness than the tire T having a large peak toe peak value P.

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

  In order to confirm the effect of the present invention, the axial force of the traveling tire was acquired by the tire performance evaluation method of this embodiment and the conventional tire performance evaluation method. Moreover, acceleration was acquired by a known acceleration evaluation method using the same test tire. The correlation coefficient between the peak toe peak value P of the axial force and the peak toe peak value P1 of acceleration (shown in FIG. 4) is calculated, and the result is shown in Table 1. FIG. 3 shows a correlation diagram in which the vertical axial force according to the first embodiment is taken on the horizontal axis and the acceleration obtained by the acceleration evaluation method is taken on the vertical axis. The common specifications are as follows.

<Test tire>
Tire size: 235 / 45RF19
Rim: 19 × 8.0J
Internal pressure: 250kPa
In each test, ten different hardnesses were used.
<Bench testing equipment>
Axial force measuring tool: Load cell (Piezoelectric element (Kistler))
Measuring axial force: Vertical axial force Isometric part specification: Mixing of aggregate and binder (common to both conventional and examples)
Radius R of equal diameter part: 1500mm
Tire rotation speed: 30km / h
Drum circumferential length La: 150mm
Protrusion material: Steel (SS400)
The width of the protrusion in the drum axis direction: the same in both the conventional example and the example <Running surface of the example>
Height of the end of the taper part h: 1mm
<Actual vehicle running test (acceleration in the vertical direction)>
Speed: 50-70km / h
Measurement: Acquire acceleration when climbing a step of 25mm height provided on the asphalt road surface Accelerometer: 3-axis strain type accelerometer (ARF-20A-T (manufactured by Tokyo Sokki Kenkyujo Co., Ltd.))
Measurement location: Unsprung vehicle Vehicle: 3000cc passenger car

  As shown in Table 1, the axial force acquired using the evaluation method of the embodiment has a high correlation with the acceleration obtained by the acceleration evaluation method. Therefore, it can be said that this evaluation method has a high correlation with the sensory evaluation method, so that the ride comfort performance can be evaluated with high accuracy. Further tests were performed by changing the tire size and the shape of the protrusions within a preferable range, and the test results showed the same tendency as the test.

  Moreover, the axial force change (solid line) acquired using the protrusion of Example 1 and the acceleration change (broken line) acquired by the acceleration evaluation method in the above test are shown in FIG. Furthermore, FIG. 5 shows the axial force change (solid line) acquired using the protrusion of Conventional Example 1 and the acceleration change (broken line) acquired by the acceleration evaluation method in the above test. Each value is an average of 10 tires used in the test. In each figure, one vertical axis is the vertical axial force, the other vertical axis is the acceleration, and the horizontal axis is the elapsed time. In the figure, A is the position where the protrusion starts, B is the position immediately after the protrusion, C indicates a position where the axial force and acceleration first become zero after A.

  From the graph of FIG. 4, it can be understood that both the axial force change and the acceleration change change with the same tendency from A to C. Moreover, from the graph of FIG. 5, although the axial force change and the acceleration change are changing with the same tendency in AB, the tendency of these changes is different in BC. That is, in FIG. 5, in B to C, the axial force is uniformly reduced, whereas the acceleration is increased and decreased. For this reason, it is considered that the evaluation method of the present embodiment in which the tire travels on the traveling surface including the gradually decreasing portion has higher correlation than the evaluation method of Conventional Example 1.

2A Drum 3 Running surface 6 Equi-diameter part 8 Start-up part 9 Gradually decreasing part T Tire

Claims (5)

A tire performance evaluation method for evaluating tire performance by measuring a tire axial force using a rotatable drum having a running surface on which the tire can travel,
An equal-diameter portion having a constant radius, a rising portion rising from the equal-diameter portion, and a gradually decreasing portion whose height in the drum radial direction gradually decreases from the rising portion in a cross section in the drum circumferential direction of the drum; An acquisition step of acquiring an axial force acting on the tire when the tire travels in the order of the equal-diameter portion, the rising portion, and the gradually decreasing portion. Evaluation method of tire performance.   2. The tire performance evaluation method according to claim 1, wherein a length in the drum circumferential direction of the gradually decreasing portion is larger than a length in the drum circumferential direction of the ground contact surface of the tire at the equal diameter portion.   The tire performance evaluation method according to claim 1, wherein the gradually decreasing portion has an arc shape in the cross section.   The tire performance evaluation method according to claim 3, wherein, in the cross section, a radius of curvature Ra of the gradually decreasing portion is 60% or more of a radius R of the equal diameter portion. A tire bench test apparatus comprising a rotatable drum having a running surface on which the tire can travel,
In the drum circumferential section of the drum, the running surface has an equal-diameter portion having a constant radius, a rising portion that rises from the equal-diameter portion, and a height in the drum radial direction that is smooth from the rising portion. A gradually decreasing portion that gradually decreases,
A tire bench test apparatus, which comes into contact with a tire in the order of the equal-diameter portion, the rising portion, and the gradually decreasing portion.

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