Tire measuring device and tire measuring method

Abstract

To measure a physical quantity acting on a tread of a tire during traveling accurately.SOLUTION: A measuring device 1 includes: a rotatable drum 2 having a travel road surface 10 for allowing a tire T to travel; and at least one measuring device 3 for measuring a physical quantity acting on a tread Ta of the tire T. The travel road surface 10 includes: a first road surface part 11 to which the measuring device 3 is attached; and a second road surface part 12 which is disposed at a position different from that of the first road surface part 11 in a drum circumferential direction and has a frictional coefficient larger than that of the first road surface part 11.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a tire measuring device and a tire measuring method.

Background Art

[0002] Patent Document 1 below describes a test device used for measuring the contact surface stress of a tire. This test device includes a drum that can rotationally drive the tire. Further, a tire stress measuring device is provided at at least one location on the road surface of the drum. This device can measure the contact surface stress by running the tire on the road surface of the drum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, tires for motor sports and tires with high temperature dependence of tread rubber cannot exhibit the original performance of the tire (especially grip force) unless the tread rubber rises to a certain temperature. For this reason, when this type of tire is run on a conventional test device, there is a problem that the tire slips with respect to the drum and the physical quantities acting on the tread surface of the running tire cannot be accurately measured.

[0005] The present disclosure has been devised in view of the above actual situation, and the main object is to provide a tire measuring device and a tire measuring method that can accurately measure the physical quantities acting on the tread surface of a running tire.

Means for Solving the Problems

[0006] The present disclosure relates to a measuring device for measuring physical quantities acting on the tread surface of a tire during travel, including a rotatable drum having a travel road surface for causing the tire to travel, and at least one measuring instrument for measuring physical quantities acting on the tread surface of the tire. The travel road surface includes a first road surface portion to which the measuring instrument is attached, and a second road surface portion that is arranged at a position different from the first road surface portion in the circumferential direction of the drum and has a friction coefficient greater than that of the first road surface portion.

Advantages of the Invention

[0007] By adopting the above configuration, the measuring device for a tire and the method for measuring a tire according to the present disclosure can accurately measure physical quantities acting on the tread surface of a tire during travel.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a side view of a measuring device 1 (hereinafter sometimes simply referred to as "device") according to the present embodiment. The device 1 of the present embodiment is for measuring a physical quantity F acting on the tread surface Ta of a tire T during travel. The physical quantity F measured by the device 1 of the present embodiment is, for example, a shear stress in the tire axial direction, a shear stress in the tire circumferential direction, and a vertical stress in the tire radial direction, etc. It should be noted that the physical quantity F is not limited to these stresses.

[0010] In this specification, the tread surface Ta, in the case of a pneumatic tire, is the area that contacts the plane when the tire T is mounted on a standard rim (not shown), filled with the standard internal pressure, and grounded on the plane at a camber angle of 0 degrees under the standard load. The "standard rim" is the rim defined for each tire in the standard system including the standard on which the tire is based. For example, in the case of JATMA, it means the standard rim; in the case of TRA, it means "Design Rim"; or in the case of ETRTO, it means "Measuring Rim". The "standard internal pressure" is the air pressure defined for each tire by the standard. In the case of JATMA, it means the maximum air pressure; in the case of TRA, it means the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; in the case of ETRTO, it means "INFLATION PRESSURE". The "standard load" is the load defined for each tire by the standard. In the case of JATMA, it means the maximum load capacity; in the case of TRA, it means the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; in the case of ETRTO, it means "LOAD CAPACITY".

[0011] The tire T for measuring the physical quantity F is preferably, for example, a motor sports tire with a high temperature dependence of tread rubber. However, the tire T is not limited thereto, and various pneumatic tires such as heavy-duty tires, passenger car tires, or motorcycle tires, and airless tires having a structure different from that of pneumatic tires are adopted.

[0012] As shown in FIG. 1, the apparatus 1 of the present embodiment includes a drum 2 for running the tire T and a measuring instrument 3 for measuring the physical quantity F. The apparatus 1 also includes a thermometer 4 for measuring the temperature of the tire T, a drum support 5 for rotatably supporting the drum 2, and a tire support 6 for supporting the tire T.

[0013] The drum 2 of this embodiment includes an annular drum body 2A having an inner peripheral surface 2i extending in the circumferential direction of the drum, a first side surface portion 2B disposed on one side in the drum axis direction of the drum body 2A, and a second side surface portion 2C disposed on the other side in the drum axis direction of the drum body 2A. The first side surface portion 2B is connected to, for example, the drum support 5. The second side surface portion 2C is provided with an opening O for taking in and out the tire T in this embodiment.

[0014] A running road surface 10 on which the tire T can continuously run is provided on the inner peripheral surface 2i of the drum body 2A. Thus, the drum 2 of this embodiment is an inside drum type in which the running road surface 10 is formed on the inner peripheral surface 2i of the drum 2. However, the drum 2 of the present disclosure is not limited to the inside drum type, and for example, an outside drum type in which a running road surface is formed on the outer peripheral surface 2e of the drum 2 may be used (not shown).

[0015] The drum support 5 rotatably supports the drum 2 around a horizontal axis j2. The drum support 5 of this embodiment includes a support shaft 5A having one end fixed to the first side surface portion 2B of the drum 2, and a driving tool 5B that rotationally drives the support shaft 5A. Such a drum support 5 is configured with a well-known structure.

[0016] The tire support 6 includes a tire support shaft 6A that rotatably supports the tire T, and a tire moving tool 6B that moves the tire support shaft 6A. The tire support shaft 6A includes a driving tool such as a motor (not shown) for rotationally driving the tire T. The tire moving tool 6B moves the tire T in the drum axis direction and the drum radius direction. The tire moving tool 6B can bring the tread surface Ta of the tire T into contact with the running road surface 10 with a predetermined load. Note that the tire support 6 may include, for example, an axis angle adjuster (not shown) that changes the tire axis direction of the supported tire T at an arbitrary angle with respect to the drum axis direction. Thereby, it becomes possible to apply an arbitrary camber angle and slip angle to the tire T. Such a tire support 6 is configured with a well-known structure. Note that the tire support 6 may have a well-known structure in which the tire T rotates following the rotation of the drum 2.

[0017] The running road surface 10 is formed by, for example, a plane parallel to the axis j2. Such a running road surface 10 is useful for accurately measuring the physical quantity F.

[0018] FIG. 2 is a longitudinal sectional view of the running road surface 10. FIG. 3 is a partial perspective view of the running road surface 10. As shown in FIGS. 2 and 3, the running road surface 10 includes a first road surface portion 11 to which the measuring instrument 3 is attached, and a second road surface portion 12 that is arranged at a position different from that of the first road surface portion 11 in the circumferential direction of the drum and has a friction coefficient larger than that of the first road surface portion 11. Such a second road surface portion 12 deforms the tread portion of the tire T to increase the temperature. Therefore, the device 1 of the present disclosure can accurately measure the physical quantity F acting on the tread surface Ta.

[0019] In this specification, the friction coefficient is obtained as follows. First, the tire T is non-rotatably constrained by the tire support 6. Next, the tread surface Ta of the constrained tire T is pressed against the running road surface 10 of the drum 2 with a predetermined load Fz. Then, the drum 2 is rotated at a predetermined rotational speed. The friction coefficient is the value (Fx / Fz) obtained by dividing the longitudinal force Fx generated in the tire T at this time by the load Fz.

[0020] The first road surface portion 11 of the present embodiment is provided with a base surface 11A that comes into contact with the tread surface Ta of the tire T during running, and a concave portion 11B that is recessed outward in the drum radius direction from the base surface 11A. A measuring instrument 3 is attached to the concave portion 11B of the present embodiment so as to be able to measure the physical quantity F.

[0021] In the present embodiment, the measuring instrument 3 employs a three-component force sensor composed of a well-known load cell. In the case of a three-component force sensor, its detection portion is arranged so as to contact the tread surface Ta of the tire T.

[0022] The measuring instrument 3 is connected to, for example, a processing tool (not shown) for processing the measurement result. As the processing tool, a well-known microcomputer including, for example, a CPU (central processing unit) and a memory is preferably used.

[0023] It is desirable that a plurality of measuring instruments 3 be attached to the first road surface portion 11, for example. The plurality of measuring instruments 3 are preferably arranged in the drum axis direction and the drum circumferential direction, for example. Thereby, an accurate shear stress distribution and vertical stress distribution can be measured. In this case, a plurality of concave portions 11B are provided in the first road surface portion 11 (not shown).

[0024] The base surface 11A is formed as a smooth surface with a small coefficient of friction, for example. The base surface 11A is formed of a metal material such as iron or copper alloy such as steel or stainless steel, for example.

[0025] The second road surface portion 12 is formed as a rough road with a large coefficient of friction, for example. Such a second road surface portion 12 further deforms the tire T to promote a temperature rise. Further, such a second road surface portion 12 heats the tire T to soften its tread portion. Thereby, it is difficult to generate vibrations on the base surface 11A and the third road surface portion 13 described later, for example, vibrations caused by so-called stick-slip that occur when the adhesion and slip of the tire T are repeated. Such a rough road is preferably an asphalt road. The asphalt road gives a large frictional force to the tire T and gives a deformation due to unevenness including voids. The asphalt road is preferably formed of a material conforming to, for example, the particle size curve of the ISO road surface standard (refer to the allowable range of the particle size curve of the asphalt mixture described in the appendix C design guidelines of ISO10844).

[0026] In order to effectively exert the above-described effects, the texture depth (TD) of the asphalt road is preferably 1.0 mm or more. Also, the skid resistance value of the asphalt road is preferably 50 BPN or more. In addition, in order to suppress damage to the tread surface Ta of the tire T, the texture depth (TD) is preferably 1.5 mm or less. Also, the skid resistance value is preferably 90 BPN or less. The texture depth (TD) is determined by a sand patch test. The sand patch test is the average depth of a sand layer obtained by spreading sand of a known volume circularly on the road surface and dividing this volume by the area of the spread sand. The skid resistance value is a value measured using a skid resistance measuring device (for example, SKID-FRICTION TR300 Model B manufactured by MASTRAD).

[0027] The length L2 of the second road surface portion 12 in the drum circumferential direction is preferably larger than the length L1 of the first road surface portion 11 in the drum circumferential direction. Thereby, the temperature of the tire T can be raised quickly. Although not particularly limited, the length L2 of the second road surface portion 12 is preferably about 8 to 15 times the length L1 of the first road surface portion 11.

[0028] Also, the driving road surface 10 further includes a third road surface portion 13 having a smaller coefficient of friction than the second road surface portion 12. And in order to stabilize the contact state of the tire T and measure the physical quantity F, when the drum 2 is rotated in the first direction N, it is desirable that the second road surface portion 12, the third road surface portion 13, and the first road surface portion 11 appear in this order with respect to the tire T. Such a third road surface portion 13 can suppress (reduce) the deformation of the transient contact state (contact shape) that occurs at the moment of switching from the second road surface portion 12 to the third road surface portion 13. Thereby, since the tire T with the deformation of the contact state suppressed in the third road surface portion 13 continues to travel on the first road surface portion 11, the physical quantity F is accurately measured.

[0029] In order to effectively exert the above-described effects, the length L3 of the third road surface portion 13 in the drum circumferential direction is preferably 50% to 100% of the circumference of the tire T.

[0030] In this embodiment, the third road surface portion 13 and the first road surface portion 11 are formed from smooth surfaces having the same coefficient of friction. More specifically, the base surface 11A of the third road surface portion 13 and the first road surface portion 11 is formed from a smooth surface having the same coefficient of friction. As a result, the transient deformation suppressed by the third road surface portion 13 can also be continuously suppressed by the first road surface portion 11, so that the grounding state is stabilized, and thus the physical quantity F can be measured more accurately. In this specification, the "smooth surface" refers to a surface having a sliding resistance value of less than 50 BPN.

[0031] The third road surface portion 13 is formed of, for example, the same material as the base surface 11A. Thereby, the above-described action is effectively exerted. In this case, however, the boundary between the base surface 11A and the third road surface portion 13 may become unclear. When such an unclear situation occurs, the boundary is set at a position 100 mm away in the circumferential direction of the drum from the measuring instrument 3 that first contacts the tire T after rotating the drum 2 in the first direction N and bringing the tire T into contact with the second road surface portion 12.

[0032] As shown in FIG. 1, the thermometer 4 has a function of measuring, for example, the surface temperature of the tire T. In this embodiment, the thermometer 4 measures the surface temperature of the tread surface Ta of the tire T. The thermometer 4 is preferably a non-contact type such as the Sensortech TIR series (manufactured by Sensortech Co., Ltd.).

[0033] Next, a measuring method for measuring the physical quantity F using this apparatus 1 will be described. The measuring method of this embodiment includes a running step of running the tire T on the running road surface 10 of the drum 2. In the running step, the tire T is rotatably supported by the tire support 6. Further, the drum 2 is rotated in the first direction N by the drum support 5, and the running road surface 10 of the drum 2 and the tread surface Ta of the tire T are in contact with each other. As a result, the tire T rotates, and the physical quantity F acts on the tread surface Ta of the tire T. Further, in the running step, the surface temperature of the tread surface Ta of the tire T is measured by the thermometer 4.

[0034] FIG. 4 is a flowchart of the running process. As shown in FIG. 4, the running process includes a first step S1 of promoting heat generation of the tire T and a second step S2 of measuring the physical quantity F of the tire T.

[0035] In the first step S1, for example, it is desirable to run the tire T on a portion of the running road surface 10 where the friction coefficient is relatively large. In the present embodiment, in the first step S1, the tire T runs on at least the second road surface portion 12.

[0036] In the first step S1, the surface temperature of the tread Ta is heated to a predetermined temperature (T1 ° C). The predetermined temperature (T1 ° C) is desirably a temperature at which the rise in the surface temperature is 2 ° C or less per minute. Such a temperature is, for example, the temperature of the tire T in circuit running, which helps to accurately measure the physical quantity F. In the first step S1, in order to heat the tire T to the predetermined temperature (T1 ° C), the running road surface 10 including the second road surface portion 12 is run around a plurality of times by the tire T. The predetermined temperature (T1 ° C) is, for example, 30 to 50 ° C.

[0037] In the second step S2, in the present embodiment, the physical quantity F of the tire T is measured by the measuring instrument 3 arranged on the first road surface portion 11. In the present embodiment, the tire T runs from the second road surface portion 12 to the third road surface portion 13. Thereby, the deformation of the grounding state generated at the boundary between the second road surface portion 12 and the third road surface portion 13 is suppressed on the third road surface portion 13. Then, the tire T runs on the first road surface portion 11 after the third road surface portion 13. That is, the measuring instrument 3 on the first road surface portion 11 can measure the physical quantity F with the tire T in a state where the deformation of the grounding state is suppressed on the third road surface portion 13. Therefore, with the measuring method of the present disclosure, the physical quantity F can be measured accurately.

[0038] Note that after the second step S2, an evaluation step of evaluating tire performance may be performed based on the physical quantity F obtained in the second step S2. In the second step S2 of the present embodiment, since the shear stress in the tire axial direction, the shear stress in the tire circumferential direction, the vertical stress in the tire radial direction, etc. are obtained, for example, various tire performances such as the grip performance, wear resistance performance, and snow performance of the tire T can be evaluated.

[0039] As described above, the preferred embodiments of the present disclosure have been described in detail. However, the present disclosure is not limited to the illustrated embodiments and can be implemented in various forms.

[0040] [Appendix] The present disclosure includes the following aspects.

[0041] [Disclosure 1] A measuring device for measuring a physical quantity acting on the tread surface of a tire during running, A rotatable drum having a running road surface for running the tire, And at least one measuring instrument for measuring a physical quantity acting on the tread surface of the tire, The running road surface includes a first road surface portion to which the measuring instrument is attached, and a second road surface portion that is arranged at a position different from the first road surface portion in the drum circumferential direction and has a larger friction coefficient than the first road surface portion, A measuring device for a tire. [Disclosure 2] The measuring device for a tire according to Disclosure 1, wherein the second road surface portion is a rough road surface. [Disclosure 3] The measuring device for a tire according to Disclosure 1 or 2, wherein the second road surface portion is an asphalt road surface. [Disclosure 4] The measuring device for a tire according to Disclosure 3, wherein the texture depth of the asphalt road surface is 1.0 mm or more. [Disclosure 5] The measuring device for a tire according to Disclosure 3 or 4, wherein the skid resistance value of the asphalt road surface is 50 BPN or more. [Disclosure 6] The measuring device for a tire according to any one of Disclosures 1 to 5, wherein the length of the second road surface portion in the circumferential direction of the drum is larger than the length of the first road surface portion in the circumferential direction of the drum. [Disclosure 7] The running road surface further includes a third road surface portion having a smaller coefficient of friction than the second road surface portion. The measuring device for a tire according to any one of Disclosures 1 to 6, wherein when the drum is rotated in the first direction, the second road surface portion, the third road surface portion, and the first road surface portion are arranged to appear in this order. [Disclosure 8] The measuring device for a tire according to Disclosure 7, wherein the first road surface portion and the third road surface portion are formed of smooth surfaces having the same coefficient of friction. [Disclosure 9] The measuring device for a tire according to Disclosure 7 or 8, wherein the length of the third road surface portion in the circumferential direction of the drum is 50% or more of the circumferential length of the tire. [Disclosure 10] A measuring method for measuring a physical quantity acting on the tread surface of a tire during running, including a running step of running the tire on a running road surface of a rotatable drum. The running step includes a first running step of running the tire on a portion of the running road surface having a relatively large coefficient of friction to promote heat generation, and a second running step of measuring the physical quantity while running the tire on a portion of the running road surface having a relatively small coefficient of friction after the first running step. Measuring method for a tire. [Disclosure 11] The measuring method for a tire according to Disclosure 10, wherein in the first running step, heat is generated until the surface temperature of the tread surface of the tire reaches a predetermined temperature. [Disclosure 12] The measuring method for a tire according to Disclosure 11, wherein the predetermined temperature is a temperature at which the rise in the surface temperature is 2°C or less per minute.

Explanation of reference numerals

[0042] 1 Measuring device 2 Drum 3 Measuring instrument 10 Traveling road surface 11 First road surface part 12 Second road surface part T Tire Ta Tread

Claims

1. A measuring device for measuring a physical quantity acting on the tread surface of a tire during running, comprising: a rotatable drum having a running road surface for running the tire; at least one measuring instrument for measuring a physical quantity acting on the tread surface of the tire, wherein the running road surface includes a first road surface portion to which the measuring instrument is attached, and a second road surface portion that is arranged at a position different from the first road surface portion in the circumferential direction of the drum and has a larger friction coefficient than the first road surface portion; the second road surface portion is a rough road surface; A measuring device for a tire.

2. The measuring device for a tire according to claim 1, wherein the second road surface portion is an asphalt road surface.

3. A measuring device for measuring a physical quantity acting on the tread surface of a tire during running, comprising: a rotatable drum having a running road surface for running the tire; at least one measuring instrument for measuring a physical quantity acting on the tread surface of the tire, wherein the running road surface includes a first road surface portion to which the measuring instrument is attached, and a second road surface portion that is arranged at a position different from the first road surface portion in the circumferential direction of the drum and has a larger friction coefficient than the first road surface portion; the second road surface portion is an asphalt road surface; A measuring device for a tire.

4. The measuring device for a tire according to claim 2 or 3, wherein the texture depth of the asphalt road surface is 1.0 mm or more.

5. The measuring device for a tire according to any one of claims 2 to 4, wherein the skid resistance value of the asphalt road surface is 50 BPN or more.

6. A measuring device for measuring a physical quantity acting on the tread surface of a tire during running, comprising: a rotatable drum having a running road surface for running the tire; at least one measuring instrument for measuring a physical quantity acting on the tread surface of the tire, wherein the running road surface includes a first road surface portion to which the measuring instrument is attached, and a second road surface portion that is arranged at a position different from the first road surface portion in the circumferential direction of the drum and has a larger friction coefficient than the first road surface portion; the length of the second road surface portion in the circumferential direction of the drum is larger than the length of the first road surface portion in the circumferential direction of the drum; A measuring device for a tire.

7. A measuring device for measuring a physical quantity acting on the tread surface of a tire during running, comprising: a rotatable drum having a running road surface for running the tire; at least one measuring instrument for measuring a physical quantity acting on the tread surface of the tire, The running road surface includes a first road surface portion to which the measuring instrument is attached, and a second road surface portion that is arranged at a position different from the first road surface portion in the drum circumferential direction and has a friction coefficient larger than that of the first road surface portion. The running road surface further includes a third road surface portion having a friction coefficient smaller than that of the second road surface portion. When the drum is rotated in a first direction, the second road surface portion, the third road surface portion, and the first road surface portion are arranged so as to appear in this order. The first road surface portion and the third road surface portion are formed from smooth surfaces having the same friction coefficient. Measuring device for a tire.

8. A measuring device for measuring a physical quantity acting on the tread surface of a tire during running, A rotatable drum having a running road surface for running the tire, And at least one measuring instrument for measuring a physical quantity acting on the tread surface of the tire. The running road surface includes a first road surface portion to which the measuring instrument is attached, and a second road surface portion that is arranged at a position different from the first road surface portion in the drum circumferential direction and has a friction coefficient larger than that of the first road surface portion. The running road surface further includes a third road surface portion having a friction coefficient smaller than that of the second road surface portion. When the drum is rotated in a first direction, the second road surface portion, the third road surface portion, and the first road surface portion are arranged so as to appear in this order. The length of the third road surface portion in the drum circumferential direction is 50% or more of the circumference of the tire. Measuring device for a tire.

9. A measuring method for measuring a physical quantity acting on the tread surface of a tire during running, Including a running step of running the tire on the running road surface of a rotatable drum, The running step includes a first running step of running the tire on a portion of the running road surface having a relatively large friction coefficient to promote heat generation, After the first running step, a second running step of measuring the physical quantity while running the tire on a portion of the running road surface having a relatively small friction coefficient. Measuring method for a tire.

10. The measuring method for a tire according to claim 9, wherein the first running step heats the surface temperature of the tread surface of the tire to a predetermined temperature.

11. The measuring method for a tire according to claim 10, wherein the predetermined temperature is a temperature at which the rise in the surface temperature is 2°C or less per minute.

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