JP2023025553A - Tire measuring device and tire measuring method - Google Patents

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

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

Patent Literature 1 listed below describes a test apparatus used to measure the stress on the contact surface of a tire. This testing apparatus comprises a drum capable of driving the tire in rotation. Also, a tire stress measuring device is provided on at least one location on the road surface of the drum. This device can measure the tread stress by running the tire on the road surface of the drum.

JP 2017-090234 A

For example, motor sports tires and tires whose tread rubber is highly temperature dependent cannot exhibit their inherent performance (particularly, grip) unless the temperature of the tread rubber rises to a certain level. Therefore, when this type of tire is run on a conventional test apparatus, the tire slips on the drum, and there is a problem that the physical quantity acting on the tread surface of the running tire cannot be accurately measured.

The present disclosure has been devised in view of the actual situation as described above, and aims to provide a tire measuring device and a tire measuring method capable of accurately measuring physical quantities acting on the tread surface of a running tire. Its main purpose.

The present disclosure is a measuring device for measuring physical quantities acting on the tread of a running tire, comprising a rotatable drum having a running surface for running the tire, and a rotatable drum acting on the tread of the tire. and at least one measuring device for measuring a physical quantity, wherein the traveling road surface is arranged at a different position in the circumferential direction of the drum from the first road surface portion to which the measuring device is attached, and and a second road surface portion having a coefficient of friction greater than that of the first road surface portion.

The tire measuring device and tire measuring method of the present disclosure can accurately measure physical quantities acting on the tread surface of a running tire by adopting the above configuration.

1 is a side view conceptually showing one embodiment of a measuring device of the present disclosure; FIG. FIG. 2 is a vertical cross-sectional view of a road surface; 1 is a perspective view of a road surface; FIG. It is a flow chart which shows a measuring method.

An embodiment of the present disclosure will be described below with reference to the drawings.
FIG. 1 is a side view of a measuring device (hereinafter sometimes simply referred to as “device”) 1 of this embodiment. The device 1 of this embodiment is for measuring a physical quantity F acting on a tread Ta of a tire T during running. The physical quantity F measured by the device 1 of the present embodiment includes, for example, shear stress in the axial direction of the tire, shear stress in the circumferential direction of the tire, normal stress in the radial direction of the tire, and the like. Note that the physical quantity F is not limited to these stresses.

In this specification, in the case of pneumatic retirement, the tire T is mounted on a regular rim (not shown), filled with regular internal pressure, and grounded on a plane with a camber angle of 0 degrees under a regular load. It is the area that contacts the plane when it is pressed. The "regular rim" is a rim defined for each tire in a standard system including standards on which tires are based, for example, JATMA is a standard rim, TRA is a "Design Rim", or ETRTO. means "Measuring Rim". The above-mentioned "regular internal pressure" is the air pressure specified for each tire by the above-mentioned standard, and for JATMA it is the maximum air pressure, for TRA it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", ETRTO means "INFLATION PRESSURE". The "regular load" is the load defined for each tire by the standard, and is the maximum load capacity for JATMA, and the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA. If it is ETRTO, it is "LOAD CAPACITY".

A tire T whose physical quantity F is measured is preferably a motor sports tire whose tread rubber is highly temperature dependent, for example. However, the tire T is not limited to this, and various pneumatic tires such as tires for heavy loads, tires for passenger cars and tires for motorcycles, airless tires having a structure different from pneumatic tires, etc. are adopted. be done.

As shown in FIG. 1, the device 1 of this embodiment includes a drum 2 for running a tire T and a measuring device 3 for measuring a physical quantity F. As shown in FIG. The apparatus 1 also includes a temperature measuring instrument 4 for measuring the temperature of the tire T, a drum support 5 that rotatably supports the drum 2, and a tire support 6 that supports the tire T. As shown in FIG.

The drum 2 of this embodiment includes an annular drum main body 2A having an inner peripheral surface 2i extending in the drum peripheral direction, a first side surface portion 2B arranged on one side of the drum main body 2A in the drum axial direction, and a drum It includes a second side surface portion 2C arranged on the other side of the main body 2A in the drum axial direction. The first side portion 2B is connected to the drum support 5, for example. 2 C of 2nd side parts are provided with the opening O for putting in and out the tire T in this embodiment.

A running road surface 10 on which the tires 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 2 i of the drum 2 . However, the drum 2 of the present disclosure is not limited to the inside drum type, and may be, for example, an outside drum type in which a running road surface is formed on the outer peripheral surface 2e of the drum 2 (not shown).

The drum support 5 supports the drum 2 so as to be rotatable around a horizontal axis j2. The drum support 5 of this embodiment includes a support shaft 5A, one end of which is fixed to the first side surface 2B of the drum 2, and a drive member 5B that drives the support shaft 5A to rotate. Such a drum support 5 has a well-known structure.

The tire support 6 includes a tire support shaft 6A that rotatably supports the tire T, and a tire moving device 6B that moves the tire support shaft 6A. The tire support shaft 6A includes a driving tool such as a motor (not shown) for driving the tire T to rotate. The tire moving tool 6B moves the tire T in the drum axial direction and the drum radial direction. The tire mover 6B can bring the tread Ta of the tire T into contact with the road surface 10 with a predetermined load. The tire support 6 may include, for example, an axis angle adjuster (not shown) that changes the axial direction of the supported tire T by an arbitrary angle with respect to the axial direction of the drum. Thereby, it becomes possible to give the tire T an arbitrary camber angle and slip angle. Such a tire support 6 has a well-known structure. Note that the tire support 6 may have a known structure in which the tire T is rotated following the rotation of the drum 2 .

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

FIG. 2 is a longitudinal sectional view of the road surface 10. As shown in FIG. FIG. 3 is a partial perspective view of the road surface 10. As shown in FIG. As shown in FIGS. 2 and 3, the traveling road surface 10 is arranged at different positions in the circumferential direction of the drum than the first road surface portion 11 to which the measuring device 3 is attached. and a second road surface portion 12 having a coefficient of friction 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 and raises the temperature. Therefore, the device 1 of the present disclosure can accurately measure the physical quantity F acting on the tread Ta.

Said coefficient of friction is herein obtained as follows. First, the tire T is unrotatably restrained by the tire support 6 . Next, the tread Ta of the restrained tire T is pressed against the 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 a value (Fx/Fz) obtained by dividing the longitudinal force Fx generated in the tire T at this time by the load Fz.

The first road surface portion 11 of the present embodiment includes a base surface 11A that contacts the tread Ta of the running tire T, and a recessed portion 11B that is recessed outward from the base surface 11A in the radial direction of the drum. A measuring instrument 3 is attached to the concave portion 11B of the present embodiment so that the physical quantity F can be measured.

In this embodiment, the measuring device 3 employs a three-component force sensor that is a well-known load cell. In the case of the 3-component force sensor, its detection portion is arranged so as to be in contact with the tread Ta of the tire T. As shown in FIG.

The measuring instrument 3 is connected to, for example, a processing tool (not shown) for processing measurement results. As the processing tool, for example, a well-known microcomputer equipped with a CPU (Central Processing Unit), memory, etc. is preferably used.

For example, it is desirable that a plurality of measuring instruments 3 be attached to the first road surface portion 11 . It is desirable that the plurality of measuring instruments 3 be arranged, for example, in the axial direction of the drum and in the circumferential direction of the drum. This makes it possible to measure accurate shear stress distribution and normal stress distribution. In this case, the first road surface portion 11 is provided with a plurality of recesses 11B (not shown).

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

The second road surface portion 12 is formed, for example, as an uneven road with a large coefficient of friction. Such a second road surface portion 12 further deforms the tire T and promotes temperature rise. Moreover, such a second road surface portion 12 causes the tire T to generate heat to soften the tread portion. This makes it difficult for the base surface 11A and the third road surface portion 13, which will be described later, to vibrate, for example, so-called stick-slip vibration caused by repeated sticking and slipping of the tire T. An asphalt road is desirable as such an uneven road. The asphalt road imparts a large frictional force to the tire T and deforms it due to irregularities including voids. The asphalt road is preferably made of a material conforming to, for example, the grain size curve of the ISO road surface standard (see the allowable range of grain size curve of asphalt mixture described in ISO 10844 Annex C design guidelines).

In order to effectively exhibit the above effects, it is desirable that the texture depth (TD) of the asphalt road is 1.0 mm or more. Also, it is desirable that the slip resistance value of the asphalt road is 50 BPN or more. In order to suppress damage to the tread Ta of the tire T, it is desirable that the texture depth (TD) is 1.5 mm or less. Also, the slip resistance value is desirably 90 BPN or less. Texture depth (TD) is determined in a sandbatch test. The Sand Batch Test is the average depth of the sand layer obtained by spreading a known volume of sand in a circle on the pavement and dividing this volume by the area of the spread sand. The slip resistance value is a value measured using a slip resistance measuring device (eg, SKID-FRICTION TR300 Model B manufactured by MASTRAD).

It is desirable that the length L2 of the second road surface portion 12 in the drum circumferential direction is greater 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 .

Further, the traveling road surface 10 further includes a third road surface portion 13 having a smaller coefficient of friction than the second road surface portion 12 . Then, 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, the second road surface portion 12, the third road surface portion 13, and the It is desirable that the first road surface portions 11 are arranged so as to appear in this order. Such a third road surface portion 13 can suppress (reduce) the deformation of the ground contact state (ground contact shape) in the transient state that occurs at the moment when the second road surface portion 12 is switched to the third road surface portion 13 . As a result, the tire T, whose contact deformation is suppressed by the third road surface portion 13, continues to run on the first road surface portion 11, so that the physical quantity F is accurately measured.

The length L3 of the third road surface portion 13 in the circumferential direction of the drum is desirably 50% to 100% of the circumferential length of the tire T in order to effectively exhibit the above-described action.

In this embodiment, the third road surface portion 13 and the first road surface portion 11 are formed of smooth surfaces having the same coefficient of friction. More specifically, the base surfaces 11A of the third road surface portion 13 and the first road surface portion 11 are formed of smooth surfaces having the same coefficient of friction. As a result, the deformation in the transient state suppressed by the third road surface portion 13 is also continuously suppressed by the first road surface portion 11, so that the contact state is stabilized, so that the physical quantity F can be measured more accurately. The "smooth surface" used herein means a surface having a slip resistance value of less than 50 BPN.

The third road surface portion 13 is made of, for example, the same material as the base surface 11A. As a result, the above effects are effectively exhibited. In this case, the boundary between the base surface 11A and the third road surface portion 13 may become unclear. When it becomes unclear as described above, the boundary is determined by a measuring instrument that comes into contact with the tire T earliest after the drum 2 is rotated in the first direction N and the tire T and the second road surface portion 12 come into contact with each other. 3 to the front in the first direction N in the circumferential direction of the drum at a distance of 100 mm.

As shown in FIG. 1, the temperature measuring instrument 4 has a function of measuring the surface temperature of the tire T, for example. The temperature measuring instrument 4 measures the surface temperature of the tread Ta of the tire T in this embodiment. The temperature measuring instrument 4 is desirably of a non-contact type such as, for example, Sensatec TIR series (manufactured by Sensatec).

Next, a measuring method for measuring the physical quantity F using this device 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 process, 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 traveling road surface 10 of the drum 2 and the tread 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 Ta of the tire T. As shown in FIG. In the running process, the surface temperature of the tread Ta of the tire T is measured by the temperature measuring device 4 .

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

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

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 surface temperature rises by 2° C. or less per minute. Such a temperature is, for example, the temperature of the tire T during circuit running, and is useful for measuring the physical quantity F with high accuracy. In the first step S1, in order to heat the tire T up to a predetermined temperature (T1° C.), the tire T is caused to travel a plurality of times on the road surface 10 including the second road surface portion 12 . The predetermined temperature (T1°C) is, for example, 30-50°C.

In the second step S<b>2 , the physical quantity F of the tire T is measured by the measuring instrument 3 arranged on the first road surface portion 11 in this embodiment. The tire T runs from the second road surface portion 12 to the third road surface portion 13 in this embodiment. As a result, the third road surface portion 13 suppresses the deformation of the contact state that occurs at the boundary between the second road surface portion 12 and 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 device 3 of the first road surface portion 11 can measure the physical quantity F of the tire T in a state where the deformation of the contact state is suppressed on the third road surface portion 13 . Therefore, in the measuring method of the present disclosure, the physical quantity F can be measured with high accuracy.

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, the shear stress in the axial direction of the tire, the shear stress in the circumferential direction of the tire, and the vertical stress in the tire radial direction are obtained. Various tire performances such as performance and snow performance can be evaluated.

Although the preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the illustrated embodiments, and can be modified in various ways.

[Appendix]
The present disclosure includes the following aspects.

[Present Disclosure 1]
A measuring device for measuring a physical quantity acting on the tread surface of a running tire,
a rotatable drum having a running surface for running the tire;
at least one measuring instrument for measuring a physical quantity acting on the tread of the tire;
The running road surface is arranged at different positions in the circumferential direction of the drum from the first road surface portion to which the measuring instrument is attached, and a second road surface portion having a larger coefficient of friction than the first road surface portion. including a road surface,
Tire measuring device.
[Disclosure 2]
The tire measuring device according to the present disclosure 1, wherein the second road surface portion is an uneven road.
[Disclosure 3]
The tire measuring device according to the present disclosure 1 or 2, wherein the second road surface portion is an asphalt road.
[Disclosure 4]
The tire measuring device according to the present disclosure 3, wherein the texture depth of the asphalt road is 1.0 mm or more.
[Disclosure 5]
5. The tire measuring device according to 3 or 4 of the present disclosure, wherein the slip resistance value of the asphalt road is 50 BPN or more.
[Disclosure 6]
6. The tire measuring device according to any one of the present disclosures 1 to 5, wherein the length of the second road surface portion in the circumferential direction of the drum is greater than the length of the first road surface portion in the circumferential direction of the drum.
[Present 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,
7. Any one of present disclosures 1 to 6, wherein 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 when the drum is rotated in a first direction. The tire measuring device according to any one of the above.
[Disclosure 8]
The tire measuring device according to the present 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 tire measuring device according to the present disclosure 7 or 8, wherein the length of the third road surface portion in the drum circumferential direction 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 running tire,
including a running step of running the tire on a running 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;
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 where the coefficient of friction is relatively small,
How to measure tires.
[Present Disclosure 11]
11. The tire measurement method according to the present disclosure 10, wherein in the first running step, the surface temperature of the tread surface of the tire heats up to a predetermined temperature.
[Present Disclosure 12]
The tire measurement method according to the present disclosure 11, wherein the predetermined temperature is a temperature at which the surface temperature rises by 2°C or less per minute.

REFERENCE SIGNS LIST 1 measuring device 2 drum 3 measuring instrument 10 traveling road surface 11 first road surface portion 12 second road surface portion T tire Ta tread

Claims (12)

A measuring device for measuring a physical quantity acting on the tread surface of a running tire,
a rotatable drum having a running surface for running the tire;
at least one measuring instrument for measuring a physical quantity acting on the tread of the tire;
The running road surface is arranged at different positions in the circumferential direction of the drum from the first road surface portion to which the measuring instrument is attached, and a second road surface portion having a larger coefficient of friction than the first road surface portion. including a road surface,
Tire measuring device. The tire measuring device according to claim 1, wherein the second road surface portion is an uneven road. The tire measuring device according to claim 1 or 2, wherein the second road surface portion is an asphalt road. The tire measuring device according to claim 3, wherein the texture depth of the asphalt road is 1.0 mm or more. The tire measuring device according to claim 3 or 4, wherein the slip resistance value of the asphalt road is 50 BPN or more. The tire measuring device according to any one of claims 1 to 5, wherein the length of the second road surface portion in the circumferential direction of the drum is greater than the length of the first road surface portion in the circumferential direction of the drum. The running road surface further includes a third road surface portion having a smaller coefficient of friction than the second road surface portion,
7. Any one of claims 1 to 6, wherein 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 when the drum is rotated in the first direction. 1. A tire measuring device according to claim 1. The tire measuring device according to claim 7, wherein the first road surface portion and the third road surface portion are formed of smooth surfaces having the same coefficient of friction. The tire measuring device according to claim 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. A measuring method for measuring a physical quantity acting on the tread surface of a running tire,
including a running step of running the tire on a running 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;
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 where the coefficient of friction is relatively small,
How to measure tires. 11. The tire measuring method according to claim 10, wherein in the first running step, the surface temperature of the tread surface of the tire is heated to a predetermined temperature. The tire measuring method according to claim 11, wherein the predetermined temperature is a temperature at which the surface temperature rises by 2°C or less per minute.

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