JP6794774B2 - Tire ground contact measuring device - Google Patents

Description

The present invention relates to a device for measuring the ground contact state of a tire, and more particularly to a tire ground contact state measuring device capable of streamlining the measurement work.

For example, Patent Document 1 below proposes a device capable of measuring the shape of a contact patch of a tire, the magnitude of a contact pressure, and the like. The tire ground contact state measuring device of Patent Document 1 has a substrate having a surface for grounding the tire, a pressure sensor sheet arranged on the surface of the substrate, and a protective sheet covering the surface of the pressure sensor sheet. ing. Further, in order to reduce these frictions, a liquid lubricant such as low-viscosity oil or soapy water is injected between the pressure sensor sheet and the protective sheet of Patent Document 1.

However, a liquid lubricant such as Patent Document 1 tends to have a bias or the like even if the ground contact state of the tire is measured several times, and the frictional force between the pressure sensor sheet and the protective sheet tends to increase at an early stage. .. For this reason, it was necessary to frequently inject a lubricant during the measurement work. Further, the device of Patent Document 1 has a problem that the slipperiness of the pressure sensor sheet and the protective sheet tends to vary depending on each position due to variations in the injection amount of the lubricant and the like, and thus the measurement results tend to vary.

Japanese Unexamined Patent Publication No. 2013-217726

The present invention has been devised in view of the above circumstances, and is based on the provision of an auxiliary sheet for reducing friction between the pressure sensor sheet and the protective sheet, and is capable of streamlining the measurement work. Its main purpose is to provide a state measuring device.

The present invention is a device for measuring the ground contact state of a tire, a substrate having a surface for grounding the tire, and a pressure sensor sheet arranged on the surface of the substrate and having a plurality of pressure measurement points. And a protective sheet covering the surface of the pressure sensor sheet, and an auxiliary sheet for reducing friction is arranged between the pressure sensor sheet and the protective sheet. It is a device.

In the tire ground contact state measuring device of the present invention, it is desirable that the auxiliary sheet has a constant thickness.

In the tire ground contact state measuring device of the present invention, it is desirable that the auxiliary sheet contains a fluororesin.

In the tire ground contact state measuring device of the present invention, it is desirable that the coefficient of friction between the auxiliary sheet and the pressure sensor sheet is 0.1 or less.

In the tire ground contact state measuring device of the present invention, the thickness of the auxiliary sheet is 0.05 to 0.40 mm, and the total thickness of the auxiliary sheet and the protective sheet is 0.10 to 0.80 mm. It is desirable to have it.

In the tire ground contact state measuring device of the present invention, it is desirable that the flexural modulus of the auxiliary sheet is smaller than the flexural modulus of the protective sheet.

In the tire ground contact state measuring device of the present invention, it is desirable that the flexural modulus of the auxiliary sheet and the flexural modulus of the protective sheet are 0.40 to 0.65 GPa, respectively.

In the tire ground contact state measuring device of the present invention, the protective sheet has a first surface in contact with the auxiliary sheet and a second surface in contact with the tire on the opposite side of the first surface. It is desirable that the surface roughness of the two surfaces is larger than the surface roughness of the first surface.

The tire ground contact state measuring device of the present invention is for applying tension in the direction perpendicular to the first direction to the tire holder for moving the tire relative to the substrate in the first direction and the protective sheet. It is desirable to further include a tensioning device.

The tire ground contact state measuring device of the present invention covers a substrate having a surface for grounding a tire, a pressure sensor sheet arranged on the surface of the substrate and having a plurality of pressure measurement points, and the surface of the pressure sensor sheet. An auxiliary sheet for reducing friction is arranged between the pressure sensor sheet and the protective sheet, including the protective sheet.

Such an auxiliary sheet does not need to be injected as frequently as a liquid lubricant, and can maintain a low friction state between the pressure sensor sheet and the protective sheet for a long period of time. Therefore, according to the tire ground contact state measuring device of the present invention, the tire ground contact state measurement work can be made more efficient. In addition, the auxiliary sheet can maintain the slipperiness of the pressure sensor sheet and the protective sheet at a constant level, and thus can reduce the variation in the measurement results.

It is a side view of the ground contact state measuring device of the tire of this embodiment. FIG. 1 is a cross-sectional view taken along the line AA of FIG. (A) is a plan view of the substrate of FIG. 1, and (b) is a sectional view taken along line BB of (a). (A) is a partial perspective view of the pressure sensor sheet, and (b) is a sectional view taken along line CC of (a). (A) is a graph showing the correlation between the first measurement integrated ground pressure in the conventional example and the first measurement integrated ground pressure in the comparative example, and (b) is the first measurement integrated ground pressure in the conventional example. It is a graph which shows the correlation between the pressure and the integrated ground pressure of the 20th measurement in the comparative example. (A) is a graph showing the correlation between the first measurement integrated ground pressure in the conventional example and the first measurement integrated ground pressure in the embodiment, and (b) is the first measurement integrated ground pressure in the conventional example. It is a graph which shows the correlation between the pressure and the integrated ground pressure of the 20th measurement in an Example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a side view of the tire ground contact state measuring device (hereinafter, may be simply referred to as “measuring device”) 1 of the present embodiment. As shown in FIG. 1, the measuring device 1 can measure the shape of the ground contact surface of the tire T, the magnitude of the ground pressure, and the like by running the tire T on the substrate 3. The measuring device 1 of the present embodiment moves, for example, the gantry 2, the substrate 3 provided on the gantry 2, and the tire T relative to the substrate 3 in the first direction X (the traveling direction of the tire). It is equipped with a tire holder 4 for making the tire holder.

FIG. 2 shows a sectional view taken along line AA of the measuring device 1 of FIG. As shown in FIG. 2, the gantry 2 has, for example, a moving device 5 for moving the base 3 and a support frame 7 for supporting the tire holder 4.

The moving device 5 is provided, for example, on the upper part of the main body frame 6 of the gantry 2 fixed to the floor surface. The moving device 5 includes, for example, a guide rail 10 and a substrate moving means 11.

A pair of guide rails 10 are provided on both sides of the gantry 2, for example. Each guide rail 10 has, for example, a convex portion 18 that is convex upward, and extends linearly along the first direction. The substrate 3 is placed on the pair of guide rails 10, 10.

The substrate moving means 11 can, for example, move the substrate 3 on the guide rail 10 in the first direction. In the present embodiment, as the substrate moving means 11, a feed screw mechanism including a screw rod 12a and a ball nut 12b screwed into the screw rod 12a is adopted. However, the substrate moving means 11 is not limited to such an embodiment, and various configurations such as a winding conduction mechanism can be adopted.

The support frame 7 is provided on the side of the main body frame 6, for example, and supports the tire holder 4. The support frame 7 has, for example, a wall portion 14 extending upward from the end portion.

The tire holder 4 of the present embodiment can hold the tire T so that, for example, the rotation axis of the tire T is in the second direction perpendicular to the first direction. The tire holder 4 has, for example, a main body portion 16 supported by the wall portion 14 of the support frame 7, and a swing arm 17 extending from the main body portion 16. A rim for mounting the tire T is rotatably pivotally supported at the tip of the swing arm 17.

In the present embodiment, the main body portion 16 can be moved up and down along the wall portion 14 by, for example, the first drive machine 21. With the tire T mounted on the substrate 3, the main body 16 is moved downward by the first drive machine 21, so that the tire T is urged downward. That is, in the present embodiment, the tire T can be pressed against the surface of the substrate 3.

As a more desirable embodiment, for example, a second drive machine 22 and a third drive machine 23 are hung between the swing arm 17 and the main body portion 16. The second drive 22 can, for example, adjust the angle between the main body 16 and the swing arm 17, and can impart a camber angle to the tire T. The third drive 23 can, for example, adjust the angle of the tire rotation axis with respect to the first direction, and can impart a slip angle to the tire T. Drive cylinders are used as the second drive 22 and the third drive 23, respectively, but the present invention is not limited to this mode. By providing such a second drive machine 22 and a third drive machine 23, it is possible to measure the ground contact state of the tire under various conditions.

For example, a pair of engaging frames 20 are provided in the lower portion of the substrate 3. Engagement frames 20 are provided on both sides of the substrate 3 in the second direction. The engaging frame 20 has, for example, a groove-shaped concave portion 19 and is slidably fitted in the convex portion 18 of the guide rail 10. As a result, the substrate 3 is movably supported in the first direction. In the present embodiment, the tire T moves relative to the base 3 by moving the base 3 in the first direction. However, the present invention is not limited to such an embodiment, and the substrate 3 may be fixed and the tire T may roll on the substrate 3.

FIG. 3A shows a plan view of the substrate 3. In FIG. 3A, the tire holder 4 is omitted. FIG. 3B shows a sectional view taken along line BB of FIG. 3A. As shown in FIGS. 3A and 3B, the substrate 3 has a surface for grounding the tire T. The surface of the substrate 3 is, for example, a vertically long rectangular shape in the first direction. A pressure sensor sheet 24 and a protective sheet 25 covering the surface of the pressure sensor sheet 24 are arranged on the surface of the substrate 3.

A plurality of pressure measurement points are arranged vertically and horizontally on the pressure sensor sheet 24. By pressing the tread surface of the tire T against the pressure sensor sheet 24, the pressing load is measured at each pressure measuring point in the ground contact surface. By processing this measurement data, for example, by a computer, the shape of the ground contact surface of the tire T, the distribution of the ground contact pressure in the ground contact surface, and the like can be obtained. These results can be displayed as an image by, for example, a display device (not shown).

FIG. 4A shows an enlarged perspective view of a part of the pressure sensor sheet 24 of the present embodiment. FIG. 4B shows a sectional view taken along line CC of FIG. 4A. As shown in FIGS. 4A and 4B, the pressure sensor sheet 24 has a plurality of first linear electrodes 27a and a plurality of second linear electrodes between the two film-like sheets 26, 26. 27b is arranged vertically and horizontally at a short pitch. The first linear electrodes 27a and the second linear electrodes 27b intersect each other in a plan view.

As shown in FIG. 4B, a resin 28 whose electrical resistance decreases according to the amount of deformation when compressed is filled between the first linear electrode 27a and the second linear electrode 27b. (The resin 28 is omitted in FIG. 3A). The electrical resistance of the resin 28 decreases as the force pressing the outer surface of the sheet 24 increases. Therefore, the electric resistance between the linear electrodes 27a and 27b is reduced by pressing the sheet 24 at the intersection 31 of the first linear electrode 27a and the second linear electrode 27b in a plan view. Therefore, by measuring the electric resistance, the force acting on the resin at the intersection 31 can be measured. Therefore, the intersection 31 is a pressure measurement point 29, and the electrical resistance at each intersection 31 formed by the plurality of first linear electrodes 27a and the plurality of second linear electrodes 27b is measured. , The contact patch shape and the contact pressure distribution of the tire T can be obtained.

As shown in FIGS. 3A and 3B, the protective sheet 25 covers the surface of the pressure sensor sheet 24 and protects the pressure sensor sheet 24 from the frictional force of the tire. A more detailed configuration of the protective sheet 25 will be described later.

In the present invention, an auxiliary sheet 30 for reducing friction is arranged between the pressure sensor sheet 24 and the protective sheet 25. The auxiliary sheet 30 does not need to be injected as frequently as a liquid lubricant, and can maintain a low friction state between the pressure sensor sheet 24 and the protective sheet 25 for a long period of time. Therefore, according to the measuring device 1 of the present invention, it is possible to improve the efficiency of the measurement work of the ground contact state of the tire T. Further, the auxiliary sheet 30 can maintain the slipperiness of the pressure sensor sheet 24 and the protective sheet 25 to be constant, and thus can reduce the variation in the measurement results.

In order to further exert the above-mentioned effects, preferable configurations of the protective sheet 25 and the auxiliary sheet 30 will be described.

It is desirable that the protective sheet 25 covers the entire surface of the pressure sensor sheet 24, for example. As a more desirable embodiment, the length L1 of the protective sheet 25 in the first direction (vertical direction in FIG. 3A) is 2.0 to 3.0 times the length L2 of the pressure sensor sheet 24 in the first direction. is there. The width W1 of the protective sheet 25 in the second direction (left-right direction in FIGS. 3A and 3B) is 1.5 to 2.0 times the width W2 of the pressure sensor sheet 24 in the second direction. The protective sheet 25 having such a sufficient area can reliably protect the pressure sensor sheet 24.

The protective sheet 25 is preferably tough and flexible. From this point of view, the material of the protective sheet 25 is preferably a synthetic resin such as polycarbonate. Further, in order to suppress a decrease in the sensitivity of the pressure sensor sheet 24, it is desirable that the protective sheet 25 has a constant thickness. The thickness t1 (not shown) of the protective sheet 25 is preferably, for example, 0.05 to 0.50 mm.

The flexural modulus of the protective sheet 25 is preferably 0.40 GPa or more, more preferably 0.50 GPa or more, preferably 0.65 GPa or less, and more preferably 0.55 GPa or less. Such a protective sheet 25 can exhibit excellent durability while maintaining the sensitivity of the pressure sensor sheet 24. In the present specification, the “flexural modulus” means a three-point flexural modulus measured in accordance with JIS K 6911.

The protective sheet 25 has a first surface 33 that contacts the auxiliary sheet 30 and a second surface 34 that contacts the tire T on the opposite side of the first surface 33. It is desirable that the surface roughness Ra2 of the second surface 34 is larger than the surface roughness Ra1 of the first surface 33. Such a protective sheet 25 can reduce friction with the auxiliary sheet 30 while suppressing slippage of the tire T on the second surface 34, and the durability of the protective sheet 25 and the sensitivity of the pressure sensor sheet 24. Can be compatible with. In addition, in this specification, "surface roughness" means the arithmetic mean roughness defined in JISB0601-2001.

The auxiliary sheet 30 preferably has a smaller coefficient of friction in order to sufficiently suppress the friction between the pressure sensor sheet 24 and the protective sheet 25. On the other hand, it is desirable that the auxiliary sheet 30 has high durability in order to reduce the frequency of its replacement. From such a viewpoint, it is desirable that the material of the auxiliary sheet 30 is composed of, for example, a fluororesin, and more specifically, it is desirable that the material of the auxiliary sheet 30 is composed of PTFE.

The flexural modulus of the auxiliary sheet 30 is preferably 0.40 to 0.65 GPa, for example. The flexural modulus of the auxiliary sheet 30 of the present embodiment is smaller than, for example, the flexural modulus of the protective sheet 25. Specifically, it is desirable that the flexural modulus of the auxiliary sheet 30 is, for example, 0.85 to 0.95 times the flexural modulus of the protective sheet 25. Such an auxiliary sheet 30 is useful for suppressing a decrease in sensitivity of the pressure sensor sheet 24.

It is desirable that the auxiliary sheet 30 has a constant thickness. The thickness t2 (not shown) of the auxiliary sheet 30 is preferably 0.05 mm or more, more preferably 0.15 mm or more, preferably 0.40 mm or less, and more preferably 0.30 mm or less. The total thickness of the auxiliary sheet 30 and the protective sheet 25 is 0.10 to 0.80 mm. As a result, the pressure sensor sheet 24 can be effectively protected while maintaining the sensitivity of the pressure sensor sheet 24.

As a preferred embodiment, the measuring device 1 of the present embodiment further includes a tension applying device 35 for applying tension to the protective sheet 25. The tension applying device 35 of the present embodiment includes, for example, a pair of winding rolls 36, 36. The take-up roll 36 has a rotation axis extending linearly along the first direction, and is arranged on both sides of the substrate 3. Each winding roll 36 can appropriately wind the protective sheet 25, and can apply tension to the protective sheet 25 in the second direction (direction perpendicular to the first direction). In such a tension applying device 35, a pair of take-up rolls 36, 36 can apply sufficient tension to the entire protective sheet 25 from both sides in the second direction, and eventually wrinkles of the protective sheet 25 are generated. It can be effectively suppressed.

An experiment was conducted to investigate the correlation between the measurement result of the tire contact pressure when the tire contact state measuring device of the present embodiment was used and the measurement result of the tire contact pressure when the conventional device was used.

As a conventional example, a protective sheet having a thickness of 0.09 mm and a bending rigidity of 0.50 GPa is provided on the pressure sensor sheet, and a lubricant or an auxiliary sheet is provided between the pressure sensor sheet and the protective sheet. A measuring device not provided was used, and the integrated contact pressure of a plurality of (N = 121) plain tires was measured under the following conditions. The integrated contact pressure is the integrated contact pressure of the portion where the contact pressure is in the range of 75 mm on each side in the tire axial direction from the contact center line of the tire and the contact pressure is 20 kPa or more. In each plain tire, the integrated contact pressure was measured 20 times, and the first and 20th integrated contact pressures were recorded.
Tire size: 195 / 65R15
Internal pressure: 230kPa
Load: 4.00kN
Room temperature: 25 ± 2 ° C

As a comparative example, a measuring device having the same protective sheet as the conventional example on the pressure sensor sheet and having a silicon-based lubricant injected between the pressure sensor sheet and the protective sheet is used. Similarly, the integrated contact pressure of the plurality of plain tires was measured.

As an embodiment, a measuring device in which the same protective sheet as in the conventional example is provided on the pressure sensor sheet and an auxiliary sheet for reducing friction is provided between the pressure sensor sheet and the protective sheet is used. Similar to the example, the contact pressures of the plurality of plain tires were measured. The detailed configuration of the auxiliary sheet is as follows.
Auxiliary sheet thickness: 0.14 mm
Flexural rigidity of auxiliary sheet: 0.45GPa
Auxiliary sheet material: PTFE

The measuring devices of the conventional example, the comparative example, and the embodiment have substantially the same configuration except for the above-described configuration.

FIG. 5A shows a graph showing the correlation between the integrated ground pressure of the first measurement in the conventional example and the integrated ground pressure of the first measurement in the comparative example. The slope of these correlation lines is 0.987. FIG. 5B shows a graph showing the correlation between the integrated ground pressure of the first measurement in the comparative example and the integrated ground pressure of the 20th measurement in the comparative example. The slope of these correlation lines is 0.849.

FIG. 6A shows a graph showing the correlation between the integrated ground pressure of the first measurement in the conventional example and the integrated ground pressure of the first measurement in the embodiment. The slope of these correlation lines is 1.317. FIG. 6B shows a graph showing the correlation between the integrated ground pressure of the first measurement in the embodiment and the integrated ground pressure of the 20th measurement in the embodiment. The slope of these correlation lines is 1.042.
The results of summarizing the correlation coefficients shown in FIGS. 5 and 6 are shown in Table 1.

As shown in Table 1, in the comparative example, in the 20th measurement, the slope of the correlation line with the 1st measurement is as low as 0.849. On the other hand, in the example, the slope of the correlation line is 1.042 at the 20th measurement, and there is almost no difference between the data at the 1st measurement and the 20th measurement. That is, it can be confirmed that the measuring device of the present embodiment can maintain a low friction state between the pressure sensor sheet and the protective sheet for a long period of time, and the variation in the measurement results is small. It was.

Although one embodiment of the tire ground contact state measuring device of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment, but is modified to various embodiments. obtain.

3 Hypokeimenon 24 Pressure sensor sheet 25 Protective sheet 30 Auxiliary sheet

Claims (8)

It is a device for measuring the ground contact condition of tires.
A substrate having a surface for grounding a tire, a pressure sensor sheet arranged on the surface of the substrate and having a plurality of pressure measurement points, and a protective sheet covering the surface of the pressure sensor sheet are included.
Between the protective sheet and the pressure sensor sheet, Ri Contact arranged auxiliary sheet for reducing friction,
The protective sheet has a first surface that comes into contact with the auxiliary sheet and a second surface that comes into contact with the tire on the opposite side of the first surface.
A tire ground contact state measuring device characterized in that the surface roughness of the second surface is larger than the surface roughness of the first surface . The tire ground contact state measuring device according to claim 1, wherein the auxiliary sheet has a constant thickness. The tire ground contact state measuring device according to claim 1 or 2, wherein the auxiliary sheet contains a fluororesin. The tire ground contact state measuring device according to any one of claims 1 to 3, wherein the friction coefficient between the auxiliary sheet and the pressure sensor sheet is 0.1 or less. The thickness of the auxiliary sheet is 0.05 to 0.40 mm.
The tire ground contact state measuring device according to any one of claims 1 to 4, wherein the total thickness of the auxiliary sheet and the protective sheet is 0.10 to 0.80 mm. The tire contact state measuring device according to any one of claims 1 to 5, wherein the flexural modulus of the auxiliary sheet is smaller than the flexural modulus of the protective sheet. The tire ground contact state measuring device according to any one of claims 1 to 6, wherein the flexural modulus of the auxiliary sheet and the flexural modulus of the protective sheet are 0.40 to 0.65 GPa, respectively. A tire holder for moving the tire relative to the substrate in the first direction, and
The tire ground contact state measuring device according to any one of claims 1 to 7, further comprising a tension applying device for applying tension in the direction perpendicular to the first direction to the protective sheet.

Images