JP2013217726A - Apparatus and method for measuring ground contact condition of tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus 1 for measuring the ground contact condition of a tire.SOLUTION: A ground contact condition measuring apparatus 1 includes a ground contact body 3, a press device 4 for pressing a tire T against the ground contact body 3, a pressure sensor sheet 13 arranged on the surface of the ground contact body 3 and having multiple pressure measurement points, a protective film 16 arranged so as to cover the top face of the pressure sensor sheet 13, a tension addition device 17 for applying tension to the protective film 16, and a lubricant injected between the pressure sensor sheet 13 and the protective film 16.

Description

  The present invention. The present invention relates to a ground contact state measuring device and a ground contact state measuring method capable of measuring a contact surface pressure and a contact surface shape of a tire.

  Conventionally, as an apparatus or a method for measuring the contact surface shape of a tire, JP-A-03-146809, JP-A-03-226636, JP-A-2004-294374, JP-A-2003-240681, JP-A-2001-221716 The apparatus and method disclosed in the publication are known. These are all images of a ground contact surface when a load is applied to a tire using a camera. The shape of the ground contact surface of the tire pressed against the transparent ground plate is photographed with a camera from the back side of the ground plate. Therefore, these methods are not sufficient for measuring the contact pressure distribution of a tire when a load is applied.

  JP-A-2005-096595, JP-A-2007-216895, and the like disclose a measurement device for a tire ground contact state using a load cell. However, since the measurement is performed by the load cell, the measurement result of the contact shape and the contact pressure distribution is not precise. In addition, the configuration of the apparatus becomes complicated.

  Therefore, a pressure sensor sheet for measuring the range of pressing load may be used. In this pressure sensor sheet, linear electrodes are arranged vertically and horizontally at a short pitch between two film-like sheets. The intersection of the vertical and horizontal linear electrodes is a force detection unit (sensor cell). The electric resistance of the sensor cell at no load is infinite at normal times, but decreases according to the applied force. By measuring the electric resistance value of each sensor cell, the ground plane shape and the ground plane pressure distribution are obtained.

  However, the pressure sensor sheet has a sufficient strength against a load perpendicular to the surface, which is simply pressed by a tire, but is relatively weak against a tensile force. When tire braking, driving start, turning, slip angle or camber angle is set, a tensile force is applied to the pressure sensor sheet by friction between the tire and the pressure sensor sheet. This pulling force may damage the pressure sensor sheet.

Japanese Unexamined Patent Publication No. 03-146809 Japanese Patent Laid-Open No. 03-226636 JP 2004-294374 A JP 2003-206881 A JP 2001-221716 A JP 2005-096595 A JP 2007-216895 A

  The present invention has been made in view of the above-described present situation, and an object thereof is to provide a tire ground contact state measuring device and a ground contact state measuring method in which the load of frictional force from the tire to the sensor is greatly suppressed. Yes.

The tire ground contact state measuring device according to the present invention is:
A grounding body,
A pressing device for pressing the tire against the grounding body;
A pressure sensor sheet having a large number of pressure measurement points disposed on the surface of the grounding body;
A protective film arranged to cover the upper surface of the pressure sensor sheet;
A tension applying device for applying tension to the protective film.

  Preferably, a lubricant is injected between the pressure sensor sheet and the protective film.

  Preferably, the protective film thickness is 0.1 mm or more and 0.5 mm or less.

  Preferably, the tension is applied in a range of 2 kN or more and 10 kN or less with respect to a width of 25 cm of the protective film in a direction perpendicular to the direction of the tension, and the tension is proportional to an increase or decrease in the width of the protective film which is the load range. Increase or decrease.

The tire ground contact state measuring method according to the present invention is:
Arranging a protective film so as to cover the surface of the grounding body on which the pressure sensor sheet is installed;
Applying a tension to the protective film;
Interposing the protective film, pressing the tread surface of the tire against the surface of the grounding body;
Measuring the pressing force from the tire at a number of pressure measurement points of the pressure sensor sheet on which the tire is pressed.

  Preferably, in the step of disposing the protective film, a lubricant is injected between the pressure sensor sheet and the protective film.

  According to the tire ground contact state measuring apparatus or the measurement method according to the present invention, in the measurement of the tire ground contact state, the load of frictional force from the tire to the pressure sensor seat is greatly suppressed, and a more precise measurement result is obtained. sell.

FIG. 1 is a partially cutaway front view showing an embodiment of a tire ground contact state measuring apparatus according to the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 3 is a view taken along the line III-III in FIG. FIG. 4A is a partial cross-sectional perspective view showing an example of a pressure sensor sheet used in the ground state measurement apparatus of FIG. 1, and FIG. 4B is a cross-sectional view taken along line IV-IV in FIG. FIG.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  1 and 2 show a tire ground contact state measuring device (hereinafter also simply referred to as a measuring device) 1. This measuring apparatus 1 includes a gantry 2, a grounding body 3 that can move in the horizontal direction on the gantry 2, and a tread surface of a test tire (hereinafter also simply referred to as a tire) T against the grounding body 3. The pressing device 4 is provided. The planar view shape of the grounding body 3 is a rectangle, but is not particularly limited to a rectangle.

  As shown in FIG. 2, a guide rail 5 is laid on the top of the gantry 2. An engagement frame 6 that engages with the gantry 2 is provided at the lower end of the grounding body 3. The engagement frame 6 can move on the guide rail 5. The gantry 2 is provided with a driving device 7 for moving the grounding body 3 along the guide rail 5. In this embodiment, a feed screw mechanism including a screw rod 7a and a nut 7b screwed to the screw rod 7a is employed as the driving device 7. However, the drive device of the present invention is not particularly limited to the feed screw mechanism. The grounding body 3 moves in the front-rear direction (rolling direction) of the tire T to be pressed. Since the grounding body 3 moves while the tire T is pressed, the tire T is rolled. The rectangular grounding body 3 has a long length along this moving direction. Therefore, the moving direction of the grounding body 3 is referred to as the longitudinal direction of the grounding body 3. The direction perpendicular to the longitudinal direction is referred to as the width direction.

  FIG. 2 shows details of the tire pressing device 4. The pressing device 4 includes a support member 9 that supports the test tire T via a swing arm 8. The support member 9 can be moved up and down with respect to a pressing device main body (hereinafter also simply referred to as a main body) 10 by an elevator 14. Accordingly, the test tire T is pressed against the upper surface of the grounding body 3 and the pressing is released. As for the posture of the tire T supported by the support member 9, the front-rear direction thereof coincides with the moving direction of the grounding body 3. Between the swing arm 8 and the main body 10, a vertical swing drive unit 11 and a horizontal swing drive unit 12 are suspended. The vertical swing drive unit 11 sets a camber angle for the test tire T attached to the swing arm 8. The lateral swing drive machine 12 sets a slip angle for the test tire T. In the present embodiment, drive cylinders are used as the elevator 14, the vertical swing drive 11, and the lateral swing drive 12, respectively, but the present invention is not limited to such a configuration.

  In the present embodiment, the grounding body 3 is configured to move horizontally in the front-rear direction of the tire T, but is not limited to this configuration. The grounding body 3 may be configured to be vertical or inclined from the vertical and movable in the in-plane direction. Further, the grounding body 3 may be fixed so as not to move, and the pressing device 4 may be configured to be movable so as to roll the tire T along the surface of the grounding body 3. Alternatively, the tire T may be rotationally driven and braked by the pressing device 4. In this case, the grounding body 3 may be configured to be selectively movable and immovable.

  As shown in FIGS. 1 to 3, a pressure sensor sheet 13 is installed at the center of the upper surface of the grounding body 3. The pressure sensor sheet 13 is thin and is laminated on the upper surface of the grounding body 3. As the pressure sensor sheet 13, for example, various sensor sheets manufactured by Nitta Corporation can be adopted. The pressure sensor sheet 13 has a large number of force detectors arranged vertically and horizontally on the surface thereof. When the tread surface of the tire T is pressed against the pressure sensor sheet 13, the pressing load is measured at each force detection unit in the ground contact surface. By processing this measurement data by a computer (not shown), the shape of the contact surface of the test tire T, the distribution of the contact surface pressure within the contact surface, and the like are obtained. On a display device (not shown), the ground plane shape and the distribution of the ground plane pressure can be displayed as an image.

  FIG. 4 shows a part of the pressure sensor sheet 13. In the pressure sensor sheet 13, linear electrodes 15a and 15b are arranged vertically and horizontally at a short pitch between two film sheets 15c. The intersection of the longitudinal linear electrode 15a and the lateral linear electrode 15b in plan view is the force detector 13a. The electric resistance of the force detector 13a at no load is infinite at normal times, but decreases according to the applied force. By measuring the electric resistance value of each force detection unit 13a, the shape of the ground plane and the distribution of the ground plane pressure are obtained. As shown in FIG. 3, a large number of electrical connection terminals 13b extend laterally from the electrodes 15a and 15b.

  As shown in FIGS. 1 and 3, a protective film 16 is provided on the upper surface of the grounding body 3 so as to cover the pressure sensor sheet 13. The protective film 16 is not fixed to the upper surface of the grounding body 3 and the upper surface of the pressure sensor sheet 13. In FIG. 1, for easy understanding, the thickness of the protective film 16 is made larger than the actual thickness, and a gap D that is much larger than the actual size is shown between the protective film 16 and the upper surface of the grounding body 3. Although the planar view shape of this protective film 16 is a rectangle, it is not limited to a rectangle in particular. The protective film 16 is for protecting the pressure sensor sheet 13 from frictional force caused by the tire T. The protective film 16 receives the frictional force from the tire T. Only the vertical pressing force from the tire T is applied to the pressure sensor sheet 13.

  When the tire T is braked, driven, turned, camber angle set, and slip angle set, friction force is applied from the tire T to the pressure sensor seat 13. This frictional force becomes a pulling force for the pressure sensor sheet 13. This pulling force needs to be received by another member. Therefore, the protective film 16 is disposed so as to cover the upper surface of the pressure sensor sheet 13. The protective film 16 has a rectangular shape in plan view. The protective film 16 has a lower coefficient of friction than the tread surface of the tire T. It is possible to suppress the frictional force from being applied to the pressure sensor sheet 13 from the tire T through the protective film 16. Although the surface pressure from the tire T is applied to the pressure sensor sheet 13, most of the frictional force is applied to the protective film 16 and is prevented from being applied to the pressure sensor sheet 13. For this purpose, as described above, the protective film 16 is not fixed to the upper surface of the grounding body 3 and the upper surface of the pressure sensor sheet 13.

  A tension is applied to the protective film 16. This is to prevent the protective film 16 from being displaced in the in-plane direction by the frictional force from the tire T. In other words, the frictional force from the tire T prevents the tire T and the protective film 16 from integrally sliding relative to the pressure sensor sheet 13. This is because it is difficult to measure an accurate contact surface shape and an accurate contact surface pressure if the tire T slides on the pressure sensor sheet 13 without rolling. By applying tension to the protective film 16, the tire T and the protective film 16 are less likely to slip, and an accurate contact surface shape, contact pressure distribution, and the like can be measured. In this embodiment, the form with which the tension | tensile_strength with respect to the protective film 16 is added only to the rolling direction (front-back direction) of a tire is illustrated. However, the present invention is not limited to such a configuration.

  FIG. 1 shows a tension applying device 17 for the protective film 16. The tension applying device 17 includes a tension adjusting unit 18 provided at one end of the grounding body 3 in the longitudinal direction (movement direction) and a film fixing unit 19 provided at the other end of the grounding body 3 in the longitudinal direction. Become. The tension applying device 17 is integrated with the grounding body 3. The film fixing portion 19 is shown at the left end of the grounding body 3 in FIG. The film fixing part 19 is for fixing one end part of the protective film 16.

  FIG. 3 shows only the tension adjusting unit 18. The tension adjusting unit 18 includes a film end holding member 20, a support frame 21, a fixing member 22, a tension measuring device 24, and a measuring device fixing member 25. Although the load cell 24 is adopted as the tension measuring device, it is not limited to the load cell. The film end holding member 20 is a rod-like member that holds the other end of the protective film 16. The film end holding member 20 and the measuring instrument fixing member 25 are connected by a load cell 24. The film end holding member 20, the load cell 24, and the measuring device fixing member 25 connected to each other can move only in the longitudinal direction of the grounding body 3. The support frame 21 is a gate-shaped member fixed to one end of the grounding body 3.

  Adjustment bolts 23 are inserted into bolt holes formed in the support frame 21. The adjusting bolt 23 is screwed into a screw hole formed in the measuring instrument fixing member 25. When the adjustment bolt 23 is rotated, the measuring instrument fixing member 25 moves in the longitudinal direction of the grounding body 3. Thereby, the tension applied to the protective film 16 increases and decreases, and the tension is applied to the load cell 24 as well. When the tension of the protective film 16 measured by the load cell 24 reaches a predetermined range, the protective film 16 is fixed to the grounding body 3 by the fixing member 22.

  The fixing member 22 is a rod-like member, and is bolted to the surface of the grounding body 3 so that a gap through which the protective film 16 can be inserted is formed. The gap can be adjusted by a bolt. When fixing the protective film 16, the bolt is tightened and the protective film is clamped between the fixing member 22 and the grounding body 3. The above is an example of the tension adjusting unit 18. Other configurations may be employed as the tension adjusting unit 18. A roll or the like that winds the protective film 16 may be employed.

  The protective film 16 is selected to be strong and flexible. As a material of the protective film 16, for example, a synthetic resin sheet such as polycarbonate can be adopted. The thickness of the protective film 16 is preferably selected from a range of 0.1 mm to 0.5 mm. When the thickness is 0.5 mm or more, the bending rigidity of the protective film 16 is increased, and the radius of curvature of the curved portion of the protective film due to the pressing of the tire T is not reduced. As a result, the force (surface pressure) applied perpendicularly to the pressure sensor sheet 13 and its range may be difficult to measure accurately. That is, although the load values applied from the tire to the large number of force detection portions of the pressure sensor sheet 13 are different from each other, the same detection value may be obtained due to the poor adaptability of the protective film 16. sell. As a result, the accuracy of the image of the ground plane obtained from the measurement data may be rough. If the thickness is less than 0.1 mm, it may be difficult to obtain a film that can withstand the tension.

  If the tension applied to the protective film 16 is too large, the protective film 16 may be damaged, and if it is too small, the protective film 16 may slide between the pressure sensor sheet 13 and wrinkles may occur. The tension applied to the protective film 16 is preferably set in the range of 2 kN to 10 kN for the protective film 16 having a width of 25 cm. The tension is proportionally increased or decreased according to the increase or decrease of the width of the protective film 16.

  A lubricant is injected between the pressure sensor sheet 13 and the protective film 16 (gap D in FIG. 1). The purpose is to remove the friction between the pressure sensor sheet 13 and the protective film 16. By injecting the lubricant, the friction coefficient of the lower surface of the protective film 16 is drastically lowered, so that it is possible to prevent the friction force from being applied to the pressure sensor sheet 13 from the tire T through the protective film 16. As the lubricant, a low-viscosity lubricating oil, soapy water, or the like can be used. A commercially available liquid detergent diluted with water having a volume of about 10 times may be used. A preferred example of this commercially available detergent is arbos soap: chlorxylenol 0.3% edetate. The viscosity of the lubricant is preferably low. This is because if the viscosity is high, the flow is poor and the protective film 16 may be uneven.

  Ideally, the tension applied to the protective film 16 is applied to the protective film 16 in all directions (360 ° direction). However, any one of the front-back direction and the axial direction of the tire T may be sufficient. In the embodiment described above, the direction of the tension applied to the protective film 16 is the front-rear direction of the tire T, in other words, the longitudinal direction of the grounding body 3. Even when such tension is applied, the displacement of the protective film 16 can be suppressed against the frictional force in the tire T-axis direction on the protective film 16.

  In the present invention, tension may be applied to the protective film 16 in the axial direction of the test tire T, in other words, in the width direction of the grounding body 3. Such a configuration can be easily realized by installing the tension adjusting unit 18 and the film fixing unit 19 opposite to both ends of the grounding body 3 in the width direction. Alternatively, as described above, the grounding body 3 is fixed so as not to be movable, and the pressing device 4 can be easily adopted for a measuring device in which the grounding body 3 is movable in the longitudinal direction. Thus, even when the tension is applied in the axial direction of the test tire T, the displacement of the protective film 16 can be suppressed against the frictional force in the longitudinal direction of the tire T on the protective film 16. . In addition, although the structure is complicated, tension may be applied to the protective film 16 in both the front-rear direction and the axial direction of the test tire T.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Evaluation of measurement accuracy]
The measurement accuracy of the contact surface shape and contact surface pressure is evaluated using the measurement apparatus 1 described above. The size of the test tire T is 330 / 710R17. As the pressure sensor sheet 13 used, a sensor sheet manufactured by Tekscan is used. As the protective film 16, LAIRD PLASTICS made by LAIRD PLASTICS is used. A plurality of types of protective films are used. There are also several types of tension applied to the protective film. The evaluation is performed by pressing and rotating the tire T in a state where the protective film 16 is attached to the measuring apparatus 1 and the adjusting bolt 23 is operated to apply tension to the protective film 16. The tension is measured by the load cell 24 described above. The evaluation is based on the measurement accuracy of the grounding shape and the contact surface pressure that change due to damage to the protective film 16, slip between the protective film 16 and the sensor sheet 13, bending rigidity (bending anti-adaptation) of the protective film 16, and the like. Done about.

[Example]
The measurement accuracy of the contact surface shape and contact surface pressure was evaluated by the method described above. In the examples, among the 26 examples shown in Table 1, the thickness of the protective film 16 used is 0.02 mm, 0.10 mm, 0.20 mm, 0.50 mm, and 1.00 mm, and Twenty examples satisfying the conditions that the tension applied to the protective film 16 is 1 kN, 2 kN, 5 kN, and 12 kN (20 examples on the lower right surrounded by a thick line in Table 1). All the width dimensions of the film are 25 cm (range in which tension is applied).

[Comparative example]
By the method described above, the measurement accuracy of the contact surface shape and contact surface pressure was evaluated in the same manner as in the example. However, no tension was applied to the protective film 16 used. In the comparative example, among the 26 examples shown in Table 1, the protective film 16 is not used (described as “the thickness of the protective film is“ none ”)” and the protective film 16 is used. However, there are five examples in which the tension applied to the protective film 16 is 0 kN. All the width dimensions of the film are 25 cm (range in which tension is applied).

[Evaluation]
The evaluation results are represented in Table 1 by A, B, C, D, E, and F. A indicates that a good measurement result with high accuracy was obtained. B indicates that the accuracy of the measurement result is rough and lacks accuracy. C indicates that the pressure sensor sheet 13 is damaged due to generation of wrinkles of the protective film 16, and the accuracy of measurement is lacking. D indicates that the protective film 16 is damaged, so that measurement is not easy and accuracy is lacking. E shows that the protective film 16 slipped with the tire on the pressure sensor sheet 13 and measurement was impossible. F indicates that the pressure sensor sheet 13 was damaged and measurement was impossible. From this evaluation result, the superiority of the present invention is clear.

  The tire ground contact state measuring apparatus according to the present invention can contribute to elucidating a more desirable ground contact state of the tire, and thus can be applied to the development of a more preferable tire.

DESCRIPTION OF SYMBOLS 1 ... Measuring apparatus 2 ... Base 3 ... Grounding body 4 ... Pressing device 5 ... Guide rail 6 ... Engagement frame 7 ... Drive device 8 ... Swing arm 9 ... Support member 10 ... Main body (of pressing device) 11 ... Vertical swing drive 12 ... Horizontal swing drive 13 ... Pressure sensor sheet 14 ... Elevators 15a, 15b ... Linear electrode 15c ... Sheet 16 ... Protective film 17 ... Tension load device 18 ... Tension adjusting part 19 ... Film fixing part 20 ... Film edge holding member 21 ... Support frame 22: fixing member 23 ... adjusting bolt 24 ... load cell 25 ... measuring device fixing member T ... tire

Claims (6)

A grounding body,
A pressing device for pressing the tire against the grounding body;
A pressure sensor sheet having a large number of pressure measurement points disposed on the surface of the grounding body;
A protective film arranged to cover the upper surface of the pressure sensor sheet;
A tire ground contact state measuring device including a tension applying device for applying tension to the protective film.   The tire ground contact state measuring device according to claim 1, wherein a lubricant is injected between the pressure sensor sheet and the protective film.   The tire ground contact state measuring device according to claim 1 or 2, wherein the protective film thickness is 0.1 mm or more and 0.5 mm or less.   The tension is applied in a range of 2 kN or more and 10 kN or less with respect to a width of 25 cm of the protective film in a direction perpendicular to the direction of the tension, and the tension increases or decreases in proportion to the increase or decrease of the width of the protective film. 4. The tire ground contact state measuring device according to any one of 3 above. Arranging a protective film so as to cover the surface of the grounding body on which the pressure sensor sheet is installed;
Applying a tension to the protective film;
Interposing the protective film, pressing the tread surface of the tire against the surface of the grounding body;
A method for measuring a ground contact state of a tire, including a step of measuring a pressing force from the tire at a plurality of pressure measurement points of the pressure sensor sheet.   The tire ground contact state measuring method according to claim 5, wherein in the step of arranging the protective film, a lubricant is injected between the pressure sensor sheet and the protective film.

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