JP2009025170A - Method for measuring deformation, and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily improve measurement accuracy and reproducibility, when measuring deformation. <P>SOLUTION: In the apparatus for measuring deformation, a first support body 21 provided with one-side electrodes 22 and 23 and, a second support body 28 provided with the other-side electrodes 30 and 31 paired with the one-side electrodes 22 and 23 are fixed separated to a support seat 18 fixed to a tire 11, as well as, the size is made large, by installing a cushion layer 35 between the second support body 28 and the support seat 18 so that the fixed position and the direction can be set easily to a prescribed position and direction, and thereby measurement accuracy and reproducibility at measurement of deformation are improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

    The present invention relates to a deformation measuring method and a deformation measuring device for measuring deformation of a measured object, for example, a pneumatic tire.

As a conventional deformation measuring method and deformation measuring apparatus, for example, those described in Patent Document 1 below are known.
JP 2002-002472 A

  This is a resistance wire strain gauge affixed to the inner periphery of the tread portion of a pneumatic tire, and the resistance change of the metal wire when the resistance wire of the strain gauge expands and contracts following the deformation (strain) of the tread portion. And a measurement unit for determining the deformation of the tread portion, and measuring the deformation of the tread portion based on the wiping deformation of the pneumatic tire.

    However, in such a conventional deformation measuring method and deformation measuring instrument, since the strain gauge is thin and small, about several mm square, the position and orientation of the strain gauge are attached to the specified position and orientation. As a result, there is a problem that the accuracy and reproducibility of the measurement results are lowered.

  An object of this invention is to provide the deformation | transformation measuring method and deformation | transformation measuring device which can improve a measurement precision and reproducibility easily.

    Such a purpose is as follows. First, the first support provided with the one-side electrode and the second support provided with the other-side electrode at a position separated from the first support are fixed, A cushioning layer made of a material having a smaller elastic coefficient than itself is interposed between either the first support or the second support, and a support sheet that can expand and contract following the deformation of the measured object. By a deformation measurement method comprising: a step of fixing to a measurement object to be deformed; and a step of obtaining a deformation of the measurement object based on a capacitance value between a pair of one side electrode and the other side electrode, Can be achieved.

  Secondly, a support sheet that is fixed to the measurement object at the time of measuring the deformation of the measurement object and that can expand and contract following the deformation of the measurement object; A first support body provided with a first support body, a second support body fixed to a support sheet at a position spaced apart from the first support body, and provided with an other electrode paired with the one side electrode, and a first support body A cushion layer made of a material having a smaller elastic coefficient than that of the support sheet, the one side electrode and the other side electrode forming a pair, interposed between either the body or the second support and the support sheet This can be achieved by a deformation measuring instrument that determines the deformation of the object to be measured based on the capacitance value between the two.

  In the present invention, the first support body provided with the one-side electrode on the support sheet and the second support body provided with the other-side electrode are separated and fixed, and either one of these and the support sheet is interposed between them. As a whole, the cushion layer is interposed, making it larger than conventional strain gauges. As a result, the fixing position and orientation can be easily set to the specified position and orientation, and the accuracy and reproducibility of measurement results can be easily achieved. Can be improved.

  In the present invention, when the support sheet expands and contracts following the deformation of the measured object, the first or second support without the cushion layer is displaced by the same amount as the support sheet. The remaining first or second support provided with the cushion layer has a displacement amount approaching zero because the cushion layer absorbs deformation. As a result, the distance between the first and second supports, specifically, the distance between the paired one side electrode and the other side electrode changes, and the capacitance value changes. That is, the deformation of the measured object is obtained based on the detection result.

  Further, if configured as in claim 3, it is possible to easily measure the deformation of the measured object in a desired direction with high accuracy. Further, if configured as in claim 4, if configured, Measurement can be easily performed in a state where the deformation of the measuring body is disassembled in two orthogonal directions. Further, if configured as described in claim 5, the support sheet can be manufactured easily and inexpensively, and if configured as described in claim 6, it is inexpensive but sufficiently absorbs deformation. can do.

Embodiment 1 of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 11 denotes a pneumatic radial tire as a body to be measured that is mounted on, for example, a passenger car, a truck, a bus, and the like. The tire 11 has a tread portion 13 that contacts a road surface 12 during traveling. A plurality of main grooves 14 that are wide and continuously extend in the circumferential direction, and wide lateral grooves 15 that extend in the width direction and intersect the main grooves 14 are formed on the outer periphery of the portion 13. In some cases, only one of the main groove 14 and the lateral groove 15 is formed on the outer periphery of the tread portion 13. When such a tire 11 is run under a load, various external forces are applied to the tread portion 13 in the ground contact region, causing expansion and contraction in at least one of the circumferential direction and the width direction.

  17 is a deformation measuring device installed on the inner periphery of the tire 11 (tread portion 13). The deformation measuring device 17 is a deformation in the circumferential direction and width direction on the inner periphery of the tread portion 13 based on the external force as described above. Is disposed on the inner periphery of the tread portion 13. The deformation measuring instrument 17 has a rectangular sheet-like support sheet 18 that is detachably fixed to the tire 11 (inner periphery of the tread portion 13) with an adhesive or the like, as shown in FIGS. The support sheet 18 is thin and has a constant thickness, and can expand and contract by the same amount in the same direction following the deformation of the tire 11 (tread portion 13).

  As a result, the support sheet 18 expands and contracts in the circumferential direction and the width direction following the deformation of the tire 11 (tread portion 13) each time the deformation measuring instrument 17 reaches the ground contact region by the rotation of the tire 11. When the external force is no longer applied away from the ground contact area, the original shape (length) is restored. Here, since the support sheet 18 described above is made of vulcanized rubber, it can be easily and inexpensively manufactured.

  21 is a first support whose base end (outer end) is directly fixed to the central portion of the support sheet 18 and extends in the radial direction toward the rotation axis of the tire 11, and this first support 21 is a hollow octagon. It is columnar and is made of a rigid body such as plastic. Of the outer surfaces of the first support 21, the two outer surfaces 21a that are orthogonal to the tire circumferential direction and are 180 degrees apart from each other in the circumferential direction of the first support 21 have plate-like one-side electrodes 22 respectively. On the other hand, rectangular plate-shaped one-side electrodes 23 are fixed to two outer surfaces 21b that are orthogonal to the tire width direction and that are 180 degrees apart from each other in the circumferential direction of the first support 21. . Here, the one-side electrodes 22 and 23 may be provided by being embedded in the first support 21.

  In the case where only deformation in one direction (for example, circumferential direction or width direction) of the tire 11 is measured, only one of the one-side electrodes 22 and 23 may be provided. Furthermore, in order to measure deformation in a plurality of directions, it is preferable to provide two or more of these one-side electrodes. When a plurality of one-side electrodes are provided as described above, it is preferable to dispose these one-side electrodes on the first support 21 at an equal angle in the circumferential direction. The one-side electrodes 22 and 23 are made of a conductor such as copper or aluminum.

  A rectangular plate-like support plate 26 is made of a rigid body, for example, plastic, and is fixed to the support sheet 18 via a cushion layer to be described later. The support plate 26 has a central portion coaxial with the first support 21. A through hole 25 having a diameter larger than that of the first support 21 is formed, and a base end portion of the first support 21 is inserted into the through hole 25. A plurality of, here four, rigid bodies, for example, plastic-made brackets 27 having an L-shaped cross section are fixed to the support plate 26 in the vicinity of the inner periphery of the through-hole 25, and these brackets 27 are equiangular in the circumferential direction. Then it is 90 degrees away.

  These brackets 27 have projecting portions 27a projecting from the support plate 26 in the radial direction, and the projecting portions 27a of these brackets 27 face the one-side electrodes 22 and 23, respectively. The support plate 26 and the bracket 27 described above constitute a second support 28 fixed to the support sheet 18 at a position spaced apart from the first support 21 as a whole. Is fixed, the first support 21 can be displaced independently of the second support 28.

  30 is an other side electrode in the form of two rectangular plates fixed to the two brackets 27 (projecting portions 27a) facing the one side electrode 22 and paired with the one side electrode 22, These other side electrodes 30 are arranged apart from each other in the circumferential direction of the tire 11. 31 is an other side electrode that is fixed to two brackets 27 (protruding portions 27a) facing the one side electrode 23 and has two rectangular plates that are paired with the one side electrode 23; These other side electrodes 31 are arranged apart from each other in the width direction of the tire 11.

  The paired one-side electrodes 22 and 23 and the other-side electrodes 30 and 31 extend in parallel while facing each other, and the distance between the two is equal. As a result, a plurality of these pairs, here one side of the four pairs, the other side electrodes 22, 23, 30, 31 are arranged 90 degrees apart in the circumferential direction around the central axis of the first support 21. It will be. If the measurement accuracy does not have to be high, two pairs in total, which are 90 ° apart from the other side electrode, may be provided. The other side electrodes 30 and 31 are made of a conductor such as copper or aluminum in the same manner as the one side electrodes 22 and 23.

  As a result, the support sheet 18 expands and contracts by the same amount in the same direction following the deformation in the circumferential direction and the width direction of the tire 11 (tread portion 13), and the paired one side electrodes 22, 23 and the other side electrode When the distance between 30 and 31 changes as described later, the value of the capacitance between the one-side electrodes 22 and 23 and the other-side electrodes 30 and 31 changes according to the change in the distance, The deformation in the circumferential direction and the width direction of the tire 11 (tread portion 13) can be measured.

  Further, as described above, if the plurality of one-side and other-side electrodes that are paired are arranged 90 degrees apart in the circumferential direction, the deformation of the tire 11 (tread portion 13) can be performed without performing complicated calculations. , And can be easily measured in a state of being decomposed in two orthogonal directions. When multiple pairs of one side and other side electrodes are installed, these one side and other side electrodes can be spaced apart in the circumferential direction by an angle other than 90 degrees. By performing the calculation based on the capacitance value (detection result) between the one side electrode and the other side electrode, the deformation of the tire 11 (tread portion 13) in a desired direction can be measured with high accuracy. The effect becomes more prominent as the number of pairs of one side electrode and the other side electrode increases.

  Reference numeral 35 denotes a cushion layer interposed between the second support 28 (support plate 26) and the support sheet 18. By interposing this cushion layer 35, the second support 28 is attached to the support sheet 18. It will be fixed indirectly. The cushion layer 35 is made of a material having a smaller elastic coefficient than the support sheet 18, and as a result, when the support sheet 18 expands and contracts following the tire 11 (tread portion 13), the cushion layer 35 is supported by the support sheet 18. Thus, the displacement amount of the second support 28 approaches zero. Here, it is preferable that the cushion layer 35 is made of a synthetic sponge such as a urethane foam that is porous, because the deformation can be sufficiently absorbed while being inexpensive.

  Reference numeral 38 denotes a measurement unit fixed to the second support 28 (bracket 27). The measurement unit 38 is composed of a control board such as an IC chip. The measuring unit 38 and the one-side electrodes 22 and 23 are connected by a signal line 39, while the measuring unit 38 and the other-side electrodes 30 and 31 are connected by a signal line 40, respectively. The capacitance value (detection result) corresponding to the distance between the one side electrode 22, the other side electrode 22, 30, 31, and the like is sent to the measurement unit 38.

  When the capacitance value (detection result) is sent to the measurement unit 38 in this way, the measurement unit 38 performs a calculation based on the capacitance value (detection result) between the one side electrode 22 and the other side electrode 30. The tire 11 (tread portion 13) is deformed in the circumferential direction, and the calculation is performed on the basis of the capacitance value (detection result) between the one side and the other side electrodes 23, 31. Find the deformation in the width direction.

  Specifically, when the deformation measuring instrument 17 is located outside the grounding area, an average capacitance value between one side electrode and the other side electrode forming a pair is obtained and stored in the measuring unit 38 as a reference value. When the capacitance value between the deformation measuring device 17 reaches the grounding region and the pair of electrodes on the one side and the other side of the electrode change to change the capacitance value between them, the changed capacitance value Is detected and compared with the reference value, and the deformation in the circumferential direction and the width direction of the tire 11 (tread portion 13) is measured from the comparison result. Here, the deformation in the circumferential direction and the width direction of the tire 11 is obtained by using an average value of two pairs of one side, other side electrodes 22, 23, 30, and 31, so that the deformation is highly accurate. Can be measured.

    As described above, the first support 21 provided with the one-side electrodes 22 and 23 and the second support 28 provided with the other-side electrodes 30 and 31 are separated from and fixed to the support sheet 18, and the second Since the cushion layer 35 is interposed between the support 28 and the support sheet 18, the overall size is larger than that of the conventional strain gauge. As a result, the fixing position and orientation can be easily set to the specified position and orientation. The accuracy and reproducibility of the measurement results can be easily improved. In addition, since the first and second electrodes 22, 23, 30, 31, and the measurement unit 38 are provided on the first and second supports 21, 28, the signal lines 39, 40 that connect them are formed by deformation of the tire 11. The situation that the wire breaks is suppressed, and thereby the interruption of the measurement work can be effectively suppressed.

Next, the operation of the first embodiment will be described.
When measuring the deformation of the tire 11 (tread portion 13) using the deformation measuring instrument 17 described above, an adhesive or the like is used on the inner periphery of the tire 11 (tread section 13) to support the deformation measuring instrument 17. Removably fix 18 Next, after the tire 11 is mounted on the rim and filled with the internal pressure, the tire 11 is run on the road surface 12 while being loaded with a predetermined load, and is rotated a plurality of times. At this time, when the deformation measuring instrument 17 is located outside the ground region using the measuring unit 38 based on the capacitance value (measurement result) between the one side and the other side electrodes 22, 23, 30, 31 ( The average capacitance value (when no external force is applied) is obtained and stored in the measurement unit 38 as a reference value. The reference value may be stored in the measurement unit 38 as a preset value.

  Next, when the tire 11 is run again and the deformation measuring instrument 17 reaches the ground contact region, the inner periphery of the tread portion 13 and the support sheet 18 expand and contract in the circumferential direction and the width direction following the expansion and contraction of the tire 11. At this time, since the cushion layer is not provided between the first support 21 and the support sheet 18, the first support 21 is displaced by the same amount as the support sheet 18, but the second support 28 and the support sheet 18 are supported. Since the cushion layer 35 is interposed between the seat 18 and the seat 18, the cushion layer 35 absorbs the deformation of the support sheet 18, and the displacement amount of the second support 28 approaches zero.

  Due to such displacement of the first and second supports 21 and 28, the distance between the paired one side electrodes 22 and 23 and the other side electrodes 30 and 31, that is, the capacitance value changes. The changed distance, that is, the capacitance value is output as a detection result from the one side, other side electrodes 22, 23, 30, 31 to the measurement unit 38. At this time, the measurement unit 38 compares the detection result with a reference value, and determines the deformation in the circumferential direction and the width direction of the tire 11 (tread portion 13) from these comparison results. The deformation of the tire 11 (tread portion 13) measured in this way is read from the measurement portion 38 by, for example, a reader installed outside the tire 11 by wireless communication. Further, based on the detection results from the one-side and other-side electrodes 22, 23, 30, and 31 described above, the input value to the tire 11 or the accumulated rotation number of the tire 11 can be obtained.

    In the above-described embodiment, the deformation measuring instrument 17 is installed on the inner periphery of the tread portion 13 of the tire 11. However, in the present invention, it may be installed on the sidewall portion of the tire, or the tire Other deformation members such as a conveyor belt, seismic isolation rubber, etc. may be installed to measure the deformation. In the above-described embodiment, the cushion layer 35 is interposed only between the support sheet 18 and the second support 28. However, in the present invention, the support sheet 18 and the first support 21 Even if the cushion layer is interposed only between the support sheets 18 and the support sheet 18 and the second support 28 are omitted, the deformation can be measured in the same manner.

  The present invention can be applied to the industrial field for measuring deformation of a measured object, for example, a tire.

It is sectional drawing of the tread part in the width direction which shows Embodiment 1 of this invention. It is a perspective view of a deformation measuring instrument vicinity. FIG. FIG. 4 is a cross-sectional view taken along the line II in FIG. 3.

Explanation of symbols

11 ... Measured object 18 ... Support sheet
21 ... 1st support body 22, 23 ... One side electrode
28 ... Second support 30, 31 ... Other side electrode
35… Cushion layer

Claims (6)

    The first support provided with the one-side electrode and the second support provided with the other-side electrode are fixed at a position spaced from the first support, and either the first support or the second support A cushioning layer made of a material having a smaller elastic coefficient than itself is interposed between the support sheet and the support sheet capable of expanding and contracting following the deformation of the measured object, and fixing the deformed measured object to the measured object. And a step of obtaining a deformation of the object to be measured based on a capacitance value between the paired one side electrode and the other side electrode.     A support sheet that is fixed to the measurement object at the time of deformation measurement of the measurement object and that can expand and contract following the deformation of the measurement object, and is fixed to the support sheet and provided with one side electrode A first support, a second support fixed to a support sheet at a position spaced apart from the first support, and provided with another electrode that forms a pair with the one electrode; and the first support or the second A cushion layer made of a material having a smaller elastic coefficient than that of the support sheet and interposed between any one of the supports and the support sheet, and is static between the pair of one side electrode and the other side electrode. A deformation measuring device characterized in that a deformation of a measured object is obtained based on a value of electric capacity.     The deformation measuring instrument according to claim 2, wherein a plurality of one-side and other-side electrodes forming the pair are arranged apart from each other in the circumferential direction.     The deformation measuring instrument according to claim 3, wherein the plurality of one-side and other-side electrodes forming the pair are arranged 90 degrees apart in the circumferential direction.     The deformation measuring instrument according to claim 1, wherein the support sheet is made of vulcanized rubber.     The deformation measuring instrument according to claim 1, wherein the cushion layer is made of a synthetic sponge.

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