JP4386427B2 - Pressure measuring device - Google Patents

Description

  The present invention relates to a pressure measuring device, for example, a pressure measuring device for a ground contact portion of a tire.

  Conventionally, in order to analyze the dynamic or static characteristics of a tire, it is important to measure the contact pressure of the tire, and several measurement methods have been proposed.

  Specifically, for example, as shown in FIG. 7 (referred to as Conventional Configuration Example 1), a surface corresponding to the long side of the right-angle prism 34 is adhered to the lower portion of the tempered glass plate 33 serving as a substitute road surface with a transparent adhesive, and the prism 34 The light is applied through the inclined surface of the tempered glass plate and totally reflected on the upper surface of the tempered glass plate 33. When the tire 31 is brought into contact with the upper portion of the tempered glass plate 33, the amount of reflected light changes depending on the contact pressure. Therefore, the relationship between the amount of reflected light and the pressure is obtained, and the amount of light absorbed by the minute area of the contact portion is measured and converted to pressure. There is a method in which this measurement is performed over the entire surface of the contact portion and processed by a computer to display the pressure distribution state of the tire as a color image (see, for example, Patent Document 1).

Further, as shown in FIG. 8 (referred to as “conventional configuration example 2”), a sheet-shaped pressure detection body in which a plurality of parallel electrode wires are orthogonally crossed to form a grid-shaped detection end has been proposed. Thus, a planar pressure distribution can be displayed as an image. That is, as shown in FIG. 9A, the sheet 50 is formed by coating the longitudinal electrode 54 disposed on the back sheet 52 with the pressure-sensitive conductive ink 72, and the back sheet 62 as shown in FIG. The sheet 60 coated with the pressure-sensitive conductive ink 74 is overlapped with the arranged lateral electrode 64 so as to be integrated, and the intersection forms a detection end (see, for example, Patent Document 2).
Japanese Utility Model Publication No. 7-2944 US Pat. No. 4,856,993

  However, when measuring the tire contact pressure as described above, there are some problems that require improvement.

  That is, in the method as in Conventional Configuration Example 1, it is advantageous to measure the static ground pressure, but there is a problem that high optical accuracy is required, the apparatus is large and lacks versatility. Furthermore, when dynamic contact pressure measurement such as rotational movement of the tire is performed, there is a big problem that the image on the measurement surface is not stable.

  For the sheet-like pressure detection unit as in the conventional configuration example 2, it is advantageous to measure the static ground pressure in a wide plane, but there is a problem in that the sensitivity at each detection end in the sheet varies. was there. Further, when the tire is rolled, there is a problem that the sheet is damaged or the detection end is broken, which is not suitable for dynamic measurement. In addition, if the grid density is increased to increase the measurement density, adjacent detection edges may be affected by each other. However, if the grid density is decreased to reduce these effects, the measurement density will decrease. There was also a problem of becoming.

  Accordingly, an object of the present invention is to provide a pressure measuring device that has a strong structure that does not affect even if a vertical, horizontal, and horizontal force is applied to the detection unit and that can be extracted as multidimensional pressure information with a high measurement density. To do. In particular, an object of the present invention is to provide a pressure measurement device that requires high measurement density and can be applied to dynamic measurement as in the case of measuring the tire contact pressure.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-described object can be achieved by a pressure measuring device shown below, and have completed the present invention.

In the present invention, a plurality of pressure detectors composed of a pressure-sensitive conductive elastomer having an application electrode, an output electrode, and a measurement surface are arranged in a plane at regular intervals, and the outputs of the plurality of pressure detectors are used as multidimensional information. A pressure measuring device to be taken out,
Wherein the periphery of the pressure detecting portion, the outer peripheral cover portion of the rigid body for limiting the deformable region of the pressure-sensitive conductive elastomer provided, provided with a narrow gap between the outer peripheral cover and the pressure detecting unit, wherein At least a part of the outer peripheral cover part is conductive, and the narrow gap part is filled by the deformation of the pressure-sensitive conductive elastomer during pressure measurement, and the pressure detecting part and the outer peripheral cover part are electrically connected. .

  In other words, when pressure is applied to the entire surface, a pressure detection unit is provided in a subdivision of the planar pressure detection unit, and a pressure-sensitive conductive elastomer (hereinafter referred to as “pressure-sensitive element”) is used as the pressure detection unit. As a result, it was found that the function of the pressure-sensitive element can be quickly recovered as the applied pressure is released. Especially when dynamic pressure measurement is performed, the pressure measurement is accurately performed. be able to. In addition, by arranging a plurality of such pressure detection units in a plane at regular intervals, a two-dimensional pressure distribution, or a three-dimensional distribution including the resistance value of each pressure detection unit, and the same target are repeatedly measured. In some cases, a four-dimensional distribution including time can be obtained as information. Therefore, it provides a pressure measurement device that has a robust structure that does not affect the detection unit even when force is applied to the detector, can be extracted as multidimensional pressure information with a high measurement density, and can perform dynamic measurement. can do.

In addition, by providing a rigid outer cover around the pressure detector and limiting the deformable area of the pressure-sensitive conductive elastomer (pressure-sensitive element), the robustness is enhanced and the pressure-sensitive element is deformed. Recovery can be done quickly and reliably. Furthermore, as will be described later, since only the region where the correlation between the pressure and the resistance value is optimal can be used, high measurement accuracy can be ensured. Therefore, it is possible to provide a pressure measuring device that can ensure a strong structure and perform dynamic measurement. In addition, the structure having such a narrow gap portion is effective in that the reproducibility of the pressure detection unit can be ensured because it can bring about a spatial delay to recover the deformation of the pressure sensitive element due to pressurization. is there.

  As described above, durability and pressure resistance of the pressure detection unit itself of the measuring device are required for tire ground pressure measurement and the like. In addition, in order to ensure the reproducibility required as an important characteristic of the detection unit, a mechanically plastic structure is indispensable. In the present invention, a protective cover that covers the measurement surface is provided, and a pressure detection unit is damaged by providing a cover portion that covers the outer periphery so that the deformation stops at a predetermined height while securing the measurement surface. Or destruction can be prevented and the deformation | transformation recovery of a pressure-sensitive conductive elastomer can be performed rapidly and reliably. Therefore, it is possible to provide a pressure measuring device that can ensure a strong structure and perform dynamic measurement.

Further, according to the present invention, in addition to the above features, at least a part of the outer peripheral cover portion has conductivity, and the narrow gap portion is filled by deformation of the pressure-sensitive conductive elastomer at the time of pressure measurement. The cover portion is electrically connected.

  When a pressure-sensitive conductive elastomer is used as a pressure detector, the pressure-resistance value (current value) correlation is closer to a linear relationship after a certain deformation occurs, and high measurement accuracy can be obtained. . Accordingly, the surface of the outer periphery cover part of the pressure detection part or the entire surface is formed of a conductive member, and the narrow gap part provided between the pressure detection part and the cover part is used as a contact point, so that the pressure detection part is deformed constantly. By making the measurement start time clear, the measurement accuracy can be improved. Moreover, since such a narrow gap part can bring about a spatial delay which recovers the deformation | transformation accompanying pressurization, it can ensure the reproducibility of a detection part.

  The present invention is characterized in that the pressure measuring device is used for measuring a ground contact pressure of a tire, and the plurality of pressure detecting units are in contact with one block in a tread pattern of the tire.

  The pressure measuring device as described above is useful for measuring the pressure in a minute part. Especially, in dynamic measurement under pressure conditions such as measurement of tire ground pressure, pressure that enables robust and highly accurate measurement. A measuring device can be provided.

  As described above, in the present invention, a pressure measurement element is used as a robust and small spot pressure detection unit, and the pressure detection unit is formed into a planar pressure measurement device with an optimal structure and optimal arrangement, thereby achieving high measurement density. It is possible to provide a pressure measuring device capable of dynamic measurement that requires In particular, a pressure measurement device with high measurement accuracy can be provided by adopting a structure that promptly recovers the pressure detection unit accompanying deformation.

  Specifically, the robust and high measurement density function of the present invention is very effective for applications in which a load is directly applied to the pressure detection unit, such as tire ground pressure measurement.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 illustrates a pressure measuring device according to the present invention. A pressure detection unit 1 including a plurality of pressure detection units and application electrodes and output electrodes corresponding to the pressure detection units is fixed to the base body 4 by a frame 3 via a protective cover 2. For example, in the measurement of the tire, by scanning the tire over the frame 3, each pressure detection unit of the pressure detection unit 1 can sense the pressure and measure the tire contact pressure.

  Here, the protective cover 2 is provided for the purpose of preventing damage or contamination caused by the direct contact of the object with the pressure detection unit 1 or maintaining insulation, for example, a rubber of about several tens to several hundreds of micrometers. Alternatively, a flexible resin film or the like can be used.

  In addition, the material and the configuration of the frame 3 and the base body 4 are not limited as long as the pressure detection unit 1 is held and fixed. For example, a metal, a ceramic, or a rigid resin can be used. Alternatively, it is possible to form a configuration similar to that of a general wiring board using a resin such as glass epoxy. Furthermore, a flexible substrate can be formed using a polyimide-based high-functional resin or the like.

  In the pressure measuring device, as illustrated in FIG. 2, a plurality of pressure detectors 5 are arranged in a plane at regular intervals. By arranging in this way, two-dimensional pressure information can be obtained, and the pressure detection unit 1 is subdivided into small pressure detection units 5 so that one has a robust structure against pressure deformation. Another advantage is that it is possible to obtain abundant information about pressure from the pressure detection unit 1.

For the former, the pressure receiving area is the entire pressure detection unit 1, but the pressure detection unit 5 has only a very narrow pressure receiving surface (measurement surface), and is not subject to pressure from the adjacent portion. Thus, destruction or squeezing due to rapid compression can be prevented. In particular, it is possible to further enhance the robustness by providing a rigid outer peripheral cover part around the pressure detection part 5 as will be described later and limiting the deformation amount of the pressure detection part 5 within a predetermined range. . Moreover, since it is possible to obtain a highly independent output without being affected by the adjacent portion, it is possible to ensure high-accuracy pressure measurement. Furthermore, each pressure detection unit 5 can be easily calibrated by, for example, a constant pressure checker, mutual traceability can be easily ensured, and measurement accuracy can be further improved.

  About the latter, the magnitude | size and arrangement | sequence of the pressure detection part 5 can be set arbitrarily, and it sets in consideration of the amount of information required by detection sensitivity or measurement object. For example, in the measurement of a tire, the pressure detection unit 5 is set to about 0.5 to 1.5 mmφ and arranged at intervals of 2 to 3 mm, so that one block having a width of 5 to 10 mm in the tread pattern of the tire is used. Measurement of 5 to 10 points can be performed. When the pressure detection unit 1 having a width of 200 to 300 mm is formed based on such an arrangement, measurement of 100 to 150 points in the width direction is possible, and sufficient information can be obtained for dynamic measurement of the tire. . This is very useful in evaluation tests for various tires, such as analyzing the difference in dynamic contact pressure due to the difference in tire air pressure.

  Moreover, in this apparatus, the pressure detection part 5 is comprised with the pressure sensitive conductive elastomer (pressure sensitive element). The pressure-sensitive element is inherently plastic with respect to pressure deformation, and in this apparatus, since each pressure detection unit 5 has a small capacity as described above, the shape is quickly recovered as pressure is released, A highly accurate pressure measurement output with good reproducibility can be obtained. Further, as will be described later, the pressure-sensitive conductive elastomer has a characteristic that the electric resistance value changes due to pressure deformation, and the pressure value and the resistance value have a predetermined correlation under a certain condition. Therefore, by utilizing such characteristics and forming the pressure detection unit 1 as described above, the output of each pressure detection unit can be extracted as three-dimensional pressure information. Furthermore, when the same object is repeatedly measured, it can be extracted as plane information and four-dimensional information obtained by adding time to the resistance value of each point.

  Any pressure sensitive element can be selected as long as it can form the pressure detecting portion 5 as a molded body of rubber or resin. Specifically, conductive type elastomers in which conductive materials are mixed with insulating rubber materials can be used, but conductive paints, organic semiconductors, piezoelectric elements such as piezo elements and polyvinylidene fluoride, etc. are used. The molded body can also be used.

  Although the shape of the pressure detection unit 5 is shown as a cylindrical shape in FIG. 2, the shape is not limited to this, and is arbitrarily set such as a cubic shape, a prismatic shape, or a cylindrical shape whose cross section is a polygonal shape. be able to. Further, the measurement surface 5a is not limited to a flat surface as long as the pressure at the contact surface (point) can be transmitted to the entire pressure-sensitive element. It is possible to set arbitrarily, for example, when a projecting portion is provided at a location. Further, the outer peripheral surface 5b is not particularly limited, and may be part of the outer periphery (one or a plurality of locations or the peripheral surface) so as to facilitate contact with the outer peripheral cover portion through a narrow gap portion to be described later. It is possible to arbitrarily set such as providing a protrusion.

  FIG. 3A shows a cross section of a configuration example of the pressure detection unit 5. A protective cover 2 and an outer cover portion 6 that cover the measurement surface 5a and the outer peripheral surface 5b of the pressure detector 5 are provided. In FIG. 3A, the protective cover 2 and the outer peripheral cover portion 6 are illustrated as an integrated member, but the present invention is also applicable to a case where they are separate bodies.

  The details of the pressure detection unit 5 are illustrated in FIG. Here, the pressure sensitive element 7 is attached to the substrate 9 via the plated layer 8, and the application electrode 10 and the output electrode 11 are connected to the pressure sensitive element 7 via the plated layer 8. Here, when a predetermined voltage is applied to the application electrode 10, the current value between the two electrodes changes in accordance with the change in the resistance value of the pressure-sensitive element 7. That is, when pressure is applied to the measurement surface 5a, the pressure-sensitive element 7 changes in resistance value corresponding to the pressure. The generated change in resistance value is a change in current value corresponding to the amount of change. Therefore, if the current value is measured via the output electrode 11, the pressure on the measurement surface 5a can be measured.

  An example of the correlation between the pressure on the measurement surface 5a and the resistance value (current value) of the pressure-sensitive element 7 is shown in FIG. On the semilogarithmic graph, the two regions (A) or (B) have a characteristic that is close to a straight line, and by using this region, the pressure on the measurement surface 5a can be easily measured. In addition, it is possible to ensure high measurement accuracy. In general, it is easier to measure the current value with high accuracy. Therefore, as shown in the area (A), when the change in the load amount is smaller than the change in the resistance value, the measurement accuracy with a higher load amount can be obtained. Can do. Further, by applying a predetermined amount of pressure to the pressure-sensitive element 7 in advance and making the characteristics of the pressure-sensitive element 7 usable in such a region (A) or (B), high measurement accuracy is ensured. Is also possible.

Here, as illustrated in FIG. 3B, it is preferable that at least a part of the height of the measurement surface 5 a is larger than the height of the outer peripheral cover portion 6. In other words, in the measurement of tire contact pressure, the durability and pressure resistance of the pressure detector itself of the measuring device are required, and in order to ensure the reproducibility required as an important characteristic of the detector. In particular, a plastic structure is indispensable. By providing a rigid outer cover around the pressure detector 5 and restricting the deformable region of the pressure-sensitive element 7 , as described above, the robustness is enhanced and the deformation of the pressure-sensitive element is recovered. It can be done quickly and reliably. In addition, since only the region where the correlation between the pressure and the resistance value illustrated in FIG. 5 is optimal can be used, high measurement accuracy can be ensured. Therefore, it is possible to provide a pressure measuring device that can secure a strong structure and perform dynamic measurement.

  The specific heights of the measurement surface 5a and the outer peripheral cover 6 are set according to the characteristics of the pressure sensitive element 7 and the pressure range necessary for actual measurement. For example, in the pressure detection unit configured as described above, which is used for tire contact pressure measurement, if the measurement surface 5a is about 0.1 to 1 mm higher, highly accurate detection is possible.

  Another embodiment of the present invention is illustrated in FIG. A configuration is adopted in which a narrow gap portion is provided between the outer peripheral cover portion 6 and the pressure detecting portion 5, and the pressure detecting portion 5 and the outer peripheral cover portion 6 can be electrically connected by deformation of the pressure sensitive element 7 at the time of pressure measurement. Yes.

  That is, for one thing, the structure having such a narrow gap portion can bring about a spatial delay in recovering the deformation of the pressure-sensitive element 7 due to pressurization, so that the reproducibility of the pressure detection portion 5 is ensured. Is effective.

  Further, as shown in FIG. 5, the relationship between the applied pressure and the resistance value of the pressure-sensitive element 7 is closer to a linear relationship at a certain applied pressure (load) G or higher, and the higher the closer to the linear relationship as described above, the higher the measurement. Accuracy can be obtained. In other words, the measurement accuracy can be improved by connecting the outer peripheral cover portion 6 to the application electrode 10 and using the pressure G that causes deformation so as to fill the narrow gap portion as a contact for starting measurement. In particular, in tire contact pressure measurement, the measured value from zero additional pressure does not necessarily require accuracy, and there is a strong demand for accurately measuring deviations above a predetermined pressure. The configuration using the narrow gap portion as a trigger is very useful.

  At this time, it is preferable that the pressure detection unit 5 is equidistant from the outer peripheral cover unit 6, and the distance of the narrow gap portion does not necessarily require strict management, and is practical if it is managed with a certain degree of accuracy. is there. Specifically, accuracy management of about 0.1 mm is sufficient, and when higher accuracy is required, for example, calibration with a constant pressure checker is possible. Further, the outer peripheral cover portion 6 does not need to be a conductor as a whole, and the outer cover portion 6 may be coated with a conductive material on the surface so as to be connected to the application electrode 10 and to the pressure sensitive element 7. Good.

  The output from the output electrode 11 is processed by a signal processing unit (not shown) and then displayed on a display unit (not shown), or converted into a digital signal and output from the pressure measuring device, and is multidimensional. Used as information.

  The pressure measuring device according to the present invention as described above is very useful particularly when used for measuring the ground contact pressure of a tire. In other words, in tire contact pressure measurement, the pressure distribution in one block of the tread pattern and the difference in pressure distribution in each block are important for the analysis of the dynamic characteristics of the tire. Can be provided with high accuracy. Specifically, three-dimensional information on the tire contact pressure at a small spot can be obtained continuously and reproducibly by a plurality of robust pressure detectors arranged at equal intervals. Therefore, it can be said that it is suitable for robust and highly accurate dynamic measurement.

  In the above, the application of the present invention to the pressure measuring device for measuring the ground contact pressure of the tire has been described. However, the same technical idea can be applied not only to the tire but also to other rubber molded bodies. Further, the shape of the measurement object can be applied to various shapes such as a flat shape or a curved surface shape, and can be applied to a wide range of uses.

  Specifically, in the sports field, the present invention can be applied to the measurement of athletic ability, for example, the measurement of the pressure distribution on the bottom surface of the running foot or the impact (pressure) distribution accompanying jumping. Also, in a wide range of fields and applications, such as measurement of load distribution with prosthetic hands and legs on the skin and skeleton in the medical field, or measurement of contact pressure distribution such as capture, pinching or pressing in the field of robotics And is very useful.

Explanatory drawing which shows the structural example of the pressure measuring device which concerns on this invention Explanatory drawing illustrating the arrangement of the pressure detectors in the above configuration example Explanatory drawing illustrating the configuration of the pressure detection unit in the above configuration example Explanatory drawing which illustrates the detail of a structure of the pressure detection part in the said structural example. Explanatory diagram illustrating the pressure-resistance characteristic of a pressure-sensitive conductive elastomer Explanatory drawing which illustrates the detail of a structure of the pressure detection part in another structural example which concerns on this invention. Explanatory drawing which shows the example of 1 structure of the pressure measuring device which concerns on a prior art Explanatory drawing which shows the other structural example of the pressure measuring device which concerns on a prior art. Explanatory drawing which shows the detail of the other structural example of the pressure measuring device which concerns on a prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure detection unit 2 Protective cover 3 Frame 4 Base body 5 Pressure detection part 5a Measurement surface 5b Outer peripheral surface 6 Outer peripheral cover part 7 Pressure-sensitive conductive elastomer (pressure-sensitive element)
10 Applied electrode 11 Output electrode

Claims (2)

A pressure measuring device in which a plurality of pressure detection units each composed of a pressure-sensitive conductive elastomer having an application electrode, an output electrode, and a measurement surface are arranged in a plane at regular intervals, and the plurality of pressure detection unit outputs are extracted as multidimensional information Because
Wherein the periphery of the pressure detecting portion, the outer peripheral cover portion of the rigid body for limiting the deformable region of the pressure-sensitive conductive elastomer provided, provided with a narrow gap between the outer peripheral cover and the pressure detecting unit, wherein At least a part of the outer peripheral cover part is conductive, and the narrow gap part is filled by the deformation of the pressure-sensitive conductive elastomer during pressure measurement, and the pressure detection part and the outer peripheral cover part are electrically connected. Pressure measuring device. 2. The pressure measuring device according to claim 1, wherein the pressure measuring device is used for measuring a ground contact pressure of a tire, and the plurality of pressure detecting units are in contact with one block in a tread pattern of the tire. .

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