JP2006337118A - Elastomer sensor and vibration detection method using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elastomer sensor which is easily and inexpensively manufacturable, and enables high-precision and stable measurement of stress, strain, vibration, or the like input over a broad measuring range. <P>SOLUTION: The elastomer sensor is constituted by using a sensor body molded in such a state that fine fillers having a granular or linear simple shape are mixed with elastomer material being scattered, and attaching a plurality of detecting electrodes for applying a detecting alternating voltage, to the sensor body. There, an impedance: Z to be detected in such a state that the detecting alternating voltage of a frequency of 1 kHz is applied to the detecting electrodes, is made to satisfy 100 Ω≤Z≤100 MΩ. Moreover, the phase angle: θ between the detecting alternating voltage and the detected impedance under detection conditions is made to satisfy 1°≤¾θ¾≤90°. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an elastomer sensor that can be suitably used for detecting stress, acceleration, vibration, deformation, and the like in a predetermined member, and a vibration detection method using the same.

  Conventionally, an inorganic strain sensor using an inorganic sensor material typified by a piezoceramic has been used as a sensor for detecting external force applied to a member, deformation of the member resulting from the force, or stress. Yes.

  However, since such an inorganic strain sensor is generally formed of a highly rigid material, the degree of freedom of the processing shape is limited. In addition, it is necessary to determine and adjust the sensor material according to the detection range such as the strain expected for the detection target member, and it is difficult to realize a strain sensor that can detect external force and deformation over a wide measurement range. there were.

  In view of such circumstances, an elastomer sensor which is an organic sensor using a pressure-sensitive conductive elastomer has also been proposed (Patent Document 1). Such an elastomer sensor is obtained from a composite material in which conductive particles are mixed with an elastomer, and the amount of compressive deformation is determined based on the fact that the contact state between the conductive particles changes with compressive deformation. It is supposed to detect as.

  Such an elastomer sensor has an advantage that the shape can be selected with a high degree of freedom since it is easy to process. However, an elastomer sensor having a conventional structure that merely detects the amount of compressive deformation by simply changing the resistance value of a direct current has a large variation in the characteristics of strain and detected value, making it difficult to obtain stable measurement results. Variations in the characteristics of the distortion and the detected value tend to occur greatly when the deformation direction is different not only among the individual sensors but also with one sensor. For this reason, the reliability of the measurement results is low, and there are many cases where the accuracy required in the industry cannot be obtained.

  In addition, in an elastomer sensor having a conventional structure, the detection sensitivity differs significantly depending on the mixing ratio of the conductive particles to the elastomer material. For this reason, it is difficult to impart measurement characteristics such as intended sensitivity, and it is very difficult to design and manufacture.

  Furthermore, in the conventional structure of the elastomer sensor, the amount of compressive deformation is detected simply by the change in the resistance value of the direct current, so that the detected value changes little after the mixed conductive particles reach a certain contact state. I will not. Therefore, there is a problem that the detection range of external force and stress is small.

  In Patent Document 2 (Japanese Patent Laid-Open No. 2005-49332), a special carbon fiber having a micro helical coil shape is employed, and the coiled carbon fiber is dispersed in a medium such as rubber. A tactile sensor has been proposed.

  However, since such a tactile sensor requires a very special coiled carbon fiber, it is extremely difficult to manufacture, and it is difficult to say that it is practical except for special applications. Further, since the inductance component, the capacitance component, and the resistance component of the coil-shaped carbon fiber itself are used, the characteristics of the contact sensor itself greatly depend on the structure and performance of the carbon fiber itself. Moreover, in view of the current situation where it is difficult to say that such a coiled carbon fiber itself is still in a stable supply state, it is expected that it is difficult to desire high reliability and performance stability.

  Further, the detection characteristic is derived from an inductance component or the like in the coil-shaped carbon fiber itself, but it is difficult to think that the deformation amount of the minute carbon fiber itself is so large. Therefore, in such a tactile sensor, it is difficult to obtain a measurement characteristic with such a high sensitivity or to secure a wide measurement range.

JP 03-93109 A JP 2005-49332 A

  Here, the present invention has been made in the background as described above, and the problem to be solved is that it is possible to measure the amount of distortion over a wide measurement range (measurement range) and to provide high accuracy. An object of the present invention is to provide an elastomer sensor having a novel structure that can be stably realized and can be easily manufactured.

  Hereinafter, the aspect of this invention made | formed in order to solve such a subject is described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible. Further, aspects or technical features of the present invention are not limited to those described below, but are described in the entire specification and drawings, or an invention that can be understood by those skilled in the art from those descriptions. It should be understood that it is recognized based on thought.

  That is, the first aspect of the elastomer sensor according to the present invention is an elastomer sensor comprising a sensor main body in which an elastomer is mixed with a conductive filler, and a detection electrode for detecting the impedance of the sensor main body. A granular or linear fine filler is employed as the conductive filler in the sensor body, and impedance detected when an AC voltage for detection having a frequency of 1 kHz is applied to the detection electrode: Z is 100Ω ≦ Z ≦ 100 MΩ, and the phase angle between the detected AC voltage and the detected impedance under the action state of the load to be detected: θ is 1 degree ≦ | θ | ≦ 90 degrees And

  In the elastomer sensor having the structure according to this aspect, instead of detecting an external force or the like based on a change in DC resistance value in the pressure-sensitive conductive elastomer described in Patent Document 1, impedance is detected. : An external force or the like is detected based on the change in Z.

  In addition, a sufficiently wide measurement range can be ensured by adopting a specific sensor main body in which the value of impedance Z in the applied state of an alternating voltage with a frequency of 1 kHz is 100Ω ≦ Z ≦ 100MΩ. .

  Furthermore, in a state where the detection load is applied and elastically deformed by a predetermined amount, the value of the phase angle θ between the detection applied AC voltage and the detected impedance is 1 degree ≦ | θ | ≦ 90. By adopting a sensor body with specific spring characteristics and electrical characteristics that have been measured, excellent measurement accuracy can be more advantageously ensured over a wide measurement range.

  However, by employing a sensor body having such a phase angle: θ, not only inductive reactance: L and capacitive reactance: C but also resistance: R can be considered as a contribution to the detected impedance. . Therefore, for example, even when the frequency of the input vibration is different or changes, the input load can be detected with high accuracy using the detection value effective for the static load and the detection value effective for the dynamic load. Is possible.

  In addition, in the present invention, a special mixed material as shown in Patent Document 2 described above is not particularly required. That is, the fine filler as the conductive filler employed in this embodiment is granular or linear, and a special material such as carbon microcoil (coiled carbon fiber) that is essential in Patent Document 2 is unnecessary.

  In other words, Patent Document 2 discloses a tactile sensor in which an LCR resonance circuit is configured by using a very special coiled carbon fiber and utilizing the characteristics of the coiled carbon fiber itself as a current-carrying coil. ing. On the other hand, the present inventor has found that, as a result of research, a sensor capable of detecting an external force based on a change in inductance can be put into practical use without employing such a coiled carbon fiber. It was discovered for the first time, and the present invention was completed based on such knowledge.

  Although the technical clarification of the elastomer sensor according to the present invention is not yet complete, as is clear from the examples described later, a rubber elastic body using a granular or linear simple shape conductive filler (micro filler) as a medium. There is no doubt that it is possible to detect the deformation state by the inductance as a whole by being dispersed in the elastomer. This is presumed that the conductive fillers scattered in the elastomer can function as a coil, a capacitor, a resistor, etc. as a whole by electrically interacting with each other close to each other. Note that the fine fillers do not have to be separated and scattered separately, and a large number of fine fillers may exist in a state where they are in contact with each other or entangled with each other. Depending on the blending amount, the particle size and length of the fine filler to be mixed, the slenderness ratio, etc., the desired performance can be set appropriately. When the sensor body is elastically deformed, the mutual positional relationship between the conductive fillers dispersed in the elastomer changes, so that virtual components such as coils, capacitors, resistors, etc. that are formed by these conductive fillers change. Therefore, it is considered that the characteristic of a simple electric element changes and the result is detected as a change in impedance.

  In addition, it should be particularly noted that the conductive particles themselves have special electrical characteristics (L component) like the coiled carbon fiber described in Patent Document 2, as is apparent from the results of Examples described later. Since it is not a thing, the elastic deformation of the whole sensor main body will be reflected obediently and efficiently as a change of the value of detection impedance. Therefore, in the elastomer sensor having the structure according to the present invention, it is possible to detect the external force with a sufficiently satisfactory accuracy with a stable detection accuracy over a relatively wide measurement range.

  Of course, the elastomer sensor having a structure according to the present invention does not require a very special material like the coiled carbon fiber required for the tactile sensor described in Patent Document 2, and has been marketed conventionally. Because it is configured by adopting carbon particles such as carbon black and conductive fillers of simple shape such as carbon fibers and carbon nanotubes as fine particles, it is easy to manufacture and inexpensive to manufacture. This is a very advantageous effect in industrial implementation.

  A second aspect of the elastomer sensor according to the present invention is the elastomer sensor according to the first aspect, wherein the detection electrode is configured by a plurality of electrodes fixed to different positions in the sensor body. Is a feature.

  According to this aspect, by providing electrodes for applying an AC voltage for detection sufficiently apart, it is possible to detect a wider range of electrical characteristics, thereby further improving detection accuracy. Can be illustrated.

  Further, the electrodes to be employed do not have to be a pair, and may be provided in three or more, or two or more pairs. By providing such a large number of electrodes, a change in electrical characteristics (impedance) between these electrodes can be detected with higher accuracy by, for example, obtaining an average value or the like, or obtaining, for example, a total value or the like. This makes it possible to detect with higher sensitivity.

  Further, according to a third aspect of the elastomer sensor of the present invention, in the elastomer sensor according to the first or second aspect, the dynamic distortion in the sensor body and the detected impedance: Z have linearity. The region covers the range of strain rate (ε) in the sensor body: ε (1) to ε (2), and | ε (1) −ε (2) | ≧ 5 (%) It is characterized by being.

  In the elastomer sensor having the structure according to this aspect, the detection circuit is simplified by making the load-strain characteristic, that is, the external force-detection value characteristic substantially linear over a sufficiently wide measurement range. In addition, the detection accuracy can be further improved.

  According to a first aspect of the vibration detection method of the present invention, the elastomer sensor according to any one of the first to third aspects is attached to a vibration body, and the elastomer sensor accompanying vibration of the vibration body is provided. The vibration state of the vibrating body is detected by detecting the dynamic elastic deformation of the sensor body as an impedance change of the sensor body by the detecting means.

  In the elastomer sensor having the structure according to this aspect, it is possible to detect the vibration state of the vibrating body, that is, the dynamic state change or force change with high accuracy. In particular, when elastic deformation of the elastomer sensor occurs in various directions, it is possible to detect the elastic deformation as an impedance change regardless of the deformation direction. Therefore, the detection data can be diversified as compared with conventional load sensors made of ceramic materials, and the degree of freedom in design can be improved by easing the conditions for mounting the sensor. is there.

  As is apparent from the above description, the elastomer sensor having the structure according to the present invention has a novel structure which has not been heretofore known, and can be manufactured from a material that is generally provided on the market and is easily available. . In addition, it is possible to detect an input external force or the like over a large measurement range and with good accuracy in a plurality of input directions.

  Therefore, with such a sensor, it is possible to detect static external force and dynamic external force with great flexibility and good accuracy easily and at low cost. There exists.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, liquid silicone rubber and liquid silicon gel were used as elastomers, and carbon nanotubes were mixed as conductive fillers (fine fillers) into the elastomer material to obtain a sensor molding material. The amount of carbon nanotubes mixed in this example was 5% by weight with respect to 95% by weight of the elastomer material.

As an elastomer material in this example, Shin-Etsu Chemical Co., Ltd. two-part curable silicone rubber product number: KE103 (mixed with 5% of catalyst cat-103) and Shin-Etsu Chemical Co., Ltd., one-pack type A silicon gel product number: KE1151 was mixed at a weight ratio of 1: 2, and then stirred. Carbon nanotubes mixed with the elastomer material include Shenzhen Nanotech Port Co. , LTD. Single-walled carbon nanotubes sold by, were used. The carbon nanotubes used had a diameter of 2 nm or more, tube length: 0.5 to 500 μm, purity: 90% or more, ash content: 2 wt% or less, specific surface area: 600 m ² / g or more, ratio of amorphous carbon: 3% or less.

  Then, the elastomer material mixed with the carbon nanotubes is sufficiently mixed, and the dispersibility of the carbon nanotubes in the elastomer material is made uniform, and then a rectangular block of 10 mm (width) × 10 mm (depth) × 5 mm (height) 10 mm (width) x 10 mm (depth) x 5 mm (height) by injecting an elastomer material into a molding die having a shape space inside, and curing by heating at 150 ° C. for 1 hour, followed by demolding ) To obtain a sensor main body 10 made of a block-shaped molded body (see FIG. 1). Further, when molding the sensor body 10, by injecting and molding an elastomer material in a state where a pair of upper and lower copper plates 12, 14 are set on the inner space wall surfaces facing in the height direction of the molding die, A pair of copper plates 12 and 14 applied to both end surfaces in the height direction of the sensor body 10 were fixed as electrodes. In the present embodiment, the copper plates 12 and 14 have a thin rectangular plate shape of 12 mm (width) × 12 mm (depth) × 0.2 mm (height).

  Further, power feeding lead wires 16 are connected to a pair of copper plates 12 and 14 fixed to the sensor body 10. Further, an electric circuit including the sensor main body 10 was configured by connecting an AC detection current power supply device 18 through these power supply lead wires 16. In addition, an impedance detection device 20 that measures the value of impedance in the electric circuit based on the magnitude of the alternating current or voltage is connected on the electric circuit. As a result, the detection means in the present embodiment is configured such that the pair of copper plates 12 and 14 fixed to the sensor body 10, the power supply lead wires 16 connected to the pair of copper plates 12 and 14, and the power supply lead wires 16. The detection current feeder 18 that applies an AC voltage to the copper plates 12 and 14 and the impedance detector 20 that detects the impedance of the sensor body 10 when the AC voltage is applied by the detection current feeder 18 are configured. ing.

  In the sensor body 10, carbon nanotubes as conductive fillers are mixed and dispersed in an elastomer material, so that a large number of carbon nanotubes as a whole have an inductive reactance: L and a capacitive reactance: C. In addition, in a state where an AC voltage having a frequency of 1 kHz is applied to the sensor main body 10 by the detection current power supply device 18, the sensor main body such that the value of impedance: Z detected by the impedance detection device 20 satisfies 100Ω ≦ Z ≦ 100MΩ. Ten materials, shapes, and the like are set. Preferably, the value of the detected impedance Z is 1 kΩ ≦ Z ≦ 1 MΩ in a state where a voltage having a frequency of 1 kHz is applied.

  In order to advantageously detect an impedance change corresponding to an input strain or the like using the elastomer sensor 22 having such a structure, a resistance: R and an inductive reactance: It is desirable that L and capacitive reactance: C have a complex influence. If the resistance: R is dominant and there is little influence of the inductive reactance: L and the capacitive reactance: C, the measurable input distortion region can be expanded by measuring the distortion by measuring the impedance change. Such excellent effects are not fully exhibited.

  Inductive reactance and capacitive reactance both increase and decrease according to the frequency of the applied voltage. Therefore, by appropriately setting the frequency of the applied voltage, the ratio of the resistance, the inductive reactance, and the capacitive reactance in the impedance can be adjusted appropriately.

  The frequency of the applied voltage suitable for the impedance measurement can be easily determined by performing an experiment for measuring the change in impedance with respect to the frequency change of the applied voltage in a steady state in which no external force is applied to the sensor body 10. Can be obtained. Therefore, first, an experiment was performed in which an applied voltage having an amplitude of ± 3.0 V was applied to the sensor body 10 in a steady state, and an impedance value change due to a change in the frequency of the applied voltage was measured. FIG. 2 is an example of measured data of the frequency dependence of impedance in such a steady state. In the present embodiment, as an impedance detection device 20 used for such an experiment, a dielectric test electrode jig (product number: HP-16451B) manufactured by Hewlett-Packard Company and an impedance analyzer (product number: HP-4194A) manufactured by Hewlett-Packard Company are used. )It was adopted.

  According to the experimental results shown in FIG. 2, in the frequency region (A) of less than 100 kHz, the resistance mainly affects the impedance, and the inductive reactance and the capacitive reactance substantially affect the impedance. Absent. On the other hand, in the frequency region (C) higher than 1 MHz, the inductive reactance and the capacitive reactance are dominantly acting on the impedance, and the resistance has no influence. Further, in the frequency region (B) of 100 kHz or more and 1 MHz or less, it can be confirmed that resistance, inductive reactance, and capacitive reactance are caused to act comprehensively on the impedance. Therefore, by adopting the frequency of the frequency domain (B), which is the transition area between the frequency domain (A) and the frequency domain (C), as the frequency of the applied voltage, R, L, and C are combined with respect to the impedance Z. The applied voltage adjusted to a suitable frequency that influences the frequency can be realized, and the impedance change can be advantageously measured. As is clear from FIG. 2, in the present embodiment, the R, L, and C components affect the impedance: Z in a complex manner in a frequency range of about 100 kHz to 1 MHz. In particular, according to the actual measurement result, since the frequency of about 500 kHz is the frequency of the applied voltage suitable for impedance measurement, in this example, in the following experiment, unless otherwise specified, the amplitude: ± 3.0 V, Frequency: An applied voltage of 500 kHz is applied to the sensor body 10 by the detection current power supply device 18.

  In such an applied voltage application state, the sensor body 10 of the present embodiment shows the relative ratio of the real number term of the impedance corresponding to the resistance and the imaginary number term of the impedance corresponding to the reactance which is the sum of the inductive reactance and the capacitive reactance. Phase angle at tan θ: The absolute value | θ | of θ is 1 ≦ | θ | ≦ π / 2. That is, both resistance and reactance influence the impedance. It is more desirable that the absolute value | θ | of the phase angle: θ is π / 9 ≦ θ ≦ π / 3 in tan θ indicating the relative ratio between resistance and reactance in the detected impedance.

  Next, an AC voltage having an amplitude of ± 3.0 V and a frequency of 500 kHz was applied to the sensor body 10, and the impedance value was actually measured 10 times under the same conditions. FIG. 3 shows an example of actual measurement data of such impedance values. As a comparison object, the results of 10 measurements of the resistance value by applying a voltage to a DC resistor having no L and C components under the same conditions are shown as measured data in FIG.

  According to the actual measurement data shown in FIG. 3, the actual measurement result of the impedance in the sensor main body 10 has a smaller variation in the measurement value in a plurality of measurements under substantially the same condition as compared with the actual measurement result of the DC resistance. it is obvious. That is, in the result of 10 measurements, when the impedance value is measured, the standard deviation: σ is 0.037, whereas when the DC resistance value is measured, the standard deviation: σ is It is 0.1457, and it is proved by the actual measurement data that the data closer to the average value can be stably obtained when the impedance value is measured. Further, the difference between the maximum value and the minimum value of the measured value is 0.11546 in the measurement result of measuring the impedance value, whereas it is 0.45 in the measurement result of measuring the DC resistance value. There is also a noticeable difference in the variation of the minimum value. Then, the tendency of such an actual measurement result is as follows. By measuring impedance: Z constituted by resistance: R, inductive reactance: L, and capacitive reactance: C, DC resistance: R constituted only by resistance: R It is considered that a stable measurement result can be obtained as compared with the case of detecting.

  Next, in a state where an AC voltage having an amplitude of ± 3.0 V is applied to the sensor body 10, a static compressive strain is applied to the sensor body 10 in the opposing direction of the pair of copper plates 12 and 14, An experiment was conducted to measure the impedance change accompanying the elastic deformation of the sensor body 10. FIG. 4 shows an example of actual measurement data in this experiment. In this experiment, experiments were performed on three patterns in which the frequency of the applied voltage was 1 kHz, 10 kHz, and 500 kHz, respectively, and the distortion-impedance characteristics were measured.

  In the actual measurement data shown in FIG. 4, it can be seen that there is a linear relationship between the measured impedance value and the magnitude of the compressive strain input to the sensor body 10. That is, it is clear from the graph of FIG. 4 that the impedance value measured with respect to the magnitude of the input distortion is substantially proportional. According to such strain-impedance characteristics, it is possible to accurately detect the magnitude of the static strain input from the measured impedance change.

  The region where the static strain in the sensor body and the detected impedance Z are linear is the range of strain rate (ε) in the sensor body: ε (1) to ε (2) It is desirable that | ε (1) −ε (2) | ≧ 5 (%).

  In this embodiment, at least in the deformation range where the distortion rate of the sensor body is within 5%, the input distortion and the corresponding impedance change have linearity. Further, it is desirable that the distortion and impedance change have linearity in a deformation range where the distortion rate of the sensor body is within 20%, and the distortion and impedance change are linear in a deformation range where the distortion rate of the sensor body is within 50%. It is more desirable to have

  Further, in the graph showing the actual measurement result of FIG. 4, when the frequency of the applied voltage is decreased, the impedance value for the same distortion is increased. Therefore, the sensitivity of the measurement can be easily adjusted by adjusting the frequency of the applied voltage in the frequency range (B) in FIG. 2 in accordance with the predicted magnitude of the input distortion.

  Next, in a state where an AC voltage having an amplitude of ± 3.0 V and a frequency of 500 kHz is applied to the sensor body 10, a dynamic compressive strain is applied to the sensor body 14 in the opposing direction of the pair of copper plates 12 and 14. And measured as an output voltage (mV) corresponding to an impedance change accompanying elastic deformation of the sensor body 10 (showing a value not converted to impedance). FIG. 5 shows an example of actual measurement data of impedance change with respect to such dynamic input distortion.

  In the actual measurement data shown in FIG. 5, the actual measurement value has a large degree of linear relevance, and even when the input distortion is a sinusoidal dynamic distortion, the input distortion is measured by measuring the impedance change corresponding to the input distortion. It is clear that the size of can be measured with high accuracy. That is, for example, even for dynamic strain input such as vibration of an engine as a vibrating body, high-precision sensing can be realized by measuring impedance change using the sensor body 10 of the present embodiment. It is.

  Further, as shown in FIG. 5, in this embodiment, the dynamic strain in the sensor body and the detected impedance: Z are in the range of strain rate (ε): ε (1) to It has linearity in the region of ε (2), and it is possible to suitably realize highly accurate detection within the range of the distortion rate. As is apparent from FIG. 5, in this embodiment, ε (1) is the strain rate when the strain amount is 0 μm, and ε (2) is the strain rate when the strain amount is approximately 300 μm. ing.

  Note that the amplitude of the dynamic strain input in the deformation range where the distortion rate of the sensor body 10 due to the input strain is 5% or less and the output voltage corresponding to the impedance change corresponding to the input strain have linearity. It is desirable. In addition, by appropriately preparing the material of the sensor body 10 and the like, more preferably, the amplitude of the dynamic strain input in the deformation range in which the distortion rate of the sensor body 10 due to the input strain is 20% or less and the input. The output voltage corresponding to the impedance change corresponding to the distortion has linearity, and more preferably, in the deformation range where the distortion rate of the sensor body 10 is 50% or less, The output voltage corresponding to the impedance and the impedance change corresponding to the input distortion has linearity.

  In the elastomer sensor 22 having the structure according to the present embodiment, the sensor body 10 is configured so that the impedance Z is 100Ω ≦ Z ≦ 100 MΩ when an applied voltage having a frequency of 1 kHz is applied. When the frequency of the applied voltage is appropriately set, etc., the absolute value | θ | of tan θ indicating the relative ratio of the resistance: R and reactance in impedance: Z is θ ≦ 1 || θ | / 2. As a result, it is possible to measure an input distortion or the like by a change in impedance: Z, which is comprehensively affected by resistance: R, inductive reactance: L, and capacitive reactance: C. Accurate detection can be realized stably.

  In particular, in the elastomer sensor 22 of this embodiment, R, L, and C are contained at an appropriate ratio, so that the amount of conductive filler (carbon nanotubes) mixed is relatively large, and resistance when a certain amount of strain is input. Even when a strain larger than that is input in the case of being almost zero, the impedance is changed by changing the inductive reactance and the capacitive reactance, and the strain is measured. Yes. On the other hand, even when the amount of conductive filler mixed is relatively small and no change in resistance occurs when a minute strain is input, the change in impedance is measured by the change in inductive reactance or capacitive reactance. It is.

  Furthermore, by measuring the change in impedance that includes resistance, inductive reactance, and capacitive reactance in a well-balanced manner, variations in measurement results are suppressed compared to when measuring changes in DC resistance, resulting in more accurate measurements. The result can be obtained.

  In addition, since a large number of carbon nanotubes mixed with the elastomer material have an inductive reactance and a capacitive reactance, a coiled carbon microcoil is used as a conductive filler such as carbon nanotubes mixed with the elastomer material. Measurement of a change in impedance including R, L, and C can be easily realized without employing a special conductive filler such as. Therefore, productivity can be improved and manufacturing costs can be reduced by not using special materials.

  In addition, since the sensor body 10 in the elastomer sensor 22 of the present embodiment is formed by mixing carbon nanotubes with an elastomer material, the shape and material properties can be set relatively freely, and the design shape of the processed shape can be freely set. A large degree can be obtained.

  Next, FIG. 6 shows an elastomer sensor 24 as a second embodiment of the present invention. In the following description, members and portions that are substantially the same as those in the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

  That is, the elastomer sensor 24 in this embodiment employs a sensor body 26 in which fine carbon fibers are mixed as a conductive filler with the same elastomer material as that shown in the first embodiment. . Any carbon fiber can be used as the carbon fiber, but it is preferable that the fiber diameter is 10 μm or less and the fiber length is 1 mm or less. When the carbon fiber is covered and has a large fiber diameter or a long fiber length, it may be difficult to sufficiently disperse the carbon fiber in a state of being mixed with the elastomer material. In particular, in this example, a fine carbon fiber (registered trademark: VGCF) sold by Showa Denko Co., Ltd. is adopted as the carbon fiber, the fiber diameter: 150 nm, the fiber length: 9 μm, and the resistivity: 0. .013 Ω · cm.

  7 to 9 show actual measurement data obtained by performing an actual measurement similar to that of the first embodiment using the elastomer sensor 24 as described above. According to these measured data, the elastomer sensor 24 in the present embodiment can easily select a suitable frequency for the applied voltage as in the first embodiment, and use the applied voltage at the frequency. By measuring the change of impedance: Z, static and dynamic input distortions can be advantageously measured. In short, the impedance change can be measured with high accuracy even by the sensor body 26 employing fine carbon fibers as the conductive filler mixed with the elastomer material.

  As mentioned above, although several Example of this invention was described, this is an illustration to the last, Comprising: This invention is not interpreted limitedly by the specific description in this Example.

  For example, in the first and second embodiments, carbon nanotubes and fine carbon fibers are used as the conductive filler. However, the conductive filler is not limited to these carbon nanotubes and carbon fibers. Absent. Specifically, for example, carbon black (for example, ketjen black sold by Lion Corporation) can be employed as the conductive filler. In addition, the conductive filler is not limited to carbon-based materials such as hollow carbon fibers such as carbon nanotubes, fine carbon fibers, and particulate carbon such as carbon black, but metal particles including nano metal particles , Conductive polymers, ionic compounds, and the like can also be employed as the conductive filler.

  In addition, the conductive filler does not necessarily need to be composed of one type of material, and it is possible to employ a mixture of multiple types of materials, realizing more effective conductivity and dispersibility. Can also be possible.

  In addition, as shown in the first embodiment, even when carbon nanotubes are used as the conductive filler, the diameter, tube length, shape, etc., are determined according to the specific description in the embodiment. It is not limited at all. The diameter and the tube length of the carbon nanotubes are desirably carbon nanotubes having a small diameter and a short tube length in order to obtain good dispersibility of the conductive filler in the elastomer material and good conductivity of the sensor body 10.

  In the first and second embodiments, the two-part curable silicone rubber and the one-part silicone gel are mixed and stirred so that the weight ratio is 1: 2, and the elastomer material is configured. Such an elastomer material is not limited to those described in the above-described embodiments, and any other general-purpose elastomer can be used. In addition, in order to implement | achieve the favorable dispersibility of the electroconductive filler mixed with an elastomer material, the liquid polymer with a low viscosity is employ | adopted suitably.

  Further, for example, when the elastomer sensors 22 and 24 are used for an engine mount or the like and an initial load is applied to the elastomer sensors 22 and 24, the frequency is set in a state where the initial load is applied. Impedance: Z is set to satisfy 100Ω ≦ Z ≦ 100MΩ by measurement at an applied voltage of 1 kHz.

  In addition, although not enumerated one by one, the present invention can be carried out in a mode to which various changes, modifications, improvements and the like are added based on the knowledge of those skilled in the art. It goes without saying that all are included in the scope of the present invention without departing from the spirit of the present invention.

Explanatory drawing which shows the state which set the elastomer sensor as 1st Example of this invention to the experiment apparatus. It is a graph which shows the experimental result which measured the change of the impedance with respect to the frequency change of the applied voltage of the elastomer sensor as an Example with the experimental apparatus shown by FIG. It is a table | surface which shows the experimental result which measured the output of the elastomer sensor as an Example with the experimental apparatus shown by FIG. It is a graph which shows the distortion-impedance characteristic according to the frequency of the applied voltage at the time of the static compressive force effect | action of the elastomer sensor as an Example by the experimental apparatus shown by FIG. It is a graph which shows the distortion-impedance characteristic at the time of the dynamic compressive force effect | action of the elastomer sensor as an Example by the experimental apparatus shown by FIG. Explanatory drawing which shows the state which set the elastomer sensor as 2nd Example of this invention to the experiment apparatus. It is a graph which shows the experimental result which measured the change of the impedance with respect to the frequency change of the applied voltage of the elastomer sensor as an Example with the experimental apparatus shown by FIG. It is a graph which shows the distortion-impedance characteristic according to the frequency of the applied voltage at the time of the static compressive force effect | action of the elastomer sensor as an Example by the experimental apparatus shown by FIG. It is a graph which shows the distortion-impedance characteristic at the time of the dynamic compressive force effect | action of the elastomer sensor as an Example with the experimental apparatus shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sensor main body 12 Copper plate 14 Copper plate 18 Feeding lead 20 Detecting current feeding device 22 Impedance detecting device 24 Elastomer sensor

Claims (4)

In an elastomer sensor comprising a sensor body in which an elastomer is mixed with a conductive filler, and a detection electrode for detecting the impedance of the sensor body,
A granular or linear fine filler is employed as the conductive filler in the sensor body, and impedance detected when an AC voltage for detection having a frequency of 1 kHz is applied to the detection electrode: Z is 100Ω ≦ Z ≦ The phase angle between the AC voltage for detection and the detected impedance under the action state of the load to be detected: θ is 1 degree ≦ | θ | ≦ 90 degrees. Elastomer sensor.   The elastomer sensor according to claim 1, wherein the detection electrode is configured by a plurality of electrodes fixed to different positions in the sensor body.   The region where the dynamic strain in the sensor body and the detected impedance: Z are linear covers the range of strain rate (ε) in the sensor body: ε (1) to ε (2). The elastomer sensor according to claim 1, wherein | ε (1) −ε (2) | ≧ 5 (%). The elastomer sensor according to any one of claims 1 to 3 is attached to a vibration body, and dynamic elastic deformation of the sensor body of the elastomer sensor due to vibration of the vibration body is caused by impedance of the sensor body. A vibration detection method characterized by detecting a vibration state of the vibrating body by detecting the change by the detection means.

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