JP2013142564A - Pressure-sensitive sensor cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive sensor cable that is such sensitive to the weight of a load that can sense pressure even when a slight weight of a load applies thereto.SOLUTION: A pressure-sensitive sensor cable 1 is formed by laminating an insulation intervention 3 made of an insulating body and a conductive layer 4 in this order around a linear inner conductive body 2, and the insulation intervention 3 forms an air gap between the inner conductive body 2 and the conductive layer 4. The conductive layer 4 is formed of a metal conductive layer 42. The inner conductive body 2 and the conductive layer 4 are kept in a noncontact state by the air gap when external pressure does not apply thereto, and the inner conductive body 2 and the conductive layer 4 are brought into contact with each other to allow electrical connection when the external pressure applies thereto.

Description

  The present invention relates to a pressure-sensitive sensor cable including a cable-shaped pressure sensor.

  A contact-type pressure-sensitive sensor formed in the shape of a cable is used as a pressure-sensitive sensor cable (hereinafter sometimes simply referred to as a sensor cable) in automobiles, electrical equipment, electronic devices, and the like. A conventional sensor cable has, for example, a coaxial cable shape, and has a known structure in which a cylindrical conductive rubber layer, a pressure sensitive body, a sensor electrode, and an insulating sheath are sequentially laminated on the outer periphery of a core wire (for example, Patent Document 1).

  In the sensor cable described in Patent Document 1, the conductive rubber layer is formed of a rubber material containing carbon. The pressure sensitive body of the sensor cable is formed of a rubber material (nickel-containing pressure sensitive body) in which nickel powder is dispersed as a magnetic material. The conventional sensor cable detects pressure by utilizing the fact that the resistance value changes when pressure is applied to the cable from the outside and the pressure sensitive body is deformed.

JP 2006-300559 A

  However, since the conventional sensor cable is a pressure-sensitive body-containing type and uses a change in resistance value due to pressure, there is a problem that it is difficult to read the change in resistance value with a minute pressure.

  An object of the present invention is to overcome the drawbacks of the prior art described above, and is a pressure-sensitive sensor cable that has high sensitivity to load, can sense pressure even with a small load, and has good sensitivity to pressure. Is to provide.

In order to solve the above problems, the pressure-sensitive sensor cable of the present invention is
A pressure-sensitive sensor cable in which an insulating interposition and a conductive layer made of an insulator are sequentially laminated around a linear inner conductor, and a gap is formed between the inner conductor and the conductive layer by the insulating interposition. ,
The conductive layer has a metal conductive layer,
When no pressure is applied to the pressure sensor cable from the outside, the inner conductor and the conductive layer are held in a non-contact state by the gap, and when the pressure is applied, the inner conductor and the conductive layer are in contact and can conduct. The gist is that it is formed.

  In the pressure-sensitive sensor cable of the present invention, it is preferable that the metal conductive layer includes one or more selected from the group consisting of a metal braid, a metal wire, and a metal foil.

  In the pressure-sensitive sensor cable of the present invention, it is preferable that the insulating inclusion includes one or more selected from the group consisting of paper, a plastic film, an insulated wire, and rubber.

  In the pressure-sensitive sensor cable of the present invention, it is preferable that the conductive layer has an insulating rubber layer formed outside the metal conductive layer.

  In the pressure-sensitive sensor cable of the present invention, the insulating rubber layer is selected from the group consisting of silicone rubber, acrylic rubber, ethylene-propylene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, epichlorohydrin rubber, and isoprene rubber. It is preferable that 1 type, or 2 or more types are included.

  In the pressure-sensitive sensor cable of the present invention, an insulating coating layer can be formed on the outer periphery of the conductive layer.

  In the pressure-sensitive sensor cable according to the present invention, an insulating interposition and a conductive layer made of an insulator are sequentially laminated around a linear inner conductor, and a gap is formed between the inner conductor and the conductive layer by the insulating interposition. The conductive layer has a metal conductive layer, and the inner conductor and the conductive layer are held in a non-contact state by the gap when no pressure is applied to the pressure-sensitive sensor cable from the outside, and pressure is applied. In this state, the inner conductor and the conductive layer are in contact with each other and are formed to be conductive. Therefore, compared to a sensor cable that uses a change in resistance value due to pressure using a conventional pressure sensitive body, the sensitivity to load is high. The pressure can be sensed even with a small load, and the sensitivity to pressure is good.

FIG. 1 is a perspective view showing an example of a pressure-sensitive sensor cable of the present invention. 2 is a cross-sectional view taken along the line AA in FIG. 3 is a longitudinal sectional view taken along line BB in FIG. 4 is a cross-sectional view showing a state in which pressure is applied to the pressure-sensitive sensor cable of FIG. FIG. 5 is a cross-sectional view showing another embodiment of the pressure-sensitive sensor cable of the present invention.

  The present invention will be described in detail with reference to examples. 1 is a perspective view showing an example of a pressure-sensitive sensor cable according to the present invention, with its end peeled, FIG. 2 is a cross-sectional view in the direction of the line AA in FIG. 1, and FIG. 1 is a longitudinal sectional view taken along line BB in FIG. FIG. 2 shows a state in which the end of the pressure sensor cable is not peeled. A pressure-sensitive sensor cable 1 (hereinafter also abbreviated as a sensor cable) shown in FIGS. 1 to 3 has an insulating interposition 3 made of an insulator and a conductive layer 4 having conductivity around a linear inner conductor 2. Are sequentially laminated, and the outer periphery of the conductive layer 4 is covered with an insulating coating layer 5.

  The insulating interposition 3 is spirally wound so that the adjacent interposing insulating interpositions 3 have a predetermined interval. As shown in FIG. 2 and FIG. 3, in the sensor cable 1, a portion between the insulating intermediates 3 is formed as a gap 6 between the inner conductor 2 and the conductive layer 4.

  The conductive layer 4 is formed so as to cover the entire outer periphery of the insulating intermediate 3. The insulating coating layer 5 is also formed so as to cover the entire outer periphery of the conductive layer 4. Note that the inner conductor 2 and the conductive layer 4 are exposed to the outside so that the end portion of the sensor cable 1 can output signals from the inner conductor 2 and the conductive layer 4 to the outside, and can be electrically connected. Is formed.

  In a state where no pressure is applied from the outside, the sensor cable 1 is brought into a non-contact state due to the intervening insulation 3 between the inner conductor 2 and the conductive layer 4 as shown in FIGS. Yes.

  4 is a cross-sectional view showing a state in which the sensor cable of FIG. 3 is pressed from the outside and pressure P is applied. As shown in FIG. 4, when the outside of the sensor cable 1 is pushed and pressure P is applied from above the insulating coating layer 5, the conductive layer 4 in the space 6 formed by the insulating interposition 3 is deformed by the pressure. As a result, the inner conductor 2 and the conductive layer 4 come into contact with each other and become conductive.

  The sensor cable 1 includes an inner conductor 2 as a core electrode and a conductive layer 4 as a sensor electrode. The end portions of the inner conductor 2 and the conductive layer 4 of the sensor cable 1 are electrically connected to a current detection element, a control circuit, and the like. In the sensor cable 1, a current change occurs when the inner conductor 2 and the conductive layer 4 are brought into contact with each other, so that the pressure can be sensed by detecting the current change with the detection element.

  Conventionally, this type of sensor cable is provided with a pressure-sensitive body layer containing a pressure-sensitive body, and by measuring a change in current value due to a change in resistance value when the pressure-sensitive body layer receives pressure. The pressure change was detected. On the other hand, the sensor cable of the present invention detects the pressure by detecting that the inner conductor 2 and the conductive layer 4 are in contact and electrically connected. By detecting electrical continuity, it was possible to obtain a sensor cable with higher sensitivity compared to the case of detecting pressure using the change in resistance value of the pressure sensitive body.

  For the inner conductor 2, an inner conductor of a normal electric wire or the like can be used. As the inner conductor 2, for example, copper, copper alloy, aluminum or the like can be used. The thickness of the inner conductor 2 can be appropriately selected according to the thickness of the pressure-sensitive sensor cable 1 and the like, and is not particularly limited. For example, a range of 0.1 to 2.0 mm is preferable.

  As the insulating interposition 3, for example, insulating paper, plastic film, fibers such as aramid fibers, insulating wires, insulating materials such as insulating rubber are used. The insulation interposition 3 of the pressure-sensitive sensor cable 1 shown in FIG. 1 has a spirally wound shape, but the insulation interposition 3 is not limited to this shape. The insulating interposition 3 is interposed between the inner conductor 2 and the conductive layer 4, and holds a gap formed between the inner conductor 2 and the conductive layer 4 when no pressure is applied to the sensor cable 1. Any shape that can insulate and hold the two may be used.

  For the insulating interposition 3, for example, rubber formed in a mesh shape can be used as a structure other than the spiral shape.

  The conductive layer 4 is composed of a conductor made of the metal conductive layer 42. The metal conductive layer 42 includes a metal braid, a metal wire, a metal foil, and the like, and is made of a material that can be deformed when pressure is applied to the sensor cable. The fact that the deformation is possible means that it is possible to make contact with the lower inner conductor 2 by using the gap formed by the presence of the insulating interposition 3.

  Specific examples of the metal conductive layer 42 include a braid made of a tin-plated copper wire, a copper wire, a silver wire, a gold wire, a copper foil, and a gold foil. In the case of a metal wire, for example, the metal conductive layer can be formed by spirally winding the outer periphery of an insulating medium. Further, the metal wire may be wound twice in a spiral. In that case, you may wind so that it may cross | intersect, and you may wind so that it may become spiral in the same direction so that it may not cross | intersect.

  Since the conductive layer 4 includes the metal conductive layer 42, the resistance of the conductive layer 4 is sufficiently low, and electrical connection between the conductive layer 4 and the inner conductor 2 can be reliably performed. As a result, the sensor cable can exhibit good sensitivity (degree of decrease in electrical resistance value with respect to load).

  FIG. 5 is a cross-sectional view showing another aspect of the sensor cable of the present invention. As shown in FIG. 5, in the sensor cable 1, the conductive layer 4 is preferably composed of a metal conductive layer 42 and an insulating rubber layer 41 formed outside the metal conductive layer 42.

  The insulating rubber layer 41 supports the entire metal conductive layer 42 and easily deforms against pressure due to rubber elasticity, so that the sensitivity of the sensor cable can be increased. The rubber component of the insulating rubber layer is not particularly limited and can be used. The conductive layer 4 is easily deformed by the rubber component and comes into contact with the inner conductor 2 when the sensor cable 1 receives a weak pressure with a slight load. It is easy to read the current change due to the contact between the inner conductor 2 and the conductive layer, and the sensor cable 1 with high sensitivity can be obtained. In addition, when the pressure is removed, the insulating rubber layer 41 immediately returns to its original shape due to rubber elasticity. Since the metal conductive layer 41 is integrated with the insulating rubber layer 42, when the pressure on the cable is removed, the metal conductive layer 41 also immediately returns to its original shape and can be disconnected from the inner conductor 2.

  The rubber component of the insulating rubber layer 41 may be either a crosslinked rubber or a non-crosslinked rubber. Examples of the rubber component of the conductive layer 4 include silicone rubber, acrylic rubber, ethylene-propylene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, epichlorohydrin rubber, and isoprene rubber. The rubber may be used alone or in combination of two or more. When the above rubber is used for the rubber component, it is excellent in flexibility and heat resistance, has high sensitivity to the load, and can easily contact the inner conductor 2 and the conductive layer 4 with a small load.

  As the silicone rubber, either a millable type (heat-crosslinking type) that becomes an elastic body by kneading a cross-linking agent and then heat-crosslinking, or a liquid rubber type that is liquid before cross-linking may be used. The liquid rubber type silicone rubber includes a room temperature crosslinking type (RTV) capable of crosslinking near room temperature and a low temperature crosslinking type (LTV) capable of crosslinking when heated near 100 ° C. after mixing.

  The millable silicone rubber has an advantage that it is easy to mix during kneading and has excellent workability because the crosslinking temperature is relatively high at 180 ° C. or higher and has good stability. On the other hand, since the liquid rubber type silicone rubber has a low crosslinking temperature of about 120 ° C., it is necessary to suppress heat generation at the time of kneading with low stability, and there is a risk that the temperature management and the like may become troublesome. is there. Millable silicone rubber is a commercially available rubber compound that contains linear organopolysiloxane as the main raw material (raw rubber) and contains reinforcing filler, filler, dispersion accelerator, and other additives. May be.

  The cross-linked acrylic rubber is cross-linked by forming a composition containing uncross-linked acrylic rubber and a conductive filler into a predetermined shape and then heating to cross-link the acrylic rubber. Acrylic rubber has an acrylic ester as a main component.

  Examples of the acrylic rubber include those having ethyl acrylate as a main component and copolymerized with other monomers such as butyl acrylate and acrylonitrile and a comonomer for crosslinking. Examples of the comonomer for crosslinking the acrylic rubber include halogen-containing compounds such as 2-chloroethyl vinyl ether, epoxy compounds such as glycidyl acrylate and allyl glycidyl ether, and diene compounds such as ethylidene norbornene. Commercially available acrylic rubber may be used.

  The crosslinked ethylene-propylene rubber is obtained by crosslinking a composition comprising a rubber composed of uncrosslinked ethylene, propylene, diene or the like and a conductive filler by heating or the like. Examples of the rubber made of the above copolymer include ethylene-propylene copolymer (EPM) and ethylene-propylene-diene copolymer (EPDM). Examples of the diene include ethylidene norbornene (ENB) and dicyclopentadiene (DCP).

  The crosslinked styrene-butadiene rubber is formed by molding a composition containing styrene-butadiene rubber (SBR) obtained by polymerizing styrene and butadiene by emulsion polymerization or solution polymerization into a predetermined shape, and then heating the styrene. -Cross-linked by subjecting butadiene rubber to cross-linking treatment.

  The crosslinked acrylonitrile-butadiene rubber is crosslinked by subjecting a copolymer rubber (NBR) of acrylonitrile and butadiene to a crosslinking treatment by heating or the like. Acrylic nitrile-butadiene copolymer rubber has a reactive end group by copolymerizing with acrylic acid, methacrylic acid, acrylic ester, etc. as the third monomer, and both ends have a carboxyl group, a mercapto group, a hydroxyl group, etc. The telechelic type etc. which became can be used.

  The crosslinked chloroprene rubber is crosslinked by subjecting chloroprene rubber (CR) to a crosslinking treatment by heating or the like. The chloroprene rubber is obtained by polymerizing chloroprene using acetylene as a raw material or chloroprene using butadiene as a raw material by emulsion polymerization or the like.

  The crosslinked epichlorohydrin rubber is crosslinked by subjecting the epichlorohydrin rubber to a crosslinking treatment by heating or the like. Epichlorohydrin rubber is an epichlorohydrin homopolymer (CO), a copolymer of epichlorohydrin and ethylene oxide (ECO), a copolymer of epichlorohydrin and allyl glycidyl ether, a terpolymer of epichlorohydrin, ethylene oxide, and allyl glycidyl ether (GECO). ) Etc.

  The crosslinked isoprene rubber is crosslinked by subjecting polyisoprene (isoprene rubber: IR) to a crosslinking treatment by heating or the like. The isoprene rubber is obtained by solution polymerization of isoprene using a Ziegler catalyst or a lithium catalyst.

  In addition to the rubber component, the insulating rubber layer 41 may contain other additives. For example, a crosslinking agent is mentioned as another additive. The crosslinking agent is not particularly limited. For example, dihexyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) Examples include dialkyl peroxides such as hexane, and peroxyketals such as n-butyl 4,4-di (t-butyl peroxide) valerate.

  The insulating rubber layer 41 can be manufactured, for example, as follows. First, a rubber composition containing an uncrosslinked rubber component, a crosslinking agent and the like is prepared by kneading. Next, the prepared rubber composition is extruded into a predetermined shape on the outer periphery of the metal conductive layer 42 to form an insulating rubber layer 41. Furthermore, the insulating coating layer 5 is formed around the conductive layer 4 to obtain the sensor cable 1. Next, the uncrosslinked rubber of the insulating rubber layer 41 is crosslinked by a crosslinking means such as heating. Thereby, an insulating rubber layer 41 made of a crosslinked rubber is obtained.

  The method for kneading the rubber composition is not particularly limited. For example, the rubber composition is uniformly melt-kneaded with a conventional kneader such as a Banbury mixer, a pressure kneader, a kneading extruder, a twin-screw kneading extruder, or a roll. Can be dispersed.

  The insulating coating layer 5 is not particularly limited as long as it is formed of an insulator capable of covering the conductive layer 4. Examples of the insulating coating layer 5 include silicone rubber, acrylic rubber, ethylene-propylene rubber, and the like. The thickness of the insulating coating layer 5 can be appropriately selected as long as the insulating property with respect to the conductive layer 4 can be maintained and flexibility that can be deformed with respect to the pressure of the sensor cable 1 is not impaired. The insulating coating layer 5 is not particularly limited to rubber as long as it has flexibility.

  An example of a method for manufacturing the sensor cable shown in FIG. The insulating interposition 3 is wound around the inner conductor 2 in a spiral manner with a gap in the longitudinal direction. Further, the conductive layer 4 is formed by providing a metal conductive layer 42 around the insulating intermediate 3. The conductive layer 4 is provided around the insulating intermediate 3 so as not to directly contact the inner conductor 2 and to form a gap. Furthermore, the insulating rubber layer 41 or the insulating coating layer 5 is formed around the metal conductive layer 4 to obtain the sensor cable 1.

  The thickness, length, and the like of the sensor cable 1 of the present invention can be appropriately selected according to the application.

  The sensor cable according to the present invention can be used as a touch sensor for automobiles and electronic / electrical devices. It is particularly suitable for applications that require heat resistance and sensor sensitivity. As a specific application, it can be suitably used as a pressure-sensitive sensor for detecting a foreign object sandwiched between a door panel of an automobile door and a vehicle body.

  Examples of the present invention and comparative examples are shown below.

Examples 1-6
After winding the various conductors (insulated wire, paper, PET (polyethylene terephthalate) tape, etc.) shown in Table 1 with an outer diameter or thickness of 200 μm around the inner conductor made of copper wire of 0.8 mmφ in a spiral shape Then, various metal conductors having a thickness of 200 μm shown in Table 1 were formed on the outer side, and a conductive layer was formed on the outer side by covering the insulating rubber with a thickness of 200 μm to obtain a sensor cable having an outer diameter of 2 mmφ. . About the obtained sensor cable, the sensitivity evaluation as a pressure-sensitive sensor was performed. The results of sensitivity evaluation are shown in Table 1. The details and sensitivity evaluation methods of the inner conductor, insulating interposition, metal conductive layer, and insulating rubber used in the examples are as follows.

[Inner conductor]
A 0.8 mmφ copper wire was used.
[Insulation]
A space was provided around the inner conductor so as to have a thickness of 200 μm, and it was spirally wound. The interval was set to about 0.5 to 1.0 mm.
Insulated wire: An enameled wire (wire diameter: 200 μm) made by baking a polyamideimide resin having a thickness of 50 μm.
Paper: Insulating paper having a thickness of 200 μm and a width of 500 μm.
PET tape: Polyethylene terephthalate (PET) tape having a thickness of 200 μm and a width of 500 μm.
PET-laminated paper: A paper having a thickness of 100 μm and a PET having a thickness of 100 μm bonded together by lamination.
PET-coated paper: 100 μm thick paper coated with PET dissolved in a solvent and dried to a thickness of 100 μm.
(Metal conductor layer)
Copper wire: A copper wire having an outer diameter of 200 μm wound in a cross-winding manner with respect to insulation.
Silver wire: A silver wire having an outer diameter of 200 μm wound in a cross-winding manner around an insulating medium.
Copper foil: A copper foil having a thickness of 200 μm and a width of 500 μm wound in a cross-winding manner with respect to insulation.
Gold wire: A gold wire having an outer diameter of 200 μm wound in a cross-winding manner around an insulating medium.
-Braid: 25 copper wires with an outer diameter of 0.1 mm are knitted side by side.
[Insulating rubber layer]
・ Silicone rubber: Asahi Kasei Wacker Silicone Co., Ltd., trade name “R401-30” 100 parts by mass of DCP (dicumyl peroxide) as a cross-linking agent 3 parts by mass EP rubber (ethylene propylene rubber): JSR A material obtained by adding 1 part by mass of DCP as a cross-linking agent to 100 parts by mass of a trade name “EP11”. Acrylic rubber: A material obtained by adding 3 parts by mass of DCP as a cross-linking agent to 100 parts by mass of a trade name “Baymac G”.

[Sensitivity evaluation method]
For sensitivity evaluation, a pressure-sensitive sensor cable having a length of 1 m was used, a load was applied while pressing the center portion, a change in resistance value with respect to the load was measured, and a load with a resistance value of 0.1 kΩ or less was measured.

Comparative Examples 1-6
After a pressure sensitive element having the composition shown in Table 2 is spirally wound with a thickness of 200 μm around an inner conductor made of a 0.8 mmφ copper wire, a sensor electrode (braid) having a thickness of 200 μm is covered on the outside. The insulation coating layer shown in Table 2 was coated on the outside to a thickness of 200 μm to obtain pressure-sensitive sensor cables of Comparative Examples 1 to 6 having an outer diameter of 2 mmφ. The sensitivity of the obtained pressure-sensitive sensor cable was evaluated in the same manner as in the example. The test results are shown in Table 2. Details of the rubber component, the pressure-sensitive filler, and the jacket used in the pressure-sensitive bodies of Comparative Examples 1 to 6 are as follows.

[Rubber component of pressure-sensitive body]
Silicone rubber: Shin-Etsu Chemical Co., Ltd., trade name “KE-931-U”
・ EP rubber (ethylene propylene rubber): manufactured by Sumitomo Chemical Co., Ltd., trade name “301”
・ Fluorine rubber: Product name “G902” manufactured by Daikin Industries, Ltd.
[Pressure-sensitive filler of pressure-sensitive body]
・ Nickel: Seishin Enterprise Co., Ltd., trade name “T-255”
・ Carbon: Tokai Carbon Co., Ltd., trade name “SEAST9”
-Ferrite: manufactured by Toda Kogyo Co., Ltd., trade name "GP-500"
[Rubber of jacket]
Silicone rubber: Shin-Etsu Chemical Co., Ltd., trade name “KE-575-U”
・ Acrylic rubber: Product name “4200P”, manufactured by Denki Kagaku Kogyo Co., Ltd.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Pressure-sensitive sensor cable 2 Inner conductor 3 Insulation interposition 4 Conductive layer 41 Insulating rubber layer 42 Metal conductive layer 5 Insulating coating layer

Claims (6)

A pressure-sensitive sensor cable in which an insulating interposition and a conductive layer made of an insulator are sequentially laminated around a linear inner conductor, and a gap is formed between the inner conductor and the conductive layer by the insulating interposition. ,
The conductive layer has a metal conductive layer,
When no pressure is applied to the pressure sensor cable from the outside, the inner conductor and the conductive layer are held in a non-contact state by the gap, and when the pressure is applied, the inner conductor and the conductive layer are in contact and can conduct. A pressure-sensitive sensor cable characterized by being formed into   The pressure-sensitive sensor cable according to claim 1, wherein the metal conductive layer includes one or more selected from the group consisting of a metal braid, a metal wire, and a metal foil.   The pressure-sensitive sensor cable according to claim 1, wherein the insulating medium includes one or more selected from the group consisting of paper, plastic film, insulated wire, and rubber.   2. The pressure-sensitive sensor cable according to claim 1, wherein the conductive layer has an insulating rubber layer formed outside the metal conductive layer.   The insulating rubber layer includes one or more selected from the group consisting of silicone rubber, acrylic rubber, ethylene-propylene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, epichlorohydrin rubber, and isoprene rubber. The pressure-sensitive sensor cable according to claim 4.   The pressure-sensitive sensor cable according to claim 1, wherein an insulating coating layer is formed on an outer periphery of the conductive layer.

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