JP2017021890A - Pressure-sensitive sensor and method of manufacturing pressure-sensitive sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive sensor that can secure restitutive force for separating electrode wires from each other while suppressing increase in size of the pressure-sensitive sensor, and a method of manufacturing the same.SOLUTION: A pressure sensitive sensor 1A includes a hollow tubular member 10 having elasticity and insulating property, a plurality of electrode wires 20 which are spirally held apart from one other inside the tubular member 10, and inclusions 30 that are spirally held inside the tubular member 10, interposed between the plurality of electrode wires 20 and formed of linear elastic material. A method of manufacturing the pressure-sensitive sensor 1A comprises a winding step of spirally winding the plurality of electrode wires 20 and the plurality of inclusions 30 around a linear spacer 5, and an extrusion step of extruding a material around the electrode wires 20 and the inclusions 30 wound around the spacer 5 to form the tubular member 10, and a pull-out step of pulling out the spacer 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure-sensitive sensor that includes a plurality of electrode wires held inside a hollow tubular member and performs a switching function when the electrode wires come into contact with each other by external pressure, and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, pressure-sensitive sensors that perform a switching function when electrode wires are brought into contact with each other by external pressure have been used in a vehicle slide door or the like (for example, see Patent Document 1).

  The pressure-sensitive sensor described in Patent Document 1 includes an elastic insulator as a tubular member having a hollow portion, and a plurality of electrode wires arranged so as not to contact each other with the inner peripheral surface of the hollow portion of the elastic insulator. It has. This pressure sensor has a plurality of electrode wires along the outer peripheral surface of the spacer formed in the same shape as the hollow portion, and extrudes a rubber material to the outer periphery of the spacer and the plurality of electrode wires, and then molds an elastic insulator. It is formed by removing the spacer.

JP-A-10-281906

  When the elasticity of an elastic insulator made of rubber changes due to aging or the like, the electrode wires may come into contact with each other even with a smaller pressure compared to the beginning of use. That is, the restoring force of the elastic insulator for keeping the electrode wires apart from each other when no pressure is applied is reduced, and the characteristics of the pressure sensitive sensor are changed. Further, if the thickness of the elastic insulator is increased, this restoring force can be maintained, but in this case, the pressure-sensitive sensor becomes larger (larger diameter).

  Then, this invention aims at providing the pressure-sensitive sensor which can ensure the restoring force which separates electrode wires, and the pressure-sensitive sensor manufacturing method, suppressing the enlargement of a pressure-sensitive sensor. .

  In order to solve the above-mentioned problems, the present invention provides a hollow tubular member having elasticity and insulation, a plurality of electrode wires that are spaced apart from each other inside the tubular member, and spirally held, and the tubular member. A plurality of insulating inclusions spirally held inside the member and interposed between the plurality of electrode wires, wherein the inclusions are formed of a linear elastic body. .

  The present invention is also directed to a method for manufacturing the above-described pressure-sensitive sensor for solving the above-described problems, in which a plurality of the electrode wires and the inclusions are spirally wound around a linear spacer. And a step of forming a tubular member by extruding a material around the electrode wire and the inclusion wound around the spacer, and a step of pulling out the spacer.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to ensure the restoring force which spaces apart electrode wires, suppressing the enlargement of a pressure sensor.

It is sectional drawing which shows the pressure sensor which concerns on the 1st Embodiment of this invention, (a) is the state which has not received the pressure from the outside, (b) is the state which received the pressure from the outside, Each is shown. It is a perspective sectional view showing a tubular member used as an envelope of a pressure-sensitive sensor with a virtual line (two-dot chain line), and showing the inside. It is a figure which shows the structural example of the electric circuit for detecting this when a pressure acts on a pressure-sensitive sensor from the outside. It is a perspective view which shows the spacer after a winding process, the several electrode wire wound around the spacer, and several inclusions. It is sectional drawing which shows the pressure sensor which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of the electric circuit for detecting this when a pressure acts on a pressure-sensitive sensor from the outside.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In addition, although embodiment shown below is shown as a suitable specific example in implementing this invention, although there are some parts which have illustrated various technical matters that are technically preferable. The technical scope of the present invention is not limited to this specific embodiment.

  FIG. 1 is a cross-sectional view showing a pressure-sensitive sensor according to a first embodiment of the present invention, in which (a) shows a state where no pressure is applied from the outside, and (b) shows a pressure received from the outside. Each state is shown. FIG. 2 is a perspective cross-sectional view showing the inside of the tubular member serving as the outer cover of the pressure-sensitive sensor by phantom lines (two-dot chain lines).

(Configuration of pressure sensor)
This pressure-sensitive sensor 1A includes a hollow tubular member 10 having elasticity and insulating properties, and a plurality (two in this embodiment) of electrode wires 20 that are spirally held inside the tubular member 10 and spaced apart from each other. And a plurality (four in this embodiment) of insulating inclusions 30 that are spirally held inside the tubular member 10 and are interposed between the plurality of electrode wires 20. The tubular member 10 has a circular cross section.

  Each of the plurality of electrode wires 20 includes a plurality of metal wires 200 and a conductive coating layer 201 having conductivity that collectively covers the plurality of metal wires 200 and has a circular cross section. The diameters of the plurality of electrode wires 20 are the same. The plurality of metal wires 200 are made of a highly conductive metal such as copper and are twisted together.

  The conductive coating layer 201 is made of, for example, a mixture in which a conductive filler such as carbon black is blended with rubber or elastic plastic. The cross-sectional area of the conductive coating layer 201 is preferably at least twice the cross-sectional area of the metal wire 200, whereby sufficient elasticity is given to the electrode wire 20 and the holding by the tubular member 10 is appropriately performed. Made.

The inclusion 30 is made of a linear elastic body. In the present embodiment, the inclusion 30 is a hollow cylindrical tube, and a space 300 is formed at the center thereof. The diameter (outer diameter) of the inclusion 30 is not less than the diameter of the electrode wire 20. In the present embodiment, the diameter of the inclusion 30 is formed larger than the diameter of the electrode wire 20, but the diameter of the inclusion 30 may be equal to the diameter of the electrode wire 20. That is, as shown in FIG. 1A, when the diameter of the electrode wire 20 is D ₁ and the diameter (outer diameter) of the inclusion 30 is D ₂ , the pressure sensitivity is such that the inequality D ₂ ≧ D ₁ is satisfied. A sensor 1A is configured. In the present embodiment, since the diameter of the inclusion 30 is larger than the diameter of the electrode wire 20, the thickness of the tubular member 10 in the radial direction around the central axis C of the pressure sensor 1 </ b> A is The outer side is thinner than the outer side of the electrode wire 20.

  The plurality of inclusions 30 have the same inner diameter and outer diameter. The inclusion 30 is not limited to a hollow cylindrical tube, and for example, a sponge-like linear body may be used.

  Hereinafter, when it is necessary to distinguish and explain each of the plurality of electrode lines 20, each of the plurality of electrode lines 20 is referred to as a first electrode line 21 and a second electrode line 22. Moreover, when it is necessary to distinguish and explain each of the plurality of inclusions 30, each of the plurality of inclusions 30 is referred to as first to fourth inclusions 31 to 34.

  The first electrode line 21 and the second electrode line 22 face each other across the central axis C of the pressure sensor 1A. In the present embodiment, when the first electrode line 21 and the second electrode line 22 are viewed side by side as shown in FIG. 1A, the first and second electrode lines 21 and 22 The first and second inclusions 31 and 32 are disposed adjacent to each other on the right side, and the third and fourth inclusions 33 and 34 are adjacent to each other on the left side of the first and second electrode lines 21 and 22. Are arranged. That is, in the present embodiment, the inclusion set 3a including the first and second inclusions 31 and 32 and the inclusion set 3b including the third and fourth inclusions 33 and 34 are the first It is arranged between the electrode line 21 and the second electrode line 22.

  In the present embodiment, as described above, the inclusion set 3a is composed of two inclusions 30 (first and second inclusions 31 and 32), and the inclusion set 3b is also composed of two inclusions. (Three and fourth inclusions 33 and 34), but is not limited to this. For example, the inclusion sets 3a and 3b may be configured by three or more inclusions 30.

  The tubular member 10 is formed by extruding a rubber material around the outer periphery of the plurality of electrode wires 20 and the plurality of inclusions 30. As this rubber material, for example, ethylene propylene rubber excellent in water resistance, chemical resistance, weather resistance, and cold resistance can be suitably used. A space 100 is formed at the center of the tubular member 10. The space 100 at the center of the tubular member 10 and the space 300 at the center of the inclusion 30 are open to the atmosphere at at least one end in the longitudinal direction of the pressure sensor 1A.

  As a material for the inclusions 30, it is desirable to use the same kind of rubber material as that of the tubular member 10. This is because the inclusion 30 is formed of the same kind of rubber material as that of the tubular member 10 so that the tubular member 10 and the plurality of inclusions 30 are in close contact with each other with high strength. In the present embodiment, EPDM is used as the material for the tubular member 10 and the inclusion 30.

(Electric circuit including pressure sensor)
FIG. 3 is a diagram showing a configuration example of an electric circuit 4A for detecting when pressure is applied to the pressure sensor 1A from the outside. The electric circuit 4A includes a pressure-sensitive sensor 1A, a DC power supply 41, an ammeter 42, and first and second resistors 43 and 44.

  The DC power supply 41, the ammeter 42, and the first resistor 43 are arranged between the metal wire 200 of the first electrode wire 21 and the metal wire 200 of the second electrode wire 22 at one end of the pressure sensor 1A. Connected in series. The second resistor 44 is connected between the metal wire 200 of the first electrode wire 21 and the metal wire 200 of the second electrode wire 22 at the other end of the pressure sensor 1A.

  When no pressure is applied to the pressure sensor 1A from the outside, the first electrode wire 21 and the second electrode wire 22 are separated by the elasticity of the tubular member 10 and the first to fourth inclusions 31 to 34. The ammeter 42 measures a current having a value obtained by dividing the power supply voltage of the DC power supply 41 by the resistance value of the combined resistance of the first resistor 43 and the second resistor 44. On the other hand, when pressure is applied to the pressure sensor 1A from the outside and the first electrode line 21 and the second electrode line 22 contact (short-circuit) at least partially, the ammeter 42 supplies the power supply voltage of the DC power supply 41. Is divided by the resistance value of the first resistor 43 to measure the current. That is, if the resistance value of the first resistor 43 and the resistance value of the second resistor 44 are the same, when a pressure is applied to the pressure sensor 1A from the outside, a current value approximately twice as large is obtained. Measured by ammeter 42. Therefore, the presence or absence of contact between the first electrode wire 21 and the second electrode wire 22 can be determined based on the measurement value of the ammeter 42.

  The ammeter 42 only needs to be able to determine whether or not the current flowing through the electric circuit 4A is equal to or greater than a predetermined threshold value. For example, it determines whether or not the potential difference between both ends of the shunt resistor is equal to or greater than a predetermined value. The thing of the simple structure which can only be used can be used.

(Method for manufacturing pressure-sensitive sensor)
Next, a manufacturing method of the pressure sensitive sensor 1A will be described with reference to FIG. A manufacturing method of the pressure-sensitive sensor 1A includes a winding step in which a plurality of electrode wires 20 and a plurality of inclusions 30 are spirally wound around a single linear spacer 50 (see FIG. 4) described later, It has an extrusion molding process of forming a tubular member 10 by extruding a rubber material around a plurality of wound electrode wires 20 and a plurality of inclusions 30, and a drawing process of pulling out the spacer 50.

  FIG. 4 shows the spacer 50 after the winding step, the plurality of electrode wires 20 (first and second electrode wires 21 and 22) wound around the spacer 50, and the plurality of inclusions 30 (first to fourth interventions). It is a perspective view which shows the thing 31-34).

  The spacer 50 is a rod-shaped member made of, for example, a fluororesin (Teflon (registered trademark)). In the present embodiment, the spacer 50 has a cylindrical shape, but is not limited thereto, and may be, for example, an elliptical column shape or a rectangular column shape with a polygonal cross section. However, in order to facilitate the drawing operation in the drawing process, it is desirable that the cross-sectional shape perpendicular to the longitudinal direction is constant.

  In the winding step, the plurality of electrode wires 20 and the plurality of inclusions 30 are supplied from the reel to the outer periphery of the spacer 50 stretched linearly with a predetermined tension, and are wound spirally. At this time, the plurality of electrode lines 20 and the plurality of inclusions 30 are in contact with the outer peripheral surface of the spacer 50 and between the electrode lines 20 and the inclusions 30 adjacent to each other in the circumferential direction of the spacer 50 and between the inclusions 30. Avoid gaps. Hereinafter, the spacer 50, the plurality of electrode wires 20 wound around the spacer 50, and the plurality of inclusions 30 are referred to as a wound body 5.

  In the extrusion molding process, a rubber material (EPDM) is extruded to the outer periphery of the wound body 5 by an extruder, and then the rubber material is solidified to mold the tubular member 10. Thus, the wound body 5 in which the tubular member 10 is molded on the outer periphery is cut into a predetermined length (for example, 1 to 2 m) and sent to the drawing process.

  In the drawing process, one end of the wound body 5 cut to a predetermined length is fixed, and the spacer 50 is pulled out from the other end. If the spacer 50 is made of a fluororesin having a small surface friction coefficient, this drawing operation can be easily performed. A central portion of the tubular member 10 from which the spacer 50 is drawn becomes a space 100 sandwiched between the plurality of electrode wires 20. As described above, the pressure-sensitive sensor 1A is obtained.

(Effects of the first embodiment)
According to the first embodiment described above, the plurality of electrode wires 20 are separated not only by the tubular member 10 but also by the elasticity of the inclusions 30. Thereby, it is possible to ensure a restoring force that separates the electrode wires 20 from each other while suppressing an increase in size of the pressure-sensitive sensor 1A. In addition, the inclusion 30 does not need to be extracted after the extrusion molding process, and only one spacer 50 needs to be pulled out. Therefore, the operation in the extraction process is facilitated, and the manufacturing cost can be reduced.

  Further, according to the present embodiment, the diameter of the inclusion 30 is larger than the diameter of the electrode wire 20, and the thickness of the tubular member 10 is thinner on the outside of the inclusion 30 than on the outside of the electrode wire 20. When receiving pressure from the outside, the tubular member 10 is elastically deformed flexibly, and the sensitivity of the pressure sensor 1A can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6, members and the like that are the same as those described in the first embodiment are given the same reference numerals, and redundant descriptions are omitted.

  FIG. 5 is a cross-sectional view showing a pressure-sensitive sensor 1B according to the second embodiment of the present invention. In the first embodiment, the case where the pressure-sensitive sensor 1A has two electrode wires 20 and a plurality of inclusions 30 are arranged on both sides of the two electrode wires 20 has been described. The pressure-sensitive sensor 1B according to the embodiment has four electrode wires 20, and one inclusion 30 is provided between each two electrode wires 20 adjacent in the circumferential direction in the cross section shown in FIG. Is arranged. The inclusion 30 is formed of a hollow cylindrical tube, and the diameter thereof is formed to be equal to the diameter of the electrode wire 20. However, the diameter of the inclusion 30 may be larger than the diameter of the electrode wire 20. The plurality of electrode wires 20 and inclusions 30 are spirally held inside the tubular member 10.

  The pressure sensor 1B is manufactured by a manufacturing method similar to the manufacturing method described in the first embodiment. That is, a plurality of electrode wires 20 and a plurality of inclusions 30 are spirally wound around a linear spacer, and a rubber material is extruded around the plurality of electrode wires 20 and the plurality of inclusions 30 to form the tubular member 10. Thereafter, the pressure sensor 1B is obtained by pulling out the spacer.

  If these four electrode lines 20 are first to fourth electrode lines 21 to 24, respectively, the first electrode lines 21 facing each other across the central axis C when pressure is applied to the pressure sensor 1B from the outside. And the third electrode line 23 or the second electrode line 22 and the fourth electrode line 24 are in contact (short circuit) with each other.

  FIG. 6 is a diagram illustrating a configuration example of an electric circuit 4B for detecting when pressure is applied to the pressure sensor 1B from the outside. Similar to the electric circuit 4A according to the first embodiment, the electric circuit 4B includes a pressure-sensitive sensor 1B, a DC power supply 41, an ammeter 42, and first and second resistors 43 and 44. The connection method is different.

  That is, in the electric circuit 4B, the DC power source 41, the ammeter 42, and the first resistor 43 are formed of the metal wires 200 of the first electrode wire 21 and the metal of the fourth electrode wire 24 at one end of the pressure sensor 1B. The second resistor 44 is connected in series between the wire 200 and the metal wire 200 of the second electrode wire 22 and the metal wire 200 of the third electrode wire 23 at one end of the pressure sensor 1B. Are connected in series. At the other end of the pressure-sensitive sensor 1B, the metal line 200 of the first electrode line 21 and the metal line 200 of the second electrode line 22 are short-circuited, and the metal line 200 of the third electrode line 23 and the fourth line The metal wire 200 of the electrode wire 24 is short-circuited.

  When pressure does not act on the pressure sensor 1B from the outside, the first to fourth electrode wires 21 to 24 are separated by the elasticity of the tubular member 10 and the first to fourth inclusions 31 to 34, and the ammeter At 42, a current having a value obtained by dividing the power supply voltage of the DC power supply 41 by the resistance value of the combined resistance of the first resistor 43 and the second resistor 44 is measured. On the other hand, when pressure is applied to the pressure sensor 1B from the outside and the first electrode line 21 and the third electrode line 23 or the second electrode line 22 and the fourth electrode line 24 come into contact with each other, the ammeter 42 Then, a current having a value obtained by dividing the power supply voltage of the DC power supply 41 by the resistance value of the first resistor 43 is measured. Thereby, similarly to the first embodiment, it is possible to determine the presence or absence of contact between the plurality of electrode wires 20 based on the measurement value of the ammeter 42.

  Also according to this embodiment, the same operations and effects as those of the first embodiment can be obtained. The electric circuit 4B is not limited to the configuration shown in FIG. 6 and the arrangement of the second electrode line 22 and the third electrode line 23 may be switched. In this case, when the first electrode line 21 contacts the second electrode line 22 or the fourth electrode line 24, or the third electrode line 23 contacts the second electrode line 22 or the fourth electrode line 24. When contacted, the current measured by the ammeter 42 changes.

(Summary of embodiment)
Next, the technical idea grasped from the embodiment described above will be described with reference to the reference numerals in the embodiment. However, each reference numeral in the following description does not limit the constituent elements in the claims to members or the like specifically shown in the embodiment.

[1] A hollow tubular member (10) having elasticity and insulating properties, a plurality of electrode wires (20) that are spirally held inside the tubular member (10), and the tubular member (10) 10), and a plurality of insulating inclusions (30) interposed between the plurality of electrode wires (20) in a spiral shape, and the inclusions (30) are linear elastic. A pressure-sensitive sensor (1A / 1B) comprising a body (30).

[2] The pressure sensor (1A / 1B) according to [1], wherein the inclusion (30) is a hollow cylindrical tube.

[3] The pressure sensor (1A / 1B) according to [1] or [2], wherein a diameter (D ₂ ) of the inclusion (30) is equal to or larger than a diameter (D ₁ ) of the electrode wire. .

[4] The pressure sensor (1A / 1B) according to any one of [1] to [3], wherein the inclusion (30) is made of the same rubber material as the tubular member (10).

[5] Between the plurality of electrode lines (20), the inclusion sets (3a, 3b) including the plurality of inclusions (30) adjacent to each other are disposed. [1] to [4] ] The pressure-sensitive sensor (1A) according to any one of the above.

[6] A method of manufacturing a pressure sensitive sensor (1A / 1B) according to any one of [1] to [5], wherein a plurality of the electrode wires (around the linear spacer (50) ( 20) and the step of winding the inclusion (30) in a spiral shape, and extruding a material around the electrode wire (20) and the inclusion (30) wound around the spacer (50) to form the tubular member ( 10) and a method for manufacturing the pressure-sensitive sensor (1A / 1B), which includes a step of pulling out the spacer (50).

(Appendix)
While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

  Further, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention. For example, the material of each member described above is shown as an example, and a material different from the above can be used as appropriate. Further, the number of electrode wires 20 and inclusions 30 is not limited to those exemplified in the first and second embodiments, and can be increased or decreased as necessary.

DESCRIPTION OF SYMBOLS 1A, 1B ... Pressure-sensitive sensor 10 ... Tubular member 20 ... Electrode wires 21-24 ... 1st thru | or 4th electrode wire 30 ... Inclusions 31-34 ... 1st thru | or 4th inclusion 3a, 3b ... Inclusion group 50 ... Spacers D ₁ , D ₂ ... Diameter

Claims (6)

A hollow tubular member having elasticity and insulation;
A plurality of electrode wires that are spirally held apart from each other inside the tubular member;
A plurality of insulating inclusions spirally held inside the tubular member and interposed between the plurality of electrode wires,
The inclusion is made of a linear elastic body.
Pressure sensitive sensor. The inclusion is a hollow cylindrical tube,
The pressure-sensitive sensor according to claim 1. The diameter of the inclusion is not less than the diameter of the electrode wire,
The pressure-sensitive sensor according to claim 1 or 2. The inclusion is made of the same rubber material as the tubular member.
The pressure-sensitive sensor according to any one of claims 1 to 3. Between the plurality of electrode lines, an inclusion set composed of a plurality of the inclusions adjacent to each other is disposed.
The pressure-sensitive sensor according to any one of claims 1 to 4. A method for manufacturing a pressure-sensitive sensor according to any one of claims 1 to 5,
A step of spirally winding a plurality of the electrode lines and the inclusions around a linear spacer;
Forming the tubular member by extruding a material around the electrode wire and the inclusion wound around the spacer;
Extracting the spacer; and
A method for manufacturing a pressure sensitive sensor.

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