JPWO2017056240A1 - Pressure sensor - Google Patents

Abstract

Disclosed is a pressure-sensitive sensor having excellent terminal processability with suppressed surface adhesion.
SOLUTION: A cylindrical elastic insulator 2 having a hollow portion 2a along the longitudinal direction and an inner peripheral surface of the hollow portion 2a of the elastic insulator 2 are arranged so as not to contact each other. The elastic insulator 2 includes at least the outermost layer 5 made of thermoplastic urethane, and the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is 3 μm or more.

Description

  The present invention relates to a pressure sensitive sensor.

  Conventionally, a cylindrical elastic insulator having a hollow portion along the longitudinal direction, and a plurality of electrode wires arranged along the inner peripheral surface of the hollow portion of the elastic insulator and arranged so as not to contact each other Are known.

  A pressure-sensitive sensor fulfills a switching function by contacting internal electrode wires when they are subjected to an external force and becoming a conductive state. For example, the pressure-sensitive sensor is used for pinching detection in a sliding door of a vehicle. Yes.

  Patent Document 1 describes a pressure sensor using thermoplastic urethane as the outermost layer of an elastic insulator. By using thermoplastic urethane as the outermost layer of the elastic insulator, the heat resistance, oil resistance, cold resistance, and wear resistance of the pressure sensitive sensor can be improved at low cost.

JP 2011-52433 A

  By the way, the detector which detects the conduction | electrical_connection state of an electrode wire is attached to the terminal of a pressure sensor, and it is used as a sensor unit. At this time, many processes such as removal of the elastic insulator of the pressure sensor (coating strip), soldering of the conductor of the electrode wire, resin molding of the terminal portion, and the like are performed as terminal processing. At the time of this terminal processing, it is usual that a plurality of (for example, 100 to 200) pressure-sensitive sensors are collectively transferred from the previous process to the next process.

  However, in the pressure-sensitive sensor using the thermoplastic urethane as the outermost layer of the elastic insulator, the thermoplastic urethanes of the outermost layer are easily adhered to each other. For example, if only one is extracted from a bundle of 100 to 200, a plurality There is a problem in that the pressure sensor of the book sticks and gets tangled, and the workability is significantly reduced.

  From the viewpoint of improving mass productivity, it is desirable to use an automatic processing machine for the process of the covering strip. However, in a pressure-sensitive sensor using thermoplastic urethane as the outermost layer of the elastic insulator, the outermost layer of thermoplastic urethane is used. Since the removed elastic insulator adheres to the automatic processing machine due to the adhesion, there is also a problem that it is difficult to use the automatic processing machine.

  Accordingly, an object of the present invention is to provide a pressure-sensitive sensor having excellent terminal processability with suppressed surface adhesion.

  In order to solve the above problems, the present invention is arranged along a cylindrical elastic insulator having a hollow portion along the longitudinal direction, along an inner peripheral surface of the hollow portion of the elastic insulator, and A plurality of electrode wires arranged so as not to contact each other, and the elastic insulator includes at least an outermost layer made of thermoplastic urethane, and an arithmetic average surface roughness Ra of the surface of the outermost layer is 3 μm. A pressure-sensitive sensor as described above is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the pressure sensitive sensor with favorable terminal workability which suppressed surface adhesion can be provided.

It is sectional drawing of the pressure-sensitive sensor which concerns on one embodiment of this invention. (A) is the photograph of the surface of the outermost layer in the pressure sensor of Example 1, (b) is a graph which shows the measurement result of the surface roughness. (A) is the photograph of the surface of the outermost layer in the pressure sensor of Example 3, (b) is a graph which shows the measurement result of the surface roughness. (A) is the photograph of the surface of the outermost layer in the pressure sensor of the comparative example 1, (b) is a graph which shows the measurement result of the surface roughness. (A), (b) is a figure explaining the terminal processing of the pressure-sensitive sensor by an automatic processing machine. It is sectional drawing of the pressure sensitive sensor which concerns on other embodiment of this invention. It is sectional drawing of the pressure sensitive sensor which concerns on other embodiment of this invention.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a pressure-sensitive sensor according to this embodiment.

  As shown in FIG. 1, the pressure-sensitive sensor 1 is disposed along a cylindrical elastic insulator 2 having a hollow portion 2a along the longitudinal direction, and an inner peripheral surface of the hollow portion 2a of the elastic insulator 2, And a plurality of electrode wires 3 arranged so as not to contact each other.

(Description of electrode wire 3)
The electrode wire 3 is configured by covering a conductor 6 with a conductor 7. In the present embodiment, the case where two electrode wires 3 are used will be described, but the number of electrode wires 3 may be three or more. The two electrode wires 3 are spirally arranged along the inner peripheral surface of the hollow portion 2a, and are opposed to each other with the hollow portion 2a interposed therebetween (with the center in the sectional view of the pressure sensor 1 interposed). Are arranged to be.

  As the conductor 6, in order to obtain excellent flexibility, it is preferable to use a metal stranded wire obtained by twisting a plurality of metal strands. As the conductor 6, for example, a stranded wire of 26-30 AWG silver-plated annealed copper wire can be used.

  As the conductive resin composition constituting the conductor 7, a rubber material or an elastic plastic material blended with a conductive filler such as carbon can be used. Moreover, as the conductor 7, a conductive resin composition containing a styrene-based thermoplastic elastomer and carbon can also be used. Since the styrenic thermoplastic elastomer does not require crosslinking during molding, the manufacturing process of the conductor 7 can be simplified and the manufacturing cost can be reduced as compared with the case of using a material that requires crosslinking during molding. Can do.

  Styrenic thermoplastic elastomer is a thermoplastic elastomer having styrene blocks at both ends of the molecule. Examples of the styrene-based thermoplastic elastomer include SEBS having styrene blocks at both ends of EB (ethylene-butylene), SEPS having styrene blocks at both ends of EP (ethylene-propylene), or EEP (ethylene-ethylene-propylene). An example is SEEPS having styrene blocks at both ends.

  Carbon added to the conductor 7 is added to impart conductivity to the conductor 7. The carbon is preferably particulate carbon such as carbon black. When a shape other than particles, for example, linear or planar carbon, is used, the magnitude of the electrical resistance of the conductor 7 varies depending on the direction, which may adversely affect the operation of the pressure-sensitive sensor 1. Here, carbon black is fine particles of carbon having a diameter of about 3 to 500 nm obtained by incomplete combustion of oil or gas. In particular, conductive carbon black having a structure called a structure in which carbon primary particles are connected is preferable.

  The mass percentage concentration of carbon in the conductive resin composition constituting the conductor 7 is preferably 18% by mass or more. Thereby, the volume resistivity of the conductor 7 becomes sufficiently small. The mass percent concentration of carbon is calculated by multiplying 100 by the value obtained by dividing the mass of carbon by the mass of the entire conductive resin composition (the mass of the conductor 7).

(Description of elastic insulator 2)
The elastic insulator 2 includes at least an outermost layer 5 made of thermoplastic urethane (thermoplastic urethane elastomer). That is, at least the outer surface of the elastic insulator 2 is made of thermoplastic urethane.

  In the present embodiment, the elastic insulator 2 includes a tubular member 4 having a circular outer peripheral surface in a cross section perpendicular to the longitudinal direction, and an outermost layer 5 made of thermoplastic urethane formed around the tubular member 4. And is composed of.

  The tubular member 4 has elasticity (restorability) that is deformed when an external force is applied and is restored immediately when the external force disappears. The two electrode wires 3 are separated from each other only by the elastic force of the tubular member 4 and are kept in a non-contact state when no external force is applied.

  As the insulating resin composition constituting the tubular member 4, rubber materials such as ethylene propylene diene rubber (EPDM), silicone rubber, ethylene propylene rubber, styrene butadiene rubber, or chloroprene rubber, and elastic plastics can be used.

  The tubular member 4 is formed by extrusion molding with an extruder. When the annular member 4 is formed, two electrode wires 3 and a plurality of (for example, five) spacers (dummy wires) are twisted together, and the tubular member 4 is covered by extrusion molding. Thereafter (after the outermost layer 5 is formed), the hollow portion 2a is formed by pulling out the spacer (dummy line).

  The outermost layer 5 protects the tubular member 4 and enhances scratch resistance, durability, and weather resistance. In the present embodiment, the outermost layer 5 is made of thermoplastic urethane having excellent heat resistance, oil resistance, cold resistance, and wear resistance.

  In the pressure-sensitive sensor 1 according to the present embodiment, the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is 3 μm or more. By making the surface of the outermost layer 5 a rough surface with an arithmetic average surface roughness Ra of 3 μm or more, surface adhesion is suppressed, and a plurality of pressure-sensitive sensors 1 are prevented from being adhered and entangled during terminal processing. It becomes possible to do. In addition, when the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is less than 3 μm, the surface of the outermost layer 5 becomes glossy and surface adhesion occurs.

  From the viewpoint of further suppressing surface adhesion, the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is more preferably 4 μm or more. In addition, if the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is too large, the mechanical strength of the outermost layer 5 may be lowered, and the appearance is obviously deteriorated. The arithmetic average surface roughness Ra is more preferably 7 μm or less. That is, it can be said that the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is more preferably 4 μm or more and 7 μm or less.

  Here, the arithmetic average surface roughness Ra is obtained by a parameter calculation formula based on JIS B0601 (2013). When calculating the arithmetic average surface roughness Ra, it is necessary to measure the contour curve in advance. In the present embodiment, the contour curve is measured by non-contact contour curve measurement using a confocal microscope or the like.

When performing non-contact type contour curve measurement, an apparatus having at least the following resolution is used when an objective lens of 100X / NA 0.95 (100 times, numerical aperture 0.95) is used. An example of such an apparatus is a confocal microscope H300 manufactured by Lasertec. Note that σ is a standard deviation.
(Line width measurement function: X-axis direction)
Minimum measurement resolution: 0.001 μm
Repeat measurement accuracy: (3σ) 0.01 μm
(Height measurement function: Z-axis direction)
Minimum measurement resolution: 0.001 μm
Repeat measurement accuracy: (σ) 0.01 μm

  That is, the arithmetic average surface roughness Ra in the present specification is calculated by a parameter calculation formula based on JIS B0601 (2013) based on the result of the non-contact type contour curve measurement by the apparatus having at least the resolution described above. It is.

  The outermost layer 5 is formed by extrusion using an extruder. The surface roughness of the outermost layer 5 can be controlled by the conditions at the time of extrusion molding, that is, the set temperature and line speed (resin flow rate) at the time of extrusion molding. For example, the surface roughness of the outermost layer 5 can be increased by lowering the set temperature during extrusion molding to increase the viscosity of the resin. Further, by setting the line speed faster, the shear stress acting on the resin can be increased, and the surface roughness of the outermost layer 5 can be increased. The set temperature and line speed during extrusion can be set as appropriate according to the size of the extruder and the like, and the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is 3 μm or more (more preferably 4 μm or more and 7 μm or less). Extrusion molding is preferably performed under the following conditions.

  Here, the measurement result of the arithmetic mean surface roughness Ra of the surface of the outermost layer 5 when the set temperature and the line speed during the extrusion molding of the outermost layer 5 are changed will be described.

  Here, the number of the electrode wires 3 is two, and the conductors 7 of both the electrode wires 3 are made of a crosslinked conductive rubber compounded with carbon black, and the outer diameter thereof is 0.6 mm. The tubular member 4 is made of crosslinked EPDM and has an outer diameter of 3.5 mm. The outermost layer 5 is made of thermoplastic urethane having a hardness of 85, and the thickness of the outermost layer 5 is 0.3 mm. For the measurement of the arithmetic average surface roughness Ra of the surface of the outermost layer 5, the above-mentioned Confocal Microscope H300 manufactured by Lasertec was used. Table 1 summarizes the conditions during extrusion molding and the measurement results of the arithmetic average surface roughness Ra of the surface of the outermost layer 5.

  As shown in Table 1, when the extruder size is 65 mm and the cylinder set temperature and the head set temperature are 204 ° C., the surface of the outermost layer 5 is set at 35-60 m / min. The arithmetic average surface roughness Ra can be set to 4.3 μm to 7.0 μm of 3 μm or more (Examples 1 to 3). On the other hand, in Comparative Example 2 in which the cylinder set temperature is 220 ° C., the head set temperature is 215 ° C., and the line speed is 18 m / min, the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is 1.8 μm, which is less than 3 μm. became.

  In the case where the extruder size is 20 mm, the cylinder set temperature is 190 ° C., the head set temperature is 180 ° C., and the line speed is 15 m / min. In Example 4, the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is It became 3.3 micrometers of 3 micrometers or more. On the other hand, in Comparative Example 1 in which the cylinder set temperature is 190 ° C., the head set temperature is 185 ° C., and the line speed is 1.8 m / min, the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is less than 3 μm. It became 5 μm.

  In addition, the diameter of the screw of an extruder becomes large and the self-heating of resin becomes large, so that an extruder size is large. Therefore, the larger the extruder size, the higher the actual resin temperature even at a relatively low set temperature, and the arithmetic average surface roughness Ra of the surface of the outermost layer 5 may become smaller. Therefore, it is necessary to select an appropriate set temperature according to the extruder size and the like, and to form the outermost layer 5 under the condition that the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is 3 μm or more.

  Micrographs of the surface of the outermost layer 5 of Example 1, Example 3, and Comparative Example 1 are shown in FIGS. 2 (a), 3 (a), and 4 (a), respectively. The measurement results of the surface roughness of Example 3 and Comparative Example 1 are shown in FIG. 2 (b), FIG. 3 (b), and FIG. 4 (b), respectively. 2B, 3B, and 4B, the horizontal axis represents the measurement position (distance from the reference position), and the vertical axis represents the height of the surface (from the reference position). Height).

  As shown in FIGS. 2 and 3, in Examples 1 and 3, the surface of the outermost layer 5 is in a rough state, and it is difficult for adhesion to occur. However, as shown in FIG. 1 shows that the surface of the outermost layer 5 is in a smooth state, and is in a state where adhesion is likely to occur.

  Next, the workability of terminal processing was examined using the pressure sensitive sensors 1 of Examples 1 to 4 and Comparative Examples 1 and 2. Here, workability when the created pressure-sensitive sensor 1 was cut to a length of 1300 mm, the cut pressure-sensitive sensor 1 was set in an automatic processing machine, and the terminal was automatically processed was examined.

  In the automatic processing machine, as shown in FIG. 5A, at the position 15 mm from the end of the pressure sensor 1, two V-shaped hot blades 51 are advanced so as to sandwich the pressure sensor 1 from the opposite direction. Then, the tubular member 4 and the outermost layer 5 are cut by the hot blade 51. At this time, the advancement amount (slide amount) of the hot blade 51 is adjusted so as not to damage the electrode wire 3. Thereafter, as shown in FIG. 5B, the elastic insulator 2 is grasped and pulled out by holding the terminal portion 54 of the elastic insulator 2 cut by the hot blade 51 with the pressure sensor 1 held by the clamp 52. Remove. Thereafter, the terminal portion 54 of the elastic insulator 2 is released from the manipulator 53 by releasing the gripping of the manipulator 53. At this time, when the outermost layer 5 made of thermoplastic urethane in the terminal portion 54 adheres to the manipulator 53 and does not fall, the automatic processing is interrupted. Here, 2000 pressure-sensitive sensors 1 are automatically machined. Even if automatic machining work is interrupted even once, workability x (failed), and work that has been completed without any problem is workability ○ (passed) It was. The results are shown in Table 1.

  As shown in Table 1, in Examples 1-4 where the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is 3 μm or more (3.3 μm to 7.0 μm), 2000 pressure-sensitive sensors 1 are automatically processed. The automatic machining operation was not interrupted once. On the other hand, in Comparative Examples 1 and 2 in which the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is less than 3 μm (0.5 μm to 1.8 μm), the automatic processing operation of the pressure-sensitive sensor 1 is interrupted and the workability is increased. It was confirmed that there was a problem in terms of

(Operation and effect of the embodiment)
As described above, the pressure-sensitive sensor 1 according to the present embodiment includes the outermost layer 5 made of thermoplastic urethane, and the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is 3 μm or more.

  While the arithmetic average surface roughness Ra of the surface of the outermost layer 5 is 3 μm or more, the outermost layer 5 is made of thermoplastic urethane excellent in heat resistance, oil resistance, cold resistance, wear resistance, and economy. It becomes possible to suppress surface adhesion and to improve terminal processability.

  In addition, by setting the arithmetic average surface roughness Ra of the surface of the outermost layer 5 to 3 μm or more, it is possible to suppress the terminal portion 54 of the extracted elastic insulator 2 from adhering to the manipulator 53, and automatic processing by an automatic processing machine can be performed. It becomes possible. As a result, the mass productivity of the pressure sensitive sensor 1 can be improved.

  Furthermore, by setting the arithmetic average surface roughness Ra of the surface of the outermost layer 5 to 3 μm or more, it becomes possible to suppress the gloss of the surface to give a matte appearance and to improve the appearance. .

(Other embodiments)
Next, another embodiment of the present invention will be described.

  The pressure-sensitive sensor 61 shown in FIG. 6 has basically the same configuration as the pressure-sensitive sensor 1 in FIG. 1, and only the shape of the outermost layer 5 is different.

  In the pressure-sensitive sensor 61, a flat adhesive surface 62 is formed on the outer peripheral surface of the outermost layer 5 along the longitudinal direction for bonding and fixing to an attachment object such as a vehicle slide door. The pressure-sensitive sensor 61 is directly adhered and fixed to the attachment object by adhering the adhesion surface 62 to the attachment object with a double-sided tape, an adhesive, or the like. This makes it possible to easily attach the pressure-sensitive sensor 61 to an attachment object without using a member such as a protector rubber or a sensor guide as in the prior art.

  In the pressure-sensitive sensor 61, the arithmetic average surface roughness Ra of the entire outermost layer 5 including the adhesive surface 62 is 3 μm or more, and the surface is rough. Therefore, when the pressure-sensitive sensor 61 is bonded and fixed to the object to be attached, it is possible to improve the adhesion due to the anchor effect.

  In the pressure-sensitive sensor 61, the outermost layer 5 has a flange-like tongue piece 63 protruding in the width direction (longitudinal direction and a direction perpendicular to the normal direction of the adhesive surface 62, the left-right direction in the drawing) at the periphery of the adhesive surface 62. Is integrated. The tongue piece 63 is a protruding piece that protrudes along the width direction, is formed symmetrically so as to protrude on both sides in the width direction, and is formed in the entire longitudinal direction of the outermost layer 5.

  By forming the tongue piece portion 63, it is possible to increase the area of the adhesive surface 62 and firmly fix the pressure sensor 61 to the attachment object. Further, by forming the tongue piece portion 63, even when pressure is applied in a direction parallel to the bonding surface 62, the tongue piece portion 63 on the side opposite to the pressure-receiving side is stretched, whereby the tubular member 4 can be deformed and both electrode wires 3 can be brought into contact with each other. Therefore, the pressure detection angle range in the cross section orthogonal to the extending direction of the tubular member 4 can be 180 ° or more, and it is possible to appropriately detect contact with the detection target within the detection angle range. .

  The pressure-sensitive sensor 71 shown in FIG. 7 has a bonding surface 62 formed by forming a cross-sectional shape perpendicular to the longitudinal direction of the outermost layer 5 in a D shape. Even when the outermost layer 5 is formed in a D-shaped cross-section like the pressure-sensitive sensor 71, the pressure-sensitive sensor 71 can be easily attached to the attachment object by double-sided tape, adhesive, or the like, similarly to the pressure-sensitive sensor 61 of FIG. It becomes possible to install. In addition, since the arithmetic average surface roughness Ra of the bonding surface 62 is 3 μm or more, the adhesiveness can be improved by the anchor effect.

  In the pressure-sensitive sensor 71 of FIG. 7, when pressure is applied from a direction parallel to the bonding surface 62, a force in a peeling direction is generated at the end of the bonding surface 62 on the side receiving the pressure. It is easy to peel off from the object to be attached. Therefore, it can be said that it is more desirable to form the tongue piece part 63 like the pressure sensor 61 of FIG. 6 from a viewpoint of suppressing peeling from an attachment target object.

(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, the reference numerals and the like in the following description are not intended to limit the constituent elements in the claims to the members and the like specifically shown in the embodiments.

[1] A cylindrical elastic insulator (2) having a hollow portion (2a) along the longitudinal direction, and an inner peripheral surface of the hollow portion (2a) of the elastic insulator (2), And a plurality of electrode wires (3) arranged so as not to contact each other, and the elastic insulator (2) includes at least an outermost layer (5) made of thermoplastic urethane, and the outermost layer ( 5) The pressure-sensitive sensor (1) having an arithmetic average surface roughness Ra of 3 μm or more.

[2] The pressure-sensitive sensor (1) according to [1], wherein an arithmetic average surface roughness Ra of the surface of the outermost layer (5) is 4 μm or more and 7 μm or less.

[3] The pressure sensitive sensor (1) according to [1] or [2], wherein the electrode wire (3) has a conductor (7) made of a conductive resin composition containing a styrene-based thermoplastic elastomer and carbon. ).

[4] On the outer peripheral surface of the outermost layer (5), a flat adhesive surface (62) for adhering and fixing to an attachment object is formed along the longitudinal direction. [1] to [3] The pressure sensor (61, 71) according to any one of the above.

[5] The outermost layer (5) is a flange-like tongue projecting in the longitudinal direction and the width direction that is perpendicular to the normal direction of the adhesive surface (62) at the periphery of the adhesive surface (62). The pressure-sensitive sensor (61) according to [4], wherein the pressure sensor (61) has an integral part (63).

  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.

  The present invention can be appropriately modified and implemented without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the case where the present invention is applied to a sliding door of a vehicle has been described as an example. However, the present invention is not limited to this, and the present invention includes, for example, a vehicle back door, a power window, an elevator, a shutter, an automatic door, The present invention can be applied to sensors that detect any physical pinching such as windows.

DESCRIPTION OF SYMBOLS 1 ... Pressure sensor 2 ... Elastic insulator 2a ... Hollow part 3 ... Electrode wire 4 ... Tubular member 5 ... Outermost layer 6 ... Conductor 7 ... Conductor

Claims (5)

A cylindrical elastic insulator having a hollow portion along the longitudinal direction;
A plurality of electrode wires arranged along the inner peripheral surface of the hollow portion of the elastic insulator and arranged not to contact each other,
The elastic insulator includes at least an outermost layer made of thermoplastic urethane, and an arithmetic average surface roughness Ra of the surface of the outermost layer is 3 μm or more.
Pressure sensitive sensor. The arithmetic average surface roughness Ra of the surface of the outermost layer is 4 μm or more and 7 μm or less,
The pressure-sensitive sensor according to claim 1. The electrode wire has a conductor made of a conductive resin composition containing a styrene-based thermoplastic elastomer and carbon.
The pressure-sensitive sensor according to claim 1 or 2. On the outer peripheral surface of the outermost layer, a flat adhesive surface is formed along the longitudinal direction for bonding and fixing to an attachment object.
The pressure-sensitive sensor according to any one of claims 1 to 3. The outermost layer integrally has a flange-like tongue piece projecting in the width direction, which is a direction perpendicular to the longitudinal direction and the normal direction of the adhesive surface, at the periphery of the adhesive surface.
The pressure-sensitive sensor according to claim 4.