Pressure sensor and method for manufacturing the same

Abstract

To improve the assembly efficiency of pressure-sensitive sensors. [Solution] The pressure sensor comprises a hollow outer sheath 11, first conductive wires 21a to fourth conductive wires 24a provided inside the outer sheath 11 and capable of conducting electricity with each other due to the elastic deformation of the outer sheath 11, and a conductive wire twisted portion 14 provided on one side in the longitudinal direction of the outer sheath 11, formed by bringing the second and fourth conductive wires 22a and 24a into contact with each other. This eliminates the need for a short-circuit wire to connect the second and fourth conductive wires 22a and 24a in a conductive manner, and also eliminates the welding work required to connect such a short-circuit wire. Therefore, it is possible to improve the assembly workability of the pressure sensor 10. In addition, since the number of welding points can be reduced, the occurrence of welding defects and the like can be suppressed.

Description

Technical Field

[0001] The present invention relates to a pressure sensor and a method for manufacturing the same.

Background Art

[0002] For example, Patent Document 1 describes a cable-shaped sensor unit including a cylindrical insulating layer and four electrode wires disposed inside the insulating layer. When the insulating layer is elastically deformed by contact with an obstacle, the four electrode wires inside the insulating layer come into contact (short circuit) with each other.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the sensor unit described in Patent Document 1, two short-circuit wires are provided on one side in the longitudinal direction. One short-circuit wire is connected to one side in the longitudinal direction of a pair of electrode wires, and the other short-circuit wire is connected to one side in the longitudinal direction of the other pair of electrode wires. Therefore, it is necessary to prepare two short-circuit wires and connect each short-circuit wire to the electrode wire by welding or the like, which has led to a decrease in assembly workability.

[0005] An object of the present invention is to improve the assembly workability of a pressure sensor.

Means for Solving the Problems

[0006] In one aspect of the present invention, the pressure sensor is an elastically deformable pressure sensor that can be brought into contact with an obstacle, and comprises a hollow cable-like insulator, at least one pair of conductive wires provided inside the cable-like insulator and capable of conducting electricity with each other due to the elastic deformation of the cable-like insulator, and a conductive wire contact portion provided on one side in the longitudinal direction of the cable-like insulator, which brings the pair of conductive wires into contact with each other.

[0007] In another aspect of the present invention, a method for manufacturing a pressure sensor is a method for manufacturing a pressure sensor that is elastically deformable upon contact with an obstacle, comprising: a workpiece preparation step of preparing a workpiece consisting of a hollow cable-like insulator and a pair of conductive wires provided inside the cable-like insulator; a cable-like insulator cutting step of making an incision in the cable-like insulator so that the cable-like insulator can be separated into a main body portion and an end portion in the longitudinal direction thereof; a conductive wire exposure step of pulling the main body portion and the end portion apart from each other to expose the pair of conductive wires between the main body portion and the end portion; and a conductive wire contact portion forming step of bringing the exposed pair of conductive wires into contact with each other to form a conductive wire contact portion. [Effects of the Invention]

[0008] According to the present invention, the assembly workability of pressure-sensitive sensors can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing the pressure sensor of Embodiment 1. [Figure 2] This is a cross-sectional view of the pressure sensor along its radial direction. [Figure 3] This is an electrical circuit diagram showing an example of the use of a pressure-sensitive sensor. [Figure 4] This is a view of the tip end of the pressure sensor, seen from the axial direction. [Figure 5] This is a view from arrow A in Figure 4. [Figure 6] This is a view from arrow B in Figure 4. [Figure 7] This diagram shows the workpiece preparation process and the outer shell cutting process. [Figure 8] It is a diagram showing the process of exposing the conductive wire. [Figure 9] It is a diagram showing the process of welding the short - circuit wire. [Figure 10] It is a diagram showing the clamping process. [Figure 11] It is a diagram showing the process of twisting the conductive wire. [Figure 12] It is a diagram showing the process of separating the end material. [Figure 13] It is a diagram corresponding to FIG. 6 showing the pressure - sensitive sensor of Embodiment 2. [Figure 14] It is a diagram showing the process of welding the conductive wire. [Figure 15] It is a diagram corresponding to FIG. 4 showing the pressure - sensitive sensor of Embodiment 3. [Figure 16] It is a view seen from the direction of arrow C in FIG. 15. [Figure 17] It is a view seen from the direction of arrow D in FIG. 15. [Figure 18] It is a diagram showing the process of twisting the first conductive wire. [Figure 19] It is a diagram showing the process of twisting the second conductive wire. [Figure 20] It is a diagram corresponding to FIG. 3 showing the pressure - sensitive sensor of Embodiment 4.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] <Embodiment 1> FIG. 1 is a perspective view showing the pressure - sensitive sensor of Embodiment 1. FIG. 2 is a cross - sectional view along the radial direction of the pressure - sensitive sensor. FIG. 3 is an electrical circuit diagram showing an example of use of the pressure - sensitive sensor. FIG. 4 is a view of the tip - side terminal portion of the pressure - sensitive sensor seen from the axial direction. FIG. 5 is a view seen from the direction of arrow A in FIG. 4. FIG. 6 is a view seen from the direction of arrow B in FIG. 4.

[0012] <Overview of the Pressure - Sensitive Sensor> The pressure sensor 10 shown in Figures 1 to 6 is used, for example, to detect entrapment of occupants or luggage (obstacles) in a sliding door of a vehicle such as an automobile. Specifically, the pressure sensor 10 is mounted on the front of the sliding door and is easily elastically deformable upon contact with an obstacle.

[0013] The pressure sensor 10 is connected to an in-vehicle controller that controls the opening and closing operation of the sliding door. The pressure sensor 10 sends a detection signal to the in-vehicle controller as it undergoes elastic deformation. When the in-vehicle controller detects the detection signal from the pressure sensor 10, it switches the rotation direction of the electric motor that drives the sliding door, causing the sliding door to open while it is in the closing operation. This prevents obstacles from being caught in the sliding door.

[0014] <Structure of a pressure-sensitive sensor> As shown in Figures 1 and 2, the pressure sensor 10 is provided with a cable-like outer sheath 11. The outer sheath 11 is made of an elastic material such as rubber that has insulating properties, and its cross-section along the short direction (radial direction) intersecting its longitudinal direction is approximately circular. The outer sheath 11 is also formed in a roughly cylindrical shape, and a first electrode wire 21, a second electrode wire 22, a third electrode wire 23, and a fourth electrode wire 24 are provided on the radially inner side of the outer sheath 11.

[0015] Specifically, the first electrode wires 21 to the fourth electrode wires 24 are arranged at equal intervals (90-degree intervals) in the circumferential direction of the outer sheath 11 and extend spirally in the longitudinal direction of the outer sheath 11. Here, the first electrode wires 21 to the fourth electrode wires 24 are non-contacting with each other on the radially inner side of the outer sheath 11 and are arranged in a four-strand helix structure.

[0016] Furthermore, a hollow portion 12, formed in a substantially cross shape when viewed axially, is provided on the radially inner side of the outer sheath 11. In other words, the outer sheath 11 is hollow. As a result, the pressure sensor 10 (outer sheath 11) can be elastically deformed by the application of an external force F, as shown by the dashed line in Figure 2. The first electrode wires 21 to the fourth electrode wires 24, provided on the radially inner side of the outer sheath 11 and around the hollow portion 12, come into contact with each other and become electrically conductive (short-circuit) as the outer sheath 11 elastically deforms. The outer sheath 11 corresponds to the cable-like insulator in this invention.

[0017] As shown in Figures 1 and 2, the first electrode wires 21 to the fourth electrode wires 24 each have the same structure. Specifically, the first electrode wires 21 to the fourth electrode wires 24 each consist of a first conductive wire 21a to the fourth conductive wire 24a, which are made by twisting thin copper wires together, and a first conductive rubber 21b to the fourth conductive rubber 24b that covers the first conductive wires 21a to the fourth conductive wire 24a. As a result, when an external force F is applied to the outer sheath 11 and the outer sheath 11 is elastically deformed, the first conductive rubber 21b to the fourth conductive rubber 24b come into contact with each other, and the first conductive wires 21a to the fourth conductive wire 24a inside them become electrically conductive with each other.

[0018] Furthermore, the materials used for the first conductive rubber 21b to the fourth conductive rubber 24b include, for example, silicone rubber containing carbon black or metal powder.

[0019] <End portion> As shown in Figures 3 to 6, a tip-side terminal portion 13 is provided on one longitudinal side of the pressure sensor 10 (the right side in Figures 3, 5, and 6). The tip-side terminal portion 13 is provided with one longitudinal side (tip side) of the first and third conductive wires 21a and 23a exposed from the outer sheath portion 11. The pair of first and third conductive wires 21a and 23a are electrically connected to each other via a short-circuit wire WL.

[0020] Here, the short-circuit wire WL is a copper rod-shaped body that extends radially across the pressure sensor 10. Furthermore, both longitudinal ends of the short-circuit wire WL are fixed to the first and third conductive wires 21a and 23a by soldering, welding, or other means.

[0021] Furthermore, the tip end portion 13 is provided with one longitudinal side (tip side) of the second and fourth conductive wires 22a and 24a exposed from the outer sheath portion 11. Here, on one longitudinal side of the pressure sensor 10, the length dimension L1 of the second and fourth conductive wires 22a and 24a exposed from the outer sheath portion 11 is greater than the length dimension L2 of the first and third conductive wires 21a and 23a exposed from the outer sheath portion 11 (L1 > L2).

[0022] Furthermore, one longitudinal side of the pair of second and fourth conductive wires 22a and 24a are twisted together in a spiral, thereby bringing them into contact with each other. In other words, the pair of second and fourth conductive wires 22a and 24a can conduct electricity with each other without using a shorting wire WL. Specifically, the second and fourth conductive wires 22a and 24a are directly connected to each other by twisting them about five times.

[0023] Here, the contact portion of the second and fourth conductive wires 22a and 24a is a conductive wire twisted portion 14 formed by twisting one longitudinal side of these second and fourth conductive wires 22a and 24a together. Furthermore, the conductive wire twisted portion 14 is located at the tip-most part on one longitudinal side of the pressure sensor 10.

[0024] Thus, a conductive wire twisted portion 14 is provided on one longitudinal side of the second and fourth conductive wires 22a and 24a, where these second and fourth conductive wires 22a and 24a are in contact with each other. The conductive wire twisted portion 14 corresponds to the conductive wire contact portion in the present invention. The conductive wire contact portion refers to the part in which one conductive wire of a pair of conductive wires is in direct contact with the other conductive wire without any intermediary.

[0025] As shown in Figures 5 and 6, the short-circuit wire WL is positioned to cross the second and fourth conductive wires 22a and 24a, and is not in contact with the second and fourth conductive wires 22a and 24a and the conductive wire twisted portion 14. In addition, at the tip end portion 13, the pair of first and third conductive wires 21a and 23a and the pair of second and fourth conductive wires 22a and 24a are not in contact with each other.

[0026] Furthermore, the tip end portion 13 is provided with a tip end cap 15 made of an insulating material such as transparent rubber. The tip end cap 15 covers the first and third conductive wires 21a, 23a and the shorting wire WL, and the second and fourth conductive wires 22a, 24a and the conductive wire twisted portion 14.

[0027] The inside of the tip cap 15 is filled with UV-curing resin RS, which hardens when exposed to ultraviolet light. The UV-curing resin RS has insulating properties, and as a result, the pair of first and third conductive wires 21a, 23a, the pair of second and fourth conductive wires 22a, 24a, the short-circuit wire WL, and the twisted conductive wire portion 14 at the tip terminal portion 13 are sealed by the UV-curing resin RS to prevent them from short-circuiting each other.

[0028] The ultraviolet-curing resin RS corresponds to the encapsulant in this invention. Furthermore, the encapsulant is not limited to the ultraviolet-curing resin RS described above; an insulating thermosetting resin or the like can also be used.

[0029] Thus, the pressure sensor 10 is provided with a pair of first and third conductive wires 21a and 23a, and a pair of second and fourth conductive wires 22a and 24a. In other words, the pressure sensor 10 is provided with a total of two pairs of conductive wires.

[0030] <Base end portion> As shown in Figure 3, a base end portion 16 is provided on the other longitudinal side (left side in Figure 3) of the pressure sensor 10. The other longitudinal ends of the first conductive wires 21a to the fourth conductive wires 24a, which are exposed from the outer sheath portion 11, are provided on the base end portion 16. A resistor R is also provided on the base end portion 16. The resistor R is fixed to the second and third conductive wires 22a and 23a by soldering, welding, or the like.

[0031] Furthermore, at the base end portion 16, the positive terminal 17a of the power supply BT is connected to the first conductive wire 21a, and the negative terminal 17b of the power supply BT is connected to the fourth conductive wire 24a via the current detection unit 18. Here, the current detection unit 18 detects the current values ​​flowing through the first conductive wires 21a to the fourth conductive wires 24a, which are connected in series with each other.

[0032] Specifically, the current detection unit 18 detects the current value a1 flowing through the first conductive wire 21a to the fourth conductive wire 24a via the resistor R when no external force F is applied to the outer sheath 11, that is, when the outer sheath 11 is not elastically deformed. In contrast, when an external force F is applied to the outer sheath 11, the first conductive wire 21a to the fourth conductive wire 24a are short-circuited with each other via the first conductive rubber 21b to the fourth conductive rubber 24b (see Figures 1 and 2) due to the elastic deformation of the outer sheath 11. Therefore, the current detection unit 18 detects a large current value a2 (a2 > a1) that does not go through the resistor R.

[0033] Here, as shown in Figure 3, the portion of the pressure sensor 10 in the longitudinal direction in which the first electrode wires 21 to the fourth electrode wires 24 are arranged in a four-strand helical structure, that is, the portion corresponding to the outer sheath 11 in Figure 3, is a detection unit that can be elastically deformed upon contact with an obstacle.

[0034] The current detection unit 18 is connected to the in-vehicle controller, which can detect when an obstacle has come into contact with the pressure sensor 10 by detecting a change in current value from a small value a1 to a large value a2. When the in-vehicle controller detects the detection signal (increase in current value) from the pressure sensor 10 and determines that an obstacle has come into contact with the pressure sensor 10, it immediately reverses the rotation direction of the electric motor. As a result, the sliding door, which is in the closing operation, opens, preventing the obstacle from getting caught.

[0035] Furthermore, a base-end cap 19 made of an insulator such as transparent rubber is provided at the base-end terminal portion 16. The base-end cap 19 covers the first conductive wires 21a to the fourth conductive wires 24a and the resistor R.

[0036] Furthermore, the base end cap 19 is filled with an insulating ultraviolet-curing resin (sealant), similar to the tip end cap 15. As a result, the first conductive wires 21a to the fourth conductive wires 24a and the resistor R do not short-circuit with each other at the base end portion 16.

[0037] <Manufacturing method for pressure-sensitive sensors> Next, the manufacturing method of the pressure sensor 10 formed as described above, and in particular the assembly procedure of the tip end portion 13 (see Figures 5 and 6), will be explained using Figures 7 to 12.

[0038] Figure 7 shows the workpiece preparation process and the outer sheath cutting process. Figure 8 shows the conductive wire exposure process. Figure 9 shows the short-circuit wire welding process. Figure 10 shows the clamping process. Figure 11 shows the conductive wire twisting process. Figure 12 shows the end material separation process.

[0039] <Work preparation process> First, a long workpiece W cut to a predetermined length is prepared, as shown in Figure 7. Here, the workpiece W has a hollow section 12 and first to fourth electrode wires 21 to 4th electrode wires 24 inside the outer shell 11, as shown in Figures 1 and 2. Furthermore, the term "workpiece W" refers to the state before processing the terminal portions at the longitudinal front end and longitudinal base end.

[0040] The workpiece W is formed into a long length by extruding a flexible insulating material, which will form the outer sheath 11, together with the first to fourth electrode wires 21 to 24 using an extrusion molding machine.

[0041] <Outer skin cutting process> Next, as shown in Figure 7, a pair of cutting blades 31 forming the wire stripper 30 are positioned at a predetermined distance L from one longitudinal side of the workpiece W. Then, as indicated by arrow m1, the pair of cutting blades 31 are moved from the radially outer side of the workpiece W toward each other. Then, cuts are made on the outer circumference of the workpiece W to a depth that reaches the first conductive wire 21a to the fourth conductive wire 24a (see Figures 1 and 2).

[0042] This allows cuts to be made in the outer sheath 11 and the first conductive rubber 21b to the fourth conductive rubber 24b (see Figures 1 and 2) without cutting the first conductive wires 21a to the fourth conductive wires 24a. As a result, the outer sheath 11 and the first conductive rubber 21b to the fourth conductive rubber 24b can be separated into the main body W1 and the end material W2 in the longitudinal direction (see Figure 8). Note that the outer sheath cutting step corresponds to the cable-like insulator cutting step in the present invention.

[0043] <Conductive wire exposure process> Next, as shown in Figure 8, the first conductive wire 21a to the fourth conductive wire 24a are partially exposed between the main body W1 and the end material W2. Specifically, the main body W1 and the end material W2 are slowly pulled apart in the longitudinal direction of the workpiece W, as indicated by arrow m2. This partially exposes the first conductive wire 21a to the fourth conductive wire 24a between the main body W1 and the end material W2.

[0044] At this time, since the first conductive wire 21a to the fourth conductive wire 24a are each arranged spirally around the outer sheath 11, it is preferable to separate the main body W1 and the end material W2 while rotating them relative to each other around their axis AC. This avoids applying large tension in the longitudinal direction to each of the first conductive wire 21a to the fourth conductive wire 24a.

[0045] Subsequently, the cutting points P1 of the first and third conductive wires 21a and 23a are cut using a cutting tool 32 such as scissors. As a result, the length dimension of the first and third conductive wires 21a and 23a exposed from the outer sheath 11 on one longitudinal side of the main body W1 (right side in Figure 8) becomes L2 (see Figures 5 and 6).

[0046] <Short-circuit wire welding process> Next, as shown by arrow m3 in Figure 9, the first and third conductive wires 21a and 23a on the end portion W2 side are bent at approximately a right angle. This creates a relatively wide space 33 on the tip side (right side in Figure 9) of the first and third conductive wires 21a and 23a on the main body portion W1 side. By providing this space 33, the welding work of the short-circuit wire WL and the subsequent conductive wire twisting process (see Figure 11) can be easily carried out.

[0047] Next, the short-circuit wire WL is positioned to span the first conductive wire 21a and the third conductive wire 23a, and the welding tool 34 is positioned facing the short-circuit wire WL. Then, both longitudinal sides of the short-circuit wire WL are fixed to the first conductive wire 21a and the third conductive wire 23a, respectively. As a result, the first and third conductive wires 21a and 23a become electrically conductive with each other via the short-circuit wire WL.

[0048] Furthermore, at the welded portion of the short-circuit wire WL, the first and third conductive rubbers 21b and 23b are peeled off to expose the first and third conductive wires 21a and 23a. This ensures sufficient fixing strength of the short-circuit wire WL to the first and third conductive wires 21a and 23a.

[0049] Here, the lower diagram in Figure 9 shows the main body W1 and the end material W2 rotated 90 degrees around their axis AC relative to the upper diagram in Figure 9.

[0050] <Clamping process> Next, as shown in Figure 10, the workpiece W is positioned between the pair of claws 36 of the clamping device 35. Specifically, in the longitudinal direction of the workpiece W, the workpiece W is positioned near the short-circuit wire WL and with the end portion W2 side of the short-circuit wire WL (right side in Figure 10) between the pair of claws 36. The workpiece W is positioned such that the direction of movement of the pair of claws 36 is perpendicular to the direction of alignment of the second and fourth conductive wires 22a and 24a (depth direction in Figure 10) (up and down direction in Figure 10).

[0051] Subsequently, as indicated by arrow m4, the pair of claws 36 are moved closer to each other, and the second and fourth conductive wires 22a and 24a are clamped by the pair of claws 36. As a result, the second and fourth conductive wires 22a and 24a are fixed between the pair of claws 36 so that the distance between them does not change.

[0052] <Conductive wire twisting process> Next, as shown in Figure 11, a spiral conductive wire twist 14 is formed on the end portion W2 side of the pair of claws 36 in the longitudinal direction of the workpiece W. Specifically, with the second and fourth conductive wires 22a and 24a clamped by the pair of claws 36, the end portion W2 is rotated around axis AC relative to the main body W1, as indicated by arrow m5. As a result, the second and fourth conductive wires 22a and 24a exposed from the outer sheath 11 are twisted together and made electrically conductive contact with each other.

[0053] As a result, a conductive wire twisted portion 14 is formed on the end material portion W2 side of the pair of claws 36 in the longitudinal direction of the workpiece W. In this embodiment, the end material portion W2 is twisted five times with respect to the main body portion W1. Note that the conductive wire twisting process corresponds to the conductive wire contact portion formation process in the present invention.

[0054] <Scrap material separation process> Next, as shown in Figure 12, the cutting points P2 of the second and fourth conductive wires 22a and 24a are cut using the cutting tool 32. Specifically, the cutting points P2 are located in the longitudinal direction of the second and fourth conductive wires 22a and 24a on the side where the end material portion W2 is provided, rather than on the conductive wire twisted portion 14, and are located in the vicinity of the conductive wire twisted portion 14. This separates the end material portion W2 from the main body portion W1.

[0055] <Sealing process> Next, the tip cap 15 is attached to one longitudinal side of the main body W1 (the right side in Figures 5 and 6), and the inside of the tip cap 15 is filled with ultraviolet-curing resin RS. Then, the tip cap 15 is irradiated with ultraviolet light using an ultraviolet irradiator to cure the ultraviolet-curing resin RS. As a result, the conductive wire twisted portion 14 on one longitudinal side of the main body W1 is sealed with ultraviolet-curing resin RS, and the assembly of the tip terminal portion 13 of the pressure sensor 10 is completed.

[0056] As described in detail above, the pressure sensor 10 of Embodiment 1 comprises a hollow outer sheath 11, first conductive wires 21a to fourth conductive wires 24a provided inside the outer sheath 11 and capable of conducting electricity with each other due to the elastic deformation of the outer sheath 11, and a conductive wire twisted portion 14 provided on one side in the longitudinal direction of the outer sheath 11, formed by bringing the second and fourth conductive wires 22a and 24a into contact with each other.

[0057] This eliminates the need for a short-circuit wire to connect the second and fourth conductive wires 22a and 24a in a conductive manner, and also eliminates the welding work required to connect the short-circuit wire. Therefore, it is possible to improve the assembly workability of the pressure sensor 10. In addition, since the number of welding points can be reduced, the occurrence of welding defects can be suppressed.

[0058] Furthermore, the pressure sensor 10 of Embodiment 1 has a conductive wire twisted portion 14 formed by twisting one side in the longitudinal direction of the second and fourth conductive wires 22a and 24a.

[0059] As a result, by simply rotating the end piece W2 relative to the main body W1 around the axis AC, the second and fourth conductive wires 22a and 24a can be brought into direct contact and reliably made electrically connected to each other.

[0060] Furthermore, according to the pressure sensor 10 of Embodiment 1, the conductive wire twisted portion 14 is sealed with an insulating ultraviolet curing resin RS.

[0061] This ensures that the pair of first and third conductive wires 21a, 23a, the pair of second and fourth conductive wires 22a, 24a, the short-circuit wire WL, and the conductive wire twisted portion 14 do not short-circuit with each other.

[0062] <Embodiment 2> Next, Embodiment 2 of the present invention will be described in detail with reference to the drawings. Parts having the same function as those in Embodiment 1 described above will be denoted by the same symbols, and their detailed descriptions will be omitted.

[0063] Figure 13 is a diagram corresponding to Figure 6, showing the pressure sensor of Embodiment 2. Figure 14 is a diagram showing the conductive wire welding process.

[0064] As shown in Figure 13, the pressure sensor 40 of Embodiment 2 has a different structure in the tip end portion 41 compared to the pressure sensor 10 of Embodiment 1 (see Figure 6). Specifically, the tip end portion 41 of Embodiment 2 is provided with a conductive wire welding portion 42 instead of the conductive wire twisted portion 14 of Embodiment 1 (see Figure 6).

[0065] Specifically, the conductive wire welding portion 42 is provided on one longitudinal side of the outer sheath portion 11 (the right side in Figure 13), and is formed by bringing the second and fourth conductive wires 22a and 24a, exposed from the outer sheath portion 11, into contact with each other. The conductive wire welding portion 42 corresponds to the conductive wire contact portion in the present invention.

[0066] The conductive wire welded portion 42 is formed by combining one longitudinal side of a pair of second and fourth conductive wires 22a and 24a and welding them together, thereby enabling electrical conductivity between them. Specifically, the conductive wire welded portion 42 is formed through the conductive wire welding process shown below. Note that the conductive wire welding process is performed in place of the conductive wire twisting process in Embodiment 1 (see Figure 11).

[0067] <Conductive wire welding process> As shown in Figure 14, in the conductive wire welding process, a conductive wire welded portion 42 is formed on the end material portion W2 side of the pair of claws 36 in the longitudinal direction of the workpiece W using a welding device 50. Here, the welding device 50 is a resistance welding machine and is equipped with a pair of electrode members 51. Here, the direction of movement of the pair of electrode members 51 is perpendicular to the direction of movement of the pair of claws 36.

[0068] Then, as shown in Figure 14, with the second and fourth conductive wires 22a and 24a clamped by the pair of claws 36, the pair of electrode members 51 are moved closer together as indicated by arrow m6. As a result, the end portions W2 of the second and fourth conductive wires 22a and 24a exposed from the outer sheath 11 are clamped by the pair of electrode members 51 and come into contact with each other.

[0069] Next, an electric current is passed through the pair of electrode members 51. As a result, the contact portions of the second and fourth conductive wires 22a and 24a are heated and melted, thereby forming a conductive wire welded portion 42. The conductive wire welding process corresponds to the conductive wire contact portion formation process in the present invention. Here, in the conductive wire welding process, the contact portions of the second and fourth conductive wires 22a and 24a may be welded not only by resistance welding as described above, but also by, for example, ultrasonic welding.

[0070] In the pressure sensor 40 of Embodiment 2, formed as described above, the short-circuit wires connecting the second and fourth conductive wires 22a and 24a to each other can be eliminated, similar to Embodiment 1 described above. Therefore, the assembly workability of the pressure sensor can be improved. In Embodiment 2, the conductive wire welded portion 42 is formed by welding one longitudinal side of the pair of second and fourth conductive wires 22a and 24a to each other. Therefore, the second and fourth conductive wires 22a and 24a can be made to conduct electricity more reliably.

[0071] <Embodiment 3> Next, Embodiment 3 of the present invention will be described in detail with reference to the drawings. Parts having the same function as those in Embodiment 1 described above will be denoted by the same symbols, and their detailed descriptions will be omitted.

[0072] Figure 15 is a diagram corresponding to Figure 4, showing the pressure sensor of Embodiment 3. Figure 16 is a view taken along arrow C in Figure 15. Figure 17 is a view taken along arrow D in Figure 15. Figure 18 is a diagram showing the first conductive wire twisting process. Figure 19 is a diagram showing the second conductive wire twisting process.

[0073] As shown in Figures 15 to 17, the structure of the tip end portion 61 of the pressure sensor 60 of Embodiment 3 differs from that of the pressure sensor 10 of Embodiment 1 (see Figures 4 to 6). Specifically, in the tip end portion 61 of Embodiment 3, the short-circuit wire WL used in Embodiment 1 is eliminated, and a conductive wire twisted portion 62 is also provided on one longitudinal side (the right side in Figures 16 and 17) of the pair of first and third conductive wires 21a and 23a. That is, the tip end portion 61 of Embodiment 3 is provided with a pair of conductive wire twisted portions 14 and 62 (one conductive wire twisted portion 14 and the other conductive wire twisted portion 62).

[0074] Specifically, the other conductive wire twisted portion 62 is provided on one longitudinal side (right side in the figure) of the pair of first and third conductive wires 21a and 23a, and is formed by twisting the first and third conductive wires 21a and 23a exposed from the outer sheath portion 11 together. The other conductive wire twisted portion 62 corresponds to the conductive wire contact portion in the present invention.

[0075] The other conductive wire twisted portion 62 is formed through the first conductive wire twisting process shown in Figure 18. The other conductive wire twisted portion 14 is formed through the second conductive wire twisting process shown in Figure 19. The manufacturing method of the pressure sensor 60 of Embodiment 3 will now be described, in particular the assembly procedure of the tip end portion 61 (see Figures 16 and 17).

[0076] In addition, in the process preceding the first conductive wire twisting process, the workpiece preparation process, the outer sheath cutting process, the conductive wire exposure process, and the clamping process are performed in the same manner as in Embodiment 1 described above. However, in the conductive wire exposure process of Embodiment 3, the main body W1 and the end material W2 (see Figure 8) are separated from each other, and the first conductive wires 21a to the fourth conductive wires 24a are partially exposed. Then, all of the first conductive wires 21a to the fourth conductive wires 24a are cut, and the end material W2 is separated from the main body W1.

[0077] Specifically, as shown in the left-hand diagram of Figure 18, the cutting tool 32 is used to cut the first and third conductive wires 21a and 23a so that their exposed portions are the same length. The cutting tool 32 is also used to cut the second and fourth conductive wires 22a and 24a so that their exposed portions are the same length. The length of the exposed portions of the second and fourth conductive wires 22a and 24a is approximately twice the length of the exposed portions of the first and third conductive wires 21a and 23a.

[0078] Subsequently, as indicated by arrow m7, the exposed bases of the second and fourth conductive wires 22a and 24a are bent 90 degrees in opposite directions (up and down in the diagram). This makes it possible to perform the twisting operation (first conductive wire twisting process) on the exposed portions of the first and third conductive wires 21a and 23a.

[0079] Furthermore, in the clamping process of Embodiment 3, as shown in the right-hand diagram of Figure 18, the bases of the exposed portions of the first and third conductive wires 21a and 23a are clamped by a pair of claws 36. As a result, the first and third conductive wires 21a and 23a are fixed between the pair of claws 36 so that the distance between them does not change.

[0080] <First Conductive Wire Twisting Process> Next, with the first and third conductive wires 21a and 23a clamped by the pair of claws 36, the ends of the first and third conductive wires 21a and 23a (right side in Figure 18) are twisted together around axis AC and brought into contact with each other, as shown by arrow m8.

[0081] As a result, as shown in Figure 19, a conductive wire twisted portion 62 is formed on the exposed portions of the first and third conductive wires 21a and 23a. The other conductive wire twisted portion 62 is formed by twisting the tip ends of the first and third conductive wires 21a and 23a five times. The first conductive wire twisting step corresponds to the conductive wire contact portion formation step in the present invention.

[0082] <Second Conductive Wire Twisting Process> Next, as shown by arrow m9 in the left-hand diagram of Figure 19, the second and fourth conductive wires 22a and 24a, which were bent 90 degrees in opposite directions, are returned to their original positions along axis AC. Then, as shown in the right-hand diagram of Figure 19, the second and fourth conductive wires 22a and 24a are clamped by a pair of claws 36. This fixes the second and fourth conductive wires 22a and 24a between the pair of claws 36 so that their distance from each other does not change.

[0083] Then, with the second and fourth conductive wires 22a and 24a clamped, the ends of the second and fourth conductive wires 22a and 24a (right side of Figure 19) are twisted together around axis AC and brought into contact with each other, as shown by arrow m10 in the right side of Figure 19.

[0084] As a result, as shown in Figures 16 and 17, one of the conductive wire twisted portions 14 is formed on the exposed portions of the second and fourth conductive wires 22a and 24a. The second conductive wire twisting step corresponds to the conductive wire contact portion formation step in the present invention.

[0085] Here, the diagram on the right in Figure 19 shows the same diagram as the one on the left in Figure 19, rotated 90 degrees around axis AC.

[0086] The pressure sensor 60 of Embodiment 3, formed as described above, can achieve the same effects as Embodiment 1 described above. In addition, in Embodiment 3, the short-circuit wire can be completely eliminated. Therefore, the number of parts can be further reduced. Furthermore, welding work and equipment can be eliminated. Moreover, since welding points can be eliminated, the occurrence of welding defects can be eliminated, and reliability can be further improved.

[0087] <Embodiment 4> Next, Embodiment 4 of the present invention will be described in detail with reference to the drawings. Parts having the same function as those in Embodiment 1 described above will be denoted by the same symbols, and their detailed descriptions will be omitted.

[0088] Figure 20 is a diagram corresponding to Figure 3, which shows the pressure sensor of Embodiment 4.

[0089] As shown in Figure 20, the pressure sensor 70 of Embodiment 4 differs from the pressure sensor 10 of Embodiment 1 (see Figures 1 to 3) in that it comprises only a pair of electrode wires 71 and 72.

[0090] The pair of electrode wires 71 and 72 are all of the same structure. Each pair of electrode wires 71 and 72 is provided with conductive wires 71a and 72a made by twisting thin copper wires together, and conductive rubber 71b and 72b that covers a portion of the conductive wires 71a and 72a along their longitudinal direction (the portion corresponding to the detection part).

[0091] These electrode wires 71 and 72 are provided radially inside the outer sheath 11 and around the hollow portion 73. The pair of electrode wires 71 and 72 are positioned facing each other radially in the outer sheath 11 and extend spirally in the longitudinal direction of the outer sheath 11. Here, the pair of electrode wires 71 and 72 are non-contacting each other radially inside the outer sheath 11 and are arranged in a double-helix structure.

[0092] Then, when an external force F is applied to the outer sheath 11, the outer sheath 11 is elastically deformed, and as a result, the pair of electrode wires 71 and 72 come into contact (short-circuit) with each other on the radially inner side of the outer sheath 11. Here, the resistance value r1 of the entire conductive wire formed by connecting the conductive wires 71a and 72a in series is greater than the resistance value r2 of the respective conductive rubbers 71b and 72b (r1 > r2). The conductive rubbers 71b and 72b are made of, for example, silicone rubber containing carbon black or metal powder.

[0093] Therefore, when the pair of conductive rubbers 71b and 72b are not in contact with each other, the current detection unit 18 detects the current value a3 flowing through the entire long conductive wire formed by connecting the conductive wires 71a and 72a in series. In contrast, when an external force F is applied to the outer sheath 11 and the outer sheath 11 is elastically deformed, the pair of conductive wires 71a and 72a are short-circuited (conductive) with each other via the conductive rubbers 71b and 72b.

[0094] As a result, current flows through the conductive rubber 71b and 72b with a small resistance value r2, and the current detection unit 18 detects a current value a4 (a4 > a3) that is greater than the current value a3. Therefore, the in-vehicle controller can detect the increase from current value a3 to current value a4 and understand that an obstacle has come into contact with the pressure sensor 70.

[0095] As shown in Figure 20, the tip end portion 74 of the pressure sensor 70 is provided with a conductive wire twisted portion 75, which is formed by twisting together one longitudinal side of a pair of conductive wires 71a and 72a exposed from the outer sheath portion 11 into a spiral shape. The conductive wire twisted portion 75 is formed in the same way as the conductive wire twisted portion 14 of Embodiment 1 (see Figure 5). The conductive wire twisted portion 75, which is formed by bringing the pair of conductive wires 71a and 72a into contact with each other, corresponds to the conductive wire contact portion in the present invention.

[0096] Furthermore, the conductive wire twisted portion 75 is also covered with ultraviolet curing resin RS and a tip-side cap 15, similar to the conductive wire twisted portion 14 in Embodiment 1. In addition, the tip-side terminal portion 74 of the pressure sensor 70 is assembled in substantially the same manner as in Embodiment 1, except for the short-circuit wire welding process in Embodiment 1.

[0097] The pressure sensor 70 of Embodiment 4, formed as described above, can achieve the same effects as those of Embodiment 1. In addition, in Embodiment 4, the number of electrode wires can be halved compared to Embodiment 1, making it possible to reduce the diameter and weight of the pressure sensor 70. Furthermore, it becomes possible to simplify the electrical circuit, which in turn can further improve durability.

[0098] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention. In the embodiments described above, the multiple electrode wires are shown in a 4-strand helix structure and a 2-strand helix structure, but the present invention is not limited to these, and depending on the application of the pressure sensor, a 6-strand helix structure or an 8-strand helix structure (2 × n-strand helix structure) may also be used.

[0099] Furthermore, in the above-described embodiments 1 to 3, the first electrode wires 21 to 4th electrode wires 24 are shown to consist of first conductive wires 21a to 4th conductive wires 24a and first conductive rubber 21b to 4th conductive rubber 24b. However, the present invention is not limited to this, and the first conductive rubber 21b to 4th conductive rubber 24b may be omitted, and the first conductive wires 21a to 4th conductive wires 24a may be provided radially inward of the outer sheath portion 11 so as to be electrically conductive to one another.

[0100] Furthermore, in the above-described embodiment 1, the first and third conductive wires 21a and 23a are connected to each other via a short-circuit wire WL, and the second and fourth conductive wires 22a and 24a are provided with a conductive wire twist 14, and these second and fourth conductive wires 22a and 24a are in direct contact with each other. However, the present invention is not limited to this. Conversely, the first and third conductive wires 21a and 23a may be provided with a conductive wire twist, these first and third conductive wires 21a and 23a may be in direct contact with each other, and the second and fourth conductive wires 22a and 24a may be connected to each other via a short-circuit wire.

[0101] Furthermore, in the above-described embodiment 2, the first and third conductive wires 21a and 23a are connected to each other via a short-circuit wire WL, and conductive wire welding portions 42 are provided on the second and fourth conductive wires 22a and 24a, and these second and fourth conductive wires 22a and 24a are in direct contact with each other. However, the present invention is not limited to this. Conversely to the above, conductive wire welding portions may be provided on the first and third conductive wires 21a and 23a, these first and third conductive wires 21a and 23a may be in direct contact with each other, and the second and fourth conductive wires 22a and 24a may be connected to each other via a short-circuit wire.

[0102] Furthermore, while the above-described embodiment 3 shows that the first and third conductive wires 21a, 23a and the second and fourth conductive wires 22a, 24a are each provided with conductive wire twisted portions 62, 14, the present invention is not limited to this, and conductive wire welded portions may also be provided on each of the first and third conductive wires 21a, 23a and the second and fourth conductive wires 22a, 24a.

[0103] Furthermore, while Embodiment 4 described above shows a conductive wire twisted portion 75 provided on one side in the longitudinal direction of a pair of conductive wires 71a, 72a, the present invention is not limited to this, and a conductive wire welded portion may be provided instead of the conductive wire twisted portion 75.

[0104] Furthermore, while the above-described embodiments show the pressure sensors 10, 40, 60, and 70 being mounted on the sliding doors of vehicles such as automobiles and used to detect obstructions getting caught, the present invention is not limited to this. For example, it can also be used to detect obstructions getting caught in automatic doors of buildings or elevator doors.

[0105] Furthermore, the material, shape, dimensions, number, and installation location of each component in the above-described embodiments are arbitrary as long as they can achieve the present invention, and are not limited to the above-described embodiments. [Explanation of Symbols]

[0106] 10...Pressure sensor, 11...Outer sheath (cable-shaped insulator), 12...Hollow section, 13...Tip end section, 14...Conductive wire twisted section (conductive wire contact section), 15...Tip end cap, 16...Base end section, 17a...Positive terminal, 17b...Negative terminal, 18...Current detection section, 19...Base end cap, 21...First electrode wire, 21a...First conductive wire, 21b...First conductive rubber, 22...Second electrode wire, 22a...Second conductive wire, 22b...Second conductive rubber, 23...Third electrode wire, 23a...Third conductive wire, 23b...Third conductive rubber, 24...Fourth electrode wire, 24a...Fourth conductive wire, 24b...Fourth conductive rubber, 30...Wire stripper, 31...Cutting blade, 32...Cutting tool, 33...Space, 3 4...Welding tool, 35...Clamping device, 36...Claw, 40...Pressure sensor, 41...Tip end, 42...Conductive wire welding part (conductive wire contact part), 50...Welding device, 51...Electrode member, 60...Pressure sensor, 61...Tip end, 62...Conductive wire twisted part (conductive wire contact part), 70...Pressure sensor, 71, 72...Electrode wire, 71a, 72a...Conductive wire, 71b, 72b...Conductive rubber, 73...Hollow part, 74...Tip end, 75...Conductive wire twisted part (conductive wire contact part), AC...Axis wire, BT...Power supply, F...External force, P1, P2...Cutting point, R...Resistor, r1, r2...Resistance value, RS...UV curing resin (sealant), W...Workpiece, W1...Main body, W2...Skip part, WL...Short circuit wire

Claims

1. A pressure-sensitive sensor that is elastically deformable upon contact with an obstacle, A hollow cable-like insulator, A pair of conductive wires are provided inside the cable-like insulator, and are electrically conductive to each other due to the elastic deformation of the cable-like insulator, A conductive wire contact portion is provided on one longitudinal side of the cable-like insulator, and the pair of conductive wires are in contact with each other. Equipped with, Pressure sensor.

2. The conductive wire contact portion is a conductive wire twisted portion formed by twisting one longitudinal side of the pair of conductive wires. The pressure sensor according to claim 1.

3. The conductive wire contact portion is a conductive wire welded portion formed by welding one longitudinal side of the pair of conductive wires together. The pressure sensor according to claim 1.

4. The conductive wire contact portion is sealed with an insulating sealing material. The pressure sensor according to claim 1.

5. A method for manufacturing a pressure-sensitive sensor that can be elastically deformed upon contact with an obstacle, A workpiece preparation step involves preparing a workpiece consisting of a hollow cable-like insulator and a pair of conductive wires provided inside the cable-like insulator, A cable-like insulator cutting step, which involves making an incision in the cable-like insulator so that the cable-like insulator can be separated into a main body portion and an end portion in the longitudinal direction thereof, A conductive wire exposure step involves separating the main body portion and the end portion from each other and exposing the pair of conductive wires between the main body portion and the end portion, A conductive wire contact portion forming step, in which the exposed pair of conductive wires are brought into contact with each other to form a conductive wire contact portion, Having, A method for manufacturing a pressure-sensitive sensor.

6. In the conductive wire contact portion formation step, the pair of exposed conductive wires are twisted together to form the conductive wire twisted portion which serves as the conductive wire contact portion. A method for manufacturing a pressure-sensitive sensor according to claim 5.

7. In the conductive wire contact portion formation step, the pair of exposed conductive wires are welded together to form the conductive wire welded portion, which serves as the conductive wire contact portion. A method for manufacturing a pressure-sensitive sensor according to claim 5.

8. After the conductive wire contact portion formation step, a sealing step is performed in which the conductive wire contact portion is sealed with an insulating sealing material. A method for manufacturing a pressure-sensitive sensor according to claim 5.

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