Conductive fabric, steering wheel equipped with conductive fabric, and method for manufacturing the steering wheel.

Abstract

To provide a conductive fabric that can suppress the decrease in sensor sensitivity at the suture site. [Solution] A conductive fabric used in a steering wheel mounted on a moving object, comprising a conductive woven fabric composed of woven yarn including crimped yarn, wherein the density of the woven fabric at a position corresponding to the seam of the steering wheel surface when attached to the steering wheel is higher than the density of the woven fabric at a position corresponding to the surface area excluding the seam.

Description

Technical Field

[0001] The present disclosure relates to a conductive fabric, a steering wheel equipped with the conductive fabric, and a method for manufacturing the steering wheel.

Background Art

[0002] Steering wheels equipped with sensors for detecting gripping by occupants have been variously proposed. For example, Patent Document 1 discloses a steering wheel provided with a sensor layer including a knitted fabric having conductivity. The sensor layer is covered with an epidermis.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The epidermis is fixed by stitching the ends of the epidermis members together and covers the sensor layer. The stitching portion is thicker than other portions of the epidermis in order to secure a seam allowance. Therefore, the sensitivity of the sensor for gripping detection at the stitching portion may decrease.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms.

[0006] According to one aspect of the present disclosure, a conductive fabric for use in a steering wheel mounted on a moving body is provided. This conductive fabric is composed of woven yarns including crimped yarns, includes a woven fabric having conductivity, and the density of the woven fabric at a position corresponding to the stitching portion of the epidermis of the steering wheel in a state where it is attached to the steering wheel is higher than the density of the woven fabric at a position corresponding to the portion of the epidermis excluding the stitching portion. With this form of conductive fabric, the density of the woven fabric at the location corresponding to the suture is higher than the density of the woven fabric at the location corresponding to the epidermal portion excluding the suture, thus suppressing the decrease in sensor sensitivity at the suture. Furthermore, since the woven fabric is composed of yarns that include crimped yarn, it is more elastic than a fabric composed of yarns that do not include crimped yarn. This makes it easy to create density differences in the conductive fabric, and to easily increase the density of the fabric at the location corresponding to the seam. Furthermore, since conductive fabric includes woven fabric, it can suppress deformation of the conductive fabric compared to conductive fabric composed solely of knitted fabric without woven fabric.

[0007] This disclosure can be implemented in various forms. For example, it can be implemented in the form of a steering wheel equipped with conductive fabric, a mobile body equipped with the steering wheel, or a method for manufacturing the steering wheel. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view of the steering wheel in one embodiment of the present disclosure. [Figure 2] This is a cross-sectional view of the rim portion cut along line II-II in Figure 1. [Figure 3] This is a flowchart showing the steps for manufacturing a steering wheel. [Modes for carrying out the invention]

[0009] A. Embodiments: A1. Equipment configuration: Figure 1 is a front view of a steering wheel 100 in one embodiment of the present disclosure. The X, Y, and Z axes shown in the figure are axes that intersect each other at 90-degree angles. In this embodiment, the Y axis is parallel to the left-right direction of the vehicle, and the Z axis is parallel to the rotation axis 101. The steering wheel 100 in this embodiment is mounted on a vehicle and used to indicate the direction of travel of the vehicle. The steering wheel 100 comprises a hub portion 110, a rim portion 120, and spoke portions 130. The hub portion 110 is located at the center of the steering wheel 100 when viewed from the front and is connected to the rotation axis 101 of the vehicle. The rim portion 120 is provided so as to surround the hub portion 110. The rim portion 120 is held by the occupant who steers the vehicle. In this embodiment, the rim portion 120 has an annular external shape. The spoke portions 130 connect the hub portion 110 and the rim portion 120 to each other. Functional components such as switches are provided on the spoke portion 130.

[0010] Figure 2 is a cross-sectional view of the rim portion 120 cut along the line II-II in Figure 1. The rim portion 120 comprises a rim body 200, a conductive fabric 300, and a surface layer 400.

[0011] The rim body 200 has a rim core 210 and a cushion portion 220. The rim core 210 is the skeleton of the rim portion 120. The rim core 210 has a U-shape in a cross-section that is parallel to and passes through the rotation axis 101, and protrudes toward the outer circumference of the steering 100 (away from the rotation axis 101). The rim core 210 is made of metal. The cushion portion 220 covers the rim core 210. In this disclosure, "covers" means both when the members are in contact with each other and when another member is sandwiched between the members. That is, the cushion portion 220 and the rim core 210 may be in direct contact, or any member such as an adhesive member may be sandwiched between the cushion portion 220 and the rim core 210. The cushion portion 220 is made of an elastic material such as urethane. The cushion portion 220 is molded, for example, by the RIM (Reaction Injection Molding) method.

[0012] The conductive fabric 300 covers the rim body 200. The conductive fabric 300 is an electrode of a sensor that detects when an occupant grips the rim portion 120. In this disclosure, "detecting grip" means detecting not only when the occupant is gripping the rim portion 120, but also when the occupant's hand is close enough to touch the rim portion 120. The conductive fabric 300 includes a conductive woven fabric 310. Before being attached to the rim body 200, the woven fabric 310 has a rectangular, sheet-like appearance. The woven fabric 310 is composed of woven yarns, including crimped yarns. The woven fabric 310 becomes conductive by being plated. The woven fabric 310 may also become conductive by using conductive yarns as woven yarns. The woven fabric 310 is electrically connected to an ECU mounted in the vehicle via a harness.

[0013] The crimped yarn is preferably a heat-processed multifilament yarn. Heat processing allows for the formation of finer crimps, resulting in a crimped yarn with bulkiness, elasticity, and resilience. By using such a crimped yarn, the elasticity of the woven fabric 310 can be enhanced.

[0014] Furthermore, the crimped yarn preferably has a breaking elongation of 10% or more, more preferably 15% or more, and even more preferably 20% or more. The breaking elongation can be determined as follows: In accordance with JIS L1013, a tensile testing machine (AG-I / 20kN-50kN Autograph manufactured by Shimadzu Corporation) is used to measure the sample yarn length at 20 cm and a constant tensile speed of 20 cm / min. The sample yarn length (cm) at which the maximum load value is shown on the load-elongation curve is determined. The elongation rate (%) is calculated by dividing this yarn length by the sample yarn length (20 cm) before the load is applied. These tests are repeated 5 times, and the average value of the 5 measurements is obtained. This average value is the breaking elongation (%).

[0015] The material for crimped yarn can be, for example, natural fibers, chemical fibers, synthetic fibers, or a combination thereof. Among these materials, synthetic fibers are preferred because they have relatively high resistance to plating. Polyester-based synthetic fibers are particularly preferred as synthetic fibers.

[0016] The woven fabric 310 may be of any weave pattern. The weave pattern may be, for example, plain weave, twill weave, or satin weave. Among these weave patterns, plain weave is preferred in that the tissue displacement is relatively small when stretched in the diagonal direction.

[0017] The elasticity of the woven fabric 310 is not particularly limited, but the tensile strength at 10% elongation in the warp direction and the weft direction is preferably 30 N / cm or less, more preferably 20 N / cm or less. Also, the tensile strength at 10% elongation is preferably 0.1 N / cm or more, more preferably 0.2 N / cm or more. The elasticity of the woven fabric 310 is a value measured according to Method B (Grab method) described in 8.14 of JIS L1096:2010, except that the sample width (grip width) is 10 mm. The conditions during measurement are that the testing machine is a constant speed tension type, the grip interval is 100 mm, and the tensile speed is 150 ± 10 mm / min.

[0018] The areal density of the woven fabric 310 is 2 ~230 g / m 2 preferably, and 2 ~170 g / m 2 more preferably. Also, the amount of metal deposition in plating is 2 ~60 g / m 2 preferably, and 2 ~43 g / m 2 more preferably. Also, the amount of metal deposition is preferably 10 mass% to 60 mass%, more preferably 17 mass% to 45 mass% with respect to the total mass of the woven fabric 310.

[0019] The warp density of the woven fabric 310 is preferably 50 threads / 25.4 mm to 200 threads / 25.4 mm. The weft density of the woven fabric 310 is preferably 40 threads / 25.4 mm to 200 threads / 25.4 mm. The woven fabric 310 is more preferably a plain weave having such a weave density.

[0020] The outer skin 400 covers the conductive fabric 300. The outer skin 400 is touched by the occupant gripping the rim portion 120. The outer skin 400 has an outer skin member 410 and a suture portion 420. The outer skin member 410 is, for example, a sheet of synthetic leather or natural leather. The suture portion 420 is the part where the seam allowances of the ends of the outer skin member 410 are overlapped and sewn together with thread. In this embodiment, the suture portion 420 is provided along the inner circumference of the rim portion 120 in a front view of the steering wheel 100. In this disclosure, the "inner circumference" of the rim portion 120 refers to the part of the rim portion 120 along the circumferential direction in a front view that is closer to the rotation axis 101. The "outer circumference" of the rim portion 120 refers to the part of the rim portion 120 along the circumferential direction in a front view that is farther from the rotation axis 101.

[0021] In this disclosure, the density of the woven fabric 310 at the location corresponding to the suture portion 420 is higher than the density of the woven fabric 310 at the location corresponding to the portion of the epidermis 400 excluding the suture portion 420. Here, since the woven fabric 310 is conductive, the change in charge of the woven fabric 310 at the location corresponding to the suture portion 420 is relatively large. That is, the sensitivity of the touch sensor is higher at the location corresponding to the suture portion 420 than at the location corresponding to the portion of the epidermis 400 excluding the suture portion 420.

[0022] A2. Manufacturing method of steering wheel 100: Figure 3 is a flowchart showing the procedure for manufacturing the steering wheel 100. The manufacturing of the steering wheel 100 is carried out as one step in the vehicle manufacturing process. The manufacturing of the steering wheel 100 includes a preparation step (P110) and a coating step (P120).

[0023] In the preparation step (P110), the rim body 200 and the conductive fabric 300, which includes a conductive woven fabric 310 made of woven yarn including crimped yarn, are prepared. An adhesive member is pre-attached to the side of the conductive fabric 300 that will cover the rim body 200. The adhesive member is, for example, an adhesive or double-sided tape. In the covering step (P120), the conductive fabric 300 is covered over the rim body 200 such that the density of the woven fabric 310 at the position corresponding to the seam 420 of the outer skin 400 that will cover the conductive fabric 300 on the steering wheel 100 is higher than the density of the woven fabric 310 at the position corresponding to the part of the outer skin 400 excluding the seam 420.

[0024] In this embodiment, the suture portion 420 is provided along the inner circumference of the rim portion 120 in a front view of the steering wheel 100, as shown in Figure 1. P120 in Figure 3 shows how the conductive fabric 300 is covered on the rim body 200 at a position corresponding to line II-II in Figure 1. In P120 of Figure 3, the right side of the paper is the outer circumference of the rim body 200, and the left side of the paper is the inner circumference. Therefore, the position corresponding to the suture portion 420 of the outer skin 400 is on the left side of the paper on the rim body 200, and is the central part in the vertical direction of the paper. The conductive fabric 300 is covered on the rim body 200 such that the density of the woven fabric 310 at the lower end of the paper is higher than the density of the woven fabric 310 in other parts. Specifically, as shown in the left-hand process P121 in P120 of Figure 3, the sheet-like conductive fabric 300 is arranged so that its central portion in the short direction is in contact with the outer circumference of the rim body 200. Next, as shown in step P122 on the right side of P120 in Figure 3, the portion of the conductive fabric 300 that is in contact with the outer circumference of the rim body 200 is stretched toward the inner circumference and wrapped around the rim body 200 so that both ends in the shorter direction are positioned to correspond to the suture portion 420 of the rim body 200.

[0025] In the coating process (P120), the density of the coated conductive fabric 300 is low in the stretched portion and high in the other portions. Therefore, the density of the conductive fabric 300 located on the inner circumference side of the rim body 200 is relatively high.

[0026] Following step P120, a step is performed to cover the conductive fabric 300 with the outer layer 400.

[0027] According to the steering 100 of the embodiment described above, the density of the woven fabric 310 at the position corresponding to the suture portion 420 is higher than the density of the woven fabric 310 at the position corresponding to the portion of the epidermis 400 excluding the suture portion 420, so that a decrease in sensor sensitivity at the suture portion 420 can be suppressed.

[0028] Furthermore, according to the steering 100 of this embodiment, since the woven fabric 310 is composed of yarns that include crimped yarns, the woven fabric 310 is more flexible than a configuration that does not include crimped yarns in the yarns. This makes it easy to create density differences in the woven fabric 310 within the conductive fabric 300, and makes it relatively easy to increase the density of the woven fabric 310 at the position corresponding to the seam 420.

[0029] Furthermore, according to the steering wheel 100 of this embodiment, since the conductive fabric 300 includes the woven fabric 310, it is possible to suppress deformation of the conductive fabric 300 compared to a configuration in which the conductive fabric 300 does not include the woven fabric 310 and consists only of knitted fabric.

[0030] Furthermore, according to the manufacturing method of the steering wheel 100 of the embodiment, the covering step (P120) includes a step (P121) of arranging the conductive fabric 300 along the outer circumferential surface of the rim body 200, and a step (P122) of stretching the conductive fabric 300 arranged on the outer circumferential surface toward the inner circumference so that the end of the conductive fabric 300 is positioned to correspond to the seam portion 420 of the rim body 200. This makes it easy to increase the density of the woven fabric 310 at the seam portion 420.

[0031] B. Other embodiments: (B1) In the above embodiment, the skin 400 was formed by suturing a single skin member 410 together, but the disclosure is not limited thereto. The skin 400 may be formed by suturing a plurality of skin members 410 together. Also, in the above embodiment, the suture portion 420 was provided along the inner circumference of the rim portion 120, but the disclosure is not limited thereto. The suture portion 420 may be provided in any direction on the rim portion 120. For example, the suture portion 420 may be provided along the radial direction of the steering 100.

[0032] (B2) In the above embodiment, the steering 100 may further include a heating element used for a grip heater. The heating element is provided, for example, to cover the rim body 200.

[0033] (B3) In the above embodiment, the conductive fabric 300 was used as an electrode for a touch sensor, but the disclosure is not limited thereto. The conductive fabric 300 may also be used as a heating element for a grip heater.

[0034] (B4) In the above embodiment, the rim portion 120 had an annular shape, but the disclosure is not limited thereto. The rim portion 120 may have any shape, such as a D shape or a butterfly shape.

[0035] (B5) In the above embodiment, the steering 100 may be provided on any moving body other than a vehicle. Such moving bodies include, for example, ships, airplanes, spacecraft, and so-called flying cars. Furthermore, the moving body is not necessarily limited to an object that realizes actual movement, but may also be an object that realizes virtual movement, such as a simulator.

[0036] (B6) In the above embodiment, the X-axis, Y-axis, and Z-axis may each be in a direction parallel to any other direction that is orthogonal to each other.

[0037] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0038] 100...Steering, 101...Rotation axis, 110...Hub section, 120...Rim section, 130...Spoke section, 200...Rim body, 210...Rim core metal, 220...Cushion section, 300...Conductive fabric, 310...Woven fabric, 400...Surface, 410...Surface material, 420...Suture section

Claims

1. A conductive fabric used in a steering system mounted on a moving object, It comprises a woven fabric composed of crimped yarn and having conductivity. In the state in which it is attached to the steering wheel, the density of the woven fabric at the position corresponding to the seam of the steering wheel's surface is higher than the density of the woven fabric at the position corresponding to the portion of the surface excluding the seam. Conductive fabric.

2. A steering wheel equipped with the conductive fabric described in claim 1.

3. A method for manufacturing a steering wheel having a rim portion that is grasped by the occupant of a moving vehicle, A preparation step to prepare the rim body and a conductive fabric including a woven fabric made of crimped yarn and having conductivity, A covering step of covering the rim body with the conductive fabric such that the density of the woven fabric at the position corresponding to the seam of the surface covering the conductive fabric in the steering wheel is higher than the density of the woven fabric at the position corresponding to the part of the surface covering excluding the seam, A method for manufacturing a steering wheel, comprising the features described above.

4. A method for manufacturing a steering wheel according to claim 3, The suture portion is provided along the inner circumference of the rim portion, The coating process is as follows: The steps include: arranging the conductive cloth along the outer circumferential surface of the rim body; A step of stretching the conductive fabric, which is positioned on the outer surface, toward the inner circumference so that both ends of the conductive fabric are positioned at locations corresponding to the stitched portion of the rim body, A method for manufacturing a steering wheel, including the method described above.

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