JP6642703B2 - Manufacturing method of steering wheel - Google Patents

Description

  The present invention relates to a steering wheel that detects whether or not a driver is holding the steering wheel, and a method of manufacturing the steering wheel.

  2. Description of the Related Art There is known a steering wheel in which a capacitance sensor is attached to a steering wheel of an automobile and detects whether a driver is holding the steering wheel.

  Patent Document 1 discloses a capacitance sensor mounted on a steering core, a flexible substrate having an insulating property, and a steering device provided on the flexible substrate and mounted on the steering core. And a plurality of capacitance detection electrodes that are arranged side by side in the circumferential direction of the steering core with the direction in which the wheel extends as an axis and are formed so as to extend in the direction in which the wheel extends. I have.

  In the steering wheel of Patent Document 1, the capacitance sensor is covered with a cushioning material, and the cushioning material is covered with leather (steering skin) in order to reduce unevenness of the wheel surface caused by disposing the capacitance sensor on the steering core. ing. However, there is a problem that the presence of the cushioning material under the leather lowers the surface hardness of the steering wheel. If no cushioning material is used, the surface hardness can be increased, but unevenness due to the capacitance sensor appears on the leather, which impairs the appearance of the design surface.

JP-A-2015-147531 JP 2013-90834 A JP-A-5-310130 JP 2011-219084 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a steering wheel to which a sensor is mounted, which maintains a surface hardness and which is excellent in design, and a method for manufacturing the same.

  A steering wheel according to a first aspect of the present invention is a steering wheel including a steering hub, a wheel, and a spoke extending from the steering hub and connected to the wheel, wherein the wheel is a core that surrounds the steering wheel. Gold, a foamed synthetic resin layer covering the cored bar, a sensor covering the foamed synthetic resin layer, and leather that directly covers the sensor and forms the outermost surface of the wheel portion. It has an arc shape or an annular shape extending in the circumferential direction, and has a U-shaped or C-shaped cross section.

  In one aspect of the first invention, the sensor includes a first sensor and a second sensor having a U-shaped cross section, the first sensor covering an occupant side of the synthetic resin foam layer, and the second sensor is Covers the non-occupant side of the foamed synthetic resin layer.

  In one aspect of the first invention, the outer surface of the first sensor is continuous with the outer surface of the second sensor without any steps.

  In one aspect of the first invention, the sensor includes an arc-shaped third sensor and a fourth sensor extending in the steering circling direction, and the third sensor and the fourth sensor are arranged in the steering circling direction. They are provided adjacent to each other.

  In one aspect of the first invention, the outer surface of the third sensor is continuous with the outer surface of the fourth sensor without any steps.

  In one aspect of the first invention, a plurality of arc-shaped sensors extending in the steering circling direction are provided, and the plurality of sensors are such that at least one of the ends in the steering circling direction is the wheel portion. The harness is connected to each sensor at a connection point between the sensor and the spoke portion.

  In one aspect of the first invention, a groove is provided in the foamed synthetic resin layer from a connection point between the wheel portion and the spoke portion to an end of an arc-shaped sensor extending in the steering circling direction. And a harness connected to the sensor is disposed in the groove.

  In one aspect of the first invention, the sensor has a C-shaped cross section, and a gap is provided along the circumferential direction of the steering, and the gap is located immediately below a suture thread for sewing the leather.

  In one aspect of the first invention, the sensor is a capacitance sensor.

  In one aspect of the first invention, the sensor is provided on a substrate made of a resin film, a detection circuit provided on a first surface of the substrate, and a detection circuit provided on a second surface of the substrate opposite to the first surface. Having a shield circuit.

  According to a second aspect of the present invention, there is provided a method of manufacturing a steering wheel including a steering hub, a wheel including a metal bar that surrounds the steering wheel, and a spoke extending from the steering hub and connected to the wheel. Wherein a substrate made of a resin film, a detection circuit provided on a first surface of the substrate, an insulating layer covering the detection circuit, and a second surface of the substrate opposite to the first surface are provided on the second surface. A sheet-like sensor having a shield circuit and an adhesive material covering the shield circuit is formed into an arc shape or an annular shape along a steering circling direction, a U-shaped or C-shaped cross section, and the insulating layer is formed on the outside, the adhesive A step of processing so that the material is on the inside, a step of forming a foamed synthetic resin layer so as to cover the cored bar, and the sensor after the processing is performed using an inner adhesive material. A step of attaching the foam synthetic resin layer, a step of suturing the leather wrapped leather directly to the sensor, but equipped with.

  In one embodiment of the second invention, a first sensor and a second sensor having a U-shaped cross section are manufactured using the sheet-like sensor, and the first sensor is mounted on an occupant side of the foamed synthetic resin layer. The second sensor is mounted on the non-passenger side of the synthetic resin foam so that the outer surface of the first sensor is continuous with the outer surface of the second sensor without any step.

  According to one aspect of the second invention, a third sensor and a fourth sensor having an arc shape along the steering rotation direction are manufactured using the sheet-like sensor, and the third sensor and the fourth sensor are connected to the steering rotation. The third sensor and the fourth sensor are attached to the foamed synthetic resin layer such that the third sensor and the fourth sensor are adjacent to each other in the direction and the outer surface of the third sensor is continuous with the outer surface of the fourth sensor without any step. Manufacturing method of a steering wheel.

  In the steering wheel of the present invention, the sensor that covers the foamed synthetic resin layer has an arc shape or an annular shape extending in the steering circling direction, has a U-shaped or C-shaped cross section, and has an outer surface with no steps. It is continuous. Since the leather directly covers the sensor, the surface hardness can be maintained and the design can be excellent.

FIG. 1 is a perspective view of the steering wheel according to the embodiment. FIG. 2 is an enlarged view of a part of the steering wheel of FIG. FIG. 3 is a sectional view taken along the line III-III in FIG. FIG. 4 is a perspective view of the capacitance sensor according to the embodiment before shaping. FIG. 5 is a plan view of the capacitance sensor. FIG. 6 is a sectional view taken along the line VI-VI of FIG. FIG. 7 is a perspective view of the capacitance sensor according to the embodiment after shaping. FIG. 8 is a diagram illustrating a method of attaching the capacitance sensor according to the embodiment to the wheel unit. FIG. 9 is a plan view of the wheel unit to which the capacitance sensor is attached. FIG. 10 is a plan view of a capacitance sensor according to another embodiment. FIG. 11 is a perspective view of a capacitance sensor according to another embodiment. FIG. 12 is a perspective view of a capacitance sensor according to another embodiment. FIG. 13 is a view showing a groove for a harness provided in the urethane foam layer.

  Hereinafter, embodiments will be described with reference to the drawings. In the following description, the left and right directions of the steering wheel correspond to the left and right directions of the vehicle body in a state where the steering wheel is in a steering posture when the vehicle is traveling straight. The 12 o'clock side and 6 o'clock side of the steering wheel indicate upper and lower sides when the steering wheel is viewed from the front (that is, from the occupant side), the 3 o'clock side indicates the right side, and the 9 o'clock side indicates the left side.

  FIG. 1 is a perspective view of a steering wheel 1 according to an embodiment, FIG. 2 is an enlarged view of a part of the steering wheel 1, and FIG. 3 is a cross-sectional view taken along line III-III of FIG. In this embodiment, the steering wheel 1 is of a so-called three-spoke type, and spoke portions 8L, 8R, 8D extend from the central steering hub portion 7 in three directions, left, right, and downward, respectively. The distal ends of the portions 8L, 8R, 8D are connected to the wheel portion 2 on the outer periphery of the steering wheel 1, respectively.

  The number and arrangement of the spokes provided on the steering wheel 1 are not limited to this. A boss 7a at the center of the steering hub 7 is engaged with a tip of a steering shaft (not shown) of the vehicle.

  The wheel portion 2 includes a metal core 3 that goes around the steering wheel 1, a foamed synthetic resin layer (urethane foam layer 4 in this embodiment) that covers the metal core 3, and a wheel metal 2 that covers the urethane foam layer 4. It has a sensor 10 provided over the entire circumference and a leather 5 which covers the sensor 10 and forms the outermost surface of the wheel portion 2. The sensor 10 is a capacitance sensor, and one end of a harness 22 is connected. The other end of the harness 22 is connected to the electronic control unit 20 through the spoke portions 8L and 8R.

  The electronic control unit 20 converts a capacitance detected by the sensor 10 into a voltage, a CV conversion circuit, and an A / D converter that converts an analog signal indicating a voltage from the CV conversion circuit into a digital signal. A CPU that determines whether or not the driver is holding the steering wheel 1 based on a digital signal output from the A / D converter, and a shield drive circuit that applies a voltage to a shield circuit 13 (see FIG. 6) described later. Etc.

  The leather 5 is obtained by wrapping the sensor 10 and the urethane foam layer 4 by one turn and sewing them with a suture thread 6. Leather 5 is sewn on the inner peripheral side of the wheel portion 2 in order to make the suture 6 inconspicuous and to prevent the stitching portion from touching the hand as much as possible when the driver grips the wheel portion 2. . The leather 5 continuously makes one round of the wheel portion 2 in the direction D2 (see FIG. 2) around the steering axis. As the leather 5, artificial leather other than natural leather such as cowhide can be used.

  FIGS. 4 and 5 show the sensor 10 before being mounted on the wheel unit 2. FIG. 6 is a sectional view taken along the line IV-IV in FIG. As shown in FIG. 6, the sensor 10 includes a substrate 11, a detection circuit 12 provided on one surface (front surface) of the substrate 11, and a shield circuit 13 provided on the other surface (back surface) of the substrate 11. Having. The detection circuit 12 is covered with an insulating layer 14 such as a resist. The shield circuit 13 is covered with an insulating acrylic adhesive 15.

  For the substrate 11, a resin film that can be shaped and formed, such as PET (polyethylene terephthalate) or polyester, can be used. Silver, copper, carbon, or the like can be used for the detection circuit 12 and the shield circuit 13. As shown in FIG. 5, the detection circuit 12 is preferably provided so as to cover almost the entire surface of the substrate 11.

  The thickness of the substrate 11 is about 0.03 to 0.07 mm. The thickness of the sensor 10 is about 0.2 to 0.3 mm.

  A mold having the same shape as that of the core metal 3 covered with the urethane foam layer 4 is prepared, and the sheet-shaped sensor 10 as shown in FIGS. As a result, as shown in FIG. 7, the wheel portion 2 has an arc shape extending along the circumferential direction D1 (see FIG. 1), and has a substantially U-shaped cross section. In the shaped sensor 10, the shield circuit 13 and the adhesive 15 on the back side of the substrate 11 are located inside the U-shape, and the detection circuit 12 and the insulating layer 14 on the front side of the board 11 are located outside the U-shape I do. After the shaping process, unnecessary portions are removed by cutting when attaching to the urethane foam layer 4 described later. As shown in FIG. 7, the sensor 10 may be provided with an overhang H for connection to the harness 22.

  As shown in FIG. 7, the sensor 10 having an arc shape extending along the circumferential direction of the wheel portion 2 and having a substantially U-shaped cross section is manufactured in such a manner as to cover the entire surface of the wheel portion 2. For example, as shown in FIGS. 8 and 9, sensors 10A, 10B, 10C, and 10D that cover the occupant side of the wheel portion 2 by ４ turn in the circling direction of the wheel portion 2 and the opposite occupant side of the wheel portion 2 10E, 10F, 10G, and 10H, which cover 周 in the circumferential direction of the wheel portion 2. 8 and 9, illustration of spoke portions and hub portions is omitted for convenience of explanation.

  As shown in FIG. 8, the sensors 10A to 10H can be mounted by fitting the urethane foam layer 4 inside the sensors 10A to 10H having a substantially U-shaped cross section and bonding them with the adhesive 15.

  The sensors 10 </ b> A to 10 </ b> H are mounted such that one end of the wheel portion 2 in the circling direction is located on the 3 o'clock side or 9 o'clock side of the wheel portion 2. For example, as shown in FIG. 9, the sensor 10A is mounted on the occupant side of the wheel unit 2 from the 12 o'clock side to the 3 o'clock side. The sensor 10B is mounted on the occupant side of the wheel unit 2 from the 3 o'clock side to the 6 o'clock side. The sensor 10C is mounted on the occupant from the 6 o'clock side to the 9 o'clock side of the wheel portion 2. The sensor 10D is mounted on the occupant from the 9 o'clock side to the 12 o'clock side of the wheel portion 2.

  Similarly, the sensor 10E is mounted on the non-occupant side of the wheel portion 2 from the 12:00 side to the 3 o'clock side. The sensor 10F is mounted on the opposite side of the wheel section 2 from the 3 o'clock side to the 6 o'clock side. The sensor 10G is mounted on the opposite side of the wheel section 2 from the 6 o'clock side to the 9 o'clock side. The sensor 10H is mounted on the non-occupant side of the wheel unit 2 from the 9 o'clock side to the 12 o'clock side.

  The U-shaped edges E1 and E1 of the sensors 10A to 10H mounted on the urethane foam layer 4 (see FIG. 7) are the U-shaped edges of the sensors 10A to 10H facing each other via the urethane foam layer 4. It is preferable to contact the portions E1 and E1 without overlapping in the direction D2 around the axis. As a result, the outer surface continues from the sensor 10A to the sensor 10E without any step. Similarly, the outer surface continues from the sensor 10B to the sensor 10F without a step. The outer surface continues from the sensor 10C to the sensor 10G without any step. The outer surface continues from the sensor 10D to the sensor 10H without any step.

  Of the sensors 10A to 10H attached to the urethane foam layer 4, the end E2 in the steering rotation direction D1 (see FIG. 7) is in contact with the end E2 of the sensor 10A to 10H adjacent in the steering rotation direction D1 without overlapping. Is preferred. For example, the outer surfaces of the sensors 10A, 10B, 10C, and 10D are continuous without any steps. Similarly, the outer surfaces of the sensors 10E, 10F, 10G, and 10H are continuous without any steps.

  The harnesses 22 are provided in the same number as the sensors 10, and in this embodiment, eight harnesses 22 corresponding to the sensors 10A to 10H are provided. At the 3 o'clock side and the 9 o'clock side of the wheel portion 2, the sensors 10 </ b> A to 10 </ b> H are respectively connected to one ends of the corresponding harnesses 22. The other end of the harness 22 is connected to the electronic control unit 20. Thereafter, the sensors 10A to 10H are covered with the leather 5, and the leather 5 is sewn with the suture 6 on the inner peripheral side of the steering wheel, whereby the steering wheel 1 is manufactured.

  When the driver grips the steering wheel 1, a change in the capacitance is detected by the detection circuit 12, and the electronic control unit 20 determines that the driver has gripped the steering wheel 1.

  In the present embodiment, the surface of the wheel portion 2 (urethane foam layer 4) is divided into a total of eight regions, that is, divided into two on the occupant side and the non-occupant side and four in the steering circling direction. The sensors 10A to 10H which are shaped so as to have a quadrant arc shape and a substantially U-shaped cross section are mounted. By arranging the sensors 10A to 10H without gaps, the outer surfaces of the sensors 10A to 10H are continuous without any step, and when the sensors 10A to 10H are covered with the leather 5, no irregularities appear and the design is excellent. Become.

  Further, since the sensors 10A to 10H are mounted on the urethane foam layer 4 and the sensors 10A to 10H are directly covered with the leather 5, the surface hardness of the wheel portion 2 can be maintained. Further, since there is no need to provide a cushioning material between the leather 5 and the sensors 10A to 10H, the weight and the manufacturing cost can be reduced, and the manufacturing process can be simplified.

  In the above embodiment, the U-shaped edges E1 of the sensors 10A to 10H facing each other via the urethane foam layer 4 may not contact each other, and a very small gap may be left between the edges E1. In particular, on the inner peripheral side of the steering wheel, there is a suture thread 6 for sewing the leather 5, and when the leather 5 is wound, irregularities due to the gap between the edge portions E1 are unlikely to appear. May be. Further, the ends E2 of the sensors 10A to 10H adjacent to each other in the steering rotation direction D1 may not contact each other, and an extremely small gap may be left between the ends E2.

  In the above-described embodiment, a case has been described in which the surface of the wheel portion 2 (urethane foam layer 4) is divided into a total of eight regions, that is, the surface is divided into two on the occupant side and the non-occupant side and four in the steering direction. As shown in FIG. 10, the vehicle is divided into a total of four regions, ie, two regions on the occupant side and the non-occupant side, and two regions in the steering circling direction. The sensors 10I, 10J, 10K, and 10L which have been shaped so as to be formed may be mounted.

  The sensor 10I extends from the 9 o'clock side to the 3 o'clock side of the occupant side of the wheel portion 2 via the 12 o'clock side. The sensor 10J extends from the 3 o'clock side to the 9 o'clock side of the occupant side of the wheel portion 2 via the 6 o'clock side. The sensor 10K extends from the 9 o'clock side to the 3 o'clock side of the wheel portion 2 from the 9 o'clock side. The sensor 10L extends from the 3 o'clock side to the 9 o'clock side via the 6 o'clock side on the non-occupant side of the wheel portion 2.

  As shown in FIG. 11, the surface of the wheel portion 2 (urethane foam layer 4) is divided into an occupant side and a non-occupant side, and each divided region is formed into an annular shape and a substantially U-shaped cross section. The shaped sensors 10M and 10N may be mounted. The sensor 10M is mounted on the occupant side of the wheel unit 2, and the sensor 10N is mounted on the non-occupant side of the wheel unit 2.

  As shown in FIG. 12, the surface of the wheel portion 2 (urethane foam layer 4) is not divided into the occupant side and the non-occupant side, but is divided into four regions in the steering circling direction. Sensors 10O, 10P, 10Q, and 10R shaped and shaped so as to have a substantially circular arc shape and a substantially C-shaped cross section may be mounted. A small gap G along the steering circling direction is formed between the C-shaped end portions. The wheel section 2 is inserted into the inside of the sensors 100 to 10R from the gap G, and the sensors 100 to 10R are inserted into the wheel section 2. Is fitted. This gap G is preferably located immediately below the suture thread 6 for sewing the leather 5.

  The surface of the wheel portion 2 (urethane foam layer 4) is not divided into the occupant side and the non-occupant side, but is divided into two regions in the steering circling direction. A sensor shaped and shaped so as to be substantially C-shaped may be mounted.

  Further, a sensor shaped and processed so as to have an annular shape and a substantially C-shaped cross section may be mounted on the surface of the wheel portion 2 (urethane foam layer 4).

  Considering the connectivity with the harnesses 22 provided on the spoke portions 8L, 8R, 8D, the arc-shaped sensor extending along the circling direction of the wheel portion 2 It is preferably located on the hour or 9 o'clock side. As shown in FIG. 1, when the steering wheel 1 is a three-spoke type, one end of the sensor in the steering circling direction may be located on the 6 o'clock side of the wheel unit 2.

  When there is a sensor whose both ends in the steering rotation direction are not located at the 3 o'clock side, 6 o'clock side, or 9 o'clock side of the wheel section 2, as shown in FIG. 13, from the connection point between the wheel section and the spoke section A harness groove 30 extending to the sensor end is formed in the urethane foam layer 4, the harness 22 is disposed in the groove 30, and the harness 22 is extended to the sensor. The harness groove 30 formed in the urethane foam layer 4 is provided on the steering inner circumferential side in accordance with the position of the suture 6, so that even when the harness 22 is passed through the inside of the wheel portion 2, the appearance of the steering wheel 1 is obtained. And the tactile sensation is not affected.

  In the above embodiment, the case where the sensor 10 provided between the urethane foam layer 4 and the leather 5 is a capacitance sensor has been described, but the sensor 10 may be another sensor such as a pressure sensor.

  When the leather 5 is composed of a plurality of leathers, it is preferable that the boundary of the sensor adjacent to the steering rotation direction D1 be located at a stitching portion where the leathers are sewn.

  The sensor 10 may be provided over the entire circumference in the steering circling direction, or the sensor 10 may not be provided at a connection portion between the spoke portions 8L, 8R, 8D and the wheel portion 2 and in the vicinity thereof.

  Each of the above embodiments is an example of the present invention, and the present invention is not limited to the illustrated state.

  This application is based on Japanese Patent Application No. 2016-083013 filed on April 18, 2016, which is incorporated by reference in its entirety.

Claims (3)

A method of manufacturing a steering wheel, comprising: a steering hub, a wheel including a metal core that orbits a steering wheel, and a spoke extending from the steering hub and connected to the wheel.
A substrate made of a resin film, a detection circuit provided on a first surface of the substrate, an insulating layer covering the detection circuit, a shield circuit provided on a second surface of the substrate opposite to the first surface, and A sheet-like sensor having an adhesive covering the shield circuit is formed in an arc shape or an annular shape along the steering circling direction, the cross-sectional shape is U-shaped or C-shaped, the insulating layer is outside, and the adhesive is inside. Processing to become
Forming a foamed synthetic resin layer so as to cover the metal core,
A step of mounting the processed sensor on the foamed synthetic resin layer using an inner adhesive,
A step of directly wrapping leather around the sensor and sewing the leather;
The manufacturing method of a steering wheel provided with. 2. The first sensor and the second sensor having a U-shaped cross section according to claim 1 , wherein the sheet-shaped sensor is used,
Mounting the first sensor on the occupant side of the foamed synthetic resin layer;
A method of manufacturing a steering wheel, comprising: mounting the second sensor on the non-occupant side of the synthetic resin foam layer so that the outer surface of the first sensor is continuous with the outer surface of the second sensor without any step. . 3. The third sensor and the fourth sensor according to claim 1 or 2 , wherein the third sensor and the fourth sensor are formed in an arc shape along the steering circling direction using the sheet-shaped sensor.
The third sensor and the fourth sensor are arranged such that the third sensor and the fourth sensor are adjacent to each other in the steering circling direction, and the outer surface of the third sensor is continuous with the outer surface of the fourth sensor without any step. Is attached to the foamed synthetic resin layer.

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