Connection structure and steering unit

Abstract

To provide a connection structure that can be easily manufactured. [Solution] The connecting structure 10 comprises a conductive sheet 20, a metal foil 30, and a metal terminal 50. The conductive sheet 20 has a mesh shape. The metal foil 30 is superimposed on the conductive sheet 20. The metal terminal 50 has a main body 51 and a protruding piece 52. The main body 51 is connected to an electric wire. The protruding piece 52 protrudes from the main body 51 and penetrates the conductive sheet 20 and the metal foil 30. The metal terminal 50 is crimped and fixed to the conductive sheet 20 and the metal foil 30 by the protruding piece 52.

Description

Technical Field

[0001] The present invention relates to a connection structure and a steering unit.

Background Art

[0002] Conventionally, a connection structure for electrically connecting an electric wire and a conductive member has been known. Patent Document 1 discloses this type of connection structure.

[0003] The connection structure of Patent Document 1 includes a terminal to which an electric wire is attached and which has an insertion hole, a sheet-like conductive member having a cut portion, and a rivet that is inserted through the insertion hole of the terminal and the cut portion of the conductive member and is caulked to conduct the terminal and the conductive member.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in manufacturing the connection structure of Patent Document 1, it is necessary to form an insertion hole in the terminal and a cut portion in the conductive member, insert a rivet through the insertion hole and the cut portion, and then caulk the rivet. That is, there is room for improvement in that the connection structure of Patent Document 1 has many manufacturing steps.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a connection structure that can be easily manufactured. Means and Effects for Solving the Problems

[0007] The problems to be solved by the present invention are as described above. Next, means for solving this problem and its effects will be described.

[0008] In view of the present invention, a connection structure is provided with the following configuration: The connection structure comprises a conductive sheet, a metal foil, and a metal terminal. The conductive sheet has a mesh shape. The metal foil is superimposed on the conductive sheet. The metal terminal has a main body and a protruding piece. The main body is connected to an electric wire. The protruding piece protrudes from the main body and penetrates the conductive sheet and the metal foil. The protruding piece is crimped and fixed to the conductive sheet and the metal foil.

[0009] This allows for the manufacture of a connection structure by passing a protruding piece of a metal terminal through the conductive sheet and the metal foil layered on top of it, and then crimping the protruding piece. In other words, the connection structure can be manufactured easily. Furthermore, in addition to direct electrical contact at the point where the protruding piece penetrates, the metal terminal and the conductive sheet also conduct electricity indirectly through the metal foil. That is, by providing the metal foil, the conductive path becomes wider compared to when it is not provided, and the connection resistance between the metal terminal and the conductive sheet is reduced.

[0010] In the aforementioned connecting structure, the following configuration is preferable. That is, the connecting structure further comprises a porous body superimposed on the opposite side of the metal foil superimposed on the conductive sheet. The metal terminal is fixed to the conductive sheet, the metal foil, and the porous body by crimping the protruding piece.

[0011] As a result, when the protruding piece is crimped, the porous material is strongly compressed, and its restoring force increases the contact pressure between the conductive sheet and the metal terminal via the metal foil. This increase in contact pressure further reduces the connection resistance between the conductive sheet and the metal terminal. Furthermore, even if the porous material deteriorates over time, because it is strongly compressed, the conductive sheet, metal foil, and metal terminal are less likely to separate from each other. Therefore, it is possible to suppress the increase in connection resistance between the conductive sheet and the metal terminal over time.

[0012] In the aforementioned connection structure, it is preferable that the protruding piece of the metal terminal penetrates the porous body, the conductive sheet, and the metal foil in that order.

[0013] As a result, the main body of the metal terminal makes contact with the porous material over a wider area, causing the porous material to be compressed more strongly. Therefore, the restorative force of the porous material increases even further, and the connection resistance between the conductive sheet and the metal terminal can be reduced even more.

[0014] In the aforementioned connecting structure, the following configuration is preferable: The protruding piece has a curved portion that curves toward the metal foil after penetrating the porous body, the conductive sheet, and the metal foil. At least a portion of the metal foil is in contact with the inner circumferential surface of the curved portion.

[0015] As a result, at least a portion of the metal foil comes into contact with the inner surface of the curved portion of the protruding piece, making the conductive path between the metal terminal and the conductive sheet wider. Therefore, the connection resistance between the metal terminal and the conductive sheet can be further reduced.

[0016] In the aforementioned connecting structure, the thickness of the metal foil is preferably 100 μm or more.

[0017] As a result, when crimping the protruding piece, the space occupied by the metal foil within the curved portion tends to increase, and even if the porous material deteriorates over time, the conductive sheet, metal foil, and metal terminals are less likely to separate from each other. Therefore, it is possible to suppress the increase in connection resistance between the conductive sheet and the metal terminals over time.

[0018] In the aforementioned connecting structure, it is preferable that the tip of the protruding piece is in contact with the metal foil.

[0019] As a result, by increasing the contact area between the metal terminal having the protruding piece and the metal foil, the conductive path between the metal terminal and the conductive sheet becomes even thicker. Therefore, the connection resistance between the metal terminal and the conductive sheet can be made even smaller.

[0020] In the above connection structure, it is preferable that the metal material constituting the metal foil and the metal material constituting the metal terminal are the same as each other.

[0021] Thereby, it is possible to suppress the occurrence of dissimilar metal contact corrosion between the metal foil and the metal terminal. Therefore, it is possible to suppress a decrease in the contact area between the metal foil and the metal terminal, and thus suppress an increase in the connection resistance between the metal terminal and the conductive sheet over time.

[0022] According to another aspect of the present invention, a steering unit having the following configuration is provided. That is, the steering unit includes a steering, the above connection structure, wherein the conductive sheet is disposed on at least a part of the steering, and a determination unit that is connected to the conductive sheet via the electric wire and the metal terminal and determines a gripping state of the steering by an occupant.

[0023] Thereby, the conductive sheet can be used as a gripping sensor to determine the gripping state of the steering by an occupant. Here, the determination unit determines the gripping state of the steering by an occupant based on the capacitance between the conductive sheet and the ground portion. As described above, since the connection structure according to the present invention has a small connection resistance between the metal terminal and the conductive sheet, the determination accuracy by such a determination unit can be improved.

Brief Description of the Drawings

[0024] [Figure 1] Front view showing the appearance of the steering unit according to the first embodiment of the present invention. [Figure 2] Perspective view showing the overall configuration of the connection structure. [Figure 3]Perspective view showing the enlarged tip of the metal terminal. [Figure 4] Cross-sectional view of the connection structure in a cross-section passing through the protruding piece of the metal terminal. [Figure 5] Perspective view showing the enlarged tip of the metal terminal of the connection structure of the second embodiment.

Embodiments for Carrying Out the Invention

[0025] Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing the appearance of the steering unit 1. FIG. 2 is a perspective view showing the overall configuration of the connection structure 10. FIG. 3 is a perspective view showing the enlarged tip of the metal terminal 50. FIG. 4 is a cross-sectional view of the connection structure 10 in a cross-section passing through the protruding piece 52 of the metal terminal 50.

[0026] The steering unit 1 of the first embodiment shown in FIGS. 1 to 4 is provided, for example, in a passenger car not shown. The steering unit 1 includes a steering 2, a determination unit 60, and at least one (in this example, two) connection structures 10. The two connection structures 10 are arranged symmetrically left and right in the steering unit 1.

[0027] The steering 2 has an annular rim portion 2a arranged on the outer peripheral side, a plate-shaped hub portion 2b arranged on the inner peripheral side of the rim portion 2a, and at least one (in this example, three) spoke portions 2c connecting the rim portion 2a and the hub portion 2b. On the rim portion 2a, a conductive sheet 20 and a porous body 40, which will be described later and are provided in each connection structure 10, are arranged. The hub portion 2b is connected to the drive mechanism of the passenger car via a steering shaft not shown.

[0028] The determination unit 60 is connected to the conductive sheet 20 of each connecting structure 10 via electric wires 100 and metal terminals 50 described later. The determination unit 60 determines the gripping state of the steering wheel 2, more specifically, the rim portion 2a of the steering wheel 2, by the occupant. The gripping state of the steering wheel 2 includes, for example, whether or not the steering wheel 2 is being gripped by the occupant, and the degree to which the steering wheel 2 is being gripped by the occupant. This determination is made based on the capacitance between the conductive sheet 20 and the ground (for example, the vehicle body, not shown). That is, when an occupant grips the steering wheel 2, the capacitance between the conductive sheet 20 and the ground increases. Furthermore, the amount of increase in this capacitance increases as the strength with which the occupant grips the steering wheel 2 increases. By utilizing this change in capacitance, the gripping state of the steering wheel 2 by the occupant can be detected. For example, the determination unit 60 determines that the steering wheel 2 is being held sufficiently firmly by the occupant if the capacitance between the conductive sheet 20 and the grounding portion exceeds a first threshold, while determining that the steering wheel 2 is being held weakly by the occupant if the capacitance exceeds a second threshold (which is smaller than the first threshold) but is less than or equal to the first threshold.

[0029] The determination unit 60 comprises an arithmetic unit and a storage device that stores a program executable by the arithmetic unit (for example, a program that causes a computer to execute the determination method described in the previous paragraph). The determination unit 60 may be part of a control device that controls each element of a passenger car, or it may be a separate device from said control device.

[0030] Each connecting structure 10 comprises a conductive sheet 20, a metal foil 30, a porous body 40, and a metal terminal 50. The conductive sheet 20 and the porous body 40 can form a gripping sensor applicable to the determination method described above. Note that the porous body 40 is not an essential component of the connecting structure 10.

[0031] The conductive sheet 20 has a mesh shape. The overall shape of the conductive sheet 20 is not particularly limited, and for example, it may be an elongated rectangle. The conductive sheet 20 in this embodiment is composed of a conductive fabric having a fiber cloth and a metal plating provided on its surface, but is not limited thereto.

[0032] The metal foil 30 is layered on the conductive sheet 20. The metal material constituting the metal foil 30 is not particularly limited and may be, for example, copper, copper alloy, aluminum, or aluminum alloy. The shape of the metal foil 30 is not particularly limited and may be, for example, rectangular. In this embodiment, the thickness of the metal foil 30 is 100 μm or more, but is not limited thereto. However, from the viewpoint of material cost and manufacturing, the thickness of the metal foil 30 is preferably 300 μm or less.

[0033] The porous body 40 is placed on the opposite side (the lower side in Figure 2) of the metal foil 30 which is layered on the conductive sheet 20. An adhesive layer (not shown) may be provided between the porous body 40 and the conductive sheet 20. The shape of the porous body 40 is not particularly limited; for example, it may be the same as or substantially the same as the shape of the conductive sheet 20, in the form of a rectangular sheet. The porous body 40 in this embodiment is made of an insulating foamed resin, but is not limited to this.

[0034] The metal terminal 50 has a main body 51 and a plurality (six in this example) of protruding pieces 52. The main body 51 is connected to the electric wire 100 shown by the dashed line in Figure 2. The main body 51 has a first crimping portion 51a, a second crimping portion 51b, and a connecting portion 51c which are formed integrally with each other. The first crimping portion 51a is the portion furthest from the conductive sheet 20 and is the portion to which the insulator-covered part of the electric wire 100 is crimped. The second crimping portion 51b is located next to the first crimping portion 51a and is the portion to which the conductor-exposed part of the electric wire 100 is crimped. The connecting portion 51c is located next to the second crimping portion 51b and is the portion that contacts the porous body 40.

[0035] Multiple protruding pieces 52 protrude from the connection portion 51c. Multiple protruding pieces 52 protrude from both edges in the width direction (left-right direction in Figure 4) of the connection portion 51c. In this embodiment, three protruding pieces 52 protrude from one edge, while the remaining three protruding pieces 52 protrude from the other edge. The three protruding pieces 52 protruding from one edge and the three protruding pieces 52 protruding from the other edge face each other in the width direction of the connection portion 51c. Multiple protruding pieces 52 penetrate the porous body 40, the conductive sheet 20, and the metal foil 30 in this order.

[0036] The metal terminal 50 has each protruding piece 52 crimped and fixed to the conductive sheet 20, metal foil 30, and porous body 40. The crimped protruding piece 52 has a curved portion 52a that curves toward the metal foil 30 after penetrating the porous body 40, conductive sheet 20, and metal foil 30. When the protruding piece 52 is crimped, as shown in Figure 4, the metal foil 30 surrounding the protruding piece 52 is plastically deformed so as to stretch due to the shear force acting from the protruding piece 52. The plastically deformed portion (deformed portion 30a) of the metal foil 30 comes into contact with the inner surface of the curved portion 52a. As a result, the metal terminal 50 and the metal foil 30 come into contact with each other over a wide area, so that a sufficiently conductive path is secured between the metal terminal 50 and the conductive sheet 20 via the metal foil 30. The tip of the crimped protruding piece 52 comes into contact with the metal foil 30. This makes the conductive path even wider. The metal material constituting the metal terminal 50 is not limited, but it is preferable that it be the same as the metal material constituting the metal foil 30. The crimp height CH of the metal terminal 50 including the crimped protruding piece 52 (see Figure 4) is preferably 1.65 mm or less or 1.30 mm or less. This makes it possible to further increase the space occupied by the metal foil 30 in the space inside the curved portion 52a of the protruding piece 52, and consequently further suppress the increase in connection resistance between the conductive sheet 20 and the metal terminal 50 over time. From a manufacturing standpoint, the crimp height CH of the metal terminal 50 including the crimped protruding piece 52 is preferably 1.50 mm or more or 1.15 mm or more. In particular, depending on the type of metal terminal 50, the crimp height CH may be 1.50 mm or more and 1.65 mm or less, or 1.15 mm or more and 1.30 mm or less.

[0037] In the connection structure 10 of this embodiment, some (three in this example) of the protruding pieces 52 and the remaining (the remaining three in this example) of the protruding pieces 52 face each other in the width direction of the connection portion 51c (or the width direction of the metal terminal 50). However, as in the second embodiment shown in Figure 5, some of the protruding pieces 52 and the remaining protruding pieces 52 do not have to face each other in the width direction of the metal terminal 50. In other words, some of the protruding pieces 52 and the remaining protruding pieces 52 may be arranged alternately in the longitudinal direction of the metal terminal 50.

[0038] As described above, the connection structure 10 of the first and second embodiments comprises a conductive sheet 20, a metal foil 30, and a metal terminal 50. The conductive sheet 20 has a mesh shape. The metal foil 30 is superimposed on the conductive sheet 20. The metal terminal 50 has a main body 51 and a protruding piece 52. The main body 51 is connected to the electric wire 100. The protruding piece 52 protrudes from the main body 51 and penetrates the conductive sheet 20 and the metal foil 30. The protruding piece 52 is crimped and fixed to the conductive sheet 20 and the metal foil 30.

[0039] This allows the connection structure 10 to be manufactured by passing the conductive sheet 20 and the metal foil 30 superimposed thereon through the protruding piece 52 of the metal terminal 50, and then crimping the protruding piece 52. In other words, the connection structure 10 can be easily manufactured. Furthermore, the metal terminal 50 and the conductive sheet 20 are electrically connected not only at the point where they are penetrated by the protruding piece 52, but also indirectly through the metal foil 30. In other words, by providing the metal foil 30, the conductive path becomes wider compared to when it is not provided, and the connection resistance between the metal terminal 50 and the conductive sheet 20 is reduced.

[0040] The connecting structure 10 in the first and second embodiments further comprises a porous body 40 superimposed on the opposite side of the metal foil 30 superimposed on the conductive sheet 20. The metal terminal 50 has a protruding piece 52 that is crimped and fixed to the conductive sheet 20, the metal foil 30, and the porous body 40.

[0041] As a result, when the protruding piece 52 is crimped, the porous body 40 is strongly compressed, and its restoring force increases the contact pressure between the conductive sheet 20 and the metal terminal 50 via the metal foil 30. This increase in contact pressure further reduces the connection resistance between the conductive sheet 20 and the metal terminal 50. Furthermore, even if the porous body 40 deteriorates over time, because it is strongly compressed, the conductive sheet 20, metal foil 30, and metal terminal 50 are less likely to separate from each other. Therefore, it is possible to suppress the increase in connection resistance between the conductive sheet 20 and the metal terminal 50 over time.

[0042] In the connection structure 10 of the first and second embodiments, the protruding piece 52 of the metal terminal 50 penetrates the porous body 40, the conductive sheet 20, and the metal foil 30 in that order.

[0043] As a result, the main body 51 of the metal terminal 50 makes contact with the porous body 40 over a wide area, causing the porous body 40 to be compressed even more strongly. Therefore, the restoring force of the porous body 40 becomes even greater, and the connection resistance between the conductive sheet 20 and the metal terminal 50 can be further reduced.

[0044] In the connecting structure 10 of the first and second embodiments, the protruding piece 52 has a curved portion 52a that curves toward the metal foil 30 after penetrating the porous body 40, the conductive sheet 20, and the metal foil 30. At least a portion of the metal foil 30 is in contact with the inner circumferential surface of the curved portion 52a.

[0045] As a result, at least a portion of the metal foil 30 comes into contact with the inner circumferential surface of the curved portion 52a of the protruding piece 52, which further widens the conductive path between the metal terminal 50 and the conductive sheet 20. Therefore, the connection resistance between the metal terminal 50 and the conductive sheet 20 can be further reduced.

[0046] In the connecting structure 10 of the first and second embodiments, the thickness of the metal foil 30 is 100 μm or more.

[0047] As a result, when the protruding piece 52 is crimped, the space occupied by the metal foil 30 within the space inside the curved portion 52a tends to increase, and even if the porous body 40 deteriorates over time, the conductive sheet 20, metal foil 30, and metal terminal 50 are less likely to separate from each other. Therefore, it is possible to suppress the increase in connection resistance between the conductive sheet 20 and the metal terminal 50 over time.

[0048] In the connecting structure 10 of the first and second embodiments, the tip of the protruding piece 52 is in contact with the metal foil 30.

[0049] This increases the contact area between the metal terminal 50 having the protruding piece 52 and the metal foil 30, thereby widening the conductive path between the metal terminal 50 and the conductive sheet 20. As a result, the connection resistance between the metal terminal 50 and the conductive sheet 20 can be further reduced.

[0050] In the connection structure 10 of the first and second embodiments, the metal material constituting the metal foil 30 and the metal material constituting the metal terminal 50 are the same.

[0051] This makes it possible to suppress the occurrence of galvanic corrosion between the metal foil 30 and the metal terminal 50. Therefore, it is possible to suppress the reduction in the contact area between the metal foil 30 and the metal terminal 50, and consequently, to suppress the increase in connection resistance between the metal terminal 50 and the conductive sheet 20 over time.

[0052] The steering unit 1 of the first and second embodiments comprises a steering wheel 2, a connecting structure 10 in which a conductive sheet 20 is disposed on at least a part of the steering wheel 2, and a determination unit 60 connected to the conductive sheet 20 via an electric wire 100 and a metal terminal 50, which determines the gripping state of the steering wheel 2 by the occupant.

[0053] This allows the conductive sheet 20 to be used as a gripping sensor to determine the gripping state of the steering wheel 2 by the occupant. Here, the determination unit 60 determines the gripping state of the steering wheel 2 by the occupant based on the capacitance between the conductive sheet 20 and the ground portion. As described above, since the connection structure 10 has low connection resistance between the metal terminal 50 and the conductive sheet 20, the determination accuracy of such determination unit 60 can be improved.

[0054] Preferred embodiments of the present invention have been described above, but the above configuration can be modified as follows, for example. Modifications may be made individually, or multiple modifications may be made in any combination.

[0055] The multiple protruding pieces 52 may penetrate the metal foil 30, the conductive sheet 20, and the porous body 40 in the order described. In other words, the multiple protruding pieces 52 may penetrate the three elements in the reverse order of the order in the first and second embodiments.

[0056] The porous body 40 may be omitted. In this case, the resistance reduction effect due to the restoring force of the compressed porous body 40 cannot be obtained, but the resistance reduction effect due to the increase in conductive paths by providing the metal foil 30 can be sufficiently obtained.

[0057] The connection structure 10 according to the present invention is applicable not only to the steering unit 1 but also to any other application. For example, it could be used as a sensor to detect human gripping or contact in other applications in the automotive field or in the medical field. [Explanation of Symbols]

[0058] 1. Steering Unit 2 Steering 10 Connection Structures 20 Conductive Sheet (Gripping Sensor) 30 Metal foil 40. Porous material (grasping sensor) 50 metal terminal 51 Main body 52 Projecting piece 52a Curved section 60 Judgment section 100 wire

Claims

1. A mesh-shaped conductive sheet, A metal foil is placed on top of the aforementioned conductive sheet, A metal terminal having a main body that connects to an electric wire and a protruding piece that protrudes from the main body and penetrates the conductive sheet and the metal foil, wherein the protruding piece is crimped and fixed to the conductive sheet and the metal foil, A connection structure characterized by comprising the above.

2. A connection structure according to claim 1, The conductive sheet further comprises a porous body superimposed on the opposite side of the metal foil superimposed on the conductive sheet, The metal terminal is a connecting structure characterized in that the protruding piece is crimped and fixed to the conductive sheet, the metal foil, and the porous body.

3. A connection structure according to claim 2, The connecting structure is characterized in that the protruding piece of the metal terminal penetrates the porous body, the conductive sheet, and the metal foil in that order.

4. The connection structure according to claim 3, The protruding piece has a curved portion that curves toward the metal foil after penetrating the porous body, the conductive sheet, and the metal foil. A connecting structure characterized in that at least a portion of the metal foil is in contact with the inner circumferential surface of the curved portion.

5. A connection structure according to claim 4, The connecting structure is characterized in that the thickness of the metal foil is 100 μm or more.

6. A connection structure according to any one of claims 1 to 5, A connecting structure characterized in that the tip of the protruding piece is in contact with the metal foil.

7. A connection structure according to any one of claims 1 to 5, A connection structure characterized in that the metal material constituting the metal foil and the metal material constituting the metal terminal are the same as each other.

8. The steering wheel and A connection structure according to any one of claims 1 to 5, wherein the conductive sheet is disposed on at least a part of the steering, A determination unit is connected to the conductive sheet via the electric wire and the metal terminal to determine the state in which the steering wheel is held by the occupant, A steering unit characterized by having the following features.

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