Patent Application
20120261185
The present invention relates to a wiring harness including flat cables.
Conventionally, a wiring harness 101 is used for wiring in a power supply circuit of an automobile, where the wiring harness 101 is used with a relatively large electric current, the wiring harness 101 including about three round wires 102 (single wires) having a relatively large diameter, each of which is prepared by coating a conductors 103 having a cross-sectional area of 15 mm2 or more with an insulator 104, where the three round wires 102 are covered with a shielding layer 105 and an armoring member 106, whereby the three round wires 102 are bunched together as shown in
In these days, a flat cable (a Flexible Flat Cable, hereinafter called to also as an FFC) is used for wiring in an automobile. The FFC has a larger surface area than the round wire and accordingly has improved radiation performance. Thus, a conductor of the FFC can be reduced in size. In addition, the FFC is very flat and flexible, which brings about an advantage such that the space for wiring can be reduced, and the FFC is foldable in a narrow space.
For example, laminated flat cables including a plurality of flat cables that are laminated are known as cables used for electric wiring in an automobile (see PTL 1).
PTL 1: JP2008-117781A
While the FFC has the larger surface area and accordingly has the improved radiation performance, the radiation is prevented if the FFCs are laminated completely to each other or overlap each other, which tends to cause a rise in temperature of the conductors. For this reason, the laminated configuration of the FFCs is unfavorable for the use where a large electric current is passed.
In addition, the radiation is prevented if the cables overlap each other, even if the FFCs do not have a laminated configuration. To solve this problem, wiring paths need to be prepared such that the cables do not overlap each other in wiring the FFCs; however, the wiring paths are limited. In addition, paying sufficient attention such that the cables do not overlap each other in wiring the FFCs is a very troublesome task.
The object to be solved by the present invention is to provide a wiring harness that has favorable radiation performance, is capable of achieving a reduced space for wiring, and allows an easy wiring task in wiring a plurality of flat cables that are bunched together.
In order to solve the problems described above, a wiring harness of the present invention includes plurality of single flat cables, each of which has a flat shape in cross section in a width direction, and includes a conductor having a flat shape and an insulator with which the conductor is coated, wherein the single flat cables are disposed in parallel in the width direction where the flat cables are prevented from overlapping each other.
Having the configuration that the plurality of single flat cables having the flat shape in cross section in the width direction and including the conductors having the flat shape and the insulators with which the conductors are coated, wherein the single flat cables are disposed in parallel in the width direction, the wiring harness of the present invention is capable of achieving a reduced space for wiring because the wiring harness of the present invention has a flatter shape as a whole than a conventional wiring harness including round wires.
In addition, having the configuration that the plurality of single flat cables are disposed in parallel in the width direction, which is not a laminated configuration such that the plurality of single flat cables are laminated vertically, the wiring harness of the present invention has favorable radiation performance. In addition, because the single flat cables are already disposed so as not to overlap each other, wiring paths for the flat cables are not limited in wiring the flat cables, and there is no possibility of temperature rise caused by degraded radiation performance of the wiring harness due to overlapping flat cables. Thus, favorable heat radiation from the single flat cables can be performed.
In addition, because the single flat cables are already disposed so as not to overlap each other, wiring paths for the wiring harness are not limited in wiring, so that it is unnecessary to pay attention such that the cables do not overlap each other in wiring, which allows an easy wiring task.
A detailed description of a wiring harness of a first preferred embodiment of the present invention will now be provided with reference to the accompanying drawings.
FFCs of a same configuration are used for the single flat cables 2. Each single flat cable 2 includes a conductor 3 having a flat shape, and an insulator with which the conductor 3 is coated. Each single flat cable 2 has a flat shape in cross section in the width direction.
The protection member 5 has the function of protecting the single flat cables 2 from the outside, and the function of holding the plurality of single flat cables 2 so as to prevent them from overlapping each other. By including the protection member 5, the wiring harness 1 can maintain its shape even if bent, and keep the single flat cables disposed in parallel. Thus, the wiring harness 1 can prevent in a convincing way degradation in radiation performance resulting from overlapping of flat cables.
Further, the wiring harness 1 includes a shielding layer 6 for proving shielding characteristics between the single flat cables 2 and the protection member 5 as shown in
A corrugated tube is preferably used as the protection member 5 . It is preferable that the protection member 5 is made from a material that has an improved adhesion property to the single flat cables 2. The improved adhesion property between the protection member 5 and the single flat cables 2 prevents formation of a gap therebetween, which improves thermal conductivity, and accordingly improves radiation performance. A thermoplastic resin is used for the material of the protection member 5, and a polyimide resin and a polypropylene resin are preferably used. The protection member 5 is formed by extrusion-molding the thermoplastic resin so as to have a hollow shape.
End portions of single flat cables 2 at one end la and the other end lb of the wiring harness 1 are exposed out of the ends of the protection member 5 as shown in
Each single flat cable 2 includes one conductor 3 . A gathering member of stranded wires that consist of elemental wires and are disposed in the width direction, a gathering member of elemental wires that are disposed in the width direction, or a single wire having a flat shape such as a rectangular conductor can be used as the conductor 3. Using the gathering members of stranded wires or elemental wires as the conductors 3 provides flexibility to the conductors 3.
When the conductors 3 are flexible, the single flat cable 2 improves in flexibility. The single flat cable 2 that improves in flexibility improves in adhesion property to the protection member 5, which improves radiation performance. In addition, when the single flat cable 2 improves in flexibility, the wiring harness 1 accordingly improves in flexibility. Thus, the wiring harness 1 is easy to bend in wiring, which facilitates a wiring task. In addition, if the conductors 3 are flexible in the single flat cable 2, an adhesion property of the conductors 3 to the insulators 4 improves.
The conductors 3 are made from a metal such as copper, a copper alloy, aluminum and an aluminum alloy. Examples of the copper and the copper alloy include oxygen free copper, tough pitch copper, and phosphor bronze. It is preferable that the conductors 3 are plated with a metal such as tin and nickel.
The size of the conductors 3 is determined as appropriate according to the intended use of the wiring harness 1 and the size of the flat cables 2.
Examples of the shielding layer 6 include a metallic braid, and a thin film layer of a metal such as aluminum. It is essential only that the shielding layer 6 should provide shielding characteristics to the wiring harness 1. The metallic thin film layer can be formed on an inner surface of the protection member by evaporating aluminum thereon, or by laminating an aluminum film thereon.
The wiring harness 1 possessing shielding characteristics can prevent an influence exerted by electromagnetic waves on surrounding devices when used in a high-voltage circuit. In addition, the metallic braid if used as the shielding layer 6 has an effect of improving radiation performance because metal has favorable thermal conductivity.
Shielding characteristics are provided to the protection member 5 preferably using a method of dispersing an electromagnetic wave absorption material such as ferrite particles into the protection member 5, or a method of burying a braid inside of the protection member 5. In order to disperse the ferrite particles into the protection member 5, the ferrite particles are added to the resin from which the protection member 5 is made, and then extrusion-molding of the protection member 5 is performed. In order to bury the braid inside of the protection member 5, the metallic braid is placed inside of a mold, and then the resin is extrusion-molded, whereby the braid and the protection member 5 have a monolithic construction to provide the protection member 5 inside of which the braid is buried.
A material that is in a liquid state before curing and becomes like rubber by being subjected to curing after filling is used as the filler 7. Examples of the filler 7 include liquid silicone rubber. The filler 7 in a liquid state is charged into the gap between the single flat cables 2 and the protection member 5, and then cured at room temperature or by heating. The liquid silicone rubber after subjected to curing becomes like rubber, and lies between the single flat cables 2 and the protection member 5, whereby the heat generated by the single flat cables 2 can be efficiently radiated outside.
An example of the method for producing the wiring harness 1 shown in
In the wiring harness 1 of the present invention, the shape of the protection member 5 is not limited to the shape described above in the present embodiment. It is essential only that the protection member 5 has a shape such that the state where the single flat cables 2 disposed in parallel can be maintained.
Alternatively, it is also preferable that the protection member 5 has a configuration of including the tubular members 5a, 5b and 5c, each of which defines a mere tubular housing member that cannot be split in two in the width direction. In this case, the single flat cables 2 are inserted into the housing spaces 51, 52 and 53 from one end portions of the tubular members 5a, 5b and 5c.
The connecting members 15 and 17 of the protection member units 11 and 12 define concave grooves that have a circular shape in section. The connecting members 16 and 18 define convex ridges that are arranged to fit into the concave grooves of the connecting members 15 and 17. The connecting member 16 of the protection member unit 12 fits into the connecting member 15 of the protection member unit 11, and the connecting member 18 of the protection member unit 13 fits into the connecting member 17 of the protection member unit 12.
As shown in
The wiring harness 1 can be obtained in which four or more than four single flat cables 2 are disposed in parallel by connecting in the width direction a plurality of the protection member units 12 that are used for middle positions as shown in
The number of single flat cables 2 is not limited to three in the present invention, and may be two, or four or more . The single flat cables 2 consisting of three cables of the wiring harness, which is the wiring harness of the preferred embodiments of the present invention, can be favorably used for cables used in a three-phase motor.
The wiring harness of the present invention can be favorably used in a low-voltage circuit or a high-voltage circuit of an automobile.
A description of the present invention will now be provided.
A wiring harness having a wire configuration such that three flat cables (referred to as FFC in Table 1), of which each conductor had a cross-sectional area of 14 mm2, were disposed in parallel as show in Table 1 was subjected to measurement of electric current value such that ΔT, which was a difference between an ambient temperature and a heat resistance temperature, became 70 degrees C. A result of the measurement and the wire configuration are shown in Table 1. A method for measuring the electric current value is described below. Rises in temperature (T) of the wiring harness were measured by applying currents of 80A, 100A and 120A to the wiring harness as shown in
For a comparison purpose, a wiring harness in which three single flat cables that were same as the cables used in Example 1 were laminated vertically (see Table 1) was subjected to measurement of electric current value such that ΔT became 70 degrees C. As a result, the electric current value of Comparative Example 1 was 98A while the electric current value of Example 1 was 126A, which showed Example 1 had the larger electric current value. cl Comparative Example 2
A wiring harness in which three single flat cables that were same as the cables used in Example 1 overlapped with one another such that the overlapping portions became ½ of the wire width as shown in Table 1 was subjected to measurement of electric current value such that ΔT became 70 degrees C. As a result, the electric current value of Comparative Example 2 was 103A, which showed that Example 1 had the larger electric current value though the electric current value of Comparative Example 2 was larger than that of Comparative Example 1.
A wiring harness in which three conventional round wires were bunched together as shown in Table 1 was subjected to measurement of electric current value such that ΔT became 70 degrees C. As a result, the electric current value of Reference Example 1 was 125A, which was almost same as Example 1. It is to be noted that each conductor of the wiring harness of Reference Example 1 had a cross-sectional area of 20 mm2, which was larger than the conductor cross-sectional area of 14 mm2 of Example 1. This result showed that when the FFCs disposed in parallel were used, the conductor cross-sectional areas of the FFCs could be reduced compared with the round wires if used with same electric current value.
A wiring harness in which the three single flat cables used in Example 1 were disposed in parallel and covered with a shielding layer and a protection member was subjected to measurement of electric current value such that ΔT became 70 degrees C., similarly to Example 1. As a result, the electric current value of Example 2 was 102A.
A wiring harness in which the three round wires used in Reference Example 1 were bunched together and covered with a shielding layer and a protection member that were similar to Example 1 was subjected to measurement of electric current value such that ΔT became 70 degrees C. The measurement of temperature was performed at three points shown in the wire sectional view of Table 1, and the obtained temperatures were averaged. As a result, the electric current value of Reference Example 2 was 97A, which showed Example 2 had the larger electric current value than Reference Example 2.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-294852 | Dec 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/073163 | 12/22/2010 | WO | 00 | 6/25/2012 |
