Wire harness

Abstract

To provide a wire harness superior in a heat dissipation effect, which enables increase in heat resistance while keeping down cost.SOLUTION: A wire harness 1 comprises a wire 11, and a cylindrical outer package member 12 with the wire 11 extending therethrough. The outer package member 12 includes: an interior layer 121 containing a resin of which a relative temperature index RTI2 is 150°C or higher; and an exterior layer 122 containing a resin of which the relative temperature index RTI2 is 130°C or higher and below 150°C. (The relative temperature index RTI2 is an environment temperature when a mechanical strength-keeping rate after 10,000 hrs is 50% in a high-temperature environment exposure test performed on the resin.) In a section of the wire and outer package member in axial and vertical directions, a distance D between an outer peripheral part of the wire and an inner peripheral part of the outer package member in a radial direction of the wire is 0.4 mm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wire harness.

Background Art

[0002] Patent Document 1 describes a polyamide resin composition containing (A) a polyamide resin, (B) melamine cyanurate, and (C) a copper compound. Here, (A) the polyamide resin is a mixture containing two or more selected from (A-1) polyamide 66 resin, (A-2) polyamide 6 resin, and (A-3) polyamide 66 / 6 resin, and the content of units derived from caprolactam in (A) the polyamide resin is 10 to 40% by mass. The content of (B) melamine cyanurate with respect to 100% by mass of the polyamide resin composition is 1 to 3% by mass, and the content of (C) the copper compound with respect to the total amount of the polyamide resin composition is 20 to 100 ppm as copper element. Further, the oxygen index measured in accordance with JIS K7201 is 25 or more. Furthermore, Patent Document 1 describes a molded body formed by molding the above polyamide resin composition.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a wire harness having an electric wire and an exterior member provided outside the electric wire, when the exterior member is produced using the polyamide resin composition as described above, there is a problem that the heat resistance and durability are inferior. On the other hand, when a brass-based material is used to improve the heat resistance, there is a problem that the cost increases.

[0005] Therefore, the present invention aims to provide a wire harness that improves heat resistance while keeping costs down and exhibiting excellent heat dissipation. [Means for solving the problem]

[0006] To achieve the above objective, the wire harness according to the present invention includes an electric wire and a cylindrical outer casing member through which the electric wire is inserted, wherein the outer casing member includes an inner layer containing a resin with a relative temperature index RTI2 of 150°C or higher and an outer layer containing a resin with a relative temperature index RTI2 of 130°C or higher and less than 150°C (wherein the relative temperature index RTI2 is the ambient temperature at which the retention rate of mechanical strength after 10,000 hours is 50% when a high-temperature environmental exposure test of the resin is performed), and the distance D between the outer circumference of the electric wire and the inner circumference of the outer casing member in the radial direction of the electric wire is 0.4 mm or less in the cross-section perpendicular to the axial direction of the electric wire and the outer casing member. [Effects of the Invention]

[0007] The wire harness according to the present invention offers the advantages of improved heat resistance, reduced costs, and excellent heat dissipation. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram illustrating a wire harness according to an embodiment. [Figure 2] Figure 2 is a diagram illustrating a wire harness according to an embodiment. [Figure 3] Figure 3 is a diagram illustrating a wire harness according to another embodiment. [Figure 4] Figure 4 shows the temperature distribution in the axial and perpendicular directions of the wire harness in Example 1-1. [Modes for carrying out the invention]

[0009] The wire harness according to the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the embodiments described below. That is, the components in the embodiments described below include those that can be easily imagined by a person skilled in the art, or that are substantially the same, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention.

[0010] [Embodiment] Figures 1 and 2 are diagrams illustrating a wire harness according to an embodiment. Specifically, Figure 1 shows a cross-sectional view of the wire harness (electric wire and sheathing member) along the axial direction (a cross-sectional view cut along the axial direction passing through the central axis of the electric wire). Figure 2 shows a cross-sectional view of the wire harness (electric wire and sheathing member) in a direction perpendicular to the axial direction. The wire harness 1 includes an electric wire 11 and a sheathing member 12.

[0011] The electric wire 11 has a conductor and an insulating layer provided on the outer circumference of the conductor, and for example, the cross-sectional area of ​​the conductor is 50 sq. The outer covering member 12 is cylindrical, and the electric wire 11 is inserted through the space inside. The outer covering member 12 is a corrugated tube that protects the electric wire 11 routed in a vehicle such as an automobile from surrounding parts such as the vehicle body. In this case, the corrugated tube may be provided in the required number of sections for the entire electric wire, excluding connector connection points, etc. Alternatively, the required number of sections may be provided only in the parts that require protection from surrounding parts. Specifically, the outer covering member 12 is formed by concentrically and alternately connecting annular recesses 12A and annular protrusions 12B on the outer circumference side, along the cylindrical axis. That is, the multiple annular recesses 12A and multiple annular protrusions 12B form a substantially cylindrical and bellows-shaped molded body. The pitch between the annular recess 12A and the annular protrusion 12B is preferably 3.5 mm or less from the viewpoint of heat dissipation effect and flexibility. Figure 2 shows a cross-sectional view of the annular recess 12A.

[0012] The exterior component 12 includes an inner layer 121 and an outer layer 122. The inner side of the exterior component's inner layer is close to the electrical wires, so the inner layer needs to have high heat resistance. On the other hand, the outer side of the exterior component's outer layer is in contact with the outside air and dissipates heat, so the outer layer does not need to have as high heat resistance as the inner layer. Therefore, the inner layer 121 contains a resin with a relative temperature index RTI2 of 150°C or higher, and the outer layer 122 contains a resin with a relative temperature index RTI2 of 130°C or higher and less than 150°C. Here, the relative temperature index RTI2 is the ambient temperature at which the retention rate of mechanical strength after 10,000 hours of high-temperature environmental exposure testing of the resin drops to 50%. Specifically, the high-temperature environmental exposure test is performed by exposing the resin to air at a constant temperature for 10,000 hours. The relative temperature index RTI2 is expressed at the constant temperature at which the mechanical strength drops to 50% of its initial value. Here, the mechanical strength can be determined in accordance with JIS K 7226 "Plastics - Time after long-term heat exposure - Method for determining temperature limits" and JIS K 7127 "Plastics - Test methods for tensile properties - Part 3: Test conditions for films and sheets". In practice, it can be determined by the 10°C half-reduction rule. Thus, because the exterior component employs a two-layer structure consisting of an inner layer containing a high heat-resistant resin and an outer layer containing a general-purpose engineering plastic resin, the wire harness according to this embodiment can reduce costs while improving heat resistance.

[0013] Examples of resins included in the inner layer 121, i.e., resins with a relative temperature index RTI2 of 150°C or higher, include polyphenylene sulfide (PPS) and polyamide 46 (PA46). The resin included in the inner layer 121 may be used individually or in combination of two or more types. Furthermore, as the resin included in the outer layer 122, i.e., resins with a relative temperature index RTI2 of 130°C or higher and less than 150°C, polypropylene (PP), polyamide 6 (PA6), or polyamide 66 (PA66) are preferably used because they have excellent abrasion resistance and can be colored. The resin included in the outer layer 122 may be used individually or in combination of two or more types.

[0014] Here, Table 1 shows the heat resistance of each resin. Note that RTI is the relative temperature index (RTI: Relative thermal index) of UL 746B.

[0015]

Table 1

[0016] Also, the thickness of the inner layer 121 is preferably 1.0 times or more and 4.0 times or less the thickness of the outer layer 122.

[0017] Also, as shown in FIG. 2, in a cross section perpendicular to the axial direction of the wire harness (electric wire and exterior member), the electric wire 11 and the exterior member 12 are each represented by a substantially circular shape, and the electric wire 11 and the exterior member 12 are arranged concentrically. Regarding the cross section perpendicular to the axial direction of this wire harness (electric wire and exterior member), the distance D between the outer peripheral portion of the electric wire 11 and the inner peripheral portion of the exterior member 12 in the radial direction of the electric wire 11 is 0.4 mm or less, and preferably 0.3 mm or less. In other words, the distance D is 0.0 mm or more and 0.4 mm or less, and preferably 0.0 mm or more and 0.3 mm or less. When the distance D is within the above range, the heat dissipation effect can be improved. More specifically, as shown in FIG. 1, the distance D is the distance between the outer peripheral portion of the electric wire 11 and the inner peripheral portion at the annular recess 12A of the exterior member 12 in the radial direction of the electric wire 11.

[0018] By the way, in a conventional wire harness including an electric wire and an exterior member, the distance between the electric wire and the exterior member is large in order to secure a threading work space for the electric wire during manufacturing. For this reason, the conventional wire harness has poor heat conduction and a poor heat dissipation effect, and cannot protect a wiring electric wire with a large current and a high voltage at high temperatures. On the other hand, in the wire harness according to the embodiment, the distance between the electric wire and the exterior member having a specific two-layer structure is reduced, and the electric wire and the exterior member are made to adhere to each other as closely as possible. For this reason, the wire harness according to the embodiment has an improved heat dissipation effect, and can sufficiently protect a wiring electric wire with a large current and a high voltage at high temperatures.

[0019] In addition, compared with the prior art, the diameter of the electric wire has been reduced. In a wire with a reduced diameter, since the current flowing through it remains unchanged, the heat generation temperature rises, and the heat received by the outer member increases. In the wire harness according to the embodiment, since the distance between the electric wire and the outer member having a specific two-layer structure is reduced, even if a wire with a reduced diameter is used, the heat dissipation effect can be fully exerted. Further, when a wire with a reduced diameter is used, the outer member around it will also be reduced in diameter, and as a result, the weight reduction and cost reduction of the wire harness can be achieved.

[0020] The wire harness according to the embodiment can be manufactured by integral molding. Specifically, by using a crosshead die, the electric wire 11 can be passed through the die, and the outer member 12 can be molded from above it. According to this manufacturing method, the distance D between the outer peripheral portion of the electric wire 11 and the inner peripheral portion of the outer member 12 can be adjusted within the above range.

[0021] FIG. 3 is a diagram for explaining a wire harness according to another embodiment. Specifically, FIG. 3 shows a cross-sectional view along the axial direction of the wire harness (the electric wire and the outer member) (a cross-sectional view cut along the central axis of the electric wire along the axial direction). In another embodiment, the outer member 12 is different from the above-described embodiment in that it further includes an intermediate layer 123 containing an olefin-based elastomer or a styrene-based elastomer between the inner layer 121 and the outer layer 122, and other points are the same as those of the above-described embodiment. By providing the intermediate layer 123, the impact resistance can be improved. Further, the thickness of the intermediate layer 123 is preferably 1.0 times or more and 4. times or less the thickness of the outer layer 122.

[0022] [Examples] [Example 1-1] Using a crosshead die, a wire 11 (standard…JASO D 625-5 Part 5: High-voltage copper wire, type…Table-1 Heat resistance class 150℃ / Cross-linked high-temperature resistant polyethylene insulated high-voltage wire for electric vehicles (EEHX), size…Table-13 50sq wire outer diameter standard 13.1mm) was passed through the die, and an outer sheath member 12 was formed over it to produce a wire harness 1 (Figures 1 and 2). Polyphenylene sulfide (PPS) was used as the material for the inner layer 121, and polyamide 6 (PA6) was used as the material for the outer layer 122. The inner diameter DI (inner diameter at the annular recess 12A), outer diameter DO (outer diameter at the annular protrusion 12B), pitch, and distance D of the exterior member 12 were as shown in Table 2.

[0023] [Examples 1-2 to 1-4] Wire harness 1 was manufactured in the same manner as in Example 1-1, except that the inner diameter DI of the outer casing member 12, the outer diameter DO of the outer casing member 12, the pitch of the outer casing member 12, and the distance D of the outer casing member 12 were changed to the values ​​in Table 2.

[0024] [Comparative Example 1-1~1-2] A wire harness was manufactured in the same manner as in Example 1-1, except that the inner diameter DI of the outer casing member 12, the outer diameter DO of the outer casing member 12, the pitch of the outer casing member 12, and the distance D of the outer casing member 12 were changed to the values ​​shown in Table 2.

[0025] [Evaluation Method and Results] <Power-on test> For the wire harnesses prepared in the examples or comparative examples, current was applied to the wires at a current of 400A and an ambient temperature of 70°C. After application of current, the maximum temperature was measured for the wires, the inner circumference of the outer casing (inner circumference of the annular recess), and the outer circumference of the outer casing (outer circumference of the annular protrusion). The results are shown in Table 2. When the maximum temperature at the inner circumference of the exterior component is 150°C or less, the heat dissipation effect is excellent, and when the maximum temperature at the inner circumference of the exterior component exceeds 150°C, the heat dissipation effect is poor. Table 2 also shows the difference (temperature increase) between the ambient temperature of 70°C and the maximum temperature for the inner circumference of the electric wire and the outer sheathing material (inner circumference of the annular recess). Furthermore, Figure 4 shows the temperature distribution in the axial and perpendicular directions of the wire harness (electric wires and outer sheathing members) for Example 1-1. Furthermore, in Example 1-1, the same results were obtained when polyamide 46 (PA46) was used instead of PPS as the material for the inner layer 121. Similarly, the same results were obtained when polypropylene (PP) or polyamide 66 (PA66) was used instead of PA6 as the material for the outer layer 122. Moreover, in Examples 1-2 to 1-4, the same results were obtained when PA46 was used as the material for the inner layer 121 or when PP or PA66 was used as the material for the outer layer 122.

[0026] [Table 2]

[0027] [Example 2-1] A wire harness 1 was fabricated in the same manner as in Example 1-1 (Figures 1 and 2). The thickness of the inner layer 121 was 1.0 to 4.0 times the thickness of the outer layer 122. The inner diameter of the exterior member 12 (inner diameter at the annular recess 12A), the pitch of the exterior member 12, and the distance D were the same as in Example 1-1 in Table 2.

[0028] [Example 2-2] A wire harness 100 was manufactured in the same manner as in Example 2-1, except that an intermediate layer 123 was added to the exterior member 12 (Figure 3). An olefin-based elastomer was used as the material for the intermediate layer 123. The thickness of the outer layer 122 and the inner layer 121 were equal, and the thickness of the intermediate layer 123 was 1.0 to 4.0 times that of the outer layer 122. The inner diameter of the exterior member 12 (inner diameter at the annular recess 12A), the pitch of the exterior member 12, and the distance D were the same as in Example 1-1 in Table 2.

[0029] [Evaluation Method and Results] <Impact Test> Impact tests were performed on the wire harnesses obtained in the examples. In the static impact test, the maximum load at which the test specimen fractured was recorded when it was crushed using a compression testing machine / JIS B 7721 with a test fixture having a 90° tip. In the dynamic impact test, a weight was attached to a compression testing machine / JIS B 7721 with a 90° tip, and it was dropped from a height of 1000 mm. The weight at which the test specimen fractured was recorded. The results are shown in Table 3.

[0030] [Table 3]

[0031] An electrical conduction test was also performed on the wire harnesses fabricated in Examples 2-1 and 2-2. In both Examples 2-1 and 2-2, the maximum temperature at the inner circumference of the outer casing was 150°C or less. Furthermore, in Example 2-2, the same results as in Example 2-2 were obtained when a styrene-based elastomer was used instead of an olefin-based elastomer as the material for the intermediate layer 123. [Explanation of Symbols]

[0032] 1,100 Wire Harness 11 Electric wire 12 Exterior components 121 Inner Layer 122 Outer layer 123 Middle Class

Claims

1. It includes an electric wire and a cylindrical outer member through which the electric wire is inserted. The exterior member comprises an inner layer made entirely of resin with a relative temperature index RTI2 of 150°C or higher, and an outer layer made entirely of resin with a relative temperature index RTI2 of 130°C or higher and less than 150°C (wherein the relative temperature index RTI2 is the ambient temperature at which the retention rate of mechanical strength after 10,000 hours of high-temperature exposure testing of the resin is 50%). The exterior member is a corrugated tube formed by alternating annular recesses and annular protrusions on the outer surface side, arranged concentrically along the axial direction of the tube. The inner diameter of the annular recesses is 13.1 mm or more and 13.9 mm or less, the outer diameter of the annular protrusions is 17.4 mm or more and 18.2 mm or less, and the pitch between the annular recesses and annular protrusions is 3.5 mm or less. Regarding the cross-section of the electric wire and the outer sheathing member in the direction perpendicular to the axial direction, the distance D between the outer circumference of the electric wire and the inner circumference of the annular recess of the outer sheathing member in the radial direction is 0.4 mm or less. The resin having a relative temperature index (RTI2) of 150°C or higher is polyphenylene sulfide or polyamide 46, and the resin having a relative temperature index (RTI2) of 130°C or higher and less than 150°C is polypropylene, polyamide 6, or polyamide 66. Wire harness.

2. The distance D is 0.3 mm or less. The wire harness according to claim 1.

3. The exterior member further includes an intermediate layer between the inner layer and the outer layer, which contains an olefin-based elastomer or a styrene-based elastomer. The wire harness according to claim 1 or 2.

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