Electric wire, heater, and heater for car seat

Abstract

An electric wire (1) according to the present invention comprises: twisted wiring (10) obtained by twisting a plurality of element wires (11); and an insulating layer (20) that covers the twisted wiring (10). Provided that the outer diameter of the twisted wiring (10) is X mm and the twist pitch of the twisted wiring (10) is Y mm, Y / X is 10-100.

Description

Electric wire, heater, and heater for car seat

[0001] The present invention relates to an electric wire, a heater, and a heater for a car seat.

[0002] There is known an electric wire in which a plurality of strands are twisted together to form a twisted wire, and the twisted wire is coated with an insulating layer. Such an electric wire can be used, for example, as an in-vehicle electric wire. Patent Document 1 discloses an in-vehicle electric wire having the above-described configuration.

[0003] International Publication No. 2019 / 026365

[0004] For the above-described electric wire, terminal processing may be performed to expose the twisted wire, which is a conductor, by peeling the insulating layer at the terminal. During such terminal processing, if the adhesion between the twisted wire and the insulating layer is too high, the surface of the twisted wire (the surface of the strands) may be peeled off together with the insulating layer, and the twisted wire may be damaged.

[0005] As a technique for reducing the adhesion between the twisted wire and the insulating layer, it is known to improve the slipperiness and reduce the adhesion by filling a lubricant between the twisted wire and the insulating layer. However, when such a technique is used, the outer diameter of the electric wire increases according to the amount of the lubricant filled.

[0006] An object of the present invention is to provide an electric wire capable of reducing the adhesion between a twisted wire and an insulating layer without using a lubricant, a heater having the electric wire, and a heater for a car seat having the heater.

[0007] According to one aspect of the present invention for solving the above problems, a twisted wire formed by twisting a plurality of strands together, an insulating layer covering the twisted wire, are provided, when the outer diameter of the twisted wire is X mm and the twist pitch of the twisted wire is Y mm, Y / X is 10 to 100, and an electric wire is provided.

[0008] According to another aspect of the present invention, a heater is provided, which includes the above-described electric wire used as a heating wire.

[0009] According to another aspect of the present invention, a heater for a car seat is provided, which has the above-described heater.

[0010] According to the present invention, it is possible to provide an electric wire that can reduce the adhesion between stranded wires and an insulating layer without using a lubricant, a heater having the electric wire, and a car seat heater having the heater.

[0011] Figure 1A is a cross-sectional view of an electric wire, and Figure 1B is a side view of the stranded wires of the electric wire.

[0012] The following describes stranded wires according to preferred embodiments of the present invention, but the present invention is not limited to these embodiments. In this specification, with respect to the notation of "~" indicating a numerical range, the lower limit and upper limit are included in that numerical range.

[0013] [Wire Structure] Figure 1A is a schematic cross-sectional view of a wire 1 according to one embodiment of the present invention, and Figure 1B is a schematic side view of the stranded wire 10 of the wire 1. As shown in Figures 1A and 1B, the wire 1 has a stranded wire 10 in which a plurality of strands 11 are twisted together, and an insulating layer 20 covering the stranded wire 10. The outer diameter of the wire 1 is, for example, about 0.4 to 2 mm.

[0014] Here, in the stranded wire 10 of the electric wire 1, if the outer diameter of the stranded wire 10 is X mm and the twist pitch of the stranded wire 10 is Y, then Y / X is between 10 and 100. If Y / X is 10 or less, the direction of extension of the strands 11 (direction of the spiral) is greatly inclined with respect to the longitudinal direction of the electric wire 1, increasing the degree of adhesion. Conversely, if Y / X is 100 or more, the inclination of the direction of extension of the strands 11 becomes smaller, and the degree of adhesion decreases.

[0015] Specifically, a Y / X ratio of 10 or more prevents excessive adhesion between the stranded wire 10 and the insulating layer 20 in the electric wire 1, thereby suppressing damage to the stranded wire 10 during terminal processing. In other words, a Y / X ratio of 10 or more prevents excessive contact area between the stranded wire 10 and the insulating layer 20 per unit length of the electric wire 1, thereby suppressing the degree of adhesion. From this viewpoint, a Y / X ratio of 15 or more is preferable.

[0016] On the other hand, if Y / X is 100 or less, the contact load between the strands 11 in the stranded wire 10 does not become too small, which prevents the stranded wire 10 from coming off the insulating layer 20 during terminal processing. In other words, if Y / X is 100 or less, the contact area between the stranded wire 10 and the insulating layer 20 per unit length of the electric wire 1 does not become too small, and the degree of adhesion can be maintained. From this viewpoint, it is preferable that Y / X be 80 or less, and more preferably 50 or less. Details of the relationship between these Y / X and terminal processability will be described later with reference to examples. The contact load between the stranded wire 10 and the insulating layer 20 is preferably 0.5 to 20 N. If the contact load is 0.5 N or less, the stranded wire 10 will come off the insulating layer 20 during terminal processing. Also, if the contact load is 20 N or more, a strong force is required when peeling off the insulating layer 20 due to the high adhesion, and there is a risk that the wire stripper will come into contact with the stranded wire 10 and damage it.

[0017] The twist pitch Y is the axial length of the stranded wire 10 when one of the multiple strands 11 that are twisted into a spiral shape (the strand 11 with a diagonal line in Figure 1B) is traced along this strand 11, and the strand 11 completes one revolution (360° rotation) around the central axis (spiral axis) of the stranded wire 10.

[0018] On the other hand, the outer diameter X was determined by either direct measurement of the stranded wire's outer diameter using a micrometer or video microscope, or by deriving it from the outer diameter of the individual wires 11 and their number using the formula (outer diameter = 1.155 × outer diameter of individual wires 11 × √ number of strands).

[0019] The details of the stranded wire 10 and insulating layer 20 of the electric wire 1 will be described below.

[0020] (Stranded wire) As described above, the stranded wire 10 is composed of multiple strands 11 twisted together. The number of strands 11 in the stranded wire 10 is not particularly limited. The number of strands 11 in the stranded wire 10 is, for example, about 5 to 40. The twist pitch Y and outer diameter X of the stranded wire 10 are not particularly limited as long as the above Y / X is satisfied. The twist pitch Y of the stranded wire 10 is, for example, about 2 to 60 mm. On the other hand, the outer diameter X of the stranded wire 10 is, for example, about 0.1 to 0.6 mm. The conductor resistance of the stranded wire 10 is not particularly limited.

[0021] As shown in Figure 1A, the wire strand 11 has a conductor 11a and a coating 11b covering the conductor 11a. In this embodiment, the wire strand 11 is an enameled wire, the conductor 11a is the conductor of the enameled wire, and the coating 11b is an enamel coating. The outer diameter of the wire strand 11 is, for example, about 0.03 mm to 0.08 mm.

[0022] The conductor 11a is not particularly limited as long as it is electrically conductive. Examples of materials for the conductor 11a include metals and metal alloys. Examples of metals and metal alloys include Cu, Ag, Cu-Ag alloys, etc. In this embodiment, the material of the conductor 11a is a Cu-Ag alloy, and the wire 11 is a Cu-Ag alloy wire with a coating 11b formed on the surface of the Cu-Ag alloy wire. The Cu content and Ag content of the Cu-Ag alloy are not particularly limited. In this embodiment, the Cu-Ag alloy contains, for example, 2 to 11 mass% of Ag, with the remainder being Cu and unavoidable impurities.

[0023] If the wire strand 11 is an enameled wire, the enameled coating may be an insulating coating formed by applying and baking a known varnish onto the conductor 11a. Examples of varnishes that constitute the insulating coating include polyvinyl acetal (e.g., polyvinyl formal or polyvinyl butyral), polyurethane, nylon, polyester, epoxy resin, polyesterimide, polyamide, polyimide, and polyamideimide.

[0024] (Insulating layer) The insulating layer 20 is not particularly limited as long as it can insulate the stranded wire 10. Examples of materials for the insulating layer 20 include resins, etc. More specifically, examples of materials for the insulating layer 20 include fluororesins, olefin resins, nylon resins, silicones, etc. Specifically, examples of resins include ETFE, FEP, PFA, polyamide, polypropylene, polyethylene, polyvinyl chloride, etc.

[0025] The thickness of the insulating layer 20 is not particularly limited as long as it can perform the desired insulating function. When the electric wire 1 is used as a heating wire, the thickness of the insulating layer 20 is preferably such that it can easily conduct heat. The thickness of the insulating layer 20 may be, for example, about 0.05 to 0.2 mm. The insulating layer 20 can be formed by extruding a material that forms the insulating layer 20 around the stranded wire 10.

[0026] (Effects) In the embodiment of the present invention, the adhesion between the stranded wire 10 and the insulating layer 20 is reduced. Therefore, damage to the stranded wire 10 is suppressed when the wire 1 is terminated. Also, the adhesion between the stranded wire 10 and the insulating layer 20 is not too low. Therefore, the stranded wire 10 is less likely to come loose when the wire 1 is terminated, making termination easier.

[0027] Furthermore, according to the electric wire 1 of this embodiment, the adhesion between the stranded wire 10 and the insulating layer 20 can be reduced without using a lubricant. Therefore, adhesion can be reduced without increasing the outer diameter of the electric wire 1. In addition, in the electric wire 1 of this embodiment, even if repeated external forces are applied, the friction between the stranded wire 10 and the insulating layer 20 is small, so the stranded wire 10 is less likely to be damaged. Therefore, when the electric wire 1 is used as a heating element in a heater, damage such as breakage of the stranded wire 10 is suppressed even if external forces are applied. For example, the electric wire 1 of this embodiment is suitable for heating elements that are subjected to repeated loads, such as car seat heaters.

[0028] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0029] We manufactured electric wires of samples 1 to 160. Below, we will first describe the manufacturing method and evaluation of electric wire sample 1. Next, for electric wires 2 to 160, we will only describe the differences from the manufacturing method and evaluation of electric wire sample 1. The parameters and evaluation results for each sample are shown in Tables 1 to 9.

[0030] (Manufacturing of Sample 1 Wire) Cu-Ag alloy wire was manufactured by heat-treating a cast rod of a Cu-based alloy containing 3 mass% Ag and the remainder being Cu and unavoidable impurities, and a wire that had been cold-worked to the middle, followed by further cold-working to 0.05 mm. The obtained Cu-Ag alloy wire was coated with varnish and baked to enamel-coate it, and 11 Cu-Ag alloy strands with a diameter of 0.06 mm were prepared. The 11 prepared strands were twisted together to obtain a stranded wire with a twist pitch of 1.3 mm. The outer diameter of the obtained stranded wire was measured to be 0.26 mm. That is, the Y / X ratio of the stranded wire of Sample 1 was 5.0.

[0031] An insulating layer with a thickness of 0.1 mm was formed around the resulting stranded wire by extrusion molding of ETFE resin. The outer diameter of the resulting wire was 0.46 mm.

[0032] (Evaluation of Sample 1 Wire) <Adhesion Load> The adhesion between the stranded wire and the insulation layer was investigated. The adhesion was tested according to the strip force in section 5.9 of ISO 6722-2. Specifically, a sample of Sample 1 wire was cut to 75 mm, and the insulation layer was stripped from one side of the sample (25 mm). A tensile testing machine was prepared equipped with a jig having a hole that was greater than or equal to the outer diameter of the stranded wire but less than the outer diameter of the wire. The stranded wire, with a portion of the insulation layer stripped and exposed, was inserted into the hole in the jig, and the wire was placed in the tensile testing machine. The adhesion load between the stranded wire and the insulation layer was measured by pulling the jig at 250 mm / min.

[0033] <Insulation Layer Peelability> The insulation layer of the electric wire was stripped using a wire stripper. The peelability of the insulation layer was evaluated according to the following criteria: ○: No damage to the wire's coating or conductor ×: Damage to the wire's conductor

[0034] <Presence or absence of stranded wire detachment> When the above-mentioned terminal processing was performed, the presence or absence of stranded wire detachment from the insulating layer was evaluated according to the following criteria: ○: No stranded wire detachment ×: Stranded wire detachment present

[0035] <Comprehensive Evaluation> The electric wires were comprehensively evaluated as follows based on the peelability of the insulating layer and the presence or absence of strand pulling-out described above. ○: Both the peelability of the insulating layer and the presence or absence of strand pulling-out were ○. ×: × was present in either the peelability of the insulating layer or the presence or absence of strand pulling-out.

[0036] (Manufacture and Evaluation of Electric Wires of Samples 2 to 160) Electric wires of Samples 2 to 160 were manufactured and evaluated in the same manner as the electric wire of Sample 1, except that the conditions shown in Tables 1 to 9 were changed.

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046] As shown in Tables 1 to 9, the samples with Y / X of 10 to 100 had good comprehensive evaluations. This is presumably because when Y / X is 10 or more, the adhesion between the strands and the insulating layer does not become too large, and the strands are not damaged when the insulating layer is peeled. On the other hand, when Y / X is 100 or less, the contact area between the strands and the insulating layer per unit length of the electric wire does not become too small, and the adhesion can be maintained, so strand pulling-out did not occur during terminal processing.

[0047] According to the present invention, an electric wire that is easy to process at the terminal can be provided.

[0048] 1 Electric wire 10 Strand 11 Strand wire 11a Conductor 11b Coating 20 Insulating layer

Claims

1. An electric wire comprising: a stranded wire formed by twisting together multiple strands; and an insulating layer covering the stranded wire, wherein when the outer diameter of the stranded wire is X mm and the twist pitch of the stranded wire is Y mm, Y / X is 10 to 100.

2. An electric wire according to claim 1, characterized in that the Y / X ratio is 10 to 50.

3. An electric wire according to claim 1, characterized in that the contact load between the stranded wire and the insulating layer is 0.5 to 20 N.

4. An electric wire according to claim 1, characterized in that the strands are Cu-Ag alloy strands.

5. An electric wire according to claim 1, characterized in that it is used as an electric heating wire.

6. A heater characterized by including the electric wire described in claim 5 as a heating element.

7. A car seat heater characterized by having the heater described in claim 6.

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