Wire assembly

Abstract

To provide a wire assembly which has good cut-off performance between a resin mold member and a resin coating.SOLUTION: A wire assembly includes a wire having a conductor and a resin coating, a terminal member connected to the conductor at the end of the wire, and a resin mold member covering a region from the terminal member and the resin coating, wherein a value of Y1 is equal to or more than 30. Y1=1.26×X1-5.02×103×X2+1.55×103×X4-2.36×10-1×X5+93. X1 is a bonding work of the resin mold member and the resin coating, and a unit is mJ / m2. X2 is a difference between strain of the resin mold member and strain of the resin coating, and a unit is no unit. X4 is a difference between a coefficient of linear expansion of the resin mold member, and a coefficient of linear expansion of the resin coating, and a unit is 1 / °C. X5 is an elastic modulus of the resin coating, and a unit is MPa.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electric wire assembly.

Background Art

[0002] Patent Document 1 discloses a composite cable in which a first electric wire and a multi-core electric wire are collectively covered with an outer skin. The multi-core electric wire has a configuration in which a plurality of second electric wires are covered with an inner sheath. The second electric wire includes a conductor and an insulating layer. The inner sheath is a resin coating disposed on the outermost periphery of the multi-core electric wire. At the end of the multi-core electric wire, a terminal member and a resin molding member are provided. The terminal member is a sensor or the like electrically connected to the conductor of the second electric wire. The resin molding member covers a region extending from the terminal member to the outer periphery of the inner sheath. The resin molding member seals the connection portion between the conductor and the terminal member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to seal the connection portion, it is necessary for the resin molding member and the inner sheath which is a resin coating to adhere to each other without a gap. However, depending on the compatibility between the resin constituting the resin molding member and the resin constituting the resin coating, there is a possibility that sufficient water sealing performance cannot be obtained. This compatibility may vary depending on the grade of the resin, the molecular weight of the resin, or the ratio of additives contained in the resin. For example, there is a difference in the adhesion ability to the resin coating between a resin molding member composed of resin A and a resin molding member composed of resin A containing an additive.

[0005] In view of the above circumstances, one of the objectives of the present disclosure is to provide a wire assembly with good water-stopping performance between a resin molded member and a resin coating.

Means for Solving the Problems

[0006] The wire assembly of the present disclosure includes: a wire having a conductor and a resin coating; a terminal member connected to the conductor at an end of the wire; and a resin molded member covering a region from the terminal member to the resin coating. The value of Y1 obtained by the following formula (A) is 30 or more. Y1 = 1.26×X1 - 5.02×10 3 ×X2 + 1.55×10 3 ×X4 - 2.36×10 -1 ×X5 + 93… Formula (A) Here, X1 is the adhesion work between the resin molded member and the resin coating, with the unit of mJ / m 2 、 X2 is the difference between the strain of the resin molded member and the strain of the resin coating, with the unit being dimensionless; X4 is the difference between the linear expansion coefficient of the resin molded member and the linear expansion coefficient of the resin coating, with the unit of 1 / °C; X5 is the elastic modulus of the resin coating, with the unit of MPa.

[0007] Another wire assembly of the present disclosure includes: a wire having a conductor and a resin coating; a terminal member connected to the conductor at an end of the wire; and a resin molded member covering a region from the terminal member to the resin coating. The value of Y2 obtained by the following formula (B) is 30 or more. Y2 = -3.59×10 3 ×X2 + 4.99×10×X3 - 1.20×10 5 ×X4 - 2.65×10 -1 ×X5 + 139… Formula (B) Here, X2 is the difference between the strain of the resin molded member and the strain of the resin coating, and the unit is dimensionless. X3 is the shear adhesion strength between the resin molded member and the resin coating, and the unit is MPa. X4 is the difference between the linear expansion coefficient of the resin molded member and the linear expansion coefficient of the resin coating, and the unit is 1 / °C. X5 is the elastic modulus of the resin coating, and the unit is MPa.

Advantages of the Invention

[0008] The wire assembly of the present disclosure is excellent in water-stopping performance between the resin molded member and the resin coating in the wire assembly.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0010] [Description of Embodiments of the Present Disclosure] The inventors of the present invention identified physical quantities related to the adhesiveness between the resin molded member and the resin coating, and considered evaluating the water-stopping property between the resin molded member and the resin coating depending on whether the physical quantity is equal to or greater than a predetermined value. As a result, it was found that in a wire assembly that satisfies Formula (A) or Formula (B), sufficient water-stopping property between the resin molded member and the resin coating is ensured. Details of Formula (A) and Formula (B) will be described later. The wire assembly of the present disclosure was obtained based on the above findings.

[0011] First, the contents of the embodiments of the present disclosure will be listed and described.

[0012] <1>The wire assembly according to the embodiment is An electric wire having a conductor and a resin coating, a terminal member connected to the conductor at an end of the electric wire, and a resin molding member covering a region from the terminal member to the resin coating, The value of Y1 obtained by the following formula (A) is 30 or more. Y1 = 1.26×X1 - 5.02×10 3 ×X2 + 1.55×10 3 ×X4 - 2.36×10 -1 ×X5 + 93…Formula (A) Here, X1 is the adhesion work between the resin molding member and the resin coating, and the unit is mJ / m 2 、 X2 is the difference between the strain of the resin molding member and the strain of the resin coating, and the unit is dimensionless, X4 is the difference between the linear expansion coefficient of the resin molding member and the linear expansion coefficient of the resin coating, and the unit is 1 / ℃, X5 is the elastic modulus of the resin coating, and the unit is MPa.

[0013] Formula (A) is a formula for estimating the leak pressure of the wire assembly based on the physical quantities X1, X2, X4, and X5 related to the adhesion between the resin molding member and the resin coating. That is, Y1 is an estimated value of the leak pressure obtained from the physical quantities X1, X2, X4, and X5. Details of the physical quantities X1, X2, X4, and X5 will be described in detail in the embodiments. The leak pressure is obtained when the wire assembly is subjected to a predetermined leak test. The leak test is a test for examining whether air leaks from the interface between the resin coating and the resin molding member when pressure is applied to the inside of the resin coating of the electric wire by an air pump and air is sent in, as shown in Test Example 1 described later. The leak pressure is the value of the pressure meter of the air pump when air leaks from the above interface. The unit of the leak pressure is kPa. That is, if Y1 obtained from Formula (A) is 30, the leak pressure of the wire assembly is estimated to be 30 kPa.

[0014] If the leakage pressure is 30 kPa or more, it can be determined that the water-stopping property between the resin molded member and the resin coating is sufficiently high. Therefore, if the physical quantities X1, X2, X4, and X5 obtained by examining the wire assembly are substituted into Equation (A) and the value of Y1 obtained is 30 or more, it can be said that the wire assembly has sufficient water-stopping performance.

[0015] <2>Another wire assembly according to the embodiment is a wire having a conductor and a resin coating, a terminal member connected to the conductor at an end of the wire, and a resin molded member covering a region from the terminal member to the resin coating. The value of Y2 obtained by the following formula (B) is 30 or more. Y2 = -3.59×10 3 ×X2 + 4.99×10×X3 - 1.20×10 5 ×X4 - 2.65×10 -1 ×X5 + 139… Formula (B) Here, X2 is the difference between the strain of the resin molded member and the strain of the resin coating, and the unit is dimensionless, X3 is the shear adhesive strength between the resin molded member and the resin coating, and the unit is MPa, X4 is the difference between the linear expansion coefficient of the resin molded member and the linear expansion coefficient of the resin coating, and the unit is 1 / °C, X5 is the elastic modulus of the resin coating, and the unit is MPa.

[0016] Formula (B) is a formula for estimating the leakage pressure of the wire assembly based on the physical quantities X2, X3, X4, and X5 related to the adhesiveness between the resin molded member and the resin coating. That is, Y2 is an estimated value of the leakage pressure obtained from the physical quantities X2, X3, X4, and X5. Details of the physical quantities X2, X3, X4, and X5 will be described in detail in the embodiment. The physical quantities X2, X4, and X5 are the same as the physical quantities X2, X4, and X5 in the above embodiment <1>. The definition of the leakage pressure is the same as in the above embodiment <1>. If Y2 obtained from Formula (B) is 30, the leakage pressure of the wire assembly is estimated to be 30 kPa.

[0017] If the leakage pressure is 30 kPa or more, it can be determined that the water-stopping property between the resin-molded member and the resin coating is sufficiently high. Therefore, by substituting the physical quantities X2, X3, X4, and X5 obtained by examining the wire assembly into Equation (B), if the obtained value of Y2 is 30 or more, it can be said that the wire assembly has sufficient water-stopping performance.

[0018] <3> In an example of the wire assembly according to the embodiment, The resin-molded member covers the entire terminal member.

[0019] In a wire assembly in which the resin-molded member covers the entire terminal member, only the interface between the resin-molded member and the resin coating is the route for moisture to penetrate into the connection portion between the conductor of the wire and the terminal member. In the wire assembly of the embodiment, since the water-stopping property between the resin-molded member and the resin coating is high, it is difficult for moisture to adhere to the above connection portion. Therefore, corrosion of the conductor or damage to the terminal member is suppressed.

[0020] <4> In an example of the wire assembly according to the embodiment, The main component of the resin-molded member is polyamide resin, polyphenylene sulfide resin, or polybutylene terephthalate resin.

[0021] These resins are excellent in heat resistance and are suitable as materials for the resin-molded member.

[0022] <5> In an example of the wire assembly according to the embodiment, The main component of the resin coating is polyester or polyurethane.

[0023] These resins are excellent in flexibility and are suitable as resin coatings for wires that are required to be easily bent.

[0024] <6> In an example of the wire assembly according to the embodiment, The terminal member is a sensor.

[0025] If the terminal member is a sensor, it can measure the physical quantity in the device equipped with the wire assembly. For example, when the wire assembly is mounted on a vehicle, the sensor can monitor the physical quantity related to the operation of the vehicle. The type of the sensor is not particularly limited.

[0026] [Details of Embodiments of the Present Disclosure] Hereinafter, with appropriate reference to the drawings, embodiments of the present disclosure will be described in detail. The same reference numerals in the drawings indicate the same named objects. The present invention is not limited to the examples of the embodiments, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0027] [Embodiment 1] The wire assembly 1 of this example shown in FIG. 1 includes a wire 2, a resin molding member 3, and a terminal member 4. One of the features of the wire assembly 1 of this example is that the resin coating 23 disposed on the outermost periphery of the wire 2 and the resin molding member 3 are firmly adhered to each other. Hereinafter, each component of the wire assembly 1 will be described. Next, an index indicating that the water resistance between the resin coating 23 and the resin molding member 3 is sufficient due to the firm adhesion between the resin coating 23 and the resin molding member 3 will be described.

[0028] [[Wire]] As shown in the cross-sectional view of FIG. 2, the wire 2 of this example is a multi-core wire, so-called twisted pair cable. The wire 2 of this example includes two core wires 2A and 2B. The core wire 2A and the core wire 2B of this example have the same configuration. The number of core wires is not particularly limited. The configurations of the plurality of core wires may be different. Different from this example, the wire 2 may be a single-core wire.

[0029] The core wires 2A and 2B include a conductor 20 and an insulating layer 21. The conductor 20 is made of a conductive material such as aluminum, aluminum alloy, copper, or copper alloy. The conductor 20 is electrically connected to the terminal member 4 (FIG. 1). The insulating layer 21 is made of an insulating resin such as polyvinyl chloride or polyethylene.

[0030] The two core wires 2A and 2B are arranged inside the tubular resin coating 23. The resin coating 23 in this example is a so-called sheath. In this example, there is a gap between the core wires 2A and 2B and the resin coating 23. Different from this example, the space between the core wires 2A and 2B and the resin coating 23 may be filled with inclusions such as resin. Examples of the inclusions include urethane resin. A shielding layer or the like may be provided on the inner peripheral side of the resin coating 23.

[0031] As shown in FIG. 1, a part of the resin mold member 3 is arranged on the outer periphery of the resin coating 23. The inner peripheral surface of the resin mold member 3 adheres to the outer peripheral surface of the resin coating 23. The main component of the resin coating 23 is a resin material. The main component means a component having a content of 50% by mass or more in the resin coating 23. The resin material is, for example, polyurethane (PU) resin, or polyester (PE) resin. The resin coating 23 may contain additives such as a flame retardant or a filler.

[0032] Here, even if the resin materials constituting the resin coating 23 are the same, the adhesiveness between the resin coating 23 and the resin mold member 3 changes depending on the number of branched chains of the resin material, the molecular weight, the type of additives contained in the resin coating 23, and the content of the additives. Therefore, even if the resin coating 23 is made of, for example, PU resin, there may be a case where the values of formula (A) or formula (B) described later cannot be satisfied.

[0033] ≪Terminal member≫ The terminal member 4 shown in FIG. 1 is electrically connected to the conductor 20 (FIG. 2) of the electric wire 2. The terminal member 4 in this example is a wheel speed sensor. The sensor is not limited to a wheel speed sensor. For example, the sensor may be a temperature sensor, an acceleration sensor, or the like. Different from this example, the terminal member 4 may be a terminal or the like.

[0034] ≪Resin mold member≫ The resin mold member 3 covers the region from the terminal member 4 to the resin coating 23. In this example, the resin mold member 3 covers the entire terminal member 4.

[0035] The resin molded member 3 overlaps the outer periphery of the resin coating 23 of the electric wire 2. That is, the inner peripheral surface of the resin molded member 3 adheres to the outer peripheral surface of the resin coating 23. The resin molded member 3 suppresses the adhesion of moisture to the connection portion between the conductor 20 (FIG. 2) of the electric wire 2 and the terminal member 4. The longer the overlapping length L0 of the resin molded member 3 and the resin coating 23 along the longitudinal direction of the electric wire 2, the better the water-stopping property by the resin molded member 3. If the length L0 is too long, the resin molded member 3 becomes large, and it becomes difficult to arrange the electric wire assembly 1 in the device. From the viewpoints of improving the water-stopping property and suppressing the increase in size, the length L0 is preferably, for example, 1 mm or more and 100 mm or less. The length L0 may further be 5 mm or more and 50 mm or less.

[0036] Unlike this example, when the electric wire 2 is a single-core wire, the resin molded member 3 covers the outer periphery of the insulating layer 21 disposed on the outer periphery of the conductor 20. That is, in the electric wire assembly including a single-core wire, the insulating layer 21 corresponds to the resin coating of the electric wire 2.

[0037] The outer shape of the resin molded member 3 is not particularly limited. The outer shape of the resin molded member 3 in this example is a shape along the outer shape of the terminal member 4. Unlike this example, the resin molded member 3 may include a flange or the like for fixing the electric wire assembly 1 to the attachment target.

[0038] The main component of the resin molded member 3 is a resin material. The main component means a component having a content of 50% by mass or more in the resin molded member 3. The resin material is, for example, a polyamide (PA) resin, a polyphenylene sulfide (PPS) resin, or a polybutylene terephthalate (PBT) resin. The resin molded member 3 may contain additives such as a flame retardant or a filler.

[0039] Here, even if the resin materials constituting the resin mold member 3 are the same, the adhesiveness between the resin coating 23 and the resin mold member 3 changes depending on the number of branched chains of the resin material, the molecular weight, the types of additives contained in the resin mold member 3, and the content of the additives. Therefore, even if the resin mold member 3 is made of, for example, a PA resin, there may be cases where the values of formula (A) or formula (B) described later cannot be satisfied.

[0040] ≪Waterproofing index≫ The waterproofing between the resin mold member 3 and the resin coating 23 in the wire assembly 1 can be evaluated by the leak pressure. The leak pressure can be obtained by performing the leak test of Test Example 1 described later. The leak test is a test for examining whether air leaks from the interface between the resin coating 23 and the resin mold member 3 when pressure is applied to the inside of the resin coating 23 of the wire 2 by an air pump to send air. The leak pressure is the value of the pressure meter of the air pump when air leaks from the above interface. If the leak pressure is 30 kPa or more, it can be determined that the waterproofing of the wire assembly 1 is sufficient. If the leak pressure is 50 kPa or more, it can be determined that the waterproofing of the wire assembly 1 is satisfactory.

[0041] The wire assembly 1 of this example satisfies that the value of Y1 obtained by the following formula (A) or the value of Y2 obtained by the following formula (B) is 30 or more. Formula (A) and formula (B) are formulas for estimating the leak pressure of the wire assembly 1 based on physical quantities obtained by examining the wire assembly 1. The units of Y1 and Y2 are kPa. Therefore, if Y1 or Y2 is 30, the leak pressure is estimated to be 30 kPa. By obtaining Y1 or Y2, the waterproofing between the resin mold member 3 and the resin coating 23 can be evaluated without performing a leak test.

[0042] · Formula (A) Y1 = 1.26×X1 - 5.02×10 3 ×X2 + 1.55×10 3 ×X4 - 2.36×10 -1 ×X5 + 93 X1…Adhesive work between the resin mold member 3 and the resin coating 23 X2…Difference between the distortion of the resin molded member 3 and the distortion of the resin coating 23 X4…Difference between the linear expansion coefficient of the resin molded member 3 and the linear expansion coefficient of the resin coating 23 X5…Elastic modulus of the resin coating 23

[0043] ·Formula (B) Y2 = -3.59×10 3 ×X2 + 4.99×10×X3 - 1.20×10 5 ×X4 - 2.65×10 -1 ×X5 + 139 X2…Same as X2 in formula (A) X3…Shear adhesion strength between the resin molded member 3 and the resin coating 23 X4…Same as X4 in formula (A) X5…Same as X5 in formula (A)

[0044] Formula (A) and formula (B) are obtained by performing multiple regression analysis on the data of Test Example 1 described later. Multiple regression analysis is to calculate a regression equation representing the target variable by a plurality of explanatory variables. In this example, X1, X2, X3, X4, X5 correspond to the explanatory variables, and Y1, Y2 correspond to the target variables. The details of X1 to X5 to be substituted into formula (A) or formula (B) will be described below.

[0045] ≪Adhesion work≫ X1 in formula (A) is the adhesion work. The unit of X1 is mJ / m 2 is. The adhesion work is an index indicating the magnitude of the adhesiveness between the resin molded member 3 and the resin coating 23. That is, the adhesion work is an index indicating that it is difficult for the resin molded member 3 to peel off from the resin coating 23, and is also an index for evaluating the water-stopping property between the resin molded member 3 and the resin coating 23.

[0046] The adhesion work is determined from the surface free energy of the resin mold member 3 and the surface free energy of the resin coating 23. The surface free energy corresponds to the surface tension in a solid. To determine the adhesion work, first, the surface free energy of the resin mold member 3 and the surface free energy of the resin coating 23 are determined. The surface free energy is determined by using the following Young's equation and extended Fowkes equation.

[0047] ·Young's equation γ S =γ L cosθ+γ SL θ…Contact angle of a droplet stationary on the surface of the solid; unit is (π / 180) rad γ S …Surface tension of the solid, i.e., surface free energy; unit is mJ / m 2 γ L …Surface tension of the liquid constituting the droplet; unit is mJ / m 2 γ SL …Interface tension between the solid and the liquid; unit is mJ / m 2

[0048] ·Extended Fowkes equation γ SL =γ S +γ L -2(γ S d γ L d ) 1 / 2 -2(γ S p γ L p ) 1 / 2 -2(γ S H γ L H ) 1 / 2 γ L d …Dispersion component in the surface tension of the liquid γ L P …Polar component in the surface tension of the liquid γ L H … Hydrogen bond component in the surface tension of the liquid γ S d … Dispersion component in the surface free energy of the solid γ S P … Polar component in the surface free energy of the solid γ S H … Hydrogen bond component in the surface free energy of the solid The unit of each component of the surface tension is mJ / m 2 , and the unit of each component of the surface free energy is mJ / m 2 That is. Note that there is also an induction component in the surface tension, but since the induction component is very small, it can be ignored.

[0049] Substituting Young's equation into γ in the extended Fowkes equation gives the following equation (1). SL

[0050] · Equation (1) γ L (1 + cosθ) = 2(γ S d γ L d ) 1 / 2 + 2(γ S p γ L p ) 1 / 2 + 2(γ S H γ L H ) 1 / 2

[0051] The surface free energy of the solid is obtained by attaching three known types of liquids to the solid and measuring the contact angle θ. For example, γ related to the surface free energy of the resin mold member 3 L , γ L d , γ L p , γ L H is obtained by attaching three known types of liquids to the solid and measuring the contact angle θ. For example, γ related to the surface free energy of the resin mold member 3 S d, γ S P , γ S H To obtain γ, the first liquid, the second liquid, and the third liquid with known surface tension values are each attached to the resin mold member 3 to obtain three linear equations with three unknowns. By solving the three linear equations with three unknowns, γ S d , γ S P , γ S H can be obtained. Examples of liquids with known surface tension components include pure water. The method for obtaining the surface free energy of the resin coating 23 is the same as the method for obtaining the surface free energy of the resin mold member 3.

[0052] The adhesion work is obtained by the Dupre's equation shown below.

[0053] ·Dupre's equation γ 12 + W = γ 1 + γ 2 W... Adhesion work; unit is mJ / m 2 γ 12 ... Interfacial free energy; unit is mJ / m 2 γ 1 ... Surface free energy of the resin mold member 3 γ 2 ... Surface free energy of the resin coating 23

[0054] Here, γ 12 is obtained by the extended Fowkes equation shown below.

[0055] ·Extended Fowkes equation γ 12 = γ 1 + γ 2 - 2(γ 1 d γ 2 d ) 1 / 2 - 2(γ 1 p γ 2 p )1 / 2 -2(γ 1 H γ 2 H ) 1 / 2 γ 1 d …Dispersion component of the surface free energy of the resin molded member 3 γ 1 P …Polar component of the surface free energy of the resin molded member 3 γ 1 H …Hydrogen bond component of the surface free energy of the resin molded member 3 γ 2 d …Dispersion component of the surface free energy of the resin coating 23 γ 2 P …Polar component of the surface free energy of the resin coating 23 γ 2 H …Hydrogen bond component of the surface free energy of the resin coating 23

[0056] Substituting the extended Fowkes' equation into Dupre's equation gives the following equation (2).

[0057] ·Equation (2) W = 2(γ 1 d γ 2 d ) 1 / 2 + 2(γ 1 p γ 2 p ) 1 / 2 + 2(γ 1 H γ 2 H ) 1 / 2

[0058] Each component of the surface free energy of the resin molded member 3 substituted into Equation (2) is obtained by Equation (1). Similarly, each ChengThe minute is also obtained by Equation (1). If W obtained by Equation (2) is, for example, 45 mJ / m 2 then 45 is substituted into X1 of Equation (A).

[0059] If the adhesion work W is large, it can be said that the resin mold member 3 and the resin coating 23 are firmly adhered. The adhesion work W in the wire assembly 1 of this example is 45 mJ / m 2 or more, which is preferable. If the value of the adhesion work W is 45 mJ / m 2 or more, the water blocking property between the resin mold member 3 and the resin coating 23 is likely to be kept good. The adhesion work W is preferably 65 mJ / m 2 or more, and more preferably 80 mJ / m 2 or more.

[0060] ≪Difference in Strain≫ X2 in Equation (A) and Equation (B) is the difference in strain. The difference in strain is the difference between the strain of the resin mold member 3 and the strain of the resin coating 23 when the temperature changes from 90°C to 20°C. The unit of X2 is dimensionless. The procedure for forming the resin mold member 3 on the outer peripheries of the electric wire 2 and the terminal member 4 is as follows. Among the electric wires 2 to which the terminal member 4 is connected, the end portion of the electric wire 2 including the terminal member 4 is placed in the mold. Then, the molten material of the resin mold member 3 is injected into the mold. The temperature of the mold is about 70°C. When the molten material flows into the mold, the resin coating 23 placed in the mold is heated to about 90°C. When the wire assembly 1 is removed from the mold, the wire assembly 1 is cooled to room temperature. Assuming the room temperature is 20°C, the temperature of the resin mold member 3 and the temperature of the resin coating 23 change from 90°C to 20°C during the manufacture of the wire assembly 1. Due to the temperature change, strain occurs in the resin mold member 3. Similarly, strain also occurs in the resin coating 23. If there is a difference between the strain of the resin mold member 3 and the strain of the resin coating 23, stress acts on the interface between the resin mold member 3 and the resin coating 23. This stress is a force that peels the resin mold member 3 from the resin coating 23. Therefore, the difference between the strain of the resin mold member 3 and the strain of the resin coating 23 can be said to be an index for evaluating the water blocking property between the resin mold member 3 and the resin coating 23.

[0061] The strain of each member is determined based on the coefficient of linear expansion. The coefficient of linear expansion of the resin mold member 3 and the coefficient of linear expansion of the resin coating 23 are measured by a method compliant with JIS K 7197:2012. Specifically, these coefficients of linear expansion are measured by TMA. In TMA, the coefficient of linear expansion (1 / °C) for every 10°C can be obtained. Specifically, the coefficient of linear expansion X1 from 20°C to 30°C, the coefficient of linear expansion X2 from 30°C to 40°C, the coefficient of linear expansion X3 from 40°C to 50°C, the coefficient of linear expansion X4 from 50°C to 60°C, the coefficient of linear expansion X5 from 60°C to 70°C, the coefficient of linear expansion X6 from 70°C to 80°C, and the coefficient of linear expansion X7 from 80°C to 90°C are obtained. As shown in the following formula (3), the strain of each member can be determined by multiplying the sum of the coefficients of linear expansion from 90°C to 20°C by the temperature difference.

[0062] · Formula (3) Strain = (X1 + X2 + X3 + X4 + X5 + X6 + X7) × 70

[0063] The difference in strain is the absolute value of the difference between the strain of the resin mold member 3 obtained by formula (3) and the strain of the resin coating 23 obtained by formula (3). A small difference in strain means that it is difficult for a strong stress to act on the interface between the resin mold member 3 and the resin coating 23. Therefore, the difference in strain is preferably 0.02 or less. A more preferable difference in strain is 0.0129 or less, and an even more preferable difference in strain is 0.0011 or less.

[0064] ≪Shear Adhesion Strength≫ X3 in formula (B) is the shear adhesion strength. The unit of X3 is MPa. The shear adhesion strength is the load leading to the failure of adhesion divided by the contact area when a tensile test is performed to pull the electric wire 2 and the resin mold member 3 in a direction away from each other. Therefore, the shear adhesion strength can be said to be an index for evaluating the water tightness between the resin mold member 3 and the resin coating 23.

[0065] The shear adhesion strength in this example can be obtained as follows. For example, cut the wire assembly 1 at the position indicated by the two-dot chain line in Fig. 1. Chuck the outer circumference of the wire 2 and the resin mold member 3 respectively, and pull the wire 2 in a direction away from the resin mold member 3 along the stretching direction of the wire 2. The pulling speed is 10 mm / min. Measure the load when either the resin mold member 3 or the resin coating 23 is broken. Divide the load by the contact area between the resin mold member 3 and the resin coating 23. The unit of the load is N, and the unit of the contact area is mm 2 is. The contact area is obtained by multiplying the circumference of the wire 2, that is, the circumference of the resin coating 23, by the length L1. The circumference is obtained by multiplying the diameter of the wire 2 by π. The length L1 is the distance from the cut surface of the wire assembly 1 to the end of the resin mold member 3 on the wire 2 side.

[0066] When the shear adhesion strength between the resin mold member 3 and the resin coating 23 is large, it can be said that the resin mold member 3 and the resin coating 23 are firmly adhered. Therefore, the shear adhesion strength is preferably 0.2 MPa or more. A more preferable shear adhesion strength is 0.8 MPa or more, and an even more preferable shear adhesion strength is 1.5 MPa or more. If the shear adhesion strength obtained by measurement is, for example, 0.2 MPa, substitute 0.2 into X3 of formula (B).

[0067] ≪Difference in coefficient of linear expansion≫ X4 in formula (A) and formula (B) is the difference in coefficient of linear expansion. The unit of X4 is 1 / °C. The coefficient of linear expansion relates to the amount of expansion and contraction of a member accompanying temperature change. Therefore, if there is a difference between the coefficient of linear expansion of the resin mold member 3 and the coefficient of linear expansion of the resin coating 23, stress acts on the interface between the resin mold member 3 and the resin coating 23. Therefore, the difference between the coefficient of linear expansion of the resin mold member 3 and the coefficient of linear expansion of the resin coating 23 can be said to be an index for evaluating the water tightness between the resin mold member 3 and the resin coating 23. The coefficient of linear expansion of the resin mold member 3 and the coefficient of linear expansion of the resin coating 23 are respectively obtained by TMA.

[0068] If the difference between the linear expansion coefficient of the resin molded member 3 and the linear expansion coefficient of the resin coating 23 is large, peeling may occur at the interface between the resin molded member 3 and the resin coating 23 during the manufacture of the wire assembly 1. If the difference in the linear expansion coefficient at 20°C is 2.2×10 -4 / °C or less, the water-blocking property between the resin molded member 3 and the resin coating 23 is likely to be kept good. The difference in the linear expansion coefficient is more preferably 2.0×10 -4 / °C or less, and even more preferably 1.5×10 -4 / °C or less.

[0069] ≪Elastic Modulus≫ X5 in Formula (A) and Formula (B) is the elastic modulus of the resin coating 23. The unit of X5 is MPa. As described above, during the manufacture of the wire assembly 1, the resin coating 23 of the wire 2 is heated in a mold. If the elastic modulus of the resin coating 23 is large, when the wire assembly 1 is removed from the mold and the resin coating 23 is cooled to room temperature, a large strain occurs in the resin coating 23. The stress generated in the resin coating 23 due to this strain may cause the resin coating 23 to peel from the resin molded member 3. The stress is the product of the strain generated in the resin coating 23 and the elastic modulus of the resin coating 23. Therefore, by selecting a resin coating 23 with a low elastic modulus, it becomes difficult for the resin coating 23 to peel from the resin molded member 3. Among the temperature range of the resin coating 23 in the manufacturing process of the wire assembly 1, since the elastic modulus of the resin coating 23 is maximum at 20°C, it is necessary to measure the elastic modulus of the resin coating 23 at 20°C in order to evaluate the water-blocking performance. The elastic modulus is determined by a measuring method conforming to JIS K 7244.

[0070] If the elastic modulus of the resin coating 23 is 100 MPa or less, the water-blocking property between the resin molded member 3 and the resin coating 23 is likely to be kept good. The elastic modulus is preferably 60 MPa or less, and more preferably 20 MPa or less. If the elastic modulus obtained by measurement is, for example, 100 MPa, 100 is substituted for X5 in Formula (A) or Formula (B).

[0071] <Test Example 1> In this test example, data for obtaining formula (A) or formula (B) was acquired. Specifically, wire assemblies 1 from sample No. 1 to sample No. 6 were fabricated, where the material of the resin mold member 3 and the material of the resin coating 23 were different. The resin mold member 3 is either the resin mold member A shown in Table 1 or the resin mold member B. The resin mold member A is composed of PA6T, a heat-resistant PA resin. The melting point of the resin mold member A is 300°C. The resin mold member B is composed of PA612, a type of PA resin. The melting point of the resin mold member B is 220°C.

[0072]

Table 1

[0073] The resin coating 23 is either the resin coating C, resin coating D, resin coating E, resin coating F, resin coating G, or resin coating H shown in Table 2. In the resin coatings where the cross-linking item in Table 2 is 'Yes', the resin is cross-linked. The resin coatings where the filler item is 'Yes' contain fillers. The resin coatings where the flame retardant item is 'Yes' contain flame retardants. The flame retardant was a metal hydroxide. The filler content in resin coating C was 50% by mass when resin coating C was taken as 100% by mass. The filler content in resin coating F was 40% by mass when resin coating F was taken as 100% by mass.

[0074]

Table 2

[0075] The wire assemblies 1 from Sample No. 1 to Sample No. 6 were subjected to a leak test. The outline of the leak test is shown in Fig. 3. As shown in Fig. 3, water was filled in the water tank 7, and the resin mold member 3 of the wire assembly 1 was placed underwater. Next, air was sent into the interior of the wire 2 from the end opposite to the resin mold member 3 by an air pump (not shown). The pressure of the air was gradually increased, and the value of the pressure meter of the air pump when air leaked from the gap between the resin mold member 3 and the resin coating 23 was recorded. The value of the pressure meter when air leakage occurred is called the leak pressure (kPa). If the leak pressure is 30 kPa or more, it can be judged that the water blocking property is good, and if it is 50 kPa or more, it can be judged that the water blocking property is excellent. The results of the leak pressure are shown in Table 3. Table 3 also shows the material of each sample, the adhesion work (mJ / m 2 ), the difference in strain, the shear adhesion strength (MPa), the difference in the linear expansion coefficient, and the elastic modulus (MPa) of the resin coating. The measurement methods of each physical quantity were obtained based on the methods shown in the embodiment.

[0076] [Table 3]

[0077] As shown in Table 3, the leak pressures of the wire assemblies 1 of Sample No. 1 to Sample No. 4 with an adhesion work of 45 mJ / m 2 or more were far exceeding 30 kPa. It can be judged that the water blocking property of the wire assemblies 1 of Sample No. 1 to Sample No. 4 is good. By comparing Sample No. 1 to Sample No. 4, it was found that the higher the adhesion work, the higher the leak pressure. In particular, the leak pressures of Sample No. 1 and Sample No. 2 with an adhesion work of 65 mJ / m 2 or more were far exceeding 50 kPa.

[0078] From the results shown in Table 3, it was found that when the difference in strain is 0.02 or less, the shear adhesion strength is 0.2 MPa or more, the difference in the linear expansion coefficient is 2.2×10 -4 or less, and the elastic modulus of the resin coating is 100 MPa or less, the leak pressure of the wire assembly 1 becomes 30 kPa or more.

[0079] Perform multiple regression analysis using the numerical values of the adhesion work, the difference in strain, the difference in coefficient of linear expansion, the numerical value of the elastic modulus of the resin coating, and the numerical value of the leak pressure for Sample Nos. 1 to 6 shown in Table 3. In multiple regression analysis, the coefficients a1, a2, a3,... and the intercept b in the following regression equation are calculated from the data of the objective variable y and a plurality of explanatory variables x1, x2, x3,.... ·Regression equation: y = a1×x1 + a2×x2 + a3×x3... + b In this example, the leak pressure is the objective variable. The adhesion work, the difference in strain, the difference in coefficient of linear expansion, and the elastic modulus of the resin coating are the explanatory variables, respectively. By multiple regression analysis, Equation (A) can be obtained. Similarly, perform multiple regression analysis using the numerical values of the difference in strain, the numerical value of the shear adhesion strength, the difference in coefficient of linear expansion, the numerical value of the elastic modulus of the resin coating, and the numerical value of the leak pressure for Sample Nos. 1 to 6 shown in Table 3. In this case, the leak pressure is the objective variable. The difference in strain, the shear adhesion strength, the difference in coefficient of linear expansion, and the elastic modulus of the resin coating are the explanatory variables, respectively. By multiple regression analysis, Equation (B) can be obtained. By using Equation (A) or Equation (B), even when the material of the resin mold member 3 is changed, the leak pressure can be obtained without performing a leak test.

Explanation of symbols

[0080] 1 Wire assembly 2 Wire 2A Core wire 2B Core wire 20 Conductor 21 Insulation layer 23 Resin coating 3 Resin mold member 4 Terminal member 7 Water tank L0 Length L1 Length

Claims

1. An electric wire having a conductor and a resin coating, a terminal member connected to the conductor at an end of the electric wire, and a resin molding member covering a region from the terminal member to the resin coating, wherein a value of Y1 obtained by the following formula (A) is 30 or more, an electric wire assembly. Y1 = 1.26×X1 - 5.02×10 ３ ×X2 + 1.55×10 ３ ×X4 - 2.36×10 －１ ×X5 + 93… Equation (A) Here, X1 is the adhesion work between the resin molded member and the resin coating, and the unit is mJ / m ２ , X2 is a difference between a strain of the resin molding member and a strain of the resin coating, unitless, X4 is a difference between a linear expansion coefficient of the resin molding member and a linear expansion coefficient of the resin coating, unit 1 / °C, X5 is an elastic modulus of the resin coating, unit MPa.

2. An electric wire having a conductor and a resin coating, a terminal member connected to the conductor at an end of the electric wire, and a resin molding member covering a region from the terminal member to the resin coating, wherein a value of Y2 obtained by the following formula (B) is 30 or more, an electric wire assembly. Y2 = -3.59×10 ３ ×X2 + 4.99×10×X3 - 1.20×10 ５ ×X4 - 2.65×10 －１ ×X5 + 139… Equation (B) Here, X2 is a difference between a strain of the resin molding member and a strain of the resin coating, unitless, X3 is a shear adhesion strength between the resin molding member and the resin coating, unit MPa, X4 is a difference between a linear expansion coefficient of the resin molding member and a linear expansion coefficient of the resin coating, unit 1 / °C, X5 is an elastic modulus of the resin coating, unit MPa.

3. The resin molding member covers the entire terminal member. The electric wire assembly according to claim 1 or claim 2.

4. The main component of the resin molding member is a polyamide resin, a polyphenylene sulfide resin, or a polybutylene terephthalate resin. The electric wire assembly according to any one of claims 1 to 3.

5. The main component of the resin coating is a polyester or a polyurethane. The electric wire assembly according to any one of claims 1 to 4.

6. The terminal member is a sensor. The electric wire assembly according to any one of claims 1 to 5.

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