JPS6260770B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field: The present invention relates to an improvement in a wire-wound resistance wire for preventing radio noise used in an ignition circuit of an internal combustion engine. Conventional technology and problems to be solved by the invention: Conventionally, in order to prevent radio noise generated in the ignition circuit of an internal combustion engine, a wire-wound resistance wire has been put into practical use, which reduces noise current by adding an inductance component. There is. This wire-wound resistance wire uses ferrite as a magnetic material to prevent noise, EPDM as a base rubber, and a magnetic mixture made of acrylic rubber, which is coated around a core member made of glass fiber or polyamide fiber. It consists of a resistance wire wound around it and an insulating coating around its outer periphery. In particular, internal combustion engines need to withstand a wide range of environmental conditions from -40°C to 180°C, so heat-resistant silicone rubber-coated electric wires are used for the outer insulating coating layer. However, in the case of this silicone rubber coated electric wire, in order to improve the noise prevention effect, if the outer diameter of the magnetic material mixture is 2.0 mmφ or more, the durability condition (48
After leaving it in an electric furnace for an hour, it is wound around a rod with a diameter of 13 mmφ to check for abnormalities.) If a winding test is performed, cracks or breaks will occur from the inside, and the wire will break if bent forcibly. A problem has occurred. Furthermore, when forming a silicone rubber coating layer directly on a winding core wound with a magnetic material mixture, the adhesion is poor and air bubbles may form in some areas. Corona discharge occurs and the outer insulating layer is destroyed and leaks, which tends to cause problems such as ignition failure. Means for Solving the Problems: The object of the present invention is to provide a wire-wound resistance wire that prevents the generation of bubbles during production without deteriorating the noise prevention effect and has excellent durability. A wire-wound resistor for preventing radio noise, comprising a fiber core member coated with a magnetic mixture so that the outer diameter of the mixture is 2.0 mmφ or more, a resistance wire wound around the outer periphery, and a silicone rubber coating. In electric wires,
Silicone rubber is used as the base rubber of the magnetic substance mixture, and the content of the magnetic substance is 85 to 50% based on the total weight of the silicone rubber and the magnetic substance, and the magnetic substance is mixed with the core member to improve rigidity. This wire-wound resistance wire for preventing radio noise is characterized by interposing a polyamide resin sheath layer with a melting point of 200°C or more and a wall thickness of 0.4mm or more between the wire and the material. Effects and Effects: The present invention changes the rubber material of the magnetic mixture to a silicone rubber type, so that it has good wettability with the silicone rubber coating layer of the outer cover, and the mixture can be applied to the outer periphery of the core member. Alternatively, it is possible to prevent the generation of air bubbles during molding using an extrusion method. In addition, since the blending ratio of the magnetic substance mixture has a limit depending on the base rubber material, the blending ratio of the magnetic substance in the mixture must also be changed, and the blending ratio of the magnetic substance is based on the total weight ratio. 85% or less. If more magnetic material is added, it will become too hard, making extrusion processing difficult and reducing flexibility;
If it is less than that, the noise prevention effect will be poor and regulations will not be satisfied. Furthermore, the present invention uses polyamide fibers instead of glass fibers in order to reduce costs. If a magnetic mixture layer is directly coated or extruded on the outside of the polyamide fibers, (1) the adhesion between the fibers and the magnetic mixture will be poor, and the pull-out strength between the terminal fitting and the electric wire will be reduced; (2) In the finished product, everything from the central core member to the outermost silicone rubber coating is soft, so it has no stiffness as an electric wire, and during actual use, it may sag and come into contact with a part of the engine, causing cracks in the electric wire due to vibration. Sometimes it comes in. As a countermeasure, providing a polyamide sheath layer with a high melting point between the polyamide fibers that form the core member and the magnetic mixture layer will compensate for the irregularities of the inner fibers and improve the adhesion with the magnetic mixture layer on the outside. can solve the above problem. The polyamide (nylon) sheath used here must have a melting point of at least 200℃, a wall thickness of 0.4 mm or more, and be able to be manufactured by extrusion molding so that it will not dissolve under the conditions in which the silicone rubber coated wire is used. Must not be. In addition, by using a hard nylon sheath, the rigidity is increased and the diameter of the polyamide fiber core member can be made thinner, so the inner diameter of the magnetic material mixture can be essentially made smaller, and the thicker wall thickness prevents noise. It can also have an advantageous effect. This will be explained in detail below using examples. Figure 1 shows a wire-wound resistance wire with conventional dimensions and structure, in which a glass fiber core member 1 of 2.7 mmφ is coated with a magnetic mixture 2 consisting of acrylic rubber and 82% by weight ferrite powder, with an outer diameter of 3.5 mm. A wire A having an outer diameter of 7.0 mmφ is made by winding a resistance wire 3 thereon and covering the outer periphery with a silicone rubber coating layer 4.
In addition, as a reference product, as shown in Figure 2, 2.7mmφ
Glass fiber core member 1 with silicone rubber and 82% by weight
A magnetic material mixture 12 mixed with ferrite powder is coated to have an outer diameter of 3.5 mmφ, and a resistance wire 3 and a silicone rubber coating layer 4 are similarly formed to produce an electric wire B having an outer diameter of 7.0 mmφ. On the other hand, the present invention, as shown in Figure 3, consists of a 1.15mm polyamide fiber twisted wire
A core member 11 of φ was made, and the core member was covered with a polyamide sheath 5 made of thermoplastic resin to an outer diameter of 2.2 mmφ, and then similarly molded to a diameter of 3.5 mm using a silicone rubber-based magnetic mixture 12. , coated with resistance wire 3 and silicone rubber coating layer 4, outer diameter 7.0mmφ
Make electric wire C. Next, regarding the durability test, the above electric wire samples A to C and additional samples include sample D, which uses polyamide fiber and nylon sheath (melting point 185°C) in place of the glass fiber of sample A, and nylon sheath of sample C. Sample E whose melting point was 185℃ compared to 205℃
Table 1 shows the results of the above-mentioned durability test using
Shown below.

【table】

[Table] As a result, the durability test shows that the melting point of the nylon sheath for polyamide fiber core material is at least 200℃.
It has been confirmed that (sample C) is required and that the sheath thickness is also required to be 0.4 mm or more. As described above, the wire-wound resistance wire of the present invention exhibits a noise prevention effect by setting the outer diameter of the magnetic material mixture to 2.0 mmφ or more. In addition, by interposing a polyamide resin sheath layer with a melting point of 200°C or more and an inner thickness of 0.4 mm or more between the polyamide fiber core member and the magnetic material mixture, rigidity and adhesion are improved. This increases the pull-out strength at the connection between the metal fitting and the wire, and prevents the wire from weakening, which prevents the wire from coming into contact with the engine and causing cracks in the wire due to vibration.Furthermore, due to the above effects, the diameter of the core member Since the thickness of the magnetic material mixture can be increased by making the magnetic material thinner, the noise prevention effect can also be improved. Furthermore, by setting the content of silicone-based magnetic material mixture and its magnetic material to 85 to 50%, and using a silicone rubber jacket in combination, it has an excellent noise prevention effect and improves the durability of the wire, and is easy to extrude. It has excellent performance and durability as a wire-wound resistance wire, such as good adhesion with silicone rubber and stable performance, and can reduce costs.

[Brief explanation of the drawing]

Figure 1 shows a conventional wire-wound resistance wire.
Figure 1a is a partially cutaway perspective view of the same, Figure 1b is a side view of the same, Figure 2 is a reference wire-wound resistance wire;
Figure a is a partially cutaway perspective view of the same, Figure 2b is a side view of the same, Figure 3 shows the wire-wound resistance wire of the present invention, and Figure 3a is a partially cutaway view of one embodiment. FIG. 3b is a side view of the cutaway perspective view. 11...Polyamide fiber core member, 12...Magnetic material mixture, 5...Polyamide sheath, 4...Silicone rubber coating.

Claims (1)

[Claims] 1 A radio wave made by using a polyamide fiber member as a core member, surrounding it with a magnetic mixture so that the outer diameter of the mixture is 2.0 mm or more, and winding a resistance wire around the outer periphery and covering it with silicone rubber. In the wire-wound resistance wire for noise prevention, silicone rubber is used as the base rubber of the magnetic substance mixture, and the content of the magnetic substance is 85 to 50% with respect to the total weight of the silicone rubber and the magnetic substance, and the core member A wire-wound resistance wire for preventing radio noise, characterized in that a sheath layer of polyamide resin having a melting point of 200° C. or more and a wall thickness of 0.4 mm or more is interposed between the and the magnetic material mixture.