JPS6273017A - Method of manufacturing heating element of sheath glow plug - Google Patents

Abstract

PURPOSE:To reduce a cost of plug by a method wherein winding directions of two electrical resistor wires made of different materials are made same and one end of one of the electrical resistor wires is bent back in an opposing direction within the same cylindrical surface and one end part is abutted against an end part of the other electrical resistor wire and welded to each other. CONSTITUTION:Two electrical resistor wires 1 and 2 made of different material are wound in the same direction to form a coil having the same diameter to each other. Then, one end part 11 of one of the electrical resistor wires 1 is bent back in an opposing direction within the same cylindrical surface to form an inverted winding within the same cylindrical surface to form an inverted winding part 1A. Further, one end 11 of the resistor wire 1 and one end 21 of the electrical resistor wire 2 are abutted to each other to form an abutment 4 to each other and then the abutment 4 is welded. With the foregoing process, it is possible to reduce a manufacturing cost of the two electrical resistor wires without reducing a connection strength of the two electrical resistor wires.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sheathed glow plug used to assist in starting an engine, and more particularly to a method for manufacturing a heating element in which two types of electrical resistance wires are connected in series.

[Prior Art] Conventionally, a sheathed glow plug uses a heating element in which an electrical resistance wire having a large positive temperature coefficient of resistance and an electrical resistance wire having a small positive temperature coefficient of resistance are connected in series. At the initial stage of energization, the temperature is raised rapidly by the action of the electrical resistance wire with a large positive temperature coefficient of resistance, and after the stomach has warmed up, the action of the electrical resistance wire with a small positive resistance temperature coefficient prevents fusing due to excessive temperature rise. It was set up like this.

Conventionally, this type of heating element is made by welding the ends of two coils wound in opposite directions, so that the glue melted during welding is absorbed between one coil and the other. For example, as shown in FIG. 6, an electric resistance wire 1 (large resistance wire) having a large positive temperature coefficient of resistance formed in a coil shape is used. ,
The tip portions 1a and 2a of each electrical resistance wire 2 (referred to as a small resistance wire) are brought into contact with an electric resistance wire 2 (referred to as a small resistance wire) formed in a coil shape in the opposite direction to the high resistance wire 1, and the corresponding contact is made. It was formed by welding the portion 4a.

[Problems to be Solved by the Invention] However, in the conventional manufacturing method, the high resistance wire and the low resistance wire were wound in opposite directions. This method requires additional equipment and has the problem of increasing the manufacturing cost of the high-resistance wire and the low-resistance wire.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a seed plug that can keep the manufacturing cost of two electrical resistance wires low without deteriorating the bonding strength of the two electrical resistance wires. The present invention provides a method for manufacturing a heating element.

[Means for solving the problems] In order to achieve the above object, the present invention provides two
A book of electrical resistance wires is wound in the same direction to form a coil shape with the same diameter, and one end of one of the two electrical resistance wires is bent back in the opposite direction within the same cylindrical surface, The one end and the other end of the electrical resistance wire are brought together and welded.

[Operation and Effects of the Invention] Since the winding direction of two electrical resistance wires made of different materials is the same, the two electrical resistance wires can be formed into a coil shape using the same winding device, and the electrical resistance wires can be formed into a coil shape. The manufacturing cost can be kept low.

[Example] Next, a method for manufacturing a heating element for a sheathed glow plug according to the present invention will be described based on an example shown in FIG.

Electric resistance wire 1 with a large positive resistance temperature coefficient made of pure iron, pure nickel, nickel alloy, etc. (hereinafter referred to as high resistance wire)
is formed into a coil shape as shown in FIG. Armel,
As shown in Fig. 1, an electrical resistance wire 2 (hereinafter referred to as "low resistance wire") made of Chromel, Pyromax (trade name), etc. and having a small positive temperature coefficient of resistance is wound in the same direction as the high resistance wire 1. Form into a coil with the same diameter. One end of the high resistance wire 1 or the low resistance wire 2 formed in a coil shape (in this embodiment, one end 11 of the high resistance wire 1) is wound in the opposite direction to form a reverse winding portion 1A. Groove 31 of jig 3 provided to loosely fit large resistance wire 1 and small resistance wire 2 on the same line
The small resistance wire 2 is placed on the one end 11 side of the large resistance wire 1 inside. The contact portion 4 is formed so that one end 11 (reversely wound portion 1A side) of the large resistance wire 1 and one end 21 of the small resistance wire 2 are in contact with each other within the groove 31. ).

Next, a cover 5 in which a hole 51 is formed so that only the contact portion 4 is exposed is placed from above the jig 3 ((b) in FIG.
)reference).

The contact portion 4 is welded from the outside of the cover 5 through the hole 51 by a welding method such as arc welding, gas welding, electron beam welding, or laser beam welding (see (C) in FIG. 1).

Through the above steps, as shown in FIG. 1(d), the wire rod 61 melted by welding flows between the one end 11 of the high resistance wire 1 and the one end 21 of the low resistance wire 2 during welding, and after welding, the wire rod 61 melts. The wire rod 61 hardens to form a welded portion 6, and the high resistance wire 1 and the small resistance wire 2 are firmly connected via the welded portion 6 to form the heating element A.

Although this embodiment shows an example in which two electrical resistance wires are joined, a heating element may also be constructed by joining a plurality of electrical resistance wires in series using the above manufacturing method.

The heating element A manufactured in this manner becomes a sheathed glow plug B through the steps shown in FIGS. 2 to 5.

As shown in FIG. 2, the other end 12 of the high resistance wire 1 is welded to one end 71a of the center shaft 71, which is the center electrode, and the other end 22 of the low resistance wire 2 is welded to a circular metal piece 72. form.

As shown in FIG. 3, this welded body 7 has a small hole 8 at its tip 81.
1a, and is inserted into the stainless steel heat generating tube 8 having an open rear end 82. In the welded body 7 inserted into the heat generating tube 8, the metal piece 72 and the small hole 81a are fitted and welded, the heat generating tube 8 is filled with the heat generating element A and the insulating powder 84, and the welded body 7 is inserted between the opening 82a and the center shaft 71. A rubber cap 83 is fitted.

Next, as shown in FIG. 4, the heat generating tube 8 is pressurized from the outer periphery to reduce its outer diameter, and swaging processing is performed to increase the dimensions, and a glass seal 85 is applied to the opening 82a.

Further, as shown in FIG. 5, the upper part 86 of the heat generating tube 8 is fitted into the through hole 92 of the metal shell 91, and the terminal nut 93 is screwed onto the other end 71b of the center shaft 71, thereby manufacturing the sheath glow plug B.

[Brief explanation of drawings]

Figure 1 (a)') and d) are manufacturing process diagrams of the heating element of a sheathed glow plug, Figures 2 to 5 are manufacturing process diagrams of a sheathed glow plug, and Figure 6 is a diagram of the manufacturing process of a conventional heating element. FIG. In the diagram 1... High resistance wire (electrical resistance wire) IA...
・Reverse winding part 2...Low resistance wire (electrical resistance wire) A...
Heating element B...seeded glow plug

Claims (1)

[Claims] 1) Two electrical resistance wires made of different materials are wound in the same direction to form a coil shape with the same diameter, and one end of one of the electrical resistance wires is wound in the opposite direction within the same cylindrical surface. A method for manufacturing a heating element for a sheathed glow plug, which comprises: bending back, and butting and welding one end of the electrical resistance wire against the other end of the electrical resistance wire.