JPS6251177A - Wire connection for terminal member - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for connecting an electric wire to a terminal member, which is used to electrically and mechanically connect an electric wire to a terminal member in an electric heater or the like.

<Background of the Invention> For example, the terminal portion of an electric heater is formed by connecting a terminal bar and an electric wire using a metal connection plate, and then molding the entire periphery of the electric wire connection portion with rubber. In this case, the terminal rod and the connecting plate are made of a material such as stainless steel in consideration of heat resistance and corrosion resistance, and therefore the two materials, which are made of the same type of metal, are heat welded using a method such as spot welding. On the other hand, the connecting plate and the conductor part (copper wire) of the electric wire are crimped together using a method such as caulking to electrically connect these three parts.

However, when the connecting plate is wrapped around the circumferential surface of the conductor portion of the electric wire and crimped, the connecting plate tends to return due to an elastic reaction force called "spring bank" and the crimped portion tends to loosen. As a result, a gap is created between the connection plate and the conductive wire portion, resulting in an increase in contact resistance, an increase in the generation of Joule heat during energization, and a buildup of heat of approximately 150° C. within the rubber mold. As a result, chlorine-based and sulfur-based gases are generated and corrode the conductor parts of the electric wires, which further increases the contact resistance mentioned above, further promoting self-heating, and eventually ignites at the wire connection parts. There are other problems.

<Object of the invention> This invention is intended to solve the above problems,
It is an object of the present invention to provide a novel method for connecting electric wires to terminal members that can suppress self-heating by reducing the contact resistance of the electric wire connecting portion.

<Structure and Effects of the Invention> In order to achieve the above object, in this invention, one end of the metallic connecting plate is welded to the terminal member, the other end is held on the circumferential surface of the covering part of the electric wire, and the intermediate part of the connecting plate is welded to the terminal member. After wrapping around the conductor at the end of the wire, the winding part was heated under pressure to anneal the connection plate, and the connection plate and the conductor of the wire were electrically connected. .

According to this invention, since the internal stress and elastic reaction force of the connecting plate are removed by annealing, "springback" does not occur, and therefore there is almost no gap between the connecting plate and the wire. This reduces contact resistance and suppresses the increase in Joule heat generated when electricity is applied.As a result, the rubber mold does not decompose due to heat accumulation and gas is generated, and this prevents the conductor part of the wire from being generated. The present invention achieves remarkable effects such as preventing corrosion of the wires, preventing further increase in contact resistance, and completely preventing ignition of wire connections due to self-heating.

<Description of Examples> Figures 1 to 4 specifically show the wire connection method of this invention, and Figures 5 and 6 show an electric heater completed by implementing this invention. show.

The electric heater shown in FIG. 5 is formed by connecting electric wires 2, 2 to both ends of a heater body 1, and applying a rubber mold layer 4.4 to each electric wire connection portion 3.3.

As shown in FIG. 6, the heater main body 1 is constructed by inserting a heating wire 6 into a metal protective tube 5, filling the surrounding area with insulating powder 7, and sealing the openings at both ends with end plates 8. It has a similar structure. Both ends of the heating wire 6 are spot-welded to one end of a terminal bar 9, respectively, and the other end of each terminal bar 9 is made to protrude outward from the end plate 8. This terminal bar 9 has a threaded groove formed on its circumferential surface, and the wire connecting portion 3 is formed at the distal end portion of the terminal bar 9 that protrudes outside the tube, and is connected to the electric wire 2 through a metal connecting plate 10 .

The terminal bar 9 and the connection plate 10 are made of a material such as stainless steel or iron in consideration of heat resistance and corrosion resistance, and a material such as stainless steel or iron is formed on the wire connection portion 3 in consideration of insulation properties. , a rubber mold layer 4 is formed on the entire circumferential surface.

To connect the electric wire 2 and the terminal bar 9 using the connection plate 10, as shown in FIG. Conductor part 1 consisting of
3 is exposed, and a connecting plate 10 having a structure as illustrated in FIG. 1 is prepared in advance. The illustrated connection vilO is bent into a U-shape according to the diameter of the electric wire 2, and has a fixing piece 14 on the end side, a connecting piece 15 on the inside, and a circular plate-like piece 16 on the opposite end. It is something.

As shown in FIGS. 2 to 4, the plate-like piece 16 is applied to the circumferential surface of the end of the terminal bar 9, and the two are welded together by spot welding, while the fixed piece 14 is attached to the rubber-coated portion 12 of the electric wire 2. The wrapping around the circumferential surface is fixed.

In this case, since the terminal bar 9 and the plate-shaped piece 16 are welded together by forming a thread groove on the circumferential surface of the terminal bar 9, the contact resistance between them becomes large and the amount of heat generated increases. 9
Because the threads of the weld are easy to melt, the effect of spot welding is greater than that of an end bar with a flat circumferential surface.

Further, the central connecting piece 15 is wrapped around the circumferential surface of the conducting wire portion 13 of the electric wire 2, and after being crimped and crimped, the electrodes 17 and 18 of the spot welding machine (in FIG. 4) are attached to the upper and lower surfaces of the connecting piece 15. (indicated by the chain line), set it in a pinched state, and then press the electrode 1.
7. Heat with electricity for 18 minutes. In this embodiment, the pressing force in this spot crimping is set to about 20 to 30 kg/cJ, and the heating temperature is set to 200 to 1050°C when the terminal bar 9 and the connecting plate 10 are made of stainless steel. is annealed under pressure to remove internal stress and elastic reaction force of the connecting plate 10. Note that the connection plate 10 and the conductor portion 13 are made of different metals (stainless steel and copper).
Therefore, the two will not be welded together by spot welding.

Thus, due to the annealing action described above, the connection piece 15 of the connection plate 10 is maintained in a crimped state, and loosening of the connection piece 15 due to the "spring bank" is prevented, thereby reducing the gap between the connection plate 10 and the conductor portion 13 of the electric wire 2. The contact resistance can be set small by reducing the contact resistance.

Therefore, even when the electric heater is energized, since the contact resistance is small, an increase in Joule heat generated at the wire connection section 3 is prevented, and gas generation and corrosion at the conductor section 13 etc. are completely prevented. be.

14 electric heaters formed by carrying out this invention,
97 electric heaters formed using conventional methods,
Prepare 3 samples of the former (A,
-A3) and the latter three samples (Bl to B3), and after connecting them in series to an alternating current constant current generator 20 as shown in FIG. The surface temperature of the rubber mold layer and the resistance of the terminal portion were measured when electricity was applied for a certain period of time.

Figures 8 and 9 show each sample A, when the current value was variably set from IA to 12A at an ambient temperature of 30°C
The surface temperature of the rubber mold layer and the resistance value of the terminal portion in ~A3 and 81~B3 are plotted, respectively. According to FIG. 8, when the current value is IOA, sample B+ by the conventional method is 104.3°C, and B2 is 106°C.
．． 3°C, B, rose to 67.3°C, whereas sample A1 according to the present invention rose to 35.4°C, B rose to 38.5°C,
B3 was 35.2°C. The internal temperature of the rubber mold layer is approximately 20°C higher than its surface temperature, and if the ambient temperature
When the temperature reaches about 0'C, the internal temperature reaches nearly 150C in the conventional product, but in the case of the sample according to the present invention, the temperature increase hardly poses a problem.

Also, according to FIG. 9, when the current value is 1 OA, the conventional sample B+ has a resistance of 43.9 mΩ, and that of B2 has a resistance of 45.5 mΩ.
mΩ, B3 is 29 mΩ, whereas sample A according to the present invention is 8.5 mΩ, A2 is 8.7 mΩ, A,
is 8.6 mΩ. Among the resistances of the terminal portion, the resistance of the electric wire and the terminal bar is approximately 7.8 mΩ, so the resistance of the crimped portion according to the present invention is 1 mΩ or less. Note that in conventional products, the reason why the resistance value decreases as the current value increases is that current flows through the gap at the crimped portion due to the Schottky effect.

[Brief explanation of drawings]

Figure 1 is an exploded perspective view showing the connection structure between the terminal bar and the electric wire.
Fig. 2 is a front view of the electric wire connection section, Fig. 3 is a plan view thereof, Fig. 4 is a sectional view taken along line A-A in Fig. 2, and Fig. 5 is a front view with the central part of the electric heater omitted. Fig. 6 is a partially cutaway cross-sectional view of the electric wire connection part of the electric heater, Fig. 7 is a diagram showing an experimental method for confirming the effects of the present invention, and Figs. 8 and 9 show the data of the experimental results. FIG. 2...Electric wire 3...Electric wire connection part 9...
・Terminal bar 10... Connection plate 13... Conductor portion Patent applicant: Daikin Industries, Ltd. Patent applicant: Shinko Electric Manufacturing Co., Ltd., agent Patent attorney: Yu Suzuki Mitsunia F 6-1 @Tsuru Heater 9 new face required'f;
Ougi Tomo, Experimental Karasukuri T-Yu and Tsume T)ffiW5几(A
)

Claims (4)

[Claims] (1) A method for connecting an electric wire to a terminal member via a metal connection plate, in which one end of the connection plate is welded to the terminal member, the other end is held on the circumferential surface of the covered portion of the electric wire, and After wrapping the middle part of the connection plate around the conductor part at the end of the wire, the wrapped part is heated under pressure to anneal the connection plate and electrically connect the connection plate and the conductor part of the wire. A method for connecting electric wires to a terminal member, characterized in that: (2) The method for connecting electric wires to a terminal member according to claim 1, wherein the terminal member is a terminal bar in an electric heater. (3) The method for connecting electric wires to a terminal member according to claim 1 or 2, wherein the terminal member and the connection plate are made of stainless steel or iron. (4) The method for connecting an electric wire to a terminal member according to claim 1, wherein the entire peripheral surface of the connecting portion between the terminal member and the electric wire is molded with rubber.