JPH039602B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a high temperature temperature sensor, and aims to improve the following points.

(1) By connecting and fixing an electrode body with an arcuate groove similar to the outer diameter of the pipe-shaped electrode to the pipe-shaped electrode, the thermistor element is protected from the radiant heat caused by plasma oscillation during welding and the heat generated by welding. .

(2) Prevent the large current that momentarily flows through the thermistor element during plasma welding.

(3) Prevent the molten material of the pipe-shaped electrode and heat-resistant metal wire from flowing and touching the thermistor element body due to welding.

A conventional example will be explained with reference to FIGS. 1 and 2. Two heat-resistant metal wires 5, which are housed together with insulating powder 4 inside a heat-resistant sheath tube 3, are inserted into the pipe-like electrode 2 embedded in the thermistor body 1 for signal extraction. After inserting the heat-resistant metal wire 5 until it penetrates, a torch 7 for plasma welding is fixed immediately near the tip 6 of the heat-resistant metal wire 5 to serve as a negative electrode, and the other end 8 of the heat-resistant metal wire 5 is used as a positive electrode for welding. By causing plasma oscillation in a reducing atmosphere, the tips of the heat-resistant metal wire 5 and the pipe-shaped electrode 2 were melted, and the heat-resistant metal wire 5 and the pipe-shaped electrode 2 were electrically and mechanically connected.

However, in the case of the above configuration, a momentary large current passes through the thermistor element during plasma welding, and heat due to radiation and melting reaches the thermistor element, raising concerns that microcracks may occur in the thermistor element. The occurrence of microcracks causes the thermistor element to break down due to changes in resistance and vibrations and shocks, resulting in a significant loss of function as a thermistor element.

The present invention has been made to eliminate the above-mentioned conventional problems, and an embodiment thereof will be described below with reference to FIGS. 3 and 4, in which the same parts as above are given the same numbers.

First, a heat-resistant sheath tube 3 is attached to a pipe-shaped electrode 2 embedded in a thermistor body 1 for signal extraction.
After inserting two heat-resistant metal wires 5 housed together with insulating powder 4 into the inside of the pipe-shaped electrode 2 until their tips penetrate through the inside of the pipe-shaped electrode 2, a plasma welding wire is inserted immediately near the tip 6 of the heat-resistant metal wire 5. The torch 7 is fixed as a negative pole, and an electrode extraction body 9 having an arcuate groove having the same shape as the outer diameter of the pipe-shaped electrode is connected and fixed to the pipe-shaped electrode 2 to serve as a positive electrode for welding. By oscillating plasma in an atmosphere, the heat-resistant metal wire 5 and the tip of the pipe-shaped electrode 2 are melted and electrically and mechanically connected.

The following effects can be obtained by the above-described manufacturing method of the present invention.

(1) By sandwiching and connecting and fixing the electrode take-out body with the circular arc groove that is the same as the outer diameter of the pipe-like electrode, heat dissipation and heat insulation effects are generated, and the radiant heat generated by plasma oscillation and welding The thermistor element can be protected from the generated heat.

(2) Since the large current that momentarily flows during plasma welding does not pass through the thermistor element, there is no adverse effect from Joule heat.

(3) Due to welding, the molten material of the pipe-shaped electrode and the heat-resistant metal wire is blocked by the electrode extraction body, so there is no fear that it will flow and reach the thermistor body and cause adverse thermal effects.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a thermistor element to explain a conventional example, Fig. 2 is a side sectional view of the conventional example during plasma welding, and Fig. 3 is a side sectional view during plasma welding to explain the manufacturing method of the present invention. , FIG. 4 is a front view of the same. 1... Thermistor element body, 2... Pipe-shaped electrode,
5...Heat-resistant metal wire, 6...Tip part, 9...Electrode extraction body.

Claims (1)

[Claims] 1 A thermistor element having a structure in which a pipe-shaped electrode is embedded in the thermistor element body is used, and one end of a heat-resistant metal wire is inserted into the pipe-shaped electrode until it penetrates the pipe-shaped electrode, and one end of the heat-resistant metal wire is inserted into the end of the pipe-shaped electrode for signal extraction. Plasma welding is performed by connecting and fixing the tip of the metal wire to the pipe-shaped electrode protruding from the thermistor body by sandwiching and fixing the electrode take-out body having a circular arc groove having the same outer diameter shape as the pipe-shaped electrode. A method for manufacturing a high temperature temperature sensor characterized by being connected to a high temperature sensor.