JPS61134638A - High temperature sensor - Google Patents

Abstract

PURPOSE:To prevent the break of a temperature sensor element and to prevent bad influences due to softening of a glass by packing a crystallizable glass powder between the temperature sensor element and a metallic pipe and fusing and crystallizing the glass powder. CONSTITUTION:Platinum electrodes 3 are connected to both end parts of a thermistor element 1, and one electrode 3 is joined to the inside of the closed end of a metallic pipe 2. The other electrode 3 is joined to an electrode wire 4. Electric insulating materials 5 consisting of a crystallizable glass are packed in this pipe 2 and are crystallized by heat treatment. By this constitution, internal constituting parts of the element 1, electrodes 3, and the electrode wire 4 are fixed rigidly by insulating materials to improve the quakeproof property. Since the crystallizable glass is not flowed viscously unless its temperature exceeds the melting point of the deposited crystal, bad influences due to viscous flow for temperature are not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high temperature sensor used under high temperature and vibration conditions such as automobile exhaust gas.

[Conventional technology]

Conventional thermistor-type exhaust temperature sensors, for example, have a thermistor element housed inside a metal pipe with one end closed, electrically insulating powder such as magnesia filled between the element and the metal pipe, and the thermistor element In order to improve vibration resistance, the outside diameter of the gold mud pipe is reduced to increase the packing density of the insulating powder around the thermistor spool.

[Problem that the invention seeks to solve]

In the conventional structure described above, since the outer diameter of the metal pipe is drawn, there are problems such as damage to the thermistor element or deformation of the electrode wire connected to the element.

[Means for solving problems]

In the present invention, glass powder that crystallizes is filled between a temperature sensor element such as a thermistor element and a metal pipe, and the glass powder is melted and
It has a crystallized structure.

C Effect] In the present invention, at the stage of melting the glass powder to be crystallized, the glass powders are welded together and crystallized. Therefore, the entire crystallized glass between the temperature sensor element and the metal pipe has a strong structure due to the bonds between the glass particles, and can prevent the temperature sensor element from moving within the metal pipe under vibration.

In addition, since crystallized glass does not exhibit viscous flow unless the temperature exceeds its heat treatment temperature, that is, the melting point of the precipitated crystals, it does not exhibit viscous flow with respect to temperature like when ordinary amorphous glass is used. There are no negative effects, such as a decrease in insulation resistance or a decrease in density.

〔Effect of the invention〕

As described above, according to the present invention, the temperature sensor element can be held inside the pipe without being moved without reducing the outer diameter of the metal pipe as in the past. This can eliminate problems such as

In addition, since the crystallized glass does not soften during practical use, there is an effect that no adverse effects are caused by the softening of the glass.

〔Example〕

In FIG. 1, 1 is a thermistor element, and 2 is a heat-resistant alloy pipe, one end of which is closed. Thermistor element 1
Platinum electrodes 3 are connected to both ends of the metal pipe 2, and one of the electrodes 3 is bonded to the inside of the closed end of the metal pipe 2. Electrode 3
The other end is connected to the electrode wire 4. 5 is an electrical insulating material made of crystallized glass. This involves filling a metal pipe 2 with a glass powder that crystallizes, or a mixture of the powder and an electrically insulating powder such as alumina, silica, or magnesia, and then performing appropriate heat treatment to sufficiently melt the glass that crystallizes. and is crystallized. The crystallizing glass used for the insulating material 5 was selected to have a heat resistance of 1000° C. or higher, that is, a melting temperature of precipitated crystals of 1000° C. or higher, considering the usage environment of the automobile exhaust gas temperature sensor. This crystallized glass is, for example, MgO-BaO-B2O3SiO
It is a 2-type glass, and can be sufficiently crystallized by heating it to 850°C with an appropriate temperature increase and holding it at 850°C for 10 minutes or more.

According to this embodiment, the insulating material 5
Internal components consisting of the one-star element 1, electrode 3, and electrode wire 4 are rigidly fixed, and vibration resistance can be improved. Here, to give a concrete example of the effect, we will compare the exhaust temperature sensor with the structure shown in Fig. 1 and the comparison sensor (the overall structure is the same as Fig. 1), which is filled with MgO powder by tapping instead of the insulating material 5. When vibrations of about 200 Hz x 30 G were applied to both sensors, the comparative sensor developed problems such as electrode breakage and joint peeling after about 5 to 7 hours. However, the sensor of this embodiment shown in FIG. 1 did not have any problems even after 20 hours had elapsed. Regarding vibration resistance, it is also possible to use ordinary amorphous glass instead of crystallized glass in order to obtain the same effect as in this example, but ordinary glass is not suitable for high temperatures (800°C to 1000°C). It is difficult to ensure insulation resistance in

For example, if we compare borosilicate glass, which has a working temperature of 900°C, and the crystallized glass of this example,
At 000°C, the insulation resistance of crystallized glass is one to two orders of magnitude higher.

FIG. 2 shows a sheath type thermocouple temperature sensor showing another embodiment, in which instead of a thermistor or the like as an internal component, a thermocouple element wire 6 is inserted into a metal pipe 2, and an insulator made of crystallized glass is inserted into the metal pipe 2. Fix with material 5.

FIG. 3 shows yet another embodiment, which is a temperature fuse.

A lead wire 8 is welded to the fuse wire 7, and an insulator tube 10, an insulator tube 11, and an insulator disk 12 are arranged so that a space 9 is created around the fuse wire 7. Note that the space 9 may be filled with flux or glass that has fluidity below the melting temperature of the fuse 7.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the invention, and FIGS. 2 and 3 are sectional views showing other embodiments of the invention. ■...Thermistor element, 2...Metal pipe, 5...
・Electrical insulation material.

Claims (1)

[Claims] A temperature sensor element is housed inside a metal pipe with one end closed, and between the sensor element and the metal pipe, a crystallizing glass powder or a mixture of the crystallizing glass powder and alumina, silica, magnesia, etc. A high-temperature sensor made by filling a mixture with insulating powder, melting it, and crystallizing it.