CN2044765U

CN2044765U - Indirectly heated micro gas-sensitive element

Info

Publication number: CN2044765U
Application number: CN 88216621
Authority: CN
Inventors: 韩文述
Original assignee: FUSHUN OXYGEN FACTORY
Current assignee: FUSHUN OXYGEN FACTORY
Priority date: 1988-07-07
Filing date: 1988-07-07
Publication date: 1989-09-20

Abstract

The utility model relates to an indirectly heated micro gas-sensitive element. The indirectly heated micro gas-sensitive element is composed by connecting a gas-sensitive member and a tube base. The gas-sensitive member of the indirectly heated micro gas-sensitive element is composed of a heating pole, an insulating layer, a gas-sensitive layer, and a working electrode. The volume of the gas-sensitive element which adopts the indirectly heated micro gas-sensitive element is small. The utility model has the advantages of high speed, low cost, and high rate of finished products. The large-sized gas-sensitive elements can be replaced by the indirectly heated micro gas-sensitive element. The rate of finished products is as high as 95%. The indirectly heated micro gas-sensitive element is applied to the analytical apparatus as a quantitative analysis element, and the impurity concentration of the ppb level can be detected. The indirectly heated micro gas-sensitive element is a key element of developing gas-sensitive chromatogram, developing low concentration detecting, leaking detection, alarming, and monitoring, and developing various flavours identified by a computer.

Description

Indirectly heated micro gas-sensitive element

The transducer that the utility model relates to equipment such as a kind of detection that is used for imflammable gas, leak detection, monitoring is with miniature heater-type gas sensor.

Gas sensor has been widely used in the various aspects of national defence, traffic, telecommunication and people's lives.Particularly the N type semiconductor gas sensor is used for leakage, detection and the warning of imflammable gas very early.This element, commercialization at home and abroad at present.But, because its volume is big, response speed is slow, power consumption is high, has just limited its scope of application.Discern various smells as exploitation with computer, the exploitation gas-sensitive chromatogram detects and low concentration detects.Aspects such as warning, monitoring, large-scale element is helpless, in recent years, miniature directly heated gas sensing element occurred and has been used for above-mentioned each side.But the technical characteristic of miniature directly heated gas sensing element is dispersed big, can not produce standardized element, and rate of finished products is low, has only a few percent, so the cost height, and price is than high ten times of large-scale elements.

The purpose of this utility model is to overcome the deficiency of above-mentioned various gas sensors, and a kind of computer that can be used for is provided, the miniature heater-type gas sensor of aspects such as gas-sensitive chromatogram detection and low concentration detection, warning, monitoring.

Fig. 1 is the structural representation of miniature heater-type gas sensor;

Fig. 2 is the structural representation of the gas-sensitive element among Fig. 1.

Among the figure, 1 is base, and 2 is gas-sensitive element, and 3 is thermoae for adding, and 4 is insulating barrier, and 5 is gas sensing layer, and 6 is work electrode.

The utility model is achieved in that miniature heater-type gas sensor is formed by connecting by gas-sensitive element 2 and base 1, it is helix that gas-sensitive element 2 adopts the middle part, the lead-out wire of two ends is adding of straight line thermoae 3, outside adding thermoae 3 spiral part, be surrounded by insulating barrier 4, scribble gas sensing layer 5 outside the insulating barrier 4, two ends of gas sensing layer 5 are provided with working electrode 6.

Wherein, it is straight line that the high temperature nickel chromium triangle filament winding that adds thermoae 3 usefulness φ 0.04-φ 0.06mm is made two ends, and the middle part is the structure of helix, and the spiral part external diameter is 0.2-0.4mm, and pitch is 0.07mm, and the number of turns is the 30-100 circle.

The glass dust that insulating barrier 4 usefulness add micro-sodium carbonate is coated with to be pressed in and adds on thermoae 3 the spiral part, has been coated with the outside 0.4-0.7mm of being of back insulating barrier.

Work electrode 6 usefulness are made a circle and external diameters such as insulating barrier with adding the identical high temperature nickel chromium triangle filament winding of thermoae 3 diameters, and two statures are two work electrodes 6 of long 10-15mm respectively, be enclosed within outside the insulating barrier 4, and the spacing that makes two work electrodes 6 are between 0.5-4.5mm.

Gas sensing layer 5 can coat with different gas sensitives to detect different gas.As be coated with tin dioxide gas-sensitive material, in order to detect hydrogen, methane gas, CO (carbon monoxide converter) gas, gasoline, alcohol, gas, flavor that the smog equal-volume is lighter; Be coated with the ferric oxide gas sensitive and can detect the great gas of liquefied gas geometric ratio.Gas sensitive is applied to outside the insulating barrier 4, and its thickness is 0.2-0.4mm, and when being coated with gas sensing layer 5, two ends will be reserved the sub-fraction insulating barrier.

At last, the method that adopts crotch to clamp lead-in wire or spot welding the gas-sensitive element of making 2 is loaded on the base 1.

Operation principle of the present utility model is basic identical with the operation principle of large-scale gas sensor and miniature directly heated gas sensing element, gas sensor is a kind of " gas-" conversion element, is formed by the metal oxide semiconductor material sintering with gas sensitive effect of non-chemical proportion.As CaO, WO ₃, VO ₂, SnO ₂Deng, this quasi-metal oxides all has gas-sensitive activity at 250 ℃-450 ℃, and when contacting with imflammable gas, because the oxygen on gas and the metal oxide surface interacts, the reaction that produces MO-X changes conductivity, and its resistance value will be from large to small.When removing the contact of imflammable gas, its MO-X returns to the state of original MO again, and promptly resistance value restores to the original state, and is the change transitions of this resistance value the signal of telecommunication, have only the volume of transducer do very little, just can carry out detection by quantitative to imflammable gas.

Embodiment of the present utility model is as follows:

The high temperature nickel chromium triangle filament winding system that adds thermoae 3 usefulness φ 0.05mm forms, and helix part external diameter is 0.22mm, and pitch is 0.07mm, and the number of turns is 30 circles, and two ends leave the long lead-in wire of 5mm.Be coated with the glass dust that insulating barrier 4 usefulness participate in 2/1000ths sodium carbonate and make insulating material, add porphyrize behind an amount of distilled water, the glass paste that is ground into sticking silk fabric shape is coated in adds on the thermoae spiral part, be coated with insulating barrier 4 afterwards external diameters be 0.5mm.Make two work electrodes 6 of a circle φ 0.5mm, long 10mm with the high temperature nickel chromium triangle filament winding of φ 0.05mm, be enclosed within on the insulating barrier 4, making two work electrode 6 spacings is 0.5mm.Be coated with gas sensing layer 5 with tin ash, its thickness is 0.2mm, at last the gas-sensitive element of making 2 is connected (or spot welding connection) with the method that base 1 adopts crotch to clamp lead-in wire.

The utility model volume is little, fast response time, applied range can replace large-scale air-sensitive original paper, and production cost is low, yield rate is up to 95%, economic benefit height, the utility model can be used for doing on the analytical instrument quantitative analysis element, can detect the concentration of PPb level impurity, be the exploitation gas-sensitive chromatogram, the key element of various smells is identified in the detection of exploitation low concentration, leak detection, warning, monitoring and exploitation with computer.

Claims

A kind of miniature heater-type gas sensor is formed by connecting by gas-sensitive element 2 and base 1, it is characterized in that:

A. to adopt the middle part be helix for gas sensor 2, and the lead-out wire at two ends is that adding of straight line is thermoae 3, is surrounded by insulating barrier 4 outside adding thermoae 3 spiral part, and insulating barrier 4 scribbles gas sensing layer 5 outward, and the two ends of gas sensing layer 5 are provided with work electrode 6;

B. the high temperature nickel filament that adds thermoae 3 usefulness φ 0.04-0.06mm is made, and its spiral part external diameter is 0.2-0.4mm, and pitch is 0.07mm, and the number of turns is the 30-100 circle;

C. insulating barrier 4 adopts the glass dust that adds micro-sodium carbonate to be coated in to add on thermoae 3 the spiral part, and being coated with afterwards, insulating barrier 4 external diameters are 0.4-0.7mm;

D. materials such as gas sensing layer 5 usefulness tin ash, ferric oxide are applied to outside the insulating barrier 4, and its thickness is 0.2-0.4mm;

E. work electrode 6 usefulness with add the identical high temperature nickel chromium triangle filament winding of thermoae 3 diameters make a circle and two statures of insulating barrier 4 external diameters such as grade respectively two work electrodes 6 of long 10-15mm be enclosed within outside the insulating barrier 4, and the spacing that makes two work electrodes 6 is between 0.5-4.5mm.