CN101995425A

CN101995425A - Nitrogen oxide sensor chip for automobile

Info

Publication number: CN101995425A
Application number: CN2010105257485A
Authority: CN
Inventors: 谢光远; 黄海琴; 尹亮亮; 王哲; 倪铭
Original assignee: Wuxi Longsheng Technology Co Ltd
Current assignee: Wuxi Longsheng Technology Co Ltd
Priority date: 2010-10-30
Filing date: 2010-10-30
Publication date: 2011-03-30

Abstract

The invention discloses a nitrogen oxide sensor chip for an automobile. The nitrogen oxide sensor chip comprises a substrate which is formed by laminating first to fifth layers of substrates, wherein heating electrodes are arranged on the fifth layer of substrate, arranged in a wavelike shape and covered by an insulating layer; a reference gas passage is formed above the fourth layer of substrate and comprises a thick cavity and a thin cavity which are connected through a small hole; the insulating layer is made of ceramic powder paste which comprises aluminum oxide as a main component; and the thickness of the thin cavity is one fourth to one third the thickness of the thick cavity. The nitrogen oxide sensor chip has the characteristics of simple structure, high thermal efficiency, and capability of realizing effective compression and sealing at the working temperature without generating over-high thermal stress and can be quickly started. A heating element, an introduction and discharge element and a detection element are integrated by laminating once and sintering at a high temperature.

Description

A kind of automobile NOx sensor chip

Technical field

The present invention relates to a kind of automobile NOx sensor chip, relating in particular to a kind of is electrolytical flat NOx sensor chip with the stabillzed with yttrium zirconium dioxide, belongs to vehicle exhaust control system field.

Background technology

Oxides of nitrogen is a kind of main gas pollutant, not only directly human body and animal are damaged, and can form acid rain animals and plants and human entire environment are worked the mischief, therefore the detection to oxides of nitrogen in industrial gaseous waste, vehicle exhaust and the atmosphere is a urgent task.The detection method of oxides of nitrogen has: ion-selective electrode method, chemoluminescence method, biochemical sensor method, semiconductor transducer method, solid electrolyte electric potential type sensor method etc., wherein solid electrolyte electric potential type sensor method is considered to a kind of method of tool future, such sensor and industrialization have been arranged at present, be mainly used in the exhaust emissions disposal system of heavy duty diesel engine.

At present the structure of NOx sensor mostly is slice structure greatly, is formed by stacking by six layers even more yttrium stable zirconium oxide and alumina ceramic plate, and structure and manufacture craft are all very complicated.Also can cause a series of problem thus:

1. what structure and manufacture craft loaded down with trivial details directly caused is the reduction of integrated yield;

2. because the difference of yttrium stable zirconium oxide and aluminium oxide character is given the superimposed difficulty of bringing, what cause then is the poor air-tightness of chip, influences precision of test result;

3. the integral thickness of chip is thick partially, and solid electrolyte reaches working temperature length consuming time, certainly will reduce the resistance of heating electrode for shortening the reaction time, and the life-span of heating electrode and solid electrolyte all will be affected like this.

In addition,, in the patent document of the patent No. JP09171015 main part and ejectment element portion are separately made in order to prevent in the sintering process that activated electrode is polluted in the gold volatilization in the disactivation electrode, sinter molding separately, and then unite two into one.Can still also there be following two technological difficulties in this technology by simplified structure at least:

1. except there is technical difficulty in sealing, also can increase the unrelieved stress of chip when ejectment part and main part are superimposed;

2. the ejectment partial electrode is difficult with being connected of lead-in wire.

The researcher is also arranged in order to reduce manufacture difficulty, improve the on-state rate of heating electrode, with heater section making and then superimposed separately with main part.Do so really and can improve chip, especially the yield rate of heater section has still simultaneously also increased cost, and in heating process, the easy heat of aggregation stress of the boundary of heating plate and main part, thus cracking caused.

Summary of the invention

The purpose of this invention is to provide a kind of built-in heating, simple in structure, quick startup, under working temperature, realize effectively compressing the flat automobile NOx sensor chip that sealing does not produce excessive thermal stress again.

The technical solution adopted in the present invention is:

A kind of automobile NOx sensor chip, comprise first substrate that is overrided to form to layer 5, the layer 5 substrate is provided with heating electrode, the heating electrode undulate is arranged, be coated with insulation course on the heating electrode, the top of the 4th layer of substrate is provided with the reference gas passage, and the reference gas passage comprises thick chamber and thin chamber, and thin chamber links to each other by aperture with thick chamber.

Described insulating layer material is the ceramic powder slurry based on aluminium oxide.

Described thin chamber thickness is 1/4th to 1/3rd of thick chamber thickness.

Beneficial effect: owing to adopt technique scheme, that the present invention has is simple in structure, the thermal efficiency is high, quick startup, realize effectively compressing the characteristics that sealing does not produce excessive thermal stress again under working temperature.Heating element, ejectment element and detecting element are made as one, only can finish by superimposed back high temperature sintering once.

Description of drawings

Fig. 1 is an one-piece construction sectional view of the present invention;

Fig. 2 is the vertical view of second layer substrate of the present invention;

Fig. 3 is that heating plate of the present invention is the vertical view of layer 5 substrate.

Embodiment

The invention will be further described below in conjunction with accompanying drawing.

A kind of automobile NOx sensor chip, comprise

first substrate

2,11,21,13,14 that is overrided to form to layer 5, layer 5 substrate 14 is provided with heating electrode 19, heating electrode 19 undulates are arranged, be coated with insulation course 18 on the heating electrode 19, the top of the 4th layer of substrate 13 is provided with the reference gas passage, and the reference gas passage comprises thick chamber 12 and thin chamber 16, and thin chamber 16 links to each other by aperture 15 with thick chamber 12.

Described insulation course 18 materials are the ceramic powder slurry based on aluminium oxide.

Described thin chamber 16 thickness are 1/4th to 1/3rd of thick chamber 12 thickness.

Fig. 1 is a kind of internal heater structural representation of the present invention.Layer 5 substrate 14 is a heating plate, and the substrate material is fine and close yttrium stable zirconium oxide, and layer 5 substrate 14 upper surfaces are printed heating electrode 19, for guaranteeing the insulation of layer 5 substrate 14 and the 4th layer of substrate 13, prints insulation paste 18 on heating electrode 19.

Ground floor substrate 2, second layer substrate 11, the 3rd layer of substrate 21 are formed the ejectment element, first electrode 1, second electrode 5, ground floor substrate 2 and impressed voltage constitute oxygen pump one, and its function is to reduce oxygen concentration in first cavity 6 to certain value by the size of regulating impressed voltage.First electrode 1, third electrode 8, ground floor substrate 2 and impressed voltage constitute oxygen pump two, and its function is to reduce oxygen concentration in second cavity 9 to approaching 0ppm by the size of regulating impressed voltage.Thereby impel the decomposition of oxides of nitrogen gas.

Second layer substrate 11, the 3rd layer of substrate 21 and the 4th layer of substrate 13 are formed detecting element.The 4th electrode 10, the 5th electrode 17, the 3rd layer of substrate 21 are formed the loop with extension instrument, can reflect the concentration of oxides of nitrogen gas in second cavity 9 by the reading of extension instrument.Thick chamber 12 is the reference gas passage, connects by aperture 15 and thin chamber 16, thereby also is reference gas in the thin chamber 16.

Fig. 2 is the vertical view of second layer substrate 11.Gas to be measured is stabilization in the 3rd cavity 22, enter the 4th cavity 20 through ground floor diffusion barrier layer 3, stabilization once more, enter first cavity 6 through second layer diffusion barrier layer 4, gas in first cavity 6 under the effect of oxygen pump one oxygen concentration be reduced, after enter second cavity 9 through the 3rd layer of diffusion barrier layer 7, gas in second cavity 9 under the effect of oxygen pump two oxygen concentration further reduce so that oxides of nitrogen gas is decomposed into oxygen and nitrogen.

Fig. 3 is the vertical view of layer 5 substrate 14 for heating element.It is heat distribution requirements in order to improve the rate of heat addition and to satisfy chip operation that heating electrode 19 adopts the bending purposes.

Heating part adopts the method making of printing the platinum circuit at the yttrium stable zirconium oxide substrate.Heating electrode 19 all be printed with insulation paste up and down, heating electrode 19 links to each other with the pin of reverse side by the method for perforation conducting, and is printed with on the heating electrode 19 and links to each other to reach the purpose of temperature control with thermopair after the platinum lead-in wire is derived.For shortening heat time heating time and making chip satisfy desirable heat distribution, heating electrode 19 is designed to bending, sees accompanying drawing 3 for details.

Ejectment element and detecting element all adopt the yttrium stable zirconium oxide substrate to make.Entire chip finished product (after the sintering) is of a size of: length is 60～70mm; Wide is 4～5mm; Height is 1～2mm.By 5 layers of disposable being formed by stacking of substrate, all adopt the yttrium stable zirconium oxide substrate to make altogether.Bottom one deck is a heating plate, above four functions of finishing ejectment and detection.

Owing to adopt technique scheme, this is simple in structure, the thermal efficiency is high, quick startup, realize that under operating temperature effective press seal does not produce again the characteristics of excessive thermal stress.

Claims

1. automobile NOx sensor chip, comprise first substrate (1,11,21,13,14) that is overrided to form to layer 5, it is characterized in that: layer 5 substrate (14) is provided with heating electrode (19), heating electrode (19) undulate is arranged, be coated with insulation course (18) on the heating electrode (19), the top of the 4th layer of substrate (13) is provided with the reference gas passage, the reference gas passage comprises thick chamber (12) and thin chamber (16), and thin chamber (16) links to each other by aperture (15) with thick chamber (12).

2. automobile NOx sensor chip according to claim 1 is characterized in that: described insulation course (18) material is the ceramic powder slurry based on aluminium oxide.

3. automobile NOx sensor chip according to claim 1 is characterized in that: described thin chamber (16) thickness is 1/4th to 1/3rd of thick chamber (12) thickness.