CN210347524U

CN210347524U - Civil air-fuel ratio sensor chip and civil air-fuel ratio sensor

Info

Publication number: CN210347524U
Application number: CN201921281559.0U
Authority: CN
Inventors: 余昌艳; 洪旭; 张财盛
Original assignee: Xiamen Haisai Mike New Material Technology Co ltd
Current assignee: Xiamen Haisai Mike New Material Technology Co ltd
Priority date: 2019-08-08
Filing date: 2019-08-08
Publication date: 2020-04-17
Anticipated expiration: 2029-08-08

Abstract

The utility model provides a civilian air-fuel ratio sensor chip and civilian air-fuel ratio sensor, include: the upper surface of the solid electrolyte layer is provided with an outer electrode, and the lower surface of the solid electrolyte layer is provided with an inner electrode; a diffusion base layer provided below the solid electrolyte layer; a heater layer disposed below the diffusion substrate layer; and the porous diffusion barrier layer is arranged on the diffusion base body layer and covers the surface of the inner electrode, and the porous diffusion barrier layer is provided with air holes which can be communicated with each other, so that gas is introduced to the position of the inner electrode from the outer side of the diffusion base body layer with a certain barrier. The utility model discloses sensor chip area porous diffusion barrier layer structure, the precision is high, measuring range is wide, simple structure and with low costs.

Description

Civil air-fuel ratio sensor chip and civil air-fuel ratio sensor

[ technical field ] A method for producing a semiconductor device

The utility model relates to a sensor, in particular to civil air-fuel ratio sensor chip's structure.

[ background of the invention ]

Sensors for measuring the oxygen content in the exhaust gases of internal combustion engines are well known. Gas sensors for measuring oxygen content are mainly classified into narrow-area types and wide-area types according to output characteristics, and the narrow-area types utilize the nernst principle of zirconia solid electrolytes, and although it can be confirmed whether the oxygen content in exhaust gas is rich or lean, accurate judgment cannot be made. The wide-range type limit current technology can realize linear control on the oxygen content and accurately judge the specific value of the oxygen content in the exhaust gas.

In recent years, gas sensors for detecting the oxygen content in gas are widely used in the fields of medical treatment, infant incubator, fermentation equipment, incubator, food packaging, air quality monitoring and the like. However, the existing narrow-area sensor cannot meet the detection requirement of the specific content of oxygen, and the existing wide-area sensor involves the measurement of gas content under reducing atmosphere and oxidizing atmosphere, so that the structure is complex, the production cost is high, and the detection of the full concentration range of oxygen cannot be realized.

[ Utility model ] content

The to-be-solved technical problem of the utility model lies in providing a civil air-fuel ratio sensor chip and civil air-fuel ratio sensor, take porous diffusion obstacle layer structure, precision height, measuring range are wide, simple structure and with low costs.

On the one hand, the utility model provides a civilian air-fuel ratio sensor chip realizes like this: a civil air-fuel ratio sensor chip comprising:

the upper surface of the solid electrolyte layer is provided with an outer electrode, and the lower surface of the solid electrolyte layer is provided with an inner electrode;

a diffusion base layer provided below the solid electrolyte layer;

a heater layer disposed below the diffusion substrate layer;

and the porous diffusion barrier layer is arranged on the diffusion base body layer, one end of the porous diffusion barrier layer covers the surface of the inner electrode, the other end of the porous diffusion barrier layer extends to the edge of the diffusion base body layer, and the porous diffusion barrier layer is provided with air holes which can be communicated with each other, so that gas is introduced into the inner electrode from the outer side of the diffusion base body layer with a certain barrier.

Further, the utility model discloses in can also be:

the porosity of the porous diffusion barrier layer is between 10% and 40%.

The porous diffusion barrier layer is of a linear type, an L type and a reciprocating and reversing type sheet-like structure.

The solid electrolyte layer is also provided with a porous protective layer which covers the surface of the outer electrode.

On the other hand, the utility model provides a civilian air-fuel ratio sensor realizes like this: the utility model provides a civilian air-fuel ratio sensor, has as above the utility model discloses a civilian air-fuel ratio sensor chip.

The utility model has the advantages that:

1. the measurement precision is high, the gas entering the inner electrode side is limited through the porous diffusion barrier layer, the gas flow is stable, the output signal fluctuation is small, the stability is high, and the high-precision control can be realized;

2. the full concentration range detection can be carried out, and different limiting current output ranges can be realized by controlling the porosity of the material of the porous diffusion barrier layer, the diffusion section area of the porous diffusion barrier layer and the diffusion distance. Therefore, different output current ranges can be selected according to different application fields and different oxygen contents, so that the detection with high precision and full concentration range is realized;

3. the insulating property is strong, and the substrate layer and the heater layer are made of alumina materials with excellent insulating property, so that the current in a heater loop can be prevented from generating interference on the output signal of the solid electrolyte layer;

4. the protection performance is strong, the outer electrode and the inner electrode are respectively contacted with the test gas through the porous protection layer and the porous diffusion barrier layer, and the porous protection layer can adsorb particulate matters and partial water vapor in the test gas, so that the electrode and the device are protected, and the service life of the device is long;

6. the cost is low, and compared with a wide-area gas sensor used by an internal combustion engine, the whole device has small volume, so that the used platinum slurry can be greatly reduced, and the device has considerable market competitiveness.

[ description of the drawings ]

The invention will be further described with reference to the following examples with reference to the accompanying drawings.

Fig. 1 is an overall schematic diagram of the sensor chip of the present invention.

Fig. 2 is a functional block diagram of the sensor chip of the present invention.

Fig. 3 is an exploded view of the sensor chip of the present invention.

Fig. 4 is a schematic structural view of several longitudinal sections of the middle porous diffusion barrier layer of the present invention.

[ detailed description ] embodiments

Referring to fig. 1 to 3, a civil air-fuel ratio sensor chip 100 of the present invention includes:

a solid electrolyte layer 1, the upper surface of which is provided with an outer electrode 11 and the lower surface of which is provided with an inner electrode 12; and a porous protection layer 13 is also arranged, and the porous protection layer 13 covers the surface of the outer electrode 12.

A diffusion base layer 2 provided below the solid electrolyte layer 1;

a heater layer 3 disposed below the diffusion base layer 2;

and the porous diffusion barrier layer 4 is arranged on the diffusion base body layer 2, one end of the porous diffusion barrier layer is covered on the surface of the inner electrode 12, the other end of the porous diffusion barrier layer extends to the edge of the diffusion base body layer 2, the porous diffusion barrier layer 4 is provided with air holes 42 which can be communicated with each other, and gas is led into the inner electrode 12 from the outer side of the diffusion base body layer with a certain barrier.

Wherein, specifically:

the solid electrolyte layer 1 is a zirconia material (YSZ) layer with partially stabilized yttria, and the upper surface is provided with the outer electrode 11, an outer electrode lead 112, two outer electrode pins 114 and the porous protection layer 13 by screen printing; the lower surface is provided with an inner electrode 12 and an inner electrode lead 122 through screen printing, the inner electrode 12 is connected with an inner electrode pin 123 through the inner electrode lead 122 and then to a via hole 15, the outer electrode 11 is connected with an outer electrode pin 114 through an outer electrode lead 112, the two outer electrode pins 114 realize the external output of signals, and meanwhile, the porous protection layer 13 completely covers the outer electrode 11 and the outer electrode lead 112 and does not cover the electrode pins 114. The solid electrolyte layer 1 is formed by catalyzing oxygen ions by the electrode under a high temperature condition by utilizing the Nernst principle, and the oxygen ions are conducted through the solid electrolyte material, so that signals are generated among the outer electrode pins 114 and are output to the outside.

The diffusion base layer 2 is an alumina material layer, and one of the functions is to play an insulating role so that signals of the heater cannot interfere with the solid electrolyte layer 1, and the other function is to serve as a support of the porous diffusion barrier layer 4.

The heater layer 3 is an alumina material layer, the upper surface of the heater layer is provided with a heater 31 and a heater lead 32, the lower surface of the heater layer is provided with a heater pin 33, and the heater 31 is connected with the heater pin 33 through the heater lead 32, so that the input of external voltage is realized. The function of the heater layer 3 is to provide a heat source to the sensor so that the solid electrolyte layer 1 reaches a desired operating temperature, e.g. 700 ℃.

The porous diffusion barrier layer 4 is formed on an alumina casting sheet of the diffusion substrate layer 2 by silk-screen porous diffusion slurry, wherein the porous diffusion slurry adopts high-purity alumina powder which is the same as that in the alumina casting sheet as a ceramic substrate, 42-57 parts of alumina ceramic powder, 5-20 parts of pore-forming agent, 7 parts of binder, 1 part of dispersant and 30 parts of solvent.

The porosity of the porous diffusion barrier layer 4 is 10% to 40%. The porous diffusion barrier layer 4 can be designed into different shapes according to different requirements of output limiting current, for example, in fig. 3, (a) the longitudinal section is a linear type, (b) an L-shaped sheet-like structure and (c) a reciprocating and folding type sheet-like structure, wherein the linear type path is shorter, the L-shaped path is centered, and the reciprocating and folding type path is longer, the diffusion distance of oxygen ions can be controlled by controlling the length of the path, and the control of the cross-sectional area (namely, the diffusion sectional area) is combined, so that different output current ranges can be selected according to different application fields and different oxygen contents, and the design requirements of different limiting currents are met, thereby realizing the detection of high precision and full concentration range.

On the other hand, assemble foretell civilian air-fuel ratio sensor chip, form civilian air-fuel ratio sensor, realized promptly the utility model discloses a civilian air-fuel ratio sensor.

The utility model discloses a theory of operation:

in use, as shown in fig. 2, the whole sensor is placed in a test gas after being assembled, the heater 31 is energized to generate heat so that the solid electrolyte layer 1 reaches an operating temperature, a voltage U is applied between the inner electrode 12 and the outer electrode 11, and oxygen gas is pumped from the inner electrode side to the outer electrode side of the solid electrolyte layer 1 in the form of oxygen ions. As the voltage U increases, the current value I between the electrodes increases first, and then the presence of the porous diffusion barrier 4 restricts the entry of gas to saturate the current, which is called the limiting current Ip, and is almost proportional to the ambient oxygen concentration, as shown in equation (1).

F is Faraday constant, R is gas constant, T is absolute temperature, D is O2 diffusion constant, s is cross-sectional area of the porous diffusion barrier layer, β is porosity of the material of the porous diffusion barrier layer, l is diffusion distance, P (O2) is oxygen concentration in the test gas.

In this way, the output current of the sensor and the corresponding oxygen concentration have a corresponding relationship, thereby achieving the purpose of detection. Due to production tolerances, each sensor must be calibrated individually. The sensor varies depending on its application range, and is mainly determined by the operating voltage and output current range.

Although specific embodiments of the present invention have been described, it will be understood by those skilled in the art that the specific embodiments described are illustrative only and are not limiting upon the scope of the invention, and that equivalent modifications and variations can be made by those skilled in the art without departing from the spirit of the invention, which is to be limited only by the claims appended hereto.

Claims

1. A civil air-fuel ratio sensor chip is characterized in that: the method comprises the following steps:

a diffusion base layer provided below the solid electrolyte layer;

a heater layer disposed below the diffusion substrate layer;

2. The civil air-fuel ratio sensor chip as recited in claim 1, wherein:

the porosity of the porous diffusion barrier layer is between 10% and 40%.

3. The civil air-fuel ratio sensor chip as recited in claim 1, wherein:

4. The civil air-fuel ratio sensor chip as recited in claim 1, wherein: the solid electrolyte layer is also provided with a porous protective layer which covers the surface of the outer electrode.

5. A civil air-fuel ratio sensor characterized by: has a civil air-fuel ratio sensor chip as claimed in any one of claims 1 to 4.