CN210487676U - Household appliance air-fuel ratio sensor capable of rapidly igniting - Google Patents

Abstract

The utility model provides a fast ignition air-fuel ratio sensor for household appliances, which comprises a solid electrolyte layer, a diffusion layer and a substrate layer which are arranged in sequence; the outer surface of the solid electrolyte layer is provided with an outer electrode, the inner surface of the solid electrolyte layer is provided with an inner electrode, one end of the diffusion layer is in butt joint with the inner electrode and is sealed by the inner electrode and the substrate layer to form a closed end, and the other end of the diffusion layer extends out of the solid electrolyte layer and the substrate layer to form an air inlet end. The utility model discloses can reduce the air input of diffusion layer, make the sensor can reach the limiting current with faster speed when cold start.

Description

Household appliance air-fuel ratio sensor capable of rapidly igniting

[ technical field ] A method for producing a semiconductor device

The utility model relates to an air-fuel ratio sensor, in particular to air-fuel ratio sensor for household electrical appliances.

[ background of the invention ]

In recent years, gas sensors have been developed rapidly, and besides being widely used in the automobile field, the gas sensors have also been widely paid attention and accepted in some industries such as civil life, national defense, medicine, food safety and the like, in particular to sensors for detecting oxygen content. At present, conventional switch-type sensors have been unable to meet increasingly stringent oxygen content detection requirements. Instead, an air-fuel ratio sensor with higher control accuracy is used. For example, a household oven needs to adopt an air-fuel ratio sensor with higher precision and faster ignition time for detecting the oxygen content in the oven so as to calculate the water content.

For an air-fuel ratio sensor, a gas diffusion structure is one of the core elements of the characteristics relating to product measurement accuracy, stability, light-off time, and the like.

As shown in fig. 1, a conventional air-fuel ratio sensor 100 'includes a solid electrolyte layer 1', a diffusion layer 2 ', and a base layer 3' provided in this order. The outer surface of the solid electrolyte layer 1 ' is provided with an outer electrode 11 ', the inner surface is provided with an inner electrode 12 ', the outer electrode 11 ' is further covered with a protective layer 4 ', the base layer 3 is further provided with a heater 5 ', and the diffusion layer 2 ' is covered on the inner electrode 12 ', so that oxygen can be conveniently conveyed to the inner electrode 12 '. The diffusion layer 2 'is generally formed on a substrate layer below the solid electrolyte 1' by silk-screening a porous thin layer with high porosity, the porosity is about 35-45%, and the conventional diffusion layer 2 'generally adopts a two-side air inlet mode, namely, the left end and the right end of the diffusion layer 2' are communicated with the edge of the whole device, so that the purpose of air inlet at the two ends is achieved. On one hand, the air inlet mode has high requirements on the material of the silk-screen slurry, and the high porosity easily causes low product bonding strength; on the other hand, the porosity of the porous diffusion layer is large, and the air inflow caused by air inflow on two sides is large, so that the time of the product outputting the limiting current (1.5-2.8 mA), namely the ignition time is long, usually reaches 10-20 s, and the detection of the oxygen or water content when the household appliance is just started is not facilitated.

[ summary of the invention ]

The to-be-solved technical problem of the utility model lies in providing a household electrical appliances of quick light-off are with air-fuel ratio sensor, through the air input that reduces the diffusion layer, make the sensor can reach limiting current with faster speed when cold start.

The utility model discloses a realize like this: a fast ignition household appliance air-fuel ratio sensor comprises a solid electrolyte layer, a diffusion layer and a substrate layer which are arranged in sequence; the outer surface of the solid electrolyte layer is provided with an outer electrode, the inner surface of the solid electrolyte layer is provided with an inner electrode, one end of the diffusion layer is in butt joint with the inner electrode and is sealed by the inner electrode and the substrate layer to form a closed end, and the other end of the diffusion layer extends out of the solid electrolyte layer and the substrate layer to form an air inlet end.

According to the utility model discloses a specific embodiment, the diffusion layer is made at aluminium oxide casting piece by porous thick liquids printing, porous thick liquids's porosity is 15 ~ 30%, and printing thickness is 10 ~ 20 mu m, and the printing width is 1 ~ 3 mm.

According to the specific embodiment of the present invention, the thickness of the alumina casting sheet is 100 to 300 μm.

According to the utility model discloses a specific embodiment, the base member layer with still have an air chamber between the inner electrode, the blind end of diffusion layer is connected in this air chamber.

According to the utility model discloses a specific embodiment, air-fuel ratio sensor for household electrical appliances still includes a protective layer, the protective layer covers completely on the outer electrode.

The utility model has the advantages that: the utility model discloses an air-fuel ratio sensor for household electrical appliances, its diffusion layer one end is admitted air, and one end is sealed, forms the unilateral mode of admitting air and reduces the air input, and adopts the lower porous thick liquids of porosity to print in aluminium oxide curtain coating piece and get when specifically realizing, makes the porosity control at 15% ~ 30% to make the product can reach the limiting current with faster speed when cold start.

[ 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 a cross-sectional view showing a diffusion position of a conventional air-fuel ratio sensor

Fig. 2 is a schematic structural diagram of a diffusion position cross section of the air-fuel ratio sensor for household appliances.

Fig. 3 is an exploded schematic view of the air-fuel ratio sensor for household electrical appliances of the present invention.

Fig. 4 is a schematic diagram comparing the light-off time of the air-fuel ratio sensor of the present invention with the existing air-fuel ratio sensor.

[ detailed description ] embodiments

Referring to fig. 2 and fig. 3, the fast ignition air-fuel ratio sensor 100 for household electrical appliances of the present invention comprises a solid electrolyte layer 1, a diffusion layer 2, a substrate layer 3, a protective layer 4, and a heater 5 on the substrate layer 3; the outer surface of the solid electrolyte layer 1 is provided with an outer electrode 11, the inner surface is provided with an inner electrode 12, and the protective layer 4 completely covers the outer electrode 11.

One end of the diffusion layer 2 is abutted against the inner electrode 12 and is closed by the inner electrode 12 and the base layer 3 to form a closed end 21, and the other end extends beyond the solid electrolyte layer 1 and the base layer 3 to form an air inlet end 22. And a gas chamber 23 is also arranged between the substrate layer 3 and the inner electrode 12, the closed end 21 of the diffusion layer is connected to the gas chamber 23, gas enters the gas chamber 23 through the diffusion layer 2 and contacts with the inner electrode 12, and the gas chamber 23 can play a role of gas buffering, so that the gas pressure at the side of the inner electrode 12 is reduced, and the output limiting current Ip is flatter.

The diffusion layer 2 is formed by printing porous slurry on an alumina tape-cast sheet, wherein the porosity of the porous slurry is 15-30%, the printing thickness is 10-20 μm, and the printing width is about 1-3 μm. The thickness of the alumina casting sheet is 100-300 mu m, and the alumina casting sheet is the solid electrolyte casting sheet of the solid electrolyte layer 1.

The utility model discloses an air-fuel ratio sensor for household electrical appliances, gaseous from diffusion layer 2 entering into the 12 sides of inner electrode, oxygen gets the electron and becomes oxygen ion, and oxygen ion transports outer electrode 11 sides through solid electrolyte layer 1, loses electron again and obtains oxygen, and the limiting current IP of formation is directly proportional with the oxygen volume of transmission. Therefore, the smaller the intake air amount, the smaller the limit current Ip to be output. The experiment proves, the utility model discloses an air-fuel ratio sensor for household electrical appliances is only at unilateral printing diffusion barrier thick liquids, and the limiting current of output is steerable at 100 ~ 300 mu A. By adopting the structure, the ignition time can be controlled within 5-10 s at the normal working temperature.

The utility model discloses an implementation process:

preparing a casting sheet: adding a certain amount of auxiliary materials such as a solvent, a dispersing agent, a binder, a plasticizer and the like into high-purity alumina powder, carrying out ball milling and mixing in a ball milling tank to prepare slurry of a uniform system, defoaming the slurry, preparing an alumina casting sheet with the thickness of about 100-300 mu m by using a casting machine, preparing a solid electrolyte casting sheet with 6 mol% of yttria and partial stability by using the same method, using carbon powder as a porous casting sheet of a pore-forming agent, and adjusting the porosity of the porous casting sheet by adjusting the adding amount of the carbon powder.

Preparing diffusion layer slurry: a certain amount of carbon powder is added into alumina powder to prepare diffusion layer slurry with corresponding porosity, and the porosity is generally controlled to be 15-30%.

Punching: punching the heating matrix layer casting sheet, the solid electrolyte layer casting sheet, the diffusion matrix layer casting sheet and the protective layer casting sheet in a mechanical punching mode, wherein 3 small holes are punched for ensuring communication, and the diameter of each through hole is selected to be 0.2-0.3 mm;

and (3) silk-screen printing: silk-screen printing a heater, a heater lead and heater pins on the heating substrate layer tape casting sheet by adopting a silk-screen printing technology, and silk-screen printing an inner electrode, an outer electrode and an electrode lead on the solid electrolyte layer tape casting sheet; printing a layer of carbon paste on the inner electrode; printing diffusion layer slurry on a substrate layer below the solid electrolyte; screen printing through holes on the protective layer tape casting sheet to ensure that signals at the electrode end can be conducted with the electrode pins; printing electrode pins on the other side of the protective layer in a silk-screen manner;

punching a square hole: punching a square hole on the protective layer casting sheet in an upper die and a lower die mode, and punching the porous protective layer into the same size by adopting the same die;

6) laminating: sequentially overlapping a heater substrate layer casting sheet, a plurality of support layer casting sheets (for example, 4 layers), a solid electrolyte layer casting sheet and a protective layer casting sheet together, and cutting after isostatic pressing;

7) and (3) binder removal and sintering: and (3) placing the element biscuit in a high-temperature sintering furnace to prepare the air-fuel ratio oxygen sensor for the household appliance. The binder, the plasticizer and other organic matters in the biscuit are rapidly decomposed and expanded in a binder removal stage, so that structural defects such as cracking and layering are avoided, a slow speed is adopted in the binder removal stage, a temperature rise speed of 1.5 ℃/min or less is adopted from the normal temperature to 500 ℃, heat preservation is carried out at a temperature point where the plasticizer and the binder are severely volatilized, for example, the temperature is preserved at 270 ℃ for 2 hours, and the time of the whole binder removal stage is about 40-48 hours. The sintering process adopts a high-temperature sintering furnace and is carried out under the atmospheric condition of normal pressure, the sintering temperature is 1400-1600 ℃, and the time is 1-3 h.

Example one

According to the air-fuel ratio sensor 100 for home appliances of the present invention, the porous slurry for preparing the diffusion layer 2 has a porosity of 20% and a single-sided air inlet method, and has a printing thickness of 15 μm and a printing width of about 2 mm. The thickness of the cast aluminum oxide sheet was 200 μm.

Comparative example 1

The comparative example is a conventional air-fuel ratio sensor, and the structure shown in fig. 1 is adopted, that is, the diffusion layer 2 'of the air-fuel ratio sensor 100' of the comparative example is a double-sided intake system. The porosity of the porous thin layer used for screen printing the diffusion layer 2' was 40%, the printing thickness was 15 μm, and the printing width was about 2 mm.

Comparing the ignition time of the air-fuel ratio sensor of the first embodiment with that of the first comparative example of the existing air-fuel ratio sensor, the comparison effect is shown in fig. 4, and the solid line part is shown, the output limit current IP1 of the air-fuel ratio sensor of the first embodiment of the present invention can be controlled at 200 muA and the ignition time t1 can be controlled at about 7s at normal operating temperature; see the dashed line, while the air-fuel ratio sensor of the comparative example outputs the limiting current IP2 of about 1.5mA at the normal operating temperature, and the light-off time t2 requires about 14 s. It can be seen that the utility model discloses an air-fuel ratio sensor for household electrical appliances can reach the limiting current with faster speed when cold-start.

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 (5)

1. The utility model provides an air-fuel ratio sensor for household electrical appliances that light-off fast which characterized in that: comprises a solid electrolyte layer, a diffusion layer and a matrix layer which are arranged in sequence; the outer surface of the solid electrolyte layer is provided with an outer electrode, the inner surface of the solid electrolyte layer is provided with an inner electrode, one end of the diffusion layer is in butt joint with the inner electrode and is sealed by the inner electrode and the substrate layer to form a closed end, and the other end of the diffusion layer extends out of the solid electrolyte layer and the substrate layer to form an air inlet end.

2. The fast light-off air-fuel ratio sensor for home appliances according to claim 1, wherein: the diffusion layer is formed by printing porous slurry on an alumina casting sheet, wherein the porosity of the porous slurry is 15-30%, the printing thickness is 10-20 mu m, and the printing width is 1-3 mm.

3. The fast light-off air-fuel ratio sensor for home appliances according to claim 2, wherein: the thickness of the alumina casting sheet is 100-300 mu m.

4. The fast light-off air-fuel ratio sensor for home appliances according to claim 1, wherein: and a gas chamber is also arranged between the substrate layer and the inner electrode, and the closed end of the diffusion layer is connected with the gas chamber.

5. The fast light-off air-fuel ratio sensor for home appliances according to claim 1, wherein: the protective layer is completely covered on the outer electrode.

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