JPH07107527B2 - Oxygen sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention provides an oxygen sensor that improves thermal efficiency and power consumption by reducing the overall shape to a small thickness to reduce power consumption. Regarding

[Prior Art] Conventionally, an oxygen sensor has been put into practical use, which measures an oxygen concentration from a current change accompanying movement of an oxygen sensor in a solid electrolyte having ion conductivity such as stabilized zirconia.

FIG. 2 shows a conventional example of this type of oxygen sensor 1, which comprises a solid electrolyte 2 made of a ceramic similar to ion conductive stabilized zirconia, and the solid electrolyte 2.
Porous electrodes 3A and 3B which are respectively laminated on both sides of the solid electrolyte 2 and to which a predetermined voltage is applied, a ceramic cap 5 bonded to one surface of the solid electrolyte 2 with an amorphous glass 4 interposed therebetween, and a ceramic cap 5 The heater 6 is provided on the upper surface and applies heat to the solid electrolyte 2. In the figure, 7 is a cavity for bringing the gas to be measured into contact with one surface of the solid electrolyte 2, 8 is a gas diffusion hole, and 9 is a lead wire connected to a DC power source.

In the oxygen sensor 1, when the solid electrolyte 2 is heated by the heater 6 and activated to apply a DC voltage, oxygen in the gas in the cavity 7 permeates the solid electrolyte 2 due to the pumping action. An ionic current using the oxygen sensor as a carrier flows through the solid electrolyte 2, and the ambient oxygen concentration is measured from the current value of the ionic current.

[Problems to be Solved by the Invention] In the conventional oxygen sensor 1 described above, the heat generated by the heater 6 changes from the ceramic cap 5 to the amorphous glass 4.
→ Solid electrolyte 2 path or ceramic cap 5
→ Cavity 7 → Conducted through the path of the solid electrolyte 2, so there was a problem that the heating efficiency was poor. As a result, in order to sufficiently heat the solid electrolyte 2, the heater 6 needs a considerable wattage, and there is a problem that the power consumption becomes large.

The present invention solves the above problems, and an object of the present invention is to provide an oxygen sensor that improves thermal efficiency and power consumption by reducing the overall shape with a thin thickness and a small size, and at the same time, achieves improved airtightness. .

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a solid electrolyte having ionic conductivity, a pair of porous electrode plates formed on both surfaces of the solid electrolyte, and a cathode side. A powdery filler formed to cover the electrode plate, amorphous glass formed to cover the filler, crystallized glass formed to cover the amorphous glass, and crystallization It is characterized by comprising a heater formed on the surface of the glass and a gas diffusion hole communicating with the filling material.

[Operation] According to the present invention, the oxygen sensor has a laminated structure composed of a powdery filler that covers the cathode side electrode plate on one surface of the solid electrolyte, amorphous glass, and crystallized glass. Since the heater is formed, the heat from the heater is efficiently conducted to the solid electrolyte through the crystallized glass, the amorphous glass and the filler. Further, since the laminated structure as described above is used, it is possible to form the entire structure to be thin.
As a result, the thermal efficiency of the heater can be improved and the power consumption can be reduced.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing the structure of the oxygen sensor 10 of the present embodiment. In the figure, reference numeral 11 is a solid electrolyte, which is formed in a thin and thick shape having ion conductivity such as stabilized zirconia. Gas diffusion holes 12 are formed in the solid electrolyte 11, and the gas diffusion holes 12 are filled with a filler, an amorphous glass,
Closed space formed by crystallized glass and oxygen sensor 10
By controlling the diffusion with the outside, the diffusion rate control is generated. In addition, a porous electrode plate (cathode) 13 and electrode plate (anode) 14 are laminated on both sides of the solid electrolyte 11, and a direct current power source (not shown) leads to these electrode plates 13 and 14. A predetermined voltage is applied via the lines 15 and 16.

Further, the surface of the electrode plate 13 on the cathode side is formed of alumina (Al ₂ O
₃ ) A filler 17 such as powder is provided and the filler 1
An amorphous glass 18 is provided on the surface of 7, and a crystallized glass 19 is provided on the surface of the amorphous glass 18. Further, a heater 20 is provided on the upper surface of the crystallized glass 19,
A predetermined voltage is applied from a heater voltage applying circuit (not shown) via the lead wires 21. The overall shape of the oxygen sensor 10 of this embodiment is thinner and smaller than that of the conventional oxygen sensor.

Next, an example of a manufacturing process of the oxygen sensor 10 having the above configuration will be described.

Step 1: Gas diffusion holes 12 are formed in the solid electrolyte 11.

Step 2: A conductive material paste such as a porous platinum paste is printed on both surfaces of the solid electrolyte 11 to form electrode plates 13 and 14 by firing, and lead wires 15 and 16 are attached to the electrode plates 13 and 14, respectively. Install each.

Step 3: Filling material such as alumina powder on the entire surface of the electrode plate 13
Apply 17.

Step 4: An amorphous glass 18 having high airtightness is applied to the entire surface of the filler 17 and fired. By forming the amorphous glass 18, the electrode plate 13 is sealed.

Step 5: The crystallized glass 19 is applied to the entire surface of the amorphous glass 18 and baked.

Step 6: A heater 20 is printed and formed on the upper surface of the crystallized glass 19.

Process 7: Attach the lead wires 21 and 21 to the heater 20.

In this case, since the electrode plates 13 and 14 are porous,
The gas diffusion holes 12 formed in the solid electrolyte 11 can smoothly generate the diffusion rate controlling.

The oxygen sensor 10 of the present embodiment has a laminated structure in which a filler 17 such as alumina powder, an amorphous glass 18, and a crystallized glass 19 are sequentially applied and fired on the electrode plate 13 on the cathode side of the solid electrolyte 11 surface. Since the heater 20 is formed on the surface of the crystallized glass 19 by printing, the entire sensor can be formed thin. And, unlike the oxygen sensor of the conventional structure which has a cavity and in which the ceramic cap and the solid electrolyte are in contact only with the surrounding amorphous glass portion, the heat from the heater 20 is directly in contact with the crystallized glass 19 and the amorphous glass. Glass 18,
Conducts efficiently to the solid electrolyte 11 through the filler 17. Therefore, the effect of reducing the thickness of the entire sensor and the effect of improving the thermal conductivity are combined, so that the power consumption of the heater can be significantly reduced compared to the conventional case.

Although the gas diffusion holes 12 are formed in the solid electrolyte 11 in the above embodiment, the present invention is not limited to this, and the gas diffusion holes may be formed in the amorphous glass 18, the crystallized glass 19 and the heater 20, for example. That is, the gas diffusion holes may be arranged either below or above the filler 17 of the oxygen sensor 10.

[Effects of the Invention] As described above, according to the present invention, a solid electrolyte having ionic conductivity, a pair of porous electrode plates formed on both surfaces of the solid electrolyte, and the electrode plate on the cathode side. On the surface of the crystallized glass, the powdery filler formed to cover the amorphous glass, the amorphous glass formed to cover the filler, the crystallized glass formed to cover the amorphous glass Since the heater is formed and the gas diffusion hole communicating with the filling material is provided, the following effects are obtained.

Since the oxygen sensor has the above structure, the entire thickness can be made thin. Furthermore, since the crystallized glass, the amorphous glass, and the filler are in direct contact with each other, the heat from the heater is transferred to the solid electrolyte. As a result of smooth conduction, thermal efficiency can be significantly improved as compared with the conventional case, power consumption can be reduced, and the airtightness of the oxygen sensor can be further improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an oxygen sensor according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the structure of a conventional oxygen sensor. 10 ... Oxygen sensor, 11 ... Solid electrolyte, 12 ... Gas diffusion hole, 13/14 ... Electrode plate, 17 ... Filling material, 18 ... Amorphous glass, 19 ... Crystallized glass, 20 ... …heater.

Claims (1)

[Claims] 1. A solid electrolyte having ionic conductivity (11)
A pair of porous electrode plates (13, 14) formed on both sides of the solid electrolyte, a powdery filler (17) formed to cover the electrode plate on the cathode side, and the filling An amorphous glass (18) formed to cover the material, a crystallized glass (19) formed to cover the amorphous glass, and a heater (20) formed on the surface of the crystallized glass, An oxygen sensor comprising a gas diffusion hole (12) communicating with the filling material.