Method of confirming reception of drops of water and powder used for the method

Abstract

A method of confirming reception of a drop of water has the steps of applying a powder on a surface of a gas sensing element, placing the element in a gas passage so as to expose the surface of the element to the gas passage, causing a measured gas to flow through the gas passage, receiving drops of water included in the measured gas on limited areas of the surface of the element such that the drops of water take out the powder applied on the limited areas from the element, and confirming the reception of the drops of water on the surface of the element. The powder has a melting point or a sublimation temperature equal to or higher than 1000° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a distal portion of a gas sensing element and a water confirming powder of fine particles applied on or attached to a whole surface of the distal portion of the gas sensing element, according to the first embodiment of the present invention;

FIG. 2 is a side view of the distal portion of the gas sensing element after the tentative reception of drops of water;

FIG. 3 is a sectional view taken substantially along line A-A of. FIG. 2; and

FIG. 4 is a view showing a relation between a volume of a drop of water received on a surface of the gas sensing element and a diameter of the drop of water, according to the second embodiment of the present invention.

Claims

1. A method of confirming reception of a drop of water in a gas sensing element for detecting a concentration of a specific component included in a measured gas, comprising the steps of: applying a powder on a surface of the gas sensing element;placing the gas sensing element in a gas passage so as to expose the surface of the gas sensing element to the gas passage;causing the measured gas to flow through the gas passage;receiving a drop of water included in the measured gas on a limited area of the surface of the gas sensing element such that the drop of water takes out the powder from the limited area; andconfirming the reception of the drop of water on the surface of the gas sensing element, based on a trace of the drop of water at which the powder is taken out,wherein the powder has a melting point or a sublimation temperature equal to or higher than 1000° C.

2. The method according to claim 1, further comprising a step of forming the powder having a specific color distinguishable from a color of the surface of the gas sensing element in a temperature range from 100 to 1000° C.

3. The method according to claim 1, further comprising the steps of: forming the powder having a specific color distinguishable from a color of the gas sensing element in a temperature range from 100 to 1000° C. and having the melting point or the sublimation temperature equal to or higher than 1000° C. in circumstances that the powder is exposed to an exhaust gas output from an internal combustion engine; andusing the exhaust gas as the measured gas.

4. The method according to claim 1, further comprising a step of forming fine particles of the powder which are maintained in a solid state without being dissolved by any of water, lubricating oil and fuel oil.

5. The method according to claim 1, further comprising a step of forming fine particles of the powder which are substantially not combined with a material of the gas sensing element in a temperature range lower than the melting point or the sublimation temperature of the powder.

6. The method according to claim 1, further comprising a step of forming fine particles of the powder which have an average diameter distributed in a range from 0.5 μm to 100 μm.

7. The method according to claim 1, further comprising a step of performing heat treatment for the powder at a temperature equal to or higher than 1000° C.

8. The method according to claim 1, further comprising a step of forming fine particles of the powder made of metal or metallic oxide.

9. The method according to claim 1, further comprising a step of forming fine particles of the powder made of at least one of iron oxide, cobalt oxide, titanium oxide, nickel oxide, copper oxide, tungsten oxide, mica, agate, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zirconium, molybdenum, tungsten, iridium, platinum, and gold.

10. The method according to claim 1, further comprising a step of forming a porous layer on the surface of the gas sensing element so as to apply the powder on a surface of the porous layer in the step of applying the powder.

11. The method according to claim 1, further comprising the steps of: forming a surface portion of the gas sensing element made of a ceramic material.

12. The method according to claim 1, wherein the step of confirming the reception of the drop of water includes: measuring a diameter of the drop of water; andestimating a volume of the drop of water from the diameter.

13. A water confirming powder which is applied on a surface of a gas sensing element for detecting a concentration of a specific component included in a measured gas, characterized in that the water confirming powder is adapted to be taken out from a limited area of the surface of the gas sensing element in response to a reception of a drop of water included in the measured gas on the limited area so as to obtain a confirmative trace of receiving the drop of water, and the water confirming powder has a melting point or a sublimation temperature equal to or higher than 1000° C.

14. The powder according to claim 13, wherein the water confirming powder has a specific color in a temperature range from 100 to 1000° C., and the specific color is distinguishable from a color of the gas sensing element.

15. The powder according to claim 13, wherein the measured gas is formed of an exhaust gas output from an internal combustion engine, the water confirming powder has a specific color in a temperature range from 100 to 1000° C. and the melting point or the sublimation temperature equal to or higher than 1000° C. in circumstances that the water confirming powder is exposed to the exhaust gas.

16. The powder according to claim 13, wherein the water confirming powder has fine particles maintained in a solid state without being dissolved by any of water, lubricating oil and fuel oil.

17. The powder according to claim 13, wherein the water confirming powder has fine particles which substantially are not combined with a material of the gas sensing element in a temperature range lower than the melting point or the sublimation temperature of the powder.

18. The powder according to claim 13, wherein the water confirming powder has fine particles having an average diameter distributed in a range from 0.5 μm to 100 μm.

19. The powder according to claim 13, wherein heat treatment is performed for the water confirming powder at a temperature equal to or higher than 1000° C.

20. The powder according to claim 13, wherein the water confirming powder has fine particles made of metal or metallic oxide.

21. The powder according to claim 13, wherein the water confirming powder has fine particles made of at least one of iron oxide, cobalt oxide, titanium oxide, nickel oxide, copper oxide, tungsten oxide, mica, agate, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zirconium, molybdenum, tungsten, iridium, platinum, and gold.