Oxygen concentration detector

• US 5,707,504 A
• Filed: 01/18/1996
• Issued: 01/13/1998
• Est. Priority Date: 01/19/1995
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Jyouno, Kouji, Watanabe, Isao
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US08/588,327
• Time in Patent Office: 726 Days
• Field of Search: 204/428, 204/429, 204/424
• US Class Current: 204/428
• CPC Class Codes: G01N 27/4077 Means for protecting the electrolyte or the electrodes

Abstract

An oxygen concentration detector comprises a housing 10, a detecting element 12 with a built-in heater, a holder 2 made of an insulating ceramic and interposed between the housing and the detecting element 12, and a protecting cover 16 fixed to the housing 10 in such a manner as to cover the outside of the detecting element 12. The protecting cover 16 has gas inlets 160, and a protecting cylinder 21 formed by extending the holder 2 is interposed between the detecting element 12 and the protecting cover 16.

Claims

1. An oxygen concentration detector comprising:

a) an oxygen concentration detecting element having an elongated shape with first and second ends, said element having a detecting portion and a heater on a side of said first end of said element;

b) a housing having an outer shape defining a coupling structure, said housing accepting said element inside thereof, the first end of said element protruding from said housing;

c) an insulating ceramic holder interposed between said housing and said element for holding said element at an intermediate portion of the element, said holder being supported by said housing; and

d) a protecting cover mounted on said housing and extending toward said first end of said element in the longitudinal direction of said element, said protecting cover being spaced apart from and covering the outside of said element, said protecting cover having gas inlet ports at locations corresponding to said element in the longitudinal direction of said element;

wherein said holder has between said element and said protecting cover an extended portion thereof spaced apart from and covering the outside of said element, said holder covering at last said gas inlet ports of said protecting cover in the longitudinal direction of said element, said holder thus forming a protecting cylinder for said element.

2. An oxygen concentration detector according to claim 1, wherein said holder has an open end.

3. An oxygen concentration detector according to claim 1 wherein said holder has openings, through which a gas to be measured flows, and said openings are so disposed as not to oppose said gas inlet ports of said protecting cover.

4. An oxygen concentration detector according to claim 1, wherein said protecting cover has a bottom plate.

5. An oxygen concentration detector according to claim 4, wherein said bottom plate of said protecting cylinder has an opening.

6. An oxygen concentration detector according to claim 4, wherein said bottom plate of said protecting cylinder protrudes from the cover bottom plate of said protecting cover, and an opening is formed between said protecting cylinder and said cover bottom plate.

7. An oxygen concentration detector according to claim 4, wherein said bottom plate of said protecting cylinder has a thick protruding portion smaller than the outer diameter of said bottom plate, said thick protruding portion having an opening, the lower end surface of said thick protruding portion exists on the same plane as said cover bottom plate of said protecting cover or protrudes from said cover bottom plate, and an opening is disposed between said thick protruding portion and said cover bottom plate.

8. An oxygen concentration detector according to claim 4, wherein said bottom plate of said protecting cylinder is positioned inside said cover bottom plate of said protecting cover, said bottom plate of said protecting cylinder has an opening, and said cover bottom plate of said protecting cover has an opening.

9. An oxygen concentration detector according to claim 1, wherein said protecting cylinder has openings, through which the gas to be measured passes, closer to said second end of said element than to an end of said housing.

10. An oxygen concentration detector according to claim 1, wherein the lower end portion of said protecting cylinder has an open end, and said protecting cover has a cover bottom plate with an opening.

11. An oxygen concentration detector according to claim 1, wherein said protecting cylinder has an open end, said protecting cover has a cover bottom plate with an opening, and said opening of said cover bottom plate is bent at the end portion thereof in such a manner as to face said open end at the end of said protecting cylinder.

12. An oxygen concentration detector according to claim 1, wherein said detecting element comprises:

a planer solid electrolyte;

a gas-to-be-measured side electrode disposed on a first surface of said planer solid electrolyte;

a reference gas side electrode disposed on a second surface opposite to said first surface of said planer solid electrolyte;

a planer insulator laminated with said planer solid electrolyte, said planer insulator forming a space as a reference gas chamber between said planer solid electrolyte and said planer insulator, said space being closed at a first end portion thereof on the side of said detection side and being open at a second end portion thereof; and

a heater formed on said planer insulator on the opposite side to said planer solid electrolyte.

13. An oxygen concentration detector according to claim 12, wherein said detecting element has a flange portion between said first and second ends thereof, and said holder holds said detecting element at said flange portion.

14. An oxygen concentration detector according to claim 1, wherein said detecting element comprises a solid electrolyte having a shape of a cylinder with a closed end, a gas-to-be measured side electrode on an outer surface of said cylinder, a reference gas side electrode on an inner surface of said cylinder, and a heater inside said cylinder.

15. An oxygen concentration detector according to claim 1, wherein said housing has an open end.

16. An oxygen concentration detector comprising:

a) an oxygen concentration detecting element having an elongated shape with first and second ends said element having a detecting portion and a heater on a side of said first end of said element;

b) a housing having an outer shape defining a coupling structure, said housing accepting said element inside thereof, the first end of said element protruding from said housing;

c) an insulating ceramic holder interposed between said housing and said element for holding said element at an intermediate portion of the element, said holder being supported by said housing; and

d) a protecting cover mounted on said housing and extending toward said first end of said element in the longitudinal direction of said element said protecting cover being spaced apart from and covering the outside of said element, said protecting cover having gas inlet ports at locations corresponding to said element in the longitudinal direction of said element;

wherein said housing has between said element and said protecting cover an extended portion thereof spaced apart from and covering the outside of said element, said housing covering at least said gas inlet ports of said protecting cover in the longitudinal direction of said element, said housing thus forming a protecting cylinder for said element.