Oxygen sensor

• US 4,466,880 A
• Filed: 09/17/1982
• Issued: 08/21/1984
• Est. Priority Date: 09/17/1981
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Torii, Hideo, Okinaka, Hideyuki, Ozawa, Toshio
• Primary Examiner(s): Andrews, R. L.
• Assistant Examiner(s): Chapman, Terryence
• Application Number:
  US06/419,497
• Time in Patent Office: 704 Days
• Field of Search: 204/1 S, 204/428, 204/429
• US Class Current: 204/428
• CPC Class Codes: G01N 27/4077 Means for protecting the electrolyte or the electrodes

Abstract

An oxygen sensor whose sensing element is covered by a cylindrical porous filter cap, prepared by sintering metallic wool such as nickel-chromium alloy wool for protecting the sensing element from damage by mechanical shock and thermal shock due to a high flow pressure of a high temperature gas and for easy determination of sensing response time.

Claims

1. An oxygen gas sensor for use in a high temperature gas flowing at a high speed and for sensing an oxygen concentration in the gas, said sensor comprising:

an oxygen gas sensing element comprising a sensing body and an electrode; and

a hollow cylindrical cap housing said sensing element in the hollow thereof in a manner that said sensing element is spaced from the inner surface of said cylindrical cap so as to expose said electrode in said hollow, said cylindrical cap being self supporting and being formed of a sintered metal wool forming a metal wool web complex porous to said gas, with innumerable small meandering gas paths being formed in said metal wool web complex, whereby said cylindrical cap functions to weaken mechanical shock and thermal shock to said sensing element due to the high flow pressure of the high temperature gas, and also functions to determine the sensing response time of said sensing element with a selected porosity of said metal wool web complex.

2. An oxygen gas sensor according to claim 1, wherein said metal wool is made of an nickel-chromium alloy.

3. An oxygen gas sensor according to claim 1, wherein said metal wool is made of a refractory stainless steel.

4. An oxygen gas sensor according to claim 1, wherein said metal wool is made of nickel.

5. An oxygen gas sensor according to claim 1, which further comprises a hollow cylindrical cover mechanically supporting and housing said cylindrical cap in the hollow thereof in a manner that the outer surface of said cylindrical cap is in direct contact with the inner surface of said cylindrical cover.