Oxygen sensor

• US 4,526,672 A
• Filed: 03/23/1984
• Issued: 07/02/1985
• Est. Priority Date: 03/23/1984
• Status: Expired due to Fees

• Current Assignee: Larry T. Reed
• Original Assignee: Axia Incorporated (Axia Acquisition Holding Corp.)
• Inventors: Reed, Larry T.
• Primary Examiner(s): Tung, T.
• Application Number:
  US06/592,626
• Time in Patent Office: 466 Days
• Field of Search: 204/421, 204/424-429, 174/74 R, 174/75 R, 174/75 F
• US Class Current: 204/428
• CPC Class Codes: F01N 13/008 Mounting or arrangement of exhaust sensors in or on exhaust apparatus sensor arrangements for engine control F02D41/1439
• CPC Class Codes: G01N 27/407 for investigating or analysing gases G01N27/411 takes precedence
• CPC Class Codes: G01N 27/4078 Means for sealing the sensor element in a housing

Abstract

An exhaust gas sensor (10) is disclosed which includes a sensor element (12) and a member (48). The member (48) includes a hollow tube (50) and a seal disk (58). The seal disk (58) is urged into sealing engagement with an annular surface (14) on the sensor element (12) to prevent exhaust gas from entering the interior (26) of the sensor element (12). The inner electrode (22) of the sensor element (12) extends to the annular surface (14) in an annular ring (88). The seal disk (58) is permitted to contact the inner electrode (22) about the entire periphery of the ring (88).

Claims

1. An exhaust gas sensor for sensing the oxygen content in an exhaust system relative to the oxygen content of air, comprising:

a solid electrolyte sensor element having a generally conical shape with one closed end and one open end surrounded by an annular surface, the sensor element having an outer electrode formed on the exterior surface of the sensor element and an inner electrode formed on the interior surface of the sensor element extending to the annular surface;

a housing for supporting said sensor element and having a conical shoulder;

an electrically conductive seal for sealing engagement between the conical shoulder on the housing and the outer electrode of the sensor element;

a member forming an enclosed elongate hollow tube and a sealing disk, both the elongate hollow tube and the sealing disk being electrically conductive, the hollow tube having an opening at the first end thereof and an opening at the second end thereof, the opening at the second end thereof being a notch through the wall of the hollow tube, the hollow tube extending beyond the notch forming a crimping portion having a wire crimped therein to connect the inner electrode of the exhaust gas sensor to the wire, the sealing disk being positioned on the hollow tube adjacent the first end for sealing engagement with the annular surface of the sensor element for insuring that the only gases present in the interior of the sensor element enter the second end of the hollow tube and pass through the hollow tube to the sensor element;

a cover secured to the housing, the second end of the hollow tube extending out of the cover;

means for urging the sealing disk into contact with the inner electrode so that sealing contact is made between the member and the annular surface of the gas sensor and between the conical shoulder of the housing and outer electrode through said electrically conductive seal; and

a vent cap housing secured to the cover with at least one gap between the cover and vent cap housing to admit air into the interior of the vent cap housing, the second end of the hollow tube being within the interior of the vent cap housing with said at least one gap positioned between said second end of the hollow tube and the electrically conductive seal between the housing and the outer electrode to reduce the potential for contamination of the air within the hollow tube with exhaust gas.

2. The exhaust gas sensor of claim 1 wherein said sealing disk contacts the annular surface about the entire periphery thereof to enhance the electrical connection between the sealing disk and the inner electrode.

3. The exhaust gas sensor of claim 1 wherein the inner electrode in the sensor element extends to define an annular ring at the annular surface of the sensor element, the seal disk of said member being positioned for electrical contact with the inner electrode about the entire circumference thereof.

4. The exhaust gas sensor of claim 1 wherein said means for urging comprises at least one belleville washer.

5. An exhaust gas sensor for sensing the oxygen content in an exhaust system relative to the oxygen content of air, comprising:

a solid electrolyte sensor element having a generally conical shape with one closed end and one open end surrounded by an annular surface, the sensor element having an outer electrode formed on the exterior surface of the sensor element and an inner electrode formed on the interior surface of the sensor element extending to the annular surface, said sensor element having a conical shoulder;

a housing for supporting said sensor element and having a conical shoulder, said housing further having a threaded portion and an inwardly turned lip;

an electrically conductive seal for sealing engagement between the conical shoulder on the housing and the sensor element;

a gas deflector for engagement with the lip on said housing, said gas deflector having apertures therein to permit the exhaust gases to contact the exterior surface of the sensor element;

a member forming an enclosed elongate hollow tube having a through aperture opening at first and second ends and a sealing disk, both the hollow tube and sealing disk being electrically conductive, the sealing disk being positioned along the hollow tube adjacent the first end for simultaneous sealing engagement with the annular surface of the sensor element and electrical contact with the inner electrode, the opening of said aperture at the second end of the hollow tube being formed by a notch in the wall of the hollow tube, a portion of the hollow tube forming a crimping portion to crimp a wire therein to connect the inner electrode of the exhaust gas sensor to the wire the crimping portion being crimped to the wire without interfering with the opening through the notch;

a ceramic insulator having a hollow core, one end of the ceramic insulator contacting the surface of the sealing disk opposite the annular surface of the sensor element;

a cover secured to said housing, the second end of the hollow tube extending out of the cover;

means for acting between the housing and the ceramic insulator to urge the ceramic insulator into contact with the sealing disk so that sealing contact is made between the member and the annular surface of the sensor element and between the conical shoulders of the sensor element and housing through said electrically conductive seal; and

a vent cap housing secured to the cover, at least one gap being formed between the cover and vent cap housing to permit air onto the interior of the vent cap housing, the second end of the hollow tube being within the vent cap housing with said gap being between the second end of the hollow tube and the electrically conductive seal to reduce the potential for exhaust gas entering the hollow tube, exhaust gas leaking past the conductive seal being vented through said at least one gap.

6. The exhaust gas sensor of claim 5 wherein said means for acting between the housing and the ceramic insulator comprises at least one belleville washer.