Patent ID: 11921079
Assignee: NGK INSULATORS, LTD.
Field: Measurement (Instruments)
Classification: CPC G  Y | IPC G

Claim 7:
8. A gas sensor sensing a sensing target gas component contained in a measurement gas and identifying concentration of said sensing target gas component, said gas sensor comprising:
a sensor element having a central axis and an inlet for said measurement gas on one end portion, and including:
an element base made of an oxygen-ion conductive solid electrolyte;
a heater buried in said element base; and
a porous leading-end protective layer covering a predetermined range of said element base on said one end portion;

a metallic housing within which said sensor element is fixed; and
a metallic protective cover attached to said housing, and surrounding a portion of said sensor element on said one end portion to allow said measurement gas to flow into an interior of said protective cover, wherein
a minimum distance between one of an inner surface of said housing and an inner surface of said protective cover closer to said sensor element and said sensor element is 0.20 mm or more and 0.95 mm or less, said one of said inner surface of said housing and said inner surface of said protective cover closer to said sensor element being parallel to said central axis of the sensor element, and
said one of said inner surface of said housing and said inner surface of said protective cover closer to said sensor element and facing said porous leading-end protective layer in a direction perpendicular to said central axis has an arithmetic average roughness of 5 μm or less.