US 11,913,900 B2
Sensor element
Yusuke Watanabe, Nagoya (JP); Mika Kai, Nagoya (JP); Ryo Onishi, Nagoya (JP); and Saki Suzuki, Nagoya (JP)
Assigned to NGK INSULATORS, LTD., Nagoya (JP)
Filed by NGK INSULATORS, LTD., Nagoya (JP)
Filed on May 10, 2022, as Appl. No. 17/740,789.
Application 17/740,789 is a division of application No. 16/522,720, filed on Jul. 26, 2019, granted, now 11,360,043.
Claims priority of application No. 2018-146710 (JP), filed on Aug. 3, 2018.
Prior Publication US 2022/0268727 A1, Aug. 25, 2022
Int. Cl. G01N 27/41 (2006.01); G01N 27/407 (2006.01)
CPC G01N 27/41 (2013.01) [G01N 27/4077 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A sensor element for a gas sensor detecting a predetermined gas component in a measurement gas, said sensor element comprising:
an element base including:
an elongated planar ceramic body made of an oxygen-ion conductive solid electrolyte, and having a gas inlet at one end portion thereof;
at least one internal chamber located inside said ceramic body, and communicating with said gas inlet under predetermined diffusion resistance;
at least one electrochemical pump cell including an outer pump electrode located on an outer surface of said ceramic body, an inner pump electrode located to face said at least one internal chamber, and a solid electrolyte located between said outer pump electrode and said inner pump electrode, said at least one electrochemical pump cell pumping in and out oxygen between said at least one internal chamber and an outside;
a heater buried in a predetermined range on a side of said one end portion of said ceramic body; and
a first region in which water-induced cracking is to be prevented defined in said element base on the side of said one end portion;
a first leading-end protective layer being porous, and surrounding a first range at least including a leading end surface and said first region of said element base on the side of said one end portion; and
a second leading-end protective layer being porous, having a larger porosity than said first leading-end protective layer, and located on four side surfaces and four corners of said element base at least in said first range, wherein
an end portion of said first leading-end protective layer opposite said one end portion is a fixed portion in which said first leading-end protective layer is fixed to said second leading-end protective layer,
said first leading-end protective layer is further fixed to said leading end surface of said element base on the side of said one end portion, and
a single heat insulating space is interposed between said first leading-end protective layer and said four side surfaces and four corners of said element base to surround said four side surfaces and four corners of said element base and said second leading-end protective layer in said first range surrounded by said first leading-end protective layer.