# US 12,007,353 B2 · Method for producing gas sensor element, gas sensor element, and gas sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,007,353 B2 - Document ID: US12007353B2 - Status: Granted - Kind: B2 - Application number: 17/392,368 - Filed: 2021-08-03 - Published: 2022-02-17 - Granted: 2024-06-11 - Earliest claimed: 2020-08-11 - Assignees: Niterra Co., Ltd. - Applicants: Ngk Spark Plug Co., Ltd. - Inventors: Yuki Hanaki; Suguru Kyomoto; Kaoru Osaki; Kotaro Ueda; Masaki Nakagawa - Web page: https://patentgrep.com/patent/US12007353B2 ## CPC - C23C 24/08: by application of heat or pressure and heat (C23C24/04 takes precedence) - G01N 27/409: Oxygen concentration cells - B05D 1/18: performed by dipping - B05D 1/38: with intermediate treatment (intermediate treatment per se B05D3/00) - B05D 3/007: {After-treatment} - B05D 7/534: {the first layer being let to dry at least partially before applying the second layer (B05D7/538 takes precedence)} - G01N 27/4077: {Means for protecting the electrolyte or the electrodes} - B05D 3/12: by mechanical means - B05D 7/542: {the two layers being cured or baked together} - B05D 2401/20: Aqueous dispersion or solution - G01N 27/41: Oxygen pumping cells - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02) ## Abstract A method for producing a gas sensor element, for covering a detection portion (150) by an inner protection layer (21) and an outer protection layer (22), including: a first dipping step of dipping the gas sensor element into a first slurry S1 for the inner protection layer, to form a first coating film (700) on a front end surface (100c) and a peripheral surface (100d); a drying step of drying and solidifying the first coating film; a second dipping step of dipping, without removing the first coating film, the gas sensor element into a second slurry S2 for the outer protection layer, to form a second coating film (800) on a surface of the solidified first coating film; and a scraping-off step of performing scraping-off on the second coating film so as not to scrape-off the first coating film, to remove a part of the second coating film. ## Claims ### Claim 1 A method for producing a gas sensor element extending in a direction of an axial line thereof and having a detection portion disposed on a front end side thereof, the detection portion being covered by, as a porous protection layer, an inner protection layer that is porous and an outer protection layer that is porous and that has a porosity different from a porosity of the inner protection layer, in this order, the method comprising: a first dipping step of dipping the front end side of the gas sensor element into a first slurry for the inner protection layer, to form a first coating film made of the first slurry on a front end surface and a peripheral surface of the gas sensor element; a drying step of drying and solidifying the first coating film; a second dipping step of dipping, without removing the first coating film, the front end side of the gas sensor element into a second slurry for the outer protection layer, to form a second coating film made of the second slurry on an entirety of a surface of the solidified first coating film; and a scraping-off step of performing scraping-off on the second coating film so as not to scrape-off the solidified first coating film, to remove a part of the second coating film. ### Claim 2 (depends on 1) The method for producing the gas sensor element as claimed in claim 1, wherein the scraping-off step is performed such that a surface of the second coating film having been subjected to the scraping-off becomes a flat surface. ### Claim 3 (depends on 1) The method for producing the gas sensor element as claimed in claim 1, wherein the scraping-off step includes: a peripheral surface scraping-off step of scraping-off and removing a peripheral part of the second coating film; and a front end surface scraping-off step of scraping-off and removing part of a front end side of the second coating film, and the front end surface scraping-off step being performed after the peripheral surface scraping-off step. ### Claim 4 (depends on 2) The method for producing the gas sensor element as claimed in claim 2, wherein the scraping-off step includes: a peripheral surface scraping-off step of scraping-off and removing a peripheral part of the second coating film; and a front end surface scraping-off step of scraping-off and removing part of a front end side of the second coating film, and the front end surface scraping-off step being performed after the peripheral surface scraping-off step. ### Claim 5 A gas sensor element extending in a direction of an axial line thereof and having a plate shape that has opposing main surfaces, the gas sensor element comprising: a detection portion at a front end side thereof; and a porous protection layer configured to cover the detection portion, wherein the porous protection layer comprises an inner protection layer and an outer protection layer that is porous, the outer protection layer having a porosity different from a porosity of the inner protection layer, and that covers the inner protection layer, the inner protection layer has a maximum thickness region along the direction of the axial line, and has a reduced thickness from the region of maximum thickness toward a front end side and a rear end side of the inner protection layer, the outer protection layer has a flat front end surface and flat side surfaces, and when viewed in a direction perpendicular to the main surfaces, a rear end edge on a radially outermost side of the outer protection layer has a shape in which a center portion of the rear end edge in a width direction of the gas sensor element is recessed to the front end side with respect to a rearmost end. ### Claim 6 (depends on 5) A gas sensor, comprising: the gas sensor element according to claim 5; a metal shell which holds the gas sensor element; and a protector mounted to a front end portion of the metal shell. ### Claim 7 (depends on 6) The gas sensor according to claim 6, wherein the protector covers a front end portion of the gas sensor element, protruding from a front end of the metal shell, and has a plurality of gas introduction holes.