Method for manufacturing a gas sensor
AssigneeDenso Corporation
InventorsYukio Ohba, Akira Nishimatsu
Life of this patent
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Abstract
A hardened powder ring, being a hardened block of talc powder, is inserted into an annular end space between a housing and a sensing element. A pushing member presses and crashes the hardened powder ring into talc powder, thereby stuffing the talc powder into the annular end space. An inner radius rp and an outer radius Rp of the pushing member have the relationship 0.275 mm≦rp−Re≦0.375 mm and 0.15 mm≦rh−Rp≦0.25 mm with respect to an outer radius Re of the sensing element and an inner radius rh of the housing. A press portion of pushing member has an inner curved surface having a curvature radius of 0.3˜0.4 mm and an outer curved surface having a curvature radius of 0.3˜0.5 mm.
Claims10
A method for manufacturing a gas sensor having a tubular housing and a sensing element disposed in said housing, comprising:
- a step of inserting said sensing element into said tubular housing from a rear end toward a front end of said housing, said sensing element having a flange portion protruding radially outward from an outer surface thereof, and said housing having an inner cylindrical stepped portion protruding radially inward from an inner cylindrical surface thereof;
- a step of placing said flange portion of said sensing element on said inner cylindrical stepped portion of said housing;
- a step of inserting a hardened powder ring into an annular end space defined between the inner cylindrical surface of said housing and the outer surface of said sensing element, said hardened powder ring being a hardened block of inorganic powder configured into a ring shape;
- a step of pressing said hardened powder ring toward the front end of said housing by a tubular pushing member and crushing said hardened powder ring into inorganic powder by said tubular pushing member so that said annular end space is stuffed by the inorganic powder;
- wherein the following relationship is satisfied
- 0.275 mm≦rp−Re≦0.375 mm,
- and
- 0.15 mm≦rh−Rp≦0.25 mm,
- where rp represents an inner radius of said pushing member, Rp represents an outer radius of said pushing member, rh represents an inner radius of said housing, and Rθ represents an outer radius of said sensing element at a portion substantially defining said annular end space.
A method for manufacturing a gas sensor having a tubular housing and a sensing element disposed in said housing, comprising:
- a step of inserting said sensing element into said tubular housing from a rear end toward a front end of said housing, said sensing element having a flange portion protruding radially outward from an outer surface thereof, and said housing having an inner cylindrical stepped portion protruding radially inward from an inner cylindrical surface thereof;
- a step of placing said flange portion of said sensing element on said inner cylindrical stepped portion of said housing;
- a step of inserting a hardened powder ring into an annular end space defined between the inner cylindrical surface of said housing and the outer surface of said sensing element, said hardened powder ring being a hardened block of talc powder configured into a ring shape;
- a step of inserting a packing ring in said annular end space to dispose said packing ring on said hardened powder ring, said packing ring being made of an inorganic member different from said hardened powder ring,
- a step of inserting a guide into a rear end of said sensing element, said guide being disposed inside an annular pushing member and slidable in an axial direction of said pushing member,
- a step of sliding said pushing member along said guide toward the front end of said housing, thereby pressing said hardened powder ring via said packing ring by said pushing member and crushing said hardened powder ring into talc powder by said tubular pushing member so that said annular end space is stuffed by the talc powder;
- wherein the following relationship is satisfied
- 0.275 mm≦rp−Re0.375 mm,
- and
- 0.15 mm≦rh−Rp≦0.25 mm,
- where rp represents an inner radius of said pushing member, Rp represents an outer radius of said pushing member, rh represents an inner radius of said housing, and Re represents an outer radius of said sensing element at a portion substantially defining said annular end space, and
- said pushing member has a press portion consisting of a flat surface, an inner curved surface having a curvature radius of 0.3˜0.4 mm, and an outer curved surface having a curvature radius of 0.3˜0.5 mm, said inner curved surface being formed at a radially inner end of said press portion while said outer curved surface being formed at a radially outer end of said press portion.
Dependencies are inferred from the claim text.