Gas sensor, gas sensor installation structure, and method for installing gas sensor

A gas sensor comprising a sensor element which has a function of detecting a specific gas component, a housing which contains the sensor element therein and has a sealing surface which forms a sealing section together with an installation section at the front in a direction in which the sensor element is inserted, and a rotating member which has a thread section which is formed outside the rotating member and is to be screwed into the installation section and can be rotated concentrically with a center axis of the housing,

• wherein release torque of the rotating member at 850° C. (1123 K) in the case where the gas sensor is installed in the installation section by screwing the rotating member into the installation section is 9 N·m or more, and
• wherein an estimated value X3 of a gap formed between the sealing surface and the installation section at 850° C. (1123 K) calculated according to the following equation (3) is 31 μm or less:
• X3(μm)={(L1×α1)−(L4×α4)−(L5×α5)}×1123 (3)
• wherein X3 represents an estimated value (μm) of the gap, L1 represents a length (μm) from the sealing surface to a top end of the installation section, L4 represents a length (μm) from a bottom end to a top end of the thread section, L5 represents a length (μm) from the sealing surface to the bottom end of the thread section, α1 represents a coefficient of thermal expansion (×10−6/° C.) of the installation section, α4 represents a coefficient of thermal expansion (×10−6/° C.) of the rotating member, and ax represents a coefficient of thermal expansion (×10−6/° C.) of the housing.

A gas sensor installation structure in which a gas sensor comprising a sensor element which has a function of detecting a specific gas component, and a housing which contains the sensor element therein and includes a thread section which is formed outside the housing and is screwed into a specific installation section and a sealing surface which forms a sealing section together with the installation section at a position deeper than the thread section in a direction in which the sensor element is inserted, is installed by screwing the housing into the installation section,

• wherein release torque at 850° C. (1123 K) is 9 N·m or more, and
• wherein an estimated value X5 of a gap formed between the sealing surface and the installation section at 850° C. (1123 K) calculated according to the following equation (5) is 31 μm or less:
• X5(μm)={(L1×α1)−(L2×α2)}×1123 (5)
• wherein X5 represents an estimated value (μm) of the gap, L1 represents a length (μm) from the sealing surface to a top end of the installation section, L2 represents a length (μm) from the sealing surface to a top end of the thread section, α1 represents a coefficient of thermal expansion (×10−6/° C.) of the installation section, and α2 represents a coefficient of thermal expansion (×10−6/° C.) of the housing.

A gas sensor installation structure in which a gas sensor comprising a sensor element which has a function of detecting a specific gas component, a housing which contains the sensor element therein and has a sealing surface which forms a sealing section together with an installation section at the front in a direction in which the sensor element is inserted, and a rotating member which has a thread section which is formed outside the rotating member and is screwed into the installation section and can be rotated concentrically with a center axis of the housing, is installed in the installation section by screwing the rotating member into the installation section,

• wherein release torque of the rotating member at 850° C. (1123 K) is 9 N·m or more, and
• wherein an estimated value X7 of a gap formed between the sealing surface and the installation section at 850° C. (1123 K) calculated according to the following equation (7) is 31 μm or less:
• X7(μm)={(L1×α1)−(L4×α4)−(L5×α5)}×1123 (7)
• wherein X7 represents an estimated value (μm) of the gap, L1 represents a length (μm) from the sealing surface to a top end of the installation section, L4 represents a length (μm) from a bottom end to a top end of the thread section, L5 represents a length (μm) from the sealing surface to the bottom end of the thread section, α1 represents a coefficient of thermal expansion (×10−6/° C.) of the installation section, α4 represents a coefficient of thermal expansion (×10−6/° C.) of the rotating member, and α5 represents a coefficient of thermal expansion (×10−6/° C.) of the housing.

A method for installing gas sensor comprising installing a gas sensor which comprises a sensor element which has a function of detecting a specific gas component, a housing which contains the sensor element therein and has a sealing surface which forms a sealing section together with an installation section at the front in a direction in which the sensor element is inserted, and a rotating member which has a thread section which is formed outside the rotating member and is screwed into the installation section and can be rotated concentrically with a center axis of the housing, in the installation section by screwing the rotating member,

• wherein the rotating member is screwed so that release torque at 850° C. (1123 K) is 9 N·m or more and an estimated value X11 of a gap formed between the sealing surface and the installation section at 850° C. (1123 K) calculated according to the following equation (11) is 31 μm or less:
• X11(μm)={(L1×α1)−(L4×α4)−(L5×α5)}×1123 (11)
• wherein X11 represents an estimated value (μm) of the gap, L1 represents a length (μm) from the sealing surface to a top end of the installation section, L4 represents a length (μm) from a bottom end to a top end of the thread section, L5 represents a length (μm) from the sealing surface to the bottom end of the thread section, α1 represents a coefficient of thermal expansion (×10−6/° C.) of the installation section, α4 represents a coefficient of thermal expansion (×10−6/° C.) of the rotating member, and α5 represents a coefficient of thermal expansion (×10−6/° C.) of the housing.