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

• US 20030188568A1
• Filed: 03/25/2003
• Published: 10/09/2003
• Est. Priority Date: 03/29/2002
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Lee, Sang Jae, Kurachi, Hiroshi, Ikoma, Nobukazu
• Granted Patent: US 6,796,175 B2
• Time in Patent Office: Days
• US Class Current: 73/31.05
• CPC Class Codes: G01N 27/4074 for detection of gases other than oxygen
• CPC Class Codes: G01N 33/0037 for NOx
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A gas sensor 10 includes a sensor element 1 having a specific function, and a housing 5 containing the sensor element 1 therein and including a specific thread section 2 and a sealing surface 4 which forms a sealing section 3 together with an installation section at a position deeper than the thread section 2 in a direction in which the sensor element 1 is inserted. Release torque at 850° C. (1123 K) in the case where the housing is screwed into the installation section is 9 N·m or more, and an estimated value X₁ of a gap formed between the sealing surface 4 and the installation section at 850° C. (1123 K) calculated according to a specific equation is 31 μm or less.

Claims

1. 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 to be 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,

wherein release torque at 850°

C. (1123 K) in the case where the housing is screwed into the installation section is 9 N·

m or more, and

wherein an estimated value X₁ of a gap formed between the sealing surface and the installation section at 850°

C. (1123 K) calculated according to the following equation (1) is 31 μ

m or less;

X₁(μ

m)={(L₁×

α

₁)−

(L₂×

α

₂)}×

1123 

 

(1)

wherein X₁ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₂ represents a length (μ

m) from the sealing surface to a top end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, and α

₂ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.

2. The gas sensor according to claim 1, wherein a gasket is provided to the sealing surface and an estimated value X₂ of the gap is calculated according to the following equation (2):

X₂(μ

m)={(L₁×

α

₁)−

(L₂×

α

₂)−

(L₃×

α

₃)}×

1123 

 

(2)

wherein X₂ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₂ represents a length (μ

m) from the sealing surface to a top end of the thread section, L₃ represents a thickness (μ

m) of the gasket, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₂ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing, and α

₃ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the gasket.

3. The gas sensor according to claim 2, wherein a material for the gasket is at least one material selected from the group consisting of 430 SS, 304 SS, 310 SS, 316 SS, and 321 SS.

8. The gas sensor according to claim 1, wherein a material for the housing is at least one material selected from the group consisting of 430 SS, 304 SS, 310 SS, 316 SS, and 321 SS.

4. 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 μ

m or less;

X₃(μ

m)={(L₁×

α

₁)−

(L₄×

α

₄)−

(L₅×

α

₅)}×

1123 

 

(3)

wherein X₃ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₄ represents a length (μ

m) from a bottom end to a top end of the thread section, L₅ represents a length (μ

m) from the sealing surface to the bottom end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₄ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the rotating member, and ax represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.

5. The gas sensor according to claim 4, wherein a gasket is provided to the sealing surface and an estimated value X₄ of the gap is calculated according to the following equation (4):

X₄(μ

m)={(L₁×

α

₁)−

(L₃×

α

₃)−

(L₄×

α

₄)−

(L₅×

α

₅)}×

1123 

 

(4)

wherein X₄ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₃ represents a thickness (μ

m) of the gasket, L₄ represents a length (μ

m) from a bottom end to a top end of the thread section, L₅ represents a length (μ

m) from the sealing surface to the bottom end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₃ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the gasket, α

₄ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the rotating member, and α

₅ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.

6. The gas sensor according to claim 5, wherein a material for the gasket is at least one material selected from the group consisting of 430 SS, 304 SS, 310 SS, 316 SS, and 321 SS.

7. The gas sensor according to claim 4, wherein a material for the rotating member is at least one material selected from the group consisting of 430 SS, 304 SS, 310 SS, 316 SS, and 321 SS.

9. 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 μ

m or less;

X₅(μ

m)={(L₁×

α

₁)−

(L₂×

α

₂)}×

1123 

 

(5)

wherein X₅ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₂ represents a length (μ

m) from the sealing surface to a top end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, and α

₂ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.

10. The gas sensor installation structure according to claim 9, wherein the sealing section is formed through a gasket and an estimated value X₆ of the gap is calculated according to the following equation (6):

X₆(μ

m)={(L₁×

α

₁)−

(L₂×

α

₂)−

(L₃×

α

₃)}×

1123 

 

(6)

wherein X₆ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₂ represents a length (μ

m) from the sealing surface to a top end of the thread section, L₃ represents a thickness (μ

m) of the gasket, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₂ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing, and α

₃ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the gasket.

11. The gas sensor installation structure according to claim 10, wherein a material for the gasket is at least one material selected from the group consisting of 430 SS, 304 SS, 310 SS, 316 SS, and 321 SS.

16. The gas sensor installation structure according to claim 9, wherein a material for the housing is at least one material selected from the group consisting of 430 SS, 304 SS, 310 SS, 316 SS, and 321 SS.

12. 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 μ

m or less;

X₇(μ

m)={(L₁×

α

₁)−

(L₄×

α

₄)−

(L₅×

α

₅)}×

1123 

 

(7)

wherein X₇ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₄ represents a length (μ

m) from a bottom end to a top end of the thread section, L₅ represents a length (μ

m) from the sealing surface to the bottom end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₄ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the rotating member, and α

₅ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.

13. The gas sensor installation structure according to claim 12, wherein the sealing section is formed through a gasket and an estimated value X₈ of the gap is calculated according to the following equation (8):

X₈(μ

m)={(L₁×

α

₁)−

(L₃×

α

₃)−

(L₄×

α

₄)−

(L₅×

α

₅)}×

1123 

 

(8)

wherein X₈ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₃ represents a thickness (μ

m) of the gasket, L₄ represents a length (μ

m) from a bottom end to a top end of the thread section, L₅ represents a length (μ

m) from the sealing surface to the bottom end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₃ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the gasket, α

₄ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the rotating member, and α

₅ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.

14. The gas sensor installation structure according to claim 13, wherein a material for the gasket is at least one material selected from the group consisting of 430 SS, 304 SS, 310 SS, 316 SS, and 321 SS.

15. The gas sensor installation structure according to claim 12, wherein a material for the rotating member is at least one material selected from the group consisting of 430 SS, 304 SS, 310 SS, 316 SS, and 321 SS.

17. 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, 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, in the installation section by screwing the housing,

wherein the housing is screwed so that release torque at 850°

C. (1123 K) is 9 N·

m or more and an estimated value X₉ of a gap formed between the sealing surface and the installation section at 850°

C. (1123 K) calculated according to the following equation (9) is 31 μ

m or less;

X₉(μ

m)={(L₁×

α

₁)−

(L₂×

α

₂)}×

1123 

 

(9)

wherein X₉ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₂ represents a length (μ

m) from the sealing surface to a top end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, and α

₂ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.

18. The method for installing gas sensor according to claim 17, wherein the sealing section is formed through a gasket and the housing is screwed so that an estimated value X₁₀ of the gap calculated according to the following equation (10) is 31 μ

m or less;

X₁₀(μ

m)={(L₁×

α

₁)−

(L₂×

α

₂)−

(L₃×

α

₃)}×

1123 

 

(10)

wherein X₁₀ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₂ represents a length (μ

m) from the sealing surface to a top end of the thread section, L₃ represents a thickness (μ

m) of the gasket, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₂ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing, and α

₃ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the gasket.

19. 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 μ

m or less;

X₁₁(μ

m)={(L₁×

α

₁)−

(L₄×

α

₄)−

(L₅×

α

₅)}×

1123 

 

(11)

wherein X₁₁ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₄ represents a length (μ

m) from a bottom end to a top end of the thread section, L₅ represents a length (μ

m) from the sealing surface to the bottom end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₄ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the rotating member, and α

₅ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.

20. The method for installing gas sensor according to claim 19, wherein the sealing section is formed through a gasket and the housing is screwed so that an estimated value X₁₂ of the gap calculated according to the following equation (12) is 31 μ

m or less;

X₁₂(μ

m)={(L₁×

α

₁)−

(L₃×

α

₃)−

(L₄×

α

₄)−

(L₅×

α

₅)}×

1123 

 

(12)

wherein X₁₂ represents an estimated value (μ

m) of the gap, L₁ represents a length (μ

m) from the sealing surface to a top end of the installation section, L₃ represents a thickness (μ

m) of the gasket, L₄ represents a length (μ

m) from a bottom end to a top end of the thread section, L₅ represents a length (μ

m) from the sealing surface to the bottom end of the thread section, α

₁ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the installation section, α

₃ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the gasket, α

₄ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the rotating member, and α

₅ represents a coefficient of thermal expansion (×

10<sup>−

6</sup>/°

C.) of the housing.