JP2016001105A - Gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor which, while preventing the breakage of the flange part of an insulator due to the load applied thereto when a sealing member is compressed, makes it possible to reduce the diameter of the flange part.SOLUTION: A gas sensor 1 comprises a sensor element 10, an insulator 20, a housing 30, and a sealing member 40. The insulator 20 is formed in shape of a cylinder so as to hold the sensor element 10 in the inside 20a thereof, and has a flange part 21 formed in the shape of a convex on an outer circumferential face 20b. The housing 30 holds the sensor element 10 and the insulator 20 inside thereof, and has an annular projection 31 bearing the flange part 21 on an inner wall face 30a. The sealing member 40 is filled and compressed in a space 40a surrounded by the flange part 21, the housing 30, and the insulator 20. When it is assumed that the length in an axial direction Y of the flange part 21 is T, the projection length in a radial direction X of the flange part 21 is W, and the outer diameter of the flange part 21 is D, the value of W/(π×D×T/6) is 0.06 or less.

Description

  The present invention relates to a gas sensor.

  Conventionally, a gas sensor for detecting a specific gas in exhaust gas has been used for air-fuel ratio control of an internal combustion engine such as an automobile. As such a gas sensor, for example, in Patent Document 1, a sensor element including a detection unit that detects a specific gas, an insulator that holds the sensor element, and a substantially cylindrical shape that is formed so as to hold the insulator inside. Housing. A flange portion is formed to project from the outer peripheral surface of the insulator, and an annular inner projecting portion is formed to project from the inner wall of the housing. The diameter of the inner wall of the inner projecting portion of the housing is smaller than the outer diameter of the flange portion of the insulator. The insulator is inserted through the housing, and the flange portion is supported by the inner projecting portion. Between the insulator and the housing, talc as a seal member is filled and compressed by being compressed. This prevents the exhaust gas from leaking between the insulator and the housing. And when compressing a sealing member, the collar part of an insulator will receive the load by the said compression.

JP 2005-326395 A

  Since the gas sensor is provided in a limited space inside an automobile or the like, it is required to reduce the diameter of the gas sensor in order to increase the degree of freedom of installation location. However, simply reducing the diameter of the entire gas sensor has the following problems. That is, when the diameter of the insulator is reduced, the flange portion of the insulator is reduced, so that the stress inside the flange portion caused by a load when compressing the seal member is excessively increased and the flange portion may be damaged. Therefore, there is room for improvement in order to reduce the diameter of the entire gas sensor while preventing breakage of the flange.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a gas sensor capable of reducing the diameter while preventing breakage of the flange portion of the insulator due to a load when the seal member is compressed.

One embodiment of the present invention is formed in a rod shape extending in the axial direction, and a detection unit that detects a specific gas in the measurement gas by being exposed to the measurement gas on the distal end side, and a detection result of the detection unit on the proximal end side A sensor element including an output unit that outputs an output signal according to
An insulator made of a cylindrical insulator having a collar portion that is formed in a cylindrical shape so as to hold the sensor element inside and that protrudes in a convex shape on the outer peripheral surface;
A cylindrical housing that holds the sensor element and the insulator inside, and has an annular protrusion formed annularly on the inner wall surface so as to support the flange portion;
A seal member that fills and compresses a space surrounded by the base end side surface of the flange, the inner wall surface of the housing, and the outer peripheral surface of the insulator, and seals between the insulator and the housing;
In a gas sensor comprising:
The axial length of the flange portion T, a projecting length in the radial direction of the flange portion W, when the outer diameter of the flange portion and is D, in W / (π × D × T 2/6) The gas sensor is characterized in that the stress value per unit load shown is 0.06 or less.

In the gas sensor, the value of the ^{W / (π × D × T} 2/6) is in the 0.06 or less. Thereby, even if the diameter of the gas sensor is reduced, the axial length T (that is, the thickness of the collar portion) of the collar portion is sufficiently secured, so that the stress in the collar portion generated when the seal member is compressed is used. Damage to the buttocks of the insulator is prevented.

  As described above, according to the present invention, it is possible to provide a gas sensor capable of reducing the diameter while preventing breakage of the flange portion of the insulator due to a load when the seal member is compressed.

FIG. 3 is a cross-sectional view of the gas sensor in the first embodiment. The partially expanded view in FIG. The graph which shows the relationship between the thickness of the collar part in Example 1, and the stress value per unit load in a collar part. The graph which shows the relationship between the width | variety of a collar part in Example 1, and the stress value per unit load in a collar part. The graph which shows the relationship between the outer diameter of a collar part in Example 1, and the stress value per unit load in a collar part. FIG. 3 is a schematic diagram for explaining a damage test method according to the first embodiment. Sectional drawing of the gas sensor in Example 2. FIG. Sectional drawing of the gas sensor in Example 3. FIG.

  The gas sensor of the present invention can be used, for example, for air-fuel ratio control of an internal combustion engine such as an automobile.

(Example 1)
A gas sensor according to an embodiment of the present example will be described with reference to FIGS.
The gas sensor 1 of this example includes a sensor element 10, an insulator 20, a housing 30, and a seal member 40.
The sensor element 10 is formed in a rod shape extending in the axial direction Y, is exposed to the gas to be measured on the distal end side Y1, and detects the specific gas in the gas to be measured, and the detector 11 on the proximal end side Y2. And an output unit 12 for outputting an output signal corresponding to the detection result.
The insulator 20 is formed of an insulator having a cylindrical shape so as to hold the sensor element 10 in the interior 20a, and having a flange portion 21 formed in a protruding shape on the outer peripheral surface 20b.
The housing 30 is cylindrical and holds the sensor element 10 and the insulator 20 inside. And it has the cyclic | annular protrusion part 31 formed in cyclic | annular form so that the collar part 21 might be supported by the inner wall surface 30a.
The seal member 40 is filled and compressed into a space 40 a surrounded by the proximal end side surface 21 b of the flange portion 21, the inner wall surface 30 a of the housing 30, and the outer peripheral surface 20 b of the insulator 20, and the insulator 20 and the housing 30 are compressed. The space between them is sealed.
As shown in FIG. 2, the length (hereinafter also referred to as “thickness”) of the flange portion 21 in the axial direction Y is T, and the protruding length (hereinafter also referred to as “width”) of the flange portion 21 in the radial direction X. the W, when the outer diameter of the flange portion 21 is D, the stress value per unit load represented by W / (π × D × T 2/6) is in the 0.06 or less.
The axial direction of the sensor element 10 is Y, and the direction perpendicular to the axial direction Y, that is, the radial direction of the insulator 20 is X.

Hereinafter, the gas sensor 1 of this example will be described in detail.
The gas sensor 1 is attached to an exhaust system of an internal combustion engine in an automobile or the like, and is used for air-fuel ratio control of the internal combustion engine. As shown in FIG. 1, the gas sensor 1 includes a housing 30 that houses the insulator 20 therein. A double-structured gas-side cover 50 to be measured, which includes an outer cover 51 and an inner cover 52, is provided at the front end Y 1 of the housing 30. The measured gas side cover 50 is provided with a measured gas introduction hole 501 through which the measured gas is introduced. The measurement gas side atmosphere 53 is formed inside the inner cover 52 by introducing the measurement gas into the measurement gas side cover 50 from the measurement gas introduction hole 501.

  In addition, an atmosphere side cover 54 is provided on the base end side Y2 of the housing 30. An air introduction hole (not shown) is provided on the outer peripheral surface of the base end side Y <b> 2 of the atmosphere side cover 54. Further, a water repellent filter is provided in the atmosphere introduction hole, and the atmosphere is introduced into the atmosphere side cover 54 through the water repellent filter from the atmosphere introduction hole. An air atmosphere 55 is formed inside.

As shown in FIGS. 1 and 2, the annular protrusion 31 formed on the inner wall surface 30 a of the housing 30 is formed in the entire circumferential direction at a substantially center in the axial direction Y of the inner wall surface 30 a.
And the annular protrusion part 31 is comprised so that the collar part 21 formed in the outer peripheral surface 20b of the insulator 20 may be supported. The insulator 20 is made of alumina ceramic.

  The seal member 40 is made of powdered talc. As shown in FIG. 2, the talc as the seal member 40 is surrounded by a base end side surface 21 b facing the base end side Y <b> 2 in the flange portion 21, an inner wall surface 30 a of the housing 30, and an outer peripheral surface 20 b of the insulator 20. The space 40a is filled and compressed. The seal member 40 is provided in the entire circumferential direction of the insulator 20 and seals between the insulator 20 and the housing 30.

When compressing the seal member 40, as shown in FIG. 2, a load P in the distal end Y1 direction in the axial direction Y is applied to the flange portion 21. The stress generated in the flange portion 21 by the load P can be expressed as follows. First, the stress σ ′ generated in the cantilever beam of the prism with respect to the load P is expressed by the equation (1) when the distance W ′ to the power point, the thickness of the prism column T ′, and the length L ′. Can be represented.
σ '= P × W' ( L '× T' 2/6) ··· Equation (1)

In this example, the flange 21 that receives the load P has a donut shape when viewed from the axial direction Y. Therefore, the distance W ′ is the width W of the flange portion 21 (the protruding length of the flange portion 21 in the radial direction X, that is, the distance in the radial direction X from the outer peripheral surface 20b of the insulator 20 to the outer peripheral surface 21a of the flange portion 21). The thickness T ′ can be the length T in the axial direction Y of the flange 21, and the length L ′ can be approximated as the circumferential length L of the flange 21. Here, when the outer diameter of the collar portion 21 is D, L is 2 × π × (D / 2). Therefore, the stress σ generated in the flange portion 21 due to the load P can be expressed as Equation (2), and the stress value per unit load can be expressed as Equation (3).
σ = P × W / (π × D × T 2/6) ... Equation (2)
^{W / (π × D × T} 2/6) ... formula (3)

In this example, the width W of the flange 21 is 2.45 mm, the outer diameter D of the flange 21 is 14.75 mm, and the length T in the axial direction Y is 2.3 mm. In this case, the value of stress per unit load ^{W / (π × D × T} 2/6) is 0.06.

Next, the effect in the gas sensor 1 of this example is explained in full detail.
In the gas sensor 1, the value of the ^{W / (π × D × T} 2/6) is in the 0.06 or less. Thereby, even when the diameter of the gas sensor 1 is reduced, the length T (that is, the thickness of the flange portion 21) of the flange portion 21 is sufficiently secured, so that the flange generated when the seal member 40 is compressed. It is prevented that the said collar part 21 is damaged by the stress in the part 21. FIG.

  As described above, according to this example, it is possible to provide the gas sensor 1 that can be reduced in diameter while preventing damage to the flange portion 21 of the insulator 20 due to a load when the seal member 40 is compressed.

Next, the relationship between the value of the length in the axial direction Y of the flange portion 21 (thickness) T and W / (π × D × T 2/6) in FIG. In addition, the outer diameter D of the collar part 21 is 14.75 mm, and the width W is 2.45 mm. As shown in FIG. 3, as the length T of the axial direction Y of the flange portion 21 is increased, the value of W / (π × D × T 2/6) is smaller. Then, in such conditions, when T is 2.3 mm, the value of ^{W / (π × D × T} 2/6) is 0.06, when T is 2.8mm, W / (π × D × value of ^T 2/6) is 0.04.

Next, the relationship between the value of the width W and W of the collar ^{21 / (π × D × T} 2/6) in FIG. In addition, the outer diameter D of the collar part 21 is 14.75 mm, and the thickness T is 2.8 mm. As shown in FIG. 4, as the width W of the flange portion 21 is increased, the value of W / (π × D × T 2/6) is larger. Then, in such conditions, when W is 2.45 mm, the value of ^{W / (π × D × T} 2/6) is 0.04.

Next, the relationship between the value of the outer diameter D and ^{W / (π × D × T} 2/6) of the flange portion 21 in FIG. 5. The width W of the collar portion is 2.45 mm, and the thickness T is 2.8 mm. As shown in FIG. 5, as the outer diameter D of the flange portion 21 is increased, the value of W / (π × D × T 2/6) is smaller. Then, in such conditions, when the value D is a 14.75, the value of ^{W / (π × D × T} 2/6) is 0.04.

(Damage test)
Next, a breakage test was performed on Sample 1 and Sample 2 of the insulator 20 shown in Table 1, and the quality of the insulator was evaluated.

  The breakage test was performed as follows. As shown in FIG. 6, the sample 1 or the sample 2 was first placed on the lower jig 101. The lower jig 101 has a cylindrical shape, and the flange portion 21 is supported on the end portion 101a on the base end side Y2 in the axial direction Y. Next, the upper jig 102 was applied to the end portion of the base end side Y2 of the insulator 20, and a predetermined amount of load P was applied to the front end side Y1 in the axial direction Y using an Amsler type compression tester. Thereafter, the presence or absence of cracks in the insulator 20 was examined by a dye penetrant inspection (so-called red check). A crack was determined to be damaged. The number of samples 1 and 2 was 20, and the load P was increased by 5 kN from 30 kN to 60 kN, and the number of damaged samples was cumulatively counted. The results are shown in Table 2.

As shown in Table 2, Sample 1 did not break up to 45 kN in all samples. Sample 2 did not break up to 35 kN in all samples. Usually, in the compression process of the sealing member 40, a load of 35 kN at the maximum is applied to the collar portion 21. Accordingly, from the test results of the samples 2, if the value of the W / (π × D × T 2/6) is 0.06 or less, in the compression process of the sealing member 40, to prevent damage to the flange portion 21 It was shown that Furthermore, in consideration of mass productivity (for example, failure probability 3σ, where σ indicates a standard deviation), it is preferable that the sample does not break even when a larger load P is applied. from the test results, the values of the W / (π × D × T 2/6) it was shown that it is preferable that 0.04 or less. In this case, a more reliable gas sensor can be provided.

(Example 2)
The gas sensor 1 of this example includes a collar part 210 shown in FIG. 7 instead of the collar part 21 (FIGS. 1 and 2) in the first embodiment. Further, instead of the housing 30 (FIG. 1), a housing 300 and a flare nut 350 shown in FIG. 7 are provided. Other components are the same as those in the first embodiment, and the same reference numerals as those in the first embodiment are used in this example, and the description thereof is omitted.

The collar portion 210 has an outer diameter D of 11.1 mm, a width W of 1.75 mm, and a length T in the axial direction Y of 7.85 mm. Then, a value of 0.005 in ^{W / (π × D × T} 2/6), which is 0.06 or less of the value. Therefore, even in this example, even if the diameter of the gas sensor 1 is reduced, the thickness T of the flange portion 210 is sufficiently ensured. Therefore, the flange portion 210 is caused by the stress in the flange portion 210 generated when the seal member 40 is compressed. Is prevented from being damaged. Further, in the gas sensor 1 of this example, the outer diameter D is smaller than in the case of Example 1, but the length in the axial direction Y (the thickness of the flange 210) T of the flange 210 is large. The effect of preventing damage to the insulator 20 is even higher.

  The housing 300 is formed in a cylindrical shape, and a flare nut 350 is screwed on the outside thereof. By reducing the outer diameter D of the collar portion 210 as described above, it becomes easy to ensure the thickness of the housing 300 and the thickness of the flare nut 350. As a result, it is possible to provide the gas sensor 1 including the flare nut 350 while preventing the insulator 20 from being damaged. By providing the flare nut 350, the gas sensor 1 can easily adjust the installation direction in the circumferential direction, so that the degree of installation freedom is further improved.

(Example 3)
The gas sensor of this example includes a flange 220 as shown in FIG. 8 instead of the flange 210 (FIG. 7) in the second embodiment. The flange portion 220 has an outer diameter D is 11.1 mm, the width W is 1.75 mm, is 3.0mm thick, the value of ^{W / (π × D × T} 2/6) is in the 0.034 . In addition, the same code | symbol is attached | subjected to the component equivalent to the case of Example 1, 2, and the description is abbreviate | omitted.

In this example, the length T in the axial direction Y of the flange portion 220 is 3.0 mm, and the flange portion 220 is thinner than that in the second embodiment. However, also in this embodiment, the value of ^{W / (π × D × T} 2/6) is a value of 0.06 or less. Therefore, in this example as well, even if the gas sensor 1 is reduced in diameter, the length Y in the axial direction Y of the flange 220 (the thickness of the flange 220) is sufficiently secured. This prevents the flange 220 from being damaged by the stress in the flange 220 that is generated when the seal member 40 is compressed. Furthermore, since the flange portion 220 is thinner than in the second embodiment, the insulator 20 can be formed in a small size, which contributes to downsizing of the entire gas sensor 1. In addition, there exists an effect equivalent to Example 2. FIG.

DESCRIPTION OF SYMBOLS 1 Gas sensor 10 Sensor element 20 Insulator 20b Peripheral surface 21,210,220 collar 21b Base end side surface 30,300 Housing 30a Inner wall surface 31 Annular protrusion 40 Seal member 40a Space part

Claims (2)

It is formed in a rod shape extending in the axial direction (Y), is exposed to the gas to be measured on the tip side (Y1), and detects the specific gas in the gas to be measured, and the base side (Y2) A sensor element (10) including an output unit (12) that outputs an output signal corresponding to a detection result of the detection unit (11);
An insulator (20) made of an insulator having a flange (21) which is formed in a cylindrical shape so as to hold the sensor element (10) inside and which protrudes in a convex shape on the outer peripheral surface (20b); ,
The sensor element (10) and the insulator (20) are held inside, and an annular protrusion (31) formed in an annular shape on the inner wall surface (30a) so as to support the flange (21). A cylindrical housing (30) having;
Fills a space (40a) surrounded by the base end side surface (21b) of the flange (21), the inner wall surface (30a) of the housing (30), and the outer peripheral surface (20b) of the insulator (20). And a seal member (40) that is compressed and sealed between the insulator (20) and the housing (30);
In a gas sensor (1) comprising:
The length in the axial direction (Y) of the flange (21) is T, the protrusion length in the radial direction (X) of the flange (21) is W, and the outer diameter of the flange (21) is D. when gas sensor stress value per unit load represented by ^{W / (π × D × T} 2/6) is characterized in that less than or equal to 0.06 (1). The gas sensor according to claim 1, the value of the ^{W / (π × D × T} 2/6) is characterized in that 0.04 or less (1).

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