JP6308054B2 - Gas sensor element assembly - Google Patents

Description

  The present invention relates to a gas sensor element for detecting the concentration of a specific gas component in a gas to be measured, a cylindrical insulator that accommodates and holds the gas sensor element, and a sealing glass that hermetically fixes the gas sensor element and the insulator And a gas sensor element assembly.

Conventionally, as a gas sensor for detecting the concentration of a specific gas in a gas to be measured, a gas sensor element having a detection portion on the tip side, a substantially cylindrical insulator that holds the sensor element inserted therein, and the insulator There is known a housing constituted by a housing in which is inserted and disposed and a cover body which is disposed on the front end side of the housing and protects the sensor element.
As a gas sensor element used in such a gas sensor, a solid electrolyte layer having conductivity with respect to specific ions such as zirconia, a pair of electrodes formed on at least opposite surfaces thereof, and an insulating material such as alumina are used. 2. Description of the Related Art Laminated gas sensor elements are widely used which are formed by laminating element holding members and heater layers with built-in heating elements, etc., and having a rectangular cross section and a flat plate shape extending in the axial direction.
Patent Document 1 discloses a gas sensor element in which a flat sensor element extending in the axial direction is housed and fixed inside a substantially cylindrical insulator via a sealing glass, and is a boundary portion between the sealing glass and the sensor element. Discloses a gas sensor element which is made of an inorganic material and has a coating layer having a multi-particle structure so as to cover 80% or more of the surface of the sealing glass while covering the outer periphery of the sensor element, and a method for manufacturing the same.

  In the conventional gas sensor element, an annular groove-shaped glass filling space surrounding the outer periphery of the sensor element is provided on the base end side of the insulator, filled with sealing glass, heated and melted, and then cooled and solidified. And the insulator are hermetically fixed.

JP 2010-243422 A

However, in the conventional gas sensor element assembly 4z shown as the comparative example 1 in FIG. 10, when a part of the outer peripheral surface of the base end side of the insulator 3z is cut out in a planar shape to form the rotation preventing portion 33, the meat of that portion is formed. The thickness T ₃₃ z becomes thinner than the thickness (T ₃₀ ) of other portions, the mechanical strength against the assembly load of the insulator 3z is lowered, and there is a possibility of causing a crack failure during assembly.
In addition, when the insulator 3z is molded using a mold or the like, the cavity for forming the anti-rotation portion 33 is narrow, the material filling property is lowered, and distortion due to local density reduction may be caused. there were.

Therefore, as shown in FIG. 11 as Comparative Example 2, the rotation preventing portion 33 is formed, and the inner peripheral surface of the glass-filled space 32y is parallel to the outer peripheral surface of the insulator 3y formed in a cross-sectional shape. By forming the cross-sectional oval shape, the thickness T ₃₃ y at the position where the anti-rotation portion 33 of the insulator 3 y is formed is made equal to the thickness (T ₃₀ ) of the other portion, thereby improving the mechanical strength. It was thought that it was possible.
On the other hand, high-melting glass such as crystallized glass, aluminosilicate glass, borosilicate glass is used for the sealing glass 2 used for fixing the conventional sensor element 1 in consideration of heat resistance. Such heat-resistant glass has a large surface tension that acts during melting, and the contact surface with the insulator tends to be rounded.

Further, since the surface of the sensor element 1 is provided with a terminal electrode for connection to the outside, a detection electrode exposed to the gas to be measured, etc., the electrode is configured when exposed to an excessively high temperature environment. There is a possibility that the life of the electrode may be reduced due to aggregation of the metal particles.
For this reason, the heating temperature at the time of melting the sealing glass is limited so that the electrode is not exposed to an excessively high temperature environment, and the fluidity of the sealing glass is also limited.
For this reason, when the glass filling space 32y is formed by providing the inner peripheral surface of the cross-sectional oval shape parallel to the outer peripheral surface of the insulator 3 formed in the cross-sectional oval shape, as shown in FIG. There is a possibility that a gap GP is formed between the inner peripheral surface of the glass filling space 32y drilled in the surface and the surface of the sealing glass 2y having an elliptical cross section due to surface tension, leading to a decrease in hermeticity.

  Further, in the configuration in which the rotation preventing portion is not formed on the outer peripheral surface of the insulator 3x as in the gas sensor element assembly 4x shown as the comparative example 3 in FIG. 12, in order to further reduce the size of the gas sensor, When the outer peripheral surface of the base end side of the insulator 3x forming the glass-filled space 32x is thinned to the limit that can be formed as a peripheral wall surface, and the outer diameter φD3x of the insulator 3x is reduced, the load at the time of assembly is received. Since the cross-sectional area is small, the entire thin portion cannot withstand the assembling load, and there is a risk of causing a crack failure during assembling.

  Then, in view of such a situation, the present invention suppresses a decrease in mechanical strength of a cylindrical insulator that accommodates and fixes a flat sensor element having a rectangular cross section and extending in the axial direction, and an insulator and a sealing glass. An object of the present invention is to provide a highly reliable gas sensor element assembly that improves the adhesion of the gas sensor.

In the gas sensor element assembly ( 4a, 4b, 4d ) according to one aspect of the present invention, the gas sensor element assembly ( 4a, 4b, 4d ) includes a detection unit (10) that is exposed to the gas to be measured and detects a specific component in the gas to be measured. A plate-like gas sensor element (1) extending in the direction of a cylinder, and a cylindrical insulator ( 3 ) having a through-hole (31) extending in the axial direction with a rectangular cross section inside and accommodating and holding the gas sensor element in the through-hole. And a cylindrical sealing glass ( 2 ) disposed in a glass-filled space ( 32 ) partitioned by hollowing out a part of the insulator, and melting and solidifying the sealing glass to form the gas sensor element In the gas sensor element assembly in which the insulator and the insulator are hermetically fixed, the cross-sectional shape of the glass-filled space is a rounded octagonal shape with rounded corners. JP that without a rounded octagonal with rounded To.
Moreover, the gas sensor element assembly (4, 4a, 4b) in another aspect is
A flat gas sensor element (1) that is exposed to the gas to be measured and includes a detection unit (10) that detects a specific component in the gas to be measured, and has a rectangular cross section and extends in the axial direction;
A cylindrical insulator (3) which has a through-hole (31) which is rectangular in cross section and extends in the axial direction on the inside, and which accommodates and holds the gas sensor element in the through-hole;
A cylindrical sealing glass (2) disposed in a glass-filled space (32) partitioned by hollowing out a part of the insulator,
In the gas sensor element assembly in which the sealing glass is melted and solidified, and the gas sensor element and the insulator are hermetically fixed.
By making the cross-sectional shape of the glass-filled space an elliptical shape having a flat part, or a rounded polygonal shape of a polygon rather than a square with rounded corners,
The cross-sectional shape of the sealing glass is an elliptical shape having a flat part, or a polygonal rounded polygonal shape rather than a rounded corner,
The insulator includes a detent (33) formed so that a part of the outer peripheral surface thereof is cut out in a planar shape.
In still another aspect, the gas sensor element assembly (4, 4a, 4b, 4c, 4d)
A flat gas sensor element (1) that is exposed to the gas to be measured and includes a detection unit (10) that detects a specific component in the gas to be measured, and has a rectangular cross section and extends in the axial direction;
A cylindrical insulator (3) which has a through-hole (31) which is rectangular in cross section and extends in the axial direction on the inside, and which accommodates and holds the gas sensor element in the through-hole;
A cylindrical sealing glass (2) disposed in a glass-filled space (32) partitioned by hollowing out a part of the insulator,
In the gas sensor element assembly in which the sealing glass is melted and solidified, and the gas sensor element and the insulator are hermetically fixed.
By making the cross-sectional shape of the glass-filled space an elliptical shape having a flat part, or a rounded polygonal shape of a polygon rather than a square with rounded corners,
The cross-sectional shape of the sealing glass is an elliptical shape having a flat part, or a polygonal rounded polygonal shape rather than a rounded corner,
An intersection (insulator diagonal position end point P ₃₀ ) from an intersection (glass diagonal position end point P ₂₀ ) between the extended line of the diagonal of the gas sensor element and the outer periphery of the sealing glass (glass diagonal position end point P ₂₀ ) the distance to an insulator diagonal positions thickness T _30,
An intersection (a glass longitudinal direction end point P ₂₁ ) between a long side direction center line (CL ₁ ) vertically lowered from a central point (CP) of the gas sensor element toward a short side of the gas sensor element and an outer peripheral edge of the sealing glass. ) To the intersection (insulator longitudinal direction end point P ₃₁ ) of the long side direction center line and the outer peripheral edge of the insulator as the insulator longitudinal direction thickness T ₃₁ ,
From the intersection (the glass short direction end point P ₂₂ ) of the short side direction center line (CL ₂ ) vertically lowered from the center of the gas sensor element toward the long side of the sealing glass and the outer peripheral edge of the sealing glass. When the distance to the intersection (insulator short direction end point P ₃₂ ) of the short side direction center line and the outer peripheral edge of the insulator 3 is the insulator short direction thickness T ₃₂ ,
The relationship T ₃₀ ≦ T ₃₁ <T ₃₂ is established.
In still another aspect, the gas sensor element assembly (4, 4a, 4b, 4c, 4d)
A flat gas sensor element (1) that is exposed to the gas to be measured and includes a detection unit (10) that detects a specific component in the gas to be measured, and has a rectangular cross section and extends in the axial direction;
A cylindrical insulator (3) which has a through-hole (31) which is rectangular in cross section and extends in the axial direction on the inside, and which accommodates and holds the gas sensor element in the through-hole;
A cylindrical sealing glass (2) disposed in a glass-filled space (32) partitioned by hollowing out a part of the insulator,
In the gas sensor element assembly in which the sealing glass is melted and solidified, and the gas sensor element and the insulator are hermetically fixed.
By making the cross-sectional shape of the glass-filled space an elliptical shape having a flat part, or a rounded polygonal shape of a polygon rather than a square with rounded corners,
The cross-sectional shape of the sealing glass is an elliptical shape having a flat part, or a polygonal rounded polygonal shape rather than a rounded corner,
The distance from the apex (element diagonal position end point P ₁₀ ) of the gas sensor element to the intersection (glass diagonal position end point P ₂₀ ) between the extended line of the diagonal of the gas sensor element and the outer periphery of the sealing glass is glass. a diagonal position thickness _{T 20,}
From the intersection (element longitudinal direction end point P ₁₁ ) of the long side direction center line (CL ₁ ) vertically lowered from the center (CP) of the gas sensor element toward the short side of the gas sensor element and the short side of the gas sensor element The distance to the intersection (glass longitudinal direction end point P ₂₁ ) of the long side direction center line and the outer peripheral edge of the sealing glass is the glass longitudinal direction thickness T ₂₁ ,
From the intersection (element short direction end point P ₁₂ ) of the short side direction center line (CL ₂ ) vertically lowered from the center of the gas sensor element toward the long side of the gas sensor element and the long side of the gas sensor element When the distance to the intersection (glass short direction end point P ₂₂ ) with the outer periphery of the stop glass is the glass short direction thickness T ₂₂ ,
The relationship T ₂₀ ≦ T ₂₁ <T ₂₂ is established.

  According to the present invention, the gap is formed between the inner peripheral surface of the glass filling space and the surface of the sealing glass while maintaining the strength at which the insulator does not crack against a predetermined load. In addition, a highly reliable gas sensor element assembly in which the insulator and the gas sensor element are hermetically fixed can be realized.

The perspective view which shows the whole outline | summary of the gas sensor element assembly 4 in the 1st Embodiment of this invention. 1 is a longitudinal sectional view of the gas sensor element assembly 4 of FIG. 1A. The detail of the glass filling space 32 which is the principal part of this invention is shown, and the cross-sectional view along CC in FIG. 1B The principal part top view for demonstrating the test method performed for optimization of the cross-sectional shape of the glass filling space 32 The characteristic view which shows the effect in the 1st Embodiment of this invention with a comparative example Cross-sectional view of glass-filled space 32a, which is the main part of gas sensor element assembly 4a in the second embodiment of the present invention The principal part top view for demonstrating the test method performed for optimization of the cross-sectional shape of the glass filling space 32a The characteristic figure which shows the effect in the 2nd Embodiment of this invention with a comparative example Cross-sectional view of glass-filled space 32b, which is the main part of gas sensor element assembly 4b in the third embodiment of the present invention The principal part top view for demonstrating the test method performed for optimization of the cross-sectional shape of the glass filling space 32b The characteristic view which shows the effect in the 3rd Embodiment of this invention with a comparative example Characteristic chart summarizing the effects of the present invention The cross-sectional view of the glass filling space 32c which is the principal part of the gas sensor element assembly 4c in the 4th Embodiment of this invention. Cross-sectional view of glass-filled space 32d, which is the main part of gas sensor element assembly 4d in the fifth embodiment of the present invention Cross-sectional view of a glass-filled space 32z, which is a main part of a conventional gas sensor element assembly 4z, shown as Comparative Example 1 A cross-sectional view of a glass filling space 32y, which is a main part of the gas sensor element assembly 4y, shown as a comparative example 2. A cross-sectional view of a glass-filled space 32x, which is a main part of the gas sensor element assembly 4x, shown as Comparative Example 3. The longitudinal cross-sectional view which shows the general | schematic outline of the gas sensor using the gas sensor element assembly of this invention

The gas sensor element assembly 4 according to the first embodiment of the present invention will be described with reference to FIGS. 1A, 1B, and 1C.
The sensor element assembly 4 (hereinafter abbreviated as the assembly 4) is used in a gas sensor that is provided in a combustion exhaust passage of a combustion engine and measures the concentration of a specific gas component in a gas to be measured.
In the following description, a combustion exhaust discharged from an internal combustion engine such as an automobile engine is used as a gas to be measured, and an oxygen sensor that detects an oxygen component concentration in the gas to be measured will be described as an example. The element assembly 4 is not limited to an oxygen sensor, but can be applied to assembling various gas sensor elements such as an NH ₃ sensor, a NOx sensor, an O ₂ sensor, and a PM sensor according to a detection target in a gas to be measured. It is possible.
In the following description, in the cross section of the flat gas sensor element 1 (hereinafter abbreviated as element 1) having a rectangular cross section and extending in the axial direction, the direction parallel to the short side of the element 1 is the short direction, and the element 1 A direction parallel to the long side is referred to as a longitudinal direction.

The assembly 4 includes the element 1, the insulator 3, and the sealing glass 2.
The element 1 includes a detection unit 10 that is exposed to a gas to be measured and detects a specific component in the gas to be measured, and is formed in a flat plate shape having a rectangular cross section and extending in the axial direction.

The insulator 3 is made of a known insulating material such as alumina and is formed in a cylindrical shape.
A through hole 31 having a rectangular cross section and extending in the axial direction is provided inside the insulator 3.
The element 1 is accommodated and held in the through hole 31.
The insulator 3 is formed with a glass-filled space 32 in which a part of the proximal end portion is recessed and partitioned.
In the glass filling space 32, a sealing glass 2 in which a known heat-resistant glass is previously formed into a cylindrical shape is disposed.
By melting and solidifying the sealing glass 2, the element 1 and the insulator 3 are fixed in an airtight manner to constitute an assembly 4.

The insulator 3 is formed with an anti-rotation portion 33 formed so that a part of the outer peripheral surface thereof is cut out in a planar shape.
The glass filling space 32 in the present embodiment has an elliptical shape with a flat portion in the cross-sectional shape.
The cross-sectional shape of the sealing glass 2 in the present embodiment is an elliptical shape having a flat portion .

The element 1 is a so-called laminated sensor element formed in a flat plate shape having a rectangular cross section and extending in the axial direction.
A detection unit 10 that is exposed to the gas to be measured is provided on the tip side of the element 1.
The detection unit 10 is opposed to a flat solid electrolyte layer (not shown) made of partially stabilized zirconia that exhibits conductivity with respect to specific ions with the solid electrolyte layer interposed therebetween, and is in contact with the gas to be measured. An electrode (not shown) and a reference electrode (not shown) in contact with the reference gas are provided.
Further, in order to heat-activate the detection unit 10, a heater (not shown) is provided that is embedded in an insulating layer (not shown) formed of an insulating material such as alumina in a flat plate shape and generates heat when energized.
The surface of the detection unit 10 is covered with a porous protective layer 11.

At the base end of the element 1, a reference gas chamber 12 for introducing the atmosphere as a reference gas is opened inside the detection unit 10.
On the base end side surface of the element 1, a pair of signal terminals 13 for conducting electrical connection between a calculation unit (not shown) provided outside and a reference electrode layer and a measurement electrode layer, and a heater provided in the detection unit 10 and provided outside. A pair of energization terminals 14 are provided for connection with the power source.

In the following description, a straight line extending vertically from the center point CP of the element 1 toward the short side of the element 1 is referred to as a long-side direction center line CL _1, and from the center point CP of the element 1 toward the long side of the element 1. the drawn vertically straight and short side direction center line CL _2.

Element 1, the element diagonal length T ₁₀ the distance from the center point CP with a rectangular cross section to elements diagonally opposite the end point P ₁₀ of the apex of the element 1 along the diagonal, elements from the central point CP longitudinal edge point P ₁₁ is the element longitudinal direction length T _11, and the distance from the center point CP to the element short direction end point P ₁₂ is the element short direction length T ₁₂ , T ₁₀ ² = T ₁₁ ² + T ₁₂ There is a relationship of ^two .

The sealing glass _{2, B 2 O 3 - ZnO -SiO} 2 -Al 2 O 3 crystallized glass such as -BaO-MgO, aluminosilicate glass, refractory glass such as borosilicate glass is used.
The sealing glass 2 is formed in a cylindrical shape for easy assembly of a powdery sealing glass raw material, and is inserted into a glass filling space 32 provided in the insulator 3.

In the present embodiment, the sealing glass 2 is formed in an elliptical cross section, and a through hole for inserting the element 1 is provided at the center.
When the element 1, the insulator 3, and the sealing glass 2 are temporarily assembled and heated to about 900 ° C. to crystallize the sealing glass 2, the element 1 is in the insulator 3 through the sealing glass 2. The airtight state is maintained.

More specifically, the thickness of up to glass diagonal positions the end point P ₂₀ intersects the diagonal extension line and the edge of the sealing glass 2 of the element 1 as the glass diagonal positions thickness T _20, elements of the device 1 the distance from the longitudinal end point P ₁₁ to the glass longitudinally end point P ₂₁ of the sealing glass 2 and the glass longitudinal thickness T _21, glass lateral direction of the sealing glass 2 from the element widthwise direction end point P ₁₂ of element 1 when the distance to the end point _{P 22} and the glass short direction thickness _{T 22,} the relationship _{T 20} ≦ _T 21 _{<T 22} holds.
Incidentally, for convenience of molding the sealing glass 2 glass diagonal positions thickness _{T 20} is required to be a less than 1.0mm.
Furthermore, the short side edge from the glass diagonal position end point P _{20 of} the sealing glass 2 to the glass longitudinal direction end point P ₂₁ has a radius R ₂₀ = T ₂₀ with the element diagonal position end point P ₁₀ of the element 1 as the center. And a straight line parallel to the side of the short side of the element 1 or an arc having a radius R ₂₁ = T ₁₀ + T ₂₀ with the center point CP of the element 1 as the center.
The distance L ₂₁ from the center point CP of the element 1 to the short side edge of the sealing glass 2 can be appropriately changed within the range of T ₁₁ + T ₂₀ ≦ L ₂₁ ≦ T ₁₀ + T ₂₀ .

Also, the longitudinal side edges of the glass diagonal positions the end point P ₂₀ of the sealing glass 2 to the glass widthwise direction end point P ₂₂ is the long diameter a around the virtual center point VCP, an elliptical shape of minor axis b ing.
The virtual center point VCP in the present embodiment is perpendicular to a straight line that passes through the center point CP of the element 1 and intersects with the long side of the element 1 from the point where the diagonal extension of the element 1 and the outer peripheral edge of the sealing glass 2 intersect. It is an intersection with a straight line.
The distance W ₂₂ from the center point CP of the element 1 to the long side edge of the sealing glass 2 can be appropriately changed within the range of T ₁₂ + T ₂₀ <W ₂₂ ≦ T ₁₀ + T ₂₀ −H ₃₃ .
From the viewpoint of fluidity sealing glass 2, it was found that it is desirable to 1.25 mm ≦ _{W 22.}
However, the position of the virtual center point VCP is not limited to this, and can be changed as appropriate within the range that has been clarified by the test described later.

The insulator 3 is formed in a cylindrical shape using a known heat-resistant insulating material such as high-purity alumina.
The insulator 3 includes an insulator base 30, a sensor element insertion hole 31, a sealing glass housing space 32, a rotation stopper 33, and an insulator enlarged diameter portion 34.
The insulator base 30 is formed in a cylindrical shape having an outer shape φD ₃ (= 2 (T ₁₀ + T ₂₀ + T ₃₀ )).
The sensor element insertion hole 31 is formed so as to penetrate the insulator base 30 and has a cross-sectional shape into which the element 1 having a predetermined clearance can be inserted with respect to the cross-sectional shape of the element 1.

In the sealing glass housing space 32 in the present embodiment, the inner peripheral surface is curved in an elliptical shape in order to suppress the formation of a gap between the sealing glass 2 and the outer peripheral surface of the sealing glass 2.
Moreover, in order to prevent the local mechanical strength fall, the inner peripheral surface of the sealing glass accommodation space 32 is formed so that the insulator base 30 may have a predetermined thickness.
Insulator diagonal positions thickness T ₃₀ includes a extension line of the diagonal lines of the element 1, from the intersection of the outer periphery of the sealing glass 2 (glass diagonal position the end point P _20), the outer peripheral edge of the insulator base 30 This is the distance to the intersection (insulator diagonal position end point P ₃₀ ).
The insulator longitudinal thickness T ₃₁ is a distance from the glass longitudinal end point P ₂₁ of the sealing glass 2 to the insulator longitudinal end point P ₃₁ of the insulator 3.
From the sealing point of intersection (glass widthwise direction end point) between the outer peripheral edge of the short-side direction center line CL ₂ and the sealing glass 2 drawn down vertically toward the long side of the glass 2 P ₂₂ from 1 center of the gas sensor element, a short When the distance to the intersection (insulator short direction end point P ₃₂ ) of the side direction center line CL ₂ and the outer peripheral edge of the insulator 3 is the insulator short direction thickness T ₃₂ ,
The relationship T ₃₀ ≦ T ₃₁ <T ₃₂ is established.
The insulator detent portion thickness T ₃₃ is the distance from the element short direction end point P ₁₂ of the sealing glass 2 to the end point (insulator detent position end point) P ₃₃ of the detent portion 33 of the insulator 3.
The notch depth H ₃₃ is the depth of the rotation stopper 33.
T ₃₀ ≦ T ₃₁ ≦ T ₃₀ + T ₁₀ −T ₁₁ ,
Relationship _{T 10 + T 30 -H 33 -T} 12 <T 33 ≦ T 10 + T 20 -H 33 holds.

  The insulator diameter-expanded portion 34 is formed in a bowl shape projecting so that a part of the insulator base portion 30 has a large diameter in the outer diameter direction, and is known as talc powder or the like when assembled to a gas sensor to be described later. The housing is hermetically held via the sealing member.

With reference to FIG. 2A and FIG. 2B, the test performed for the optimization of the cross-sectional shape of the glass filling space 32 in the 1st Embodiment of this invention and its result are demonstrated.
As the element 1, a cross-sectional width of 4.0 mm and a plate thickness of 1.6 mm were used.
That is, the above-mentioned T ₁₁ = 2.0 mm, T ₁₂ = 0.8 mm, and T ₁₀ ≈2.15 mm.
The outer [phi] D ₃ of the insulator 3 and 7.60Mm, the detent portion depth _{H 33} and 0.25 mm, 1.0 mm glass diagonal positions thickness _{T 20,} the insulator diagonal positions thickness _{T 30} 0 .65 mm, the distance from the edge of the rotation stopper 33 to the edge of the sealing glass 2, that is, the rotation stopper thickness T ₃₃ is changed stepwise from 0.5 mm to 1.75 mm to insulate A compressive load was applied in the axial direction of the body 3, and the limit load at which cracking occurred was measured.
As a result, in the conventional comparative example 1, the crack was generated by the compressive load of 800 N or less.
In the first embodiment of the present invention, the detent portion thickness T ₃₃ in the case of the above 0.68 mm, was found to be able to exhibit the strength that can counter the above target load 900 N.
Further, when the rotation preventing portion thickness T ₃₃ thicker than 1.5 mm, the mechanical strength can be greater than the target load, the glass cross section longitudinal thickness T ₂₁ of the sealing glass 2 becomes thin, molded It has been found that the gap GP increases between the inner peripheral surface of the glass filling space 32 and the outer peripheral edge of the sealing glass 2 in addition to a decrease in the packing density at the time.
From the above, it has been found that in the present embodiment, it is desirable to set the insulator detent thickness T _{33 to} 0.68 mm or more and 1.5 mm or less.

An assembly 4a according to the second embodiment of the present invention will be described with reference to FIGS. 3, 4A, and 4B.
In the following embodiments, the same components as those in the above embodiments are denoted by the same reference numerals, and the characteristic portions in the respective embodiments are denoted by alphabetical symbols as branch numbers. The description will be omitted, and the features of the respective embodiments will be mainly described.

The glass filling space 32a in the present embodiment is formed in an octagonal shape with rounded corners whose corners are curved in an R shape.
In the present embodiment, on the extension of the diagonal line of the element 1, T ₂₀ ≦ T ₂₁ <between the glass diagonal position wall thickness T ₂₀ , the glass longitudinal direction wall thickness T ₂₁ , and the glass short-side wall thickness T _22. relation of T ₂₂ is satisfied.
Further, on the extension line of the diagonal line of the element 1, T ₃₀ ≦ T ₃₁ ≦ between the insulator diagonal position thickness T ₃₀ , the insulator longitudinal direction thickness T ₃₁ , and the insulator detent thickness T _33. relation of T ₃₃ is satisfied.
Each vertex angle of the octagon is formed in a round angle of curvature radius R = T _20.
Further, the inner peripheral surface of the glass filling space 32a is parallel to the longitudinal plane of the element 1, and the inner peripheral surface on the side where the anti-rotation portion 33 is formed, and the lateral side surface of the element 1 The inclination angle θ ₂ a of the inclined side of the polygonal inner peripheral surface connecting the short side inner peripheral surface parallel to the angle is set to 45 °.

In this embodiment, as shown in FIG. 4A, the insulator detent portion thickness _{T 33} a, by changing to 0.5Mm～1.75Mm, was investigated cracking load, as shown in FIG. 4B It was found that a strength of not less than a predetermined target load (900 N) can be exhibited at 0.62 mm or more.

With reference to FIG. 5, FIG. 6A, and FIG. 6B, the assembly 4b in the 3rd Embodiment of this invention is demonstrated.
In the present embodiment, the inclination angle θ ₂ b of the inclined side of the inner peripheral surface of the polygon is set to 30 °.
In this embodiment, as shown in FIG. 6A, when the insulator detent thickness T ₃₃ b is changed from 0.45 mm to 1.75 mm, the crack load is improved at 0.45 mm or more. Turned out to be possible.
Also in the present embodiment, as in the above-described embodiment, when the insulator detent thickness T ₃₃ b exceeds 1.5 mm, the gap GP is reduced due to a decrease in the filling property of the sealing glass 2b or a decrease in the fluidity. There is concern about the formation of

Table 1 shows the results of investigations on changes in cracking load in each example, as well as comparative examples.
According to the present invention, it has been found that in any of the embodiments, the strength higher than the target crack load can be exhibited.

Furthermore, as shown in FIG. 7, when the effects of the present invention are summarized, in any of the embodiments, the detent thicknesses T ₃₃ , T ₃₃ a, and T ₃₃ b are set to 0.68 mm or more. It has been found that highly durable assemblies 4, 4a and 4b can be formed which avoid local strength reduction and exceed the target load.
In the above embodiment, the example in which the inclination angles θ ₂ a and θ ₂ b are set to 45 ° and 30 ° when the cross-sectional shape of the sealing glasses 2a and 2b is a rounded octagon is shown. In the present invention, the shape of the outer peripheral edge of the sealing glass 2a, 2b along the shape of the inner peripheral edge of the glass-filled spaces 32a, 32b is not limited to these. Various rounded polygonal shapes such as a square shape and a rounded square shape may be used.
Also in this case, the glass cross-sectional direction thickness T ₂₂ and the glass diagonal position thickness T ₂₀ and the insulator diagonal position thickness T ₃₀ on the extension of the diagonal line of the element 1 are the thinnest. by setting the rotation stopper wall thickness T _33, it is possible to exhibit a sufficient strength against a load operating in the axial direction of the insulator 3,
Moreover, when the inner peripheral surface of the glass filling space 32 is formed in a polygon, by providing a predetermined R at the corner formed by the intersection of two adjacent sides, the sealing glass 2, 2a, 2b It becomes difficult to form a gap between the outer peripheral edge and airtightness can be secured.

With reference to FIG. 8, the gas sensor element assembly 4c in the 4th Embodiment of this invention is demonstrated.
In the above-described embodiment, the configuration in which the anti-rotation portion 33 is provided in the insulator 3 has been described. However, in the insulator 3c in this embodiment, the anti-rotation portion is not provided, and the outer diameter φD3c of the insulator 3c is The inner peripheral surface constituting the glass filling space 32c is made as thin as possible in contact with the outer diameter.
In this embodiment, the cross-sectional shape of the glass filling space 32c is the same elliptical shape as the gas sensor element assembly 1 in the first embodiment, so that the cross-sectional shape of the sealing glass 2c is an elliptical shape. It is formed.
Also in the present embodiment, the relationship of T ₃₀ ≦ T ₃₁ <T ₃₂ c is established.
Furthermore, also in this embodiment, the relationship of T ₂₀ ≦ T ₂₁ <T ₂₂ is established.
In the present embodiment, by making the cross-sectional shape of the glass-filled space 32 and elliptical, by forming the insulator lateral direction thickness T _{32 c} of the insulator 3c thicker, the thinnest portion It is possible to make up for the insufficient strength at the diagonal position of the insulator and relatively increase the strength of the base end side of the insulator 3c.
In the present embodiment, when the element 1 having the same size as the above-described embodiment (for example, plate thickness 2T ₁₂ = 1.6 mm × width 2T ₁₁ = 4.0 mm) is used, the base end side of the insulator 3c insulator diagonal positions thickness T ₃₀ of the thinnest portion of the peripheral wall portion forming a glass-filled space 32c in, for example, more than 0.65 mm, the thickest portion to become the insulator lateral direction thickness T _{32 c} is It has been found that the effect of the present invention can be exhibited if the thickness is 0.83 mm or more.

With reference to FIG. 9, the assembly 4d in the 5th Embodiment of this invention is demonstrated.
Also in the present embodiment, as in the fourth embodiment, no detent portion is provided, and the outer diameter φD3d of the insulator 3d is made as thin as possible.
Furthermore, in this embodiment, the cross-sectional shape of the glass filling space 32d is a rounded polygonal shape with rounded corners, similar to the gas sensor element assemblies 4a and 4b in the second and third embodiments. The cross-sectional shape of the sealing glass 2d is a rounded polygonal shape with rounded corners.
By setting it as such a structure, the effect similar to 3rd Embodiment can be exhibited.

Assemblies 4z, 4y, and 4x, which are shown as Comparative Example 1, Comparative Example 2, and Comparative Example 3 in FIG. 10, FIG. 11, and FIG.
In Comparative Example 1, and thinner than the inner circumferential surface of the glass-filled space 32z is formed in a circular shape, the thickness T _{33 z} of the portion forming the rotation stopper 33 is the thickness of the other portion (T ₃₀₎ It has become.
For this reason, the mechanical strength with respect to the assembly load of the insulator 3z is lowered, and there is a possibility of causing a crack defect during the assembly.
In addition, when the insulator 3z is molded using a mold or the like, the cavity for forming the anti-rotation portion 33 is narrow, the material filling property is lowered, and distortion due to local density reduction may be caused. there were.

In Comparative Example 2, the rotation preventing portion 33 is formed, and the inner peripheral surface of the glass filling space 32y is formed in a cross-sectional oval shape in parallel with the outer peripheral surface of the insulator 3y formed in a cross-sectional oval shape. The thickness T ₃₃ y at the position where the anti-rotation portion 33 of the insulator 3 y is formed is formed to be equal to the thickness T ₃₀ of other portions.
A gap GP is formed between the inner peripheral surface of the glass filling space 32y and the surface of the sealing glass 2y having an elliptical cross section due to surface tension, which may cause a decrease in airtightness.

In Comparative Example 3, the base end of the insulator 3x that forms the annular groove-shaped glass-filled space 32x in order to further reduce the size of the gas sensor in the configuration in which the rotation preventing portion is not formed on the outer peripheral surface of the insulator 3x. The outer peripheral surface is thinned to the limit that can be formed as a peripheral wall surface, and the outer diameter φD3x of the insulator 3x is reduced.
Since the wall thickness T ₃₀ x on the base end side of the insulator 3 is extremely thin, the cavity formed in the mold used at the time of molding is narrow, the compactness is lowered, and the cross-sectional area that receives the load at the time of assembly Therefore, the entire thin-walled portion cannot withstand the assembly load, and there is a risk of causing a crack failure during assembly.

With reference to FIG. 13, the outline | summary of the gas sensor 8 containing the assembly 4 of this invention is demonstrated.
The gas sensor 8 includes an assembly 4, a housing 5, a cover body 6, and a gas sensor base end portion 7.
The housing 5 is made of a known metal material such as iron, nickel, alloys thereof, carbon steel, and stainless steel.
The housing 5 includes a housing base 50, an assembly housing portion 51, an assembly locking portion 52, a large-diameter cylindrical portion 53, a caulking portion 54, a cover caulking portion 55, and a screw portion 56. Has been.

An assembly housing portion 51 is formed inside the housing base 50, and an assembly locking portion 52 that changes in diameter so as to increase in diameter toward the proximal end side at the proximal end side of the assembly housing portion 51. Further, a large-diameter cylindrical portion 53 into which the insulator enlarged-diameter portion 34 can be inserted is formed on the proximal end side.
In the assembly accommodating part 51, the front end side of the assembly 4 which concerns on this invention is accommodated.
The surface on the distal end side of the insulator expanded diameter portion 34 of the assembly 4 is in direct or indirect contact with the assembly locking portion 52.
Further, a known powder filler 57 such as talc or a seal member is filled in a space defined by the insulator enlarged diameter portion 34, the caulking portion 54, and the large diameter cylindrical portion 53. A force is applied to press the insulator enlarged diameter portion 34 so as to be hermetically fixed.
The screw portion 56 is screwed into the measurement gas flow path 81 through which the measurement gas 80 flows, and holds the detection unit 10 provided at the tip of the element 1 in the measurement gas 80.

The cover body 6 is provided in a bottomed cylindrical shape. The cover base 60 is provided with an introduction hole 61 for introducing a gas to be measured inside.
The base end side of the cover body 6 is caulked and fixed by a cover body caulking portion 55 provided at the distal end of the housing 5.
In this figure, a cover body having a double cylinder structure is shown. However, in the present invention, it is not particularly limited and can be appropriately changed.

  The gas sensor base end portion 7 includes a casing 70, an insulator 71, a pair of signal terminal fittings 72, a pair of energizing terminal fittings 73, a pair of signal wires 74, a pair of energizing wires 75, and a water repellent filter 76. And a grommet 78.

The casing 70 is formed in a cylindrical shape using a known metal material such as stainless steel.
The casing 70 covers the proximal end side of the housing 5 and accommodates an insulator 71, a pair of signal terminal fittings 72, a pair of energizing terminal fittings 73, a pair of signal wires 74, and a pair of conducting wires 75 inside. The base end side is airtightly held through a grommet 78.
Ventilation holes 761 and 762 are formed in the casing 70 to communicate the inside of the gas sensor 8 with the atmosphere via the water repellent filter 76.
The water repellent filter 76 is formed of a known water-repellent porous film that blocks liquid and allows gas to pass through, and prevents water droplets from entering when air is introduced as a reference gas.
A pair of signal electrodes 13 and a pair of heater electrodes 14 provided at the base end of the element 1 are formed. The signal terminal fitting 72, the conduction terminal fitting 73, the pair of signal lines 74, and the conduction line 75 are externally provided. It is connected to a not-shown calculation unit and power supply control unit.
The signal terminal fitting 72 and the energizing terminal fitting 73 are made of a known conductive material such as stainless steel or copper, and the distal end side is formed in a spring shape, elastically contacts the signal terminal 13 and the energizing terminal 14, and on the proximal end side. The signal line 74 and the energization line 75 are pressure-bonded to achieve electrical connection between the element 1 and the outside.

The insulator 71 is made of a known insulating material such as alumina, and maintains insulation between the signal terminal fitting 72, the energizing terminal fitting 73 and the casing 70.
Further, the rotation prevention portion 33 provided on the insulator 3 of the assembly 4 and the insulator 71 are fitted to each other, the direction of the electrodes 13 and 14 provided on the element 1 and the pressing direction of the signal terminal fitting 72 and the energizing terminal fitting 73. And match.
The casing 70 is fitted and fixed so as to cover the outer periphery of the large-diameter cylindrical portion 53 of the housing 5.
The caulking portion 77 compresses the grommet 78 and hermetically seals the proximal end side of the casing 70.

  The gas sensor element assembly of the present invention is an oxygen sensor, an air-fuel ratio sensor, an ammonia sensor, a NOx sensor, a PM sensor, a humidity sensor, or the like, in which the sensor element has a rectangular cross section and is formed in a flat plate shape extending in the axial direction. For example, it can be used for various sensors regardless of the fluid to be measured.

1 gas sensor element 10 detecting unit 2 the sealing glass 3 insulator 30 insulating base 31 sensor element insertion hole 32 of glass-filled space 33 anti-rotation unit 4 gas sensor element assembly _{T 20} glass diagonal positions the thickness (thinnest thickness)
T ₂₁ Glass longitudinal thickness _{T 22} Glass short direction thickness _{T 30} insulator diagonal positions the thickness (thinnest thickness)
T ₃₁ insulator longitudinal thickness T ₃₂ insulator transverse thickness (maximum thickness)
T ₃₃ Insulator detent thickness H ₃₃ Detent notch depth L ₂₁ Glass length in length W ₂₂ Glass length in length a ₂ Filling space length b ₂ Filling space length φD ₃ Outside insulation holding member Diameter CP Center point VCP Virtual center point CL ₁ Long side direction center line CL ₂ Short side direction center line P ₂₀ Glass diagonal position end point P ₂₁ Glass longitudinal direction end point P ₂₂ Glass short direction end point P ₃₀ Insulator diagonal position end point P ₃₁ insulator longitudinal direction end point P ₃₂ insulator short direction end point P ₃₃ insulator detent position end point

Claims (6)

A flat gas sensor element (1) that is exposed to the gas to be measured and includes a detection unit (10) that detects a specific component in the gas to be measured, and has a rectangular cross section and extends in the axial direction;
A cylindrical insulator (3) which has a through-hole (31) which is rectangular in cross section and extends in the axial direction on the inside, and which accommodates and holds the gas sensor element in the through-hole;
A cylindrical sealing glass (2) disposed in a glass-filled space (32) partitioned by hollowing out a part of the insulator,
In the gas sensor element assembly in which the sealing glass is melted and solidified, and the gas sensor element and the insulator are hermetically fixed.
By making the cross-sectional shape of the glass filling space a rounded octagonal shape with rounded corners ,
A gas sensor element assembly ( 4a, 4b, 4d ) characterized in that the cross-sectional shape of the sealing glass is a rounded octagonal shape with rounded corners. A flat gas sensor element (1) that is exposed to the gas to be measured and includes a detection unit (10) that detects a specific component in the gas to be measured, and has a rectangular cross section and extends in the axial direction;
A cylindrical insulator (3) which has a through-hole (31) which is rectangular in cross section and extends in the axial direction on the inside, and which accommodates and holds the gas sensor element in the through-hole;
A cylindrical sealing glass (2) disposed in a glass-filled space (32) partitioned by hollowing out a part of the insulator,
In the gas sensor element assembly in which the sealing glass is melted and solidified, and the gas sensor element and the insulator are hermetically fixed.
By making the cross-sectional shape of the glass-filled space an elliptical shape having a flat part, or a rounded polygonal shape of a polygon rather than a square with rounded corners,
The cross-sectional shape of the sealing glass is an elliptical shape having a flat part, or a polygonal rounded polygonal shape rather than a rounded corner,
It said insulator comprises a detent portion formed so as to cut out a portion of its outer peripheral surface in a plane (33), the gas sensor element assembly (4, 4a, 4b) A flat gas sensor element (1) that is exposed to the gas to be measured and includes a detection unit (10) that detects a specific component in the gas to be measured, and has a rectangular cross section and extends in the axial direction;
A cylindrical insulator (3) which has a through-hole (31) which is rectangular in cross section and extends in the axial direction on the inside, and which accommodates and holds the gas sensor element in the through-hole;
A cylindrical sealing glass (2) disposed in a glass-filled space (32) partitioned by hollowing out a part of the insulator,
In the gas sensor element assembly in which the sealing glass is melted and solidified, and the gas sensor element and the insulator are hermetically fixed.
By making the cross-sectional shape of the glass-filled space an elliptical shape having a flat part, or a rounded polygonal shape of a polygon rather than a square with rounded corners,
The cross-sectional shape of the sealing glass is an elliptical shape having a flat part, or a polygonal rounded polygonal shape rather than a rounded corner,
An intersection (insulator diagonal position end point P ₃₀ ) from an intersection (glass diagonal position end point P ₂₀ ) between the extended line of the diagonal of the gas sensor element and the outer periphery of the sealing glass (glass diagonal position end point P ₂₀ ) the distance to an insulator diagonal positions thickness T _30,
An intersection (a glass longitudinal direction end point P ₂₁ ) between a long side direction center line (CL ₁ ) vertically lowered from a central point (CP) of the gas sensor element toward a short side of the gas sensor element and an outer peripheral edge of the sealing glass. ) To the intersection (insulator longitudinal direction end point P ₃₁ ) of the long side direction center line and the outer peripheral edge of the insulator as the insulator longitudinal direction thickness T ₃₁ ,
From the intersection (the glass short direction end point P ₂₂ ) of the short side direction center line (CL ₂ ) vertically lowered from the center of the gas sensor element toward the long side of the sealing glass and the outer peripheral edge of the sealing glass. When the distance to the intersection (insulator short direction end point P ₃₂ ) of the short side direction center line and the outer peripheral edge of the insulator 3 is the insulator short direction thickness T ₃₂ ,
Relationship _{T 30} ≦ T 31 _{<T 32} holds, the gas sensor element assembly (4, 4a, 4b, 4c) An intersection (insulator diagonal position end point P ₃₀ ) from an intersection (glass diagonal position end point P ₂₀ ) between the extended line of the diagonal of the gas sensor element and the outer periphery of the sealing glass (glass diagonal position end point P ₂₀ ) the distance to an insulator diagonal positions thickness T _30,
Intersection (glass longitudinal direction end point P ₂₁ ) of the long side direction center line (CL ₁ ) vertically lowered from the center (CP) of the gas sensor element toward the short side of the gas sensor element and the outer peripheral edge of the sealing glass To the intersection (insulator longitudinal direction end point P ₃₁ ) of the long side direction center line and the outer peripheral edge of the insulator as the insulator longitudinal direction thickness T ₃₁ ,
From the intersection (the glass short direction end point P ₂₂ ) of the short side direction center line (CL ₂ ) vertically lowered from the center of the gas sensor element toward the long side of the sealing glass and the outer peripheral edge of the sealing glass. When the distance to the intersection (insulator anti-rotation position end point P ₃₃ ) between the short side direction center line and the edge of the anti-rotation part is the insulator anti-rotation part thickness T ₃₃ ,
The gas sensor element assembly (4, 4a, 4b) according to claim 2, wherein a relationship of T ₃₀ ≤ T ₃₁ ≤ T ₃₃ is established. A flat gas sensor element (1) that is exposed to the gas to be measured and includes a detection unit (10) that detects a specific component in the gas to be measured, and has a rectangular cross section and extends in the axial direction;
A cylindrical insulator (3) which has a through-hole (31) which is rectangular in cross section and extends in the axial direction on the inside, and which accommodates and holds the gas sensor element in the through-hole;
A cylindrical sealing glass (2) disposed in a glass-filled space (32) partitioned by hollowing out a part of the insulator,
In the gas sensor element assembly in which the sealing glass is melted and solidified, and the gas sensor element and the insulator are hermetically fixed.
By making the cross-sectional shape of the glass-filled space an elliptical shape having a flat part, or a rounded polygonal shape of a polygon rather than a square with rounded corners,
The cross-sectional shape of the sealing glass is an elliptical shape having a flat part, or a polygonal rounded polygonal shape rather than a rounded corner,
The distance from the apex (element diagonal position end point P ₁₀ ) of the gas sensor element to the intersection (glass diagonal position end point P ₂₀ ) between the extended line of the diagonal of the gas sensor element and the outer periphery of the sealing glass is glass. a diagonal position thickness _{T 20,}
From the intersection (element longitudinal direction end point P ₁₁ ) of the long side direction center line (CL ₁ ) vertically lowered from the center (CP) of the gas sensor element toward the short side of the gas sensor element and the short side of the gas sensor element The distance to the intersection (glass longitudinal direction end point P ₂₁ ) of the long side direction center line and the outer peripheral edge of the sealing glass is the glass longitudinal direction thickness T ₂₁ ,
From the intersection (element short direction end point P ₁₂ ) of the short side direction center line (CL ₂ ) vertically lowered from the center of the gas sensor element toward the long side of the gas sensor element and the long side of the gas sensor element When the distance to the intersection (glass short direction end point P ₂₂ ) with the outer periphery of the stop glass is the glass short direction thickness T ₂₂ ,
Relationship _{T 20} ≦ T 21 _{<T 22} holds the gas sensor element assembly (4,4a, 4b, 4c, 4d ) The gas sensor element assembly (4a, 4b) according to claim 1, wherein the glass-filled space and the sealing glass have a cross-sectional shape in which one side of a rounded octagonal shape is opposed to a short side of the gas sensor element.

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