WO2015046363A1

WO2015046363A1 - Gas sensor

Info

Publication number: WO2015046363A1
Application number: PCT/JP2014/075493
Authority: WO
Inventors: 直人小澤; 後藤　常利
Original assignee: 株式会社デンソー
Priority date: 2013-09-25
Filing date: 2014-09-25
Publication date: 2015-04-02
Also published as: CN105814439A; CN105814439B; JP6201568B2; JP2015064273A

Abstract

A gas sensor (GS1) is configured so that a gas sensor element (1) and a housing (2) are sealed by a sealing means (3) comprising, between an outer periphery (10) of the gas sensor element (1) and an inner periphery (20) of the housing (2), a talc based powder filling part (30) and a cylindrical insulator (31) for pressing the powder filling part (30). In a relationship between a sieving particle size (D_SV) of filling powder particles (300) that constitute the powder filling part (30), an element-side gap (GP1) between the inner periphery (310) of the cylindrical insulator (31) and the outer periphery (10) of the gas sensor element (1), and a housing-side gap (GP2) between the outer periphery (311) of the cylindrical insulator (31) and the inner periphery (20) of the housing (2), the element-side gap (GP1) and the housing-side gap (GP2) are set to sizes not more than twice the sieving particle size (D_SV) of the filling powder particles (300).

Description

Gas sensor

The present invention relates to a gas sensor that detects the concentration of a specific gas component in a gas to be measured, and particularly contributes to an improvement in airtightness between a gas sensor element and a housing.

Conventionally, a gas sensor for detecting the concentration of a specific gas component such as oxygen contained in combustion exhaust gas is disposed in a combustion exhaust flow path of an internal combustion engine such as an automobile engine. Then, air-fuel ratio control, temperature control of the exhaust treatment catalyst, and the like are performed based on the detected concentration of the specific gas component.

As such a gas sensor, an oxygen concentration detection element in which a measurement electrode layer in contact with a measurement gas and a reference electrode layer in contact with the atmosphere introduced as a reference gas are provided on the surface of an oxygen ion conductive solid electrolyte such as zirconia Oxygen sensors that measure the oxygen concentration in the measurement gas by detecting the potential difference generated between the two electrodes due to the difference between the oxygen concentration in the measurement gas and the oxygen concentration in the reference gas are widely used. Yes. In addition, an air-fuel ratio sensor that detects the air-fuel ratio of the air-fuel mixture introduced into the internal combustion engine from the concentration of a specific gas component in the combustion exhaust, or the ammonia concentration in the gas to be measured using a hydrogen ion conductive solid electrolyte body Ammonia sensors are also widely used.
Further, in such a gas sensor, it is necessary to ensure airtightness between the gas sensor element and the housing holding the gas sensor element in order to prevent a decrease in detection accuracy due to leakage of the gas to be measured.

Patent Document 1 discloses a detection structure including a detection element for detecting a component to be detected in a gas to be measured, which has a rod-like or cylindrical shape in which a detection portion is formed at a tip portion, and the detection structure. A metal shell mainly disposed on the outside of the body, and a talc main body, and a seal filler layer that fills and seals the gap between the inner surface of the metal shell and the outer surface of the detection structure, A gas sensor is disclosed in which the seal filler layer contains water glass in the range of 2 to 7% by weight.

JP 2000-314715 A

However, as in Patent Document 1, when water glass is added to the seal filling layer to improve the airtightness, water glass is added to the powder filler or the molded body of the filling powder is heated. The man-hour for adjusting the moisture increases, which may increase the manufacturing cost.
In addition, since the sealing property of water glass changes depending on the moisture content, in the gas sensor used in a high temperature environment, the moisture content of the filling portion varies depending on the use situation, and it is impossible to expect stable airtightness. There is also a fear.

On the other hand, gas sensors that detect specific gas components in the combustion exhaust gas of internal combustion engines used for air-fuel ratio control of automobiles and motorcycles are used in harsh environments that are subject to large external vibrations and exposed to a cold cycle. The
For this reason, when fine talc particles having a sieving particle size D _SV of 2 to 30 μm are used in the powder filling portion, there is a possibility that the airtightness may be lowered due to the granulation from the powder filling portion. In order to prevent this, it is necessary to provide a seal packing made of metal or vermiculite, mica, mica molded product, etc. between the cylindrical insulator and the powder filling portion. This has led to an increase in material costs.

Therefore, in view of such circumstances, the present invention is less likely to occur from the powder filling portion even if the seal packing for preventing the filling powder leakage is abolished, and the airtightness of the powder filling portion is reduced while reducing the manufacturing cost. An object of the present invention is to provide a highly reliable gas sensor that is unlikely to deteriorate.

The present invention is a gas sensor for detecting a specific component in a gas to be measured, the gas sensor element, a cylindrical housing for housing and fixing the gas sensor element, an outer peripheral surface of the gas sensor element, and an inner peripheral surface of the housing In the gas sensor formed by providing a sealing means including a powder filling part mainly composed of talc and a cylindrical insulator that presses the powder filling part, the powder filling part is configured Sieving particle size of filled powder particles, element side gap GP1 between the inner peripheral surface of the cylindrical insulator and the outer peripheral surface of the gas sensor element, the outer peripheral surface of the cylindrical insulator and the inner peripheral surface of the housing In relation to the housing side gap, the element side gap and the housing side gap are not more than twice the sieving particle size of the filling powder.

By optimizing the relationship between the sieving particle size, the element-side gap, and the housing-side gap, it is possible to cool and cool without providing a seal packing between the powder filling portion and the cylindrical insulator. Even when exposed to cycles and external vibrations, the powder particles do not fall out of the powder filling part, the internal pressure of the powder filling part is maintained at a constant state, and airtightness is reduced. There is no.
In addition, since it is not necessary to provide seal packing to prevent the pulverization of the filled powder particles, it is possible to reduce the number of parts and the number of assembling steps.

The principal part sectional drawing which shows the outline | summary of the sealing structure of the gas sensor which concerns on this invention. The flowchart which shows the order of a process later about the sealing method of the gas sensor which concerns on this invention. The characteristic diagram of talc used for this invention, Comprising: The schematic diagram which shows a crystal structure. The schematic diagram which shows a change when a pressure acts on large particle size filling powder. The principal part enlarged view which shows the state which has arrange | positioned the powder compact in order to demonstrate the effect of this invention. The principal part enlarged view which shows the state which compressed the powder compact and formed the powder filling part following FIG. 4A. FIG. 3 is an enlarged view of a main part showing a problem when a packed powder of 2 to 30 μm is used as Comparative Example 1. The main part enlarged view which shows the case where a seal | sticker is added to FIG. 5A as the comparative example 2. FIG. The characteristic view which shows the effect of this invention. Sectional drawing which shows the whole gas sensor outline | summary in the 1st Embodiment of this invention. Sectional drawing which shows the whole gas sensor outline in the 2nd Embodiment of this invention. Sectional drawing which shows the principal part of the gas sensor in the 3rd Embodiment of this invention.

The present invention is a gas sensor that detects a specific component in a gas to be measured, and includes a gas sensor element 1, a cylindrical housing 2 that houses and fixes the gas sensor element 1, an outer peripheral surface 10 of the gas sensor element 1, and a housing 2. The present invention relates to a gas sensor in which a gap between the inner peripheral surface 20 is sealed by a sealing means 3 including a powder filling portion 30 mainly composed of talc and a cylindrical insulator 31 that presses the powder filling portion 30. is there.
The gas sensor of the present invention is not particularly limited in application, and can be applied to any of early activation gas sensor GS1, simple gas sensor GS2, and stacked gas sensor GS3, which will be described later.

With reference to FIG. 1, the structure and structure of the powder filling part 30 which is the principal part of this invention are demonstrated. The configuration shown in FIG. 1 is common to all the embodiments described later. In the following description, in order to facilitate understanding of the present invention, as the gas sensor element 1, a so-called cup-type gas sensor in which a pair of electrodes are formed on the inner side and the outer side of a solid electrolyte body formed in a bottomed cylindrical shape. Will be described as an example.

The gas sensor element 1 will be described below with the upper side in FIG. 1 defined as the proximal side and the lower side as the distal side.
A part of the outer periphery of the gas sensor element 1 is formed with an enlarged diameter portion 11 protruding so as to increase in diameter toward the outside.
A cylindrical powder filling portion 30 is formed on the proximal end side of the enlarged diameter portion 11 so as to cover the outer peripheral surface 10 of the gas sensor element 1.
The distal end side of the enlarged diameter portion 11 is in contact with a locking portion 21 whose diameter is reduced so that a part of the inner peripheral surface of the housing 2 is reduced in diameter via a metal spacer ring 32.

The powder filling unit 30 is pressed by a cylindrical insulator 31 formed in a cylindrical shape.
A known ceramic material such as alumina is used for the cylindrical insulator 31.
In the powder filling unit 30, talc powder having a sieving particle size D _SV of 210 μm or more and 710 μm or less is used as the filling powder particles 300.
An element-side gap GP 1 is formed between the inner peripheral surface 310 of the cylindrical insulator 31 and the outer peripheral surface 10 of the gas sensor element 1. Further, a housing side gap GP 2 is formed between the outer peripheral surface 311 of the cylindrical insulator 31 and the inner peripheral surface 20 of the housing 2.
Then, in the relationship among the sieving particle size D _SV of the filling powder particles 300 constituting the powder filling unit 30, the element side gap GP1, and the housing side gap GP2, the element side gap GP1 and the housing side gap GP2 are: In either case, the sieving particle size D _SV of the packed powder particle 300 is less than twice.
The element side gap GP1 and the housing side gap GP2 are set to 0.1 mm or more.

Further, both the element side gap GP1 and the housing side gap GP2 are formed to be 0.1 mm or more, and the assembly of the gas sensor element 1 and the powder filling unit 30 into the housing 2 is facilitated.
The powder filling unit 30 is formed by a manufacturing method described later, and is a powder compact 30MLD formed by pressing the filled powder particles 300 uniaxially into a cylindrical shape. Further, the filled powder particles 300 are pressed through the cylindrical insulator 31 in the space defined between the gas sensor element 1 and the housing 2 to increase the airtightness, thereby forming the powder filling portion 30.

The housing 2 is provided with a wrap caulking portion 22 that elastically presses the cylindrical insulator 31 in the axial direction so that the axial force of the housing 2 can be efficiently transmitted to the cylindrical insulator 31. A shrunk portion 23 formed by heat caulking is provided on the front end side of the enveloping caulking portion 22.
The shrump part 23 is buckled in the axial direction by heat caulking, and applies an axial force in a direction in which the cylindrical insulator 31 is pressed against the powder filling part 30 via the wrapping caulking part 22.
The axial force that presses the powder filling portion 30 forms a repulsive force that acts in all directions in the powder filling portion 30, and the outer peripheral surface 10 of the gas sensor element 1, the proximal end surface of the enlarged diameter portion 11, and the housing 2. The inner peripheral surface 20, the bottom surface of the cylindrical insulator 31, and the powder filling portion 30 are in close contact with each other.

In the powder filling portion 30 of the present invention, the flaky filled powder particles 300 having a large particle size are oriented in layers, and airtightness is maintained.
Further, a metal spacer ring 32 may be interposed between the cylindrical insulator 31 and the wrapping and crimping portion 22.
Further, the distal end side of the enlarged diameter portion 11 provided in the gas sensor element 1 is engaged with an engagement portion 21 having a reduced diameter on a part of the inner periphery of the housing 2 via a metal spacer ring 32.
For the housing 2, a known metal material such as carbon steel, stainless steel, iron, nickel, or an alloy thereof is selected and used according to the use environment.

With reference to FIG. 2, the manufacturing method of the powder filling part 30 which is the principal part of the gas sensor of this invention is demonstrated.
In the powder pretreatment process P1, talc powder used as a filling powder material is pretreated. Specifically, the particle size of talc powder is adjusted to a predetermined particle size range (210 μm or more and 710 μm or less) by sieving, and combustible impurities are removed by heat treatment.
For example, using talc powder having a fine particle size of 100 μm or less as a starting material, an organic binder such as methyl cellulose or an inorganic binder such as primary aluminum phosphate is added, and talc powder is added to a predetermined particle size range ( It may be granulated to 210 μm or more and 710 μm or less.

In the powder molding step P2, a predetermined amount of talc powder is filled in a mold, and a predetermined molding load (for example, 235 N / mm ² or less) is applied to form a cylindrical powder compact 30MLD.
At this time, if the molding pressure is increased, the molding density can be increased, but there is a risk of cracking when taking out from the mold due to the orientation and cleavage of the talc particles.
Further, since it is compressed again after being mounted in the housing 2, it is not necessary to increase the molding load in particular, and it is only necessary to maintain a certain shape so that a predetermined amount of talc can be accurately assembled in the housing 2.
By making the talc molding load smaller than the load when the powder compact 30MLD is assembled and compressed to form the powder filling portion 30, the packing density of the powder filling portion 30 can be finally increased.

Next, in the powder compact assembly / compression process P3, the spacer ring 32, the gas sensor element 1, and the powder compact 30MLD are sequentially mounted in the housing 2, and the powder is obtained using the cylindrical insulator 31 or the pressing jig. The compact 30MLD is compressed to form the powder filling part 30.
At this time, since large talc particles having a sieving particle size D _SV of 210 μm or more are used as the packed powder particles 300, rearrangement of the flaky particles occurs due to slipping and cleaving of the lump particles, resulting in an increase in orientation. By reducing the voids, the porosity of the powder filling portion 30 can be reduced and stabilized.

Furthermore, in this process. (Specifically, for example, 235N / mm ² or more 705N / mm ² or less) load of a predetermined range by load, while achieving a reduction in sufficient porosity, achieve prevention of cracking of the gas sensor element 1 be able to.

Next, in the insulator / spacer ring assembly step P4, the cylindrical insulator 31 and the spacer ring 32 are assembled.
As a matter of course, when the powder compact 30MLD is compressed through the cylindrical insulator 31, only the spacer ring 32 is assembled.
In addition, the spacer ring 32 is not essential, and the spacer ring 32 may be omitted, and in the next step, the wrap and crimp part 22 may be brought into direct contact with the upper surface of the cylindrical insulator 31.

Next, in the cooling step P5, the pressure in the axial direction is applied by the caulking dies M1 and M2 to perform the cold caulking, and the wrapping caulking portion 22 of the housing 2 is tilted toward the cylindrical insulator 31 so that the axial force Is shaped so that it can be efficiently transmitted to the cylindrical insulator 31.
Next, in the heat caulking step P6, the shrump portion 23 is buckled and formed by applying an alternating current to the housing 2 while applying a load to the enveloping caulking portion 22.
By forming the shrump portion 23, it is possible to prevent the axial force from being lost even if it is exposed to a cooling cycle.
In the heat caulking step P6, not only the shrump part 23 is locally heated, but also the entire housing 2 is heated to provide a temperature difference between the housing 2 and the powder filling part 30, thereby increasing the axial force and airtightness. It is also possible to further suppress the decrease in sex.

Here, with reference to FIG. 3A and FIG. 3B, the talc used as a powder filler in this invention is demonstrated.
Talc is a natural mineral composed of magnesium hydroxide and silicate having a composition of (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ), and includes magnesite, dolomite and the like as impurities. This talc has a monoclinic / triclinic crystal structure as shown in FIG. 3A, and exhibits complete cleavage only in a certain direction.
As shown in FIG. 3B, the talc particle 300, which is a large particle size packed powder quantum used in the present invention, is a lump-like particle formed by agglomerating flaky particles in a plurality of layers, and a load in a certain direction is applied. When loaded, the particles slip and cleave, and the flaky particles are oriented in a certain direction.

The effects of the present invention will be described with reference to FIGS. 4A and 4B.
As shown in FIG. 4A, the powder compact 30MLD is formed in a state in which some pores remain as described above, and the directions of the filled powder particles (talc particles) 300 are not aligned.
When this is pressed in the housing 2 via the cylindrical insulator 31 as shown in FIG. 4B, the talc particles 300 are rearranged while sliding, increasing the orientation and reducing the gaps between the particles.
At this time, the talc particles 300 in contact with the inner peripheral surface 20 of the housing 2 tend to be oriented in the axial direction due to friction with the inner peripheral surface, and in the central portion of the powder filling portion 30, parallel to a plane perpendicular to the axis. The tendency to orient in the direction becomes stronger.

In addition, since a predetermined housing side gap GP2 exists between the outer peripheral surface of the cylindrical insulator 31 and the inner peripheral surface 20 of the housing 2, the talc particles 300 at a position exposed to the housing side gap GP2 The axial pressing force from the cylindrical insulator 31 does not act directly, but is indirectly pressed through the talc particles 300 in contact with the bottom surface of the cylindrical insulator 31.
As a result, the talc particles 300 in contact with the cylindrical insulator 31 are covered with the adjacent talc particles 300, or a plurality of talc particles 300 are arranged in the housing-side gap GP2, as indicated by a portion A surrounded by a dotted line in FIG. 4B. At this time, since it bites into the inner peripheral surface 20 of the housing 2, the talc particles 300 play a role as a lid at the position exposed to the housing side gap GP2 to prevent the particles from falling into the housing side gap GP2. It is assumed that there is.

In particular, in the present invention, talc particles having a large particle size with a sieving particle size D _SV of 210 to 710 μm are used as the filling powder particles 300, and the housing-side gap GP2 has a sieving particle size D _SV of Since it is set to be twice or less, a part of the talc particles 300 that are directly pressed against the bottom surface of the cylindrical insulator 31 is in contact with the talc particles 300 exposed in the housing-side gap GP2, Axial force will be transmitted.
In the element-side gap GP1, the filled powder particles 300 do not fall out of the powder filling portion 30 and the airtightness can be stably maintained based on the same principle.
Moreover, the powder compact 30MLD is formed in advance, accommodated in the housing 2, and then compressed again, so that the filled powder particles 300 (talc particles) constituting the powder filler 30 are not completely oriented. Since the orientation direction varies moderately, the difference in thermal expansion coefficient between the axial direction and the orthogonal direction of the gas sensor GS1 does not become extremely large.

Here, referring to FIG. 5A and FIG. 5B, in the same configuration as the gas sensor GS1 of the present invention, fine talc powder having a sieving particle size D _SV of 2 to 30 μm is used as the talc particles 300z that are filled powder particles. The problem when used is described.
As Comparative Example 1, when a talc powder having an average particle size of about 10 μm and a sieving particle size D _{SV in} the range of 2 to 30 μm is used as the packed powder particles 300z as in the gas sensor GSz shown in FIG. 5A. Accordingly, the specific surface area increases, the internal pressure of the powder filling portion 30z is dispersed, and the force for pressing each particle becomes relatively small.

Further, in the portion B covered by the dotted line in FIG. 5A, even if the pressing force from the cylindrical insulator 31 is not transmitted at all or is transmitted through a plurality of adjacent talc particles 300z, each talc particle 300z is The pressing force is reduced.
When the axial force transmitted to the powder filling portion 30z through the cylindrical insulator 31 is weakened due to the thermal expansion of the housing 2, if the external vibration is applied, the filling powder particles 300z are likely to fall apart.
The filled powder particles 300z may be separated from the powder filling portion 30z and leak out from the housing side gap GP2 between the inner diameter of the sealing member housing portion 20 and the outer diameter of the cylindrical insulator 31.

Once the pulverization of the filled powder particles 300z occurs, the internal pressure of the powder filling portion 30z decreases, causing further pulverization of the filled powder particles 300z, and the airtightness of the powder filling portion 30z decreases.
Therefore, as in the gas sensor GSy shown in FIG. 5B, in order to suppress the detachment of the filled powder particles 300z, a metal or vermiculite is formed between the cylindrical insulator 31 and the upper surface of the powder filling portion 30z. Further, it is necessary to provide a seal packing 34 made of mica, mica molded product, etc., resulting in an increase in manufacturing man-hours and an increase in material costs.

Referring to FIG. 6, the test results will be described were performed on the relationship sieve particle size DS _V and the pressing load of the filled powder particles 300 (kN) Porosity (%) and.
As shown in this figure, when talc particles having different particle sizes were used and the load for pressing the cylindrical insulator 31 was changed and the porosity was measured, 10 kN (to 235 N / mm ² at any particle size). In the above case, the porosity is stabilized, and in the case of 30 kN (corresponding to 705 N / mm ² ) or more, there is a possibility that the gas sensor element 1 is cracked, and when the sieving particle size D _SV is 210 to 710 μm, the porosity is most It turned out that it can be lowered.

Note that the porosity can be lowered even when the sieve particle size D _SV is 210 to 1000 μm, but since there is almost no change from the state of the molded body, after assembling the powder molded body 30MLD in the housing 2, Even when pressed through the insulating insulator 31, the filled powder particles 300 do not bite into the element side gap GP 1 and the housing side gap GP 2, and there is a possibility that the filled powder particles 300 may be separated from the powder filling portion 30.
In addition, if the orientation of the filled powder particles 300 is too strong, the difference in thermal expansion coefficient between the axial direction and the radial direction of the gas sensor increases, and the axial force from the housing 2 may be weakened.
Thus, it has been found that the sieving particle size D _SV is desirably in the range of 210 to 710 μm, which causes moderate variation in orientation.

Here, the effects of the present invention will be described with reference to Table 1.
The inventors changed the talc particle diameter _DSV and the talc presser part gap (element side gap GP1, housing side gap GP2), created a plurality of gas sensors, and performed an endurance test corresponding to 240,000 km running. Then, the high temperature airtightness after the durability test was investigated, and the result is shown in Table 1.
As an endurance condition, the housing 2 was heated to 400 ° C. and then immersed in water to apply a thermal stress, and this was repeated 400 times.
Moreover, the evaluation of the high temperature airtightness is that when air is injected from the front end side of the housing 2 under a high temperature environment of 550 ° C. (air pressure 0.4 MPa) and the flow rate is 10 cc / min or less, the airtightness is good. Judgment was made and a round mark was given. When it exceeded 10 cc / min, it was judged that the airtightness was poor, and an x mark was given.
As a result, when the talc pressing portion gap (element side gap GP1, housing side gap GP2) is narrower than 0.1 mm, it is difficult to assemble the cylindrical insulator 31 to the housing 2. Further, the talc presser gap is 0.1 mm or more, so that assembly is easy. Then, talc pressing portion gap (element side gap GP1, the housing-side gap GP2) when more than 2 times the talc sieving particle diameter D _SV is hot airtightness deterioration was observed, talc sieve particle diameter D _SV It was found that good high temperature hermeticity can be maintained when it is 2 times or less.

With reference to FIG. 7A, the gas sensor GS1 in the first embodiment of the present invention will be described.
The gas sensor GS1 is a so-called cup-type gas sensor, and is an early activation type gas sensor that incorporates a heater 18 to achieve early activation.
In the present embodiment, an oxygen sensor that is a typical example of a cup-type sensor will be described as an example. However, in the present invention, the detection target is not limited, and an oxygen sensor, an A / F sensor, a NOx sensor, ammonia The present invention can be applied to any of sensors, hydrogen sensors, and the like.
The gas sensor GS 1 is provided in the measured gas flow path 6, and the detection unit 12 provided at the tip is exposed to the measured gas G.

The gas sensor element 1 uses a known solid electrolyte material such as zirconia having oxygen ion conductivity, and has a reference electrode 121 on the inner surface of a solid electrolyte body 120 formed in a bottomed cylindrical shape, and a measurement electrode 122 on the outer surface. Each of them is provided to constitute a detection unit 12, and a diameter-expanded portion 11 that is expanded to have a large diameter is provided on the base end side of the detection unit 12.
Air is introduced as a reference gas inside the solid electrolyte body 120 and is in contact with the reference electrode 121.
A plus signal line 14S + is connected to the reference electrode 121 via a plus terminal fitting 131S +.

A measurement electrode 122 that is exposed to the gas G to be measured is formed outside the detection unit 12, and the measurement electrode 122 is connected to the negative terminal fitting 131S- at the base end portion 100 of the solid electrolyte body 120. The minus terminal fitting 131S- is connected to the minus signal line 14S-.
The plus terminal fitting 131S + has a crimping portion 130S + connected to one center line 140S of the pair of signal lines 14S and a reference electrode formed on the inner peripheral surface of the solid electrolyte body 120 that exerts a pressing force toward the outer peripheral side. The connecting portion 134 is elastically connected to the contact portion 121, and the heater gripping portion 133 that exerts a pressing force toward the center and grips the heater 18.
The minus terminal fitting 131S- is a crimping part 130S- connected to the other center line 140S of the pair of signal lines 14S, and a measurement standard formed on the outer peripheral surface of the solid electrolyte body 120 that exerts a pressing force toward the center. The connection part 135 is elastically connected to the electrode 123. Housed inside the gas sensor element 1 is a heater 18 having a built-in heating element that generates heat when energized.

The heater 18 includes a known heating element such as tungsten or molybdenum silicide in an insulator such as alumina.
A pair of energizing electrodes 181 for energizing a built-in heating element (not shown) is provided on the proximal end side of the heater 18.
The pair of energizing electrodes 181 is connected to the pair of energizing wires 14H via a pair of energizing terminal fittings 13H.

The energizing terminal fitting 13H is electrically connected to the energizing electrode 181 by elastically contacting the energizing electrode 181 by exerting a pressing force toward the center on the crimping portion 130H connected to the center line 140H of the energizing wire 14H on the proximal end side. And a connecting portion 131H for achieving the above.

The housing 2 is formed in a cylindrical shape using a known metal material such as stainless steel, iron, nickel, alloys thereof, carbon steel, or the like according to the installation environment, and accommodates and fixes the gas sensor element 1 on the inner side. .
Between the inner peripheral surface 20 of the housing 2 and the outer peripheral surface 10 of the gas sensor element 1, a powder filling portion 30 and a cylindrical insulator 31 which are the main parts of the present invention are disposed.
A part of the inner peripheral surface of the housing 2 is reduced in diameter so that the diameter decreases toward the tip, and a locking part 21 that locks the diameter-enlarged part 11 of the gas sensor element 1 is formed.
On the proximal end side of the housing 2, a wrap crimping portion 22 and a shrunk portion 23 are formed to generate an axial force that presses the cylindrical insulator 31 in the distal axial direction.

A cylindrical casing 4 is fixed to the boss portion 24 of the housing 2 so as to cover the proximal end side of the housing and to draw out and fix the signal line and the conductive line.
A screw portion 25 is formed on the outer periphery on the front end side of the housing 2 and is screwed to the gas flow path 6 to be measured.
A hexagonal portion 26 for tightening the screw portion 25 is formed on the outer periphery of the base end side of the housing 2.
A caulking portion 27 for fixing the

cover bodies

50 and 51 is formed at the tip of the housing 2.

In the present embodiment, the sealing unit 3 includes a powder filling unit 30, a cylindrical insulator 31, a spacer ring 32, and a seal ring 33.
Sealing means 3 is provided between the gas sensor GS1, the cylindrical housing 2 that accommodates and fixes the gas sensor GS1, the outer peripheral surface 10 of the gas sensor GS1, and the inner peripheral surface 20 of the housing 2.

An element-side gap GP 1 is formed between the inner peripheral surface 310 of the cylindrical insulator 31 and the outer peripheral surface 10 of the gas sensor element 1. A housing-side gap GP 2 is formed between the outer peripheral surface 311 of the cylindrical insulator 31 and the inner peripheral surface 20 of the housing 2.
Then, in the relationship among the sieving particle size D _SV of the filling powder particles 300 constituting the powder filling unit 30, the element side gap GP1, and the housing side gap GP2, the element side gap GP1 and the housing side gap GP2 are: In either case, the sieving particle size D _SV of the packed powder particle 300 is less than twice.

The detection unit 12 provided on the distal end side of the gas sensor element 1 is covered with

cover bodies

50 and 51.
The

cover bodies

50 and 51 are caulked and fixed by a caulking portion 27 provided at the front end of the housing 2.
The

cover bodies

50 and 51 are appropriately provided with through holes for introducing the gas to be measured G into the

cover bodies

50 and 51 and leading it out.
On the proximal end side of the hexagonal portion 26, a boss portion 24 for fixing the casing 4 is formed.

The casing 4 is made of a metal such as stainless steel, and has a cylindrical portion 40 formed in a stepped cylindrical shape, a vent hole 41 for introducing air, and a caulking portion 42 that seals the base end side of the casing 4. And holding means 43 of the insulator 15.
The casing 4 covers the base end side of the housing 2 and holds a pair of signal lines 14S + and 14S-, a pair of signal terminal fittings 131S + and 131S-, a pair of energization wires 14H, and a pair of energization terminal fittings 13H. .
The pair of signal terminal fittings 131S +, 131S- and the pair of energization wires 14H are accommodated in an insulator 15 made of an insulating material such as alumina so as to be electrically insulated from each other.

The insulator 15 is elastically held by the holding means 43.
The casing 4 is provided with a known water repellent filter 16 that prevents air from entering while air is introduced from the vent hole 41.
On the base end side of the casing 4, there is provided a sealing member 17 made of a heat-resistant elastic member such as silicone rubber or fluoro rubber, and pulling out the pair of signal lines 14S +/− and the conductive line 14H while ensuring airtightness. It has been.
In the present invention, how the pair of signal lines 14S (+/−) and the pair of conductive lines 14H are connected to the gas sensor element 1 inside the casing 4, The manner in which the atmosphere as the reference gas is taken inside, the shape of the insulator 15 and the like can be changed as appropriate, and are not limited to the embodiments.

With reference to FIG. 7B, gas sensor GS2 in the 2nd Embodiment of this invention is demonstrated.
In addition, about the same structure as previous embodiment, the same code | symbol is attached | subjected, About the different part, since the branch number of the alphabet was attached to the corresponding code | symbol, the description about a common part is abbreviate | omitted, Description will be made centering on characteristic portions in the present embodiment.
The gas sensor GS2 is a simple gas sensor that has a simple configuration by eliminating the heater from the gas sensor GS1, and is used in an internal combustion engine such as a motorcycle.
Also in the present embodiment, as shown in FIG. 1, the powder filling portion 30 and the cylindrical insulator 31 are provided between the gas sensor element 1 and the housing 2, and the gaps GP1 and GP2 in the pressing portion are set to be predetermined. By ensuring that the airtightness is within the range, airtightness is ensured.

In the above-described embodiment, the heater 14 that generates heat by energization is provided in order to activate the gas sensor element 1 at an early stage. However, in this embodiment, the activation of the gas sensor element 1A is performed by the gas G to be measured itself. No heat is provided for activation, using the heat it has.
Further, in the embodiment, the reference electrode 121 of the detection unit 12 is connected to the plus signal line 14S + via the plus terminal fitting 131S +, and the measurement electrode 122 is connected to the minus signal line 14S− via the minus terminal fitting 131S−. However, in this embodiment, the measurement electrode 122 provided in the detection unit 12 by eliminating the negative signal line 14S− is grounded to the gas flow path 6 to be measured through the spacer ring 32 and the housing 2. Only the plus signal line 14 connected to the reference electrode 121 via the plus terminal fitting 13A is drawn out.
The positive terminal fitting 13A includes a crimping portion 130A connected to the center line 140 of the signal line 14, a connection portion 131A elastically connected to the reference electrode 121 formed on the inner peripheral surface of the solid electrolyte body, and a solid electrolyte body The contact portion 132A is configured to elastically contact the inclined portion of the inner peripheral surface and suppress axial vibration.
Also in the present embodiment, as shown in FIG. 1, the powder filling portion 30 and the cylindrical insulator 31 are provided between the gas sensor element 1A and the housing 2, and the gaps GP1 and GP2 in the pressing portion are set to be predetermined. By ensuring that the airtightness is within the range, airtightness is ensured.

With reference to FIG. 7C, a gas sensor GS3 according to a third embodiment of the present invention will be described.
In the above embodiment, a so-called cup-type gas sensor has been shown. However, the present invention can also be applied to a so-called laminated gas sensor, and this embodiment is an example.

In the embodiment, the powder filling portion 30 and the cylindrical insulation are provided between the enlarged diameter portions 11 and 11A obtained by enlarging a part of the solid electrolyte body constituting the

gas sensor elements

1 and 1A and the inner peripheral surface 20 of the housing 2. The sealing means 3 including the body 31, the spacer ring 32, and the seal ring 33 is interposed between the latching portion 21 of the housing 2, the wrapping caulking portion 22, and the shrump portion 23, and an axial force is applied. However, in the gas sensor GS3 in the present embodiment, as shown in FIG. 7C, the tubular housing 2, the gas sensor element 1B disposed in the housing 2, and the insulator constituting the gas sensor element 1B with the inner side surface 20 of the housing 2 The housing 2 is wrapped with a sealing means 3 including a powder filling portion 30, a cylindrical insulator 31, a spacer ring 32, and a seal ring 33 interposed between the outer surface 10B and the outer surface 10B. Clamping portion 22, Shurunpu portion 23, the locking portion 21, by holding the enlarged diameter portion 11B which is enlarged a portion of the insulator of the gas sensor element 1B, holding the airtightness by applying an axial force.

The detection unit 12B in the present embodiment is constituted by a so-called laminated gas sensor element, and is formed in a flat bar shape by laminating a plurality of ceramic sheets.
The detection unit 12B is inserted into a cylindrical insulator made of alumina or the like and is held by a sealing unit 35 made of glass or the like.

Also in the present embodiment, as shown in FIG. 1, the powder filling portion 30 and the cylindrical insulator 31 are provided between the gas sensor element 1B and the housing 2, and the gaps GP1 and GP2 in the pressing portion are set to be predetermined. By ensuring that the airtightness is within the range, airtightness is ensured.
The specific configuration of the gas sensor element 1B is not particularly limited, and the detection unit 12B is formed with a detection cell, a heat generation unit, and the like according to a required detection function.
In addition, the detection target of the gas sensor in the present embodiment is not limited to the gas component, but may be PM, moisture, or the like.

DESCRIPTION OF SYMBOLS 1 Gas sensor element 2 Housing 3 Sealing means 10 Element outer peripheral surface 20 Housing inner peripheral surface 30 Powder filling part 300 Filling powder particle (talc particle)
31 Tubular insulator 310 Tubular insulator outer peripheral surface 311 Tubular insulator outer peripheral surface GS1, GS2, GS3 Gas sensor D _SV sieving particle size GP1 Element side gap GP2 Housing side gap

Claims

A gas sensor for detecting a specific component in a gas to be measured, the gas sensor element (1), a cylindrical housing (2) for housing and fixing the gas sensor element (1), and an outer peripheral surface of the gas sensor element (1) (10) and the inner peripheral surface (20) of the housing (2), a powder filling part (30) mainly composed of talc, and a cylindrical insulator for pressing the powder filling part (30) (31) In the gas sensor (GS1, GS2, GS3) formed by providing the sealing means (3) including the sealing,
Sieving particle size D SV of filled powder particles (300) constituting the powder filling portion (30);
An element side gap GP1 between the inner peripheral surface (310) of the cylindrical insulator (31) and the outer peripheral surface (10) of the gas sensor element (1);
In the relationship between the outer peripheral surface (311) of the cylindrical insulator (31) and the housing side gap GP2 between the inner peripheral surface (20) of the housing (2),
The element side gap GP1 and the housing side gap GP2 are
Gas sensors (GS1, GS2, GS3), wherein the sieving particle size D SV of the filled powder particles (300) is not more than twice.
The gas sensor (GS1, GS2, GS3) according to claim 1, wherein the sieving particle size D SV is 210 µm or more and 710 µm or less.
The gas sensor (GS1, GS2, GS3) according to claim 1 or 2, wherein the element side gap GP1 and the housing side gap GP2 are 0.1 mm or more.
The filled powder particles (300) are uniaxially pressed to form a powder molded body (30MLD) molded into a cylindrical shape, and further, in the space defined between the gas sensor element (1) and the housing (2), The gas sensor according to any one of claims 1 to 3, wherein the powder filling portion (30) is formed by pressing through a cylindrical insulator (31) to enhance airtightness.
The gas sensor according to any one of claims 1 to 4, wherein the housing (2) includes a wrap crimping portion (22) that elastically presses the cylindrical insulator (31) in the axial direction.
The gas sensor according to any one of claims 1 to 4, wherein the housing (2) includes a shrump portion (23) for elastically pressing the cylindrical insulator (31) in the axial direction.