WO2015076131A1

WO2015076131A1 - Gas sensor

Info

Publication number: WO2015076131A1
Application number: PCT/JP2014/079668
Authority: WO
Inventors: 翔太郎森; 欣二宝平; 直人小澤
Original assignee: 株式会社デンソー
Priority date: 2013-11-20
Filing date: 2014-11-10
Publication date: 2015-05-28
Also published as: CN105745532B; JP6287098B2; CN105745532A; JP2015099110A

Abstract

A gas sensor provided with a terminal fitting (1) having a cylindrical portion for thermal insulation layer formation (15) that is exposed from the proximal end side of a gas sensor element (3), an element side abutting portion (14) that abuts a flat surface part (34) that is perpendicular to the longitudinal axis of a solid electrolyte body (300), a proximal end side abutting portion (16) that abuts the bottom surface (40) of a grommet, a conduction part (12) for facilitating conduction with a reference electrode layer (320), and a crimping part (10) for crimping and fixing a core wire (20) of a signal line, wherein a thermal insulation space part (SP_TI) is provided that separates the grommet (4) and the gas sensor element (3) and communicates with a ventilation hole (52).

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.

Conventionally, a gas sensor for detecting the concentration of a specific gas component such as oxygen contained in combustion exhaust gas has been provided in a combustion exhaust passage of an internal combustion engine such as an automobile engine, and the air-fuel ratio is determined by the detected concentration of the specific gas component. Control and temperature control of exhaust treatment catalyst are performed.

As such a gas sensor, a solid electrolyte body in which a solid electrolyte material having oxygen ion conductivity such as zirconia is formed in a bottomed cylindrical shape, a measurement electrode layer in contact with a gas to be measured on its outer peripheral surface side, and an inner peripheral surface thereof It has a so-called cup-shaped detection element consisting of a reference electrode layer in contact with the atmosphere introduced as a reference gas on the side, and is generated between both electrodes due to the difference between the oxygen concentration in the measured gas and the oxygen concentration in the reference gas An oxygen sensor that measures the oxygen concentration in the gas under measurement by detecting the potential difference, 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, hydrogen An ammonia sensor or the like that detects an ammonia concentration in a gas to be measured using an ion conductive solid electrolyte is widely used.

In recent years, such a gas sensor has been adopted for an engine for a motorcycle. In a motorcycle engine, a space for mounting a gas sensor is limited, and it is disposed at a position where the temperature of combustion exhaust gas to be measured is high, without using a heater for activating the solid electrolyte body, By adopting a structure that uses exhaust heat, both manufacturing cost reduction and downsizing are achieved. For this reason, the gas sensor for motorcycles is exposed to severe thermal stress more than the gas sensor for passenger cars, and is used in harsh environments such as intense vibration from outside and water, etc. In addition, there is a high demand for improving vibration resistance and durability.

Patent Document 1 discloses a conventional gas sensor, and forms a current path by extending from a cylindrical detection element, a metal shell for holding the detection element, a terminal metal fitting electrically connected to the detection element, and the terminal metal fitting. A lead wire to be inserted, a separator through which the lead wire is inserted, an inner cylinder that surrounds the periphery of the separator, a grommet that is disposed in a cylindrical hole of the inner cylinder and through which the lead wire is inserted, and is disposed radially outside the inner diameter. And a filter having a filter interposed between the inner cylinder and a separator sandwiched between the detection element and the grommet.

JP 2013-104832 A

However, in the conventional gas sensor as disclosed in Patent Document 1, a ceramic insulator having a relatively high thermal conductivity such as alumina is used as a separator. For this reason, the grommet is heated by using the separator as a heat conductor from the detection part provided at the tip of the gas sensor exposed to the gas to be measured at several hundred degrees C or higher. In particular, in the structure in which the separator is sandwiched between the detection element and the grommet as in the gas sensor of Patent Document 1, since the bottom surface of the grommet is in contact with the separator in a wide range, the amount of heat received from the separator increases, and the grommet There is a risk of thermal degradation.

If the elasticity of the grommet is lost due to thermal deterioration, the holding strength of the terminal fitting is reduced, and a gap is created between the terminal fitting and the detection element. In this state, when external vibration is applied, the continuity between the terminal fitting and the detection element is easily interrupted, leading to a decrease in the conduction reliability of the terminal fitting. Moreover, in the conventional gas sensor, it is possible to suppress the thermal degradation of the grommet by lengthening the separator and increasing the distance from the heat source, but this has been a factor that hinders downsizing of the gas sensor. .

Therefore, in view of such circumstances, the present invention suppresses the thermal degradation of the grommet while reducing the size, and further impairs the conduction reliability between the terminal fitting and the detection element against external vibration. An object of the present invention is to provide a gas sensor having an excellent structure without any problem.

The gas sensor (8, 8a to 8i) of the present invention includes a terminal fitting (1, 1a to 1h), a signal line (2), and gas sensor elements (3, 3c, 3d, 3e), a grommet (4), a casing (5), and a housing (7). The gas sensor elements (3, 3c, 3d, 3e) are formed at least on a bottomed cylindrical solid electrolyte body (300) having conductivity with respect to specific ions, and an outer peripheral surface (301) of the solid electrolyte body. The measurement electrode layer (310) in contact with the gas to be measured (91) and the reference electrode layer (320) formed on the inner peripheral surface (321, 321c, 321e) of the solid electrolyte body and in contact with the atmosphere introduced as the reference gas ) Is included. The signal line (2) is intended to connect the gas sensor element to the outside. The terminal fittings (1, 1a to 1h) are intended to connect the gas sensor element and the signal line. The housing (7) accommodates the gas sensor element, and disposes and fixes the detection unit in the gas to be measured. The cylindrical casing (5) covers the base end side of the gas sensor element together with the terminal fitting, and includes a vent hole (52) for introducing air into the inside. The grommet (4) holds the signal line connected to the terminal fitting while hermetically sealing the base end side of the casing. Further, the gas sensor (8, 8a to 8i) is provided with a water repellent filter (61) made of a porous fiber structure that is provided to face the vent hole and allows gas permeation but prevents liquid permeation. It has been done. Thus, in the gas sensor (8, 8a to 8i) for detecting a specific component in the gas to be measured, the terminal fitting is formed in a cylindrical shape, and is exposed at a predetermined length from the base end side of the gas sensor element. The heat insulating layer forming cylindrical parts (15, 15b to 15e, 15g) and the flat part (34, 34e) perpendicular to the longitudinal axis of the solid electrolyte body on the tip side of the heat insulating layer forming cylindrical parts The element side contact portion (14, 14c, 14e) that contacts, or the element side inclined contact portion (14d) that contacts the inclined surface (34d) including the vertical component, and the base end of the tubular portion for forming the heat insulation layer A base end side contact portion (16, 16c, 16e) that contacts the bottom surface (40) of the grommet on the side, and a conductive portion (12, 12b to 12e) that elastically contacts the reference electrode layer to achieve conduction. 12h) and crimping the core wire (20) of the signal wire Comprising crimping portion with a constant and (10,10g, 10h), the. Further, the gas sensor (8, 8a to 8i) is provided with a heat insulating space ( _SPTI ) communicating with the vent hole while separating the grommet and the gas sensor element. .

In the structure of the gas sensor according to the present invention, a heat insulation space is formed between the gas sensor element and the grommet by the tubular portion for heat insulation layer formation, and an air layer having high heat insulation is formed in the heat insulation space. In addition, the atmosphere is easily exchanged with the external atmosphere via the vents. Furthermore, even if the gas sensor has a simple structure that activates the solid electrolyte body and detects the specific gas component by the high temperature of the gas to be measured (for example, exhaust gas), the heat insulating space is formed. The heat conduction to the bottom surface of the grommet is cut off and the grommet is not exposed to high temperatures. Therefore, unlike the conventional gas sensor structure, an insulator having high thermal conductivity such as alumina serves as a heat medium, and the bottom surface of the grommet is directly heated to cause no thermal degradation.

In addition, in the structure of the gas sensor according to the present invention, the heat insulating space functions also as an electrical insulating layer between the casing and the terminal fitting, so that it is not necessary to use an insulator for holding the terminal fitting. Well, that is, it can be abolished, which can reduce the overall size of the gas sensor. Since the tubular portion for forming the heat insulation layer of the terminal fitting is elastically sandwiched between the gas sensor element and the grommet, electrical continuity between the terminal fitting and the detection element is also provided against external vibration. Therefore, it is possible to provide a highly reliable gas sensor with excellent electrical continuity.

It is a longitudinal cross-sectional view which shows the whole outline | summary of the gas sensor 8 in the 1st Embodiment of this invention. (A) A perspective view showing an outline of the terminal fitting 1 that is a main part of the gas sensor 8 of FIG. 1, (B) a half sectional view of the terminal fitting 1 shown in FIG. 2A, (C) CC in FIG. 2 (B). , DD, and EE, and a cross-sectional view of the cross-section along the line CC, DD, and EE in FIG. It is sectional drawing shown. It is principal part sectional drawing for demonstrating the effect of the gas sensor 8 shown in FIG. (A) The perspective view which shows the outline | summary of the terminal metal fitting 1b of the gas sensor 8b which concerns on the 2nd Embodiment of this invention, (B) The half sectional view of the terminal metal fitting 1b shown to FIG. 4 (A), (C) This invention. It is principal part sectional drawing for demonstrating the effect of the gas sensor 8b which concerns on 2nd Embodiment. (A) The perspective view which shows the outline | summary of the terminal metal fitting 1c in the gas sensor 8c which concerns on the 3rd Embodiment of this invention, (B) The half sectional view of the terminal metal fitting 1c shown to FIG. 5 (A), (C) The terminal metal fitting 1c. The principal part expanded sectional view which shows the relationship between the sensor element 3c and (D) principal part sectional drawing for demonstrating the effect of the gas sensor 8c which concerns on the 3rd Embodiment of this invention. (A) The perspective view which shows the outline | summary of the terminal metal fitting 1d of the gas sensor 8d which concerns on the 4th Embodiment of this invention, (B) The half sectional view of the terminal metal fitting 1d shown to FIG. 6 (A), (C) The terminal metal fitting 1d. The principal part expanded sectional view which shows the relationship between the sensor element 3d and (D) principal part sectional drawing for demonstrating the effect of the gas sensor 8d which concerns on the 4th Embodiment of this invention. (A) The perspective view which shows the outline | summary of the terminal metal fitting 1e of the gas sensor 8e which concerns on the 5th Embodiment of this invention, (B) The half sectional view of the terminal metal fitting 1e shown to FIG. 7 (A), (C) The terminal metal fitting 1e. The principal part expanded sectional view which shows the relationship between the sensor element 3e, and (D) principal part sectional drawing for demonstrating the effect of the gas sensor 8e of 5th Embodiment which concerns on this invention. (A) The perspective view which shows the outline | summary of the terminal metal fitting 1f of the gas sensor 8f which concerns on the 6th Embodiment of this invention, (B) The half sectional view of the terminal metal fitting 1f shown to FIG. 8 (A), (C) This invention. It is principal part sectional drawing for demonstrating the effect of the gas sensor 8f which concerns on 6th Embodiment of this. (A) The perspective view which shows the outline | summary of the terminal metal fitting 1g of the gas sensor 8g which concerns on the 7th Embodiment of this invention, (B) The half sectional view of the terminal metal fitting 1g shown to FIG. 9 (A), (C) This invention. It is principal part sectional drawing for demonstrating the effect of the gas sensor 8g of 7th Embodiment which concerns on this. (A) The perspective view which shows the outline | summary of the terminal metal fitting 1h of the gas sensor 8h which concerns on the 8th Embodiment of this invention, (B) The half sectional view of the terminal metal fitting 1h shown to FIG. 10 (A), (C) This invention. It is principal part sectional drawing for demonstrating the effect of the gas sensor 8h which concerns on 8th Embodiment of this. It is a longitudinal cross-sectional view which shows the outline | summary of the gas sensor 8i which concerns on the 9th Embodiment of this invention.

(First Embodiment) With reference to FIGS. 1, 2A, 2B, (C), (D) and FIG. 3, the configuration of a gas sensor 8 according to the first embodiment of the present invention, Operations and effects will be described. In the following description, the side exposed to the gas to be measured of the gas sensor 8 is referred to as the distal end side, and the side from which the signal line 2 is drawn out is referred to as the proximal end side. The gas sensors 8, 8b to 8i according to the present invention use the combustion exhaust gas or the like of an internal combustion engine such as an automobile engine or a motorcycle engine as the measured gas 91, and at the position close to the exhaust pipe of the internal combustion engine, the measured gas flow path wall 90 It is a so-called heaterless type gas sensor that detects a specific component in the measurement gas by activating the solid electrolyte body using the high temperature of the measurement gas 91. In order to facilitate understanding of the present invention, in the following description, an oxygen sensor using a solid electrolyte material having oxygen ion conductivity such as zirconia will be described as an example. Instead of using a proton conductor or the like as the solid electrolyte material constituting the gas sensor element 3 depending on the detection target, or for detecting not only the oxygen concentration but also the air-fuel ratio, NOx, ammonia, etc. Is also possible.

The gas sensor 8 in the first embodiment includes at least the terminal fitting 1, the signal line 2, the gas sensor element 3, the grommet 4, the casing 5, and the housing 7. The gas sensor element 3 is a so-called cup-type element, and a solid electrolyte body 300 formed of a solid electrolyte material having conductivity with respect to specific ions in a bottomed cylindrical shape having one end closed and the other end opened; Formed on the outer peripheral surface 301, the measurement electrode layer 310 that flows through the measured gas flow path and contacts the measured gas 91 that has entered from the opening 77 of the cover body 76, and the inner peripheral surface 321 of the solid electrolyte body 300. The detection unit 30 includes a reference electrode layer 320 in contact with the atmosphere introduced into the reference gas chamber 32 as a reference gas.

The measurement electrode layer 310 and the reference electrode layer 320 are each formed of a known porous electrode made of platinum or a platinum alloy. A reference gas chamber 32 into which air is introduced as a reference gas is defined inside the solid electrolyte body 300. In the middle of the solid electrolyte body 300 on the base end side of the detection unit 30, a large diameter part 31 is formed with the diameter enlarged so as to increase in diameter toward the outer peripheral side. Further, on the base end side of the large-diameter portion 31, a signal extraction portion 33 that is formed in a cylindrical shape and is connected to the outside is formed.

The reference electrode layer 320 is connected to the signal line 2 connected to the outside by the terminal fitting 1. The measurement electrode layer 310 is electrically connected to the measured gas flow channel wall 90 via the housing 7 and is in a grounded state. The gas sensor 8 includes a terminal fitting 1, a signal line 2, a gas sensor element 3, a grommet 4, a casing 5, and a housing 7.

The terminal fitting 1, which is the main part of the present invention, is made of stainless steel having excellent heat resistance, electrical conductivity, and elasticity. The signal line 2 is intended for electrical connection between the gas sensor element 3 and an external device. The terminal fitting 1 is intended to connect the gas sensor element 3 and the signal line 2.

The terminal fitting 1 in the present embodiment includes a crimping portion 10 that crimps and fixes the core wire 20 of the signal line 2, a conduction portion 12 that establishes conduction with the reference electrode layer 320, and a bottom surface 40 of the grommet 4 and the gas sensor element 3. It is constituted by a connecting

portion

11, 13 for connecting the heat insulating layer forming the tubular portion 15 for forming the heat-insulating space portion SP _TI to. The heat insulating layer forming cylindrical portion 15 is formed in a partially cut-out cylindrical shape having a larger diameter than the inner diameter of the inner peripheral surface 321 of the solid electrolyte body 300 and extending in the axial direction with a C-shaped cross section. The heat insulating layer forming cylindrical portion 15 is formed so as to be exposed at a predetermined length from the base end side of the gas sensor element 3 when the terminal fitting 1 is attached to the solid electrolyte body 300.

The element side abutting portion 14 is formed so as to abut on the flat portion 34 perpendicular to the longitudinal axis of the solid electrolyte body 300 on the distal end side of the heat insulating layer forming cylindrical portion 15. In the present embodiment, the end surface on the base end side of the solid electrolyte body 300 is a flat portion 34.

The proximal end contact portion 16 is formed so as to contact the bottom surface 40 of the grommet 4 on the proximal end side of the heat insulating layer forming cylindrical portion 15. That is, the base end side contact portion 16 corresponds to a collar portion at the base end side end portion of the terminal fitting 1. Moreover, the base end side contact part 16 in this embodiment is formed in the shape of a collar protruding in radial direction. By using the hook shape, it is possible to disperse the pressure that presses the bottom surface 40 of the grommet 4, and to prevent the local pressure from acting on the grommet 4 and causing cracks.

The conducting portion 12 has a slightly larger diameter than the inner diameter of the inner peripheral surface 321 of the solid electrolyte body 300, and is formed in a partially-notched cylindrical shape having a C-shaped cross section and extending in the axial direction. Since the conducting portion 12 is urged in the outer diameter direction, when the conducting portion 12 is attached to the solid electrolyte body 300 while reducing the diameter, the conducting portion 12 is elastically brought into contact with the reference electrode layer 320 to achieve conduction. It can be done.

In the present embodiment, the tapered portion 17 is provided so that a part of the conducting portion 12 is tapered at the tip. By forming the tapered portion 17, when the terminal fitting 1 is attached to the solid electrolyte body 300, the tip of the tapered portion 17 functions as an insertion guide, and the diameter of the tapered portion 17 is reduced within the inner peripheral surface 321 of the solid electrolyte body 300. It can be inserted smoothly. The crimping portion 10 is for crimping and fixing the core wire 20 of the signal line 2. In the present embodiment, the crimping portion 10 is provided on the distal end side of the conducting portion 12, and the size of the terminal fitting 1 exposed from the gas sensor element 3 can be reduced, and the gas sensor 8 can be downsized.

When the terminal fitting 1 is attached to the solid electrolyte body 300, the heat insulating layer forming cylindrical portion 15 is exposed from the base end side of the solid electrolyte body 300, and the grommet 4 and the gas sensor element 3 are separated from each other. forming an insulating space portion _{SP TI} which communicates with the vent hole 52. In addition, by providing the connecting

portions

11 and 13 with an inclination, as shown in FIG. 2C, the crimping portion 10, the conducting portion 12, and the heat insulating layer forming cylindrical portion 15 are arranged so as to be concentric. Alternatively, as shown as modified example 1a in FIG. 2D, the position of the heat insulating layer forming cylindrical portion 15 may be eccentrically arranged so as to coincide with the outer peripheral edge of the conducting portion 12. . Further, FIGS. 1 to 3 show an example in which the outer diameter of the conductive portion 12 is formed smaller than the outer diameter of the tubular portion 15 for forming the heat insulating layer, but the outer diameter of the conductive portion 12 is used for forming the heat insulating layer. It is formed so as to have the same diameter as the outer diameter of the cylindrical portion 15 and press-fitted into the solid electrolyte body 300 while reducing the diameter so as to be in close contact with the reference electrode layer 320 formed on the inner peripheral surface of the solid electrolyte body 300. Also good.

The detection unit 30 includes a solid electrolyte body 300, a reference electrode layer 320 formed on the inside thereof and in contact with the atmosphere introduced as a reference gas, and formed on the outside thereof. The measurement electrode layer 310 is in contact with the measurement gas 91 entering from the opening 77, and is protected by the cover body 76. In the measurement gas flow path through which the measurement gas 91 (for example, exhaust gas) flows. It is arranged.

The grommet 4 is made of a heat-resistant elastic member such as fluorine rubber, silicone rubber, urethane rubber, etc., is formed in a cylindrical shape, and the signal line 2 is inserted and held inside. The grommet 4 is inserted into the proximal end side opening of the casing 5 together with the proximal end portion of the water repellent filter 61, and is sealed and fixed by the caulking portion 54.

The casing 5 is formed of a stepped cylindrical metal material such as iron, nickel, and stainless steel. The large diameter portion 50 formed on the front end side of the casing 5 is fitted to the boss portion 74 of the housing 7 and is sealed and fixed by a welding portion 56 such as laser welding. A plurality of vent holes 52 are formed in the side surface of the middle diameter portion 51 of the casing 5 to introduce air into the casing 5. The vent hole 52 is provided with a water repellent filter 61 that allows gas to pass therethrough and prevents liquid from entering.

The housing 7 is made of a known heat-resistant metal material such as stainless steel, iron, nickel, iron-nickel alloy or the like, is formed in a cylindrical shape, and accommodates the gas sensor element 3 inside. A screw part 75 is formed on the outer periphery of the front end side of the housing 7, and the screw part 75 is fixed to the gas flow channel wall 90 to be measured, and the detection unit 30 covered with a cover body 76 having a plurality of openings 77 is provided. Arranged and fixed in a measurement gas flow path through which the measurement gas 91 flows. A boss portion 74 is formed on the base end side of the housing 7, and a large diameter portion 50 formed on the distal end side of the casing 5 is attached to the boss portion 74 to form a fixing portion obtained by fixing means such as laser welding, The gas sensor element 3 is fixed in an airtight manner.

The powder filling member 62 is formed by annularly forming a heat-resistant ceramic powder such as talc powder. The insulating sealing member 63 is formed by annularly forming a heat-resistant ceramic sintered body such as alumina. The sealing member (seal member) 64 is made of a stainless steel or the like formed of a metal material having high heat resistance in an annular shape.

The large-diameter portion 31 in which the diameter of the gas sensor element 3 is enlarged is formed by an element locking portion 71 and a caulking portion 73 formed on the housing 7 via a powder filling member 62, an insulating sealing member 63, and a sealing member 64. Airtightness is secured by pinching and applying axial force. A part of the gas sensor element 3 is exposed from the base end side of the housing 7 to constitute a signal extraction part 33.

A cylindrical elastic member 60 is fitted on the outer peripheral surface 331 of the signal extraction portion 33, and is caulked and fixed together with the distal end portion of the water repellent filter 61 by the caulking portion 55 of the casing 5 with the outer peripheral surface 331 of the signal extraction portion as the back. ing.

The water repellent filter 61 is made of a porous fiber structure made of a fluororesin such as polytetrafluoroethylene and formed in a cylindrical shape. The water repellent filter 61 is provided at a position facing the vent hole 52, and has a function of allowing gas to pass from the vent hole 52 to the inside of the sensor and blocking liquid from passing therethrough.

Between the casing 5 and the signal extraction part 33 of the gas sensor element 3, the front end side of the water repellent filter 61 and the cylindrical elastic member 60 are interposed, and the outer surface 331 of the signal extraction part 33 is backed. A portion of the front end side of the medium diameter portion 51 is compressed toward the center in the radial direction, and a caulking portion 55 is provided and fixed. In the present embodiment, the cylindrical elastic member 60 is disposed on the inner side of the gas sensor than the water repellent filter 61.

The front end side of the water repellent filter 61 is compressed and densified by the caulking portion 55, thereby blocking liquid intrusion from the end portion on the front end side of the water repellent filter 61. Further, a part of the base end side of the middle diameter portion 51 of the casing 5 is compressed toward the center in the radial direction, and a caulking portion 54 is further provided, and the base end side of the water repellent filter 61 is connected to the grommet 4 and the signal. It is fixed together with the wire 2 by caulking.

The base end side of the water-repellent filter 61 is compressed and densified by the caulking portion 54 of the casing 5 to block moisture from entering from the base end side. The grommet 4 and the cylindrical elastic member 60 are made of heat-resistant elastic members such as fluoro rubber and silicone rubber, and generate a reaction force that elastically presses the

caulking portions

54 and 55 from the inside, thereby producing a water repellent filter 61. So that no gap is generated between them.

In the present invention, the shape of the cover body 76 and the position, size, number, etc. of the opening 77 are not particularly limited, and can be appropriately changed according to the application. The present invention is not limited to a single one as shown in FIGS. 1 to 3, and a plurality of cover bodies arranged concentrically may be used.

In the gas sensor 8 of the present invention, for example, as shown in FIG. 3, the element side abutment that is the front end side end surface of the cylindrical portion of the terminal fitting is in contact with the flat portion 34 that is the upper surface of the open end of the solid electrolyte body 300 of the gas sensor element 3. The base 14 comes into contact with the base end side contact portion 16 (the flange on the base end side end of the terminal fitting 1) comes into contact with the bottom surface 40 of the grommet 4, and the base end of the gas sensor element 3 and the grommet 4 An air heat insulating space _SPTI is formed between the air repellent filter 61 and the air vent 52 serving as an air introduction hole. This air heat insulation space part _SPTI functions as a heat insulation layer. The conventional gas sensor is provided with an insulator such as alumina having a high thermal conductivity, but the gas sensor 8 of the present invention is not provided with an insulator such as alumina having a high thermal conductivity, so that the temperature is high. The heat of the gas to be measured is not transmitted to the bottom surface 40 of the grommet 4 through the insulator, the thermal deterioration is suppressed, and the conduction reliability between the conduction portion 12 of the terminal fitting 1 and the reference electrode layer 320 is improved. An excellent gas sensor 8 can be realized.

In the gas sensor element 3, the detection unit 30 provided on the tip side is exposed to the high temperature gas 91 to be measured, the solid electrolyte body 300 is activated by the high temperature of the gas to be measured 91, exhibits oxygen ion conductivity, The electromotive force generated by the difference between the oxygen concentration in the measurement gas and the oxygen concentration in the atmosphere introduced into the reference gas chamber 32 is transmitted to a detection circuit provided outside via the signal line 2 and this detection is performed. By detecting the electromotive force with the circuit, the oxygen concentration in the gas to be measured can be detected.

(Second Embodiment) A gas sensor 8b according to a second embodiment of the present invention will be described with reference to FIGS. 4 (A), (B) and (C). In the description of each embodiment described below, the same reference numerals are given to the same components as those of the gas sensor 8 in the first embodiment, and different parts are indicated by alphabetic symbols (for example, 1b). Etc.), the description of the same part will be omitted, and the characteristic part in each embodiment will be mainly described.

In the terminal fitting 1b, which is the main part of the gas sensor 8b according to the second embodiment, as shown in FIGS. 4A and 4B, the heat insulating layer forming cylindrical portion 15b extends in the axial direction with a C-shaped cross section. It is formed in the shape of a notch. The outer diameter of the heat insulating layer forming cylindrical portion 15 b is formed so as to be larger than the inner peripheral diameter of the solid electrolyte body 300.

Further, as shown in FIG. 4C, the conducting portion 12b is also formed in a cut-out cylindrical shape having a C-shaped cross section and extending in the axial direction. Furthermore, the outer diameter of the conducting portion 12b is formed to be slightly larger than the inner peripheral diameter of the solid electrolyte body 300, and is press-fitted inside the solid electrolyte body 300 in a reduced diameter state.

The conduction portion 12b elastically presses the reference electrode layer 320 outward to ensure conduction. Also in the gas sensor 8b according to the present embodiment, the element-side contact portion 14 is in contact with the end surface on the base end side of the solid electrolyte body 300 as the flat surface portion 34, and is not formed in a bowl shape on the bottom surface 40 of the grommet 4. The end side contact portion 16b is in contact. Also in the gas sensor 8b according to this embodiment, as in the embodiment, the insulating space portion SP _TI, thermal degradation of the grommet 4 is suppressed. Furthermore, in this embodiment, the structure is simplified and the manufacturing cost is further reduced by adopting a configuration in which the collar portion and the inclined surface are eliminated.

(Third Embodiment) A gas sensor 8c according to a third embodiment of the present invention will be described with reference to FIGS. 5A, 5B, 5C, and 5D. In the gas sensor element 3c which is a main part of the gas sensor 8c according to the present embodiment, the signal extraction portion 33c provided on the base end side of the solid electrolyte body 300 has a small diameter at the tip end side as the flat surface portion and the base end. A stepped portion 34c whose diameter is changed stepwise is provided so that the side becomes larger in diameter.

Furthermore, in the terminal fitting 1c of the gas sensor 8c according to the present embodiment, in order to use a part of the heat insulating layer forming cylindrical portion 15c as the conduction portion 12c, the heat insulating layer forming cylindrical portion 15c is elongated. Is formed. A part of the distal end side of the heat insulating layer forming cylindrical portion 15 c is press-fitted inside the solid electrolyte body 300. The conducting portion 12c press-fitted inside the solid electrolyte body 300 elastically presses the inner peripheral surface 321c in the radial direction from the inside to achieve conduction with the reference electrode layer 320.

Further, as shown in FIG. 5D, the element-side contact portion 14c at the distal end of the conducting portion 12c is in contact with a stepped portion 34c provided inside the solid electrolyte body 300, and the base end of the solid electrolyte body 300 The base end side contact portion 16 corresponding to the base end side end portion of the heat insulating layer forming cylindrical portion 15c exposed to the side contacts the bottom surface of the grommet 4 and is elastically pressed. In this embodiment, the insulating space portion SP _TI, thermal degradation of the grommet 4 is suppressed.

In addition, as shown in FIG. 5 (C), the conducting portion 12c elastically presses the reference electrode layer 320 formed on the inner peripheral surface 321c of the solid electrolyte body 300 in the outer diameter direction to achieve conduction. In addition, since the element side contact portion 14c presses the reference electrode layer 320 formed on the surface of the stepped portion 34c in the axial direction, conduction between the terminal fitting 1c and the reference electrode layer 320 is ensured, and extremely high conduction is achieved. Can demonstrate reliability. In the present embodiment, the proximal end contact portion 16c is notched in a petal shape while expanding in a hook shape, but has a configuration in which no hook portion is provided, that is, a terminal in the gas sensor 8b according to the second embodiment. A structure in which the metal fitting 1b is removed can also be adopted in the gas sensor of each embodiment. By notching the proximal end contact portion 16c into a petal shape, it is possible to suppress the occurrence of cracks and deformation when forming the ridge shape.

(Fourth Embodiment) A gas sensor 8d according to a fourth embodiment of the present invention will be described with reference to FIGS. 6 (A), (B), (C) and (D). Like the structure of the gas sensor of another embodiment, in the structure of the gas sensor 8d according to the present embodiment, the insulating space portion SP _TI, thermal degradation of the grommet 4 is suppressed.

In addition, in the gas sensor element 3d in the present embodiment, as shown in FIGS. 6C and 6D, at the open end of the signal extraction portion 33d provided on the base end side of the solid electrolyte body 300, the base end side is provided. The diameter is gradually changed so as to gradually increase in diameter, and an inclined surface 34d is provided as an inclined portion including a vertical component. In the terminal fitting 1d in the present embodiment, an element-side inclined contact portion 14d is provided between the heat insulating layer forming cylindrical portion 15d and the conducting portion 12d. As a result, when the element-side inclined contact portion 14d is brought into contact with the inclined surface 34d, an elastic pressing force acts in both the radial direction and the axial direction, and is highly conductive against external vibrations. Can demonstrate reliability.

(Fifth Embodiment) A gas sensor 8e according to a fifth embodiment of the present invention will be described with reference to FIGS. 7 (A), (B), (C) and (D). In the gas sensor element 3e which is a main part of the gas sensor 8e according to the present embodiment, a signal extraction portion 33e in which the reference electrode layer 320 formed on the inner peripheral surface 321e of the solid electrolyte body 300 is formed on the base end side of the solid electrolyte body 300. The solid electrolyte body 300 is extended to the outer peripheral surface 331e. In this embodiment, by forming the heat-insulating space portion SP _TI between the grommet 4 and the gas sensor element 3e, thermal degradation of the grommet 4 is suppressed.

Furthermore, as shown in FIG. 7C, a part of the heat insulating layer forming cylindrical portion 15e of the terminal fitting 1e is fitted to the outer peripheral surface 331e of the solid electrolyte body 300 as a conducting portion 12e. The conducting portion 12e is formed in a C-shaped cross-section with a diameter slightly smaller than the outer diameter of the outer peripheral surface 331e of the solid electrolyte body 300, and the conducting portion 12e is fitted to the outer peripheral surface 331e. Sometimes it is biased to generate a pressing force in the direction from the outside toward the center.

Thereby, the conduction part 12e elastically presses the reference electrode layer 320 from the outer peripheral side direction to achieve conduction. Compared to the case where the conducting part is press-fitted into the inner peripheral surface of the solid electrolyte body 300, the outer diameter of the conducting part 12e is increased, so that the surface area of the conducting part 12e is increased, the cooling effect is improved, and the transfer to the grommet 4 is improved. It is also possible to reduce the amount of heat.

Further, as shown in FIG. 7 (C), the step portion provided on the outer periphery of the signal extraction portion 33 is used as a flat portion 34e, and the element side contact portion 14e is brought into contact, and as shown in FIG. 7 (D). In this way, the base end side contact portion 16e of the heat insulating layer forming cylindrical portion 15e contacts the bottom surface 40 of the grommet 4, and elastic pressing force acts from the grommet 4 also in the axial direction, thereby improving the conduction reliability. I am trying. Further, a cylindrical elastic member 60 is fitted so as to cover the outer periphery of the conducting portion 12 e and is compressed from the outer peripheral direction by the caulking portion 55 together with the water repellent filter 61. The conducting portion 12e is biased so as to elastically press the reference electrode layer 320 extending on the outer peripheral surface 331e of the signal extraction portion 33e toward the center, but the cylindrical elastic member 60 is superimposed on the conductive portion 12e. Since the conduction part 12e is elastically pressed toward the center, the one-phase conduction reliability can be further improved.

(Sixth Embodiment) A gas sensor 8f according to a sixth embodiment will be described with reference to FIGS. The second conductive portion 18 connected via the connecting portion 19 is provided on the distal end side of the conductive portion 12 of the terminal fitting 1f, which is the main part of the gas sensor 8f according to the present embodiment, so that the inner diameter of the solid electrolyte body 300 is reduced. The diameter changing portion 322 is brought into contact with the reference electrode layer 320. In the present embodiment, in the same manner as in the above-described embodiment, in addition to the effect of suppressing thermal deterioration of the grommet 4 to ensure conduction reliability and improve durability, the second conduction portion 18 complementarily conducts. Reliability has been improved. As shown in FIG. 8C, the second conducting portion 18 is formed in a tongue-like shape that is bifurcated at the tip end side, and is in contact with the inclined diameter changing portion 322 so as to be axial and radial. Will be pressed. As a result, even if external vibration acts on the terminal fitting 1f, the conduction portion 12 that elastically presses the reference electrode layer 320 in the radial direction and the reference electrode layer 320 are neatly arranged in both the axial direction and the radial direction. Since any one of the second conducting parts 18 to be pressed always maintains conduction with the reference electrode layer 320, extremely high conduction reliability can be exhibited.

Further, in the present embodiment, the front end side of the water repellent filter 61 and the cylindrical elastic member 60 are interposed between the casing 5 f and the signal extraction portion 33 of the gas sensor element 3, and the outer peripheral surface of the signal extraction portion 33. The caulking portion 55 is provided by compressing the middle diameter portion 51 of the casing 5f toward the center in the radial direction with the back of 331. In the present embodiment, the water-repellent filter 61 is disposed on the inner side than the cylindrical elastic member 60 when caulking and fixing. By disposing the tip of the water repellent filter 61 inside the cylindrical elastic member 60, the water repellent filter 61 is compressed via the cylindrical elastic member 60 when the caulking portion 55 is formed. Excessive deformation is suppressed, and no gap is formed between the water repellent filter 61 and the cylindrical elastic member 60, so that water droplets can be reliably prevented from entering.

(Seventh Embodiment) With reference to FIGS. 9A, 9B and 9C, an outline of a terminal fitting 1g which is a main part of a gas sensor 8g according to a seventh embodiment of the present invention and its effects will be described. In the first to sixth embodiments described above, the configuration in which the crimping portion 10 is provided at the distal ends of the

terminal fittings

1 and 1a to 1f is shown. However, the terminal fitting 1g of the gas sensor 8g according to the seventh embodiment is crimped. The difference is that the portion 10g is provided closer to the base end side than the tubular portion 15g for heat insulation layer formation. Furthermore, as shown in FIG. 9C, a crimping portion space 41 for accommodating the crimping portion 10g is provided on the distal end side (opposite the base end side) of the grommet 4 and accommodated inside the grommet 4g. You may do it. According to the configuration of the gas sensor 8g according to the present embodiment, the crimping portion 10g is located on the proximal end side with respect to the vent hole 52 and is disposed in a relatively low temperature environment. Damage can also be reduced.

Also, using an insulating material such as alumina, an insulating body (not shown) that is formed in an annular shape by providing a space capable of accommodating the crimping portion 10g is prepared, and the heat insulating layer forming cylindrical portion 15g and the bottom surface of the grommet are prepared. You may make it interpose between 40g. In this case, the insulator having high thermal conductivity comes into contact with the grommet bottom surface 40g, but is supported on the tip side of the insulator by the tubular portion 15g for forming the heat insulating layer through the vent hole 52 while being supported by the air hole 52. since communicated thermal insulation space SP _TI is present, almost without heat in the measurement gas for heating the gas sensor element 3 reaches the grommet 4, it is possible to suppress thermal deterioration of the grommet 4.

(Eighth Embodiment) Referring to FIGS. 10A, 10B and 10C, an outline of a terminal fitting 1h which is a main part of a gas sensor 8h according to an eighth embodiment of the present invention, and its The effect will be described. In the present embodiment, a crimping portion 10h for crimping and fixing the core wire 20 of the signal line 2 is disposed at the center of the terminal fitting 1h, and a proximal end abutment that abuts on the proximal end side via the connecting portion 13h. A tubular portion 15 for forming a heat insulating layer having a portion 16 is provided, and a conducting portion 12h is provided on the tip side via a connecting portion 11h.

Also in the configuration of the gas sensor 8h of the present embodiment, as shown in FIG. 10C, the flat portion 34 that is the upper surface of the open end of the solid electrolyte body 300 of the gas sensor element 3 is placed on the distal end side of the cylindrical portion of the terminal fitting. The element side contact portion 14 which is an end surface contacts, the base end side contact portion 16 contacts the bottom surface 40 of the grommet 4, and the water repellent filter 61 is interposed between the base end of the gas sensor element 3 and the grommet 4. the air insulating space portion SP _TI is formed continuous to the vent hole 52 for introducing air Te, thermal degradation of the grommet 4 is suppressed, and a conductive portion 12h of the terminal 1h, the inner peripheral surface of the solid electrolyte body 300 A highly reliable gas sensor 8h having excellent electrical continuity with the reference electrode layer 320 formed in 321 can be realized. In addition, in the present embodiment, as shown in FIG. 10C, the crimping portion 10h is housed inside the gas sensor element 3, so that the size of the gas sensor 8h can be reduced. Furthermore, since the crimping portion 10h is provided on the proximal end side with respect to the conducting portion 12h, the distance from the heat source is longer than when the crimping portion 10 is provided at the distal end. Can reduce thermal damage.

In the configuration of the gas sensor 8h according to the present embodiment, the distal end side of the water repellent filter 61 and the cylindrical elastic member 60 are interposed between the casing 5 and the signal extraction portion 33 of the gas sensor element 3, and the signal extraction portion 33 is interposed. The caulking portion 55 is provided by compressing the middle diameter portion 51 of the casing 5 toward the center in the radial direction with the outer peripheral surface 331 of the casing 5 as the back. In the gas sensor 8h according to the present embodiment, the distal end portion of the water repellent filter 61 is disposed on the inner side of the cylindrical elastic member 60, whereby the caulking portion 55 is formed via the cylindrical elastic member 60. Since the water repellent filter 61 is compressed, excessive deformation is suppressed, and no gap is formed between the water repellent filter 61 and the cylindrical elastic member 60, so that the intrusion of water droplets can be reliably prevented. effective.

(Ninth embodiment)
With reference to FIG. 11, an outline of a gas sensor 8i according to a ninth embodiment of the present invention will be described. As described above, in the gas sensors 8 to 8h according to the first to eighth embodiments, an example in which the welded portion 56 in which the tip of the casing 5 is fixed to the boss portion 74 of the housing 7 by laser welding is shown. However, in the configuration of the gas sensor 8i according to the ninth embodiment, the casing flange portion 56i protruding in the outer peripheral direction is provided at the tip of the casing 5i, and the powder filling member 62i, the insulating sealing member 63i, and the sealing member Along with the (seal member) 64, it is sandwiched between the powder filling portion locking portion 72 and the caulking portion 73i of the housing 7i, and is fixed by caulking by applying an axial force in the axial direction. This point is different from the structure of the gas sensor according to another embodiment. As shown in FIG. 11, a casing collar portion 56 i that spreads in a hat shape in the radial direction is provided at the tip of the middle diameter portion 51 of the casing 5 i of the gas sensor 8 i according to the ninth embodiment. The casing flange 56i is caulked and fixed together with the sealing member 64 by a caulking portion 73i of the housing 7i.

FIG. 11 shows an example in which the terminal fitting 1 having the same configuration as that of the terminal fitting 1 used in the gas sensor 8 according to the first embodiment is used, but it is used in the gas sensor according to the other embodiments described above. Any of the terminal fittings 1a to 1h can be used. Also in the gas sensor 8i according to the present embodiment, the water repellent filter is provided between the base end of the gas sensor element 3 and the grommet 4 by the heat insulating layer forming cylindrical portion 15 as in the gas sensor according to the other embodiments described above. the air insulating space portion SP _TI continuous 61 to vent 52 for introducing air via is formed, thermal deterioration of the grommet 4 is suppressed, between the conductive section 12 and the reference electrode layer 320 of the terminal fitting 1 The gas sensor 8i having excellent conduction reliability can be realized.

DESCRIPTION OF

SYMBOLS

1, 1b-1h Terminal metal fitting 10 Crimp part 12 Conductive part 14 Element side contact part 14d Element side inclination contact part 15 Heat insulation layer forming cylindrical part 16 Base end side contact part 2 Signal line 20 Signal line core wire 3 Gas sensor Element 30 Detector 300 Solid electrolyte body 301 Solid electrolyte body outer peripheral surface 310 Measurement electrode layer 32 Reference gas chamber 320 Reference electrode layer 321 Inner peripheral surface of solid electrolyte body 34 Solid electrolyte body flat surface part 34d Solid electrolyte body inclined surface 4 Grommet 40 Grommet Bottom 5 Casing 52 Ventilation hole 61 Water repellent filter 7 Housing 8 Gas sensor 91 Gas to be measured _SPTI heat insulation space

Claims

At least a bottomed cylindrical solid electrolyte body (300) having conductivity with respect to specific ions, and a measurement electrode layer formed on the outer peripheral surface (301) of the solid electrolyte body and in contact with the gas to be measured (91) ( 310) and a reference electrode layer (320) formed on the inner peripheral surface (321, 321c, 321e) of the solid electrolyte body and in contact with the atmosphere introduced as a reference gas, A gas sensor element (3) for detecting a specific component in the gas to be measured;
A signal line (2) for connecting the gas sensor element to the outside;
Terminal fittings (1, 1b to 1h) for connecting the gas sensor element and the signal line;
A housing (7) for housing the gas sensor element and arranging and fixing the detection unit in the gas to be measured (91);
A cylindrical casing (5) provided with a vent hole (52) for introducing the air inside while covering the base end side of the gas sensor element together with the terminal fitting,
A grommet (4) for holding the signal line connected to the terminal fitting, while airtightly sealing the base end side of the casing;
A water repellent filter (61) provided with a porous fiber structure that is provided opposite to the vent hole and allows gas permeation but prevents liquid permeation, and detects a specific component in the gas to be measured A gas sensor that
The terminal fitting is formed in a cylindrical shape, and a heat insulating layer forming cylindrical portion (15, 15b to 15e) exposed at a predetermined length from the base end side of the gas sensor element;
An element side contact portion (14, 14c, 14e) that contacts a flat portion (34, 34e) perpendicular to the longitudinal axis of the solid electrolyte body on the tip side of the heat insulating layer forming cylindrical portion, or a vertical component An element side inclined contact portion (14d) that contacts an inclined surface (34d) including;
A base end side contact portion (16, 16c, 16e) that contacts the bottom surface (40) of the grommet on the base end side of the tubular portion for heat insulation layer formation;
Conductive portions (12, 12b to 12e, 12h) that elastically contact with the reference electrode layer to achieve conduction;
A crimping part (10, 10 g, 10 h) for crimping and fixing the core wire (20) of the signal line,
A gas sensor (8, 8a˜) characterized in that a heat insulating space (SP TI ) communicating with the vent hole (52) is provided while separating the grommet (4) and the gas sensor element (3). 8i).
In the terminal fitting (1, 1b to 1h), the tubular portion for forming the heat insulating layer is formed in a partially cut-out tubular shape having a diameter larger than the inner peripheral diameter of the solid electrolyte body, 2. The gas sensor according to claim 1, wherein the element side contact portion is brought into contact with the base end side end surface of the electrolyte body as the flat portion.
In the signal extraction portion provided on the base end side of the solid electrolyte body, the gas sensor element has a stepwise diameter so that the inner peripheral surface has a smaller diameter on the distal end side and a larger diameter on the proximal end side as the planar portion. Providing a changed stepped portion (34c);
A part of the tubular portion for forming the heat insulation layer of the terminal fitting (1c) is press-fitted into the solid electrolyte body as the conductive portion, and the conductive portion radially extends the inner peripheral surface from the inner side. 2. The device according to claim 1, wherein the element-side contact portion is in contact with the stepped portion and pressed in the axial direction while being elastically pressed to be electrically connected to the reference electrode layer. Gas sensor.
The gas sensor element includes an inclined surface whose diameter is gradually increased toward the base end side at the opening end of the signal extraction portion provided on the base end side of the solid electrolyte body, and
The element side inclined contact portion (14d) is provided between the tubular portion (15d) for forming the heat insulation layer of the terminal fitting (1d) and the conducting portion (12d), and the element side inclined contact portion. The gas sensor according to claim 1, wherein the gas sensor is brought into contact with the inclined surface (34d).
The gas sensor element extends a reference electrode layer formed on the inner peripheral surface of the solid electrolyte body to the outer peripheral surface of the solid electrolyte body at a signal extraction portion (33e) formed on the base end side of the solid electrolyte body, A part of the tubular portion for forming the heat insulation layer of the terminal fitting (1e) is fitted as the conducting portion to the outer peripheral surface of the solid electrolyte body,
While the conducting portion elastically presses the outer peripheral surface in the radial direction from the outside to achieve conduction with the reference electrode layer, the step portion provided on the outer circumference of the signal extraction portion (33e) 34. The gas sensor according to claim 1, wherein the element side contact portion is contacted as 34e).
A second conductive portion (18) in contact with the reference electrode layer is provided at the diameter changing portion obtained by reducing the inner diameter of the solid electrolyte body on the distal end side of the conductive portion of the terminal fitting (1f). The gas sensor according to any one of claims 1 to 4, characterized in that:
7. The base end side contact portion (16) of the tubular portion for forming the heat insulating layer of the terminal fitting (1g) is formed in a hook shape projecting in the radial direction. The gas sensor according to item 1.
The gas sensor according to any one of claims 1 to 7, wherein the crimping portion (10) is disposed on a distal end side of the conducting portion (12, 12b, 12d, 12e) of the terminal fitting. .
The gas sensor according to any one of claims 1 to 7, wherein the pressure-bonding portion (10g) is disposed on a proximal end side with respect to the heat-insulating layer forming cylindrical portion (15g).
The said crimping | compression-bonding part (10h) was arrange | positioned between the said cylindrical part (15) for said heat insulation layer formation, and the said conduction | electrical_connection part (12h), The any one of Claim 1 thru | or 7 characterized by the above-mentioned. Gas sensor.
A front end side of the water repellent filter and a cylindrical elastic member (60) are interposed between the casing and the signal lead-out portion of the gas sensor element, and the outer circumference of the signal lead-out portion is placed behind the casing. When the middle diameter portion is compressed toward the center in the radial direction and the caulking portion is provided and fixed, the cylindrical elastic member (60) is disposed on the inner side than the water repellent filter (61). The gas sensor according to any one of claims 1 to 10, wherein the gas sensor is characterized in that:
A front end side of the water repellent filter and a cylindrical elastic member (60) are interposed between the casing and the signal lead-out portion of the gas sensor element, and the outer circumference of the signal lead-out portion is placed behind the casing. When the middle diameter portion is compressed toward the center in the radial direction and the caulking portion is provided and fixed, the water repellent filter (61) is disposed on the inner side of the cylindrical elastic member (60). The gas sensor according to any one of claims 1 to 10, wherein the gas sensor is characterized in that:
The large-diameter portion (50) formed on the front end side of the casing is fitted into the boss portion (74) of the housing, and a welded portion (56) is provided to be hermetically sealed. 13. The gas sensor according to any one of 12 above.
A casing collar portion (56i) that expands in a hat shape in the radial direction is provided at the tip of the middle diameter portion of the casing, and is fixed by caulking with the caulking portion of the housing together with the sealing member (64). The gas sensor according to any one of claims 1 to 12.