JP7044668B2

JP7044668B2 - Gas sensor

Info

Publication number: JP7044668B2
Application number: JP2018163425A
Authority: JP
Inventors: 雄次島崎
Original assignee: NGK Spark Plug Co Ltd
Current assignee: NGK Spark Plug Co Ltd
Priority date: 2018-08-31
Filing date: 2018-08-31
Publication date: 2022-03-30
Anticipated expiration: 2038-08-31
Also published as: JP2020034506A

Description

本発明は、センサ素子の先端側を囲むプロテクタを備えたガスセンサに関する。 The present invention relates to a gas sensor provided with a protector that surrounds the distal end side of the sensor element.

従来から、筒状の主体金具にセンサ素子を組み付け、さらにセンサ素子の先端側を覆うようにして主体金具の先端側に金属製筒状のプロテクタを溶接したガスセンサが知られている。しかしながら、主体金具に用いる材料の熱膨張率と、プロテクタに用いる材料の熱膨張率とは一般に大きく異なるため、溶接部が高温に曝された後に室温付近に冷却される熱履歴を受けると、溶接部に応力が生じて溶接部の剥離やクラックが生じるおそれがある。
一方、主体金具にプロテクタを溶接しないで固定する方法として、内側プロテクタと外側プロテクタを溶接して二重プロテクタとすると共に、内側プロテクタの後端側をフランジ状に拡径し、このフランジを主体金具の内面とセンサ素子の鍔部の外面との間で挟持する技術が知られている（特許文献１）。 Conventionally, there has been known a gas sensor in which a sensor element is assembled to a tubular main metal fitting, and a metal tubular protector is welded to the tip side of the main metal fitting so as to cover the tip side of the sensor element. However, the coefficient of thermal expansion of the material used for the main metal fitting and the coefficient of thermal expansion of the material used for the protector are generally very different. Stress may be generated in the welded portion, causing peeling or cracking of the welded portion.
On the other hand, as a method of fixing the protector to the main metal fitting without welding, the inner protector and the outer protector are welded to form a double protector, and the rear end side of the inner protector is expanded in a flange shape, and this flange is used as the main metal fitting. A technique for sandwiching between the inner surface of the sensor element and the outer surface of the flange portion of the sensor element is known (Patent Document 1).

特開２０１５－２１０１４７号公報Japanese Unexamined Patent Publication No. 2015-210147

しかしながら、特許文献１記載の技術の場合、比較的厚みの薄い内側プロテクタと外側プロテクタとを溶接しているため、溶け込み深さをあまり大きくすることができず、溶接強度が低下するおそれがある。
又、厚みの薄い内側プロテクタの後端側をフランジ状にして主体金具に固定するため、プロテクタに飛石等の衝撃が加わった場合に、フランジがずれたり曲がってプロテクタが主体金具に対して斜めになったり、主体金具から脱落するおそれがある。 However, in the case of the technique described in Patent Document 1, since the inner protector and the outer protector having a relatively thin thickness are welded, the penetration depth cannot be increased so much, and the welding strength may decrease.
In addition, since the rear end side of the thin inner protector is made into a flange shape and fixed to the main metal fitting, when an impact such as a stepping stone is applied to the protector, the flange is displaced or bent and the protector is slanted with respect to the main metal fitting. There is a risk that it will become or fall off from the main metal fittings.

本発明は、かかる現状に鑑みてなされたものであって、プロテクタが高温に曝されたりプロテクタに外力が加わっても、プロテクタを主体金具に確実に固定することができるガスセンサを提供することを目的とする。 The present invention has been made in view of the present situation, and an object of the present invention is to provide a gas sensor capable of reliably fixing the protector to the main metal fitting even when the protector is exposed to a high temperature or an external force is applied to the protector. And.

本発明のガスセンサは、軸線方向に延び、先端側に被測定ガス中の特定ガスを検知する検知部が形成されたセンサ素子と、前記センサ素子の前記検知部よりも後端側の径方向周囲を取り囲んで保持する筒状の主体金具と、前記センサ素子の先端側を囲む筒状をなし、前記被測定ガスを導入又は排出可能なプロテクタと、を備えたガスセンサであって、さらに、筒状の中間部材を備え、前記中間部材の外面又は内面に前記プロテクタが重なり合った状態で溶接部が形成され、前記中間部材が前記主体金具の先端側の内面に圧入又は係合されており、前記溶接部に隣接する前記中間部材と前記プロテクタとの重なり部位において、前記プロテクタの厚みｔｈ１と前記中間部材の厚みｔｈ２とを比較したとき、ｔｈ１＜ｔｈ２の関係を満たし、前記主体金具の構成材料の２０～８５０℃における熱膨張率をＴ１、前記プロテクタの構成材料の２０～８５０℃における熱膨張率をＴ２、前記中間部材の構成材料の２０～８５０℃における熱膨張率をＴ３とした場合、Ｔ２＞Ｔ１、かつＴ３＞Ｔ１の関係を満たすことを特徴とする。 The gas sensor of the present invention has a sensor element extending in the axial direction and having a detection unit for detecting a specific gas in the gas to be measured formed on the front end side, and a radial circumference on the rear end side of the detection unit of the sensor element. A gas sensor having a tubular main metal fitting that surrounds and holds the sensor element, and a protector that has a tubular shape that surrounds the tip end side of the sensor element and can introduce or discharge the gas to be measured, and further has a tubular shape. A welded portion is formed in a state where the protector is overlapped on the outer surface or the inner surface of the intermediate member, and the intermediate member is press-fitted or engaged with the inner surface on the tip end side of the main metal fitting. When the thickness th1 of the protector and the thickness th2 of the intermediate member are compared at the overlapping portion between the intermediate member and the protector adjacent to the portion, the relationship of th1 <th2 is satisfied, and 20 of the constituent material of the main metal fitting is satisfied. When the thermal expansion rate at ~ 850 ° C. is T1, the thermal expansion rate at 20 to 850 ° C. of the constituent material of the protector is T2, and the thermal expansion rate at 20 to 850 ° C. of the constituent material of the intermediate member is T3> It is characterized by satisfying the relationship of T1 and T3> T1.

このガスセンサによれば、ｔｈ１＜ｔｈ２の関係を満たすことで、プロテクタに比べて厚い中間部材にプロテクタを溶接するので、溶け込み深さを大きくして溶接強度を向上させることができる。又、主体金具に固定される中間部材がプロテクタより厚いので、プロテクタに飛石等の衝撃が加わっても中間部材が変形し難く、プロテクタを主体金具に確実に固定することができる。
さらに、Ｔ２＞Ｔ１、かつＴ３＞Ｔ１の関係を満たしたうえで、プロテクタを中間部材に溶接することで、主体金具とプロテクタに用いる材料のそれぞれの熱膨張率Ｔ１，Ｔ２が大きく異なっても、プロテクタと中間部材に用いる材料のそれぞれの熱膨張率Ｔ２、Ｔ３を近づけることで、溶接部が高温に曝された後に室温付近に冷却される熱履歴を受けても、溶接部に応力が生じて溶接部の剥離やクラックが生じることを抑制できる。
又、Ｔ３＞Ｔ１としつつ、中間部材を主体金具の内面に配置することで、高温下で中間部材が主体金具よりも膨張して主体金具の内面に密着する焼嵌め効果が生じ、高温下でも中間部材、ひいてはプロテクタを主体金具により強固に固定できる。
以上により、プロテクタが高温に曝されたり、プロテクタに力が掛かっても主体金具に確実に固定することができる。 According to this gas sensor, by satisfying the relationship of th1 <th2, the protector is welded to the intermediate member which is thicker than the protector, so that the penetration depth can be increased and the welding strength can be improved. Further, since the intermediate member fixed to the main metal fitting is thicker than the protector, the intermediate member is not easily deformed even if an impact such as a stepping stone is applied to the protector, and the protector can be securely fixed to the main metal fitting.
Further, by satisfying the relationship of T2> T1 and T3> T1 and welding the protector to the intermediate member, even if the respective thermal expansion coefficients T1 and T2 of the main metal fitting and the material used for the protector are significantly different, By bringing the coefficients of thermal expansion T2 and T3 of the materials used for the protector and the intermediate member close to each other, stress is generated in the weld even if the weld is exposed to high temperature and then cooled to near room temperature. It is possible to suppress peeling and cracking of the welded portion.
Further, by arranging the intermediate member on the inner surface of the main metal fitting while setting T3> T1, the intermediate member expands more than the main metal fitting at high temperature to produce a shrink-fitting effect in which the intermediate member adheres to the inner surface of the main metal fitting, and even at high temperature. The intermediate member and eventually the protector can be firmly fixed by the main metal fittings.
As described above, even if the protector is exposed to a high temperature or a force is applied to the protector, it can be securely fixed to the main metal fitting.

本発明のガスセンサにおいて、前記中間部材は無底筒状をなしてもよい。
このガスセンサによれば、中間部材を有底筒状とした場合に比べ、センサ素子を囲むプロテクタの内部空間を大きくすることができ、センサ素子により多くの被測定ガスを接触させて検出精度を向上させることができる。 In the gas sensor of the present invention, the intermediate member may have a bottomless cylinder shape.
According to this gas sensor, the internal space of the protector surrounding the sensor element can be made larger than when the intermediate member has a bottomed cylinder shape, and more gas to be measured is brought into contact with the sensor element to improve the detection accuracy. Can be made to.

本発明のガスセンサにおいて、前記センサ素子の外面と前記主体金具の内面との間にシール部材が配置され、前記軸線方向から見て、前記中間部材と前記シール部材とが少なくとも一部で重なってもよい。
このガスセンサによれば、プロテクタが高温に曝されて中間部材が熱膨張して膨らんだ際、シール部材を圧縮し、シール性をさらに向上させることができる。 In the gas sensor of the present invention, even if a seal member is arranged between the outer surface of the sensor element and the inner surface of the main metal fitting, and the intermediate member and the seal member overlap at least a part when viewed from the axial direction. good.
According to this gas sensor, when the protector is exposed to a high temperature and the intermediate member thermally expands and swells, the sealing member can be compressed and the sealing property can be further improved.

本発明のガスセンサにおいて、前記センサ素子の外面と前記主体金具の内面との間にシール部材が配置され、前記中間部材が前記シール部材よりも先端側に位置してもよい。
このガスセンサによれば、プロテクタが高温に曝されて中間部材が熱膨張して膨らんだ際、後端側のシール部材を圧縮し、シール性をさらに向上させることができる。 In the gas sensor of the present invention, a seal member may be arranged between the outer surface of the sensor element and the inner surface of the main metal fitting, and the intermediate member may be located on the distal end side of the seal member.
According to this gas sensor, when the protector is exposed to a high temperature and the intermediate member thermally expands and swells, the sealing member on the rear end side can be compressed to further improve the sealing property.

本発明のガスセンサにおいて、前記プロテクタが前記中間部材の外面に重なり合った状態で前記溶接部が形成され、Ｔ３＞Ｔ２の関係を満たしてもよい。
このガスセンサによれば、高温下で中間部材がプロテクタよりも膨張してプロテクタの内面に密着する焼嵌め効果が生じ、高温下でも中間部材とプロテクタとをより強固に固定でき、ひいてはプロテクタを主体金具により強固に固定できる。 In the gas sensor of the present invention, the welded portion may be formed in a state where the protector overlaps the outer surface of the intermediate member, and the relationship of T3> T2 may be satisfied.
According to this gas sensor, the intermediate member expands more than the protector at high temperature to produce a shrink-fitting effect that adheres to the inner surface of the protector, and even at high temperature, the intermediate member and protector can be fixed more firmly, and the protector is the main metal fitting. Can be fixed more firmly.

本発明のガスセンサにおいて、前記プロテクタが前記中間部材の内面に重なり合った状態で前記溶接部が形成され、Ｔ３＜Ｔ２の関係を満たしてもよい。
このガスセンサによれば、高温下でプロテクタが中間部材よりも膨張して中間部材の内面に密着する焼嵌め効果が生じ、高温下でも中間部材とプロテクタとをより強固に固定でき、ひいてはプロテクタを主体金具により強固に固定できる。 In the gas sensor of the present invention, the welded portion may be formed in a state where the protector overlaps the inner surface of the intermediate member, and the relationship of T3 <T2 may be satisfied.
According to this gas sensor, the protector expands more than the intermediate member at high temperature to produce a shrink-fitting effect that adheres to the inner surface of the intermediate member, and even at high temperature, the intermediate member and protector can be fixed more firmly, and by extension, the protector is the main component. Can be firmly fixed by metal fittings.

本発明のガスセンサにおいて、Ｔ３＝Ｔ２の関係を満たしてもよい。
このガスセンサによれば、プロテクタと中間部材の構成材料の２０～８５０℃における熱膨張率が等しいので、プロテクタが高温に曝されても溶接部に応力が生じることを抑制できる。 In the gas sensor of the present invention, the relationship of T3 = T2 may be satisfied.
According to this gas sensor, since the coefficient of thermal expansion of the protector and the constituent material of the intermediate member at 20 to 850 ° C. is equal, it is possible to suppress the generation of stress in the welded portion even if the protector is exposed to a high temperature.

本発明のガスセンサにおいて、前記溶接部は、前記中間部材を貫通しなくてよい。
このガスセンサによれば、溶接部と反対側の中間部材の内面（又は外面）が滑らかになり、ガスセンサ組付け時に中間部材の内面等に他部材が接触して破損することを抑制すると共に、ガスセンサ使用時に中間部材の内面側のセンサ素子周辺の気流を乱して応答性が低下することも抑制できる。又、ｔｈ２＞ｔｈ１であるので、溶接部が中間部材を貫通しなくとも、溶け込み深さを大きくできる。 In the gas sensor of the present invention, the welded portion does not have to penetrate the intermediate member.
According to this gas sensor, the inner surface (or outer surface) of the intermediate member on the opposite side to the welded portion becomes smooth, and it is possible to prevent other members from coming into contact with the inner surface of the intermediate member and being damaged when the gas sensor is assembled, and at the same time, the gas sensor is used. It is also possible to suppress the deterioration of responsiveness due to the disturbance of the airflow around the sensor element on the inner surface side of the intermediate member during use. Further, since th2> th1, the penetration depth can be increased even if the welded portion does not penetrate the intermediate member.

この発明によれば、ガスセンサのプロテクタが高温に曝されたりプロテクタに外力が加わっても、プロテクタを主体金具に確実に固定することができる。 According to the present invention, even if the protector of the gas sensor is exposed to a high temperature or an external force is applied to the protector, the protector can be reliably fixed to the main metal fitting.

本発明の第１の実施形態にかかるガスセンサの断面図である。It is sectional drawing of the gas sensor which concerns on 1st Embodiment of this invention. 図１の中間部材近傍の部分拡大図である。It is a partially enlarged view in the vicinity of the intermediate member of FIG. 第１の実施形態にかかるガスセンサの製造方法を示す断面図である。It is sectional drawing which shows the manufacturing method of the gas sensor which concerns on 1st Embodiment. 本発明の第２の実施形態にかかるガスセンサの断面図である。It is sectional drawing of the gas sensor which concerns on the 2nd Embodiment of this invention. 第２の実施形態にかかるガスセンサの製造方法を示す断面図である。It is sectional drawing which shows the manufacturing method of the gas sensor which concerns on 2nd Embodiment. 本発明の第３の実施形態にかかるガスセンサの断面図である。It is sectional drawing of the gas sensor which concerns on 3rd Embodiment of this invention.

本発明の実施形態について、各図に基づいて詳細に説明する。まず、図１～図３を参照し、本発明の第１の実施形態にかかるガスセンサ１Ａについて説明する。
図１は、本発明の第１の実施形態にかかるガスセンサ１Ａの断面図、図２は図１の中間部材１００近傍の部分拡大図、図３はガスセンサ１Ａの製造方法を示す断面図である。 An embodiment of the present invention will be described in detail with reference to each figure. First, the gas sensor 1A according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
1 is a cross-sectional view of the gas sensor 1A according to the first embodiment of the present invention, FIG. 2 is a partially enlarged view of the vicinity of the intermediate member 100 of FIG. 1, and FIG. 3 is a cross-sectional view showing a method of manufacturing the gas sensor 1A.

図１において、ガスセンサ（全領域空燃比ガスセンサ）１Ａは、センサ素子２１と、軸線Ｏ方向に貫通してセンサ素子２１を挿通させる貫通孔３２を有するホルダ（セラミックホルダ）３０Ａと、セラミックホルダ３０Ａの径方向周囲を取り囲む主体金具１１と、プロテクタ６０Ａと、後述する中間部材１００と、を備えている。
センサ素子２１のうち、検知部２２が形成された先端寄り部位が、セラミックホルダ３０Ａより先端に突出している。このように貫通孔３２を通されたセンサ素子２１は、セラミックホルダ３０Ａの後端面側（図示上側）に配置されたシール部材（本例では滑石）４１を、絶縁材からなるスリーブ４３、リングワッシャ４５を介して先後方向に圧縮することによって、主体金具１１の内側において先後方向に気密を保持して固定されている。
なお、センサ素子２１の後端２９を含む後端寄り部位はスリーブ４３及び主体金具１１より後方に突出しており、その後端寄り部位に形成された各電極端子２４に、シール部材８５を通して外部に引き出された各リード線７１の先端に設けられた端子金具７５が圧接され、電気的に接続されている。また、この電極端子２４を含むセンサ素子２１の後端寄り部位は、外筒８１でカバーされている。以下、さらに詳細に説明する。 In FIG. 1, the gas sensor (all-region air-fuel ratio gas sensor) 1A includes a sensor element 21, a holder (ceramic holder) 30A having a through hole 32 penetrating in the axis O direction and inserting the sensor element 21, and a ceramic holder 30A. It includes a main metal fitting 11 that surrounds a radial periphery, a protector 60A, and an intermediate member 100, which will be described later.
Of the sensor element 21, the portion near the tip where the detection portion 22 is formed protrudes from the ceramic holder 30A to the tip. The sensor element 21 passed through the through hole 32 in this way has a seal member (talc in this example) 41 arranged on the rear end surface side (upper side in the drawing) of the ceramic holder 30A, a sleeve 43 made of an insulating material, and a ring washer. By compressing in the front-rear direction via the 45, the airtightness is maintained and fixed in the front-rear direction inside the main metal fitting 11.
The portion near the rear end including the rear end 29 of the sensor element 21 protrudes rearward from the sleeve 43 and the main metal fitting 11, and is pulled out to the outside through the seal member 85 through each electrode terminal 24 formed at the portion near the rear end. The terminal fittings 75 provided at the tips of the lead wires 71 are pressure-welded and electrically connected. Further, the portion near the rear end of the sensor element 21 including the electrode terminal 24 is covered with the outer cylinder 81. Hereinafter, it will be described in more detail.

センサ素子２１は軸線Ｏ方向に延びると共に、測定対象に向けられる先端側（図示下側）に、検知用電極等（図示せず）からなり被検出ガス中の特定ガス成分を検出する検知部２２を備えた帯板状（板状）をなしている。センサ素子２１の横断面は、先後において一定の大きさの長方形（矩形）をなし、セラミック（固体電解質等）を主体として細長いものとして形成されている。このセンサ素子２１自体は、従来公知のものと同じものであり、固体電解質（部材）の先端寄り部位に検知部２２をなす一対の検知用電極が配置され、これに連なり後端寄り部位には、検知用出力取り出し用のリード線７１接続用の電極端子２４が露出形成されている。
また、本例では、センサ素子２１のうち、固体電解質（部材）に積層状に形成されたセラミック材の先端寄り部位内部にヒータ（図示せず）が設けられており、後端寄り部位には、このヒータへの電圧印加用のリード線７１接続用の電極端子２４が露出形成されている。なお、図示はしないが、これら電極端子２４は縦長矩形に形成され、例えばセンサ素子２１の後端寄り部位において、帯板の幅広面（両面）に３つ又は２つの電極端子が横に並んでいる。
なお、センサ素子２１の検知部２２に、アルミナ又はスピネル等からなる多孔質の保護層２３が被覆されている。 The sensor element 21 extends in the O-axis direction, and is composed of a detection electrode or the like (not shown) on the tip side (lower side in the drawing) facing the measurement target, and is a detection unit 22 that detects a specific gas component in the detected gas. It has a strip-shaped (plate-shaped) shape. The cross section of the sensor element 21 forms a rectangle (rectangle) of a certain size before and after, and is formed as an elongated one mainly composed of ceramic (solid electrolyte or the like). The sensor element 21 itself is the same as that conventionally known, and a pair of detection electrodes forming a detection unit 22 are arranged at a portion near the tip of the solid electrolyte (member), which is connected to the sensor element 21 and is connected to the portion near the rear end. The electrode terminal 24 for connecting the lead wire 71 for taking out the output for detection is exposed.
Further, in this example, in the sensor element 21, a heater (not shown) is provided inside the portion near the tip of the ceramic material formed in a laminated manner on the solid electrolyte (member), and the portion near the rear end is provided. The electrode terminal 24 for connecting the lead wire 71 for applying a voltage to the heater is exposed and formed. Although not shown, these electrode terminals 24 are formed in a vertically long rectangular shape, and for example, at a portion near the rear end of the sensor element 21, three or two electrode terminals are arranged side by side on the wide surface (both sides) of the strip. There is.
The detection unit 22 of the sensor element 21 is covered with a porous protective layer 23 made of alumina, spinel, or the like.

主体金具１１は、先後において同心異径の筒状をなし、先端側が小径で、後述する中間部材１００を自身の内面に係合するための円筒状の円環状部（以下、円筒部ともいう）１８を有し、その後方（図示上方）の外周面には、それより大径をなす、エンジンの排気管への固定用のネジ１３が設けられている。そして、その後方には、このネジ１３によってセンサ１をねじ込むための多角形部１４を備えている。また、この多角形部１４の後方には、ガスセンサ１Ａの後方をカバーする保護筒（外筒）８１を外嵌して溶接する円筒部１５が連設され、その後方には外径がそれより小さく薄肉のカシメ用円筒部１６を備えている。なお、このカシメ用円筒部１６は、図１では、カシメ後のために内側に曲げられている。なお、多角形部１４の下面には、ねじ込み時におけるシール用のガスケット１９が取着されている。
さらに、主体金具１１の円環状部１８近傍の内周面には、後端側から先端側に向かって径方向内側に先細るテーパ状の段部１７を有している。 The main metal fitting 11 has a cylindrical shape having concentric and different diameters at the front and rear, has a small diameter on the tip side, and has a cylindrical annular portion (hereinafter, also referred to as a cylindrical portion) for engaging the intermediate member 100 described later with its inner surface. 18 is provided, and a screw 13 for fixing to the exhaust pipe of the engine having a larger diameter is provided on the outer peripheral surface behind the 18 (upper side in the drawing). A polygonal portion 14 for screwing the sensor 1 by the screw 13 is provided behind the screw 13. Further, behind the polygonal portion 14, a cylindrical portion 15 to which a protective cylinder (outer cylinder) 81 covering the rear of the gas sensor 1A is fitted and welded is continuously provided, and behind the cylindrical portion 15, the outer diameter is smaller than that. It is provided with a small and thin-walled caulking cylindrical portion 16. In FIG. 1, the caulking cylindrical portion 16 is bent inward for post-caulking. A gasket 19 for sealing at the time of screwing is attached to the lower surface of the polygonal portion 14.
Further, the inner peripheral surface of the main metal fitting 11 near the annular portion 18 has a tapered step portion 17 that tapers inward in the radial direction from the rear end side toward the tip side.

主体金具１１の内側には、絶縁性セラミック（例えばアルミナ）からなり、概略短円筒状に形成されたセラミックホルダ３０Ａが配置されている。セラミックホルダ３０Ａは、先端に向かって先細りのテーパ状に形成された先端向き面３０ｆを有している。そして、先端向き面３０ｆの外周寄りの部位が中間部材１００を介して段部１７に係止されつつ、セラミックホルダ３０Ａが後端側からシール部材４１で押圧されることで主体金具１１内にセラミックホルダ３０Ａが位置決めされ、かつ隙間嵌めされている。
一方、貫通孔３２は、セラミックホルダ３０Ａの中心に設けられると共に、センサ素子２１が略隙間なく通るように、センサ素子２１の横断面とほぼ同一の寸法の矩形の開口とされている。 Inside the main metal fitting 11, a ceramic holder 30A made of an insulating ceramic (for example, alumina) and formed in a substantially short cylindrical shape is arranged. The ceramic holder 30A has a tip facing surface 30f formed in a tapered shape that tapers toward the tip. Then, the ceramic holder 30A is pressed by the seal member 41 from the rear end side while the portion of the tip facing surface 30f near the outer circumference is locked to the step portion 17 via the intermediate member 100, so that the ceramic is inside the main metal fitting 11. The holder 30A is positioned and fitted in a gap.
On the other hand, the through hole 32 is provided in the center of the ceramic holder 30A, and is a rectangular opening having substantially the same dimensions as the cross section of the sensor element 21 so that the sensor element 21 can pass through without a gap.

センサ素子２１は、セラミックホルダ３０Ａの貫通孔３２に通され、センサ素子２１の先端をセラミックホルダ３０Ａ及び主体金具１１の先端よりも先方に突出させている。
一方、センサ素子２１の先端部位は、筒状をなし、被測定ガスを導入又は排出可能なプロテクタ６０Ａで覆われている。本形態では、プロテクタ６０Ａは、通気孔５６及び排出孔５３を有する有底円筒状の内側プロテクタ５１と、通気孔６７及び排出孔６９を有する有底円筒状の外側プロテクタ６１とを離間して配置した２重プロテクタからなる。
このうち内側プロテクタ５１と外側プロテクタ６１の後端６０Ａｅが中間部材１００の外面に重なり合った状態で、内側プロテクタ５１及び外側プロテクタ６１を貫通する溶接部Ｗが形成されている。より具体的には、内側プロテクタ５１の後端が拡径して外側プロテクタ６１の後端に接し、両者が重なった後端６０Ａｅが形成されている。そして、内側プロテクタ５１の後端と中間部材１００の外面とが対向し、外側プロテクタ６１から中間部材１００に向かって溶接部Ｗが形成されている。 The sensor element 21 is passed through a through hole 32 of the ceramic holder 30A, and the tip of the sensor element 21 is projected beyond the tips of the ceramic holder 30A and the main metal fitting 11.
On the other hand, the tip portion of the sensor element 21 has a cylindrical shape and is covered with a protector 60A capable of introducing or discharging the gas to be measured. In this embodiment, the protector 60A is arranged so that the bottomed cylindrical inner protector 51 having the ventilation holes 56 and the discharge holes 53 and the bottomed cylindrical outer protector 61 having the ventilation holes 67 and the discharge holes 69 are separated from each other. It consists of a double protector.
Of these, a welded portion W that penetrates the inner protector 51 and the outer protector 61 is formed in a state where the inner protector 51 and the rear end 60Ae of the outer protector 61 overlap the outer surface of the intermediate member 100. More specifically, the rear end of the inner protector 51 has a large diameter and is in contact with the rear end of the outer protector 61, and a rear end 60Ae in which both are overlapped is formed. The rear end of the inner protector 51 and the outer surface of the intermediate member 100 face each other, and a welded portion W is formed from the outer protector 61 toward the intermediate member 100.

中間部材１００は、金属製で無底筒状をなし、後端側に径方向外側に広がるフランジ部１００ａを有している。中間部材１００のフランジ部１００ａを除く外径は、主体金具１１の円環状部１８の内径よりわずかに小さく、円環状部１８の内側に中間部材１００を嵌合可能になっている。
そして、主体金具１１の後端側から中間部材１００を挿入すると、段部１７にフランジ部１００ａの先端向き面１００ｆが係止される。さらに中間部材１００の後端側に配置されたセラミックホルダ３０Ａの先端向き面３０ｆを先端に向かって押圧すると、先端向き面３０ｆがフランジ部１００ａの後端向き面に当接し、先端向き面３０ｆが中間部材１００を介して段部１７に係止される。
つまり、中間部材１００は、主体金具１１とセラミックホルダ３０Ａとの間に挟持されている。
このようにして中間部材１００が主体金具１１に係合されると共に、主体金具１１の先端よりも先方に突出した中間部材１００の外面に、上記したようにプロテクタ６０Ａの後端６０Ａｅが溶接されて溶接部Ｗが形成されている。 The intermediate member 100 is made of metal and has a bottomless cylindrical shape, and has a flange portion 100a extending radially outward on the rear end side. The outer diameter of the intermediate member 100 excluding the flange portion 100a is slightly smaller than the inner diameter of the annular portion 18 of the main metal fitting 11, and the intermediate member 100 can be fitted inside the annular portion 18.
Then, when the intermediate member 100 is inserted from the rear end side of the main metal fitting 11, the tip facing surface 100f of the flange portion 100a is locked to the step portion 17. Further, when the tip facing surface 30f of the ceramic holder 30A arranged on the rear end side of the intermediate member 100 is pressed toward the tip, the tip facing surface 30f comes into contact with the rear end facing surface of the flange portion 100a, and the tip facing surface 30f is formed. It is locked to the step portion 17 via the intermediate member 100.
That is, the intermediate member 100 is sandwiched between the main metal fitting 11 and the ceramic holder 30A.
In this way, the intermediate member 100 is engaged with the main metal fitting 11, and the rear end 60Ae of the protector 60A is welded to the outer surface of the intermediate member 100 protruding beyond the tip of the main metal fitting 11. The welded portion W is formed.

一方、図１に示すように、センサ素子２１の後端寄り部位に形成された各電極端子２４には、外部にシール部材８５を通して引き出された各リード線７１の先端に設けられた各端子金具７５がそのバネ性により圧接され、電気的に接続されている。そして、この圧接部を含む各端子金具７５は、本例ガスセンサ１Ａでは、外筒８１内に配置された絶縁性のセパレータ９１内に設けられた各収容部内に、それぞれ対向配置で設けられている。なお、セパレータ９１は、外筒８１内にカシメ固定された保持部材８２を介して径方向及び先端側への動きが規制されている。そして、この外筒８１の先端部を、主体金具１１の後端寄り部位の円筒部１５に外嵌して溶接することで、ガスセンサ１Ａの後方が気密状にカバーされている。
なお、リード線７１は外筒８１の後端部の内側に配置されたシール部材（例えばゴム）８５を通されて外部に引き出されており、この小径筒部８３を縮径カシメしてこのシール部材８５を圧縮することにより、この部位の気密が保持されている。 On the other hand, as shown in FIG. 1, each electrode terminal 24 formed at a portion near the rear end of the sensor element 21 has a terminal fitting provided at the tip of each lead wire 71 drawn out through the seal member 85 to the outside. 75 is pressure-welded by its springiness and electrically connected. In the gas sensor 1A of this example, the terminal fittings 75 including the pressure contact portion are provided in opposite arrangements in each accommodating portion provided in the insulating separator 91 arranged in the outer cylinder 81. .. The separator 91 is restricted from moving in the radial direction and toward the tip side via a holding member 82 that is caulked and fixed in the outer cylinder 81. Then, the tip of the outer cylinder 81 is fitted onto the cylindrical portion 15 of the portion near the rear end of the main metal fitting 11 and welded, so that the rear of the gas sensor 1A is airtightly covered.
The lead wire 71 is pulled out to the outside through a sealing member (for example, rubber) 85 arranged inside the rear end portion of the outer cylinder 81, and the small diameter cylinder portion 83 is crimped to this seal. By compressing the member 85, the airtightness of this portion is maintained.

因みに、外筒８１の軸線Ｏ方向の中央よりやや後端側には、先端側が径大の段部８１ｄが形成され、この段部８１ｄの内面がセパレータ９１の後端を先方に押すように支持する。一方、セパレータ９１はその外周に形成されたフランジ９３を外筒８１の内側に固定された保持部材８２の上に支持させられており、段部８１ｄと保持部材８２とによってセパレータ９１が軸線Ｏ方向に保持されている。 Incidentally, a stepped portion 81d having a large diameter at the tip side is formed on the rear end side of the outer cylinder 81 slightly from the center in the axis O direction, and the inner surface of the stepped portion 81d supports the rear end of the separator 91 so as to push it forward. do. On the other hand, in the separator 91, a flange 93 formed on the outer periphery thereof is supported on a holding member 82 fixed to the inside of the outer cylinder 81, and the separator 91 is oriented in the axis O direction by the stepped portion 81d and the holding member 82. It is held in.

次に、図２を参照し、本発明の特徴部分について説明する。
まず、溶接部Ｗに隣接する中間部材１００とプロテクタ６０Ａ（後端６０Ａｅ）との重なり部位において、プロテクタ６０Ａの厚みｔｈ１と、中間部材１００の厚みｔｈ２とを比較したとき、ｔｈ１＜ｔｈ２の関係を満たす。換言すると、中間部材１００とプロテクタ６０Ａ（後端６０Ａｅ）との重なり部位のうち、溶接部Ｗを含まない部位において、プロテクタ６０Ａの厚みｔｈ１と、中間部材１００の厚みｔｈ２とを比較したとき、ｔｈ１＜ｔｈ２の関係を満たす。
ここで、本例ではプロテクタ６０Ａは内側プロテクタ５１と外側プロテクタ６１の二重プロテクタであるが、溶接部Ｗに隣接する後端６０Ａｅでは内側プロテクタ５１と外側プロテクタ６１とが重なっているので、厚みｔｈ１は後端６０Ａｅにおける内側プロテクタ５１と外側プロテクタ６１の合計厚みとする。 Next, a feature portion of the present invention will be described with reference to FIG.
First, when the thickness th1 of the protector 60A and the thickness th2 of the intermediate member 100 are compared at the overlapping portion between the intermediate member 100 adjacent to the welded portion W and the protector 60A (rear end 60Ae), the relationship of th1 <th2 is established. Fulfill. In other words, when the thickness th1 of the protector 60A and the thickness th2 of the intermediate member 100 are compared at the portion where the intermediate member 100 and the protector 60A (rear end 60Ae) do not include the welded portion W, th1 <Satisfy the relationship of th2.
Here, in this example, the protector 60A is a double protector of the inner protector 51 and the outer protector 61, but at the rear end 60Ae adjacent to the welded portion W, the inner protector 51 and the outer protector 61 overlap each other, so that the thickness th1 Is the total thickness of the inner protector 51 and the outer protector 61 at the rear end 60Ae.

又、主体金具１１の構成材料の２０～８５０℃における熱膨張率をＴ１、プロテクタ６０Ａの構成材料の２０～８５０℃における熱膨張率をＴ２、中間部材１００の構成材料の２０～８５０℃における熱膨張率をＴ３とした場合、Ｔ２＞Ｔ１、かつＴ３＞Ｔ１の関係を満たす。なお、本例では、主体金具１１、プロテクタ６０Ａ（内側プロテクタ５１と外側プロテクタ６１）、及び中間部材１００の構成材料はそれぞれＳＵＳ４３０，ＳＵＳ３１０Ｓ、ＳＵＳ３１０Ｓである。 Further, the coefficient of thermal expansion of the constituent material of the main metal fitting 11 at 20 to 850 ° C is T1, the coefficient of thermal expansion of the constituent material of the protector 60A at 20 to 850 ° C is T2, and the thermal expansion of the constituent material of the intermediate member 100 at 20 to 850 ° C. When the expansion coefficient is T3, the relationship of T2> T1 and T3> T1 is satisfied. In this example, the constituent materials of the main metal fitting 11, the protector 60A (inner protector 51 and outer protector 61), and the intermediate member 100 are SUS430, SUS310S, and SUS310S, respectively.

このように、ｔｈ１＜ｔｈ２の関係を満たすことで、プロテクタ６０Ａに比べて厚い中間部材１００にプロテクタ６０Ａを溶接するので、溶け込み深さを大きくして溶接強度を向上させることができる。
又、主体金具１１に固定される中間部材１００の厚みｔｈ２が、プロテクタ６０Ａの厚みｔｈ１より厚いので、プロテクタ６０Ａに飛石等の衝撃が加わっても中間部材１００が変形し難く、プロテクタ６０Ａを主体金具１１に確実に固定することができる。 By satisfying the relationship of th1 <th2 in this way, the protector 60A is welded to the intermediate member 100 which is thicker than the protector 60A, so that the penetration depth can be increased and the welding strength can be improved.
Further, since the thickness th2 of the intermediate member 100 fixed to the main metal fitting 11 is thicker than the thickness th1 of the protector 60A, the intermediate member 100 is not easily deformed even if an impact such as a stepping stone is applied to the protector 60A, and the protector 60A is used as the main metal fitting. It can be securely fixed to 11.

さらに、Ｔ２＞Ｔ１、かつＴ３＞Ｔ１の関係を満たしたうえで、プロテクタ６０Ａを中間部材１００に溶接することで、主体金具１１とプロテクタ６０Ａに用いる材料のそれぞれの熱膨張率Ｔ１，Ｔ２が大きく異なっても、プロテクタ６０Ａと中間部材１００に用いる材料のそれぞれの熱膨張率Ｔ２、Ｔ３を近づけることで、溶接部Ｗが高温に曝された後に室温付近に冷却される熱履歴を受けても、溶接部Ｗに応力が生じて溶接部の剥離やクラックが生じることを抑制できる。
又、Ｔ３＞Ｔ１としつつ、中間部材１００を主体金具１１の内面に配置することで、高温下で中間部材１００が主体金具１１よりも膨張して主体金具１１の内面に密着する焼嵌め効果が生じ、高温下でも中間部材１００、ひいてはプロテクタ６０Ａを主体金具１１により強固に固定できる。
以上により、プロテクタ６０Ａが高温に曝されたり、プロテクタ６０Ａに力が掛かっても主体金具１１に確実に固定することができる。 Further, by satisfying the relationship of T2> T1 and T3> T1 and welding the protector 60A to the intermediate member 100, the respective thermal expansion coefficients T1 and T2 of the main metal fitting 11 and the material used for the protector 60A are large. Even if they are different, even if the welded portion W is exposed to a high temperature and then cooled to near room temperature by bringing the thermal expansion coefficients T2 and T3 of the materials used for the protector 60A and the intermediate member 100 close to each other, even if they receive a thermal history. It is possible to prevent the welded portion W from being stressed and causing peeling or cracking of the welded portion.
Further, by arranging the intermediate member 100 on the inner surface of the main metal fitting 11 while setting T3> T1, the intermediate member 100 expands more than the main metal fitting 11 at high temperature and has a shrink fitting effect of being in close contact with the inner surface of the main metal fitting 11. Even at high temperatures, the intermediate member 100 and thus the protector 60A can be firmly fixed by the main metal fitting 11.
As described above, even if the protector 60A is exposed to a high temperature or a force is applied to the protector 60A, it can be reliably fixed to the main metal fitting 11.

なお、本実施形態では、中間部材１００は無底筒状をなしている。これにより、中間部材１００を有底筒状とした場合に比べ、センサ素子２１を囲むプロテクタ６０Ａの内部空間を大きくすることができ、センサ素子２１により多くの被測定ガスを接触させて検出精度を向上させることができる。
又、本実施形態では、溶接部Ｗは中間部材１００を径方向に貫通しない。これにより、溶接部Ｗと反対側の中間部材１００の内面（又は外面）が滑らかになり、ガスセンサ組付け時に中間部材１００の内面等に他部材が接触して破損することを抑制すると共に、ガスセンサ使用時に中間部材１００の内面側のセンサ素子２１周辺の気流を乱して応答性が低下することも抑制できる。又、ｔｈ２＞ｔｈ１であるので、溶接部Ｗが中間部材１００を貫通しなくとも、溶け込み深さを大きくできる。 In this embodiment, the intermediate member 100 has a bottomless cylindrical shape. As a result, the internal space of the protector 60A surrounding the sensor element 21 can be increased as compared with the case where the intermediate member 100 has a bottomed cylinder shape, and more gas to be measured is brought into contact with the sensor element 21 to improve the detection accuracy. Can be improved.
Further, in the present embodiment, the welded portion W does not penetrate the intermediate member 100 in the radial direction. As a result, the inner surface (or outer surface) of the intermediate member 100 on the opposite side of the welded portion W becomes smooth, and when the gas sensor is assembled, the other members are prevented from coming into contact with the inner surface of the intermediate member 100 and being damaged, and the gas sensor is prevented from being damaged. It is also possible to suppress the deterioration of responsiveness by disturbing the air flow around the sensor element 21 on the inner surface side of the intermediate member 100 during use. Further, since th2> th1, the penetration depth can be increased even if the welded portion W does not penetrate the intermediate member 100.

又、図２の矢印Ｖに示すように、本実施形態では、軸線Ｏ方向から見て、中間部材１００とシール部材４１とが少なくとも一部で重なる。これにより、プロテクタ６０Ａが高温に曝されて中間部材１００が熱膨張して膨らんだ際、シール部材４１を圧縮し、シール性をさらに向上させることができる。
同様に、本実施形態では、中間部材１００がシール部材４１よりも先端側に位置する。これによっても、プロテクタ６０Ａが高温に曝されて中間部材１００が熱膨張して膨らんだ際、後端側のシール部材４１を圧縮し、シール性をさらに向上させることができる。
さらに、本実施形態ではＴ３＝Ｔ２の関係を満たす。これにより、プロテクタ６０Ａと中間部材１００の構成材料の２０～８５０℃における熱膨張率が等しいので、プロテクタ６０Ａが高温に曝されても溶接部Ｗに応力が生じることを抑制できる。 Further, as shown by the arrow V in FIG. 2, in the present embodiment, the intermediate member 100 and the seal member 41 overlap at least a part when viewed from the axis O direction. As a result, when the protector 60A is exposed to a high temperature and the intermediate member 100 thermally expands and swells, the seal member 41 can be compressed and the sealing property can be further improved.
Similarly, in the present embodiment, the intermediate member 100 is located on the distal end side of the seal member 41. Also with this, when the protector 60A is exposed to a high temperature and the intermediate member 100 thermally expands and swells, the sealing member 41 on the rear end side can be compressed, and the sealing property can be further improved.
Further, in this embodiment, the relationship of T3 = T2 is satisfied. As a result, since the coefficients of thermal expansion of the protector 60A and the constituent materials of the intermediate member 100 at 20 to 850 ° C. are equal, it is possible to suppress the generation of stress in the welded portion W even when the protector 60A is exposed to a high temperature.

次に、図３を参照し、ガスセンサ１Ａの製造方法について説明する。
まず、センサ素子２１を主体金具１１に対して保持させ、さらに中間部材１００を主体金具１１の内面に係合させた素子アッセンブリＡｃを準備する。
次に、素子アッセンブリＡｃの先端側に突出した中間部材１００の先端に、プロテクタ６０Ａの後端６０Ａｅを外嵌し、後端６０Ａｅを全周溶接することで溶接部Ｗ（図２参照）を形成し、プロテクタ６０Ａを中間部材１００に固定する。 Next, a method of manufacturing the gas sensor 1A will be described with reference to FIG.
First, an element assembly Ac is prepared in which the sensor element 21 is held by the main metal fitting 11 and the intermediate member 100 is further engaged with the inner surface of the main metal fitting 11.
Next, the rear end 60Ae of the protector 60A is externally fitted to the tip of the intermediate member 100 protruding toward the tip side of the element assembly Ac, and the rear end 60Ae is welded all around to form a welded portion W (see FIG. 2). Then, the protector 60A is fixed to the intermediate member 100.

次いで、外筒８１内にグロメット８５、セパレータ９１、各端子金具７５が接続されたリード線７１等のパーツを収容し、外筒８１を主体金具１１の後端側の円筒部１５に嵌め込み、外筒８１と共に保持部材８２をカシメる。これにより、外筒８１に支持されたセパレータ９１を外筒８１の内部に収容すると共に、段部８１ｄと保持部材８２の間でセパレータ９１のフランジ９３を支持させる。
そして、外筒８１の先端部に対して、主体金具１１の外周面の全周にわたってレーザ溶接し、外筒８１を主体金具１１に対して固定する一方、シール部材８５を外筒８１の後端に組み付けた後にカシメる。
このようにして、本実施形態のガスセンサ１Ａを製造することができる。 Next, parts such as a grommet 85, a separator 91, and a lead wire 71 to which each terminal fitting 75 is connected are housed in the outer cylinder 81, and the outer cylinder 81 is fitted into the cylindrical portion 15 on the rear end side of the main fitting 11 to the outside. The holding member 82 is crimped together with the cylinder 81. As a result, the separator 91 supported by the outer cylinder 81 is housed inside the outer cylinder 81, and the flange 93 of the separator 91 is supported between the stepped portion 81d and the holding member 82.
Then, laser welding is performed on the tip of the outer cylinder 81 over the entire circumference of the outer peripheral surface of the main metal fitting 11, and the outer cylinder 81 is fixed to the main metal fitting 11, while the seal member 85 is attached to the rear end of the outer cylinder 81. After assembling to, crimp.
In this way, the gas sensor 1A of the present embodiment can be manufactured.

次に、図４～図５を参照し、本発明の第２の実施形態にかかるガスセンサ１Ｂについて説明する。
図４は、本発明の第２の実施形態にかかるガスセンサ１Ｂの断面図、図５はガスセンサ１Ｂの製造方法を示す断面図である。
なお、ガスセンサ１Ｂは、プロテクタ６０Ｂ、セラミックホルダ３０Ｂ及び中間部材１０２が異なること以外は、第１の実施形態にかかるガスセンサ１Ａと同一であるので、ガスセンサ１Ａと同一構成部分については同一符号を付して説明を省略する。 Next, the gas sensor 1B according to the second embodiment of the present invention will be described with reference to FIGS. 4 to 5.
FIG. 4 is a cross-sectional view of the gas sensor 1B according to the second embodiment of the present invention, and FIG. 5 is a cross-sectional view showing a method of manufacturing the gas sensor 1B.
Since the gas sensor 1B is the same as the gas sensor 1A according to the first embodiment except that the protector 60B, the ceramic holder 30B, and the intermediate member 102 are different, the same components as those of the gas sensor 1A are designated by the same reference numerals. The explanation is omitted.

図４に示すように、プロテクタ６０Ｂは、有底円筒状の内側プロテクタ５２と、有底円筒状の外側プロテクタ６２とを離間して配置した２重プロテクタからなる。
このうち内側プロテクタ５２と外側プロテクタ６２の後端６０Ｂｅが中間部材１０２の内面に重なり合った状態で、内側プロテクタ５２及び外側プロテクタ６２を貫通する溶接部Ｗが形成されている。より具体的には、外側プロテクタ６２の後端が縮径して内側プロテクタ５２の後端に接し、両者が重なった後端６０Ｂｅが形成されている。そして、外側プロテクタ６２の後端と中間部材１０２の内面とが対向し、内側プロテクタ５２から中間部材１０２に向かって溶接部Ｗが形成されている。 As shown in FIG. 4, the protector 60B includes a double protector in which a bottomed cylindrical inner protector 52 and a bottomed cylindrical outer protector 62 are arranged apart from each other.
Of these, a welded portion W that penetrates the inner protector 52 and the outer protector 62 is formed in a state where the inner protector 52 and the rear end 60Be of the outer protector 62 overlap the inner surface of the intermediate member 102. More specifically, the rear end of the outer protector 62 is reduced in diameter and is in contact with the rear end of the inner protector 52, and a rear end 60Be in which both are overlapped is formed. The rear end of the outer protector 62 and the inner surface of the intermediate member 102 face each other, and a welded portion W is formed from the inner protector 52 toward the intermediate member 102.

中間部材１０２は、金属製で一定の径の無底筒状をなしている。中間部材１０２の外径は、主体金具１１の円環状部１８の内径よりわずかに小さく、円環状部１８の内側に中間部材１０２を圧入可能になっている。
そして、主体金具１１の先端側から中間部材１０２を圧入すると、セラミックホルダ３０Ｂの先端に中間部材１０２が当接して圧入深さが調整される。又、セラミックホルダ３０Ｂの先端向き面３０Ｂｆは、主体金具１１の段部１７に直接係止されている。 The intermediate member 102 is made of metal and has a bottomless cylinder shape having a constant diameter. The outer diameter of the intermediate member 102 is slightly smaller than the inner diameter of the annular portion 18 of the main metal fitting 11, and the intermediate member 102 can be press-fitted into the inside of the annular portion 18.
Then, when the intermediate member 102 is press-fitted from the tip end side of the main metal fitting 11, the intermediate member 102 abuts on the tip end of the ceramic holder 30B, and the press-fitting depth is adjusted. Further, the tip facing surface 30Bf of the ceramic holder 30B is directly locked to the step portion 17 of the main metal fitting 11.

ガスセンサ１Ｂは、図５に示すようにして製造することができる。
まず、ガスセンサ１Ａと同様、センサ素子２１を主体金具１１に対して保持させた素子アッセンブリＡｃ２を準備する。但し、素子アッセンブリＡｃ２は中間部材１０２を含まない。
一方、予め、プロテクタ６０Ｂの後端６０Ｂｅに中間部材１０２を溶接して溶接部Ｗを形成しておく。
次に、素子アッセンブリＡｃの先端側に突出した主体金具１１の円環状部１８の内側に、プロテクタ６０Ｂを溶接した中間部材１０２を圧入し、中間部材１０２、ひいてはプロテクタ６０Ｂを主体金具１１に固定する。
そして、ガスセンサ１Ａと同様、各種パーツを収容した外筒８１を主体金具１１の後端側の円筒部１５に嵌め込み、適宜カシメを行うと共に、外筒８１の先端部の外周面の全周にわたってレーザ溶接し、外筒８１を主体金具１１に対して固定する。 The gas sensor 1B can be manufactured as shown in FIG.
First, as with the gas sensor 1A, an element assembly Ac2 in which the sensor element 21 is held by the main metal fitting 11 is prepared. However, the element assembly Ac2 does not include the intermediate member 102.
On the other hand, the intermediate member 102 is welded to the rear end 60Be of the protector 60B in advance to form the welded portion W.
Next, the intermediate member 102 to which the protector 60B is welded is press-fitted into the inside of the annular portion 18 of the main metal fitting 11 protruding toward the tip end side of the element assembly Ac, and the intermediate member 102 and eventually the protector 60B are fixed to the main metal fitting 11. ..
Then, as in the gas sensor 1A, the outer cylinder 81 containing various parts is fitted into the cylindrical portion 15 on the rear end side of the main metal fitting 11, and is appropriately caulked, and the laser is applied over the entire circumference of the outer peripheral surface of the tip portion of the outer cylinder 81. Weld and fix the outer cylinder 81 to the main metal fitting 11.

ガスセンサ１Ｂにおいても、ｔｈ１＜ｔｈ２の関係を満たすことで、溶け込み深さを大きくして中間部材１０２とプロテクタ６０Ｂとの溶接強度を向上させることができる。又、プロテクタ６０Ｂに飛石等の衝撃が掛かった場合に中間部材１０２が変形することを抑制し、プロテクタ６０Ｂを主体金具１１に確実に固定することができる。 Also in the gas sensor 1B, by satisfying the relationship of th1 <th2, the penetration depth can be increased and the welding strength between the intermediate member 102 and the protector 60B can be improved. Further, it is possible to prevent the intermediate member 102 from being deformed when an impact such as a stepping stone is applied to the protector 60B, and to securely fix the protector 60B to the main metal fitting 11.

さらに、Ｔ１，Ｔ２が大きく異なっても、Ｔ２、Ｔ３を近づけることで、溶接部Ｗが高温に曝された後に室温付近に冷却される熱履歴を受けても、溶接部Ｗに応力が生じて溶接部の剥離やクラックが生じることを抑制できる。
又、高温下で中間部材１０２が主体金具１１よりも膨張して主体金具１１の内面に密着する焼嵌め効果が生じ、高温下でも中間部材１０２、ひいてはプロテクタ６０Ｂを主体金具１１により強固に固定できる。
以上により、プロテクタ６０Ｂが高温に曝されたり、プロテクタ６０Ｂに力が掛かっても主体金具１１に確実に固定することができる。 Further, even if T1 and T2 are significantly different, stress is generated in the welded portion W even if the welded portion W is exposed to a high temperature and then cooled to near room temperature by bringing T2 and T3 closer to each other. It is possible to suppress peeling and cracking of the welded portion.
Further, the intermediate member 102 expands more than the main metal fitting 11 at high temperature to produce a shrink fitting effect in which the intermediate member 102 adheres to the inner surface of the main metal fitting 11, and the intermediate member 102 and thus the protector 60B can be firmly fixed by the main metal fitting 11 even at high temperature. ..
As described above, even if the protector 60B is exposed to a high temperature or a force is applied to the protector 60B, it can be reliably fixed to the main metal fitting 11.

なお、本実施形態では、プロテクタ６０Ｂが中間部材１０２の内面に重なり合った状態で溶接部Ｗが形成されると共に、Ｔ３＜Ｔ２の関係を満たす。これにより、高温下でプロテクタ６０Ｂが中間部材１０２よりも膨張して中間部材１０２の内面に密着する焼嵌め効果が生じ、高温下でも中間部材１０２とプロテクタ６０Ｂとをより強固に固定でき、ひいてはプロテクタ６０Ｂを主体金具１１により強固に固定できる。 In this embodiment, the welded portion W is formed in a state where the protector 60B is overlapped with the inner surface of the intermediate member 102, and the relationship of T3 <T2 is satisfied. As a result, the protector 60B expands more than the intermediate member 102 under high temperature to produce a shrink-fitting effect in which the protector 60B adheres to the inner surface of the intermediate member 102, and the intermediate member 102 and the protector 60B can be more firmly fixed even at high temperature, and thus the protector. 60B can be firmly fixed by the main metal fitting 11.

次に、図６を参照し、本発明の第３の実施形態にかかるガスセンサ１Ｃについて説明する。
図６は、本発明の第３の実施形態にかかるガスセンサ１Ｃの断面図である。
なお、ガスセンサ１Ｃは、プロテクタ６０Ｃ、セラミックホルダ３０Ｃ及び中間部材１０４が異なること以外は、第１の実施形態にかかるガスセンサ１Ａと同一であるので、ガスセンサ１Ａと同一構成部分については同一符号を付して説明を省略する。 Next, the gas sensor 1C according to the third embodiment of the present invention will be described with reference to FIG.
FIG. 6 is a cross-sectional view of the gas sensor 1C according to the third embodiment of the present invention.
Since the gas sensor 1C is the same as the gas sensor 1A according to the first embodiment except that the protector 60C, the ceramic holder 30C, and the intermediate member 104 are different, the same components as those of the gas sensor 1A are designated by the same reference numerals. The explanation is omitted.

図６に示すように、プロテクタ６０Ｃは、有底円筒状の１重プロテクタからなる。
そして、プロテクタ６０Ｃの後端６０Ｃｅが中間部材１０４の外面に重なり合った状態で、プロテクタ６０Ｃを貫通する溶接部Ｗが形成されている。より具体的には、プロテクタ６０Ｃから中間部材１０４に向かって溶接部Ｗが形成されている。 As shown in FIG. 6, the protector 60C is composed of a bottomed cylindrical single protector.
A welded portion W penetrating the protector 60C is formed in a state where the rear end 60Ce of the protector 60C overlaps the outer surface of the intermediate member 104. More specifically, the welded portion W is formed from the protector 60C toward the intermediate member 104.

中間部材１０４は、金属製で一定の径の無底筒状をなしている。中間部材１０４の外径は、主体金具１１の円環状部１８の内径よりわずかに小さく、円環状部１８の内側に中間部材１０４を圧入可能になっている。
そして、主体金具１１の先端側から中間部材１０４を圧入すると、セラミックホルダ３０Ｃの先端に中間部材１０４が当接して圧入深さが調整される。又、セラミックホルダ３０Ｃの先端向き面３０Ｃｆは、主体金具１１の段部１７に直接係止されている。 The intermediate member 104 is made of metal and has a bottomless cylinder shape having a constant diameter. The outer diameter of the intermediate member 104 is slightly smaller than the inner diameter of the annular portion 18 of the main metal fitting 11, and the intermediate member 104 can be press-fitted inside the annular portion 18.
Then, when the intermediate member 104 is press-fitted from the tip end side of the main metal fitting 11, the intermediate member 104 comes into contact with the tip end of the ceramic holder 30C, and the press-fitting depth is adjusted. Further, the tip facing surface 30Cf of the ceramic holder 30C is directly locked to the step portion 17 of the main metal fitting 11.

このガスセンサ１Ｃも、ガスセンサ１Ｂと同様にして製造することができる。つまり、中間部材１０４を含まない素子アッセンブリを作成しておくと共に、予め、プロテクタ６０Ｃの後端６０Ｃｅに中間部材１０４を溶接して溶接部Ｗを形成しておく。
そして、素子アッセンブリの先端側に突出した主体金具１１の円環状部１８の内側に、プロテクタ６０Ｃを溶接した中間部材１０４を圧入し、中間部材１０４、ひいてはプロテクタ６０Ｃを主体金具１１に固定する。
そして、各種パーツを収容した外筒８１を主体金具１１の後端側の円筒部１５に嵌め込み、適宜カシメを行うと共に、外筒８１の先端部の外周面の全周にわたってレーザ溶接し、外筒８１を主体金具１１に対して固定する。 The gas sensor 1C can also be manufactured in the same manner as the gas sensor 1B. That is, an element assembly that does not include the intermediate member 104 is created, and the intermediate member 104 is welded to the rear end 60Ce of the protector 60C in advance to form the welded portion W.
Then, the intermediate member 104 to which the protector 60C is welded is press-fitted into the inside of the annular portion 18 of the main metal fitting 11 protruding toward the tip end side of the element assembly, and the intermediate member 104 and eventually the protector 60C are fixed to the main metal fitting 11.
Then, the outer cylinder 81 accommodating various parts is fitted into the cylindrical portion 15 on the rear end side of the main metal fitting 11, caulked appropriately, and laser welded over the entire outer peripheral surface of the tip portion of the outer cylinder 81 to perform laser welding. The 81 is fixed to the main metal fitting 11.

ガスセンサ１Ｃにおいても、ｔｈ１＜ｔｈ２の関係を満たすことで、溶け込み深さを大きくして中間部材１０４とプロテクタ６０Ｃとの溶接強度を向上させることができる。又、プロテクタ６０Ｃに飛石等の衝撃が掛かった場合に中間部材１０４が変形することを抑制し、プロテクタ６０Ｃを主体金具１１に確実に固定することができる。 Also in the gas sensor 1C, by satisfying the relationship of th1 <th2, the penetration depth can be increased and the welding strength between the intermediate member 104 and the protector 60C can be improved. Further, it is possible to prevent the intermediate member 104 from being deformed when an impact such as a stepping stone is applied to the protector 60C, and to securely fix the protector 60C to the main metal fitting 11.

さらに、Ｔ１，Ｔ２が大きく異なっても、Ｔ２、Ｔ３を近づけることで、溶接部Ｗが高温に曝された後に室温付近に冷却される熱履歴を受けても、溶接部Ｗに応力が生じて溶接部の剥離やクラックが生じることを抑制できる。
又、高温下で中間部材１０４が主体金具１１よりも膨張して主体金具１１の内面に密着する焼嵌め効果が生じ、高温下でも中間部材１０４、ひいてはプロテクタ６０Ｃを主体金具１１により強固に固定できる。
以上により、プロテクタ６０Ｃが高温に曝されたり、プロテクタ６０Ｃに力が掛かっても主体金具１１に確実に固定することができる。 Further, even if T1 and T2 are significantly different, stress is generated in the welded portion W even if the welded portion W is exposed to a high temperature and then cooled to near room temperature by bringing T2 and T3 closer to each other. It is possible to suppress peeling and cracking of the welded portion.
Further, the intermediate member 104 expands more than the main metal fitting 11 at high temperature to produce a shrink fitting effect in which the intermediate member 104 adheres to the inner surface of the main metal fitting 11, and the intermediate member 104 and thus the protector 60C can be firmly fixed by the main metal fitting 11 even at high temperature. ..
As described above, even if the protector 60C is exposed to a high temperature or a force is applied to the protector 60C, it can be reliably fixed to the main metal fitting 11.

又、本実施形態でもガスセンサ１Ａと同様、Ｔ３＝Ｔ２の関係を満たす。これにより、プロテクタ６０Ｃと中間部材１０４の構成材料の２０～８５０℃における熱膨張率が等しいので、プロテクタ６０Ｃが高温に曝されても溶接部Ｗに応力が生じることを抑制できる。 Further, also in this embodiment, the relationship of T3 = T2 is satisfied as in the gas sensor 1A. As a result, since the coefficients of thermal expansion of the protector 60C and the constituent materials of the intermediate member 104 at 20 to 850 ° C. are equal, it is possible to suppress the generation of stress in the welded portion W even when the protector 60C is exposed to a high temperature.

本発明のガスセンサは、本発明の要旨を逸脱しない限りにおいて、適宜にその構造、構成を設計変更して具体化できる。
センサ素子は板状に限らず、筒状素子でもよい。
プロテクタの構造や形状も上記実施形態に限定されないし、中間部材を主体金具の先端側の内面に係合する方法も限定されない。
また、プロテクタが中間部材の外面に重なり合った状態で溶接部が形成される場合において、Ｔ３＞Ｔ２としてもよい。この場合、高温下で中間部材がプロテクタよりも膨張してプロテクタの内面に密着する焼嵌め効果が生じ、高温下でも中間部材とプロテクタとをより強固に固定でき、ひいてはプロテクタを主体金具により強固に固定できる。 The structure and configuration of the gas sensor of the present invention can be appropriately redesigned and embodied without departing from the gist of the present invention.
The sensor element is not limited to a plate shape, but may be a cylindrical element.
The structure and shape of the protector are not limited to the above embodiment, and the method of engaging the intermediate member with the inner surface on the tip end side of the main metal fitting is not limited.
Further, when the welded portion is formed in a state where the protector overlaps the outer surface of the intermediate member, T3> T2 may be set. In this case, the intermediate member expands more than the protector at high temperature to produce a shrink-fitting effect that adheres to the inner surface of the protector, and the intermediate member and protector can be fixed more firmly even at high temperature, and the protector is firmly fixed by the main metal fitting. Can be fixed.

１Ａ，１Ｂ、１Ｃガスセンサ
１１主体金具
２１センサ素子
２２検知部
４１シール部材
６０Ａ，６０Ｂ，６０Ｃプロテクタ
１００、１０２、１０４中間部材
Ｏ軸線
Ｗ溶接部 1A, 1B, 1C Gas sensor 11 Main metal fittings 21 Sensor element 22 Detection part 41 Seal member 60A, 60B, 60C Protector 100, 102, 104 Intermediate member O Axis line W Welded part

Claims

A sensor element that extends in the axial direction and has a detection unit that detects a specific gas in the gas to be measured on the tip side.
A cylindrical main metal fitting that surrounds and holds the radial periphery of the sensor element on the rear end side of the detection unit, and
A protector that has a cylindrical shape that surrounds the tip side of the sensor element and can introduce or discharge the gas to be measured.
It is a gas sensor equipped with
In addition, it is equipped with a cylindrical intermediate member.
A welded portion is formed with the protector overlapping on the outer surface or the inner surface of the intermediate member.
The intermediate member is press-fitted or engaged with the inner surface on the tip end side of the main metal fitting.
When the thickness th1 of the protector and the thickness th2 of the intermediate member are compared at the overlapping portion between the intermediate member and the protector adjacent to the welded portion, the relationship of th1 <th2 is satisfied.
The coefficient of thermal expansion of the constituent material of the main metal fitting at 20 to 850 ° C. is T1, the coefficient of thermal expansion of the constituent material of the protector at 20 to 850 ° C. is T2, and the coefficient of thermal expansion of the constituent material of the intermediate member at 20 to 850 ° C. Is T3, the gas sensor is characterized in that the relationship of T2> T1 and T3> T1 is satisfied.

The gas sensor according to claim 1, wherein the intermediate member has a bottomless cylindrical shape.

A sealing member is arranged between the outer surface of the sensor element and the inner surface of the main metal fitting.
The gas sensor according to claim 1 or 2, wherein the intermediate member and the seal member overlap at least a part when viewed from the axial direction.

A sealing member is arranged between the outer surface of the sensor element and the inner surface of the main metal fitting.
The gas sensor according to any one of claims 1 to 3, wherein the intermediate member is located on the distal end side of the seal member.

The welded portion is formed with the protector overlapping the outer surface of the intermediate member.
The gas sensor according to any one of claims 1 to 4, wherein the gas sensor satisfies the relationship of T3> T2.

The welded portion is formed with the protector overlapping the inner surface of the intermediate member.
The gas sensor according to any one of claims 1 to 4, wherein the relationship of T3 <T2 is satisfied.

The gas sensor according to any one of claims 1 to 4, wherein the gas sensor satisfies the relationship of T3 = T2.

The gas sensor according to any one of claims 1 to 7, wherein the weld portion does not penetrate the intermediate member.