JP2023064825A - gas sensor - Google Patents

gas sensor Download PDF

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JP2023064825A
JP2023064825A JP2021175204A JP2021175204A JP2023064825A JP 2023064825 A JP2023064825 A JP 2023064825A JP 2021175204 A JP2021175204 A JP 2021175204A JP 2021175204 A JP2021175204 A JP 2021175204A JP 2023064825 A JP2023064825 A JP 2023064825A
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diameter portion
outer cylinder
rear end
small
stepped portion
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昌史 野村
Masashi Nomura
邦彦 米津
Kunihiko Yonezu
大介 松山
Daisuke Matsuyama
優人 猪瀬
Yuto Inose
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Niterra Co Ltd
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NGK Spark Plug Co Ltd
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Priority to JP2021175204A priority Critical patent/JP2023064825A/en
Priority to PCT/JP2022/025268 priority patent/WO2023074046A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/409—Oxygen concentration cells
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/41—Oxygen pumping cells
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/417—Systems using cells, i.e. more than one cell and probes with solid electrolytes
    • G01N27/419—Measuring voltages or currents with a combination of oxygen pumping cells and oxygen concentration cells

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Abstract

To provide a gas sensor that suppresses damage to an outer cylinder due to vibration while reducing a diameter of a separator.SOLUTION: A gas sensor 1 includes: a sensor element 21; a main metal fitting 11; a metallic and cylindrical outer cylinder 81 housing a rear end side of the sensor element; and a separator 91 holding a terminal metal fitting 75. The outer cylinder has: a large-diameter portion 81a; a small-diameter portion 81c arranged on a rear end side of the large-diameter portion and extending straight; and a stepped portion 81d connected to the large-diameter portion and the small-diameter portion by a connection line L1 and extending in a radial direction. In addition, the outer cylinder has a plurality of convex reinforcing ribs 81e connected to the small-diameter portion and protruding outside the small-diameter portion, and connected to a part of the stepped portion across the connection line and protruding from the stepped portion to a rear end side. A rear end facing surface of the separator is engaged with a front-end facing surface of the stepped portion. A drawing ratio represented by a ratio D2/D1 between an inner diameter D1 of the large-diameter portion and an inner diameter D2 of the small-diameter portion on a tip-facing surface of the stepped portion is 0.72 or less. The reinforcing ribs are arranged spaced circumferentially.SELECTED DRAWING: Figure 2

Description

本発明は、センサ素子を収容する外筒を備えたガスセンサに関する。 The present invention relates to a gas sensor provided with an outer cylinder housing a sensor element.

従来から、被測定ガス中の特定ガスを検出するセンサ素子を主体金具に保持し、センサ素子の後端側を金属製の外筒に収容した構成のガスセンサが知られている。ここで、外筒の先端側は主体金具の後端側に接続され、外筒の後端側は固定されていない自由端となっている。又、外筒の先端側は大径部となっていて、大径部の後端側には段部を介して小径部が形成されている。そして、この段部の内側（先端向き面）に、セパレータの後端側を係止させている（特許文献１）。 Conventionally, there has been known a gas sensor configured such that a sensor element for detecting a specific gas in a gas to be measured is held by a metal shell, and the rear end side of the sensor element is accommodated in a metal outer cylinder. Here, the front end side of the outer cylinder is connected to the rear end side of the metal shell, and the rear end side of the outer cylinder is a free end that is not fixed. The outer cylinder has a large-diameter portion on the front end side, and a small-diameter portion is formed on the rear end side of the large-diameter portion via a stepped portion. Then, the rear end side of the separator is engaged with the inside of the stepped portion (surface facing the tip) (Patent Document 1).

特開２００５－１７２７８号公報Japanese Unexamined Patent Application Publication No. 2005-17278

ところが、このガスセンサを車両等に搭載して使用すると、車両の走行振動等によって、自由端となる外筒の後端側が振れ、主体金具との接続部位に近い外筒の段部付近に応力が集中して亀裂が生じるという不具合がある。
ここで、上述のように、外筒の段部の内側には重量物であるセパレータが保持されているため、振動等による外筒の振れを大きくする作用がある、そこで、セパレータを軽量化（小径化）することで外筒の振れを低減する対策が考えられる。しかしながら、セパレータを小径化するためには、大径部に比べて小径部をより細くする必要があり、段部のくびれが大きくなって段部付近の亀裂を促進することが判明した。
さらに、一般に外筒の後端側にはゴム製のグロメットが保持されるが、ガスセンサの使用環境が高温になり、グロメットの耐熱温度を超えると、グロメットによる気密性の確保が困難になる。そこで、外筒の厚みを薄くして外筒からグロメットへの熱伝導を抑制する対策がある。しかし、この場合には振動等による外筒の破損がより生じ易くなる。 However, when this gas sensor is mounted on a vehicle and used, the rear end of the outer cylinder, which is the free end, vibrates due to the running vibration of the vehicle, etc., and stress is applied near the stepped portion of the outer cylinder near the joint with the metal shell. There is a problem that cracks are generated intensively.
Here, as described above, since the separator, which is a heavy object, is held inside the stepped portion of the outer cylinder, it has the effect of increasing the vibration of the outer cylinder due to vibrations, etc. Therefore, the weight of the separator is reduced ( A possible countermeasure is to reduce the runout of the outer cylinder by reducing the diameter of the outer cylinder. However, in order to reduce the diameter of the separator, it is necessary to make the small diameter portion thinner than the large diameter portion.
Furthermore, a rubber grommet is generally held on the rear end side of the outer cylinder, but if the operating environment of the gas sensor becomes hot and exceeds the heat resistance temperature of the grommet, it becomes difficult to ensure airtightness with the grommet. Therefore, there is a countermeasure to suppress heat conduction from the outer cylinder to the grommet by reducing the thickness of the outer cylinder. However, in this case, damage to the outer cylinder due to vibration or the like is more likely to occur.

本発明は、かかる現状に鑑みてなされたものであって、セパレータを小径化しつつ、振動による外筒の破損を抑制したガスセンサを提供することを目的とする。 SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas sensor in which the diameter of the separator is reduced and damage to the outer cylinder due to vibration is suppressed.

本発明のガスセンサは、軸線方向に延びるセンサ素子と、前記センサ素子を取り囲んで保持する主体金具と、前記主体金具の後端側に取り付けられ、前記センサ素子の後端側を収容する金属製で筒状の外筒と、前記外筒に収容され、前記センサ素子に接続される端子金具を保持するセパレータと、を備えたガスセンサであって、前記外筒は大径部と、前記大径部よりも後端側に配置されストレートに延びる小径部と、前記大径部に接続されると共に前記小径部に接続線にて接続されて径方向に延びる段部と、を有し、さらに、前記小径部に接続されて前記小径部よりも外側に突出すると共に、前記接続線を跨いで前記段部の一部に接続されて前記段部よりも後端側に突出する複数の凸状の補強リブを有し、前記セパレータの後端向き面が前記段部の先端向き面に係止され、前記段部の先端向き面における前記大径部の内径Ｄ１と、前記小径部の内径Ｄ２との比Ｄ２/Ｄ１で表される絞り率が０．７２以下であり、前記補強リブが周方向に離間して配置されることを特徴とする。 The gas sensor of the present invention comprises a sensor element extending in an axial direction, a metal shell surrounding and holding the sensor element, and a metal body attached to the rear end side of the metal shell and accommodating the rear end side of the sensor element. A gas sensor comprising a cylindrical outer cylinder and a separator that is housed in the outer cylinder and holds terminal fittings connected to the sensor element, wherein the outer cylinder has a large diameter portion and the large diameter portion. and a stepped portion connected to the large-diameter portion and connected to the small-diameter portion by a connection line and extending in the radial direction, and further comprising: A plurality of convex reinforcements connected to the small-diameter portion and protruding outside the small-diameter portion, straddling the connection line and connected to a part of the stepped portion and protruding toward the rear end side of the stepped portion. The separator has a rib, the rear end facing surface of the separator is engaged with the front end facing surface of the stepped portion, and the inner diameter D1 of the large diameter portion and the inner diameter D2 of the small diameter portion on the front end facing surface of the stepped portion are equal to each other. The drawing ratio represented by the ratio D2/D1 is 0.72 or less, and the reinforcing ribs are spaced apart in the circumferential direction.

このガスセンサによれば、Ｄ２/Ｄ１≦０．７２とすることで、段部の径方向長さが長くなるので、セパレータを小型化（小径化）しても段部に確実に係止させて固定することができる。その結果、外筒内部の重量物であるセパレータを小径化（軽量化）することができ、振動等による外筒の振れを低減することができる。又、セパレータを小径化することで、ガスセンサ１全体の軽量化やコストダウンを実現できる。
一方、セパレータを小径化するために、上述のようにＤ２/Ｄ１≦０．７２とすると、大径部に比べて小径部がより細くなり、段部のくびれが大きくなって段部と小径部の接続線付近の亀裂を促進する。
そこで、接続線を跨いで小径部と段部との一部に複数の凸状の補強リブを設けることで、段部の特に接続線付近の強度を向上させ、セパレータを小径化しつつ、振動による外筒の破損を抑制することができる。 According to this gas sensor, by setting D2/D1≦0.72, the radial length of the stepped portion is increased, so even if the size of the separator is reduced (reduced in diameter), the stepped portion can be reliably retained. can be fixed. As a result, it is possible to reduce the diameter (lighten) of the separator, which is a heavy object inside the outer cylinder, and to reduce the deflection of the outer cylinder due to vibration or the like. Further, by reducing the diameter of the separator, the weight and cost of the gas sensor 1 can be reduced.
On the other hand, if D2/D1≤0.72 as described above in order to reduce the diameter of the separator, the small diameter portion becomes thinner than the large diameter portion, and the constriction of the stepped portion becomes large. promoting cracks near the connecting lines of
Therefore, by providing a plurality of convex reinforcing ribs on a part of the small-diameter portion and the stepped portion across the connection line, the strength of the stepped portion, especially in the vicinity of the connection line, is improved. Damage to the outer cylinder can be suppressed.

本発明のガスセンサにおいて、前記補強リブの外面が前記段部及び前記小径部の外面に沿った形状であってもよい。
このガスセンサによれば、リブをプレス加工等で形成する際の外筒の変形量が少なく、残留応力が小さくなるため、振動による外筒の応力腐食割れを抑制できる。 In the gas sensor of the present invention, the outer surface of the reinforcing rib may have a shape along the outer surfaces of the step portion and the small diameter portion.
According to this gas sensor, the amount of deformation of the outer cylinder when the ribs are formed by press working or the like is small, and the residual stress is small, so stress corrosion cracking of the outer cylinder due to vibration can be suppressed.

本発明のガスセンサにおいて、前記外筒の後端側に、前記端子金具に接続されたリード線を挿通する挿通孔を有するグロメットが保持され、前記外筒の最大厚みが０．４ｍｍ以下であってもよい。
このガスセンサによれば、外筒の厚みが薄いので、外筒の後端側にグロメットが保持されている場合に、外筒からグロメットへの熱伝導を抑制することができる。特に、ガスセンサの使用環境が高温になり、グロメットの耐熱温度を超え易い場合に有利である。
また、補強リブを設けることで、外筒の厚みが薄くなっても振動等による外筒の破損を抑制できる。 In the gas sensor of the present invention, a grommet having an insertion hole for inserting a lead wire connected to the terminal fitting is held at the rear end side of the outer cylinder, and the outer cylinder has a maximum thickness of 0.4 mm or less. good too.
According to this gas sensor, since the thickness of the outer cylinder is thin, heat conduction from the outer cylinder to the grommet can be suppressed when the grommet is held on the rear end side of the outer cylinder. In particular, it is advantageous when the gas sensor is used in a high-temperature environment and easily exceeds the heat-resistant temperature of the grommet.
Further, by providing the reinforcing ribs, damage to the outer cylinder due to vibration or the like can be suppressed even if the thickness of the outer cylinder is reduced.

この発明によれば、セパレータを小径化しつつ、振動による外筒の破損を抑制したガスセンサが得られる。 According to the present invention, it is possible to obtain a gas sensor in which damage to the outer cylinder due to vibration is suppressed while the diameter of the separator is reduced.

本発明の実施形態にかかるガスセンサの断面図である。1 is a cross-sectional view of a gas sensor according to an embodiment of the invention; FIG. 外筒の斜視図である。It is a perspective view of an outer cylinder. 外筒の上面図である。It is a top view of an outer cylinder. 外筒の変形例を示す斜視図である。It is a perspective view which shows the modification of an outer cylinder.

本発明の実施形態について、図１～図３に基づいて詳細に説明する。図１は、本発明の実施形態にかかるガスセンサの断面図、図２は外筒８１の斜視図、図３は外筒８１の上面図である。 An embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3. FIG. 1 is a cross-sectional view of a gas sensor according to an embodiment of the present invention, FIG. 2 is a perspective view of an outer cylinder 81, and FIG. 3 is a top view of the outer cylinder 81. FIG.

図１において、ガスセンサ（全領域空燃比ガスセンサ）１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）３０と、セラミックホルダ３０の径方向周囲を取り囲む主体金具１１と、外筒８１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３０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３０の後端面側（図示上側）に配置されたシール材（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２９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２９寄り部位に形成された各電極パッド２４に、グロメット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、この電極パッド２４を含むセンサ素子２１の後端２９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, a gas sensor (full-range air-fuel ratio gas sensor) 1 includes a sensor element 21, a holder (ceramic holder) 30 having a through hole 32 passing through in the direction of the axis O and through which the sensor element 21 is inserted, and a ceramic holder 30. It is provided with a metal shell 11 and an outer cylinder 81 that surround the periphery in the radial direction.
A part of the sensor element 21 near the tip where the detection part 22 is formed protrudes from the ceramic holder 30 to the tip. The sensor element 21 passed through the through-hole 32 in this manner is connected to a seal material (talc in this example) 41 arranged on the rear end surface side (upper side in the figure) of the ceramic holder 30, a sleeve 43 made of an insulating material, and a ring washer. By compressing it in the front-rear direction via 45 , it is fixed airtightly in the front-rear direction inside the metal shell 11 .
A portion near the rear end 29 including the rear end 29 of the sensor element 21 protrudes rearward from the sleeve 43 and the metal shell 11, and the electrode pads 24 formed near the rear end 29 are connected to the outside through a grommet 85. A terminal fitting 75 provided at the tip of each lead wire 71 drawn out is press-contacted and electrically connected. A portion of the sensor element 21 near the rear end 29 including the electrode pad 24 is covered with an outer cylinder 81 . Further details will be described below.

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接続用の電極パッド２４が露出形成されている。 The sensor element 21 extends in the direction of the axis O, and on the tip side (lower side in the figure) directed toward the object to be measured, there is a detection part 22 comprising a detection electrode and the like (not shown) for detecting a specific gas component in the gas to be detected. It has a strip shape (plate shape) with The cross section of the sensor element 21 has a rectangular (rectangular) shape with a certain size on the front and rear sides, and is formed as an elongated body mainly made of ceramic (such as a solid electrolyte). The sensor element 21 itself is the same as the conventionally known one, and a pair of detection electrodes forming a detection part 22 is arranged at a portion near the tip of the solid electrolyte (member), and connected to the electrode near the rear end. , an electrode pad 24 for connecting a lead wire 71 for taking out an output for detection is formed to be exposed.

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接続用の電極パッド２４が露出形成されている。なお、図示はしないが、これら電極パッド２４は縦長矩形に形成され、例えばセンサ素子２１の後端２９寄り部位において、帯板の幅広面（両面）に３つ又は２つの電極パッドが横に並んでいる。
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。 Further, in this example, a heater (not shown) is provided inside the sensor element 21 near the front end of the ceramic material formed in a layered shape on the solid electrolyte (member), and a heater (not shown) is provided at the rear end near the part. , an electrode pad 24 for connecting a lead wire 71 for applying a voltage to the heater is formed to be exposed. Although not shown, these electrode pads 24 are formed in a vertically elongated rectangular shape. For example, three or two electrode pads are arranged horizontally on the wide surfaces (both sides) of the strip at the rear end 29 side of the sensor element 21. I'm in.
The sensing portion 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、後述するプロテクタ６０を外嵌して固定するための円筒状の円環状部（以下、円筒部ともいう）１２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１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。
一方、主体金具１１は、軸線Ｏ方向に貫通する内孔１８を有している。内孔１８の内周面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 metal shell 11 has a concentric tube shape with different diameters at the front and rear ends, a small diameter at the front end, and a cylindrical annular portion (hereinafter also referred to as a cylindrical portion) 12 for externally fitting and fixing a protector 60 to be described later. A screw 13 having a larger diameter for fixing to the exhaust pipe of the engine is provided on the outer peripheral surface behind it (upper in the drawing). A polygonal portion 14 for screwing the sensor 1 with this screw 13 is provided behind it. Further, behind the polygonal portion 14, a cylindrical portion 15 is continuously provided to which a protective cylinder (outer cylinder) 81 that covers the rear of the gas sensor 1 is fitted and welded. It has a small and thin cylindrical portion 16 for caulking. The crimping cylindrical portion 16 is bent inward in FIG. 1 for after crimping. A gasket 19 is attached to the lower surface of the polygonal portion 14 for sealing during screwing.
On the other hand, the metal shell 11 has an inner hole 18 penetrating in the axis O direction. The inner peripheral surface of the inner hole 18 has a tapered step portion 17 that tapers radially inward from the rear end side to the front end 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３０が配置されている。セラミックホルダ３０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３０ａを有している。そして、先端向き面３０ａの外周寄りの部位が段部１７に係止されつつ、セラミックホルダ３０が後端側からシール材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３０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３０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 metal shell 11, a ceramic holder 30 made of an insulating ceramic (for example, alumina) and having a substantially short cylindrical shape is arranged. The ceramic holder 30 has a tip-facing surface 30a tapered toward the tip. The ceramic holder 30 is positioned in the metallic shell 11 by pressing the ceramic holder 30 from the rear end side with the sealing material 41 while the portion near the outer periphery of the tip facing surface 30a is engaged with the stepped portion 17. And it is fitted with a gap.
On the other hand, the through-hole 32 is provided in the center of the ceramic holder 30 and is a rectangular opening having approximately the same dimensions as the cross section of the sensor element 21 so that the sensor element 21 can pass therethrough without any gap.

センサ素子２１は、セラミックホルダ３０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３０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、本形態では、１重構造からなり、通気孔（穴）６１，６３を有する有底円筒状のプロテクタ（保護カバー）６０で覆われている。そして、プロテクタ６０の後端が、主体金具１１の円筒部１２に外嵌され、溶接されている。なお、通気孔６１はプロテクタ６０の軸線Ｏ方向の中央付近の段部に周方向に離間して複数個設けられている。一方プロテクタ６０の先端側に、排出穴となる通気孔６３が一個設けられている。 The sensor element 21 is passed through the through hole 32 of the ceramic holder 30 , and the tip of the sensor element 21 protrudes further than the tips of the ceramic holder 30 and metal shell 11 .
On the other hand, in this embodiment, the tip portion of the sensor element 21 has a single-layer structure and is covered with a bottomed cylindrical protector (protective cover) 60 having ventilation holes (holes) 61 and 63 . The rear end of the protector 60 is fitted onto the cylindrical portion 12 of the metal shell 11 and welded. A plurality of ventilation holes 61 are provided in a stepped portion near the center of the protector 60 in the direction of the axis O so as to be spaced apart in the circumferential direction. On the other hand, one ventilation hole 63 serving as a discharge hole is provided on the tip side of the protector 60 .

又、図１に示すように、センサ素子２１の後端２９寄り部位に形成された各電極パッド２４には、外部にグロメット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、本例のガスセンサ１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保持されている。なお、セパレータ９１は、外筒８１内にカシメ固定された保持金具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１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グロメット（例えばゴム）８５を通されて外部に引き出されており、小径筒部８１ｃを縮径カシメしてこのグロメット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。 Further, as shown in FIG. 1, each electrode pad 24 formed near the rear end 29 of the sensor element 21 has terminal metal fittings provided at the tips of the lead wires 71 drawn out through the grommet 85 to the outside. 75 is press-contacted by its springiness and electrically connected. In the gas sensor 1 of the present embodiment, the terminal fittings 75 including the press-contact portion are held in opposing positions in respective accommodating portions provided in the insulating separator 91 arranged in the outer cylinder 81 . there is The movement of the separator 91 in the radial direction and toward the distal end side is restricted via a holding metal fitting 82 crimped and fixed in the outer cylinder 81 . The front end of the outer cylinder 81 is fitted onto and welded to the cylindrical portion 15 near the rear end of the metal shell 11 , thereby airtightly covering the rear of the gas sensor 1 .
The lead wire 71 passes through a grommet (e.g., rubber) 85 disposed inside the rear end portion of the outer cylinder 81 and is led out to the outside. By compressing, this portion is kept airtight.

次に、図１～図３を参照し、外筒８１について詳しく説明する。
外筒８１は、大径部８１ａと、大径部８１ａよりも後端側に配置されて軸線Ｏ方向にストレートに延びる小径部８１ｃと、大径部８１ａに接続されると共に小径部８１ｃに接続線Ｌ１にて接続されて径方向に延びる段部８１ｄと、補強リブ８１ｅと、を有している。
段部８１ｄは外筒８１の軸線Ｏ方向の中央よりやや後端側に形成されている。接続線Ｌ１は小径部８１ｃの先端でもあり、環状になっている。 Next, the outer cylinder 81 will be described in detail with reference to FIGS. 1 to 3. FIG.
The outer cylinder 81 includes a large-diameter portion 81a, a small-diameter portion 81c arranged on the rear end side of the large-diameter portion 81a and extending straight in the direction of the axis O, and connected to the large-diameter portion 81a and the small-diameter portion 81c. It has a radially extending stepped portion 81d connected by a line L1 and a reinforcing rib 81e.
The stepped portion 81d is formed slightly rearward from the center of the outer cylinder 81 in the direction of the axis O. As shown in FIG. The connection line L1 is also the tip of the small diameter portion 81c and has a ring shape.

一方、補強リブ８１ｅは、小径部８１ｃに接続されると共に、接続線Ｌ１を跨いで段部８１ｄの一部に接続されている。
又、補強リブ８１ｅは、小径部８１ｃと段部８１ｄから隆起するように形成されている。つまり、補強リブ８１ｅは、小径部８１ｃよりも外側に突出すると共に、段部８１ｄよりも後端側に突出してなる複数の凸状の部材である。
ここで、補強リブ８１ｅの位置では、小径部８１ｃと段部８１ｄとの境界が隆起するため、接続線Ｌ１は存在しない。そこで、補強リブ８１ｅの位置では、補強リブ８１ｅを除く小径部８１ｃと段部８１ｄの間の接続線Ｌ１を外挿した仮想線を接続線Ｌ１とみなす。 On the other hand, the reinforcing rib 81e is connected to the small-diameter portion 81c and is also connected to a part of the stepped portion 81d across the connection line L1.
Further, the reinforcing rib 81e is formed so as to protrude from the small diameter portion 81c and the stepped portion 81d. That is, the reinforcing ribs 81e are a plurality of convex members that protrude outward from the small-diameter portion 81c and protrude further to the rear end side than the stepped portion 81d.
Here, since the boundary between the small diameter portion 81c and the stepped portion 81d rises at the position of the reinforcing rib 81e, the connecting line L1 does not exist. Therefore, at the position of the reinforcing rib 81e, a virtual line extrapolated from the connecting line L1 between the small-diameter portion 81c and the stepped portion 81d excluding the reinforcing rib 81e is regarded as the connecting line L1.

なお、本例では、補強リブ８１ｅは接続線Ｌ１から段部８１ｄに沿うように径方向外側に延びるが、大径部８１ａまで延びずに段部８１ｄの径方向中央付近で終端となっている。
そして、図２に示すように、各補強リブ８１ｅは周方向に離間して（本例では６個）配置されている。 In this example, the reinforcing rib 81e extends radially outward from the connection line L1 along the stepped portion 81d, but does not extend to the large diameter portion 81a and terminates near the radial center of the stepped portion 81d. .
As shown in FIG. 2, the reinforcing ribs 81e are spaced apart in the circumferential direction (six in this example).

ここで、外筒８１の内面側から見ると、補強リブ８１ｅが段部８１ｄより凹んでいるので、セパレータ９１の後端向き面９１ｅは段部８１ｄの先端向き面に係止されることになる。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金具８２の上に支持させられており、段部８１ｄと保持金具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。
なお、大径部８１ａを径方向内側に加締めた第１加締め部８１ｐにより、保持金具８２が外筒８１の内側に固定されている。又、小径部８１ｃの後端側を径方向内側に加締めた第２加締め部８１ｒにより、グロメット８５が外筒８１の内側に固定されている。
又、「セパレータ９１の後端向き面が段部８１ｄの先端向き面に係止される」とは、セパレータ９１の後端向き面の一部が段部８１ｄの先端向き面の一部に片当たりしていてもよいものとする。 Here, when viewed from the inner surface side of the outer cylinder 81, the reinforcing rib 81e is recessed from the stepped portion 81d, so that the rear end facing surface 91e of the separator 91 is engaged with the leading end facing surface of the stepped portion 81d. . On the other hand, the flange 93 formed on the outer periphery of the separator 91 is supported on a holding metal fitting 82 fixed inside the outer cylinder 81, and the step portion 81d and the holding metal fitting 82 move the separator 91 in the direction of the axis O is held in
The holding metal fitting 82 is fixed inside the outer cylinder 81 by a first crimping portion 81p which crimps the large diameter portion 81a radially inward. Further, the grommet 85 is fixed inside the outer cylinder 81 by a second crimping portion 81r which crimps the rear end side of the small diameter portion 81c radially inward.
Further, "the rear-end-facing surface of the separator 91 is engaged with the front-end-facing surface of the stepped portion 81d" means that a part of the rear-end-facing surface of the separator 91 is engaged with a part of the front-facing surface of the stepped portion 81d. It is assumed that it is acceptable to hit.

さらに、段部８１ｄの先端向き面における大径部８１ａの内径Ｄ１と、小径部８１ｃの内径Ｄ２との比Ｄ２/Ｄ１で表される絞り率が０．７２以下である。
このように、Ｄ２/Ｄ１≦０．７２とすることで、段部８１ｄの径方向長さが長くなるので、セパレータ９１を小型化（小径化）しても段部８１ｄに確実に係止させて固定することができる。その結果、外筒８１内部の重量物であるセパレータ９１を小径化（軽量化）することができ、振動等による外筒の振れを低減することができる。又、セパレータ９１を小径化することで、ガスセンサ１全体の軽量化やコストダウンを実現できる。 Furthermore, the drawing ratio represented by the ratio D2/D1 between the inner diameter D1 of the large-diameter portion 81a and the inner diameter D2 of the small-diameter portion 81c on the tip-facing surface of the stepped portion 81d is 0.72 or less.
By setting D2/D1≦0.72 in this way, the radial length of the stepped portion 81d is increased, so that even if the separator 91 is made smaller (reduced in diameter), it can be reliably engaged with the stepped portion 81d. can be fixed. As a result, it is possible to reduce the diameter (lighten) of the separator 91, which is a heavy object inside the outer cylinder 81, and to reduce the deflection of the outer cylinder due to vibration or the like. Further, by reducing the diameter of the separator 91, the weight and cost of the gas sensor 1 as a whole can be reduced.

一方、セパレータ９１を小径化するために、上述のようにＤ２/Ｄ１≦０．７２とすると、大径部８１ａに比べて小径部８１ｃがより細くなり、段部８１ｄのくびれが大きくなって段部８１ｄと小径部８１ｃの接続線Ｌ１付近の亀裂を促進することが判明した。
そこで、接続線Ｌ１を跨いで小径部８１ｃと段部８１ｄとの一部に複数の凸状の補強リブ８１ｅを設けることで、段部８１ｄの特に接続線Ｌ１付近の強度を向上させ、セパレータ９１を小径化しつつ、振動による外筒８１の破損を抑制することができる。 On the other hand, if D2/D1≤0.72 as described above in order to reduce the diameter of the separator 91, the small diameter portion 81c becomes thinner than the large diameter portion 81a, and the stepped portion 81d becomes narrower. It was found that cracks near the connecting line L1 between the portion 81d and the small diameter portion 81c are accelerated.
Therefore, by providing a plurality of convex reinforcing ribs 81e on a part of the small-diameter portion 81c and the stepped portion 81d across the connection line L1, the strength of the stepped portion 81d, especially in the vicinity of the connection line L1, is improved. While reducing the diameter of the outer cylinder 81, damage to the outer cylinder 81 due to vibration can be suppressed.

Ｄ２/Ｄ１が０．６５以下であると、セパレータ９１をさらに小径化できるので、好ましい。Ｄ２/Ｄ１の下限は制限されないが、例えば０．５である。 When D2/D1 is 0.65 or less, the diameter of the separator 91 can be further reduced, which is preferable. The lower limit of D2/D1 is not limited, but is, for example, 0.5.

また、本例においては、図２に示すように、補強リブ８１ｅの外面が段部８１ｄ及び小径部８１ｃの外面に沿った形状である。
このようにすると、リブをプレス加工等で形成する際の外筒の変形量が少なく、残留応力が小さくなるため、振動による外筒の応力腐食割れを抑制できる。
なお、「補強リブ８１ｅの外面が段部８１ｄ及び小径部８１ｃの外面に沿った形状」とは、補強リブ８１ｅの外面が段部８１ｄ及び小径部８１ｃの外面と略平行なことをいう。本例では、図１の断面を見たときに、補強リブ８１ｅの外面の輪郭が、段部８１ｄ及び小径部８１ｃの外面の輪郭に沿って略Ｌ字状になっている。 In this example, as shown in FIG. 2, the outer surface of the reinforcing rib 81e has a shape along the outer surfaces of the stepped portion 81d and the small diameter portion 81c.
In this way, the amount of deformation of the outer cylinder when the ribs are formed by press working or the like is small, and the residual stress is reduced, so that stress corrosion cracking of the outer cylinder due to vibration can be suppressed.
Note that "the outer surface of the reinforcing rib 81e follows the outer surfaces of the stepped portion 81d and the small diameter portion 81c" means that the outer surface of the reinforcing rib 81e is substantially parallel to the outer surfaces of the stepped portion 81d and the small diameter portion 81c. In this example, when the cross section of FIG. 1 is viewed, the contour of the outer surface of the reinforcing rib 81e is substantially L-shaped along the contours of the outer surfaces of the stepped portion 81d and the small diameter portion 81c.

外筒８１の最大厚みが０．４ｍｍ以下であると、外筒８１の後端側にグロメット８５が保持されている場合に、外筒８１からグロメット８５への熱伝導を抑制することができる。そして、補強リブ８１ｅを設けることで、外筒８１の厚みが薄くなっても振動等による外筒８１の破損を抑制できる。 When the maximum thickness of the outer cylinder 81 is 0.4 mm or less, heat conduction from the outer cylinder 81 to the grommet 85 can be suppressed when the grommet 85 is held on the rear end side of the outer cylinder 81 . By providing the reinforcing ribs 81e, damage to the outer cylinder 81 due to vibration or the like can be suppressed even if the thickness of the outer cylinder 81 is reduced.

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。
例えば、図４に示すように、外筒１８１の各補強リブ１８１ｅが接続線Ｌ１から段部１８１ｄに沿うように径方向外側に大径部１８１ａまで延びていてもよい。
又、図４に示すように、各補強リブ１８１ｅの外面が接続線Ｌ１から径方向外側に向かって先端に下がり、大径部１８１ａに接続するようなフラット面であってもよい。
センサ素子としては、酸素の濃度を測定するものに限定されず、窒素酸化物（ＮＯｘ）又は炭化水素（ＨＣ）等の濃度を測定するものを用いてもよい。 The gas sensor of the present invention can be embodied by appropriately changing its structure and configuration without departing from the gist of the present invention.
For example, as shown in FIG. 4, each reinforcing rib 181e of the outer cylinder 181 may extend radially outward from the connection line L1 along the stepped portion 181d to the large diameter portion 181a.
Further, as shown in FIG. 4, the outer surface of each reinforcing rib 181e may be a flat surface that descends radially outward from the connection line L1 to the tip and connects to the large diameter portion 181a.
The sensor element is not limited to one that measures the concentration of oxygen, and may be one that measures the concentration of nitrogen oxides (NOx) or hydrocarbons (HC).

１ ガスセンサ
１１ 主体金具
２１ センサ素子
７１ リード線
７５ 端子金具
８１、１８１ 外筒
８１ａ、１８１ａ 大径部
８１ｃ、１８１ｃ 小径部
８１ｄ、１８１ｄ 段部
８１ｅ、１８１ｅ 補強リブ
８５ グロメット
９１ セパレータ
Ｏ 軸線
Ｌ１ 接続線 1 gas sensor 11 metal shell 21 sensor element 71 lead wire 75 terminal metal fittings 81, 181 outer cylinders 81a, 181a large diameter portions 81c, 181c small diameter portions 81d, 181d step portions 81e, 181e reinforcing ribs 85 grommets 91 separator O axis line L1 connection line

Claims (3)

軸線方向に延びるセンサ素子と、
前記センサ素子を取り囲んで保持する主体金具と、
前記主体金具の後端側に取り付けられ、前記センサ素子の後端側を収容する金属製で筒状の外筒と、
前記外筒に収容され、前記センサ素子に接続される端子金具を保持するセパレータと、
を備えたガスセンサであって、
前記外筒は、大径部と、前記大径部よりも後端側に配置されストレートに延びる小径部と、前記大径部に接続されると共に前記小径部に接続線にて接続されて径方向に延びる段部と、を有し、
さらに、前記小径部に接続されて前記小径部よりも外側に突出すると共に、前記接続線を跨いで前記段部の一部に接続されて前記段部よりも後端側に突出する複数の凸状の補強リブを有し、
前記セパレータの後端向き面が前記段部の先端向き面に係止され、
前記段部の先端向き面における前記大径部の内径Ｄ１と、前記小径部の内径Ｄ２との比Ｄ２/Ｄ１で表される絞り率が０．７２以下であり、
前記補強リブが周方向に離間して配置されることを特徴とするガスセンサ。 an axially extending sensor element;
a metal shell surrounding and holding the sensor element;
a cylindrical outer cylinder made of metal that is attached to the rear end side of the metal shell and accommodates the rear end side of the sensor element;
a separator that is housed in the outer cylinder and holds a terminal fitting that is connected to the sensor element;
A gas sensor comprising
The outer cylinder includes a large-diameter portion, a small-diameter portion arranged on the rear end side of the large-diameter portion and extending straight, and a connecting wire connected to the large-diameter portion and the small-diameter portion. and a stepped portion extending in the direction of
Further, a plurality of projections connected to the small diameter portion and protruding outside the small diameter portion, straddling the connection line and connected to a part of the step portion and protruding toward the rear end side of the step portion. It has a reinforcing rib shaped like
The rear end facing surface of the separator is engaged with the front end facing surface of the stepped portion,
A drawing ratio represented by a ratio D2/D1 between an inner diameter D1 of the large diameter portion and an inner diameter D2 of the small diameter portion on the tip-facing surface of the stepped portion is 0.72 or less,
A gas sensor, wherein the reinforcing ribs are spaced apart in a circumferential direction. 前記補強リブの外面が前記段部及び前記小径部の外面に沿った形状であることを特徴とする請求項１に記載のガスセンサ。 2. The gas sensor according to claim 1, wherein the outer surface of said reinforcing rib has a shape along the outer surfaces of said step portion and said small diameter portion. 前記外筒の後端側に、前記端子金具に接続されたリード線を挿通する挿通孔を有するグロメットが保持され
前記外筒の最大厚みが０．４ｍｍ以下であることを特徴とする請求項１又は２に記載のガスセンサ。 2. A grommet having an insertion hole through which a lead wire connected to said terminal fitting is inserted is held at the rear end of said outer cylinder, and said outer cylinder has a maximum thickness of 0.4 mm or less. Or the gas sensor according to 2.
JP2021175204A 2021-10-27 2021-10-27 gas sensor Pending JP2023064825A (en)

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