JP2015087383A

JP2015087383A - Gas sensor

Info

Publication number: JP2015087383A
Application number: JP2014187625A
Authority: JP
Inventors: 後藤　常利; Tsunetoshi Goto; 常利後藤
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2013-09-26
Filing date: 2014-09-16
Publication date: 2015-05-07
Anticipated expiration: 2034-09-16
Also published as: JP6379900B2; BR102014023730B1; BR102014023730A2

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor having excellent current-carrying reliability of a heater.SOLUTION: Disclosed is a gas sensor which at least includes: a gas sensor element; a heater; a pair of conductive lines: and a pair of terminal metal fittings 1 which achieves connection between a pair of electrode pads and a pair of conductive lines provided on both sides on opposing flat surfaces of a heater. The terminal metal fitting 1 includes a flat plate like base part 10 extending in the axial direction, a bent part 11, an abutting part 12, and a crimp part 13. The abutting part 12 is formed in a spherical shape curved so as be projected toward the electrode pad side.

Description

本発明は、被測定ガス中の特定ガス成分の濃度を検出するガスセンサに関するものであり、特にガスセンサを早期に活性化するためのヒータと外部との接続を図る端子金具に関する。 The present invention relates to a gas sensor for detecting the concentration of a specific gas component in a gas to be measured, and more particularly to a terminal fitting for connecting a heater and the outside for activating the gas sensor at an early stage.

従来、自動車エンジン等の内燃機関の燃焼排気流路に、燃焼排気中に含まれる酸素等の特定ガス成分の濃度を検出するガスセンサを配設して、検出された特定ガス成分の濃度によって空燃比制御や排気処理触媒の温度制御等を行っている。 2. Description of the Related Art Conventionally, a gas sensor for detecting the concentration of a specific gas component such as oxygen contained in combustion exhaust has been provided in a combustion exhaust flow path 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.

このようなガスセンサとして、ジルコニア等の酸素イオン伝導性固体電解質の基体表面に被測定ガスに接する測定電極層と基準ガスとして導入された大気に接する基準電極層とを施した酸素濃度検出素子を具備し、被測定ガス中の酸素濃度と基準ガス中の酸素濃度との差によって両電極間に発生する電位差を検出して被測定ガス中の酸素濃度を測定する酸素センサや、燃焼排気中の特定ガス成分の濃度から内燃機関に導入される混合気の空燃比を検出する空燃比センサや、水素イオン導電性固体電解質体を用いて被測定ガス中のアンモニア濃度を検出するアンモニアセンサ等が広く用いられている。 As such a gas sensor, an oxygen concentration detection element is provided in which a measurement electrode layer in contact with a gas to be measured and a reference electrode layer in contact with the atmosphere introduced as a reference gas are provided on the surface of an oxygen ion conductive solid electrolyte such as zirconia. An oxygen sensor that detects the potential difference between the two electrodes based on the difference between the oxygen concentration in the gas to be measured and the oxygen concentration in the reference gas to measure the oxygen concentration in the gas to be measured, 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 the gas component, an ammonia sensor that detects the ammonia concentration in the gas to be measured using a hydrogen ion conductive solid electrolyte body, etc. are widely used It has been.

特許文献１には、有底円筒状で内部に基準ガス室を設け、該基準ガス室と対面する内側面に内側電極を、被測定ガスと接する外側面に外側電極を設けたコップ型の固体電解質体よりなると共に上記基準ガス室にはヒータホルダにより保持固定されたヒータが挿入配置されたセンサ素子を有するガスセンサが開示されている。
このようなガスセンサにおいては、従来、ヒータと外部電源との接続を図る通電線との接続は、ヒータの基端側に設けられた一対の電極に、ロウ付け、溶接等により、棒状の端子部材を接続した上で、その端子部材と通電線とを圧着端子を介して接続している（特許文献１図２等参照）。 In Patent Document 1, a cup-shaped solid body having a cylindrical shape with a bottom, a reference gas chamber provided therein, an inner electrode on the inner surface facing the reference gas chamber, and an outer electrode provided on the outer surface in contact with the gas to be measured. A gas sensor having a sensor element made of an electrolyte body and having a heater inserted and arranged in the reference gas chamber by a heater holder is disclosed.
In such a gas sensor, conventionally, the connection between the heater and the energization line for connecting the external power source is made by connecting a pair of electrodes provided on the base end side of the heater by brazing, welding, etc. Then, the terminal member and the conductive wire are connected via a crimp terminal (see Patent Document 1, FIG. 2, etc.).

一方、特許文献２には、平板状に形成したセンサ素子の基端側の両面にそれぞれに、２つの電極パッドを引き出した、いわゆる積層型のガスセンサにおいて、信号線との導通を図るために、電極との接点にセンサ側（電極側）に突出する突起部を設けて、板バネ状の端子金具が開示されている（特許文献２図１０等参照）。 On the other hand, in Patent Document 2, in a so-called stacked gas sensor in which two electrode pads are drawn out on both surfaces of the base end side of a sensor element formed in a flat plate shape, in order to achieve conduction with a signal line, A leaf spring-like terminal fitting is disclosed by providing a protrusion protruding to the sensor side (electrode side) at a contact point with the electrode (see, for example, FIG. 10 of Patent Document 2).

特許文献１にあるような、いわゆる積層型のヒータの電極パッドと通電線との接続をするに当たり、特許分文献２にあるような、接点部に電極パッド側に向かって突出する突起部を弾性的に押しつけて導通を図る端子金具を用いた場合、板状のヒータの両面に形成した電極パッドを一対の端子金具が両側から押圧することになる。 When connecting the electrode pad of the so-called stacked heater as in Patent Document 1 and the conducting wire, the protrusion protruding toward the electrode pad side is elastically formed in the contact portion as in Patent Document 2. When the terminal metal fittings that are pressed and conductive are used, the pair of terminal metal parts press the electrode pads formed on both sides of the plate-shaped heater from both sides.

特開２００１−３０５０９８号公報JP 2001-305098 A 特開２０１３−１８１７６９号公報JP 2013-181769 A

このとき、端子金具の組み付け誤差により、一方の端子金具の突起部がヒータの一方の面側に設けた電極パッドを押圧する位置と、他方の端子金具の突起部が他方の面側に設けた電極パッドを押圧する位置との間で、ヒータの軸方向に対して直交する横断面方向にズレが生じた場合、ヒータの長手軸を中心として回転方向のモーメントが働き、ヒータが大きく傾斜して、電極パッド形成面と端子金具の押圧方向に対する角度が大きくなる。
このため、接点における接点荷重が小さくなり、外部からの振動が負荷された時などにおいて、瞬間的な導通の遮断を招き、ガスセンサの信頼性を低下させるおそれがある。 At this time, due to the assembly error of the terminal fitting, the position where the projection of one terminal fitting presses the electrode pad provided on one side of the heater and the projection of the other terminal fitting is provided on the other side. If a deviation occurs in the cross-sectional direction perpendicular to the axial direction of the heater between the position where the electrode pad is pressed, a moment in the rotational direction acts around the longitudinal axis of the heater, and the heater tilts greatly. The angle with respect to the pressing direction of the electrode pad forming surface and the terminal fitting is increased.
For this reason, the contact load at the contact point becomes small, and when external vibration is applied, for example, there is a possibility that the instantaneous conduction is interrupted and the reliability of the gas sensor is lowered.

そこで、本発明は、かかる実情に鑑み、軸方向に伸びる平板状のヒータと、その対向平面のそれぞれに設けた一対の電極パッドと、一対の電極パッドと一対の通電線とを接続する弾性部材からなる一対の端子金具とを具備するガスセンサにおいて、対向する一対の端子金具に位置ズレが生じても、接点荷重の低下を抑制し、接触抵抗の安定化を図ることのできる信頼性の高いガスセンサを提供することを目的とする。 Therefore, in view of such a situation, the present invention provides a flat heater extending in the axial direction, a pair of electrode pads provided on each of the opposing planes, and an elastic member that connects the pair of electrode pads and the pair of conductive wires. A gas sensor comprising a pair of terminal fittings, and a highly reliable gas sensor that can suppress a decrease in contact load and stabilize contact resistance even if a positional deviation occurs between a pair of opposing terminal fittings. The purpose is to provide.

本発明では、被測定ガス中の特定ガス成分の濃度を検出するガスセンサ（ＧＳ）であって、少なくとも、ガスセンサ素子（４）と、通電により発熱し、前記ガスセンサ素子（４）の活性化を図るべく設けられ、前記ガスセンサ素子（４）の軸方向に伸びる平板状のヒータ（３）と、該ヒータ（３）と外部との接続を図る一対の通電線（２）と、前記ヒータ（３）の基端側において対向する平面の両側に設けた一対の電極パッド（３１）と前記一対の通電線（２）との接続を図るべく設けられ、弾性部材からなる一対の端子金具（１）と、を具備するガスセンサにおいて、前記端子金具（１）が、軸方向に伸びる平板状の基部（１０）と、該基部（１０）を基端側に向かって折り返した屈曲部（１１）と、該屈曲部（１１）の先に設けられ、前記屈曲部（１１）によって付勢され、前記電極パッド（３１）に弾性的に当接する当接部（１２）と、前記基部（１０）の基端側に設けられ、前記導通線（２）の芯線（２０）に接続する圧着部（１３）と、を具備し、前記当接部（１２）を、前記電極パッド（３１）側に向かって凸となるように湾曲する球面状に形成せしめたことを特徴とする。 In the present invention, the gas sensor (GS) detects the concentration of a specific gas component in the gas to be measured, and at least the gas sensor element (4) generates heat when energized to activate the gas sensor element (4). A flat heater (3) provided in the axial direction of the gas sensor element (4), a pair of energizing wires (2) for connecting the heater (3) and the outside, and the heater (3) A pair of terminal fittings (1) made of an elastic member provided to connect the pair of electrode pads (31) provided on both sides of the opposing plane on the base end side of the pair and the pair of conductive wires (2); The terminal fitting (1) includes a flat base portion (10) extending in the axial direction, a bent portion (11) where the base portion (10) is folded back toward the base end, Provided at the tip of the bend (11) A contact portion (12) that is urged by the bent portion (11) and elastically contacts the electrode pad (31), and is provided on the base end side of the base portion (10), and is connected to the conductive wire (2). A crimping portion (13) connected to the core wire (20), and the contact portion (12) is formed in a spherical shape curved so as to be convex toward the electrode pad (31) side. It is characterized by that.

本発明によれば、前記一対の端子金具（１）の組み付け精度によって、横断面方向に位置ズレを生じている場合であっても、前記ヒータ（３）を挟んで対向する一対の当接部（１２）の一方の横断面曲率半径（Ｒ_２）の中心点（Ｏ）と、他方の横断面曲率半径（Ｒ_２）の中心点（Ｏ）とを結ぶ直線上で、常に両当接部（１２）が接し、前記電極パッド（３１）に対して直交する方向の接点荷重（Ｆ）を発生させるため、接点荷重（Ｆ）の低下を抑制することができる。 According to the present invention, the pair of contact portions opposed to each other with the heater (3) interposed therebetween, even when the positional deviation occurs in the cross-sectional direction due to the assembly accuracy of the pair of terminal fittings (1). In the straight line connecting the center point (O) of one of the cross-sectional curvature radii (R ₂ ) of (12) and the center point (O) of the other cross-sectional radius of curvature (R ₂ ), both contact portions are always provided. Since (12) contacts and generates a contact load (F) in a direction perpendicular to the electrode pad (31), a decrease in the contact load (F) can be suppressed.

本発明の第１の実施形態におけるガスセンサの要部である端子金具１の全体概要を示す斜視図The perspective view which shows the whole terminal metal fitting 1 outline | summary which is the principal part of the gas sensor in the 1st Embodiment of this invention. 図１Ａの端子金具１に導通線２を接続した状態における縦断面図1 is a longitudinal sectional view of the terminal fitting 1 of FIG. 一対の端子金具１をヒータ３に取り付けた状態における図１Ｂ中Ｂ−Ｂに沿った横断面図A cross-sectional view along the line BB in FIG. 1B in a state in which the pair of terminal fittings 1 is attached to the heater 3. 比較例として、当接部１２Ｚに突起部Ｐｃを設けた従来の端子金具１Ｚの概要を示す斜視図As a comparative example, a perspective view showing an outline of a conventional terminal fitting 1Z in which a protrusion Pc is provided on the contact portion 12Z. 本発明の接点荷重低減抑制効果を示す横断面図Cross section showing the contact load reduction suppression effect of the present invention 比較例の接点荷重低下の問題点を示す横断面図Cross-sectional view showing the problem of contact load reduction in the comparative example 本発明の効果を発揮する横断面曲率半径Ｒ_２と変位量δとの関係を示す特性図Characteristic diagram showing the relationship between the cross-sectional radius of curvature R ₂ to exhibit the effect of the present invention the amount of displacement δ 任意のヒータ３の厚みＴ_３に対して本発明の効果を発揮し得る横断面半径Ｒ_２の範囲を示す特性図Characteristic diagram showing the cross section radial extent R ₂ capable of exhibiting the effects of the present invention with respect to the thickness T ₃ of any of the heater 3 本発明の実施形態におけるガスセンサＧＳ全体の概要を示す縦断面図The longitudinal cross-sectional view which shows the outline | summary of the whole gas sensor GS in embodiment of this invention 本発明の要部である端子金具の変形例１ａを示す斜視図The perspective view which shows the modification 1a of the terminal metal fitting which is the principal part of this invention

本発明は、被測定ガス中の特定ガス成分の濃度を検出するガスセンサＧＳに係るもので、ガスセンサＧＳを早期に活性化するために用いられるヒータ３と導通線２との接続を図る端子金具１の当接部１２を対向するヒータ３の表面に設けた電極パッド３１に向かって凸となるように湾曲する球面状に形成したことを最大の特徴とするものである。
なお、本発明において、検出対象を特に限定するものではなく、本発明の要部である端子金具１の当接部１２を所定の形状とすることで、接点の導通信頼性の向上を図る本発明の趣旨に反しない限りにおいて、ガスセンサ素子の構成を適宜変更することができる。 The present invention relates to a gas sensor GS for detecting the concentration of a specific gas component in a gas to be measured, and a terminal fitting 1 for connecting a heater 3 and a conducting wire 2 used to activate the gas sensor GS at an early stage. The contact portion 12 is formed in a spherical shape that curves so as to protrude toward the electrode pad 31 provided on the surface of the opposing heater 3.
In the present invention, the detection target is not particularly limited, and the contact portion 12 of the terminal fitting 1 which is a main part of the present invention is formed in a predetermined shape, thereby improving the contact reliability of the contact. As long as not departing from the spirit of the invention, the configuration of the gas sensor element can be changed as appropriate.

図１Ａ、図１Ｂ、図１Ｃを参照して、端子金具１について説明する。
端子金具１は、電気伝導性に優れ、弾性を有する金属材料が用いられている。
端子金具１は、基部１０、屈曲部１１、当接部１２、圧着部１３、及び、撓み部１４によって構成されている。 The terminal fitting 1 will be described with reference to FIGS. 1A, 1B, and 1C.
The terminal fitting 1 is made of a metal material having excellent electrical conductivity and elasticity.
The terminal fitting 1 includes a base portion 10, a bent portion 11, a contact portion 12, a crimping portion 13, and a bent portion 14.

基部１０は、軸方向に伸びる平板状に形成されている。
屈曲部１１は、基部１０の先端側を基端側に向かって折り返して形成されている。
屈曲部１１は、その先端側に設けた当接部１２をヒータ３の表面に設けた電極パッド３１側に向かって付勢する。
当接部１２は、ヒータ３の表面に形成した電極パッド３１に弾性的に当接する。
圧着部１３は、基部１０の基端側に設けられ、導通線２の芯線２０に接続され、圧着固定される。
撓み部１４は、圧着部１３と基部１０との間に設けられ、ガスセンサＧＳ内に収容した時に、適度に湾曲して端子金具１を保持する位置と導通線２を保持する位置との位置ズレを緩衝する。 The base 10 is formed in a flat plate shape extending in the axial direction.
The bent portion 11 is formed by folding the distal end side of the base portion 10 toward the proximal end side.
The bent portion 11 urges the contact portion 12 provided on the distal end side thereof toward the electrode pad 31 provided on the surface of the heater 3.
The contact portion 12 elastically contacts the electrode pad 31 formed on the surface of the heater 3.
The crimping part 13 is provided on the proximal end side of the base part 10, connected to the core wire 20 of the conducting wire 2, and fixed by crimping.
The bending portion 14 is provided between the crimping portion 13 and the base portion 10, and when housed in the gas sensor GS, the bending portion 14 is appropriately curved and is displaced from a position where the terminal fitting 1 is held and a position where the conducting wire 2 is held. Buffer.

本発明に係る一対の端子金具１をヒータ３に組み付けたときに、図１Ｃに示すように、ヒータ３を挟んで、端子金具１の当接部１２がヒータ３の両側から電極パッド３１を弾性的に押圧して端子金具１と電極パッド３１との導通が図られる。
接点荷重Ｆは、それぞれの当接部１２の横断面曲率半径Ｒ_２の中心Ｏを結ぶ直線上で当接部１２の法線方向に作用し、一対の端子金具１がヒータ３の中心位置に組み付けられた場合に最大となる。 When the pair of terminal fittings 1 according to the present invention is assembled to the heater 3, the contact portion 12 of the terminal fitting 1 elastically holds the electrode pad 31 from both sides of the heater 3 with the heater 3 interposed therebetween, as shown in FIG. Thus, the terminal metal 1 and the electrode pad 31 are electrically connected.
The contact load F acts in the normal direction of the contact portion 12 on a straight line connecting the centers O of the cross-sectional curvature radii R ₂ of the respective contact portions 12, and the pair of terminal fittings 1 are located at the center position of the heater 3. Maximum when assembled.

さらに、当接部１２において、ヒータ３の長手軸方向に沿った縦断面曲率半径Ｒ_１と長手軸方向に直交する横断面曲率半径Ｒ_２との関係において、式１の関係を満たすように設定されている。
Ｒ_２＞Ｒ_１・・・式１ Further, it sets in the abutment section 12, as in relation to the cross-sectional radius of curvature R ₂ which is perpendicular to the longitudinal section radius of curvature R ₁ and a longitudinal axis direction along the longitudinal axis of the heater 3, satisfy the relationship of Formula 1 Has been.
R ₂ > R ₁ Formula 1

さらに、端子金具１の基部１０の表面から当接部１２までの自由高さＨ_１と、ヒータ３の電極パッド３１に当接したときの当接時高さＨ_２との差ΔＨ（＝Ｈ_１−Ｈ_２）を、ヒータ電極部板厚Ｔ_３を基準とした相対変位量δ（＝ΔＨ／Ｔ_３）で表し、横断面曲率半径Ｒ_２をヒータ電極部板厚Ｔ_３を基準とした相対半径ｒ_２（＝Ｒ_２／Ｔ_３）で表したとき、相対変位量δと相対半径ｒ_２との間に式２の関係が成り立つように設定することが望ましいことが判明した。

Further, the difference ΔH (= H) between the free height H ₁ from the surface of the base 10 of the terminal fitting 1 to the contact portion 12 and the contact height H ₂ when contacting the electrode pad 31 of the heater 3. the ₁ -H _2), expressed as a relative displacement amount relative to the heater electrode portion thickness _{_{T 3 δ (= ΔH / T}} 3), and the cross-sectional radius of curvature _{R 2} with respect to the heater electrode portion thickness _{T 3} It has been found that it is desirable to set the relationship of Equation 2 between the relative displacement δ and the relative radius r ₂ when expressed by the relative radius r ₂ (= R ₂ / T ₃ ).

さらに、ヒータ３の一方の表面に形成した電極パッド３１の表面から対向する他方の表面に形成した前記電極パッド３１の表面に至る長さをヒータ電極部板厚Ｔ_３としたとき、ヒータ電極部板厚Ｔ_３と横断面曲率半径Ｒ_２との間に式３の関係が成り立つように形成することにより、電極パッド３１に対する当接部１２の接点荷重Ｆを１０％以上低下させないことが判明した。
Ｒ_２≧２×Ｔ_３・・・式３ Further, when the heater electrode portion thickness T ₃ the length leading to the surface of the electrode pad 31 formed on the other surface opposite from the surface of one electrode pad 31 formed on the surface of the heater 3, the heater electrode portion by forming such relationship of equation 3 is established between the thickness T ₃ and the transverse surface radius of curvature R _2, and the contact load F of the contact portion 12 with respect to the electrode pads 31 proved not to lower than 10% .
R ₂ ≧ 2 × T ₃ Formula 3

より具体的には、ヒータ電極部板厚Ｔ_３が、０．８ｍｍ以上、１．６ｍｍ以下であり、横断面曲率半径Ｒ_２が３．０ｍｍ以上、８．０ｍｍ以下に設定されている。 More specifically, the heater electrode portion thickness _{T 3,} 0.8 mm or more and 1.6mm or less, cross-sectional radius of curvature _{R 2} is 3.0mm or more, is set to be below 8.0 mm.

ここで、図２を参照して比較例として示す、従来型の端子金具１Ｚについて説明する。
なお、端子金具１Ｚと本発明に係る端子金具１との共通する部分については、同じ符号を付し、相違する部分にＺの枝番を付したので、同一の部分についての説明を省略し、相違する点を中心に説明する。
比較例においては、本発明のような比較的緩やかなカーブを描いて湾曲する球面ではなく、当接部１２Ｚの中心に電極パッド側に向かって突出する突起部Ｐ_Ｃが形成されており、突起部Ｐｃの曲率半径Ｒ_Ｚは、本発明の端子金具１の当接部１２の縦断面曲率半径Ｒ_１、及び、横断面曲率半径Ｒ_２のいずれよりも遙かに小さく（例えば、Ｒ_Ｚ＝０．３〜０．７ｍｍ）設定されている。 Here, a conventional terminal fitting 1Z shown as a comparative example with reference to FIG. 2 will be described.
In addition, about the common part of the terminal metal fitting 1Z and the terminal metal fitting 1 which concerns on this invention, since the same code | symbol was attached | subjected and the branch number of Z was attached | subjected to the different part, description about the same part is abbreviate | omitted, The difference will be mainly described.
In the comparative example, rather than a spherical curved drawing a relatively gentle curve, such as in the present invention, are projections P _C that protrudes toward the electrode pad side formed in the center of the contact portion 12Z, projection the radius of curvature R _Z parts Pc is a longitudinal sectional radius of curvature R ₁ of the contact portion 12 of the terminal fitting 1 of the present _invention, and, much smaller than any transverse section a radius of curvature R ₂ (e.g., R _Z = 0.3 to 0.7 mm).

ここで、図３、図４を参照して、本発明の効果と比較例における問題点について説明する。
図３に示すように、一対の端子金具１を組み付けたときに、一方の端子金具１の中心点Ｏと、他方の端子金具１の中心点Ｏとが、横断面方向にＸ（ｍｍ）の位置ズレが生じた場合であっても、ヒータ３が傾き角度θだけ回転し、ヒータ３を挟んで対向する一対の当接部１２の一方の横断面曲率半径Ｒ_２の中心点Ｏと、他方の横断面曲率半径Ｒ_２の中心点Ｏとを結ぶ直線上で、常に両当接部１２が接し、電極パッド３１に対して直交する方向の接点荷重Ｆを発生させるため、接点荷重Ｆの低下を抑制することができる。
このとき、一対の端子金具１の中心点Ｏがヒータ３の中心位置と一致する正位置の場合に比べ、位置ズレが生じた場合の当接部１２の当接時高さＨ_２が僅かに高くなるため、変位量ΔＨが僅かに小さくなり、接点荷重Ｆ（バネ常数Ｋ×変位量ΔＨに相当）も小さくなる。
しかし、本発明の範囲に横断面方向曲率半径Ｒ_２を設定することで、横断面方向にヒータ電極部板厚Ｔ_３の１．５倍の位置ズレ量Ｘ（ｍｍ）を生じても、接点荷重Ｆの低下を１０％以内に抑制できることが判明した。 Here, with reference to FIG. 3 and FIG. 4, the effect of this invention and the problem in a comparative example are demonstrated.
As shown in FIG. 3, when the pair of terminal fittings 1 are assembled, the center point O of one terminal fitting 1 and the center point O of the other terminal fitting 1 are X (mm) in the cross-sectional direction. even if the positional deviation occurs, then rotated by an angle θ tilt heater 3, and the center point O one cross-sectional radius of curvature R ₂ of the pair of contact portions 12 which face each other across the heater 3 and the other Since both contact portions 12 are always in contact with each other on the straight line connecting the center point O of the cross-sectional curvature radius R ₂ , the contact load F in the direction orthogonal to the electrode pad 31 is generated, so that the contact load F is reduced. Can be suppressed.
In this case, compared with the normal position of the center point O of the pair of terminal fittings 1 coincides with the center position of the heater 3, slightly abutment at the height of H ₂ abutting portion 12 when misalignment occurs Therefore, the displacement amount ΔH is slightly decreased, and the contact load F (equivalent to the spring constant K × displacement amount ΔH) is also decreased.
However, by setting the cross-sectional direction radius of curvature R ₂ within the scope of the present invention, even if a positional deviation amount X (mm) 1.5 times the heater electrode plate thickness T ₃ occurs in the cross-sectional direction, the contact point It has been found that the decrease in the load F can be suppressed within 10%.

一方、図４に示す比較例では、一対の端子金具１Ｚに同じ量の位置ズレを生じた場合、突起部Ｐ_Ｃの曲率半径Ｒ_Ｚが小さいため、両突起部Ｐ_Ｃの中心点Ｏ_Ｚを結ぶ直線と接点荷重Ｆの作用する方向とが一致するまでの回転角度θ_Ｚが大きくなる。
このため、端子金具１Ｚの幅によっては、接点荷重Ｆ作用方向と中心点Ｏ_Ｚを結ぶ直線とが一致する前に、ヒータ３と端子金具１Ｚの側面とが当接して、ヒータ３の回転が止まるので、接点荷重Ｆが低下する。
しかも、互いに対向する端子金具１Ｚの接点荷重Ｆが中心点Ｏ_Ｚを結ぶ直線上から外れるため、ヒータ３をひねるような回転モーメントが発生する。
その結果、従来のガスセンサにおいては、使用時に、ヒータ３の内部に残留する応力と冷熱ストレスが重畳的に作用し、ヒータ割れを起こし易くなることが判明した。 On the other hand, in the comparative example shown in FIG. 4, when misaligned with the same amount of the pair of terminal fittings 1Z, since the radius of curvature R _Z of the projections P _C is small, the center point O _Z of both projections P _C rotation angle theta _Z to the direction of action of the straight line and the contact load F coincides connecting increases.
Therefore, depending on the width of the terminal fitting 1Z, before the line connecting the contact point load F acting direction and the center point O _Z coincide, the side surface of the heater 3 and the terminal fitting 1Z abuts, the rotation of the heater 3 Since it stops, the contact load F falls.
Moreover, the contact load F of the terminal fitting 1Z facing each other for deviates from a straight line connecting the center point O _Z, rotation moment that twisting the heater 3 is generated.
As a result, it has been found that in the conventional gas sensor, the stress remaining in the heater 3 and the thermal stress act in a superimposed manner during use, and the heater is likely to crack.

ここで、図５Ａ、図５Ｂを参照して、本発明のガスセンサの要部である端子金具１の当接部１２の相対半径ｒ_２と相対変位量δ及びヒータ電極部板厚Ｔ_３と、接点荷重Ｆとの関係について調査した結果について説明する。
図５Ａは、横断面方向曲率半径Ｒ_２と変位量ΔＨを変化させ、接点荷重Ｆが１０％以上低下しない範囲を効果ありと判断し、限界領域を求めたものである。その結果、式２の関係を満たす範囲で効果があるものと確認された。

Here, with reference to FIG. 5A and FIG. 5B, the relative radius r ₂ and the relative displacement δ of the contact portion 12 of the terminal fitting 1 which is the main part of the gas sensor of the present invention, and the heater electrode portion plate thickness T ₃ , The result of investigating the relationship with the contact load F will be described.
Figure 5A is a cross-sectional direction of curvature radius R ₂ to change the displacement amount [Delta] H, determines that there is effective range does not decrease the contact force F is 10% or more, in which to determine the limit region. As a result, it was confirmed that there was an effect in the range satisfying the relationship of Formula 2.

さらに、図５Ｂに示すように、式１、式３の関係を満たし、ヒータ電極部板厚Ｔ_３が０．８ｍｍ以上、１．６ｍｍ以下で、横断面方向半径Ｒ_２が、３．０ｍｍ以上、８．０ｍｍ以下の時、本発明の効果が発揮されることが判明した。
Ｒ_２＞Ｒ_１・・・式１
当接部１２の縦断面曲率半径Ｒ_１を横断面曲率半径Ｒ_２よりも小さくすることで、当接部１２の変位量ΔＨに違いがあっても、素子に接する点までのばねの腕の長さがほぼ一定となり、接点位置の変化が小さくなるので、接点荷重Ｆの安定化を図ることができる。
なお、後述するように、図６に示す、ヒータ把持部７３によってヒータ３の中腹が保持されているので、ヒータ３の直線性が確保され、軸方向の接点ズレは無視できる。
Ｒ_２≧２×Ｔ_３・・・式３ Furthermore, as shown in Figure 5B, wherein 1, satisfy the relationship of Equation 3, the heater electrode portion thickness _{T 3} is 0.8mm or more, at 1.6mm or less, cross-sectional direction the radius _{R 2} is, 3.0 mm or more It was found that the effect of the present invention is exhibited when the thickness is 8.0 mm or less.
R ₂ > R ₁ Formula 1
By making the longitudinal section curvature radius R ₁ of the contact portion 12 smaller than the transverse section curvature radius R ₂ , even if there is a difference in the displacement amount ΔH of the contact portion 12, the spring arm up to the point of contact with the element Since the length is substantially constant and the change in the contact position is small, the contact load F can be stabilized.
As will be described later, since the middle of the heater 3 is held by the heater gripping portion 73 shown in FIG. 6, the linearity of the heater 3 is ensured and the contact displacement in the axial direction can be ignored.
R ₂ ≧ 2 × T ₃ Formula 3

図６を参照して本発明の実施形態におけるガスセンサＧＳの一例について説明する。
なお、本発明のガスセンサＧＳは特に用途を限定するものではなく、ガスセンサ素子４の構成を適宜変更することで、様々な用途に適用することができる。例えば、電極形状や制御方法を工夫することにより、空燃比の検出やＮＯｘの検出を行ったり、固体電解質材料としてプロトン伝導性を有するものを用いて、アンモニア検出等を行うガスセンサに採用することもできる。
なお、以下の実施形態においては、このようなガスセンサとして典型的な酸素センサを例として説明する。
ガスセンサＧＳは、被測定ガス中の特定ガス成分の濃度を検出するものである。ガスセンサＧＳは、少なくとも、ガスセンサ素子４と、ヒータ３と、端子金具１と導通線２とを具備し、それ以外に一般的にガスセンサに用いられる構成を含むものである。 An example of the gas sensor GS in the embodiment of the present invention will be described with reference to FIG.
The gas sensor GS of the present invention is not particularly limited in application, and can be applied to various applications by appropriately changing the configuration of the gas sensor element 4. For example, by devising the electrode shape and control method, the air-fuel ratio can be detected, NOx can be detected, or a solid electrolyte material having proton conductivity can be used for a gas sensor that performs ammonia detection or the like. it can.
In the following embodiments, a typical oxygen sensor will be described as an example of such a gas sensor.
The gas sensor GS detects the concentration of a specific gas component in the gas to be measured. The gas sensor GS includes at least the gas sensor element 4, the heater 3, the terminal fitting 1, and the conductive wire 2, and includes a configuration generally used for a gas sensor.

導通線２は、外部に設けた図略の電源に接続され、絶縁被覆で覆われた芯線２０が、端子金具１の圧着部１３にかしめ固定されている。
端子金具１は、上述の如く、導電性と弾性と有する弾性部材からなり、基部１０、屈曲部１１、当接部１２、圧着部１３、撓み部１４によって構成され、当接部１２は、電極パッド３１に向かって凸となるように湾曲する球面状に形成されている。 The conducting wire 2 is connected to a power supply (not shown) provided outside, and the core wire 20 covered with an insulating coating is caulked and fixed to the crimping portion 13 of the terminal fitting 1.
As described above, the terminal fitting 1 is made of an elastic member having conductivity and elasticity, and includes a base portion 10, a bending portion 11, a contact portion 12, a crimping portion 13, and a bending portion 14, and the contact portion 12 is an electrode. It is formed in a spherical shape that curves so as to be convex toward the pad 31.

ヒータ３は、いわゆる積層型のヒータで、内部に通電により発熱する発熱体３２が埋設され、アルミナ等の公知の絶縁材料からなり平板状に形成された絶縁体３０で覆われ、絶縁体３０の基端側の対向する平面に、発熱体３２に導通する一対の電極パッド３１が形成されている。
ガスセンサ素子４は、いわゆるコップ型のセンサ素子で、酸素イオンに対して伝導性を有するジルコニア等の固体電解質材料を有底筒状に形成し、信号取出部４０、拡径部４１、検出部４２基準ガス室４３によって構成されている。 The heater 3 is a so-called laminated heater, and a heating element 32 that generates heat when energized is embedded therein, and is covered with an insulator 30 made of a known insulating material such as alumina and formed in a flat plate shape. A pair of electrode pads 31 that are electrically connected to the heating element 32 are formed on opposing planes on the base end side.
The gas sensor element 4 is a so-called cup-type sensor element, in which a solid electrolyte material such as zirconia having conductivity with respect to oxygen ions is formed in a bottomed cylindrical shape, and a signal extraction unit 40, a diameter expansion unit 41, and a detection unit 42. A reference gas chamber 43 is used.

検出部４２は、固体電解質層４２０と、その内周面に形成され、基準ガス室４３内に基準ガスとして導入される大気に接する基準電極層４２１と、外周面に形成され、被測定ガスに接する測定電極層４２２とによって構成されている。
基準電極層４２１は、ガスセンサ素子１の基端側で、プラス端子金具７２＋に接続され、プラス端子金具７２＋の基端側に設けた圧着部７１＋を介してプラス信号線７０＋に接続されている。
プラス端子金具７２＋の先端側には、ヒータ把持部７３が設けられ、ヒータ３をガスセンサ素子４内で保持している。 The detection unit 42 is formed on the solid electrolyte layer 420 and the inner peripheral surface thereof, is formed on the outer peripheral surface of the reference electrode layer 421 that is in contact with the atmosphere introduced into the reference gas chamber 43 as a reference gas, and is used as a gas to be measured. The measurement electrode layer 422 is in contact therewith.
The reference electrode layer 421 is connected to the plus terminal fitting 72+ on the base end side of the gas sensor element 1, and is connected to the plus signal line 70+ via a crimping portion 71+ provided on the base end side of the plus terminal fitting 72+.
A heater gripping portion 73 is provided on the front end side of the plus terminal fitting 72+, and the heater 3 is held in the gas sensor element 4.

測定電極層４２２は、ガスセンサ素子４の基端側で、マイナス端子金具７２−に接続され、さらにマイナス端子金具７２−の基端側に設けた圧着部７１−を介して、マイナス信号線７０−に接続されている。
一対の端子金具１、プラス端子金具７２＋、マイナス端子金具７２−は、アルミナ等の公知の絶縁材料で形成された絶縁体８０によって、それぞれ絶縁分離されている。 The measurement electrode layer 422 is connected to the minus terminal fitting 72- on the base end side of the gas sensor element 4, and further through the crimping portion 71- provided on the base end side of the minus terminal fitting 72-. It is connected to the.
The pair of terminal fittings 1, the plus terminal fitting 72+, and the minus terminal fitting 72- are each insulated and separated by an insulator 80 formed of a known insulating material such as alumina.

ガスセンサ素子４は、ステンレス、鉄、ニッケル等、公知の金属材料を用いて筒状に形成したハウジング５の内側に収容され、拡径部４１が、ハウジング５の内側に設けた係止部５１に係止されている。
拡径部４１を覆うように、ハウジング５の内周面とガスセンサ素子４の外周面との間に、タルク粉末等からなる粉末充填部６０、筒状絶縁体６１、金属シール６２からなる封止部材６が配設され、加締め部５３によって封止部材６を軸方向に押圧して、ハウジング５とガスセンサ素子４との間の気密性が確保されている。 The gas sensor element 4 is accommodated inside a housing 5 that is formed in a cylindrical shape using a known metal material such as stainless steel, iron, nickel, etc., and a diameter-expanded portion 41 is provided in a locking portion 51 provided inside the housing 5. It is locked.
Sealing composed of a powder filling portion 60 made of talc powder, a cylindrical insulator 61, and a metal seal 62 between the inner peripheral surface of the housing 5 and the outer peripheral surface of the gas sensor element 4 so as to cover the enlarged diameter portion 41. The member 6 is disposed, and the sealing member 6 is pressed in the axial direction by the caulking portion 53 to ensure the airtightness between the housing 5 and the gas sensor element 4.

ハウジング５の先端側には、ガスセンサ素子４の検出部４２が露出しており、検出部４２は、ハウジング５の先端に固定したカバー体９０によって覆われている。
カバー体９０には、被測定ガスを導入するための開孔９１が設けられている。
なお、本発明において、カバー体９０の構成を限定するものではなく、複数のカバー体を同心に配設したものでも良いし、開孔９１の位置、大きさ、形状等も適宜変更し得る。 The detection part 42 of the gas sensor element 4 is exposed at the front end side of the housing 5, and the detection part 42 is covered with a cover body 90 fixed to the front end of the housing 5.
The cover body 90 is provided with an opening 91 for introducing a gas to be measured.
In the present invention, the configuration of the cover body 90 is not limited, and a plurality of cover bodies may be arranged concentrically, and the position, size, shape, and the like of the opening 91 can be appropriately changed.

ハウジング５の先端側外周には、被測定ガス流路に固定するためのネジ部５４が形成され、基端側外周にはネジ部５４をネジ締めする六角部５５が形成され、さらに基端側にはボス部５２が形成されている。
ボス部には、段付き筒状のケーシング８６が固定されている。
ケーシング８６は、ステンレス等の金属製で、ヒータ３及びガスセンサ素子４の基端側を覆い、一対の端子金具１、プラス端子金具７２＋、マイナス端子金具７２−、絶縁体８０、一対の信号線７０＋／７０−、一対の導通線２を、封止固定する。 A screw portion 54 for fixing to the gas flow path to be measured is formed on the outer periphery on the front end side of the housing 5, and a hexagonal portion 55 for tightening the screw portion 54 is formed on the outer periphery on the base end side. A boss portion 52 is formed on the surface.
A stepped cylindrical casing 86 is fixed to the boss portion.
The casing 86 is made of a metal such as stainless steel and covers the base end side of the heater 3 and the gas sensor element 4, and includes a pair of terminal fittings 1, a plus terminal fitting 72+, a minus terminal fitting 72-, an insulator 80, and a pair of signal wires 70+. / 70-, the pair of conductive wires 2 are sealed and fixed.

絶縁体８０は、筒状のケーシング８６内に収容され、保持手段８１によって弾性的に保持されている。
ケーシング８６の基端側には、耐熱ゴム等からなるグロメット８２、撥水フィルタ８３、通気孔８５が設けられ、加締め部８４によってかしめ固定され、センサ内部への水分の侵入は阻止され、大気の導入のみが許容されている。 The insulator 80 is accommodated in a cylindrical casing 86 and is elastically held by holding means 81.
A grommet 82 made of heat-resistant rubber or the like, a water repellent filter 83, and a vent hole 85 are provided on the base end side of the casing 86, and are caulked and fixed by a caulking portion 84 to prevent moisture from entering the sensor. Only the introduction of is allowed.

本発明のガスセンサＧＳでは、ガスセンサ素子４を加熱活性化するヒータ３と一対の導通線２との導通を図る端子金具１が、電極パッド３１に接触する当接部が所定の球面状に形成され、接点荷重Ｆの安定化が図られているので、瞬断等の不具合を抑制し、安定した検出を行うことができる。 In the gas sensor GS of the present invention, the terminal fitting 1 for conducting the heater 3 that heats and activates the gas sensor element 4 and the pair of conducting wires 2 has a contact portion that contacts the electrode pad 31 in a predetermined spherical shape. Since the contact load F is stabilized, problems such as momentary interruption can be suppressed and stable detection can be performed.

図７を参照して、本発明の要部である端子金具の変形例１Ａについて説明する。
図１に示した端子金具と基本的な構成は同一であり、本変形例では、基部１０Ａの両側に舌片状に張り出す係止部１５を設けた点が相違する。
係止部１５を設けることで、絶縁体８０への固定が容易となり、端子金具１Ａの横断面方向の位置ズレを抑制し、接点荷重Ｆの低下を抑制する本発明の効果をより一相高めることができる。
係止部１５は、本図に示すような形状に限るものではなく、端子金具１Ａを固定する絶縁体８０の形状に応じて適宜変更することができる。
本実施形態においても、当接部１２の横断面曲率半径Ｒ_２と縦断面曲率半径Ｒ_１とを上述と同様の範囲に形成することで、ヒータ３との導通信頼性の向上を図ることができる。 With reference to FIG. 7, the modification 1A of the terminal metal fitting which is the principal part of this invention is demonstrated.
The basic configuration is the same as that of the terminal fitting shown in FIG. 1, and the present modification is different in that a locking portion 15 is provided on both sides of the base portion 10A so as to project in a tongue shape.
By providing the locking portion 15, the fixing to the insulator 80 is facilitated, the positional displacement of the terminal fitting 1 </ b> A in the cross-sectional direction is suppressed, and the effect of the present invention that suppresses the decrease in the contact load F is further enhanced. be able to.
The locking portion 15 is not limited to the shape as shown in the figure, and can be appropriately changed according to the shape of the insulator 80 that fixes the terminal fitting 1A.
Also in this embodiment, the conduction reliability with the heater 3 can be improved by forming the cross-sectional curvature radius R ₂ and the longitudinal cross-section curvature radius R _{1 of the} contact portion 12 in the same ranges as described above. it can.

１端子金具
１０基部
１１屈曲部
１２当接部
１３圧着部
１４撓み部
１５係止部 DESCRIPTION OF SYMBOLS 1 Terminal metal fitting 10 Base part 11 Bending part 12 Contact part 13 Crimping part 14 Deflection part 15 Locking part

Claims

A gas sensor (GS) for detecting the concentration of a specific gas component in a gas to be measured,
at least,
A gas sensor element (4);
A plate-like heater (3) that generates heat when energized and is provided to activate the gas sensor element (4) and extends in the axial direction of the gas sensor element (4);
A pair of energization wires (2) for connecting the heater (3) to the outside;
A pair of terminals made of an elastic member provided to connect the pair of electrode pads (31) provided on both sides of the opposing plane on the base end side of the heater (3) and the pair of energization wires (2). Metal fitting (1),
In a gas sensor comprising:
The terminal fitting (1) is a flat base (10) extending in the axial direction;
A bent portion (11) obtained by folding the base portion (10) toward the base end side;
An abutting portion (12) provided at the tip of the bent portion (11), urged by the bent portion (11), and elastically abutted on the electrode pad (31);
A crimping portion (13) provided on the base end side of the base portion (10) and connected to the core wire (20) of the conductive wire (2),
The gas sensor is characterized in that the contact portion (12) is formed in a spherical shape that is curved so as to be convex toward the electrode pad (31) side.

The contact portion (12)
In the relationship between the longitudinal section curvature radius (R ₁ ) along the longitudinal axis direction of the heater (3) and the transverse section curvature radius (R ₂ ) perpendicular to the longitudinal axis direction,
The gas sensor R ₂ > R _{1 according} to claim 1 that satisfies the relationship of Equation 1 Equation 1

The length from the surface of the electrode pad (31) formed on one surface of the heater (3) to the surface of the electrode pad (31) formed on the opposite surface is defined as the heater electrode portion plate thickness (T ₃ )
When the free height (H ₁ ) from the surface of the base (10) to the contact portion (12) of the terminal fitting (1) and the electrode pad (31) of the heater (1) are contacted The difference ΔH (= H ₁ −H ₂ ) from the contact height (H ₂ ) is expressed by a relative displacement amount δ (= ΔH / T ₃ ) based on the heater electrode plate thickness T ₃ .
When the radius of curvature of the cross section (R ₂ ) is expressed by a relative radius r ₂ (= R ₂ / T ₃ ) based on the heater electrode plate thickness T ₃ ,
In the relationship between the relative displacement (δ) and the relative radius (r ₂ ),
The gas sensor according to claim 2, satisfying the relationship of Formula 2.

In the relationship between the heater electrode portion plate thickness (T ₃ ) and the cross-sectional radius of curvature (R ₂ ),
The gas sensor R ₂ ≧ 2 × T _{3 (} Equation 3) according to claim 3 satisfying the relationship of Equation 3.

5. The heater electrode portion plate thickness (T ₃ ) is 0.8 mm or more and 1.6 mm or less, and the transverse section curvature radius (R ₂ ) is 3.0 mm or more and 8.0 mm or less. Gas sensor described in