JP2006343297A - Lamination-type gas sensor element and gas sensor - Google Patents

Lamination-type gas sensor element and gas sensor Download PDF

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JP2006343297A
JP2006343297A JP2005171754A JP2005171754A JP2006343297A JP 2006343297 A JP2006343297 A JP 2006343297A JP 2005171754 A JP2005171754 A JP 2005171754A JP 2005171754 A JP2005171754 A JP 2005171754A JP 2006343297 A JP2006343297 A JP 2006343297A
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gas sensor
sensor element
porous layer
tip
element body
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JP4570091B2 (en
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Shinya Awano
真也 粟野
Keisuke Makino
圭祐 牧野
Yoshiaki Kuroki
義昭 黒木
Masafumi Ando
雅史 安藤
Takao Kojima
孝夫 小島
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Niterra Co Ltd
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NGK Spark Plug Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a lamination-type gas sensor element and a gas sensor equipped with the gas sensor element capable of urging the detection part with early activation, the defects of which are less likely to take place by becoming wet. <P>SOLUTION: The lamination-type gas sensor 20 comprises the ceramic heater 12, including ceramic bases 122 and 123, in which heating resistors are embedded and the plate-like element main body including the solid-state electrolyte layer 111 overlying this ceramic heater 12 and provided with a pair of electrodes at the tip, extending in the longitudinal direction. The width size of the tip part 101 including the detection part is formed smaller than the remaining parts 103 and 105. Both the side surfaces along the lamination direction of the tip part 101 and the tip surface are coated with porus protective layers 13. Thereby, the heat generated by the ceramic heater 12 can be transmitted quickly, and the direct adhesion of water drops to the element main body can be inhibited. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、積層型ガスセンサ素子及びガスセンサに関する。更に詳しくは、水滴等の付着による素子本体の損傷を防止することができ、且つセラミックヒータの加熱による検出部の早期活性を実現可能な積層型ガスセンサ素子、及びこの積層型ガスセンサ素子を備えるガスセンサに関する。   The present invention relates to a stacked gas sensor element and a gas sensor. More specifically, the present invention relates to a multilayer gas sensor element that can prevent damage to an element body due to adhesion of water droplets and the like, and can realize early activation of a detection unit by heating of a ceramic heater, and a gas sensor including the multilayer gas sensor element. .

内燃機関から排出される排気ガス中の酸素、一酸化炭素、各種の炭化水素、酸化窒素(NOx)等の検出あるいはその濃度測定が可能なガスセンサの一種として、積層型ガスセンサ素子を備えるガスセンサが知られている。このガスセンサの1種である酸素センサ向けの積層型ガスセンサ素子(積層型酸素センサ素子)は、セラミック基体の内部に発熱抵抗体を埋設したセラミックヒータと、先端側に一対の電極を設けた固体電解質層とを積層してなる素子本体を有している。なお、固体電解質層のうち、一対の電極にて挟まれている部分が酸素濃淡電池と機能し、この部分が酸素濃度を検出するための検出部となる。このような積層型酸素センサ素子は、固体電解質層が所定の温度に達しないと活性化しないため、内燃機関の始動時から発熱抵抗体に通電して固体電解質層(検出部)を加熱させ、早期の酸素濃度検出を促すことが提案されている。   As one type of gas sensor capable of detecting or measuring the concentration of oxygen, carbon monoxide, various hydrocarbons, nitrogen oxide (NOx), etc. in exhaust gas discharged from an internal combustion engine, a gas sensor having a stacked gas sensor element is known. It has been. A laminated gas sensor element (stacked oxygen sensor element) for an oxygen sensor, which is one type of gas sensor, includes a ceramic heater in which a heating resistor is embedded in a ceramic substrate, and a solid electrolyte provided with a pair of electrodes on the tip side. It has an element body formed by laminating layers. Of the solid electrolyte layer, a portion sandwiched between the pair of electrodes functions as an oxygen concentration cell, and this portion serves as a detection unit for detecting the oxygen concentration. Since such a laminated oxygen sensor element is not activated unless the solid electrolyte layer reaches a predetermined temperature, the heating resistor is energized from the start of the internal combustion engine to heat the solid electrolyte layer (detector), It has been proposed to promote early oxygen concentration detection.

ところで、内燃機関の冷間始動時といった排気管内の温度(排気管の壁面の温度)が低い条件下では、通常、排気管壁面に凝縮した水分が付着しているため、発熱抵抗体に通電を行って検出部を高温に加熱すると、凝縮水の付着による熱衝撃(所謂、サーマルショック)に起因して積層型ガスセンサ素子(素子本体)が損傷することがある。そのため、従来から通気孔を有する金属製のプロテクタでガスセンサ素子の検出部を保護している。しかし、このようなプロテクタを使用しても、プロテクタの通気孔を通過して水分が侵入することがあり、素子本体にクラックが発生する等の損傷を十分に抑制できない。また、通気孔を小さくすると、検出部に排気ガスが十分に流通せず、ガス検知性能が低下する傾向にあるため、通気孔を小さくするには限界がある。   By the way, under conditions where the temperature in the exhaust pipe (the temperature of the wall surface of the exhaust pipe) is low, such as when the internal combustion engine is cold-started, usually the condensed moisture adheres to the wall surface of the exhaust pipe. If the detection unit is heated to a high temperature, the stacked gas sensor element (element body) may be damaged due to a thermal shock (so-called thermal shock) due to adhesion of condensed water. Therefore, the detection part of a gas sensor element is conventionally protected with the metal protector which has a vent hole. However, even if such a protector is used, moisture may enter through the vent hole of the protector, and damage such as generation of cracks in the element body cannot be sufficiently suppressed. Further, if the vent hole is made small, exhaust gas does not sufficiently flow through the detection part, and the gas detection performance tends to be lowered. Therefore, there is a limit to reducing the vent hole.

このような問題を解決するため、素子本体のうちで排気ガスに晒される検出部の周囲の損傷を受ける可能性のある部位(具体的には側面)を多孔質層にて被覆し、素子本体に水滴等が直接付着することを抑制した積層タイプのガスセンサ素子が提案されている(例えば、特許文献1参照。)。特許文献1に記載のガスセンサ素子では、多孔質層に水滴等が付着しても、この水滴等が検出部にまで浸透する前にガスセンサ素子の発熱によって蒸発させることができるため、素子本体に大きな熱衝撃が及び難く、素子本体の損傷を抑制することができる。   In order to solve such a problem, the element body (specifically, the side surface) that may be damaged around the detection part exposed to the exhaust gas in the element body is covered with a porous layer, and the element body A laminated type gas sensor element in which water droplets or the like are prevented from directly adhering to the surface has been proposed (see, for example, Patent Document 1). In the gas sensor element described in Patent Document 1, even if water droplets or the like adhere to the porous layer, the water droplets or the like can be evaporated by the heat generated by the gas sensor element before penetrating to the detection unit. Thermal shock hardly occurs and damage to the element body can be suppressed.

特開2001−281210号公報JP 2001-281210 A

しかし、検出部の活性化をより早期に実現したいという近年の要求に対して、特許文献1の構造では十分に応えられない可能性がある。つまり、素子本体への耐被水性を確保するには、素子本体に対して多孔質層をある程度の厚み以上形成する必要があるが、多孔質層の厚みが厚くなればその多孔質層を含めた検出部周囲の容積が増すことになるので、セラミックヒータによって検出部を活性化温度にまで加熱するのに時間が掛かってしまうからである。また、ガスセンサ素子をなす素子本体の角部は熱衝撃等によって損傷し易い部分であり、十分な損傷防止対策が必要となるが、特許文献1に記載のガスセンサ素子では、そのようなことは特に考慮されていない。   However, there is a possibility that the structure of Patent Document 1 cannot sufficiently meet the recent request to realize the activation of the detection unit earlier. In other words, in order to ensure water resistance to the element body, it is necessary to form a porous layer with a certain thickness or more on the element body. However, if the thickness of the porous layer increases, the porous layer is included. This is because it takes time to heat the detection unit to the activation temperature by the ceramic heater because the volume around the detection unit increases. Further, the corners of the element main body constituting the gas sensor element are parts that are easily damaged by thermal shock or the like, and sufficient measures for preventing damage are required. Not considered.

本発明は、上記の従来の問題点を解決するためになされたものであり、水滴等の付着による素子本体の損傷、特に検出部及びその周辺の損傷を抑制することができ、且つ検出部の早期活性化を促すことができる積層型ガスセンサ素子、及びこの積層型ガスセンサ素子を備え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 to solve the above-described conventional problems, and can suppress damage to the element body due to adhesion of water droplets and the like, in particular, damage to the detection unit and its surroundings. It is an object of the present invention to provide a stacked gas sensor element that can promote early activation, and a gas sensor including the stacked gas sensor element.

その解決手段は、セラミック基体の内部に発熱抵抗体を埋設したセラミックヒータと、該セラミックヒータに積層されるとともに、先端側に一対の電極を配設した検出部が形成された固体電解質層とを含む素子本体であって、長手方向に延びる板状をなす素子本体を備える積層型ガスセンサ素子において、該素子本体は、上記検出部を含む先端部における長手方向及び積層方向に直交する向きの幅寸法が、残余の部位の前記幅寸法よりも小さくなっており、上記素子本体のうち少なくとも上記先端部の上記積層方向に沿った両側面が多孔質層により被覆されている積層型ガスセンサ素子である。   The solution includes a ceramic heater in which a heating resistor is embedded in a ceramic substrate, and a solid electrolyte layer that is laminated on the ceramic heater and in which a detection portion having a pair of electrodes disposed on the tip side is formed. A stacked gas sensor element comprising an element body including a plate-shaped element body extending in a longitudinal direction, wherein the element body has a width dimension in a direction perpendicular to the longitudinal direction and the stacking direction at a tip including the detection unit. However, it is a laminated gas sensor element that is smaller than the width dimension of the remaining part, and at least both side surfaces of the element body along the laminating direction of the tip are covered with a porous layer.

本発明の積層型ガスセンサ素子によれば、素子本体のうちで先端部の少なくとも両側面を、多孔質層にて被覆している。素子本体の先端部の両側面は、被測定ガスに晒される面であって、積層界面が露出する面であるため、この両側面に水滴が付着すると素子本体に損傷を招くことがあるが、本発明では、その両側面に多孔質層を形成しているので、飛水する水滴が直接側面に付着するのを抑制することができる。   According to the laminated gas sensor element of the present invention, at least both side surfaces of the tip portion of the element body are covered with the porous layer. Both side surfaces of the tip of the element body are surfaces exposed to the gas to be measured and the surface where the lamination interface is exposed.If water droplets adhere to both side surfaces, the element body may be damaged. In this invention, since the porous layer is formed in the both sides | surfaces, it can suppress that the water droplet to fly fly adheres to a side surface directly.

そして、この多孔質層に付着した水滴は、多数の気孔内を分散しながら緩慢に浸透していくことから、多孔質層の内側に位置する素子本体に到達する前に水滴を分散でき、素子本体に生ずる温度勾配を小さくし、熱衝撃を有効に抑制することができる。したがって、水滴等の付着による素子本体(検出部近傍)の損傷を防止することができる。また、積層型ガスセンサ素子は、使用時において、発熱抵抗体の通電に伴い高温状態に加熱されるので、多孔質層を浸透する水滴はその周囲の熱により蒸発され、素子本体に水滴が到達するのを抑制することも可能となる。   And since the water droplets adhering to the porous layer slowly permeate while dispersing in a large number of pores, the water droplets can be dispersed before reaching the element body located inside the porous layer. The temperature gradient generated in the main body can be reduced, and thermal shock can be effectively suppressed. Therefore, it is possible to prevent damage to the element body (near the detection unit) due to adhesion of water droplets or the like. In addition, since the stacked gas sensor element is heated to a high temperature state as the heating resistor is energized in use, water droplets that permeate the porous layer are evaporated by the surrounding heat, and the water droplets reach the element body. It is also possible to suppress this.

そして、本発明の積層型ガスセンサ素子によれば、この多孔質層が形成される素子本体の先端部の幅寸法が、素子本体の残余の部位における幅寸法よりも小さく形成されている。このため、多孔質層をある程度厚めに形成しようとした場合にも、多孔質層を含めた素子本体の先端部における幅寸法が大きくなるのを抑えることができ、残余の部分と同一の幅寸法をもつ先端部に多孔質層を形成したケースと比較して多孔質層を含めた先端部の容積を相対的に小さくすることができる。従って、本発明の積層型ガスセンサ素子によれば、多孔質層を含めた素子本体の先端部の容積を小さく抑えることができるので、従来による幅寸法が同一の素子本体の先端部側面に多孔質層を形成するケースと比較して、発熱抵抗体による発熱を効率良く先端部(検出部)に伝えられ、多孔質層をある程度に厚めに形成しつつもガスセンサ素子の早期活性化を促すことができる。   According to the multilayer gas sensor element of the present invention, the width dimension of the tip portion of the element body where the porous layer is formed is formed to be smaller than the width dimension at the remaining portion of the element body. For this reason, even when trying to form the porous layer to be somewhat thick, it is possible to suppress an increase in the width dimension at the tip of the element body including the porous layer, and the same width dimension as the remaining part The volume of the tip including the porous layer can be made relatively small as compared with the case where the porous layer is formed at the tip having the tip. Therefore, according to the multi-layer gas sensor element of the present invention, the volume of the tip of the element body including the porous layer can be kept small. Compared with the case of forming a layer, the heat generated by the heating resistor is efficiently transmitted to the tip (detection unit), and the early activation of the gas sensor element is promoted while the porous layer is formed to be thick to some extent. it can.

なお、上記「セラミック基体」は、セラミック焼結体であれば特に限定されず、高温においても絶縁性を維持されるアルミナ、スピネル、ムライト等から構成することが好ましい。これらのセラミックは1種のみを用いてもよいし、2種以上を併用することもできる。   The “ceramic substrate” is not particularly limited as long as it is a ceramic sintered body, and is preferably composed of alumina, spinel, mullite, or the like that maintains insulation even at high temperatures. These ceramics may use only 1 type and can also use 2 or more types together.

上記「発熱抵抗体」の材質についても特に限定されず、例えば、貴金属、タングステン、モリブデンを用いることができる。この貴金属としては、Pt、Au、Pd、Ir、Ru及びRhが挙げられる。これらは1種のみを用いてもよいし、2種以上を併用することもでき、2種以上の場合は合金であってもよい。さらに、貴金属のうちでは、耐熱性、耐酸化性等を考慮してPtを主体に構成することが好ましい。また、発熱抵抗体には、貴金属の他にセラミック成分を含有させることができる。このセラミック成分の種類は特に限定されないが、セラミック基体のうちの発熱抵抗体と接する部分を構成するセラミック成分と同じであることが、固着強度の観点から好ましい。   The material of the “heating resistor” is not particularly limited, and for example, a noble metal, tungsten, or molybdenum can be used. Examples of the noble metal include Pt, Au, Pd, Ir, Ru, and Rh. These may use only 1 type and can use 2 or more types together, and an alloy may be sufficient in the case of 2 or more types. Furthermore, among noble metals, it is preferable that Pt is mainly used in consideration of heat resistance, oxidation resistance, and the like. In addition to the noble metal, the heating resistor can contain a ceramic component. The type of the ceramic component is not particularly limited, but is preferably the same as the ceramic component constituting the portion of the ceramic base that contacts the heating resistor, from the viewpoint of fixing strength.

上記「固体電解質層」は、一般的に、酸素イオン伝導性を有するジルコニア(ZrO)にて構成することができる。なお、この固体電解質層には、セラミック基体の主成分をなすセラミック成分と同じ成分を含有させることができる。このセラミック成分の固体電解質層への含有量は、固体電解質層を100質量%とした場合に、10〜80質量%、好ましくは20〜70質量%とすることができる。これにより、セラミック基体と固体電解質層との間の熱膨張差による応力を緩和することができる。 The “solid electrolyte layer” can be generally composed of zirconia (ZrO 2 ) having oxygen ion conductivity. The solid electrolyte layer can contain the same component as the ceramic component that is the main component of the ceramic substrate. The content of the ceramic component in the solid electrolyte layer can be 10 to 80% by mass, preferably 20 to 70% by mass, when the solid electrolyte layer is 100% by mass. Thereby, the stress by the thermal expansion difference between a ceramic base | substrate and a solid electrolyte layer can be relieved.

また、この固体電解質層に配設される上記「電極」の材質は特に限定されないが、貴金属が好ましく、Ptが特に好ましい。電極は2種以上の金属から構成されていてもよく、2種以上の金属からなる場合は合金を用いてもよい。例えば、Ptを主成分として、Au、Ag、Pd、Ir、Ru及びRh等を含有させてもよく、Ptと他の貴金属との合金を使用してもよい。特に、高温におけるPtの揮発が抑えられるRhとの併用は有用である。   Further, the material of the “electrode” disposed on the solid electrolyte layer is not particularly limited, but a noble metal is preferable, and Pt is particularly preferable. The electrode may be composed of two or more metals, and an alloy may be used when the electrodes are composed of two or more metals. For example, Au, Ag, Pd, Ir, Ru, Rh, or the like may be contained with Pt as a main component, or an alloy of Pt and another noble metal may be used. In particular, the combined use with Rh that can suppress the volatilization of Pt at a high temperature is useful.

また、上述の積層型ガスセンサ素子であって、上記素子本体は、上記一対の検知電極及び上記発熱抵抗体と電気的に接続される複数の電極端子部が外表面に露出した後端部と、上記先端部と上記後端部との間に位置し、該先端部から該後端部に向けて徐々に上記幅寸法が大きくなる中間部とを有し、上記多孔質層は、上記先端部の両側面に加え、上記中間部の上記積層方向に沿った側面と上記先端部の側面とを繋ぐ境界部までを被覆してなる積層型ガスセンサ素子とすると良い。   Further, in the above-described laminated gas sensor element, the element body includes a rear end portion where a plurality of electrode terminal portions electrically connected to the pair of detection electrodes and the heating resistor are exposed on an outer surface, The porous layer is located between the tip portion and the rear end portion, and has an intermediate portion in which the width dimension gradually increases from the tip portion toward the rear end portion. In addition to the both side surfaces, it is preferable that the laminated gas sensor element is formed by covering up to the boundary portion connecting the side surface of the intermediate portion along the stacking direction and the side surface of the tip portion.

素子本体の検出部を含めた先端部の幅寸法を、残余の部分より小さくする形態としては、後端部と先端部との間に、先端部から後端部に向けて徐々に幅寸法が大きくなる中間部を設ける形態が挙げられる。このように中間部を設けることで、素子本体の強度を保ちつつ、幅寸法の先端部を有する素子本体を得ることができる。ところで、このような形態を図る場合、多孔質層を素子本体の先端部の側面後端縁で留めるように形成すると、先端面の側面と中間部の側面とを境界部が露出する形になるが、この境界部においても水滴等が直接付着することがあると、素子本体の損傷を招く可能性がある。   As a form in which the width dimension of the tip part including the detection part of the element body is made smaller than the remaining part, the width dimension gradually increases from the tip part toward the rear end part between the rear end part and the tip part. The form which provides the intermediate part which becomes large is mentioned. By providing the intermediate portion in this way, it is possible to obtain an element body having a width end portion while maintaining the strength of the element body. By the way, when aiming at such a form, if the porous layer is formed so as to be fastened by the rear end edge of the side surface of the tip portion of the element body, the boundary portion is exposed between the side surface of the tip surface and the side surface of the intermediate portion. However, if water droplets or the like may directly adhere to this boundary portion, the element body may be damaged.

そこで、本発明の積層型ガスセンサ素子では、素子本体部のうち、先端部の両側面に加え、中間部の側面と先端部の側面とを繋ぐ境界部までを被覆するようにしている。これにより、上記中間部を有する素子本体における損傷を抑制することができる。なお、上記中間部を有する形態の積層型ガスセンサ素子では、多孔質層のうち、上記境界部の位置における厚みを上記先端部の側面の位置における厚みよりも厚くすることが好ましい。多孔質層をこのような厚み関係をもって形成することで、より確実に素子本体の損傷を抑制することができるからである。   Therefore, in the multilayer gas sensor element of the present invention, the element main body is covered not only on both side surfaces of the tip portion but also on the boundary portion connecting the side surface of the intermediate portion and the side surface of the tip portion. Thereby, the damage in the element main body which has the said intermediate part can be suppressed. In the multilayer gas sensor element having the intermediate portion, it is preferable that the thickness of the porous layer at the position of the boundary portion is larger than the thickness of the side surface of the tip portion. This is because, by forming the porous layer with such a thickness relationship, damage to the element body can be more reliably suppressed.

さらに、上述の積層型ガスセンサ素子であって、上記素子本体の前記先端部の前記幅寸法と、該先端部の上記両側面を被覆する上記多孔質層の厚みとを合計した寸法が、上記素子本体の上記残余の部位における最大の上記幅寸法以下である積層型ガスセンサ素子とすると良い。
このように、素子本体の先端部の幅寸法と、先端部の両側面を被覆する多孔質層の厚みとを合計した寸法を、素子本体の残余の部位における最大の幅寸法以下となるように、先端部の幅寸法と多孔質層の厚みを適宜調整して積層型ガスセンサ素子を構成することで、発熱抵抗体(セラミックヒータ)によって先端部(即ち、検出部)を速やかに加熱させることができ、検出部の早期活性化を良好に促すことが可能となる。
Furthermore, in the above-described stacked gas sensor element, the total dimension of the width dimension of the tip portion of the element body and the thickness of the porous layer covering the both side surfaces of the tip portion is the element. It is preferable that the gas sensor element is a laminated gas sensor element that is not more than the maximum width dimension in the remaining portion of the main body.
Thus, the total dimension of the width dimension of the tip portion of the element body and the thickness of the porous layer covering both side surfaces of the tip section is equal to or less than the maximum width dimension in the remaining portion of the element body. By appropriately adjusting the width dimension of the tip portion and the thickness of the porous layer to constitute the laminated gas sensor element, the tip portion (that is, the detection portion) can be quickly heated by the heating resistor (ceramic heater). And early activation of the detection unit can be favorably promoted.

さらに、上記積層型ガスセンサ素子であって、上記素子本体の上記先端部の上記幅寸法をA(単位:mm)、上記発熱抵抗体のうちで該先端部に位置する部位の最大の前記幅寸法をB(単位:mm)としたときに、A×0.60<B<A×0.98の関係を満たす積層型ガスセンサ素子とする良い。
素子本体の先端部の幅寸法を基準にして、発熱抵抗体の先端部に位置する部位の最大の幅寸法を上記関係を満たすように形成することで、発熱抵抗体からの発熱によって先端部(即ち、検出部)に速やかに加熱させることができ、検出部の早期活性化を良好に促すことが可能となる。
Further, in the laminated gas sensor element, the width dimension of the tip portion of the element body is A (unit: mm), and the largest width dimension of a portion of the heating resistor located at the tip portion is When B is B (unit: mm), a stacked gas sensor element satisfying the relationship of A × 0.60 <B <A × 0.98 may be used.
By forming the maximum width dimension of the portion located at the distal end portion of the heating resistor so as to satisfy the above relationship on the basis of the width dimension of the distal end portion of the element body, the distal end portion ( That is, it is possible to quickly heat the detection unit), and it is possible to favorably promote early activation of the detection unit.

さらに、上記積層型ガスセンサ素子であって、上記多孔質層は、上記素子本体のうち少なくとも上記先端部の両側面を被覆する第1多孔質層と、該第1多孔質層が形成された上記素子本体の上記先端部の周囲を覆う第2多孔質層とを有する積層型ガスセンサ素子とすると良い。   Furthermore, in the stacked gas sensor element, the porous layer includes a first porous layer covering at least both side surfaces of the tip portion of the element body, and the first porous layer formed thereon. A laminated gas sensor element having a second porous layer covering the periphery of the tip of the element body is preferable.

本発明の積層型ガスセンサ素子では、素子本体の先端部の両側面を被覆する第1多孔質層と、この第1多孔質層が形成された先端部の周囲を覆う第2多孔質層とよって多孔質層が形成されているので、被水による素子本体の損傷をより効率よく抑制することができる。つまり、本発明の積層型ガスセンサ素子では、素子本体の積層方向に沿った断面形状が略四角形状の板状をなすため、素子本体に角部が存在するものであるが、この角部に水滴が付着すると、熱応力が集中し易く素子本体にクラックが生じ易い傾向にある。そこで、素子本体の先端部の両側面を被覆する第1多孔質層に加えて、第2多孔質層を先端部の周囲を覆うように設ければ、素子本体の角部に水滴が直接付着するのを防止することができ、被水による素子本体の損傷を有効に抑制することができる。また、多孔質層は単層では厚みを厚くするのに限界があるが、上記のように第2多孔質層を設けることで多孔質層の厚さがコントロールし易く、設計上の観点からも有効となる。   In the laminated gas sensor element of the present invention, the first porous layer covering both side surfaces of the tip portion of the element body and the second porous layer covering the periphery of the tip portion where the first porous layer is formed. Since the porous layer is formed, it is possible to more efficiently suppress damage to the element main body due to moisture. That is, in the laminated gas sensor element of the present invention, since the cross-sectional shape along the stacking direction of the element body is a substantially square plate, the element body has corners. If it adheres, thermal stress tends to concentrate and the element body tends to crack. Therefore, in addition to the first porous layer covering both sides of the tip of the element body, if a second porous layer is provided so as to cover the periphery of the tip, water droplets directly adhere to the corners of the element body. It is possible to prevent the element main body from being damaged, and to effectively prevent damage to the element body due to water exposure. In addition, although there is a limit to increasing the thickness of a single porous layer, the thickness of the porous layer can be easily controlled by providing the second porous layer as described above, and from the viewpoint of design. It becomes effective.

さらに、上記積層型ガスセンサ素子であって、上記多孔質層は、上記素子本体のうち上記先端部の両側面を含む当該先端部の周囲を覆うように形成されており、上記素子本体の角部からの上記多孔質層の厚みが20μm以上である積層型ガスセンサ素子とすると良い。このように、多孔質層により素子本体の先端部の周囲を覆いつつ、素子本体の角部からの多孔質層の厚みを20μm以上とすることで、被水による素子本体の損傷を効果的に防止することができる。また、より有効に被水による素子本体の損傷を防止するには、多孔質層の素子本体の角部からの厚みを、30μm以上とする(より好ましくは、50μm以上)ことが好ましい。なお、本明細書において「多孔質層の素子本体の角部からの厚みを20μm以上とする」とは、素子本体の積層方向に沿った断面をとったときに、素子本体の角部の多孔質層との間に直径20μmの仮想円が当該多孔質層に内包されることを意味するものである。また、ここでいう「角部」とは、板状の素子本体のうちで、長手方向に延びる表裏面のうちのいずれか一面と、両側面のいずれか一面とを連結する箇所を指すものであり、2つの面が交わる線上部(即ち、稜)のみに限られず、2つの面を例えばR形状で連結する曲面部をも含むものとする。   Further, in the stacked gas sensor element, the porous layer is formed so as to cover the periphery of the tip portion including both side surfaces of the tip portion of the element body, and the corner portion of the element body. It is preferable that the porous gas sensor element has a thickness of 20 μm or more. Thus, by covering the periphery of the tip of the device body with the porous layer and making the thickness of the porous layer from the corners of the device body 20 μm or more, it is possible to effectively damage the device body due to moisture. Can be prevented. In order to more effectively prevent damage to the element body due to moisture, the thickness of the porous layer from the corner of the element body is preferably 30 μm or more (more preferably 50 μm or more). In the present specification, “the thickness of the porous layer from the corner of the element body is 20 μm or more” means that the pores at the corners of the element body are taken when a cross section is taken along the stacking direction of the element body. This means that a virtual circle having a diameter of 20 μm is included in the porous layer between the porous layer and the porous layer. In addition, the “corner portion” as used herein refers to a location where any one of the front and back surfaces extending in the longitudinal direction and any one of both side surfaces are connected in the plate-shaped element body. Yes, it is not limited only to the upper part of the line where the two surfaces intersect (that is, the ridge), and includes a curved surface portion that connects the two surfaces in an R shape, for example.

さらに、上記積層型ガスセンサ素子であって、上記多孔質層は、空孔率が15%〜65%の範囲内にあることが好ましい。空孔率が15%未満である場合、多孔質層により水滴を分散させながら緩慢に浸透させる機能を十分に発揮することができないおそれがある。また、空孔率が65%を超えると、多孔質層における水滴等の浸透度合いが高くなり、水滴等が素子本体に接触し易くなり、被水による素子本体の損傷抑制効果を十分に期待することができないおそれがある。なお、上記「空孔率」は、多孔質層の断面を走査型電子顕微鏡にて分析し、その分析によって得られた拡大写真より、単位面積当たりに占める空孔の面積の比率(%)として求めることができる。   Furthermore, in the multilayer gas sensor element, the porous layer preferably has a porosity in a range of 15% to 65%. When the porosity is less than 15%, there is a possibility that the function of slowly penetrating while dispersing water droplets by the porous layer may not be exhibited sufficiently. In addition, when the porosity exceeds 65%, the degree of penetration of water droplets and the like in the porous layer increases, and the water droplets and the like easily come into contact with the element body, and the effect of suppressing damage to the element body due to moisture is sufficiently expected. There is a risk that it will not be possible. The “porosity” is the ratio of the area of the pores per unit area (%) from the enlarged photograph obtained by analyzing the cross section of the porous layer with a scanning electron microscope. Can be sought.

また、他の解決手段は、上述した積層型ガスセンサ素子と、前記検出部を先端から突き出させた状態で、前記積層型ガスセンサ素子の周方向を取り囲む筒状のハウジングと、を備えることを特徴とするガスセンサである。   According to another aspect of the present invention, there is provided another solution, comprising: the above-described stacked gas sensor element; and a cylindrical housing that surrounds a circumferential direction of the stacked gas sensor element in a state where the detection unit protrudes from a tip. It is a gas sensor.

本発明のガスセンサは、水滴等の付着による素子本体の損傷が生じ難い積層型ガスセンサ素子を用いて構成されているので、耐被水性に優れ、信頼性が高いものとなる。さらに、本発明のガスセンサによれば、検出部の早期活性化を実現可能な積層型ガスセンサ素子を用いて構成されているので、ガス検知を早期に促すことができ、近年の厳しい排気ガス規制に対しても対応可能なガスセンサとなり得る。   Since the gas sensor of the present invention is configured using a laminated gas sensor element in which damage to the element main body due to adhesion of water droplets or the like does not occur, the gas sensor has excellent water resistance and high reliability. Furthermore, according to the gas sensor of the present invention, since it is configured using a stacked gas sensor element that can realize early activation of the detection unit, gas detection can be promptly promoted, and the recent severe exhaust gas regulations It can become a gas sensor which can respond also to it.

本発明の実施の形態を、実施例及び変形例に基づいて説明する。   Embodiments of the present invention will be described based on examples and modifications.

(実施例)
まず、本発明の実施例に係るガスセンサ5を、図10を参照して説明する。本実施例のガスセンサ5は、図10に示すように、積層型ガスセンサ素子1が組み込まれたガスセンサであり、内燃機関の排気管に取り付けられ、排気ガス中の酸素濃度測定に使用される。このガスセンサ5では、筒状のハウジング52の内側に、検出部を突き出させた状態で積層型ガスセンサ素子1が挿通されている。なお、積層型ガスセンサ素子1は、ハウジング52内でガラスシールされることによって、ハウジング52の所定の位置に保持されている。ハウジング52の先端部外周には、積層型ガスセンサ素子1の検出部を含む先端側を覆うように二重構造のプロテクタ53が固着されている。また、このプロテクタ53には、その先端及び側周面に排気管内を流通する排気ガスを内部に導くための通気孔531が形成されている。このように、積層型ガスセンサ素子1のうちハウジング52の先端から突出する検出部を先端側が、被検知ガス(排気ガス)に晒される部分となる。なお、積層型ガスセンサ素子5の検出部を含む先端部101の両側面及び先端面には、それらの面を覆うように後述する多孔質保護層13が形成されている。
(Example)
First, the gas sensor 5 which concerns on the Example of this invention is demonstrated with reference to FIG. As shown in FIG. 10, the gas sensor 5 of the present embodiment is a gas sensor in which a stacked gas sensor element 1 is incorporated, and is attached to an exhaust pipe of an internal combustion engine and used for measuring oxygen concentration in exhaust gas. In the gas sensor 5, the stacked gas sensor element 1 is inserted inside the cylindrical housing 52 with the detection portion protruding. The laminated gas sensor element 1 is held at a predetermined position of the housing 52 by being glass sealed in the housing 52. A double-structure protector 53 is fixed to the outer periphery of the front end portion of the housing 52 so as to cover the front end side including the detection portion of the stacked gas sensor element 1. Further, the protector 53 is formed with a vent hole 531 at the tip and side peripheral surface thereof for guiding the exhaust gas flowing through the exhaust pipe to the inside. As described above, the detection portion protruding from the front end of the housing 52 in the stacked gas sensor element 1 is a portion where the front end side is exposed to the detected gas (exhaust gas). Note that a porous protective layer 13 described later is formed on both side surfaces and the front end surface of the front end portion 101 including the detection portion of the multilayer gas sensor element 5 so as to cover those surfaces.

さらに、ハウジング52の後端部は外筒51の先端部内側に挿入されるとともに、ハウジング52の後端部と外筒51の先端部との重なり部にて全周レーザ溶接が施され、両者が固着されている。また、ハウジング52の外周部には、ガスセンサ5を排気管に取り付けるためのネジ部521が形成されている。さらに、ガスセンサ5は、外筒51の内部から外部に向かって引き出される4本のリード線54(図10では、2本のみ図示)を有している。これらのリード線54は、外筒51の内部に収容される中継端子55を介して積層型ガスセンサ素子1と電気的に接続されている。具体的には、リード線54は、後述する検知素子11の検知電極112、基準電極113、セラミックヒータ12の発熱抵抗体121の正極、負極にそれぞれ個別に電気的に接続されている。また、リード線54は、外筒51の後端側に嵌合されたグロメット511のリード線挿通孔を挿通して外部に延び、外部回路に対して電気的に接続される。   Further, the rear end portion of the housing 52 is inserted inside the front end portion of the outer cylinder 51, and all-around laser welding is performed at the overlapping portion between the rear end portion of the housing 52 and the front end portion of the outer cylinder 51. Is fixed. A screw portion 521 for attaching the gas sensor 5 to the exhaust pipe is formed on the outer periphery of the housing 52. Furthermore, the gas sensor 5 has four lead wires 54 (only two are shown in FIG. 10) drawn from the inside of the outer cylinder 51 toward the outside. These lead wires 54 are electrically connected to the stacked gas sensor element 1 via relay terminals 55 housed inside the outer cylinder 51. Specifically, the lead wires 54 are individually electrically connected to a detection electrode 112 of the detection element 11, which will be described later, a reference electrode 113, and a positive electrode and a negative electrode of the heating resistor 121 of the ceramic heater 12, respectively. The lead wire 54 extends through the lead wire insertion hole of the grommet 511 fitted to the rear end side of the outer cylinder 51 and is electrically connected to an external circuit.

ついで、本発明の主要部である積層型ガスセンサ素子1について、詳細に説明する。なお、本実施例の積層型ガスセンサ素子1は、排気ガス中の酸素濃度を検出するためのものであり、積層型酸素センサ素子と言うこともできる。   Next, the laminated gas sensor element 1 which is a main part of the present invention will be described in detail. The laminated gas sensor element 1 of this embodiment is for detecting the oxygen concentration in the exhaust gas, and can also be called a laminated oxygen sensor element.

[1]積層型ガスセンサ素子1の構造
積層型ガスセンサ素子1の構造について、図1〜図3を用いて説明する。なお、図3は積層型ガスセンサ素子1の分解斜視図であり、この積層型ガスセンサ素子1は、検出素子11とセラミックヒータ12とが積層されて構成されている。この図3では、多孔質保護層13の図示を省略している。
[1] Structure of Laminated Gas Sensor Element 1 The structure of the laminated gas sensor element 1 will be described with reference to FIGS. 3 is an exploded perspective view of the multilayer gas sensor element 1. The multilayer gas sensor element 1 is configured by laminating a detection element 11 and a ceramic heater 12. FIG. In FIG. 3, illustration of the porous protective layer 13 is omitted.

検出素子11は、所定量のイットリアを安定化剤として固溶させた酸素イオン伝導性を有する部分安定化ジルコニア60質量%と、アルミナ40質量%とを含有した固体電解質層111を備える。この固体電解質層111の先端側の表面には検知電極112が形成され、裏面の検知電極112に対応する位置には基準電極113が形成されている。検知電極112及び基準電極113には、それぞれ検知電極リード部1121及び基準電極リード部1131が延設されている。なお、本実施例では、固体電解質層111を検知電極112及び基準電極113にて挟み込んでいる部分が「検出部」に相当する。   The detection element 11 includes a solid electrolyte layer 111 containing 60% by mass of partially stabilized zirconia having oxygen ion conductivity in which a predetermined amount of yttria is dissolved as a stabilizer and 40% by mass of alumina. A detection electrode 112 is formed on the front surface of the solid electrolyte layer 111, and a reference electrode 113 is formed at a position corresponding to the detection electrode 112 on the back surface. A detection electrode lead portion 1121 and a reference electrode lead portion 1131 are extended from the detection electrode 112 and the reference electrode 113, respectively. In this embodiment, the portion where the solid electrolyte layer 111 is sandwiched between the detection electrode 112 and the reference electrode 113 corresponds to a “detection unit”.

また、検知電極リード部1121の末端は、保護絶縁層115を貫通するスルーホール導体1152により中継端子55(図10参照)と接続するための信号取り出し用端子パッド1142と接続されている。更に、基準電極リード部1131の末端は、固体電解質体111を貫通するスルーホール導体1111及び保護絶縁層115を貫通するスルーホール導体1151により中継端子55と接続するための信号取り出し用端子パッド1141と接続されている。また、固体電解質体111の検知電極112が形成されている表面には、検知電極112の被毒を防止するため、多孔質体からなる電極保護層116が形成されている。   Further, the end of the detection electrode lead part 1121 is connected to a signal extraction terminal pad 1142 for connection to the relay terminal 55 (see FIG. 10) by a through-hole conductor 1152 that penetrates the protective insulating layer 115. Further, the terminal of the reference electrode lead portion 1131 is a signal extraction terminal pad 1141 for connection to the relay terminal 55 by a through-hole conductor 1111 penetrating the solid electrolyte body 111 and a through-hole conductor 1151 penetrating the protective insulating layer 115. It is connected. In addition, an electrode protective layer 116 made of a porous body is formed on the surface of the solid electrolyte body 111 on which the detection electrode 112 is formed in order to prevent the detection electrode 112 from being poisoned.

セラミックヒータ12は、白金からなる発熱抵抗体121を有し、この発熱抵抗体121は、絶縁性に優れるアルミナを主成分とする第1アルミナ層122及び第2アルミナ層123に挟持されている。この発熱抵抗体121にはリード部1211が延設され、このリード部1211の各々の末端は、第1アルミナ層122を貫通する2個のスルーホール導体1221、1222によりヒータ通電用端子パッド1241、1242と電気的に接続されている。このヒータ通電用端子パッド1241、1242は中継端子55(図10参照)と接続されている。   The ceramic heater 12 has a heat generating resistor 121 made of platinum, and the heat generating resistor 121 is sandwiched between a first alumina layer 122 and a second alumina layer 123 mainly composed of alumina having excellent insulating properties. A lead portion 1211 extends from the heating resistor 121, and each end of the lead portion 1211 is connected to the heater energizing terminal pad 1241 by two through-hole conductors 1221 and 1222 that penetrate the first alumina layer 122. 1242 is electrically connected. The heater energization terminal pads 1241 and 1242 are connected to the relay terminal 55 (see FIG. 10).

さらに、検知部を含むようにして積層方向に沿って積層型ガスセンサ素子1の断面をとったとき、図2に示すように、検出素子11とセラミックヒータ12との積層体からなる素子本体の周囲全体が、第1多孔質層131及び第2多孔質層132より構成される多孔質保護層13にて被覆されている。また、図10を援用して示すが、積層型ガスセンサ素子1の素子本体の先端面についても、多孔質保護層13にて被覆されている。この多孔質保護層13の厚さは素子本体の角部から200μmである。   Furthermore, when the cross section of the multilayer gas sensor element 1 is taken along the stacking direction so as to include the detection unit, as shown in FIG. 2, the entire periphery of the element body composed of the stacked body of the detection element 11 and the ceramic heater 12 is The porous protective layer 13 is composed of the first porous layer 131 and the second porous layer 132. In addition, as shown in FIG. 10, the end surface of the element body of the multilayer gas sensor element 1 is also covered with the porous protective layer 13. The thickness of the porous protective layer 13 is 200 μm from the corner of the element body.

なお、この実施例の積層型ガスセンサ素子1の多孔質保護層13を除いた部分の寸法は、長さ(長手方向に沿った寸法)が40mm、幅寸法(長手方向及び積層方向に直交する向きの寸法)が3mm、厚さ(積層方向に沿った寸法)が2mmである。また、図3にやや誇張して示すように、素子本体のうちで検出部を含む先端部101の幅寸法は残余の部位の幅寸法よりも小さく形成されている。具体的には、素子本体の先端部101の幅寸法は2.7mmであり、残余の部分の幅寸法は3.0mmであって、検出部に対応する部分で300μm(幅方向の片側で150μm)幅寸法が小さくなっている。そして、幅寸法が残余の部分より小さく形成された先端部101の少なくとも両側面を覆うように、多孔質保護層13が形成されている(図2参照)。また、本実施例では、先端部101の幅寸法をA(単位:mm)、発熱抵抗体121のうちで先端部101に位置する部位の最大の幅寸法をB(単位:mm)としたとき、A×0.90=Bとなるように、発熱抵抗体121の幅寸法等が適宜調整されている。   In addition, as for the dimension of the portion excluding the porous protective layer 13 of the multilayer gas sensor element 1 of this embodiment, the length (dimension along the longitudinal direction) is 40 mm, and the width dimension (the direction perpendicular to the longitudinal direction and the laminating direction). ) Is 3 mm, and the thickness (dimension along the stacking direction) is 2 mm. Further, as shown in a slightly exaggerated manner in FIG. 3, the width dimension of the tip portion 101 including the detection portion in the element body is formed smaller than the width dimension of the remaining portion. Specifically, the width dimension of the tip 101 of the element body is 2.7 mm, the width dimension of the remaining part is 3.0 mm, and 300 μm at the part corresponding to the detection part (150 μm on one side in the width direction). ) The width dimension is small. And the porous protective layer 13 is formed so that the width dimension may cover at least both side surfaces of the front-end | tip part 101 formed smaller than the remaining part (refer FIG. 2). Further, in this embodiment, when the width dimension of the tip portion 101 is A (unit: mm) and the maximum width dimension of the portion of the heating resistor 121 located at the tip portion 101 is B (unit: mm). The width dimension of the heating resistor 121 is appropriately adjusted so that A × 0.90 = B.

[2]積層型ガスセンサ素子の製造
ついで、本実施例に係る積層型ガスセンサ素子1の製造について説明する。
この積層型ガスセンサ素子1は、未焼成シート積層体を作製した後、貫通孔形成工程、充填工程、切出工程及び焼成工程を、この順に行うことにより製造される。また、焼成工程の後、被覆工程を行うことにより第2多孔質層132が形成される。
[2] Production of Multilayer Gas Sensor Element Next, production of the multilayer gas sensor element 1 according to the present embodiment will be described.
The laminated gas sensor element 1 is manufactured by performing a through-hole forming step, a filling step, a cutting step, and a firing step in this order after producing an unfired sheet laminate. Moreover, the 2nd porous layer 132 is formed by performing a coating | coated process after a baking process.

(1)未焼成検出素子の作製
イットリアを固溶させた部分安定化ジルコニア粉末60質量%とアルミナ粉末40質量%とを、有機バインダ及び有機溶剤等とともに湿式混合してなるスラリーを用いて、固体電解質層111となる未焼成シートを作製した。この未焼成シートは32個の未焼成ガスセンサ素子を切り出すことができる大きさであり、その所定位置に素子32個分のスルーホールを形成した。なお、未焼成シートは、上記のように32個の未焼成ガスセンサ素子を切り出すことができる大きさに形成されるものであるが、個片同士は所定の間隔(捨て代)を隔てて設けられている。その後、未焼成シートの表面と裏面の所定個所に、白金を主成分とする導電ペーストを所定のパターンに印刷し、乾燥させて、検知電極112、基準電極113、それぞれのリード部1121、1131となる電極パターン、及びスルーホール導体1111となる未焼成導体を形成した。
(1) Production of unsintered detection element Solid using a slurry obtained by wet-mixing 60% by mass of partially stabilized zirconia powder in which yttria is dissolved and 40% by mass of alumina powder together with an organic binder and an organic solvent An unfired sheet to be the electrolyte layer 111 was produced. This unfired sheet has a size capable of cutting out 32 unfired gas sensor elements, and through holes for 32 elements were formed at predetermined positions. The unsintered sheet is formed in such a size that the 32 unsintered gas sensor elements can be cut out as described above, but the individual pieces are provided with a predetermined interval (disposal allowance) therebetween. ing. Thereafter, a conductive paste containing platinum as a main component is printed in a predetermined pattern at predetermined locations on the front and back surfaces of the unfired sheet, and dried to detect the detection electrode 112, the reference electrode 113, and the respective lead portions 1121, 1131 and An unfired conductor to be an electrode pattern and a through-hole conductor 1111 were formed.

(2)未焼成ヒータの作製
アルミナ粉末を、有機バインダ及び有機溶剤等とともに湿式混合してなるペーストを用いて、第1アルミナ層122となる未焼成アルミナシートを形成し、素子32個分のスルーホールを形成した。その後、第1アルミナ層122となる未焼成アルミナシートの一面の所定個所に、上記(1)と同様の導電ペーストを所定のパターンに印刷し、乾燥して、発熱抵抗体121及びそれに延設されたリード部1211となる発熱抵抗体パターン、並びにスルーホール導体1221、1222となる未焼成導体を形成した。また、第1アルミナ層122となる未焼成アルミナシートの他面の所定個所に、(1)と同様の導電ペーストを用いてヒータ通電用端子パッド1241、1242となる所定の端子パターンを印刷し、乾燥した。次いで、第2アルミナ層123となる未焼成アルミナシートを第1アルミナ層122の場合と同様の方法で作製し、乾燥した後に、この第2アルミナ層123となる未焼成アルミナシートの一面を、第1アルミナ層122となる未焼成アルミナシートの発熱抵抗体パターンが形成された面に積層し、減圧圧着させた。このようにして、未焼成ヒータを作製した。なお、各未焼成アルミナシートについても、32個の第1アルミナ層122、第2アルミナ層123が切り出せる大きさを有しており、個片同士は所定の間隔(捨て代)を隔てて設けられている。
(2) Production of unsintered heater Using a paste obtained by wet mixing alumina powder together with an organic binder, an organic solvent, etc., an unsintered alumina sheet to be the first alumina layer 122 is formed, and thirty-two elements are passed through. A hole was formed. Thereafter, a conductive paste similar to the above (1) is printed in a predetermined pattern on a predetermined portion of one surface of the unfired alumina sheet to be the first alumina layer 122, dried, and extended to the heating resistor 121 and the heating resistor 121. The heating resistor pattern to be the lead portion 1211 and the unfired conductor to be the through-hole conductors 1221 and 1222 were formed. Further, a predetermined terminal pattern to be the heater energizing terminal pads 1241 and 1242 is printed on a predetermined portion of the other surface of the unfired alumina sheet to be the first alumina layer 122 by using the same conductive paste as in (1), Dried. Next, an unfired alumina sheet to be the second alumina layer 123 is prepared by the same method as that for the first alumina layer 122 and dried. The unfired alumina sheet to be the one alumina layer 122 was laminated on the surface on which the heating resistor pattern was formed, and was pressure-bonded under reduced pressure. In this way, an unfired heater was produced. Each unsintered alumina sheet also has a size that allows the 32 first alumina layers 122 and the second alumina layers 123 to be cut out, and the individual pieces are provided at a predetermined interval (disposal allowance). It has been.

(3)未焼成シート積層体の形成
(1)で作製した検出素子用未焼成シートと、(2)で作製した未焼成ヒータとを、(1)で作製した検出素子用未焼成シートの、基準電極113及びリード部1131となる電極パターンが形成された面と、(2)で作製した未焼成ヒータの第2アルミナ層123となる未焼成アルミナシートの他面とを向かい合わせて積層した。このようにして、未焼成シート積層体を作製した。
(3) Formation of unsintered sheet laminate The unsintered sheet for detection element prepared in (1) and the unsintered heater prepared in (2) The surface on which the electrode pattern to be the reference electrode 113 and the lead portion 1131 was formed and the other surface of the unfired alumina sheet to be the second alumina layer 123 of the unfired heater produced in (2) were laminated face to face. In this way, an unfired sheet laminate was produced.

(4)印刷工程
(3)で形成した未焼成シート積層体の検出部を含む先端部のうちで未焼成ヒータの裏面(即ち、第1アルミナ層122となる未焼成アルミナシートの発熱抵抗体パターンが形成された面とは反対側の面)に対して、第1多孔質層131の一部となる未焼成第1多孔質層を形成するための第1多孔質層用ペーストをスクリーン印刷し、厚さ約30μmの塗膜を形成した。その後、塗膜を95℃で2分間乾燥させた。また、印刷に用いた第1多孔質層用ペーストは、アルミナ粉末を100質量部、有機バインダとしてポリビニルブチラールを15.5質量部、有機溶剤としてブチルカルビトールを42質量部、及び気孔化剤として粒径5〜20μmのカーボン粉末を65質量部それぞれ配合したものである。
(4) Printing process The heating resistor pattern of the unfired alumina sheet that becomes the first alumina layer 122 in the front end portion including the detection part of the unfired sheet laminate formed in (3) (that is, the unfired alumina sheet 122) The first porous layer paste for forming the unfired first porous layer that is a part of the first porous layer 131 is screen printed on the surface opposite to the surface on which the first porous layer 131 is formed. A coating film having a thickness of about 30 μm was formed. Thereafter, the coating film was dried at 95 ° C. for 2 minutes. The first porous layer paste used for printing is 100 parts by mass of alumina powder, 15.5 parts by mass of polyvinyl butyral as an organic binder, 42 parts by mass of butyl carbitol as an organic solvent, and as a pore forming agent. 65 parts by mass of carbon powder having a particle size of 5 to 20 μm is blended.

(5)貫通孔形成工程
未焼成シート積層体に、図4及び図5に示すように、略コの字状の平面形状を有し、幅寸法が500μmの貫通孔2を形成した。これにより、未焼成シート積層体のうちで検出部の形成が予定される部位を含む先端部101の両側面及び先端面の三面に対して貫通孔2が同時に形成される。つまり、未焼成シート積層体の積層方向に沿って貫通孔2を形成することによって、この貫通孔2が形成された箇所が、幅狭の先端部101を構成することになる。なお、1枚の未焼成シート積層体に対して、打ち抜き法により素子32個分の貫通孔2を形成した。また、幅が500μmの貫通孔2は、図4に示すように、未焼成シート積層体における複数の個片同士間に形成される捨て代に一部が跨るように形成した(図4において、破線で囲んだ部位が後述の工程において切り出される各未焼成素子の大きさを示す。)。
(5) Through-hole formation process As shown in FIG.4 and FIG.5, the through-hole 2 which has a substantially U-shaped planar shape, and whose width dimension is 500 micrometers was formed in the unbaking sheet | seat laminated body. Thereby, the through-hole 2 is simultaneously formed with respect to the both sides | surfaces of the front-end | tip part 101 including the site | part by which formation of a detection part is planned among the unbaked sheet | seat laminated bodies, and three surfaces of a front-end | tip surface. That is, by forming the through hole 2 along the stacking direction of the unfired sheet laminate, the portion where the through hole 2 is formed constitutes the narrow tip portion 101. In addition, the through-hole 2 for 32 elements was formed with respect to one unbaked sheet laminated body by the punching method. Moreover, as shown in FIG. 4, the through-hole 2 having a width of 500 μm was formed so that part of the through-hole 2 extends between the plurality of pieces in the green sheet laminate (in FIG. 4, The part surrounded by the broken line indicates the size of each green element cut out in the process described later.)

(6)充填工程
図6及び図7のように、未焼成シート積層体の下面に離型剤3を配し、また、上面にマスク4を載置した状態で、未焼成第1多孔質層131’を形成するための第1多孔質層用ペーストをスキージによって貫通孔2に充填した。その後、充填したペーストを60℃で180分間乾燥させた。充填に用いた第1多孔質層用ペーストは、上記した(4)印刷工程で用いたペーストと同じものであり、貫通孔2に充填することが容易であり、且つ充填後は垂れ流れることがない程度の粘度とした。なお、離型剤3としては、図8に示すように、表面に凹部と凸部との差が約10μmである凹凸を有し、防水加工を施した紙からなるものを用いた。また、マスク4としては、金属製であり、厚さが120μmであり、マスク孔41の幅が貫通孔2の幅500μmより400μm幅広の幅900μmのものを使用した。これにより、未焼成第1多孔質層131’が充填された未焼成シート積層体を作製した。
(6) Filling Step As shown in FIGS. 6 and 7, the unfired first porous layer is provided with the release agent 3 disposed on the lower surface of the unfired sheet laminate and the mask 4 placed on the upper surface. The first porous layer paste for forming 131 ′ was filled into the through holes 2 with a squeegee. Thereafter, the filled paste was dried at 60 ° C. for 180 minutes. The first porous layer paste used for filling is the same as the paste used in the above-described (4) printing process, and it is easy to fill the through-holes 2 and can flow down after filling. The viscosity was not so high. In addition, as the release agent 3, as shown in FIG. 8, a material made of paper having a concavo-convex difference of about 10 μm between the concave portion and the convex portion on the surface and subjected to waterproof processing was used. The mask 4 is made of metal, has a thickness of 120 μm, and has a mask hole 41 having a width of 900 μm, which is 400 μm wider than the width 500 μm of the through hole 2. This produced the unbaked sheet laminated body with which unbaked 1st porous layer 131 'was filled.

(7)未焼成シート積層体への保護層用未焼成シート及び保護絶縁層用未焼成シートの圧着
所定のアルミナ粉末とカーボン粉末、バインダ及び有機溶剤等を湿式混合してなるスラリーを用いて、電極保護層116となる保護層用未焼成シートを形成した。次いで、第1及び第2アルミナ層122、123となる未焼成アルミナシートと同じ組成の未焼成アルミナシートを用いて、保護絶縁層115となる保護絶縁層用未焼成シートを形成した。その後、この保護絶縁層用未焼成シートに、スルーホール導体1151、1152となる未焼成導体、及び信号取出用端子パッド1141、1142となる端子パターンを形成した。そして、上記(6)の充填工程後の未焼成シート積層体の検知電極112となる電極パターンが形成された側に、保護層用未焼成シートと保護絶縁層用未焼成シートを適宜積層し、減圧圧着させた。
(7) Pressure bonding of the unfired sheet for the protective layer and the unfired sheet for the protective insulating layer to the unfired sheet laminate, using a slurry obtained by wet-mixing a predetermined alumina powder and carbon powder, a binder, an organic solvent, and the like, An unfired sheet for a protective layer to be the electrode protective layer 116 was formed. Next, an unfired sheet for protective insulating layer to be the protective insulating layer 115 was formed using an unfired alumina sheet having the same composition as the unfired alumina sheets to be the first and second alumina layers 122 and 123. Thereafter, unfired conductors serving as through-hole conductors 1151 and 1152 and terminal patterns serving as signal extraction terminal pads 1141 and 1142 were formed on the unfired sheet for protective insulating layer. And on the side where the electrode pattern to be the detection electrode 112 of the green sheet laminate after the filling step (6) is formed, the green sheet for the protective layer and the green sheet for the protective insulating layer are appropriately laminated, Pressurized under reduced pressure.

(8)分離工程
(6)において貫通孔2に第1多孔質層用ペーストが充填され、(7)において未焼成シート積層体に更に保護層用未焼成シート及び保護絶縁層用未焼成シートが積層された図9に示す積層体を、破線に沿って刃物で順次切断して計32個の未焼成素子を得た。なお、各未焼成素子の切断にあたっては、未焼成シート積層体の側面と第1多孔質層用ペーストからなる未焼成第1多孔質層131’の側面との間に段差が生じないように切断を行った。また、切断後の未焼成素子において、先端部の両側面、先端面からの未焼成第1多孔質層131’の厚さが180μmとなるように切断した。
(8) Separation step In (6), the through-hole 2 is filled with the first porous layer paste. In (7), the unfired sheet laminate is further provided with an unfired sheet for protective layer and an unfired sheet for protective insulating layer. The laminated body shown in FIG. 9 was sequentially cut with a blade along the broken line to obtain a total of 32 unfired elements. When cutting each green element, cut so as not to cause a step between the side surface of the green sheet laminate and the side surface of the green first porous layer 131 ′ made of the first porous layer paste. Went. Further, in the unfired element after cutting, cutting was performed so that the thickness of the unfired first porous layer 131 ′ from both side surfaces and the tip surface of the tip portion was 180 μm.

(9)焼成工程
(8)において得られた未焼成素子を、大気雰囲気下、脱脂炉にて室温から20℃/時間の速度で450℃まで昇温させ、450℃で1時間保持して脱脂(脱バインダ処理)した。その後、焼成炉にて200℃/時間の速度で昇温させ、最高温度1500℃で1時間焼成した。この焼成により未焼成第1多孔質層131’に含まれる気孔化剤が焼失して気孔が生成し、第1多孔質層131が形成される。
(9) Firing step The unfired element obtained in (8) is heated from room temperature to 450 ° C. at a rate of 20 ° C./hour in an air atmosphere in a degreasing furnace and held at 450 ° C. for 1 hour for degreasing. (Debinding process). Thereafter, the temperature was raised at a rate of 200 ° C./hour in a firing furnace and fired at a maximum temperature of 1500 ° C. for 1 hour. By this firing, the pore forming agent contained in the unfired first porous layer 131 ′ is burned off to generate pores, and the first porous layer 131 is formed.

(10)第2多孔質層形成工程
第1多孔質層131が形成された素子本体の検出部を含む先端側の周囲全体に、アルミナ粉末、バインダ(ポリビニルブチラール)、有機溶剤、気孔化剤としてのカーボン粉末を含有するペーストを、焼成後における多孔質保護層13の素子本体の角部からの厚さが250μmとなるように印刷し、乾燥させる。その後、この状態の素子本体を大気雰囲気下にて毎時10℃で昇温していき、最高温度900℃で1時間熱処理し、第2多孔質層132、ひいては多孔質保護層13を形成した。このようにして素子本体における先端部101が残余の部分よりも幅狭に構成され、且つ先端部101が多孔質保護層13によって被覆された積層型ガスセンサ素子1を得た。
(10) Second porous layer forming step As an alumina powder, a binder (polyvinyl butyral), an organic solvent, and a pore forming agent on the entire periphery on the front end side including the detection portion of the element body on which the first porous layer 131 is formed. A paste containing the carbon powder is printed so that the thickness from the corner of the element body of the porous protective layer 13 after firing is 250 μm and dried. Thereafter, the element body in this state was heated at 10 ° C./hour in an air atmosphere and heat-treated at a maximum temperature of 900 ° C. for 1 hour to form the second porous layer 132 and thus the porous protective layer 13. In this way, the stacked gas sensor element 1 in which the tip portion 101 in the element body was configured to be narrower than the remaining portion and the tip portion 101 was covered with the porous protective layer 13 was obtained.

(変形例)
ついで、上述の実施例の変形例に係る積層型ガスセンサ素子20及びそれを組み込んだガスセンサ5について、図11〜図13を参照して説明する。なお、図11は、本変形例に係る積層型ガスセンサ素子20の斜視図であり、図12は、積層型ガスセンサ素子20の平面図(図11の上側から平面視したときの図)である。
本変形例に係る積層型ガスセンサ素子20は、検出素子11とセラミックヒータ12とを積層してなる素子本体において、検出部を含む先端部101と信号取り出し用端子パッド1141、1142及びヒータ通電用端子パッド(図示省略)が形成される後端部105との間に、先端部101から後端部105に向けて徐々に幅寸法が大きくなる中間部103を設け、先端部101の両側面を加え、中間部103の積層方向に沿った側面と先端部101の側面とを繋ぐ境界部107までを多孔質保護層13にて被覆してなる点で大きく異なる。従って、変形例に係る積層型ガスセンサ素子20のうち、上記実施例の積層型ガスセンサ素子1と同様の部分については説明を省略することにする。
(Modification)
Next, a laminated gas sensor element 20 according to a modification of the above-described embodiment and a gas sensor 5 incorporating the same will be described with reference to FIGS. FIG. 11 is a perspective view of the multilayer gas sensor element 20 according to the present modification, and FIG. 12 is a plan view of the multilayer gas sensor element 20 (a diagram when viewed from above in FIG. 11).
The laminated gas sensor element 20 according to the present modification includes an end body 101 including a detection unit, signal extraction terminal pads 1141 and 1142, and a heater energization terminal in an element body in which the detection element 11 and the ceramic heater 12 are stacked. Between the rear end portion 105 where a pad (not shown) is formed, an intermediate portion 103 whose width dimension gradually increases from the front end portion 101 toward the rear end portion 105 is provided, and both side surfaces of the front end portion 101 are added. The difference is that the porous protective layer 13 covers the boundary portion 107 connecting the side surface along the stacking direction of the intermediate portion 103 and the side surface of the tip portion 101. Therefore, in the multilayer gas sensor element 20 according to the modification, the description of the same parts as those of the multilayer gas sensor element 1 of the above embodiment will be omitted.

本変形例に係る積層型ガスセンサ素子20は、検出素子11とセラミックヒータ12とを積層してなる素子本体を有するものであり、上述したように、先端部101と後端部105との間に、先端部101から後端部105に向けて徐々に幅寸法が大きくなる中間部103を有している。そして、図11及び図12に示すように、積層型ガスセンサ素子20の素子本体の積層方向に沿った両側面のうち、先端部101の先端から中間部103の途中の位置まで多孔質保護層13が形成されている。なお、多孔質保護層13は、上記実施例のように、第1多孔質層131と第2多孔質132の2層構造をなしている。また、多孔質保護層13は、素子本体の表裏面及び先端面にも形成されている。そのため、積層型ガスセンサ素子20のうち、検出部を含む先端部101の積層方向に沿った断面をとったときには、上記実施例の図2に示したように断面構造と類似した断面を呈するものとなる。但し、本変形例では、図12に示すように、素子本体の先端部101の幅寸法と、その先端部101の両側面を被覆する多孔質保護層13の厚みとを合計した寸法Cが、素子本体の残余の部分における最大の幅寸法(即ち、後端部105の幅寸法)Dよりも小さくなっている。   The multilayer gas sensor element 20 according to this modification has an element body formed by laminating the detection element 11 and the ceramic heater 12, and as described above, between the front end portion 101 and the rear end portion 105. The intermediate portion 103 has a width dimension that gradually increases from the front end portion 101 toward the rear end portion 105. As shown in FIGS. 11 and 12, the porous protective layer 13 extends from the tip of the tip 101 to the middle of the intermediate portion 103 on both side surfaces along the stacking direction of the element body of the multilayer gas sensor element 20. Is formed. The porous protective layer 13 has a two-layer structure of a first porous layer 131 and a second porous 132 as in the above embodiment. The porous protective layer 13 is also formed on the front and back surfaces and the front end surface of the element body. Therefore, when the cross section along the stacking direction of the tip portion 101 including the detection portion of the stacked gas sensor element 20 is taken, it exhibits a cross section similar to the cross-sectional structure as shown in FIG. Become. However, in this modification, as shown in FIG. 12, the total dimension C of the width dimension of the tip portion 101 of the element body and the thickness of the porous protective layer 13 covering both side surfaces of the tip portion 101 is It is smaller than the maximum width dimension (that is, the width dimension of the rear end portion 105) D in the remaining portion of the element body.

また、本変形例に係る積層型ガスセンサ素子20は、多孔質保護層13が上述したように、素子本体の先端部101の側面と中間部103の側面とを繋ぐ境界部107を被覆している(図12参照)が、多孔質保護層13のうち、境界部107の位置における厚みEが、先端部101の側面の位置における厚みFよりも厚く形成されている。   Further, in the multilayer gas sensor element 20 according to this modification, the porous protective layer 13 covers the boundary portion 107 that connects the side surface of the tip portion 101 and the side surface of the intermediate portion 103 as described above. In the porous protective layer 13, the thickness E at the position of the boundary portion 107 is thicker than the thickness F at the position of the side surface of the tip portion 101 (see FIG. 12).

なお、本変形例に係る積層型ガスセンサ素子20においても、基本的に上記実施例に係る積層型ガスセンサ素子1と同様の製造工程を経て作製することができる。但し、上記した(6)貫通孔形成工程における貫通孔形状や(8)分離工程における切断パターンなどは、変形例に係る積層型ガスセンサ素子20の形態をなすように適宜変更するものとする。また、変形例に係る積層型ガスセンサ素子20の製造時には、上記の(10)第2多孔質層形成工程においても、第2多孔質層132形成後に、素子本体の先端部101の幅寸法と多孔質保護層13の厚みとを合計した寸法Cが、素子本体の後端部105の幅寸法Dを下回るように同工程を適宜変更している。具体的には、第2多孔質層形成工程では、第2多孔質層1312をなすペーストの厚みを事前に調整して塗布したり、第2多孔質層形成後に適宜研磨を施したりして、適宜多孔質保護層13の厚みを調整するようにしている。   Note that the multilayer gas sensor element 20 according to this modification can also be manufactured through the same manufacturing process as that of the multilayer gas sensor element 1 according to the above embodiment. However, the shape of the through-hole in the above-described (6) through-hole forming step and (8) the cutting pattern in the separation step are appropriately changed so as to form the stacked gas sensor element 20 according to the modification. Further, when the multilayer gas sensor element 20 according to the modification is manufactured, the width dimension and the porosity of the tip 101 of the element body are formed after the second porous layer 132 is formed also in the above (10) second porous layer forming step. The same process is appropriately changed so that the total dimension C of the thickness of the quality protective layer 13 is less than the width dimension D of the rear end portion 105 of the element body. Specifically, in the second porous layer forming step, the thickness of the paste forming the second porous layer 1312 is adjusted in advance and applied, or after the second porous layer is formed, polishing is appropriately performed, The thickness of the porous protective layer 13 is adjusted as appropriate.

ついで、本変形例に係る積層型ガスセンサ素子20を組み込んだガスセンサ500について説明する。本変形例に係るガスセンサ50は、図13に示すように、上記積層型ガスセンサ素子20における素子本体の中間部103の両側面が、ハウジング52内に設置されるセラミックホルダ61のホルダ側係合部65に係合されることで、積層型ガスセンサ素子20がセラミックホルダ61の内側に位置決めされている。そして、このセラミックホルダ61をハウジング52のハウジング側係合部526に係合されることで、積層型ガスセンサ素子20は、検出部を含む先端部101を突き出すようにしてハウジングの内側に位置決めされている。つまり、本変形例のガスセンサ50では、上記実施例のガスセンサ5のように、積層型ガスセンサ素子1がガラスシールによってハウジング52の所定の位置に保持させるのではなく、セラミックホルダ61を用いて位置決めしている。なお、セラミックホルダ61の後方側であって、ハウジング52の内側には結晶化ガラスを主体とする充填層63が設けられている。また、外筒51やリード線54の構成については、上記実施例に係るガスセンサ5と同様と同様である。   Next, a gas sensor 500 incorporating the laminated gas sensor element 20 according to this modification will be described. As shown in FIG. 13, the gas sensor 50 according to the present modification includes holder side engaging portions of the ceramic holder 61 in which both side surfaces of the intermediate portion 103 of the element body in the stacked gas sensor element 20 are installed in the housing 52. The laminated gas sensor element 20 is positioned inside the ceramic holder 61 by being engaged with 65. Then, by engaging the ceramic holder 61 with the housing side engaging portion 526 of the housing 52, the stacked gas sensor element 20 is positioned inside the housing so as to protrude the tip portion 101 including the detecting portion. Yes. That is, in the gas sensor 50 of the present modification, the laminated gas sensor element 1 is not held at a predetermined position of the housing 52 by the glass seal as in the gas sensor 5 of the above embodiment, but is positioned using the ceramic holder 61. ing. A filling layer 63 mainly composed of crystallized glass is provided behind the ceramic holder 61 and inside the housing 52. The configuration of the outer cylinder 51 and the lead wire 54 is the same as that of the gas sensor 5 according to the above embodiment.

ところで、本変形例に係るガスセンサ50では、上述したように、積層型ガスセンサ素子20における素子本体の中間部013の両側面をホルダ側係合部65に係合させる構成を採用するものであるため、積層型ガスセンサ素子20に形成される多孔質保護層13は、素子本体の先端部101の側面と中間部103の側面とを繋ぐ境界部107を覆うように形成される一方、中間部103の側面のうちホルダ側係合部に係合する部位(位置)からは離間するように形成されている。つまり、積層型ガスセンサ素子20の素子本体における中間部103の両側面のうち、多孔質保護層13が被覆されていない部分をセラミックホルダ61のホルダ側係合部65に係合させているのである。このように素子本体における中間部103の両側面のうち多孔質保護層13が形成されていない部位をホルダ側係合部65に係合させることで、積層型ガスセンサ素子2の外面とセラミックホルダ61の内面(ホルダ側係合部65の内面)とを密着して接触させることができ、多孔質保護層13の内部を通過してハウジング51内に排気ガスや水滴が侵入するのを確実に抑制することができ、信頼性の高いガスセンサ50とすることができる。   By the way, in the gas sensor 50 according to the present modification, as described above, a configuration is adopted in which both side surfaces of the intermediate portion 013 of the element body in the stacked gas sensor element 20 are engaged with the holder side engaging portion 65. The porous protective layer 13 formed on the stacked gas sensor element 20 is formed so as to cover the boundary portion 107 that connects the side surface of the tip portion 101 of the element body and the side surface of the intermediate portion 103, while It forms so that it may space apart from the site | part (position) engaged with the holder side engaging part among side surfaces. In other words, the portions of the element body of the multilayer gas sensor element 20 that are not covered with the porous protective layer 13 are engaged with the holder-side engaging portion 65 of the ceramic holder 61 in both side surfaces of the intermediate portion 103. . As described above, by engaging the portions on both sides of the intermediate portion 103 in the element main body where the porous protective layer 13 is not formed with the holder-side engaging portion 65, the outer surface of the multilayer gas sensor element 2 and the ceramic holder 61. The inner surface (the inner surface of the holder-side engagement portion 65) can be brought into close contact with each other, and the passage of exhaust gas and water droplets into the housing 51 through the inside of the porous protective layer 13 is reliably suppressed. The gas sensor 50 can be made highly reliable.

以上において、本発明を実施例及び変形例に即して説明したが、本発明は上記実施例等に限定されるものではなく、その要旨を逸脱しない範囲で、適宜変更して適用できることはいうまでもない。
例えば、上記実施例等では、酸素センサ及びそれに用いる積層型ガスセンサ素子について説明しているが、酸素センサ以外のガスセンサ、例えば、一酸化炭素センサ、NOxセンサ等の各種のガスセンサ及びそれに用いる積層型ガスセンサ素子にも本発明を適用することができる。
In the above, the present invention has been described with reference to the embodiments and the modified examples. However, the present invention is not limited to the above-described embodiments and the like, and it can be applied as appropriate without departing from the gist thereof. Not too long.
For example, in the above-described embodiments and the like, the oxygen sensor and the stacked gas sensor element used therefor have been described. However, gas sensors other than the oxygen sensor, for example, various gas sensors such as a carbon monoxide sensor and a NOx sensor, and the stacked gas sensor used therefor. The present invention can also be applied to elements.

また、上記実施例等では、第1多孔質層と第2多孔質層の2層を形成したものであったが、第1多孔質層のみを形成した積層型ガスセンサ素子としてもよい。さらに、第2多孔質層を形成するにあたって上記実施例では、第2多孔質層となるペーストを用いつつ熱処理を経て第2多孔質層を形成したが、第1多孔質層が形成された素子本体の一端部の周囲全体に対して溶射を行うことで第2多孔質層を形成してもよい。   Moreover, in the said Example etc., although the two layers of the 1st porous layer and the 2nd porous layer were formed, it is good also as a laminated | stacked gas sensor element in which only the 1st porous layer was formed. Further, in forming the second porous layer, in the above embodiment, the second porous layer is formed through the heat treatment while using the paste that becomes the second porous layer, but the element in which the first porous layer is formed. You may form a 2nd porous layer by spraying with respect to the whole circumference | surroundings of the one end part of a main body.

実施例の積層型酸素センサ素子の外観を模式的に示す斜視図である。It is a perspective view which shows typically the external appearance of the laminated | stacked oxygen sensor element of an Example. 検出部を含む先端部に、第1多孔質層と第2多孔質層とからなる多孔質保護層が形成されている図1の積層型酸素センサ素子の横断面を示す模式図である。It is a schematic diagram which shows the cross section of the laminated | stacked oxygen sensor element of FIG. 1 in which the porous protective layer which consists of a 1st porous layer and a 2nd porous layer is formed in the front-end | tip part containing a detection part. 実施例の積層型酸素センサ素子の分解斜視図である。It is a disassembled perspective view of the lamination type oxygen sensor element of an Example. 未焼成シート積層体に形成される貫通孔の位置を説明するための平面図である。It is a top view for demonstrating the position of the through-hole formed in a non-baking sheet laminated body. 図4のA−A‘における断面図である。It is sectional drawing in AA 'of FIG. 充填工程を説明するための模式図である。It is a schematic diagram for demonstrating a filling process. 図6における未焼成シート積層体の貫通孔や離型材等の一部を拡大して示す断面図である。It is sectional drawing which expands and shows some through holes, a mold release material, etc. of the unbaking sheet | seat laminated body in FIG. 離型材の構成を説明するための模式図(断面図)である。It is a schematic diagram (sectional drawing) for demonstrating the structure of a mold release material. 1枚の未焼成シート積層体に32個の未焼成素子となる個片が形成されている様子を模式的に示す平面図である。It is a top view which shows typically a mode that the piece which becomes 32 unfired elements is formed in the unfired sheet laminated body of 1 sheet. 実施例のガスセンサ(酸素センサ)の構造を示す模式的な全体断面図である。It is a typical whole sectional view showing the structure of the gas sensor (oxygen sensor) of an example. 変形例の積層型ガスセンサ素子の外観を模式的に示す斜視図である。It is a perspective view which shows typically the external appearance of the multilayer gas sensor element of a modification. 変形例の積層型ガスセンサ素子を検出素子側から見たときの平面図である。It is a top view when the laminated | stacked type gas sensor element of a modification is seen from the detection element side. 変形例のガスセンサ(酸素センサ)の構造を示す模式的な全体断面図である。It is a typical whole sectional view showing the structure of the gas sensor (oxygen sensor) of a modification.

符号の説明Explanation of symbols

1,20・・・積層型ガスセンサ素子(積層型酸素センサ素子)、11・・・検出素子、111・・・固体電解質層、112・・・検知電極、113・・・基準電極、1141,1142;信号取り出し用端子パッド、116・・・電極保護層、12・・・セラミックヒータ、121・・・発熱抵抗体、122・・・第1アルミナ層、123・・・第2アルミナ層、1241,1242・・・ヒータ通電用端子パッド、13・・・多孔質保護層(多孔質層)、131・・・第1多孔質層、132・・・第2多孔質層、2・・・貫通孔、3・・・離型材、4・・・マスク、5,50・・・ガスセンサ(酸素センサ)、51;外筒、511;グロメット、52;ハウジング、101・・・先端部、103・・・中間部、105・・・後端部、107・・・境界部、61・・・セラミックホルダ、65・・・ホルダ側係合部。
DESCRIPTION OF SYMBOLS 1,20 ... Laminated gas sensor element (laminated oxygen sensor element), 11 ... Detection element, 111 ... Solid electrolyte layer, 112 ... Detection electrode, 113 ... Reference electrode, 1141, 1142 A signal extraction terminal pad, 116 ... an electrode protective layer, 12 ... a ceramic heater, 121 ... a heating resistor, 122 ... a first alumina layer, 123 ... a second alumina layer, 1241, 1242 ... Heater energization terminal pad, 13 ... Porous protective layer (porous layer), 131 ... First porous layer, 132 ... Second porous layer, 2 ... Through hole DESCRIPTION OF SYMBOLS 3 ... Release material, 4 ... Mask, 5,50 ... Gas sensor (oxygen sensor), 51; Outer cylinder, 511; Grommet, 52; Housing, 101 ... Tip part, 103 ... Middle part, 105 ... rear end part, 10 ... boundary, 61 ... ceramic holder, 65 ... holder-side engaging portion.

Claims (10)

セラミック基体の内部に発熱抵抗体を埋設したセラミックヒータと、該セラミックヒータに積層されるとともに、先端側に一対の電極を配設した検出部が形成された固体電解質層とを含む素子本体であって、長手方向に延びる板状をなす素子本体を備える積層型ガスセンサ素子において、
該素子本体は、上記検出部を含む先端部における長手方向及び積層方向に直交する向きの幅寸法が、残余の部位の前記幅寸法よりも小さくなっており、上記素子本体のうち少なくとも上記先端部の上記積層方向に沿った両側面が多孔質層により被覆されている
ことを特徴とする積層型ガスセンサ素子。
An element body including a ceramic heater in which a heating resistor is embedded inside a ceramic substrate, and a solid electrolyte layer formed on the ceramic heater and having a detection portion in which a pair of electrodes are disposed on the tip side. In the laminated gas sensor element comprising a plate-shaped element body extending in the longitudinal direction,
The element body has a width dimension in a direction orthogonal to a longitudinal direction and a stacking direction at a tip part including the detection part, which is smaller than the width dimension of a remaining part, and at least the tip part of the element body A laminated gas sensor element characterized in that both side surfaces along the laminating direction are covered with a porous layer.
上記素子本体は、上記一対の検知電極及び上記発熱抵抗体と電気的に接続される複数の電極端子部が外表面に露出した後端部と、上記先端部と上記後端部との間に位置し、該先端部から該後端部に向けて徐々に上記幅寸法が大きくなる中間部とを有し、上記多孔質層は、上記先端部の両側面に加え、上記中間部の上記積層方向に沿った側面と上記先端部の側面とを繋ぐ境界部までを被覆してなる請求項1に記載の積層型ガスセンサ素子。   The element body includes a rear end portion where a plurality of electrode terminal portions electrically connected to the pair of detection electrodes and the heating resistor are exposed on an outer surface, and a gap between the front end portion and the rear end portion. And an intermediate portion that gradually increases in the width dimension from the front end portion toward the rear end portion, and the porous layer is added to both side surfaces of the front end portion and the laminated portion of the intermediate portion. The stacked gas sensor element according to claim 1, wherein the laminated gas sensor element is covered up to a boundary portion connecting a side surface along the direction and a side surface of the tip portion. 上記多孔質層のうち、上記境界部の位置における厚みが上記先端部の側面の位置における厚みよりも厚い請求項2に記載の積層型ガスセンサ素子。   The multilayer gas sensor element according to claim 2, wherein, in the porous layer, the thickness at the boundary portion is thicker than the thickness at the side surface of the tip portion. 上記素子本体の前記先端部の前記幅寸法と、該先端部の上記両側面を被覆する上記多孔質層の厚みとを合計した寸法が、上記素子本体の上記残余の部位における最大の上記幅寸法以下である請求項1〜請求項3のいずれか1項に記載の積層型ガスセンサ素子。   The maximum dimension of the width of the remaining part of the element body is the sum of the width dimension of the tip part of the element body and the thickness of the porous layer covering the both side surfaces of the tip part. The multilayer gas sensor element according to any one of claims 1 to 3, which is the following. 上記素子本体の上記先端部の上記幅寸法をA(単位:mm)、上記発熱抵抗体のうちで該先端部に位置する部位の最大の前記幅寸法をB(単位:mm)としたときに、A×0.60<B<A×0.98の関係を満たす請求項1〜請求項4のいずれか1項に記載の積層型ガスセンサ素子。   When the width dimension of the tip portion of the element body is A (unit: mm) and the maximum width dimension of the portion of the heating resistor located at the tip portion is B (unit: mm) The laminated gas sensor element according to any one of claims 1 to 4, wherein A × 0.60 <B <A × 0.98 is satisfied. 上記多孔質層は、上記素子本体のうち少なくとも上記先端部の両側面を被覆する第1多孔質層と、該第1多孔質層が形成された上記素子本体の上記先端部の周囲を覆う第2多孔質層とを有する請求項1〜請求項5のいずれか1項に記載の積層型ガスセンサ素子。   The porous layer includes a first porous layer that covers at least both side surfaces of the tip portion of the element body, and a first cover that covers the periphery of the tip portion of the element body on which the first porous layer is formed. The laminated gas sensor element according to any one of claims 1 to 5, comprising two porous layers. 上記多孔質層は、上記素子本体のうち上記先端部の両側面を含む当該先端部の周囲を覆うように形成されており、上記素子本体の角部からの上記多孔質層の厚みが20μm以上である請求項1〜6のいずれか1項に記載の積層型ガスセンサ素子。   The porous layer is formed so as to cover the periphery of the tip portion including both side surfaces of the tip portion of the element body, and the thickness of the porous layer from the corner portion of the element body is 20 μm or more. The stacked gas sensor element according to any one of claims 1 to 6. 上記多孔質層は、空孔率が15%〜65%の範囲内にある請求項1〜請求項7のいずれか1項に記載の積層型ガスセンサ素子。   The multilayer gas sensor element according to any one of claims 1 to 7, wherein the porous layer has a porosity in a range of 15% to 65%. 請求項1〜請求項8のいずれか1項に記載の積層型ガスセンサ素子と、
前記検出部を先端から突き出させた状態で、前記積層型ガスセンサ素子の周方向を取り囲む筒状のハウジングと、を備えることを特徴とするガスセンサ。
The laminated gas sensor element according to any one of claims 1 to 8,
A gas sensor comprising: a cylindrical housing that surrounds a circumferential direction of the stacked gas sensor element in a state where the detection unit protrudes from a tip.
請求項2または請求項3に記載の積層型ガスセンサ素子と、
前記検出部を先端から突き出させた状態で、前記積層型ガスセンサ素子の周方向を取り囲む筒状のハウジングと、
前記積層型ガスセンサ素子と前記ハウジングとの間に配置される絶縁性セラミックホルダと、備え、
前記積層型ガスセンサ素子は、前記素子本体における前記中間部の前記両側面の後方側が前記セラミックホルダに設けたホルダ側係合部に係合されることで、該セラミックホルダの内側に位置決めされており、前記多孔質層は、前記中間部の前記両側面のうち前記ホルダ側係合部に係合する部位から離間して形成されていることを特徴とするガスセンサ。
The laminated gas sensor element according to claim 2 or 3,
A cylindrical housing that surrounds the circumferential direction of the stacked gas sensor element in a state in which the detection unit protrudes from the tip.
An insulating ceramic holder disposed between the laminated gas sensor element and the housing;
The laminated gas sensor element is positioned on the inner side of the ceramic holder by engaging the rear side of the both side surfaces of the intermediate portion of the element body with a holder side engaging portion provided in the ceramic holder. The gas sensor is characterized in that the porous layer is formed apart from a portion of the both side surfaces of the intermediate portion that engages with the holder side engaging portion.
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