JP2004144679A

JP2004144679A - Gas sensor and gas alarm using the same

Info

Publication number: JP2004144679A
Application number: JP2002311734A
Authority: JP
Inventors: Hisao Onishi; 大西　久男; Takeshi Hashimoto; 橋本　猛; Yasuharu Dangi; 談議　康晴
Original assignee: Osaka Gas Co Ltd
Current assignee: Osaka Gas Co Ltd
Priority date: 2002-10-25
Filing date: 2002-10-25
Publication date: 2004-05-20
Anticipated expiration: 2022-10-25
Also published as: JP3890007B2

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the time for inspecting a gas sensor and to make inspection work more efficient. <P>SOLUTION: This gas sensor is equipped with a first housing 5, a second housing 6, an intermediate chamber 7, a first vent 8 provided in the first housing 5 so that gas can circulate between the interior of the first housing 5 and the intermediate chamber 7, a second vent 9 provided in the second housing 6 so that gas can circulate between the intermediate chamber 7 and the exterior of the second housing 6, a gas detection element 1 provided in the first housing 5 for reacting to a gas to be detected and to inspection gas, an adsorption layer 3 on the second vent 9 so as to adsorb gases other than the gas to be detected, and an inspection gas lead-in hole 4 provided in the housing 6 so that the inspection gas can be injected into the intermediate chamber 7 from the exterior of the second housing 6 in addition to the second vent 9. The lead-in hole 4 is given directivity so that the inspection gas injected through the lead-in hole 4 is led to the first vent 8. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、ガス警報器等に搭載されるガスセンサーに関し、特に検知対象ガス以外のガスに対して感度を抑制するためにハウジング内部に活性炭等の吸着層を有するガスセンサーにおいて、吸着層に吸着される検知対象ガス以外のガスを点検ガスとして使用するガスセンサーの改良に関するものである。
【０００２】
【従来の技術】
一般にガスセンサーは、その目的から、検査対象ガスのみを検知し、検知対象以外のガスは検知しない性能が望まれる。しかし、一般的に可燃性ガスを検知するガス検知素子は同種の可燃性ガスに対しても感度を持っており、例えばメタンガスを検出するメタン検知素子は、同じ炭化水素系のガスであるブタンガス、プロパンガスにも感度を持つ。
【０００３】
検査対象以外のガスにも感度を持つガスセンサーの、検知対象以外のガスの感度を低減する方法として、検知対象以外のガスを吸着する活性炭等の吸着層をガス検知素子と外気との間に設ける構造が利用されている。この構造によると、検知対象ガス（例えばメタンガス）は吸着層に吸着されず、ガス検知素子に到達し、ガス検知素子は検知対象ガスを検知でき、検知対象以外のガス（アルコール、プロパンガス、ブタンガス等）は吸着層に吸着され、ガス検知素子に到達する検知対象ガスが抑制されることにより、ガス検知素子は検知対象以外のガスを検知しにくく、誤報が少ない。
【０００４】
しかし上記のメリットがある一方、検知対象ガス以外は吸着層に吸着されるため、ガスセンサーの動作を点検するために点検ガスをかける場合は、点検ガスとして検知対象ガスを用いなければならない。例えば、検知対象ガスがメタンガスの場合、メタンは常温で液化が困難であり、高圧にしても運搬できる容積にすると、通常のスプレー缶で５リットル程度が限界である。一方、ブタンは容易に液化できるため、携帯性がよく、メタンに対し数十分の１〜数百分の１の容積で持ち運びが可能であり、市販されているライター程度の大きさで、スプレー缶１本に相当するメタンガス以上の回数の点検が可能であるためブタンガスによる点検が望まれていた。
【０００５】
このような検知対象以外のガスに対する感度を抑制しつつ、検査対象以外のガスによる点検を可能とする技術としては次のものがある。
【０００６】
その一例としては、図１３に示すように金属酸化物半導体のようなガス検知素子１を設置したベース２に樹脂製のハウジングａをガス検知素子１がハウジングａ内に内装されるように被せ、ハウジングａにハウジングａ内とハウジングａ外とを連通させる通気孔ｂを設け、通気孔ｂに検知対象以外のガスを吸着する吸着層３を設け、ハウジングａ内で防爆用構造材として金属メッシュ籠ｃをガス検知素子１を覆うように被せ、点検するとき点検ガスをハウジングａ内に注入するための点検ガス導入孔４を設けたものがある（例えば、特許文献１参照）。なお、点検ガスの注入とは点検ガスを加圧または運動エネルギーを与えて流通させる等により積極的に流入せしめることである。
【０００７】
また他例としては、図１４に示すようにガス検知素子１を設置したベース２に金属製の第１ハウジング５をガス検知素子１が内装されるように被せ、第１ハウジング５の外に樹脂製等の第２ハウジング６を被せ、第１のハウジング５と第２ハウジング６間に中間室７を形成し、第１ハウジング５に第１ハウジング５内と中間室７内とを連通させる第１通気孔８を設け、第２ハウジング６に第２ハウジング６外と中間室７とを連通させる第２通気孔９を設け、第２通気孔９に検知対象以外のガスを吸着する吸着層３を装着し、第１通気孔９に防爆構造材としての金属メッシュ板１０を装着し、点検するとき点検ガスを第２ハウジング６内に注入するための点検ガス導入孔４を設けたものがある。
【０００８】
また上記のようなガスセンサーをガス警報器に搭載した状態で点検ガス導入孔４に点検ガスを導入するため、図１５に示すようにガス警報器本体にガス導入管１１を設け、このガス導入管１１の一端をガス導入孔４に臨ませ、ガス警報器本体の外に位置するガス導入管１１の他端からボンベ等で点検ガスを矢印ｅのように送入するようにしたものがある（例えば、特許文献２参照）。
【０００９】
【特許文献１】
特許第３１７１７３３号公報
【特許文献２】
特許第３１９７４０９号公報
一方、ガスセンサーのもう一つの課題として、小型化がある。昨今、ガスセンサーを搭載する機器（例えばガス警報器）は、小型化が求められている。
【００１０】
半導体式のガス検知素子は、電力により加熱することで数百度に加熱し、加熱により可燃性ガスに対して感度を持つ。そして、この温度に燃焼濃度範囲のガスが接触すれば着火するおそれがあるため、ガス検知素子のある室と外部とは燃焼が伝達しないように防爆構造とする必要がある。
【００１１】
一般的に防爆構造は、有効通気面積を管理した金属メッシュにより構成される。ガスセンサーの大きさを小型化するためには、このメッシュ部分の面積を小さくすることが望ましい。
【００１２】
金属メッシュの防爆構造の例として、図１３の例にあるようにガス検知素子１の周囲を金属メッシュ籠ｃにより構成する方法が挙げられるが、金属メッシュを小型の有底筒状に精度よく成形することは困難であり、この構造による小型化は困難であった（この構造の場合、ハウジングａの外径が１５ｍｍφ程度と大きかった）。
【００１３】
これを解決する技術として図１４の例の構造のものが提案されている。この場合、第１ハウジング５を金属板でキャップ形状にすること（小型でも容易に成形できる）と、第１通気孔８の部分に金属メッシュ板を設けることにより防爆性と小型化が図られている（この構造の場合、第２ハウジング６の外径が６〜８ｍｍφ程度と小型化できた）。またこの構造では点検ガスを導入する点検ガス導入孔４は防爆構造を形成する第１ハウジング５には設けられず、第２ハウジング６に設ける必要がある。
【００１４】
またハウジングの通気孔は検知対象以外のガスの感度を抑制する目的で、流量制限通気孔といったものを設けるという例（例えば、特許文献３参照）があるように通気孔の開口面積は検知対象ガスの検知性能に影響のない範囲でより小さくしたものがある。
【００１５】
【特許文献３】
特許第３１７１７２０号公報
この結果、第１ハウジング５が第１通気孔８のある金属板製のキャップで形成されることにより第２ハウジング６の点検ガス導入孔４から注入された点検ガスが第２ハウジング６に充満した後、第１ハウジング５の内部に到達することとなり、ガス検知素子１に点検ガスを到達させるためには、第２ハウジング６の内部に充満させるガス量が必要となり、また充満させる時間がかかることから、点検ガス圧入開始から、ガス検知素子１が点検ガスに対して感度を持つまで時間がかかる。
【００１６】
またガス検知素子１に点検ガスが到達し、ガス検知素子１が点検ガスの感度まで上昇する頃には、第２ハウジング６と第１ハウジング５の内部に点検ガスが充満した状態となり、点検ガスの圧入を止めた後も点検ガスが長時間第１ハウジング５の内部に留まり、ガス検知素子１の感度が低下するまで非常に長時間かかるという問題があった。
【００１７】
また第２ハウジング６に吸着層３があるため、第２ハウジング６内に多量の点検ガスを圧入すると、点検ガスの一部が吸着層３に吸着され、点検ガスを止めた後、第２ハウジング６内部での点検ガスの濃度が低下し始めても、吸着層３からの点検ガスの放出が起こり、第２ハウジング６内に点検ガスを供給することにより長時間点検ガスの圧入を続けることと同じ状態が起こり、さらに長時間ガス検知素子１の感度が低下しないことになる。
【００１８】
【発明が解決しようとする課題】
上記のことにより、点検ガスによりガスセンサーを点検する場合、ガス検知素子が規定の感度になるまで時間がかかり、また規定の感度になった後に点検ガスの圧入を停止した後も、長時間規定の感度が出たままとなり、なかなか点検作業が終了できなかった。
【００１９】
またこのガスセンサーを搭載した機器（例えばガス警報器）は規定の感度になったことを警報で知らせるようにしているが、長時間この警報が鳴り止まないことから点検者やその周囲の人にとって利便性が悪いという問題がある。
【００２０】
本発明は上記の点に鑑みてなされたものであり、点検ガスによりガスセンサーの点検をする場合に規定の感度になるまでの時間を短縮し、また規定感度になった後に点検ガスの圧入を停止した後、規定の感度以下になる時間を短縮することにより、ガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができるガスセンサー及びそれを用いたガス警報器を提供することを課題とするものである。
【００２１】
【課題を解決するための手段】
上記課題を解決するための本発明のガスセンサーは、内部が中空の第１ハウジング５と、この第１ハウジング５を覆うように外に被せた第２ハウジング６と、第１ハウジング５と第２ハウジング６との間に形成された中間室７と、第１ハウジング５内と中間室７との間でガスが流通可能なように第１ハウジング５に設けた第１通気孔８と、中間室７と第２ハウジング６外部との間が流通可能なように第２ハウジング６に設けた第２通気孔９と、第１ハウジング５内に設けた検知対象ガス及び点検ガスに感応するガス検知素子１と、検知対象ガス以外のガスを吸着するように第２通気孔９に設けた吸着層３と、第２通気孔９とは別に第２ハウジング６外部から中間室７に点検ガスを注入可能なように第２ハウジング６に設けた点検ガス導入孔４とを備えたガスセンサーにおいて、点検ガス導入孔４から注入される点検ガスが第１通気孔８に誘導されるように点検ガス導入孔４に指向性を持たせたことを特徴とする。上記のように構成したことにより指向性を持たせた点検ガス導入孔４から点検ガスを第１通気孔８に誘導されるように注入できて第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができるものであって、ガスセンサーの点検をする場合に規定の感度になるまでの時間を短縮できると共に規定感度になった後に点検ガスの注入を停止した後、規定の感度以下になる時間を短縮することができ、ガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００２２】
また点検ガス導入孔４から注入された点検ガスが第１ハウジング５内に誘引されるようにガイドする誘引ガイド部１２を第１通気孔８に設けたことを特徴とすることも好ましい。この場合も、点検ガス導入孔４から注入された点検ガスが誘引ガイド部１２にて第１通気孔８に誘引され、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができるものであって、上記と同様にガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００２３】
また第１ハウジング５に複数個の第１通気孔８を設けたことを特徴とすることも好ましい。点検ガス導入孔４から点検ガスを注入したとき第１ハウジング５に対して流入する流れが生じる第１通気孔８と第１ハウジング５から流出を生じる第１通気孔８とができるために流通がしやすくなって第１ハウジング５内に点検ガスが流入しやすくなり、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができるものであって、上記と同様にガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００２４】
また第１通気孔８の断面形状が点検ガス導入孔４から注入される点検ガスの流れと平行な方向に長くなるように異方性を持たせたことを特徴とすることも好ましい。この場合も、点検ガス導入孔４から点検ガスを注入したとき点検ガスの流れと平行な方向に長くなるように形成された異方性のある第１通気孔８から第１ハウジング５内に点検ガスが流入しやすくなり、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができるものであって、上記と同様にガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００２５】
また第１通気孔８が第２ハウジング６の内側側面の近傍に位置するように偏心させた位置に設けたことを特徴とすることも好ましいものである。この場合も、点検ガス導入孔４から点検ガスを注入して点検ガスが第２ハウジング６内の壁面に沿って流れた際、壁面に沿った流れの点検ガスが第２ハウジング６の内側側面近傍に位置するように偏心した第１通気孔８から第１ハウジング５内に流入しやすくなり、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができるものであって、上記と同様にガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００２６】
また点検ガス導入孔４から注入される点検ガスが第２ハウジング６の内側側面に沿って周方向に流動するように点検ガスを誘導する構造にしたことを特徴とすることも好ましい。この場合も点検ガス導入孔４から注入された点検ガスが第２ハウジング６の内側側面に沿って周方向に流動して点検ガスが第１通気孔８に導かれ、第１通気孔８付近の点検ガスの流動が比較的大きくなるため第１通気孔８から第１ハウジング５内に流入しやすくなり、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができるものであって、上記と同様にガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００２７】
また点検ガス導入孔４から注入された点検ガスが吸着層３に流入するのを抑制する流入抑制手段１３を設けたことを特徴とすることも好ましい。この場合、点検ガスが吸着層３に吸着されるのを防止でき、点検ガスの注入を停止した後、規定の感度以下になる時間を短縮することができてガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００２８】
また、前記ガスセンサーの第１通気孔８にガス流通制限手段を設けることも好ましい。第１通気孔８にガス流通制限手段を設けることにより、検知対象ガスに対する選択性が得られることは知られている（例えば、前記特許文献３参照）が、点検ガスも同様に流入が制限されてしまうため、点検ガスのガス検知素子１への到達が遅くなり、点検時間が長くなってしまうという問題があった。しかし、前記の点検時間の短縮化及び点検作業の効率化が図られたガスセンサーの第１通気孔８にガス流通制限手段を設けることにより、検知対象ガスに対する選択性の向上と、点検時間の短縮化が両立できる。
【００２９】
また上記ガスセンサーをガス警報器本体１４に搭載してガス警報器を形成することを特徴とすることも好ましい。この場合、ガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができるガス警報器を得ることができる。
【００３０】
【発明の実施の形態】
先ず、図１に示す実施の形態の例から述べる。円盤状のベース２には検査対象ガスと点検ガスを感知し得るガス検知素子１を設置してあり、このベース２には有底筒状の第１ハウジング５を被せて装着してあり、第１ハウジング５内にガス検知素子１を内装してある。この第１ハウジング５は金属板を有底筒状に成形して形成されている。第２ハウジング６は樹脂等で有底筒状に形成されており、第１ハウジング５の上に第２ハウジング６を被せるように装着してある。第２ハウジング６と第１ハウジング５との間には中間室７を形成してある。第１ハウジング５には第１ハウジング５内と中間室７とを連通させる第１通気孔８を形成してあり、この第１通気孔８には防爆構造材としての金属メッシュ板１０を装着してある。第２ハウジング６には第２ハウジング６の外部と中間室７とを連通させる第２通気孔９を穿孔してあり、検知対象以外のガスを吸着する吸着層３を中間室７側で第２通気孔９に装着してある。第２ハウジング６には点検ガスを注入するための点検ガス導入孔４を第２ハウジング６の外部と中間室７とを連通させるように設けてある。この点検ガス導入孔４は本例では第１通気孔８に向かうように指向性を持たせてある。このように構成せるガスセンサーは、金属にて形成せる第１ハウジング６と第１通気孔８に装着した金属メッシュ板１０で防爆を図るものであるため第２ハウジング６の外径が６〜８ｍｍ程度と小型化できる。
【００３１】
ガスセンサーの点検を行う際には点検ガス導入孔４から点検ガスを中間室７内に注入するが、点検ガス導入孔４に指向性を持たせてあるため点検ガス導入孔４から点検ガスを第１通気孔８に誘導されるように注入できる。これにより、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができる。これによりガスセンサーの点検をする場合に規定の感度になるまでの時間を短縮できると共に規定感度になった後に点検ガスの圧入を停止した後、注入している点検ガスの量も少ないので規定の感度以下になる時間を短縮することができる。
【００３２】
また、金属メッシュ板１０は、ガス流通制限手段を兼用しており、点検ガスを注入した際は、点検ガスが第１通気孔８を移動可能であるが、普段の検知時は対流による第１通気孔８の移動は制限し、拡散による検知対象ガスの移動は可能である。
【００３３】
なお、検知対象ガスは第２ハウジング６の第２通気孔９を通して拡散により中間室７に移動するため点検ガス導入孔４の指向性に影響を受けることはなく、検知性能は変わらない。
【００３４】
次に図２に示す実施の形態の例について述べる。本例も上記例と基本的に同じであり、同じものには同じ符号を付して説明を省略し、異なる点だけを主に述べる。本例の場合、上記の例のように点検ガス導入孔４に指向性を持たせる代わりに、点検ガス導入孔４から注入された点検ガスが第１ハウジング５内に誘引されるようにガイドする誘引ガイド部１２を第１通気孔８に設けてある。つまり、注入された点検ガスを受けて第１通気孔８に導く形状の誘引ガイド部１２を設けてある。
【００３５】
ガスセンサーの点検を行うために点検ガス導入孔４から圧入された点検ガスが誘引ガイド部１２にて第１通気孔８に誘引され、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができる。この場合、第１通気孔８の部分の形状が変わっても第１通気孔８の開口面積が変わらなければ、防爆性を維持しながら点検性は向上する。
【００３６】
なお、検知対象ガスは第２ハウジング６の第２通気孔９を通して拡散により中間室７に移動するため誘引ガイド部１２が設けられていても第１通気孔８の開口面積が変わらなければ、検知性能は変わらない。
【００３７】
次に図３に示す実施の形態の例について述べる。本例も上記例と基本的に同じであり、同じものには同じ符号を付して説明を省略し、異なる点だけを主に述べる。本例の場合、第１ハウジング５に第１通気孔８を設けるとき、複数の第１通気孔８を間隔を隔てて設けてある。図に示す例では２つの第１通気孔８ａ，８ｂを穿孔してある。この例の場合、開口面積が同一の１つの孔の第１通気孔に対して点検ガスの流通しやすくなる。つまり、ガス導入孔４から点検ガスを注入したとき第１ハウジング５に対して流入する流れが生じる第１通気孔８と第１ハウジング５から流出を生じる第１通気孔８とができるために流通がしやすくなって第１ハウジング５内に点検ガスが流入しやすくなり、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができる。
【００３８】
次に図４に示す実施の形態の例について述べる。本例も上記例と基本的に同じであり、同じものには同じ符号を付して説明を省略し、異なる点だけを主に述べる。本例の場合、第１通気孔８の断面形状が点検ガス導入孔４から注入される点検ガスの流れと平行な方向に長くなるように異方性を持たせてある。つまり点検ガスの流れの方向と平行な方向に長くなるように長孔状に形成してある。この場合、点検ガス導入孔４から点検ガスを圧入したとき点検ガスの流れと平行な方向に長くなるように形成された異方性のある第１通気孔８から第１ハウジング５内に点検ガスが流入しやすくなり、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができる。このとき、長孔状の第１通気孔８のアスペクト比は、１．５以上が望ましい。
【００３９】
次に図５に示す実施の形態の例について述べる。本例も上記例と基本的に同じであり、同じものには同じ符号を付して説明を省略し、異なる点だけを主に述べる。本例の場合、第１通気孔８を設けるとき第２ハウジング６の内側側面の近傍に位置するように偏心させた位置に設けてある。つまり、第１ハウジング５のセンターの位置に対して第２ハウジング６の内側側面の方に近付くように偏心させてある。またこのとき点検ガス導入口４と反対の方に偏心させることが望ましい。この場合、点検ガス導入孔４から点検ガスを第２ハウジング６内に注入したとき、
第２ハウジング６の内側側面である壁面に沿って流れ、この壁面に沿って流れた点検ガスが第１通気孔８の方に向かって流れて第１通気孔８から第１ハウジング５内に流入しやすくなり、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができる。
【００４０】
ここで、第２ハウジング６のセンターから第２ハウジング６の内側側面までの距離をＲ、上記センターから第１通気孔８までの距離をｒとしたとき、（ｒ／Ｒ）とガス検知素子１が感知するまでの時間との関係をグラフにすると図６に示すようになる。図６で縦軸に感知するまでの時間を示し、横軸に（ｒ／Ｒ）を示し、（ｒ／Ｒ）が大きくなる程感知するまでの時間が短くなる。（ｒ／Ｒ）＞０．１で感知するまでの時間が短くなる効果が表れ始め、（ｒ／Ｒ）＞０．２でより顕著に効果表れ、（ｒ／Ｒ）＞０．３とすることが望ましい。
【００４１】
次に図７に示す実施の形態の例について述べる。本例も上記例と基本的に同じであり、同じものには同じ符号を付して説明を省略し、異なる点だけを主に述べる。本例の場合、点検ガス導入孔４から注入される点検ガスが第２ハウジング６の内側側面に沿って周方向に流動するように点検ガスを誘導する構造にしてある。つまり、点検ガス導入孔４を斜め下方に向けると共に第２ハウジング６の内側側面の接線方向に近付くように傾斜させることにより、点検ガスが第２ハウジング６の内側側面に沿って周方向に流動するように点検ガスを誘導する構造にしてある。また第１通気孔８が第２ハウジング６の内側側面に近付く位置に偏心させて設けてある。
【００４２】
この場合、点検ガス導入孔４から注入された点検ガスが第２ハウジング６の内側側面に沿って周方向に流動して渦流が生じ、点検ガスが第１通気孔８に導かれ、第１通気孔８から第１ハウジング５内に流入しやすくなり、第２ハウジング６内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができる。
【００４３】
上記のように第２ハウジング６の内側側面に沿わせて渦巻き状に点検ガスを注入するとき、第１ハウジング５に設ける第１通気孔８を図８に示すような形状にすると一層点検ガスを導入しやすくなる。図８（ａ）に示すものでは、第１通気孔８を円弧状にして一対の第１通気孔８を対称の位置に設けてある。図８（ｂ）に示すものでは第１通気孔８に導入ガイド１５を設けてある。図８（ｃ）に示すものでは、周方向に複数（図示例では４個）の第１通気孔８を設けて各第１通気孔８に夫々導入ガイド１５を設けてある。
【００４４】
次に図９に示す実施の形態の例について述べる。本例も上記例と基本的に同じであり、同じものには同じ符号を付して説明を省略し、異なる点だけを主に述べる。本例の場合、点検ガス導入孔４から注入された点検ガスが吸着層３に流入するのを抑制する流入抑制手段１３を設けてある。つまり、吸着層３の下面に点検ガスが通過しない半円状や円環状の板を装着してある。この場合、点検ガスが吸着層３に吸着されるのを防止でき、点検ガスの注入を停止した後、規定の感度以下になる時間を短縮することにができる。すわなち、吸着層３に吸着された点検ガスが脱離により後でガス検知素子１に届き、感知が持続するようなことが抑えられ、点検性が向上する。なお、上記図９では図５に示す例のガスセンサーで流入抑制手段１３を設けたものについて述べたが、図１乃至図８のいずれの例のものでも同様に流入抑制手段１３を設けることができる。
【００４５】
また図１０は上記のようなガスセンサーをガス警報器本体１４内に組み込んでガス警報器を形成したものを示す。ガス警報器本体１４にはガス警報器本体１４の外部からガスセンサーの点検ガス導入孔４に点検ガスをガイドする注入管路１６を設けてある。
【００４６】
次に本発明のガスセンサーと従来のガスセンサーとの性能の差についでさらに具体的に説明する。
【００４７】
点検の手順は、次の▲１▼▲２▼▲３▼▲４▼の順で行われる。▲１▼点検ガス導入孔より点検ガスを規定時間の間注入する。→▲２▼ガス検知素子が規定の感度を出していることを確認する。→▲３▼規定の感度以下になるまで放置する。→▲４▼規定の感度以下になって点検を終了する。
【００４８】
ところで、図１１に点検ガスの注入時間と注入開始からガス検知素子に感度がでるまでの時間との関係を示す。図１２に点検ガスの注入時間とガス検知素子の規定の感度が出てから規定の感度がなくなるまでの時間との関係を示す。このグラフで符号Ａは図１３に示す従来例のガスセンサーの性能を示し、符号Ｂは図１に示す構造の本発明のガスセンサーの性能を示し、符号Ｃは図１の構造と図２の構造を併用した本発明のガスセンサーの性能を示す。
【００４９】
図１３に示す従来例のガスセンサーの場合（符号Ａ）、手順▲１▼−▲２▼間及び手順▲３▼−▲４▼間の時間が長い。例えば点検ガスの注入時間が２秒の場合、▲１▼−▲２▼間は２０秒、▲３▼−▲４▼間が８０秒で合計１００秒かかるが、図１に示す本発明のガスセンサーの場合（符号Ｂ）、▲１▼−▲２▼間は９秒、▲３▼−▲４▼間が６２秒で合計７１秒、図１の構造と図２の構造を併用した本発明のガスセンサーの場合（符号Ｃ）、は▲１▼−▲２▼間は４秒、▲３▼−▲４▼間が４３秒で合計４３秒で点検が終了する。
【００５０】
また実際の点検でよくされることであるが、ガス検知素子に規定の感度が出るまでの時間点検ガスと注入し続けると、図１３に示す従来例のガスセンサーの場合（符号Ａ）、規定の感度が出るまで１０秒、規定の感度以下になるまで６００秒で合計６１０秒かかる。しかし、図１に示す本発明のガスセンサーの場合（符号Ｂ）、規定の感度が出るまで５秒、規定の感度以下になるまで１２０秒で合計１２５秒と点検時間が短くなり、図１の構造と図２の構造を併用した本発明のガスセンサーの場合（符号Ｃ）、規定の感度が出るまで３秒、規定の感度以下になるまで６０秒で合計６３秒と点検時間がさらに短くなる。
【００５１】
なお、点検時に規定の感度が出たことを警報で知らせる装置として例えばガス警報器があるが、警報が鳴るまで点検ガスを注入することをすると、図１３に示す従来例のガスセンサーの場合（符号Ａ）、６００秒警報が鳴り続けることになり、点検者や周囲の人にとって利便性が悪いが、図１の構造と図２の構造を併用した本発明のガスセンサーの場合（符号Ｃ）、６０秒で警報が鳴り止むため利便性がよい。
【００５２】
なお、これまで示した実施の形態の例では、点検ガス導入孔４の数が１の場合について例示したが、本発明の効果は、点検ガス導入孔４の数が２以上の場合でも発現し、点検ガス導入孔４の数は１に制限されない。
【００５３】
また、これまで示した実施の形態の例では、第１ハウジング５と第２ハウジング６の形状は、有底筒状に形成したものとして例示したが、本発明の効果は、第１ハウジング５と第２ハウジング６の形状が半球形状、半筒状、方形、円錐形状又は、その他の形状の場合でも発現し、第１ハウジング５または第２ハウジング６の形状は有底筒状に制限されない。
【００５４】
また、これまで示した実施の形態の例では、ガスセンサーの向きを円盤状のベース２を下、第２ハウジング６を上となる向きに例示したが、本発明の効果はガスセンサーの向きによらず発現し、例示のガスセンサーの向きを任意の方向または、任意の角度に傾斜あるいは回転させた向きでも発現し、ガスセンサーの向きは例示の向きに制限されない。
【００５５】
また、第１ハウジング５は金属板に形成されたものと、第２ハウジング６は樹脂等で形成されたものとして例示したが、本発明の効果は、第１ハウジング５、第２ハウジング６を形成する材質によらず、樹脂、金属、木材、鋳物等またはこれらの複合材、焼結材等の場合でも発現し、第１ハウジング５、第２ハウジング６の材質は各々金属板、樹脂に制限されない。
【００５６】
また、これまで示した実施の形態の例では、ガス流通制限手段は、金属メッシュ板１０が兼用したものとして例示したが、本発明の効果は、ガス流通制限手段は金属メッシュ板１０が兼用しない場合や、金属メッシュ板１０以外の素材で形成した場合や、また、通気孔の径を縮小するなどの別構造の場合、例えばセラミック、金属、樹脂材料により形成されガス流通制限される多孔質等でも発現し、例示の材質、形状、構造に制限されない。
【００５７】
また、実施の形態の例では、第１ハウジング５内のガス検知素子１の数が１の場合について例示したが、本発明の効果は、ガス検知素子１の数が２以上の場合も発現し、ガス検知素子１の数は１に制限されない。
【００５８】
また、図３および図８に例示した実施の形態の例において、同形状・同構造・同じ大きさの複数の第１通気孔８を設けたものとして例示したが、本発明の効果は、異なる形状又は異なる構造又は異なる大きさあるいはこれらの組み合わせによる複数の第１通気孔８を設けた場合でも発現し、複数の第１通気孔８は同形状、同じ大きさ、同構造に制限されない。
【００５９】
また、実施の形態の例において、流入抑制手段１３は、吸着層３の下面に点検ガスが通過しない半円状や円環状の板として例示したが、本発明の効果は流入抑制手段１３がガスを通過する材質であっても、内部をガスの通過が阻害される構造（例えば、多孔質材料や、通気性シート、メッシュ状の材料）でも発現し、また形状も材質との組み合わせにより流入抑制の効果がある形状であれば任意に選択でき、流入抑制手段１３は材質あるいは形状により制限されない。
【００６０】
【発明の効果】
本発明の請求項１の発明は、点検ガス導入孔から注入される点検ガスが第１通気孔に誘導されるように点検ガス導入孔に指向性を持たせたので、指向性を持たせた点検ガス導入孔から点検ガスを第１通気孔に誘導されるように注入できて第２ハウジング内に点検ガスを充満させなくても第１ハウジング内に点検ガスを入れてガス検知素子に接触させることができる。
【００６１】
また本発明の請求項２の発明は、点検ガス導入孔から注入された点検ガスが第１ハウジング内に誘引されるようにガイドする誘引ガイド部を第１通気孔に設けたので、点検ガス導入孔から注入された点検ガスが誘引ガイド部にて第１通気孔に誘引され、第２ハウジング内に点検ガスを充満させなくても第１ハウジング内に点検ガスを入れてガス検知素子に接触させることができる。
【００６２】
また本発明の請求項３の発明は、第１ハウジングに複数個の第１通気孔を設けたので、点検ガス導入孔から点検ガスを注入したとき第１ハウジングに対して流入する流れが生じる第１通気孔と第１ハウジングから流出を生じる第１通気孔ができるために流通がしやすくなって第１ハウジング内に点検ガスが流入しやすくなり、第２ハウジング内に点検ガスを充満させなくても第１ハウジング内に点検ガスを入れてガス検知素子に接触させることができる。
【００６３】
また本発明の請求項４の発明は、第１通気孔の断面形状が点検ガス導入孔から注入される点検ガスの流れと平行な方向に長くなるように異方性を持たせたので、点検ガス導入孔から点検ガスを注入したとき点検ガスの流れと平行な方向に長くなるように形成された異方性のある第１通気孔から第１ハウジング内に点検ガスが流入しやすくなり、第２ハウジング内に点検ガスを充満させなくても第１ハウジング内に点検ガスを入れてガス検知素子に接触させることができる。
【００６４】
また本発明の請求項５の発明は、第１通気孔が第２ハウジングの内側側面の近傍に位置するように偏心させた位置に設けたので、点検ガス導入孔から点検ガスを注入して点検ガスが第２ハウジング内の壁面に沿って流れた際、壁面に沿った流れの点検ガスが第２ハウジングの内側側面近傍に位置するように偏心した第１通気孔から第１ハウジング内に流入しやすくなり、第２ハウジング内に点検ガスを充満させなくても第１ハウジング内に点検ガスを入れてガス検知素子に接触させることができる。
【００６５】
また本発明の請求項６の発明は、点検ガス導入孔から注入される点検ガスが第２ハウジングの内側側面に沿って周方向に流動するように点検ガスを誘導する構造にしたので、点検ガス導入孔から注入された点検ガスが第２ハウジングの内側側面に沿って周方向に流動して点検ガスが第１通気孔に導かれ、第１通気孔から第１ハウジング内に流入しやすくなり、第２ハウジング内に点検ガスを充満させなくても第１ハウジング５内に点検ガスを入れてガス検知素子１に接触させることができる。
【００６６】
したがって、本発明の請求項１乃至請求項６の発明は、ガスセンサーの点検をする場合に規定の感度になるまでの時間を短縮できると共に規定感度になった後に点検ガスの注入を停止した後、規定の感度以下になる時間を短縮することにができ、ガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００６７】
また本発明の請求項７の発明は、請求項１乃至請求項６において、点検ガス導入孔から注入された点検ガスが吸着層に流入するのを抑制する流入抑制手段を設けたので、点検ガスが吸着層に吸着されるのを防止でき、点検ガスの注入を停止した後、規定の感度以下になる時間を短縮することにができてガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができる。
【００６８】
また本発明の請求項８の発明は、請求項１乃至請求項７において、第１通気孔にガス流通制限手段を設けたので、ガスセンサーの点検時間の短縮化及び点検作業の効率化と、検知対象ガスに対する選択性の向上の両立ができる。
【００６９】
また本発明の請求項９の発明は、上記ガスセンサーをガス警報器本体に搭載してガス警報器を形成したので、ガスセンサーの点検時間の短縮化及び点検作業の効率化を図ることができるガス警報器を得ることができる。
【図面の簡単な説明】
【図１】（ａ）は本発明の実施の形態の一例のガスセンサーの断面図、（ｂ）は第２ハウジングの斜視図、（ｃ）は第２ハウジングの平面図である。
【図２】（ａ）は同上の他の例のガスセンサーの断面図、（ｂ）は第１ハウジングの斜視図である。
【図３】（ａ）は同上の他の例のガスセンサーの断面図、（ｂ）は第１ハウジングの斜視図である。
【図４】（ａ）は同上の他の例のガスセンサーの断面図、（ｂ）は第１ハウジングの斜視図、（ｃ）は第１ハウジングの平面図である。
【図５】同上の他の例のガスセンサーの断面図である。
【図６】図５のガスセンサーの性能を説明するグラフである。
【図７】（ａ）は同上の他の例のガスセンサーの断面図、（ｂ）は（ａ）の平面から見た断面図、（ｃ）は動作を示す斜視図である。
【図８】（ａ）（ｂ）（ｃ）は第１通気孔の構造の他の例の斜視図及び平面図である。
【図９】（ａ）は同上の他の例のガスセンサーの断面図、（ｂ）（ｃ）は流入抑制手段を示す斜視図である。
【図１０】同上のガスセンサーを組み込んだガス警報器を示す一部切欠断面図である。
【図１１】本発明のガスセンサーと従来のガスセンサーの性能を比較したグラフである。
【図１２】本発明のガスセンサーと従来のガスセンサーの性能を比較したグラフである。
【図１３】一従来例の断面図である。
【図１４】他の従来例の断面図である。
【図１５】他の従来例の断面図である。
【符号の説明】
１　ガス検知素子
４　ガス導入孔
５　第１ハウジング
６　第２ハウジング
７　中間室
８　第１通気孔
９　第２通気孔[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gas sensor mounted on a gas alarm device or the like, and particularly to a gas sensor having an adsorption layer of activated carbon or the like inside a housing in order to suppress sensitivity to a gas other than a gas to be detected. The present invention relates to an improvement of a gas sensor that uses a gas other than the detected gas to be inspected as a check gas.
[0002]
[Prior art]
In general, a gas sensor is desired to have a performance of detecting only a gas to be inspected and not detecting a gas other than the gas to be detected for the purpose. However, in general, a gas detection element that detects a flammable gas has sensitivity to the same kind of flammable gas.For example, a methane detection element that detects a methane gas is a hydrocarbon-based gas such as butane gas, Also sensitive to propane gas.
[0003]
As a method of reducing the sensitivity of gases other than the detection target of the gas sensor that also has sensitivity to the gases other than the inspection target, an adsorption layer such as activated carbon that adsorbs the gas other than the detection target is placed between the gas detection element and the outside air. The structure provided is used. According to this structure, the gas to be detected (for example, methane gas) is not adsorbed by the adsorption layer, reaches the gas detection element, and the gas detection element can detect the gas to be detected, and gases other than the detection target (alcohol, propane gas, butane gas) ) Is adsorbed by the adsorbent layer and the detection target gas reaching the gas detection element is suppressed, so that the gas detection element is less likely to detect gases other than the detection target, and there are few false alarms.
[0004]
However, on the other hand, the gas other than the detection target is adsorbed by the adsorbent layer, but when the inspection gas is applied to check the operation of the gas sensor, the detection target gas must be used as the inspection gas. For example, when the gas to be detected is methane gas, it is difficult to liquefy methane at room temperature, and if the volume is such that it can be transported even at a high pressure, the limit is about 5 liters in a normal spray can. On the other hand, butane can be easily liquefied, so it is easily portable, can be carried in a volume of several tens to one hundredth of methane, and can be sprayed in the size of a commercially available lighter. Since it is possible to perform inspections more than methane gas equivalent to one can, inspection using butane gas has been desired.
[0005]
There are the following technologies that can perform inspection using a gas other than the inspection target while suppressing sensitivity to such a gas other than the detection target.
[0006]
As an example, as shown in FIG. 13, a resin housing a is placed on a base 2 on which a gas detection element 1 such as a metal oxide semiconductor is installed so that the gas detection element 1 is housed inside the housing a. The housing a is provided with a vent hole b for communicating the inside of the housing a with the outside of the housing a, and the adsorbing layer 3 for adsorbing a gas other than the gas to be detected is provided in the vent hole b. There is one in which an inspection gas introduction hole 4 for injecting an inspection gas into the housing a at the time of inspection is provided (e.g., see Patent Document 1). The injection of the inspection gas means that the inspection gas is positively introduced by pressurizing or applying kinetic energy to distribute the inspection gas.
[0007]
As another example, as shown in FIG. 14, a first housing 5 made of metal is put on a base 2 on which the gas detection element 1 is installed so that the gas detection element 1 is housed therein, and a resin is placed outside the first housing 5. A second housing 6 made of, for example, a first housing 5 and an intermediate chamber 7 formed between the first housing 5 and the second housing 6, and a first housing 5 communicating between the inside of the first housing 5 and the inside of the intermediate chamber 7. A ventilation hole 8 is provided, a second housing 6 is provided with a second ventilation hole 9 for communicating the outside of the second housing 6 with the intermediate chamber 7, and the second ventilation hole 9 is provided with an adsorption layer 3 for adsorbing a gas other than a detection target. In some cases, a metal mesh plate 10 as an explosion-proof structure material is mounted in the first ventilation hole 9 and an inspection gas introduction hole 4 for injecting an inspection gas into the second housing 6 at the time of inspection is provided.
[0008]
Further, in order to introduce the inspection gas into the inspection gas introduction hole 4 with the above-described gas sensor mounted on the gas alarm, a gas introduction pipe 11 is provided in the gas alarm main body as shown in FIG. There is one in which one end of the pipe 11 faces the gas introduction hole 4 and the inspection gas is supplied from the other end of the gas introduction pipe 11 located outside the main body of the gas alarm using a cylinder or the like as shown by an arrow e. (For example, see Patent Document 2).
[0009]
[Patent Document 1]
Japanese Patent No. 3171733
[Patent Document 2]
Japanese Patent No. 3197409
On the other hand, another problem with gas sensors is miniaturization. Recently, devices equipped with gas sensors (for example, gas alarms) are required to be downsized.
[0010]
The semiconductor type gas detection element is heated to several hundred degrees by heating with electric power, and has sensitivity to combustible gas by heating. If a gas in the combustion concentration range comes into contact with this temperature, there is a risk of ignition. Therefore, it is necessary to provide an explosion-proof structure so that combustion is not transmitted between the chamber having the gas detection element and the outside.
[0011]
Generally, the explosion-proof structure is constituted by a metal mesh whose effective ventilation area is controlled. In order to reduce the size of the gas sensor, it is desirable to reduce the area of the mesh portion.
[0012]
As an example of the explosion-proof structure of the metal mesh, there is a method of forming the periphery of the gas detection element 1 with a metal mesh basket c as shown in the example of FIG. 13, but the metal mesh is accurately formed into a small bottomed cylindrical shape. It is difficult to reduce the size by this structure (in this structure, the outer diameter of the housing a is as large as about 15 mmφ).
[0013]
As a technique for solving this, a structure having the structure shown in FIG. 14 has been proposed. In this case, the first housing 5 is formed into a cap shape with a metal plate (it can be easily formed even if it is small), and the metal mesh plate is provided at the portion of the first ventilation hole 8 to achieve explosion-proof property and miniaturization. (In the case of this structure, the outer diameter of the second housing 6 can be reduced to about 6 to 8 mmφ). In this structure, the inspection gas introduction hole 4 for introducing the inspection gas is not provided in the first housing 5 forming the explosion-proof structure, but needs to be provided in the second housing 6.
[0014]
In addition, the opening area of the vent is limited to the gas to be detected as in an example in which the vent of the housing is provided with a flow restricting vent for the purpose of suppressing the sensitivity of gases other than the gas to be detected (for example, see Patent Document 3). Some of them have been made smaller within the range that does not affect the detection performance.
[0015]
[Patent Document 3]
Japanese Patent No. 3171720
As a result, since the first housing 5 is formed of a metal plate cap having the first ventilation hole 8, the inspection gas injected from the inspection gas introduction hole 4 of the second housing 6 fills the second housing 6. After that, the gas reaches the inside of the first housing 5, and in order to allow the inspection gas to reach the gas detection element 1, the amount of gas required to fill the inside of the second housing 6 is required, and it takes time to fill the gas. Therefore, it takes time from the start of press-fitting of the inspection gas until the gas detection element 1 has sensitivity to the inspection gas.
[0016]
When the inspection gas reaches the gas detection element 1 and the gas detection element 1 rises to the sensitivity of the inspection gas, the inside of the second housing 6 and the first housing 5 is filled with the inspection gas. Even after the press-fitting is stopped, the inspection gas remains inside the first housing 5 for a long time, and there is a problem that it takes an extremely long time until the sensitivity of the gas detection element 1 decreases.
[0017]
Further, since the second housing 6 has the adsorption layer 3, when a large amount of inspection gas is press-fitted into the second housing 6, a part of the inspection gas is adsorbed by the adsorption layer 3 and the inspection gas is stopped. Even if the concentration of the inspection gas inside the inside 6 starts to decrease, the emission of the inspection gas from the adsorption layer 3 occurs, which is the same as continuing to press-in the inspection gas for a long time by supplying the inspection gas into the second housing 6. A state occurs, and the sensitivity of the gas detection element 1 does not decrease for a long time.
[0018]
[Problems to be solved by the invention]
Due to the above, when inspecting the gas sensor with the inspection gas, it takes time for the gas detection element to reach the specified sensitivity, and for a long time after stopping the injection of the inspection gas after reaching the specified sensitivity. The sensitivity remained high, and the inspection work could not be completed.
[0019]
Devices equipped with this gas sensor (for example, a gas alarm device) are notified by an alarm that the specified sensitivity has been reached. However, since this alarm does not stop for a long time, it is difficult for inspectors and those around them. There is a problem that convenience is poor.
[0020]
The present invention has been made in view of the above points, and when inspecting a gas sensor using an inspection gas, shortens the time required to reach a specified sensitivity, and press-injects the inspection gas after reaching the specified sensitivity. To provide a gas sensor capable of shortening the inspection time of a gas sensor and improving the efficiency of inspection work by shortening the time when the sensitivity becomes equal to or less than a specified sensitivity after stopping, and a gas alarm device using the same. Is the subject.
[0021]
[Means for Solving the Problems]
A gas sensor according to the present invention for solving the above-mentioned problems includes a first housing 5 having a hollow inside, a second housing 6 covered outside so as to cover the first housing 5, a first housing 5 and a second housing 5. An intermediate chamber 7 formed between the housing 6 and a first ventilation hole 8 provided in the first housing 5 so that gas can flow between the inside of the first housing 5 and the intermediate chamber 7; A second ventilation hole 9 provided in the second housing 6 so that the gas can flow between the first housing 5 and the outside of the second housing 6; and a gas detection element provided in the first housing 5 and sensitive to a detection target gas and an inspection gas. 1, an adsorbing layer 3 provided in the second vent 9 so as to adsorb a gas other than the gas to be detected, and an inspection gas can be injected into the intermediate chamber 7 from outside the second housing 6 separately from the second vent 9. The inspection gas inlet 4 provided in the second housing 6 In the gas sensor with, wherein the inspection gas injected from the inspection gas inlet 4 is to check the gas introducing hole 4 to have a directivity to be directed to the first vent hole 8. With the above-described configuration, the inspection gas can be injected from the inspection gas introduction hole 4 having directivity into the first ventilation hole 8 so as to be guided to the first ventilation hole 8, so that the inspection gas is not filled in the second housing 6. Also, the inspection gas can be put into the first housing 5 and brought into contact with the gas detection element 1, and when the gas sensor is inspected, the time required to reach the specified sensitivity can be shortened and the specified sensitivity can be reduced. After the injection of the inspection gas is stopped after that, the time during which the sensitivity becomes equal to or lower than the specified sensitivity can be shortened, so that the inspection time of the gas sensor can be reduced and the inspection work can be performed more efficiently.
[0022]
It is also preferable that an induction guide portion 12 for guiding the inspection gas injected from the inspection gas introduction hole 4 into the first housing 5 is provided in the first ventilation hole 8. Also in this case, the inspection gas injected from the inspection gas introduction hole 4 is attracted to the first ventilation hole 8 by the attraction guide portion 12, and the first housing 5 can be filled even if the second housing 6 is not filled with the inspection gas. The inspection gas can be put into the gas detection element 1 and brought into contact with the gas detection element 1, and the inspection time of the gas sensor can be shortened and the efficiency of the inspection work can be increased similarly to the above.
[0023]
It is also preferable that a plurality of first ventilation holes 8 are provided in the first housing 5. When the inspection gas is injected from the inspection gas introduction hole 4, the first ventilation hole 8 that generates a flow that flows into the first housing 5 and the first ventilation hole 8 that flows out of the first housing 5 are formed. The inspection gas easily flows into the first housing 5, and the inspection gas is put into the first housing 5 and brought into contact with the gas detection element 1 without filling the second housing 6 with the inspection gas. As described above, the inspection time of the gas sensor can be reduced and the inspection work can be performed more efficiently.
[0024]
It is also preferable that the first ventilation hole 8 has anisotropy such that the cross-sectional shape is elongated in a direction parallel to the flow of the inspection gas injected from the inspection gas introduction hole 4. Also in this case, when the inspection gas is injected from the inspection gas introduction hole 4, the inspection is performed into the first housing 5 from the anisotropic first ventilation hole 8 formed to be elongated in a direction parallel to the flow of the inspection gas. The gas easily flows into the first housing 5 and can be brought into contact with the gas detection element 1 without filling the second housing 6 with the inspection gas. In addition, the inspection time of the gas sensor can be reduced and the inspection work can be performed more efficiently.
[0025]
It is also preferable that the first ventilation hole 8 is provided at an eccentric position so as to be located near the inner side surface of the second housing 6. Also in this case, when the inspection gas is injected from the inspection gas introduction hole 4 and flows along the wall surface in the second housing 6, the inspection gas flowing along the wall surface is close to the inner side surface of the second housing 6. The inspection gas is easily introduced into the first housing 5 from the first vent hole 8 which is eccentric so as to be located at the position, and the inspection gas is introduced into the first housing 5 without filling the second housing 6 with the inspection gas. Since the sensor can be brought into contact with the detection element 1, the inspection time of the gas sensor can be shortened and the efficiency of the inspection work can be increased in the same manner as described above.
[0026]
It is also preferable that the inspection gas is introduced such that the inspection gas injected from the inspection gas introduction hole 4 flows in the circumferential direction along the inner side surface of the second housing 6. Also in this case, the inspection gas injected from the inspection gas introduction hole 4 flows in the circumferential direction along the inner side surface of the second housing 6, and the inspection gas is guided to the first ventilation hole 8, and the vicinity of the first ventilation hole 8. Since the flow of the inspection gas is relatively large, the inspection gas easily flows into the first housing 5 from the first ventilation hole 8, and the inspection gas can be introduced into the first housing 5 without filling the second housing 6 with the inspection gas. The gas sensor can be put into contact with the gas detection element 1, and the inspection time of the gas sensor can be shortened and the efficiency of the inspection work can be improved similarly to the above.
[0027]
Further, it is preferable that an inflow suppressing means 13 for suppressing the inspection gas injected from the inspection gas introduction hole 4 from flowing into the adsorption layer 3 is provided. In this case, it is possible to prevent the inspection gas from being adsorbed to the adsorption layer 3, and to reduce the time required to reach the specified sensitivity or less after the injection of the inspection gas is stopped. Inspection work can be made more efficient.
[0028]
It is also preferable to provide a gas flow restricting means in the first vent 8 of the gas sensor. It is known that by providing a gas flow restricting means in the first ventilation hole 8, selectivity with respect to the gas to be detected can be obtained (for example, see Patent Document 3). Therefore, there is a problem that the inspection gas arrives at the gas detection element 1 at a later time and the inspection time becomes longer. However, by providing the gas flow restricting means in the first ventilation hole 8 of the gas sensor for which the inspection time is shortened and the inspection work is made more efficient, the selectivity to the detection target gas is improved and the inspection time is reduced. Shortening can be compatible.
[0029]
It is also preferable that the gas sensor is mounted on the gas alarm device main body 14 to form a gas alarm device. In this case, it is possible to obtain a gas alarm device capable of shortening the inspection time of the gas sensor and increasing the efficiency of the inspection work.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
First, an example of the embodiment shown in FIG. 1 will be described. A gas detection element 1 capable of detecting a gas to be inspected and a gas to be inspected is installed on a disc-shaped base 2. The base 2 is mounted over a bottomed first cylindrical housing 5. The gas detecting element 1 is housed in one housing 5. The first housing 5 is formed by molding a metal plate into a bottomed cylindrical shape. The second housing 6 is formed in a cylindrical shape having a bottom with resin or the like, and is mounted on the first housing 5 so as to cover the second housing 6. An intermediate chamber 7 is formed between the second housing 6 and the first housing 5. The first housing 5 is provided with a first ventilation hole 8 for communicating the inside of the first housing 5 with the intermediate chamber 7, and a metal mesh plate 10 as an explosion-proof structure material is attached to the first ventilation hole 8. It is. The second housing 6 is provided with a second ventilation hole 9 for communicating the outside of the second housing 6 with the intermediate chamber 7, and the adsorbing layer 3 for adsorbing gas other than the detection target is formed on the second chamber 6 at the second chamber 6 side. It is installed in the vent 9. Inspection gas introduction holes 4 for injecting an inspection gas are provided in the second housing 6 so as to allow the outside of the second housing 6 to communicate with the intermediate chamber 7. In this example, the inspection gas introduction hole 4 has directivity so as to be directed to the first ventilation hole 8. Since the gas sensor configured as above is designed to protect the explosion by the first housing 6 made of metal and the metal mesh plate 10 attached to the first ventilation hole 8, the outer diameter of the second housing 6 is 6 to 8 mm. Can be reduced in size.
[0031]
When the gas sensor is inspected, the inspection gas is injected into the intermediate chamber 7 from the inspection gas introduction hole 4, but the inspection gas is injected from the inspection gas introduction hole 4 because the inspection gas introduction hole 4 has directivity. It can be injected so as to be guided to the first ventilation hole 8. Accordingly, the inspection gas can be put into the first housing 5 and brought into contact with the gas detection element 1 without filling the second housing 6 with the inspection gas. This shortens the time required to reach the specified sensitivity when checking the gas sensor, and stops the injection of the check gas after the specified sensitivity is reached. The time during which the sensitivity becomes lower can be reduced.
[0032]
The metal mesh plate 10 also serves as a gas flow restricting means, and when the inspection gas is injected, the inspection gas can move through the first ventilation hole 8, but at the time of normal detection, the first gas by the convection is used. The movement of the ventilation hole 8 is restricted, and the movement of the gas to be detected by diffusion is possible.
[0033]
The gas to be detected moves to the intermediate chamber 7 by diffusion through the second ventilation hole 9 of the second housing 6, so that the detection performance is not affected by the directivity of the inspection gas introduction hole 4 and does not change.
[0034]
Next, an example of the embodiment shown in FIG. 2 will be described. This example is also basically the same as the above example, and the same components are denoted by the same reference numerals, description thereof will be omitted, and only different points will be mainly described. In the case of this example, instead of giving directivity to the inspection gas introduction hole 4 as in the above example, the inspection gas introduced from the inspection gas introduction hole 4 is guided so as to be attracted into the first housing 5. The guide portion 12 is provided in the first ventilation hole 8. That is, the guide member 12 having a shape for receiving the injected inspection gas and guiding it to the first ventilation hole 8 is provided.
[0035]
Inspection gas press-fitted from the inspection gas introduction hole 4 for inspection of the gas sensor is drawn into the first ventilation hole 8 by the induction guide portion 12, and the second housing 6 is filled with the inspection gas without being filled with the inspection gas. An inspection gas can be put into one housing 5 and brought into contact with the gas detection element 1. In this case, if the opening area of the first ventilation hole 8 does not change even if the shape of the portion of the first ventilation hole 8 changes, the inspection property is improved while maintaining the explosion-proof property.
[0036]
Since the gas to be detected moves to the intermediate chamber 7 by diffusion through the second ventilation hole 9 of the second housing 6, even if the guide portion 12 is provided, if the opening area of the first ventilation hole 8 does not change, the detection is performed. Performance does not change.
[0037]
Next, an example of the embodiment shown in FIG. 3 will be described. This example is also basically the same as the above example, and the same components are denoted by the same reference numerals, description thereof will be omitted, and only different points will be mainly described. In the case of this example, when the first housing 8 is provided with the first ventilation holes 8, the plurality of first ventilation holes 8 are provided at intervals. In the example shown in the figure, two first ventilation holes 8a and 8b are perforated. In the case of this example, the inspection gas easily flows through the first vent of one hole having the same opening area. That is, the first ventilation hole 8 that flows into the first housing 5 when the check gas is injected from the gas introduction hole 4 and the first ventilation hole 8 that flows out of the first housing 5 are formed. The inspection gas easily flows into the first housing 5 and the inspection gas is put into the first housing 5 to contact the gas detection element 1 without filling the second housing 6 with the inspection gas. Can be done.
[0038]
Next, an example of the embodiment shown in FIG. 4 will be described. This example is also basically the same as the above example, and the same components are denoted by the same reference numerals, description thereof will be omitted, and only different points will be mainly described. In the case of the present example, the first ventilation hole 8 has anisotropy so that the cross-sectional shape becomes longer in a direction parallel to the flow of the inspection gas injected from the inspection gas introduction hole 4. That is, it is formed in a long hole shape so as to be elongated in a direction parallel to the flow direction of the inspection gas. In this case, the inspection gas is introduced into the first housing 5 from the anisotropic first ventilation hole 8 formed to be elongated in a direction parallel to the flow of the inspection gas when the inspection gas is press-fitted from the inspection gas introduction hole 4. Can easily flow into the first housing 5 and make contact with the gas detection element 1 without filling the second housing 6 with the inspection gas. At this time, the aspect ratio of the elongated first ventilation hole 8 is desirably 1.5 or more.
[0039]
Next, an example of the embodiment shown in FIG. 5 will be described. This example is also basically the same as the above example, and the same components are denoted by the same reference numerals, description thereof will be omitted, and only different points will be mainly described. In the case of this example, when the first ventilation hole 8 is provided, it is provided at an eccentric position so as to be located near the inner side surface of the second housing 6. That is, the first housing 5 is eccentric with respect to the center position so as to approach the inner side surface of the second housing 6. Also, at this time, it is desirable to be eccentric in the direction opposite to the inspection gas inlet 4. In this case, when the inspection gas is injected into the second housing 6 from the inspection gas introduction hole 4,
The inspection gas that flows along the wall surface that is the inner side surface of the second housing 6 flows along the wall surface toward the first ventilation hole 8 and flows into the first housing 5 from the first ventilation hole 8. The inspection gas can be put into the first housing 5 and brought into contact with the gas detection element 1 without filling the second housing 6 with the inspection gas.
[0040]
Here, when the distance from the center of the second housing 6 to the inner side surface of the second housing 6 is R, and the distance from the center to the first ventilation hole 8 is r, (r / R) and the gas detection element 1 FIG. 6 is a graph showing the relationship between the time and the time required for sensing. In FIG. 6, the vertical axis shows the time until the sensing, and the horizontal axis shows (r / R). The larger the (r / R), the shorter the time until the sensing. When (r / R)> 0.1, the effect of shortening the time until sensing starts to appear, and when (r / R)> 0.2, the effect becomes more prominent, and (r / R)> 0.3. It is desirable.
[0041]
Next, an example of the embodiment shown in FIG. 7 will be described. This example is also basically the same as the above example, and the same components are denoted by the same reference numerals, description thereof will be omitted, and only different points will be mainly described. In the case of this example, the inspection gas is guided so that the inspection gas injected from the inspection gas introduction hole 4 flows in the circumferential direction along the inner side surface of the second housing 6. That is, the inspection gas flows in the circumferential direction along the inner side surface of the second housing 6 by turning the inspection gas introduction hole 4 obliquely downward and inclining so as to approach the tangential direction of the inner side surface of the second housing 6. In this way, the inspection gas is guided. The first ventilation hole 8 is eccentrically provided at a position close to the inner side surface of the second housing 6.
[0042]
In this case, the inspection gas injected from the inspection gas introduction hole 4 flows in the circumferential direction along the inner side surface of the second housing 6 to generate a vortex, and the inspection gas is guided to the first ventilation hole 8 and the first gas is introduced. The gas easily flows into the first housing 5 from the pores 8, and the inspection gas can be put into the first housing 5 and brought into contact with the gas detection element 1 without filling the second housing 6 with the inspection gas.
[0043]
When the inspection gas is injected spirally along the inner side surface of the second housing 6 as described above, if the first ventilation hole 8 provided in the first housing 5 is formed as shown in FIG. Easy to introduce. In FIG. 8A, the first ventilation hole 8 is formed in an arc shape, and a pair of first ventilation holes 8 are provided at symmetrical positions. In FIG. 8B, an introduction guide 15 is provided in the first ventilation hole 8. In FIG. 8C, a plurality of (four in the illustrated example) first ventilation holes 8 are provided in the circumferential direction, and an introduction guide 15 is provided in each first ventilation hole 8.
[0044]
Next, an example of the embodiment shown in FIG. 9 will be described. This example is also basically the same as the above example, and the same elements are denoted by the same reference numerals, description thereof will be omitted, and only different points will be mainly described. In the case of this example, an inflow suppressing means 13 for suppressing the inspection gas injected from the inspection gas introduction hole 4 from flowing into the adsorption layer 3 is provided. That is, a semicircular or annular plate through which the inspection gas does not pass is attached to the lower surface of the adsorption layer 3. In this case, it is possible to prevent the inspection gas from being adsorbed by the adsorption layer 3, and it is possible to shorten the time during which the sensitivity becomes equal to or lower than the specified sensitivity after the injection of the inspection gas is stopped. In other words, the inspection gas adsorbed on the adsorption layer 3 is prevented from reaching the gas detection element 1 later by desorption and continuing the detection, and the inspection property is improved. In addition, in FIG. 9 described above, the gas sensor of the example shown in FIG. 5 provided with the inflow suppression means 13 is described, but the inflow suppression means 13 may be provided in any of the examples of FIGS. it can.
[0045]
FIG. 10 shows a gas alarm device in which the gas sensor as described above is incorporated in the gas alarm device main body 14. The gas alarm device main body 14 is provided with an injection conduit 16 for guiding the inspection gas from outside the gas alarm device main body 14 to the inspection gas introduction hole 4 of the gas sensor.
[0046]
Next, the difference in performance between the gas sensor of the present invention and the conventional gas sensor will be described more specifically.
[0047]
The inspection procedure is performed in the following order (1) (2) (3) (4). (1) Inject the inspection gas from the inspection gas inlet for the specified time. → (2) Check that the gas detection element has the specified sensitivity. → (3) Leave until the sensitivity falls below the specified value. → (4) The inspection ends when the sensitivity falls below the specified sensitivity.
[0048]
FIG. 11 shows the relationship between the injection time of the inspection gas and the time from the start of the injection until the sensitivity of the gas detection element is increased. FIG. 12 shows the relationship between the injection time of the inspection gas and the time from when the specified sensitivity of the gas detection element is obtained until the specified sensitivity is lost. In this graph, the symbol A indicates the performance of the gas sensor of the conventional example shown in FIG. 13, the symbol B indicates the performance of the gas sensor of the present invention having the structure shown in FIG. 1, and the symbol C indicates the structure of FIG. The performance of the gas sensor of the present invention using the structure is shown.
[0049]
In the case of the conventional gas sensor shown in FIG. 13 (symbol A), the time between procedure (1) and (2) and the time between procedure (3) and (4) are long. For example, when the injection time of the inspection gas is 2 seconds, it takes 20 seconds between (1) and (2) and 80 seconds between (3) and (4), which takes 100 seconds in total. In the case of the sensor (symbol B), 9 seconds between (1) and (2) and 62 seconds between (3) and (4), for a total of 71 seconds, the present invention using both the structure of FIG. 1 and the structure of FIG. In the case of the gas sensor (reference code C), the inspection is completed in 4 seconds between (1) and (2) and 43 seconds between (3) and (4), for a total of 43 seconds.
[0050]
Further, as is often done in actual inspection, if the injection of the inspection gas is continued until the specified sensitivity is obtained in the gas detection element, the gas sensor of the conventional example shown in FIG. It takes 10 seconds for the sensitivity to appear, and 600 seconds for the sensitivity to fall below the specified sensitivity, for a total of 610 seconds. However, in the case of the gas sensor of the present invention shown in FIG. 1 (symbol B), the inspection time is reduced to 5 seconds until the specified sensitivity is obtained, and 120 seconds until the sensitivity is equal to or less than the specified sensitivity, for a total of 125 seconds. In the case of the gas sensor of the present invention using both the structure and the structure of FIG. 2 (reference C), the inspection time is further shortened to 3 seconds until the specified sensitivity is obtained and 60 seconds until the sensitivity is equal to or less than the specified sensitivity, for a total of 63 seconds. .
[0051]
For example, there is a gas alarm as a device that gives an alarm that a specified sensitivity has been obtained at the time of inspection. However, if the inspection gas is injected until an alarm sounds, the conventional gas sensor shown in FIG. A), the alarm continues to sound for 600 seconds, which is inconvenient for the inspector and the surrounding people, but in the case of the gas sensor of the present invention using both the structure of FIG. 1 and the structure of FIG. 2 (reference C). The alarm stops sounding in 60 seconds, which is convenient.
[0052]
In addition, in the example of the embodiment shown so far, the case where the number of the inspection gas introduction holes 4 is 1 is illustrated, but the effect of the present invention is exerted even when the number of the inspection gas introduction holes 4 is 2 or more. The number of inspection gas introduction holes 4 is not limited to one.
[0053]
Further, in the example of the embodiment described so far, the first housing 5 and the second housing 6 are illustrated as being formed into a bottomed cylindrical shape, but the effect of the present invention is not limited to the first housing 5 and the second housing 6. The shape of the second housing 6 is expressed even when the shape is a hemispherical shape, a semi-cylindrical shape, a square shape, a conical shape, or another shape, and the shape of the first housing 5 or the second housing 6 is not limited to a bottomed cylindrical shape.
[0054]
In addition, in the example of the embodiment described so far, the direction of the gas sensor is illustrated as the direction in which the disc-shaped base 2 is below and the direction of the second housing 6 is in the upward direction. The direction of the gas sensor is expressed regardless of the direction of the gas sensor. The direction of the gas sensor is not limited to the direction of the gas sensor.
[0055]
Further, the first housing 5 is illustrated as being formed of a metal plate, and the second housing 6 is illustrated as being formed of resin or the like. However, the effect of the present invention is that the first housing 5 and the second housing 6 are formed. Regardless of the material to be used, it appears even in the case of resin, metal, wood, casting, or the like, or a composite or sintered material thereof, and the material of the first housing 5 and the second housing 6 is not limited to a metal plate and a resin, respectively. .
[0056]
Further, in the example of the embodiment described so far, the gas flow restricting means is illustrated as being shared by the metal mesh plate 10. However, the effect of the present invention is that the gas flow restricting means is not shared by the metal mesh plate 10. In the case of, for example, when formed of a material other than the metal mesh plate 10, or in the case of another structure such as reducing the diameter of the vent hole, for example, a porous material which is formed of a ceramic, metal, or resin material and whose gas flow is restricted However, it is not limited to the exemplified materials, shapes and structures.
[0057]
Further, in the example of the embodiment, the case where the number of the gas detecting elements 1 in the first housing 5 is 1 is illustrated, but the effect of the present invention is also exerted when the number of the gas detecting elements 1 is 2 or more. The number of the gas detection elements 1 is not limited to one.
[0058]
In addition, in the example of the embodiment illustrated in FIGS. 3 and 8, the plurality of first ventilation holes 8 having the same shape, the same structure, and the same size are illustrated, but the effect of the present invention is different. This occurs even when a plurality of first ventilation holes 8 having a shape, a different structure, a different size, or a combination thereof are provided, and the plurality of first ventilation holes 8 are not limited to the same shape, the same size, and the same structure.
[0059]
In addition, in the example of the embodiment, the inflow suppressing means 13 is exemplified as a semicircular or annular plate through which the inspection gas does not pass on the lower surface of the adsorbing layer 3. Even if it is a material that passes through, the structure that the passage of gas inside is hindered (for example, a porous material, a gas permeable sheet, a mesh-like material) is exhibited, and the shape is suppressed by the combination with the material. The inflow suppressing means 13 is not limited by the material or the shape, as long as the shape has the above effect.
[0060]
【The invention's effect】
According to the invention of claim 1 of the present invention, the inspection gas introduction hole is provided with directivity so that the inspection gas injected from the inspection gas introduction hole is guided to the first ventilation hole. The inspection gas can be injected from the inspection gas introduction hole into the first ventilation hole so as to be guided into the first ventilation hole, and even if the inspection gas is not filled in the second housing, the inspection gas is put into the first housing and brought into contact with the gas detection element. be able to.
[0061]
According to the invention of claim 2 of the present invention, since the guide hole for guiding the inspection gas injected from the inspection gas introduction hole into the first housing is provided in the first ventilation hole, the inspection gas is introduced. The inspection gas injected from the hole is attracted to the first ventilation hole by the attraction guide portion, and the inspection gas is put into the first housing and brought into contact with the gas detection element without filling the second housing with the inspection gas. be able to.
[0062]
Further, according to the invention of claim 3 of the present invention, since the first housing is provided with a plurality of first ventilation holes, a flow which flows into the first housing when the inspection gas is injected from the inspection gas introduction hole is generated. Since the 1 vent and the 1st vent which flows out from the 1st housing are made, it becomes easy to distribute, and the inspection gas easily flows into the 1st housing, and the 2nd housing is not filled with the inspection gas. Also, the inspection gas can be put in the first housing and brought into contact with the gas detection element.
[0063]
According to the invention of claim 4 of the present invention, the first vent has an anisotropy such that the cross-sectional shape becomes longer in a direction parallel to the flow of the inspection gas injected from the inspection gas introduction hole. When the inspection gas is injected from the gas introduction hole, the inspection gas easily flows into the first housing from the first anisotropic ventilation hole formed so as to be elongated in a direction parallel to the flow of the inspection gas. Even if the inspection gas is not filled in the second housing, the inspection gas can be put in the first housing and brought into contact with the gas detection element.
[0064]
According to the invention of claim 5 of the present invention, since the first ventilation hole is provided at an eccentric position so as to be located near the inner side surface of the second housing, the inspection gas is injected from the inspection gas introduction hole to perform the inspection. When the gas flows along the wall surface in the second housing, the inspection gas of the flow along the wall surface flows into the first housing from the first vent hole eccentric so as to be located near the inner side surface of the second housing. This makes it easier to put the inspection gas into the first housing and make it contact the gas detection element without filling the second housing with the inspection gas.
[0065]
According to the invention of claim 6 of the present invention, the inspection gas is introduced such that the inspection gas injected from the inspection gas introduction hole flows in the circumferential direction along the inner side surface of the second housing. The inspection gas injected from the introduction hole flows in the circumferential direction along the inner side surface of the second housing, and the inspection gas is guided to the first ventilation hole, and easily flows into the first housing from the first ventilation hole, The inspection gas can be put into the first housing 5 and brought into contact with the gas detection element 1 without filling the second housing with the inspection gas.
[0066]
Therefore, the invention according to claims 1 to 6 of the present invention can shorten the time required for the gas sensor to reach the specified sensitivity when checking the gas sensor and stop the injection of the check gas after the specified sensitivity is reached. Therefore, the time during which the sensitivity becomes lower than the specified sensitivity can be shortened, and the inspection time of the gas sensor can be shortened and the inspection work can be performed more efficiently.
[0067]
According to a seventh aspect of the present invention, in the first to sixth aspects, the flow rate of the inspection gas introduced from the inspection gas introduction hole is reduced by preventing the inspection gas from flowing into the adsorption layer. Can be prevented from being adsorbed to the adsorbent layer, and after stopping the injection of the inspection gas, the time when the sensitivity falls below the specified sensitivity can be shortened, shortening the inspection time of the gas sensor and increasing the efficiency of inspection work Can be achieved.
[0068]
Also, in the invention of claim 8 of the present invention, since the gas flow restricting means is provided in the first ventilation hole in claim 1 to claim 7, the inspection time of the gas sensor is shortened and the inspection work is made more efficient. It is possible to simultaneously improve the selectivity for the detection target gas.
[0069]
According to the ninth aspect of the present invention, since the gas sensor is mounted on the main body of the gas alarm device to form the gas alarm device, the inspection time of the gas sensor can be shortened and the inspection work can be performed more efficiently. A gas alarm can be obtained.
[Brief description of the drawings]
1A is a cross-sectional view of a gas sensor according to an embodiment of the present invention, FIG. 1B is a perspective view of a second housing, and FIG. 1C is a plan view of the second housing.
FIG. 2A is a cross-sectional view of a gas sensor of another example of the above, and FIG. 2B is a perspective view of a first housing.
FIG. 3A is a cross-sectional view of a gas sensor of another example of the above, and FIG. 3B is a perspective view of a first housing.
4A is a sectional view of a gas sensor of another example of the above, FIG. 4B is a perspective view of a first housing, and FIG. 4C is a plan view of the first housing.
FIG. 5 is a cross-sectional view of another example of the gas sensor according to the first embodiment.
FIG. 6 is a graph illustrating the performance of the gas sensor of FIG.
7A is a cross-sectional view of a gas sensor of another example of the above, FIG. 7B is a cross-sectional view as viewed from the plane of FIG. 7A, and FIG. 7C is a perspective view showing operation.
8 (a), (b) and (c) are a perspective view and a plan view of another example of the structure of the first ventilation hole.
FIG. 9A is a cross-sectional view of another example of the gas sensor of the above embodiment, and FIGS. 9B and 9C are perspective views showing inflow suppressing means.
FIG. 10 is a partially cutaway sectional view showing a gas alarm incorporating the gas sensor according to the first embodiment.
FIG. 11 is a graph comparing the performance of the gas sensor of the present invention with the performance of a conventional gas sensor.
FIG. 12 is a graph comparing the performance of the gas sensor of the present invention with the performance of a conventional gas sensor.
FIG. 13 is a sectional view of a conventional example.
FIG. 14 is a sectional view of another conventional example.
FIG. 15 is a sectional view of another conventional example.
[Explanation of symbols]
1 Gas detection element
4 Gas inlet
5 First housing
6 Second housing
7 Intermediate room
8 First vent
9 Second vent

Claims

A first housing having a hollow interior, a second housing externally covered to cover the first housing, an intermediate chamber formed between the first housing and the second housing; A first ventilation hole provided in the first housing so that gas can flow between the chamber and a second ventilation hole provided in the second housing so that gas can flow between the intermediate chamber and the outside of the second housing; A gas sensing element provided in the first housing and responsive to the detection target gas and the inspection gas; an adsorption layer provided in the second ventilation hole to adsorb a gas other than the detection target gas; Separately, in a gas sensor having an inspection gas introduction hole provided in the second housing so that the inspection gas can be injected into the intermediate chamber from the outside of the second housing, the inspection gas injected from the inspection gas introduction hole is supplied to the first passage. I'm guided by stomata Gas sensor, characterized in that provided with directivities Inspection gas introduction holes.

A first housing having a hollow interior, a second housing externally covered to cover the first housing, an intermediate chamber formed between the first housing and the second housing; A first ventilation hole provided in the first housing so that gas can flow between the chamber and a second ventilation hole provided in the second housing so that gas can flow between the intermediate chamber and the outside of the second housing; A gas sensing element provided in the first housing and responsive to the detection target gas and the inspection gas; an adsorption layer provided in the second ventilation hole to adsorb a gas other than the detection target gas; Separately, in a gas sensor having an inspection gas introduction hole provided in the second housing so that an inspection gas can be injected into the intermediate chamber from outside the second housing, the inspection gas injected from the inspection gas introduction hole is supplied to the first housing. Attracted into Gas sensor, characterized in that a attraction guide portion for guiding the so that the first vent hole.

A first housing having a hollow interior, a second housing externally covered to cover the first housing, an intermediate chamber formed between the first housing and the second housing; A first ventilation hole provided in the first housing so that gas can flow between the chamber and a second ventilation hole provided in the second housing so that gas can flow between the intermediate chamber and the outside of the second housing; A gas sensing element provided in the first housing and responsive to the detection target gas and the inspection gas; an adsorption layer provided in the second ventilation hole to adsorb a gas other than the detection target gas; Separately, in a gas sensor having an inspection gas introduction hole provided in the second housing so that an inspection gas can be injected into the intermediate chamber from outside the second housing, a plurality of first ventilation holes are provided in the first housing. Gas characterized by that Nsa.

A first housing having a hollow interior, a second housing externally covered to cover the first housing, an intermediate chamber formed between the first housing and the second housing; A first ventilation hole provided in the first housing so that gas can flow between the chamber and a second ventilation hole provided in the second housing so that gas can flow between the intermediate chamber and the outside of the second housing; A gas sensing element provided in the first housing and responsive to the detection target gas and the inspection gas; an adsorption layer provided in the second ventilation hole to adsorb a gas other than the detection target gas; Separately, in a gas sensor provided with an inspection gas introduction hole provided in the second housing so that an inspection gas can be injected into the intermediate chamber from outside the second housing, the cross-sectional shape of the first ventilation hole is injected from the inspection gas introduction hole. Inspection gas flow Gas sensor, characterized in that gave anisotropy to be longer in a direction parallel to the.

A first housing having a hollow interior, a second housing externally covered to cover the first housing, an intermediate chamber formed between the first housing and the second housing; A first ventilation hole provided in the first housing so that gas can flow between the chamber and a second ventilation hole provided in the second housing so that gas can flow between the intermediate chamber and the outside of the second housing; A gas sensing element provided in the first housing and responsive to the detection target gas and the inspection gas; an adsorption layer provided in the second ventilation hole to adsorb a gas other than the detection target gas; Separately, in a gas sensor having an inspection gas introduction hole provided in the second housing so that an inspection gas can be injected into the intermediate chamber from the outside of the second housing, the first ventilation hole is provided near the inner side surface of the second housing. Eccentric to be located Gas sensor, characterized in that provided in the allowed position.

A first housing having a hollow interior, a second housing externally covered to cover the first housing, an intermediate chamber formed between the first housing and the second housing; A first ventilation hole provided in the first housing so that gas can flow between the chamber and a second ventilation hole provided in the second housing so that gas can flow between the intermediate chamber and the outside of the second housing; A gas sensing element provided in the first housing and responsive to the detection target gas and the inspection gas; an adsorption layer provided in the second ventilation hole to adsorb a gas other than the detection target gas; Separately, in a gas sensor having an inspection gas introduction hole provided in the second housing so that an inspection gas can be injected into the intermediate chamber from outside the second housing, the inspection gas injected from the inspection gas introduction hole is supplied to the second housing. Inside side Gas sensor, characterized in that a structure to induce an inspection gas to flow circumferentially along.

The gas sensor according to any one of claims 1 to 6, further comprising an inflow suppressing unit configured to prevent the inspection gas injected from the inspection gas introduction hole from flowing into the adsorption layer.

The gas sensor according to any one of claims 1 to 7, wherein gas flow restricting means is provided in the first ventilation hole.

9. A gas alarm device, wherein the gas sensor according to claim 1 is mounted on a gas alarm device main body.