JP4091902B2 - Explosion-proof gas sensor - Google Patents

Explosion-proof gas sensor Download PDF

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JP4091902B2
JP4091902B2 JP2003385601A JP2003385601A JP4091902B2 JP 4091902 B2 JP4091902 B2 JP 4091902B2 JP 2003385601 A JP2003385601 A JP 2003385601A JP 2003385601 A JP2003385601 A JP 2003385601A JP 4091902 B2 JP4091902 B2 JP 4091902B2
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explosion
proof
gas sensor
filter
sensor
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JP2005147844A (en
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広哉 中島
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FIS Inc
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Description

本発明は、爆発性雰囲気の燃焼による熱や火災等が外部に漏れることを防止した防爆型ガスセンサに関するものである。   The present invention relates to an explosion-proof gas sensor that prevents heat, fire, and the like due to combustion in an explosive atmosphere from leaking to the outside.

可燃性のガスや蒸気を含む爆発性雰囲気が存在していて爆発の恐れがある危険場所にガスセンサを設置する場合、このガスセンサには、高い防爆性を有した防爆構造を具備していることが要求される。ここでの防爆構造は、内部での爆発性雰囲気の爆発による熱や火災等が外部に漏れることを防止する為の構造であり、このような防爆構造を備えた防爆型ガスセンサとして従来のものは、図９に示すように、ガス感応体２０を有するガスセンサ本体２の周囲を両端が開口した筒状の防爆ケース１で覆うとともに、該防爆ケース１の一方の開口を樹脂４等で塞ぎ、他方の開口には金網状の防爆フィルタ３を配した構造となっている（特許文献１参照）。そして、上記構造を備えることで、防爆フィルタ３の通気部分を介して防爆ケース１内に導入した検査対象ガスをガス感応体２０で検知するとともに、防爆ケース１内で爆発を生じた場合であっても該防爆ケース１が損傷を受けることなく耐え、外部に存在する爆発性雰囲気にまで引火をすることがないようにしている。   When installing a gas sensor in a hazardous location where there is an explosive atmosphere containing flammable gas or vapor and where there is a risk of explosion, the gas sensor must have an explosion-proof structure with high explosion-proof properties. Required. The explosion-proof structure here is a structure for preventing heat, fire, etc. due to explosion in the explosive atmosphere inside from leaking to the outside, and conventional ones as explosion-proof gas sensors equipped with such an explosion-proof structure are 9, the periphery of the gas sensor body 2 having the gas sensitive body 20 is covered with a cylindrical explosion-proof case 1 having both ends opened, and one opening of the explosion-proof case 1 is closed with a resin 4 or the like, The opening has a structure in which a wire net-like explosion-proof filter 3 is arranged (see Patent Document 1). By providing the above structure, the gas to be inspected introduced into the explosion-proof case 1 through the ventilation portion of the explosion-proof filter 3 is detected by the gas sensitive body 20 and an explosion occurs in the explosion-proof case 1. However, the explosion-proof case 1 can endure without being damaged, and the explosion-proof atmosphere existing outside is not ignited.

しかしながら、上記した従来の防爆型ガスセンサにあっては、防爆ケース１と樹脂４との接合部分や、防爆ケース１と防爆フィルタ３との接合部分の強度が十分ではなく、防爆ケース１内で大規模な爆発があれば破損を生じて外部の爆発性雰囲気に引火してしまう恐れがあった。また、防爆フィルタ３の通気部分における火災の伝播防止機能も十分ではなく、この点においてもやはり外部の爆発性雰囲気に引火してしまう恐れのある構造であった。これに対して、防爆ケース１の樹脂４による封止部分を大きく設けたり、また、図示のような金網状の防爆フィルタ３の代りに通気穴を有するカバーを二重構造で設けたりすることで（特許文献２参照）防爆性を向上させることは可能であるが、この場合には防爆型ガスセンサが全体に大型化するといった問題や、構造が複雑化して部品点数が増加するといった問題が生じてしまう。
特開平６−６６７５３号公報 特開２００１−１０８６５０号公報 However, in the conventional explosion-proof gas sensor described above, the strength of the joint portion between the explosion-proof case 1 and the resin 4 and the joint portion between the explosion-proof case 1 and the explosion-proof filter 3 is not sufficient and is large in the explosion-proof case 1. If there was a large-scale explosion, there was a risk of breaking and igniting an external explosive atmosphere. Further, the function of preventing the propagation of fire in the ventilation portion of the explosion-proof filter 3 is not sufficient, and in this respect as well, the structure may possibly ignite an external explosive atmosphere. On the other hand, by providing a large sealing portion with the resin 4 of the explosion-proof case 1 or by providing a cover having a vent hole in a double structure instead of the wire mesh-shaped explosion-proof filter 3 as shown in the figure. (Refer to Patent Document 2) Although it is possible to improve the explosion-proof property, in this case, there arises a problem that the explosion-proof gas sensor is increased in size as a whole and a problem that the structure becomes complicated and the number of parts increases. End up.
JP-A-6-66753 JP 2001-108650 A

本発明は上記問題点に鑑みて発明したものであって、コンパクトで部品点数の少ない構造であり、尚且つ高い防爆性を具備している防爆型ガスセンサを提供することを課題とするものである。   The present invention was invented in view of the above problems, and an object of the present invention is to provide an explosion-proof gas sensor having a compact structure with a small number of parts and having a high explosion-proof property. .

上記課題を解決するために本発明を、内部空間１２と連通した通気穴１０と端子導出穴１１とを有する金属製の防爆ケース１の前記内部空間１２内にセンサ本体２を収容し、通気穴１０を防爆フィルタ３で塞ぐとともに、端子導出穴１１を樹脂４注入により封止して成る防爆型ガスセンサであって、防爆フィルタ３として焼結金属フィルタを用い、焼結金属フィルタと防爆ケース１とを同時焼結により接合させるとともに、端子導出穴１１の内周面には樹脂４を抜け止めする為の凹溝１６を設けていることを特徴としたものとする。このようにすることで、防爆フィルタ３が防爆ケース１と同時焼結により強固に接合されるとともに、樹脂４も十分な強度で抜け止めされることから、防爆ケース１内部での爆発に対しても十分な強度を有することとなる。加えて、防爆フィルタ３として焼結金属フィルタを用いていることで、外部のガスを導入する通気部分においても十分な火災伝播防止機能が得られ、したがって外部の爆発性雰囲気への引火が確実に防止されることとなる。即ち、本発明の防爆型ガスセンサは、上記のようなコンパクトで部品点数の少ない構造でありながら高い防爆性を具備した防爆型ガスセンサとなるものである。   In order to solve the above-mentioned problem, the present invention is configured such that the sensor body 2 is accommodated in the internal space 12 of the metal explosion-proof case 1 having the vent hole 10 communicating with the internal space 12 and the terminal lead-out hole 11. 10 is an explosion-proof gas sensor in which a terminal lead-out hole 11 is sealed by injecting resin 4, and a sintered metal filter is used as the explosion-proof filter 3. Are joined by simultaneous sintering, and a concave groove 16 for preventing the resin 4 from coming off is provided on the inner peripheral surface of the terminal lead-out hole 11. By doing so, the explosion-proof filter 3 is firmly joined to the explosion-proof case 1 by simultaneous sintering, and the resin 4 is also prevented from coming off with sufficient strength. Has sufficient strength. In addition, by using a sintered metal filter as the explosion-proof filter 3, a sufficient fire propagation preventing function can be obtained even in the ventilation portion for introducing the external gas, and therefore, the ignition to the external explosive atmosphere is ensured. Will be prevented. That is, the explosion-proof gas sensor of the present invention is an explosion-proof gas sensor having a high explosion-proof property while having a compact structure with a small number of parts as described above.

本発明は、コンパクトで部品点数の少ない構造であっても高い防爆性を具備する防爆型ガスセンサを提供することができるという効果を奏するものである。   The present invention provides an effect that it is possible to provide an explosion-proof gas sensor having a high explosion-proof property even with a compact structure having a small number of parts.

本発明を添付図面に示す実施形態に基いて説明する。図１には、本発明の実施の形態における一例の防爆型ガスセンサを示している。図示のように、本例の防爆型ガスセンサは、両端の開口した円筒型の防爆ケース１内に、ガス感応体２０を有し端子ピン２１を突設してあるセンサ本体２を収容し、センサ本体２のガス感応体２０を防爆ケース１の一端側の開口穴である通気穴１０と対向させ、センサ本体２の端子ピン２１を防爆ケース１の他端側の開口穴である端子導出穴１１から外部に導出した構造のものである。そして、防爆ケース１の通気穴１０を円盤状の防爆フィルタ３で塞ぎ、端子導出穴１１を樹脂４の注入により封止することで、防爆ケース１内で爆発が生じた場合であっても、外部の爆発性雰囲気にまで引火をすることがないようにしている。   The present invention will be described based on embodiments shown in the accompanying drawings. FIG. 1 shows an example of an explosion-proof gas sensor according to an embodiment of the present invention. As shown in the figure, the explosion-proof gas sensor of the present example accommodates a sensor body 2 having a gas sensitive body 20 and protruding terminal pins 21 in a cylindrical explosion-proof case 1 opened at both ends. The gas sensitive body 20 of the main body 2 is opposed to the vent hole 10 which is an opening hole on one end side of the explosion-proof case 1, and the terminal pin 21 of the sensor main body 2 is a terminal lead-out hole 11 which is an opening hole on the other end side of the explosion-proof case 1. The structure is derived from the outside. And even if an explosion occurs in the explosion-proof case 1 by closing the vent hole 10 of the explosion-proof case 1 with a disk-shaped explosion-proof filter 3 and sealing the terminal lead-out hole 11 by injection of the resin 4, It does not ignite even outside explosive atmosphere.

以下、更に詳細な構成について説明する。図２には、本例のセンサ本体２を示している。本例のセンサ本体２は半導体ガスセンサであって、例えばＳｎＯ２のような金属酸化物半導体２２内にヒータ兼用電極コイル２３を埋設し、このヒータ兼用電極コイル２３の内部に検知電極２４を設けることでガス感応体２０を形成したものである。ヒータ兼用電極コイル２３の両端と検知電極２４とは、樹脂ベース２５に植設させてある三本の端子ピン２１の先端部２１ａにそれぞれ接続させてあり、この樹脂ベース２５やガス感応体２０を筒状の金属製パッケージ２６により覆っている。金属製パッケージ２６にはガス導入用の開口部２７を設けており、この開口部２７からメッシュ２８を介して金属パッケージ２６内に侵入したガスがガス感応体２０と接触するようになっている。また、樹脂ベース２５からは端子ピン２１の他方の先端部２１ｂが外部に突出している。 Hereinafter, a more detailed configuration will be described. FIG. 2 shows the sensor body 2 of this example. The sensor body 2 of this example is a semiconductor gas sensor, and a heater / electrode coil 23 is embedded in a metal oxide semiconductor 22 such as SnO 2 and a detection electrode 24 is provided inside the heater / electrode coil 23. The gas sensitive body 20 is formed. Both ends of the heater combined electrode coil 23 and the detection electrode 24 are respectively connected to the tip portions 21a of the three terminal pins 21 implanted in the resin base 25. The resin base 25 and the gas sensitive body 20 are connected to each other. Covered by a cylindrical metal package 26. The metal package 26 is provided with an opening 27 for introducing gas, and gas that has entered the metal package 26 through the mesh 28 through the opening 27 comes into contact with the gas sensitive body 20. Further, the other end portion 21 b of the terminal pin 21 protrudes from the resin base 25.

図３には、本例の防爆ケース１を示している。本例の防爆ケース１は、通気穴１０と端子導出穴１１とを有する金属製（例えばＳＵＳ３０４）の筒状部材であって、防爆ケース１内部の通気穴１０と端子導出穴１１とを連通させる部分が、センサ本体２を収容する内部空間１２となっている。防爆ケース１の内周壁の内部空間１２と通気穴１０との境界部分には、防爆フィルタ３の周縁部と当りこれと接合される突部１３を、全周に亘り形成している。なお、本例の防爆フィルタ３としては図４に示すような円盤状を成す焼結金属フィルタを用いている。焼結金属フィルタは例えばＳＵＳ３１６から形成されるものであり、６０〜７０μｍ程度の孔を有するものが好ましい。また、端子導出穴１１の内周壁の内部側端部には、後述のセンサ基板５の周縁部と当りこれを位置決めする段部１４を形成しており、端子導出穴１１の内周壁の外部側端部には、後述の端子ピン支持基板６の周縁部と当りこれを位置決めする段部１５を形成している。そして、端子導出穴１１の内周壁の、両段部１４，１５に挟まれる部分には、樹脂４を抜け止めする為の凹溝１６を形成している。凹溝１６は、リング状を成すように全周に亘り凹設したものであり、軸方向に所定間隔を隔てた二箇所にこれを形成している。   FIG. 3 shows an explosion-proof case 1 of this example. The explosion-proof case 1 of this example is a metal (for example, SUS304) cylindrical member having a vent hole 10 and a terminal lead-out hole 11, and communicates the vent hole 10 and the terminal lead-out hole 11 inside the explosion-proof case 1. The portion is an internal space 12 that houses the sensor body 2. At the boundary portion between the inner space 12 of the inner peripheral wall of the explosion-proof case 1 and the vent hole 10, a projecting portion 13 that contacts the peripheral portion of the explosion-proof filter 3 and is joined thereto is formed over the entire circumference. As the explosion-proof filter 3 of this example, a sintered metal filter having a disk shape as shown in FIG. 4 is used. The sintered metal filter is formed of, for example, SUS316, and preferably has a hole of about 60 to 70 μm. Further, a stepped portion 14 is formed at the inner side end portion of the inner peripheral wall of the terminal lead-out hole 11 and a peripheral portion of the sensor board 5 described later to position the same, and the outer side of the inner peripheral wall of the terminal lead-out hole 11 At the end portion, a stepped portion 15 is formed which contacts a peripheral portion of a terminal pin support substrate 6 which will be described later and positions it. A concave groove 16 for preventing the resin 4 from coming off is formed in a portion of the inner peripheral wall of the terminal lead-out hole 11 between the step portions 14 and 15. The concave groove 16 is recessed over the entire circumference so as to form a ring shape, and is formed at two positions spaced apart from each other in the axial direction.

図５に示すように、円盤状を成すセンサ基板５には延長用の端子ピン５０を三本突設しており、センサ本体２から突出した三本の端子ピン２１の先端部２１ｂを、センサ基板５に三箇所設けてある端子穴５１にそれぞれ挿通して半田付けすることで、センサ本体２の端子ピン２１と延長用の端子ピン５０とがセンサ基板５に形成された導電パターン（図示せず）を介して一対一で電気的に接続されるようになっている。また、図６に示すように円盤状を成す端子ピン支持基板６には、センサ基板５から突出した延長用の端子ピン５０を挿通させてこれを支持する為の挿通穴６０と、樹脂注入穴６１と、この樹脂注入穴６１よりも小径の空気抜き穴６２とを貫設している。   As shown in FIG. 5, the sensor board 5 having a disk shape is provided with three terminal pins 50 for extension, and the tip portions 21b of the three terminal pins 21 protruding from the sensor main body 2 are connected to the sensor substrate 5 as shown in FIG. Conductive patterns (not shown) in which the terminal pins 21 of the sensor body 2 and the terminal pins 50 for extension are formed on the sensor substrate 5 by being inserted and soldered into the terminal holes 51 provided in three places on the substrate 5 respectively. 1) through the electrical connection. Further, as shown in FIG. 6, the terminal pin support substrate 6 having a disk shape is inserted with an extension terminal pin 50 protruding from the sensor substrate 5 and supported therethrough, and a resin injection hole 61 and an air vent hole 62 having a smaller diameter than the resin injection hole 61 are provided.

本例の防爆型ガスセンサを組立てるにあたっては、防爆ケース１の通気穴１０に外部側から防爆フィルタ３を嵌入させて、この防爆フィルタ３の外周面が通気穴１０の内周面と当接し、且つ、防爆フィルタ３の内部側を向く円盤面の周縁部分が突部１３の外向き面１３ａと当接する状態とし、同時焼結によってこの防爆フィルタ３と防爆ケース１とを接合させておく。なお、ここで行う同時焼結とは、圧粉体である防爆フィルタ３を防爆ケース１に当てた状態で焼結させると同時に防爆ケース１に接合させる技術のことである。そして、センサ本体２の端子ピン２１をセンサ基板５の端子穴５１に嵌め込むことでセンサ本体２とセンサ基板５とを一体化させ、これを、センサ本体２部分が内部空間１２内に収納されるように端子導出穴１１側から防爆ケース１内に挿入すると、センサ基板５の周縁部が段部１４に当ることで、防爆ケース１内でのセンサ基板５及びセンサ本体２の位置決めがなされる。次に、端子ピン支持基板６を、センサ基板５の端子ピン５０に挿通穴６０を嵌め込みながら段差１５と当るまで端子導出穴１１内に挿入していくことで、センサ本体２とセンサ基板５と端子ピン支持基板６とが一体化された状態で防爆ケース１内に収容されるものである。このとき、端子導出穴１１内のセンサ基板５と端子ピン支持基板６とで挟まれる空間が、樹脂４が注入される樹脂注入空間７となる。この樹脂注入空間７は、端子ピン支持基板６の樹脂注入穴６１と空気抜き穴６２とを介して外部と連通する以外は密閉された空間である。端子ピン支持基板６からは挿通穴６０を通して延長用の端子ピン５０が外部に向けて突出しており、本例においてはこの端子ピン５０を介してセンサ本体２の端子ピン２１が端子導出穴１１から外部に導出された状態となっている。この状態で、端子ピン支持基板６の樹脂注入穴６１に例えば熱硬化性エポキシ樹脂である樹脂４を注入すると、空気抜き穴６２から内部の空気を抜きながら樹脂封入空間７内に樹脂４が充填されてゆく。そして、樹脂注入空間７内に隙間なく樹脂４が注入された後に該樹脂４を硬化させることで、端子導出穴１１が確実に封止されるものである。   In assembling the explosion-proof gas sensor of this example, the explosion-proof filter 3 is inserted into the ventilation hole 10 of the explosion-proof case 1 from the outside, and the outer peripheral surface of the explosion-proof filter 3 is in contact with the inner peripheral surface of the ventilation hole 10. The peripheral portion of the disk surface facing the inside of the explosion-proof filter 3 is brought into contact with the outward surface 13a of the protrusion 13, and the explosion-proof filter 3 and the explosion-proof case 1 are joined by simultaneous sintering. The simultaneous sintering performed here is a technique in which the explosion-proof filter 3 that is a green compact is sintered in a state where it is applied to the explosion-proof case 1 and simultaneously bonded to the explosion-proof case 1. Then, the sensor body 2 and the sensor substrate 5 are integrated by fitting the terminal pins 21 of the sensor body 2 into the terminal holes 51 of the sensor substrate 5, and the sensor body 2 portion is accommodated in the internal space 12. When inserted into the explosion-proof case 1 from the terminal lead-out hole 11 side, the sensor board 5 and the sensor body 2 are positioned in the explosion-proof case 1 by the peripheral edge of the sensor board 5 coming into contact with the stepped portion 14. . Next, the terminal pin support substrate 6 is inserted into the terminal lead-out hole 11 until the terminal pin support substrate 6 contacts the step 15 while fitting the insertion hole 60 into the terminal pin 50 of the sensor substrate 5. The terminal pin support substrate 6 is accommodated in the explosion-proof case 1 in an integrated state. At this time, a space between the sensor substrate 5 and the terminal pin support substrate 6 in the terminal lead-out hole 11 becomes a resin injection space 7 into which the resin 4 is injected. This resin injection space 7 is a sealed space except that it communicates with the outside through the resin injection hole 61 and the air vent hole 62 of the terminal pin support substrate 6. An extension terminal pin 50 protrudes outward from the terminal pin support substrate 6 through an insertion hole 60, and in this example, the terminal pin 21 of the sensor body 2 extends from the terminal lead-out hole 11 through the terminal pin 50. It is in a state derived to the outside. In this state, when the resin 4 which is, for example, a thermosetting epoxy resin is injected into the resin injection hole 61 of the terminal pin support substrate 6, the resin 4 is filled into the resin enclosure space 7 while the air is extracted from the air release hole 62. Go. Then, after the resin 4 is injected into the resin injection space 7 without any gap, the resin lead 4 is hardened, so that the terminal lead-out hole 11 is reliably sealed.

上記構成を備えた本例の防爆型ガスセンサにあっては、焼結金属フィルタである防爆フィルタ３を介して外部のガスを防爆ケース１内に導入し、これをセンサ本体２のガス感応体２０と接触させて、金属酸化物半導体２２に埋設してある電極２３，２４間の抵抗値の変化を基に検知対象ガスを検知するものである。更に、本例のガスセンサ本体２においては、ヒータ兼用電極２３への印加電圧の制御により金属酸化物半導体２２の温度をガス検知時よりも高く設定して金属酸化物半導体２２に付着した吸着ガスを一旦取り除くクリーニング期間を設けており、このような高温のクリーニング期間と低温のガス検知期間とを交互に繰返して検知対象ガスの濃度変化を精度良く検知するようになっている。このようにヒータ兼用電極２３による加熱を行い、特にクリーニング期間に高温に維持されるものである場合には、爆発性雰囲気が存在する危険場所に設置するにあたって高い防爆性が求められるが、本例においては上記したように、防爆フィルタ３として焼結金属フィルタを用い、これを同時焼結により防爆ケース１と接合させるとともに、端子導出穴１１の内周面に樹脂４を抜け止めする為の凹溝１６を設けた構造としていることで、コンパクトで部品点数の少ない構造でありながら高い防爆性を具備した防爆型ガスセンサとなっている。即ち、本例の防爆型ガスセンサは、凹溝１６を設けた端子導出穴１１内に注入された樹脂４が、凹溝１６と嵌合する凸部４１を有した形状で硬化し、この凹溝１６と凸部４１との嵌合によって内部での爆発に対しても十分な強度で樹脂４が抜け止めされることとなり、内部の爆発に対する十分な強度を有することとなる。ここで、凹溝１６を形成せずに同程度の強度を備えようとする場合と比べると、樹脂４の注入部分ひいては防爆ケース１全体の軸方向の寸法を小さく形成することができる。また、防爆フィルタ３も同時焼結により防爆ケース１と強固に接合されることから内部の爆発に対する十分な強度を有することとなる。そして、このように防爆ケース１自体の破損が十分に防止されていることに加えて、防爆フィルタ３として焼結金属フィルタを用いたことで防爆フィルタ３の通気部分においても十分な火災伝播防止機能が得られ、したがって外部の爆発性雰囲気への引火が確実に防止されるものである。しかも、凹溝１６を設ける等の簡単な構造で済むことから防爆ケース１自体もコンパクトに形成され、部品点数も少なくて済むものである。   In the explosion-proof gas sensor of the present example having the above-described configuration, an external gas is introduced into the explosion-proof case 1 through the explosion-proof filter 3 that is a sintered metal filter, and this gas sensor 20 of the sensor body 2 is introduced. The gas to be detected is detected based on the change in resistance value between the electrodes 23 and 24 embedded in the metal oxide semiconductor 22. Further, in the gas sensor main body 2 of this example, the temperature of the metal oxide semiconductor 22 is set higher than that at the time of gas detection by controlling the voltage applied to the heater electrode 23, and the adsorbed gas adhering to the metal oxide semiconductor 22 is reduced. A cleaning period that is once removed is provided, and the high temperature cleaning period and the low temperature gas detection period are alternately repeated to detect the concentration change of the detection target gas with high accuracy. When heating is performed by the heater combined electrode 23 and maintained at a high temperature especially during the cleaning period, high explosion-proof properties are required for installation in a dangerous place where an explosive atmosphere exists. As described above, a sintered metal filter is used as the explosion-proof filter 3, and this is joined to the explosion-proof case 1 by simultaneous sintering, and a recess for preventing the resin 4 from coming off from the inner peripheral surface of the terminal lead-out hole 11. The structure provided with the groove 16 is an explosion-proof gas sensor having a high explosion-proof property while having a compact structure with a small number of parts. That is, in the explosion-proof gas sensor of this example, the resin 4 injected into the terminal lead-out hole 11 provided with the concave groove 16 is cured in a shape having a convex portion 41 that fits into the concave groove 16. The resin 4 is prevented from coming off with sufficient strength against the internal explosion by the fitting of the protrusion 16 and the convex portion 41, so that the resin 4 has sufficient strength against the internal explosion. Here, as compared with the case where it is intended to provide the same level of strength without forming the concave groove 16, the injection portion of the resin 4 and thus the axial dimension of the entire explosion-proof case 1 can be made smaller. Further, since the explosion-proof filter 3 is firmly joined to the explosion-proof case 1 by simultaneous sintering, the explosion-proof filter 3 has sufficient strength against internal explosion. In addition to the fact that the explosion-proof case 1 itself is sufficiently prevented from being damaged in this way, the use of a sintered metal filter as the explosion-proof filter 3 enables a sufficient fire propagation prevention function even in the ventilation portion of the explosion-proof filter 3. Therefore, ignition to an external explosive atmosphere is surely prevented. In addition, since a simple structure such as the provision of the concave groove 16 is sufficient, the explosion-proof case 1 itself can be formed compactly and the number of parts can be reduced.

次に、本発明の実施の形態における他例の防爆型ガスセンサについて説明するが、一例と同様の構成については説明を省略して、一例と異なる特徴的な構成についてのみ以下に述べる。図７に示すように、本例の防爆型ガスセンサの防爆ケース１には、その外周面の軸方向中央部分に、Ｏリング８が嵌合される断面略半円状の凹溝１７を全周に亘り形成している。図中の９０は、端子ピン５０が接続される基板９を収納する所定機器のハウジングであり、このハウジング９０に貫設してある取付け穴９１に本例の防爆ガスセンサを装着した状態において、凹溝１７に嵌合してあるＯリング８が取付け穴９０の内周面と弾接して、防爆ケース１を防爆フィルタ３側が外部に突出した状態で確実に保持するものである。   Next, another example of the explosion-proof gas sensor according to the embodiment of the present invention will be described, but the description of the same configuration as the example will be omitted, and only the characteristic configuration different from the example will be described below. As shown in FIG. 7, the explosion-proof case 1 of the explosion-proof gas sensor of this example has a substantially semicircular concave groove 17 into which the O-ring 8 is fitted in the central portion of the outer peripheral surface in the axial direction. It is formed over. Reference numeral 90 in the figure denotes a housing of a predetermined device that accommodates the substrate 9 to which the terminal pins 50 are connected. In the state where the explosion-proof gas sensor of this example is mounted in the mounting hole 91 penetrating the housing 90, The O-ring 8 fitted in the groove 17 is in elastic contact with the inner peripheral surface of the mounting hole 90 to securely hold the explosion-proof case 1 with the explosion-proof filter 3 side protruding outward.

次に、本発明の実施の形態における更に他例の防爆型ガスセンサについて説明するが、他例と同様の構成については説明を省略して、他例と異なる特徴的な構成についてのみ以下に述べる。図８に示すように、本例の防爆型ガスセンサの防爆ケース１には、その外周面の軸方向中央部分に、貫通穴１９を有するフランジ状の固定片１８を突設している。本例のハウジング９０には、取付け穴９１の近傍に貫通穴９２を設けており、ハウジング９０の取付け穴９１に本例の防爆ガスセンサを装着した状態において、固定片１８の貫通穴１９とハウジング９０の貫通穴９２とが連通するようになっている。そして、この連通する貫通穴１９，９２内に固定具９３を挿入固定することで、防爆ケース１を防爆フィルタ３側が外部に突出した状態で確実に保持するものである。   Next, a further example of the explosion-proof gas sensor according to the embodiment of the present invention will be described, but the description of the same configuration as the other example will be omitted, and only the characteristic configuration different from the other example will be described below. As shown in FIG. 8, in the explosion-proof case 1 of the explosion-proof gas sensor of this example, a flange-shaped fixing piece 18 having a through hole 19 is provided in a projecting manner at the axial center portion of the outer peripheral surface. The housing 90 of this example is provided with a through hole 92 in the vicinity of the mounting hole 91, and the through hole 19 of the fixing piece 18 and the housing 90 are mounted in a state where the explosion-proof gas sensor of this example is mounted in the mounting hole 91 of the housing 90. The through hole 92 communicates with each other. Then, the fixing tool 93 is inserted and fixed in the communicating through holes 19 and 92, thereby securely holding the explosion-proof case 1 with the explosion-proof filter 3 side protruding outside.

本発明の実施の形態における一例の防爆型ガスセンサを示しており、（ａ）は正面図、（ｂ）は側断面図、（ｃ）は底面図である。1 shows an example of an explosion-proof gas sensor according to an embodiment of the present invention, where (a) is a front view, (b) is a side sectional view, and (c) is a bottom view. 同上の防爆型ガスセンサのセンサ本体を示しており、（ａ）は正面図、（ｂ）は側面図、（ｃ）は底面図である。The sensor main body of the explosion-proof type gas sensor same as the above is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. 同上の防爆型ガスセンサの防爆ケースを示しており、（ａ）は正面図、（ｂ）は側断面図、（ｃ）は底面図である。The explosion-proof case of the same explosion-proof gas sensor is shown, (a) is a front view, (b) is a side sectional view, and (c) is a bottom view. 同上の防爆型ガスセンサの防爆フィルタを示しており、（ａ）は側面図、（ｂ）は正面図である。The explosion-proof filter of the same explosion-proof gas sensor is shown, (a) is a side view, and (b) is a front view. 同上の防爆型ガスセンサのセンサ基板を示す正面図である。It is a front view which shows the sensor board | substrate of an explosion-proof gas sensor same as the above. 同上の防爆型ガスセンサの端子ピン支持基板を示す正面図である。It is a front view which shows the terminal pin support substrate of an explosion-proof type gas sensor same as the above. 本発明の実施の形態における他例の防爆型ガスセンサの装着状態を示す説明図である。It is explanatory drawing which shows the mounting state of the other explosion-proof gas sensor in embodiment of this invention. 本発明の実施の形態における更に他例の防爆型ガスセンサの装着状態を示す説明図である。It is explanatory drawing which shows the mounting state of the further explosion-proof type gas sensor in embodiment of this invention. 従来の防爆型ガスセンサを示す説明図である。It is explanatory drawing which shows the conventional explosion-proof type gas sensor.

符号の説明Explanation of symbols

１ 防爆ケース
２ センサ本体
３ 防爆フィルタ
４ 樹脂
１０ 通気穴
１１ 端子導出穴
１２ 内部空間
１６ 凹溝
２０ ガス感応体
DESCRIPTION OF SYMBOLS 1 Explosion-proof case 2 Sensor body 3 Explosion-proof filter 4 Resin 10 Vent hole 11 Terminal lead-out hole 12 Internal space 16 Concave groove 20 Gas sensitive body

Claims (1)

内部空間と連通した通気穴と端子導出穴とを有する金属製の防爆ケースの前記内部空間内にセンサ本体を収容し、通気穴を防爆フィルタで塞ぐとともに、端子導出穴を樹脂注入により封止して成る防爆型ガスセンサであって、防爆フィルタとして焼結金属フィルタを用い、焼結金属フィルタと防爆ケースとを同時焼結により接合させるとともに、端子導出穴の内周面には樹脂を抜け止めする為の凹溝を設けていることを特徴とする防爆型ガスセンサ。   The sensor body is housed in the internal space of a metal explosion-proof case that has a vent hole communicating with the internal space and a terminal lead-out hole, the vent hole is closed with an explosion-proof filter, and the terminal lead-out hole is sealed by resin injection. An explosion-proof gas sensor using a sintered metal filter as an explosion-proof filter, joining the sintered metal filter and the explosion-proof case by simultaneous sintering, and preventing resin from slipping out to the inner peripheral surface of the terminal lead-out hole Explosion-proof gas sensor, characterized in that a concave groove is provided.
JP2003385601A 2003-11-14 2003-11-14 Explosion-proof gas sensor Expired - Fee Related JP4091902B2 (en)

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JP2007132695A (en) * 2005-11-08 2007-05-31 Riken Keiki Co Ltd Explosion proof type gas sensor
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