TW202011020A - Gas detection device having exceptional humidity resistance and exceptional sensitivity - Google Patents
Gas detection device having exceptional humidity resistance and exceptional sensitivity Download PDFInfo
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本發明是關於一種具備氣體感測器之氣體偵測裝置，該氣體感測器係具有：加熱器部位、藉由與偵測對象氣體接觸而改變特性之氣體偵測部位、以及覆蓋該氣體偵測部位的至少一部分之觸媒部位，對前述加熱器部位通電而將前述氣體偵測部位及前述觸媒部位加熱並偵測前述偵測對象氣體。The invention relates to a gas detection device equipped with a gas sensor, the gas sensor having: a heater part, a gas detection part whose characteristics are changed by contacting with the gas to be detected, and a gas detection covering the gas detection part The catalyst part of at least a part of the measurement part energizes the heater part to heat the gas detection part and the catalyst part and detect the gas to be detected.
這樣的氣體偵測裝置揭示於專利文獻1、專利文獻2。 以下，以該等文獻所記載的氣體偵測裝置為一例來做說明。 氣體偵測裝置係具備：氣體感測器、用於將該氣體感測器進行加熱驅動之加熱控制部、以及用於偵測氣體偵測部位的特性改變之氣體偵測部，利用加熱控制部來控制加熱器部位所進行的加熱，將氣體偵測部位及設置於其表面側之觸媒部位加熱到對應於偵測對象氣體的種類之適切溫度而進行氣體的偵測。Such a gas detection device is disclosed in
偵測對象氣體係包含：甲烷(CH4 )、丙烷(C3 H8 )等的可燃性氣體，一氧化碳(CO)、氫(H2 )等的還原性氣體。The gas system to be detected includes flammable gases such as methane (CH 4 ) and propane (C 3 H 8 ), and reducing gases such as carbon monoxide (CO) and hydrogen (H 2 ).
在實施氣體偵測時，加熱控制部是對加熱器部位進行脈衝通電，而將氣體偵測部位及觸媒部位加熱。在本說明書的圖4(a)(b)(c)，將其加熱形態用加熱驅動信號表示。圖4(a)(b)係顯示偵測對象氣體為可燃性氣體的情況之加熱驅動信號，圖4(c)係顯示偵測對象氣體為可燃性氣體及還原性氣體的情況。 從圖4(a)可明白，對加熱器部位之通電係包含：實行通電之氣體偵測工序Ts、及接續於該氣體偵測工序Ts而進行之加熱休止工序Tr，以既定的氣體偵測周期Rt反覆進行氣體偵測。 偵測對象氣體的偵測，大致是如這些圖式的黑圈所示般，在即將停止通電之前進行。When implementing gas detection, the heating control unit pulses the heater to energize the gas detection part and the catalyst part. In FIG. 4(a)(b)(c) of this specification, the heating form is represented by a heating drive signal. Fig. 4(a)(b) shows the heating drive signal when the detection target gas is a flammable gas, and Fig. 4(c) shows the case where the detection target gas is a flammable gas and a reducing gas. As can be understood from FIG. 4(a), the energization of the heater part includes: a gas detection process Ts that performs energization, and a heating rest process Tr that is performed in succession to the gas detection process Ts to detect with a predetermined gas Gas detection is performed repeatedly in the cycle Rt. The detection of the target gas is roughly performed as shown by the black circles in these figures, just before the power is turned off.
在實施可燃性氣體的偵測時，如圖4(a)(b)所示般成為高溫加熱(High)，將成為偵測的干擾氣體之雜訊氣體(noise gases)在觸媒部位進行燃燒除去。 代表性的干擾氣體為氫(H2 )、乙醇(C2 H5 OH)、一氧化碳(CO)，因為具有這樣的功能，觸媒部位也稱為氧化觸媒層。在高溫加熱狀態下，可偵測通過觸媒部位而到達氣體偵測部位之難燃性的可燃性氣體(代表性的氣體為甲烷)。When the detection of flammable gas is carried out, it becomes high temperature heating (High) as shown in FIG. 4(a)(b), and the noise gas which becomes the detected interference gas is burned in the catalyst part Remove. Representative interference gases are hydrogen (H 2 ), ethanol (C 2 H 5 OH), and carbon monoxide (CO). Because of such a function, the catalyst site is also called an oxidation catalyst layer. Under the condition of high temperature heating, it can detect the inflammable flammable gas (the representative gas is methane) that reaches the gas detection part through the catalyst part.
圖4(c)所示的加熱驅動形態，是接續於高溫加熱(High)進行低溫加熱(Low)的形態，在即將停止低溫加熱(Low)的通電之前進行還原性氣體(代表性的氣體為一氧化碳)的偵測。The heating driving form shown in FIG. 4(c) is a form in which low-temperature heating (Low) is performed in succession to high-temperature heating (High), and a reducing gas (typical gas is Carbon monoxide) detection.
如圖4(a)所示般，氣體偵測工序Ts是以既定的氣體偵測周期Rt反覆進行，在氣體偵測工序Ts間之加熱休止工序Tr，對加熱器部位的通電成為停止(off)。 氣體感測器，當其為被加熱部的熱容量小且加熱響應性高之可脈衝加熱驅動之氣體感測器的情況，在氣體偵測工序Ts的通電，成為將其通電時間設定為0.05秒~0.5秒左右的形態，該脈衝通電是隔著加熱休止工序Tr而以20秒~60秒左右的氣體偵測周期反覆，藉此可實現省電的驅動。亦即，在本例，氣體偵測工序Ts之加熱採用脈衝加熱，將該脈衝加熱隔著加熱休止工序Tr而以既定的氣體偵測周期Rt反覆。 在這樣的情況，加熱休止工序Tr的時間壓倒性的長，氣體感測器僅在極短時間被加熱。 這樣的氣體感測器，基於其熱容量低等的理由，用於氣體偵測之加熱驅動可採用所謂脈衝加熱，而成為可使用電池作為電源之省電的氣體偵測裝置。As shown in FIG. 4(a), the gas detection process Ts is repeated with a predetermined gas detection cycle Rt, and the heating stop process Tr between the gas detection processes Ts turns off the power to the heater. ). When the gas sensor is a gas sensor that can be driven by pulse heating with a small heat capacity of the heated portion and a high heating response, the energization time in the gas detection step Ts is set to 0.05 seconds In the form of ~0.5 seconds, the pulse energization is repeated with a gas detection period of about 20 seconds to 60 seconds through the heating stop process Tr, thereby achieving power-saving driving. That is, in this example, the heating of the gas detection process Ts uses pulse heating, and the pulse heating is repeated at a predetermined gas detection cycle Rt across the heating rest process Tr. In such a case, the time of the heating stop process Tr is overwhelmingly long, and the gas sensor is heated only for a very short time. Such a gas sensor is based on the reason that its heat capacity is low, and the heating drive for gas detection can use so-called pulse heating, which becomes a power-saving gas detection device that can use a battery as a power source.
在專利文獻1介紹進行氣體偵測裝置之預防維持的技術，在專利文獻2介紹，抑制氣體偵測層的吸濕而維持高靈敏度之薄膜氣體感測器。 若與到此為止所介紹之先前技術中使用的用語之對應以(專利文獻1的用語、專利文獻2的用語)表示，則氣體偵測部位成為(偵測層57、氣體偵測層5)，觸媒部位成為(選擇燃燒層58、氣體選擇燃燒層5d)。
根據這些專利文獻揭示的技術可明白，這種氣體偵測裝置所具備的氣體感測器，作為觸媒部位是採用：在氧化鋁(Al2
O3
)載體上載持鈀(Pd)或鉑(Pt)作為觸媒金屬而構成的燒結材。 再者，在專利文獻2所欲解決的問題是針對濕度所造成之氣體感測器的經年劣化，如其說明書之圖1所示般係採用吸濕抑制驅動。It can be understood from the technology disclosed in these patent documents that the gas sensor provided in this gas detection device is used as a catalyst part: supporting palladium (Pd) or platinum (Al 2 O 3 ) on a carrier of aluminum oxide (Al 2 O 3 ) Pt) A sintered material constituted as a catalyst metal. In addition, the problem to be solved in
[專利文獻1]日本特開2013-190232號公報 [專利文獻2]日本特開2007-24509號公報[Patent Document 1] Japanese Patent Application Publication No. 2013-190232 [Patent Document 2] Japanese Patent Application Publication No. 2007-24509
[發明所欲解決之問題][Problems to be solved by the invention]
本發明之發明人等，調查在家庭廚房、餐廳廚房等之濕度高的環境下所使用之氣體偵測裝置的氣體感測器，發現有甲烷靈敏度降低的疑慮。 專利文獻2所揭示的技術，雖提出在這種濕度高的環境下使用氣體偵測裝置的情況可採用之一對策，但必須在加熱休止工序中進行吸濕抑制驅動，並不符合獲得省電的氣體偵測裝置之目的。 再者，考慮到對於偵測對象氣體之感測器靈敏度，其靈敏度是越高越好，根據這次進行之發明人等的探討得知，關於以往的氧化鋁載體之氣體感測器尚有改善的餘地。The inventors of the present invention investigated the gas sensor of a gas detection device used in a high-humidity environment such as a home kitchen, a restaurant kitchen, etc., and found that there is a concern that methane sensitivity is reduced. The technology disclosed in
本發明是有鑑於上述問題而開發完成的，其目的是關於在家庭廚房、餐廳廚房等之濕度高的環境下所使用之氣體偵測裝置，為了提供一種耐濕性優異且靈敏度方面也優異的氣體偵測裝置。 進一步是獲得可在這樣的氣體偵測裝置使用之氣體感測器。 [解決問題之技術手段]The present invention was developed in view of the above problems, and its object is to provide a gas detection device used in a high humidity environment such as a home kitchen, a restaurant kitchen, etc., in order to provide an excellent moisture resistance and excellent sensitivity Gas detection device. is to obtain a gas sensor that can be used in such a gas detection device. [Technical means to solve the problem]
本發明的第1特徵構造，係具備氣體感測器之氣體偵測裝置，該氣體感測器係具有：加熱器部位、藉由與偵測對象氣體接觸而改變特性之氣體偵測部位、以及覆蓋該氣體偵測部位的至少一部分之觸媒部位，對前述加熱器部位通電而將前述氣體偵測部位及前述觸媒部位加熱並偵測前述偵測對象氣體， 前述觸媒部位，是在以過渡金屬氧化物為主成分之載體上，載持以鉑為主成分之觸媒金屬而構成。A first characteristic structure of the present invention is a gas detection device provided with a gas sensor, the gas sensor having: a heater portion, a gas detection portion whose characteristics are changed by contact with a gas to be detected, and The catalyst part covering at least a part of the gas detection part is energized to the heater part to heat the gas detection part and the catalyst part and detect the gas to be detected. The catalyst part is used to The carrier of the transition metal oxide as the main component is formed by supporting a catalytic metal mainly composed of platinum.
發明人等苦心探究的結果得知，以往的氣體偵測裝置之歷時的靈敏度變動之主要原因在於，在觸媒部位之作為載體的主成分、即氧化鋁上之水分吸附及蓄積。氧化鋁載體與水的相互作用很強，不僅短期內就會吸附羥基(OH基)而使化學吸附水增加，且會蓄積無法在加熱時完全趕走之水分子(物理吸附水)，逐漸地物理吸附水會和氧化鋁反應而形成水合物，導致氧化鋁變質。 結果，作為用於燃燒還原性氣體等的干擾氣體之觸媒部位的功能、以及氣體偵測功能會改變。此外，起因於水分的吸附及蓄積，氧化鋁會變質而使其表面上所載持之鈀等的觸媒金屬之分散狀態變差，造成觸媒金屬的表面積減少，同樣的使其作為觸媒部位的功能劣化，變得無法回復(不可逆變化)。 再者，使得溫度無法上昇到為了對偵測對象氣體進行偵測所必需的溫度。可推測，應是基於這些的主要原因，使對於上述偵測對象氣體之靈敏度發生歷時變化。As a result of painstaking investigations by the inventors, it has been known that the main reason for the change in the sensitivity of the conventional gas detection device over time is the adsorption and accumulation of moisture on alumina, which is the main component of the catalyst, which is a carrier. The interaction between the alumina carrier and water is very strong. Not only will the hydroxyl group (OH group) be adsorbed in a short period of time, which increases the chemically adsorbed water, but also will accumulate water molecules (physically adsorbed water) that cannot be completely removed when heated, and gradually Physically adsorbed water reacts with alumina to form hydrates, which causes the alumina to deteriorate. As a result, the function of the catalyst site used to disturb the reducing gas such as the reducing gas and the gas detection function will change. In addition, due to the adsorption and accumulation of water, alumina will deteriorate and the dispersion state of the catalytic metal such as palladium supported on the surface will deteriorate, resulting in a reduction in the surface area of the catalytic metal. The function of the part deteriorates and becomes irreversible (irreversible change). Furthermore, the temperature cannot be raised to the temperature necessary to detect the gas to be detected. It can be speculated that the sensitivity to the gas to be detected changes over time due to these main reasons.
如此般「觸媒的載體與水之相互作用對甲烷之歷時的靈敏度變動造成影響」的認知，乃是前所未見的全新認知。 基於這些全新的認知，發明人等針對觸媒部位的載體材質進行探討，而選定過渡金屬氧化物作為載體的主成分。 一般而言，作為過渡金屬氧化物的代表例、即氧化鋯，因為其比表面積比氧化鋁小，作為觸媒部位的載體，並不是迄今為止被積極採用的物質。氧化鋁的比表面積為約120m2 /g，相對於此，氧化鋯為約30m2 /g而存在約4倍的差距。以往，因為表面積越大其與氣體進行相互作用的面積越大，當作為觸媒部位的載體來使用的情況，是認為氧化鋁作為觸媒部位的性能高，氧化鋯的性能較低。The cognition that "the interaction between the carrier of the catalyst and water affects the sensitivity change of methane over time" is a new cognition that has never been seen before. Based on these new knowledge, the inventors discussed the carrier material of the catalyst site and selected transition metal oxide as the main component of the carrier. In general, zirconia, which is a typical example of transition metal oxides, has a smaller specific surface area than alumina, and is not a substance that has been actively adopted so far as a carrier for catalyst sites. The specific surface area of aluminum oxide is about 120 m 2 /g, compared with about 30 m 2 /g for zirconia, and there is a gap of about 4 times. In the past, because the larger the surface area, the larger the area where it interacts with the gas, when it is used as a carrier for the catalyst site, it is considered that the performance of alumina as the catalyst site is high and the performance of zirconia is low.
然而，發明人等抗拒這樣的以往認知，相對於使用氧化鋁作為載體，是使用氧化鋯及氧化鈦作為載體，進行調查空氣中的水分所造成的影響之實驗(後述[高濕暴露實驗])而確認出，比起氧化鋁，氧化鋯及氧化鈦縱使在高濕中也不容易發生靈敏度變動。此外也確認出，比起氧化鋁，氧化鋯及氧化鈦縱使在高濕環境下仍能控制靈敏度降低。這些應都是因為氧化鋯及氧化鈦與水間的相互作用較小所造成，此效果在同樣是與水間的相互作用小之過渡金屬氧化物中也是同樣的。於是使用過渡金屬氧化物作為觸媒部位的載體而完成本發明。However, the inventors have resisted such conventional knowledge that, compared to using alumina as a carrier, zirconia and titania are used as a carrier to conduct experiments to investigate the effects of moisture in the air (later [high humidity exposure experiment]) However, it was confirmed that zirconia and titania are less prone to change in sensitivity than alumina even under high humidity. In addition, it has been confirmed that zirconia and titania can control the decrease in sensitivity even in a high-humidity environment compared to alumina. These should be caused by the small interaction between zirconia and titanium oxide and water, and this effect is also the same in transition metal oxides that also have small interaction with water. Thus, the present invention was completed using a transition metal oxide as a carrier of a catalyst site.
再者，關於感測器靈敏度，經由發明人等此次的探討得知，縱使是採用同一觸媒金屬的情況，僅將觸媒部位的載體從氧化鋁改變成過渡金屬氧化物，就能使靈敏度提高，藉由將觸媒組成最佳化能使靈敏度更加提高。此外，當載體採用氧化鋯的情況，作為觸媒金屬之鉑顯現高靈敏度。Furthermore, regarding the sensitivity of the sensor, the inventors have learned from this discussion that even if the same catalyst metal is used, only the carrier at the catalyst site can be changed from alumina to transition metal oxide. Sensitivity can be improved by optimizing the catalyst composition. In addition, when the carrier uses zirconia, platinum as a catalyst metal exhibits high sensitivity.
因此，依據本構成，作為使用氣體感測器來進行氣體偵測之氣體偵測裝置，該氣體感測器係具備加熱器部位、氣體偵測部位、觸媒部位，例如關於在家庭廚房、餐廳廚房等之濕度高的環境下所使用之氣體偵測裝置，可獲得耐濕性優異且能維持高靈敏度之氣體偵測裝置。Therefore, according to this configuration, as a gas detection device that uses a gas sensor for gas detection, the gas sensor is provided with a heater part, a gas detection part, and a catalyst part, for example, in a home kitchen, a restaurant A gas detection device used in a high-humidity environment such as a kitchen can obtain a gas detection device excellent in humidity resistance and capable of maintaining high sensitivity.
該氣體偵測裝置所使用的氣體感測器具備以下的構成。The gas sensor used in the gas detection device has the following configuration.
一種氣體感測器，係具有：加熱器部位、藉由與偵測對象氣體接觸而改變特性之氣體偵測部位、以及覆蓋該氣體偵測部位的至少一部分之觸媒部位， 前述觸媒部位，是在以過渡金屬氧化物為主成分之載體上，載持以鉑為主成分之觸媒金屬。A gas sensor includes: a heater part, a gas detection part whose characteristics are changed by contacting with the gas to be detected, and a catalyst part covering at least a part of the gas detection part, the aforementioned catalyst part, It is a catalyst metal containing platinum as the main component on a carrier containing transition metal oxide as the main component.
因此，如本發明之第2特徵構成所載，作為載體的主成分之前述過渡金屬氧化物，可採用氧化鋯及氧化鈦之任一方或雙方。Therefore, as described in the second characteristic configuration of the present invention, either or both of zirconia and titania can be used as the transition metal oxide as the main component of the carrier.
本發明的第3特徵構成，在前述觸媒部位，在作為前述載體之過渡金屬氧化物上載持0.3質量%~9質量%的鉑作為前述觸媒金屬。According to a third characteristic configuration of the present invention, at the catalyst site, 0.3% by mass to 9% by mass of platinum is supported on the transition metal oxide as the carrier as the catalyst metal.
依據本構成，作為載體是使用過渡金屬氧化物，藉此可獲得耐濕性，且如隨後[甲烷靈敏度實驗]所說明般，作為觸媒金屬是採用鉑，比起使用氧化鋁作為載體的情況，可獲得高靈敏度的氣體偵測裝置。在此，關於鉑的載持濃度，未達0.3質量%時無法獲得充分的選擇氧化能力，高於9質量%時氧化能力變得過高，甚至連甲烷都在觸媒進行燃燒。According to this configuration, a transition metal oxide is used as a carrier to obtain moisture resistance, and as explained later in [Methane Sensitivity Experiment], platinum is used as a catalyst metal, compared to the case of using alumina as a carrier , A highly sensitive gas detection device can be obtained. Here, regarding the supported concentration of platinum, sufficient selective oxidation ability cannot be obtained when it is less than 0.3% by mass, and when it exceeds 9% by mass, the oxidation capacity becomes too high, and even methane is combusted in the catalyst.
本發明的第4特徵構成，作為前述觸媒金屬，除了前述主成分之鉑以外，還含有鈀及銥之任一方或雙方。According to a fourth characteristic configuration of the present invention, as the catalyst metal, in addition to platinum as the main component, either or both of palladium and iridium are contained.
依據本構成，在與鉑的組合中，混合鈀、銥而成的複合物同樣的可獲得選擇氧化性，而能獲得靈敏度良好的氣體偵測裝置。According to this configuration, in the combination with platinum, a compound formed by mixing palladium and iridium can also obtain selective oxidizability, and can obtain a gas detection device with good sensitivity.
本發明的第5特徵構成，係將氣體偵測工序和非偵測工序反覆進行而偵測前述偵測對象氣體，該氣體偵測工序，是對前述加熱器部位通電而將前述氣體偵測部位及前述觸媒部位加熱並偵測前述偵測對象氣體；該非偵測工序，是將前述氣體偵測部位及前述觸媒部位的溫度設定成比前述氣體偵測工序中之兩部位的溫度更低的狀態。A fifth characteristic configuration of the present invention is to repeatedly perform a gas detection process and a non-detection process to detect the gas to be detected, and the gas detection process is to energize the heater part to turn the gas detection part And the catalyst part heats and detects the detection target gas; the non-detection process is to set the temperature of the gas detection part and the catalyst part to be lower than the temperature of the two parts in the gas detection process status.
在本構成中，氣體偵測裝置是將氣體偵測工序和非偵測工序反覆進行，在非偵測工序中，將氣體偵測部位及觸媒部位的溫度設定成比氣體偵測工序中之兩部位的溫度更低的狀態，例如，能夠在雖尚未到達可進行氣體偵測的溫度但可降低水的影響之溫度，將氣體偵測部位及觸媒部位進行管理。In this configuration, the gas detection device repeats the gas detection process and the non-detection process. In the non-detection process, the temperatures of the gas detection site and the catalyst site are set to be higher than those in the gas detection process. The state where the temperature of the two parts is lower, for example, can manage the gas detection part and the catalyst part at a temperature that can reduce the influence of water although it has not reached the temperature where gas detection is possible.
這樣的非偵測工序，例如可將加熱休止(通電停止)、加熱(通電)以任意形態進行組合來實現。在此，若將兩部位的溫度管理成作為本發明的目的之不容易受到水的影響之狀態，可有效阻止此次發明人全新發現之水合物的生成。如此，在抑制電力消耗的狀態下，可長壽命地維持高靈敏度。Such a non-detection process can be realized by combining heating stop (power-off stop) and heating (power-on) in any form. Here, if the temperature of the two parts is controlled to be in a state that is not easily affected by water, which is the object of the present invention, the generation of hydrates newly discovered by the inventors can be effectively prevented. In this way, the high sensitivity can be maintained for a long life while the power consumption is suppressed.
此動作雖是與先前所說明之吸濕抑制驅動類似的動作，但在本發明中，因為構成觸媒部位之載體是以過渡金屬氧化物作為主成分，比起前述文獻所揭示之吸濕抑制驅動，能讓其加熱程度降低、或是加熱頻率降低。結果，能夠實現富含實用性之氣體偵測裝置。Although this operation is similar to the operation of the moisture absorption suppression drive described previously, in the present invention, since the carrier constituting the catalyst site uses the transition metal oxide as the main component, compared with the moisture absorption suppression disclosed in the aforementioned documents Driven, it can reduce the heating degree or the heating frequency. As a result, a gas detection device rich in practicality can be realized.
本發明的第6特徵構成，係將氣體偵測工序和小加熱工序反覆進行而偵測前述偵測對象氣體，該氣體偵測工序，是對前述加熱器部位通電而將前述氣體偵測部位及前述觸媒部位加熱並偵測前述偵測對象氣體；該小加熱工序，是將前述氣體偵測部位及前述觸媒部位以比前述氣體偵測工序中之兩部位的溫度更低的溫度進行通電。A sixth characteristic configuration of the present invention is to repeatedly perform a gas detection process and a small heating process to detect the gas to be detected. The gas detection process is to energize the heater part to turn the gas detection part and The catalyst part heats and detects the gas to be detected; the small heating process energizes the gas detection part and the catalyst part at a temperature lower than the temperature of the two parts in the gas detection process .
在氣體偵測工序之間隔著小加熱工序，氣體偵測部位及觸媒部位不是加熱到可進行氣體偵測的溫度，而是成為比常溫更為加熱之加熱狀態(例如50℃左右)，可減少本發明中作為課題之水對觸媒部位的影響。 此外，藉由將其加熱量減小，還能將電力消耗降低。Between the gas detection process and a small heating process, the gas detection part and the catalyst part are not heated to a temperature where gas detection can be performed, but become a heating state that is more heated than normal temperature (for example, about 50°C). Reduce the effect of water, which is a subject of the present invention, on the catalyst site. In addition, by reducing the amount of heating, it can also reduce power consumption.
本發明的第7特徵構成，係將氣體偵測工序和加熱休止工序反覆進行而偵測前述偵測對象氣體，該氣體偵測工序，是對前述加熱器部位通電而將前述氣體偵測部位及前述觸媒部位加熱並偵測前述偵測對象氣體；該加熱休止工序，是將對前述加熱器部位的通電停止。A seventh characteristic configuration of the present invention is to repeatedly perform a gas detection step and a heating stop step to detect the gas to be detected. The gas detection step is to energize the heater part to turn the gas detection part and The catalyst part heats and detects the gas to be detected; the heating stop process stops the energization of the heater part.
藉由採用此構成，不用在不需要的時點將氣體感測器加熱，可更省電地進行氣體偵測。By adopting this configuration, it is not necessary to heat the gas sensor at an unnecessary time, and gas detection can be performed with more power saving.
在此應可理解，水對觸媒部位造成的影響，在氣體偵測工序中不容易發生。在該工序中，氣體偵測部位及觸媒部位被充分加熱，水附著於觸媒部位的情況很少。It should be understood here that the influence of water on the catalyst site is not likely to occur in the gas detection process. In this process, the gas detection site and the catalyst site are sufficiently heated, and water rarely adheres to the catalyst site.
相對於此，在加熱休止工序中，對加熱器部位的通電停止，各部位的溫度急劇降低到常溫。因此，例如，在進行脈衝加熱而周期性地進行氣體偵測之氣體偵測裝置，氣體感測器僅被瞬間加熱，通常是處於大受水的影響之環境(特別是溫濕度環境)下。結果，應容易發生歷時的先前所說明之問題。這個想法，根據在先前所介紹之專利文獻2中也進行之吸附抑制驅動的工序就是本發明的加熱休止工序，也能獲得支持。On the other hand, in the heating stop process, the energization to the heater part is stopped, and the temperature of each part drops sharply to normal temperature. Therefore, for example, in a gas detection device that performs pulse detection and periodically performs gas detection, the gas sensor is only heated instantaneously, usually under an environment greatly affected by water (especially a temperature and humidity environment). As a result, it should be prone to problems that have been previously explained over time. This idea can also be supported according to the process of the adsorption suppression drive which is also performed in
然而，在本發明，作為觸媒部位之載體主成分是使用過渡金屬氧化物，作為觸媒金屬的主成分是使用鉑，藉此可不受水的影響而進行高靈敏度的氣體偵測。However, in the present invention, the main component of the carrier of the catalyst site is a transition metal oxide, and the main component of the catalyst metal is platinum, whereby high-sensitivity gas detection can be performed without being affected by water.
本發明的第8特徵構成，前述氣體偵測工序中之加熱時間是比前述加熱休止工序的加熱停止時間短。According to an eighth characteristic configuration of the present invention, the heating time in the gas detection step is shorter than the heating stop time in the heating stop step.
藉由採用此構成，加熱時間縮短，可抑制消耗電力並進行高靈敏度的氣體偵測。By adopting this configuration, the heating time is shortened, power consumption can be suppressed, and high-sensitivity gas detection can be performed.
本發明的第9特徵構成是至少實行基本加熱形態，在該基本加熱形態，至少前述氣體偵測工序中的加熱是加熱時間0.05秒~0.5秒之脈衝加熱，且將該脈衝加熱隔著前述加熱休止工序而以20秒~60秒的氣體偵測周期反覆進行。 基本加熱形態是指，除了基於偵測遲延對策、誤報抑制、故障診斷、性能提高目的之定期或不定期地脫離上述加熱條件的情況以外之通常的加熱方法。A ninth characteristic configuration of the present invention is to implement at least a basic heating form. In this basic heating form, at least the heating in the gas detection step is pulse heating with a heating time of 0.05 seconds to 0.5 seconds, and the pulse heating is separated by the heating. The process is stopped and the gas detection cycle is repeated from 20 seconds to 60 seconds. Basic heating form refers to a general heating method except for the case where the above-mentioned heating conditions are regularly or irregularly deviated from the purpose of detection delay countermeasures, false alarm suppression, fault diagnosis, and performance improvement.
依據此構成，可進行更加抑制消耗電力之氣體偵測。 在本發明的構成，例如，縱使是利用電池驅動來進行甲烷偵測的情況，仍能在氣體偵測裝置所要求之既定期間良好地進行氣體偵測。According to this configuration, gas detection that further suppresses power consumption can be performed. In the configuration of the present invention, for example, even if methane detection is performed by battery driving, gas detection can be performed well within a predetermined period required by the gas detection device.
本發明的第10特徵構成，係包含高溫加熱工序，該高溫加熱工序，是在前述偵測對象氣體的偵測時，將前述氣體偵測部位及前述觸媒部位加熱到甲烷偵測用的溫度。A tenth characteristic configuration of the present invention includes a high-temperature heating process that heats the gas detection site and the catalyst site to a temperature for methane detection when the gas to be detected is detected .
依據本構成，可耐濕性佳且高靈敏度地進行作為偵測對象氣體中的一種之對於天然瓦斯(天然氣)漏氣偵測非常重要的甲烷偵測。According to this configuration, methane detection, which is one of the detection target gases and is very important for natural gas (natural gas) leak detection, can be performed with high humidity resistance and high sensitivity.
針對本實施形態的氣體偵測裝置100，參照圖1做說明。 氣體偵測裝置100係具有：感測器元件20(氣體感測器的一例)、加熱控制部12及氣體偵測部13。 氣體偵測裝置100，在裝設了電池15的狀態下，可從該電池15獲得電力而對偵測對象氣體進行偵測。The
感測器元件20係具有隔膜構造之所謂省電氣體感測器。從圖1可知，感測器元件20，係在隔膜構造的支承層5上具備加熱器層6(加熱器部位的一例)、氣體偵測層10(氣體偵測部位的一例)及觸媒層11(觸媒部位的一例)。因此，觸媒層11成為暴露於周圍環境的構造，偵測對象氣體是通過該觸媒層11而到達氣體偵測層10。到達後的偵測對象氣體，是與該層10接觸而讓其特性改變。在此的特性，具體而言可列舉電阻值或電壓值。The
氣體偵測裝置100，是利用加熱控制部12對加熱器層6進行通電，將氣體偵測層10加熱到按照偵測對象氣體的種類之適切溫度，在保持該溫度的狀態下，根據氣體偵測層10的特性變化來對偵測對象氣體進行偵測。The
觸媒層11，在進行甲烷偵測時，是藉由加熱器層6以300℃以上進行高溫加熱(圖4(a)(b)(c)之High)，讓一氧化碳、氫等的還原性氣體及其他干擾氣體燃燒，並讓活性低的甲烷透過、擴散而到達氣體偵測層10。藉此將甲烷的偵測精度提高。The
附帶一提，在進行一氧化碳偵測時，藉由加熱器層6以50℃~250℃進行低溫加熱(圖4(c)之Low)，讓氫等的還原性氣體及其他雜訊氣體燃燒。一氧化碳之一部分雖進行燃燒，但大部分會透過、擴散而到達氣體偵測層10。在該低溫區，活性低之甲烷等並無法由氣體偵測層10偵測。Incidentally, when performing carbon monoxide detection, the
換言之，觸媒層11的功能，是將偵測對象氣體以外之氫氣、乙醇氣體等的干擾氣體(非偵測對象氣體)加熱到適切溫度讓其燃燒而無法到達氣體偵測層10，藉此讓氣體偵測裝置100具有氣體選擇性。再者還具有：對氣體偵測層10的表面供給氧氣而將靈敏度提高的作用。In other words, the function of the
(感測器元件) 感測器元件20係具有支承層5的端部由矽基板1支承之隔膜構造。支承層5，係將熱氧化膜2、氮化矽(Si3
N4
)膜3、氧化矽(SiO2
)膜4依序積層而構成。在支承層5上形成加熱器層6，以覆蓋加熱器層6全體的方式形成絕緣層7，在絕緣層7上形成一對的接合層8，在接合層8上形成電極層(電極的一例)9。加熱器層6，是藉由通電進行發熱而將氣體偵測層10及觸媒層11加熱。感測器元件20亦可採用各層較厚的塊狀(bulk)構造，加熱器層6亦可兼用為電極層。此外，作為支承構造可採用所謂橋接(bridge)構造。(Sensor element) The
在絕緣層7上之一對的電極層9間形成氣體偵測層10。氣體偵測層10是以金屬氧化物為主成分之半導體層。在本實施形態，氣體偵測層10是使用以氧化錫(SnO2
)為主成分之混合物。氣體偵測層10，藉由與偵測對象氣體接觸而使電阻值改變。氣體偵測層10可為厚度0.2~1.6μm左右的薄膜，亦可為具有超過1.6μm的厚度之膜(厚膜)。A
在氣體偵測層10上以覆蓋氣體偵測層10的形態形成觸媒層11。觸媒層11，是在以金屬氧化物為主成分的載體上載持觸媒金屬而構成。該觸媒層11的形成，是讓載持著觸媒金屬之金屬氧化物透過黏結劑(binder)互相結合。The
作為觸媒金屬所採用的金屬，在進行偵測對象氣體的偵測時變成能將可能引起錯誤偵測之干擾氣體(乙醇、氫等的還原性氣體及其他)氧化除去的觸媒。作為觸媒金屬可使用鈀、鉑、銥(Ir)，在本實施形態是包含鈀、鉑、銥當中之至少一者。The metal used as the catalyst metal becomes a catalyst that can oxidize and remove interference gases (reducing gases such as ethanol, hydrogen, etc.) that may cause erroneous detection during the detection of the detection target gas. As the catalyst metal, palladium, platinum, and iridium (Ir) can be used. In this embodiment, at least one of palladium, platinum, and iridium is included.
作為載持觸媒金屬之載體，以往主要是採用氧化鋁。在本實施形態，作為比氧化鋁更不容易在表面產生羥基而能抑制空氣中的水分吸附、蓄積於觸媒層11之材料，是使用氧化鋯。As the carrier supporting the catalytic metal, alumina has been mainly used in the past. In the present embodiment, zirconia is used as a material that is less likely to generate hydroxyl groups on the surface than alumina and can suppress the adsorption of moisture in the air and accumulate in the
讓載體結合之黏結劑，可使用金屬氧化物的微粉末，例如氧化鋯、氧化矽微粉末、氧化矽溶膠、氧化鎂等。如果只是作為黏結劑的微量使用，在不阻害觸媒層11的功能之範圍內，也能使用氧化鋁微粉末或氧化鋁溶膠。As the binding agent for the carrier, fine powders of metal oxides such as zirconia, fine powders of silica, silica sol, magnesium oxide, etc. can be used. If it is used only as a trace amount of binder, alumina fine powder or alumina sol can be used within the range that does not hinder the function of the
觸媒層11，是將載持有金屬氧化觸媒之氧化鋯粉末(粒度為1~10μm左右)和黏結劑及有機溶劑混合而調製成印刷糊(paste)，將該印刷糊利用網版印刷進行印刷，於室溫乾燥後，於500℃進行1小時燒結而形成。觸媒層11的大小設定成可將氣體偵測層10充分覆蓋。如此般利用網版印刷使厚度變薄。如此般形成之氧化鋯燒結體的比表面積為約30m2
/g左右。The
上述的觸媒金屬、作為載體之金屬氧化物、黏結劑都是，可將1種單獨使用，或將2種以上併用。The above-mentioned catalyst metals, metal oxides as carriers, and binders are all used alone, or two or more kinds can be used in combination.
觸媒層11所含之觸媒金屬的量，相對於觸媒金屬和載體的合計質量宜為0.3~9質量%。作為觸媒金屬是使用2種以上的金屬的情況，相對於觸媒金屬和載體的合計質量，觸媒金屬的合計質量宜為0.3~9質量%。 僅實施甲烷偵測的情況，鉑的質量宜為0.3質量%~6質量%。The amount of catalyst metal contained in the
(加熱控制部) 以偵測甲烷之氣體偵測裝置100為例來做說明。如到此為止所說明般，偵測的加熱驅動信號是如圖4(a)(b)所示。 加熱控制部12是進行：對加熱器層6通電之通電動作(進行此通電動作的時點成為本發明的氣體偵測工序Ts)、及不對加熱器層6通電之非通電動作(進行此非通電動作的時點成為本發明的加熱休止工序Tr)。該通電動作(氣體偵測工序Ts)是以氣體偵測周期Rt反覆。亦即，脈衝加熱以氣體偵測周期Rt反覆進行。(Heating Control Unit) Take methane
此外，加熱控制部12是構成為用於讓加熱器層6的溫度變動，而能將加熱器層6的溫度加熱到所設定之任意溫度。 具體而言，加熱控制部12，是接受來自電池15電源之電源供給，對感測器元件20的加熱器層6通電而將感測器元件20加熱。加熱溫度、亦即氣體偵測層10及觸媒層11的到達溫度，是藉由改變例如施加於加熱器層6之電壓來控制。In addition, the
(氣體偵測部) 氣體偵測部13，是在氣體偵測工序Ts之適切時點測定氣體偵測層10的特性變化而對偵測對象氣體進行偵測。在本實施形態的氣體偵測部13，是藉由測定一對的電極層9間之電阻值(特性的一例)來測定氣體偵測層10的電阻值，依據其變化來偵測出偵測對象氣體的濃度。(Gas detection unit) The
(偵測對象氣體的偵測) 接著說明，利用如以上般構成之氣體偵測裝置100來偵測甲烷、丙烷等的可燃性氣體(偵測對象氣體)的情況。(Detection of Gas to be Detected) Next, a description will be given of a case where the
利用加熱控制部12對加熱器層6通電，於0.05秒~0.5秒間將氣體偵測層10及觸媒層11加熱到甲烷偵測用的300℃~500℃。在此期間(宜為圖4(a)(b)之黑圈所示的即將停止通電之前)，氣體偵測部13測定氣體偵測層10的電阻值，根據其值來偵測甲烷、丙烷等的可燃性氣體之濃度。 然後，將對加熱器層6的通電停止。因此，到此為止所說明的氣體偵測工序Ts成為高溫加熱工序。The
在此期間，在成為高溫的觸媒層11，利用觸媒金屬的燃燒觸媒作用，將一氧化碳、氫等的還原性氣體及其他雜訊氣體燃燒。而且，在觸媒層11讓惰性的甲烷、丙烷等之可燃性氣體透過、擴散而到達氣體偵測層10後，和氣體偵測層10之金屬氧化物(氧化錫)進行反應而使電阻值改變。During this period, in the
如以上般，利用氣體偵測裝置100偵測可燃性氣體。 而且，此氣體偵測工序Ts，是以20秒~60秒的氣體偵測周期Rt反覆進行，在氣體偵測工序Ts之後，如前述般將通電停止(off，加熱休止工序Tr)。As described above, the
[高濕暴露實驗] 為了調查載體材料的種類對感測器靈敏度的歷時變動之影響，製作僅改變載體的種類之試樣，測定感測器靈敏度(甲烷靈敏度)的歷時變化。[High Humidity Exposure Test] In order to investigate the effect of the type of carrier material on the change of sensor sensitivity over time, a sample was prepared that only changed the type of carrier, and the change in sensor sensitivity (methane sensitivity) was measured over time.
測定對象為以下3試樣。The measurement objects are the following 3 samples.
(高濕暴露實驗例1) 在作為載體的氧化鋯(ZrO2 )上載持了5質量%的鉑(Pt)及2質量%的銥(Ir)而成的試樣。 (高濕暴露實驗例2) 在作為載體的氧化鈦(TiO2 )上載持了5質量%的鉑(Pt)及2質量%的銥(Ir)而成的試樣。 (高濕暴露實驗例3) 在作為載體的氧化鋁(Al2 O3 )上載持了5質量%的鉑(Pt)及2質量%的銥(Ir)而成的試樣。(Experimental Example 1 of High Humidity Exposure) A sample obtained by supporting 5% by mass of platinum (Pt) and 2% by mass of iridium (Ir) on zirconia (ZrO 2 ) as a carrier. (Experimental Example 2 of High Humidity Exposure) A sample obtained by supporting 5% by mass of platinum (Pt) and 2% by mass of iridium (Ir) on titanium oxide (TiO 2 ) as a carrier. (Experimental Example 3 of High Humidity Exposure) A sample obtained by supporting 5% by mass of platinum (Pt) and 2% by mass of iridium (Ir) on alumina (Al 2 O 3 ) as a carrier.
圖2顯示，進行50℃、60%RH暴露試驗後的試樣之甲烷靈敏度(將在400℃加熱時3000ppm甲烷氣體中的電阻值RCh4除以在400℃加熱時空氣中的電阻值Rair，即RCh4/Rair)的歷時變化。甲烷靈敏度的測定，是在20℃、65%RH清淨空氣中進行。 氣體偵測，是將到此為止所說明的脈衝加熱以氣體偵測周期Rt反覆進行(在後述的甲烷靈敏度實驗，是同樣的)。Figure 2 shows the methane sensitivity of the sample after the 50°C, 60%RH exposure test (the resistance value RCh4 in 3000ppm methane gas when heated at 400°C divided by the resistance value Rair in the air when heated at 400°C, ie RCh4/Rair) changes over time. The measurement of methane sensitivity is performed in clean air at 20°C and 65%RH. Gas detection is to repeat the pulse heating described so far with the gas detection period Rt (the methane sensitivity experiment described later is the same).
如圖2所示般，在載體為氧化鋯或氧化鈦之高濕暴露實驗例1、2，甲烷靈敏度不會發生歷時變化。相對於此，在高濕暴露實驗例3(載體為氧化鋁)，甲烷靈敏度會歷時地降低。As shown in FIG. 2, in the high humidity exposure experiment examples 1 and 2 where the carrier is zirconia or titania, the methane sensitivity does not change over time. On the other hand, in the high humidity exposure experiment example 3 (the carrier is alumina), the sensitivity of methane decreases over time.
發明人等推定其主要原因如下。 觸媒層11與水的相互作用包含以下的3階段。The inventors presume that the main reason is as follows. The interaction between the
(1)短期內吸附OH基而使化學吸附水增加， (2)使無法在加熱時完全趕走的水分子(物理吸附水)蓄積， (3)吸附水與塊體(載體)反應而形成水合物， 共3階段。(1) Adsorption of OH groups in a short period of time increases chemically adsorbed water, (2) accumulates water molecules (physically adsorbed water) that cannot be completely removed when heated, and (3) reacts with adsorbed water and blocks (carriers) to form Hydrate, a total of 3 stages.
在不含加熱休止工序的情況，是以(1)→(3)的步驟進展，在含有加熱休止工序的情況，是以(2)→(3)的步驟進展。因此，當使用與水的相互作用較強之SiO2 、Al2 O3 作為載體的情況，在不含加熱休止工序的情況，在高濕中(1)容易發生，在成為本實施形態的對象之含有加熱休止工序的情況，在高濕中(2)容易發生，會歷時地往(3)轉移，讓偵測對象氣體之靈敏度改變。In the case of not including the heating stop step, the step of (1)→(3) progresses, and in the case of including the heating stop step, the step of (2)→(3) advances. Therefore, when SiO 2 and Al 2 O 3, which have a strong interaction with water, are used as a carrier, (1) is likely to occur in high humidity without the heating stop process, which is the object of this embodiment. Including the heating stop process, it is easy to occur in high humidity (2), and it will shift to (3) over time, so that the sensitivity of the gas to be detected changes.
針對這點，當使用與水的相互作用幾乎不存在之氧化鋯或氧化鈦作為載體的情況，在不含加熱休止工序的情況，縱使在高濕中(1)也不容易發生，在含有加熱休止工序的情況，縱使在高濕中(2)也很少發生。因此，不致歷時地形成水合物，靈敏度變動不會發生。此外，氣體靈敏度也不會取決於濕度。Regarding this point, when using zirconia or titania with almost no interaction with water as a carrier, even if the heating stop process is not included, even in high humidity (1) is not likely to occur. Even if the process is suspended, it rarely occurs even in high humidity (2). Therefore, hydrates are not formed over time, and sensitivity changes do not occur. In addition, gas sensitivity does not depend on humidity.
[甲烷靈敏度實驗] 為了將載體的種類、觸媒金屬的種類、量的不同所造成的甲烷靈敏度進行比較，製作出主要將觸媒金屬的種類、量改變後的19個試樣，測定通常環境下的甲烷靈敏度。 甲烷靈敏度，除了環境條件以外，是與先前在[高濕暴露實驗]所說明的相同。亦即，甲烷靈敏度，是將在400℃加熱時3000ppm甲烷氣體中的電阻值RCh4除以在400℃加熱時的空氣中之電阻值Rair，即RCh4/Rair。 先前在高濕暴露實驗所使用的高濕暴露實驗例1、2，是試樣16、試樣18。 關於作為測定對象之各試樣，整理如下。[Methane Sensitivity Experiment] In order to compare the methane sensitivity caused by the difference in the type of carrier, the type and amount of catalyst metal, 19 samples were prepared after mainly changing the type and amount of catalyst metal, and the normal environment was measured. Under the sensitivity of methane. Sensitivity of methane, except for environmental conditions, is the same as previously explained in [High Humidity Exposure Test]. That is, the methane sensitivity is the resistance value RCh4 in 3000 ppm methane gas when heated at 400°C divided by the resistance value Rair in the air when heated at 400°C, namely RCh4/Rair. Examples 1 and 2 of the high-humidity exposure experiment previously used in the high-humidity exposure experiment are
1.載體的種類 試樣 1~17 氧化鋯 18 氧化鈦 19 氧化鋁 2.觸媒金屬 作為探討對象之觸媒金屬，是鈀(Pd)、銥(Ir)、鉑(Pt)這3種。1. Types of
在以下的表1、2、3、4顯示試樣1~19之觸媒金屬的載持量(質量%)。沒有記載的欄位表示未載持觸媒金屬。Tables 1, 2, 3, and 4 below show the supported amount (mass %) of catalyst metals for
再者，圖3顯示各試樣的甲烷靈敏度。 在圖3的上段標示試樣編號，在圖3的下段標示金屬氧化觸媒的種類及濃度(質量%)。In addition, FIG. 3 shows the methane sensitivity of each sample. The sample number is indicated in the upper part of FIG. 3, and the type and concentration (mass %) of the metal oxidation catalyst are indicated in the lower part of FIG.
結果，比起相當於習知技術之試樣19(氧化鋁載體，7質量%鈀)，僅將載體變更為氧化鋯之試樣17的甲烷靈敏度是上昇的。 兩試樣中的試樣17，縱使在另外進行的高濕暴露實驗，也獲得靈敏度不改變之良好結果。 再者，使用比較對象的氧化鋯作為載體的試樣(1~17)，在所有的試樣中，比起試樣19都是對甲烷具有高靈敏度。 此外，使用比較對象的氧化鈦作為載體之試樣18，比起試樣19是對甲烷具有高靈敏度。 若和先前所說明之高濕暴露實驗例3(氧化鋁載體，5質量%鉑、2質量%銥)做比較，試樣1~18顯現出該高濕暴露實驗例3以上的甲烷靈敏度。As a result, the methane sensitivity of the
作為探討對象的試樣中顯現出特高的甲烷靈敏度者，是使用氧化鋯為載體且觸媒金屬僅由鉑構成之試樣(8及13)。 結果得知，對作為載體的氧化鋯僅使用鉑作為觸媒金屬的組合，是作為氣體感測器的特佳組合。Among the samples to be examined, those exhibiting extremely high methane sensitivity are samples using zirconia as a carrier and the catalytic metal consisting only of platinum (8 and 13). As a result, it is known that the combination of using platinum as the catalyst metal for the zirconia as a carrier is a particularly good combination as a gas sensor.
此外，若將試樣8和試樣13做比較，鉑濃度高的試樣13之甲烷靈敏度變高，鉑濃度越高則甲烷靈敏度越高。另一方面，若將試樣15和試樣16做比較，對於相同的銥濃度，鉑濃度越高則甲烷靈敏度越低。如此，鉑濃度到某個程度的濃度為止，其濃度越高則甲烷靈敏度越高，但超過某個濃度時反而甲烷靈敏度變低，可知為了獲得甲烷高靈敏度是存在適切的濃度範圍。 又當超過某個濃度時甲烷靈敏度降低的原因，應是鉑的氧化活性變高，在觸媒層中甚至連甲烷也進行燃燒氧化。基於以上說明，鉑的濃度較佳為0.3質量%~9質量%，更佳為0.3質量%~6質量%。In addition, if
[其他實施形態] (1)在上述實驗，是用作為可燃性氣體的一例之關於甲烷的實驗例，來說明本發明的意義，如到此為止所說明般，關於丙烷等之低碳數的烴氣的偵測，本發明的氣體偵測裝置也能進行偵測。[Other embodiments] (1) In the above experiment, the experimental example of methane as an example of flammable gas is used to illustrate the significance of the present invention. As explained so far, the low carbon number of propane etc. The detection of hydrocarbon gas can also be detected by the gas detection device of the present invention.
(2)在上述實驗，雖是說明載持觸媒金屬的載體由氧化鋯及氧化鈦構成的例子，但如段落[0016]所說明般，因為過渡金屬氧化物與水的相互作用小，作為載持觸媒金屬的載體可採用過渡金屬氧化物。(2) In the above experiment, although the catalyst metal-supporting carrier is composed of zirconia and titanium oxide, as explained in paragraph [0016], the interaction between the transition metal oxide and water is small, as The carrier carrying the catalyst metal may use a transition metal oxide.
(3)當載體是由過渡金屬氧化物所構成的情況，在上述實驗，雖說明僅由氧化鋯或氧化鈦所構成的例子，但觸媒部位的載體只要以過渡金屬氧化物作為主成分而構成即可。在此，主成分是指50質量%以上(由複數個過渡金屬氧化物構成的情況，其合計質量為50質量%以上)。 再者，關於觸媒金屬，在本發明較佳為，以鉑為主成分，相對於其與載體的合計質量，其觸媒濃度為0.3~9質量%。 在此，以鉑為主成分是指，在前述範圍內載持鉑，當含有其他金屬氧化觸媒(擇自鈀、銥之一種以上)的情況，其含量是比鉑含量少。(3) When the carrier is composed of a transition metal oxide, in the above experiment, although an example composed only of zirconia or titanium oxide is described, the carrier at the catalyst site only needs to have a transition metal oxide as the main component. Just make up. Here, the main component means 50% by mass or more (when it is composed of a plurality of transition metal oxides, the total mass thereof is 50% by mass or more). Furthermore, regarding the catalyst metal, in the present invention, it is preferable that platinum is the main component, and the catalyst concentration is 0.3 to 9% by mass relative to the total mass of the carrier and the carrier. Here, the main component of platinum means that it supports platinum within the aforementioned range, and when it contains other metal oxidation catalysts (selected from one or more of palladium and iridium), its content is less than that of platinum.
(4)在到此為止的說明，主要是說明，用圖4(a)(b)所示的加熱驅動信號來偵測甲烷的情況，但如圖4(c)所示般，在偵測甲烷之後進行一氧化碳偵測亦可，對甲烷和一氧化碳交互進行偵測亦可。在偵測一氧化碳時，是將氣體偵測層10及觸媒層11加熱到50℃~250℃。在此期間(宜為圖4(c)的黑圈所示之即將停止通電之前)，氣體偵測部13測定氣體偵測層10的電阻值，可根據其值來偵測一氧化碳的濃度。 在圖4(c)中，雖是緊接於甲烷的偵測而連續地進行一氧化碳的偵測，但在兩偵測間介入將對加熱器部位的通電停止之加熱休止工序亦可。(4) The description so far is mainly for the purpose of detecting methane using the heating drive signal shown in FIG. 4(a)(b), but as shown in FIG. 4(c) Carbon monoxide detection may be performed after methane, and methane and carbon monoxide may be detected alternately. When detecting carbon monoxide, the
(5)在上述實施形態所說明的情況，在氣體偵測工序Ts之對加熱器部位的通電，是將通電時間設定為0.05秒~0.5秒之脈衝通電，將該脈衝通電隔著加熱休止工序Tr以20秒~60秒的氣體偵測周期Rt反覆進行。 此通電形態，是所謂將脈衝加熱以既定的氣體偵測周期Rt反覆的形態，如先前所說明般，是在通常時成為基本之通電形態的一例。 因此，當有可能實行此基本通電形態而例如偵測甲烷的情況，可將脈衝通電(脈衝加熱)的周期、即氣體偵測周期設定成例如5秒~10秒周期等之任意的短周期。 另一方面，關於氣體偵測工序的加熱時間和加熱休止工序的加熱停止時間之關係，如先前所說明般，基於省電性，較佳為前者比後者短。(5) In the case described in the above embodiment, the energization of the heater portion in the gas detection step Ts is the energization of pulses with the energization time set to 0.05 seconds to 0.5 seconds, and the energization of the pulses through the heating stop step Tr repeats with a gas detection period Rt of 20 to 60 seconds. This energization form is a form in which pulse heating is repeated with a predetermined gas detection period Rt, and as previously described, it is an example of a basic energization form in normal times. Therefore, when it is possible to implement this basic energization form such as the detection of methane, the pulse energization (pulse heating) period, that is, the gas detection period can be set to any short period such as a period of 5 seconds to 10 seconds. On the other hand, regarding the relationship between the heating time of the gas detection step and the heating stop time of the heating stop step, as previously described, it is preferable that the former is shorter than the latter based on power saving.
(6)在上述實施形態所說明的例子，在氣體偵測工序Ts對加熱器部位的通電，是其通電時間設定為0.05秒~0.5秒之脈衝通電，作為脈衝通電時間，當氣體偵測周期Rt為20秒~60秒的情況，其通電時間可為5秒以下。(6) In the example described in the above embodiment, the energization of the heater portion in the gas detection step Ts is a pulse energization whose energization time is set to 0.05 seconds to 0.5 seconds, as the pulse energization time, when the gas detection period When Rt is 20 to 60 seconds, the power-on time can be 5 seconds or less.
(7)再者，在到此為止所示的實施形態中，是在氣體偵測工序Ts之後，實行將加熱休止之加熱休止工序Tr。 然而，根據本發明的趣旨，基於耐濕性的觀點較佳為，在相當於前述加熱休止工序Tr的時間帶，對加熱器部位通電，而將氣體偵測部位及觸媒部位加熱。 於是，在對前述加熱器部位通電而將氣體偵測部位以及觸媒部位加熱並對偵測對象氣體進行偵測的氣體偵測工序之間，可實行小加熱工序Trh，該小加熱工序Trh是加熱到：未達在該氣體偵測工序氣體偵測部位及觸媒部位所到達的溫度之溫度(例如，僅進行甲烷偵測的情況，是未達100℃且比常溫更高的溫度；伴隨一氧化碳偵測的情況，是比該一氧化碳偵測溫度更低的溫度，且未達100℃之比常溫更高的溫度(一氧化碳偵測於100℃進行的情況，是溫度50℃左右的溫度))。圖5顯示實行這樣的小加熱工序的例子。圖5(a)是對應於圖4(a)的說明圖，是接續於氣體偵測工序Ts實行小加熱工序Trh。在該小加熱工序Trh中，進行某種程度的通電而實行某種程度的加熱。圖5(a)所示的例子，是在氣體偵測工序Ts組合接續的小加熱工序Trh而成立氣體偵測周期Rt。圖5(b)(c)都是進行甲烷偵測的例子，圖5(b)顯示，小加熱成為圖5(a)所示之通常時加熱狀態的例子。圖5(c)顯示，小加熱以加熱休止(通電停止)、加熱(通電)的方式進行。(7) Furthermore, in the embodiment shown so far, after the gas detection step Ts, the heating stop step Tr is performed to stop the heating. However, according to the interest of the present invention, from the viewpoint of moisture resistance, it is preferable to energize the heater portion and heat the gas detection portion and the catalyst portion at a time period corresponding to the heating stop step Tr. Therefore, between the gas detection process that energizes the heater part to heat the gas detection part and the catalyst part and detects the gas to be detected, a small heating process Trh can be implemented. The small heating process Trh is Heating up to: the temperature that has not reached the temperature reached by the gas detection part and the catalyst part in the gas detection process (for example, in the case of only methane detection, it is less than 100°C and higher than normal temperature; accompanied In the case of carbon monoxide detection, it is a temperature lower than the carbon monoxide detection temperature, and it is not higher than 100 ℃ than the normal temperature (carbon monoxide detection is performed at 100 ℃, which is about 50 ℃ temperature)) . FIG. 5 shows an example of performing such a small heating process. FIG. 5(a) is an explanatory diagram corresponding to FIG. 4(a), and is a small heating process Trh performed following the gas detection process Ts. In this small heating step Trh, a certain degree of energization is performed to perform a certain degree of heating. In the example shown in FIG. 5(a), a gas detection period Rt is established by combining a small heating step Trh in succession in the gas detection step Ts. 5(b)(c) are all examples of methane detection, and FIG. 5(b) shows an example where the small heating becomes the normal heating state shown in FIG. 5(a). Fig. 5(c) shows that the small heating is performed in such a manner that the heating is stopped (the energization stops) and the heating (the energization) is performed.
亦即，在進行氣體偵測之氣體偵測工序Ts後實行不進行氣體偵測的非偵測工序之構成中，該非偵測工序可設定為加熱休止工序Tr或小加熱工序Trh，在該非偵測工序中，可將加熱休止(通電停止)、加熱(通電)以任意的形態組合，而在該非偵測工序中使氣體偵測部位及觸媒部位的溫度成為比氣體偵測工序中之兩部位的溫度更低的狀態。 在此情況，若將兩部位的溫度維持於不容易受到水的影響之溫度，可阻害水合物的生成。在此之加熱休止(通電停止)、加熱(通電)的組合當然包含：組合時點的選擇、通電量大小的選擇之任一方以上。亦可為歷時地使溫度變化者。 再者，該非偵測工序之溫度管理，可採用任意的手段，例如，可採用與對加熱器部位通電不同的手段。That is, in the configuration of the non-detection process that does not perform gas detection after the gas detection process Ts that performs gas detection, the non-detection process can be set to the heating rest process Tr or the small heating process Trh. In the measurement process, the heating stop (stop of energization) and heating (energization) can be combined in any form, and in this non-detection process, the temperature of the gas detection part and the catalyst part can be higher than that of the gas detection step. The temperature of the part is lower. In this case, if the temperature of the two parts is maintained at a temperature that is not easily affected by water, the formation of hydrates can be hindered. Here, the combination of heating stop (power-off stop) and heating (power-on) includes, of course, one or more of the choice of the combination time and the amount of power supply. It is also possible to change the temperature over time. Furthermore, the temperature management of the non-detection process can adopt any means, for example, a means different from energizing the heater can be used.
(8)在上述實施形態，構成氣體偵測裝置100的一部分之氣體感測器(氣體偵測元件20)的構造，雖是圖1所示般之所謂基板型，但可採用其他構造。例如，不設置覆蓋加熱器層6的絕緣層7，而成為加熱器層6兼作為電極層9的構造亦可。 此外，例如圖6所示般，作為氣體感測器20a亦可構成為，在兼作為電極及加熱器部位之電極線21之線圈22的周圍形成氧化物半導體所構成的氣體偵測部位23，並在其周圍形成觸媒層(觸媒部位)24、25的構造。在此，觸媒層雖是2層，但亦可為單層。在2層的情況，可在層間改變觸媒金屬的比例。在此情況，以鉑為主成分是指，在至少1層中，鉑含量是在上述量的範圍內，且比其他觸媒金屬量更多。 又如圖7所示般，作為氣體感測器20b亦可構成為，在兼作為電極及加熱器部位之電極線31之線圈32的中心配置別的電極33，在線圈32的周圍形成氧化物半導體所構成的氣體偵測部位34，並在其周圍形成觸媒層35。 氣體偵測裝置100只要是具備有氣體感測器，該氣體感測器係具有：加熱器部位、藉由與偵測對象氣體接觸而使特性改變之氣體偵測部位、以及覆蓋該氣體偵測部位的至少一部分之觸媒部位，該氣體偵測裝置是對加熱器部位通電而將氣體偵測部位及觸媒部位加熱並對偵測對象氣體進行偵測即可，並不限定於到此為止所說明的實施形態。(8) In the above embodiment, the structure of the gas sensor (gas detection element 20) forming part of the
(9)再者，在以過渡金屬氧化物為主成分之載體上，載持以鉑為主成分之觸媒金屬而成的觸媒部分，對於氣體偵測部位，只要設置成至少覆蓋其一部分即可。藉由設置這樣的觸媒部位，應可進行干擾氣體的選擇燃燒。(9) Furthermore, on the carrier containing the transition metal oxide as the main component, the catalyst part formed by supporting the catalyst metal containing platinum as the main component, as long as the gas detection part is provided to cover at least a part of it That's it. By setting up such catalyst parts, it should be possible to carry out selective combustion of interfering gases.
1:矽基板2:熱氧化膜3:氮化矽膜4:氧化矽膜5:支承層(基板)6:加熱器層(加熱器部位)7:絕緣層8:接合層9:電極層(電極)10:氣體偵測層(氣體偵測部位)11:觸媒層(觸媒部位)12:加熱控制部13:氣體偵測部15:電池(電源)20:感測器元件(氣體感測器)100:氣體偵測裝置1: silicon substrate 2: thermal oxide film 3: silicon nitride film 4: silicon oxide film 5: support layer (substrate) 6: heater layer (heater part) 7: insulating layer 8: bonding layer 9: electrode layer ( Electrode) 10: Gas detection layer (gas detection part) 11: Catalyst layer (catalyst part) 12: Heating control part 13: Gas detection part 15: Battery (power supply) 20: Sensor element (gas sensing part) Sensor) 100: gas detection device
圖1係顯示氣體偵測裝置的概要。 圖2係顯示在高濕暴露實驗之甲烷靈敏度的歷時變化的曲線圖。 圖3係顯示使用各種觸媒金屬之氣體偵測裝置的靈敏度之比較圖。 圖4(a)~(c)係顯示加熱驅動的形態之說明圖。 圖5(a)~(c)係顯示加熱驅動的其他實施形態之說明圖。 圖6係顯示氣體感測器的其他實施形態。 圖7係顯示氣體感測器的其他實施形態。Figure 1 shows an overview of the gas detection device. Figure 2 is a graph showing the change over time of the methane sensitivity in the high humidity exposure experiment. Figure 3 is a comparison chart showing the sensitivity of gas detection devices using various catalytic metals. Figure 4 (a) ~ (c) is an explanatory diagram showing the form of heating drive. FIG. 5(a) to (c) are explanatory diagrams showing other embodiments of heating and driving. FIG. 6 shows another embodiment of the gas sensor. FIG. 7 shows another embodiment of the gas sensor.
1:矽基板 1: silicon substrate
2:熱氧化膜 2: Thermal oxide film
3:氮化矽膜 3: silicon nitride film
4:氧化矽膜 4: Silicon oxide film
5:支承層(基板) 5: Support layer (substrate)
6:加熱器層(加熱器部位) 6: Heater layer (heater part)
7:絕緣層 7: Insulation
8:接合層 8: junction layer
9:電極層(電極) 9: electrode layer (electrode)
10:氣體偵測層(氣體偵測部位) 10: Gas detection layer (gas detection part)
11:觸媒層(觸媒部位) 11: Catalyst layer (catalyst part)
12:加熱控制部 12: Heating control department
13:氣體偵測部 13: Gas detection department
15:電池(電源) 15: battery (power supply)
20:感測器元件(氣體感測器) 20: Sensor element (gas sensor)
100:氣體偵測裝置 100: gas detection device
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