Ngk Spark Plug Company, Limited

Masaya Watanabe

Shoji Kitanoya

Daisuke Ichikawa

Yusuke Matsukura

Masahiro Yamashita

Noboru Ishida

Norihiko Nadanami

Tomonori Kondo

Ryuji Inoue

Takafumi Oshima

Kaoru Hisada

Toshihiro Matsuno

A gas sensor () including a first gas detection element () and a second gas detection element (), a first storage portion () having a first internal space (A), and a first opening (B) establishing communication between the first internal space (A) and the outside space thereof exposed to a detection subject atmosphere, a second storage portion () having a second internal space (A) and a second opening (B) establishing communication between the second internal space (A) and the outside space, a first membrane (C) allowing permeation of water vapor and substantially not allowing permeation of a detection target gas, and covering the first opening (B), and a calculation unit () for calculating the concentration of a detection target gas contained in the detection subject atmosphere, based on outputs from the first and second gas detection elements (), respectively.

Gas sensor

Disclosed is a gas sensor for detecting a measurement target gas in a measurement gas atmosphere, including first and second sensor elements respectively installed in first and second inner spaces of first and second installation parts. The first and second sensor elements have respective heating resistors connected in series and each has a resistance value that varies with change in temperature thereof so that the concentration of the measurement target gas can be calculated according to a potential between the heating resistors of the first and second sensor elements with the application of a constant voltage. The first and second installation parts are located at such positions that allow a maximum temperature difference of 0.4&#xb0; C. or less between the first and second inner spaces during change in atmosphere temperature from 0&#xb0; C. to 80&#xb0; C.

Disclosed is a gas sensor for detecting a measurement target gas in a measurement gas atmosphere, including: a first sensor element; a first installation part defining a first inner space in which the first sensor element is installed; and a casing accommodating therein the first installation part. The casing has an opening formed to introduce the measurement target gas into an inside of the casing. The first installation part has: a first gas introduction hole formed to provide communication between the first inner space and the inside of the casing; and a membrane member arranged to cover the first gas introduction hole and having permeability to water vapor and substantially no permeability to the measurement target gas. At least a portion of the first installation part in contact with the membrane member is made of insulating ceramic material or resin material.

Disclosed is a gas sensor for detecting hydrogen gas in a measurement gas atmosphere, including: a first installation part defining a first inner space in communication with the measurement gas atmosphere through a solid electrolyte membrane member; a second installation part defining a second inner space in direct communication with the measurement gas atmosphere; first and second sensor elements respectively installed in the first and second inner spaces; and a calculation unit configured to calculate the concentration of the hydrogen gas according to a potential between the first and second sensor elements. The gas sensor further includes a current detecting portion that detects a current flowing through the first and second sensor elements. The calculation unit is configured to, when the current detected by the current detecting portion is larger than or equal to a threshold value, judge that the hydrogen gas is present at high concentration.

A gas detection apparatus () which includes a gas detection element () including a heat generation resistor (); an energization control section () which switches the energization state of the heat generation resistor to alternately assume one of two resistance values corresponding to one of two set temperatures set in advance; and a casing member () which accommodates the gas detection element and has a gas inlet opening (). The gas detection apparatus further includes a humidity computation section () which computes the humidity of the object atmosphere based on a ratio of a high-temperature-time voltage VH to a low-temperature-time voltage VL; and a clogging determination section () which determines the degree of clogging of the gas inlet opening based on a change in the humidity computed by the humidity computation section.

Gas detection apparatus

A gas detector includes a gas detection element having a protection layer formed of an oxide film mainly containing tantalum oxide (TaO). Since the protection layer has excellent condensed-water resistance, even when water droplets adhere thereto, the morphology thereof does not change from dense to porous. Thus, since a change in property of the protection layer, which would otherwise be caused by adhesion of water droplets, can be reduced in the gas detector, even when water droplets adhere to the outermost surface layer of the gas detection element, impurities can be prevented from entering the protection layer (the outermost surface layer), whereby a change in thermal capacity of the gas detection element can be reduced. Thus, the gas detection element of the gas detector has excellent alkali resistance and condensed-water resistance.

Gas detector

A fluid state detection apparatus which can detect a short failure in which a constituent Wheatstone bridge circuit is shorted to a power supply. A combustible gas detection apparatus () judges that a short failure has occurred in a constant temperature control circuit () (S) when a top potential Vis equal to or greater than a first judgment value Vthand a difference D(=V&#x2212;V) is equal to or greater than a second judgment value Vth. As a result, apparatus () can distinguish 'a state in which a bridge circuit () is shorted to a DC power supply () (where the constant temperature control circuitis in a short failure state)' from 'a state in which the resistance of the heat generation resistor () deceases due to a combustible gas (hydrogen)' based on the top potential Vand the difference D

Fluid state detection apparatus

A gas detector includes a detecting element, a circuit board, a housing case having a gas introduction hole, and a metal member which covers the gas introduction hole. The detecting element is disposed under the metal member. The gas detector further includes a detecting element wiring fusing prevention member which is electrically conductive and is electrically connected to a grounding line of the circuit board. The detecting element wiring fusing prevention member is disposed at a position such that the shortest distance between the metal member and the detecting element wiring fusing prevention member is smaller than that between the metal member and the detecting element.

A first bridge fixed resistor () of a combustible gas detection apparatus () is composed of a resistor element which is less likely to deteriorate as compared with a second bridge fixed resistor () and a variable resistor section (). The combustible gas detection apparatus () can judge a deteriorated state of at least one of the second bridge fixed resistor () and the variable resistor section () on the basis of the absolute value of a difference temperature &#x394;T which is the difference between a detection-time judgment temperature Tand a reference judgment temperature T. The combustible gas detection apparatus () obtains a corrected high-temperature-time voltage VH' and a corrected low-temperature-time voltage VL&#x2032; through use of a voltage error &#x394;V. Thus, a decrease in the accuracy in detecting the hydrogen concentration can be suppressed even when the resistance of the resistor section changes.

Gas detector and program

A combustible gas detection device includes an energization control circuit which controls the switching of the energization state of a heat generation resistor every predetermined time period such that the heat generation resistor alternately has resistances corresponding to two predetermined temperatures, a temperature measurement resistor disposed on the same substrate on which the heat generation resistor is disposed, where its resistance changes with the environmental temperature, a gas concentration computation section which calculates the combustible gas concentration by using a voltage generated across the heat generation resistor which is detected when electricity is supplied to the heat generation resistor and the environmental temperature based on a voltage change caused by a change in the resistance of the temperature measurement resistor. The predetermined time period is such that a change in the environmental temperature which occurs when the energization control circuit switches the energization state, falls within a range of 0.5&#xb0; C.

Combustible gas detection device

A flammable gas concentration detection apparatus () including an energization control unit () that switches the energization state of heating resistor () at regular time periods TW, and a gas concentration computation unit (). The heating resistor has first and second set temperatures CH and CL. The voltage detected across the heating resistor at the first and second set temperatures corresponds to a high and low temperature voltage, respectively. The gas concentration computation unit computes the concentration of a flammable gas based on a first information group including an average high temperature voltage averaging the values of two temporally successive high temperature voltages, the low temperature voltage in a period of time between two high temperature voltages, and an environment temperature in the period of time in which the low temperature voltage is detected.

Combustible gas detecting device

A gas detecting apparatus including: a heating resistor exposed to a detected atmosphere, and a control circuit for controlling the heating resistor at two different temperatures, wherein each output voltage from the heating resistor corresponding to the different temperatures is detected when the heating resistor is controlled to the different temperatures, and a state of a gas is obtained based on the detected output voltage. For example, two different offset voltages are set, each potential difference obtained by subtracting each of the offset voltages from corresponding detected output voltages is amplified and the state of the gas is obtained using the amplified potential differences.

Gas detecting apparatus and gas detecting method

There is provided a combustible gas detection apparatus with a gas sensor and a control device. The gas sensor includes first and second heating resistors each having a resistance that changes depending on a combustible gas concentration of gas under measurement. The control device includes an energization control section that alternately energizes the first and second heating resistors, a first calculation section that calculates a first calculation value responsive to the combustible gas concentration based on a voltage across the first heating resistor during energization of the first heating resistor, a second calculation section that calculates a second calculation value responsive to the combustible gas concentration based on a voltage across the second heating resistor during energization of the second heating resistor, and an anomaly judgment section that judges the occurrence of an anomaly in the first heating resistor by comparison of the first and second calculation values.

Combustible gas detection apparatus and combustible gas sensor control method

A gas detector for use in, for example, measuring the concentration of flammable gas or detecting leakage of flammable gas. The gas detector has a gas detection element in which at least a heat-generating resistor and an insulation layer are laminated on a semiconductor substrate made of silicon while the insulation layer encloses the heat-generating resistor. The gas detector detects flammable gas on the basis of temperature and resistance of the heat-generating resistor which vary according to flammable gas. In the gas detection element, a protection layer in the form of a gas impermeable oxide film is provided on its outermost surface which comes into contact with an environmental atmosphere that contains flammable gas. Thus, alkali resistance is ensured. Since the protection layer is impermeable to gas, entry of impurities (organic silicon) contained in the environmental atmosphere into the protection layer is restrained, whereby output is stabilized and becomes accurate.

This invention provides a gas sensor including a proton-conductive polymer electrolyte layer and a method for measuring gas concentration, that are capable of measuring gas concentration at high accuracy notwithstanding the presence of water vapor.

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Komaki, Japan

Masaya Watanabe