Abstract: A refrigerator oil for use in compressors using therein a hydrogen-containing halogenocarbon as a refrigerant, consisting essentially of as a base oil at least one kind of an ester selected from the group consisting of a specific pentaerythritol ester such as an ester of pentaerythritol with a mono- or dicarboxylic acid, a specific polyol ester such as an ester of trimethylolethane with a mono- or dicarboxylic acid, a specific ester such as an ester of ethylene glycol and a dicarboxylic acid, and a specific polyol ester synthesized from a neopentyl type polyhydric alcohol, a monocarboxylic acid and a dicarboxylic acid; and further comprising at least one kind of an epoxy compound.

Abstract: A method for detecting the concentration of a specific component in gas discharged from an internal combustion engine, which includes detecting the concentration of the specific component under certain driving conditions to determine a zero point, which indicates a zero concentration of the specific component, of the detection output; calibrating the detection output of the gas sensor based on the determined zero point; and detecting the concentration of the specific component in exhaust gas based on the calibrated detection output.

Abstract: A hydrogen gas sensor is configured such that an O-ring 21 is disposed within a measurement chamber 11a in order to seal against a first support element 9a and against a proton conduction layer 1. This O-ring 21 assumes the form of a rectangular frame that surrounds a first electrode 3, and a substantially circular cross section, and is elastic, heat resistant, and durable. A first metal plate 23a and a second metal plate 23b are disposed from the outside on opposite support elements 9a and 9b, respectively. The hydrogen gas sensor of the present embodiment has a pair of right-hand and left-hand through-holes 29 formed therein so as to extend along the thickness direction thereof. Bolts 31 are inserted into the corresponding through-holes 29. By fastening the metal plates 23a and 23b from the outside by means of the bolts 31 and nuts 33, the opposite support elements 9a and 9b are fastened, thereby clamping the entire hydrogen sensor in a unitary condition.

Abstract: A gas sensor includes an element case 42 with an internal peripheral surface formed as a taper surface 100. A portion of a housing section 43 surrounded by the taper surface 100 and a protective film 48 is filled with a filler 49. When the filler 49 thermally expands at high temperature, the filler 49 is subjected to a component of force in an upward direction by the taper surface 100. Therefore, projection of an element portion 44 involving deformation of the protective film 48 is suppressed, a change ?L of a propagation distance L to a reflecting section 33 is also suppressed, and a detection accuracy never decreases. In addition, reverberation is reduced.

Abstract: A gas concentration sensor includes a measurement chamber for measuring a concentration of a specific gas component in a gas under measurement; an inflow path for allowing inflow of the gas under measurement thereinto and an outflow path for allowing outflow of the gas under measurement therefrom; a reflection wall for reflecting an acoustic wave; and an acoustic wave transmitting-receiving element having a transmitting-receiving surface adapted to transmit an acoustic wave toward the reflection wall and receive an acoustic wave reflected from the reflection wall. The concentration of the specific gas in the gas under measurement is detected on the basis of a propagation time between transmission of the acoustic wave and reception of the reflected acoustic wave. When a predetermined member having the sensor attached thereto is placed in a horizontal plane, the transmitting-receiving surface faces downward. A recess is formed in a peripheral portion of the reflection wall.

Abstract: An ultrasonic-wave propagation-time measuring method and gas concentration sensor are disclosed in which a reception wave which has been transmitted and received by an ultrasonic element 5 is subjected to full-wave rectification in order to obtain a full-wave-rectified wave, which is then integrated by an integration circuit 37 to obtain an integral value. A peak value of the integral value is held by a peak-hold circuit 39. As to detection of gas concentration, a threshold-level calculation section 21e sets a reference value on the basis of the peak value, and a point in time when the amplitude of a reception wave having undergone full-wave rectification is judged by a comparator 43 to have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is determined on the basis of a period between the emission time and the arrival time.

Abstract: A humidity sensor including an insulating substrate, and a lower electrode formed from a noble metal, a moisture sensitive layer formed of a porous body predominantly containing alumina and containing predetermined amounts of TiO2 and SnO2 and an upper electrode formed of a noble metal porous body successively formed on the insulating substrate. The upper electrode is connected to the moisture sensitive layer and a portion of the insulating substrate. Preferably, the lower electrode is formed of a porous body. More preferably, the lower and upper electrodes are formed from Pt. Furthermore, preferably, a heater and a temperature measurement resistor are provided in the insulating substrate and are located directly below the moisture sensitive layer.

Abstract: Lubricant compositions comprises a lubricant base oil and one or more compounds resulting the modification of a succinimide represented by formula (1) or (2) wherein R1 and R2 may be the same or different and are each independently a hydrocarbon group having 8 to 30 carbon atoms, R3 and R4 may be the same or different and are each independently a hydrocarbon group having 1 to 4 carbon atoms, R5 is hydrogen or a hydrocarbon group having 1 to 30 carbon atoms, n is an integer from 1 to 7. The lubricant compositions have a long-lasting anti-shudder property, an enhanced transmission capacity for a wet clutch, and an excellent shifting property.

Abstract: A humidity-sensitive porous layer (13) of a humidity-sensitive element section (3) of a humidity sensor (1) is formed of a crystalline phase oxide grains such as Al2O3—SnO2—TiO2 and of a glass phase such as silicate glass covering the crystalline phase. The glass phase contains an alkali metal oxide and/or alkaline earth metal oxide such as Li2O. The humidity sensitive porous layer (13) assumes a skeletal structure that is formed of crystalline phase oxide grains covered or coated with the glass phase. A heater (17) of the humidity sensor is controlled to heat the humidity-sensitive element section (3) at a temperature ranging from 500° C. to 800° C. so as to clean off the humidity-sensitive element section while an internal combustion engine is running and exhausting fouling substances.

Abstract: A humidity sensor comprising an insulating substrate, a detection electrodes and a moisture-sensitive layer, wherein the moisture-sensitive layer is a porous layer and has a thickness not greater than 200 &mgr;m.

Abstract: A CO sensor and a CO-concentration measurement method which enables accurate measurement of CO concentration irrespective of the hydrogen concentration of a gas under measurement. By applying a first predetermined voltage between first and second electrodes 7 and 8, hydrogen contained in a gas under measurement which has been introduced into a first measurement space 2 via a first diffusion-controlling section 1 dissociates, decomposes, or reacts with another element to generate protons. The thus-generated protons are transported from the first electrode 7 to the second electrode 8 via a first proton-conductive layer 5 or protons are transported from the second electrode 8 to the first electrode 7 via the first proton-conductive layer 5 (when the hydrogen concentration of the measurement gas is extremely low), so that the hydrogen concentration within the first measurement space 2 is controlled to a constant level.

Abstract: There is provided a gas sensor for measuring the concentration of a specific gas component in a gas under measurement, including a gas diffusion rate limiting portion, a measurement chamber communicating with an atmosphere of the gas under measurement through the gas diffusion rate limiting portion, a sensor element having an ion-conductive layer with first and second surfaces, a first electrode disposed in contact with the first surface of the ion-conductive layer within the measurement chamber and a second electrode disposed in contact with the second surface of the ion-conductive layer and communicating exclusively with the atmosphere of the gas under measurement and a cylindrical support member installing therein the sensor element with the first and second surfaces of the ion-conductive layer directed toward front and base end sides of the support member, respectively.

Abstract: A gas sensor suitable for measuring hydrogen concentration, including a proton conductive layer (1); a first electrode (3) and a second electrode (5) provided on the proton conductive layer (1); a gas diffusion-limiting inlet (19) provided between the first electrode (3) and a measurement gas atmosphere (6) containing hydrogen gas; and a gas diffusion-limiting outlet (21) provided between the second electrode (5) and the atmosphere (6); wherein the ratio (a/b) between the diffusion resistance (a) of the diffusion limiting portion (19) and the diffusion resistance (b) of the gas outlet portion (21) is not greater than 2.

Abstract: In an ammonia sensor (1), lead portions (7) and (9) are provided on an insulating substrate (5); a pair of comb-shaped electrodes (11) and (13) are connected to the lead portions (7) and (9), respectively; a sensitive layer (15) is provided on the comb-shaped electrodes (11) and (13); and a protective layer (17) is provided on the sensitive layer (15). Particularly, the sensitive layer (15) is formed of a gas-sensitive raw material predominantly containing ZrO2 and containing at least W in an amount of 2 to 40 wt. % as reduced to WO3.

Abstract: A method for detecting the concentration of a specific gas (NOx) in an engine exhaust gas using a gas sensor and a process of correcting the gas sensor. According to the correcting process, the amount of moisture in the exhaust gas is estimated, then a a gas concentration detection signal output by the gas sensor on the basis of an estimated amount of moisture is corrected. Finally, the effect of the amount of moisture in the exhaust gas is removed or reduced from the detected value of gas concentration.

Abstract: Method and sensor for measuring accurate measurement of NOx concentration in an exhaust gas containing O2,H2O, CO2 and NOx and a NOx gas concentration sensor. A first oxygen pump cell sufficiently pumps out oxygen in a measurement gas such as not to decompose NOx. A pair of electrodes is provided on an inner side and an outer side of a second measurement chamber into which the gas is introduced from a first measurement chamber via a diffusion resistance. A voltage is impressed across the paired electrodes for decomposing NOx in the second measurement chamber to dissociate oxygen which causes the current to flow in a second oxygen ion pump cell. The NOx gas concentration is measured for this current. The voltage impressed across the paired electrodes of the second oxygen ion pump cell is set so as not to dissociate H2O and CO2 present in the second measurement chamber.

Abstract: A hydrogen gas sensor capable of accurately measuring hydrogen concentration of a measurement gas atmosphere in the presence of a variety of interfering gasses such as H2O and CO. In the hydrogen gas sensor, the flow sectional area of a diffusion-rate limiting portion 6 is rendered small; the electrode surfaces of first and second electrodes 3 and 4 are rendered large; and/or a solution containing a polymer electrolyte which may be identical to that of a proton-conductive layer 2 is applied onto the surfaces of the first and second electrodes 3 and 4 to thereby form a layer containing the polymer electrolyte. Thus, the rate of conduction of protons from the first electrode 3 to the second electrode 4 becomes greater than the rate at which protons are derived from hydrogen which is introduced onto the first electrode 3 via the diffusion-rate limiting portion 6.

Abstract: A detecting-element assembly (40) is configured such that a piezoelectric element (51) is housed in a casing body portion (43) of a casing (42), and is attached to a housing portion (22) of a flow path formation member (20) via a flange portion (41). Therefore, the path between the piezoelectric element (51) and the position of attachment of the detecting-element assembly (40) is elongated, whereby ultrasonic waves which leak into the interior of the detecting-element assembly (40) from the piezoelectric element (51) become unlikely to reflectively return from a joint. Thus, the influence of, for example, noise stemming from reflected waves is reduced, thereby enhancing the accuracy of detection. An average clearance of 1 millimeter or more is provided along the outer circumferential surface of the casing body portion (43) of the detecting-element assembly (40), whereby a problem of collected foreign matter is unlikely to occur.

Abstract: Lubricant compositions comprises a lubricant base oil and one or more compounds resulting the modification of a succinimide represented by formula (1) or (2) 1

Abstract: A gas sensor includes an element case 42 with an internal peripheral surface formed as a taper surface 100. A portion of a housing section 43 surrounded by the taper surface 100 and a protective film 48 is filled with a filler 49. When the filler 49 thermally expands at high temperature, the filler 49 is subjected to a component of force in an upward direction by the taper surface 100. Therefore, projection of an element portion 44 involving deformation of the protective film 48 is suppressed, a change &Dgr;L of a propagation distance L to a reflecting section 33 is also suppressed, and a detection accuracy never decreases. In addition, reverberation is reduced.