Abstract: A flow measurement device is disclosed, in which an accumulation of pollution substance onto a detection element is prevented, and which can measure a reverse flow similarly to a normal flow. On both ends of an outer wall 23 outer peripheral portion of a divided flow pipe 20 having a &OHgr;-shape pipe passage, there are oppositely formed an inlet port 25 and an outlet port 26, which open in faces orthogonal to a flow direction of a main flow M that is a detection object. Within the divided flow pipe 20, by a curved partition 27, plural branch flow passages 28a, 28b mutually branching and joining in the divided flow pipe 20 are formed.

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 hydrogen sensor includes a first electrode 3 and a second electrode 4 provided in contact with a proton conduction layer 2; a gas diffusion controlling portion 6 provided between a measurement gas atmosphere and the first electrode 3; and a support element (1a, 1b) for supporting the proton conduction layer 6, the first electrode 3, the second electrode 4, and the gas diffusion controlling portion 6. Hydrogen contained in a measurement gas introduced via the gas diffusion controlling portion 6 is dissociated, decomposed, or reacted by applying a voltage between the first electrode 3 and the second electrode 4 to thereby generate protons. Hydrogen concentration is obtained on the basis of a limiting current generated as a result of the generated protons being pumped out via the proton conduction layer 2 from the first electrode 3 side of the proton conduction layer to the second electrode 4 side of the proton conduction layer.

Abstract: A split-flow-type flowmeter includes a detection element 2 disposed to face a flow path thereof and a venturi structure 4 formed within a flow path 1 in the vicinity of the detection element 2 and adapted to throttle a flow directed toward the detection element 2 to thereby reduce disturbance of the flow. The venturi structure 4 is disposed in opposition to the detection element 2 within the flow path 1 and includes a protrusion 5 protruding toward the detection element 2 within the flow path 1 of the split-flow-type flowmeter.

Abstract: A piping joint for preventing pipe members laid across the connection end faces of two adjacent structural elements from being damaged by changes in the relative positional relationship between the two adjacent structural elements due to the expansion and contraction caused by changes in the temperature or external stresses. The piping joint connects the end portions of the two pipe members laid in two structural elements whose connection end faces can displace relatively to each other, between the connection end faces to make the two pipe members communicate. It comprises a fixed unit (30) fixedly embedded into the connection end face of one of the structural elements and a movable unit (50) supported by the fixed unit so as to be movable along the connection end face. The pipe member in the structural element is connected to the fixed unit, and the pipe member in the other structural element is connected to the movable element. The two pipe members communicate in the fixed unit.

Abstract: A flow rate and flow velocity measurement device. A part of a flow 10 in a main flow pipe 1, which is a detection object, is introduced into a passage of a divided flow pipe 2 and becomes a flow 11. The divided flow pipe 2 has a curved portion 2c or rather an inverted arc portion in which the flow is abruptly changed in direction or rather inverted by protuberances 2a, 2b formed preferably in symmetry in upstream and downstream sides of the curved portion 2c. Outside the main flow pipe 1, there is disposed on the bottom portion of the curved portion 2c of the divided flow pipe 2 a detection element 5 fixed to a support body 4 while protruding preferably 0.05-0.3 mm from flow passage faces 2e, 2f in the vicinity thereof. An opposed face 2d opposite to the detection element 5 protrudes toward the detection face so as to throttle the passage and to accelerate a flow speed at the element.

Abstract: A flow rate and flow velocity measurement device has a divided flow pipe (332) which is attached so as to be orthogonal to an intake pipe (1) of an engine, and into which a flow in the intake pipe (1) is introduced, an inlet plate (334) which extends in a direction orthogonal to a flow direction in the intake pipe (1) and forms a U-shape form pipe passage in the divided flow pipe (332) and a detection element (331) which is disposed so as to be exposed to a flow in the divided flow pipe (332) outside the intake pipe (1) and detects a flow rate and a flow velocity, wherein one end of the inlet plate (334) protrudes into the intake pipe (1) while passing a top opening of the divided flow pipe (332), and the divided flow pipe (332) has a flow passage structure symmetrical with the detection element (331) being made a center, so that an equivalent detection element (331) output is obtained in regard to both cases in which a fluid flows through the intake pipe (1) in a normal direction and a reverse direction.

Abstract: A piping joint for preventing pipe members laid across the connection end faces of two adjacent structural elements from being damaged by changes in the relative positional relationship between the two adjacent structural elements due to the expansion and contraction caused by changes in the temperature or external stresses. The piping joint connects the end portions of the two pipe members laid in two structural elements whose connection end faces can displace relatively to each other, between the connection end faces to make the two pipe members communicate. It comprises a fixed unit (30) fixedly embedded into the connection end face of one of the structural elements and a movable unit (50) supported by the fixed unit so as to be movable along the connection end face. The pipe member in the structural element is connected to the fixed unit, and the pipe member in the other structural element is connected to the movable element. The two pipe members communicate in the fixed unit.

Abstract: An ohmic electrode for an SiC semiconductor includes a p-type Si layer formed on the surface of a p-type SiC semiconductor, and a metal silicide layer formed on the surface of the Si layer, the metal silicide layer being formed from a metal silicide such as PtSi. The p-type Si layer is preferably formed from p-type Si having a carrier concentration equal to or higher than that of the aforementioned p-type SiC. Preferably, the ohmic electrode is formed as follows: deposition of Si is performed; deposition of a metal silicide is performed by means of laser ablation; laser irradiation is performed to thereby improve ohmic properties and enhance adhesion between the resultant deposition layer and the p-type SiC semiconductor; and then further deposition of the metal silicide is performed by means of laser ablation.

Abstract: A flow rate and flow velocity measurement device. A part of a flow 10 in a main flow pipe 1, which is a detection object, is introduced into a passage of a divided flow pipe 2 and becomes a flow 11. The divided flow pipe 2 has a curved portion 2c or rather an inverted arc portion in which the flow is abruptly changed in direction or rather inverted by protuberances 2a, 2b formed preferably in symmetry in upstream and downstream sides of the curved portion 2c. Outside the main flow pipe 1, there is disposed on the bottom portion of the curved portion 2c of the divided flow pipe 2 a detection element 5 fixed to a support body 4 while protruding preferably 0.05-0.3 mm from flow passage faces 2e, 2f in the vicinity thereof. An opposed face 2d opposite to the detection element 5 protrudes toward the detection face so as to throttle the passage and to accelerate a flow speed at the element.

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.

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 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: When a sensor has deteriorated, the propagation time T1′ of a first reflection wave becomes greater than the propagation time T1 of a first reflection wave as measured in a new sensor. If measurement of the concentration of a specific gas is based on the propagation time T1 of the first reflection wave as measured in the new sensor, gas concentration cannot be determined accurately. By contrast, a reflection wave other than the first reflection wave (for example, a second reflection wave) is merely reflected off the surface of the ultrasonic element and is not affected by the internal structure of the ultrasonic element. Therefore, even when the sensor is deteriorated, the propagation time T2, T2′ of the second reflection wave exhibits less variation and is less susceptible to deterioration of the sensor.

Abstract: A nitrogen oxide concentration detector has a first measurement chamber 2 into which is introduced a measurement gas via a first diffusion resistance 1; an oxygen concentration detection electrode 7a for measuring the oxygen concentration in the measurement gas in said first measurement chamber 1; a first oxygen ion pump cell 6 for pumping out oxygen in the measurement gas from said first measurement chamber 2 based on the potential of said oxygen concentration detection electrode 7a; a second measurement chamber 8 into which the gas is introduced from said first measurement chamber 2 via a second diffusion resistance 3; and a second oxygen ion pump cell 8 having a pair of electrodes 8a,8b across which a voltage is applied to decompose NOx in the second measurement chamber 4 to pump out dissociated oxygen to cause a circuit Ip2 corresponding to the NOx concentration to flow in the second oxygen ion pump cell 8. Variation of NOx concentration is a function of variation of Ip2.

Abstract: A split-flow-type flowmeter in which an end portion of a flow splitter tube 1 is inserted into a main-flow pipe 10 having a diameter D. A flow splitter tube 1 includes a U-shaped split-flow passage 1a. A detection element is disposed at a bottom portion (not shown) of the U-shaped split-flow passage 1a. The split-flow passage 1a assumes a flow path structure symmetrical with respect to a plane passing through the detection element. A flow inlet 2a and a flow outlet 2b of the split-flow passage 1a face in mutually opposite directions along the flow direction of the main-flow pipe 10 and open symmetrically at the same position on the flow cross section of the main-flow pipe 10.

Abstract: A gas sensor having a pn junction including two discrete electrical conductive-type layers, namely, a first semiconductor layer and a second semiconductor layer, disposed in contact with each other. Ohmic electrodes are formed on the respective surfaces of the semiconductor layers. A catalytic layer containing a metallic catalytic component which dissociates hydrogen atom from a molecule having hydrogen atom is formed on one of the ohmic electrodes. The pn junction diode-type gas sensor has a simple constitution, exhibits a small change in diode characteristics with time in long-term service and is capable of detecting a gas concentration of a molecule having a hydrogen atom, for example, H2, NH3, H2S, a hydrocarbon and the like, contained in a sample gas.

Abstract: A nitrogen oxide concentration detector has a first measurement chamber 2 into which is introduced a measurement gas via a first diffusion resistance 1; an oxygen concentration detection electrode 7a for measuring the oxygen concentration in the measurement gas in said first measurement chamber 1; a first oxygen ion pump cell 6 for pumping out oxygen in the measurement gas from said first measurement chamber 2 based on the potential of said oxygen concentration detection electrode 7a; a second measurement chamber 8 into which the gas is introduced from said first measurement chamber 2 via a second diffusion resistance 3; and a second oxygen ion pump cell 8 having a pair of electrodes 8a,8b across which a voltage is applied to decompose NOx in the second measurement chamber 4 to pump out dissociated oxygen to cause a current Ip2 corresponding to the NOx concentration to flow in the second oxygen ion pump cell 8. Variation of NOx concentration is a function of variation of Ip2.

Abstract: An apparatus and method using a two-serial space sensor (having first and second internal spaces 2,3) for accurately measuring NOx concentration in gas, e.g., exhausted from an internal combustion engine. Both NOx (nitrogen oxide) and oxygen are forced to be partially dissociated in the first space 2 to an oxygen concentration level of 2×10−7 to 2×10−10 atm by pumping out oxygen from the first space 2. The NOx concentration is determined based on the second current measured in the second space 4 and based on the NO dissociation percentage in the first chamber which is 0.5-50%, or preferably 2-20%. The NOx measurement accuracy is further improved when the above oxygen concentration level is maintained from 2×10−8 to 2×10−9 and the temperature drift of the sensor is maintained within ±5° C. under a sensor temperature range of 700-900° C.

Abstract: A method of manufacturing a gas sensor, including a substrate electrode layer forming step, and a surface electrode layer forming step. The gas sensor includes first and second processing spaces, an oxygen concentration detection element, an oxygen pumping element, an oxidation catalyst and a combustible gas component concentration detection element.