Abstract: A flow rate sensor has a problem that a resistance value of a heat generating resistor itself varies and sensor characteristics are changed during use of the sensor for a long term. Also, the temperature of the heat generating resistor must be adjusted on a circuit substrate with a resistance constituting one side of a fixed temperature difference control circuit, and this has been one of factors pushing up the production cost. All resistances used for fixed temperature difference control are formed on the same substrate as temperature sensitive resistors of the same material. This enables all the resistances for the fixed temperature difference control to be exposed to the same environmental conditions. Hence, even when the resistances change over time, the changes over time occur substantially at the same tendency. Since the resistances for the fixed temperature difference control change over time essentially at the same rate, a resulting output error is very small.

Abstract: Resin members, on the surfac s of which metal films are formed, are used for; an auxiliary air passage provided in a main air passage, in which a sensor element of a physical quantity sensor such as an air flow sensor, an intake-air temperature sensor, etc., is situated; a housing; and so forth; in order to decrease both the thermal conductivity and the emissivity of those components to respective small values, whereby the temperature increase of the sensor due to both the heat conduction and the heat radiation can be suppressed.

Abstract: Resin members, on the surfaces of which metal films are formed, are used for; an auxiliary air passage provided in a main air passage, in which a sensor element of a physical quantity sensor such as an air flow sensor, an intake-air temperature sensor, etc., is situated; a housing; and so forth; in order to decrease both the thermal conductivity and the emissivity of those components to respective small values, whereby the temperature increase of the sensor due to both the heat conduction and the heat radiation can be suppressed.

Abstract: A structure is disclosed in which a conductive material having corrosiveness equal to or higher than that of the materials constituting electronics circuitry is disposed on halfway of the diffusion path of corrosive gases between an entrance place thereof and the electronics circuitry, whereby the conductive material traps the corrosive gases.

Abstract: To offer a mass airflow measuring apparatus in which the effect of the adhesion onto the heating resistor caused while the engine is off is reduced and the measuring accuracy is improved. The apparatus measures the mass airflow of the air sucked into the internal combustion engine, using the heating resistor 1. The power control circuit 4 maintains the heating resistor 1 temperature equal to or higher than the temperature during the operation of the internal combustion engine after the internal combustion engine has stopped and until the temperature of the internal combustion engine and its apparatuses installed in the suction system has lowered below the generation temperature of volatile gas such as oil vapor.

Abstract: A support member where a flow amount detection element, which includes a heating resistor and electronic circuit parts for obtaining the air flow amount according to the flow amount signal detected by flow amount detection element are mounted, is cooled from both the direction of the main flow of main passage and the direction of an anti-main flow (i.e., the direction opposite to the direction of the main flow).

Abstract: All independent acoustical physical constants (elastic constants, piezoelectric constants, dielectric constants and density) of a material are predetermined as a function of its chemical composition, and the calibration line between the acoustic velocity for each of the substrate crystal plane, the propagation direction and the propagation mode, and other chemical and physical properties is numerically calculated with ease without making any experiments.

Abstract: A heating resistor type air flow rate measuring apparatus is provided with a couple of heating resistors placed at the positions where those resistors may interfere thermally each other with respect to an air flow, and a couple of driving circuits for driving those heating resistors. The air flow rate signal is obtained by calculating the difference between the output signals of a couple of heating resistors in terms of heat radiation rate effected by an air flow, and adding the difference value onto the output signal of one of heating resistors.

Abstract: To offer a mass airflow measuring apparatus in which the effect of the adhesion onto the heating resistor caused while the engine is off is reduced and the measuring accuracy is improved. The apparatus measures the mass airflow of the air sucked into the internal combustion engine, using the heating resistor 1. The power control circuit 4 maintains the heating resistor 1 temperature equal to or higher than the temperature during the operation of the internal combustion engine after the internal combustion engine has stopped and until the temperature of the internal combustion engine and its apparatuses installed in the suction system has lowered below the generation temperature of volatile gas such as oil vapor.

Abstract: A thermal airflow sensor is made highly resistant to thermal stresses due to cold-heat cycles, highly reliable even in the presence of corrosive gases, and capable of low dispersion of output characteristics. The thermal airflow sensor has a semiconductor sensor element in a dent formed on a ceramic laminated board on which a control circuit and a metallic film are formed. The laminated board area at which the semiconductor sensor element is electrically connected to the laminated board is covered with epoxy resin. The part covered with epoxy resin is placed in the air passage.

Abstract: A gas flowmeter capable of reducing a secular change comprises a silicon semiconductor substrate formed with a cavity and a heat element formed above the cavity of the semiconductor substrate by way of an insulating film. The heat element is a silicon (Si) semiconductor thin film impurity-doped at high concentration. Stoichiometrically stable silicon nitride (Si3N4) thin films as barrier layers which less permeate and less absorb hydrogen in the heat generating temperature range of the heat element are formed above and below the silicon (Si) semiconductor thin film.

Abstract: To provide a flow measurement sensor which accurately outputs signals even when pulsation flow is generated at high engine speed and also when pulsation flow accompanying reverse flow is generated. In a flow measurement sensor comprising a flow measurement element which has a heater resistance pattern on one side of a plate-shaped member, and a bypass passage in which the flow measurement element is disposed, a first outlet through which fluid flowing along the surface of said flow measurement element flows out, and a second outlet through which fluid flowing along the back side of said flow measurement element flows out are provided, and said second outlet is positioned at a different location from said first outlet.

Abstract: To offer a mass airflow measuring apparatus in which the effect of the adhesion onto the heating resistor caused while the engine is off is reduced and the measuring accuracy is improved. The apparatus measures the mass airflow of the air sucked into the internal combustion engine, using the heating resistor 1. The power control circuit 4 maintains the heating resistor 1 temperature equal to or higher than the temperature during the operation of the internal combustion engine after the internal combustion engine has stopped and until the temperature of the internal combustion engine and its apparatuses installed in the suction system has lowered below the generation temperature of volatile gas such as oil vapor.

Abstract: A thermal type flow rate measuring device can certainly prevent adhesion of water droplet onto a sensor element and thus achieve high reliability. The thermal type flow rate measuring device includes an auxiliary passage defined within a main passage for introducing a part of fluid flowing through the main passage, a sensor disposed within the auxiliary passage for detecting flow rate of the fluid and capturing means formed on an inner periphery of the auxiliary passage for capturing liquid contained in the fluid and transferring the captured liquid.

Abstract: A heating element type mass flow sensor has a composition such that a heating resistor is located substantially in a straight line in the direction perpendicular to the air flow direction; at least a pair of resistance temperature-sensing elements are separately arranged upstream and downstream of the heating resistor, respectively; the heating resistors and the resistance temperature-sensing elements are symmetrically arranged with respect to the air flow direction (the x direction) and the direction perpendicular to the air flow (the y direction), that is, in the two-rotation symmetric manner; and slits are shaped in the respective regions near the two end sides of the heating resistor.

Abstract: Grooves into which an adhesive agent is poured are formed on the adhesion face of a sensor element, the adhesion face being adhered to a surface of a sensor-supporting member, which in turn can make the depth of a layer of the adhesive agent between the sensor element and the sensor-supporting member zero, and remove the difference in level between both the top surfaces of the sensor element and the sensor-supporting member.

Abstract: There is provided a flow rate measuring device which comprises a means for introducing a backward flow of the main passage into the sub-passage through the outlet of the sub-passage of the flow rate measuring device is provided near the outlet of the sub-passage, in order to keep the flow rate measuring element from being destroyed under the presence of dust and water in an intake manifold and which has high reliability for a long period of use and an excellent pulsation characteristic.

Abstract: In a thermal air flow sensor, an air flow measuring element and an intake air temperature sensing element of an intake air temperature sensor are mounted on a single support member so as to be positioned within an intake passage. The support member is made of a glass-ceramic material for example and is held by a holder secured to the wall of an intake pipe. The support member has a structure whereby both sides of a portion of the support member located on the side away from the intake pipe wall are easy to be taken away their heat by an air flow moving through the intake pipe. The air flow measuring element and the intake air temperature sensing element are disposed on such a heat-removed surface of the support member and are electrically connected respectively to conductors disposed on the support member, with their electric connections being sealed with resin, whereby the intake air temperature sensor and the air flow sensor can be rendered integral with each other.

Abstract: Support member 7 where flow amount detection element 9 including a heating resistor and electronic circuit parts 8 for obtaining the air flow amount according to the flow amount signal detected by flow amount detection element 9 are mounted is cooled from both the direction of the main flow of main passage 2 and the direction of an anti-main flow (the opposite direction to the direction of the main flow).

Abstract: A thermal type air flow rate sensor is formed with at least a heating resistor and a temperature measuring resistor on a semiconductor substrate via an electric insulation film, by forming the heating resistor and the temperature measuring resistor with an impurity doped silicon (Si) semiconductor thin film, and by performing high concentration doping process so that an electric resistivity (&rgr;) of the silicon (Si) semiconductor thin film is less than or equal to 8×10−4 &OHgr; cm, with simplified fabrication process for formation of the silicon (Si) semiconductor thin film at the same impurity concentration simultaneously in a lump at low cost.