In order to provide a correction device that enables the accuracy of the linearity between sensor output values and flow rate values in a flow rate sensor, there are provided a sensitivity correction function storage unit that stores a sensitivity correction function in which at least a portion of sensitivity correction values are set to different values in accordance with the sensor output values output from a flow rate sensor in an initial state in which the sensitivity coefficient is set to an initial value, a sensitivity setting unit that sets the sensitivity coefficient based on the initial values and on the sensitivity correction function, and then adjusts the sensitivity of the flow rate sensor, and a coefficient calculation unit that calculates a post-correction flow rate characteristic function based on function correction values that are decided in accordance with the flow rate values output post sensitivity correction.

A flow sensor includes a flow tube in a form of a tube and a support cast around the flow tube. The support clamps the flow tube and the flow tube extends through the support. The flow sensor is formed by placing the flow tube in a tube cavity of a casting mold and pouring or injecting a liquid resin into a support cavity of the casting mold. The support is formed around the flow tube from solidifying the liquid resin in the support cavity of the casting mold. A temperature of the casting mold during formation of the support does not exceed a threshold temperature to avoid deformation of the flow tube. The flow sensor can also include at least one memory chip that stores calibration information associated with the flow sensor and connectors that allows a controller to read the calibration information from the memory chip.

Thermal flow measuring device (1), especially for determining and/or monitoring the mass flow (Φ.sub.M) and/or the flow velocity (v.sub.F) of a flowable medium (3) through a pipeline (2), comprising at least three sensor elements (4a,4b,4c) and an electronics unit (9), wherein each of the at least three sensor elements (4a,4b,4c) is at least partially and/or at times in thermal contact with the medium (3), and includes a heatable temperature sensor (5a,5b,5c), and wherein the electronics unit (9) is embodied to heat each of the three sensor elements (4a,4b,4c) with a heating power (P1,P2,P3), to register their temperatures (T1,T2,T3), to heat at least two of the at least three sensor elements (4a,4b,4c) simultaneously, to ascertain the mass flow (Φ.sub.M) and/or the flow velocity (v.sub.F) of the medium (3), from a pairwise comparison of the temperatures (T1,T2,T3) and/or heating powers (P1,P2,P3) of the at least three sensor elements (4a,4b,4c) and/or at least one variable derived from at least one of the temperatures (T1,T2,T3) and/or heating powers (P1,P2,P3), to provide information concerning a change of the thermal resistance of at least one of the at least three sensor elements (4a,4b,4c), from a response to an abrupt change ΔP of the heating power supplied to at least one of the at least three sensor elements, to provide information concerning a change of the inner thermal resistance of the at least one sensor element, and in the case that a change of the inner and/or outer thermal resistance occurs in the case of at least one of the at least three sensor elements (4a,4b,4c), to perform a correction of the measured value for the mass flow (Φ.sub.M) and/or the flow velocity (v.sub.F) and/or to generate and to output a report concerning the state of the at least one sensor element mass flow (Φ.sub.M) and/or the flow velocity (v.sub.F).

A thermal sensor comprises an active element (41), e.g., a heater or cooler, at least one temperature sensor (31), and processing circuitry (50). The processing circuitry causes a change of power supplied to the active element (41). It then determines, at a plurality of times, a thermal parameter based on an output signal of the temperature sensors and analyzes the transient behavior of the thermal parameter. Based on this analysis, the processing circuitry determines a contamination signal that is indicative of a contamination on a sensing surface of the thermal sensor. If the thermal sensor comprises a plurality of temperature sensors arranged in different sectors of the sensing surface, a multi-sector thermal signal can be derived from the outputs of the sensors, and determination of the contamination signal can be based on the multi-sector thermal signal.

An operator is able to easily perform down-tuning while still achieving superior responsiveness and, in some cases, obtain an equivalent responsiveness as that obtained from the flow rate control device currently being used. In a flow rate control device that performs feedback control of a fluid control valve such that a measured flow rate closely approximates a target flow rate, there are provided a response lag input section that inputs a response lag set value, which is a value showing a response lag that an operator wishes to set, and a response lag generating section that generates response lags used in the feedback control in accordance with the response lag set values.

The present invention provides a thermal flow meter which can suppress a degradation of measurement accuracy caused by deformation of a diaphragm and a stained rear surface thereof even in a case where a gap is provided in order to form the diaphragm in an air flow sensing element. The present invention relates to a thermal flow meter 300 which includes a bypass passage through which a measurement target gas 30 received from a main passage 124 flows, and an air flow sensing element which measures a flow rate of the measurement target gas 30 by performing heat transfer with the measurement target gas 30 flowing through the bypass passage. The thermal flow meter 300 includes at least a circuit package 400 which contains the air flow sensing element 602. A gap 674 is formed in a rear surface of the air flow sensing element 602 to form a diaphragm 672 in an air flow sensing area 437 of the air flow sensing element 602, and the gap 674 becomes a sealed space reduced in pressure compared to an atmospheric pressure.

A thermal, flow measuring device for ascertaining a mass flow or a flow velocity of a medium in a pipe. The thermal, flow measuring device has at least one measuring transducer with at least a first and a second sensor element. The first sensor element has a pin-shaped metal sleeve, which has a lowest point on a wall of the metal sleeve in the gravitational direction, wherein there is arranged in the metal sleeve at least one heating means, especially a heatable temperature sensor. The heating means is arranged in the metal sleeve and above the aforementioned point in the gravitational direction, in such a manner that the maximum heat input per unit area from the heating means into the medium occurs in the gravitational direction above the point.

The present invention has been made to improve measurement accuracy of a thermal flow meter. In the thermal flowmeter according to the invention, a circuit package (400) that measures a flow rate is molded in a first resin molding process. In a second resin molding process, a housing (302) having an inlet trench (351), a bypass passage trench on frontside (332), an outlet trench (353), and the like are formed through resin molding, and an outer circumferential surface of the circuit package (400) produced in the first resin molding process is enveloped by a resin in the second resin molding process to fix the circuit package (400) to the housing (302).

A method for determining at least one gas parameter, of a flowing gas, by means of a flow meter, comprising a measurement section having a heating element and at least three temperature sensors, over which the gas is fed, at least one first temperature sensor being arranged upstream of the heating element, at least one second temperature sensor being arranged in the region of the heating element, and at least one third temperature sensor being arranged downstream of the heating element, wherein a calculation unit determines the at least one gas parameter as a function of the temperature measurement values at the first, second and third temperature sensors, and/or at least two separate gas parameters as a function of the temperature measurement values of individual different temperature sensors and/or the combinations of temperature measurement values of different temperature sensors.

A system for metering gas includes a flow sensor and a controller. The flow sensor is disposed in a conduit in fluid connection with a flow of a gas through the conduit. The flow sensor includes a heater and a temperature sensing element, and generates an electrical output based on the flow of the gas. The controller controls operation of the heater and is operable in a pre-measurement mode and multiple measurement modes. The controller in the pre-measurement mode operates the heater at a pre-measurement setting. The controller in the measurement modes operates the heater at corresponding measurement settings that have increased power levels and/or increased operating durations relative to the pre-measurement setting. The controller in the measurement modes is configured to determine a flow rate of the gas based on an amplitude characteristic and/or a temporal characteristic of the electrical output of the flow sensor.