In using a fast Fourier transform for correction of a pulsation error in a conventional air flow rate measuring device, the correction is delayed due to the observation time and computation time required for the fast Fourier transform, leading to difficulty in following changes in the pulsation state at high speed. The air flow rate measuring device according to the present invention comprises an air flow rate detector that generates an output signal in accordance with an air flow rate being measured, an amplitude detector that detects a pulsation amplitude from the output signal, a low-pass filter in which the cut-off frequency changes in accordance with the value of the pulsation amplitude, and a waveform arithmetic unit that computes the waveforms of the output signal from the low-pass filter and the output signal. The waveform arithmetic unit is constituted from multipliers, an adder, and a condition determination process. The low-pass filter is constituted from a subtractor, a multiplier, an adder, and a delay element, with the cut-off frequency changing in accordance with the pulsation amplitude by changing the gain of the multiplier with the pulsation amplitude.

A flow rate measuring member configured to measure a flow rate of a gas, a storage configured to store a plurality of pieces of predetermined data, except for a meter read value, of a plurality of pieces of data each of which is calculated based on the flow rate measured by the flow rate measuring member, and a communicator configured to transmit the plurality of pieces of predetermined data stored in the storage to an external device are provided. The storage starts sequentially storing the plurality of pieces of predetermined data in response to an occurrence of a predetermined event, and the communicator transmits, at a predetermined timing, the plurality of pieces of predetermined data stored in the storage to the external device.

A fluid flow meter serves to determine the flow of a fluid, in particular in the form of gas, in a pipe, wherein the fluid flow meter is configured to generate a first measurement variable and at least a second measurement variable for the fluid and at least a first diagnostic parameter. The fluid flow meter comprises a diagnostic system that is configured to determine a first threshold value for the at least one first diagnostic parameter both based on the first measurement variable and based on the at least one second measurement variable and to output a first message to a higher-ranking control device when said first threshold value is reached.

A housing defines a bypass passage and a sub-bypass passage therein. A bypass passage is configured to draw a part of an air flowing through a duct. The sub-bypass passage branches off the bypass passage and is configured to draw a part of air flowing through the bypass passage. A flow rate sensor is arranged in the sub-bypass passage and configured to generate an electric signal according to a flow rate of air in the duct by performing heat transfer with air passing through the sub-bypass passage. A physical quantity sensor is configured to measure a physical quantity of air in the duct. A sensor assembly is integrally formed with the flow rate sensor, the physical quantity sensor, and a circuit module. The circuit module includes a substrate that is configured to process signals from the flow rate sensor and the physical quantity sensor.

A mass flow control system can be self verified for its accuracy when controlling a flow to a process. The system comprises: a control valve for controlling the flow of fluid through the system as a function of a control signal; a controller for generating the control signal as a function of measured flow of fluid through the system and a targeted flow set point; a pressure sensor for measuring the controlling fluid pressure for use in measuring and verifying the flow rate; and a source of fluid for providing a known volume of fluid for use in verifying the system accuracy anytime between steps of the flow control process.

A device (12) that uses a temperature coefficient pre-calibrated for the device for measuring a flow within the device. The device includes a differential pressure sensor (80) configured to generate a differential pressure signal responsive to a differential pressure within a flow path (16) and a temperature sensor configured to sense a temperature near the differential pressure sensor. A differential amplifier amplifies differential pressure signals from the differential pressure sensor. A processor receives signals from the differential pressure sensor, amplified signals from the differential amplifier, and signals from the temperature sensor. The amplified signals are corrected based upon at least a predetermined temperature coefficient, and the processor calculates a flow rate based on the corrected representation of the differential pressure.

A housing defines a bypass passage and a sub-bypass passage. The bypass passage draws a part of air flowing through an interior of a duct. The sub-bypass passage is branched from the bypass passage to draw a part of air flowing through the bypass passage. A flow sensor is equipped in the sub-bypass passage to cause heat transfer with air, which passes through the sub-bypass passage, and to generate an electric signal according to a flow quantity of air in the duct. An intake-air temperature sensor is configured to measure a temperature in the duct. A moisture sensor is configured to measure a humidity in the duct. The flow sensor and the multiple sensors are equipped in the sub-bypass passage and are located along a direction of flow of air in the sub-bypass passage.

The mass of a fluid flowing through a flow rate meter at a temperature which fluctuates in a given temperature range is determined by driving an exciter magnet system through the fluid with an exact correlation between the fluid volume flowing there through and the movement path covered by the exciter magnet system, producing a measurement voltage pulse after each passage through a movement path corresponding to a unit volume of the fluid by means of a Wiegand wire and a coil surrounding same, at each measurement time charging a first energy storage means by electric energy contained in each measurement voltage pulse, and using same as operating energy for measurement of the instantaneous temperature of the fluid, producing a temperature value as an integral multiple of the smallest temperature measurement unit to be resolved and an integral count value including said temperature value, and adding same to a sum contained in a non-volatile storage means from the precedingly ascertained count values for forming an ongoing sum in the non-volatile storage means and passing same to a processor which can be supplied with external energy and which calculates therefrom the temperature-corrected delivery volume of the fluid.

Techniques for the design and operation of an efficient battery-powered meter are described herein. A metrology unit of the meter may be at least partially located in the gas flow of a pipe, and measures gas flow rate data according to a static flow sensor. The metrology unit calculates raw gas-volume data using at least the flow rate data as input. The metrology unit measures gas temperature to produce gas temperature data, and adjusts the raw gas-volume data, based at least in part on the gas temperature data, to produce corrected gas-volume data. The metrology unit accumulates the corrected gas-volume data over multiple minutes, hours or even days, and then sends the accumulated corrected gas-volume data to an index unit of the meter. By accumulating the data over time, fewer data transmissions are required. The index unit may send the accumulated the accumulated corrected gas-volume data to a utility server.

Techniques for the design and operation of an efficient battery-powered meter are described herein. A metrology unit of the meter may be at least partially located in the gas flow of a pipe, and measures gas flow rate data according to a static flow sensor. The metrology unit calculates raw gas-volume data using at least the flow rate data as input. The metrology unit measures gas temperature to produce gas temperature data, and adjusts the raw gas-volume data, based at least in part on the gas temperature data, to produce corrected gas-volume data. The metrology unit accumulates the corrected gas-volume data over multiple minutes, hours or even days, and then sends the accumulated corrected gas-volume data to an index unit of the meter. By accumulating the data over time, fewer data transmissions are required. The index unit may send the accumulated the accumulated corrected gas-volume data to a utility server.