ELECTROOPTICAL GAS OR LIQUID FLOW METER Russian patent published in 2012 - IPC G01F1/704 G01F1/708 

FIELD: physics.

SUBSTANCE: flow meter has a measuring pipe (1) with a flow leveller (2) at the inlet, a controlled heat mark generator (3) with a pulsed heater (4), a heating controller (5), a flow rate indicator (6) and a velocity and flow rate computer (7). The heating controller (5) is connected by its output to the control input of the heat mark generator (3). The velocity and flow rate computer (7) is connected by the first output, which informs on flow rate, to the input of the flow rate indicator (6), and by the second output, which informs on velocity, to the first input of the heating controller (5). The input of the velocity and flow rate computer (7) is connected to a timer (8) The enable and inhibit inputs of the timer (8) are respectively connected to first and second identical recorders (9.1, 9.2) of the heat mark. Both recorders (9.1, 9.2) of the heat mark have heat detectors (10.1, 10.2) at the input and secondary transducers (11.1, 11.2) at the output, which are connected to output electrodes of the heat detectors. The heat detectors (10.1, 10.2) of the first and second recorders lie at unequal distances from the heater on the flow path at a fixed distance (L), which forms the control section. Both heat detectors (10.1, 10.2) are in form of electrooptical units comprising the following elements: a coordinate-sensitive thermal detector (12.1, 12.2) provided with a central and two lateral output electrodes; a reflector-generator (13) of infrared radiation flux emitted by the heat mark, where said reflector-generator is deposited on the inner surface of the pipe; an infrared window (14.1, 14.2) for outlet of radiation of the heat mark from the pipe; an infrared lens (15.1, 15.2), which focuses radiation of the heat mark onto the sensitive surface of the receiver. Each secondary transducer (11.1, 11.2) is in form of an electric circuit, having at the input a bridge circuit (16.1, 16.2) for switching the coordinate-sensitive detector, a differential amplifier (17.1, 17.2), an adder amplifier (18.1, 18.2), and at the output - a null element (19.1, 19.2), provided with measuring and clock inputs and a strobing output. Each of the coordinate-sensitive thermal detectors (12.1, 12.2) is connected on a differential circuit by three output electrodes to adjacent input arms of the bridge circuits (16.1, 16.2). The adjacent output arms of the bridge circuits (16.1, 16.2) are connected in parallel to inputs of the differential (17.1, 17.2) and adder (18.1, 18.2) amplifiers. The outputs of the differential (17.1, 17.2) amplifiers are connected to measuring inputs of the null elements (19.1, 19.2), the strobing outputs of which are connected to corresponding inputs of the timer (8). The flow metre also has a comparator unit (20) which is connected by the first and second inputs to outputs of adder amplifiers (18.1, 18.2) of the first and second recorders, respectively. The comparator unit (20) is connected by the first and second outputs, which inform on duration of input pulses, to clock inputs of null elements (19.1, 19.2) of the first and second recorders, respectively, and by the third output, which informs on amplitude of input pulses, to the second input of a heating controller (5). The output of the heating controller (5) has two channels, one of which (P_I) serves to control the heater based on the power of the heating pulse, and the other (τ_I) for controlling the heater based on pulse duration.

EFFECT: high accuracy of measuring speed and flow of a gas or liquid, as well as a wider range of measured quantities with simplification of the circuitry of the flow metre.

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