SU446755A1 - Mass flow meter - Google Patents

Description

one

This invention relates to the field of flow measurement.

In known mass flow meters, the mass flow rate is proportional to the time interval between the pulses of the two sequences produced by the sensor.

However, when measuring the flow rate of these devices, the measurement accuracy is influenced by interference, which can cause a false null organ actuation.

To improve noise immunity, a comparator, an integrator and a logic circuit are entered into the proposed flow meter, the inputs of which are connected to the outputs of the comparator and the zero-organ, the outputs are connected to the computing unit and the second trigger input, and the output of the sensor is connected to the comparator input via a control key and integrator.

Thus, in contrast to previously known flowmeters, the zero-organ signals are used not only to control the computing unit, but also to start the second channel to form rectangular pulses. By coincidence of signals of two channels of formation, the presence of a signal with

flow sensor. This makes it possible to significantly increase the noise immunity of the device.

FIG. 1 shows a block diagram of the flowmeter described; in fig. 2 - voltage plots showing the operation of the flow meter. The bipolar signals of sensor 1 arrive at the null organ 2 and the control key 3. When the signals of sensor 1 reach a predetermined threshold level (FIG. 2, a),

null-organ 2 triggering (Fig. 2, b), on the leading edge of a pulse of which, via trigger 4, key 3 is opened, as a result of which sensor 1 signal goes to integrator 5. A monopolar signal is received from the integrator output (Fig. 2, c), which goes to the comparator 6. At the output of the comparator 6, rectangular pulses are formed, which are symmetrical about the zero value of the sensor signals (Fig. 2, d), which

arrive at the logic circuit 7. The logic circuit generates a signal for controlling the computing unit 8. The logic circuit 7 can generate two types of signals controlling the computing unit 8. In the first case, the computing unit 8 is controlled by the signals of the zero-organ 2, which will pass on the output of logic circuit 7 only in the presence of the comparator signal 6. The input device will be protected from

impact of impulse noise (coarse failures), but is subject to the influence of additive noise, acting at the time of the sensor signals passing through a zero value. At the same time, the requirements for the key, integrator, and comparator characteristics are low.

In the second case, the control is performed by the signals of the comparator 6. In this case, the input device is protected from the effects of both pulsed and additive interference, and the integrator and comparator must meet rather high requirements, since their characteristics will determine the accuracy of the flow meter.

Subject invention

Mass flow meter containing a double-turbine sensor connected to the input of the czl-organ, the output of which through a trigger is connected to the control input of the key, n computing unit, characterized in that, in order to improve noise immunity, a comparator, an integrator and a logic circuit, inputs are introduced into it which are connected to the outputs of the comparator and the zero of the organ, the outputs to the computing unit and to the second trigger input, and the output of the sensor through the controlled key and the integrator is connected to the input of the comparator.

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