Gas flow calibrating device based on bell shape-column shape dual piston structure

Abstract

The invention relates to a gas flow test device based on piston working principle. The existing device is suitable for large flow test, but is inconvenient to use and inaccurate in measuring result when measuring small flow. The invention comprises a frame, a cylinder, a motor and a measurement and control system, wherein the cylinder, the motor and the measurement and control system are arranged on the frame and the motor drives the piston in the cylinder. The invention is characterized in that the piston is of bell shape, a column-shaped piston is formed at the middle of the bell-shaped piston, the cylinder comprises an inner gas chamber and an outer gas chamber, the column-shaped piston is inserted into the inner gas chamber, the inner gas chamber and the outer gas chamber are connected via a gas outlet pipe arranged outside the cylinder, the gas outlet pipe is connected with a detected flowmeter, the inner gas chamber and the outer gas chamber are respectively connected with an external gas duct, and the gas duct and the gas outlet pipe are respectively provided with a flow controller. The invention is designed to optimize chamber structure in the cylinder to match with the dual pistons, and measurement is realized by selecting the corresponding piston according to different measurement need, thus improving measurement accuracy and expanding application range.

Description

technical field [0001] The invention relates to a gas flow test device based on a piston-type working principle, in particular to a gas flow calibration device based on a bell-shaped cylindrical double-piston structure. It can work under positive and negative pressures, providing standard flow values ​​for low Reynolds number critical flow flowmeters, gas mass flow controllers, small-diameter rotameters, laminar flowmeters, etc. Background technique [0002] At present, the basic structure of domestic piston gas flow calibrator is as follows: figure 1 As shown, it is mainly composed of frame 4", cylinder 6", piston 5", screw assembly 3", motor 1", intake valve 9" and measuring instrument 2". The rear part of the air duct 7". When working, the operating system instructs the motor to rotate, and the screw rod is driven by the speed change mechanism. After the gas pressure is constant, the measuring instrument (the computer operating system composed of the upper and lower com...

AI Technical Summary

Problems solved by technology

However, the piston structure of this type of device is relatively simple, all of which are traditional cylindrical pistons, which are suitable for large flow tests. When measuring small flow rates, it is inconvenient to use and the measurement results are inaccurate.

In addition, it takes a certain amount of time for the gas pressure in the cylinder to rise to stabilize during operation, and the utilization rate of the cylinder volume is low; when the motor and the transmission mechanism are running at low speed (that is, when the flow rate is small), the piston may sometimes crawl, which affects the measurement accuracy

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