Design Of Testing Apparatus For Responses Speed Of Flowmeter

The thesis focus on the lack of tester of gas flow meters'response speed in market and the limitation of system function, suggests designing a device that test gas flow meters'response speed, which can bring out steady gas flow, that is variation frequency, variation flowrate.What's more, the device has simple structure and integrated function, and can be easily handled.The device will mainly used in automobile field to test gas flow meters'response speed.The paper introduces the system's mechanical design, controlling hardware and software design, and analyzes the data collected by flowmeter. At the end, gives a summary on the whole system's function and design.The control system design mainly includes circuit design of high frequency valve's driver, program design of USB data collection card; Mechanical structure design mainly includes system's pipe connection, high frequency's reconstruction by Voice Coil Motor. The software and hardware are supportive to each other.Vacuumize the liquefaction tank through the vacuum pump, vacuum degree can be detected by the barometer that connected to the export of the liquefaction tank.The square wave signal generated by control circuit can control the turn-off of the valve . Due to the atmospheric pressure, air is pressed into the liquefaction tank, meanwhile, induced by the flowmeter, we get the signal and the signal will be gathered by the USB acquisition card, and transmitted to the computer. The designing of bypass valve can produce different flow of gas. Because of the switching speed of high-frequency valve directly affect the shape of flowmeter response curve, it will lead to inaccurate measurement results, so that testers can't make sure whether there is something wrong with the response of the flowmeter or the switching speed of the valve is too slow.We must transform its voice coil motor to improve its switching speed and make the rise and fall time of the response curve shorter.Task of the control section of the system is mainly used to writing programs for multifunction Signal Acquisition Card of MPS-010601, and we use Visual Basic6.0 to write the code. The function of the code is outputting square-wave signals of different frequencies and outputting signals of collecting flow meters, it also establishes easy and convenient interface, and this makes controlling the device easy and intuitive.Experimental results demonstrate that our device can produce air current of changing frequencies and flow rate, it also can precisely get the influence curve of all the flow meters. The device is simple and easy controlled, and is testing response speed of flowmeters with high accuracy and high efficiency.