Development Of Thermal Gas Flow Meter For Air Jet Loom

Air-jet loom is a shuttleless loom which uses high-speed air flow to complete weft insertion.Due to the increasingly perfect manufacture technology and function of air-jet looms,its advantages such as fast weaving speed,high weft insertion rate and The range of weaving varieties is more and more extensive,which makes air-jet looms account for an increasing proportion of shuttleless looms.However,the energy consumption of air-jet looms is highest in the same kind of shuttleless looms.Energy saving and consumption reduction have become an important problem to be solved in the development of air-jet looms.The energy consumption of air-jet looms mainly includes power consumption and gas consumption.Gas consumption accounts for more than 2/3 of total energy consumption.If air flow rate of air-jet looms can be monitored in real time,then gas consumption of each air-jet loom will be refined.So it is very important for the production enterprises to formulate corresponding inspection system and check index,strengthen consciousness of energy saving of production workers,and reduce the gas consumption from the source.In order to monitor gas consumption of air-jet loom,a flow meter specially used in air-jet looms is proposed in this paper.The hardware and software functions of the flowmeter are designed in detail,and a calibration system which matching with the flowmeter is studied.The main contents of this paper are as follows:The measuring principle of traditional thermal flowmeter is studied.Based on the principle,a mathematical model of measuring flow-rate is established.The temperature characteristics of hot-film probe under different ambient temperature and current are studied by design experiments,and the linear relationship between resistance and temperature is also verified.The velocity distribution and calculation method of flow-rate in pipeline are studied,and reasonable position and calculation method of the hot-film probe are determined.It lays a theoretical foundation for the design and development of thermal flowmeter.According to design requirements of the flowmeter,a design scheme of flowmeter based on FS5 air flow sensor and the Renesas RL78/L13 single chip microcomputer is presented.The circuit of the flowmeter.The structure of key circuits,such as air flow sensor circuit,RS485 communication circuit and power supply module circuit,is given in this paper.The working principle of these circuits are analyzed in detail.Then software platform is built based on hardware circuit,and software function module of the flowmeter is designed.Finally,the drawing of mechanical shell for the flowmeter is given,and installation method and position are illustrated.Expansibility and reliability of the flowmeter are considered in whole design.A data fitting model of flowmeter based on local weighted regression algorithm is established and verified.In order to improve measurement accuracy of the flowmeter,the automatic calibration experiment platform is designed.User interface of system is developed based on MATLAB,and then calibration experiment of the fowmeter is carried out.Comparison experiments between the sample of flowmeter and SMC standard flowmeter(PF2A750)are carried out,it shows that the output characteristics of the designed flowmeter are consistent with standard flowmeter,and it's precision is very high.It has reached the design target,and it can meet the matching use of air-jet looms.