Design Of Measuring System For Rotating Machinery

In the power and transmission systems of ships and mechanical equipment,the torque is the important parameter which can directly reflect the mechanical performance and running state of the power and transmission systems.Following the constant development of modern science and technology,research and development of the new-type torque sensor is one of the hot topics in the sensor research field.The sensor based on the surface acoustics waves(SAW)technology gradually draws the extensive attention because of its high precision,fine stability,wide use range and other features.This paper regards the SAW sensor as the sensing portion of torque inspection to design the wireless torque measuring system.The main research content includes:1)On the basis of analyzing the positive piezoelectric and negative piezoelectric characteristics of piezoelectric materials and transmission characteristics of SAW signals,theoretical model that two single-ended resonant SAW resonators(SAWR)form the torque and frequency deviation of the sensor in the differential structure is deduced.2)Based on the theoretical model,the measured goal is clear.System is designed with two single-ended resonant SAWRs,wireless micro-power communication module and C8051F021 single-chip microcomputer.Gathering module of frequency offset in the designed system consists of resonance circuit,mixer circuit,single-chip microcomputer and wireless radiating circuit designed by torque sensor with 45° and 135° direction to the axis center line;the output module of the system consists of wireless receiving circuit,single-chip microcomputer and RS232 interface,etc.to output the torque in the way of serial data and analog voltage.3)Test is carried out with the installation of the designed wireless torque measuring device to the test platform of one transmission system.9 different given torques are set in uniformly-space in the range of 0~4000N·m to conduct the experimental verification and the result shows that the designed wireless torque measuring system can collect and transmit the torque measured data in real time;within the experiment range of 4000N·m,measured sensor sensitivity is 0.1443KHz/ N·m;the measured result is close to the theoretical model,has the good linearity and the relative mean error is 0.63% while the maximum relative mean error is1.3%.