| Hydraulic transmission system has been extensively used in industrial production because of high power, small size, high degree of automation. But at the same time, the hydraulic transmission system has the disadvantages of high fault rate and difficulty in fault detection,which brings the magnitude economic loss. Flow and pressure is an important parameter to reflect the running state of the hydraulic system, and System fault detection is often start with system flow and pressure.. The traditional intrusive detection method is very limited because of difficult installation, low efficiency。In this paper, a method of outside measuring flow and pressure of the hydraulic system is presented with ultrasonic wave. Based on this method, detection of hydraulic transmission system failure can be quickly completed。The development history and research trend of ultrasonic waves non-intrusive flow and pressure measurement at home and abroad are discussed in the paper. And the paper opens the principle and key technology of ultrasonic flow and pressure detecting method. And the mathematical model used in this method is discussed in detail.This paper is aimed at the problem of large dispersion of time measurement results in small diameter, low flow rate. By using data processing method, the time measurement is converted to the determination of time termination point. Thus, the stability and accuracy of the system are improved.The ultrasonic flow and pressure detecting system is composed of high voltage module, ultrasonic transducer, ultrasonic emission circuit, echo gain adjustment circuit, 4 way high speed data acquisition circuit, USB transmission circuit and PC data processing. The system accomplishes ultrasonic signal transmission and reception, the echo signal amplification conditioning, signal data acquisition and upload as well as the flow and pressure calculation.The filter design based on the reference signal can effectively filter out the interference of the signal. Automatic echo algorithm can quickly search the target signal, and realize the intelligent data processing. Using Hilbert transform for signal envelope,and the algorithm of envelope peak point is used as the end point of the time,which overcomes the problems of random measure ment and large error of time measurement.Finally through the experiment data, in this paper, the design of the ultrasonic flow, pressure detection system, can quickly, hydraulic device for convenient measurement of the flow, the pressure value, measurement results reliability, high precision to meet the requirements of fault diagnosis of hydraulic system. |
