Research On The Key Technologies Of 2D Proportional Valve

With many advantages, such as reliable performance, low cost, high precision and fast dynamic response, Electro-hydraulic proportional technology can control the position, speed and force of the load, and replace electric-hydraulic servo system in many fields. Electro-hydraulic proportional valve represents the development direction of the electro-hydraulic proportional technology.There are two types of proportional valve, direct-acting and pilot-operated proportional valve. The former has limitations of small flow and low pressure due to the limited thrust of proportional solenoid; and the later has complex structure, needs pilot oil and cannot work under zero-pressure condition. The 2D proportional valve achieves power amplification through servo screw mechanism, whose working principle is based on the usage of dual DOFs of spool radial rotation and axial movement. Compared to other types of proportional valve, 2D proportional valve possesses benefits of simple structure, high anti-pollution capability, neglectable null position leakage of pilot stage, high natural frequencies and fast dynamic response. In this thesis the key technologies of 2D proportional valve are researched and the main contents are as follows:(1) In order to improve the performance of the electro-mechanical converter of the 2D proportional valve, A new type of rotary solenoid with a six-blade rotor is proposed. Base on the study of its working principle, mathematical model is established about the rotating magnet, the influence of structural parameters on its static and dynamic characteristics is simulated and analyzed, on the base prototype production and experimental platform building, the rotary solenoids' static and dynamic characteristics and experimental are studied, the rotary solenoid has constant output driving torque 0.04 N.m, 12.5° angular displacement, and about 5ms dynamic response time.(2) The traditional single-stage direct-acting electro-hydraulic valve is difficult to achieve high pressure and large-flow, and pilot-controlled electro-hydraulic valve's structure is complex, to overcome these shortcomings, 2D proportional valve spool adopts hydraulic servo screw mechanism, which arise spool large stroke and spool driving force to improve the 2D proportional valve's flow and response speed. The dynamic characteristics of hydraulic servo screw mechanism is researched, the influence of main structure parameters to valve frequency characteristics and step response such as radius of high and low pressure hole, initial chord height, system pressure and length of sensitive chamber are all studied. Theoretical analysis shows frequency response at-3d B amplitude attenuation is about 160 Hz, the step response time is about 2.5ms.(3) In view of the deficiency of the current research on calibration technology of LVDT(Linear Variable Differential Transformer), An calibration technique using Support Vector Machine for LVDT is proposed in this paper. The objective of this technique is to improve the linearity of LVDT in the full range as well as eliminate the effect of excitation frequency, physical parameters and working temperature on the output of LVDT. The system once designed is subjected to test data with variations in excitation frequency, physical parameters and working temperature for particular displacement. The conventional calibration circuit is replaced by Support Vector Machine(SVM) model to achieve desired objectives. Results show the proposed technique has achieved its set objectives. The proposed calibration technique yields the maximum error of 0.125%,with linearization over the range 0 to 10 mm.(4) The test rig for performance of 2D proportional valve is built. The experiments of null position leakage of pilot stage, flow characteristics and dynamic characteristics of 2D proportional valve are performed.