A new closed loop flow controlling principle through correcting the valve's opening area while load pressure is changing is carried out. Further more a principle using only one proportional valve to compound control pressure and flow is suggested. By using very simple proportional throttle valve in structure, the functions that five kinds of proportional valves or any two of them combined possess can be complimented. After analyzing, comparing, and testing the dynamic and static characteristics of valve with different controlling principles and main valve structure styles, the optimized structure styles and control methods are achieved.
Quan LongMa JianWang YongjinInstitute of Mechatronics,Taiyuan University of Technology,Taiyuan 030024, China
To control the position of differential cylinder closed loop without using any throttle elements, a new idea that two speed variable pumps are used to compensate the non-symmetric flow of differential cylinder is carried out.According to the leaking property of the system, a speed offset principle is also proposed to eliminate the cavitation and tension caused by the leakage and condensation of oil, which makes the system be in the same state as a valve controlled circuit.This principle is explained theoretically and experimentally.Further the relationship that the pressures in cylinder chambers change with load and leakage, and the relationship between biasing speed and pre-load pressures in cylinder chambers are established.The research has proved that the new system has similar technique features as those of controlled with servo valves, but due to the elimination of all the throttle lose the efficiency of system can be improved greatly.
