The Research Of The Load-Sensing Counterbalance Valve

Hydraulic counterbalance valve is a key element in the hydraulic balanced loop , which is applied abroad in modern engineering mechanism especially in elevating machinery. The performance of the complete appliance is influenced by the property of the counterbalance valve, so, if the design is irrational, the working of the equipment is confined, at the same time, the stability of the complete appliance and the rigidity of the movable beam and the frame are effected badly. There are many pieces of disadvantage in conventional counterbalance valves, such as whipping in Low Frequency, the high control pressure, the bad working stability, the large power loss, and especially the changeless backpressure set up. When pressure brought by load is higher (large load) than pressure set up by counterbalance valve, systemic Low Frequency whipping can't be eliminated clearly, but when lower (small load), the control pressure is very high and the power loss is very large. Aiming at the disadvantage above, a new sort of load- sensing counterbalance valve is researched in this paper.The load-sensing counterbalance valve in this paper is a new kind of counterbalance valve which is designed on the basis of summary of the designing experience of conventional counterbalance valves and the analysis of the latest outcome. The load-sensing theory is applied in this designing, which the pressure signal from the lower cavity of hydraulic cylinder is fed back to the valve to make the size of valve plug uncork change according to the load change in order to solve the exiting problem that the backpressure can't change with the load pressure thoroughly.In this paper, the theory of load sensing counterbalance valve is elaborated, its structure is detailed and especially, its key parts are computed in detail. According to design calculation of the valve port and compensating spring, dual spring and non-linear valve port are adopted to adapt to various section load, so as to the regulation performance and control performance of the valve are ameliorated hugely. The functional relationship graphic between spool traverse and axial relief with various springs function and the comparison diagram between real area of orifice and theoretical are given in this design.Static state and dynamic emulation about the new counterbalance valve are carried out by the software Matlab/Simulink. The outcome of emulation proves that with the step load signal or step flow signal, system can reach steady state all the time in about ls,which is obviously improved compared with other counterbalance valve products (such as literature: at fractional load 1.5s and burden 2.1s).A whole suite of testing program is thought out at last in this paper in view of the characteristic of this valve. The innovation points of this paper are that a kind of counterbalance valve (it has been declared patent of invention and the application number of patent is 200610102007.X) with completely new theory is brought forward and complete analyses are carried out it.