Study On Static And Dynamic Characteristics Of Counterbanlance Valve With Asymmetrical Hydraulic Damping Network Structure

At present,the counterbalance valve has been developed into a series of motion control valves and functions integrating load locking,anti-pressure shock,anti-cavitation and load-controlled decentralization,and counterbalancing valves are widely used in hydraulic circuits with over-loading.The introduction of the counterbalance valve in the hydraulic circuit will bring stability and additional energy consumption to the system.In this paper,LHDV type counterbalanced valve with asymmetric damping network is taken as the research object,its structure composition and working principle are briefly analyzed,and the nonlinear mathematical model of the counterbal ance valve-controlled asymmetric hydraulic cylinder is established to study the static and dynamic characteristics of the counterbalance valve.The main contents include:solving the curve of the over-flow area of the counterbalance valve port displacement a nd calculating the flow coefficient of the balance valve port;calculating the geometric opening ratio and the actual opening ratio of the counterbalance valve,and analyzing the static characteristics of the asymmetric damper and counterbalance valve;study ing the influence of the size of the adjustable orifice,the bypass orifice and the fixed orifice on the dynamic characteristics of the counterbalance valve,and studying the parameters of different working conditions in asymmetrical damping networks.Research indicates:1)The bypass damping bridge in the asymmetric damping network increases the external leakage of the hydraulic cylinder,It increases the pressure coefficient of the flow of the system,and can reduce the gradient of pressure rise in the rod chamber of the hydraulic cylinder,which is beneficial to suppress the overpressure and oscillation of the system.It also has the functions of pressure clipping and amplitude attenuation,which reduces the pilot ratio of the counterbalance valve and i mproves the smoothness of the counterbalance valve action.2)The energy exchange between the bypass chamber and the damping chamber is controlled by an asymmetric damper.That is,the opening process of the main valve spool is jointly controlled by the adj ustable damping hole and the one-way valve,and the closing process is jointly controlled by the adjustable damping hole and the bypass one-way valve.The asymmetry of the damping structure enables the main valve spool to have a quick opening and slow closing asymmetric movement characteristics.3)In the damping network,with the decrease of the aperture of the adjustable orifice and the fixed orifice,the movement of the spool is more stable,but the response lag and pressure overshoot may occur.With the increase of the orifice diameter of the bypass orifice,the movement of the spool will be more stable,but it will also increase the flow leakage and delay the spool response.The change of the fixed orifice and bypass orifice bore diameter is more sensitive to the movement of the valve core,and the adjustable orifice plays a fine tuning role.