Hydraulic Compensated Four-way Control Valve Characteristic
There are many ways of compensating for the reaction forces in spool type valves. In general most of these methods do not actually change the reaction force characteristics at each orifice. The general trend is to try either to nullify the forces on the spool by flow restrictions in some part of the valve or to overcompensate for the reaction forces at two out of the four controlling edges of the valve. One approach to compensating for the .reaction forces is given by Fig. 1.13. This method uses contouring at the discharge orifices to provide flow forces on the spool in the opposite direction to the normal reaction forces of the other orifices. The valve :reaction forces for this type of compensated valve are given by Fig. 1.14.
Most compensating methods do not modify the magnitude or the slope of the reaction forces at the null position of the valve spool or for the very, very small orifice openings. The compensation takes place at the slightly larger orifice openings where the flows are slightly larger. The greatest modification achieved by most compensating methods reduces the total reaction force to about one-tenth of the force of an uncompensated valve. Usually, less compensation is used because of the manufacturing costs which increase as a function of the amount of. the
Categories: Hydraulic Control System | Tags: reaction forces, spool valve | Leave a comment