Non-leaking storage charging valve

An accumulator charging valve for connecting an inlet to an outlet of a hydraulic system when an adjustable upper charging pressure in the hydraulic system is reached and for separating the inlet from the outlet when an adjustable lower charging pressure is reached, comprising:

• a valve body having inlet means for coupling a fluid pressure source to said valve body, outlet means for coupling an outlet to said valve body and control connection means for coupling a hydraulic system to said valve body;
• a first conduit in said valve body connecting said inlet means and said outlet means;
• a control piston movably mounted in said valve body between a first switching position blocking connection of said inlet means and said outlet means and a second position opening connection of said inlet means and said outlet means, said control piston being coupled to restoring means for biasing said control piston toward said first position;
• a separating means including a first adjustable piloting valve for separating said control connection means from said outlet means and for adjusting the lower charging pressure;
• a second conduit in said valve body connecting said inlet means and said control connection means and extending between said control connection means and said outlet means;
• a check valve located in said second conduit between said inlet means and said control connection means, said first adjustable piloting valve and said check valve forming a tight seal for a leak point between said control connection means and said outlet means when the adjustable upper charging pressure is attained, said check valve controlling connection of said control connection means to said outlet means;
• a control chamber in said valve body for said control piston, said control piston having a passage opening into said control chamber;
• means in said valve body for connecting said passage to a leak line;
• a third conduit connecting said control chamber with said inlet means;
• and
• a second piloting valve for adjusting the upper charging pressure and maintaining a predetermined pressure in said control chamber.