Patent ID: 8424836

Claim:
A valve comprising: a valve body including a main chamber having a first port and a second port; a main poppet disposed within the main chamber and being slidable between an open position and a closed position to control fluid flow between the first port and the second port, the main poppet having a first surface forming a control chamber within the main chamber; a first passage communicating the control chamber with the first port, the first passage having a check valve therein allowing fluid to flow from the first port to the control chamber, and a second passage communicating the control chamber with the second port, the second passage having a check valve therein allowing fluid to flow from the second port to the control chamber; a pilot valve having a pilot poppet for controlling fluid flow between the control chamber and the first port through a third passage, and for controlling fluid flow between the control chamber and the second port through a fourth passage; and a spring coupled between the main poppet and the pilot poppet to provide a force relative to a distance between the main poppet and the pilot poppet to close the pilot valve.