Patent ID: 6497251
Filing Date: 2002-12-24
Classification: F15B,F16K,Y10T

Abstract:
A hydraulic latching spool valve adapted to be inserted in a valve chamber in a body, the body defining a supply port, a function port, a vent port, a pilot close port and a pilot open port, the supply port connected to a pressurized fluid source which delivers supply pressure to the spool valve, the pilot close port connected to a close pilot to deliver close fluid to the spool valve when the close pilot is pulsed and the pilot open port connected to an open pilot to deliver open fluid to the spool valve when the open pilot is pulsed, the hydraulic latching spool valve comprising:valve cage sized and arranged to be inserted in the valve chamber of the body, the valve cage defining a first seat positioned between a valve supply port and a valve function port and a second seat positioned between the valve function port and a valve vent port; a seal assembly carried by a movable elongate piston, the piston moving from a closed position in which the seal assembly is engaged with the first seat and disengaged with the second seat, allowing fluid communication between the valve action port and the valve vent port, and containing pressurized fluid in the valve supply port, to an open position in which the seal assembly is disengaged with the first seat and engaged with the second seat allowing, pressurized fluid to flow from the valve supply port to the valve function port and preventing pressurized fluid from flowing to the valve vent port, the elongate piston having a head and a toe; a spring urging the movable piston into the closed position, the spring positioned in a pilot close chamber, the chamber in fluid communication with the pilot close port; a pilot open chamber in fluid communication with the pilot open port, the pilot open chamber exerting fluid pressure on the head of the elongate movable piston and causing the piston to move from the closed position to the open position when the open pilot is actuated; and a latching chamber formed on an interior of the elongate movable piston, near the head, the latching chamber in fluid communication with supply pressure, and the latching fluid entering the latching chamber from the elongate movable piston when the valve is in the open position, the latching chamber having an area exposed to supply pressure that generates sufficient latching force to overcome the opposing forces generated by the spring and opposing forces generated by the supply pressure acting against the piston and seal assembly to hold the piston in the open position until the close pilot is pulsed and close fluid enters the pilot close chamber overcoming the latching force to close the spool valve.