Patent ID: 6024112
Filing Date: 2000-02-15
Classification: F16K,F16T,Y10T

Abstract:
A drain valve for removing liquid from a compressed air system driven by a compressor pump which operates according to the pressure of the system to cycle between a desired maximum pressure and a desired minimum pressure, said drain valve comprising, in combination:(a) A drain valve assembly including a drain valve body forming a central cavity, an inlet port located in said drain valve assembly and adapted to be connected to the compressed air system, and a drain port located in said drain valve assembly away from said inlet port;(b) Said drain valve assembly further including a valve operating structure mounted within said central cavity and a vent passageway located between a first portion of said central cavity and said drain port, said passageway including a vent orifice for controlling the flow of liquid through said vent passageway and said drain port;(c) A piston assembly, at least a portion of said piston assembly mounted within said first portion of said central cavity between said inlet port and said vent passageway and having an inlet face which can seal said inlet port when said piston is contiguous said inlet port and a vent face having an area larger than said inlet face which can seal said vent passageway when said piston is contiguous said vent passageway;(d) Said piston assembly including a dividing member which divides said first portion of said central cavity into a vent cavity located between said dividing member and said vent passageway and an inlet cavity located between said dividing member and said inlet port; an opening between said inlet cavity and said vent cavity, said opening having an area larger than the area of said vent orifice, but smaller than the other areas through which fluid can flow between said inlet port and said vent orifice;(e) An adjustable pressure valve assembly mounted within said valve operating structure, said adjustable pressure valve assembly exerting force on said piston assembly toward said inlet port to seal said inlet port when there is no pressure at said inlet port;(f) The area of said inlet face of said piston assembly is of a size which, when said inlet face is sealing said inlet port, allows the force exerted by said valve member to be overcome by a preselected high drain pressure at said inlet port as the pressure of the compressor system increases toward the desired maximum pressure, said inlet face moving away from said inlet port at the high drain pressure to allow liquid to drain from said inlet port and through a flow path comprising said inlet cavity, said opening, said vent cavity, said vent passageway including said vent orifice and said drain port, while the relative sizes of the areas of said opening and said vent orifice prevent said vent face on said piston assembly from moving to a closed position against said vent passageway until compressed air begins flowing through said flow path;(g) The area of said vent face of said piston assembly is of a size such that, when said vent face is sealing said vent passageway, pressure on the piston assembly prevents the force exerted by said valve member from overcoming the pressure of the compressed air system until a preselected low drain pressure is reached at said inlet port as the pressure of the compressor system decreases toward the desired minimum pressure, said vent face being moved away from said vent passageway at said low drain pressure to allow liquid to drain from said inlet port and through said flow path comprising said inlet cavity, said opening, said vent cavity, said vent passageway including said vent orifice, and said drain port, while the relative sizes of the areas of said opening and said vent orifice prevent said inlet face on said piston assembly from moving to a closed position against said inlet port until after compressed air begins flowing through said flow path.