Energy conserving tandem directional valve

Claim 1

An energy conserving tandem directional valve comprising: a multiported longitudinal valve housing having first and second ends interconnected by a bore extending therethrough, said bore having a first diameter portion adjacent said first end extending inwardly therefrom toward said second end, a second diameter portion adjacent said second end extending inwardly therefrom toward said first end and a third diameter portion interconnecting the innermost ends of said first and second diameters, said first and second diameter portions having larger diameters than said third diameter portion, including shoulders at the interconnection of said diameters with a first shoulder facing said housing first end and a second shoulder facing said housing second end, said housing further including at least three perpendicular ports extending through said housing and communicating with said bore extending therethrough, one of said ports comprising a first fluid supply port communicating with said first diameter portion adjacent said first housing end and adaptable to be connected to the pressurized fluid source, another of said ports comprising a second fluid port communicating with said third diameter portion and adaptable to be connected to a first fluid receiver, the remaining port comprising a third fluid port communicating with said second diameter portion adjacent said second housing end and adaptable to be connected to a second fluid receiver, said second bore end being closed by an end cap provided with a central opening therethrough comprising a main valve exhaust port open to atmosphere, said second and said third ports receiving and exhausting said pressurized fluid from said first fluid port in tandem flow therethrough, said first bore end receiving slidably an elongated stem with a piston at one end and a smaller diameter opposite stem end round, said piston being of close sliding fit with the housing having a seal received slidably inside said first diameter portion with said piston head including an end face, a second seal in said stem received inside said first diameter portion and spaced along said stem from said piston adjacent said first shoulder with a seal diameter of less than the diameter of said piston but greater than said third diameter portion, a third seal in said stem received inside said second diameter portion and spaced along said stem adjacent said second shoulder with a seal diameter greater than said third diameter portion but less than The diameters of said piston and of said second diameter portion, and a final seal on said opposite stem end adjacent said end cap sized to permit close sliding fit inside said exhaust port of said end cap opening, said stem being selectively shifted between a first position wherein said fluid communication is permitted between said fluid supply and said first fluid receiver port but is precluded from entering said second fluid receiver port by said third seal being firmly seated against said second shoulder while simultaneously allowing fluid communication between said second fluid receiver port and said exhaust port, and a second position wherein fluid communication is permitted between said first and second receiver ports while having said second seal firmly seated against said first shoulder to preclude fluid communication between said fluid supply port and said first fluid receiver port and also having said final seal engaged inside said main valve exhaust port to preclude fluid exhaust into the atmosphere, said stem further including a small fluid passage extending therethrough from said first diameter portion to said piston end face for selectively allowing fluid flow from said first diameter portion through said fluid passage and outwardly from said end face, a solenoid valve operator disposed at said first bore end of said housing, said operator having a plunger disposed generally coaxial with said stem and axially movable selectively in an operative relationship with solenoid energization between an open position spaced from said end face of said piston and defining a fluid cavity therebetween and a closed position in blocking engagement with said small passage at said end face, wherein when said plunger is in said closed position said stem is retained in said first position by fluid entering a first annulus formed between said stem and said first diameter portion said fluid acting on said piston with a force large enough to maintain said third seal firmly seated against said second shoulder when said stem is in said first position with said valve being open to full pressure of the working fluid for feeding said first receiver port while said main valve exhaust port is open to atmosphere allowing said second receiver port to simultaneously exhaust, and wherein when said plunger is in said open position said stem is shifted to said second valve closed position by fluid entering said cavity through said passage in said piston end face and acting against said piston head end face exposed to said cavity with a force large enough to maintain said second seal firmly seated against said first shoulder while allowing full pressure from said first receiver port to enter said second receiver port, said solenoid valve operator further including means for exhausting fluid from said cavity as said plunger is moved from said open toward said closed position, including spring biasing means for continuously exerting a biasing force on said plunger to force said plunger toward said closed position, whereby when said solenoid valve operator is de-energized said spring biasing means forces said plunger from said open to said closed position, energization of said solenoid causing said plunger to overcome said biasing force of said biasing means in moving from said closed to said open position.