Spool valve

A spool valve having at least two positions, comprising:

• a valve housing having means defining therein a spool hole and plural control ports for fluid control which communicate with said spool hole;
• a valve spool axially movably supported in said spool hole and having fluid control collar means thereon for effecting fluid connections between selected ones of said ports in response to movement of said valve spool;
• servo piston means for moving said valve spool in two axial directions;
• and pilot valve means which can be remotely controlled by putting said servo piston means under pressure and freeing it of pressure;
• wherein said valve housing includes a body having a central opening therethrough and having openings therein which each serve as a portion of a respective one of said ports, two end plates shutting off said central opening at opposite ends of said body, and two liners which have therein said spool hole and openings which each serve as a portion of a respective one of said ports, said liners being positioned symmetrically in said central opening through said body with respect to a plane which is normal to the axis of said spool hole and being axially spaced from each other, and said servo piston means including spaces provided within said spool hole in said liners;
• including an air let-off valve provided in one of said end plates, said let-off valve having a large air flow cross-section;
• wherein said servo piston means includes two servo pistons;
• wherein said air let-off valve includes a valve jumper having an axial stem and a cup-like annular packing therearound, said air let-off valve furthermore having means defining a valve seat part engageable with said stem;
• wherein an axial space provided between said valve jumper and said valve seat part of said let-off valve communicates with a servo piston space having one of said servo pistons movably supported therein;
• wherein said pilot valve means includes said valve body being adapted to have two pilot valves mounted thereon, and includes a first connection duct in said body of said valve housing which extends lengthwise of said valve housing, which communicates with two first connection ports which are provided in said body and are each adapted to communicate with a respective said pilot valve, and which opens through an end face provided at one end of said valve housing body;
• wherein said body of said valve housing has two separate and parallel second connection ducts provided in and extending lengthwise of said body of said valve housing and two second connection ports provided in said body which each effect fluid communication between a respective said second connection duct and a respective one of said pilot valves;
• wherein one of said second connection ducts opens through said one of said end faces of said valve housing;
• wherein said valve includes a support plate which is disposed adjacent said valve body and which has plural connection openings which each communicate with a respective said control port in said valve housing, wherein through-holes for valve fixing parts are provided in said body and communicate with said central opening in said body in which said liners are placed, and including a gasket disposed between said valve housing and support plate, having holes lined up with said control ports of said valve body, and having further holes lined up with said through-holes in said valve body, said through-holes having washers at ends thereof remote from said gasket which, when said fixing parts are disposed in said through-holes and are securely fixing said valve housing on said support plate, provide an air-tight seal between a head of each of said fixing parts and said valve housing.

A valve, comprising:

• a body having first and second end surfaces at opposite ends thereof, a central bore extending between and opening through said end surfaces, plural control ports extending through said body from a first side surface thereof to said central bore, first and second connection ports provided in a second side surface of said body, means defining a first passageway which provides fluid communication between said first connection port and a first one of said control ports, and means defining a second passageway which communicates with said second connection port and opens through said second end surface;
• first and second end plates which are sealingly mounted against said first and second end surfaces, said second end plate having means defining a first let-off valve therein which is actuated by fluid pressure and can selectively provide fluid communication between the adjacent end of said bore in said body and one of said second passageway and a let-off opening of large cross-sectional size provided in an exterior surface of said second end plate;
• a first pilot valve which is supported on said valve body in fluid communication with said first and second connection ports and is adapted to selectively permit and interrupt fluid communication between said first and second connection ports;
• valve insert means sealingly supported in said central bore in said body, having a central opening therethrough, and having means defining plural openings therein which each provide fluid communication between said central opening and a respective one of said control ports in said body, said valve insert means including two sleevelike, axially spaced valve inserts;
• a spool which is supported in said central opening through said valve insert means for axial movement between first and second positions, which has means defining axially spaced annular control collars and defining annular seal means on each said control collar which sealingly engages an inner surface of said central opening through said valve insert means, and which has means defining an axially extending opening in an end thereof which faces said first end plate;
• a servo piston which is axially slidably supported in and sealingly engages said opening in said spool, and which has a portion adapted to engage said first end plate;
• means for yieldably urging axial movement of said spool toward said second end plate relative to said servo piston;
• and third and fourth connection ports provided in a side surface of said valve body other than said first side surface thereof, said third connection port being in fluid communication with said first passageway;
• wherein said valve body includes means defining a third passageway therein which communicates with said fourth connection port and opens through said first end surface of said body.