Valve-positioning apparatus

A valve comprising in combination:

• a housing having a first internal passageway and a plurality of second fluid passageways communicating with said first passageway;
• a valve element mounted within said first passageway for movement therewithin between at least two positions for opening and closing said second fluid passageways;
• valve shifting means for causing said valve element to move within said first passageway between its positions and for holding said valve element in one position after such movement, said valve shifting means being in an operating mode when it moves said valve element between said two positions and holds said valve element in one of said position;
• said valve shifting means being in a nonoperating mode when it neither moves said valve element between its positions nor holds it in one of said positions;
• positioning means for shifting said valve element to a predetermined position within said first passageway whenever said valve shifting means is in said nonoperating mode, said positioning means including at least one valve element contact means for contacting and positioning said valve element and position control means for moving said valve contact means to a first position out of contact with said valve element to allow movement of said valve element by said valve shifting means when said shifting means is in said operating mode and for moving said valve element contact means to a second position in contact with said valve element for urging said valve element to said predetermined position within said first passageway when said shifting means is in its nonoperating mode;
• second control means for allowing movement of said valve element contact means to its first position only after said valve element is positioned in said predetermined position by said valve shifting means in said operating mode;
• said valve being a spool valve, said valve element comprising an elongated spool within said first passageway in said spool valve, said valve shifting means being fluid operated and including fluid conduits communicating with a source of fluid pressure and internal portions of said first passageway in said housing and control valve means for controlling insertion and exhaustion of fluid under pressure to said first passageway through said fluid conduits such that when fluid pressure is present, said valve shifting means is in its operating mode and said valve element contact means is held in its first position;
• said control valve means including at least two electric, solenoid-operated fluid pilot valves, one of said pilot valves adapted to control movement of said spool in one direction in said first passageway and the other of said pilot valves adapted to control movement of said spool in the opposite direction in said first passageway.

A valve comprising in combination:

• a housing having a first internal passageway and a plurality of second fluid passageways communicating with said first passageway;
• a valve element mounted within said first passageway for movement therewithin between at least two positions for opening and closing said second fluid passageways;
• valve shifting means for causing said valve element to move within said first passageway between its positions and for holding said valve element in one position after such movement, said valve shifting means being in an operating mode when it moves said valve element between said two positions and holds said valve element in one of said positions;
• said valve shifting means being in a nonoperating mode when it neither moves said valve element between its positions nor holds it in one of said positions;
• positioning means for shifting said valve element to a predetermined position within said first passageway whenever said valve shifting means is in said nonoperating mode, said positioning means including at least one valve element contact means for contacting and positioning said valve element and position control means for moving said valve contact means to a first position out of contact with said valve element to allow movement of said valve element by said valve shifting means when said shifting means is in said operating mode and for moving said valve element contact means to a second position in contact with said valve element for urging said valve element to said predetermined position within said first passageway when said shifting means is in its nonoperating mode;
• second control means for allowing movement of said valve element contact means to its first position only after said valve element is positioned in said predetermined position by said valve shifting means in said operating mode;
• said position control means including fluid-operated, fluid pressure responsive means responsive to said valve shifting means being in said operating mode for moving said valve element contact means to and holding said valve element contact means in said first position and a third fluid passageway for conducting fluid under pressure from a source of fluid pressure to said fluid pressure responsive means;
• said valve shifting means being fluid operated;
• said second control means including fluid seal means between said valve element contact means and said fluid operated valve shifting means for allowing fluid movement therepast only to move said valve element contact means to its first position, and check valve means in said third fluid passageway for preventing fluid passage to said fluid pressure responsive means through said third fluid passageway until after said valve element is positioned in said predetermined position by fluid and fluid has moved past said fluid seal means to move said valve element contact means to its first position.

In a spool valve including a housing having a bore therein and a plurality of fluid passageways interconnecting with said bore, an axially shiftable spool having opposite ends and mounted in said bore and adapted to be shifted to open and close various of said fluid passageways, means for axially shifting said spool to open and close said passageways, and means for inserting a fluid under pressure into at least one of said fluid passageways;

• the improvement comprising:
• spool positioning means for shifting said spool to a predetermined axial position within said bore whenever fluid pressure fails or is absent in said one fluid passageway, said positioning means including an aperture axially aligned with one of said ends of said spool through at least one end of said housing;
• a generally closed fluid chamber mounted on at least said one housing end and generally covering said aperture;
• a piston mounted for movement in said fluid chamber in alignment with the axis of said spool between a first position in which said piston is withdrawn out of contact with said spool and a second position in which a portion of said piston extends through said housing aperture and contacts said one end of said spool to shift said spool to said predetermined axial position within said bore, the entirety of said piston being located beyond said one end of said spool at all times;
• sealing means for sealing said piston within said fluid chamber;
• biasing means for biasing said piston toward its second position;
• and a fluid passageway connected in fluid communcation with said fluid under pressure in said one fluid passageway for admitting a fluid under pressure against said piston within said chamber whereby whenever fluid pressure is present in said one fluid passageway, said piston is withdrawn to its first position against the force of said biasing means but when the fluid pressure fails or is absent, said piston is moved by said biasing means to its second position to contact said one end of said spool and shift said spool to said predetermined position;
• said means for axially shifting said spool being fluid operated;
• said sealing means including fluid seal means between said piston and said fluid-operated means for axially shifting said spool for allowing fluid movement therepast only to move said piston to its first position, and check valve means in said fluid passageway which admits pressure against said piston for preventing fluid passage to said piston through the said fluid passageway until after said spool is positioned in said predetermined axial position by fluid and fluid has moved past said fluid seal means to move said piston to its first position.