Position feedback pilot valve actuator for a spool control valve
AssigneeHUSCO International, Inc.
InventorDennis Barber
Life of this patent
Estimating the term…
Abstract
A spool type control valve is operated by an electrically driven pilot valve. A pilot piston is attached to the control spool. As an electrical actuator moves the pilot spool, a greater pressure is applied to one side of the pilot piston than the other side, which causes movement of the control spool. When the control spool reaches the desired position, its positional relationship to the pilot valve defines a pressure differential across the pilot piston which exerts a net force on the control spool that counterbalances a spring force acting on the control spool. This defines an equilibrium position at which the control spool remains until subsequent motion of the pilot spool occurs which alters the pressure differential across the pilot piston.
Claims39
In a valve assembly having body in which a control spool selectively controls flow of fluid between at least one workport and both a supply passage and a return passage, a pilot valve comprising:
- a piston bore formed in the body;
- a pilot piston connected to the control spool and slideably received in the piston bore, thereby defining a first chamber and a second chamber in the piston bore;
- a pilot spool slidably received in the body and moveable with respect to the control spool to open and close fluid passages between the first chamber and both and the supply passage and the return passage, and between the second chamber and the supply passage and the return passage;
- and
- a linear actuator engaging the pilot spool to move the pilot spool with respect to the control spool.
In a valve assembly having a control spool which selectively controls flow of fluid between at least one workport and both a supply passage and a return passage, a pilot valve comprising:
- a body having a piston bore and a pilot valve bore opening into the piston bore, the supply passage opening into the pilot valve bore;
- a pilot piston coupled to the control spool and slideably received in the piston bore thereby defining a first chamber and a second chamber in the piston bore, the pilot piston having a surface with a predefined contour;
- the body further having a first pilot passage extending from the first chamber to the pilot valve bore, and a second pilot passage extending from the second chamber to the pilot valve bore;
- a tubular pilot sleeve slidably received in the pilot valve bore and having an outer surface and an inner surface defining a pilot spool bore, a plurality of transverse passages extending between the inner and outer surfaces and communicating with the supply passage, the first pilot passage and the second pilot passage;
- a member engaging the surface of the pilot piston and acting on the tubular pilot sleeve, wherein movement of the pilot piston produces movement of the tubular pilot sleeve;
- a pilot spool slidably received in the tubular pilot sleeve to provide fluid paths between selected ones of the plurality of transverse passages;
- and
- a linear actuator coupled to the pilot spool for moving the pilot spool within the tubular pilot sleeve.
A pilot valve for operating a control spool which selectively controls flow of fluid between at least one workport and both a supply passage and a return passage, said pilot valve comprising:
- a body having a piston bore and a pilot valve bore opening into the piston bore;
- a pilot piston coupled to the control spool and slideably received in the piston bore thereby defining a first chamber and a second chamber in the piston bore, the pilot piston having a tapered surface;
- the body further having a first pilot passage extending from the first chamber to a first opening into the pilot valve bore, and a second pilot passage extending from the second chamber to a second opening into the pilot valve bore, and wherein the supply passage communicates with the pilot valve bore at a third opening adjacent the first opening and at a fourth opening adjacent the second opening;
- a tubular pilot sleeve slidably received in the pilot valve bore and having an outer surface and an inner surface defining a pilot spool bore, the tubular pilot sleeve further including first, second, third and fourth transverse passages extending between the inner and outer surfaces and respectively communicating with the first, second, third and fourth openings, the tubular pilot sleeve engaging the surface of the pilot piston wherein movement of the pilot piston produces movement of the tubular pilot sleeve;
- a pilot spool slidably received in the tubular pilot sleeve and providing fluid paths between selected ones of the first, second, third and fourth transverse passages;
- and
- a linear actuator coupled to the pilot spool for moving the pilot spool within the tubular pilot sleeve.
In a valve assembly having a control spool which selectively controls flow of fluid between at least one workport and both a supply passage and a return passage, a pilot valve comprising:
- a body with a bore into which the control spool extends, a first opening into the bore communicates with one of the supply passage and the return passage, and a second opening into the bore communicates with the other of the supply passage and the return passage;
- a pilot piston connected to the control spool and slideably received in the bore thereby defining a first chamber and a second chamber in the bore, the pilot piston having a feeder aperture that communicates with the first opening in the body and with a first aperture in the control spool;
- a pilot spool slidably received in a pilot bore in the control spool and having a first position which provides fluid paths between the first aperture and both the first chamber and a second chamber in the bore, a second position at which communication is provided between the first aperture and the first chamber and between the second aperture and the second chamber, and a third position at which communication is provided between the second aperture and the first chamber and between the first aperture and the second chamber;
- and
- a linear actuator operably coupled to move the pilot spool within the control spool.
In a valve assembly having a control spool which selectively controls flow of fluid between at least one workport and both a supply passage and a return passage, a pilot valve comprising:
- a body with a piston bore into which a section of the control spool extends, a first opening into the bore communicates with one of the supply passage and the return passage, and a second opening into the bore communicates with the other of the supply passage and the return passage;
- a tubular pilot piston through which the control spool extends and is connected thereto, the pilot piston being slideably received in the piston bore thereby defining a first chamber and a second chamber in the piston bore, the pilot piston having a feeder aperture that communicates with the first opening in the body and with a first aperture in the control spool;
- a pilot spool slidably received in a pilot bore in the control spool and having a first position which opens a first passage between the first aperture in the control spool and the first chamber in the piston bore and opens a second passage between the first aperture and the second chamber in the piston bore, a second position which opens the first passage and a third passage between the second chamber and the second opening in the piston bore, and a third position which opens the second passage and a fourth passage between the first chamber and the second opening;
- and
- a linear actuator operably coupled to move the pilot spool within the control spool.
Dependencies are inferred from the claim text.