Multifunction valve for use in a hydraulic component

A valve apparatus for use in controlling the flow of fluid between the closed hydraulic loop and the fluid source of a hydraulic component, comprising:

• a valve seat movable between a first open position to permit fluid to flow from the fluid source to the closed hydraulic loop when the pressure in the closed hydraulic loop is lower than a first predetermined pressure level and a second closed position when the pressure in the closed hydraulic loop is equal to or greater than the first predetermined pressure level;
• a sleeve member located in the valve seat and movable between a first position where the valve apparatus is open to permit fluid communication between the closed hydraulic loop and the fluid source when the pressure in the closed hydraulic loop is below a second predetermined pressure level and a second position where the sleeve member prevents fluid communication between the closed hydraulic loop and the fluid source;
• a movable poppet, cooperating with the valve seat and the sleeve member to provide a pressure rise rate function whereby the poppet opens for a limited time when the pressure in the closed hydraulic loop exceeds a third predetermined level and increases at a rate exceeding a predetermined rate and closes in a controlled manner;
• and
• whereby the poppet will open to permit fluid to flow from the closed hydraulic loop to the fluid source when the pressure in the closed hydraulic loop exceeds a fourth predetermined level.

A valve apparatus for use in regulating the flow of fluid between a closed hydraulic loop and a fluid source in a hydraulic circuit, comprising:

• a valve seat for selectively opening and closing fluid communication between the closed hydraulic loop and the fluid source, the valve seat comprising a head portion, a body forming a first internal volume, a first opening formed in the head portion to permit fluid communication between the closed hydraulic loop and the first internal volume and at least one second opening in the head portion to permit fluid communication between the fluid source and the first internal volume;
• a slidable member located in the first internal volume, the slidable member comprising a first end adapted to engage the valve seat head, a base formed at a second end, at least one opening formed in the base, and a second internal volume formed between the first and second ends of the slidable member;
• a relief poppet slidably disposed in the first internal volume, the relief poppet comprising a head adapted to sealingly engage the first opening in the head portion of the valve seat and a body extending from the relief poppet head and at least partially located inside the second internal volume;
• a relief compression spring located inside the second internal volume and positioned between the relief poppet and the base of the slidable member;
• a valve guide comprising a first end attached to the valve seat, a second end, an opening formed in the second end and in fluid communication with the closed hydraulic loop, and an internal passage between the first end and the opening, wherein the diameter of the opening is less than the diameter of the internal passage;
• and
• an accumulator piston slidably mounted within the internal passage of the valve guide, wherein the accumulator piston cooperates with the internal passage of the valve guide to define an accumulator volume.

A valve for use between a hydraulic circuit and a fluid source in a hydraulic apparatus, the valve comprising:

• a check means for opening the valve to permit fluid to pass from the fluid source into the hydraulic circuit when the pressure in the hydraulic circuit is below the pressure in the fluid source by a first predetermined amount;
• a relief valve means formed with the check means for opening the hydraulic circuit to the fluid source when the pressure in the hydraulic circuit exceeds a first predetermined pressure level;
• and
• pressure rise rate means for temporarily opening the hydraulic circuit to the fluid source when the pressure in the hydraulic circuit exceeds a second predetermined pressure level, and increases at a rate exceeding a predetermined rate and for then closing the hydraulic circuit from the fluid source in a controlled manner.