Energy Storage Cylinder and Control System for a Moving Structural Member
AssigneeCaterpillar Inc.
InventorsGang Victor Wen, Pengfei Ma, Jiao Zhang
Life of this patent
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Abstract
An energy storage system is disclosed for use in a hydraulic system for moving a structural member such as a boom assembly. The system features at least one work cylinder and an additional energy storage cylinder that assists in raising and lowering functions by storing and withdrawing pressurized fluid from an accumulator. The pressurized fluid in the accumulator may be used for raising operations as well as digging and tamping operations. Further, the energy recovery features may be selectively disconnected during either a raising or lowering operation.
Claims20
An energy storage system for assisting in vertically moving a structural member, the system comprising:
- at least one work cylinder to vertically move the structural member;
- an energy storage cylinder coupled to the structural member, including a rod end and a cap end, wherein the rod end and the cap end are in selective fluid communication;
- an accumulator;
- a fluid reservoir;
- a first valve disposed between the accumulator and the cap end of the energy storage cylinder, a second valve disposed between the fluid reservoir and the cap end of the energy storage cylinder;
- wherein, when the structural member is lowered and the first valve is at least partially open and the second valve is at least partially closed, at least a portion of the fluid from the cap end of the energy storage cylinder is directed to the accumulator;
- and
- wherein, when the structural member is raised and the first valve is at least partially open and the second valve is at least partially closed, at least a portion of fluid from the accumulator is directed to the cap end of the energy storage cylinder.
A machine that raises and lowers a structural member, the machine comprising:
- a work cylinder including a rod end, a cap end, a piston disposed therebetween and a rod coupling the piston to the structural member;
- the cap end and rod end of the work cylinder in communication with a main control valve for raising or lowering the structural member;
- an energy storage cylinder including a rod end, a cap end and a piston disposed therebetween, the piston connected to an assist rod that is coupled to the structural member;
- the cap and rod ends of the energy storage cylinder in communication with a first valve disposed between the energy storage cylinder and an accumulator and a second valve disposed between the energy storage cylinder and the reservoir;
- the rod end of the energy storage cylinder in selective communication with the cap end of the energy storage cylinder;
- wherein, when the structural member is lowered, fluid flows from the cap end of the energy storage cylinder, through the first valve to the accumulator;
- and
- when the structural member is raised, fluid flows from the accumulator to the cap end of the energy storage cylinder through the first valve.
A method of controlling a raising and a lowering of a structural member, the method comprising:
- providing a work cylinder including a rod end, a cap end, a piston disposed therebetween and a rod coupling the piston to the structural member, the cap end and rod end of the work cylinder in communication with a main control valve for raising or lowering the structural member;
- providing an energy storage cylinder including a rod end, a cap end and a piston disposed therebetween, the piston connected to an assist rod that extends out the rod end and is coupled to the structural member, the cap and rod ends of the energy storage cylinder in communication with a first valve that provides selective communication between the energy storage cylinder and an accumulator;
- wherein, to lower the structural member, the method includes
- blocking flow to the work cylinder and providing communication between the cap end of the energy storage cylinder and the accumulator;
- instituting a lower command;
- and
- allowing gravity to lower the structural member while fluid flows from cap end of the energy storage cylinder through the first control valve to the accumulator;
- and
- wherein, to raise the structural member, the method includes
- pumping flow from the main control valve to the cap end of the work cylinder;
- instituting a raise command;
- and
- releasing flow from the accumulator, through the first control valve, to the cap end of the energy storage cylinder.
Dependencies are inferred from the claim text.