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A method provides several modes for recovering hydraulic energy produced by an overrunning load acting on cylinders connected in parallel to a machine component. In one mode, fluid from first chambers in both cylinders is routed into the accumulator, while other fluid is directed into second chamber

A method provides several modes for recovering hydraulic energy produced by an overrunning load acting on cylinders connected in parallel to a machine component. In one mode, fluid from first chambers in both cylinders is routed into the accumulator, while other fluid is directed into second chambers of those cylinders. In a different mode, fluid is routed from the first chamber of only one cylinder into the accumulator, and fluid from the first chamber of the other cylinder goes into the second chambers of both cylinders. Yet another mode comprises routing fluid from the first chambers of both cylinders into the second chambers of both cylinders. In still another mode, fluid from the first chambers of both cylinders goes into the return conduit while the second chambers of both cylinders receive fluid from a supply conduit. Several modes of reusing the recovered energy are described.

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What is claimed is: 1. An energy recovery method for a hydraulic system that includes a supply conduit, a return conduit, an accumulator, and a first cylinder and a second cylinder mechanically connected in parallel to operate a component on a machine and each having first and second chambers, said

What is claimed is: 1. An energy recovery method for a hydraulic system that includes a supply conduit, a return conduit, an accumulator, and a first cylinder and a second cylinder mechanically connected in parallel to operate a component on a machine and each having first and second chambers, said energy recovery method comprising: a split cylinder energy recovery mode which comprises routing fluid from the first chamber of the second hydraulic cylinder only into the accumulator and routing fluid from the first chamber of the first hydraulic cylinder into the second chambers of both the first and second hydraulic cylinders; and thereafter reusing fluid in the accumulator to power at least one of the first cylinder and the second cylinder. 2. The energy recovery method as recited in claim 1 wherein the split cylinder energy recovery mode further comprises routing fluid from the supply conduit into the second chambers of both the first and second hydraulic cylinders. 3. The energy recovery method as recited in claim 1 further comprising a cross chamber recovery mode which comprises routing fluid from the first chambers of both the first and second hydraulic cylinders into the second chambers of both the first and second hydraulic cylinders, wherein any excess quantity of fluid beyond that required to fill the second chambers is sent to one of the accumulator and the return conduit. 4. The energy recovery method as recited in claim 3 wherein a transition from the split cylinder energy recovery mode to the cross chamber recovery mode occurs when fluid from the first chamber of the second hydraulic cylinder no longer provides sufficient energy to charge the accumulator and a cross chamber energy recovery mode differential pressure is greater than zero. 5. The energy recovery method as recited in claim 3 further comprising a dual cylinder energy recovery mode which comprises routing fluid from the first chambers of both the first and second hydraulic cylinders into the accumulator, and directing fluid into the second chambers of the first and second hydraulic cylinders. 6. The energy recovery method as recited in claim 5 wherein directing fluid into the second chambers in the dual cylinder energy recovery mode comprises routing fluid from one of the supply conduit and the return conduit into the second chambers of the first and second hydraulic cylinders. 7. The energy recovery method as recited in claim 5 further comprising a pseudo-split cylinder energy recovery mode in which a path is provided for fluid to flow from the first chambers of both the first and second hydraulic cylinders into the second chambers of both the first and second hydraulic cylinders, wherein any excess quantity of fluid beyond that required to fill the second chambers is sent into the accumulator. 8. The energy recovery method as recited in claim 7 wherein a transition from the dual cylinder energy recovery mode to at least one of the split cylinder energy recovery mode, the pseudo-split energy recovery mode, and the cross chamber energy recovery mode occurs in response to pressure at the accumulator being less than a corresponding one of a split cylinder energy recovery mode differential pressure, a pseudo-split energy recovery mode differential pressure, and a cross-chamber energy recovery mode differential pressure. 9. The energy recovery method as recited in claim 8, wherein the pressure at the accumulator is less than at least two of the split cylinder energy recovery mode differential pressure, the pseudo-split energy recovery mode differential pressure, and the cross-chamber energy recovery mode differential pressure, and the transition occurs to the one of the split cylinder energy recovery mode, the pseudo-split energy recovery mode, and the cross-chamber energy recovery mode providing the most efficient mode for recovery. 10. The energy recovery method as recited in claim 1 wherein the reusing fluid in the accumulator comprises at least one of an energy reuse mode A that comprises routing fluid from the accumulator into the first chambers of both the first and second hydraulic cylinders, and an energy reuse mode B that comprises routing fluid from the accumulator into the first chamber of only the second hydraulic cylinder and routing fluid from the supply line into the first chamber of the first hydraulic cylinder. 11. The energy recovery method as recited in claim 10 wherein at least one of the energy reuse mode A and the energy reuse mode B further comprises routing fluid from the second chambers of both the first and second hydraulic cylinders to the return conduit. 12. The energy recovery method as recited in claim 10 wherein a first pump is connected to the supply line; and further comprising a mode in which fluid is routed from the supply line into the first chamber of the first hydraulic cylinder, and in which fluid is routed into the first chamber of the second hydraulic cylinder from at least one of the accumulator and a second pump. 13. The energy recovery method as recited in claim 1 wherein the hydraulic system further comprising a control valve assembly coupling the supply and return conduits to the first and second cylinders, and in the split cylinder energy recovery mode the fluid is routed from the first chamber of the second hydraulic cylinder into the accumulator without entering either the supply conduit or the return conduit. 14. An energy recovery method for a hydraulic system that includes a supply conduit, a return conduit, an accumulator, and a first cylinder and a second cylinder mechanically connected in parallel to operate a component on a machine and each having first and second chambers, said energy recovery method comprising: a dual cylinder energy recovery mode which comprises routing fluid from the first chambers of both the first and second hydraulic cylinders into the accumulator, and routing fluid into the second chambers of the first and second hydraulic cylinders; a split cylinder energy recovery mode which comprises routing fluid from the first chamber of the second hydraulic cylinder only into the accumulator, and routing fluid from the first chamber of the first hydraulic cylinder into the second chamber of at least one of the first and second hydraulic cylinders; and reusing fluid in the accumulator to power at least one of the first cylinder and the second cylinder. 15. The energy recovery method as recited in claim 14 wherein the split cylinder energy recovery mode further comprises routing fluid from the supply conduit into the second chambers of both the first and second hydraulic cylinders. 16. The energy recovery method as recited in claim 14 wherein routing fluid into the second chambers in the dual cylinder energy recovery mode comprises routing fluid from one of the supply conduit and the return conduit into the second chambers of the first and second hydraulic cylinders. 17. The energy recovery method as recited in claim 14 wherein the reusing fluid in the accumulator comprises at least one of an energy reuse mode A that comprises routing fluid from the accumulator into the first chambers of both the first and second hydraulic cylinders, and an energy reuse mode B that comprises routing fluid from the accumulator into the first chamber of only the second hydraulic cylinder and routing fluid from the supply line into the first chamber of the first hydraulic cylinder. 18. The energy recovery method as recited in claim 14 wherein at least one of the energy reuse mode A and the energy reuse mode B further comprises routing fluid from the second chambers of both the first and second hydraulic cylinders to the return conduit. 19. The energy recovery method as recited in claim 14 wherein a first pump is connected to the supply line; and further comprising a mode in which fluid is routed from the supply line into the first chamber of the first hydraulic cylinder, and in which fluid is routed into the first chamber of the second hydraulic cylinder from at least one of the accumulator and a second pump. 20. The energy recovery method as recited in claim 14 wherein: in the dual cylinder energy recovery mode, the fluid is routed through a direct path provided by a recovery control valve from the first chambers of both the first and second hydraulic cylinders into the accumulator, and in the split cylinder energy recovery mode, the fluid is routed through a direct path provided by a recovery control valve from the first chamber of the second hydraulic cylinder into the accumulator. 21. An energy recovery method for a hydraulic system that includes a supply conduit, a return conduit, an accumulator, and a first cylinder and a second cylinder mechanically connected in parallel to operate a component on a machine and each having first and second chambers, said energy recovery method comprising: a split cylinder energy recovery mode which comprises routing fluid from the first chamber of the second hydraulic cylinder only into the accumulator, and routing fluid from the first chamber of the first hydraulic cylinder into the second chamber of at least one of the first and second hydraulic cylinders; a cross chamber recovery mode which comprises routing fluid from the first chambers of both the first and second hydraulic cylinders into the second chambers of both the first and second hydraulic cylinders; and reusing fluid in the accumulator to power at least one of the first cylinder and the second cylinder. 22. The energy recovery method as recited in claim 21 wherein the split cylinder energy recovery mode further comprises routing fluid from the supply conduit into the second chambers of both the first and second hydraulic cylinders. 23. The energy recovery method as recited in claim 22 further comprising a dual cylinder energy recovery mode which comprises directing fluid from the first chambers of both the first and second hydraulic cylinders into the accumulator, and directing fluid into the second chambers of the first and second hydraulic cylinders. 24. The energy recovery method as recited in claim 22 wherein the reusing fluid in the accumulator comprises at least one of a first energy reuse mode that comprises routing fluid from the accumulator into the first chambers of both the first and second hydraulic cylinders, and a second energy reuse mode that comprises routing fluid from the accumulator into the first chamber of only the second hydraulic cylinder and routing fluid from the supply line into the first chamber of the first hydraulic cylinder. 25. The energy recovery method as recited in claim 22 wherein a first pump is connected to the supply line; and further comprising a mode in which fluid is routed from the supply line into the first chamber of the first hydraulic cylinder, and fluid is routed into the first chamber of the second hydraulic cylinder from at least one of the accumulator and a second pump. 26. The energy recovery method as recited in claim 21 wherein the hydraulic system further comprising a control valve assembly coupling the supply and return conduits to the first and second cylinders, and in the split cylinder energy recovery mode the fluid is routed from the first chamber of the second hydraulic cylinder into the accumulator without entering either the supply conduit or the return conduit.