Hydraulic system and a working machine comprising such a hydraulic system
AssigneeVolvo Construction Equipment AB
InventorsBo Vigholm, Andreas Ekvall, Kim Heybroek
Life of this patent
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Abstract
A hydraulic system for a working machine includes at least one work function and a control valve unit for controlling hydraulic fluid to and from the work function, and a recovery unit connected to a return port of the control valve unit for recovering energy from the work function. The system further includes an arrangement for limiting the pressure of the hydraulic fluid at the return port, which pressure limiting arrangement has a pilot-operated valve adapted to set a maximum allowable pressure at the return port of the control valve unit. The pressure is variable by controlling the pilot-operated valve by a control unit.
Claims31
A hydraulic system for a working machine, comprising at least one work function and a control valve unit for controlling hydraulic fluid to and from the work function, and a recovery unit connected to a return port of the control valve unit for recovering energy from the work function, and a means for limiting the pressure of the hydraulic fluid at the return port, wherein the pressure limiting means comprises a pilot-operated valve arranged to set a maximum allowable pressure at the return port of the control valve unit, which pressure is variable by controlling the pilot-operated valve by means of a control unit.
A method for recovering energy in a hydraulic system, wherein the hydraulic system comprises at least one work function and a control valve unit for controlling hydraulic fluid to and from the work function, and a recovery unit connected to a return port of the control valve unit for recovering energy from the work function, comprising controlling a maximum allowable pressure at the return port by a pressure limiting means through receiving signals from a control unit to adapt a maximum energy recovery rate of the recovery unit to an actual operation mode of the work function.
Dependencies are inferred from the claim text.