Power plants – Pressure fluid source and motor – Condition responsive control of pump or motor displacement
Reexamination Certificate
2008-07-01
2008-07-01
Lopez, F. Daniel (Department: 3745)
Power plants
Pressure fluid source and motor
Condition responsive control of pump or motor displacement
Reexamination Certificate
active
07392653
ABSTRACT:
A hydraulic control system for a working machine according to the present invention comprises a hydraulic pump for supplying working oil to a hydraulic actuator through a control valve, a relief mechanism disposed on the discharge side of the pump, the relief mechanism assuming an open state when a pump discharge pressure which varies according to the pump flow rate exceeds a predetermined pressure and assuming a closed state when the pump discharge pressure becomes the predetermined one or lower, an ordinary control means for controlling the pump flow rate in accordance with working information, and a pressure feedback control means for controlling the pump flow rate in accordance with the pump discharge pressure. In this system, out of controls performed by both control means, control wherein the flow rate by one control becomes smaller than that of the other is selected, thereby opening/closing control of the relief mechanism is performed. According to this, it is possible to decrease the relief loss and improve the energy efficiency while making the most of the ordinary control.
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Kobelco Construction Machinery Co., Ltd.
Lopez F. Daniel
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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