Power plants – Pressure fluid source and motor – Ram driven by fluid pumped from reservoir
Patent
1994-05-27
1996-04-09
Nguyen, Hoang
Power plants
Pressure fluid source and motor
Ram driven by fluid pumped from reservoir
91361, F16D 3102, F15B 1316
Patent
active
055050433
ABSTRACT:
A hydraulic lift device for battery operated industrial trucks comprising a hydraulic ram, a hydraulic machine operating as a pump in a load raising cycle and as a motor in a load lowering cycle, a separately excited DC machine operating as a motor in the load raising cycle and as a generator in the load lowering cycle, and energy recovering circuitry which is fed by the DC machine in the load lowering cycle. A load holding valve is disposed in the fluid path between the hydraulic ram and the hydraulic machine. Speed of the DC machine is set by a speed control. A separate field current control includes a desired value setting circuit for determining a desired value for the field current (I.sub.FSoll) from a predetermined relationship between the speed (n.sub.Ist) and the armature current (I.sub.ASoll). Power switches are associated with the field winding and the armature, and are actuated by the current control. The power switches are arranged and controlled such than the intensity and the direction of the current through the armature and field winding are defined. The current control comprises a directional setting control for the lowering and raising cycle generating signals to control the load holding valve.
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Baginski Ralf
Claussen Hans-Peter
Doss Hans-Joachim
Klatt Andreas
Korner Jochen
Jungheinrich Aktiengesellschaft
Nguyen Hoang
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