초록 ▼

A control system for variable displacement hydraulic pumps for use in a hydraulically operated construction vehicle having a fixed displacement hydraulic pump, a plurality of reducing valves operatively interlocked with work implement control valve units of the vehicle disposed on the delivery sides

A control system for variable displacement hydraulic pumps for use in a hydraulically operated construction vehicle having a fixed displacement hydraulic pump, a plurality of reducing valves operatively interlocked with work implement control valve units of the vehicle disposed on the delivery sides of the variable displacement pumps, control sections for controlling respective flow rate of the variable displacement pumps and equipment for exerting delivery pressures of both the fixed and variable displacement pumps and output pressure of the reducing valve on the control units. The control system exhibits three control functions, i.e., flow control for varying the angle of the swash plate of the variable displacement pump in proportion to the manipulating position of the respective work implement controlling valve, constant torque control in proportion to the delivery pressures of the variable displacement pumps, and cut-off control for reducing relief losses.

대표청구항 ▼

A control system for variable displacement hydraulic pumps comprising: (a) a fixed displacement hydraulic pump for supplying a control fluid pressure for a hydraulic servo mechanism; (b) a plurality of reducing valve means operatively interlocked with work implement control valve units disposed on t

A control system for variable displacement hydraulic pumps comprising: (a) a fixed displacement hydraulic pump for supplying a control fluid pressure for a hydraulic servo mechanism; (b) a plurality of reducing valve means operatively interlocked with work implement control valve units disposed on the delivery sides of a plurality of variable displacement hydraulic pumps, said reducing valve means being adapted to convert the delivery pressure of said fixed displacement hydraulic pump into the output pressure of the reducing valve in proportion to respective displacements of said control valve units by the manipulation thereof; (c) control units for controlling respective flow rate of said variable displacement pumps, each control unit including a servo piston section adapted to selectively receive the delivery pressure of said fixed displacement hydraulic pump on either side thereof to thereby control the delivery pressures of said variable displacement hydraulic pumps, a guide section adapted to control the delivery pressure of said fixed displacement hydraulic pump to selectively direct it on either side of said servo piston section, and an input signal section adapted to receive the delivery pressure of said fixed displacement hydraulic pump, the output pressure of said reducing valve means and respective delivery pressures of said variable displacement hydraulic pumps so as to control said guide section; and (d) means adapted to exert the delivery pressure of said fixed displacement hydraulic pump, the output pressure of said reducing valve and respective delivery pressures of said variable displacement hydraulic pumps on said control units, respectively.