FLOW RATE CONTROLLER OF VARIABLE DISPLACEMENT HYDRAULIC PUMP

摘要

The present invention provides a flow rate control device of a variable capacity hydraulic pump which can perform both horsepower control and cutoff control. The flow rate control device (1) of a variable capacity hydraulic pump comprises a servo mechanism (2), a conversion mechanism (3), a horsepower control mechanism (4), and a cutoff mechanism (5). The cutoff mechanism (5) comprises: a cutoff piston (51); a first cutoff water pressure chamber (52) to apply a discharge pressure of a hydraulic pump (11) to the cutoff piston (51) to allow the cutoff piston (51) to move a spool (31) of the conversion mechanism (3) in a flow reduction direction; and a second cutoff water pressure chamber (53) to apply a cutoff pressure resisting the discharge pressure of the hydraulic pump (11) to the cutoff piston (51). The cutoff pressure is outputted to the second cutoff water pressure chamber (53) from an electronic proportional valve (8A). A selection mechanism (6) determines which one among a horsepower control piston (41) and the cutoff piston (51) operates the spool (31).