To provide a variable displacement gear pump in which the mechanical efficiency of the most frequently operated gear pump can be improved.
The variable displacement gear pump 1 is provided with a drive gear 20 in a casing 10, and a plurality of driven gears 30, 40 engaged with the drive gear 20. A plurality of gear pumps (a first gear pump 50, a second gear pump 60) composed of the drive gear 20 and the driven gear 30, 40 are changed over to operate so that the discharge quantity can be made changed. A sliding resistance reducing means (chip clearance h2, side clearance w2) for reducing a sliding resistance of the least frequently operated (relatively less frequently operated) gear pump (the second gear pump 60) out of a plurality of the gear pumps (the first gear pump 50 and the second gear pump 60), and the mechanical efficiency of the most frequently operated (relatively more frequently operated) gear pump (the first gear pump 50) is improved.
IBARAKI TAKATSUGU
SHIOIRI HIROYUKI
YOSHIDA MICHIO
