Patent ID: 7942567

Claim:
An extruder system with a gear pump, comprising an extruder for axially extruding a rubber or plastic material in a barrel by rotation of an extrusion screw arranged in the barrel, and a gear pump driven by a rotational force for rotating the extrusion screw so that a predetermined amount of the material extruded from the extruder is discharged by engagement of gears, wherein: the gear pump comprises a driving pinion arranged coaxially to the extrusion screw and fixedly secured to a tip end of the extrusion screw, at least one driven pinion meshed with, and driven by the driving pinion and rotatable about a rotational shaft that is parallel to a rotational shaft of the extrusion screw, and a gear casing housing the driving pinion and the at least one driven pinion; the gear casing comprises side plates arranged on both axial sides of the driving pinion and the at least one driven pinion leaving a small clearance from the driving pinion and the at least one driven pinion, and extending perpendicularly to the rotational shaft of the extrusion screw, and a casing body arranged between the side plates and enclosing a space on a radially outer side of the driving pinion and the at least one driven pinion, the casing body comprising a plurality of axial opening portions, each axial opening portion housing a respective pinion selected from a group consisting of the driving pinion and the at least one driven pinion, the each opening portion substantially conforming in size and shape to an outer circumferential profile of the respective pinion such that a space on the radially outer side of the respective pinion is minimized so that the predetermined amount of material extruded flows between teeth of each respective pinion in operation; the rotational shaft of the at least one driven pinion is fixedly secured to the side plates; the side plates include a side plate situated on the suction side adjacent to the extrusion screw and a side plate situated on the discharge side remote from the extrusion screw, the side plate on the suction side having a suction port that is arranged opposite to that side of an engagement region between the driving pinion and the at least one driven pinion, where teeth of the driving pinion and the at least one driven pinion are being disengaged from each other, and the side plate on the discharge side having a discharge port that is arranged opposite to that side of the engagement region between the driving pinion and the at least one driven pinion, where the teeth of the driving pinion and the at least one driven pinion are being engaged from each other, the suction port and the discharge port being maintained out of an axial communication with each other by the driving pinion and the at least one driven pinion, and the casing body further comprises a plurality of recesses positioned at each axial end of at least one of the plurality of axial opening portions, the plurality of recesses being partially non-overlapping with the suction port and the discharge port.