Patent ID: 6568929
Filing Date: 2003-05-27
Classification: F04C

Abstract:
A trochoid gear pump for sucking fluid from an inlet port and delivering fluid from an outlet port, the trochoid gear pump comprising:an inner gear having trochoid outer teeth formed on an outer periphery thereof, the inner gear being adapted to be rotated; an outer gear having trochoid inner teeth formed on an inner periphery thereof and a cylindrical outer periphery; a cylindrical pump casing having an inner bore, the cylindrical outer periphery of the outer gear being rotatably supported in the inner bore of the cylindrical pump casing, so that the trochoid inner teeth of the outer gear rotatably contact the trochoid outer teeth of the inner gear in an eccentric relation, forming pumping chambers between the inner teeth and the outer teeth; a plurality of blade ditches formed on the cylindrical outer periphery of the outer gear; a pressure-introducing port, formed on the inner bore of the pump casing, communicating with the blade ditches; a pressure-releasing port, formed on the inner bore of the pump casing, communicating with the blade ditches; wherein: the fluid introduced into the blade ditches is pressurized to generate an outer imbalance load imposed on the cylindrical outer periphery of the outer gear; and the pressure-introducing port and the pressure-releasing port are so positioned on the inner bore of the pump casing that the outer imbalance load cancels at least part of an inner imbalance load generated in the pumping chambers and imposed on the inner periphery of the outer gear.