Patent ID: 6715847
Filing Date: 2004-04-06
Classification: B60T,F04C,F05C

Abstract:
A rotary pump comprising:an outer rotor provided with inner teeth at an inner circumference thereof; an inner rotor provided with outer teeth at an outer circumference thereof, the outer teeth being in mesh with the inner teeth so as to constitute a plurality of teeth gap portions therebetween, the teeth gap portions having a first closed region whose teeth gap volume is largest and a second closed region whose teeth gap volume is smallest; a drive shaft fitted to the inner rotor for rotating the inner rotor together with the drive shaft; and a casing provided with a rotor room in which the inner and outer rotors are rotatably contained with an outer circumference clearance between an inner circumferential surface of the rotor room and an outer circumferential surface of the outer rotor, and intake and discharge ports communicating respectively with the teeth gap portions, wherein fluid is sucked from the intake port, compressed through the teeth gap portions and discharged from the discharge port when the drive shaft is driven, while fluid pressure difference between the intake and discharge ports is maintained by limiting brake fluid leakage though a teeth top clearance between the outer and lower teeth at the first and second closed regions, and wherein the outer rotor has deformation assist means for allowing the rotor to deform, when the fluid is discharged from the discharge port, so that the teeth top clearance of at least one of the first and second closed regions is narrowed, and wherein the teeth gap portions communicating with the intake port has a first low pressure teeth gap portion adjacent to the first closed region, a second low pressure teeth gap portion adjacent to the second closed region and a third low pressure teeth gap portion provided between the first and second low pressure teeth gap portions, and the fluid discharge pressure is applied to a first outer circumference surface that is positioned radially outside the first low pressure teeth gap portion and a second outer circumference surface that is positioned radially outside the second low pressure teeth gap portion at the outer circumference surface of the outer rotor so that the first and second outer circumference surfaces are pressed radially inward to deform the outer rotor due to pressure difference between the high pressure outer circumference chamber and the first or second low pressure teeth gap portion.