Patent ID: 6315517
Filing Date: 2001-11-13
Classification: F04D

Abstract:
A vacuum pump comprising: an inlet port into which a gas is introduced; an outlet port from which the gas is discharged; a stator; a motor; and a rotor opposing the stator and driven by the motor to undergo rotation to cooperate with the stator to force the gas from the inlet port to the outlet port, the rotor having a body, a spiral thread disposed on the body, and a thread groove disposed between adjacent lines of the spiral thread, an axial length of the spiral thread being shorter than an axial length of the rotor so that a terminal end portion of the spiral thread terminates short of an axial end of the rotor, the terminal end portion of the spiral thread sloping inward toward a surface portion of one of the thread grooves, and a junction surface between a terminal end portion of the slope of the spiral thread and the surface portion of the thread groove forming a recessed portion.