Abstract: The present invention provides a vacuum pump allowing process pressure control with high responsiveness and miniaturization and cost reduction of the overall apparatus, as well as reduction of the running cost. A second pump mechanism portion is equipped on the way of an exhaust passage communicating an exhaust side out of a first pump mechanism portion with a gas outlet. The second pump mechanism portion is constructed to be capable of changing the pump speed of rotation independently of the first pump mechanism portion. When the pump speed of rotation of the second pump mechanism portion is changed, the pressure of the exhaust side out (backing pressure) of the first pump mechanism portion changes. Therefore, efficiency of gas suction from a gas inlet to the first pump mechanism portion side is increased or decreased, and the pressure in a process chamber is changed.

Abstract: A screw groove-type pump has a rotor member mounted for undergoing rotation, a stator member arranged so as to be coaxial with the rotor member and having a peripheral wall disposed opposite to and spaced-apart from a circumferential wall of the rotor member, an inlet port for introducing gas into a space between the circumferential wall of the rotor member and the peripheral wall of the stator member, and an outlet port for discharging gas introduced into the space between the circumferential wall of the rotor member and the peripheral wall of the stator member. A screw groove is formed on one of the circumferential wall of the rotor member and the peripheral wall of the stator member for transferring gas introduced into the inlet port through the space between the circumferential wall of the rotor member and the peripheral wall of the stator member and to the outlet port during rotation of the rotor member.

Abstract: A vacuum pump has an inner cylinder having a hollow portion in fluid communication with atmospheric air, an inner flange disposed on an upper side of the inner cylinder, and an inner sealing groove disposed on an upper end surface of the inner flange. An outer cylinder is disposed over the inner cylinder. The outer cylinder has an outer flange disposed on an upper side of the outer cylinder and an outer sealing groove disposed on an upper end surface of the outer flange. An intake port is disposed at the upper side of the inner and outer cylinders. An exhaust port is disposed at lower sides of the inner and outer cylinders. A pump mechanism pumps gaseous molecules from the intake port to the exhaust port to discharge the gaseous molecules from the exhaust port.

Abstract: A vacuum pump comprises 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 has 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 is 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 slopes inward toward a surface portion of one of the thread grooves. A junction surface between a terminal end portion of the slope of the spiral thread and the surface portion of the thread groove forms a recessed portion.

Abstract: A vacuum pump has a rotor body having multiple stages of rotor blades each comprising a plurality of open-ended blades. The uppermost rotor blade formed on the rotor body is located in a position corresponding to a conical portion in a casing. The tip end of the rotor blade is inclined at the same angle as an inclination angle of the conical portion. Accordingly, gas molecules accelerated at the tip end of the rotor blade in a gas molecular region are unlikely to impinge on the casing, and are prevented from staying so that deterioration in discharge capabilities at the tip end can be suppressed. The uppermost rotor blade is located at the conical portion, making it possible to effectively transport the gas molecules toward the outer periphery of the second and following rotor blades.