Abstract: In a grease filled bearing for a machine such as a turbo molecular pump that rotates at high speed, objects are to prevent grease retained in an inner circumferential part of a ball retainer from being forced out to the outside of the bearing due to centrifugal force, thereby achieving extension of the operational life of the bearing, and preventing occurrence of rotational mass unbalance due to the grease forced out. A retainer (1) of a ball bearing includes a main body (1A) having a circular annular shape, and plural circular pockets (1a) for retaining balls (4) therein that extend through the main body (1A) in a radial direction, wherein intermediate parts between adjacent pockets (1a) in an inner circumferential surface of the main body (1A) define recesses (1b) for holding grease.

Abstract: In a grease filled bearing for a machine such as a turbo molecular pump that rotates at high speed, objects arc to prevent grease retained in an inner circumferential part of a ball retainer from being forced out to the outside of the bearing due to centrifugal force, thereby achieving extension of the operational life of the bearing, and preventing occurrence of rotational mass unbalance due to the grease forced out. A retainer (1) of a ball bearing includes a main body (1A) having a circular annular, shape, and plural circular pockets (1a) for, retaining balls (4) therein that extend through the main body (1A) in a radial direction, wherein intermediate parts between adjacent pockets (1a) in an inner circumferential surface of the main body (1A) define recesses (1b) for holding grease.

Abstract: A thread groove type vacuum pump in which the gap between a rotor and a stator is not subjected to any influence of the rotor temperature and thus the pumping performance does not deteriorate during plasma combustion in a nuclear fusion reactor. The thread groove pumping portion is formed as a circular cone so that the expansion and contraction of the rotor occurs along the generatrix of the circular cone. The pump exhibits supreme pumping performance throughout the whole running mode of the vacuum pumping system of the nuclear fusion reactor because the gap between the rotor and the stator is kept constant despite changes of thermal expansion due to the temperature change of the rotor caused by the different gas loads.

Abstract: Disclosed is a vacuum pump having a peripheral groove vacuum pump unit which includes a casing provided with an inlet port and an outlet port; a rotor disposed within the casing and including a rotor shaft journaled on the casing, a rotor body fixed to the rotor shaft and provided integrally with a rotor disk; and a stator fixedly disposed within the casing and provided with an annular groove receiving the peripheral portion of the rotor disk. Both sides of the peripheral portion of the rotor disk are cut in steps or portions of the side walls of the annular groove corresponding to the peripheral portion of the rotor disk are cut in annular recesses to form flow passages on both sides of the peripheral portion of the rotor disk. Partitions are projected from the stator into the flow passages. The starting ends of the flow passages on the inlet side of the partitions communicate with the inlet port, and the terminating ends of the same on the outlet side of the partitions communicate with the outlet port.

Abstract: A vacuum pump includes a casing provided with an inlet port and an outlet port; a turbo molecular pump unit disposed in an uppermost section, with respect to a flow direction of the gas, of the casing; a peripheral groove vacuum pump unit disposed in a middle section of the casing; and a vortex vacuum pump unit disposed in a lowermost section, with respect to the flow direction of the gas, of the casing.

Abstract: A vacuum pump includes a casing provided with an inlet port and an outlet port, a peripheral groove vacuum pump unit disposed in an upper section, with respect to a flow direction of the gas, of the casing, and a vortex vacuum pump unit disposed in a lower section, with respect to the flow direction of the gas, of the casing. The vacuum pump unit and the vortex vacuum pump unit have a common rotor. Since the common rotor is provided for the vacuum pump unit and the vortex vacuum pump unit, the dynamic balance of the rotor can be easily adjusted and the rotor rotates with a minimal amount of vibration.

Abstract: Disclosed is a vacuum pump having a peripheral groove vacuum pump unit which includes a casing provided with an inlet port and an outlet port; a rotor disposed within the casing and including a rotor shaft journaled on the casing, a rotor body fixed to the rotor shaft and provided integrally with a rotor disk; and a stator fixedly disposed within the casing and provided with an annular groove receiving the peripheral portion of the rotor disk. Both sides of the peripheral portion of the rotor disk are cut in steps or portions of the side walls of the annular groove corresponding to the peripheral portion of the rotor disk to form flow passages on both sides of the peripheral portion of the rotor disk. Partitions are projected from the stator into the flow passages. The starting ends of the flow passages on the inlet side of the partitions communicate with the inlet port, and the terminating ends of the same on the outlet side of the partitions communicate with the outlet port.

Abstract: Disclosed is a vacuum pump having a peripheral groove vacuum pump unit which includes a casing provided with an inlet port and an outlet port; a rotor disposed within the casing and including a rotor shaft journaled on the casing, a rotor body fixed to the rotor shaft and provided integrally with a rotor disk; and a stator fixedly disposed within the casing and provided with an annular groove receiving the peripheral portion of the rotor disk. Both sides of the peripheral portion of the rotor disk are cut in steps or portions of the side walls of the annular groove corresponding to the peripheral portion of the rotor disk are cut in annular recesses to form flow passages on both sides of the peripheral portion of the rotor disk. Partitions are projected from the stator into the flow passages. The starting ends of the flow passages on the inlet side of the partitions communicate with the inlet port, and the terminating ends of the same on the outlet side of the partitions communicate with the outlet port.

Abstract: A hollow cylindrical stator and a cylindrical rotor are disposed in the stator with a gap therebetween, the inner peripheral surface of the stator or the outer peripheral surface of the rotor being provided with a helical groove, or thread groove, and evacuation being performed by rotation of the rotor. The width of the helical groove adjacent the suction side of the pump is larger than the width of a ridge between adjacent turns of the groove.