Abstract: A bearing lubricating apparatus for a rotary machine has a rotary shaft rotatably supported by a rolling bearing, and an oil receiving portion which receives lubricating oil picked up by a pick-up member. The oil in the oil receiving portion is sucked by a suction nozzle and is sent to interior of the rotary shaft through a first passage. Then, the oil flows back through a second passage into the bearing. Oil supply nozzles are formed in the rotary shaft so that the oil is supplied to the bearing by a pumping action of the oil supply nozzles when the rotary shaft rotates.

Abstract: A multi-stage screw vacuum pump having a reduced number of constituent parts as compared with the conventional one and a reduced overall size. The multi-stage screw vacuum pump comprises an input mechanism for transmitting a driving force derived from a driving source to a former-stage pump, and speed up mechanisms for speeding up the rotation of the former-stage pump for transmission to a latter-stage pump.

Abstract: To provide a screw vacuum pump which is compact and yet capable of attaining a high degree of vacuum. A screw vacuum pump having a pair of male and female rotors 7 and 7A rotating in mesh with each other around two parallel axes, respectively, and a casing 1 for accommodating the two rotors 7 and 7A, the casing 1 having a suction port 8b and a discharge port 9b, the screw vacuum pump further having a process of sucking a gas from the suction port 8b into a space defined between the rotors 7 and 7A, a process of transferring the gas, a process of compressing the gas, and a process of discharging the gas from the discharge port 9b, wherein the suction port 8b is closed early, thereby providing an expansion process between the suction and transfer processes.

Abstract: A screw vacuum pump is designed so that it is possible to reduce the load on the pump at the time of starting and evacuation of a gas under atmospheric pressure. The screw vacuum pump has male and female rotors rotating in mesh with each other around two parallel axes, respectively, and a casing for accommodating the rotors, the casing having a suction port and a discharge port, wherein the discharge port is formed so that V.sub.1 /V.sub.2 is in the range of 1.5 to 0.51, where V.sub.1 is a groove volume defined by the casing and the male and female rotors immediately after a gas has been trapped, and V.sub.2 is a groove volume immediately before the gas is discharged.

Abstract: A screw vacuum pump is capable of reducing the load thereon at the time of evacuation of a gas at atmospheric pressure by the use of a throttle plate. The screw vacuum pump has male and female rotors which rotate in meshing engagement with each other around two parallel axes, respectively, in a casing so that a gas that is sucked in from a suction opening is introduced through a suction port into a groove space defined between the male and female rotors and the casing is then discharged from a discharge opening through a discharge port, wherein the throttle plate is provided upstream of and near the opening of the suction port.

Abstract: The present invention is drawn to a screw compressor having a wide operating range with respect to flow rate and pressure ratio, wherein a discharge opening portion of a casing is provided with a generally tapered notch portion so that compressed gas is gradually discharged from a certain fixed point where a volume ratio of one groove defined by rotors and the casing is smaller than an inherent built-in volume ratio. Since the present invention is arranged in the above-mentioned manner, the flow of the gas at the discharge opening portion is reduced by the notch portion which is readily formed. Thereby the variation range of the pressure (the amplitude of pulsation of the pressure) is decreased and the noise level is lowered. Further, a loss of pressure resulting from the rapid flow of the gas is restricted to thereby widen a range of preferable performance of the compressor.

Abstract: A muffler is constructed to have a tubular perforated plate within its cavity so as to divide the cavity into an outer resonant cavity and an inner resonant cavity, to thereby provide two resonant frequencies. The tubular perforated plate is formed in the shape of a funnel.

Abstract: There is proposed a tilt sensor in which a permanent magnet having a surface coated with a magnetic field is housed in a hollow portion of a nonmagnetic case, and a magnetic sensing element is disposed outside a bottom portion of the case. When the case is tilted at an angle exceeding a predetermined angle, the permanent magnet is greatly moved and the magnetic sensing element detects the movement of the magnet. Furthermore, adverse influences due to magnetic attraction between the permanent magnet and the magnetic sensing element or a surface tension of the magnetic fluid are compensated.

Abstract: A switchable magnetic chuck has a magnet assembly slidably arranged in a casing to magnetize and demagnetize a top plate disposed in an open side of the casing. The top plate is provided with main pole members and auxiliary pole members which are arranged alternatively in the sliding direction of the magnet assembly, separated respectively by a non-magnetic separator disposed between them. To smoothen the change-over operation, enhance magnetic force under the magnetized condition and reduce residual attraction under the demagnetized condition, each main pole member is formed on the side facing the magnet assembly with an extension extending between the auxiliary pole member adjacent thereto and the magnet assembly.

Abstract: A magnet assembly used as a magnetism generating source for attaching an article to a magnetic substance or for magnetically retaining a magnetic member. The magnet assembly consists of a cylindrical casing open at least at one end, a core disposed within the casing at a spacing from an inner wall thereof, with one end of the core aligned with the open end face of the casing, and a permanent magnet disposed between the core and the inner peripheral surface of the casing. The permanent magnet has one magnetic pole on an outer surface thereof opposing the inner peripheral surface of the casing, and the other magnetic pole opposite the magnetic pole on an inner surface thereof opposing the outer peripheral surface of the core, so that the open end face of the casing and the end face of the core serve as a magnetic attraction surface.

Abstract: A switchable permanent magnet holding device in which a permanent magnet rotatably disposed within a bore in a magnetic circuit block is rotated, so that the magnetism acting surfaces of the magnetic circuit block are brought into an exciting state for retaining a magnetic substance thereon and into a non-exciting state for releasing the magnetic substance therefrom. The permanent magnet is pressed against a stopper for impeding rotation thereof, due to a gyromagnetic force acting across the permanent magnet and the magnetic circuit block when the permanent magnet is rotated to a position in which the magnetism acting surfaces of the block become exciting.

Abstract: A magnetic base adapted to be secured to a magnetic substance attractively, wherein a permanent magnet 20 having a small reversible permeability .mu. is employed as a rotary magnet housed in a magnetic block 18 and rotated for switching magnetic active surfaces 24 of the block from an unexcited state to an excited state, thereby effecting a light and smooth rotation.