Abstract: A magnetic bearing is provided with a simulating circuit for estimating a displacement of a rotor on the basis of a force which is exerted on the rotor. An output of the simulating circuit is compared with an actual displacement signal. A delay circuit and a subtracter are provided to subtract a run-out, which was estimated one period before the rotation of the rotor, from the displacement signal. A displacement signal from which the run-out component was eliminated is set to a new displacement signal. A signal which is obtained by adding an estimated run-out of one period before, namely, an output of the delay circuit to the run-out which was estimated by comparing the output of the simulating circuit with the new displacement signal is newly inputted to the delay circuit.

Abstract: A controller of magnetic bearing controls the rotor speed with a reduced drive current while suppressing the rotor vibration. The controller implements the ABS control, N-cross control, N-straight control and FF control in proper combination in addition to the basic PID control. A computer in the controller determines the activation of each control in accordance with a predetermined table of control plan in response to the detected rotor speed.

Abstract: A balancing method for balancing a flexible rotor is disclosed. First, the rotor is rotated and vibration of the rotor is measured to determine resonance speeds. Vibration exciting forces of frequencies synchronized with the rotor rotation in two orthogonal directions are imparted to the rotor or rotor support bearings while rotating the rotor at a speed near the respective resonance speeds. The amplitude and the phase of the vibration exciting force which reduces the resonance vibration of the rotor are then determined. A correction weight on the basis of the amplitude and the phase of the vibration exciting force is then determined. Balancing work on the rotor such as grinding of the rotor or addition of a mass to the rotor in accordance with the correction weight is then carried out, followed by a rotor rotation conducted for the purpose of confirming the effect of the balancing work.

Abstract: A control method and apparatus for suppressing the vibration components of a magnetic bearing. According to this invention, a vibration wave is sampled at pulses synchronized with the rotation of a rotor, the vibration waveform sampled values at each revolution are averaged, and only the frequency components synchronized with the rotation frequency of the rotor are extracted from the vibration waveform. In addition, the extracted components are subjected to Fourier transform, processed in a frequency region and subjected to Fourier reverse transform. The sequence of these signal processes produces a signal, and the vibration components are suppressed by this signal.

Abstract: A rotary compressor has an electric motor and a compressing mechanism drivingly connected together by a crank shaft and disposed in a closed housing. The compressing mechanism has a rolling piston rotatable in a cylinder bore and driven by an eccentric portion of the crank shaft. First, second and third balancers are mounted on an end of the crank shaft and on the opposite ends of a motor rotor, respectively. The second and third balancers are formed therein with weight-adjusting holes by which the masses of the second and third balancers are finely adjusted to fall within tolerable ranges.

Abstract: A rotary magnetic head apparatus for use in a VTR and producing a low level of vibration by restraining the unbalance of an overall rotary body of the magnetic head apparatus. The apparatus includes a fixed cylinder for supporting a rotary shaft via bearings, a rotary cylinder secured to one end of the rotary shaft and having magnetic heads, and a motor rotor directly coupled with the other end of the rotary shaft. At least one first balancer and at least one second balancer are respectively provided in the rotary cylinder and the rotor so as to compensate for the unbalance of the rotary body composed of the rotary cylinder, the rotary shaft, and the rotor.

Abstract: This invention relates to a magnetic disk apparatus equipped with magnetic bearings for supporting a spindle without contact by a magnetic attracting or repulsing force. The magnetic disk apparatus prevents occurrence of oscillation of magnetic disks and accomplishes high accuracy positioning.

Abstract: A band pass filter multiplies an input waveform with first trigonometric functions at a plurality of frequencies and then filters the products. Furthermore, with that filtering step, the products are multiplied, or their phase is changed by a predetermined value, and the results are multiplied by the inverse of the trigonometric functions.The sum of this, for all frequencies, generated a filtered output waveform. Where the input waveform has two components, the corresponding outputs can be obtained from the read and imaginary components of the output waveform. In practice the trigonometric functions are produced by sine and cosine components at each frequency. In this way a band pass filter device is formed which is suitable for use in the control system of an apparatus which must be controlled continuously, such as a control system for a rotor.

Abstract: In an electromagnetic bearing control apparatus for suppressing vibratory rotational motion of a rotor, a selective extraction unit is provided in servo-circuits which control currents being supplied to electromagnetic coils in accordance with x and y-component signals of radial displacement of the rotor such that the rotor is held in a predetermined radial position, and x and y-component signals delivered out of the selective extraction unit are crossed and inputted to the servo-circuits so as to be added in opposite polarities to processed x and y-component signals of radial displacement.

Abstract: A turbomolecular vacuum pump having stator blades disposed in a multistage fashion within a casing in an axial direction thereof, and rotor blades which are located between respectively adjacent stator blades and are mounted on an outer periphery of a rotor situated centrally of the casing. A motor rotor is fixed to a rotating member which is formed of the rotor having the rotor blades fixed to the outer periphery, and a motor stator opposite to the motor rotor is arranged so as to construct a drive mechanism for the rotating member. The rotating member is supported at a lower portion thereof by a pivot-type plane bearing, and a magnetic bearing is arranged in such a manner so as to oppose a lower end of the rotor and a supporting member for the rotating member.

Abstract: A turbomolecular pump for evacuating a space by a plurality of turbine grooves located on a rotor and a stator located in face-to-face relationship to the rotor, with the turbine grooves, including rotor grooves on an outer peripheral surface of a rotor extending peripherally at a predetermined angle with respect to the axis of the rotor, and stator grooves on a surface of a stator facing the rotor which extend at the same angle as the rotor grooves but are oriented in an opposite direction to the rotor grooves. The rotor grooves and stator grooves overlap in part as viewed axially of the rotor. A pumping action is performed by surfaces of blades of an axial flow turbomolecular pump and a pumping action is performed by the rotor and the bottom surface of the groove of a helical groove turbomolecular pump, whereby a high compression ratio and a high gas discharge or evacuation speed can be achieved.

Abstract: The present invention reduces the resonance amplitude of the rotational frequency-synchronous unbalance vibration of a rotor supported by an electromagnetic bearing.To this end, the invention disposes an X-direction control servo circuit and a Y-direction control servo circuit each of which detects the deviation of the rotor from a desired position in the radial direction thereof and controls the rotor so as to be held at the desired position on the basis of the detection signal, and a tracking filter which is synchronous with the rotational frequency. Outputs from the filter are crossed to supply the Y-direction control servo circuit with the X-directional output and to supply the X-direction control servo circuit with the Y-directional output signal.

Abstract: A method and apparatus for monitoring cracks of a rotatable body by detecting cracks by measuring accoustic emission signals and evaluating the depth of cracks from the result of the comparison of assumed vibrations of the rotatable body and its measured vibrations. By this method and apparatus not only the beginning of cracking of the rotatable body, but also the progress of cracking on an online basis can be detected and monitored.

Abstract: A turbomolecular pump including a casing stationary blades arranged in a plurality of stages in the casing axially thereof, rotating blades arranged between the stationary blades and located on an outer periphery of a rotor located in a central portion of the casing, and a bearing device journaling the rotor at its high vacuum and end a low vacuum end. A first permanent magnet of the fixed side having a high Curie point and a second permanent magnet of the rotor side located in juxtaposed relation to the first permanent magnet constitute a magnetic bearing of an attraction type for journaling the rotor at its high vacuum end. A pivot type hydrodynamic bearing or active magnetic bearings journal the rotor at its low vacuum end.

Abstract: A rotary fluid machine such as, for example, a screw compressor, a centrifugal compressor, or a pump, is provided with a thrust bearing mounting unit adapted to maintain natural frequencies of bending vibrations of rotors thereof within ranges of permissible values. The axial rigidity of the mounting unit is at least as high as that of the thrust bearings and the radial rigidity thereof is made to be not more than half that thereof. When a radial load is applied to the thrust bearings, the bearing mounting unit is deformed solely substantially in the radial direction and the thrust bearings bear substantially no radial load.

Abstract: A device for identifying an acoustic sound producing location in an axial direction of a rotating body by using an acoustic signal and a rotational pulse signal. In the device, a rubbing location identifying signal is provided in synchronism with the rotational pulse signal in which the pulse interval corresponds to the distance between acoustic sensors or a rotor length. A phase of a peak in a rubbing location identifying signal as measured with respect to the pulse represents an acutal rubbing location.