Hitachi Koki Co., Ltd.

Takahiro Fujimaki

Masahiro Inaniwa

Shinji Watanabe

Noriyasu Matsufuji

Hiroyuki Takahashi

Yoshinori Tobita

Nobuharu Kido

Yoshitaka Niinai

Shoji Kusumoto

Satoshi Numata

Tsutomu Takamura

Hisanobu Oyama

A centrifuge including: a rotor rotating with a sample contained therein; a rotating shaft rotatably engaged with the rotor; a motor rotating the rotor and the rotating shaft; a belt transmitting rotational force of the motor to the rotating shaft; a rotor speed detecting unit detecting a rotation speed of the rotor; a motor speed detecting unit detecting a rotation speed of the motor; and a control unit controlling the motor, wherein the control unit calculates a signal for controlling the rotation speed of the rotor on the basis of a signal from the rotor speed detecting unit and controls the motor on the basis of a signal from the motor speed detecting unit and the calculated signal.

Centrifuge

In a centrifugal separator of the type in which driving power of a motor is transmitted to a rotor via a power transmission mechanism, such as a belt, a motor-rotation signal frequency fm and a rotor-rotation signal frequency fr are computed, on the basis of which a frequency ratio A (fr/fm) is computed. When the frequency ratio A exceeds the upper limit of a first predetermined range, a warning message is displayed to prompt the user to perform maintenance. When the frequency ratio A exceeds the upper limit of a second predetermined range, an alarm message is displayed and the motor is stopped.

Belt driven centrifugal separator with multi-stage, belt deterioration alerting display

A centrifugal separator facilitates maintenance with a function that provides the user with useful data for investigating the causes of failures and for preventing their recurrence, such as data needed to determine the appropriate management and replacement frequency of consumable parts. The centrifugal separator also has a storing unit for recording the number of times that the door is opened and closed, operation records of the drive unit by each shaft, and the number of operations performed by operating function, as well as a display unit for displaying the data. The centrifugal separator also includes a function for displaying messages prompting the user to perform maintenance when the aforementioned performance data reach a predetermined value.

Centrifugal separator with a plurality of shafts

A transformer outputs different (high or low) secondary voltages. A switch outputs high or low secondary voltage according to a mode signal. An electric power converter including a rectifying circuit and a switching circuit either charges a smoothing capacitor with an output of the switch or discharges the smoothing capacitor to supply a regenerative current toward the transformer with a power fact improved. An phase signal generation circuit generates PWM or PAM phase signals in accordance with the mode signal. An inverter circuit generates driving signals supplied to the motor in response to the phase signals from power from the smoothing capacitor. A mode determining circuit determines one of modes to generate the mode signal in accordance with a speed command signal and acceleration/deceleration which is indicated by the rotating speed signal and the rotating speed command signal.

Motor control apparatus

A power control apparatus for controlling power supplied to an electric motor rotating a rotor employed in a centrifuge is provided. The power control apparatus includes first and second inverters and a smoothing capacitor disposed between the first and second inverters. In a motor power mode, the first inverter charges the smoothing capacitor with power supplied by an AC power supply, while the second inverter charges, in a motor braking mode, the smoothing capacitor with power regenerated by the motor during a braking operation for returning the regenerated power back to the AC power supply through the first inverter. An reactor is arranged between the AC power supply and the first inverter for reducing harmonic components contained in the current supplied from or back to the AC power supply.

Motor control system for centrifugal machine

A centrifugal protection apparatus including: a rotor having markers connected to a motor responsive to drive signals; first and second detectors for detecting the marker upon rotation of the rotor and generating first and second detection signals respectively; a drive circuit responsive to a command for generating the drive signals from the supply power via input terminal in response to the first or second detection signal; first and second switch circuits, arranged in series between the input terminal and the motor, for controlling the supply of the drive signals to the motor; a current detector for detecting a current of one of the drive signals and generating a current detection signal; and first and second judging portions for detecting whether the first and second detection signals are within a predetermined value and for operating the first and second switch circuits to cut off the drive signals when the first and second detection signals are not within the predetermined value respectively and when a magnitude of the current detection signal is larger than the predetermined value when the second detection signal is not generated. The first and second judging portions, first and second detectors, and the current detector operate in parallel and independently. The first and second switch circuits are arranged in series to provide more dependable protection.

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Hitachinaka, Japan

Takahiro Fujimaki