Centrifuge

• US 7,548,034 B2
• Filed: 11/29/2006
• Issued: 06/16/2009
• Est. Priority Date: 11/30/2005
• Status: Expired due to Fees

• Current Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Oyama, Hisanobu, Fujimaki, Takahiro, Takahashi, Hiroyuki
• Primary Examiner(s): Ro; Bentsu
• Assistant Examiner(s): DINH, THAI T
• Application Number:
  US11/564,514
• Publication Number:
  US 20070138988A1
• Time in Patent Office: 930 Days
• Field of Search: 318/268, 318/66, 318/69, 494/7, 494/9, 494/10, 494/84
• US Class Current: 318/268
• CPC Class Codes: B04B 9/10 Control of the drive; Speed regulating for solid bowl screw centrifuges B04B1/2016

Abstract

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.

Claims

1. A centrifuge comprising:

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 that detects an actual rotation speed of the rotor and generates a first signal indicative of the actual rotation speed of the rotor;

a motor speed detecting unit that detects an actual rotation speed of the motor and generates a second signal indicative of the actual rotation speed of the motor; and

a control unit that receives the first signal and the second signal and produces an output signal indicative of a voltage applied to the motor,

wherein the control unit includes;

a target rotor rotation speed output unit that outputs a target rotor rotational speed in accordance with a setting value;

a rotor speed difference calculating unit that receives the target rotor speed and the actual rotor rotation speed detected by the rotor speed detecting unit and calculates difference there between; and

an application voltage calculating unit that receives the actual motor rotational speed detected by the motor speed detecting unit and the difference between the target rotor speed and the actual rotor rotation speed and calculates the voltage applied to the motor.

2. The centrifuge according to claim 1, wherein the control unit further includes an excitation frequency calculating unit that produces a signal to control an excitation frequency of the motor on the basis of the second signal indicative of the actual rotation of the motor.

3. The centrifuge according to claim 1, wherein the motor is an induction motor.

4. The centrifuge according to claim 1, wherein the motor is a brushless DC motor.

5. The centrifuge according to claim 1, wherein the rotor speed detecting unit is disposed at the rotation shaft of the rotor to detect the rotation speed of the rotor.

6. A centrifuge comprising;

a rotor rotating with a sample contained therein;

a rotating shaft rotatably engaged with the rotor;

an induction motor for rotating the rotor through the rotating shaft of the rotor and a transmission belt, the transmission belt being provided between a motor shaft and the rotating shaft of the rotor and having slippage when transmitting rotational force of the motor to the rotating shaft of the rotor, the speed of the induction motor being controlled by a voltage (V) and an excitation frequency (f) applied thereto;

a rotor speed detecting unit that detects a rotation speed of the rotor and generates a first signal indicative of the rotation speed of the rotor;

a motor speed detecting unit that detects a rotation speed of the motor and generates a second signal indicative of the rotation speed of the motor; and

a motor drive unit for driving the induction motor, the drive unit including a control unit that produces the voltage applied to the induction motor on the basis of the first signal indicative of the rotation speed of the rotor and the second signal indicative of the rotation speed of the motor;

wherein the control unit includes;

a target rotor rotation speed output unit that outputs a target rotor rotational speed in accordance with a setting value;

a rotor speed difference calculating unit that receives the target rotor speed and the actual rotor rotation speed detected by the rotor speed detecting unit and calculates a difference there between; and

an application voltage calculating unit that receives the actual motor rotational speed detected by the motor speed detecting unit and the difference between the target rotor speed and the actual rotor rotation speed and calculates the voltage applied to the motor.

7. The centrifuge according to claim 6, wherein the control unit further includes an excitation frequency calculating unit that produces a signal to control an excitation frequency of the motor on the basis of the second signal indicative of the actual rotation of the motor.

8. A centrifuge comprising:

a rotor rotating with a sample contained therein;

a rotating shaft rotatably engaged with the rotor;

a DC brushless motor for rotating the rotor through the rotating shaft of the rotor, and a transmission belt, the transmission belt being provided between a motor shaft and the rotating shaft of the rotor and having slippage when transmitting rotational force of the motor to the rotating shaft of the rotor, the speed of the DC brushless motor being controlled by a voltage (V) and an excitation phase (θ

) applied thereto; and

a motor drive unit for driving the DC brushless motor, the drive unit including a control unit that produces the voltage applied to the brushless motor, on the basis of the first signal indicative of the rotation speed of the rotor and the second signal indicative of the rotation speed of the motor and calculates the excitation phase (θ

) for the DC brushless motor on the basis of the second signal indicative of the rotation of the motor;

wherein the control unit includes;

a target rotor rotation speed output unit that outputs a target rotor rotational speed in accordance with a setting value;

a rotor speed difference calculating unit that receives the target rotor speed and the actual rotor rotation speed detected by the rotor speed detecting unit and calculates a difference there between; and

an application voltage calculating unit that receives the actual motor rotational speed detected by the motor speed detecting unit and the difference between the target rotor speed and the actual rotor rotation speed and calculates the voltage applied to the motor.