Boc Edwards Japan Limited

Seiko Seiki Kabushiki Kaisha

Masayuki Yamamoto

Akira Yamauchi

Toshiaki Kawashima

To provide a magnetic bearing device capable of lowering the costs required for the manufacture, installation, or the like of a turbo molecular pump by reducing the number of elements of an amplifier circuit that drives, through excitation, electromagnets as well as the number of wires of a cable that connects the each electromagnet and the amplifier circuit to each other, and a turbo molecular pump with the magnetic bearing device mounted thereto. One end of an electromagnet coil is connected to a common node. Also, the other end thereof is connected to an amplifier circuit composed of one transistor and one diode. Further, the one end of the electromagnet coil is common with respect to each of the electromagnets, and the common node R is controlled by an intermediate-voltage maintaining circuit so as to maintain an intermediate voltage.

Magnetic bearing device and turbo molecular pump with the magnetic bearing device mounted thereto

To reduce vibration caused by an unbalance of magnetic force generated in a motor portion due to run-out of a rotor in a magnetic bearing apparatus having the motor portion. The vibration of the rotor is detected by means of a radial direction sensor mounted for controlling a magnetic bearing. Then, the vibration in the motor portion is inferred from the run-out of the rotor detected by the radial direction sensor by using the geometric positional relationship between the rotor and the radial direction sensor. The relationship between the unbalance amount of the magnetic force and the amount of run-out of the rotor in the motor portion is formed into the database through experiments or simulation in advance, and the unbalance amount of magnetic force is obtained from this database. Then, the magnetic force resisting the unbalance amount of this magnetic force is generated to offset this unbalance amount.

Growing community of inventors

Narashino, Japan

Masayuki Yamamoto