초록 ▼

A rotary motor and a rotary magnetic bearing are integrated in a compact assembly that is contact-less. A stator assembly surrounds a ferromagnetic rotor with an annular air gap which can accommodate a cylindrical wall, e.g. of a chamber for semiconductor wafer processing. The stator assembly has a

A rotary motor and a rotary magnetic bearing are integrated in a compact assembly that is contact-less. A stator assembly surrounds a ferromagnetic rotor with an annular air gap which can accommodate a cylindrical wall, e.g. of a chamber for semiconductor wafer processing. The stator assembly has a permanent magnet or magnets sandwiched between vertically spaced magnetic stator plates with plural pole segments. The rotor is preferably a ring of a magnetic stainless steel with complementary pole teeth. The stator assembly (i) levitates and passively centers the rotor along a vertical axis and against tilt about either horizontal axis, (ii) provides a radial position bias for the rotor, and (iii) establishes a motor flux field at the rotor poles. Polyphase coils wound on the stator plates produce a rotating flux field that drives the rotor as a synchronous homopolar motor. A rotor without pole teeth allows operation with an asynchronous inductive drive. A controller energizes control coils wound on each stator pole segment in response to a sensed physical position of the rotor. The control coils provide active radial position control and can actively damp tip and tilt oscillations that may overcome the passive centering.

대표청구항 ▼

[ What is claimed is:] [1.] A process for rotating and levitating a mass within a cylindrical wall about a vertical z-axis with a motor having a stator assembly and a rotor, the rotating occurring without frictional contact between the stator assembly and the rotor, and with the cylindrical wall loc

[ What is claimed is:] [1.] A process for rotating and levitating a mass within a cylindrical wall about a vertical z-axis with a motor having a stator assembly and a rotor, the rotating occurring without frictional contact between the stator assembly and the rotor, and with the cylindrical wall located in an air gap between the stator assembly and the rotor, comprising,forming the rotor as a ring of a ferromagnetic material with a high magnetic permeability and with two flanges mutually spaced along the z-axis and each extending toward the stator assembly,forming the stator assembly as a pair of pole plates that are each vertically aligned with one of said flanges and which sandwich a permanent magnet, said pole plates having a polyphase drive coil and position control coils wound thereon, said position control coils being wound on a plurality of angularly spaced pole segments,passively levitating and centering the rotor in the stator assembly along the z-axis with a DC magnetic flux field, which also centers the rotor against tilt out of a plane orthogonal to the z-axis, said DC flux field originating at said permanent magnet of the stator assembly,simultaneously radially biasing the rotor with said DC magnetic flux field,simultaneously inducing a flux field in said rotor with said DC magnetic flux field applied across the air gap and through the cylindrical wall,driving the rotor to rotate about the z-axis using a rotating electromagnetic field produced by said drive coil at the stator assembly which interacts with said flux field induced in the rotor by said DC magnetic flux field, said rotating electromagnetic field being applied across said air gap and through the cylindrical wall,sensing at least the radial position of the rotor with respect to the stator assembly, andadjusting with said control coils the DC magnetic flux at angularly spaced regions about the stator assembly in response to said sensing to maintain spacing between said rotor and said stator assembly during said driving.