The present invention provides a magnetic rotor bearing for suspending a rotor in a contact-free manner, in particular the rotor of an axial- or radial-centrifugal blood pump, comprising a permanent- and electromagnet arrangement which stabilizes the position of, and suspends the rotor in a stator, in particular a housing, and comprises a circuit arrangement connected to at least one position sensor or to the position sensor operating circuit thereof for the rotor. The rotor is suspended in the stator in a stable, contact-free manner by means of a permanent magnet arrangement except for a single geometric adjusting degree of freedom. The position of the rotor is stabilized only within the geometric adjusting degree of freedom not stabilized by the permanent magnet arrangement, by a permanent magnet arrangement located in the rotor and comprising at least one permanent magnet. The permanent magnet arrangement which co-operates with the electromagnet arrangement comprises at least one permanent magnet of the permanent magnet arrangement provided for suspending the rotor and consists in particular, of the permanent magnets of this permanent magnet arrangement positioned in the rotor. The circuit arrangement is a control circuit stabilizing the position of the rotor, during the absence of external forces, in a position of minimum energy requirement of the electromagnet arrangement.

Magnetic rotor bearing

The tool-holding spindle assembly, particularly for a grinding machine, comprises means for supporting the shaft of the spindle and a power drive, for example an electric motor for rotating the spindle. The support means comprise at least one electromagnetic radial bearing controlled by a radial detector, having an annular armature mounted on the shaft of the spindle and a fixed armature surrounding this annular armature, an electromagnetic axial bearing having a disc-shaped armature mounted on the shaft of the spindle and a fixed armature, a chain for controlling the radial and/or axial position of the spindle, said chain being connected on the one hand to at least one detector of the radial and/or axial position of the spindle, and on the other hand to excitation coils of the armatures of each magnetic bearing, and means for selectively modifying the signal generated by said at least one position detector. This tool-holding spindle assembly makes it possible to give a rotating spindle a high speed of rotation and the desired rigidity for obtaining a very high machining precision. Further, precise displacements of the tool of limited amplitude may be controlled by modifying the detector's output signal.

Tool holding spindle assembly particularly for a grinding machine

A controlled radial magnetic bearing device, which consists of a revolution number detector (14) for detecting the rotational speed of a rotary shaft (1) with respect to X-axis and Y-axis control circuits 7X, 7Y, which are adapted to control the outputs from X-axis and Y-axis electromagnets provided so as to extend in X- and Y-axis directions which cross each other in a plane extending at right angles to the axis of the rotary shaft (1), by feedback-inputting into the circuits 7X, 7Y the outputs from X-axis and Y-axis position sensors 5X, 5Y which are adapted to detect the displacement of the rotary shaft (1) from a reference position; an X-axis correction circuit 13X composed of a band-pass filter 19X for extracting a frequency component of backward precession from an output from the Y-axis position sensor 5Y, a means 20X for varying an output from the filter in accordance with an output from the detector (14), and an adder means for adding to an output from the X-axis position sensor 5X an output from the means 20X as an output representative of a 90o advancement of the phase of a backward precession frequency output; and a Y-axis correction circuit 13Y having the same construction as the X-axis correction circuit and including a circuit (22) adapted to reverse an output from the X-axis position sensor 5X. This arrangement enables the outputs from the X- and Y-axis control circuits to be attenuated with respect to a backward precession frequency component, and the precession of the rotary shaft (1) to be thereby effectively reduced.

Controlled radial magnetic bearing device

A device for reducing the vibrations of a rotating machine equipped with an active magnetic suspension comprises at least two vibration detectors located on the machine frame for detecting disturbances applied to the frame, and at least an additional selection feedback loop with narrow band and high gain whose central frequency is synchronized with a reference frequency and which receives signals delivered by the vibration detectors. The additional selective feedback loop comprises means for integrating the signals delivered by the vibration detectors and filtering means for eliminating the transient signals whose frequency is not linked to the reference frequency.

Method and device for reducing the vibrations of rotating machines equipped with an active magnetic suspension

A rotor-stator structure for electrodynamic machinery is disclosed to, among other things, minimize magnetic flux path lengths and to eliminate back-iron for increasing torque and/or efficiency per unit size (or unit weight) and for reducing manufacturing costs. In one embodiment, an exemplary rotor-stator structure can comprise a shaft defining an axis of rotation, and a rotor on which at least two substantially conical magnets are mounted on the shaft. The magnets include conical magnetic surfaces facing each other and confronting air gaps. In some embodiments, substantially straight field pole members can be arranged coaxially and have flux interaction surfaces formed at both ends of those field poles. Those surfaces are located adjacent to the confronting conical magnetic surfaces to define functioning air gaps. Current in coils wound on the field poles provide selectable magnetic fields that interact with magnet flux in flux interaction regions to provide torque to the shaft.

Rotor-stator structure for electrodynamic machines

A gyroscope including a rotating member which is supported by a pair of magnetic bearings. Each bearing has two detectors for providing signals representative of the relative position of the member with respect to a common axis of the two bearings along first and second directions perpendicular to the axis and to each other. A feed-back loop controls biasing means in each bearing assembly and includes, for each direction, a summation circuit which sums the signals from the detectors corresponding to that direction in the two bearings and applies correction signals increasing with the summed signals to the biasing means corresponding to the directions in the two bearings. A subtracting circuit subtracts the signals from the detectors corresponding to the considered direction in the two bearings and applied correction signals to the biasing means, but through a polarity inverter in one of the bearings.

H Habermann

Papers

Devices including rotating members supported by magnetic bearings