摘要:
A device is disclosed for damping the critical frequencies of a rotor suspended by a radial electromagnetic bearing which has means associated therewith for detecting the radial position of the rotor, comprising a servo-circuit for connection between the detecting means and windings of the electromagnetic bearing and including a circuit for controlling the current supply to the windings in response to signals from the detecting means to keep the rotor in a predetermined radial position. The servo-circuit is provided with means for the selective amplification of the phase advance gain of said circuit in a frequency equal to the speed of rotation of the rotor for damping said critical frequencies.
摘要:
A device is disclosed for compensating synchronous disturbances in the magnetic suspension system of a rotor which is supported by a radial electromagnetic bearing and which has means associated therewith for detecting the radial position of the rotor, comprising a servo-circuit for connection between the detecting means and windings of the electromagnetic bearing and including a circuit for the control of the current supply to the windings in response to signals from the detecting means to keep the rotor in a pre-determined radial position. The servo-circuit is provided with means for filtering the signals supplied by the detecting means between the latter and the control circuit, the filtering means having at least one band rejection filter centered on a frequency which is a direct function of the speed of rotation of the rotor.
摘要:
The invention relates to a device for compensating the gain of a circuit servo-controlling the position of a rotor with the aid of at least one electromagnetic bearing provided with electromagnet windings, from signals delivered by at least one detector detecting the position of the rotor, the servo-control circuit ensuring the control of the supply of the windings in response to the signals delivered by the detectors and comprising an amplification circuit with which is associated a negative current feedback loop, said device further comprising supplementary electrical means for injecting at the input of the amplification circuit a signal depending on the variations in the airgap of the servo-controlled electromagnetic bearing, in a predetermined variation frequency zone. The invention is more particularly applicable to electronic circuits for controlling active electromagnetic bearings.
摘要:
Active radial magnetic bearing with solid rotor comprising a stator composed of an armature and electromagnetic coils, a rotor fast with a rotary shaft and placed opposite the stator, detectors for detecting the radial position of the rotor with respect to the stator, and servo-control circuits for adjusting the current going through the electromagnetic coils according to the value of the signals delivered by said position detectors.The electromagnetic coils are so designed as to create a rotating sinusoidal magnetic field with radial flux, the electromagnetic coils comprising a plurality of windings distributed over the periphery of the stator and supplied in succession one after another from the servo-control circuits.This type of bearing helps going through critical frequencies.
摘要:
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.
摘要:
A turbomolecular vacuum pump has a housing, a vertically oriented hollow pump rotor situated in the housing, and a vertically upwardly oriented stub shaft affixed to the housing and extending into the hollow pump rotor. The pump rotor is supported on the stub shaft by a magnetic axial bearing and at least one magnetic radial bearing, all disposed in the space surrounded by the hollow pump rotor.
摘要:
This invention relates to magnetic bearings and particularly to active magnetic bearings having a very low "friction couple". In accordance with the invention the active magnetic bearing is of the type which has a stator formed by an electromagnetic circuit having at least one pair of north and south poles, and wherein said electromagnetic circuit of said stator includes at least one electromagnet of U-shaped section. The arms of said U form north pole and south poles respectively and the electromagnet is so arranged that the plane of symmetry which separates the north pole from the south pole lies perpendicularly to the axis of rotation of the magnetic bearing.
摘要:
The rotor of the radial bearing comprises a central shaft and a stack of ferromagnetic laminations constituted by a set of very thin individual laminations each of which extends over a limited angular sector around the periphery of the central shaft, said laminations being disposed in parallel planes so as to constitute a succession of flat split rings extending perpendicularly to the rotor axis. The individual laminations in any given plane are angularly offset relative to the individual laminations of the adjacent planes in such a manner as to provide a stack of laminations which is staggered. A bearing in accordance with the invention is suitable for supporting large diameter shafts which rotate at high speeds.
摘要:
The device for measuring the longitudinal tension in a strip leaving a rolling mill or stand comprises a measuring roll over which the strip bearingly runs, said roll consisting of at least one roll mounted on active radial magnetic bearings acting as load sensors and supplying a signal based upon the tensile stress in the strip bearing on said measuring roll, and means for measuring the current flowing in the windings of the magnetic bearings, as well as means for detecting the radial position of the rolls supported by said bearings and means for measuring the air gap of the magnetic bearings and keeping said air gap substantially constant.
摘要:
The present invention relates to an active electromagnetic bearing comprising first and second sets of electromagnet coils, the two sets of coils being so placed on one armature that on each double-pole part of armature are wound one coil of the first set and one coil of the second set and that the successive coils of the first set are all wound in the same direction whereas the coils of the second set which duplicate the coils of the first set are alternately wound in the same direction and in opposite directions with respect to the corresponding coils of the first set, a detector for sensing the position of the movable member and a control circuit being associated with each set of coils, and switch-over means being provided for connecting either set of coils with the corresponding control circuit in response to a control signal.