Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1994-05-19
1997-04-29
Dougherty, Thomas M.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 90, 310 92, 310 93, 188 67, 188 30, 188342, 188 823, H02K 709
Patent
active
056252404
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns the use of a magnetic bearing to position a body rotating relative to a stator body and is more particularly concerned with the mechanical retention that is required in practice before the magnetic bearing is activated and/or to protect the magnetic bearing from vibration or excessive amplitude likely to damage it. The invention has preferable, but not exclusive, applications in a space environment (intense vacuum, hostile environment, especially thermally, low or even negligible gravity).
It is not possible to design a magnetic bearing which can be passive (using only permanent magnets) both axially and in at least two transverse directions. This is well known. It is always necessary to provide, on one axis at least, active control using an electromagnetic actuator, in practice embodying a coil which is energized to generate in air gaps correcting fluxes which induce a correcting force conditioned by measurement signals supplied by position or speed sensors and set point values for position along the active control axis.
In the absence of any applied current, the rotating body departs from its unstable equilibrium position parallel to the axis on which control is to be applied. For this reason it is beneficial, in particular to avoid any excessive excursion, to provide mechanical abutments against which the rotating body bears in the absence of current in the control loop. To this end it is beneficial to include in the control logic some logic specifically dedicated to the phase in which the rotating body is lifted off the abutments when the control loop is activated.
There are two major categories of magnetic bearings, namely active axial control and passive radial control bearings and passive axial control and active radial control bearings. In the former case, where the rotating body is in unstable equilibrium parallel to the rotation axis, it is known to provide axial thrust bearings which can be mobile so that it is possible to key the rotating body axially. In the latter case, in which the rotating body is in unstable equilibrium transverse to the rotation axis, either the rotating body is allowed to depart from its usual set point radial position to bear radially against the abutments or, as previously, the rotating body is retained by axial keying.
The types of mechanical retention referred to above cannot always be used, either for reason of limited axial overall dimensions or because of their inability to retain the rotating body firmly in the presence of high levels of vibration, of the type generated in a satellite during launch, for example, or during firing or orbit correction thrusters.
SUMMARY OF THE INVENTION
An object of the invention is to overcome the above disadvantages and thus to ensure firm retention of the rotating body in the case of active radial control (or even in the case of axial control through choice of appropriate coefficients of friction), preferably in the equilibrium set point position of the rotating body, in a simple and reliable way, preferably in such a way as to avoid the use of complex lift logic, and enabling reversible operation of the retaining members to enable testing thereof on the group prior to launch.
To this end the invention proposes a device for positioning a body rotating about an axis relative to a stator body including a magnetic bearing and a locking/unlocking device. The locking/unlocking device includes a plurality of clamps having clamping shoes adapted to bear radially on a shaft of the rotating body. The clamps are articulated to the stator body about axial pins at a distance from the rotation axis and equi-angularly distributed around the rotation axis and pivot around the axial pins due to the action of a mobile maneuvering member between an unlocked configuration in which the clamping shoes are at a maximum distance from the axis and a locked configuration in which the shoes are at a minimal distance from the axis so that the shaft is clamped radially.
According to preferred features o
REFERENCES:
patent: 2604273 (1946-07-01), Hayes
patent: 4184572 (1980-01-01), Poubeau
patent: 4231452 (1980-11-01), Kraft
patent: 4398773 (1983-08-01), Boden et al.
patent: 4470644 (1984-09-01), Weisser
patent: 4918345 (1990-04-01), Vallant de Guelis et al.
patent: 5054594 (1991-10-01), Kampf et al.
patent: 5275261 (1994-01-01), Vranish
Aerospatiale - Societe Nationale Industrielle
Dougherty Thomas M.
Enad Elvin G.
Meehan Thomas A.
VanOphem John
LandOfFree
Magnetic bearing and mechanical thrust bearing device for positi does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic bearing and mechanical thrust bearing device for positi, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic bearing and mechanical thrust bearing device for positi will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-708523