Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – With magneto-mechanical motive device
Patent
1992-06-22
1995-02-28
Picard, Leo P.
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
With magneto-mechanical motive device
335219, 335232, 335234, 335243, 335255, 335259, 335261, 335265, 335272, 335279, 335281, 310 20, 310 92, 25112901, 25112902, 361160, H01F 700
Patent
active
053941314
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a magnetic drive with at least one armature magnetized in the direction of excursion and consisting of a permanent magnet with two magnetically soft pole pieces, said armature being movable along a common axis between two electromagnetic external pole-pieces which are magnetizable always with the same polarity and are axially located inside a passage of a third electromagnet that is present between the external pole-pieces and that can be controlled with a magnetic polarity that is opposite that of the said external pole-pieces, the central annular pole-piece comprising passages and/or the external pole-pieces projecting from a coil wound on a magnetically soft core.
Such a magnetic drive is known from the British patent 1,068,610.
The state of the art contains moreover numerous magnetic drives with armatures made of permanent magnetic materials and displaceable between two pole-pieces of the same sign. Essentially the basic designs of simple magnetic circuits of this sort have been exhausted. However there are almost no reliable practical computation methods or design criteria, and this kind of magnetic drive so far has found little acceptance, in considerable part because of mechanical inadequacies, the use of earlier magnetic materials of lower performance.
The German Offenlegungsschrift 34 26 688 discloses a magnetic drive of the above species with two cylindrical, coaxial and sequentially mounted coils and a permanent-magnet armature which is displaceable centrally in the axial direction inside the coil bore. This arrangement of two coils hardly allows mounting operational devices at the magnetic armature for lack of adequate space inside the coil bore. Moreover there is danger of the magnetic armature heating on account of the unfavorable position and thereby losing its permanent field strength.
SUMMARY OF THE INVENTION
The object of the invention is to create a novel and especially simple magnetic drive with appropriate design criteria that shall take into account the high performance together with the unfavorable mechanical properties of modern permanent magnetic materials and that is suitable for miniaturization with minimal armature weights and manifold applications.
The problem is solved by the features of the characterizing part of claim 1.
Advantageous embodiments of the invention are stated in the sub-claims.
The bistable character of the described magnetic drive allows energizing them with short current pulses. These pulses may be generated for instance by charging and discharging a capacitor or an inductive-capacitive coil such as known from the German Offenlegungsschrift 36 04 579. Suitable circuits of this kind with energy storage furthermore permit imparting monostable behavior to the magnetic drive.
Illustrative embodiments of the invention are schematically shown in the drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a-1d show the magnetic drive in simplified form with the armature in various positions, and the forces acting on the armature,
FIGS. 2a-2e are cross-sections of the annular pole-piece (which is a part of the core of the coil) plus the permanent magnets, the cross-sectional plane being perpendicular to the motion of the armature,
FIGS. 3a-3d are various sections in the plane of the armature-excursion axis, that is they are cross-sections of the pole-piece and armature zone,
FIGS. 4-10 are examples of applications of the invention that elucidate how operational devices can be driven in the armature-polepiece space with minimal expenditure and possibly can be integrated without accessories,
FIG. 11 is an illustrative circuit for operating the magnetic drive as a reciprocating magnet fed from a DC source,
FIG. 12 is an illustrative embodiment of the magnetic drive with a coil divided in two and asymmetric pole-piece regions,
FIG. 13 shows the characteristic curves of this drive,
FIG. 14 is a variation of the magnetic drive of FIG. 12 with an external yoke mounted only on one side of the coil,
FIG. 15 is an illustrativ
REFERENCES:
patent: 3203447 (1965-08-01), Bremner et al.
patent: 3379214 (1968-04-01), Weinberg
patent: 4422060 (1983-12-01), Matsumoto et al.
patent: 4494098 (1985-01-01), Haneda et al.
patent: 4779582 (1987-08-01), Lequesne
Barrera R.
Picard Leo P.
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