Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – With magneto-mechanical motive device
Patent
1993-03-30
1995-02-07
Picard, Leo P.
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
With magneto-mechanical motive device
335234, 29607, H01F 700, H01F 706
Patent
active
053878922
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
This invention relates to a permanent magnet release solenoid for automatic circuit breakers, which has a magnetic circuit whereon a permanent magnet and an electric winding would induce respective magnetic fields.
In particular, the invention relates to a solenoid of the type wherein the magnetic circuit comprises a stationary part including a squared annular shroud which is divided theta-like by a partition enclosing, on the one side, the permanent magnet, and on the other side, the electric winding, between itself and the shroud, and a moving part including a small plunger being slidable axially within the winding and guided through an opening in the shroud, the plunger being movable between a retracted position and an extended position dependent on the magnetic field induced by the winding.
In the retracted position, the plunger is magnetically coupled to both the shroud (through the opening being dimensioned to minimize the gap around the plunger while still allowing the plunger to slide) and the partition; the last-mentioned coupling is usually accomplished by means of a cylindrical lug formed integrally with the partition and having the same cross-sectional dimension as the plunger, with the plunger being arranged to bear on said lug. The bearing area between the plunger and the lug forms a break in continuity and, hence, a disturbance in the magnetic field; accordingly, care is taken to locate this discontinuity in the middle of the winding, where the substantially straight, magnetic flux lines will lie perpendicularly to the discontinuity and, therefore, not be liable to distortion.
In this way, however, the partition becomes quite expensive to make, because of the need to start with a blank of comparatively large size and machine it down until the lug is left proud.
Furthermore, during the assembly stage, it is impossible to fit all the parts, one after another, separately into the shroud from one of the open sides; at least the partition and winding must be pre-assembled together, and then the assembled parts fitted into the shroud, while in extreme cases, the various parts may have to be fitted in with the shroud in the open condition, and the shroud be closed again at the end of the operation. This affects assembly costs considerably.
It is the object of this invention to provide a solenoid of the type specified above, which can overcome the problems just outlined.
This object is achieved, according to the invention, by a solenoid as indicated being characterized in that the partition comprises a flat plate whereon the plunger is brought to bear directly in its retracted position.
It has been found, in fact, that by removing the lug from the partition altogether, and having the plunger bear directly on the partition, the distortions introduced in the magnetic field are in no way such as to hinder proper operation of the solenoid.
On the other hand, the partition can be here just a simple plate of minimal cost; in addition, with no lug to be fitted into the winding, the whole unit can be assembled with the shroud closed, and all the components fitted separately one after another, to cut down assembly time and cost.
In a second aspect, the invention relates to a method of making a solenoid as indicated, characterized in that it comprises the steps of,
cutting off a tube length from a square cross-section stock of a ferromagnetic material;
making an opening through said tube length;
inserting, laterally into the tube length, an electric winding to a position adjacent to the opening;
inserting, laterally into the tube length, a plate of a ferromagnetic material to contact the winding;
inserting, laterally into the tube length, a permanent magnet to contact the opposite side of the plate from the winding; and
inserting a plunger of a ferromagnetic material through the opening and inside the winding.
This method, made possible by this invention, is of special value in that it is simple and inexpensive.
Further features and advantages of the invention will be more clearly apparent from t
REFERENCES:
patent: 3886507 (1975-05-01), Johnson et al.
patent: 4443775 (1984-04-01), Fujitani et al.
patent: 4595896 (1986-06-01), DiMarco et al.
patent: 4660012 (1987-04-01), Bonniau et al.
patent: 4684309 (1987-08-01), Horn
patent: 4876521 (1989-10-01), Boyd
Contardi Augusto
Rossetti Gian P.
Bticino S.P.A.
Picard Leo P.
Ryan Stephen T.
LandOfFree
Permanent magnet release solenoid for automatic circuit breakers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Permanent magnet release solenoid for automatic circuit breakers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Permanent magnet release solenoid for automatic circuit breakers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1113186