Inductor devices – With closed core interrupted by an air gap
Patent
1993-04-30
1995-08-29
Kozma, Thomas J.
Inductor devices
With closed core interrupted by an air gap
336198, 336221, 336234, H01F 1706, H01F 2724, H01F 2730
Patent
active
054464358
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an electric current sensor comprising a magnetic circuit with an air-gap and at least one electric coil disposed around a branch of this circuit, this branch having the shape of an elongate rectangular parallelepiped. More particularly, the invention relates to open-loop sensors of the above mentioned type in which a Hall generator is arranged in the air-gap of the magnetic circuit.
In the present day sensors in which the magnetic circuit has only one air-gap, two separate pieces or stackings of two groups of pieces of sheet metal are required to allow the mounting of a coil on a branch of the magnetic circuit. Such a structure and the corresponding assembling process are expensive and render the installations for automatic assembling relatively complex, the major problem being the accomplishing of an interpenetration of the metal sheets of the usual lamellar magnetic circuits.
The invention aims at providing a current sensor of a substantially lower cost price than that of the existing sensors of the same type and at allowing, in particular, a much more simple mounting of the coil or coils onto the magnetic circuit.
To this end, the current sensor according to the invention is characterized in that the magnetic circuit consists of a single piece or of a corresponding stacking of metal sheets of same shape and has an air-gap extending parallelly to the branch on which said coil is arranged, the height of this air-gap being greater than the thickness of the coil, measured transversally to the longitudinal direction of said branch on one side thereof, so as to allow the positioning of the coil by passing it through the air-gap.
The sensor according to the invention can in particular comprise a self-supporting winding or a winding made on an insulating support having, at least over the length supporting the coil, a U-shaped cross-section, the open section of the U being turned towards the inside of the magnetic circuit. In this case, the support comprises preferably, on at least one of its ends, a flange, a portion of which, located at the open side of the U of the part of the support carrying the coil, has an inner height lesser than that of the air-gap. This portion of the flange can, in particular, have a height which is smaller at the side directed towards the outside of the support than at the side directed towards the coil.
According to the present invention, the coil can be placed on an insulating separated support which itself is arranged around said branch of the circuit, this support having, at least on one side of its cross-section, a thickness smaller than the height of the air-gap, so as to allow positioning the same inside the coil by passing it through the air-gap.
At least a second coil can be arranged inside a first coil, said second coil having a thickness, measured transversally to the longitudinal direction of said branch of the circuit at one side thereof, smaller than the height of the air-gap, so as to allow the positioning of this second coil on said branch of the circuit by passing it through the air-gap after the introduction of the first coil.
Preferably, the air-gap is formed between a side part of a free end of the branch of the magnetic circuit supporting the coil or coils, and a front part of a free end of a branch of the circuit substantially perpendicular to the branch supporting the coil or coils. In this case, the branch which is perpendicular to that supporting the coil or coils, can comprise an end with a cross-section greater than the sections of the other parts of the circuit.
According to a particular embodiment, a piece or a stacking of sheets of a magnetically permeable material is placed in contact with parts of the circuit adjacent to the air-gap, so as to form a magnetic bridge across the air-gap.
The invention will be better understood in the light of the following description of different embodiments given by way of example and illustrated in the appended drawing in which:
FIG. 1 is a side view of a magnetic circuit with an air-ga
REFERENCES:
patent: 1367988 (1921-02-01), Replogle
patent: 1862613 (1932-06-01), Tomoda
patent: 1863936 (1932-06-01), Schwager
patent: 2867785 (1959-01-01), Crumbliss
patent: 3750073 (1973-07-01), Okano
patent: 4000483 (1976-12-01), Cook et al.
patent: 4654563 (1987-03-01), Boyd
patent: 4656452 (1987-04-01), Martin et al.
Browning Clifford W.
Kozma Thomas J.
Liaisons Electroniques-Mecaniques Lem S.A.
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