Metal working – Method of mechanical manufacture – Electrical device making
Patent
1993-09-16
1995-10-17
Hall, Carl E.
Metal working
Method of mechanical manufacture
Electrical device making
29609, 336180, 336184, 336185, 336221, H01F 4102
Patent
active
054578736
DESCRIPTION:
BRIEF SUMMARY
The present invention is concerned with a method for mounting an electric coil on a magnetic circuit with an air gap of a current sensor, this circuit being formed by a stack of metal sheets of a magnetically permeable material.
Present day current sensors, the magnetic circuit of which has a single air gap, require nevertheless a magnetic circuit formed of two separate pieces or of stacks of two groups of pieces of metal sheet to allow the mounting of a coil on one branch of the magnetic circuit. Such a structure and the resulting assembling process are expensive and render the automatic assembling installations relatively complicated.
The invention is aimed at providing a method for mounting at least one coil on a magnetic circuit which is substantially simpler and cheaper, in particular for automated assembling in mass production.
To this end, the method of the invention is characterized in that metal sheets are stacked, which all have the general shape of the magnetic circuit and which are slidable in their plane each one relatively to the others, in that this stack is held firmly and at least one part of the circuit close to the air gap is deformed relatively to the plane of the metal sheets, in such a manner as to allow the placement of the coil on a portion close to the air gap, and in that the deformed parts of the circuit are brought back into the plane of the metal sheets after the placement of the coil.
In a preferred embodiment of this method, at least the portion of the circuit on which the coil will be placed and/or at least one portion of the circuit at the opposite of the air gap are clamped during the deformation of at least one portion of the circuit. Preferably, the deformation of the metal sheets is spread over the major part of the circuit which is not clamped.
According to one embodiment of this method, the metal sheets are deformed and then brought back into their plane by means of at least one pusher. This pusher can include a part which is at least temporarily clamped to the coil.
The invention is concerned in particular with the application of the present method to a magnetic circuit having an air gap within a rectilinear part of the circuit and to a coil of a length comprised between those of said branches and, in this case, the coil is placed in its final position in which the air gap is located within the coil, once the circuit is brought back into the plane of the metal sheets.
The invention is also concerned with a current sensor made by using the method according to claim 1.
Such a sensor can advantageously have a magnetic circuit which includes a rectilinear base branch and two rectilinear branches formed inclined at an acute angle with respect to the base branch, the first ends of the inclined branches being connected to the base branch and the second ends of the inclined branches being arranged to form the air gap of the magnetic circuit.
In this case, one can advantageously place on the circuit two coils, namely one coil on each one of the inclined branches, and this without increasing the deformation of the magnetic circuit for placing the second coil. Further, in this manner, a structure is obtained which exhibits an optimal ratio of the circuit length to the volume of the windings of the coil with which the circuit is coupled. The acute angle is preferably equal substantially to 45.degree.. The air gap can be made substantially perpendicular to the base branch or parallel to one of the inclined branches.
Other features and advantages of the invention will become apparent from the following description of preferred embodiments, given by way of example and illustrated by the appended drawing, in which:
FIG. 1 shows a magnetic circuit with a coil mounted according to the invention;
FIG. 2 illustrates the partial bending of the metal sheets and the positioning of the coil in the case of the circuit of FIG. 1;
FIG. 3 shows another version of the shape of the metal sheets of a magnetic circuit;
FIGS. 4 and 5 show a magnetic circuit using the metal sheets of FIG. 3 with a co
REFERENCES:
patent: 1401493 (1921-12-01), Replogle
patent: 3034203 (1962-05-01), Vienneau
patent: 4267719 (1981-05-01), Walker
patent: 4790064 (1988-12-01), Ballard
Browning Clifford W.
Hall Carl E.
Liaisons Electroniques Mecaniques Lem S.A.
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