Magnetic coupling with hysteresis, particularly for winding/unwinding devices
A magnetic coupler with hysteresis ( 1 ) has an inductor subassembly ( 2 ) and an armature subassembly ( 6 ) that are capable of rotating one with respect to the other. The inductor subassembly has a plurality of magnetic poles and the armature subassembly ( 6 ) has one or more armature permanent magnets with hysteresis ( 11, 12 ). The invention is notable in that the or each armature magnet is produced in the form of a ring of one piece in magnetic material with vertical hysteresis and has through-slots for attenuating radial currents each running in the direction of the circumferential spread of the ring. Application to limiting heating and reducing axial bulk.
1. A magnetic coupler with hysteresis ( 1 ) comprising an inductor sub-assembly ( 2 ) and an armature sub-assembly ( 6 ) suitable for rotating relative to one another, the inductor sub-assembly having a plurality of magnetic poles and the armature sub-assembly ( 6 ) having one or more permanent armature magnets with hysteresis ( 11 , 12 ), wherein each armature magnet is made in the form of a crown in a single piece of a magnetic material with vertical hysteresis cycle and comprises through-slots (F 1 -F 4 ) for attenuating radial currents, each extending in the direction of the circumferential spread of the crown,
wherein there is a set of offset slots (F 1 -F 4 ) one relative to the other in the radial dimension of the crown, between its outer edge and its inner edge.
2. The coupler according to claim 1 , wherein each slot has an angular spread substantially greater than that of a pole of the inductor sub-assembly.
3. The coupler according to claim 1 , wherein the slots extend according to circles concentric with the centre of the crown.
4. The coupler according to claim 3 , wherein the circles are essentially equidistant from one another.
5. The coupler according to claim 1 , wherein the or each armature magnet ( 11 , 12 ) is made of magnetic iron-chromium-cobalt alloy.
6. The coupler according to claim 1 , wherein the or each armature magnet has a ratio between crown width and thickness greater than approximately 3.
7. The coupler according to claim 1 , wherein the or each armature magnet is borne by a flange ( 9 , 10 ) made of non-magnetic metallic material with high electric resistivity, in particular greater than 5 μohm·cm, and with high thermal conductivity.
8. The coupler according to claim 7 , wherein the flange is made of stainless steel.
9. The coupler according to claim 7 , wherein there is close surface contact between the or each armature magnet and the associated flange.
10. The coupler according to claim 7 , wherein a thermally conductive paste is provided between the or each armature magnet and the associated flange.
11. The coupler according to claim 7 , wherein opposite the armature magnet the or each flange has heat dissipation fins ( 90 , 100 ).
12. The coupler according to claim 1 , wherein a number of slots per concentric level (F 1 -F 4 ) and a number of magnetic poles of the inductor sub-assembly are not multiples of one another.