GB649553A - Improvements in or relating to magnetic fluid clutch - Google Patents

Abstract

649,553. Friction clutches and couplings. DEPARTMENT OF COMMERCE, DIRECTOR OF THE OFFICE OF TECHNICAL SERVICES OF. Oct. 12, 1948, No. 26561. Convention date, Oct. 31, 1947. '[Class 80(ii)] [Also in Group XXXIV] A clutch or a coupling has two closely spaced movable elements of magnetic material between which magnetic particles, preferably in a fluid, are maintained and, when a magnetic field is applied, locking of the said two elements is effected. Fig. 1 shows a driving shaft 1 having a disc 3 secured to it, and a driven shaft 2 having fixed to it a cup 4 containing a fluid, e.g. oil in which iron dust is placed. When a coil 6 is energized from a source such as a battery 7 magnetic flux flows as indicated by the arrows and a magnetic locking of the elements 3, 4 is effected through the medium of the iron dust contained there between. The locking torque can be made variable by the use of a variable resistance 9. If either of the shafts 1, -2 is held stationary the device can be used as a brake on the application of the magnetic field. In a modification, the two elements 3, 4 of the device are replaced by two cylindrical magnetic bodies with the exciting coil mounted concentrically within the inner element. This coil can be eliminated by making the inner element of permanently magnetizable material strongly polarized at spaced areas around its periphery but in this form the torque cannot be varied unless a still further modification is made consisting in making the two elements of the device conical and means provided to alter the air gap between them by moving axially the inner element Fig. 4 (not shown). In a further modification, the device is made particularly useful as a brake by employing a number of discs fixed to each of the two elements of the device and by providing a circulating cooling system to dissipate the heat. In another modification. the exciting coil is held stationary and positioned concentrically outside the outer of the two elements. When used for A.C. the two elements are laminated and the A.C. exciting coil is mounted either on the inner or on the outer element.