GB751790A - Electric motor with brake - Google Patents

Abstract

751,790. Electric-motor brakes. FODGAARD, M. March 15, 1954 [March 17, 1953], No. 7504/54. Class 103 (1). [Also in Group XXXV] In an electric motor, used for hoisting winches and cranes, machine tools, textile machines, conveyer plants, &c., which incorporates a brake the two co-operating parts of which are mounted on the rotor and in the stationary part of the motor and which brake is engaged when the motor does not develop torque and vice versa, releasing of the stationary brake part from the rotor brake part is effected in response to torque produced by the motor-operating current by permitting a limited angular movement of the stator 14 about the rotor axis. As shown, the stator 14 is disposed in a tube 15 supported by balls 16 or rollers in the motor housing 1 and when moved angularly is also moved axially whereby the end 17 of the tube controls the axial position of a brake lining holder 9 having a conical lining 11 engageable with the complementary lining 12 of a wheel 13 secured to the rotor shaft 5. The holder 9 is urged by compression springs 10 to a position of brake engagement, see top half of Fig. 1, and is released, see bottom half of Fig. 1, by the torque actuated axial stator movement which is effected by sets of contact surfaces 18 ... 20 arranged in the end of tube 15 and engaged by rollers 23 accommodated on projections 22 on the end shield 4. The two surfaces 18, 19 are to operate the brake with either direction of motor rotation, and tension springs 25 acting between projections 21, 24 on the tube 15 and end shield respectively return the tube to its angular rest position when no motor torque is developed, said projections 21, 24 also limiting the stator angular movement. In modifications leaf springs may replace the helical springs 25, or such springs may be dispensed with entirely; electromagnetically acting members may replace the springs 10; the rotor ball bearing 26 which takes the brake axial pressure may be axially adjustable to vary the distance between the brake linings 11, 12; the stator may be axially stationary by disposing the components 18 ... 25 at the left-hand end of the rotor and providing plane annular surfaces at the righthand end thereof; or components 18 ... 25 may be replaced by studs projecting radially from the tube 15 and engaging helical recesses in the motor housing or in the stationary brake part. The motor may be an A.C. or a D.C. motor. The wheel 13 may have spokes (not shown) forming an impeller of cooling air through openings 27 ... 30, such air passing through the clearance between the tube 15 and housing 1 and being directed to the brake linings 11, 12 by plates 31.