GB647512A - An improved electromechanical control device - Google Patents

Abstract

647,512. Electromagnets. GRETENER, E. Dec. 15, 1947, No. 32975. Convention date, Oct. 5, 1946. [Class 35] [Also in Group XXXVII] An electromechanical control device comprises an electromagnet with an armature which, in its initial movement towards the attracted position, is not mechanically loaded and which is returned to its initial position at regular intervals by separately operable mechanical means. Figs. 2, 3 show an electromagnet 1 and an armature 2 which is supported by a spring 3, the free end of which is arranged to push a cross-piece 8 after this free end has moved through a distance 10 at the commencement of the armature movement. Fixed to the cross-piece 8 is a contact spring 9a of a contact unit 9, the contacts of which can only be closed when a gap in a flange 12 of a continuously rotating control disc 11 coincides with the cross-piece 8. These contacts remain closed by the engagement of the inner periphery of the flange 12 with the cross-piece 8 except when the latter coincides with the flange gap and the magnet retaining force is below a predetermined value. The armature is returned to its initial position by a lobe 5 of a disc 6 also continuously rotating by the same shaft 7 driving the control disc 11. In a modification, Figs. 5, 6 (not shown), the device without a contact unit is arranged for mechanical control purposes wherein a continuously rotating disc cam transmits torque to a sprocket-wheel through a friction disc. When the electromagnet is energized a pawl at the free end of the armature spring engages a sprocket and blocks the rotation of the sprocket-wheel, the armature being returned to the initial position every revolution of the cam disc by a lobe on the latter, thus intermittently eliminating the blocking of the sprocket-wheel. In this application, the commencement of the armature movement takes place without it being loaded by the control mechanism.