GB1087733A - Improvements in or relating to electro-magnetic devices - Google Patents

Abstract

1,087,733. Electromagnets. PLESSEYU.K. Ltd. June 10, 1964 [June 18, 1963], No. 24128/63. Heading H1P. [Also in Division F2] An electromagnetic device for producing stepped rotary motion comprises a pair of cooperating polepieces which are arranged for relative movement when an associated coil is energized and an output member which is normally locked by a locking device but is disengaged so that the output member can follow the relative movement of the polepieces when the coil is energized. The magnetic members 10, 11 in Fig. 1 move axially when coil 12 is energized and rotary motion of shaft 14 is attained in known manner by means of opposed cams 17 and balls 18. In operation, member 11 is initially attracted to frame 13 thereby removing stud 20 from a hole in locking disc 21, member 10 then rotates and drives shaft 22, which is attached to disc 21, through ratchet 16. When the coil is de-energized member 11 is returned by spring 19 so that stud 20 engages a hole in locking disc 21 and member 10 is returned to the rest position by a return spring, not shown. In Fig. 2, armature 110 has poles and rotates when coil 115 is energized. The locking member 117 initially moves axially and withdraws pin 124 from a slot in disc 123 so that rotation of the armature drives output shaft 121 through ratchet wheels 125, 126 and index arm 128 until at the end of the stroke a peg on index arm 128 falls into a slot in disc 123. On de-energization of coil 115 locking member 117 moves under the action of spring 118 so that pin 124 enters the same slot in disc 123 forcing out the peg on the index arm thus releasing armature 110 which returns to its rest position by a spring, not shown. The co-operating poles on frame 112 and armature 111 are generally arcuate and shaped so that the opposed area of any one pair of pole surfaces remains constant.