GB1199479A - Improvements in or relating to Door Operating Mechanisms. - Google Patents

Abstract

1,199,479. Linear motors. ELECTRICITY COUNCIL. 22 Oct., 1968 [23 Oct., 1967], No. 48114/67. Heading H2A. [Also in Division E2] A linear motor for operating a door comprises an alongated armature 12 on which is wound a coil 13 energized with D.C. through brushes mounted on a surrounding field assembly 20. As shown, the field assembly has four poles 21 . . . 24 with three energizing coils 25 and the armature has three brushes 15 . . . 17 contacting bored portions of the winding and connected so as to energize the intermediate portions of coil 13 in opposite senses, which portions then co-operate with the appropriately energized poles to produce motion in one direction or the other. Reversal of motion is obtained by reversing either the field current or armature current. The armature may be circular and supported on rollers or generally rectangular and slidable on P.T.F.E. a block (Fig. 5, not shown). The circular armature may rotate as it slides to ensure even brush wear on the coil. Either the armature or the field assembly may be coupled to the door and in the latter case connection to the motor may be effected by sliding contacts engaging conductor rails, by trailing leads or by flexible leads extending through a pivoted arm. The motor may be stopped by limit switches at each end of the stroke and further limit switches may be provided for increasing the field current and reducing the armature current near each end of the stroke so as to slow down the motor. A reversing switch may be operated by a rubberfaced strip on the leading edge of the door if the door meets an obstruction.