| 摘要 |
1281336 Brush-gear for dynamo-electric machines PLESSEY CO Ltd 13 Aug 1969 [16 Aug 1968] 39213/68 Heading H2A [Also in Division H1] In brush-lifting gear similar to that disclosed in Specification 1,259,777 incorporating a rotary actuating solenoid having radially inner and outer polepieces 35, 36 defining an air gap between them into which armature polepieces 43 coupled to the brushes are movable against a spring in response to energization of the solenoid, the polepieces 36 are shaped at 36a, Fig. 2, by a single angular machined cut so as to produce an air gap which converges away from the direction of entry of the polepieces 43 whereby the torque/rotation characteristic of the solenoid is improved. Alternatively, Fig. 4, the armature polepieces 43a are provided with auxiliary polepieces 43b which bridge the stator polepieces 35, 36 as the polepieces 43a enter the air gap. The auxiliary polepieces may be faced with thin strips of non-magnetic material to prevent sticking when the solenoid is deenergized. |
