| 摘要 |
856,160. Control of motors; controllers. TELEFLEX PRODUCTS Ltd. May 9, 1958 [July 27, 1957], No. 23432/57. Class 38 (3). [Also in Group XXX] The shaft 9 of an electric motor driving an actuator is geared to a threaded shaft 17 which is allowed to have limited axial movement in either direction. A non-rotatable nut 32 engages thread 18 and is fixed to a tubular ram 34 carrying an apertured fork for a connecting-pin, a sleeve being provided to protect the projecting portion of the ram from dust. A hollow cylinder 47 is mounted in thrust bearing 41, a portion of the shaft 17 which comes within the cylinder having a sleeve 50 in sliding engagement with pressure-plate 52 forming an abutment for gear-wheel 16. A compression spring 53 resists relative movement between the plate 52 and flange 51. If the shaft 17 is pulled downwardly, the plate 52 is not moved, but the downward movement is imparted to the flange 51 through nut 55 and thrust-sleeve 54. Alternatively, if the shaft is pushed upwardly, the flange 51 remains fixed but the gear-wheel 16 abuts the pressureplate 52 to move it over the outer surface of the sleeve 50. A sliding rod 56 has a fork member 59 embracing the gear-wheel 16 and is adapted to actuate limit switches 62, 63, by means of collar 79 between plates 72, 73. Thus, upward movement of the rod 56 causes collar 79 to engage plate 72 so pushing a plunger which opens the switch 62 and stops the motor. Owing to spring 78, the plate 73 is drawn away from the switch 63. The motor is similarly switched-off if the rod 56 is moved downwardly due to the maximum loading, as set by the springs 53, being exceeded. In addition to the load-sensitive means, the actuator may also be provided with travel-sensitive means operating on the same two limit switches. For this purpose, a fixed guide rod has two blocks adjustably secured to it by means of clamping screws which constitute pivots for a pair of twoarmed levers. A rod moving with the ram of the actuator, has abutments for engaging the levers at the limits of travel so that a striking rod 90 having sleeve 93 actuates switch 62 or 63. A removable crank handle 22 allows manual operation of the actuator. In another arrangement, the screw of the actuator moves axially and is held from rotation, whilst the nut rotates and is held from axial movement, Fig. 6 (not shown). |
