| 摘要 |
1,039,195. Valves; converting rotary into reciprocating motion. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. July 28, 1965 [Aug. 26, 1964], No. 34915/64. Headings F2Q and F2V. Linear movement of a valve closure member 3 may be effected by a hand wheel 6 or a reversible electric motor 9 on a bracket 8 fixed to the valve body. A motor pinion 11 meshes with a ring gear 12 clamped between two plates 13 which mount three planet gears 14, the upper halves 15 meshing with a first sun-gear 16 threadedly engaging a screwed part 18 of the valve stem 4; the lower parts 19 of the planets engage a second sun-gear 20 threaded 21 on to an element 23 fixed to the bracket 8 and having a thread of opposite hand to that of the first sun-gear 16. The latter has one less tooth than the second sun gear. With the motor inoperative the sun gear 16, 20 are prevented from rotating so that the valve may be actuated directly from the hand wheel through the threads 17, 18 on the first sun gear and stem, respectively. Energization of the motor 9 rotates the ring gear 12 and since the stem 4 tends to remain stationary when the member 3 is jammed on to its seat the sun gear 16 also remains stationary and the planets 14 will be rotated. Due to the ratio difference between the planets 14 and the sun gear 16, 20, the latter will be slowly rotated and apply a high torque to the element 23, the resulting high force relative axial motion of the sun gear 20 lifting the stem 4 until the sun gear abuts a shoulder 27 on the element 23 whereupon its rotation is also stopped. The planets 14 now roll round the sun gear 20 and torque of a lower value is applied to the first sun gear 16 to continue the upward motion of the stem with reduced force. A similar cycle of events occur during closing of the valve. A packing 5 round the stem or a removable tooth which constrains the stem 4 for linear movement during power operation must be overcome or removed upon manual actuation. |
