| 摘要 |
814,217. Controlling variable speed gearing. BRITISH THOMSON-HOUSTON CO. Ltd. Oct. 18, 1957 [Nov. 15, 1956], No. 34982/56. Class 80 (2). An induction motor is connected to its load through a variable speed gear automatically varied to maintain the motor speed constant by governor means, the governor being biased to maintain the percentage slip in the motor at a desired value as the supply frequency varies. An induction motor 1 drives a load, such as the starting gear of a gas turbine, through a variable speed gear 2, the ratio of which is controlled by a governor 4 to maintain the motor speed constant. The governor is biased by a spring S loaded by a flange 5 axially free but rotationally fixed on the governor shaft 6, the flange 5 being moved axially by differential working of a screw 7 and nut 8 mechanism in which the nut 8 is driven through gears 11 from a synchronous motor 10 connected to the supply to the motor 1. The gearing 11 is determined to provide a required percentage slip in the motor 1, the motor 10 being sensitive to any frequency change in the supply and acting through the governor to cause the slip in motor 1 to remain at a desired percentage. When the motor 1 is used as an alternator after the prime-mover 20 (Fig. 3), has started, the variable speed gear 2 is connected through a high ratio gear train 18, 19 bridged by a one-way clutch b to start the.: prime-mover, and directly through the clutch b when the direction of the torque is reversed, the gears 18, 19 being bridged by a second oneway clutch a. Under these latter conditions the screw 7 (Fig. 4) moves to the right and causes pivoted jaws 12, 13 to engage a fixed member 15 to release the flange member 5 from axial connection with the screw 7. Specification 806,947, [Group XXXV], is referred to. |
