GB562095A - Improvements in and relating to the driving of dynamos - Google Patents

Abstract

562,095. Driving dynamos. SELFCHANGING GEAR CO., Ltd., WILSON, A. G., and MILLER, A. A. Sept. 14, 1942, No. 12934. [Class 35] [Also in Groups XXIV and XXXVII] A dynamo is driven by a prime mover of varying speed, such as an internal-combustion engine, through a variable speed-gear, and means are provided for changing the gear so as to maintain the dynamo at a sufficient charging speed. For this purpose, hand or automatically controlled devices increase the speed ratio when the speed of the prime falls below the required value. In the arrangements described, the variable speed gear is of the epi-cyclic type, input shaft 10 carrying planet wheels 12 which mesh with a sun-wheel 16 on the output shaft 17 and with an internally toothed wheel 14, which can be held stationary by braking surfaces 15, 15a or left free ; a free wheel arrangement 31, 32, 33 between the planet wheel system and the wheel 14 or the sun-wheel, ensures that the system will turn as a unit during the direct drive periods, while allowing a step-up speed ratio. The brakesurface 15 is carried by a disc 18 with a hub 19 connected to a fixed ring 19a by balls 20 and helical grooves 20a; rotary movement of this disc causes the surfaces 15, 15a to approach each other and clamp on the periphery of the wheel 14. This movement is obtained by a shaft 25 connected by an arm and spring to the disc and turned by a handle 22, either manually or by a solenoid actuating mechanism. Alternatively the wheel 14 may be held stationary by an electro-magnetically operated friction brake, Fig. 5 (not shown). Automatic means for controlling the speed-changing gear may comprise a centrifugally operating device carried by the prime mover shaft and adapted to control the circuit of the electrically actuated brake mechanism of the wheel 14. As shown in Fig. 12, this consists of two weights 56 diametrically disposed on the shaft 10 and connected by springs 56a. The weights are pivoted on shafts 57 working in slots 59, and as the speed of the shaft 10 increases they swing about their pivots so as to bring their ends 63 into contact with two slip rings in circuit with the braking supply. Further increase in the speed of the shaft 10, causes the weights to swing about stops 66 engaging the edges of slots 65a, so that the pivot pins 57 are forced between pairs of spring-pressed balls 64, whereby the contact with the slip rings is interrupted. The circuit is also broken when the shaft 10 is at rest. A modified form of free-wheel mechanism is shown in Figs. 6, 9, in which the inner member 42 is formed with flats 48 which engage rollers 35 mounted in a cage 47. Pins 49 on the cage engage enlarged openings 50 on the member 42 to limit the movement of the balls in one direction.