GB695245A - Improvements in electrical variable speed gears - Google Patents

Abstract

695,245. Electric control systems. DELETAILLE, E. June 7, 1951 [July 6, 1950], No. 13580/51. Class 40 (i) [Also in Group XXIV] The preselector element of a continuouslyvariable speed gear positions correspondingly the control element of a follow-up switch, the follower element of which is driven with, and controls the stopping position of the means for adjusting the gear 'ratio. As shown, Fig. 1, an electric motor 3 drives the output shaft 11 through belts 6, 10 and a change speed device 8 of known type in which the output to input speed ratio is varied by translation of a member 12 in-direction A or B according to the sense of the change. The preselector element comprises an arm 40 which is rotated to the desired gear-ratio position as indicated by a pointer 41, and through a cable drive 37, pinion 35.and a rack 34 moves a spindle 33 axially to a corresponding position. A ring 47 rigid with the spindle accordingly moves one or other ot two spring biased collars 43, 44 along the spindle out of engagement with its associated switch contact pair 26-28, 27-29 carried by the member 12. The switch pair so released, close, when, provided the preselector lever 40 has been also rocked in the direction of arrow C to close the gear changing switch 22, a relay 18 is energized, locks, and closes the stator circuit of the three-phase motor 16 over the closed switch pair 26-28 or 27-29. The motor 16 then drives through worm gearing 15, a nut 14, which engages the threaded portion 13' of shaft 13 and thereby moves this shaft axially to follow up the axial movement of the spindle 33, and at the same time effect the gear change. The motor 16 is stopped and relay 18 is released when the member 12 has moved the actuated switch pair into engagement with the associated collar 43, 44 to open the switches. Four switches 26-29 are used, two for each direction of rotation of motor 16 since reversal is effected by reversing the connections to two of the stator phases. In a modification one pair of switches 57-58 only is used Fig. 6 to control two relays 51, 52 to effect change over of the phases of motor 16. The spindle 33, may in this case carry rigid therewith a sleeve 60 ending in conical portions 61, 62 for actuating the respective switches 57, 58 the normal position being as shown with the switch actuating elements 63, 64 spaced apart a distance equal to the length of the cylindrical portion of the sleeve 63 and engaged thereby to hold the switches open. Further embodiments, are described Figs. 7, 8 (not shown) using a D.C. motor for effecting the gear change with the follow-up switch arrangement of Fig. 1 or Fig. 6.