Patent GB-421536-A (GB)
Title: Improvements in electro-mechanical variable speed transmission systems
IPC: H02P9/00
Filed: 1933-04-18
Abstract: 421,536. Systems for transmitting mechanical power. NEULAND, A. H., 92, Stuyvesant Avenue, Irvington, New Jersey, and WHITSON, J., 345, East 57th Street, Now York, both in U.S.A. April 18, 1933, No. 11388. [Claas 38 (ivj] [See also Group XXXVII] In an electromechanical transmission system having a booster dynamo-electric machine in fixed speed relation with a driving shaft and a clutch dynamo connected electrically with the booster and coupled with the driving and driven shafts, electrical means responsive to speed changes in one of the shafts controls the change of at least one of the dynamos from motor to generator operation. The electrical means may be an auxiliary generator controlling the excitation of the booster or means for shifting the brushes of one of the dynamos. In both forms control may be effected jointly by the speed variations and by the variations of current in the transmission circuit between the dynamos. Figs. 1 and 11 show a driving shaft 4 directly coupled to the armature 5 of a comparatively large booster dynamo and through a differential gear 7 with the armature 12 of a comparatively small clutch dynamo and the load shaft 9. An auxiliary generator 37 is driven from the load shaft. All the machines are series wound with fixed fields. The fields of the main machines are so connected in the series transmission circuit including the armatures and fields of both that when rotating in the same direction as the engine they would act as motors. The control arrangements are shown in Fig. 1. A teaser winding 58 energized from a battery 59 gives a small excitation to the booster in a generating direction. The throttle of the engine 1 may be adjusted for idling speed independently of the other controls by reason of a slot 54. To start, the controller 27 is moved to position s whereupon a collar 55 closes a connection at 56 between the battery and the booster dynamo B, the regulator generator D being disconnected by the switch 40 operated by the arm 60, the clutch dynamo C being disconnected at 17 and the switch R being thrown to connect the field 13 in series with the armature 5. When the engine is running it may be accelerated in neutral position n, since the armatures and fields are shortcircuited separately and the teaser field is a weak one. In position f with the engine idling, the transmission circuit is complete and the stationary generator D is in parallel with the field 14 of the clutch dynamo. The teaser winding wipes out any remanent magnetism in the booster tending to instability and assists the clutch dynamo D to set up a small current on the transmission circuit. This current excites the auxiliary generator D which upon operation of the accelerator 49 is connected in parallel with the booster field 13 by the operation of the switch A. As the engine speeds up the clutch dynamo C increases the transmission current which reverses the field of the booster. This then operates as a motor ; its booster field is progressively reduced by the increasing voltage of the generator D and at the transition stage it is reversed thereby. Both machines B and C then operate momentarily as weak generators, but as the direction of rotation of the clutch dynamo changes this operates as a motor with increasing speed. To obtain higher vehicle speeds or to obtain increased power from the engine to deal with road conditions such as gradients, further depression of the accelerator shunts the field of the auxiliary generator D at 64 resulting in increased engine speed. The engine may be used as a brake by releasing the accelerator to cause the auxiliary generator D to be connected in parallel with the field 14 and the clutch generator. The resulting change in relative field strength of the machines B and C causes a reversal of the current in the transmission circuit and of the functions of these machines. The operation of the brake pedal 70 may increase this braking action by shunting the field of the booster dynamo at 67 and increasing the speed at which it drives the engine. By placing the controller 27 in the position r shown in Fig. 1, the field windings 13, 14 are reversed and the load shaft 9 is consequently driven backwards. The auxiliary generator is disconnected at 40 in this position. A resistance 66 may be provided for adjusting the operation of the auxiliary generator. Fig. 12 shows a booster dynamo B on the engine shaft 4 which is coupled by a differential gear with a clutch dynamo C and a load shaft 9. The brush gear 81 of the booster B is operable by electromagnetic means to change its functions from generator to motor. An auxiliary generator 37 preferably a three-brush machine is driven according to the speed of the engine shaft to vary accordingly the torque of an armature 79<a> lying in a field 81<a> and coupled to the brush gear 81. The strength of the field 81<a>, which is excited by the battery 59, and consequently the torque of the armature 79<a>, is dependent also on the current in the field windings 13, 14 of the booster and clutch dynamos. The resistance of the field winding 81<a> is such as to produce a " teaser " excitation of the windings 13, 14. When the accelerator 49 is fully depressed a resistance 66 weakens the field 81<a>. The armature 79<a> may control the brushes of the machine C, the generator 37 then being preferably connected by its main brushes and driven from the load shaft 9. Switches.-The switch R, Fig. 1, comprises fixed contacts 19-21 and switch members 23, 24. The latter co-operate each with a pair of fixed contacts and are held in engagement therewith by springs 25, 26. The members 23, 24 are pivoted on an operating member 31 which is reciprocated by the pedal 49 and held in defined positions by a detent 34. The switch is adapted to make connection as shown, to connect the contacts together in pairs 19, 21 and 20, 22 or to connect the members 23, 24 with the contacts 19 and 22 respectively.