Patent GB-720272-A (GB)
Title: Improvements relating to driving systems
Inventor: CLERK ROBERT CECIL
IPC: F16H33/02
Filed: 1951-05-23
Abstract: 720,272. Variable-speed gear. GYREACTA TRANSMISSIONS, Ltd. Aug. 12, 1952 [May 23, 1951; Aug. 20, 1951], Nos. 12086/51 and 19636/51. Class 80 (2) [Also in Groups XXVI, XXIX and XXXI] A system for driving air, land, surface- and sub-marine vehicles, lifts, colliery winding and haulage gear, cranes and earth-moving equipment, with or without a driving engine, comprises a flywheel 18 capable of supplying and absorbing energy, independent of the engine where provided, coupled to an output shaft 48 through variableratio gear, Fig. 3, or a coupling 10, Fig. 1, the slip in which is controlled by torque-responsive means included in the connection between the gear or coupling and the output shaft, and adapted to provide a follow-up control of the coupling or gear in conjunction with a power-demand control such as the throttle control of the driving engine. The variable-gear may, as in Fig. 3 and in Fig. 4 (not shown), be of the disc-and-roller friction type, and the slip coupling may, as shown in Fig. 1, be a hydrodynamic coupling variably. controlled as by a scoop-tube 9, or a variable displacement hydrostatic. coupling. In the vehicle drive,shown in Fig 1, an enginedriven shaft 1 and the flywheel 18 form alternative or co-operating power sources for driving the output shaft 48 through compounding planettrains 44, 46, 53 named respectively, the intergearing driving and braking trains, to one element of which the flywheel is connected with a high mechanical advantage, which, with its high inertia ensures that the said element is kept rotating at a steady speed to serve as a reaction member during the engine-only driving phase. Normal and " overdrive" ratios, manually controlled, are provided by the trains, together with vehicle braking by transfer of energy to the flywheel. The flywheel 18 rotates in vacuo on a vertical axis at a normal speed of 20,000 r.p.m., and is connected through an electromagnetic clutch 16 and reduction bevels 12 to a sleeve 11, the rear end of which is permanently connected to a sun 53 of the intergearing train, whilst its front end carriers the impeller 10 'of the fluidcoupling which it normally drives at 3,000 r.p.m. and through which coupling it applies variable torque to the engine shaft 1 during the flywheelassisting phase. The turbine 6 of the fluidcoupling is connected to the engine-shaft 1 through a torque-responsive planet train which provides the follow-up action in conjunction with a rod 27, Fig. 2A, connected to the engine throttle control for varying the coupling slip to maintain constant coupling torque in any given setting of the throttle rod 27. For this purpose the planet carrier 3 is connected to the turbine 6 and ring 2 to the engine shaft 1, whilst a disc 32 integral with the reaction sun 5 is supported for limited rotation in the fixed casing, drive-direction reaction being yieldingly opposed by a spring 33. The reaction sun-disc 32 carries a fulcrum 31 for a lever 24, linked at one end through a floating lever 26 to the throttle-rod 27 and at the other to the controlarm 23 of the pivoted scoop tube 9. Thus for any particular setting of the throttle-rod 27 during the ftywheel-assisting drive phase, increase in coupling torque causes increased yield of the spring 33 thus moving the scoop tube 9 inwardly from the periphery of a reservoir 8 to reduce the filling of the coupling, wlilst reduction in coupling torque has the opposite effect. This acts as a follow-up for the throttle-rod 27 which, on depression of the usual accelerator-pedal 134, Fig. 2B, moves rightwards, without effect until after full throttle, whereupon a fulcrum 28, Fig. 2A, on the floating lever 26 moves to the right end (position shown) of a slot 29 in a rod 30 (governor controlled as described below), whereafter further accelerator-depression for increased torque moves the scoop tube 9 outwards to increase the filling of the coupling and hence transmitted torque, which latter, reacting back on the spring 33 through the sun-disc 31, stabilizes, the scoop tube in positions to hold the torque constant at values corresponding to the setting of the throttle-rod 27. The power flow from the flywheel 18 through the fluid-coupling to the engine shaft 1 and thence to output, is thus regulated as to torque by the accelerator pedal in its overtravel range with a follow-up action. Output gearing. The braking and driving trains comprise respectively integral ring-gears 37, 38 on the engine shaft 1, the braking train having also a free planet-carrier 39 clutchable at 42 to the geared-flywhee shaft 11 during the vehicle braking-phase only (described below) and a sun 44, fast together with the planet-carrier 43 of the drving train, to the final output shaft 48. The free sun 46 of the driving train is fast with the ring-gear 51 of the intergearing train and can be held stationary by a brake 49 for a gearedreduced engine-only drive, or clutched at 47 to the output shaft 48 for a solid one-to-one drive which serves as an overdrive." A second brake 54 holds the planet-carrier 52 of the intergearing train, the sun 53 of which is permanently fast with the geared flywheel shaft 11. The various clutches and brakes, all electromagnetic, are controlled by two centrifugal governors 55, 59, acting (in conjunction with a manual-only "overdrive " switch) as described below, and driven respectively by the geared flywheel shaft 11 and output shaft 48. Operation. Charging the flywheel is effected by releasing all the clutches and brakes of the output gearing, starting the engine in the normal manner and opening the throttle, so that the engine-shaft 1 drives the flywheel 18 through the torqueresponsive planetary train 3, now under negative torque reaction so that the scoop tube 9 is in its radially outermost position for minimum slip in the fluid-coupling which drives from turbine to impeller to the flywheel. When the flywheel has reached normal operating speed, the driver closes the throttle, the planetary train then retracting the scoop-tube 9 inwardly so that the fluid-coupling drains at 50. Starting the engine. Assuming the engine dead; the vehicle stationary with service-brakes applied and the flywheel running at normal operating speed, the engine-shaft 1 may be brought to idle speed to crank the engine for starting by applying the brake 54 whereby the geared flywheel shaft 11 drives the sun 53 forwards, ring 51 and sun 46 reversely, and ring 38 and engine-shaft 1 forwards. Starting the vehicle in engine-only phase. Under the preceding conditions the fluid-coupling is empty and the engine may be used alone to start and accelerate the vehicle. by simply opening the throttle as far as full open, this having no effect on the scoop-tube 9 since the throttle-rod 27, Fig. 2A, then merely causes the fulcrum pin 28 to slide from the left to the right hand end of the slot 29. Acting through the high mechanical advantage' of the bevel gears 12 and intergearing train 53, the high inertia of the flywheel 18 is then sufficient to maintain the sun 46 of the driving train substantially at the steady speed corresponding to engine-idle so that it serves as a reaction sun for the driving train, which transmits to the output shaft at a reduction ratio of 1.4 to 1, The engine thus drives the vehicle and also feeds a small proportion of the energy to the flywheel to maintain its operating speed. Flywheel-assisting phase. If the acceleration provided by the 1.4 to 1 ratio in the preceding engine-only phase is inadequate, the driver depresses the accelerator 134, Fig. 2B, beyond fullthrottle so that the fulcrum-pin 28, Fig. 2A, swings the scoop tube 9 outwards to fill the fluid-coupling to a degree automatically regulated in accordance with torque-demand on the accelerator (as above described), whereby: the flywheel 18, driving through fluid coupling applies engine-assisting torque to the engine-shaft 1. Engine and flywheel then drive together until attainment of the desired vehicle speed causes the driver to relax the accelerator, whereupon the scoop tube 9 is retracted inwardly, the coupling drains and the engine continues driving alone as in the engine-only phase above described. " Overdrive." By a driver-operated switch, not shown, the other brakes and clutch are released and the clutch 47 energized alone for one-to-one drive, serving as an overdrive. Governor action. During normal reduced-ratio drive, when the flywheel speed exceeds a predetermined maximum, the flywheel-driven governor 55 changes contacts to de-energize the brake 54, thus freeing the flywheel from the output gearing, and energize the brake 49 to hold the sun gear 46 directly so that its reaction is now taken by the brake 49 instead of through the preceding intergearing train 53 to the flywheel. The output-driven governor 59 acts similarly above a predetermined vehicle speed. Thus the governors ensure energization of the brake 54 for flywheel-assisted drive (under accelerator control) whenever flywheel speed is below normal or when the vehicle is stationary or moving below a predetermined speed. The governors are also connected mechanically by pins-and-slots 65, 69 to the rod 30 having the slot 29, Fig. 2A, for the fulcrum pin 28 in the scoop-tube control, so that flywheeldrive assistance through the fluid coupling is introduced earlier in the accelerator travel as flywheel speed approaches the limit or as the vehicle comes to rest. Vehicle braking. Release of the accelerator 134, Fig. 2B, and depression of the brake-pedal 130, which may subsequently operate a normal hydraulic service brake-system at 149, causes contacts 145 to break the circuit feeding the reaction brakes 49, 54 and clutch 47, and contacts 147 to energize a clutch 42 connecting the planetcarrier 39 of the braking train directly to the geared flywheel shaft 11. Further pedal-depression acts through pin-and-slot 132 on the rod 27 to open the engine-throttle 138 inde