GB432981A - Improvements in automatic variable speed gear transmission mechanism such as for automobiles driven by internal combustion engines - Google Patents

Abstract

432,981. Controlling variable - speed gearing. FLURSCHEIM, C. H., Rushmoor, Fleet, Hampshire, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Crown House, Aldwych, London. Feb. 10, 1934, Nos. 4488, 11221, 28934, and 31146. [Class 80 (ii)] Variable-speed gearing between an internalcombustion engine and a variable load is controlled by a constantly-rotating cam 5, Fig. 1, which is moved axially by a governor and which strikes in successive axial positions against a selective profile member. The governor may be fluid or centrifugal, and driven at engine or load speed, and its action is modified by the throttle lever 24. The profile member may be a series of rigidly-connected arms 8, 9, Fig. 1, or may be a member 34, with steps A ... D, Fig. 4, or may be continuously graded to operate continuously-variable gearing. In the arrangement of Fig. 1, an oil pump 1 driven from the road wheels of a vehicle pumps oil through a pipe 2 to a cylinder 3 so that pressure acts on the end of a piston 4 against the bias of a spring 10. The piston 4 is coupled to the cam 5 and both are rotated by a shaft 6 geared, say, to the cardan shaft, not shown. The rotating cam 5 is moved axially by variations in pressure in the cylinder 3 and accordingly strikes the arms 8 in succession when moving left in changing up, and the arms 9 in succession when moving right in changing down, the arms 8, 9 being rigid upon a common shaft 7 which is rocked in steps to select or to effect speed changes, or to do both. The arms 8, 9 are relatively staggered to avoid governor hunting. The effectiveness of the governor is modified in accordance with engine torque by a leak valve 26 connected to the accelerator 24 which operates the throttle 25. There may be another leak valve 28 geared at 29 to the shaft 7 which modifies the effectiveness of the governor in accordance with the operative gear ratio. Fig. 1 shows means by which when the shaft 7 operates the selector cam shaft of a Wilson gear box, (not shown), the executive control of the box is also operated automatically and by power. An executive control pedal 22 operates the engine clutch, if fitted. The power for operating the executive control is supplied automatically by a relay 18 which causes the operation of a servomotor 21 which depresses the pedal 22 and so rocks the bus-bar of the gear-box to disengage the drive. A projection 23 on the pedal linkage opens a switch 20, which causes the pedal 22 to rise and apply the gear brake selected by the selector mechanism, and so bring into effect automatically a speed in accordance with the rocking of the control shaft 7. The shaft 7 operates two sets of electric contacts 12, 14 and 15, 16 in series with one another, the latter contacts leading to the relay 18 and being to secure accurate timing of the executive operation. A lock solenoid 19 holds the contacts 12, 14 closed after being closed by a saw-tooth cam 11 on the shaft 7. In Fig. 2 is shown a more practical form of the lay-out of Fig. 1 in which a profile member 34, shown also in Fig. 4, takes the place of the staggered arms. The cam 5 is connected by a key 67, Fig. 3, to the constantlyrotating shaft 6 and by springs 64, 65 so that it can move with snap action from one step to another of the member 34. The cam 5 is connected by a sleeve 33 to the piston 4 which is acted on by oil from the pump 1. The cam 5 has a rim projection 69 by which it tilts the profile member 34 to make the actual selections and changes of speed both in changing up and changing down. The shaft 7 has a linkage connection 36, 38, 45, 46, 39, 41 with the multiple selector cam shaft 43 of the Wilson gear box, which connection can be broken by manually disengaging a clutch 46, after which the shaft 43 can be rocked manually from a lever 44. An arrangement is described with reference to Figs. 5 and 6, (not shown), bywhich the automatic action is free and a manual lever picks up for neutral and reverse. The contacts 11, 15, Figs. 2, put in motion automatically the executive control to effect the change selected by the shaft 43. A servomotor 95, Fig. 9, corresponding to the motor 21, Fig. 1, through a crank linkage 96, 97 rocks a shaft 110a which rocks the bus-bar of the Wilson gear box, and operates the engine clutch, if fitted. The crank 96 rocks sharply to the left and back again. There is a switch at 102 corresponding to the switch 20 of Fig. 1, and an oil dashpot at 108. The leak valve 26 of Fig. 1 has a counterpart in Fig. 2. Oil in the cylinder 3 passes freely to a chamber inside a sleeve 53 which has an arcuate opening 26 registering with an aperture 55 in a fixed casing. As the throttle pedal 24 is depressed, through a linkage 48, 49, 50, 51, 52 it turns the sleeve 53 so that the effective size of the leak port 26 increases and the effectiveness of the governor decreases. A leak arrangement corresponding to the valve 28 of Fig. 1 is describedwith reference to Fig. 2<a>, (not shown). An arrangement according to the invention is shown in Fig. 16 in which a centrifugal governor 138 replaces the oil pump governor. The leftward thrust of the governor 138 is exerted upon a sleeve 141 which is splined on the rotary shaft 6 and which carries the cam 5 which engages the profile member 34. This governor thrust is resisted by a spring 148 which acts through a lever 147 pivoted at 149 against an arm 150 upon a rock shaft 151. The throttle lever, (not shown), tilts the shaft 151 and so changes the pivot 149 of the lever 147, and thus modifies the action of the governor. Fig 14 shows a circuit diagram for switching off the ignition during changes up so as to slow the engine and so facilitate the change. In circuit with the ignition coil 117 are two switches R, S in parallel. The switch R is opened along with the clutch, but the switch S is opened during changes up only. The closing of switch S will be sluggish and the circuit break will be terminated by the switch R. In Fig. 15, the switch R is opened every time a cable 126 connected to the clutch is pulled. The switch S is opened only when a ratchet wheel 133 is turned, and that is when the selector and change shaft 7 is turned one way, the way for changing up.