GB421052A - Improved control system for the driving mechanism of motor vehicles - Google Patents

Abstract

421,052. Controlling variable-speed gearing. GENERAL MOTORS RESEARCH CORPORATION, Detroit, Michigan, U.S.A. March 8, 1933, No. 3845. Convention date, March 12, 1932. [Class 80 (ii)] Continuously-variable transmission gearing is controlled by the resultant action of speedresponsive means such as a governor and a manual control element, and means are provided for modifying the resultant action to lower the speed transmitted. Thus, in Fig, 10, a control lever 31 for the gearing movable between high and low limiting stops H, L is operated jointly by an engine-driven governor 125 and the accelerator 41 of a vehicle. The lever 31 can be operated independently by the governor and by the accelerator, and the modifying means comprise (1) a dashpot 71, (2) an adjustable stop 90, Fig. 2, and (3) an adjustable fulcrum 96 in the linkage. A pedal 25, Fig. 1, may operate the usual clutch between the engine 21 and the variable gearing 23, a hand-lever 40 operating reversing-gearing 39. A rock shaft 61 is connected by an arm 63 to a balance lever 53 connected to the throttle 43 and operated by the accelerator 41. Another arm 89 on the shaft 61 is connected by a link 91 to one end of a main differential lever 93 the other end of which is connected through a bell crank 135 to the governor 125. The main lever 93 is intermediately connected by a link 92 to a lever 94 which is pivoted at 96 and also connected through a link 95 with spring means 97 to the gear lever 31. Modifying means (1) comprises the dashpot 71 connected to an arm 65 on the rock shaft 61. This is, as shown in Fig. 2, adjustable by a screw valve 77. A piston 73 is thrust upwards by a spring 85. The governor 125 is controlled by two springs 120, 130 as shown in Fig. 5. Increase in governor speed moves the gear lever 31 towards high speed. The depression of the accelerator 41 first opens the throttle 43 and then rocks the shaft 61 so as to depress the dashpot piston without appreciable resistance and move the gear lever towards low speed. On release of the accelerator, the dashpot resistance permits immediate closing of the throttle. There is then delayed rocking of the shaft 61 to turn the gear lever towards high ratio. The dashpot thus modifies the joint action of the governor and the manual control to render the speed ratio lower than it otherwise would be. With the engine idling, the governor brings the gear lever to low speed. Modifying means (2) consists in the stop 90, Fig. 2, which is lowered by manipulating a button 102<1>, Fig. 1, which thrusts the piston 73 down or prevents it rising so that the gear lever 31 is displaced towards low speed. By the stop 90 the driver can lower the speed ratio below that produced by the joint action of the governor and the accelerator, or maintain a lower ratio independently of throttle opening ; with throttle closed, the stop 90 enables the engine to be used as a brake. Modifying means (3) is rendered effective by manipulating a button 102 which displaces the pivot 96 to left or right through a cable 100. Leftward displacement with reference to Fig. 10 shifts the gear lever 31 towards low speed, and by such adjustment the engine can be used to decelerate the vehicle. The adjustments of the stop 90 and the pivot 96 may overlap in their effects, but the former serves mainly for varying the full throttle operation without affecting the maximum engine speed while the latter varies the maximum engine speed. A modification of the whole device with relay operation is described with reference to Fig. 6, 7 and 8, not shown. One servo-motor is interposed in the position of the spring connector 97, Fig. 10, and a second servo-motor between the governor 125 and the main differential lever 93. Both are operated by fluid such as oil. This relay control is specially adapted for variable transmission gearing with torqueresponsive control and with inherent tendency to shift into low during drive.