Patent GB-549573-A (GB)
Title: Improvement in variable speed power transmission mechanism
Filed: 1941-04-08
Abstract: 549,573. Fluid-pressure servomotor-control systems. BENDIX AVIATION CORPORATION. April 8, 1941, No. 4696. Convention date, May 13, 1940. [Class 135] [Also in Groups XXIV and XXXVII] In a change speed gearing for automotive vehicles, speed changes are effected by a servomotor controlled by a speed governor and by movement of the accelerator pedal, the engine ignition mechanism being disabled during speed changing. As shown, a shaft 14, Fig. 1, may be driven at either of two speeds by gears 194,200, which are rendered operative by a synchronizing clutch member 196 actuated by a shifter rail 56. The two speed gear drive shown may be used in series with a manually actuated variable speed gear, and a fluid coupling may be embodied in the transmission. The rail 56 is connected by links 52, 50, 36 to the diaphragm 34, Fig. 5, of a servomotor 35 which has a valve 98, actuated by a solenoid 94. An ignition interruptor switch 22 is associated with the servomotor 35. The solenoid 94 and switch 22 are electrically connected to a vehicle speed responsive switch 24, an accelerator switch 26 and the primary winding 28 of an ignition coil 30 of a distributer 31. The link 36 telescopes with a sleeve 38, Fig. 5, fixed to the diaphragm 34, a spring 44 acting between a nut 48 on the link 36 and a nut 46 clamping the diaphragm 34. The latter is urged to the left, Fig. 5, by a spring 90, and is moved to the right when the solenoid 94 is de-energized, the valve 98 then falling and connecting the motor compartment 91 to the engine intake manifold. When the solenoid 94 is energized the diaphragm moves to the left under the action of the spring 90, the compartment 91 then being open to the atmosphere. The sleeve 38 has a pair of grooves 239, 240 ; the groove 239 co-operates with a latch 100 on the valve 98, and the groove 240 permits the switch 22 to open when the diaphragm is in its extreme right-hand position. The governor controlled switch includes two pairs of sectorshaped plates 124, 125, Fig. 12, tied together by pins 126, 127, and pivoted to a plate 128 driven in accordance with the speed of the vehicle. A bowed spring 142 is positioned between abutments carried by members 143 adjustably mounted on the plates 124, 125. The switch 24 which is similar in form to that described in U.S.A. Specification 1,960,020 includes a contact member 135. At low vehicle speeds the switch is closed. As the vehicle speed increases the plates 124, 125, move and flex the spring 142 which acts on the member 135 to move the latter away from the terminal 138 and open the switch. The accelerator switch 26 is normally open, but is closed by movement of a lever 110 when the accelerator 20 is fully depressed. Operati,on.-When the vehicle is at a standstill the switch 24 is closed, the solenoid 94 is energized, the diaphragm 34 is in its left-hand position and the transmission mechanism is in low gear, as shown in Fig. 1. As the vehicle speed increases the switch 24 opens and the solenoid 94 is de-energized. As the throttle valve is open the vacuum in the motor compartment 91 is not sufficient to move the diaphragm 34 to the right. When the vehicle reaches the desired speed the accelerator is released whereupon the increased vacuum which results causes the servomotor to act and the shifter rail 56 is moved to introduce high gear. The latch 100 then engages the groove 239 on the sleeve 38 and holds the diaphragm 34 in its right-hand position against the action of the spring 90; the accelerator may again be depressed without causing operation of the servomotor. If the accelerator is fully depressed, a stop 241 on the link 104 moves the lever 110 to close the switch 26. The solenoid is thus energized, the latch 100 is released, and the diaphragm 34 moves to the left to introduce low gear transmission. During this movement a portion 76 of the sleeve 38 engages the switch 22 and closes it. Thus the ground connection to the breaker switch 147 is completed and the engine ignition is interrupted. The length of the part 76 is such that synchronism of the gear parts occurs before the switch 22 is again opened. The transmission remains in low gear until the accelerator has been released sufficiently to again energize the motor 35 and introduce high gear transmission.