Patent GB-819988-A (GB)
Title: Improvements in or relating to carburetter systems
IPC: F02M13/02
Filed: 1957-02-25
Abstract: 819,988. Carburetters. GENERAL MOTORS CORPORATION. Oct. 25, 1957 [Nov. 2, 1956], No. 33374/57. Class 7(3) A primary carburetter has at least one manually operable throttle valve and an auxiliary carburetter has at least one throttle valve actuatable by a power device to either only a closed or a fully open position and a control device is operable by the manually operable throttle valve at a predetermined position thereof to control the operation of the power device. As shown, three two-barrel carburetters indicated generally at 10, 12 and 14 are used. The auxiliary carburetters 12 and 14 have been modified to eliminate unnecessary components such as choke valves either manual or automatic. The main carburetter 10 is manually operable and includes an automatic choke 16 which operates through a thermostat to control a choke valve 18 which will gradually open as the engine temperature rises until such time as it is completely open. The accelerator control pedal linkage (not shown) is articulated to the lever 24. Fast and slow idle adjustments 28 and 30 and a throttle return check 32 are provided. The auxiliary throttle valves 38 and 40 are simultaneously operated. A thermostatically controlled latching device is provided which will insure that the auxiliary throttle valves cannot be opened until such time as the engine has warmed sufficiently. This latching device is controlled by the thermostat of the choke valve 18. Accelerator pumps (not shown) are actuated by throttle rods 70, 72 and 74. The auxiliary carburetters do not include idling fuel systems. The auxiliary throttle valves are spring biased to closed position. The accelerator pump springs are on the opposite side of the carburetter to the other spring biasing the throttles 38 and 40 to closed position. It is desirable to use 15 degrees rather than the normal 10 degrees, throttles and further to make these throttles relatively thick. All operation except that requiring relatively high horsepower output is achieved through combustible mixture supplied by the manual carburetter 10. While numerous power systems, electrical hydraulic or the like may be employed to provide the force for opening the auxiliary throttles it is preferred to utilize a vacuum force derived from a vacuum booster pump 90 which maintains vacuum at a relatively constant level for various uses for example windscreen wiper actuation. A vacuum servo 92 is employed to move the auxiliary throttles to open position. Admission of vacuum to the servo 92 is controlled by a slide member 128 which is controlled by the manually operated throttles 22. The manual throttles 22 are substantially threefourths open before the auxiliary throttles are opened. Upon moving the manual throttles towards closed position a spring biased plunger, not shown, returns the slide member 128 to the upper position in which the servo supply conduit 106 will be in communication with the conduit 114 admitting air to the servo chamber 102. If the plunger is unable to shift the air valve member from the down or auxiliary throttle opening position arm 124 will force the slide member 128 to its upper venting position.