Patent GB-1074635-A (GB)
Title: Improvements in or relating to internal combustion engines
Inventor: BARTHOLOMEW EARL
IPC: F02M3/045
Filed: 1964-08-06
Abstract: 1,074,635. Spray carburetters; intake manifolds. ETHYL CORPORATION. Aug. 6, 1964, No. 32128/64. Heading F1B. In an engine in which the fuel is cut-off during over-running, means are provided to supply extra fuel when the cut-off is terminated. In Figs. 1 and 2 separate carburetters 32, 232, feed respectively small and large manifolds 21, 22, the branches of which remain separate up to a point 20 adjacent the intake port. The engine operates on the small manifold 21 only up to a predetermined power, whereupon the throttle valve 234 of the layer manifold 27 is opened to render both manifolds operative. The smaller carburetter 32 has main, idling and power nozzles 42, 44, 41, 43, a fuel cut-off valve 162 and a pump 110 for supplying additional fuel when the valve 162 is reopened after an over-running period. Under normal operating conditions valve 162 is held open by suction from a vacuum source 150, such as a vacuum pump, connected to pipe 143 through port 140 in a valve 132. If throttle valve 34 is closed suddenly at speed, the high suction in manifold 21 moves piston 170 to the left to close switch 169 which energizes solenoid 167 to move valve 140 to the left to cut vacuum source 150 off from pipe 143, whereupon fuel cut-off valve 162 closes, and connects it to pipe 124 to move diaphragm 116 downwards to charge pump 110 with fuel from float chamber 52. When the engine speed approaches idling, the decreased manifold suction permits opening of switch 169 whereupon valve 132 returns to normal position so that valve 162 opens and simultaneously pump 110 discharges through pipe 45 into an idling air by-pass 53 to provide a rich mixture which facilitates restarting of combustion in the cylinders. A constriction 49 causes the pump 110 to discharge over a considerable period such as several seconds. A pneumatic dashpot 182 delays the travel of throttle valve 34 to its completely closed position to avoid a too sudden fuel cut-off. Throttle valve operation. Throttle valve 34 is connected to a disc 212 resiliently connected by spring 308 to the accelerator pedal control 292. When throttle valve 34 is fully open disc 212 is held stationary by stop 255 and a flange 304 on rod 292 begins to move a disc 217 freely mounted on the pivot of throttle valve 234, which disc limits the amount by which throttle 234 can be opened by a pneumatic piston 282. In its full open position disc 212 closes switch 314 in the circuit of a solenoid 366 which is also controlled by a switch 368 actuated by a device 370 operated by suction in the manifold 21. If at full throttle position of valve 34 the suction in manifold 21 exceeds a predetermined valve, switch 368 is closed to energize solenoid 366 which moves valve 330 to connect piston 282 to the vacuum source 150, Fig. 1, whereby throttle valve 234 is opened to the limit set by disc 217 and the engine operates on both manifolds 21, 22. Simultaneously a pipe 440 may be connected to the vacuum source to operate a pump 410 to inject extra fuel into carburetter throat 232 to smooth the changeover. A delay device may be included in the circuit of solenoid 366 to prevent bringing the larger manifold into operation by a transient rise in suction in manifold 21. Cold-running. In addition to manual or automatic choke valves, an air bleed 86 into fuel passage 82 is held closed at cold starting or cold-running by a thermostat 90 to enrich the mixture. Manifold details. The separate manifolds 21, 22, may be replaced by a single manifold with a deformable wall or with an inflatable tube therein, changeover to the small cross-section manifold being achieved by squeezing the deformable wall or inflating the internal conduit.