Patent GB-825322-A (GB)
Title: Improved apparatus for forming the combustible charge for internal combustion engines
IPC: F02D9/00
Filed: 1958-01-02
Abstract: 825,322. Charge forming devices; regulating. GENERAL MOTORS CORPORATION. Jan. 2, 1958 [Jan. 18, 1957], No. 165/58. Classes 7(3) and 7(6) In apparatus for forming the combustible charge for an internal combustion engine, fuel under pressure is metered to a separate supply pipe for each cylinder by a metering mechanism responsive to the pressure drop caused by air flow through one of two parallel passages in the engine air induction system and a valve located in the second passage so controls the air flow through the second passage that the pressure drop caused by air flow through the first passage does not fall below a certain value. Referring to Fig. 1 when the throttle 22 is closer or nearly closed and the engine is lightly loaded there is a high vacuum in the intake manifold which is transmitted to the chamber 96 and holds the diaphragm 94 against its spring 112 so that the valve 98 remains closed with the result that the springs 114 and 116 respectively keep the valves 32 and 66 closed. As the throttle opens the valves 32 and 66 are opened. The restriction 108 in the vacuum line to the chamber 104 results in the throttle 32 opening very slightly after the fuel valve 66. The booster pump 45 supplies fuel through the filter 48 to the metering device 42 from which the fuel passes to a distributer 44 driven by the engine cam shaft. In Fig. 2 the fuel tank is indicated at 154 the transfer pump at 165 and the booster pump at 166. Fig. 3 is a diagrammatic view of a portion of the apparatus shown in Fig. 2. When the engine is idling or operating at part load the arm 248 on the shaft of the throttle valves 146 keeps the booster vacuum valve 238 closed so'that the springs 140 and 232 keep the valves 138 and 230 closed with the result that all the fuel flows through the primary orifices 200 and 202. The venturi vacuum is transmitted through the pipe 194 to the chamber 192 with the result that the air diaphragm 186 tends to rock the lever assembly 204 clockwise to open the fuel metering valve 214 and the valve takes up an appropriate position. When the throttle valve 146 is opened for heavy loads the spring 244 is deflected over centre to open the booster vacuum valve 238 and close the vent 246. The fuel valve 230 then opens so that fuel flows through three orifices 200, 202 and 224 and the valve 138 opens. If the intake vacuum drops sufficiently due for example to heavy acceleration the valve 230 opens to allow fuel to flow through the enrichment orifice 224 which causes a reduction in fuel pressure differential across the diaphragm 188 and consequent clockwise rocking of the lever assembly 204 to open the metering valve 214 further. Fuel flow through the enrichment orifice 226 is controlled by a valve 228 which is closed during normal operation but is opened when the induction vacuum is low, that is when the throttle 146 is fully open. A plurality of branch passages 128 communicate with the cylinders of a V-type engine and the distributer 162 distributes fuel to the nozzles 164 located in the branch passages. The compression spring 170 of the by-pass valve 158 is adjustable by means of a spring finger 172 which is rocked by movement of the throttle linkage. In Fig. 4 the valve 260 is normally retained closed by a spring member 262 but can be opened by a diaphragm 264. The flow of fuel through an orifice 273 is controlled by a valve 274 which is connected to a' diaphragm 278. The transmission of vacuum to the chamber 266 and the chamber 280 is controlled by a trigger unit 282. When the air flow through the venturi 254 reaches a certain rate the resulting vacuum acts on the diaphragm 286 to open the booster valve 284 and close the vent 294 so that a vacuum is transmitted from the pipe 292 to the chambers 266 and 280 with the result that the diaphragms 264 and 278 respectively move to open the valves 260 and the fuel valve 274.