Patent GB-610902-A (GB)
Title: Charge forming device for internal combustion engines
IPC: F02D19/12
Filed: 1946-11-11
Abstract: 610,902. Spray carburetters. BENDIX AVIATION CORPORATION. Nov. 11, 1946, No. 33475. Convention date, Dec. 21, 1945. Addition to 601,607. [Class 7 (iii)] The device according to the parent Specification for supplying water or other auxiliary fluid to the charge for an internal combustion engine is modified by the provision of means for regulating the metering head across the auxiliary charge-metering means as a function of the primary fuel metering pressure modified by a pressure derived from the supercharger. The engine 10 has an air intake 11 with a throttle 12 controllable manually or automatically from a pilot's lever 14. A supercharger 15 delivers mixture to a manifold 16 and as shown has two speeds controlled by linkage 20, 22 operated by a solenoid 21 which when energised moves the link 20 to the dotted-line position Fig. 1 to give the high speed. Alternatively a supercharger having continuously-variable speed may be employed. The carburetter is similar to that described in the parent Specification, having air-pressure differential chambers 31, 32 and fuel-pressure differential chambers 33, 34 controlling fuel flow to the jet assembly 28 in proportion to the rate of air flow and giving a constant fuel air mixture. The water, or other auxiliary fluid metering unit 65 is also similar to that described in the parent Specification, water being supplied by a pump 67 to a chamber 68 past a valve 78 which establishes a predetermined metering head in a chamber 69 whence the fluid flows through the metering devices proper 96, 93 to a line 101 to mix with the fuel supplied along line 43. To control the metering head, a line 120 conveys unmetered fuel through a pressure-reducing orifice 127 to the diaphragm chamber 80 thus tending to open the valve 76 until the water pressure in chamber 69 reaches the unmetered fuel pressure. During periods of water injection the fuel/air mixture is weakened by controlling a derichment valve 103 in the manner described in the parent Specification. The orifice 127 in the line 120 is in parallel with a passage 126 controlled by a valve 123 actuated by a solenoid coil 125. When the valve is open the effect of the restriction 127 is neutralised and an increased pressure is obtained in chamber 80 resulting in an increased metering head. This control is related to the supercharger speed changing means as shown in Fig. 3. A sealed housing 130 communicates with air intake 11 through line 131, thus actuating a pressure or density-responsive bellows 132 controlling a switch 133 in a circuit which includes the solenoid 137 of a relay switch 138. The latter when closed completes a circuit through an automatic switch to the solenoids 21<1> and 125. In the position shown in Fig. 3 a predetermined 'scoop pressure or air density causes the energisation of both solenoids, and changes the supercharger to high speed and opens valve 123 to increase the water injection. In the middle position of switch 142 the supercharger remains on low speed and in the lower position the high speed is obtained. The water pump 67 is controlled by a bellows 146 open to manifold pressure through line 148, the bellows being arranged to close the switch and start the water pump at an absolute manifold pressure of about 67 inches of mercury. In a modification, for engines having continuously - variable supercharger speeds a sectional housing comprises a manifold pressure chamber and supercharger inlet pressure chamber separated by a diaphragm controlled by a capsule in pressure communication with a temperature-responsive bulb located in the supercharger discharge ring. The water pump may as before be started automatically at a predetermined manifold pressure and the metering head in chamber 80 varies in direct rotation to temperature and pressure rise across the supercharger. Specification 523,895 is referred to.