Patent GB-680701-A (GB)
Title: Improvements in auxiliary charge regulating devices for internal combustion engines
IPC: F02M25/14
Filed: 1946-04-04
Abstract: 680,701. Spray carburetters. BENDIX AVIATION CORPORATION. April 4, 1946 [April 12, 1945], No. 10498/46. Class 7 (iii). Auxiliary fluid such as water, alcohol &c. is supplied to the air-fuel mixture of a supercharged internal combustion engine through metering means including a valve controlling the flow of said fluid in response to pressure rise across the supercharger or supercharger system. Air from a scoop 11 passes a throttle 12 and entÞrs a supercharger 14 delivering to a ring 15. The auxiliary fluid metering system is associated with a metering pump 16 of the kind described in Specification 652,853 whereby normal fuel is metered in relation to engine speed and also to mass air consumption. Metered fuel passes along conduit 21 to mixing device 22 associated with water or other fluid metering unit 23, the mixed fuel then passing through valve 20' into the conduit 11. Water in a tank 24 is pumped along a line 25 to the unit 23 by a pump 26 controlled as described in Specification 601,607. From chamber 30, Fig. 2, a valve 31 opened against a spring 32 leads to chamber 30' whence flow may occur past a valve 38 to a diaphragm chamber 41 in communication with a metering head chamber 43. The latter contains a metering valve 44 which controls flow to a chamber 48 leading through passage 51 to the metered primary fuel. The valve 38 is seated by an adjustable spring 52. A pair of diaphragms 61, 62, are connected to a guide rod 64 having a ball-head engaging the valve 38. The upper diaphragm chamber 65 communicates with chamber 50 which is at discharge nozzle pressure. A spring 67 closes the valve 38 when the pressure in chamber 41 is at a predetermined value above discharge nozzle pressure. This value determines a constant pressure drop across valve 44. The opening of the metering valve 44 is related to the pressure drop across the supercharger. For this purpose the valve is controlled by a rod 72 located between diaphragms 70, 87, the assembly being urged upwardly by a spring 80 to allow the valve 44 to seat. Supercharger inlet pressure is maintained in chamber 76 by a conduit 77 and outlet pressure is communicated to chamber 78 through a duct 79'. The supercharger outlet to line 79' is controlled by a valve 91 actuated by a solenoid 93 controlled by a switch plunger 96<SP>1</SP> adapted to close switch contacts 97 and actuated either from the power control lever or in response to other emergency power conditions. A temperature compensator comprises a needle 105 actuated from bellows 106 forming part of a fluid containing system which includes a bulb 110. The arrangement is such that rise in temperature tends to move the valve to close a passage 112 between chamber 103 and chamber 76 so as to increase the pressure above diaphragm 70 for a given pressure rise across the supercharger. This causes increased opening of valve 44 with increase of the temperature. In some cases the bulb 110 may be located between supercharger stages. For weakening the mixture during periods of water injection a diaphragm 115 controls a valve 119. Unmetered fuel in chamber 131 flows to a line 132 under the control of a valve 135 in a "derichment" device forming the subject-matter of Specification 680,756. During normal operation the "derichment" valve 130 is open and fuel is metered by two orifices 133, 134. When water injection starts the drop of pressure across valve 31 causes valve 119 to open and admit pressure to line 123 so as to close the derichment valve 130. Fuel is then metered only through the orifice 133. Valve 41 controls water pressure in chamber 42 and maintains constant metering head across valve 44. This valve opening is influenced by the pressure rise across the supercharger and changes in inlet air temperature. In some cases the temperature compensating unit is dispensed with or alternatively, it may be used to modify the action of valve 38 to vary the metering head across valve 44 as a function of the temperature.