Patent GB-670232-A (GB)
Title: Internal combustion engine charge forming apparatus
IPC: F02M1/00
Filed: 1947-08-13
Abstract: 670,232. Charge forming devices. EVANS PRODUCTS CO. Aug. 13, 1947 [June 16, 1939], No. 22540/47. Class 7(iii). A charge forming device comprises an intake conduit and a heat exchanger vaporizer adapted to be heated by the engine exhaust gases and to supply to the engine a hot rich main vaporized fuel air mixture of which the air forms only a relatively small part of the total air supply to the engine. The heat exchanger is connected to a venturi mixing chamber into which the hot rich vaporized fuel air mixture is sucked at a rate varying with engine speed, and an auxiliary fuel supply is also connected with the intake conduit at the venturi mixing chamber and supplies continuously and/or concurrently liquid volatile fuel thereto at a rate which increases with engine speed up   to a relatively constant and limited value for normal running conditions. As shown, air enters through an air cleaner 112, and passes downwardly to a mixing chamber 68 in an intake 1, from which mixture passes past a throttle valve 113 to an intake manifold 3. Fuel and rich mixture enter the chamber 68 through a venturi 69, gasoline or other like light volatile fuel entering by a passage 145, and a heated rich mixture comprising 5-10 per cent of the total air supply and vaporized fuel entering by way of a pasage 9. A venturi 65 is connected with a heavy or light fuel supply, to form the rich mixture, through selector valves 57, 56. The rich mixture passes through a tortuous passage in an exhaust heated vaporizer 5. There is an insufficient amount of heat available to the vaporizer at low engine speeds, but this amount of heat increases with engine speed and load until it is sufficient beyond which point it is regulated by an automatically controlled valve 99. Volatile idling fuel is supplied to a conventional idling system adjacent the throttle valve 113. The unheated volatile fuel increases at low engine speeds to a relatively constant limited value under normal running condi- ' tions, so that this unheated fuel forms a large proportion of the total fuel supply at low engine speeds, but at higher engine speeds it forms only a small proportion of the total fuel. Additional fuel for acceleration is supplied by a nozzle 167 and accelerating pump 150. The Specification as open to inspection under Sect. 91 states that a conventional full power jet can be employed, but describes an economizer unit 130. The main fuel jet is made larger so that it supplies enough fuel to give the rich mixture necessary for full power at high speeds, and the economizer admits a pre-determined quantity of diluent (i.e. hot or cold air or exhaust gas) for all part speed and part throttle conditions. The economizer may be in accordance with U.S.A. Specifications 2,154,417 and 2,152,028 referred to. The economizer is advantageous since the carburetter described includes a long passage for the heated rich mixture, and with a conventional power jet if this passage is full of mixture of the necessary strength for full power operation during a change to lower power operation the mixture in the intake conduit will not be decreased in strength until all the mixture in the vaporizer has been used up. Conversely during a change from lower to higher power operation, there would be a lag in the increase in the mixture strength in the intake. This is eliminated by the economizer.. Exhaust gas can be admitted to the intake manifold for anti-detonation purposes by means of a valve 174, which is allowed to open under its own weight, and exhaust gas pressure at full power, but held closed at other times by the suction in the intake manifold which acts in a space 170 on a piston 175. In a modification the exhaust gas for antidetonation purposes is admitted by a valve normally closed under its own weight, but having a lost motion connection with the throttle valve, by which it is opened at or near full throttle openings. The valve 99 is responsive to the rate of flow of the exhaust, and is controlled in accordance with the temperature by a bi-metallic coil mounted on the outside of the valve housing. The spindle of the valve at the side of the housing opposite to the coil carries a heavy disc 104, Fig. 2 (Cancelled) for damping purposes. The disc carries a weight 103 adjacent its periphery, which biasses the valve towards its closed position. When closed, the valve directs the engine exhaust through the vaporizer 5. The weight can be secured to the disc in any one of a plurality of holes 105, and since the attachment hole in the weight is eccentric the weight can be moved in or out radially for adjustment purposes. Instead of using separate sources of fuel 49, 52 as shown a single source of relatively light volatile fuel may be used for the whole apparatus. The fuel lift to the venturi member may be greater than in conventional automobile carburetters. No fuel will be drawn into the heating passage when the throttle is closed or nearly closed. The acceleration pump and anti-detonant system may be omitted, for example, in marine installations. Suitable temperatures for the vaporizer are given for use with different fuels. The vaporizer desirably comprises a rather large mass of metal, and the metal is such that it would store a large amount of heat per unit weight, and is a good conducter of heat. The invention could be applied to an updraught carburetter. It is stated that the apparatus makes use of standard carburetter parts and units. This subject-matter does not appear in the Specification as accepted.