GB1417081A - Internal combustion engine exhaust gas recirculation system - Google Patents

Abstract

1417081 Treating IC engine charges STP CORP 2 May 1973 [1 Nov 1972] 20737/73 Heading FIB A mixture-compressing I.C. engine has an exhaust gas recirculation duct leading from the exhaust manifold to the inlet manifold, the amount of exhaust gas recirculated being controlled by plate valve means in response to the combined effect of atmospheric pressure, intake manifold pressure and exhaust manifold pressure, the flow of recirculated exhaust gas being terminated during some modes of engine operation. I.C. engine 10 has exhaust gas recirculation valve 12 connected by conduit 48 to exhaust manifold 24, by pipe 56 to the air cleaner and by tube 42 to velocity nozzle 36 and hence to the inlet duct 18. The velocity nozzle 36 is also connected by a pipe 40 to a positive crank-case ventilation valve 34. Valve 12 includes a separator plate 50 having openings 58, a tube 61 and a plate valve 70 guided by pins 72 between extreme positions in which it closes the openings 58 or abuts the end face of the tube 61 so that the flow into the tube is controlled by a calibrated orifice 71 in the plate valve. During idling and low speed operation, the high manifold vacuum holds the plate valve against the tube 61 and fresh air enters through the openings 58 to mix with exhaust gas drawn through conduit 48. The exhaust manifold pressure fluctuates between positive and negative during idling, and during negative pressure pulses, air is drawn into the conduit 48 and into the cylinders.. During high speed cruise, the plate valve remains in contact with the tube 61, but the exhaust manifold pressure increases, so that exhaust gas passes to the inlet duct through the orifice 71 and to the air cleaner through the openings 58. During acceleration, the plate valve is forced against the separator plate 50 preventing the admission of fresh air and allowing unrestricted flow of exhaust gas from the conduit 48 to the tube 42. During deceleration, the plate valve is drawn against the tube 61, fresh air is drawn into tube 42 and into the cylinders through the conduit 48. Velocity nozzle 36. Due to the high velocity of the gases issuing from the nozzle 85 during acceleration, a low pressure is created in the port 86 which helps scavenge the crank-case through the valve 34. In a modification. Fig. 8 (not shown) an additional plate valve (69) is provided, between the plate valve 70 and the separator plate 50, the second plate valve being slightly larger in diameter and having a bigger orifice. Operation is similar except that during high speed cruise the second valve is pressed tightly against the separator plate, closing the openings 58. In a modification construction. Fig. 14, a poppet valve 170 is provided, which controls holes 158a in the separator plate and during idling is held against the separator plate so that air passes only through holes 158 to the inlet duct and also to the cylinders through conduit 48. During high speed cruise, the plate valve 169 is against the end of tube 61 and the poppet valve is against its seat 113 so that no fresh air enters and exhaust gas passes from the conduit 48 to the inlet duct. During acceleration, the exhaust gas pressure forces the plate valve 169 against the separator plate and the poppet valve against its seat 113. Exhaust gas passes directly from conduit 48 into tube 161. During deceleration, the plate 169 is held against tube 161 and poppet valve 170 against the underside of the separator plate. Fresh air enters the tube 161 through the orifice in plate 169 and is drawn into the cylinders through conduit 48. Ignition timing, is modified by an air bleed. Fig. 22 (not shown) into the line leading to the distributer vacuum advance diaphragm, which retards the spark to help reduce the formation of pollutants.