Patent GB-1322550-A (GB)
Title: Controlling emissions from the exhausts of motor vehicles
IPC: F02M7/18
Filed: 1970-12-23
Abstract: 1322550 Spray carburettors SUN OIL CO 23 Dec 1970 [30 Dec 1969] 61019/70 Heading F1B An exhaust emission control apparatus for a motor vehicle I. C. engine, comprising a carburettor for feeding a fuel air mixture to the engine intake, enriching means for increasing the fuelair ratio in said mixture, and means for actuating said enriching means at engine or vehicle speeds below a first predetermined speed but above a second lower predetermined speed and for terminating the action of said enriching means upon reaching said first predetermined speed.  The carburettor includes a part 2a which communicates with the float chamber and thus contains fuel to a level 6, the space above the fuel being at atmospheric pressure. A passageway 29 leads to the main well of the carburettor, the flow of fuel being controlled by a valve 10, biased by a spring 14 towards a seat 11. A piston 8 is reciprocable in a cylinder 7, and has a piston rod 9 which engages an upwardly projecting stem on the valve 10. A spring 12 abuts a collar 13 on the piston rod and biases the piston towards its lowermost position. The upper end of the cylinder 7 is connected to the inlet manifold by a line 16 which can be closed by a solenoid operated valve 15. The solenoid 22 is energized through the normally closed contacts of a relay 20, and when energized moves the valve 15 to the closed position, so that the manifold vacuum is not applied to the piston. The relay 20 is connected to the output of a pulsecounting and trigger unit 18 which receives and rectifies pulses from the ignition coil and produces a signal voltage when the pulse rate corresponds to a predetermined engine speed equivalent to a vehicle speed of say, 35 m.p.h. Operation. When the engine speed is less than the predetermined figure, the relay is not energized, contacts 21 are closed and valve 15 is shut, so that no vacuum is applied to cylinder 7. Spring 12 then moves rod 9 and valve 10 downwards so that additional fuel is supplied to the engine, which reduces the formation of NOx and aldehydes. The resulting increased amount of carbon monoxide and hydrocarbons in the exhaust gas is oxidized by passing the exhaust gas through a reactor to which secondary air is fed by an engine driven pump. The amount of air supplied is sufficient to burn the pollutants at low engine speeds, and, at higher engine speeds the excess air-flow serves to cool the reactors. Enrichment of the fuel when the engine is idling is prevented by providing a further switch in the solenoid circuit which is connected to the throttle and opens when the throttle is in a position corresponding to less than 15 m.p.h. Opening of the switch de-energizes the solenoid so that valve 15 opens and manifold vacuum is applied to cylinder 7, so that valve 10 closes. To further reduce the amount of pollutants the ignition timing may be retarded and/ or some of the exhaust gas may be re-circulated if loss of performance is acceptable. With the device in operation, the following results were obtained in a test vehicle: Nox, 354 ppm; HC, 39 ppm; Aldehydes 48 ppm; CO, 0À20%.