The Lean-Mixture Combustion In A CA1102Q Five-Valve S.I.Engine With Electronic-Controlled Port-Fuel-Injection

This paper aims at developing a multi-valve lean-burn S.I. engine with higher performence ,lower exhaust emissions and fuel comsumption. First, various tumbling intake port designs are tested on a steady flow rig, and then a high intensity tumbling three-intake-port biuld is established. Second, the modern CA1102Q dual valve engine is remade into five-valve DOHC port-injection lean-burn engine and is tested. And last, an novel conception of "Dividing Injection" for port injection engine is put forward.The results of investigation into tumbling intake port designs reveals that the composite of a modern tumbling port and a subport can produce the effection of enhancing tumbling intensity over 15% while maintaining large flow coefficiency, differiently from the effection of the subport used with diesiel swirl port; that the way neither to design the port section shape complex nor to set a upright partition in the port can reach the goal to distinctly improve the port's composite performance; that the in-cylinder tumbling intensity of the three-intake-port chamber is much influenced by the position of the mid intake valve ; and that the corelationship of three-intake-valve between the flow rate and the valve lift is much closer to the ideal rapid switch specific property.The results of 5-valve engine test showes that it has much better lean-burn performance and emission index, it's specific fuel comsumption is lower 24%, power is higher 10.6% when compared with the original engine at the same compression ratio. It is even effective using the variable intake system to improve the engine's performence in all running condition. the 5-valve engine has two injection regions for lean mixture combustion steady , this phenomina is different from that of dual-intake-valve s.i. engines.The "Dividing Injection" methed enlarges the lean-burn misfire limitation and improves the fuel economy, decreases the spesific fuel comsumption 8% lower than normal injection at the same air-fuel ratio. The beneficial results from the usage of "Dividing Injection" technique is no less than that from the substitution of carburettors by fuel injection nozzles.