| 摘要 |
A four-stroke i.c. engine (10) has an air inlet circuit (30) which communicates with the combustion chamber (20) of the engine's cylinder (14) and is controlled by a valve (34). The engine incorporates a mechanism for advancing or retarding the closure of the inlet valve (34), especially in certain operating conditions, in order to limit the volume of air admitted into the cylinder. The closure of the inlet valve can be advanced so that it takes place before the piston reaches its bdc position on the inlet stroke, with the fuel injected into the combustion chamber after bdc, or the valve can be closed after the piston has reached bdc, with the fuel injected after the instant preceding the closure of the valve and in a time which is less than the minimum time taken for the fuel to pass between the point of injection and the inlet valve.
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