Fuel injection system for internal combustion engine

Claim 1

A fuel injection system for an internal combustion engine having a crankshaft and a combustion chamber, said system comprising (a) an intake passage for introducing an intake gas into said combustion chamber and provided with an intake valve; (b) a fuel injection valve for injecting fuel into said intake passage in the vicinity of said combustion chamber; (c) operating condition detecting means for detecting the operating condition of the engine and outputting a signal corresponding to the thus detected operating condition; (d) fuel injection amount determining means which receives an output signal of said operating condition detecting means, thereby determining the amount of fuel to be supplied to the combustion chamber, and outputs a signal corresponding to thus determined amount; (e) crankshaft angle detecting means for detecting the rotation angle of said crankshaft; (f) injection timing control means which receives signals from said fuel injection amount determining means and crankshaft angle deteccting means, outputs a start signal for actuating said fuel injection valve and a termination signal for terminating the actuation of said fuel injection valve, and actuates said fuel injection valve for the duration between said start and termination signals, thereby supplying an amount of fuel determined by said fuel injection amount determining means; (g) said start and termination signals being set against the crankshaft angle so that the whole fuel injection from said injection valve to said intake passage under light load operation of the engine reaches said combustion chamber substantially in the latter half of the intake stroke before said intake valve is closed; and (h) injection timing correction means which detects the magnitude of blow-back occurring in said intake passage and corrects said start and termination signals against the crankshaft angle in response to the thus detected magnitude so that said start and termination signals advance against the crankshaft angle when the magnitude of blow-back is large under low speed operation of the engine; (i) thereby effectively attaining stratification of air-fuel mixture in said combustion chamber under light load operation of the engine.

Claim 3

A method of controlling fuel injection timing for the production of a stratified charge in a combustion chamber of an internal combustion engine, comprising: providing a fuel injection valve in an intake passage of said internal combustion engine; controlling said fuel injection valve so that fuel injected therefrom under light engine load operation reaches said combustion chamber substantially in the latter half of the intake stroke; detecting the operating condition of the engine; detecting the speed of the engine; determining the timing for terminating fuel injection relative to a crankshaft angle; advancing the crankshaft angle for terminating injection of fuel as the timing at which blow-back of intake gas occurs becomes earlier when the detected engine speed is lower than a predetermined engine speed at which maximum torque can be obtained; determined the duration of fuel injection according to a fuel injection amount corresponding to the operating condition of the engine; and determining the timing for starting fuel injection on the basis of said timing for terminating injection of fuel and said duration of fuel injection.

Claim 4

A method of controlling fuel injection timing for the production of a stratified charge in a combustion chamber of an internal combustion engine, comprising: providing a fuel injection valve in an intake passage of said internal combustion engine; controlling said fuel injection valve so that fuel injected therefrom under light engine load operation reaches said combustion chamber substantially in the latter half of the intake stroke; detecting the operating condition of the engine; detecting the speed of the engine; determining the timing for terminating fuel injection relative to a crankshaft angle; advancing the crankshaft angle for terminating injection of fuel as the timing at which blow-back of intake gas occurs becomes earlier when the detected engine speed is lower than a predetermined engine speed at which maximum torque can be obtained; determined the duration of fuel injection according to a fuel injection amount corresponding to the operating condition of the engine; and determining the timing for starting fuel injection on the basis of said timing for terminating injection of fuel and said duration of fuel injection.