Fuel injection control in internal combustion engine

Claim 1

A method for controlling fuel injection in an internal combustion engine comprising the steps of: using a control circuit for calculating a pulse width of a fuel injection signal on the basis of engine rotational speed, intake air amount measured by an air flow meter, and other engine running conditions; establishing an upper limit value for the pulse width of the fuel injection signal on the basis of a maximum intake air amount and that amount per rotation multiplied by a predetermined constant; generating fuel injection signals having a pulse width within said upper limit; and carrying out fuel injection by supplying said generated fuel injection signals to the internal combustion engine, thereby preventing an over-rich air-fuel mixture.

Claim 2

A method for controlling fuel injection in an internal combustion engine comprising the steps of: using a control circuit for calculating a pulse width of a fuel injection signal on the basis of engine rotational speed, intake air amount measured by an air flow meter, and other engine running conditions; establishing an upper limit value for the pulse width of the fuel injection signal on the basis of a maximum intake air amount and that amount per rotation multiplied by a predetermined constant; generating fuel injection signals having a pulse width within said upper limit; and carrying out fuel injection by supplying said generated fuel injection signals to the internal combustion engine, thereby preventing an over-rich air-fuel mixture.

Claim 3

A method for controlling fuel injection in an internal combustion engine, said method comprising the steps of: providing a control circuit for calculating a pulse width of a fuel injection signal on the basis of engine rotational speed N, intake air amount Q measured by an air flow meter, and other engine running conditions; reading-in to the control circuit intake air amount Q and engine rotational speed N; deciding first whether said read-in intake air amount Q is less than a predetermined limit intake air amount Q (lim); when said first decision is negative, substituting said read-in intake air amount Q by Q (lim); calculating a fuel injection period τ by using Q (lim) and N and a predetermined constant C; deciding second whether said calculated fuel injection period τ is less than a predetermined limit fuel injection period τ (lim); when said second decision is negative, substituting said calculated fuel injection period τ by said predetermined limit fuel injection period τ (lim); and delivering a fuel injection signal to said internal combustion engine by using said value τ (lim).

Claim 4

A method for controlling fuel injection in an internal combustion engine, said method comprising the steps of: providing a control circuit for calculating a pulse width of a fuel injection signal on the basis of engine rotational speed N, intake air amount Q measured by an air flow meter, and other engine running conditions; reading-in to the control circuit intake air amount Q and engine rotational speed N; deciding first whether said read-in intake air amount Q is less than a predetermined limit intake air amount Q (lim); when said first decision is negative, substituting said read-in intake air amount Q by Q (lim); calculating a fuel injection period τ by using Q (lim) and N and a predetermined constant C; deciding second whether said calculated fuel injection period τ is less than a predetermined limit fuel injection period τ (lim); when said second decision is negative, substituting said calculated fuel injection period τ by said predetermined limit fuel injection period τ (lim); and delivering a fuel injection signal to said internal combustion engine by using said value τ (lim).