Air/fuel ratio control system for internal combustion engine with airflow rate signal compensation circuit
AssigneeNissan Motor Co., Ltd.
InventorsSadao Takase, Masaharu Asano, Nobuzi Manaka
Life of this patent
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Abstract
An air flow rate compensation circuit is provided to compensate for an erroneous air flow rate signal produced in response to the movement of the flap of an air flow meter disposed in the intake air passage of an internal combustion engine where the erroneous nature of the signal occurs because of an overshoot characteristic of the flap. The compensation circuit produces an output signal with which either an air/fuel ratio control signal produced in response to the air flow rate signal or the air flow rate signal per se is modified where the output signal is produced in response to the movement of the throttle valve or the variation of the air flow rate signal.
Claims10
An air/fuel ratio control system for an internal combustion engine including an air flow meter having a flap disposed in the intake passage of said engine, an air flow rate signal generator for producing a first signal indicative of the intake air flow rate in response to the movement of said flap, a control circuit for producing a second signal in response to the first signal and other engine parameters, and fuel supply means for supplying fuel into said intake passage of said engine, the fuel flow rate being controlled in accordance with said second signal, wherein the improvement comprises:
- an air flow rate signal compensation means for producing a third signal with which one of said first and second signals is modified for electronically compensating for the overshoot characteristic of said flap in response to the variation of the intake air flow rate, said air flow rate signal compensation means including:
- (a) an ON-OFF type switch for detecting whether the angular displacement of the throttle valve of said engine is above a predetermined value or not;
- (b) a differentiation circuit for differentiating the output signal of said ON-OFF type switch;
- and
- (c) means for applying a predetermined voltage to the output of said differentiation circuit for disabling said air flow rate signal compensation means.
An air/fuel ratio control system for an internal combustion engine including an air flow meter having a flap disposed in the intake passage of said engine, an air flow rate signal generator for producing a first signal indicative of the intake air flow rate in response to the movement of said flap, a control circuit for producing a second signal in response to said first signal and other engine parameters, and fuel supply means for supplying fuel into said intake passage of said engine, the fuel flow rate being controlled in accordance with said second signal, wherein the improvement comprises:
- an air flow rate signal compensation means for producing a third signal with which one of said first and second signals is modified for electronically compensating for the overshoot characteristic of said flap in response to the variation of the intake air flow rate, said air flow rate signal compensation means including:
- (a) pulse generating means for producing a first train of pulses in response to a first direction of the movement of the throttle valve of said engine and a second train of pulses in response to a second direction of the movement of said throttle valve, the number of pulses per unit time indicating the variation speed of the angular displacement of said throttle valve;
- and
- (b) an electronic circuit responsive to said first and second trains of pulses for producing said third signal.
Dependencies are inferred from the claim text.