Abstract: An air flow sensor (10) as may be used to measure input air to an internal combustion engine has an aerodynamically designed impact tube (16) for diverting bypass air to a pair of sensors (28, 30). Downstream from the impact tube (16) is a venturi section providing exhaust means for the bypass air. The exhaust path configuration for the bypass air shields the sensors (28, 30) from a reverse pressure wave which can result from an engine backfire. The impact tube (16) operates to integrate the air velocity over a full radius of the air flow body (14).

Abstract: A closed loop system for the control of the air/fuel ratio of an internal combustion engine is disclosed. The system includes an open loop air/fuel ratio controller that has a closed loop correction applied to its basic pulse width control signal. The closed loop correction is based upon the bi-level switching of an oxygen sensor detecting a substantially stoichiometric condition in the exhaust gas of the internal combustion engine. Performing the correction is an integral controller which responds to the switching of the exhaust gas sensor to increase the air/fuel ratio for one level of the sensor and to decrease the air/fuel ratio for the other level. The limit cycle oscillation developed by the integral controller is modified by increasing the authority and gain rate of the controller as a function of the distance the system is away from a reference point so that it responds to transient conditions rapidly and smoothly.

Abstract: An electronic control unit for regulating the air/fuel ratio of an internal combustion engine is disclosed. The electronic control unit has an open loop calibration for regulating the air/fuel ratio that is corrected with a closed loop correction signal developed by an integral controller. The open loop calibration is a speed-density based schedule which is combined with corrections for special conditions to account for the operating parameters of the engine at any instant. Included in these special condition corrections are provisions for increasing the air/fuel ratio upon a deceleration sufficient enough to cause a rich air/fuel ratio breakthrough because of the EGR valve lag time. A deceleration detector senses decelerations in excess of this predetermined amount by measuring the rate of change of the pressure in the intake manifold of the engine. A fixed percentage increase in air/fuel ratio is switched into the open loop calibration when the deceleration exceeds the amount required for breakthrough.

Abstract: An electronic control unit for regulating the air/fuel ratio of an internal combustion engine is disclosed. The electronic control unit has an open loop calibration for regulating the air/fuel ratio that is corrected with a closed loop correction signal developed by an integral controller. The open loop calibration is a speed-density based schedule which is combined with corrections for special conditions to account for the operating parameters of the engine at any instant. Included in these special condition corrections are provisions for an altitude compensation feature. The altitude compensation feature includes circuitry to modify the intake manifold pressure portion of the speed density schedule with two variables which depend on altitude.

Abstract: An electronic control unit for regulating the air/fuel ratio of an internal combustion engine is disclosed. The electronic control unit has an open loop calibration for regulating air/fuel ratio that is corrected with a closed loop correction signal developed by an integral controller. The open loop calibration is a speed-density based schedule which is combined with corrections for special conditions to account for the operating parameters of the engine at any instant. Included in these special condition corrections are provision for start and warm-up features. The start feature includes an enrichment pulse generator whose pulses have a duration dependent upon the engine operating temperature and speed which are inhibited while the engine is above a predetermined RPM. The warm-up feature includes a time and temperature dependent enrichment which is linearly multiplied by an engine load factor.

Abstract: An electronic fuel control system for an internal combustion engine is disclosed capable of providing an enriched fuel/air mixture to the engine as a function of the engine's temperature and the engine's load during the transient warm up period. The fuel control unit embodies a full load warm up enrichment circuit controlling, in response to engine temperatures below a predetermined temperature and engine loads as determined from the pressure in the engine's intake manifold, the quantity of fuel being delivered to the engine. In the preferred embodiment the full load warm up enrichment circuit is a current sink sinking a portion of the current charging the injection timing capacitor in the electronic control unit to increase the duration of the generated injection fuel delivery pulses.

Abstract: An auxiliary air control system is disclosed for automatically controlling the air flow to an internal combustion engine during the starting phase of the engine's operational cycle to facilitate clean consistant starts under both hot and cold engine conditions. The system embodies an electrically actuated control providing a predetermined air flow during the cranking and subsequent start of the engine. After the start has been achieved, the engine is permitted to accelerate to a speed determined from the engine's temperature. Thereafter the air flow is reduced in a controlled manner to the normal idle air flow. The system not only facilitates consistent starting of the engine but also substantially reduces the noxious exhaust emissions normally attendant the starting of an internal combustion engine.