The Bendix Corporation

Roman O Marchak

William A Peterson, Jr

Ralph W Carp

Glen J Drellishak

Douglas R Verner

An acceleration enrichment feature for an electronic fuel injection system is disclosed. The enrichment feature includes an operating parameter enrichment circuit which provides an acceleration signal proportional to the rate of change of an engine operating parameter that is indicative of a desired acceleration. The acceleration signal is combined with an off-closed throttle enrichment signal and the combination is transmitted to a peak detect and decay circuit which produces a control voltage signal equivalent to the peak of the two signals. The control voltage signal from the peak detect and decay circuit is used to regulate a voltage controlled current sink generating an acceleration enrichment signal which varies the termination threshold of the main pulse generation. Additionally included is a warm-up multiplier circuit which varies the acceleration enrichment signal as a function of the engine coolant temperature.

Acceleration enrichment feature for electronic fuel injection system

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. The warm-up feature further includes a time dependent holding level or delay from which the enrichment factor value decays during warm up and a feature to defeat this holding level above a certain engine operating temperature.

Start and warm up features for electronic fuel management systems

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. Another aspect of the invention provides for the authority modification to take place when the controller reaches a threshold and to employ minimum constant authority for quiescent conditions. Also, in response to a closed throttle or idle condition the quiescent authority level is reduced to a convenient idle level to prevent torque roll.

Closed loop system

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. The feature is additionally inhibited at low engine speeds and when the EGR valve is not operational.

Deceleration lean out feature for electronic fuel management systems

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 signal developed by an integral controller. The integral controller bases the closed loop correction signal on a signal from an exhaust gas composition sensor located in the engine exhaust manifold. Various conditions of the system are sensed by a closed loop sensor condition detector to provide information on whether the sensor is up to operating temperature and is operative. If the exhaust gas sensor is functioning and the operating system parameters indicate the system operation should move to closed loop control, the loop is closed by the condition detector. Included in the condition detector circuit is a timer whose cycle is RPM dependent. The timer will time out if the sensor has not indicated an operational capability in one timing cycle or a set number of RPM counts and will generate a signal indicating a sensor failure. After closing the loop, the detector circuit will check for a sensor transition on a periodic basis related to the authority of the integral controller and provide a signal to open the closed loop if the transition does not occur. A rich burst generator is provided to perturbate the loop periodically to produce a rich transition of the sensor if it is operable. A latching failure indicator circuit is additionally included in the system to energize a visual indicator and alert an operator if the failure condition occurs.

Closed loop sensor condition detector

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. Power enrichment for the pressure schedule is provided as a function of altitude by lowering a power enrichment break point for increases in altitude and enrichment for all values of intake pressure is provided as a function of altitude to compensate for the internal EGR of the engine and to provide increased utilization for the closed loop controller.

Altitude compensation feature for electronic fuel management systems

Disclosed herein is a start enrichment circuit for an electronic fuel control system when the engine temperature is above or below its nominal operating temperature range. The circuit produces a start enrichment signal having an initial temperature dependent value while the starter is being energized which decay as a function of time after the engine starts. The preferred embodiment also provides a start enrichment signal within the nominal engine temperature range when the exhaut gas recirculation valve is in an activated state.

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Northville, MI, United States of America

Roman O Marchak