Abstract: A system for solving disturbances in the air-fuel ratio caused by a change in the normal correction factor, and permitting achievement of a highly accurate air-fuel ratio control. Fuel evaporative gas generated in a fuel tank is adsorbed in a canister, and then discharged into an intake pipe of an internal combustion engine. ECU calculates the fuel supply quantity to the internal combustion engine on the basis of the condition in which the internal combustion engine is operating, performs feedback control and learning control of an air-fuel ratio on the basis of a detection signal from an oxygen sensor, and corrects the fuel supply quantity by means of an air-fuel correction factor. ECU also controls fuel injection by an injector by decrement-correcting the fuel supply quantity in response to the quantity of discharged evaporative gas.

Abstract: An air-fuel control system for an internal combustion engine is provided in which air-fuel ratio control system a deviation effect due to an amount of evaporated fuel distributed to each cylinder group differing from cylinder group to cylinder group is eliminated when a deviation of air-fuel ratio due to aging of the engine has been learned. A difference value between the air-fuel correction factor and a value of a range of distribution deviation of the air-fuel ratio is obtained so that the difference value is used as the air-fuel correction factor. The difference value is obtained when the engine is determined to be in a purging operation by the first determining means, and when it is determined that learning of the air-fuel ratio correction factor is not completed. The difference value represents a true deviation of the air-fuel ratio due to aging of the engine parts.

Abstract: In a fuel vapor purge mechanism, the fuel vapor generated from a fuel tank and stored in a canister undergoes flow volume control with a purge solenoid valve while being introduced to an intake system of the engine via a purge passageway. Meanwhile, in an air/fuel ratio feedback control system, by means of a linear air/fuel ratio sensor mounted on an exhaust system of the engine, the air/fuel ratio of air-fuel mixture of fuel and intake air including the fuel vapor. If a change amount of a purge ratio the fuel vapor goes above a determined value, there is compensation of the air/fuel ratio compensation coefficient FAF concerned with the feedback control based on the change ratio.

Abstract: In an evaporative fuel control system in an internal combustion engine, a purge gas concentration is estimated by a purge gas concentration estimating device based on an air-fuel ratio correcting factor provided when a purge control valve is in its opened state and an air-fuel ratio correcting factor provided when the purge control valve is in its closed state. A lower limit value of an air-fuel ratio correcting factor, set by an air-fuel ratio correcting factor setting device, is determined by an air-fuel ratio correcting factor limit value setting device in accordance with the purge gas concentration estimated by the purge gas concentration estimating device. Thus, the lower limit value of the air-fuel ratio correcting factor can be varied depending upon the concentration of the purge gas, thereby setting an air-fuel ratio control range corresponding to the concentration of the purge gas.

Abstract: A purge amount is estimated by taking the change of purge amounts of a vapor from a canister side and a fuel tank side into consideration, an amount of fuel injection is corrected by the purge amount so estimated, and air-fuel ratio control is executed with a high level of accuracy. In an apparatus for correcting an amount of fuel injection of an internal combustion engine for purging the vapor directly evaporating from the fuel tank and the vapor emitted from the canister into an intake passage through a solenoid control valve and executing an air-fuel ratio control on the basis of the total purge flow amount, a correction amount of the amount of fuel injection on the tank side, which changes with the vapor supplied directly from the fuel tank into the intake passage through the control valve is calculated and a correction amount of fuel injection on the canister side which changes by the vapor supplied from the canister to the intake passage through the control valve is calculated.

Abstract: An engine provided with a purge valve introducing fuel vapor from the fuel tank into the intake passage, a purge valve for opening and closing the passage, a device for setting a basic flowrate of the purge valve according to the engine running conditions, and a device for detecting the fuel concentration of the purge gas. Further, a device is provided for correcting the basic flowrate based on the fuel concentration of the purge gas so as to decrease the purge valve flowrate when the fuel concentration is high, and increase the purge valve flowrate when it is low. The purge valve opening is controlled according to this corrected flowrate, and purging can therefore be performed rapidly without adversely affecting the air-fuel ratio.

Abstract: A control system for an internal combustion engine controls a fuel injection amount based on operating conditions of the engine and an evaporative fuel concentration-dependent correction coefficient. The control system includes a purge control valve arranged in a purging passage connecting a canister for temporarily storing evaporative fuel generated from a fuel tank and an intake passage. This coefficient is held to a predetermined value for a predetermined time period after purging is permitted, and to another for a predetermined time period after purging is inhibited. In another aspect, the purge control valve is controlled based on operating conditions of the engine and a purging flow rate correction coefficient. This coefficient is held when purging is inhibited, and is progressively set to a larger value depending on the evaporative fuel-dependent correction coefficient, after purging is permitted.

Abstract: A method for controlling canister purge of an internal combustion engine is disclosed. Based on a change rate of an air-fuel ratio correction coefficient per unit duty, a canister loading ratio is assumed by looking up a map. Further based on the canister loading ratio, a correction amount to the purge control duty for controlling the purge amount from the canister is determine. It is therefore possible to control a canister purge in accordance with the canister loading amount, whereby an over-loading of the canister can be prevented even under a high evaporation condition such as at extremely high temperatures or high altitudes. A deviation of the air-fuel ratio caused by the canister purge can be calculated, whereby an improvement in startability, driveability and emissions can be achieved by updating air-fuel ratio learning values with new learning values excluding a deviation of the air-fuel ratio caused by the canister purge.

Abstract: Fuel injection controller is provided for an engine having a purge passage for purging fuel vapor from the fuel tank into the intake passage, a purge valve which opens and closes the purge passage and a mechanism for feedback correcting a fuel injection amount based on a detected air-fuel ratio, The controller learns a feedback correction amount when the purge valve opens or closes, stores and updates a learning value according to the variation of the correction amount. When the variation of the learning value has converged to within certain region, the controller clamps the learning value, and corrects the fuel injection amount during purge based on this clamped value. Air-fuel ratio errors due to purging can therefore be rapidly reduced.

Abstract: An air-fuel ratio control system for an internal combustion engine which includes an evaporative fuel purge system having a canister for temporarily storing fuel vapor, detects an air to fuel ratio in the exhaust gas from the engine. An air-fuel ratio controller controls the air-fuel ratio in exhaust gas from the engine by varying a fuel quantity supplied to the engine so that the air-fuel ratio approaches a predetermined target air-fuel ratio. The evaporated fuel is purged from the canister at a specific purging rate determined based on engine operating conditions. An air-fuel ratio-shift is controlled based on the derivation of an amount by which the air-fuel ratio has shifted from the target air-fuel ratio due to a cause independent of the purging operation.

Abstract: An air-fuel ratio control apparatus constructed, in an engine of a type storing evaporated fuel generated in a fuel tank in a canister and thereafter drawing off the evaporated fuel to an intake side of an engine through a bleedoff passage, so as to inhibit renewal of an air-fuel ratio learning value when the evaporated fuel concentration is at a predetermined value or higher in case of learning and renewal of an air-fuel ratio in order to make feedback control of the air-fuel ratio of an air-fuel mixture supplied to the engine. In an apparatus which adsorbs evaporated fuel generated in a fuel tank in a canister and purges the evaporated fuel adsorbed in the canister to an intake side of an internal combustion engine together with air through a purge valve, an air-fuel ratio learning value is renewed in accordance with a deviation between an air-fuel ratio feedback FAF value detected by an oxygen sensor and a FAFSM value obtained by smoothing the FAF value with a large smoothing constant.

Abstract: Fuel injection controller is provided for an engine having a purge passage for purging fuel vapor from the fuel tank into the intake passage, a purge valve which opens and closes the purge passage and a mechanism for feedback correcting a fuel injection amount based on a detected air-fuel ratio. The controller comprises a device for detecting the fuel flowrate in the purge passage, a device for subtracting the fuel flowrate in the purge passage from the basic injection amount so as to correct the set injection amount, and a device for increasing a fuel feedback gain of the air-fuel ratio feedback correction. In this way, even if the air-fuel ratio feedback correction amount decreases due to purge, the air-fuel ratio feedback gain will not decrease and the response of the air-fuel ratio correction can be maintained.

Abstract: A method for alternately carrying out phases with and without tank venting during operation of an internal combustion engine equipped with a tank-venting assembly is characterized in that the ratio of the time spans with and without tank venting is selected to be dependent upon operating data of the engine or of the tank-venting assembly. Preferably, a variable is measured which is a measure for the fuel quantity to be regenerated during tank venting and the above-mentioned ratio is increased in favor of the tank-venting time span with respect to the base ratio when the value of the measured variable exceeds an upper limit (Dp.sub.-- SMW; FTEA.sub.-- SWU). This method makes possible that an adsorption filter and a tank-venting valve in the corresponding arrangement can be dimensioned for lesser throughput quantities than previously without the danger being present that fuel vapors escape to the ambient.

Abstract: An air-fuel ratio controller of an internal combustion engine for preventing that an air-fuel ratio in the beginning of the purging operation of evaporated fuel is excessive. Evaporated fuel produced within a fuel tank is absorbed in a canister and the evaporated fuel absorbed in the canister is purged to the air intake side of the internal combustion engine through a purge valve together with air. A concentration of the evaporated fuel is detected by an air-fuel ratio feedback value detected by an oxygen sensor and a fuel injection quantity is corrected to be reduced in accordance with the detected evaporated fuel concentration and the purge ratio. When the air-fuel ratio feedback value exceeds a predetermined value or an output of the oxygen sensor is rich during the purging operation, it is judged that detection of concentration is insufficient and the update value for detection of concentration is made larger than a usual value.

Abstract: An apparatus for controlling an engine operation such as EGR rate for an internal combustion engine is disclosed with an air/fuel mixture ratio control. In the control apparatus, a variable representing a characteristic of a combustion state in the engine is detected and a difference of the combustion state variable, a target value is averaged for each rich/lean period T determined from the variation of a feedback correction coefficient so that a basic EGR (Exhaust Gas Recirculation) rate determined according to the engine operating condition is corrected on the basis of the average value to derive a final EGR rate. Thus, the variation in the EGR rate cannot be amplified or incremented even when the variation in the combustion state variable occurs due to the influence of the variation in the air/fuel mixture ratio.

Abstract: A closed loop control for an internal combustion engine with a positive crankcase ventilation is disclosed. According to this control system, the appearance of blowby gas is detected in response to variation in feedback correction coefficient (alpha), and a product of a transient blowby gas variable (BTBL) and a time dependent factor (B.sub.T) is calculated and a blowby gas recirculation coefficient (KBLRC) is modified by this product (BTBL.times.B.sub.T) to give a modified blowby gas recirculation coefficient (KBLRC2). This modified coefficient is used in calculating a fuel injection amount (Ti) during supply of substantial blowby gas to the combustion engine after start-up of the engine.

Abstract: To improve combustion efficiency of gasoline engines having fuel injection responsive to, among other inputs, an exhaust sensor, fuel is introduced into the intake manifold in a constant stream. The fuel is taken from a return line returning excess fuel from the fuel injection system back to the fuel tank. This fuel is fed into a vacuum conduit in communication with the intake manifold, the vacuum conduit preferably being a fuel cannister purge line, or a positive crankcase ventilation line. Fuel vaporizes due to being subjected to high vacuum over a long path of travel. As the proportion of fuel introduced into the engine as a vapor increases, and reliance upon fuel which is merely atomized by the fuel injection system decreases, combustion efficiency is improved.

Abstract: In the method for the adapted precontrol and feedback control of the air/fuel mixtures to be supplied to the two fuel-metering devices of an internal combustion engine, which has two separate exhaust-gas channels with a lambda probe and a catalytic converter in each channel, a common value of the precontrol manipulated variable and a common lambda desired value are determined for both fuel-metering devices. On the other hand, values of a control manipulated variable are determined separately for each fuel-metering device and values of precontrol adaptation variables, which are dependent upon the values of the control manipulated value, are determined and are superposed separately one after the other on the common precontrol value. This method makes it possible to manage with a single device for both cylinder banks which are to be operated in a stereo lambda control.

Abstract: An engine exhaust gas recirculation system has an intake passage (2) connected to feed an air/fuel mixture to an internal combustion engine and an exhaust passage (1) connected to discharge an exhaust gas from the internal combustion engine. An exhaust gas recirculation passage (3) is provided for feeding a portion of the exhaust gas of the exhaust passage into a cylinder of the engine such that a laminar distribution is produced in the cylinder formed by air/fuel mixture adjacent to the ignition plug and the recirculated exhaust gas distributed about the air/fuel mixture. The exhaust gas recirculation passage may open in the vicinity of an intake valve of the engine or open into the cylinder above the bottom dead center of the piston. The flow of recirculated exhaust gas may be controlled by pressure, for example by the inlet and exhaust valves of the engine and/or by a pressure control valve (31, 34).

Abstract: An engine control system corrects an air-fuel ratio of an air and fuel mixture during feedback control in a feedback region of engine operating conditions and during a learning control in a learning region of engine operating conditions. A purge region of engine operating conditions, in which purging of fuel vapor into the engine is conducted, is defined so as to have a portion overlapping with the learning control region. The air-fuel learning and the fuel vapor purging are conducted alternately. A specific region of engine operating conditions is defined in the purge region for higher flow rates of intake air. The control system undergoes the air-fuel learning prior to the fuel vapor purge when engine operating conditions are in this specific region.

Abstract: A control system (10) controls fuel injected into an internal combustion engine (14) having a fuel vapor recovery system (74) coupled to the air/fuel intake. To achieve stoichiometric combustion, delivery of liquid fuel is trimmed by a feedback variable (32) responsive to an exhaust gas oxygen sensor (26) and a learned value (40) representing quantity of recovered fuel vapor. Learning (40) is inhibited when an indication is provided of air/fuel operation rich of stoichiometry which is caused by factors other than vapor recovery.

Abstract: According to an air-fuel ratio control method, an amount of fuel supplied to an internal combustion engine is calculated by the use of an air-fuel ratio correction coefficient set according to an output from an exhaust gas ingredient concentration sensor. An average value of the air-fuel ratio correction coefficient is calculated. When a difference between an actual value of opening of an exhaust gas recirculation control valve and a desired value of same set in response to operating conditions of the engine is larger than a predetermined value, the calculation of the average value of the air-fuel ratio correction coefficient is inhibited, or alternatively, an averaging rate in the calculation of the average value is decreased.

Abstract: A fuel evaporative emission control system for an internal combustion engine using a gasoline-alcohol blend fuel. The system includes a canister for trapping fuel vapors to purge them into an air intake passage of the engine through a pipe. A valve is provided at the pipe for closing/opening the same to control purging of fuel vapors to the air intake passage. In the system, when the fuel property is found to be changed from alcohol concentration detected, the valve is opened if correction coefficient for air-fuel ratio determined from an oxygen content sensor's output is within a predetermined upper and lower limit, while the valve is closed if the coefficient falls outside the range, whereby preventing degradation of the exhaust gas properties, misfiring and the like.

Abstract: A control system (10) controls the induction of fuel injected into an internal combustion engine (14) to achieve stoichiometric combustion. The control system includes a feedback controller (32) which generates a feedback variable by integrating the output of an exhaust gas oxygen sensor (26). Integration is inhibited in response to an indication of a rich air/fuel offset.

Abstract: An evaporative fuel-purging control system for an internal combustion engine having a canister in which evaporative fuel from a fuel tank is absorped. Purge control valves are arranged between the canister and the intake system of the engine for controlling the flow rate of evaporative fuel supplied from the canister to the intake system. An ECU is responsive to an output from an exhaust gas ingredient concentration sensor arranged in the exhaust system of the engine for calculating an air-fuel ratio correction coefficient, based upon the output from the exhaust gas ingredient concentration sensor and controlling the air-fuel ratio of a mixture supplied to the engine by the use of the air-fuel ratio correction coefficient. The ECU calculates an average value of the air-fuel ratio correction coefficient, and is responsive to the calculated average value for controlling the purge control valves.

Abstract: A fuel supply control device including a purge control valve. The maximum purge rate, that is, the ratio between the amount of purge and the amount of intake air when the purge control valve is fully open, is stored in advance. The purge control valve is controlled in its duty ratio, which duty ratio is the target purge rate/maximum purge rate. When the purge is started, the target duty ratio is gradually increased. When the purge is performed and the feedback correction coefficient FAF falls, the feedback correction coefficient FAF is gradually returned to the FAF before the start of a purge, the purge A/F correction coefficient is increased, and the amount of injection is corrected by the sum of the purge A/F correction coefficient and the feedback correction coefficient.

Abstract: An air fuel ratio control apparatus for an engine equipped with an EGR device for refluxing a combustion gas from an exhaust pipe to an intake pipe and a fuel supply control device for controlling a fuel supply amount to the engine. The apparatus includes an air fuel ratio sensor for detecting an air fuel ratio of an air-fuel mixture to be introduced into said engine and an EGR rate sensor for detecting a reflux degree of the combustion gas to the intake pipe. In the apparatus a plurality of optimal feedback gains are set on the basis of a dynamic model of a system for controlling an air fuel ratio of an air-fuel mixture to the engine, and one of the plurality of set optimal feedback gains is selected in accordance with the reflex degree of the combustion gas detected by the EGR rate sensor.

Abstract: The invention is directed to a method of checking the tightness of a tank-venting apparatus for a motor vehicle having a fuel tank and an internal combustion engine including a lambda controller and an air intake pipe. The tank-venting apparatus includes an adsorption filter, a supply line interconnecting the adsorption filter and the fuel tank, a connecting line interconnecting the adsorption filter and the intake pipe and a tank-venting valve mounted in the connecting line between the adsorption filter and the intake pipe. The method includes the steps of: measuring the pressure difference between pressure in the tank and ambient pressure; when the tank-venting valve is opened, determining whether the pressure difference increases above a threshold value and whether a lean correction by the lambda controller is required; and, drawing the conclusion that the tank-venting apparatus leaks when neither a lean correction is determined nor the pressure difference exceeds the threshold value.

Abstract: A control apparatus for an internal combustion engine provided with a zeolite catalyst (6) capable of reducing NOx under oxidizing gas conditions includes an engine speed detecting sensor (11), an EGR control means (13), and an air-fuel ratio control means (16). The EGR control means (13) includes an EGR valve opening degree calculating means (15) for calculating an EGR valve opening degree based on air-fuel ratios which cause a current exhaust gas temperature to be in a predetermined temperature range at engine speeds lower than a predetermined engine speed and calculating an EGR valve opening degree which causes an amount of large molecular weight HC components in the exhaust gas to be more than a predetermined amount at engine speeds equal to or higher than the predetermined engine speed. The air-fuel ratio control means (16) includes an air-fuel ratio setting means (18) for setting a current air-fuel ratio to a lean air-fuel ratio calculated based on the EGR valve opening degree.

Abstract: A method of detecting abnormality in an internal combustion engine, which is applied to at least one of a catalyst system, an evaporative fuel-purging system, a fuel supply system, an air-fuel ratio sensor, and an ignition system, for performing detection of abnormality therein according to operating parameters of the engine. An amount of residual fuel in the fuel tank is detected and the amount of residual fuel is compared with a predetermined value. The abnormality detection is inhibited when, as a result of the comparison, the amount of residual fuel is below the predetermined value.

Abstract: An air-fuel ratio feedback control method for a multi-fuel internal combustion engine using a dual O.sub.2 sensor system is provided, in which the concentration of oxygen in exhaust gas on the upstream side of an exhaust gas purifier is detected, a value corresponding to the detected oxygen concentration is compared with a first target value, and the air-fuel ratio is feedback-controlled in accordance with the result of the comparison. The mixture ratio of at least two fuels is detected, and a second target value is set in accordance with the detected fuel mixture ratio. On the other hand, the concentration of oxygen in the exhaust gas on the downstream side of the exhaust gas purifier is detected, and a value corresponding to the detected downstream-side oxygen concentration is obtained. The first target value is corrected in accordance with the difference between the obtained value and the second target value.

Abstract: An internal combustion engine air-fuel ratio control method and apparatus wherein a most favorable parameter selected from the group consisting of air, fuel, and recirculated exhaust gas is adjusted in response to detected deviation of the air-fuel ratio away from the desired ratio. Supplemental control is provided by means of the remaining parameters in the event that the most favorable parameter runs out of authority.

Abstract: An evaporative fuel control apparatus of an internal combustion engine is provided with a purge correction prohibition part. The apparatus includes a detection part for detecting operating conditions of the internal combustion engine and for supplying signals indicative of the operating conditions, a purge control valve for controlling a flow of fuel vapor to an intake passage of the engine, a calculation part for calculating a fuel injection amount in response to the signals, and a fuel injection control part for varying a feedback correction factor of an air-fuel ratio in response to the signals so as to maintain the air-fuel ratio at a stoichiometric value and for correcting the fuel injection amount on the basis of the feedback correction factor.

Abstract: An evaporative fuel control apparatus of an internal combustion engine for controlling a purge correction amount and a fuel injection amount in response to a concentration of fuel vapor in intake mixture. The apparatus includes a detection part for detecting operating conditions of the engine and for supplying signals indicative of the operating conditions, a purge valve for controlling a flow of fuel vapor from a fuel tank to an intake passage, and a calculation part for calculating the fuel injection amount in response to the signals.

Abstract: A tank ventilation system for an internal combustion engine includes a lambda control device and an intake section communicating with the engine; a throttle valve in the intake section and air flow rate meter in the intake section for determining a flow rate of air aspirated by the engine; a tank communicating with a reservoir for holding fuel vapors; a scavenging line communicating between the reservoir and the intake section downstream of the throttle valve to be scavenged by means of a scavenging air mass; a tank ventilation valve in the scavenging line for controlling the scavenging air mass; a control unit for triggering the tank ventilation valve during a scavenging event in given operating states of the engine; and a delivery line communicating between the reservoir and the intake section between the throttle valve and the air flow rate meter for delivering the scavenging air mass to the reservoir.