Abstract: An exhaust gas recirculation (EGR) system for an engine and a method of operating that system is disclosed. The system has a conduit arrangement for conducting exhaust gas from an exhaust side of the engine to an intake side of the engine, a valve arrangement configured for controlling the amount of exhaust gas to be recirculated and a conduit arrangement for providing intake air to the intake side of the engine. A sensor arrangement is provided and is configured to sense at least one parameter indicative of the humidity of the recirculated exhaust gas and the intake air at the intake side of the engine. A control arrangement is configured to receive a signal from the first sensor arrangement and further is configured to control the valve arrangement in response to a determination by the control arrangement that the first parameter is outside a desired range for low-NOx emission during a subsequent combustion period.

Abstract: When an abnormality determining process is cancelled when a fuel cut is stopped, an EGR valve (33), which is open wider than normal from the process, is returned to its original opening amount (i.e., fully closed), and fuel injection in an engine (1) is resumed. However, during execution of the abnormality determining process, an EGR passage (32) is full of air. Also, when the EGR valve (33) is returned to the fully closed state, there is a response delay in the change in the flowrate of air that flows from the EGR passage (32) into the air passage (4) following that return, such that excess air flows into the air passage (4). As a result, the intake air amount of the engine (1) becomes excessive for the fuel injection quantity after fuel injection resumes. The fuel injection quantity is thus increase corrected to inhibit this from happening.

Abstract: An internal combustion engine is selectively operative in a spark ignition combustion mode and a controlled auto-ignition combustion mode. An EGR valve operative to control flow of exhaust gas to an intake manifold is monitored, including commanding the EGR valve to a closed position and monitoring operation of the internal combustion engine. An intake manifold pressure due to a fresh air charge is estimated based upon the operation of the engine. The intake manifold pressure is measured, and the estimated intake manifold pressure is compared to the measured intake manifold pressure.

Abstract: Various systems and methods are described for controlling an engine in a vehicle which includes an exhaust passage and an exhaust gas recirculation system. One example method comprises adjusting an engine operating parameter based on an exhaust gas recirculation amount, the exhaust gas recirculation amount based on a first humidity and a second humidity, the first humidity generated from a first humidity sensor at a first location and the second humidity generated from a second humidity sensor located in the exhaust passage of the engine.

Abstract: A forced air induction system for an internal combustion engine (1) has: a forced air induction device; an EGR valve (10) provided in an EGR passage (9) connecting an intake air passage (14) and an exhaust gas passage (6); and a diagnosis device (20) adapted to execute an abnormality diagnosis for the forced air induction device based on a deviation of the actual boost pressure at the forced air induction device from a target boost pressure. The diagnosis device inhibits execution of the abnormality diagnosis when the operation state of the EGR valve is out of a normal operation range specifically determined.

Abstract: In an abnormal condition detecting system, an electronic control unit determines that a condition for carrying out a process for detecting an abnormal condition of an electric motor and/or electric supply lines for the motor is satisfied, when a position of a control valve is at its initial closed position. Then, the electronic control unit stops supply of the electrical power to the electric motor, to start a detection of the abnormal condition (electrical disconnection) in the motor and/or the electric supply lines.

Abstract: An EGR system includes a high-pressure EGR unit and a low-pressure EGR unit. During the steady operation of an internal combustion engine, the high-pressure EGR gas and the low-pressure EGR gas are mixed with each other at a mixture ratio, in which the ratio of the high-pressure EGR gas amount to the entire EGR gas amount is higher than that in a known mixture ratio, and then recirculated back to the internal combustion engine. In the engine speed-up transitional operation period, the opening amount of a high-pressure EGR valve is adjusted to the opening amount that is much smaller than the target opening amount corresponding to the target operation mode. Thus, it is possible to suppress occurrence of the situation where the entire EGR gas amount is excessive in the period in which the low-pressure EGR gas amount does not decrease by a sufficient amount.

Abstract: When the opening angle of an intake control valve is limited to a given opening angle by fuel cut, an EGR apparatus is activated, and a malfunction of the EGR apparatus is diagnosed on the basis of a change in intake manifold pressure before and after the activation of the EGR apparatus. When the control for reducing the intake-manifold negative pressure is not implemented, the change of the intake manifold pressure is corrected with a changing amount of first reference intake pressure (P(Ne)) changed by engine speed Ne. When the control for reducing the intake manifold genitive pressure is implemented, the change of the intake manifold pressure is corrected with a changing amount of second reference intake pressure (PL(Ne)) changed by engine speed Ne.

Abstract: A fluid conveyance apparatus having more than one particulate matter sensing probe situated at two or more locations on the apparatus. Signals from the probes from at least two locations may indicate particulate matter flowing within a fluid through the conveyance apparatus. The times between signals may be indicated the rate of movement of the particulate matter in the conveyance apparatus and also a flow rate and direction of the fluid. The sensing probe signals may be processed into control signals that may go to a flow control mechanism. An example application of the flow control mechanism may be for an exhaust gas recirculation system of an engine.

Abstract: An abnormality determination device for an EGR device, which is capable of determining the abnormality of the EGR device properly without interrupting the EGR operation. An ECU of an internal combustion engine detects an amount of fresh air drawn into a combustion chamber of the engine, carries out feedback control of the fresh air amount such that the detected fresh air amount converges to a predetermined target fresh air amount by controlling an opening of a throttle valve disposed in an intake system of the engine during execution of EGR by the EGR device. The ECU obtains a decreasing degree parameter which represent a degree of decrease in the fresh air amount caused by the feedback control, and determines abnormality of the EGR device based on the obtained decreasing degree parameter.

Abstract: A method for regenerating a diesel particulate filter (20) in the exhaust system (16) of an engine (12). When a request to regenerate the device is issued, a control system (14) operates the engine to begin conditioning exhaust. The conditioning process comprises a warming phase that occurs prior to initiation of regeneration and a heating phase during which regeneration can occur. During the process, data related to the warming phase and the heating phase is evaluated. The engine is operated to terminate the process prior to having reduced the amount of trapped particulate matter to a target amount when evaluation of the data discloses that the process should be terminated.

Abstract: A method for regenerating a diesel particulate filter (20) in the exhaust system (16) of an engine (12). When a request to regenerate the device is issued, a control system (14) operates the engine to begin conditioning exhaust. The conditioning process comprises a warming phase that occurs prior to initiation of regeneration and a heating phase during which regeneration can occur. During the process, data related to the warming phase and the heating phase is evaluated. The engine is operated to terminate the process prior to having reduced the amount of trapped particulate matter to a target amount when evaluation of the data discloses that the process should be terminated.

Abstract: A cooling system comprises a cooler with a hot-side passage extending between hot-side inlet and outlets. The cooler further includes a cooling passage extending between cold-side inlet and outlets. A cooling medium is disposed within the cooling passage, and is in contact with the hot-side passage to reduce the temperature of the gas or liquid passing through the hot-side passage. The cooling system is configured to regulate the condition of the cooling medium within the cooler to reduce/eliminate unwanted boiling of the cooling medium being within the cooler. The cooling system can include controller that provides an output signal in response to a detected condition of the cooling medium, and a device that receives the output signal and changes the operation of the cooling system and/or operation of an internal combustion engine to reduce the occurrence of unwanted cooling medium boiling within the cooler.

Abstract: When the opening angle of an intake control valve is limited to a given opening angle by fuel cut, an EGR apparatus is activated, and a malfunction of the EGR apparatus is diagnosed on the basis of a change in intake manifold pressure before and after the activation of the EGR apparatus. When the control for reducing the intake-manifold negative pressure is not implemented, the change of the intake manifold pressure is corrected with a changing amount of first reference intake pressure (P(Ne)) changed by engine speed Ne. When the control for reducing the intake manifold genitive pressure is implemented, the change of the intake manifold pressure is corrected with a changing amount of second reference intake pressure (PL(Ne)) changed by engine speed Ne.

Abstract: The present invention prevents an EGR sensor installed in an engine's EGR path from being soiled by soiling substances in exhaust. A catalyst is positioned upstream of the EGR sensor to purify the soiling substances in EGR gas. The status of the EGR sensor is properly controlled in accordance with the conditions of the catalyst. This ensures the EGR sensor is less likely to be affected by the soiling substances in the exhaust under any circumstances of the EGR path and allows the EGR sensor to avoid a decrease in the accuracy of EGR gas detection. An alternative configuration may be employed such that the EGR gas recirculates from the downstream side of a catalyst installed in a main exhaust path.

Abstract: An EGR failure determination system for an internal combustion engine, which is capable of accurately determining failures of both an external EGR device and an internal EGR device, irrespective of whether the EGR amount is large or small, thereby making it possible to enhance marketability of the system. The EGR failure determination system includes an ECU. The ECU calculates an actual fresh air ratio, and sets a target value thereof. Further, it calculates a feedback correction coefficient according to the actual fresh air ratio and the target value, and controls an exhaust recirculation mechanism and three variable mechanism. When the feedback correction coefficient is not within a predetermined range, and if it is larger than 0.5, at least one of the three variable mechanism is determined to be faulty, whereas if it is not larger than 0.5, the exhaust recirculation mechanism is determined to be faulty.

Abstract: An ECU calculates a foreign-matter accumulation index base on a total flow rate of EGR gas integrated since the previous execution of a last foreign-matter removal operation until the present execution of the foreign-matter removal operation. The ECU controls an actuator for operating an EGR valve and a number of the actuations of the EGR valve on the basis of the foreign-matter accumulation index. When the total flow rate of the EGR gas increases, the quantity of foreign matters contained in EGR gas correspondingly increases. Therefore, as the foreign-matter accumulation index becomes larger, the actuation intensity of the EGR valve is set higher and the number of the actuations of the EGR valve is set larger. As a result, the removal operation of foreign matters can be efficiently executed in accordance with the deposition intensity or the deposition quantity of foreign matters.

Abstract: An engine control system that having an exhaust gas recirculation (EGR) valve includes a first module that determines an EGR error and a second module that calculates a fuel injection timing based on the EGR error. Operation of an engine is regulated based on the fuel injection timing to reduce emissions during transient operation of the engine.

Abstract: A system and method for utilizing a humidity sensor with an internal combustion engine of a vehicle is described. Specifically, information from the humidity sensor is used to adjust a desired air-fuel ratio to reduce engine misfire while improving vehicle fuel economy. Further, such information is also used to adjust timing and/or lift of the valve in the engine cylinder. Finally, diagnostic routines are also described.

Abstract: A controller (70) controls the boost pressure of an internal combustion engine (60) comprising two intake/exhaust units, each intake/exhaust unit comprising a turbocharger (10) which supercharges intake air in an intake passage (20) using exhaust energy in an exhaust passage (30), and an exhaust gas recirculating device (40, 41) which recirculates a part of the exhaust gas in the exhaust passage to the intake passage. The controller (70) calculates an opening difference between valves in the two units (S121), and controls a regulating device (13) in each of the two units on the basis of this opening difference (S123-S125). As a result, the boost pressures of the turbochargers (10) match, and hence an equal amount of NOx can be discharged from each exhaust passage (30), and the NOx can be purified favorably by a catalyst.

Abstract: A control apparatus for an internal combustion engine can compensate for a variation of intake pressure resulting from various factors whereby a failure detection area can be expanded, and false detection can be prevented to enable failure determination for an EGR system with high reliability. The apparatus determines whether a vehicle is decelerating, forcedly opens and closes an EGR valve, and determines whether an EGR control device is in failure by comparing a pressure change index value based on intake pressures upon the forced opening and closing of the EGR valve with a failure determination value. The apparatus adjusts the intake pressure to a predetermined state before the EGR valve is forcedly opened and closed, whereby a failure determination can be always made based on the intake pressure whose variation was compensated for with the intake pressure becoming a predetermined characteristic to the number of revolutions per minute of the engine.

Abstract: An exhaust gas recirculation passage connects an exhaust passage with an intake passage. A cooling device is mounted to the exhaust gas recirculation passage for cooling exhaust gas in the exhaust gas recirculation passage. An EGR valve adjusts a flow passage area of the exhaust gas recirculation passage. An exhaust gas quantity (EGR quantity) in the exhaust gas recirculation passage is feedback-controlled by manipulating an opening degree of the EGR valve based on a measurement value of an airflow meter. Existence or nonexistence of an abnormality in the cooling device is diagnosed based on whether a measurement value of the opening degree of the EGR valve contains a component corresponding to compensation for reduction of the EGR quantity due to degradation of cooling performance of the cooling device.

Abstract: A method for operating an internal combustion engine is provided. By taking into account a setpoint temperature Tsetpoint of the internal combustion engine which depends on external and internal boundary conditions when controlling and/or regulating temperature-dependent functions of the internal combustion engine, fuel consumption and emission characteristics of the internal combustion engine are improved.

Abstract: An exhaust gas recirculation control device in a diesel engine, capable of suppressing NOx and smoke discharged. A first temperature sensor (11) is provided at a portion more on the upstream side than a portion where a suction air path (3) joins an exhaust gas recirculation path (4), and a second temperature sensor (12) is provided on the downstream side. Further, an engine load detection sensor (6) and an engine speed detection sensor (7) are arranged. The exhaust gas recirculation control device also has memory means where the temperature of suction air before it is mixed with an exhaust gas and a temperature value at a second temperature sensor installation position are previously memorized, the temperature value corresponding to an appropriate exhaust gas recirculation amount that is uniquely defined by an engine load and an engine speed. Further, judging means is provided.

Abstract: A method and a device for operating an internal combustion engine having exhaust-gas recirculation are provided, which make it possible to dispense with an ambient-pressure sensor. In this context, an intake-manifold pressure and an ambient pressure are modeled. The intake-manifold pressure is modeled as a function of the modeled ambient pressure. The intake-manifold pressure is also measured. The modeled intake-manifold pressure is compared to the measured intake-manifold pressure. The modeled ambient pressure is adapted as a function of the comparison result. The modeled ambient pressure is adapted only when the exhaust-gas recirculation is inactive.

Abstract: A system for controlling the air-to-fuel ratio in an internal combustion engine includes an air intake conduit coupled to an intake manifold, an EGR valve disposed in-line with an EGR conduit responsive to a valve control signal, a lambda sensor producing a lambda signal indicative of the air-to-fuel ratio of the exhaust gas and a control circuit producing the valve control signal as a function of a desired mass air flow value, a desired air-to-fuel ratio, and the lambda signal. In an alternate embodiment, the system further includes a fueling system responsive to a fueling control signal. In this embodiment, the control circuit produces the fueling control signal as a function of a desired fuel control value, a desired air-to-fuel ratio, and the lambda signal. In another alternate embodiment, the control circuit produces the valve control signal as a function of a desired air-to-fuel ratio and the lambda signal.

Abstract: A method of operating an internal combustion engine having an; electromagnetically driven intake valves for a vehicle. With the method, deviation of an opening operation of the electromagnetically driven intake valve in response to a command signal for opening the intake valve from a predetermined characteristic is detected, and at least one of parameters used for controlling operation of the internal combustion engine is corrected so as to reduce a change in an intake air charging state in which the internal combustion engine is charge with the intake air. A valve closing timing of the intake valve or a valve closing timing of the exhaust valve that cooperates with the intake valve may be used as parameters to be corrected.

Abstract: A failure diagnostic device for an exhaust gas recirculation (EGR) apparatus, which can detect an intake pipe pressure at a high accuracy with a simple control and can prevent false diagnosis of an EGR system. If at least either one of first and second off-mode intake pipe pressures P1off, P2off exceeds a cancel determination value K, an ECU determines that the intake pipe pressures P1off, Pon and P2off are not properly detected, and cancels the failure diagnosis of the EGR system. Therefore, the false diagnosis of the EGR system can be avoided with a simplified process without requiring specific determinations on individual abnormal states of the various components other than the EGR system. By setting the cancel determination value K based on the intake pipe pressure P resulting when EGR off-control is executed in a state of an EGR valve being stuck in a fully-open position, each improperly-detected intake pipe pressure can be excluded with reliability.

Abstract: A method of estimating oxygen concentration in the intake of a lean burn engine is accomplished during throttled operation by repeatedly combining determined air/fuel ratio and intake mass air flow and estimated cylinder mass flow and exhaust gas recirculation flow in a state observer, which calculates exhaust and intake burned gas fractions and resulting percent oxygen in the intake manifold. During unthrottled operation, estimation is corrected by an adaptive disturbance estimator, which operates to correct all input disturbances under conditions of higher EGR and to correct only MAF flow values under lower EGR conditions. Steps for operation of the state observer and for determining or estimating input conditions to the state observer are set forth.

Abstract: An engine ECU of a failure diagnosis system for an EGR device starts the EGR device by opening an EGR valve upon establishment of monitor conditions, detects an actual intake pipe pressure PMON based on a value of a vacuum sensor upon elapse of a predetermine time, calculates an estimated intake pipe pressure PMON using a physical model, cuts the EGR operation by changing the opened state to the closed state of the EGR valve, detects an actual PMOFF based on an input value of the vacuum sensor upon elapse of a predetermined time from cut of EGR, calculates an estimated PMOFF using the physical model, and determines the operation of the EGR device as being normal when a result of comparing a difference between the estimated PMON and estimated PMOFF with a difference between the actual PMON and actual PMOFF is smaller than a predetermined value.

Abstract: A method for diagnosing the operating condition of an internal combustion engine exhaust gas recycling valve. The method acquires a measurement value of a reference position of the recycling valve at a predetermined time corresponding to a normally closed position of the valve, calculates the difference between the acquired reference value and a reference value acquired during a diagnostic cycle previously carried out, and compares the calculated difference with a threshold value for detecting opening of the valve.

Abstract: A control system for an internal combustion engine is disclosed. The engine has an exhaust gas recirculation device which includes an exhaust gas recirculation passage for recirculating exhaust gases from the engine to an intake system of the engine, and an exhaust gas recirculation control valve provided in the exhaust gas recirculation passage, for controlling a flow rate of the exhaust gases. An air-fuel ratio control amount is calculated based on an output of the air-fuel ratio sensor provided in the exhaust system of the engine. The air-fuel ratio of the air-fuel mixture supplied to the engine is controlled with the air-fuel ratio control amount. A failure of the exhaust gas recirculation device is determined based on a changing component of the air-fuel ratio control amount when changing an opening of the exhaust gas recirculation control valve in a predetermined cycle.

Abstract: A method and device for operating an internal combustion engine, which diagnose and/or adapt the exhaust-gas recirculation system for, in particular, multibranch internal combustion engines. In this context, the internal combustion engine includes at least one adsorption catalyst in at least one exhaust branch. In addition, at least one exhaust-gas recirculation duct is provided, which is equipped with an exhaust-gas recirculation valve and feeds exhaust gas from the at least one exhaust branch back into at least one air-supply duct, a level of pollutant stored in the at least one adsorption catalyst being ascertained in a first operating state of the internal combustion engine when the exhaust-gas recirculation valve is at least partially open, so that a first value for the pollutant level is produced. In a second operating state of the internal combustion engine, a second value for the pollutant level in the at least one adsorption catalyst is ascertained when exhaust-gas recirculation valve is closed.

Abstract: An engine ECU of a failure diagnosis system for an EGR device fixes a VVT to a most retarded position upon establishment of a failure monitor condition of the EGR device, starts the EGR device, measures an actual intake pipe pressure PMON upon elapse of a predetermined time after start of EGR device, stops the EGR device, measures an actual intake pipe pressure PMOFF upon elapse of a predetermined time after stop of EGR device, and determines that the EGR device is normally operated when a value obtained by subtracting the actual PMOFF in OFF state of the EGR device from the actual PMON in ON state of the EGR device is larger than a predetermined judgment value.

Abstract: In a case where an oscillation frequency per unit time of a first feedback amount of supercharging pressure (VNT) control exceeds a judgment value, or in a case where an oscillation frequency per unit time of a second feedback amount of exhaust gas recirculation (EGR) control exceeds a judgment value, it is determined that a target VNT opening degree or a target EGR opening degree is in a hunting state. In the case where the hunting of the target VNT opening degree or the target EGR opening degree is detected, a first or a second gain correction coefficient multiplied to the first or the second feedback amount is changed to a value to decrease an absolute value of the first or the second feedback amount.

Abstract: An EGR-gas temperature estimation apparatus for an internal combustion engine which has an exhaust circulation pipe and an EGR-gas cooling apparatus. The estimation apparatus obtains the cooling efficiency ?egr of the EGR-gas cooling apparatus from the temperature Tex of EGR gas at the inlet of the exhaust circulation pipe and the flow rate Gegr of the EGR gas, and obtains the temperature THW of engine cooling water, used as a coolant for the EGR-gas cooling apparatus. Subsequently, the estimation apparatus calculates the temperature Tegr of the EGR gas at the outlet of the exhaust circulation pipe by the expression Tegr=Tex??egr·(Tex?THW). Since the cooling efficiency ?egr greatly changes depending on the EGR-gas flow rate Gegr and the EGR-gas temperature Tex, the estimation apparatus can accurately estimate the cooling efficiency ?egr, and therefore can accurately estimate the EGR-gas temperature Tegr.

Abstract: Cylinders of a diesel engine 1 are provided with cylinder pressure sensors 29a to 29d for detecting combustion chamber pressures. An electronic control unit (ECU) 20 of the engine selects optimum combustion parameters in accordance with a fuel injection mode of fuel injectors 10a to 10d of the engine and a combustion mode determined by the amount of EGR gas supplied from the EGR valve 35 from among a plurality of types of combustion parameters expressing the combustion state of the engine calculated based on the cylinder pressure sensor output and feedback controls the fuel injection amount and fuel injection timing so that the values of the combustion parameters match target values determined in accordance with the engine operating conditions. Due to this, the engine combustion state is controlled to the optimum state at all times regardless of the fuel injection mode or combustion mode.

Abstract: A potentiometer device, for detecting valve positions, wherein a voltage signal Us is sendable to a control unit having an A/D converter, including a carrier element on which at least one slider track, having a slider element in contact therewith, is disposed; wherein the slider track switches between supply voltage Uv of the control unit and ground, and the slider element is connected with the control unit with a protection resistance over an output, wherein the control unit includes a resistance for detecting a cable disconnect, which is a pull-down resistance between voltage signal Us and ground, or a pull-up resistance between supply voltage Uv and voltage signal Us, wherein a resistance is provided at output, that is, in a first embodiment, a pull-up resistance between supply voltage Uv and voltage signal Us, and, in a second embodiment, a pull-down resistance between voltage signal Us and ground.

Abstract: A method is described for detecting exhaust pressure buildup in an engine's exhaust system using information from an exhaust gas recirculation system having a valve.

Abstract: An engine exhaust gas cleaning apparatus is provided to suppress EGR ratio fluctuations when the excess air ratio is adjusted and thereby stabilize the engine operating performance.

Abstract: An apparatus and method to detect abnormal combustion conditions for use as a feedback control of an EGR (Exhaust Gas Recirculation) controlled reciprocating engine using ionization signals is presented. The system receives a succession of ionization signals for successive cycles of a running engine and processes a plurality of related ionization signals for signal stability. The ionization signals are checked to determine if an abnormal combustion condition such as knock or misfire has occurred. The variation of an ionization signal that changes with respect to an engine parameter over a combustion event of the reciprocating engine is measured and a floating bounded space is associated with the ionization signal. An indication that the abnormal combustion condition has been detected is provided if a portion of the ionization signal is within the floating bounded space.

Abstract: A vehicle system controls a compression ignition internal combustion engine equipped with a supercharger system including a plurality of superchargers. The compression ignition internal combustion engine has an exhaust gas recirculation (EGR) system. The vehicle system determines a desired intake manifold supercharging state (tQac) and a desired EGR rate (Megr). The vehicle system includes control logics, each having a first input parameter and a second input parameter, for determining desired set points (Rvnt1 & Rvnt2) for the plurality of superchargers, respectively. The desired set points are used to control the plurality of superchargers, respectively. The vehicle system also includes control logic for determining the first input parameters in response to the desired intake manifold supercharging state. The vehicle system further includes control logic for determining the second input parameters in response to the desired EGR rate.

Abstract: A vehicle control system regulates oxides of nitrogen levels in vehicle emissions. Recirculation of exhaust gas in an engine is controlled with an exhaust gas regulator valve and/or a cam phaser. An oxides of nitrogen sensor determines the level of oxides of nitrogen levels in the exhaust gas and communicates the information to a vehicle controller. The controller determines if the oxides of nitrogen levels are within a predetermined threshold according to a lookup table. The controller adjusts the valve and/or cam phaser if the oxides of nitrogen levels are not within the threshold.

Abstract: A method and an apparatus for estimating an amount of drawn air of a cylinder and a method and an apparatus for controlling the amount of drawn air, are presented. An estimated value of an amount of drawn air of the cylinder, based on intake manifold pressure, is multiplied by a value of an identification parameter obtained by an adaptive observer, to obtain a final estimated value of an amount of drawn air of the cylinder. An accurate estimated value in a transient state as well as an estimated value not oscillating in a steady state can be obtained. Accordingly, accuracy of air-fuel ratio control can be remarkably increased.

Abstract: A control method of an EGR system of an engine capable of effectively performing an EGR control at a time of rapid acceleration. For this purpose, an intake air flow rate of the engine is obtained, and from a target EGR valve opening degree and a difference in pressure in front of and behind the EGR valve, a virtual EGR gas flow rate is arithmetically operated. A virtual EGR rate is obtained from the intake air flow rate, the fuel flow rate and the virtual EGR gas flow rate, and a difference from or a ratio to a target EGR rate obtained from the engine speed and the fuel flow rate is obtained. A command EGR valve opening degree is obtained from an EGR valve opening degree correction coefficient obtained from the difference or the ratio, and the target EGR valve opening degree, whereby the EGR vale is driven.

Abstract: A system is disclosed for diagnosing operation of an EGR cooler disposed in-line with an EGR conduit fluidly coupled between an intake manifold and an exhaust manifold of the engine such that exhaust gas flowing through the EGR conduit also flows through the EGR cooler. The EGR cooler is coupled to an engine cooling system such that coolant fluid circulating through the engine also circulates through the EGR cooler. Means are provided for determining a temperature of exhaust gas produced by the engine, a temperature of exhaust gas exiting the EGR cooler, a temperature of the coolant fluid and a flow rate of exhaust gas through the EGR conduit. A control computer is configured to diagnose operation the EGR cooler as a function of the temperature of exhaust gas produced by the engine, the EGR cooler outlet temperature, the engine coolant temperature and the EGR flow rate.

Abstract: A method for determining EGR flow in an internal combustion engine, such flow being from an exhaust manifold of the engine to an intake manifold of the engine through an EGR valve. The method includes using information provided by a mass air flow sensor disposed upstream of an exhaust gas inlet to the intake manifold and information provided by an manifold absolute pressure sensor disposed downstream of such exhaust gas inlet to provide an indication of the flow of exhaust gas into the intake manifold through such inlet. The method compares such estimated exhaust gas flow into the intake manifold with a commanded exhaust gas flow to the EGR valve. With such method, a determination may be made as to whether the EGR valve is operating properly.

Abstract: A system is described for determining degradation of an exhaust gas recirculation system of an internal combustion engine. This method utilizes a combination of parameters to accurately determine degradation of the exhaust gas recirculation system. For example, the system utilizes changes in intake manifold pressure, changes in idle speed control operation, changes in ignition timing, and fueling changes to accurately determine operation of the exhaust gas recirculation system.

Abstract: A failure detection apparatus for an internal combustion engine includes failure detecting means (S22-S30) for detecting abnormality of fresh air quantity detecting means (air flow sensor) based on the result of comparison between a fresh air quantity detected by the fresh air quantity detecting means (air flow sensor) and a reference value for the fresh air quantity set by fresh air quantity reference value setting means (S20), and an EGR device (EGR passage, EGR valve, target opening setting means, EGR valve control means). The fresh air quantity reference value setting means sets the reference value (S16) in accordance with not only the operating state (engine speed Ne, fuel injection quantity Qf, etc.) of the engine but also a target EGR valve opening set by target opening setting means (S12, S14).

Abstract: An EGR fault/failure determination system for an internal combustion engine is operable to monitor a number of EGR system operational parameters and diagnose various EGR-related fault and failure statuses therefrom. For example, the system is operable to determine a number of EGR system-related fault and failure conditions by monitoring measured and command EGR position signals to determine EGR valve controller functionality, to monitor response times between fully open and closed EGR valve positions by comparing measured response times to a calibratable response time value, and to monitor in-range EGR position failures associated with fully closed and fully opened EGR valve position values. The system further includes a Kalman filter-based fault/failure isolation feature operable to isolate and identify one or more sources of EGR valve-related faults/failures.