Abstract: A flow rate of gas supplied to a diesel particulate filter is increased when it is determined that rapid combustion of collected particulates, which are collected by the particulate filter, is likely to occur based on an operating state of an internal combustion engine. Alternatively, the flow rate of gas supplied to the filter is increased when it is determined that rapid combustion of the collected particulates is initiated based on a state of the particulate filter.

Abstract: An exhaust gas recirculation (EGR) system of an internal combustion engine has an EGR cooler in an EGR passage connecting an exhaust manifold with an intake manifold. The EGR cooler cools EGR gas recirculated through the EGR passage. Cooling performance detecting means included in an electronic control unit (ECU) determines that cooling performance of the EGR cooler is degraded when intake pressure measured by an intake pressure sensor is lower than a normal intake pressure by at least a predetermined value. When the degradation of the cooling performance is detected, cooling performance regeneration controlling means included in the ECU increases the temperature inside the EGR cooler by heating the exhaust gas to eliminate soot or unburned hydrocarbon by oxidization. Thus, the cooling performance of the EGR cooler is regenerated.

Abstract: An engine control unit of an exhaust gas purification system of an internal combustion engine measures a pressure difference between an upstream and a downstream of a diesel particulate filter (DPF) after heating the DPF at least to a predetermined temperature and maintaining the DPF at the temperature for a while. The DPF is disposed in an exhaust pipe of the engine. A soluble organic fraction included in particulate matters in exhaust gas can be eliminated at the predetermined temperature. The ECU calculates a quantity of the particulate matters trapped by the DPF from the measured pressure difference. Thus, the quantity of the trapped particulate matters is calculated precisely, independently of a composition of the particulate matters or a state of the soluble organic fraction.

Abstract: Particulate material collected in a filter (PM) is burnt through a selected one of partial and perfect regenerating processes. The partial regenerating process starts, when an amount of PM is predicted to exceed a value between 2 to 10 g/l, and terminates, when the amount of PM is predicted to fall below a value between 1 to 4 g/l, whereby a part of PM is burned to an extent that incombustible ash contained in the filter (ASH) can not easily pass through the filter. The prefect regenerating process starts, when an amount of ASH is predicted to exceed a value between 0.05 to 0.25 g/l, and terminates, when the amount of PM is predicted to fall below 1 g/l, whereby a substantially entire part of PM is burnt to an extent that ASH can easily pass through the filter.

Abstract: The engine control system has an ECU that supplies relatively large amount of EGR gas and delays an injection timing in order to decrease temperature in a combustion chamber. When an engine is operated under a warming up operation or a low engine load, the ECU deactivates an EGR cooler to increase intake air temperature in order to stabilize engine operation. When the engine is operated under a high engine load, the ECU activates the EGR cooler, delays a closing timing of an intake valve, and increases a boost pressure of a forced induction system. As a result, both of a compression end temperature and a maximum combustion temperature are decreased so that emissions of NOx and particulates are reduced.

Abstract: The engine control system has an ECU that supplies relatively large amount of EGR gas and delays an injection timing in order to decrease temperature in a combustion chamber. When an engine is operated under a warming up operation or a low engine load, the ECU deactivates an EGR cooler to increase intake air temperature in order to stabilize engine operation. When the engine is operated under a high engine load, the ECU activates the EGR cooler, delays a closing timing of an intake valve, and increases a boost pressure of a forced induction system. As a result, both of a compression end temperature and a maximum combustion temperature are decreased so that emissions of NOx and particulates are reduced.

Abstract: The permeability of a DPF 21 mounted on a diesel engine 1 is evaluated by calculating the apparent passage area (A) based upon a difference in the pressure between the upstream and the downstream sides of the DPF 21 and upon other engine data, an alarm is given to a driver based on the results of evaluation, and the operation mode is changed over to regenerate the DPF 21. An abnormal increase in the passage area caused by breakage is accurately detected, and it does not happen that the PM is released into the open air for extended periods of time due to the breakage of the DPF 21. Further, without the need of dismantling the DPF 21, the DPF 21 can be reliably burned and regenerated without being undesirably overheated in every operation mode of the engine 1.

Abstract: A heat generation amount qr/r per unit flow amount of combustible substances supplied to a catalyst is estimated based on upstream and downstream temperature information and supplemental engine information. A deteriorated condition of the catalyst is detected based on a judgement whether or not the estimated heat generation amount is smaller than a predetermined judging value D.

Abstract: An air-fuel ratio control system for an internal combustion engine utilizes a pre-stored standard relation between an air-fuel ratio sensor signal and a standard air-fuel ratio indicative value for deriving the standard air-fuel ratio indicative value based on the sensor signal. The system further utilizes a pre-stored modified relationship between the standard air-fuel ratio indicative value and a for-control air-fuel ratio indicative value for deriving a for-control air-fuel ratio indicative value based on the derived standard air-fuel ratio indicative value. In the modified relationship, the for-control air-fuel ratio indicative value varies with respect to a corresponding variation of the standard air-fuel ratio indicative value within a given range across the standard air-fuel ratio indicative value representing a stoichiometric air-fuel ratio.

Abstract: An air-fuel ratio control system for an internal combustion engine utilizes a pre-stored standard relation between an air-fuel ratio sensor signal and a standard air-fuel ratio indicative value for deriving the standard air-fuel ratio indicative value based on the sensor signal. The system further utilizes a pre-stored modified relationship between the standard air-fuel ratio indicative value and a for-control air-fuel ratio indicative value for deriving a for-control air-fuel ratio indicative value based on the derived standard air-fuel ratio indicative value. In the modified relationship, the for-control air-fuel ratio indicative value varies with respect to a corresponding variation of the standard air-fuel ratio indicative value within a given range across the standard air-fuel ratio indicative value representing a stoichiometric air-fuel ratio.

Abstract: A control apparatus for speedily warming up a catalyst disposed within an exhaust pipe connected to an internal combustion engine. The control apparatus calculates a demand fuel injection quantity into the engine on the basis of an operating state of said engine, and corrects the calculated demand fuel injection quantity on the basis of a warming-up state of a catalyst provided in an exhaust pipe of the engine so that an air fuel ratio in the engine is repeatedly controlled to a rich side and a lean side in a state that the warming-up of the catalyst is not completed. The control apparatus is equipped with an inhibiting function to inhibit the air fuel ratio from being controlled to the rich side and the lean side when the engine takes an operating state that the injection quantity is set to a rich side with respect to the theoretical air fuel ratio.

Abstract: A control apparatus for rapidly warming up a catalyst disposed within an exhaust pipe connected to an internal combustion engine. The control apparatus first determines a fuel injection amount and an ignition timing of the engine on the basis of an engine operating condition such as an intake air pressure of the engine and a rotational speed of the engine. The control apparatus is also responsive to temperature information of the catalyst for adjusting the fuel injection amount and the ignition timing in accordance with the catalyst temperature information. When the catalyst temperature does not reach the effective emission-purifying temperature, the control apparatus alternately adjusts the fuel injection amount to a rich amount and a lean amount and further intermittently retards the ignition timing. This injection and ignition control operation allows acceleration of the warming-up of the catalyst to suppress the deterioration of the emissions from the engine.

Abstract: An internal combustion engine control device is constructed to estimate an engine air intake quantity based on an engine speed when the engine is running in an intake air pulsation generating range to control the engine in accordance with the air intake quantity thus estimated. The estimated air intake quantity is corrected by a correction value which is related to the density of the intake air.

Abstract: An air-fuel ratio control system realized with a computer for an internal combustion engine is disclosed, wherein an idle discriminator unit discriminates whether the internal combustion engine is idle or not, and when it is idle, an idle air-fuel ratio compensation amount determining unit decides an air-fuel ratio compensation amount in accordance with an output of an air-fuel ratio detector. When the engine is not idle, on the other hand, a non-idle air-fuel ratio compensation amount determining unit decides an air-fuel ratio compensation amount.

Abstract: A system for controlling the operating condition of an engine in which a temperature sensing element constitutes an airflow measuring device disposed in an intake air passage of the engine. The temperature sensing element is supplied with a heating current in response to a start pulse signal produced with every one-half period of each combustion cycle of the engine. A comparator delivers an output signal when a reference temperature set on the basis of the air temperature measured by an auxiliary temperature sensing element is reached by the temperature of the temperature sensing element. A pulse signal indicative of the time interval between the generation of the start pulse signal and a rise in the output signal of the comparator is delivered as an airflow measurement signal.

Abstract: An engine control apparatus for controlling the quantity of fuel injected into the engine is equipped with an intake air flow rate measuring device for detecting the operating state of the engine. This measuring device has a heat sensitive element, which is located in the intake pipe, and outputs a pulse signal having a pulse width T corresponding to the intake fuel amount. Engine control apparatus has a plurality of map memory means in which a plurality of functions f.sub.1 (N), f.sub.2 (N), f.sub.3 (N), which express the polynomial approximation ##EQU1## for expressing the air flow rate G/N per engine revolution, are stored as the parameters of the number of engine rotations N. These functions are read out from the maps and, based on the number of engine rotations N, the fuel injection amount corresponding to the pulse width T of the air flow rate is calculated.

Abstract: A control system for an engine has a temperature sensitive element as part of a device for measuring the air flow in an air intake manifold to the engine. Further, a first pulse signal is generated, corresponding to the rotation of the engine, for controlling the setting of a flip-flop. A transistor is conducted in the set state of the flip-flop to supply a heating electric current to the element. The element supplied with the current is raised to the temperature that corresponds to the air flow in the manifold. When the temperature of the element is raised until the specified temperature difference to the air temperature (measured by a sub temperature sensitive element) is set, the temperature difference is detected by a comparator, and the flip-flop is reset by the detection signal.

Abstract: In an apparatus for controlling an engine, as an air flow sensor for measuring intake air flow quantity, a heater resistor having temperature-resistance characteristic and a temperature sensitive resistor for sensing air temperature are provided in an intake passage, and heating electric power is supplied to the heater resistor in response to a start signal generated periodically. The heating electric power is cut off when the temperature of the heater resistor is raised to a specified reference temperature predetermined in accordance with the air temperature, so that an output signal indicative of the time width in which the heating electric power is supplied is applied to an electronic control unit to measure air flow quantity therefrom.

Abstract: A heater, which comprises an element whose resistance varies with changes in temperature, and a temperature element are provided in the air intake pipe of an engine. This heater and temperature element together with resistors form a bridge circuit to which heating power is supplied via a transistor. An engine control unit generates start signals Tin simultaneously with the rotation of the engine. A flip-flop circuit is set by these start signals and, when set, the transistor is turned on and the heating power rises. The output signal from the bridge circuit is supplied to a comparator and the output signal of the comparator resets the flip-flop circuit, which outputs a pulse-shaped signal representing the airflow quantity as a length of time. This pulse-shaped time signal is sent via a constant current circuit to another comparator, where it is compared with a reference voltage and the output signal from the comparator is supplied together with the above time signal to an exclusive OR circuit.

Abstract: An engine control apparatus has an air flow rate measuring device for measuring an intake air flow rate. A temperature sensing element having a temperature characteristic and constituting the device is arranged in an intake pipe. The device generates an output pulse signal having a pulse width T corresponding to the intake air flow rate. An engine control unit has the one-dimensional map for storing the relationship between the engine speed N and the pulse width to of the signal corresponding to the air flow rate. This data to is read out from the one-dimensional map in accordance with the engine speed N. Subsequently, the data to is subtracted from the data T to calculate a time duration t. The unit also has a two-dimensional map for storing the relationship between each time duration t and the corresponding rate G/N in correspondence with each of the present engine speeds. A corresponding rate G/N is read out from the two-dimensional map in response to the calculated time duration t.