Abstract: If the amount of fuel added to exhaust gas becomes excessive as a result of an abnormality of an addition agent supply unit (60), the air-fuel ratio of exhaust as decreases. If an exhaust gas air-fuel ratio obtained from a value output from an A/F sensor (4) remains equal to or smaller than a predetermined value for a predetermined period, an ECU (2) determines that an addition agent supply unit (60) is abnormal. Upon detection of an abnormality of the addition agent supply unit (60), the ECU (2) incrteases an amount of EGR gas recirculated to the intake side by an EGR unit (40), reduces an amount of fuel injection from injectors (11), and restricts an operational state of an engine body (10) to a low-speed/low-load state. Also, the ECU (2) turns a warning lamp (7) on, warns a driver of the abnormality of the addition agent supply unit (60), and makes it possible to pull a vehicle over safely.

Abstract: A compression ignition engine injects fuel through injection holes of an injector at a substantially constant injection rate to atomize the fuel so that the fuel can be easily vaporized and to make the fuel penetrate an atmosphere inside a cylinder. A spatial distribution of the injected fuel in which mixing of the fuel and air is promoted as the fuel recedes from the injection hole and the fuel reaches a premixing space where the fuel is premixed with the air is provided. The engine controls oxygen concentration inside the cylinder and an ignition delay so that a ratio of a quantity of the fuel injected before a start of ignition to a total fuel injection quantity falls within a range from 25% to 50% and so that the premixed gas formed in the premixing space is combusted serially.

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: In a fuel injection nozzle including multiple nozzle hole groups each having multiple solitary nozzle holes, a group distance C between two of the nozzle hole groups is 0.8 or more times larger than an in-group hole distance ? in a nozzle hole group. The group distance C is the minimum interval of inter-group intervals that are formed between (i) peripheral boundaries of solitary nozzle holes belonging to a first nozzle hole group and (ii) peripheral boundaries of solitary nozzle holes belonging to a second nozzle hole group adjacent to the first nozzle hole group. The in-group hole distance ? is the minimum of intervals between peripheral boundaries belonging to each nozzle hole group.

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 emission control system for an internal combustion engine is located on a vehicle and provided with a particulate filter to accumulate particulate matters in an exhaust gas of the engine. The system has a pressure difference detector, an exhaust flow rate detector, a regeneration controller and a detection accuracy increaser. The pressure difference detector detects a differential pressure in the particulate filter. The exhaust flow rate detector detects an exhaust flow rate of the engine. The regeneration controller determines to regenerate the particulate filter based on the differential pressure and the exhaust flow rate. The detection accuracy increaser increases a detection accuracy of the differential pressure.

Abstract: An electronic control unit (an ECU) detects an operating condition of an engine and quantity of particulate matters accumulated in a diesel particulate filter (a DPF) having an oxidation catalyst from a pressure difference across the DPF. The ECU operates temperature increasing means for regenerating the DPF based on the above detection results. During a low speed and light load operation, the ECU does not perform temperature increasing operation similar to an operation performed during a middle load operation. Instead, the ECU performs operation such as reduction of recirculated exhaust gas quantity in order to inhibit an increase in the quantity of the accumulated particulate matters. When the operating condition is changed afterward, the temperature increasing means is operated, so safe regeneration of the DPF is achieved.

Abstract: A compression ignition engine injects fuel through injection holes of an injector at a substantially constant injection rate to atomize the fuel so that the fuel can be easily vaporized and to make the fuel penetrate an atmosphere inside a cylinder. A spatial distribution of the injected fuel in which mixing of the fuel and air is promoted as the fuel recedes from the injection hole and the fuel reaches a premixing space where the fuel is premixed with the air is provided. The engine controls oxygen concentration inside the cylinder and an ignition delay so that a ratio of a quantity of the fuel injected before a start of ignition to a total fuel injection quantity falls within a range from 25% to 50% and so that the premixed gas formed in the premixing space is combusted serially.

Abstract: An electronic control unit estimates progress of growth in a particle diameter of an ash accumulated in a diesel particulate filter (a DPF), based on an operating state of an engine. If it is determined that an estimated particle diameter of the ash achieved through the progress of the growth is greater than a predetermined value, regeneration of the DPF is compulsorily performed even when a quantity of particulate matters accumulated in the DPF is lower than a reference value, at which the DPF should be regenerated. Thus, the particulate matters are eliminated through combustion, and the ashes are discharged from the DPF.

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 perfect 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: 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: A diesel oxidation catalyst is disposed upstream of a diesel particulate filter (a DPF) disposed in an exhaust passage of a diesel engine. An electronic control unit (an ECU) operates temperature increasing means, which performs post-injection, to eliminate particulate matters accumulated in the DPF. The ECU includes first correcting means and second correcting means. The first correcting means corrects a manipulated variable of the temperature increasing means based on a result of comparison between target temperature and temperature of the DPF estimated based on information related to an area upstream of the DPF. The second correcting means corrects the manipulated variable of the temperature increasing means based on a result of comparison between the target temperature and the temperature of the DPF estimated based on information related to an area downstream of the DPF.

Abstract: If the amount of fuel added to exhaust gas becomes excessive as a result of an abnormality of an addition agent supply unit (60), the air-fuel ratio of exhaust as decreases. If an exhaust gas air-fuel ratio obtained from a value output from an A/F sensor (4) remains equal to or smaller than a predetermined value for a predetermined period, an ECU (2) determines that an addition agent supply unit (60) is abnormal. Upon detection of an abnormality of the addition agent supply unit (60), the ECU (2) incrteases an amount of EGR gas recirculated to the intake side by an EGR unit (40), reduces an amount of fuel injection from injectors (11), and restricts an operational state of an engine body (10) to a low-speed/low-load state. Also, the ECU (2) turns a warning lamp (7) on, warns a driver of the abnormality of the addition agent supply unit (60), and makes it possible to pull a vehicle over safely.

Abstract: An electronic control unit (an ECU) detects an operating condition of an engine and quantity of particulate matters accumulated in a diesel particulate filter (a DPF) having an oxidation catalyst from a pressure difference across the DPF. The ECU operates temperature increasing means for regenerating the DPF based on the above detection results. During a low speed and light load operation, the ECU does not perform temperature increasing operation similar to an operation performed during a middle load operation. Instead, the ECU performs operation such as reduction of recirculated exhaust gas quantity in order to inhibit an increase in the quantity of the accumulated particulate matters. When the operating condition is changed afterward, the temperature increasing means is operated, so safe regeneration of the DPF is achieved.

Abstract: In an exhaust gas cleaning system of an internal combustion engine having a diesel particulate filter (DPF), measuring accuracy of a collection quantity of particulate matters collected by the DPF is estimated based on an accelerator position change rate and an exhaust gas flow rate. When the measuring accuracy is high, the collection quantity is calculated based on a pressure difference and the exhaust gas flow rate at the DPF. If the measuring accuracy is low, an increment value of the collection quantity is calculated based on a quantity of the particulate matters discharged from an engine main body. Then, the collection quantity is calculated by adding the collection quantity increment value to the previous collection quantity calculated based on the pressure difference and the exhaust gas flow rate while the measuring accuracy is high.

Abstract: A diesel particulate filter (DPF) having an oxidation catalyst is disposed between exhaust pipes of an internal combustion engine. An exhaust gas temperature sensor senses outlet gas temperature of the DPF. An engine control unit (ECU) calculates estimated central temperature of the DPF from an output of the exhaust gas temperature sensor with the use of an inverse transfer function of a change in the outlet gas temperature with respect to a change in temperature of the DPF. Based on the estimated temperature, the ECU performs excessive temperature increase prevention control or regeneration control of the DPF. The transfer function is simply expressed with first-order lag and dead time. A time constant of the first-order lag and the dead time are set in accordance with an exhaust gas flow rate.

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: 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: A diesel particulate filter (DPF) fixedly held by a holding member in a metallic case is disposed in an exhaust pipe of a diesel engine. The DPF is a monolithic structural body having a multiplicity of cells provided by porous cell walls. The DPF has wall flow structure in which the cells are blocked alternately with filler on an exhaust gas inlet side or an exhaust gas outlet side of the DPF. The cells in a peripheral area extending inward from a peripheral surface of the DPF by a predetermined width are blocked with the filler on both sides of the DPF. Thus, a peripheral heat-retaining layer having the width of 5 to 20 mm is formed to improve temperature increasing performance at a particulate matter collecting area inside the peripheral heat-retaining layer.

Abstract: In an exhaust gas cleaning system of an internal combustion engine having a diesel particulate filter (DPF), measuring accuracy of a collection quantity of particulate matters collected by the DPF is estimated based on an accelerator position change rate and an exhaust gas flow rate. When the measuring accuracy is high, the collection quantity is calculated based on a pressure difference and the exhaust gas flow rate at the DPF. If the measuring accuracy is low, an increment value of the collection quantity is calculated based on a quantity of the particulate matters discharged from an engine main body. Then, the collection quantity is calculated by adding the collection quantity increment value to the previous collection quantity calculated based on the pressure difference and the exhaust gas flow rate while the measuring accuracy is high.