Abstract: A diagnostic device of an internal combustion engine diagnoses a condition of a differential pressure sensor. The sensor in a normal condition detects a differential pressure of an exhaust gas between upstream and downstream sides of a diesel particulate filter disposed in an exhaust system of the engine. The sensor in a fault condition detects no differential pressure of the exhaust gas. The device has a block obtaining a first signal from the sensor when the engine is operated in a low flow rate region of the exhaust gas and obtaining a second signal from the sensor when the engine is operated in a high flow rate region of the exhaust gas. A diagnostic block of the device judges from a difference between levels of the first and second signals whether the sensor is in the normal or fault condition.

Abstract: A NOx sensor abnormality detection device senses a NOx concentration and an O2 concentration from output signals of a NOx sensor and calculates an estimated NOx concentration from the O2 concentration when an engine is in a steady operation state, when a zero point of the NOx concentration is sensed, and when an O2 sensing section of the NOx sensor is normal. The NOx sensor abnormality detection device calculates a sensed inclination and an estimated inclination of a NOx concentration output characteristic of the NOx sensor based on the sensed NOx concentration, the sensed O2 concentration and the estimated NOx concentration calculated from the O2 concentration. The NOx sensor abnormality detection device determines that the NOx sensor is faulty when an absolute value of a difference between the sensed inclination and the estimated inclination is larger than a predetermined value.

Abstract: A diagnostic apparatus monitors a pressure difference detection apparatus that detects the pressure difference across an engine exhaust gas cleansing device in an exhaust gas system, with the diagnostic apparatus recognizing a condition of impeded transfer of gas between the pressure difference detection apparatus and the exhaust gas system, based upon a manner of convergence of successive detected pressure difference values that are produced by the pressure difference detection apparatus following a change in the exhaust gas flow rate.

Abstract: An exhaust emission control device for an internal combustion engine includes a capturing device that is disposed in an exhaust passage of the engine and that captures particulate matter in exhaust gas flowing through the exhaust passage, a sensor that is disposed in the exhaust passage on a downstream side of the capturing device in a flow direction of exhaust gas and that measures an amount of soot in the particulate matter, a control unit for increasing the particulate matter that flows into the capturing device, and a determination device for determining whether the capturing device is at fault based on the amount of soot measured by the sensor after increasing the particulate matter that flows into the capturing device through the control unit.

Abstract: An exhaust gas purifying apparatus for an internal combustion engine includes a collector, which collects exhaust particles in exhaust gas. The apparatus computes a pressure-difference-based measured value of a collected amount of the particles based on a pressure difference, and computes a pressure-difference-based estimated value by correcting the measured value. The apparatus computes an operational-state-based estimated value of the collected amount. The apparatus regenerates the collector by burning the exhaust particles when one of the pressure-difference-based estimated value and the operational-state-based estimated value reaches a predetermined value.

Abstract: An exhaust gas cleaning apparatus (e.g., for a diesel engine) uses a collector for collecting particulates contained in the exhaust gas and is disposed in an exhaust pipe of the engine. Damages in the collector are detected based on a pressure difference between an inlet and an outlet of the collector. In order to correctly detect the damages based on the pressure difference, an exhaust gas volume flowing through the collector is increased to a target volume by raising exhaust gas temperature. The exhaust gas temperature is raised by injecting fuel into the engine at a time when an engine output is not increased by such fuel injection. The pressure difference, based on which damages in the collector are detected, is measured after the exhaust gas volume has reached the target volume. It is determined that damages in the collector have occurred if the pressure difference is lower than a predetermined value.

Abstract: A NOx sensor abnormality detection device senses a NOx concentration and an O2 concentration from output signals of a NOx sensor and calculates an estimated NOx concentration from the O2 concentration when an engine is in a steady operation state, when a zero point of the NOx concentration is sensed, and when an O2 sensing section of the NOx sensor is normal. The NOx sensor abnormality detection device calculates a sensed inclination and an estimated inclination of a NOx concentration output characteristic of the NOx sensor based on the sensed NOx concentration, the sensed O2 concentration and the estimated NOx concentration calculated from the O2 concentration. The NOx sensor abnormality detection device determines that the NOx sensor is faulty when an absolute value of a difference between the sensed inclination and the estimated inclination is larger than a predetermined value.

Abstract: A diagnostic device of an internal combustion engine diagnoses a condition of a differential pressure sensor. The sensor in a normal condition detects a differential pressure of an exhaust gas between upstream and downstream sides of a diesel particulate filter disposed in an exhaust system of the engine. The sensor in a fault condition detects no differential pressure of the exhaust gas. The device has a block obtaining a first signal from the sensor when the engine is operated in a low flow rate region of the exhaust gas and obtaining a second signal from the sensor when the engine is operated in a high flow rate region of the exhaust gas. A diagnostic block of the device judges from a difference between levels of the first and second signals whether the sensor is in the normal or fault condition.

Abstract: In an exhaust cleaning system including a DPF in exhaust passages, a pair of temperature sensors is disposed upstream and downstream the filter to detect upstream and downstream exhaust temperatures. An electronic control unit estimates a downstream exhaust temperature from the actual upstream exhaust temperature when an engine is in a predetermined condition such as a cold-start condition or a high speed and high load condition, in which no catalytic reaction heat is generated in the DPF. The control unit then compares the estimated downstream temperature with the actually detected downstream temperature, and determines an exhaust temperature senor malfunction if the difference between the compared temperatures are large.

Abstract: Unless an abnormality exists in piping introducing a pressure from front and rear of DPF 22 into a differential pressure sensor 45, pulsations of pressure propagation through an exhaust passage 21 is offset in a detection value of a pressure difference of the differential pressure sensor 45, and an amplitude of the detection value of the DPF pressure difference resulting from pulsation of the pressure becomes small. If a crack exists in one of the piping 3a and 3b, the influence of a pulsation of the pressure appears in the DPF pressure difference and the amplitude of the detection value of the DPF pressure difference becomes large. The amplitude of the detection value of the DPF pressure difference is compared with the reference value and is detected as being abnormal when it is large, utilizing the phenomenon described above.

Abstract: A diagnostic apparatus monitors a pressure difference detection apparatus that detects the pressure difference across an engine exhaust gas cleansing device in an exhaust gas system, with the diagnostic apparatus recognizing a condition of impeded transfer of gas between the pressure difference detection apparatus and the exhaust gas system, based upon a manner of convergence of successive detected pressure difference values that are produced by the pressure difference detection apparatus following a change in the exhaust gas flow rate.

Abstract: An exhaust gas cleaning apparatus of the present invention is advantageously used in a diesel engine. A collector for collecting particulates contained in the exhaust gas is disposed in an exhaust pipe of the engine. Damages in the collector are detected based on a pressure difference between an inlet and an outlet of the collector. In order to correctly detect the damages based on the pressure difference, an exhaust gas volume flowing through the collector is increased to a target volume by raising exhaust gas temperature. The exhaust gas temperature is raised by injecting fuel into the engine at a timing when an engine output is not increased by such fuel injection. The pressure difference, based on which the damages in the collector are detected, is measured after the exhaust gas volume reached the target volume. It is determined that the damages in the collector have occurred if the pressure difference is lower than a predetermined value.

Abstract: An exhaust gas purifying apparatus for an internal combustion engine includes a collector, which collects exhaust particles in exhaust gas. The apparatus computes a pressure-difference-based measured value of a collected amount of the particles based on a pressure difference, and computes a pressure-difference-based estimated value by correcting the measured value. The apparatus computes an operational-state-based estimated value of the collected amount. The apparatus regenerates the collector by burning the exhaust particles when one of the pressure-difference-based estimated value and the operational-state-based estimated value reaches a predetermined value.

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: Unless an abnormality exists in piping introducing a pressure from front and rear of DPF 22 into a differential pressure sensor 45, pulsations of pressure propagation through an exhaust passage 21 is offset in a detection value of a pressure difference of the differential pressure sensor 45, and an amplitude of the detection value of the DPF pressure difference resulting from pulsation of the pressure becomes small. If a crack exists in one of the piping 3a and 3b, the influence of a pulsation of the pressure appears in the DPF pressure difference and the amplitude of the detection value of the DPF pressure difference becomes large. The amplitude of the detection value of the DPF pressure difference is compared with the reference value and is detected as being abnormal when it is large, utilizing the phenomenon described above.

Abstract: In an exhaust cleaning system including a DPF in exhaust passages, a pair of temperature sensors is disposed upstream and downstream the filter to detect upstream and downstream exhaust temperatures. An electronic control unit estimates a downstream exhaust temperature from the actual upstream exhaust temperature when an engine is in a predetermined condition such as a cold-start condition or a high speed and high load condition, in which no catalytic reaction heat is generated in the DPF. The control unit then compares the estimated downstream temperature with the actually detected downstream temperature, and determines an exhaust temperature senor malfunction if the difference between the compared temperatures are large.

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: 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: In a system in which a common rail accumulates fuel pressurized by a high pressure supply pump, when a pipe connected to the common rail is damaged or a pulsation of fuel injection is caused in the system, reliability of the system is greatly affected because of high pressure. According to the present invention, a mechanism to prevent leakage of fuel from the common rail even when the pipe is damaged, or a mechanism to damp a pulsation of fuel pressure, is provided in a pipe close to the common rail. Therefore, reliability of the system is improved.