An internal combustion engine control device including an oxidation catalyst heating value estimation unit 88A, a NOx catalyst heating value estimation unit 88B, an oxidation catalyst temperature estimation unit 88C, a NOx catalyst temperature estimation unit 88D, and switches 801, 802, 803 that switch between an enabled state in which processing performed by the oxidation catalyst heating value estimation unit 88A and the oxidation catalyst temperature estimation unit 88C is executed and a disabled state in which the processing performed by the oxidation catalyst heating value estimation unit 88A and the oxidation catalyst temperature estimation unit 88C is not executed, wherein the control device is configured to be applied to both an exhaust gas purification system including an NOx-occlusion-reduction-type catalyst and an oxidation catalyst and an exhaust gas purification system including the NOx-occlusion-reduction-type catalyst and not including the oxidation catalyst.

A system and method for evaluating the efficiency of an oxidation catalyst of a vehicle exhaust system includes a diagnostic control system including a controller operatively connected to the exhaust system and at least one temperature sensor disposed proximate the oxidation catalyst to measure the temperature of the exhaust gas. The controller determines an operating state of at least one of the engine and exhaust system and initiates a particulate filter regeneration process in response to the detected operating state. The controller defines a first diagnostic index value and calculates a second diagnostic index value based upon the first diagnostic index value and an offset value. An oxidation catalyst efficiency validation module determines the efficiency of the oxidation catalyst.

An engine system may include an engine, an intake line, a cylinder deactivation (CDA) device mounted at a portion of combustion chambers, a first exhaust manifold connected to combustion chambers mounted with the CDA device, a second exhaust manifold connected to combustion chambers without the CDA device, a first exhaust line flowing exhaust gas exhausted from the first exhaust manifold, a second exhaust line flowing exhaust gas exhausted from the second exhaust manifold, a main exhaust line to which the first exhaust line and the second exhaust line are joined, an exhaust gas processing device at which the main exhaust line is installed, a turbocharger mounted at the first exhaust line, an electric supercharger installed at the intake line to supply supercharged air to the combustion chamber and an electric compressor, and an air injection device supplying the fresh air to the second exhaust manifold or the second exhaust line.

A method for monitoring an exhaust-gas sensor in which it is determined whether at least one monitored event has occurred by evaluating at least one heat quantity supplied to and/or withdrawn from the exhaust-gas sensor during a period of time, in particular under consideration of a change in the heat quantity stored by the exhaust-gas sensor that occurs during the period of time.

An exhaust purification system includes; a catalyst provided in an exhaust passage of an engine to purify an exhaust gas; a catalyst temperature estimating unit that estimates a temperature of the catalyst based on an initial temperature of the catalyst at the time of starting of the engine and a caloric value of the catalyst which changes depending on an operating state of the internal combustion engine; and an initial catalyst temperature setting unit that sets an initial temperature of the catalyst based on a catalyst temperature stored immediately before stopping the engine, a temperature of an exhaust gas flowing into the catalyst which is stored immediately before stopping the engine, a temperature of an exhaust gas flowing into the catalyst which is acquired at the time of starting the engine, and a temperature of air taken into the engine which is acquired at the time of starting the engine.

A diagnostic device includes: a diesel oxidation catalyst (DOC) for oxidizing hydrocarbon (HC) and nitrogen monoxide in an exhaust gas; a selective catalytic reduction (SCR) catalyst for reducing and purifying NOx contained in the exhaust gas; a NOx purification rate calculation unit which calculates, based on NOx values at upstream and downstream sides of the SCR catalyst, a low temperature NOx purification rate and a high temperature NOx purification rate; a HC heat generation rate calculation unit which calculates an HC purification rate based on at least the difference between the exhaust gas heat quantities at upstream and downstream sides of the DOC; and a deterioration determination unit which determines the deterioration in the NO.sub.2 producing capability of the DOC based on the calculated low temperature NOx purification rate, the calculated high temperature NOx purification rate, and the calculated HC purification rate.

A system and method for evaluating the efficiency of an oxidation catalyst of a vehicle exhaust system includes a diagnostic control system including a controller operatively connected to the exhaust system and at least one temperature sensor disposed proximate the oxidation catalyst to measure the temperature of the exhaust gas. The controller determines an operating state of at least one of the engine and exhaust system and initiates a particulate filter regeneration process in response to the detected operating state. The controller defines a first diagnostic index value and calculates a second diagnostic index value based upon the first diagnostic index value and an offset value. An oxidation catalyst efficiency validation module determines the efficiency of the oxidation catalyst.

A method is disclosed for optimizing fuel economy during an engine warm up phase of operation of an internal combustion engine. An exhaust manifold may have a coolant jacket through which a coolant may flow. A temperature of the coolant in the exhaust manifold may be determined to detect when it is at a predetermined maximum threshold, which represents a temperature threshold just below a temperature at which the coolant will begin to boil. When this threshold is reached, then a determination may be made as to a minimum rate of flow of the coolant through the exhaust manifold which maintains the coolant at about the predetermined maximum threshold, and the coolant may be flowed through the exhaust manifold at the determined minimum rate of flow.

A method is disclosed for regulating an exhaust after-treatment (AT) system for a diesel engine. The method includes detecting the engine's cold start when the engine's exhaust gas flow directed into the AT system is at a temperature below a threshold value. The method also includes determining flow-rates of the engine's exhaust gas and its fuel supply. The method additionally includes determining a magnitude of exhaust gas energy using the determined exhaust gas flow-rates and the fuel supply over an elapsed time following the cold start. The method also includes integrating a detected temperature of the exhaust gas over the elapsed time and comparing the determined magnitude of exhaust gas energy with the integrated temperature. Furthermore, the method includes regulating operation of the AT system using the determined exhaust gas temperature when the determined magnitude of exhaust gas energy is within a predetermined value of the integrated exhaust gas temperature.

An exhaust purifying device includes a throttle valve, a DOC device, an SCR device, a fuel injector, an inlet temperature sensor, an outlet temperature sensor, and a controller. The controller includes a heatup-control execution control unit configured to perform a regeneration treatment for removing a urea deposit when a predetermined heatup control execution condition is met, and a condition judgment unit configured to judge whether or not the first condition is met during the regeneration treatment by the heatup control.