A particulate filter for trapping the particulate matter which is contained in the exhaust gas is provided inside an engine exhaust passage. Additional fuel is secondarily injected from a fuel injector in an engine expansion stroke or exhaust stroke or hydrocarbons are secondarily added from an addition valve which is provided upstream of the particulate filter in the exhaust pipe. An amount of hydrocarbons which come from the fuel injector or addition valve and then adhere in the form of a liquid to the inflow end of the particulate filter, and an amount of particulate matter which reaches the inflow end of the particulate filter are respectively estimated. A degree of clogging at the inflow end of the particulate filter is estimated based on the amount of hydrocarbons and the amount of particulate matter.

Methods and systems are presented for regenerating a particulate filter. In one example, vehicle speed control mode parameters may be adjusted in response to an amount of soot stored in a particulate filter being greater than a first threshold. The vehicle speed control parameters may be returned to base values in response to the amount of soot stored in the particulate filter being less than a second threshold.

An exhaust gas purification system comprise a first fuel supply unit to supply fuel to exhaust gas flowing in an exhaust passage by a supply valve arranged in the exhaust passage, and a second fuel supply unit to supply fuel to exhaust gas by adjusting a fuel injection condition wherein in a temperature raising stage of the NOx SCR catalyst associated with the exhaust gas temperature raising processing, first control is performed in which fuel is supplied by the first fuel supply unit, and in a temperature holding stage of the NOx SCR catalyst associated with the exhaust gas temperature raising processing, at least second control is performed in which the ratio of an amount of fuel supply by the second fuel supply unit with respect to an amount of fuel supply by the first fuel supply unit becomes higher in comparison with that when performing the first control.

A control system includes an ECU that controls supply of fuel from an addition valve and supply of fuel from an injection valve, estimates or detects a degree of end-face clogging on an exhaust-gas inflow side of a NOx catalyst, and sets an inlet temperature of the NOx catalyst by use of the fuel supplied from the injection valve to a higher level and sets an amount of the fuel supplied from the addition valve to a smaller value in a case where the degree of end-face clogging is equal to or larger than a predetermined value, compared to the case where the degree of end-face clogging is smaller than the predetermined value, when there also is a request for regeneration of an exhaust purification filter and/or a request for regeneration of the NOx catalyst.

An exhaust system for treating an exhaust gas from an internal combustion engine is disclosed. The system comprises a modified lean NO.sub.x trap (LNT), a urea injection system, and an ammonia-selective catalytic reduction (NH.sub.3-SCR) catalyst. The modified LNT comprises platinum, palladium, barium, and a ceria-containing material, and has a platinum:palladium molar ratio of at least 3:1. The modified LNT stores NO.sub.x at temperatures below about 200? C. and releases the stored NO.sub.x at temperatures above about 200? C. The urea injection system injects urea at temperatures above about 180? C.

A method for adjusting the temperature of an exhaust gas aftertreatment device is disclosed. A first characteristic temperature value for an oxidative carbon monoxide conversion and a second characteristic temperature value for an oxidative hydrocarbon conversion are assigned to an oxidation catalytic converter, and a third characteristic temperature value for a reductive NOx conversion is assigned to an SCR catalytic converter. Different respective values for injection parameters of injection processes for fuel injections into combustion chambers of the internal combustion engine and/or the heating output of an electric heating element are set upon reaching the first and the second characteristic temperature values for the temperature of the oxidation catalytic converter and upon reaching the third characteristic temperature value for the temperature of the SCR catalytic converter.

An exhaust gas cleaning apparatus for an internal combustion engine that is mounted on a vehicle includes an exhaust passage that is connected to the internal combustion engine, a filter that collects particulate matter in exhaust gas, an NO.sub.x reducing catalyst, a dosing valve that injects urea solution into the exhaust passage, and a controller that performs a filter regeneration process in response to a request for the filter regeneration process. The filter regeneration process includes a first filter regeneration process that is performed during an idle operation of the internal combustion engine and a second filter regeneration process that is performed with the vehicle traveling. When the first filter regeneration process has been performed for a predetermined number of times without being intervened by the second filter regeneration process, the controller does not perform the first filter regeneration process even when a request for the filter regeneration process is made.

A method includes supplying a first quantity of a first fuel to an engine and supplying a charge including a second fuel and air to the engine. The first fuel is different from the second fuel. The method further includes mixing the first fuel with the charge, supplying a second quantity of the first fuel to the engine, and igniting at least a portion of the first and second fuels in response to supplying the second quantity of the first fuel.

A controller for controlling regeneration in an aftertreatment system comprising a first leg and a second leg is configured to: determine whether regeneration is permitted by the engine based on engine operating parameters; in response to regeneration being permitted, determine whether regeneration is required in at least one of the first leg or the second leg based on operating parameters of the first leg and the second leg, and whether regeneration is inhibited in either the first leg or the second leg; and in response to determining that (i) regeneration is required in at least one of the first or second leg, and (ii) regeneration is not inhibited in either the first or the second leg, cause insertion of hydrocarbons into the engine to thereby increase the temperature of the exhaust gas to a target temperature and cause regeneration in each of the first and second leg.

An apparatus and a method of purifying exhaust gas are provided. The apparatus for purifying exhaust gas may include: an exhaust pipe connected to an exhaust manifold of an engine; a catalytic converter mounted on the exhaust pipe and including a hydrocarbon trap and a three-way catalyst; an exhaust gas recirculation (EGR) pipe connecting downstream of the catalytic converter to an intake manifold of the engine; an EGR valve mounted on the EGR pipe; a first oxygen sensor mounted on the exhaust pipe downstream of the catalytic converter; a second oxygen sensor mounted on the exhaust pipe upstream of the catalytic converter; and a controller controlling an operation of the EGR valve.