An exhaust gas purification system for vehicle includes: a housing disposed on an exhaust pipe to receive a exhaust gas discharged from an engine and to exhaust the exhaust gas passed rearward; a front end catalyst disposed in the housing to purify the exhaust gas flowing into the housing through a front end of the housing; a rear end catalyst disposed in the housing to purify the exhaust gas passing through the front end catalyst before the exhaust gas flows out to a rear end of the housing; and a controller connected to the exhaust pipe at a front end of the housing to control a concentration of unburned fuel contained in the exhaust gas flowing into the housing.

Methods and systems are provided for an exhaust aftertreatment arrangement. In one example, a system includes a LNT upstream of an SCR with an oxygen storage component arranged therebetween, and where a rich operation of an engine is limited based on an oxygen load of the oxygen storage component when an exhaust gas temperature is higher than a limit temperature.

A method of controlling oxygen purge of a three-way catalyst may include: performing a fuel cut-off; determining whether a fuel cut-in condition is satisfied after the fuel cut-off; calculating an optimum valve overlap according to an intake amount, an engine rotation speed, and an ignition timing if the fuel cut-in condition is satisfied after the fuel cut-off; controlling a CVVD apparatus to be at the optimum valve overlap; and performing the oxygen purge at the optimum valve overlap.

Provided is a novel exhaust gas purification catalyst, which uses a Cu-based delafossite oxide, capable of increasing the exhaust gas purification performance compared to the case of using the Cu-based delafossite oxide alone. Proposed is an exhaust gas purification catalyst comprising a delafossite-type oxide represented by a general formula ABO.sub.2 and an inorganic porous material, wherein Cu is contained in the A site of the general formula of the delafossite oxide, one or two or more elements selected from the group consisting of Mn, Al, Cr, Ga, Fe, Co, Ni, In, La, Nd, Sm, Eu, Y, V, and Ti are contained in the B site thereof, and Cu is contained in 3 to 30% relative to the total content (mass) of the delafossite-type oxide and the inorganic porous material.

An exhaust purification system of an internal combustion engine comprises a filter trapping particulate matter in exhaust gas, a differential pressure sensor detecting a differential pressure before and after the filter or a differential pressure between a pressure in the exhaust passage and an atmospheric pressure, a temperature sensor detecting a temperature of exhaust gas, and a deposition calculating part configured to calculate an amount of particulate matter deposited at the filter. The deposition calculating part is configured to calculate a first estimated value of an amount of the particulate matter based on the differential pressure, calculate a second estimated value of an amount of the particulate matter based on an amount of increase of temperature of the exhaust gas, and calculate an amount of the particulate matter based on the first estimated value and the second estimated value.

An exhaust purification system includes an LAF sensor provided in an exhaust pipe and generates a signal corresponding to an air-fuel ratio of exhaust gas. An upstream catalytic converter is downstream of the LAF sensor and has a catalyst to purify the exhaust gas. An O2 sensor is downstream of the upstream catalytic converter, and generates a signal corresponding to the air-fuel ratio of the exhaust gas. A GPF is downstream of a the O2 sensor and purifies the exhaust gas. An ECU controls an air-fuel mixture in an engine using output signal KACT of the LAF sensor and an output signal VO2 of the O2 sensor such that the air-fuel ratio of exhaust gas flowing into the GPF converges to a target value near the stoichiometric ratio. The GPF has a filter substrate and a downstream TWC supported by a partition of the filter substrate.

An exhaust purification system of an internal combustion engine includes a catalyst arranged in an exhaust passage of the internal combustion engine and able to store oxygen, a storage amount calculating part configured to calculate an oxygen storage amount of the catalyst, a poisoning amount calculating part configured to calculate a poisoning amount of the catalyst, and an oxygen amount control part configured to control an amount of oxygen supplied to the catalyst based on the oxygen storage amount and the poisoning amount.

A method of controlling oxygen purge of a three-way catalyst may include: performing a fuel cut-off; determining whether a fuel cut-in condition is satisfied after the fuel cut-off; calculating an optimum valve overlap according to an intake amount, an engine rotation speed, and an ignition timing if the fuel cut-in condition is satisfied after the fuel cut-off; controlling a CVVD apparatus to be at the optimum valve overlap; and performing the oxygen purge at the optimum valve overlap.

An oxygen storage material comprises a LaCoAl-based composite oxide containing lanthanum, cobalt and aluminum. The LaCoAl-based composite oxide is in a form in which at least part of the aluminum is solid-dissolved in a LaCo composite oxide having a perovskite structure, and has a composition expressed by the following chemical formula (1):
LaCo.sub.yAl.sub.xO.sub.(1)
where x and y are numbers satisfying conditions of 0<x <1 and 0<y<1, where x+y=0.5 to 1.5, and is a number of 1.5 to 4.5.

An oxygen storage material including a ceria-zirconia based composite oxide containing a composite oxide of ceria and zirconia, wherein the ceria-zirconia based composite oxide comprises at least one rare-earth element selected from the group consisting of lanthanum, yttrium, and neodymium, and an amount of the rare-earth element(s) contained in total is 1 to 10% by atom in terms of element relative to a total amount of cerium and zirconium in the ceria-zirconia based composite oxide, 60 to 85% by atom of the entire amount of the rare-earth element(s) is contained in a near-surface upper-layer region extending from a surface of each primary particle of the ceria-zirconia based composite oxide to a depth of 50 nm in the primary particle, and 15 to 40% by atom of the entire amount of the rare-earth element(s) is contained in a near-surface lower-layer region extending from a depth of 50 nm to a depth of 100 nm in the primary particle, a content ratio of cerium and zirconium in the ceria-zirconia based composite oxide is in a range of 40:60 to 60:40 in terms of an atomic ratio ([Ce]:[Z]), and the ceria-zirconia based composite oxide has an intensity ratio {I(14/29) value} between a diffraction line at 2=14.5 and a diffraction line at 2=29 which satisfies the following condition: I(14/29) value0.032,
where the intensity ratio {I(14/29) value} is determined from an X-ray diffraction pattern using CuK obtained by an X-ray diffraction measurement conducted after heating in air under a temperature condition of 1100 C. for 5 hours.