Exhaust emission control device and method of controlling exhaust emission

An emission control device that reduces carbon-containing particulates included in a flow of exhaust gas from an internal combustion engine, that comprises a plurality of combustion chambers, an exhaust manifold that unites flows of exhaust gas from said plurality of combustion chambers to at least one joint flow, and an exhaust pipe that leads the joint flow of exhaust gas united by said exhaust manifold to the air, said emission control device comprising:

• a first heat-resistant filter medium that traps hydrocarbon compounds and the carbon-containing particulates included in the flow of exhaust gas in a dispersive manner to bring the respective particulates and hydrocarbon compounds in contact with oxygen included in the exhaust gas, and thereby makes the trapped hydrocarbon compounds and the trapped carbon-containing particulates subjected to combustion with the exhaust gas having a filter inflow temperature lower than a combustible temperature of the carbon-containing particulates;
• and said first heat-resistant filter medium being disposed in said exhaust manifold, and
• a second heat-resistant filter medium that traps the remaining carbon-containing particulates, which have not been trapped by said first heat-resistant filter medium but have passed through said first heat-resistant filter medium, said second heat-resistant filter medium being disposed in said exhaust pipe;
• wherein said first heat-resistant filter medium does not trap most of metal sulfate particulates but allows passage of the metal sulfate particulates therethrough, the metal sulfate particulates being produced from metal components added to lubricating oil of said internal combustion engine and sulfur in a fuel of said internal combustion engine and being suspended in the flow of exhaust gas.

An emission control device that reduces carbon-containing particulates included in a flow of exhaust gas from an internal combustion engine, said emission control device comprising:

• a first heat-resistant filter medium that traps hydrocarbon compounds and the carbon-containing particulates included in the flow of exhaust gas in a dispersive manner to bring the respective particulates and hydrocarbon compounds in contact with oxygen included in the exhaust gas, and thereby makes the trapped hydrocarbon compounds and the trapped carbon-containing particulates subjected to combustion with the exhaust gas having a filter inflow temperature lower than a combustible temperature of the carbon-containing particulates;
• a second heat-resistant filter medium that traps the remaining carbon-containing particulates, which have not been trapped by said first heat-resistant filter medium but have passed through said first heat-resistant filter medium;
• and
• a vane that is located on a pathway of the flow of exhaust gas from said internal combustion engine, is driven by the flow of exhaust gas, and breaks down the particulates included in the flow of exhaust gas,
• wherein said first heat-resistant filter medium is disposed upstream of said vane, and
• said second heat-resistant filter medium is disposed downstream of said vane.

An emission control device that reduces carbon-containing particulates included in a flow of exhaust gas from an internal combustion engine, said emission control device comprising:

• a first heat-resistant filter medium that traps hydrocarbon compounds and the carbon-containing particulates included in the flow of exhaust gas in a dispersive manner to bring the respective particulates and hydrocarbon compounds in contact with oxygen included in the exhaust gas, and thereby makes the trapped hydrocarbon compounds and the trapped carbon-containing particulates subjected to combustion with the exhaust gas having a filter inflow temperature lower than a combustible temperature of the carbon-containing particulates;
• and
• a second heat-resistant filter medium that traps the remaining carbon-containing particulates, which have not been trapped by said first heat-resistant filter medium but have passed through said first heat-resistant filter medium;
• wherein said second heat-resistant filter medium has an active oxygen release agent carried thereon, the active oxygen release agent taking in and holding oxygen in the presence of excess oxygen in its atmosphere and releasing the oxygen held therein as active oxygen with a decrease in concentration of oxygen in the atmosphere, and
• wherein said second heat-resistant filter medium has a noble metal catalyst belonging to a platinum group carried thereon, in addition to the active oxygen release agent.

An emission control device that reduces carbon-containing particulates, which are included in a flow of exhaust gas with a variation in flow rate emitted from an internal combustion engine, using a filter material having a large number of pores tangled in a three-dimensional manner, said emission control device comprising:

• a first heat-resistant filter medium that is composed of the filter material, makes the exhaust gas flown into the pores, which are greater in size than the carbon-containing particulates, and causes the carbon-containing particulates to collide with and adhere to regions defining the pores of the filter material, thereby trapping the carbon-containing particulates;
• a second heat-resistant filter medium that filters the flow of exhaust gas passing through said first heat-resistant filter medium to trap the remaining carbon-containing particulates included in the flow of exhaust gas;
• and
• a flow rate variation mitigation module that mitigates the variation in flow rate of the exhaust gas flown into said second heat-resistant filter medium;
• wherein said first heat-resistant filter medium traps hydrocarbon compounds and the carbon-containing particulates included in the flow of exhaust gas in a dispersive manner to bring the respective particulates and hydrocarbon compounds in contact with oxygen included in the exhaust gas, and thereby makes the trapped hydrocarbon compounds and the trapped carbon-containing particulates subjected to combustion with the exhaust gas having a filter inflow temperature lower than a combustible temperature of the carbon-containing particulates, and
• said second heat-resistant filter medium has an active oxygen release agent carried thereon, the active oxygen release agent taking in and holding oxygen in the presence of excess oxygen in its atmosphere and releasing the oxygen held therein as active oxygen with a decrease in concentration of oxygen in the atmosphere.

An emission control method that reduces carbon-containing particulates included in a flow of exhaust gas from an internal combustion engine, said emission control method comprising the steps of:

• uniting flows of exhaust gas from a plurality of combustion chambers of said internal combustion engine to at least one joint flow in an exhaust manifold;
• using a first heat-resistant filter medium disposed in said exhaust manifold to trap hydrocarbon compounds and the carbon-containing particulates included in the united flow of exhaust gas in a dispersive manner to bring the respective particulates and hydrocarbon compounds in contact with oxygen included in the exhaust gas;
• making the trapped hydrocarbon compounds and the trapped carbon-containing particulates subjected to combustion with the exhaust gas having an inflow temperature into said first heat-resistant filter medium lower than a combustible temperature of the carbon-containing particulates;
• and
• using a second heat-resistant filter medium disposed in an exhaust pipe to trap the remaining carbon-containing particulates, which have not been trapped by said first heat-resistant filter medium but have passed through said first heat-resistant filter medium, in said exhaust pipe through which the exhaust gas that has passed through the first heat-resistant filter medium is released to the air.

An emission control method that reduces hydrocarbon compounds and carbon-containing particulates, which are included in a flow of exhaust gas with a variation in flow rate emitted from an internal combustion engine, using a filter material having a large number of pores tangled in a three-dimensional manner, said emission control method comprising the steps of:

• making the exhaust gas flow into pores of a first heat-resistant filter medium that is composed of the filter material, the pores of the first heat-resistant filter medium greater in size than the carbon-containing particulates, and causing the carbon-containing particulates to collide with and adhere to regions defining the pores of the filter material, thereby trapping the hydrocarbon compounds and the carbon-containing particulates in a dispersive manner to bring the respective particulates and hydrocarbon compounds in contact with oxygen included in the exhaust gas, and thereby making the trapped hydrocarbon compounds and the trapped carbon-containing particulates subjected to combustion with the exhaust gas having a filter inflow temperature lower than a combustible temperature of the carbon-containing particulates;
• mitigating the variation in flow rate of the exhaust gas;
• and
• filtering the flow of exhaust gas with the mitigated variation in flow rate through a second heat-resistant filter medium with an active oxygen release agent carried thereon, the active oxygen release agent taking in and holding oxygen in the presence of excess oxygen in its atmosphere and releasing the oxygen held therein as active oxygen with a decrease in concentration of oxygen in the atmosphere, thereby trapping the remaining carbon-containing particulates included in the flow of exhaust gas.