An exhaust gas treatment system for an internal combustion engine with an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine. The system includes a heater operable to heat the exhaust gas as it passes through the exhaust gas pathway, an injector configured to inject reductant into the exhaust gas pathway, a first treatment element positioned in the exhaust gas pathway downstream of the heater and the injector, and a second treatment element positioned in the exhaust gas pathway downstream of the first treatment element. At least one of the first treatment element or the second treatment element includes a selective catalytic reduction (SCR) element, and the exhaust gas treatment system does not include a precious metal catalyst upstream of the first treatment element.

In a discharge generator, a control unit switchably performs a continuous mode and a burst mode based on determination of whether target output power is higher than discharge start power. The burst mode alternately performs a discharge mode and a non-discharge mode. The control unit causes a burst ratio to be set to a value expressed by the following equation b=Po*/P.sub.fs0 where b represents the burst ratio, Po* represents the target output power, and P.sub.fs0 represents the discharge start power. The burst ratio is defined as a ratio of the discharge period to a burst period. The burst period is the sum of the discharge period and the stop period. The control unit causes, in the burst mode, the switch circuit to output, as the output power, the discharge start power during the discharge period.

Exhaust purification system and methods for the reduction of emissions from an exhaust stream, including an upstream catalyst coupled with a passive NO.sub.x adsorber catalyst; means to contact the exhaust stream with ozone, to react NO in the exhaust stream with the ozone to produce NO.sub.2; and an SCR catalyst.

An engine assembly includes a diesel internal combustion engine and an aftertreatment system coupled to the diesel internal combustion engine. The aftertreatment system includes a diesel oxidation catalyst coupled to the diesel internal combustion engine such that the diesel oxidation catalyst receives exhaust gases from the diesel internal combustion engine. The aftertreatment system includes a plasma generator in fluid communication with the diesel oxidation catalyst, wherein the plasma generator is upstream of the diesel oxidation catalyst and downstream of the diesel internal combustion engine, and the plasma generator is configured to generate oxidizers to at least partially oxidize hydrocarbons in the exhaust gases exiting the diesel internal combustion engine.

In a discharge generator, a control unit switchably performs a continuous mode and a burst mode based on determination of whether target output power is higher than discharge start power. The burst mode alternately performs a discharge mode and a non-discharge mode. The control unit causes a burst ratio to be set to a value expressed by the following equation b=P.sub.O*/P.sub.fs0 where b represents the burst ratio, P.sub.O* represents the target output power, and P.sub.fs0represents the discharge start power. The burst ratio is defined as a ratio of the discharge period to a burst period. The burst period is the sum of the discharge period and the stop period. The control unit causes, in the burst mode, the switch circuit to output, as the output power, the discharge start power during the discharge period.

An engine assembly includes a diesel internal combustion engine and an aftertreatment system coupled to the diesel internal combustion engine. The aftertreatment system includes a diesel oxidation catalyst coupled to the diesel internal combustion engine such that the diesel oxidation catalyst receives exhaust gases from the diesel internal combustion engine. The aftertreatment system includes a plasma generator in fluid communication with the diesel oxidation catalyst, wherein the plasma generator is upstream of the diesel oxidation catalyst and downstream of the diesel internal combustion engine, and the plasma generator is configured to generate oxidizers to at least partially oxidize hydrocarbons in the exhaust gases exiting the diesel internal combustion engine.

An exhaust gas control apparatus includes a dust collection device, an oxidation treatment device, and an ECU. The dust collection device applies a DC voltage between a charging electrode and a counter electrode, and collects particulate matter on an oxidation substrate. The ECU estimates a distribution of a deposition amount of the particulate matter deposited on the oxidation substrate in a flow direction of exhaust gas, based on input information including at least a flow rate of exhaust gas and a mass of particulate matter in exhaust gas, setting information including at least an electric field intensity between the charging electrode and the counter electrode, and history information on the oxidation treatment. The ECU carries out the oxidation treatment when the deposition amount of at least a part of the deposited particulate matter exceeds a threshold.

An exhaust gas control apparatus includes a dust collection device, an oxidation treatment device, and an ECU. The dust collection device applies a DC voltage between a charging electrode and a counter electrode, and collects particulate matter on an oxidation substrate. The ECU estimates a distribution of a deposition amount of the particulate matter deposited on the oxidation substrate in a flow direction of exhaust gas, based on input information including at least a flow rate of exhaust gas and a mass of particulate matter in exhaust gas, setting information including at least an electric field intensity between the charging electrode and the counter electrode, and history information on the oxidation treatment. The ECU carries out the oxidation treatment when the deposition amount of at least a part of the deposited particulate matter exceeds a threshold.

A purification system for purifying exhaust gas from an engine includes a separation part that separates oxygen and nitrogen contained in air, an ozone generation part that generates ozone from oxygen separated by the separation part, and a supply part that supplies ozone generated by the ozone generation part to an intake pipe and an exhaust pipe of the engine. The purification system includes a supply control device that adjusts an amount of ozone supplied to the intake pipe and an amount of ozone supplied to the exhaust pipe according to a purification rate of exhaust gas of the engine.

An ozone supply device includes an ozonizer, a blower and a housing while the housing serves as an intake duct member. The ozonizer includes electrodes that generate ozone through electric discharge. The blower includes a suction inlet, through which air is drawn, and a discharge outlet, through which the air drawn from the suction inlet is discharged. The blower supplies the air discharged from the discharge outlet to the electrodes and blows the ozone generated through the electric discharge to an exhaust passage. The housing forms a suction air passage that guides the air to the suction inlet. At least a portion of the ozonizer is placed in the suction air passage.