Provided is a method for accurately diagnosing a degree of degradation of an oxidation catalyst. A target gas detecting element configured to output an electromotive force corresponding to a concentration of a target gas is provided downstream of a catalyst in an exhaust path of an internal combustion engine. A maximum change amount of an electromotive force after the introduction of a gas atmosphere for diagnosis into the catalyst is set as a diagnosis index value. The gas atmosphere has been intentionally created in the engine and includes a target gas having a concentration higher than the concentration of a target gas in a steady operation state of the engine. The index value is then compared with a threshold corresponding to the temperature of the catalyst to diagnosis whether degradation exceeding an acceptable degree has occurred in the catalyst.

Selective catalytic reduction systems are known and are generally included in exhaust systems of diesel engines in order to treat the exhaust gases of such engines. Such systems involve the introduction of diesel exhaust fluid (DEF) into exhaust gas flowing in an exhaust passage of an engine. When dosing DEF onto a hydrolysis catalyst in a SCR system, the DEF will under certain conditions cool the hydrolysis catalyst sufficiently to either slow down or effectively prevent ammonia release, which creates a lag or delay in the function of the hydrolysis catalyst. This limits the amount of control which can be exerted over ammonia storage in the SCR catalyst, and NOx conversion. In a first step, a set of measurement data is received from one or more sensors provided in the system. Subsequently, a first set of characteristics associated with a state of a component of the catalytic system, a second set of characteristics associated with an output of the catalytic system and a third set of characteristics associated with a bias and a scaling factor in the system are derived. In a third step, the derived sets of characteristics are used to control the catalytic system.

A boiler or other fired vessel includes a housing with a burner at one end, a furnace downstream of the burner, a convection section downstream of the furnace and a flue gas outlet downstream of the convection section. A first means for loading a reducing agent comprising at least two injectors is located downstream of the furnace. A second means for loading a reducing agent is located downstream of the first means for loading a reducing agent. A selective catalytic reduction catalyst is located either downstream of the second means for loading a reducing agent or adjacent the second means for loading a reducing agent such that the catalyst is provided to the boiler or other fired vessel approximately simultaneously with the reducing agent from the second means for loading the reducing agent.

A vehicle exhaust system includes a mixer assembly for a vehicle exhaust system. The mixer assembly includes a mixer housing that defines an internal cavity and which includes at least one injection opening. A manifold is positioned within the internal cavity at the injection opening. A primary injector is configured to inject fluid through the injection opening and into the internal cavity, and at least one secondary injector, which is separate from the primary injector, is configured to inject fluid into the internal cavity when operating temperatures fall below a predetermined level.

The present disclosure relates to ECU for an exhaust purging system comprises: a NOx catalyst provided in an exhaust passage; and a second composite sensor detecting an air-fuel ratio in a downstream of the NOx catalyst, the ECU, which performs a routine of a purge control, calculates the sum of values of the reductant that have been supplied to the NOx catalyst since the start of the routine of the purge control, determines whether the sum is greater than or equal to an end determination threshold, determines whether the air-fuel ratio is less than or equal to a predetermined value, and ends the routine of the purge control in response to an earlier one of a first affirmative determination that the sum is greater than or equal to the end determination threshold and a second affirmative determination that the air-fuel ratio is less than or equal to the predetermined value.

When an integrated value of a determination value correlated with a command value for an amount of supply of a reducing agent at the time of the command value being larger than a command supply amount threshold value reaches an integration threshold value, a determination is made that a diagnosis condition is satisfied, and an abnormality in the supply of the reducing agent is diagnosed based on an integrated value of the command value for the amount of supply of the reducing agent and an integrated value of an estimated value of the amount of supply of the reducing agent, whereas in cases where a period of time in which the diagnosis condition is not satisfied is longer than a time period threshold value, an interval of supply of the reducing agent is extended.

A control apparatus for a gasoline engine having a fuel injection means including an in-cylinder injection valve. The control apparatus comprises a controller configured to, when warming up an exhaust gas purification catalyst provided in an exhaust passage provided of the gasoline engine, control the fuel injection means to conduct one or more main injections, control the in-cylinder injection valve to conduct a post injection, perform a retard correction of an ignition timing at which fuel injected by the one or more main injections is ignited, determine an injection quantity by the one or more main injections and an injection quantity by the post injection such that an air-fuel mixture formed in the cylinder by gasoline fuel injected by the one or more main injections has a predetermined lean air-fuel ratio at which a difference between an actual output torque and a required torque is within a predetermined allowable range.

According to various embodiments, an exhaust treatment system includes a catalyst that is in direct contact with an exhaust stream, at least one sensor that senses a system parameter and produces one or more signals corresponding to the system parameter, and a controller that is configured to receive the one or more signals and control catalyst performance based on the one or more signals by regenerating the catalyst. Regenerating the catalyst includes increasing a temperature of the exhaust stream flowing to the catalyst and directing a reductant injector to adjust a flow rate of reductant being injected into the exhaust stream flowing to the catalyst.

A system and method for diagnosing the oxidation catalyst of a vehicle includes an engine, an exhaust system in fluid communication with an exhaust port of the engine and an oxidation catalyst connected with the engine via the exhaust port to receive an exhaust stream from the engine. A controller is operable to determine the operating state of the engine and vehicle, calculate a heat release value for the oxidation catalyst and determine an ideal heat release value. The controller will determine the oxidation catalyst efficiency by calculating a ratio of the heat release value to the ideal heat release value.

An exhaust-gas purification system and method are provided for an internal combustion engine having an NOx storage catalytic converter and a downstream SCR catalytic converter. The NOx storage catalytic converter can be supplied in a first operating mode with an oxidizing exhaust gas and in a second operating mode with a reducing exhaust gas. A third operating mode is provided between the first operating mode and the second operating mode, in which an exhaust gas which has a lower content of oxidizing constituents than the first operating mode and a lower content of reducing constituents than the second operating mode can be supplied to the NOx storage catalytic converter to improve NH.sub.3 production at the start of converter regeneration.