A method is presented for estimating an amount of ammonia stored in a urea-based SCR catalyst based on a dynamic model of the catalyst. The model takes into account chemical and physical properties of the catalyst, such as catalyst volume, the number of available ammonia storage cites, adsorption and desorption dynamics, as well as poisoning, thermal aging, and different catalyst operating temperatures, and generates the estimate based on a measured or estimated amount of NOx in an exhaust gas mixture upstream of the catalyst, an amount of reductant injected into the catalyst to facilitate NOx reduction, and on a measured value of NOx in an exhaust gas mixture downstream of the catalyst. The estimated ammonia storage amount is then used to control the amount of reductant injected into the catalyst to maintain desired ammonia storage amount such that maximum NOx conversion efficiency coupled with minimum ammonia slip are achieved.

Exhaust gas aftertreatment systems

An internal combustion engine wherein an HC treatment catalyst (12) having the function of adsorbing the HC in the exhaust gas is arranged upstream of the NOx selective reducing catalyst (14), an urea aqueous solution fed from the reducing agent feed valve (15) is arranged upstream of the HC treatment catalyst (12), urea, and NOx contained in the exhaust gas, and HC adsorbed on the HC treatment catalyst 12 are reacted with each other to form intermediate products having cyano groups, oximes, and amino groups, and these intermediate products are sent to the NOx selective reducing catalyst (14).

Exhaust purification device of internal combustion engine

Methods and systems are provided for mitigating engine pre-ignition based on a feed-forward likelihood of pre-ignition and feedback from a pre-ignition event. In response to an indication of pre-ignition, a cylinder may be enriched while an engine load is limited. The enrichment may be followed by an enleanment to restore exhaust catalyst feed-gas oxygen levels. The mitigating steps may be adjusted based on engine operating conditions, a pre-ignition count, as well as the nature of the pre-ignition.

Method and system for pre-ignition control

A method and apparatus to reduce the emissions of an exhaust stream is provided. One feature of the present invention includes a control unit for metering a reagent into the exhaust stream. The control unit adjusts a quantity of the reagent to be metered into the exhaust stream. One embodiment of the present invention concerns a method of removing nitrogen oxides in exhaust gases from a diesel engine by introducing ammonia into the exhaust stream. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. This Abstract is submitted with the explicit understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.

Emission control system

An exhaust emission control device for an internal combustion engine, capable of supplying a just enough amount of reducing agent to a selective reduction catalyst even when a NOx purification ratio of the catalyst is changed by various causes, thereby enabling a high NOx purification ratio and very low exhaust emissions to be maintained. An ECU calculates a filtered value based on a signal from an exhaust gas concentration sensor, calculates a moving average value of a product of the filtered value and a reference input, calculates a control input such that the moving average value becomes equal to 0, and adds a reference input to the control input to calculate an FB injection amount. The ECU calculates an FF injection amount with a predetermined feedforward control algorithm, and adds the FF injection amount to the FB injection amount, to thereby calculate a urea injection amount.

Exhaust emission control device for internal combustion engine

An exhaust emission control system of an internal combustion engine capable of post injection is disclosed which provides control such that the injection timing in sub injection is set to a point earlier than the target injection timing when the sub injection is started, and the injection timing in the sub injection is then delayed to the target injection timing. This realizes the post injection under the optimum conditions and enables an efficient rise in the exhaust temperature while inhibiting deterioration of the drivability due to a rapid change in torque.

Exhaust emission control system of internal combustion engine

A NOx catalyst for selectively reducing NOx in exhaust gas by adsorbing ammonia is provided at an exhaust system of an engine, ammonia or urea water is supplied to the NOx catalyst by reducing agent supplying means, a consumption amount of ammonia adsorbed to the NOx catalyst is derived by consumption amount deriving means based on an exhaust amount of NOx exhausted from the engine detected or estimated by NOx exhaust amount deriving means and an actual NOx cleaning rate by the NOx catalyst derived by actual NOx cleaning rate deriving means, an actual adsorption amount of ammonia adsorbed to the NOx catalyst is derived in accordance with an addition amount of ammonia and the consumption amount of ammonia by adsorption amount deriving means and the reducing agent supplying means is controlled by controlling means in accordance with the actual adsorption amount.

NOx cleaning apparatus and NOx cleaning method for internal combustion engine

Diesel Particulate Filters (DPFs) having an effectiveness of around 90% reduction of particulate matter (PM) are an essential after-treatment technique in order to meet upcoming PM regulations (Japan2005, Euro4, US07), which are all increasingly stringent. The continuous-regenerating DPF system [1] has been drawing particular attention, because it is possible to significantly simplify the system and reduce costs. The study presented herein investigated the application of a continuous-regenerating DPF system to commercial vehicles. Since exhaust temperatures that are encountered during a significant portion of engine operation are too low to initiate oxidation of PM, a continuously regenerating DPF must employ an oxidation catalyst. However, when the basic characteristics were investigated, an adequate PM oxidation rate was not obtained during city mode operation, during which the exhaust temperature was notably low. Consequently, continuous regeneration did not occur, and it was necessary to utilize active regeneration [2] to forcibly oxidize and remove the PM. Moreover, during high-load operating conditions, when more PM was accumulated on the filter, rapid PM oxidation inside the filter generated an extremely high temperature, resulting in filter breakage. Recently PM combustion phenomena under high temperature in filter is going to be analyzed by using of visual method [3]. In this work, a robust SiC filter [4][5] was used to withstand the high temperatures and prevent black smoke leakage. Next, using SiC filter, an active regeneration method carried out during driving was investigated. In this method, the fuel injection process was modified such that an additional late injection into the cylinder (post-injection) took place. This supplied unburned fuel to the pre-catalyst, and the PM accumulated on the filter was combusted by the heat of oxidation. Therefore, by first achieving controlled catalyst heat-up, which brought the pre-catalyst up to activation temperature (1st stage), followed by controlled filter heat-up by the post-injection process (2nd stage), the temperature became sufficiently high so that the PM was oxidized on the filter, and then regenerated actively. A catalyst temperature feedback method was devised to control the post-injection process, in order to control filter temperature, to suppress abnormal heat-up during active regeneration, and to obtain an acceptable regeneration efficiency. With this control, when active regeneration was initiated during vehicle operation, the resulting filter temperature was very stable, and a good regeneration efficiency is obtained. Based on the above results, a DPF system was suggested for commercial vehicles frequently operated in a city mode, and a high-reliability, active regeneration system was devised. For practical use in the future, there are still significant tasks to be solved, for example, how to remove the ash build-up on the filter. However, a DPF system that offers reduced impact on the environment would hopefully be realized soon.

Development of DPF System for Commercial Vehicle - Basic Characteristic and Active Regenerating Performance -

The valve drive apparatus of the invention comprises an exhaust valve drive mechanism capable of changing an open/close timing of an exhaust valve, and a control device which controls the exhaust valve drive apparatus so as to release the exhaust valve during an intake stroke, independently of an exhaust stroke, in an EGR mode. Preferably, the exhaust valve drive mechanism comprises a first exhaust cam which defines the exhaust valve releasing timing and the amount of valve lift in the exhaust stroke, and a second exhaust cam which defines the exhaust valve releasing timing and the amount of valve lift during the intake stroke. In an normal mode, the displacement of the first exhaust cam is transmitted to the exhaust valve, and in the EGR mode, the displacement of the second exhaust cam is transmitted to the exhaust valve, in addition to the displacement of the first exhaust cam.

Toru Kawatani

Papers

Exhaust emission control system of internal combustion engine

NOx cleaning apparatus and NOx cleaning method for internal combustion engine

Development of DPF System for Commercial Vehicle - Basic Characteristic and Active Regenerating Performance -

Valve drive apparatus of internal-combustion engine

Impact Study of High Biodiesel Blends on Performance of Exhaust Aftertreatment Systems