Abstract: An exhaust emission control device including a selective reduction catalyst; urea water as reducing agent being added in the pipe upstream of the reduction catalyst depurate NOx through reduction; an oxidation catalyst arranged in the pipe upstream of an added position of the urea water, the oxidation catalyst physically adsorbing NOx in the exhaust gas at a temperature lower than a lower active limit temperature of the reduction catalyst and discharging the adsorbed NOx at a temperature higher than a lower active limit temperature of the oxidation catalyst; and a fuel injection device for adding fuel into the exhaust gas upstream of the oxidation catalyst is disclosed. The start of the fuel addition by the fuel injection device is refrained until exhaust temperature on an inlet side of the reduction catalyst is increased to a preset temperature comparable with the lower active limit temperature of the oxidation catalyst.

Abstract: An object of the present invention is to provide a technique with which an amount of reducing agent adsorbed to a selective reduction type NOx catalyst provided in an exhaust passage of an internal combustion engine can be controlled to a target adsorption amount. In an exhaust gas purification system for an internal combustion engine according to the present invention, when a reducing agent adsorption amount adsorbed on a selective reduction type NOx catalyst is held at a target adsorption amount, a reducing agent supply amount supplied from a supply apparatus per unit time is controlled to an amount obtained by adding a predetermined amount to a reduction consumption amount, which is an amount of reducing agent consumed per unit time by the selective reduction type NOx catalyst for NOx reduction.

Abstract: An exhaust gas control apparatus includes a control device controlling a urea addition valve for adding urea from an upstream side of a NOx reduction catalyst. The control device obtains an ammonia adsorption amount distribution through the NOx reduction catalyst. When an ammonia adsorption amount in a predetermined part on a downstream side equals or exceeds a predetermined threshold, the control device controls the urea addition valve to stop the urea supply or reduce the amount thereof. The urea addition valve is controlled based on an adsorption amount distribution obtained from a model on which the catalyst is divided into cells such that an ammonia adsorption amount in a first cell positioned furthest upstream equals or exceeds a predetermined threshold close to a saturation adsorption amount and an ammonia adsorption amount in a second cell positioned downstream of the first cell reaches a predetermined target value smaller than the threshold.

Abstract: To estimate an amount of reducing agent adsorbed to a selective reduction type NOx catalyst with a higher degree of precision, an amount of variation over a predetermined time in a reducing agent amount adsorbed to a selective reduction type NOx catalyst is calculated from an upper limit value of a reducing agent amount that is adsorbed to the selective reduction type NOx catalyst when the reducing agent is supplied continuously by a supply unit, which is calculated on the basis of a temperature of the selective reduction type NOx catalyst, and the reducing agent amount adsorbed to the selective reduction type NOx catalyst, whereupon a reducing agent amount adsorbed to the selective reduction type NOx catalyst following the elapse of the predetermined time is estimated by adding the variation amount to the reducing agent amount adsorbed to the selective reduction type NOx catalyst.

Abstract: The purpose of the present invention is to suppress degradation of a PM sensor and a decrease in detection accuracy of the amount of PM in a configuration in which a urea addition unit and a selective reduction-type NOx catalyst (NOx catalyst) are provided downstream of a particulate filter (filter) in an internal combustion engine exhaust passage, the PM sensor being disposed downstream of the filter. According to the present invention, in an exhaust passage (2) of an internal combustion engine (1), a first NOx catalyst (4) and a second NOx catalyst (5) are disposed downstream of a filter (3) successively from the upstream side along the flow of exhaust. A urea addition unit (6) is disposed between the filter (3) and the first NOx catalyst (4). A PM sensor (7) is disposed between the first NOx catalyst (4) and the second NOx catalyst (5).

Abstract: An exhaust gas purification system is equipped with a burner in an exhaust passage upstream of an exhaust gas purification apparatus and having a burner combustion chamber in which flame is produced. When the temperature of the exhaust gas purification apparatus is raised, the burner produces flame that extends from the interior of the burner combustion chamber to the interior of the exhaust passage when the flow rate of the exhaust gas is not higher than a predetermined flow rate, and the burner causes the size of the flame to be smaller than when it is determined that the flow rate of the exhaust gas is not higher than the predetermined flow rate or to produce flame only in the interior of the burner combustion chamber when it is determined that the flow rate of exhaust gas is higher than the predetermined flow rate.

Abstract: An exhaust gas purification device for an internal combustion engine purifies exhaust gas in a first exhaust path and a second exhaust path. The device includes a confluent path. The confluent path extends from a confluent section of the first exhaust path and the second exhaust path. A first auxiliary NOx catalyst is provided in the first exhaust path. A second auxiliary NOx catalyst is provided in the second exhaust path. A main NOx catalyst is provided in the confluent path. A first addition section adds an ammonia source in a first addition amount to a section upstream of the first auxiliary NOx catalyst to supply urea water to the first auxiliary NOx catalyst. A second addition section adds an ammonia source in a second addition amount to a section upstream of the second auxiliary NOx catalyst to supply urea water to the second auxiliary NOx catalyst.

Abstract: To estimate an amount of reducing agent adsorbed to a selective reduction type NOx catalyst with a higher degree of precision while maintaining a condition in which NOx can be purified by the selective reduction type NOx catalyst, the present invention includes: an upper limit value calculation unit that calculates an upper limit value of a reducing agent amount that is adsorbed to the selective reduction type NOx catalyst when the reducing agent is supplied continuously during a steady state operation in an internal combust ion engine; and an estimation unit that estimates an upper limit value calculated by the upper limit value calculation unit when the reducing agent is supplied for at least a predetermined time during the steady state operation in the internal combustion engine to be the reducing agent amount adsorbed to the selective reduction type NOx catalyst at that time.

Abstract: An object of the present invention is to provide a technique with which an amount of reducing agent adsorbed to a selective reduction type NOx catalyst provided in an exhaust passage of an internal combustion engine can be controlled to a target adsorption amount. In an exhaust gas purification system for an internal combustion engine according to the present invention, when a reducing agent adsorption amount adsorbed on a selective reduction type NOx catalyst is held at a target adsorption amount, a reducing agent supply amount supplied from a supply apparatus per unit time is controlled to an amount obtained by adding a predetermined amount to a reduction consumption amount, which is an amount of reducing agent consumed per unit time by the selective reduction type NOx catalyst for NOx reduction.

Abstract: To estimate an amount of reducing agent adsorbed to a selective reduction type NOx catalyst with a higher degree of precision, an amount of variation over a predetermined time in a reducing agent amount adsorbed to a selective reduction type NOx catalyst is calculated from an upper limit value of a reducing agent amount that is adsorbed to the selective reduction type NOx catalyst when the reducing agent is supplied continuously by a supply unit, which is calculated on the basis of a temperature of the selective reduction type NOx catalyst, and the reducing agent amount adsorbed to the selective reduction type NOx catalyst, whereupon a reducing agent amount adsorbed to the selective reduction type NOx catalyst following the elapse of the predetermined time is estimated by adding the variation amount to the reducing agent amount adsorbed to the selective reduction type NOx catalyst.

Abstract: An exhaust gas purification device for an internal combustion engine purifies exhaust gas in a first exhaust path and a second exhaust path. The device includes a confluent path. The confluent path extends from a confluent section of the first exhaust path and the second exhaust path. A first auxiliary NOx catalyst is provided in the first exhaust path. A second auxiliary NOx catalyst is provided in the second exhaust path. A main NOx catalyst is provided in the confluent path. A first addition section adds an ammonia source in a first addition amount to a section upstream of the first auxiliary NOx catalyst to supply urea water to the first auxiliary NOx catalyst. A second addition section adds an ammonia source in a second addition amount to a section upstream of the second auxiliary NOx catalyst to supply urea water to the second auxiliary NOx catalyst.

Abstract: An exhaust purifying device for an internal combustion engine which can restrict an influence of a measurement error in a NOx sensor provided at the downstream side of a catalyst and can optimally maintain a NOx purifying rate. The device includes a catalytic converter carrying a selective catalytic reduction catalyst provided in an exhaust passage of the engine to selectively reduce nitrogen oxides, a urea water adding valve for adding urea water to the catalyst as a reducing agent, a NOx sensor provided at the downstream side of the catalyst, and an ECU for adjusting an addition amount of the urea water adding valve based upon output of the NOx sensor, wherein a urea water addition amount adjusting process is executed under a condition that a NOx amount to be generated in the engine increases.

Abstract: An object of the present invention is to increase the flexibility in the layout of an exhaust gas purification system for an internal combustion engine including selective catalytic reduction catalyst provided in an exhaust passage of the internal combustion engine and an addition device for supplying reducing agent derived from ammonia to the selective catalytic reduction catalyst, without a deterioration of the performance in reducing nitrogen oxides. To achieve the object, the exhaust gas purification system for an internal combustion engine according to the present invention is configured to supply hydrocarbon at the same time when reducing agent derived from ammonia is supplied to the selective catalytic reduction catalyst, thereby producing reducing agent that is hard to be oxidized by a precious metal catalyst.

Abstract: The purpose of the present invention is to suppress degradation of a PM sensor and a decrease in detection accuracy of the amount of PM in a configuration in which a urea addition unit and a selective reduction-type NOx catalyst (NOx catalyst) are provided downstream of a particulate filter (filter) in an internal corn engine exhaust passage, the PM sensor being disposed downstream of the filter. According to the present invention, in an exhaust passage (2) of an internal combustion engine (1), a first NOx catalyst (4) and a second NOx catalyst (5) are disposed downstream of a fitter (3) successively from the upstream side along the flow of exhaust. A urea addition unit (6) is disposed between the filter (3) and the first NOx catalyst (4). A PM sensor (7) is disposed between the first NOx catalyst (4) and the second NOx catalyst (5).

Abstract: An exhaust gas control apparatus includes a control device controlling a urea addition valve for adding urea from an upstream side of a NOx reduction catalyst. The control device obtains an ammonia adsorption amount distribution through the NOx reduction catalyst. When an ammonia adsorption amount in a predetermined part on a downstream side equals or exceeds a predetermined threshold, the control device controls the urea addition valve to stop the urea supply or reduce the amount thereof. The urea addition valve is controlled based on an adsorption amount distribution obtained from a model on which the catalyst is divided into cells such that an ammonia adsorption amount in a first cell positioned furthest upstream equals or exceeds a predetermined threshold close to a saturation adsorption amount and an ammonia adsorption amount in a second cell positioned downstream of the first cell reaches a predetermined target value smaller than the threshold.

Abstract: Utilizing the finding that the state of adsorption of NH3 on a selective reduction type NOx catalyst includes a weakly adsorbed state in which the adsorbed NH3 is useful for a reduction reaction of NOx and a strongly adsorbed state in which the adsorbed NH3 is not useful for the reduction reaction of NOx unless the state of adsorption is changed into the weakly adsorbed state, the apparatus of the invention includes an actual weakly-adsorbed amount-calculation NH3 that is adsorbed on the selective reduction type NOx catalyst in the weakly adsorbed state, and a dispensation control portion that performs a dispensation control of the reductant dispensed by a reductant-dispensation portion, according to the actual weakly adsorbed amount calculated by the actual weakly adsorbed amount calculation portion.

Abstract: The present invention provides an exhaust purification apparatus for an internal combustion engine which enables a decrease in NOx purification rate and possible ammonia slip to be inhibited. The apparatus includes an NOx catalyst, a urea aqueous solution addition valve serving as reducing agent adding means, and NOx sensors provided an inlet and an outlet of the NOx catalyst, respectively. When the bed temperature of the NOx catalyst is in a predetermined high-temperature region in which the amount of ammonia converted into NOx increases relatively and an NOx purification rate decreases relatively, the apparatus uses outputs from the NOx sensors to perform correction such that the actual addition amount of the urea aqueous solution addition valve reaches a target addition amount.

Abstract: An internal combustion engine, in which an NOX selective reducing catalyst (15) is arranged inside an engine exhaust passage, and aqueous urea stored in an aqueous urea tank (20) is fed to the NOX selective reducing catalyst (15) to selectively reduce the NOX. The aqueous urea tank (20) comprises a main tank (20a) and a sub tank (20b) arranged inside the main tank (20a). The aqueous urea in the sub tank (20b) is sent to an aqueous urea feed valve (17). When the aqueous urea tank (20) should be refilled with aqueous urea, the sub tank (20b) is refilled with aqueous urea. It is detected by a level sensor (40) if the aqueous urea in the aqueous urea tank (20) is refilled. When it is judged that the NOX purification rate falls below an allowable level at the time of engine operation right after the aqueous urea in the aqueous urea tank (20) has been refilled, it is judged that the refilled aqueous urea is abnormal.

Abstract: Utilizing the finding that the state of adsorption of NH3 on a selective reduction type NOx catalyst includes a weakly adsorbed state in which the adsorbed NH3 is useful for a reduction reaction of NOx and a strongly adsorbed state in which the adsorbed NH3 is not useful for the reduction reaction of NOx unless the state of adsorption is changed into the weakly adsorbed state, the apparatus of the invention includes an actual weakly-adsorbed amount-calculation NH3 that is adsorbed on the selective reduction type NOx catalyst in the weakly adsorbed state, and a dispensation control portion that performs a dispensation control of the reductant dispensed by a reductant-dispensation portion, according to the actual weakly adsorbed amount calculated by the actual weakly adsorbed amount calculation portion.

Abstract: A technique that, in an exhaust gas purification apparatus of an internal combustion engine, can avoid a decrease in a NOx purification rate by adding a reducing agent as continuously as possible, while avoiding NH3 from passing through a selective reduction type NOx catalyst to a downstream side thereof. The selective reduction type NOx catalyst has an active spot which purifies NOx by the use of NH3, and an adsorption site which adsorbs NH3, wherein a vicinity site, which is located in the vicinity of the active spot, and a distant site, which is located distant from the active spot, exist in the adsorption site. The addition of the reducing agent from the reducing agent addition part is controlled based on the desorption rate of NH3 in the vicinity site so as to continue to cause the NH3 adsorbed to the vicinity site to exist.