Toyota Jidosha Kabushiki Kaisha

Yuriko Hagimoto

Hiromasa Nishioka

Yuji Miyoshi

Kenji Furui

Takeru Shirasawa

Toru Kidokoro

Makoto Ogiso

Junichi Matsuo

Yoshihisa Tsukamoto

Yasumasa Notake

Ryohei Ono

Hirotaka Saitoh

Ryohei Ohno

An exhaust gas control system includes a NSR catalyst, a fuel supply valve, a SCR catalyst an addition device, and an electronic control unit. When temperature of NSR catalyst is in a range of a predetermined first temperature range and temperature of SCR catalyst is in a range of a predetermined second temperature range, the electronic control unit is configured to add additive with the addition device, and execute predetermined air-fuel ratio processing to control the air-fuel ratio of exhaust gas flowing into the NSR catalyst. In the predetermined air-fuel ratio processing, the electronic control unit is configured to execute a second air-fuel ratio processing after a first air-fuel ratio processing, and execute the third air-fuel ratio processing after a first air-fuel ratio processing and the second air-fuel ratio processing and in succession to the second air-fuel ratio processing.

Exhaust gas control system for internal combustion engine and control method for exhaust gas control system

When the temperature of an NSR catalyst belongs to a specified NSR temperature range and the temperature of an SCR catalyst belongs to a specified SCR temperature range, urea water is added, and specified air-fuel ratio processing relating to an air-fuel ratio of exhaust gas flowing into the NSR catalyst is executed. The specified air-fuel ratio processing includes i) a first air-fuel ratio processing to cause the air-fuel ratio of the exhaust gas flowing into the NSR catalyst to be a first lean air-fuel ratio that causes emission of occluded NOx from the NSR catalyst and ii) a second air-fuel ratio processing to cause the air-fuel ratio of the exhaust gas to be a second lean air-fuel ratio leaner than the first lean air-fuel ratio. In the specified air-fuel ratio processing, the first air-fuel ratio processing and the second air-fuel ratio processing are alternately repeated.

Exhaust gas control system for internal combustion engine

An object is to prevent abrasion inside an addition valve and clogging of the addition valve due to an increase in the particle diameter of precipitates. A first control is performed by which a pump is caused to operate in such a way as to return urea solution contained in the addition valve and a urea solution channel to a tank by a predetermined quantity. After the lapse of a certain time after the end of the first control, a second control is performed by which the pump is caused to operate in such a way as to return the urea solution remaining in the addition valve and the urea solution channel thoroughly to the tank.

Exhaust gas purification apparatus for internal combustion engine

Embodiments of the present disclosure may estimate the amount of ammonia adsorbed in an SCR catalyst as accurately as possible. The ammonia adsorption amount is calculated by integrating the quantity of ammonia supplied to the SCR filter, the quantity of ammonia consumed in reduction of NOx in the SCR catalyst, and the quantity of ammonia desorbed from the SCR catalyst. In the calculation, a differential pressure change rate defined as the increase in a converted differential pressure value per unit increase in the filter PM deposition amount is referred to. The ammonia desorption quantity is calculated in such a way that the calculated value of the ammonia desorption quantity is made smaller when the differential pressure change rate is smaller than a predetermined threshold than when the differential pressure change rate is equal to or higher than the predetermined threshold.

Ammonia adsorption amount estimation apparatus, ammonia adsorption amount estimation method, and exhaust gas purification system for internal combustion engine

An object of the present invention is to distinguish and detect an abnormality of SCRF and an abnormality of a diffusing device in a system in which a diffusing device is provided for an exhaust gas passage between a filter (SCRF) including an SCR catalyst carried thereon and a reducing agent addition valve. In the present invention, it is judged that which one of abnormalities of any clogging-up of SCRF caused by PM, any breakage of SCRF, and any abnormality of a diffusing device occurs, on the basis of at least any one of a difference between a NOx purification rate of an SCR catalyst carried on SCRF and a predetermined NOx purification rate and a difference between a PM amount flowing out from SCRF and a predetermined outflow PM amount, when a difference, which is provided between an exhaust gas pressure difference as a difference between an exhaust gas pressure on an upstream side from a reducing agent addition valve and an exhaust gas pressure on a downstream side from SCRF and a predetermined exhaust gas pressure difference, exceeds a certain amount.

Abnormality detection device for exhaust gas purification apparatus

An object of the disclosure is to adjust the ammonia adsorption amount in an SCR catalyst supported on an SCR filter as close as possible to a target adsorption amount in an exhaust gas purification system including the SCR filter. In a system according to the disclosure, the quantity of ammonia supplied by an ammonia supplier is made smaller when a differential pressure change rate at the time when ammonia is supplied by the ammonia supplier is lower than a predetermined threshold than when the differential pressure change rate at the time when ammonia is supplied by the ammonia supplier is equal to or higher than the predetermined threshold. Moreover, when the differential pressure change rate is lower than the predetermined threshold, the change in the quantity of ammonia supplied by the ammonia supplier relative to the change in the filter PM deposition amount is kept equal to zero.

Exhaust gas purification system for an internal combustion engine

The abnormality of an NHsensor is judged highly accurately. For this purpose, an abnormality judging system for an exhaust gas purification apparatus of an internal combustion engine comprises a selective catalytic reduction NOx catalyst which is provided at an exhaust gas passage of the internal combustion engine and which reduces NOx by using NHas a reducing agent, a supply device which supplies the reducing agent from an upstream side from the NOx catalyst, a NOx sensor which detects NOx and NHon a downstream side from the NOx catalyst, and an NHsensor which detects NHon a downstream side from the NOx catalyst, wherein it is judged that the NHsensor has any abnormality if an absolute value of a difference between an estimated NHconcentration as a difference between a detection value of the NOx sensor and an estimated value of a NOx concentration and an NHconcentration detected by the NHsensor is not less than a threshold value when NHflows out from the selective catalytic reduction NOx catalyst.

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Susono, Japan

Yuriko Hagimoto