Controller for exhaust gas purification system

Abstract

A NOx storage reduction type catalyst is equipped in an exhaust passage of an internal combustion engine and purifies NOx in exhaust gas. An ozone supply device supplies ozone to an upstream of the catalyst in the exhaust passage. A NOx sensor is provided at a downstream of the catalyst and detects a NOx amount in exhaust gas. An ECU includes a NOx amount acquisition unit which acquires a detected NOx amount detected by the NOx sensor in a state where the internal combustion engine operates and where the ozone supply device supplies the ozone. The ECU further includes a control unit which performs at least one of an ozone supply amount control by the ozone supply device and an abnormality diagnosis of the ozone supply device based on the detected NOx amount acquired by the NOx amount acquisition unit.

1 . A controller applicable to an exhaust gas purification system which includes a NOx storage reduction type catalyst equipped in an exhaust passage of an internal combustion engine and configured to purify NOx in exhaust gas, an ozone supply device configured to supply ozone to an upstream of the catalyst in the exhaust passage, and a NOx sensor provided at a downstream of the catalyst and configured to detect a NOx amount in exhaust gas, the controller for the exhaust gas purification system comprising:
 a NOx amount acquisition unit configured to acquire a detected NOx amount detected by the NOx sensor in a state where the internal combustion engine operates and where the ozone supply device supplies the ozone;   a calculation unit configured to calculate an amount of NOx discharged to a downstream of the catalyst as an estimated NOx amount based on at least one of exhaust gas information about exhaust gas discharged from the internal combustion engine and catalyst information about the catalyst; and   a control unit configured to implement comparison of the detected NOx amount acquired by the NOx amount acquisition unit with the estimated NOx amount calculated by the calculation unit and to perform at least one of an ozone supply amount control by the ozone supply device and an abnormality diagnosis of the ozone supply device based on a result of the comparison.   
     
     
         2 . The controller for the exhaust gas purification system according to  claim 1 , wherein
 the calculation unit is configured to use an exhaust gas parameter, which is at least one of an amount of NOx discharged from the internal combustion engine, a flow rate of the exhaust gas, and a temperature of the exhaust gas, as the exhaust gas information and to calculate the estimated NOx amount based on the exhaust gas parameter.   
     
     
         3 . The controller for the exhaust gas purification system according to  claim 1 , wherein
 the calculation unit is configured to use a catalyst parameter, which is at least one of a temperature of the catalyst and a NOx storage amount which indicates an amount of NOx stored in the catalyst, as the catalyst information and to calculate the estimated NOx amount based on the catalyst parameter.   
     
     
         4 . The controller for the exhaust gas purification system according to  claim 1 , further comprising:
 an ozone amount acquisition unit configured to acquire an amount of the ozone supplied to the exhaust passage by the ozone supply device, wherein   the calculation unit is configured to calculate the estimated NOx amount based on at least one of the exhaust gas information and the catalyst information and based on the ozone amount acquired by the ozone amount acquisition unit.   
     
     
         5 . The controller for the exhaust gas purification system according to  claim 1 , wherein
 the control unit is configured to perform the ozone supply amount control by the ozone supply device out of the ozone supply amount control by the ozone supply device and the abnormality diagnosis of the ozone supply device, when a difference value obtained by a subtraction of the estimated NOx amount calculated by the calculation unit from the detected NOx amount acquired by the NOx amount acquisition unit is smaller than a predetermined value, and   the control unit is configured to perform the abnormality diagnosis out of the ozone supply amount control by the ozone supply device and the abnormality diagnosis of the ozone supply device, when the difference value is larger than the predetermined value.   
     
     
         6 . The controller for the exhaust gas purification system according to  claim 1 , wherein
 the control unit is configured to control an amount of the ozone supplied by the ozone supply device based on the detected NOx amount acquired by the NOx amount acquisition unit in a range of the ozone supply amount to a predetermined upper limit value, and to perform the abnormality diagnosis of the ozone supply device in a case where the amount of the ozone supplied by the ozone supply device is the upper limit value.   
     
     
         7 . A controller applicable to an exhaust gas purification system which includes a NOx storage reduction type catalyst equipped in an exhaust passage of an internal combustion engine and configured to purify NOx in exhaust gas, an ozone supply device configured to supply ozone to an upstream of the catalyst in the exhaust passage, and a NOx sensor provided at a downstream of the catalyst and configured to detect a NOx amount in exhaust gas, the controller for the exhaust gas purification system comprising:
 a NOx amount acquisition unit configured to acquire a detected NOx amount detected by the NOx sensor in a state where the internal combustion engine operates and where the ozone supply device supplies the ozone; and   a control unit configured to perform at least one of an ozone supply amount control by the ozone supply device and an abnormality diagnosis of the ozone supply device based on the detected NOx amount acquired by the NOx amount acquisition unit, wherein,   the control unit is configured to control an amount of the ozone supplied by the ozone supply device based on the detected NOx amount acquired by the NOx amount acquisition unit in a range of the ozone supply amount to a predetermined upper limit value and to perform the abnormality diagnosis of the ozone supply device in a case where the amount of the ozone supplied by the ozone supply device is the upper limit value.