Back to results
US 2011/0296905 A1Published application
Method for monitoring an scr catalytic converter
AssigneeRobert Bosch GmbH
InventorsArthur Bastoreala, Alexander Franz, Tobias Pfister
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeRobert Bosch GmbH
InventorsArthur Bastoreala, Alexander Franz, Tobias Pfister
Estimating the term…
A method is provided for monitoring an SCR catalytic converter (12), in which method the NH3 storage capacity of the SCR catalytic converter (12) is monitored. The SCR catalytic converter (12) is initially filled in an overdosing phase with a superstoichiometric reducing agent dosing up to the maximum NH3 storage capacity. The catalytic converter is subsequently acted on in an underdosing phase with a reducing agent dosing which is reduced in relation to a normal dosing or is absent. The NH3 storage capacity is indirectly determined during the underdosing phase by determining at least one characteristic value which is dependent on the NOx conversion rate. According to the invention, to detect NH3 slippage (25), which indicates the transition from the overdosing phase to the underdosing phase, a variable which is characteristic of the NOx conversion is continuously measured during the overdosing phase, and in the event of a fall in the NOx conversion, it is inferred that NH3 slippage (25) is present.
A method for monitoring an SCR catalytic converter (12), in which method the NH3 storage capacity of the SCR catalytic converter (12) is monitored, with the SCR catalytic converter (12) initially being filled in an overdosing phase with a superstoichiometric reducing agent dosing up to the maximum NH3 storage capacity, subsequently being acted on in an underdosing phase with a reducing agent dosing which is reduced in relation to a normal dosing or is absent, and with the NH3 storage capacity being indirectly determined during the underdosing phase by determining at least one characteristic value which is dependent on the NOx conversion rate, characterized by continuously measuring, during the overdosing phase, a variable which is characteristic of the NOx conversion, and inferring that NH3 slippage (25) is present, indicating a transition from the overdosing phase to the underdosing phase, when the NOx conversion falls.
A computer program executed on a computer or a control unit (19) for carrying out a method of monitoring an SCR catalytic converter (12), in which method the NH3 storage capacity of the SCR catalytic converter (12) is monitored, with the SCR catalytic converter (12) initially being filled in an overdosing phase with a superstoichiometric reducing agent dosing up to the maximum NH3 storage capacity, subsequently being acted on in an underdosing phase with a reducing agent dosing which is reduced in relation to a normal dosing or is absent, and with the NH3 storage capacity being indirectly determined during the underdosing phase by determining at least one characteristic value which is dependent on the NOx conversion rate, characterized by continuously measuring a variable which is characteristic of the NOx conversion during the overdosing phase, and inferring that NH3 slippage (25) is present, indicating a transition from the overdosing phase to the underdosing phase, when the NOx conversion falls.
A computer program product having program code for execution executed on a computer or a control unit (19), the program code stored on a machine-readable carrier for carrying out a method of monitoring an SCR catalytic converter (12), in which method the NH3 storage capacity of the SCR catalytic converter (12) is monitored, with the SCR catalytic converter (12) initially being filled in an overdosing phase with a superstoichiometric reducing agent dosing up to the maximum NH3 storage capacity, subsequently being acted on in an underdosing phase with a reducing agent dosing which is reduced in relation to a normal dosing or is absent, and with the NH3 storage capacity being indirectly determined during the underdosing phase by determining at least one characteristic value which is dependent on the NOx conversion rate, characterized by continuously measuring a variable which is characteristic of the NOx conversion during the overdosing phase, and inferring that NH3 slippage (25) is present, indicating a transition from the overdosing phase to the underdosing phase, when the NOx conversion falls.
Dependencies are inferred from the claim text.