Method and device for controlling the injection of reducing agent

A method for controlling injection of a reducing agent upstream from a catalyst in an exhaust line from a combustion engine, the method comprising:

• calculating an accumulation actual value (A1) representative of a current accumulation in the catalyst of a reducing substance forming part of or formed by the reducing agent based on information from a computation model, wherein the model takes into account expected reactions in the catalyst under prevailing operating conditions, and the model continuously determines the current state of the catalyst,
• calculating an accumulation setpoint value (A2) based on an emission setpoint value (E2) and information from the computation model, wherein the emission setpoint value (E2) is representative of a desired content, in exhaust gases leaving the catalyst, of an exhaust gas substance which, as the exhaust gases pass through the catalyst, is at least partly removed from the exhaust gases by the action of the reducing substance or formed by the action of the reducing substance, and the accumulation setpoint value (A2) is representative of the reducing substance accumulation required in the catalyst under prevailing operating conditions for substantially achieving the emission setpoint value (E2),
• comparing the accumulation actual value (A1) with the accumulation setpoint value (A2) by supplying the accumulation actual value (A1) and the accumulation setpoint value (A2) to a first comparator, which emits a signal (S1) to a first regulator, wherein the signal (S1) depends on the conformity between the accumulation actual value (A1) and the accumulation setpoint value (A2),
• controlling the injection of reducing agent in the exhaust line based on the comparison between the accumulation actual value (A1) and the accumulation setpoint value (A2) by emitting a control signal (S2) from the first regulator based on the signal from the comparator for controlling the injection of reducing agent in the exhaust line based on the control signal (S2).

A method for controlling injection of a reducing agent upstream from a catalyst in an exhaust line from a combustion engine ,the method comprising:

• calculating an accumulation actual value (A1) representative of a current accumulation in the catalyst of a reducing substance forming part of or formed by the reducing agent based on information from a computation model, wherein the model takes into account expected reactions in the catalyst under prevailing operating conditions, and the model continuously determines the current state of the catalyst,
• calculating an accumulation setpoint value (A2) based on an emission setpoint value (E2) and information from the computation model, wherein the emission setpoint value (E2) is representative of a desired content, in exhaust gases leaving the catalyst, of an exhaust gas substance which, as the exhaust gases pass through the catalyst, is at least partly removed from the exhaust gases by the action of the reducing substance or formed by the action of the reducing substance, and the accumulation setpoint value (A2) is representative of the reducing substance accumulation required in the catalyst under prevailing operating conditions for substantially achieving the emission setpoint value (E2),
• comparing the accumulation actual value (A1) with the accumulation setpoint value (A2), and
• controlling the injection of reducing agent in the exhaust line based on the comparison between the accumulation actual value (A1) and the accumulation setpoint value (A2)
• determining an emission actual value (E1) by calculation or measurement, wherein the emission actual value (E1) is representative of the current content of the exhaust gas substance in the exhaust gases leaving the catalyst,
• comparing the emission actual value (E1) with the emission setpoint value (E2),
• supplying the emission actual value (E1) and the emission setpoint value (E2) to a second comparator which emits a regulator signal (S3) to a second regulator, wherein the regulator signal (S3) depends on the conformity between the emission actual value (E1) and the emission setpoint value (E2), and emitting a control signal (fSP) from the second regulator based on the signal from the second comparator, wherein the control signal (fSP) affects a calculation of the accumulation setpoint value (A2) and calculating the accumulation setpoint value (A2) on information from the computation model and the conformity between the emission actual value (E1) and the emission setpoint value (E2).

A method for controlling injection of a reducing agent upstream from a catalyst in an exhaust line from a combustion engine, the method comprising:

• calculating an accumulation actual value (A1) representative of a current accumulation in the catalyst of a reducing substance forming part of or formed by the reducing agent based on information from a computation model, wherein the model takes into account expected reactions in the catalyst under prevailing operating conditions, and the model continuously determines the current state of the catalyst,
• calculating an accumulation setpoint value (A2) based on an emission setpoint value (E2) and information from the computation model, wherein the emission setpoint value (E2) is representative of a desired content, in exhaust gases leaving the catalyst, of an exhaust gas substance which, as the exhaust gases pass through the catalyst, is at least partly removed from the exhaust gases by the action of the reducing substance or formed by the action of the reducing substance, and the accumulation setpoint value (A2) is representative of the reducing substance accumulation required in the catalyst under prevailing operating conditions for substantially achieving the emission setpoint value (E2), obtaining the accumulation setpoint value (A2) by multiplying a first multiplication factor in the form of a calculated accumulation maximum value (Amax) which is representative of the maximum permissible reducing substance accumulation in the catalyst under prevailing operating conditions, with a second multiplication factor which depends on the conformity between the emission actual value (E1) and the emission setpoint value (E2)
• comparing the accumulation actual value (A1) with the accumulation setpoint value (A2), and
• controlling the injection of reducing agent in the exhaust line based on the comparison between the accumulation actual value (A1) and the accumulation setpoint value (A2)
• determining an emission actual value (E1) by calculation or measurement, wherein the emission actual value (E1) is representative of the current content of the exhaust gas substance in the exhaust gases leaving the catalyst,
• comparing the emission actual value (E1) with the emission setpoint value (E2), and
• calculating the accumulation setpoint value (A2) on information from the computation model and the conformity between the emission actual value (E1) and the emission setpoint value (E2).