Method and control device for controlling a regeneration process of an exhaust gas particle filter

Abstract

The invention relates to a method ( 61 ) for controlling a regeneration process of an exhaust gas particle filter ( 41 ) of an internal combustion engine ( 11 ), wherein said method ( 61 ) comprises safeguards ( 71 ) for protecting said exhaust gas particle filter ( 41 ) from overheating and when implementing said safeguards ( 71 ) a gas flow (m a ) of the gas flowing through the exhaust gas particle filter ( 41 ) is reduced ( 71 a, 71 b ) for the purpose of restricting a reaction rate of an exothermal reaction taking place in said exhaust gas particle filter ( 41 ) during the regeneration process. In order to allow for an efficient regeneration of an exhaust gas particle filter ( 41 ) and still avoid damage to or the destruction of said exhaust gas particle filter ( 41 ) as a result of the overheating thereof, the invention is characterized in that during the regeneration process an instantaneous value (x(t)), which characterizes an instantaneous mass (x) of the soot situated in the exhaust gas particle filter ( 41 ), is ascertained, a check ( 67 ) is made as a function of the instantaneous value (x(t)) to determine whether said exhaust gas particle filter ( 41 ) is in an uncritical operating state and said safeguards ( 71 ) are suppressed in the event that the uncritical operating state is present.

1 . Method for controlling a regeneration process of an exhaust gas particle filter of an internal combustion engine, wherein said method comprises safeguards for protecting the exhaust gas particle filter from overheating and when implementing said safeguards a gas flow of gas flowing through the exhaust gas particle filter is reduced for the purpose of restricting a reaction rate of an exothermal reaction taking place in the exhaust gas particle filter during the regeneration process, wherein an instantaneous value, which characterizes an instantaneous mass of the soot situated in the exhaust gas particle filter, is ascertained during the regeneration process, a check is made as a function of said instantaneous value to determine whether the exhaust gas particle filter is in an uncritical operating state and said safeguards are suppressed in the event that said uncritical operating state is present. 
     
     
         2 . The method according to  claim 1 , wherein the uncritical operating state is recognized in the event that the instantaneous value is smaller than a predetermined minimum value. 
     
     
         3 . The method according to  claim 1 , wherein the uncritical operating state is recognized in the event that a gas temperature of the gas flowing into the exhaust gas particle filter is lower than a predetermined first minimum temperature. 
     
     
         4 . The method according to  claim 2 , wherein an initial value is ascertained, which characterizes the mass of the soot situated in the exhaust gas particle filter before the beginning of the regeneration process, and a check is made as a function of said initial value to determine whether the reaction rate is anticipated to be too high, and the safeguards are only then implemented in the event that the check resulted in the reaction rate being anticipated to be too high. 
     
     
         5 . The method according to  claim 1 , wherein the gas flow is reduced to avoid a cooling of the exhaust gas particle filter in the event that the gas temperature is lower than a predetermined second minimum temperature. 
     
     
         6 . The method according to  claim 1 , wherein the gas flow is manipulated by positioning actuating elements of an air and exhaust gas system of the internal combustion engine, preferably by adjusting a degree of opening of a throttle device and/or of an exhaust gas recirculation valve assembly. 
     
     
         7 . The method according to  claim 1 , wherein the instantaneous value is ascertained as a function of at least one state variable, which characterizes an operating state of the internal combustion engine, preferably as a function of an exhaust gas temperature, an oxygen concentration and/or a mass flow of the gas flowing into the exhaust gas particle filter. 
     
     
         8 . The method according to  claim 7 , wherein the instantaneous value is ascertained in steps by said instantaneous value being recalculated in regular intervals as a function of its current value and the at least one state variable. 
     
     
         9 . The method according to  claim 1 , wherein the method is executed while the internal combustion engine is operating in the overrun mode. 
     
     
         10 . Control unit for the open-loop and/or closed-loop control of an internal combustion engine, which has an exhaust gas system with an exhaust gas particle filter, said control unit being equipped for controlling a regeneration process of the exhaust gas particle filter such that it can implement safeguards for protecting said exhaust gas particle filter from overheating, a gas flow of gas flowing through said exhaust gas particle filter being reduced when implementing said safeguards for the purpose of restricting a reaction rate of an exothermal reaction taking place in said exhaust gas particle filter during the regeneration process, wherein said control unit is equipped such that during the regeneration process an instantaneous value, which characterizes an instantaneous mass of the soot situated in said exhaust gas particle filter, is ascertained, a check is made as a function of said instantaneous value to determine whether said exhaust gas particle filter is in an uncritical operating state and said safeguards are suppressed in the event that the uncritical operating state is present. 
     
     
         11 . The control unit according to  claim 10 , wherein it is equipped, preferably is programmed, for executing a method according to  claim 1 .