Method and Device for Controlling a Secondary Air Mass Flow in a Secondary Air Supply of an Internal Combustion Engine

Abstract

A method for controlling a secondary air mass flow in a secondary air supply of an internal combustion engine. The internal combustion engine comprises the secondary air supply, a device for determining a pressure in the secondary air supply, and an exhaust gas lambda sensor for determining a current exhaust gas lambda value. The method includes a) determining a first secondary air mass flow) related to the effective throttle area using a throttle equation and depending on a pressure in the secondary air supply, b) determining a second secondary air mass flow based on the measured exhaust gas lambda value and taking into account a primary air mass flow of the internal combustion engine and a supplied fuel mass flow, c) deriving an effective throttle area from the first secondary air mass flow determined in step a) and the second secondary air mass flow determined in step b), and d) controlling the secondary air mass flow in the secondary air supply using the effective throttle area determined in step c) or a quantity derived therefrom.

What is claimed is: 
     
         1 . A method for controlling a secondary air mass flow in a secondary air supply of an internal combustion engine, wherein the internal combustion engine comprises the secondary air supply, a device for determining a pressure in the secondary air supply, and an exhaust gas lambda sensor for determining a current exhaust gas lambda value, the method comprising:
 a) determining a first secondary air mass flow related to the effective throttle area using a throttle equation and depending on a pressure in the secondary air supply;   b) determining a second secondary air mass flow based on the measured exhaust gas lambda value and taking into account a primary air mass flow of the internal combustion engine and a supplied fuel mass flow;   c) deriving an effective throttle area from the first secondary air mass flow determined in step a) and the second secondary air mass flow determined in step b); and   d) controlling the secondary air mass flow in the secondary air supply using the effective throttle area determined in step c) or a variable derived therefrom.   
     
     
         2 . The method according to  claim 1 , wherein the first secondary air mass flow in step a) is determined by way of the throttle equation, which relates the first secondary air mass flow to the pressure in the secondary air supply and the effective throttle area. 
     
     
         3 . The method according to  claim 1 , wherein the effective throttle area in step c) is derived using a mass flow balance depending on an exhaust gas lambda value. 
     
     
         4 . The method according to  claim 1 , wherein the effective throttle area in step c) is derived in consideration of the time dynamics of the exhaust gas lambda probe. 
     
     
         5 . The method according to  claim 1 , wherein the effective throttle area in step c) is derived using the recursive Least Mean Square method or the recursive Normalized Least Mean Square method. 
     
     
         6 . The method according to  claim 5 , wherein the difference between the secondary air mass flow derived from the pressure and the secondary air mass flow derived from the exhaust gas lambda value is used as the error term of the recursive Least Mean Square method or the recursive Normalized Least Mean Square method. 
     
     
         7 . The method according to  claim 1 , wherein the secondary air mass flow is controlled as a function of an actual value of the secondary air mass flow determined using the effective throttle area. 
     
     
         8 . The method according to  claim 1 , wherein the secondary air mass flow is controlled as a function of an actual value of the secondary air mass flow, which is derived from the first secondary air mass flow related to the effective throttle area and the effective throttle area determined in step c). 
     
     
         9 . The method according to  claim 1 , wherein the secondary air mass flow is controlled as a function of the actual value of the secondary air mass flow and a target value of the secondary air mass flow predetermined as a function of the time. 
     
     
         10 . The method according to  claim 9 , wherein the target value of the secondary air mass flow is specified in the form of a time-dependent target secondary air mass flow or in the form of a time-dependent target exhaust gas air lambda value or in the form of a time-dependent target pressure in the secondary air supply. 
     
     
         11 . The method according to  claim 9 , wherein a control variable for an actuator is derived from the actual value and from the target value of the secondary air mass flow, and wherein a controllable secondary air pump or a controllable electrical additional compressor is used as the actuator. 
     
     
         12 . A control device for controlling a secondary air mass flow in a secondary air supply of an internal combustion engine, the internal combustion engine comprising:
 the secondary air supply for supplying secondary air,   a device for determining the pressure in the secondary air supply, and   an exhaust gas lambda sensor for determining a current exhaust gas lambda value,   wherein the control device is configured to:
 a) determine a first secondary air mass flow related to the effective throttle area using a throttle equation and depending on a pressure in the secondary air supply; 
 b) determine a second secondary air mass flow based on the measured exhaust gas lambda value and taking into account the primary air mass flow of the internal combustion engine and the supplied fuel mass flow; 
 c) derive an effective throttle area from the first secondary air mass flow determined in step a) and the second secondary air mass flow determined in step b); and 
 d) control the secondary air mass flow in the secondary air supply using the effective throttle area determined in step c) or a quantity derived therefrom. 
   
     
     
         13 . The control device according to  claim 12 , wherein the control device is further configured to control the secondary air mass flow by way of a controllable secondary air pump or by way of a controllable electrical additional compressor or a controllable secondary air valve. 
     
     
         14 . An exhaust gas system of an internal combustion engine comprising the control device according to  claim 12 .