Method and device for ascertaining a modeling value for a physical variable in an engine system having an internal combustion engine

A control device of an engine system for determining a modeling value of at least one physical variable at a specific point in an exhaust gas discharge section of the engine system including an internal combustion engine which is supplied with air via an air supply section, the control device comprising:

• a control unit including a processor configured to:
• operate the engine system to produce an exhaust gas mass flow in the exhaust gas discharge section;
• determine instantaneous values of other physical variables;
• and
• determine the modeling value of the at least one physical variable by solving a differential equation, which results as a discretization of a differential equation, with aid of the previously ascertained instantaneous values of the other physical variables, wherein the at least one physical variable corresponds to at least one of a pressure and an exhaust gas mass flow at a branching point of the exhaust gas discharge section downstream from a turbine of an exhaust-gas-driven turbocharger, wherein (i) a first branch from the branching point leads to a discharge point for the exhaust gas, and (ii) a second branch from the branching point forms a part of an exhaust gas recirculation line connecting the branching point to an intake point of the air supply section.

A non-transitory computer-readable medium having stored thereon a computer program having program codes which, when executed on a computer, perform an automated method for determining a modeling value of at least one physical variable at a specific point in an exhaust gas discharge section of an engine system including an internal combustion engine which is supplied with air via an air supply section, the method comprising:

• operating the engine system to produce an exhaust gas mass flow in the exhaust gas discharge section;
• determining instantaneous values of other physical variables;
• and
• determining the modeling value of the at least one physical variable by solving a differential equation, which results as a discretization of a differential equation, with aid of the previously ascertained instantaneous values of the other physical variables, wherein the at least one physical variable corresponds to at least one of a pressure and an exhaust gas mass flow at a branching point of the exhaust gas discharge section downstream from a turbine of an exhaust-gas-driven turbocharger, wherein (i) a first branch from the branching point leads to a discharge point for the exhaust gas, and (ii) a second branch from the branching point forms a part of an exhaust gas recirculation line connecting the branching point to an intake point of the air supply section.