System and method for determination of EGR flow rate

A method for determining EGR flow in a multi-cylinder internal combustion engine having a sensor for providing a signal indicative of flow of exhaust gas through an EGR circuit, the method comprising:

• determining specific heat of the exhaust gas based on current engine operating conditions;
• and
• determining EGR flow rate based on the determined specific heat and the signal provided by the sensor, wherein determining the EGR flow rate comprises:
• comparing the determined specific heat of the exhaust gas to a reference value associated with the sensor;
• determining a base EGR flow using the sensor signal;
• and
• adjusting the base EGR flow using a difference between the determined specific heat of the exhaust gas and the reference value associated with the sensor.

A computer readable storage medium having stored data representing instructions executable by a computer to determine EGR flow in a multi-cylinder internal combustion engine having a sensor for providing a signal indicative of flow of exhaust gas through an EGR circuit, the computer readable storage medium comprising:

• instructions for determining specific heat of the exhaust gas based on current engine operating conditions, wherein the instructions for determining specific heat of the exhaust gas comprise:
• instructions for tracking amounts of a plurality of species formed during combustion based on the current engine operating conditions;
• instructions for determining the specific heat contribution of each specie based on the amount of each specie and an associated specie specific heat;
• and
• instructions for summing the specific heat contributions determined for each specie to determine the specific heat of the exhaust gas;
• and
• instructions for determining EGR flow rate based on the determined specific heat and the signal provided by the sensor.

A system for determining EGR flow in a multi-cylinder internal combustion engine having a plurality of cylinders each with an associated fuel injector, the system comprising:

• an EGR valve for diverting a portion of exhaust gas through an EGR circuit to an engine intake;
• a sensor for providing a signal indicative of flow of exhaust gas through the EGR circuit;
• a turbocharger controllable to vary at least one operating characteristic in response to a command signal;
• and
• a controller in communication with the EGR valve, the sensor, and the turbocharger, the controller determining specific heat of the exhaust gas flowing through the EGR circuit based on current engine operating conditions and determining an actual EGR flow rate based on the determined specific heat of the exhaust gas flowing through the EGR circuit and the signal provided by the sensor.

A system for determining EGR flow in a multi-cylinder internal combustion engine having a plurality of cylinders each with an associated fuel injector, the system comprising:

• means for diverting a portion of exhaust gas through an EGR circuit to an engine intake;
• means for determining EGR flow based on specific heat of the exhaust gas flowing through the EGR circuit and heat dissipation of a heated element placed in the EGR flow, wherein the means for determining EGR flow determines specific heat of the exhaust gas by tracking amounts of a plurality of species formed during combustion based on current engine operating conditions;
• and
• means for controlling the engine based on the EGR flow.

A method for controlling a multi-cylinder internal combustion engine having a flow of exhaust gas through an EGR circuit, the method comprising:

• sensing the flow of exhaust gas through the EGR circuit using a sensor;
• determining specific heat of the exhaust gas based on current engine operating conditions, wherein determining specific heat of the exhaust gas comprises:
• tracking amounts of a plurality of species formed during combustion based on the current engine operating conditions;
• determining the specific heat contribution of each specie based on the amount of each specie and an associated specie specific heat;
• and
• summing the specific heat contributions determined for each specie to determine the specific heat of the exhaust gas;
• determining EGR flow rate based on the determined specific heat and the signal provided by the sensor;
• comparing the determined EGR flow rate to a desired EGR flow rate to provide an EGR flow rate error;
• and
• controlling at least one of an EGR valve and turbocharger to reduce the EGR flow error.

A method for controlling a multi-cylinder internal combustion engine having a flow of exhaust gas through an EGR circuit, the method comprising:

• sensing the flow of exhaust gas through the EGR circuit using a sensor;
• determining specific heat of the exhaust gas based on current engine operating conditions;
• determining EGR flow rate based on the determined specific heat and the signal provided by a sensor, wherein determining the EGR flow rate comprises:
• comparing the determined specific heat of the exhaust gas to a reference value associated with the sensor;
• determining a base EGR flow using the sensor signal;
• and
• adjusting the base EGR flow using a difference between the determined specific heat of the exhaust gas and the reference value associated with the sensor;
• comparing the determined EGR flow rate to a desired EGR flow rate to provide an EGR flow rate error;
• and
• controlling at least one of an EGR valve and turbocharger to reduce the EGR flow error.