Flow estimation for secondary air system
AssigneeGarrett Transportation I Inc.
InventorsPaul Dickinson, Ondrej Santin, Malay C. Maniar
Life of this patent
Estimating the term…
Abstract
Methods and systems using model based and iterative calculations of mass flow throughout an internal combustion engine system. A secondary air injection valve is provided to selectively allow intake air to pass to the exhaust side of the engine system to aid in exothermic reaction with exhaust gasses exiting the engine for various purposes. The iterative calculations of mass flow include estimation of the mass flow through the secondary air injection valve.
Claims20
A method of estimating secondary air flow in an engine system, the engine system including:
- a combustion engine having at least one combustion chamber, an intake manifold having intake manifold pressure and temperature sensors and an exhaust manifold, a turbocharger having a compressor and a turbine configured to provide torque to the compressor, a charge air cooler (CAC), and an aftertreatment system including an environmental catalyst device (ECD), the engine system configured to receive ambient air, compress the ambient air in the compressor, cool the compressed air in the CAC, provide cooled compressed air to the intake manifold, combust a quantity of fuel with the cooled compressed air in the at least one combustion chamber thereby generating exhaust, route the exhaust to the turbine, and route exhaust from the turbine to the aftertreatment system, the engine system also including a secondary air injection (SAI) valve to controllably deliver compressed air from a first location downstream of the compressor to the exhaust at a second location, the SAI valve controlled by an SAI control signal;
- the method comprising:
- sensing an intake manifold pressure and an intake manifold temperature;
- sensing an ambient air pressure, a boost pressure downstream of the CAC, and an engine speed;
- calculating a first pressure at the first location using the boost pressure and a CAC flow model;
- calculating a first temperature at the first location using a model of the compressor;
- calculating an exhaust manifold pressure;
- and
- calculating a mass flow through the SAI valve from a model of the SAI valve using the first pressure, the first temperature, the exhaust manifold pressure, and the SAI control signal as inputs to the model of the SAI valve.
A method of controlling an engine, the engine having a combustion chamber with an intake manifold and an exhaust manifold, a turbocharger with a compressor and a turbine, an aftertreatment system including an environmental catalyst device (ECD) and a lambda sensor, and a secondary air injection (SAI) valve controlled by an SAI control signal and configured to deliver charged air exiting the compressor at a first location to a second location in the exhaust path between the exhaust manifold and the ECD, the method comprising:
- determining an occurrence of a transient engine operation and a temperature of the ECD below an ECD temperature threshold;
- opening the SAI valve to enable secondary air injection to the exhaust to facilitate heating the ECD;
- during the transient engine operation, modulating the SAI control signal to adjust a position of the SAI valve using an open loop control strategy by calculating a mass flow through the SAI valve from a model of the SAI valve;
- determining an end of the transient engine operation while the temperature of the ECD remains below the threshold;
- and
- upon the end of the transient engine operation, modulating the SAI control signal to adjust a position of the SAI valve using a closed loop control strategy by obtaining an output of the lambda sensor.
A method of estimating secondary air flow (SAI) in a controller for an engine system, the engine system including a combustion chamber coupled upstream to an intake manifold (IM) and downstream to an exhaust manifold, a turbocharger having a compressor upstream of the intake manifold and a turbine downstream of the exhaust manifold, a throttle downstream of the compressor and upstream of the IM, and an SAI flow path including an SAI valve, the SAI flow path coupled from a first location downstream of the compressor and upstream of the combustion chamber to a second location downstream of the combustion chamber, the method comprising, with an SAI control signal provided to the SAI valve that causes the SAI valve to be at least partially open, the controller performing the following:
- obtaining an IM pressure and an IM temperature from sensors in the IM;
- obtaining an ambient air pressure from an ambient air pressure sensor, a boost pressure from a boost pressure sensor located upstream of the throttle, and an engine speed from an engine speed sensor;
- calculating a first pressure at the first location using the boost pressure;
- calculating a first temperature at the first location using a compressor model;
- calculating an exhaust manifold pressure;
- and
- estimating a SAI mass flow through the SAI flow path using a model of the SAI valve, the IM pressure, the first pressure, the first temperature, the exhaust manifold pressure, and the SAI control signal.
Dependencies are inferred from the claim text.