Methods and systems for PCV flow estimation with an intake oxygen sensor
AssigneeFord Gloabl Technologies, LLC
InventorsGopichandra Surnilla, James Alfred Hilditch, Matthew John Gerhart, Lynn Aimee Chesney, Stephen B. Smith
Life of this patent
Estimating the term…
Abstract
Methods and systems are provided for estimating a positive crankcase ventilation (PCV) flow based on outputs of an intake manifold oxygen sensor. For example, during engine operation when exhaust gas recirculation (EGR) and fuel canister purge are disabled, PCV flow may be estimated based on a difference between a first output of the sensor with boost enabled and a second output of the sensor with boost disabled. Then, during subsequent operation wherein EGR is enabled, PCV flow is enabled, and purge is disabled, a third output of the sensor may be adjusted based on the estimated PCV flow.
Claims12
A method for operating a turbocharged internal combustion engine including at least one turbocharger, an intake manifold, an intake oxygen sensor, an EGR valve positioned in an EGR passage, and a fuel system canister, the method comprising:
- positioning the intake oxygen sensor downstream of the at least one turbocharger and upstream of the intake manifold in a flow path of the engine;
- measuring oxygen content in the flow path by the intake oxygen sensor;
- estimating an output of PCV flow;
- operating the engine with and without boost;
- determining the output of the PCV flow with EGR flowing in the EGR passage and purge of the fuel system canister disabled based on at least one output of the intake oxygen sensor during the engine operation;
- directing the output of the PCV flow to a position in a flow path of the engine that is upstream of the intake oxygen sensor which then flows to the intake manifold of the engine during the engine operation with boost;
- directing the output of the PCV flow to a position in a flow path of the engine that is downstream of the intake oxygen sensor which then flows to the intake manifold of the engine during the engine operation without boost;
- and
- adjusting the EGR valve based on the measured oxygen content by the intake oxygen sensor, the estimated output of the PCV flow, and exhaust gas flowing through the EGR passage.
A method for operating a turbocharged internal combustion engine including at least one turbocharger, an intake manifold, an intake oxygen sensor, an EGR valve positioned in an EGR passage, and a fuel system canister, the method comprising:
- positioning the intake oxygen sensor downstream of the at least one turbocharger and upstream of the intake manifold in a flow path of the engine;
- measuring oxygen content in the flow path by the intake oxygen sensor;
- estimating an output of PCV flow;
- operating the engine with and without boost;
- determining the output of the PCV flow with EGR flowing in the EGR passage and purge of the fuel system canister disabled based on at least one output of the intake oxygen sensor during the engine operation;
- directing the output of the PCV flow to a position in a flow path of the engine that is upstream of the intake oxygen sensor which then flows to the intake manifold of the engine during the engine operation with boost;
- directing the output of the PCV flow to a position in a flow path of the engine that is downstream of the intake oxygen sensor which then flows to the intake manifold of the engine during the engine operation without boost;
- adjusting the EGR valve based on the measured oxygen content by the intake oxygen sensor, the estimated output of the PCV flow, and exhaust gas flowing through the EGR passage;
- and
- adjusting fueling of the engine based on the estimated output of the PCV flow, the engine fueling decreased as the estimated output of the PCV flow increases.
An engine system, comprising:
- an engine including an intake manifold;
- a crankcase coupled to the intake manifold via a PCV valve;
- a turbocharger with an intake compressor, an exhaust turbine, and a charge air cooler;
- an intake throttle coupled to the intake manifold downstream of the charge air cooler;
- a canister configured to receive fuel vapors from a fuel tank, the canister coupled to the intake manifold via a purge valve;
- an EGR system including a passage for recirculating exhaust residuals from downstream of the turbine to upstream of the compressor and through the engine via an EGR valve;
- an oxygen sensor coupled to the intake manifold, downstream of the charge air cooler and upstream of the intake throttle;
- and
- a controller with computer readable instructions for:
- learning a correction factor for an intake oxygen sensor based on PCV flow and boost conditions of the engine;
- and
- adjusting a position of the EGR valve based on an output of the intake oxygen sensor relative to the correction factor.
Dependencies are inferred from the claim text.