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US 10,774,768 B2Granted
Method of modelling AFR to compensate for WRAF sensor
AssigneeDelphi Automotive Systems Luxembourg SA
InventorsDamien Didiot, Julien Ardeois
Life of this patent
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Abstract
A method of providing a model which provides air/fuel ratio at a point of an air/fuel sensor located in an exhaust system of an engine includes a) providing a first model which provides a first air/fuel ratio which is outlet from an exhaust manifold of the engine; b) measuring or estimating volumetric flow through the exhaust; c) applying a transfer function to the first air/fuel ratio to provide a model of the air/fuel ratio at the sensor. The transfer function includes a first order filter and is dependent on the volumetric flow. The transfer function has a time constant equivalent to a filter coefficient which is 1/time constant which is determined based on the flow rate.
Claims12
A method of providing a model which provides parameters of an air/fuel ratio at a point where an air/fuel sensor is provided at a location in an exhaust system of an engine having an exhaust manifold, the method comprising:
- a) providing a first model which provides a first air/fuel ratio which is outlet from the exhaust manifold of said engine;
- b) measuring or estimating a volumetric flow rate through the exhaust system;
- c) applying a transfer function to the first air/fuel ratio determined by said first model to provide a model of air/fuel ratio at said location of said air/fuel sensor, said transfer function including a first order filter, said transfer function being dependent on said volumetric flow rate determined in step b), said transfer function having a time constant or a filter coefficient where the filter coefficient=1/the time constant;
- said time constant or the filter coefficient being determined based on the volumetric flow rate, characterised in amending the time constant or the filter coefficient by applying a correction factor;
- said correction factor being determined based on the following further steps:
- d) measuring a second air/fuel ratio at said location by said air/fuel sensor;
- e) over a time period, comparing the model of air/fuel ratio from step c) with the second air/fuel ratio from step d);
- f) determining or amending one or more correction factors to said filter coefficient or said time constant of said transfer function based on the comparing of step e);
- and
- g) using said model to adjust the fuel or air quantity to the engine;
- wherein step e) comprises comparing a first gradient of the model of air/fuel ratio from step c) with respect to time with a second gradient of the second air/fuel ratio measured by said air/fuel sensor in step d);
- and
- wherein said method includes determining a ratio of said first gradient and said second gradient and determining said correction factor based on said ratio.
10 more elements
A method of providing a model which provides parameters of an air/fuel ratio at a point where an air/fuel sensor is provided at a location in an exhaust system of an engine having an exhaust manifold, the method comprising:
- a) providing a first model which provides a first air/fuel ratio which is outlet from the exhaust manifold of said engine;
- b) measuring or estimating a volumetric flow rate through the exhaust system;
- c) applying a transfer function to the first air/fuel ratio determined by said first model to provide a model of air/fuel ratio at said location of said air/fuel sensor, said transfer function including a first order filter, said transfer function being dependent on said volumetric flow rate determined in step b), said transfer function having a time constant or a filter coefficient where the filter coefficient=1/the time constant;
- said time constant or the filter coefficient being determined based on the volumetric flow rate, characterised in amending the time constant or the filter coefficient by applying a correction factor;
- said correction factor being determined based on the following further steps:
- d) measuring a second air/fuel ratio at said location by said air/fuel sensor;
- e) over a time period, comparing the model of air/fuel ratio from step c) with the second air/fuel ratio from step d);
- f) determining or amending one or more correction factors to said filter coefficient or said time constant of said transfer function based on the comparing of step e);
- and
- g) using said model to adjust the fuel or air quantity to the engine;
- wherein step e) comprises comparing a first gradient of the model of air/fuel ratio from step c) with respect to time with a second gradient of the second air/fuel ratio measured by said air/fuel sensor in step d);
- and
- wherein step e) comprises amending the determined value of the time constant of said first order filter, referred to in step c), according to the equation:
- τamended=the determined value of the time constant*the time constant correction factor determined from step f).
11 more elements
A method of providing a model which provides parameters of an air/fuel ratio at a point where an air/fuel sensor is provided at a location in an exhaust system of an engine having an exhaust manifold, the method comprising:
- a) providing a first model which provides a first air/fuel ratio which is outlet from the exhaust manifold of said engine;
- b) measuring or estimating a volumetric flow rate through the exhaust system;
- c) applying a transfer function to the first air/fuel ratio determined by said first model to provide a model of air/fuel ratio at said location of said air/fuel sensor, said transfer function including a first order filter, said transfer function being dependent on said volumetric flow rate determined in step b), said transfer function having a time constant or a filter coefficient where the filter coefficient=1/the time constant;
- said time constant or the filter coefficient being determined based on the volumetric flow rate, characterised in amending the time constant or the filter coefficient by applying a correction factor;
- said correction factor being determined based on the following further steps:
- d) measuring a second air/fuel ratio at said location by said air/fuel sensor;
- e) over a time period, comparing the model of air/fuel ratio from step c) with the second air/fuel ratio from step d);
- f) determining or amending one or more correction factors to said filter coefficient or said time constant of said transfer function based on the comparing of step e);
- and
- g) using said model to adjust the fuel or air quantity to the engine;
- wherein said method includes storing a MAP or look-up table of volumetric flow rates against said one or more corrections factors to said filter coefficients or time constants of said transfer function, and amending stored correction factors dependent on result of steps d) and e).
8 more elements
A method of providing a model which provides parameters of an air/fuel ratio at a point where an air/fuel sensor is provided at a location in an exhaust system of an engine having an exhaust manifold, the method comprising:
- a) providing a first model which provides a first air/fuel ratio which is outlet from the exhaust manifold of said engine;
- b) measuring or estimating a volumetric flow rate through the exhaust system;
- c) applying a transfer function to the first air/fuel ratio determined by said first model to provide a model of air/fuel ratio at said location of said air/fuel sensor, said transfer function including a first order filter, said transfer function being dependent on said volumetric flow rate determined in step b), said transfer function having a time constant or a filter coefficient where the filter coefficient=1/the time constant;
- said time constant or the filter coefficient being determined based on the volumetric flow rate, characterised in amending the time constant or the filter coefficient by applying a correction factor;
- said correction factor being determined based on the following further steps:
- d) measuring a second air/fuel ratio at said location by said air/fuel sensor;
- e) over a time period, comparing the model of air/fuel ratio from step c) with the second air/fuel ratio from step d);
- f) determining or amending one or more correction factors to said filter coefficient or said time constant of said transfer function based on the comparing of step e);
- and
- g) using said model to adjust the fuel or air quantity to the engine;
- wherein said first order filter is defined as a lag function of (1/(τs+1)) where τ is said time constant.
8 more elements
A method of providing a model which provides parameters of an air/fuel ratio at a point where an air/fuel sensor is provided at a location in an exhaust system of an engine having an exhaust manifold, the method comprising:
- a) providing a first model which provides a first air/fuel ratio which is outlet from the exhaust manifold of said engine;
- b) measuring or estimating a volumetric flow rate through the exhaust system;
- c) applying a transfer function to the first air/fuel ratio determined by said first model to provide a model of air/fuel ratio at said location of said air/fuel sensor, said transfer function including a first order filter, said transfer function being dependent on said volumetric flow rate determined in step b), said transfer function having a time constant or a filter coefficient where the filter coefficient=1/the time constant;
- said time constant or the filter coefficient being determined based on the volumetric flow rate, characterised in amending the time constant or the filter coefficient by applying a correction factor;
- said correction factor being determined based on the following further steps:
- d) measuring a second air/fuel ratio at said location by said air/fuel sensor;
- e) over a time period, comparing the model of air/fuel ratio from step c) with the second air/fuel ratio from step d);
- f) determining or amending one or more correction factors to said filter coefficient or said time constant of said transfer function based on the comparing of step e);
- and
- g) using said model to adjust the fuel or air quantity to the engine;
- wherein step e) comprises amending the determined value of the filter coefficient K of the first order filter according to the equation:
- Kamended=determined value of the filter coefficient*the filter coefficient correction factor determined from step f).
9 more elements
Dependencies are inferred from the claim text.