Control methods for improved catalytic converter efficiency and diagnosis

• US 7,886,523 B1
• Filed: 09/09/2003
• Issued: 02/15/2011
• Est. Priority Date: 08/24/1998
• Status: Active Grant

• Current Assignee: Joseph E. Legare
• Original Assignee: Joseph E. Legare
• Inventors: Legare, Joseph E.
• Primary Examiner(s): NGUYEN, TU MINH
• Application Number:
  US10/657,188
• Time in Patent Office: 2,716 Days
• Field of Search: 602/74, 602/76, 602/77, 602/85, 123/673, 123/679, 123/681
• US Class Current: 60/285
• CPC Class Codes: F02D 2041/1431 the system including an input-output delay
• CPC Class Codes: F02D 2250/21 during a transition between engine operation modes or states
• CPC Class Codes: F02D 41/008 Controlling each cylinder individually
• CPC Class Codes: F02D 41/0255 to accelerate the warming-up of the exhaust gas treating apparatus at engine start
• CPC Class Codes: F02D 41/1408 Dithering techniques
• CPC Class Codes: F02D 41/1446 the characteristics being exhaust temperatures
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02D 41/1487 Correcting the instantaneous control value
• CPC Class Codes: F02M 35/1038 for temperature or pressure
• CPC Class Codes: F02M 35/10386 for flow rate air flow meters in air cleaners F02M35/021; circuit arrangements for generating control signals by measuring intake air flow F02D41/18
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A controlling method for adjusting concentrations of, for example, individual cylinder'"'"'s exhaust gas constituents to provide engine functions such as catalytic converter diagnosis, increased overall catalytic converter efficiency and rapid catalyst heating, before and/or after initiating closed loop fuel injection control, using a selected temperature sensor location within a low thermal mass catalytic converter design.

Claims

1. A method of early cycling an oxygen sensor'"'"'s output, during non-stoichiometric transient engine load change conditions, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

providing a switching oxygen sensor for detecting exhaust gases'"'"' rich or lean conditions;

causing estimated fuel changes into selected individual cylinders; and

modifying subsequently said estimated fuel changes using a successive approximation approach based upon feedback determined by sampling the oxygen sensor'"'"'s output during predetermined time periods.

2. A method of rapid correction of air-fuel ratio deviations from a defined control point following an engine load change, including the step of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

providing a switching oxygen sensor for detecting exhaust gases'"'"' rich or lean conditions;

controlling fuel quantities, for selected individual cylinders, based upon monitoring exhaust gases'"'"' air-fuel conditions at predetermined times, in order to determine necessary fuel quantity corrections for subsequent selected individual cylinders'"'"' combustion events that will result in cycling of catalyst inlet gases'"'"' air-fuel about a defined control point.

3. A method of individual cylinder fuel control, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

providing a switching oxygen sensor for monitoring and detecting exhaust gases'"'"' conditions;

compensating for transient engine load changes by delivering estimated fuel quantities into selected individual cylinders; and

modifying said estimated fuel quantities by monitoring subsequent exhaust gases'"'"' air-fuel conditions detected for the selected individual cylinders'"'"' combustion event at predetermined times, until said exhaust gases'"'"' air-fuel conditions fluctuate about a defined control point.

4. A method of fuel control to compensate for undesired exhaust gas air-fuel deviations from a desired control point during engine operating condition changes, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

monitoring engine exhaust gases with a switching oxygen sensor;

providing selected individual cylinder injection probe events, after a predefined number of normal fuel injection events, to have corrections in magnitudes of fuel quantity to counteract effects of load changes; and

adjusting the corrections in magnitudes of fuel quantity to selected individual cylinders, based upon the oxygen sensor feedback of exhaust gases'"'"' conditions resulting from prior said probe events by said sensor feedback sampling at predetermined times so as to cause the exhaust gases'"'"' conditions to cycle about a defined control point at an earlier time following the load change.

5. A method of identifying an individual cylinders'"'"' oxygen sensor'"'"'s response time, when an individual engine cylinders'"'"' fuel changes cause subsequent changes in exhaust gases'"'"' conditions, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

providing a switching oxygen sensor for detecting exhaust gases'"'"' conditions;

causing a sequence of at least a first and second transitions in said oxygen sensor'"'"'s conditions by enabling controlled changes in fuel quantity to at least one selected grouping of cylinders;

said first transition causing a stable lean oxygen sensor condition and said second transition creating a stable, selected rich condition; and

measuring a time difference between when the first individual cylinder'"'"'s exhaust gases enter the exhaust manifold having the second enabling controlled change in fuel quantity, and the actual time of said second transition in oxygen sensor output conditions resulting from said stable selected rich oxygen sensor condition.

6. A method of fuel control for synchronizing an individual engine cylinder'"'"'s fuel changes to their respective changes in exhaust gases, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

detecting exhaust gases'"'"' conditions with a switching type oxygen sensor;

correlating controlled fuel changes of individual cylinder'"'"'s injectors to subsequent detected exhaust gas changes, controlled at magnitudes differing from normal operation; and

storing in memory a time delay period based upon a time difference between causing the fuel change and the detected exhaust gas property changes of the individual cylinders.

7. A method according to claim 6, further comprising the step of:

determining an oxygen sensor time response characteristics for assessing proper operating condition of the oxygen sensor using the time delay period stored in memory.

8. A method of fuel control for synchronizing individual engine cylinder fuel changes to subsequent changes in exhaust gases'"'"' conditions, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

detecting exhaust gases'"'"' conditions with a switching type oxygen sensor;

detecting at least one engine parameter sufficient to determine stable exhaust gases'"'"' conditions for monitoring during a first time period;

causing a sequence of changes in fuel quantity to at least one selected grouping of cylinders, during a second time period, differing from the fuel quantity in said first time period, so as to produce a change in exhaust gases'"'"' air-fuel conditions differing from the exhaust gases'"'"' conditions detected during the first time period;

monitor a time period, from a selected reference point, for the time of the first change in said exhaust gases'"'"' air-fuel conditions that are caused by said changes in fuel quantity during said second time period; and

storing in memory the monitored time period from the selected reference point.

9. A method according to claim 8, whereby the oxygen sensor has two discrete output voltage characteristics that are activated in a non-linear manner for indicating conditions richer and leaner than stoichiometric.

10. A method of synchronizing individual engine cylinder fuel changes to subsequent changes in exhaust gases'"'"' air-fuel conditions including:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

detecting exhaust gases'"'"' conditions with a switching oxygen sensor;

detecting at least one engine parameter sufficient to determine stable exhaust gases'"'"' conditions for monitoring;

determining oxygen sensor conditions during a first time period;

causing a sequence of at least a first change in fuel quantity to at least one selected grouping of engine cylinders, said first change in quantity differing from a quantity present in said first time period, so as to produce at least one transition in oxygen sensor output conditions in a second time period differing from said conditions detected during said first time period;

monitoring a time period by determining a point in time of a first transition in said oxygen sensor conditions in relationship to a selected engine cycle reference datum that are caused by said changes in fuel quantity during said second time period; and

storing in memory said monitored time period.

11. A method according to claim 10, whereby additional recordings of said measured time are measured by causing a sequence of said transitions in oxygen sensor output conditions so as to determine a more accurate average for a value of said time period that can be stored in memory.

12. A method of transient engine fuel control compensation to selected individual cylinders, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

providing a switching oxygen sensor for detecting exhaust gases'"'"' rich or lean conditions to provide engine fuel control compensation to selected individual cylinders;

detecting, during a first time period, transient engine load condition changes that may subsequently cause exhaust gases'"'"' air-fuel ratio to deviate from a defined control point;

causing a change in fuel quantities to at least one selected individual engine cylinder, differing from quantities in the first time period, during a second time period for adjusting effects of the transient engine load condition changes;

measuring effects of at least one selected individual engine cylinder'"'"'s exhaust gases'"'"' conditions resulting from the changes in fuel quantity, by sampling exhaust gases'"'"' conditions with the switching oxygen sensor during predetermined time periods, following said second time period;

making subsequent modifications in fuel quantities supplied to at least a second selection of individual cylinders; and

detecting at predetermined times said second and subsequent selections of individual cylinders'"'"' exhaust gases'"'"' conditions resulting from immediately prior modifications in fuel quantities to selected individual cylinders, so as to cause air-fuel ratio fluctuations about the defined control point.

13. A method of individual cylinder fuel control compensation for conditions of engine load changes, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

monitoring engine exhaust gases with a switching oxygen sensor;

detecting at least one engine operating parameter indicating a load change and enabling individual cylinder fuel control;

enabling a change in fuel quantity to at least one selected individual cylinder, to produce a change in exhaust gases'"'"' air-fuel conditions that adjusts for effects of the load change;

detecting exhaust gases'"'"' conditions resulting from each said selected individual cylinders'"'"' said change in fuel quantity by sampling at predetermined times; and

controlling subsequent changes in cylinder'"'"'s fuel quantity, such changes depending on effects that each previous said change in fuel quantities has on subsequent exhaust gases'"'"' air-fuel conditions detected for each individual cylinders'"'"' combustion event, to causing in cycling of gases'"'"' air-fuel about a defined control point so as to compensate air-fuel conditions for said load changes.

14. A method according to claim 13, whereby the change in fuel quantity is implemented gradually by transitioning to the maximum controlled fuel quantity changes amongst individual cylinders spanning over a number of cylinder firing events in order to minimize perceived changes in engine smoothness caused by step changes in engine cylinders'"'"' torque levels.

15. A method according to claim 13, whereby said causing cycling of gases'"'"' air-fuel about a defined control point is used to determine dynamic catalyst oxygen storage characteristics during non-stoichiometric conditions for modifying subsequent fuel changes into the individual cylinders for more quickly reaching the defined control point.

16. A method according to claim 13, wherein the changes in fuel quantity are determined using stored correction values based upon oxygen sensor feedback during prior engine load changes of similar characteristics, such said feedback from subsequent prior combustion events having said fuel quantity causing said cycling of gases'"'"' air-fuel about a defined control point.

17. A method according to claim 13, whereby a second oxygen sensor is provided, and is a wide range linear type device allowing more rapid correction of measured exhaust gases'"'"' air-fuel ratio deviations from defined control points by controlling said subsequent changes in cylinders'"'"' fuel quantities depending upon actual magnitude of detected deviation from said control point.

18. A method of individual cylinder fuel control compensation for conditions of engine load changes, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

monitoring engine exhaust gases with a switching oxygen sensor;

detecting at least one engine operating parameter indicating a load change and enabling individual cylinder fuel control, during a first time period;

enabling a change in fuel quantity to at least one selected individual cylinder, to produce a change in exhaust gases'"'"' air-fuel conditions that adjusts for effects of the load change;

detecting exhaust gases'"'"' conditions resulting from each said selected individual cylinders'"'"' said change in fuel quantity by sampling at predetermined times; and

controlling subsequent changes in cylinder'"'"'s fuel quantity, such changes depending on effects that each previous said change in fuel quantities has on subsequent exhaust gases'"'"' air-fuel conditions detected for each individual cylinders'"'"' combustion event, to causing in cycling of gases'"'"' air-fuel about a defined control point so as to compensate air-fuel conditions for said load changes, wherein the changes in fuel quantity are determined using stored correction values based upon oxygen sensor feedback during prior engine load changes of similar characteristics, such said feedback from subsequent prior combustion events having said fuel quantity causing said cycling of gases'"'"' air-fuel about a defined control point, and whereby said causing cycling of gases'"'"' air-fuel about the defined control point is used to determine dynamic catalyst oxygen storage characteristics during non-stoichiometric conditions for modifying subsequent fuel changes into the individual cylinders for more quickly reaching the defined control point.

19. A method according to 18, further comprising the step of monitor a time period, from a selected reference point, for the time of the first change in said exhaust gases'"'"' air-fuel conditions that are caused by said changes in fuel quantity during a second time period.

20. A method of individual cylinder fuel control compensation for conditions of engine load changes, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

monitoring engine exhaust gases with a switching oxygen sensor;

detecting at least one engine operating parameter indicating a load change and enabling individual cylinder fuel control, during a first time period;

enabling a change in fuel quantity to at least one selected individual cylinder, to produce a change in exhaust gases'"'"' air-fuel conditions that adjusts for effects of the load change;

detecting exhaust gases'"'"' conditions resulting from each said selected individual cylinders'"'"' said change in fuel quantity by sampling at predetermined times; and

controlling subsequent changes in cylinder'"'"'s fuel quantity, such changes depending on effects that each previous said change in fuel quantities has on subsequent exhaust gases'"'"' air-fuel conditions detected for each individual cylinders'"'"' combustion event, to causing in cycling of gases'"'"' air-fuel about a defined control point so as to compensate air-fuel conditions for said load changes, whereby the change in fuel quantity is implemented gradually by transitioning to the maximum controlled fuel quantity changes amongst individual cylinders spanning over a number of cylinder firing events in order to minimize perceived changes in engine smoothness caused by step changes in engine cylinders'"'"' torque levels, and wherein the changes in fuel quantity are determined using stored correction values based upon oxygen sensor feedback during prior engine load changes of similar characteristics, such said feedback from subsequent prior combustion events having said fuel quantity causing said cycling of gases'"'"' air-fuel about the defined control point.

21. A method according to claim 20, further comprising the step of causing a sequence of changes in fuel quantity to at least one selected grouping of cylinders, during a second time period, differing from the fuel quantity in said first time period, so as to produce a change in exhaust gases'"'"' air-fuel conditions differing from the exhaust gases'"'"' conditions detected during the first time period.

22. A method of individual engine cylinder closed loop fuel control, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

detecting exhaust gases'"'"' rich or lean conditions with a switching oxygen sensor;

synchronizing a sampling time period for detecting a change in an oxygen sensor'"'"'s output condition to an individually selected cylinder'"'"'s exhaust gases entering the exhaust manifold;

detecting at least one engine parameter sufficient to determine stable engine operational conditions;

controlling a closed loop fuel control change in the fuel quantity during a first period to all cylinders connected to an exhaust manifold with a common oxygen sensor by using the minimum said quantity to cause sensor cycling between rich and lean conditions;

sampling the oxygen sensor'"'"'s condition during a second time period when each individual cylinder'"'"'s gases are entering said exhaust manifold and identifying cylinders resulting in a contrary sensor condition to the respective said closed loop fuel control changes during the first period;

controlling a minimum change in fuel quantity into at least one of the selected individual cylinders with said contrary sensor conditions, using said fuel quantity sufficient to produce a change in the oxygen sensor condition thus differing from the selected individual cylinder'"'"'s exhaust gases'"'"' conditions sampled in the second time period, during a third time period;

determining the minimum change in fuel quantity causing a change in the oxygen sensor condition for each selected individual cylinder having said contrary sensor conditions follow the third time period and storing in memory such minimums for each respective individual cylinder during stoichiometric conditions; and

establishing a learned average fuel quantity offset for each individual cylinder by adjusting all cylinders'"'"' offsets such that the minimum said fuel control change necessary for each selected engine operational condition are stored in memory.

23. A method of individual cylinder fuel control compensation for conditions of engine load changes, including the steps of:

providing a catalyst for reducing exhaust gas emissions;

providing at least one temperature sensor in said catalyst;

monitoring the catalyst temperature with the at least one temperature sensor for determining engine cylinder fuel control;

monitoring engine exhaust gases with a switching oxygen sensor;

detecting at least one engine operating parameter indicating a load change and enabling individual cylinder fuel control;

enabling a change in fuel quantity to at least one selected individual cylinder, to produce a change in exhaust gases'"'"' air-fuel conditions that adjusts for effects of the load change;

detecting exhaust gases'"'"' conditions resulting from each said selected individual cylinders'"'"' said change in fuel quantity by sampling at predetermined times; and

controlling subsequent changes in cylinder'"'"'s fuel quantity, such changes depending on effects that each previous said change in fuel quantities has on subsequent exhaust gases'"'"' air-fuel conditions detected for each individual cylinders'"'"' combustion event, to causing in cycling of gases'"'"' air-fuel about a defined control point so as to compensate air-fuel conditions for said load changes, whereby the change in fuel quantity is implemented gradually by transitioning to the maximum controlled fuel quantity changes amongst individual cylinders spanning over a number of cylinder firing events in order to minimize perceived changes in engine smoothness caused by step changes in engine cylinders'"'"' torque levels, and whereby said causing cycling of gases'"'"' air-fuel about a defined control point is used to determine dynamic catalyst oxygen storage characteristics during non-stoichiometric conditions for modifying subsequent fuel changes into the individual cylinders for more quickly reaching the defined control point.

24. A method according to claim 23, wherein the changes in fuel quantity are determined using stored correction values based upon oxygen sensor feedback during prior engine load changes of similar characteristics, such said feedback from subsequent prior combustion events having said fuel quantity causing said cycling of gases'"'"' air-fuel about the defined control point.