Exhaust gas control in an engine having a two-stage turbocharger

• US 6,801,846 B1
• Filed: 10/24/2003
• Issued: 10/05/2004
• Est. Priority Date: 10/24/2003
• Status: Expired due to Term

• Current Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Original Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Inventors: Rodriguez, Rogelio, Soupos, Elias P., Balekai, Priyankar S.
• Primary Examiner(s): Vo, Hieu T.
• Application Number:
  US10/692,948
• Time in Patent Office: 347 Days
• Field of Search: 701/102, 701/101, 701/115, 606/12, 606/00, 606/01, 606/02, 606/03, 123/564
• US Class Current: 701/102
• CPC Class Codes: F02B 29/0406 Layout of the intake air cooling or coolant circuit
• CPC Class Codes: F02B 37/013 with exhaust-driven pumps arranged in series
• CPC Class Codes: F02B 37/18 by bypassing exhaust from the inlet to the outlet of turbine or to the atmosphere
• CPC Class Codes: F02D 2041/1409 using at least a proportional, integral or derivative controller
• CPC Class Codes: F02D 2041/141 using a feed-forward control element
• CPC Class Codes: F02D 2041/1422 Variable gain or coefficients
• CPC Class Codes: F02D 23/00 Controlling engines characterised by their being supercharged
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• CPC Class Codes: F02D 41/1401 characterised by the control or regulation method F02D41/1473, F02D41/1477 take precedence
• CPC Class Codes: F02M 26/08 for engines having two or more intake charge compressors or exhaust gas turbines, e.g. a turbocharger combined with an additional compressor
• CPC Class Codes: F02M 26/23 Layout, e.g. schematics
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A control system (58) for controlling the extent to which a valve (50) selectively by-passes exhaust flow around one of two turbines (18T, 20T) in an engine exhaust system (14). A desired set-point (TCBC_DES) and the actual set-point of operation of the valve are used to develop a set-point error for closed-loop control of the actual set-point. A data value for closed-loop gain is selected from a schedule (164, 166) based on engine speed and fueling. The selected data value of closed-loop gain and the set-point error data value are used to create a data value for a closed-loop output (TCBC_DTY_PIF) that is used to create a data value for a final output for forcing the actual set-point to the desired set-point.

Claims

1. An internal combustion engine comprising:

combustion chambers within which fuel is combusted;

an exhaust system through which exhaust flow containing products of combustion is conveyed from the engine, including first and second turbines of a multi-stage turbocharger and a valve for selectively by-passing the exhaust flow around one of the turbines; and

a control system comprising a processor for processing data to develop data for controlling the extent to which the valve selectively by-passes the exhaust flow around the one turbine, wherein

the processor comprises a control strategy a) for processing data values of various parameters to develop a data value representing a desired set-point of operation for the valve corresponding to a desired exhaust by-pass flow around the one turbine, b) for processing the desired set-point data value and a data value correlated with the actual set-point of operation of the valve to develop a set-point error data value for closed-loop control of the actual set-point, c) for selecting a data value of closed-loop gain from a schedule based on a data value of a parameter that characterizes an aspect of engine operation, d) for processing both the selected data value of closed-loop gain and the set-point error data value to create a data value for a closed-loop output, and e) for using the data value for the closed-loop output to create a data value for a final output for forcing the actual set-point to the desired set-point.

2. An engine as set forth in claim 1 wherein the processor comprises strategy for processing the set-point error data value through both a proportional function and an integral function using a respective data value of closed-loop gain from a schedule for each of the proportional and integral functions and for using respective data values resulting from processing of the set-point error data value by the respective proportional and integral functions to create the data value for the closed-loop output.

3. An engine as set forth in claim 2 wherein the processor comprises strategy for developing a data value for a feed-forward, open-loop output approximating the desired set-point and for using the feed-forward, open-loop output data value in conjunction with the data value for the closed-loop output to create the data value for the final output.

4. An engine as set forth in claim 3 wherein the control system comprises a map containing feed-forward set-point data values, each of which is correlated with both a particular data value for engine speed within a range of engine speeds and a particular desired engine fueling within a range of engine fueling, and the processor comprises strategy for selecting one of the feed-forward set-point data values from the map on the basis of a data value indicative of engine speed and of a data value indicative of desired engine fueling developed by the processor, and for then using the one selected feed-forward set-point data value in conjunction with the data value for the closed-loop output to create the data value for the final output.

5. An engine as set forth in claim 1 wherein the processor comprises strategy for developing a feed-forward data value approximating the desired set-point and for using the feed-forward data value approximating the desired set-point in conjunction with the data value for the closed-loop output to create the data value for the final output.

6. An engine as set forth in claim 1 wherein the processor comprises strategy for processing a data value indicative of desired engine fueling, a data value indicative of engine speed, a data value indicative of engine temperature, and a data value indicative of barometric pressure to develop the data value representing the desired set-point of operation for the valve corresponding to the desired exhaust by-pass flow around the one turbine.

7. An engine as set forth in claim 6 wherein the processor comprises strategy for evaluating the data value representing the desired set-point of operation for the valve corresponding to the desired exhaust by-pass flow around the one turbine for compliance with an allowable range defined by a data value for a minimum limit and a data value for a maximum limit.

8. An engine as set forth in claim 1 wherein the processor comprises strategy for selecting a data value of closed-loop gain from a schedule based on both a data value indicative of desired engine fueling and a data value indicative of engine speed.

9. A control system for controlling the extent to which a valve selectively by-passes exhaust flow around one of two turbines in an engine exhaust system, the control system comprising:

a processor a) for processing data values of various parameters to develop to develop a data value representing a desired set-point of operation for the valve corresponding to a desired exhaust by-pass flow around the one turbine, b) for processing the desired set-point data value and a data value correlated with the actual set-point of operation of the valve to develop a set-point error data value for closed-loop control of the actual set-point, c) for selecting a data value of closed-loop gain from a schedule based on a data value of a parameter that characterizes an aspect of engine operation, d) for processing both the selected data value of closed-loop gain and the set-point error data value to create a data value for a closed-loop output, and e) for using the data value for the closed-loop output to create a data value for a final output for forcing the actual set-point to the desired set-point.

10. A system as set forth in claim 9 wherein the processor comprises strategy for processing the set-point error data value through both a proportional function and an integral function using a respective data value of closed-loop gain from a schedule for each of the proportional and integral functions and for using respective data values resulting from processing of the set-point error data value by the respective proportional and integral functions to create the data value for the closed-loop output.

11. A system as set forth in claim 10 wherein the processor comprises strategy for developing a data value for a feed-forward, open-loop output approximating the desired set-point and for using the feed-forward, open-loop output data value in conjunction with the data value for the closed-loop output to create the data value for the final output.

12. A system as set forth in claim 11 wherein the system comprises a map containing feed-forward set-point data values, each of which is correlated with both a particular data value for engine speed within a range of engine speeds and a particular desired engine fueling within a range of engine fueling, and the processor comprises strategy for selecting one of the feed-forward set-point data values from the map on the basis of a data value indicative of engine speed and of a data value indicative of desired engine fueling developed by the processor, and for then using the one selected feed-forward set-point data value in conjunction with the data value for the closed-loop output to create the data value for the final output.

13. A system as set forth in claim 9 wherein the processor comprises strategy for developing a feed-forward data value approximating the desired set-point and for using the feed-forward data value approximating the desired set-point in conjunction with the data value for the closed-loop output to create the data value for the final output.

14. A system as set forth in claim 9 wherein the processor comprises strategy for processing a data value indicative of desired engine fueling, a data value indicative of engine speed, a data value indicative of engine temperature, and a data value indicative of barometric pressure to develop the data value representing the desired set-point of operation for the valve corresponding to the desired exhaust by-pass flow around the one turbine.

15. A system as set forth in claim 9 wherein the processor comprises strategy for evaluating the data value representing the desired set-point of operation for the valve corresponding to the desired exhaust by-pass flow around the one turbine for compliance with an allowable range defined by a data value for a minimum limit and a data value for a maximum limit.

16. A system as set forth in claim 9 wherein the processor comprises strategy for selecting a data value of closed-loop gain from a schedule based on both a data value indicative of desired engine fueling and a data value indicative of engine speed.

17. A method for controlling the extent to which a valve selectively by-passes exhaust flow around one of two turbines in an engine exhaust system, the method comprising:

a) processing data values of various parameters to develop to develop a data value representing a desired set-point of operation for the valve corresponding to a desired exhaust by-pass flow around the one turbine, b) processing the desired set-point data value and a data value correlated with the actual set-point of operation of the valve to develop a set-point error data value for closed-loop control of the actual set-point, c) selecting a data value of closed-loop gain from a schedule based on a data value of a parameter that characterizes an aspect of engine operation, d) processing both the selected data value of closed-loop gain and the set-point error data value to create a data value for a closed-loop output, and e) using the data value for the closed-loop output to create a data value for a final output for forcing the actual set-point to the desired set-point.

18. A method as set forth in claim 17 including processing the set-point error data value through both a proportional function and an integral function using a respective data value of closed-loop gain from a schedule for each of the proportional and integral functions and using respective data values resulting from processing of the set-point error data value by the respective proportional and integral functions to create the data value for the closed-loop output.

19. A method as set forth in claim 18 including developing a data value for a feed-forward, open-loop output approximating the desired set-point and using the feed-forward, open-loop output data value in conjunction with the data value for the closed-loop output to create the data value for the final output.

20. A method as set forth in claim 19 including selecting a feed-forward set-point data value from a map containing feed-forward set-point data values, each of which is correlated with both a particular data value for engine speed within a range of engine speeds and a particular desired engine fueling within a range of engine fueling, on the basis of a data value indicative of engine speed and of a data value indicative of desired engine fueling, and then using the selected feed-forward set-point data value in conjunction with the data value for the closed-loop output to create the data value for the final output.

21. A method as set forth in claim 17 including developing a feed-forward data value approximating the desired set-point and for using the feed-forward data value approximating the desired set-point in conjunction with the data value for the closed-loop output to create the data value for the final output.

22. A method as set forth in claim 17 including processing a data value indicative of desired engine fueling, a data value indicative of engine speed, a data value indicative of engine temperature, and a data value indicative of barometric pressure to develop the data value representing the desired set-point of operation for the valve corresponding to the desired exhaust by-pass flow around the one turbine.

23. A method as set forth in claim 17 including evaluating the data value representing the desired set-point of operation for the valve corresponding to the desired exhaust by-pass flow around the one turbine for compliance with an allowable range defined by a data value for a minimum limit and a data value for a maximum limit.

24. A method as set forth in claim 17 including selecting a data value of closed-loop gain from a schedule based on both a data value indicative of desired engine fueling and a data value indicative of engine speed.