Granted Patent B2

US 8,096,123 · App. 12/474,599 · Granted Jan 17, 2012

Abstract

Claims (37)

1. A method for controlling an engine including a turbocharging system with a high pressure turbocharger and a low pressure turbocharger, comprising:

determining a potential boost pressure corresponding to a high pressure turbine bypass valve in a closed position when the high pressure turbine bypass valve is in an open position; and

closing high pressure turbine the bypass valve and operating a high pressure compressor with the potential boost pressure in a desired high pressure working area to obtain a desired pressure boost; and

maintaining the open position.

2. A method as recited in claim 1 wherein determining a potential boost pressure comprises determining the potential boost pressure when a variable vane position of a high pressure turbine is within a predetermined range of vane positions.

3. A method of controlling an engine comprising:

opening a high pressure turbine bypass valve of a turbocharging system;

for a first position of a variable geometry turbine of a high pressure turbocharger, determining a first predicted boost pressure when the high pressure turbine bypass valve is in an open position;

for a second position of the variable geometry turbine, determining a second predicted boost pressure when the high pressure turbine bypass valve is in the open position;

determining a desired boost; and

when the desired boost is between the first predicted boost pressure and the second predicted boost pressure, closing the high pressure turbine bypass valve.

4. A method as recited in claim 3 wherein the first position of the variable geometry turbine corresponds to a minimum position and wherein the second position of the variable geometry turbine corresponds to a maximum position.

5. A method as recited in claim 3 wherein determining a first predicted boost pressure comprises determining the first predicted boost pressure based on a high pressure compressor pressure ratio and a low pressure compressor pressure ratio.

6. A method as recited in claim 5 further comprising determining the high pressure compressor pressure ratio based on a high pressure compressor map.

7. A method as recited in claim 5 further comprising determining the high pressure compressor pressure ratio based on a high pressure compressor map and a low pressure compressor outlet temperature.

8. A method as recited in claim 7 further comprising determining the low pressure compressor outlet temperature based on a low pressure inlet temperature, a low pressure compressor pressure ratio and a low pressure compressor efficiency.

9. A method as recited in claim 8 further comprising determining the low pressure compressor pressure ratio based on an energy to a low pressure compressor.

10. A method as recited in claim 3 wherein determining a first predicted boost pressure comprises determining a first predicted boost pressure based on a potential high pressure turbine energy.

11. A method as recited in claim 10 further comprising determining the potential high pressure turbine energy based on an exhaust temperature and a high pressure turbine pressure ratio.

12. A method as recited in claim 3 wherein determining a first predicted boost pressure comprises determining the first predicted boost pressure based on a potential low pressure turbine energy.

13. A method as recited in claim 12 further comprising determining the potential low pressure turbine energy based on an exhaust temperature and a low pressure turbine pressure ratio.

14. A method as recited in claim 3 wherein determining a first predicted boost pressure comprises determining the first predicted boost pressure based on a temperature drop over a high pressure turbine.

15. A method as recited in claim 14 wherein determining a temperature drop over the high pressure turbine comprises determining a pressure drop over the high pressure turbine based on a high pressure turbine efficiency, a high pressure turbine inlet temperature and a high pressure turbine pressure ratio.

16. A control system comprising:

a boost determination module that determines a first predicted boost pressure for a first position of a variable geometry turbine when a high pressure turbine bypass valve is in an open position, and that determines a second predicted boost pressure for a second position of the variable geometry turbine when the high pressure turbine bypass valve is in the open position;

a desired boost module that determines a desired boost;

a comparison module that determines when the desired boost is between the first predicted boost pressure and the second predicted boost pressure; and

a bypass valve control module that closes the high pressure turbine bypass valve when the desired boost is between the first predicted boost pressure and the second predicted boost pressure.

17. A control system as recited in claim 16 wherein the first predicted boost pressure is based on a potential low pressure turbine energy.

18. A control system as recited in claim 16 wherein the first predicted boost pressure is based on a high pressure compressor pressure ratio and a low pressure compressor pressure ratio.

19. A system comprising:

an engine;

a high pressure turbocharger having a high pressure variable geometry turbine and a high pressure compressor;

a low pressure turbocharger in series with the high pressure turbocharger having a low pressure turbine and a low pressure compressor; and

the high pressure turbine bypass valve bypassing the high pressure turbine;

the control system as recited in claim 16 .

20. A system as recited in claim 19 wherein the first position of the variable geometry turbine corresponds to a minimum position and wherein the second position of the variable geometry turbine corresponds to a maximum position.

Assignments (8)

Continuity (1)