FLOW SENSOR

• US 20070235010A1
• Filed: 04/06/2006
• Published: 10/11/2007
• Est. Priority Date: 04/06/2006
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Weber, James, Fluga, Eric, Savage, Patrick
• Granted Patent: US 7,278,411 B1
• Time in Patent Office: Days
• US Class Current: 123/568.120
• CPC Class Codes: F02B 29/0425 Air cooled heat exchangers
• CPC Class Codes: F02B 29/0437 Liquid cooled heat exchangers
• CPC Class Codes: F02B 29/0468 Water separation or drainage means
• CPC Class Codes: F02D 41/0072 Estimating, calculating or determining the EGR rate, amount or flow sensors in EGR systems F02M26/45
• 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 26/15 in relation to engine exhaust purifying apparatus
• CPC Class Codes: F02M 26/21 with EGR valves located at or near the connection to the intake system
• CPC Class Codes: F02M 26/28 with liquid-cooled heat exchangers
• CPC Class Codes: F02M 26/47 the characteristics being temperatures, pressures or flow rates
• CPC Class Codes: F02M 26/49 Detecting, diagnosing or indicating an abnormal function of the EGR system
• CPC Class Codes: F02M 26/70 Flap valves; Rotary valves; Sliding valves; Resilient valves
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An exhaust system for receiving exhaust gas of an engine is provided. The exhaust system comprises a cooler configured to cool at least a portion of exhaust gas, a pressure sensor configured to measure an exhaust pressure drop across the cooler, and a controller configured to determine exhaust flowrate as a function the measured pressure drop across the cooler. Also provided is a method for operating an engine. The method comprises the steps of combusting a fuel and air mixture, exhausting at least some of the combusted fuel and air mixture as exhaust gas to an exhaust system of an engine, cooling at least some of the combusted exhaust gas in a cooler, measuring pressure drop of the exhaust gas across the cooler, and determining a flowrate of the exhaust gas across the cooler as a function of pressure drop.

Claims

1. An exhaust system for receiving exhaust gas of an engine, comprising:

a cooler configured to cool at least a portion of exhaust gas;

a pressure sensor configured to measure an exhaust pressure drop across the cooler;

a controller configured to determine exhaust flowrate as a function of the measured pressure drop and a level of fouling of the cooler.

2. The exhaust system of claim 1, further comprising a recirculated exhaust gas loop configured to send the cooled portion of exhaust gas to an intake of an engine.

3. The exhaust system of claim 1, further comprising at least one temperature sensor configured to measure the temperature of the exhaust.

4. The exhaust system of claim 3, further comprising at least two temperature sensors configured to measure the temperature drop of the exhaust gas across the cooler.

5. The exhaust system of claim 1, in which the cooler is a parallel-flow heat exchanger.

6. The exhaust system of claim 1, in which the cooler comprises a cooling medium for cooling the exhaust gas.

7. The exhaust system of claim 6, further comprising a first set of temperature sensors configured to measure the temperature drop of the cooling medium across the cooler.

8. The exhaust system of claim 7, further comprising a second set of temperature sensors configured to measure the temperature drop of the exhaust gas across the cooler.

9. The exhaust system of claim 8, in which the controller is configured to determined the level of fouling within the cooler as a function of the temperature drop of the cooling medium across the cooler, the temperature drop of the exhaust gas across the cooler, and the pressure drop of the exhaust gas across the cooler.

11. The exhaust system of claim 6, in which the cooler uses engine jacket water as the cooling medium.

12. The exhaust system of claim 1, in which the cooler is positioned in a recirculated exhaust gas loop of an engine and the controller is configured to determine recirculated exhaust gas flowrate.

13. An engine, comprising:

an intake air system;

at least one combustion chamber; and

the exhaust system of claim 1;

in which the intake air system is configured to receive at least some exhaust gas from the exhaust system.

32. The exhaust system of claim 1, further comprising a regeneration device configured to increase the temperature of an entire flow of the exhaust gas to a desired temperature.

33. The exhaust system of claim 1, further comprising an energy extraction assembly configured to extract energy from, and reduce the pressure of, the exhaust gas.

34. The exhaust system of claim 1, further comprising cooling a flow of exhaust gas with an aftercooler.

10. (canceled)

14. A method for operating an engine, comprising the steps of:

combusting a fuel and air mixture;

exhausting at least some of the combusted fuel and air mixture as exhaust gas to an exhaust system of an engine;

cooling at least some of the combusted exhaust gas in a cooler;

measuring a level of fouling of the cooler;

measuring pressure drop of the exhaust gas across the cooler; and

determining a flowrate of the exhaust gas across the cooler as a function of pressure drop and the level of fouling of the cooler.

15. The method of claim 14, further comprising directing at least some of the cooled exhaust gas to an intake system of the engine.

16. The method of claim 14, further comprising directing cooling medium to the cooler for cooling the exhaust gas,

measuring a temperature drop of the cooling medium across the cooler,

measuring a temperature drop of the exhaust gas across the cooler, and

determining the level of fouling of the cooler as a function of the temperature drop of the cooling medium across the cooler, the temperature drop of the exhaust gas across the cooler, and the pressure drop of the exhaust gas across the cooler.

18. The method of claim 15, further comprising controlling an engine condition as a function of the measured flowrate.

19. The method of claim 18, in which the engine condition comprises at least one of injection timing, recirculated exhaust gas flowrate, variable intake valve timing, turbocharger wastegating, and regeneration of a particulate filter.

20. The method of claim 18, in which the engine condition is controlling a recirculated exhaust gas flowrate and the flowrate is controlled by controlling the position of a recirculated exhaust gas flow valve.

35. The method of claim 14, further comprising a regeneration device configured to increase the temperature of an entire flow of the exhaust gas to a desired temperature.

36. The method of claim 14, further comprising an energy extraction assembly configured to extract energy from, and reduce the pressure of, the exhaust gas.

37. The method of claim 14, further comprising cooling a flow of exhaust gas with an aftercooler.

17. (canceled)

21. An exhaust system for receiving exhaust gas of an engine, comprising:

a cooler configured to cool at least a portion of exhaust gas;

a pressure sensor configured to measure an exhaust pressure drop across the cooler;

a controller configured to determine exhaust flowrate as a function of the measured pressure drop across the cooler, the cooler comprising a cooling medium for cooling the exhaust gas;

a first set of temperature sensors configured to measure the temperature drop of the cooling medium across the cooler;

a second set of temperature sensors configured to measure the temperature drop of the exhaust gas across the cooler; and

a controller configured to determine a level of fouling within the cooler as a function of the temperature drop of the cooling medium across the cooler, the temperature drop of the exhaust gas across the cooler, and the pressure drop of the exhaust gas across the cooler.

22. The exhaust system of claim 21, further comprising a regeneration device.

23. The exhaust system of claim 22, wherein the regeneration device is fluidly connected to an energy extraction assembly via a flow line and is configured to increase the temperature of the exhaust gas to a desired temperature.

24. The exhaust system of claim 21, further comprising an energy extraction assembly.

25. The exhaust system of claim 24, wherein the energy extraction assembly is configured to extract energy from, and reduce the pressure of, the exhaust gas.

26. The exhaust system of claim 21, further comprising an aftercooler.

27. The exhaust system of claim 26, wherein the aftercooler is fluidly connected to the engine via a flow line and is configured to cool a flow of exhaust gas passing through the flow line.

28. A method for operating an engine, comprising:

combusting a fuel and air mixture;

exhausting at least some of the combusted fuel and air mixture as exhaust gas to an exhaust system of an engine;

cooling at least some of the combusted exhaust gas in a cooler;

measuring pressure drop of the exhaust gas across the cooler;

determining a flowrate of the exhaust gas across the cooler as a function of pressure drop;

measuring a temperature drop of the cooling medium across the cooler;

measuring a temperature drop of the exhaust gas across the cooler; and

determining a level of fouling of the cooler as a function of the temperature drop of the cooling medium across the cooler, the temperature drop of the exhaust gas across the cooler, and the pressure drop of the exhaust gas across the cooler.

29. The method of claim 28, further comprising increasing the temperature of an entire flow of exhaust gas produced by the engine to a desired temperature.

30. The method of claim 28, further comprising extracting energy from, and reducing the pressure of, the exhaust gas with an energy extraction assembly.

31. The method of claim 28, further comprising cooling a flow of exhaust gas with an aftercooler.