Internal combustion engine with air/fuel ratio control

• US 6,041,765 A
• Filed: 03/04/1999
• Issued: 03/28/2000
• Est. Priority Date: 12/28/1995
• Status: Expired due to Term

• Current Assignee: Cummins Engine Company Incorporated (Cummins Incorporated)
• Original Assignee: Cummins Engine Company Incorporated (Cummins Incorporated)
• Inventors: O'Neill, Jeff S., Carroll, Matthew S., Connally, John A., Zigan, Jim A., Iwamuro, Martin A.
• Primary Examiner(s): ARGENBRIGHT, TONY MICHAEL
• Application Number:
  US09/262,435
• Time in Patent Office: 390 Days
• Field of Search: 123/478, 123/527, 123/528, 123/683, 123/684
• US Class Current: 123/683
• CPC Class Codes: F02D 19/023 to adjust the fuel mass or volume flow
• CPC Class Codes: F02D 19/025 Failure diagnosis or prevention; Safety measures; Testing
• CPC Class Codes: F02D 19/027 Determining the fuel pressure, temperature or volume flow, the fuel tank fill level or a valve position
• CPC Class Codes: F02D 2200/0402 the parameter being determined by using a model of the engine intake or its components
• CPC Class Codes: F02D 41/0027 the fuel being gaseous non-electrical control F02D19/02
• CPC Class Codes: F02D 41/18 by measuring intake air flow
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

Engine (60) has manifold (62) and includes an air pathway (20) and a fuel line (30) coupled to the manifold (62) for supplying a fuel charge. Fuel line (30) has a controllable valve (40) for regulating fuel flow and a first sensor (38) providing a fuel signal corresponding to mass flow rate of fuel through the fuel line. A second sensor (65) provides a speed signal corresponding to rotational speed of the engine. A third sensor (63) provides a temperature signal corresponding to temperature within the manifold. A fourth sensor (64) provides a pressure signal corresponding to pressure within the manifold. A fifth sensor (76) provides an exhaust signal corresponding to air/fuel ratio for combusted air and fuel in the exhaust pathway. A controller (80) responsive to the controllable valve (40) and sensors (38), (63), (64), (65), and (76) determines an air signal corresponding to the mass flow rate of air through the air pathway (20) as a function of the speed signal, temperature signal, and pressure signal. The controller actuates a valve control signal in accordance with the air signal, fuel signal, and exhaust signal to actuate fuel control valve actuator (42).

Claims

1. A system, comprising:

an internal combustion engine including a manifold, an air pathway coupled to said manifold to supply air, and a fuel line coupled to said manifold to supply gaseous fuel, said fuel line including a controllable valve for regulating fuel flow therethrough;

a first sensor providing a first signal corresponding to mass flow rate of fuel through said fuel line;

a second sensor providing a second signal corresponding to rotational speed of said engine;

a third sensor providing a third signal corresponding to pressure within said manifold;

a fourth sensor providing a fourth signal corresponding to temperature within said manifold;

a controller responsive to said first, second, third, and fourth signals to determine a fifth signal as a function of said second, third, and fourth signals corresponding to air mass flow rate through said air pathway, and generate an sixth signal in accordance with said first and fifth signals; and

wherein said controllable valve is a rotary actuated butterfly valve, actuation of said butterfly valve being limited to a predetermined range, and said controllable valve is responsive to said sixth signal to adjust the rate of fuel flow through said fuel line.

2. The system of claim 1, further comprising:

an air/fuel mixer in fluid communication with said pathway, said fuel line, and said manifold, said mixer being operable to supply a mixture of fuel and air to said manifold for combustion;

a throttle valve in fluid communication with said mixer and said manifold and being positioned therebetween, said throttle for regulating flow of the mixture to said manifold; and

a fifth sensor providing a throttle signal corresponding to position of said throttle valve, said controller being responsive to said throttle signal to further control performance of said engine.

3. The system of claim 1, wherein said engine has an exhaust pathway with a fifth sensor to provide an exhaust signal corresponding to air/fuel ratio of a combusted mixture of air and fuel, and said valve control signal is further provided in accordance with said exhaust signal.

4. The system of claim 1, wherein said function corresponds to the speed-density equation.

5. The system of claim 1, wherein said controller includes means for compensating for transient operation of said engine.

6. The system of claim 1, wherein said engine has an exhaust pathway with a fifth sensor to provide an exhaust signal corresponding to an observed air/fuel ratio of a combusted mixture of air and fuel, and said controller is responsive to said exhaust signal to compare said exhaust signal to a target air/fuel ratio signal and determine a target fuel mass flow rate from said target air/fuel ratio signal.

7. The system of claim 1, further comprising:

a mixer in fluid communication with said pathway, said fuel line, and said manifold, said mixer providing a mixture of fuel and air to said manifold;

a throttle valve in fluid communication with said mixer and said manifold and being positioned therebetween to regulate flow of the mixture to said manifold;

a compressor in fluid communication with said pathway for supplying pressurized air to said mixer;

an after cooler in fluid communication with said compressor and said mixer and being positioned therebetween; and

a fifth sensor providing a throttle control signal corresponding to position of said throttle valve, said controller being responsive to said fifth signal to further control performance of said engine.

8. The system of claim 7, wherein said engine has an exhaust pathway with a fifth sensor to provide an exhaust signal corresponding to air/fuel ratio of a combusted mixture of air and fuel, and said valve control signal is further provided in accordance with said exhaust signal.

9. The system of claim 8, wherein said controller includes means for determining a target fuel mass flow rate from said exhaust signal and a target air/fuel ratio.

10. The system of claim 9, wherein said controller includes means for compensating for transient operation of said engine.

11. The system of claim 10, wherein said function corresponds to the speed-density equation.

12. The system of claim 2, wherein said engine has an exhaust pathway with a fifth sensor to provide an exhaust signal corresponding to air/fuel ratio of a combusted mixture of air and fuel, and said valve control signal is further provided in accordance with said exhaust signal.

13. The system of claim 2, wherein said function corresponds to the speed-density equation.

14. The system of claim 2, wherein said controller includes means for compensating for transient operation of said engine.

15. The system of claim 3, wherein said controller includes means for determining a target fuel mass flow rate from said exhaust signal and a target air/fuel ratio.

16. A system, comprising:

an internal combustion engine including a manifold, an air pathway coupled to said manifold for supplying air, and a fuel line coupled to said manifold for supplying gaseous fuel, said fuel line including a rotary actuated butterfly valve for regulating the flow of fuel through said fuel line;

a first sensor providing a first signal corresponding to mass flow rate of fuel through said fuel line;

a second sensor providing a second signal corresponding to rotational speed of said engine;

a third sensor providing a third signal corresponding to air mass flow rate through said air pathway;

a controller responsive to said butterfly valve and said first, second, and third signals to provide a valve control signal; and

wherein said butterfly valve is responsive to said valve control signal to adjust fuel flow through said fuel line, actuation of said butterfly valve is limited to a predetermined range, and said valve control signal is determined in accordance with an air/fuel ratio.

17. The system of claim 16, further comprising:

a mixer in fluid communication with said pathway, said fuel line, and said manifold, said mixer providing a mixture of fuel and air to said manifold;

a throttle valve in fluid communication with said mixer and said manifold and being positioned therebetween to regulate flow of the mixture to said manifold; and

a compressor in fluid communication with said pathway for supplying pressurized air to said mixer; and

an after cooler in fluid communication with said compressor and said mixer and being positioned therebetween; and

a fourth sensor providing a fourth signal corresponding to position of said throttle valve, said controller being responsive to said fourth signal to further control performance of said engine.

18. The system of claim 16, wherein said engine has an exhaust pathway with a fourth sensor to provide an exhaust signal corresponding to the air/fuel ratio of a combusted mixture of air and fuel, and said valve control signal is further provided in accordance with said exhaust signal.

19. The system of claim 16, wherein said controller includes means for compensating for transient operation of said engine.

20. The system of claim 16, wherein said engine has an exhaust pathway with a fourth sensor to provide an exhaust signal corresponding to an observed air/fuel ratio of a combusted mixture of air and fuel, and said controller is responsive to said exhaust signal to compare said exhaust signal to a target air/fuel ratio signal, and determine a target fuel mass flow rate from said target air/fuel ratio signal.

21. The system of claim 16, wherein said engine has an exhaust pathway with a fourth sensor to provide an exhaust signal corresponding to the air/fuel ratio of a combusted mixture of air and fuel, and said valve control signal is further provided in accordance with said exhaust signal;

and further comprising;

a mixer in fluid communication with said pathway, said fuel line, and said manifold, said mixer providing a mixture of fuel and air to said manifold;

a throttle valve in fluid communication with said mixer and said manifold and being positioned therebetween to regulate flow of the mixture to said manifold;

a fifth sensor providing a fifth signal corresponding to position of said throttle valve, said controller being responsive to said fifth signal to further control performance of said engine.

22. The system of claim 21, wherein said controller includes means for determining a target fuel mass flow rate from said exhaust signal and a target air/fuel ratio.

23. The system of claim 22, wherein said controller includes means for compensating for transient operation of said engine.

24. The system of claim 17, wherein said engine has an exhaust pathway with a fifth sensor to provide an exhaust signal corresponding to air/fuel ratio of a combusted mixture of air and fuel, and said valve control signal is further provided in accordance with said exhaust signal.

25. The system of claim 17, wherein said controller includes means for compensating for transient operation of said engine.

26. The system of claim 18, wherein said controller includes means for determining a target fuel mass flow rate from said exhaust signal and a target air/fuel ratio.