Internal combustion engine with air/fuel ratio control

• US 5,904,131 A
• Filed: 12/28/1995
• Issued: 05/18/1999
• Est. Priority Date: 12/28/1995
• Status: Expired due to Term

• Current Assignee: Cummins Engine IP Inc (Cummins Incorporated)
• Original Assignee: Cummins Engine Company Incorporated (Cummins Incorporated)
• Inventors: Carroll, Matthew S., Connally, John A., Zigan, Jim A., Iwamuro, Martin A., O'Neill, Jeff S.
• Primary Examiner(s): ARGENBRIGHT, TONY MICHAEL
• Application Number:
  US08/579,839
• Time in Patent Office: 1,237 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 method of controlling an internal combustion engine, with a manifold coupled to an air pathway and a gaseous fuel line, the engine being configured to combust a mixture of air from the pathway and gaseous fuel from the fuel line, comprising the steps of:

(1) sensing engine speed;

(2) sensing manifold pressure;

(3) sensing manifold temperature;

(4) determining air mass flow rate as a function of sensed engine speed, manifold pressure, and manifold temperature;

(5) sensing fuel mass flow rate in the fuel line; and

(6) controlling fuel flow through the fuel line in accordance with air mass flow rate determined in step (4) and sensed fuel mass flow rate of step (5), wherein the engine includes an exhaust stream and a controllable valve to regulate fuel flow in the fuel line, and step (6) further includes the steps of;

(6a) establishing a target air/fuel ratio;

(6b) sensing air/fuel ratio from the exhaust stream;

(6c) determining a first fuel mass flow rate as a function of the sensed air/fuel ratio of step (6b) and the target air/fuel ratio of step (6a);

(6d) determining a second fuel mass flow rate as a function of the target air/fuel ratio and the air mass flow rate determined in step (4);

(6e) establishing a target fuel mass flow rate as a function of the first fuel mass flow rate determined in step (6c) and the second fuel mass flow rate determined in step (6d);

(6f) generating a valve control signal as a function of the sensed fuel mass flow rate of step (5) and the target fuel mass flow rate of step (6e); and

(6g) actuating the controllable valve in response to the valve control signal generated in step (6f).

2. The method of claim 1, wherein step (6) further includes the step of compensating for transient operation of the engine.

3. The method of claim 1, wherein step (6) further includes the step of compensating the first fuel mass flow rate as a function of the air mass flow rate of step (4).

4. The method of claim 1, wherein step (6) further includes the step of limiting the valve control signal to a predetermined range.

5. The method of claim 1, wherein said controllable valve is a rotary actuated butterfly valve.

6. An internal combustion engine having a manifold and configured to combust a mixture of air and gaseous fuel, comprising:

an air pathway coupled to the manifold for supplying air;

a fuel line coupled to the manifold for supplying gaseous fuel thereto, said fuel line having;

a controllable valve for regulating fuel flow through said fuel line; and

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

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

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

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

a controller responsive to said controllable valve and said first, second, third, and fourth sensors to;

determine an air signal corresponding to the mass flow rate of air through said pathway as a function of said speed signal, said pressure signal, and said temperature signal; and

provide a valve control signal in accordance with said air signal and said fuel signal; and

wherein said controllable valve is responsive to said valve control signal to adjust the rate of fuel flow through said fuel line, 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 controller further determines;

a target air/fuel ratio;

a first fuel mass flow rate as a function of said target air/fuel ratio and said exhaust signal;

a second fuel mass flow rate as a function of said target air/fuel ratio and said air signal; and

a target fuel mass flow rate as a function of said first fuel mass flow rate and said second fuel mass flow rate, said valve control signal being further provided as a function of said target fuel mass flow rate.

7. The engine of claim 6, wherein said controllable valve is a rotary actuated butterfly valve.

8. The engine of claim 6, wherein said controllable valve is a linear actuated poppet valve.

9. The engine of claim 6, further comprising an air/fuel mixer in fluid communication with said pathway, said fuel line, and said manifold.

10. The engine of claim 6, further comprising:

a mixer in fluid communication with said pathway, said fuel line and said manifold, said mixer for supplying the mixture of fuel and air to said manifold for combustion; and

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.

11. The engine of claim 10, further comprising:

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

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

12. The engine of claim 10, further comprising 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.

13. A method of controlling an internal combustion engine, with a manifold coupled to an air pathway and a fuel line, the fuel line having a rotary actuated butterfly valve operable to regulate the flow of gaseous fuel therethrough, the engine being configured to combust a mixture of air from the pathway and gaseous fuel from the fuel line, comprising the steps of:

(1) determining air mass flow rate through said air pathway;

(2) sensing fuel mass flow rate in the fuel line;

(3) actuating the butterfly valve in accordance with sensed air mass flow rate determined in step (1) and fuel mass flow rate sensed in step (2) to thereby regulate the flow of fuel through the fuel line; and

(4) limiting actuation of the butterfly valve in step (3) to a predetermined range.

14. The method of claim 13, wherein step (1) includes the steps of:

(1a) sensing engine speed; and

(1b) sensing manifold pressure.

15. The method of claim 13, wherein the air mass flow rate is generally determined in accordance with the speed density equation.

16. The method of claim 13, wherein the engine includes an exhaust stream and further comprises the steps of:

(5) establishing a target air/fueld ratio;

(6) sensing air/fuel ratio from the exhaust stream;

(7) determining a first fuel mass flow rate as a function of the sensed air/fuel ratio of step (6) and the target air/fuel ratio of step (5);

(8) compensating the first fuel mass flow rate of step (7) as a function of sensed air mass flow rate of step (1);

(9) determining a second fuel mass flow rate as a function of the target air/fuel ratio and the air mass flow rate of step (1);

(10) establishing a target fuel mass flow rate as a function of the first fuel mass flow rate determined in step (7) and the second fuel mass flow rate determined in step (9); and

(11) generating a valve control signal as a function of the sensed fuel mass flow rate of step (2) and the target fuel mass flow rate of step (10), actuation of the butterfly valve in step (3) being responsive to the valve control signal.

17. An internal combustion engine having a manifold and configured to combust a mixture of air and gaseous fuel, comprising:

an air pathway coupled to the manifold for supplying air;

a fuel line coupled to the manifold for supplying gaseous fuel thereto, said fuel line having;

a rotary actuated butterfly valve for regulating the flow of fuel through said fuel line; and

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

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

a controller responsive to said first and second sensors to generate an air mass flow rate signal as a function of at least said speed signal and to provide a valve control signal in accordance with said air mass flow rate signal and said fuel signal; and

wherein said butterfly valve is responsive to said valve control signal to adjust the rate of fuel flow through said fuel line, and actuation of said butterfly valve is limited to a predetermined range by said controller.

18. The engine of claim 17, further comprising:

a mixer in fluid communication with said pathway, said fuel line and said manifold, said mixer for supplying the mixture of fuel and air to said manifold for combustion; and

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.

19. The engine of claim 18, further comprising:

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

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

20. The engine of claim 18, further comprising a third 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.

21. The engine of claim 17, wherein:

said engine has an exhaust pathway with a third 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.

22. A method of controlling an internal combustion engine, with a manifold coupled to an air pathway and a gaseous fuel line, the engine being configured to combust a mixture of air from the pathway and gaseous fuel from the fuel line and having an exhaust stream generated by combustion, comprising the steps of:

(1) sensing engine speed;

(2) sensing an engine parameter, the engine parameter being one of manifold temperature and manifold pressure;

(3) determining air mass flow rate in the pathway as a function of sensed engine speed and the engine parameter;

(4) sensing fuel mass flow rate in the fuel line;

(5) sensing air/fuel ratio of a combusted mixture of air and fuel in the exhaust stream; and

(6) controlling fuel flow in the fuel line in accordance with air mass flow rate determined in step (3), sensed fuel mass flow rate of step (4), and sensed air/fuel ratio of step (5), said controlling further including;

establishing a target air/fuel ratio;

determining a first fuel mass flow rate as a function of the air/fuel ratio of the combusted mixture and the target air/fuel ratio;

determining a second fuel mass flow rate as a function of the target air/fuel ratio and the air mass flow rate;

establishing a target fuel mass flow rate as a function of the first fuel mass flow rate and the second fuel mass flow rate; and

actuating a controllable valve in accordance with the target fuel mass flow rate.

23. The method of claim 22, wherein step (5) includes sensing oxygen level in said exhaust stream.

24. The method of claim 22, wherein the engine parameter is manifold pressure.

25. The method of claim 22, wherein the air mass flow rate is generally determined in accordance with the speed density equation.

26. The method of claim 22, wherein the controllable valve is a rotary actuated butterfly valve and said controlling further includes limiting actuation of the butterfly valve to a predetermined range.

27. An internal combustion engine configured to combust a mixture of air and gaseous fuel and having a manifold and exhaust pathway, comprising:

an air pathway coupled to the manifold for supplying air;

a fuel line coupled to the manifold for supplying gaseous fuel thereto, said fuel line having;

a controllable valve for regulating fuel flow through said fuel line; and

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

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

a third sensor providing a manifold signal corresponding to one of temperature and pressure within the manifold;

a fourth sensor providing an exhaust signal corresponding to air/fuel ratio for combusted air and fuel in the exhaust pathway;

a controller responsive to said controllable valve and said first, second, third, and fourth sensors to;

determine an air signal corresponding to the mass flow rate of air through said pathway as a function of said speed signal and said manifold signal; and

provide a valve control signal in accordance with said air signal, said fuel signal, and said exhaust signal; and

wherein said controllable valve is responsive to said valve control signal to adjust the rate of fuel flow through said fuel line, and said controller further determines;

a target air/fuel ratio;

a first fuel mass flow rate as a function of said target air/fuel ratio and said exhaust signal;

a second fuel mass flow rate as a function of said target air/fuel ratio and said air signal; and

a target fuel mass flow rate as a function of said first fuel mass flow rate and said second fuel mass flow rate, said valve control signal being further determined as a function of said target fuel mass flow rate.

28. The engine of claim 27, wherein said fourth sensor detects oxygen level in the exhaust pathway.

29. The engine of claim 27, wherein said controllable valve is a linear actuated poppet valve.

30. The engine of claim 27, further comprising:

a mixer in fluid communication with said pathway, said fuel line and said manifold, said mixer for supplying the mixture of fuel and air to said manifold for combustion; and

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.

31. The engine of claim 30, further comprising:

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

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

32. The engine of claim 30, further comprising 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.

33. The engine of claim 27, wherein said controllable valve is a rotary actuated butterfly valve and actuation of said butterfly valve is limited to a predetermined range by