Closed-loop individual cylinder A/F ratio balancing

• US 20040084025A1
• Filed: 06/11/2003
• Published: 05/06/2004
• Est. Priority Date: 11/01/2002
• Status: Active Grant

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Daniels, Chao F., Zhu, Guoming G.
• Granted Patent: US 7,021,287 B2
• Time in Patent Office: Days
• US Class Current: 123/435
• CPC Class Codes: F01N 2430/00 Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
• CPC Class Codes: F01N 3/2006 Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235
• CPC Class Codes: F02D 2041/141 using a feed-forward control element
• CPC Class Codes: F02D 2041/285 the sensor having a signal processing unit external to the engine control unit
• CPC Class Codes: F02D 2200/1015 Engines misfires
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 35/02 on interior conditions
• CPC Class Codes: F02D 35/021 using an ionic current sensor
• CPC Class Codes: F02D 35/023 by determining the cylinder pressure
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02D 35/028 by determining the combustion timing or phasing
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• CPC Class Codes: F02D 41/0052 Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
• CPC Class Codes: F02D 41/0085 Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio
• CPC Class Codes: F02D 41/0255 to accelerate the warming-up of the exhaust gas treating apparatus at engine start
• CPC Class Codes: F02D 41/1408 Dithering techniques
• CPC Class Codes: F02D 41/1482 Integrator, i.e. variable slope
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: F02D 41/2454 Learning of the air-fuel ratio control
• CPC Class Codes: F02M 26/01 Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
• CPC Class Codes: F02P 17/02 : Checking or adjusting ignition timing
• CPC Class Codes: F02P 17/10 : Measuring dwell or antidwell time
• CPC Class Codes: F02P 17/12 : Testing characteristics of the spark, ignition voltage or current testing of sparking plugs H01T13/60
• CPC Class Codes: F02P 2017/125 : Measuring ionisation of combustion gas, e.g. by using ignition circuits
• CPC Class Codes: F02P 2017/128 : for knock detection
• CPC Class Codes: F02P 3/045 : for control of the dwell or anti dwell time
• CPC Class Codes: F02P 3/0453 : Opening or closing the primary coil circuit with semiconductor devices
• CPC Class Codes: F02P 3/051 : Opening or closing the primary coil circuit with semiconductor devices
• CPC Class Codes: F02P 5/1506 : with particular means during starting
• CPC Class Codes: F02P 5/1514 : with means for optimising the use of registers or of memories, e.g. interpolation
• CPC Class Codes: F02P 5/1523 : with particular laws of return to advance, e.g. step by step, differing from the laws of retard
• CPC Class Codes: F02P 5/1526 : with means for taking into account incorrect functioning of the pinking sensor or of the electrical means
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

The individual cylinder air to fuel ratio of an internal combustion engine varies due to the fact that the intake manifold cannot distribute airflow into the individual cylinders evenly. This feature of the present invention utilizes minimum timing for best torque MBT timing criterion provided by the ionization signals or by the in-cylinder pressure signals to balance the air to fuel ratios of the individual cylinders. The control method of the present invention comprises: calculating a mean timing coefficient, calculating a timing coefficient error, integrating the minimum timing for best torque timing coefficient error, calculating a raw fuel trim coefficient, resealing the raw fuel trim coefficient, updating a feedforward look-up table based upon the current engine operating conditions, and calculating a final fueling command.

Claims

1. A method of balancing individual cylinder air to fuel ratios, comprising inputting at least one timing coefficient into closed loop control.

2. The method of balancing individual cylinder air to fuel ratios according to claim 1 wherein said step of inputting at least one timing coefficient comprises:

calculating a mean timing coefficient;

calculating a timing coefficient error;

integrating said timing coefficient error;

calculating a raw fuel trim coefficient;

rescaling said raw fuel trim coefficient;

updating a feedforward look-up table based upon the current engine operating conditions; and

calculating a final fueling command.

3. The method of balancing individual cylinder air to fuel ratios according to claim 2 wherein said mean timing coefficient is a mean minimum timing for best torque timing coefficient;

and

wherein said timing coefficient error is a minimum timing for best torque timing coefficient error.

4. The method of balancing individual cylinder air to fuel ratios according to claim 2 wherein said step of rescaling said raw fuel trim coefficient further comprises applying saturations.

5. The method of balancing individual cylinder air to fuel ratios according to claim 2 wherein said step of calculating a raw fuel trim coefficient comprises adding an integration timing coefficient error and a feedforward fuel trim coefficient.

6. The method of balancing individual cylinder air to fuel ratios according to claim 2 further comprising the step of trimming the air to fuel ratios of individual cylinders.

7. The method of balancing individual cylinder air to fuel ratios according to claim 3 wherein said step of resealing said raw fuel trim coefficient further comprises applying saturations and wherein said step of calculating a raw fuel trim coefficient comprises adding an integration timing coefficient error and a feedforward fuel trim coefficient.

8. The method of balancing individual cylinder air to fuel ratios according to claim 6 wherein said trimming is run once every engine cycle.

9. The method of balancing individual cylinder air to fuel ratios according to claim 6 wherein said step of calculating a final fueling command comprises multiplying a fueling command by a final fuel trim coefficient.

10. A method of controlling a cylinder'"'"'s air to fuel ratio;

comprising the steps of;

calculating timing criterion of said cylinder; and

controlling said cylinder'"'"'s air to fuel ratio using said timing criterion.

11. The method of controlling a cylinder'"'"'s air to fuel ratio according to claim 10 wherein said step of controlling said cylinder'"'"'s air to fuel ratio using said timing criterion comprises inputting at least one minimum timing for best torque timing coefficient.

12. The method of controlling a cylinder'"'"'s air to fuel ratio according to claim 11 wherein said timing criterion is calculated using an ionization signal.

13. The method of controlling a cylinder'"'"'s air to fuel ratio according to claim 11 wherein said timing criterion is calculated using an in-cylinder pressure signal.

14. The method of balancing individual cylinder air to fuel ratios according to claim 11 wherein said step of inputting at least one minimum timing for best torque timing coefficient comprises:

calculating a mean minimum timing for best torque timing coefficient;

calculating a minimum timing for best torque timing coefficient error;

integrating said minimum timing for best torque timing coefficient error;

calculating a raw fuel trim coefficient;

resealing said raw fuel trim coefficient;

updating a feedforward look-up table based upon the current engine operating conditions; and

calculating a final fueling command.

15. An air to fuel ratio control system, comprising:

an ionization detection circuit;

a controller operably connected to said ionization detection circuit;

memory; and

software stored in said memory, wherein said software comprises instructions which control a cylinder'"'"'s air to fuel ratio using timing criterion.

16. The air to fuel ratio control system according to claim 15 wherein said timing criterion is minimum timing for best torque timing criterion.

17. The MBT estimator according to claim 16 further comprising a lookup table operably connected to said controller, wherein feedforward fuel trim coefficients are stored.

18. The air to fuel ratio control system according to claim 16 wherein said instructions which control a cylinder'"'"'s air to fuel ratio using timing criterion comprise:

calculating a mean timing coefficient;

calculating a timing coefficient error;

integrating said timing coefficient error;

calculating a raw fuel trim coefficient;

resealing said raw fuel trim coefficient;

updating a feedforward look-up table based upon the current engine operating conditions; and

calculating a final fueling command.

19. The air to fuel ratio control system according to claim 18 wherein said mean timing coefficient is a mean minimum timing for best torque timing coefficient;

and

wherein said timing coefficient error is a minimum timing for best torque timing coefficient error.

20. The air to fuel ratio control system according to claim 18 wherein said software further comprises instructions to trim the air to fuel ratios of individual cylinders.