Closed loop cold start retard spark control using ionization feedback

• US 7,104,043 B2
• Filed: 06/11/2003
• Issued: 09/12/2006
• 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: Zhu, Guoming G., Daniels, Chao F.
• Primary Examiner(s): Tran, Binh Q.
• Application Number:
  US10/458,711
• Publication Number:
  US 20040083717A1
• Time in Patent Office: 1,189 Days
• Field of Search: 602/74, 602/84, 602/85, 123/406.11, 123/406.13, 123/406.14, 123/406.44, 123/406.55, 701/107, 701/113, 701/115
• US Class Current: 60/284
• 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 35/021 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 41/005 according to engine operating conditions
• 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 5/152 : dependent on pinking detecting or indicating knocks in internal-combustion engines G01L23/22
• 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

This feature of the present invention comprises a method and apparatus to retard the spark time. As a result, the catalyst heats up quickly during the cold start. The retard spark control method of the present invention uses a closed loop to adjust the engine retard limit during an engine cold start to retard the engine spark as much as possible without engine misfire and with minimum partial burn. The increased exhaust temperature heats up the catalyst more quickly than conventional open loop approaches, which as a result, reduces hydrocarbon emissions. The closed loop retard spark control using ionization current feedback consists of four major components or functions, an error and gain generator, a proportional and integration control processing block, a default spark timing processor, and an adaptive learning apparatus.

Claims

1. A method of reducing cold-start hydrocarbon emission during a cold start, comprising heating up a catalyst during a cold start by retarding a spark time to raise an exhaust temperature, wherein said step of heating up a catalyst comprises the steps of:

checking at least one index signal state;

moving an ignition timing signal in a retard direction if a partial burn index and a misfire index are inactive;

moving said ignition timing signal in an advance direction if said partial burn index is active and said misfire index is inactive; and

adding an offset and moving said ignition timing signal in said advance direction if a misfire index is active.

2. The method according to claim 1 further comprising the step of comparing said ignition timing signal with a default timing signal generated from an engine'"'"'s current operating conditions.

3. The method according to claim 1 further comprising the step of summing a reference signal and a control signal to produce said ignition timing signal.

4. The method according to claim 1 wherein said step of moving an ignition timing signal in a retard direction if a partial burn index and a retard index are inactive further comprises:

setting a closed loop error signal to one;

setting a proportional gain of a closed loop gain signal to zero; and

setting an integration gain of said closed loop gain signal to a positive value.

5. The method according to claim 1 wherein said step of moving said ignition timing signal in an advance direction if a partial burn index is active and a misfire index is inactive further comprises:

setting a closed loop error signal to negative one;

setting a proportional gain of a closed loop gain signal to zero; and

setting an integration gain of said closed loop gain signal to a positive value.

6. The method according to claim 1 wherein said step of adding an offset and moving said ignition timing signal in said advance direction if a misfire index is active further comprises:

setting a closed loop error signal to negative one;

setting a proportional gain of a closed loop gain signal to zero; and

setting an integration gain of said closed loop gain signal to a positive value.

7. The method according to claim 1 further comprising the step of generating a misfire index when a peak value of an ionization current is detected during combustion.

8. The method according to claim 1 further comprising the step of generating an enable flag when a catalyst temperature crosses a threshold.

9. The method according to claim 1 further comprising the steps of:

comparing said ignition timing signal with1 a default timing signal generated from an engine'"'"'s current operating conditions; and

summing a reference signal and a control signal to produce said ignition timing signal.

10. The method according to claim 4 wherein said step of moving said ignition timing signal in an advance direction if a partial burn index is active and a misfire index is inactive further comprises:

setting a closed loop error signal to negative one;

setting a proportional gain of a closed loop gain signal to zero; and

setting an integration gain of said closed loop gain signal to a positive value; and

wherein said step of adding an offset and moving said ignition timing signal in said advance direction if a misfire index is active further comprises;

setting a closed loop error signal to negative one;

setting a proportional gain of a closed loop gain signal to zero; and

setting an integration gain of said closed loop gain signal to a positive value.

11. A method of reducing cold-start hydrocarbon emission during a cold start, comprising heating up a catalyst during a cold start by retarding a spark time to raise an exhaust temperature, wherein the step of retarding a spark time to raise an exhaust temperature is carried out by a spark controller, said spark controller comprising:

an error and gain generator having a plurality of inputs and outputs;

an integration controller having a plurality of inputs operably connected to said plurality of outputs of said error and gain generator;

a summer having a first input operably connected to an output of said integration controller; and

a feedback controller having an output operably connected to a second input of said summer and a first input operably connected to an output of said summer.

12. The method according to claim 11, wherein said feedback controller comprises:

a timing processor having an output operably connected to a second input of said summer; and

an adaptive learning apparatus having an output operably connected to an input of said timing processor and a first input operably connected to an output of said summer.

13. The method according to claim 12 wherein said plurality of inputs of said error and gain generator comprise at least one index signal input.

14. The method according to claim 12 wherein said plurality of inputs of said error and gain generator comprise a partial burn index signal input and a misfire index signal input.

15. The method according to claim 12 wherein said adaptive learning apparatus comprises:

a processor having an engine speed signal input, an engine load signal input, and an engine coolant temperature signal input; and

a comparator having a first input connected to said output of said summer and a second input operably connected to an output of said processor, whereby a timing signal generated from an engine'"'"'s current operating condition is compared with a current timing signal.

16. The method according to claim 12 wherein said timing processor comprises a plurality of inputs.

17. The method according to claim 12 wherein said adaptive learning apparatus comprises an engine speed signal input, an engine load signal input, and a coolant input.

18. The method according to claim 14 wherein said adaptive learning apparatus comprises:

a processor having an engine speed signal input, an engine load signal input, and an engine coolant temperature signal input; and

a comparator having a first input connected to said output of said summer and a second input operably connected to an output of said processor, whereby a timing signal generated from an engine'"'"'s current operating condition is compared with a current timing signal; and

wherein said dining processor comprises an engine speed signal input, an engine load signal input, and a coolant input.

19. The method according to claim 16 wherein said timing plurality of inputs of said timing processor comprises an engine speed signal input an engine load signal input, and a coolant input.