Engine control system and method

• US 5,724,951 A
• Filed: 03/29/1996
• Issued: 03/10/1998
• Est. Priority Date: 03/31/1995
• Status: Expired due to Term

• Current Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Original Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Inventors: Mukumoto, Kyoji
• Primary Examiner(s): Wolfe, Willis R.
• Application Number:
  US08/625,174
• Time in Patent Office: 711 Days
• Field of Search: 123/333, 123/481, 123/198 F, 123/672, 123/679, 123/687, 123/689
• US Class Current: 123/687
• CPC Class Codes: F02D 41/1479 Using a comparator with variable reference
• CPC Class Codes: F02D 41/2448 Prohibition of learning
• CPC Class Codes: F02D 41/2454 Learning of the air-fuel ratio control
• CPC Class Codes: F02D 41/266 the computer being backed-up or assisted by another circuit, e.g. analogue

Abstract

A control system and method for a multi cylinder engine that employs a single sensor associated with only one of the combustion chambers for feedback control of that combustion chamber and for controlling the fuel/air ratio of the remaining combustion chambers. The control of the remaining combustion chambers is based upon the value of the feedback control upon the time of shifting between lean and rich mixtures. The reference value is selected, however, after the initial switch between rich and lean so as to permit time for stabilization. Engine protection is accomplished by cylinder diseabling. At that time feed back control is discontinued.

Claims

1. An internal combustion engine having a plurality of combustion chambers, a fuel/air charging system for delivering a fuel/air charge to said combustion chambers for combustion therein, a fuel/air ratio sensor for measuring the fuel/air ratio, feedback control means for controlling the fuel/air ratio supplied to said engine to maintain the desired fuel/air ratio therein by shifting between the rich side of said desired ratio and the lean side of said desired ratio, means for sensing an undesirable engine condition, means for disabling the running of at least one of said combustion chambers when the undesirable engine condition is sensed, and means for discontinuing feed back control when the combustion chamber running is disabled.

2. An internal combustion engine as set forth in claim 1 wherein the undesirable condition is comprised of at least one of high engine temperature, low oil level, engine overspeed or a reduction of speed of another engine.

3. An internal combustion engine as set forth in claim 1 wherein the fuel/air ratio in only one combustion chamber is sensed and further including means for controlling the fuel/air ratio of the remaining combustion chambers from the setting for said one combustion chamber at the time of shift.

4. An internal combustion engine as set forth in claim 3, wherein the control of the fuel/air ratio for the remaining combustion chambers is based upon the value of the one combustion chamber sensed after the first shift between the rich and lean sides.

5. An internal combustion engine as set forth in claim 4, further including means for sensing engine running conditions and setting a basic fuel/air ratio upon said measured engine running conditions.

6. An internal combustion engine as set forth in claim 5, wherein the feedback control is employed for correcting the basic fuel/air ratio to maintain the desired fuel/air ratio.

7. An internal combustion engine as set forth in claim 6 wherein the undesirable condition is comprised of at least one of high engine temperature, low oil level, engine overspeed or a reduction of speed of another engine.

8. An internal combustion engine as set forth in claim 7 wherein the fuel/air ratio in only one combustion chamber is sensed and further including means for controlling the fuel/air ratio of the remaining combustion chambers from the setting for said one combustion chamber at the time of shift.

9. An internal combustion engine as set forth in claim 8, wherein the control of the fuel/air ratio for the remaining combustion chambers is based upon the value of the one combustion chamber sensed after the first shift between the rich and lean sides.

10. A method of operating an internal combustion engine having a plurality of combustion chambers, a fuel/air charging system for delivering a fuel/air charge to said combustion chambers for combustion therein, said method comprising the steps of measuring the fuel/air ratio, controlling the fuel/air ratio supplied to said engine to maintain the desired fuel/air ratio therein by shifting between the rich side of said desired ratio and the lean side of said desired ratio, sensing an undesirable engine condition, disabling the running of at least one of said combustion chambers when the undesirable engine condition is sensed, and discontinuing feed back control when the combustion chamber running is disabled.

11. A method as set forth in claim 10 wherein the undesirable condition is comprised of at least one of high engine temperature, low oil level, engine overspeed or a reduction of speed of another engine.

12. A method as set forth in claim 10 wherein the fuel/air ratio in only one combustion chamber is sensed and further including the step of controlling the fuel/air ratio of the remaining combustion chambers from the setting for said one combustion chamber at the time of shift.

13. A method as set forth in claim 12, wherein the control of the fuel/air ratio for the remaining combustion chambers is based upon the value of the one combustion chamber sensed after the first shift between the rich and lean sides.

14. A method as set forth in claim 13, further including means for sensing engine running conditions and setting a basic fuel/air ratio upon said measured engine running conditions.

15. A method as set forth in claim 14, wherein the feedback control is employed for correcting the basic fuel/air ratio to maintain the desired fuel/air ratio.

16. A method as set forth in claim 15 wherein the undesirable condition is comprised of at least one of high engine temperature, low oil level, engine overspeed or a reduction of speed of another engine.

17. A method as set forth in claim 16 wherein the fuel/air ratio in only one combustion chamber is sensed and further including means for controlling the fuel/air ratio of the remaining combustion chambers from the setting for said one combustion chamber at the time of shift.

18. A method as set forth in claim 17, wherein the control of the fuel/air ratio for the remaining combustion chambers is based upon the value of the one combustion chamber sensed after the first shift between the rich and lean sides.