Engine feedback control embodying learning

• US 5,813,390 A
• Filed: 09/17/1996
• Issued: 09/29/1998
• Est. Priority Date: 04/11/1995
• Status: Expired due to Fees

• Current Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Original Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Inventors: Anamoto, Takayuki
• Primary Examiner(s): Wolfe, Willis R.
• Application Number:
  US08/714,945
• Time in Patent Office: 742 Days
• Field of Search: 123/674, 123/675, 123/672, 123/695
• US Class Current: 123/674
• CPC Class Codes: F02B 2075/025 two
• CPC Class Codes: F02D 2400/04 Two-stroke combustion engines with electronic control
• CPC Class Codes: F02D 41/2445 characterised by a plurality of learning conditions or ranges
• CPC Class Codes: F02D 41/2454 Learning of the air-fuel ratio control
• CPC Class Codes: F02D 41/2474 Characteristics of sensors

Abstract

A feedback control system and method for operating an internal combustion engine to provide the desired air/fuel ratio under all running conditions. The feedback control operates when the engine is operating at a mid-range rotational velocity and throttle position and when the air/fuel ratio is between about 15 and 16 to 1 to modify the fuel/air ratio from that achieved by a basic setting that is derived from parameters of engine performance so as to maintain the desired ratio. The basic setting is updated based upon previous feedback control corrections in order to minimize the amount of corrections required and reduce hunting.

Claims

1. An internal combustion engine comprising a combustion chamber, an air-fuel charging system for delivering an air and fuel charge to said combustion chamber for combustion therein, a combustion condition sensor for determining the air/fuel ratio in said combustion chamber, control means for adjusting the air/fuel ratio delivered to said combustion chamber, said control means including a feedback mode for adjusting the air/fuel ratio delivered to said combustion chamber in response to the output of said combustion condition sensor, said feedback mode operational when said engine is operating in a first operational range, said control means further including a learning mode and a memory for storing corrective data from said sensor during operation of said learning mode, said learning mode operational in a second engine operational range narrower than but within said first operational range, said control means utilizing the contents of said memory for subsequent control of said engine air/fuel ratio.

2. An internal combustion engine as set forth in claim 1 wherein the control means sets a basic air/fuel ratio and the combustion condition sensor is employed by said control means in said feedback mode to adjust the ratio from the basic air/fuel ratio.

3. An internal combustion engine as set forth in claim 2 wherein the basic air/fuel ratio is initially set based on engine running conditions.

4. An internal combustion engine as set forth in claim 3 wherein the contents of the memory are used to update the basic air/fuel ratio from the corrective data.

5. An internal combustion engine as set forth in claim 4 wherein the engine conditions at which the corrective data is taken are also memorized.

6. An internal combustion engine as set forth in claim 1 wherein the corrective data is averaged from the data when the air/fuel ratio shifts between rich and lean sides of the desired ratio.

7. An internal combustion engine as set forth in claim 6 wherein the control means sets a basic air/fuel ratio and the combustion condition sensor is employed by said control means in said feedback mode to adjust the ratio from the basic air/fuel ratio.

8. An internal combustion engine as set forth in claim 7 wherein the basic air fuel ratio is initially set based on engine running conditions.

9. An internal combustion engine as set forth in claim 8 wherein the contents of the memory are used to update the basic air/fuel ratio from the corrective data.

10. An internal combustion engine as set forth in claim 9 wherein the engine conditions at which the corrective data is taken are also memorized.

11. An internal combustion engine as set forth in claim 10 wherein said second operational range is when said first operational range exists and said air/fuel ratio is lean.

12. A method of operating an internal combustion engine as set forth in claim 11 further including the steps of averaging the corrective data from the data when the air/fuel ratio shifts between rich and lean sides of the desired ratio.

13. A method of operating an internal combustion engine as set forth in claim 11 wherein said step of determining if said engine is operating in a second operating condition further comprises the step of determining if said air/fuel ratio is lean.

14. A method of operating an internal combustion engine as set forth in claim 11 wherein said step of determining whether said second engine operating condition exists includes the step of determining if said air/fuel ratio is between 15 and 16 to 1.

15. A method of operating an internal combustion engine as set forth in claim 11 wherein said step of determining whether said first engine operating condition exists includes the step of determining if said sensor has reached an operating temperature.

16. A method of operating an internal combustion engine as set forth in claim 11 further including the step of utilizing the contents of said memory for subsequent control of said engine air/fuel ratio.

17. A method of operating an internal combustion engine as set forth in claim 16 further including the step of setting a basic air/fuel ratio from a map of an air/fuel control and wherein said step of utilizing the contents of said memory comprises utilizing said contents when data from said map is inaccessible.

18. A method of operating an internal combustion engine as set forth in claim 11, wherein said step of determining whether said engine is operating in a second engine operating range comprises determining if said engine is operating at a mid-range rotational velocity and throttle angle.

19. A method of operating an internal combustion engine comprising a combustion chamber, an air-fuel charging system for delivering an air and fuel charge to said combustion chamber for combustion therein, a combustion condition sensor for determining the air/fuel ratio in said combustion chamber, said method comprising the steps of determining whether said engine is operating in a first engine operating range, adjusting the air/fuel ratio delivered to said combustion chamber in response to the output of said combustion condition sensor with a feedback control means, determining if said engine is operating in a second operating range within said first operating range, and if so employing a learning mode including the step of storing corrective data from said feedback control means in a memory.

20. A method of operating an internal combustion engine as set forth in claim 19 further comprising the steps of setting a basic air/fuel ratio with said feedback control means and adjusting the ratio from the basic air/fuel ratio with said output from said sensor.

21. A method of operating an internal combustion engine as set forth in claim 20 further including the step of setting the basic air fuel ratio initially based on engine running conditions.

22. A method of operating an internal combustion engine as set forth in claim 21 further including the step of using the contents of the memory to update the basic air/fuel ratio from the corrective data.

23. A method of operating an internal combustion engine as set forth in claim 22 further including the step of storing data regarding the engine conditions at which the corrective data is taken.