Apparatus and method of detecting combustion state of internal combustion engine and recording medium storing program for execution of the detecting method

• US 5,991,684 A
• Filed: 11/07/1997
• Issued: 11/23/1999
• Est. Priority Date: 09/04/1995
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi Car Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Fukuchi, Eisaku, Numata, Akihito
• Primary Examiner(s): Dombroske, George
• Application Number:
  US08/966,358
• Time in Patent Office: 746 Days
• Field of Search: 701/101, 701/110, 701/111, 73/116, 73/117.2, 73/117.3, 73/118.1, 123/419, 123/436
• US Class Current: 701/110
• CPC Class Codes: F02D 2200/1015 Engines misfires
• CPC Class Codes: F02D 41/1498 measuring engine roughness
• CPC Class Codes: G01M 15/11 by detecting misfire

Abstract

In an apparatus of detecting a combustion state of an internal combustion engine, a combustion parameter value of the engine is calculated on the basis of measurement data concerning an engine speed, the value of the data concerning the engine speed is corrected with a correction value, the correction value is calculated to make the calculated combustion parameter fall within a predetermined range, and the correction value is set to a predetermined value when a predetermined condition is satisfied.

Claims

1. An apparatus of detecting a combustion state of an internal combustion engine, comprising:

means for calculating a combustion parameter value of said engine on the basis of measurement data concerning an engine speed;

means for correcting a value of the data concerning the engine speed with a correction value;

means for calculating said correction value for making the calculated combustion parameter value fall within a predetermined range;

means for setting said correction value to a predetermined value when a predetermined condition is satisfied;

means for calculating an average value of correction values obtained in the past; and

condition decision means,

whereby when at least one of the running state of said engine and a running condition does not meet a predetermined condition, said correction value is set to said average value.

2. A detecting apparatus according to claim 1, wherein when said condition decision means determines that said calculated combustion parameter exceeds a predetermined reference value, said correction value is set to said average value.

3. A detecting apparatus according to claim 1 further comprising means for measuring a window pass time required for a rotary shaft of said engine to rotate through a predetermined rotation angle, wherein said means for calculating the combustion parameter value calculates the combustion parameter value pursuant to the following equation:

space="preserve" listing-type="equation">D1A=(TDATA.sub.(n) -TDATA.sub.(n-1))/(TDATA.sub.(n-1)).sup.3

where D1A represents combustion parameter,

TDATA.sub.(n) represents window pass time at n-th sampling,

TDATA.sub.(n-1) represents window pass time at (n-1)-th sampling, and

n represents arbitrary positive integer.

4. A detecting apparatus according to claim 1, wherein when said predetermined condition is a predetermined engine state, said correction value is set to said predetermined value to make the data concerning the engine speed of said engine substantially equal to the data which is not corrected.

5. A detecting apparatus according to claim 1, wherein said predetermined condition corresponds to an engine speed which is less than a predetermined value and no load state.

7. A detecting apparatus according to claim 1 further comprising means for deciding a misfire by comparing a corrected combustion parameter value with a reference value, wherein said misfire decider means determines the occurrence of a misfire state when said combustion parameter value exceeds said reference value.

8. A detecting apparatus according to claim 7, wherein said correction value and said combustion parameter are determined in respect of each cylinder of said engine, and said misfire decider means decides a misfire in respect of each cylinder of said engine.

9. A detecting apparatus according to claim 7 further comprising a memory for storing a data map indicating said misfire decision reference value in relation to parameters which are the engine speeds and the loads.

10. A detecting apparatus according to claim 8, wherein when the value of combustion parameter obtained at the time that no misfire occurs in a predetermined reference cylinder and a cylinder which is in phase with said reference cylinder is below a predetermined value and the value of combustion parameter obtained at the time that no misfire occurs in other cylinders is above the predetermined value, said means for calculating correction value decreases the correction value for the other cylinders but increases the correction value therefor in the other case.

11. A detecting apparatus according to claim 8, wherein when the value of combustion parameter obtained at the time that no misfire occurs in a predetermined reference cylinder and a cylinder which is in phase with said reference cylinder is below a predetermined value and the value of combustion parameter obtained at the time that no misfire occurs in other cylinders is above the predetermined value, said means for calculating correction value increases the correction value for said cylinder in phase with said reference cylinder but decreases the correction value for said in-phase cylinder in the other case.

12. A detecting apparatus according to claim 8, wherein when the value of combustion parameter obtained at the time that no misfire occurs for all of the cylinders is within a predetermined range, said means for calculating correction value does not change the correction value for a predetermined reference cylinder and a cylinder which is in phase with said reference cylinder, and wherein when the value of combustion parameter obtained at the time that no misfire occurs in said reference cylinder and said cylinder which is in phase with said reference cylinder is below a predetermined value and the value of combustion parameter obtained at the time that no misfire occurs in other cylinders is above the predetermined value, said means for calculating correction value decreases the correction value for the other cylinders but increases the correction value therefor in the other case.

13. A detecting apparatus according to claim 8, wherein when the value of combustion parameter obtained at the time that no misfire occurs in all of the cylinders is within a predetermined range, said means for calculating correction value does not change the correction value for a predetermined reference cylinder and a cylinder which is in phase with said reference cylinder, and wherein when the value of combustion parameter obtained at the time that no misfire occurs in said reference cylinder and said cylinder in phase with said reference cylinder is below a predetermined value and the value of combustion parameter obtained at the time that no misfire occurs in other cylinders is above the predetermined value, said means for calculating correction value increases the correction value for said cylinder in phase with said reference cylinder but decreases the correction value for said in-phase cylinder in the other case.

14. A detecting apparatus according to claim 1 further comprising condition decider means, wherein said condition decider means decides whether or not one or more decision parameters including the engine speed, the load, the cooling water temperature, the change rate of throttle opening in a time, the measurement value of atmospheric pressure and the presence or absence of misfire satisfy a predetermined condition, and when said condition is satisfied, said correcting means corrects data concerning the engine speed by using a correction value calculated by said means for calculating said correction value.

15. A detecting apparatus according to claim 14 further comprising means for calculating an average value of correction values obtained in the past and updating said calculated average value each time said average value is calculated, wherein when the running state of said engine and/or the circumstance condition during running does not satisfy a predetermined condition, said correction value is set to an updated average value.

16. A detecting apparatus according to claim 14, wherein when said predetermined condition is satisfied and the engine speed and the speed of a vehicle carrying said engine meet a predetermined condition, said correction value is set to said predetermined value to make the data concerning the engine speed substantially equal to the data which is not corrected.

17. A detecting apparatus according to claim 14, wherein said correction value has an upper limit and a lower limit.

6. A detecting apparatus according to claim 6 further comprising:

means for calculating an average value of correction values obtained in the past; and

condition decision means,

whereby when the running state of said engine and/or the circumstance condition during running does not meet a predetermined condition, said correction value is set to said average value.

18. A method of detecting a combustion state of an internal combustion engine, comprising the steps of:

measuring measurement data concerning an engine speed of said engine;

calculating a combustion parameter value of said engine on the basis of the measurement data concerning said engine speed;

correcting the value of the data concerning the engine speed with a correction value;

calculating said correction value for making the calculated combustion parameter value fall within a predetermined range;

setting said correction value to a predetermined value when a predetermined condition is satisfied;

calculating an average value of correction values obtained in the past; and

setting said correction value to said average value when at least one of the running state of the engine and a running condition does not meet a predetermined condition.

19. A computer program product comprising a computer usable medium having computer readable program code means embodied in said medium for detecting a combustion state of an internal combustion engine, said computer readable program code means comprising:

means for fetching measurement data concerning an engine speed;

means for calculating a combustion parameter value of said engine on the basis of the measurement data concerning the engine speed;

means for correcting the value of the data concerning the engine speed with a correction value;

means for calculating said correction value for making the calculated combustion parameter value fall within a predetermined range;

means for setting said correction value to a predetermined value when a predetermined condition is satisfied;

means for calculating an average value of correction values obtained in the past; and

condition decision means,

whereby when at least one of the running state of said engine and a running condition does not meet a predetermined condition, said correction value is set to said average value.