Method and system for determining combustion misfire of an internal combustion engine

• US 7,155,965 B2
• Filed: 06/21/2005
• Issued: 01/02/2007
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Inventors: Kim, Chang Hyun
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US11/158,404
• Publication Number:
  US 20060000264A1
• Time in Patent Office: 560 Days
• Field of Search: 731/16, 731/172, 731/173, 731/181
• US Class Current: 73/114.03
• CPC Class Codes: G01M 15/11 by detecting misfire

Abstract

A method and system for determining a combustion misfire in an internal combustion engine by calculating a segment time; normalizing the calculated segment time; modifying the normalized segment time using low pass filters for each cylinder; calculating a misfire determination reference value by adding a minimum value among the modified normalized segment times to a predetermined offset value; and determining whether a combustion misfire occurs based on a comparison of the modified normalized segment time and the misfire determination reference value.

Claims

1. A method for determining a combustion misfire of an internal combustion engine having at least one cylinder, comprising the steps of:

calculating a segment time;

normalizing the calculated segment time;

modifying the normalized segment time using low pass filters for each at least one cylinder;

calculating a misfire determination reference value by adding a minimum value among the modified normalized segment times to a predetermined offset value; and

determining whether a combustion misfire occurs based upon a comparison of the modified normalized segment time and the misfire determination reference value.

2. The method of claim 1, wherein, in the normalizing step, the calculated segment time is normalized based upon a difference between segment times of a reference cylinder and an n-th cylinder, and a difference between segment times of the reference cylinder in a previous stroke and a current stroke.

3. The method of claim 2, wherein the normalized segment time TS_C(n) is calculated as a value according to the following equation:

$\mathrm{TS\_C}<br><br>\left(n\right)=\mathrm{TS}<br><br>\left(n\right)*\left[1+\mathrm{LPF}<br><br>\left(X<br><br>\left(n\right)<br><br>\left(i\right)\right)\right]$ $X<br><br>\left(n\right)=\left[\mathrm{TS}<br><br>\left(0\right)-\mathrm{TS}<br><br>\left(n\right)+\frac{n}{4}*\left({\mathrm{TS}<br><br>\left(0\right)}^{\mathrm{\prime <br><br>}}-\mathrm{TS}<br><br>\left(0\right)\right)\right]/\mathrm{TS}<br><br>\left(n\right)$

where TS is a segment time, i is a stroke number, n is a number of cylinders, TS(0) is a segment time of a reference cylinder in a current stroke, TS(0)′

is a segment time of a reference cylinder in a previous stroke, TS(n) is a segment time of an n-th cylinder of a current stroke, X(n)(i) is a normalized value of the segment time, and an LPF is a low pass filter function.

4. The method of claim 1, wherein, in the determining step, it is determined that a combustion misfire occurs if the modified normalized segment time is greater than the misfire determination reference value.

5. The method of claim 1, further comprising:

illuminating a warning lamp if if a combustion misfire is determined to have occurred.

6. A system for determining a combustion misfire of an internal combustion engine, comprising:

a crank angle sensor; and

a control unit for determining whether a combustion misfire occurs on the basis of signals of the crank angle sensor, wherein the control unit is programmed to perform instructions comprising;

calculating a segment time;

normalizing the calculated segment time;

modifying the normalized segment time using low pass filters for each at least one cylinder;

calculating a misfire determination reference value by adding a minimum value among the modified normalized segment times to a predetermined offset value; and

determining whether a combustion misfire occurs based upon a comparison of the modified normalized segment time and the misfire determination reference value.

7. The system of claim 6, wherein in the normalizing step, the calculated segment time is normalized based upon a difference between segment times of a reference cylinder and an n-th cylinder, and a difference between segment times of the reference cylinder in a previous stroke and a current stroke.

8. The system of claim 7, wherein the normalized segment time TS_C(n) is calculated as a value according to the following equation:

$\mathrm{TS\_C}<br><br>\left(n\right)=\mathrm{TS}<br><br>\left(n\right)*\left[1+\mathrm{LPF}<br><br>\left(X<br><br>\left(n\right)<br><br>\left(i\right)\right)\right]$ $X<br><br>\left(n\right)=\left[\mathrm{TS}<br><br>\left(0\right)-\mathrm{TS}<br><br>\left(n\right)+\frac{n}{4}*\left({\mathrm{TS}<br><br>\left(0\right)}^{\mathrm{\prime <br><br>}}-\mathrm{TS}<br><br>\left(0\right)\right)\right]/\mathrm{TS}<br><br>\left(n\right)$

where TS is a segment time, i is a stroke number, n is a number of cylinders, TS(0) is a segment time of a reference cylinder in a current stroke, TS(0)′

is a segment time of a reference cylinder in a previous stroke, TS(n) is a segment time of an n-th cylinder of a current stroke, X(n)(i) is a normalized value of the segment time, and an LPF is a low pass filter function.

9. The system of claim 6, wherein, in the determining step, it is determined that a combustion misfire occurs if the modified normalized segment time is greater than the misfire determination reference value.