Method and control device for diagnosing a charge cycle valve stroke adjusting system of an internal-combustion engine

• US 20060293832A1
• Filed: 06/22/2006
• Published: 12/28/2006
• Est. Priority Date: 06/23/2005
• Status: Active Grant

• Current Assignee: Dr Ing hc F Porsche AG (Volkswagen AG)
• Original Assignee: Dr Ing hc F Porsche AG (Volkswagen AG)
• Inventors: Schwarzenthal, Dietmar, Melzig, Thomas, Nagel, Nils
• Granted Patent: US 7,308,355 B2
• Time in Patent Office: Days
• US Class Current: 701/114
• CPC Class Codes: F01L 13/0036 the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
• CPC Class Codes: F01L 2800/11 Fault detection, diagnosis
• CPC Class Codes: F01L 2820/041 Camshafts position or phase sensors
• CPC Class Codes: F02D 13/0211 the change of valve timing is caused by the change in valve lift, i.e. both valve lift and timing are functionally related
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 41/0082 per groups or banks F02D41/0087 takes precedence
• CPC Class Codes: F02D 41/1443 with one sensor per cylinder or group of cylinders
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02D 41/221 relating to the failure of actuators or electrically driven elements
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

In a method for diagnosing a charge cycle valve stroke adjusting system of an internal-combustion engine having at least one exhaust gas sensor which supplies an output signal continuously varying with an exhaust gas constituent, the spread width of the output signal is determined, and compared with a reference value. Defects of the valve stroke adjusting system are detected on the basis of the comparison.

Claims

1. A method of diagnosing a charge cycle valve stroke adjusting system of an internal-combustion engine having at least one exhaust gas sensor which supplies an output signal that continuously varies with an exhaust gas constituent, said method comprising:

measuring a spread width of said output signal;

comparing the measured spread width with a reference value; and

detecting defects of the valve stroke adjusting system based on a result of the comparison.

2. The method according to claim 1, wherein the reference value is determined as a value which depends on operating parameters of the internal-combustion engine.

3. The method according to claim 1, wherein a first measurement of a spread width of an output signal of the exhaust gas sensor in the case of a first desired value of the valve stroke is defined as a reference value for a second measurement of the spread width of the output signal of the same exhaust gas sensor in the case of a second desired value of the valve stroke.

4. The method according to claim 1, wherein:

said internal-combustion engine has a plurality of groups of cylinders, and exhaust gas sensors for each cylinder group; and

a measurement of a spread width of an output signal of a first exhaust gas sensor of a first group of cylinders is defined as the reference value for a measurement of a spread width of an output signal of a second exhaust gas sensor of a second group of cylinders.

5. The method according to claim 1, wherein:

a difference is determined between the measurement of the spread width and the reference value;

said difference is compared with a threshold value; and

when said difference exceeds the threshold value, a defect is determined to exist.

6. The method according to claim 1, wherein

a range of possible values of an output signal of an exhaust gas sensor is divided into difference classes of a defined width;

a value is then determined for a number of class boundaries through which the output signal or a filtered output signal passes, between two successive local extremes; and

a sum of a predetermined number of determined values is formed and used as a measurement for the spread width.

7. The method according to claim 6, wherein

the filtered output signal is generated by high-pass filtering of the output signal.

8. The method according to claim 1, wherein:

an average value of the output signal is determined;

an integral of absolute amounts of deviations of the output signal from the average value is determined; and

the integral is used as a measurement of the spread width.

9. The method according to claim 1, wherein

the measurement for spread width is determined as a standard deviation of values of the output signal from an average value of the output signal.

10. A control device for an internal-combustion engine, which includes diagnostic means for diagnosing a charge cycle valve stroke adjusting system of an internal combustion engine that has at least one exhaust gas sensor which supplies an output signal which continuously varies with an exhaust gas constitute, wherein said diagnostic means is programmed to perform the following steps:

measuring a spread width of said output signal;

comparing the measured spread width with a reference value; and

detecting defects of the valve stroke adjusting system based on the comparison.