WO2008142199A2 - An indicator arrangement - Google Patents

An indicator arrangement Download PDF

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Publication number
WO2008142199A2
WO2008142199A2 PCT/FI2008/050264 FI2008050264W WO2008142199A2 WO 2008142199 A2 WO2008142199 A2 WO 2008142199A2 FI 2008050264 W FI2008050264 W FI 2008050264W WO 2008142199 A2 WO2008142199 A2 WO 2008142199A2
Authority
WO
WIPO (PCT)
Prior art keywords
signal
fault
amplitude fluctuation
fault detection
knock sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/FI2008/050264
Other languages
French (fr)
Other versions
WO2008142199A3 (en
Inventor
Johan Pensar
Ari Saikkonen
Tom Kaas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wartsila Finland Oy
Original Assignee
Wartsila Finland Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wartsila Finland Oy filed Critical Wartsila Finland Oy
Publication of WO2008142199A2 publication Critical patent/WO2008142199A2/en
Publication of WO2008142199A3 publication Critical patent/WO2008142199A3/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P5/00—Advancing or retarding ignition; Control therefor
    • F02P5/04—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions
    • F02P5/145—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions using electrical means
    • F02P5/15—Digital data processing
    • F02P5/152—Digital data processing dependent on pinking
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
    • G01L23/22—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines
    • G01L23/221—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines for detecting or indicating knocks in internal combustion engines
    • G01L23/225—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines for detecting or indicating knocks in internal combustion engines circuit arrangements therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
    • G01L23/22—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines
    • G01L23/221—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines for detecting or indicating knocks in internal combustion engines
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
    • G01L27/007—Malfunction diagnosis, i.e. diagnosing a sensor defect
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M15/00—Testing of engines
    • G01M15/04—Testing internal-combustion engines
    • G01M15/11—Testing internal-combustion engines by detecting misfire
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
    • G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
    • G01R31/2829—Testing of circuits in sensor or actuator systems

Definitions

  • the present invention relates to indicators used in piston-operated internal combustion engines, such as diesel engines or gas engines.
  • the invention especially relates to knock indicators.
  • the temperature of a cylinder can be measured; the fuel flow to be supplied can be monitored; the engine running speed can be measured and so on.
  • the knocking occurring in a cylinder can also be monitored.
  • a cylinder knocks when the air-fuel mixture introduced therein is ignited in an undesired manner. Typically knocking occurs when the air-fuel mixture or the fuel used separately for ignition is ignited too early. Knocking stresses the engine and can damage the engine. Knock control is used to avoid engine knock by controlling the ignition timing and/or fuel injection for each cylinder. Knock control can reduce the engine load. The last alternative is to even turn the engine off if deemed necessary. It is also possible to recycle exhaust gas back to the engine, whereby the so-called knock margin is increased. Knock margin means the difference between the units of the operating state of the cylinder and the state causing the knock. The larger the margin is, the smaller the probability of the cylinder turning into the knock-causing state.
  • the acceleration sensor is typically a piezoresistive crystal.
  • the signal emitted by the sensor is measured at the correct moment (i.e. when the crank rotation angle is suitable) at the time knock is most likely to occur. Noise and excess frequencies are filtered from the signal.
  • the processed signal is compared with the reference value, whereby it is possible to deduce whether the cylinder is in a knock state. If the knock-indicating sensor and the cables connected thereto are not damaged, knocking can be reliably detected. However, if the sensor or the cables connected thereto are damaged, the signal provided by the sensor can be incorrect.
  • the engine can be incorrectly controlled on the basis of the incorrect signal whereby there is a great risk of damaging the engine.
  • the engine causes vibration that can in the long run damage the sensor, the cables connected thereto or the connections of the cable.
  • An aim of the present invention is to reduce the above-mentioned disadvantages.
  • the aim is achieved as described in the main claim.
  • the dependent claims describe the various embodiments of the invention.
  • the method according to the invention comprises steps for detecting a fault in a system used in connection with a piston engine.
  • a monitoring step of the method is carried out for monitoring the amplitude fluctuation of the signal of the knock sensor arrangement.
  • the second step is for comparing the amplitude of the signal and a certain limit value and the third step is for detecting any faults in the knock sensor arrangements on the basis of the said comparison.
  • the apparatus according to the invention is arranged to carry out the steps of the inventive method.
  • Figure 2 illustrates the detection of the fault from the monitored signal
  • Figure 3 is a block diagram of the method according to the invention.
  • Figure 1 illustrates an example of the apparatus according to the invention and the way it is connected to a certain system of the internal combustion engine.
  • a knock detection sensor 1 (usually an acceleration sensor) is connected via filtering means 2 to a measurement apparatus 3.
  • the filtered signal of the sensor 1 can be used for detecting whether the cylinder knocks.
  • the filtering apparatus is simply shown as a capacitor, but it will be obvious to one skilled in the art to carry the filtering means out as appropriate for the purpose.
  • the sensor 1 is connected via the filter to the measurement apparatus with a cable 5, the length of which can be many metres. Both the sensor 1 and the cable 5 can be damaged by the vibration of the engine and other external factors.
  • the measurement apparatus is provided with a fault detection apparatus 4 according to the invention.
  • the fault detection apparatus can also be placed outside the measurement apparatus for monitoring the signal provided by the sensor 1.
  • the fault detection apparatus is arranged to monitor the amplitude fluctuation of the signal of the knock sensor arrangement, to compare the amplitude fluctuation with a certain limit value and to detect any fault in the knock sensor arrangement on the basis of the comparison.
  • the fault apparatus 4 can be carried out with software as a computer program, as an ASIC circuit (Application Specific Integrated Circuit) or as a more traditional circuit.
  • Figure 2 illustrates detection of a fault.
  • the signal of the knock sensor fluctuates in a certain way. This fluctuation can be followed by, for example, calculating the variance from the sensor signal. The fluctuation of the signal can also be observed by other means than variance.
  • signal 6 thus describes the amplitude fluctuation of the knock sensor signal and the amplitude fluctuation of the signal can be, for example, the variance of the signal.
  • the monitoring of the fluctuation of the knock sensor signal is preferably made from a filtered knock sensor signal so that noise and other disturbances do not have an effect on the monitoring of the amplitude fluctuation.
  • the fault detection apparatus 4 notices a change in the knock signal fluctuation 6, with the level of fluctuation dropping below a certain limit value 7, the fault detection apparatus performs fault detection.
  • the apparatus thus compares the fluctuation of the signal amplitude to the limit value 7 and when the fluctuation of the signal amplitude is less than the limit value, the apparatus performs a fault detection operation.
  • An example of fault detection operation is changing the value of a certain signal 8 from FALSE to TRUE, in which FALSE describes the normal signal amplitude fluctuation and TRUE describes the signal fluctuation of a sensor arrangement with a fault condition.
  • Figure 2 illustrates such a method. It is also possible to arrange a certain delay 9 between the fault generation moment and the fault detection moment for avoiding incorrect fault detections.
  • the fault detection can also be carried out with a signal of a different
  • FIG. 3 illustrates the inventive method as a block diagram example.
  • the monitoring step 31 of the method is arranged for monitoring the amplitude fluctuation of the signal of the knock sensor arrangement.
  • the second step 32 is made for comparing the amplitude fluctuation of the signal and a certain limit value and the third phase 33 is arranged for detecting any faults in the knock sensor arrangement on the basis of the said comparison.
  • the fault detection is positive when the amplitude fluctuation of the monitored signal is less than the said limit value. See figure 2.
  • the method can also be arranged to delay the monitoring moment as described above.
  • the fluctuation of the signal of the knock sensor can be a variance.
  • the variance can be calculated as follows. The data points of the signal to be monitored are
  • X [X 1 X 2 ... x n _ x X n ] .
  • the variance is calculated as follows
  • the said data points can be calculated from the last monitoring window (a monitoring window is a time frame containing a certain number of data point observations), on the basis of which the variance is calculated.
  • a monitoring window is a time frame containing a certain number of data point observations
  • the method described above is only one of many ways for calculating the variance. There are other ways as well of determining the fluctuation of the signal amplitude.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biomedical Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Signal Processing (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)
  • Eye Examination Apparatus (AREA)
  • Spectrometry And Color Measurement (AREA)

Abstract

The method according to the invention comprises steps for recognizing a fault in a system used in connection with a piston engine. Amonitoring step (31) of the method is carried out for monitoring the amplitude fluctuation of the signal of the knock sensor arrangement. The second step (32) is made for comparing the amplitude of the signal and a certain limit value and the third step (33) is for detecting any faults in the knock sensor arrangement on the basis of the said comparison. The apparatus according to the invention is arranged to carry out the steps of the inventive method.

Description

AN INDICATOR ARRANGEMENT
Field of invention
The present invention relates to indicators used in piston-operated internal combustion engines, such as diesel engines or gas engines. The invention especially relates to knock indicators.
Background art
Many kinds of different indicators are used in piston-operated internal combustion engines for observing different units and states in engines. The temperature of a cylinder can be measured; the fuel flow to be supplied can be monitored; the engine running speed can be measured and so on. The knocking occurring in a cylinder can also be monitored.
A cylinder knocks when the air-fuel mixture introduced therein is ignited in an undesired manner. Typically knocking occurs when the air-fuel mixture or the fuel used separately for ignition is ignited too early. Knocking stresses the engine and can damage the engine. Knock control is used to avoid engine knock by controlling the ignition timing and/or fuel injection for each cylinder. Knock control can reduce the engine load. The last alternative is to even turn the engine off if deemed necessary. It is also possible to recycle exhaust gas back to the engine, whereby the so-called knock margin is increased. Knock margin means the difference between the units of the operating state of the cylinder and the state causing the knock. The larger the margin is, the smaller the probability of the cylinder turning into the knock-causing state. It is nowadays common to measure the knock by means of an acceleration sensor from the cylinder head, cylinder sleeve or the engine block. The acceleration sensor is typically a piezoresistive crystal. The signal emitted by the sensor is measured at the correct moment (i.e. when the crank rotation angle is suitable) at the time knock is most likely to occur. Noise and excess frequencies are filtered from the signal. The processed signal is compared with the reference value, whereby it is possible to deduce whether the cylinder is in a knock state. If the knock-indicating sensor and the cables connected thereto are not damaged, knocking can be reliably detected. However, if the sensor or the cables connected thereto are damaged, the signal provided by the sensor can be incorrect. The engine can be incorrectly controlled on the basis of the incorrect signal whereby there is a great risk of damaging the engine. The engine causes vibration that can in the long run damage the sensor, the cables connected thereto or the connections of the cable.
Brief description of the invention
An aim of the present invention is to reduce the above-mentioned disadvantages. The aim is achieved as described in the main claim. The dependent claims describe the various embodiments of the invention.
The method according to the invention comprises steps for detecting a fault in a system used in connection with a piston engine. A monitoring step of the method is carried out for monitoring the amplitude fluctuation of the signal of the knock sensor arrangement. The second step is for comparing the amplitude of the signal and a certain limit value and the third step is for detecting any faults in the knock sensor arrangements on the basis of the said comparison. The apparatus according to the invention is arranged to carry out the steps of the inventive method.
List of figures
In the following the invention is described in more detail by reference to the figures in the drawing, in which Figure 1 illustrates an example of the fault detecting apparatus according to the invention,
Figure 2 illustrates the detection of the fault from the monitored signal, and Figure 3 is a block diagram of the method according to the invention.
Description of the invention
Figure 1 illustrates an example of the apparatus according to the invention and the way it is connected to a certain system of the internal combustion engine. In the example of figure 1 a knock detection sensor 1 (usually an acceleration sensor) is connected via filtering means 2 to a measurement apparatus 3. In the measurement apparatus the filtered signal of the sensor 1 can be used for detecting whether the cylinder knocks. The filtering apparatus is simply shown as a capacitor, but it will be obvious to one skilled in the art to carry the filtering means out as appropriate for the purpose. In practice the sensor 1 is connected via the filter to the measurement apparatus with a cable 5, the length of which can be many metres. Both the sensor 1 and the cable 5 can be damaged by the vibration of the engine and other external factors. In the example of figure 1 for detecting a fault in the knock sensor arrangement the measurement apparatus is provided with a fault detection apparatus 4 according to the invention. The fault detection apparatus can also be placed outside the measurement apparatus for monitoring the signal provided by the sensor 1. The fault detection apparatus is arranged to monitor the amplitude fluctuation of the signal of the knock sensor arrangement, to compare the amplitude fluctuation with a certain limit value and to detect any fault in the knock sensor arrangement on the basis of the comparison. The fault apparatus 4 can be carried out with software as a computer program, as an ASIC circuit (Application Specific Integrated Circuit) or as a more traditional circuit.
Figure 2 illustrates detection of a fault. Usually, the signal of the knock sensor fluctuates in a certain way. This fluctuation can be followed by, for example, calculating the variance from the sensor signal. The fluctuation of the signal can also be observed by other means than variance. In figure 2 signal 6 thus describes the amplitude fluctuation of the knock sensor signal and the amplitude fluctuation of the signal can be, for example, the variance of the signal. When a fault occurs in the knock sensor arrangement (such as the sensor 1 , cable 5 or the connections of the cable being damaged), the amplitude of the signal changes, a normally high fluctuation of signal amplitude is considerably reduced as shown in figure 2. The monitoring of the fluctuation of the knock sensor signal is preferably made from a filtered knock sensor signal so that noise and other disturbances do not have an effect on the monitoring of the amplitude fluctuation. When the fault detection apparatus 4 notices a change in the knock signal fluctuation 6, with the level of fluctuation dropping below a certain limit value 7, the fault detection apparatus performs fault detection. The apparatus thus compares the fluctuation of the signal amplitude to the limit value 7 and when the fluctuation of the signal amplitude is less than the limit value, the apparatus performs a fault detection operation. An example of fault detection operation is changing the value of a certain signal 8 from FALSE to TRUE, in which FALSE describes the normal signal amplitude fluctuation and TRUE describes the signal fluctuation of a sensor arrangement with a fault condition. Figure 2 illustrates such a method. It is also possible to arrange a certain delay 9 between the fault generation moment and the fault detection moment for avoiding incorrect fault detections. The fault detection can also be carried out with a signal of a different type.
Figure 3 illustrates the inventive method as a block diagram example. The monitoring step 31 of the method is arranged for monitoring the amplitude fluctuation of the signal of the knock sensor arrangement. The second step 32 is made for comparing the amplitude fluctuation of the signal and a certain limit value and the third phase 33 is arranged for detecting any faults in the knock sensor arrangement on the basis of the said comparison. In the third phase the fault detection is positive when the amplitude fluctuation of the monitored signal is less than the said limit value. See figure 2. The method can also be arranged to delay the monitoring moment as described above.
As mentioned above, the fluctuation of the signal of the knock sensor can be a variance. The variance can be calculated as follows. The data points of the signal to be monitored are
X = [X1 X2 ... xn_x Xn ] .
The average of the data points is n x, mean(X) =
The variance is calculated as follows
1 " σ 2 = Y (x -mean(X))2 .
The said data points can be calculated from the last monitoring window (a monitoring window is a time frame containing a certain number of data point observations), on the basis of which the variance is calculated. The method described above is only one of many ways for calculating the variance. There are other ways as well of determining the fluctuation of the signal amplitude.
As can be seen, the embodiment according to the invention can be carried out by means of a number of solutions. Thus, it will be apparent that the invention is not limited to the examples mentioned in this text. Thus, any inventive embodiment can be carried out within the scope of the invention.

Claims

Claims
1. A method for detecting a fault in a system used in connection with a piston- operated internal combustion engine, characterized in that the method comprises the following steps for detecting a fault in a knock sensor arrangement: a step for monitoring the amplitude fluctuation of the signal of a knock sensor arrangement, a second step for comparing the amplitude fluctuation of the monitored signal to a certain limit value and a third step for detecting a fault in the knock sensor arrangement on the basis of said comparison.
2. The method according to claim 1 , characterized in that in the third phase the fault detection is positive when the amplitude fluctuation of the monitored signal is below the said limit value.
3. The method according to claim 2, characterized in that amplitude fluctuation of the signal is variance of the signal.
4. The method according to claim 2 or 3, characterized in that the method comprises a delay operation for delaying the detection of a possible fault.
5. A fault detection apparatus for detecting a fault in a system used in connection with a piston-operated internal combustion engine, characterized in that the fault detection apparatus (4) is arranged to monitor the amplitude fluctuation of the signal of a knock sensor arrangement, to compare the amplitude fluctuation of the monitored signal to a certain limit value and to detect a possible fault in the knock sensor system on the basis of the said comparison.
6. The apparatus according to claim 5, characterized in that in the fault detection of the fault detection apparatus is positive when the amplitude fluctuation of the monitored signal is below the said limit value.
7. The apparatus according to claim 5 or 6, characterized in that the amplitude fluctuation of the signal is the variance of the signal.
8. An apparatus according to claim 5-7, characterized in that the fault detection apparatus is carried out by means of a program.
9. An apparatus according to claim 5-7, characterized in that the fault detection apparatus is carried out by means of an ASIC circuit.
PCT/FI2008/050264 2007-05-21 2008-05-13 An indicator arrangement Ceased WO2008142199A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20075362 2007-05-21
FI20075362A FI20075362L (en) 2007-05-21 2007-05-21 Indicator arrangement

Publications (2)

Publication Number Publication Date
WO2008142199A2 true WO2008142199A2 (en) 2008-11-27
WO2008142199A3 WO2008142199A3 (en) 2009-01-29

Family

ID=38069529

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI2008/050264 Ceased WO2008142199A2 (en) 2007-05-21 2008-05-13 An indicator arrangement

Country Status (2)

Country Link
FI (2) FI20075362L (en)
WO (1) WO2008142199A2 (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2942250A1 (en) * 1979-10-19 1981-05-07 Robert Bosch Gmbh, 7000 Stuttgart DEVICE FOR DETECTING THE VIBRATIONS WHEN TAPPING AN INTERNAL COMBUSTION ENGINE
DE3211644A1 (en) * 1982-03-30 1983-10-13 Daimler-Benz Ag, 7000 Stuttgart DEVICE FOR DETECTING THE FAILURE OF A SENSOR
JP2509376B2 (en) * 1990-08-21 1996-06-19 三菱電機株式会社 Knock control method for internal combustion engine

Also Published As

Publication number Publication date
FI20075362A7 (en) 2008-11-22
FI20075362A0 (en) 2007-05-21
FIU20090453U0 (en) 2009-12-15
FI20075362L (en) 2008-11-22
WO2008142199A3 (en) 2009-01-29

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