WO2008140403A1 - Method and computer program product for identifying a malfunctioning cylinder of a multi-cylinder combustion engine - Google Patents

Method and computer program product for identifying a malfunctioning cylinder of a multi-cylinder combustion engine Download PDF

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Publication number
WO2008140403A1
WO2008140403A1 PCT/SE2008/050519 SE2008050519W WO2008140403A1 WO 2008140403 A1 WO2008140403 A1 WO 2008140403A1 SE 2008050519 W SE2008050519 W SE 2008050519W WO 2008140403 A1 WO2008140403 A1 WO 2008140403A1
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WIPO (PCT)
Prior art keywords
data set
control unit
electronic control
engine
identifying
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Ceased
Application number
PCT/SE2008/050519
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French (fr)
Inventor
Björn Völcker
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Scania CV AB
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Scania CV AB
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Publication of WO2008140403A1 publication Critical patent/WO2008140403A1/en
Anticipated expiration legal-status Critical
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1497—With detection of the mechanical response of the engine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/008—Controlling each cylinder individually
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D41/221—Safety or indicating devices for abnormal conditions relating to the failure of actuators or electrically driven elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/009—Electrical control of supply of combustible mixture or its constituents using means for generating position or synchronisation signals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to a method for identifying a malfunctioning fuel injector of a cylinder of a multi-cylinder combustion engine.
  • the invention also relates to a computer program product comprising computer program code for implementing a method according to the invention.
  • the invention also relates to a computer.
  • the invention further relates to a platform having a computer.
  • a multi-cylinder combustion engine fails to deliver its rated power, this may be due to the malfunctioning of any of the cylinders of the engine.
  • the malfunctioning of a cylinder may be due to overfuelling caused by a faulty fuel injector or to excessive fuel pressure within a fuel supply system of the engine.
  • US 5095742 discloses a method for diagnosis of faulty ignition in individual cylinders by calculating power loss. According to the method of US 5095742 accelerations of the engine speed are measured. Subsequently an acceleration value of a measurement associated with a particular cylinder of the engine is compared with a median acceleration and the resulting difference is used for a normalized calculation of power loss.
  • An object of the invention is to provide a new and advantageous manner of identifying a malfunctioning fuel injector associated with an individual cylinder of a multicylinder combustion engine.
  • An object of the invention according to an aspect of the invention is to provide an improved method for diagnosing a multi-cylinder combustion engine.
  • An advantage of the present invention is that the derivative of the engine speed values does not need to be taken into consideration. This thus means that the torque of the crank shaft also does not need to be taken into consideration. An advantage is that the noise reduction is improved.
  • An advantage of the present invention is also that the number of erroneous detections is reduced.
  • the present invention further provides an improved ability to early detect a malfunctioning cylinder of a multi-cylinder engine, which is highly desirable, not least for the operators of the vehicle, such as a driver of a heavy vehicle.
  • a beneficial contribution of the invention is that a cost effective solution to the above stated problems is achieved.
  • Existing vehicles may easily be upgraded with relevant software so as to achieve the positive effects of the present invention.
  • Yet another beneficial contribution of the invention is that the method for identifying a malfunctioning cylinder of a multi-cylinder engine is robust.
  • Yet another beneficial contribution of the invention is that an erroneous detection of a malfunctioning fuel injector is reduced.
  • the step of processing said first data set may involve establishing the median value of a chosen number of said engine-speed values. It is an advantage in comparison to using the mean value, as false calculations are diminished in this case. Alternatively other calculation procedures may be used, such as calculating the cylinder wise mean engine speed by measuring the time from marker #1 to #21.
  • the weight vector may comprise elements, the sum of which is substantially zero (0).
  • the step of establishing said detection value may involve normalizing said detection value. It should be pointed out that the normalization preferably is performed in relation to idle engine speed. This makes the algorithm average speed independent.
  • Said second data set may constitute a set of elements, each element correlates to an individual cylinder.
  • the method may comprise the step of resetting said first data set after each engine cycle. Advantageously effects from earlier time instants will not affect the performance.
  • the method may comprise the step of periodically upgrading the second data set.
  • the step of identifying at least one malfunctioning fuel injector may be established in dependence of the upgrade of the second data set.
  • the step of identifying at least one malfunctioning fuel injector may be established in dependence of a predetermined validation time. Validation makes detection more robust to false alarms.
  • the method may be performed on-line, i.e. in real time during operation of the engine.
  • possible malfunction may be detected at an early stage. This facilitates for the operator to shut off the injector or attend to the problem by replacing the malfunctioning fuel injector.
  • Figure Ia schematically illustrates a fuel injection system for a combustion engine according to an aspect of the present invention
  • Figure Ib schematically illustrates a combustion engine and a control unit according to an aspect of the present invention
  • Figure 2 schematically illustrates a side view of the fuel injection system for a combustion engine shown in Figure 1 according to an aspect of the present invention
  • Figure 3a schematically illustrates a graph according to an aspect of the present invention
  • Figure 3b schematically illustrates a graph according to an aspect of the present invention
  • Figure 4 schematically illustrates a flow chart depicting a method for identifying a malfunctioning cylinder/fuel injector according to an aspect of the present invention.
  • FIG. 5 schematically illustrates an electronic control unit according to an aspect of the invention.
  • the platform 10 is preferably a ground vehicle, such as a truck or lorry. It should be noted that the platform 10 alternatively can be a water craft or underwater craft, e.g. a ship or submarine. Alternatively the platform 10 can be a power plant.
  • the term "link" refers to a communication link which may be a physical connector, such as an optoelectronic communication wire, or a non-physical connector such as a wireless connection, for example a radio or microwave link.
  • malfunctioning primarily refers to a too high fuel injection, i.e. the amount of fuel supplied to the cylinder is considerably higher than a desired amount. This kind of malfunction may lead to cylinder/engine breakdown.
  • Fig. Ia shows a fuel injection system for a combustion engine 60 (shown fig. Ib) in the form of a schematically represented diesel engine having six cylinders.
  • the fuel injection system and the diesel engine are with advantage fitted to heavy vehicle, such as truck, lorry or bus, for propelling the vehicle.
  • the fuel injection system is a so-called Common Rail system and comprises a fuel line for supply of fuel from a fuel tank 115 to the cylinders of the diesel engine.
  • a fuel pump 116 is arranged in the fuel line to convey fuel from the fuel tank via a filter 117 to a high-pressure pump 118.
  • the high pressure pump 118 is adapted to pressurize the fuel so that it enters at high pressure an accumulator tank 120 which takes the form of a so-called Common Rail.
  • the high fuel pressure in the accumulator tank 120 constitutes a power source making it possible for fuel to be injected at high pressure into the respective cylinders of the diesel engine.
  • the fuel in the accumulator tank 120 is intended to be distributed to all the cylinders of the combustion engine 60.
  • injection means 150a- 15Of is arranged in each of the connections between the accumulator tank 120 and the respective cylinders of the diesel engine.
  • an injection means When an injection means is in an open state, it injects fuel at high pressure into the cylinder concerned.
  • fuel from the accumulator tank 120 is injected into the combustion spaces of the respective cylinder by means of the injection means which is in the form of electronic injectors which injectors can open and close very quickly.
  • a control unit in the form of an electronic control unit 110 (ECU) is adapted to control the operation of the fuel pump 116, the high pressure pump 118 and the injection means 150a, 150b, 150c, 15Od, 15Oe, and 15Of.
  • a pressure sensor 122 is fitted in the accumulator tank 120 to detect the prevailing pressure therein and to send to the control unit 110 a signal S 122 conveying information about the pressure values detected.
  • the electronic control unit 110 controls the on- time or opening times of each individual electronic injector so that the calculated amount of fuel is supplied with good accuracy to the combustion spaces of the respective cylinders.
  • the term "on-time” refers to the opening time of an injector, i.e. the duration of the time period during which the injector is kept open in order to inject fuel into the associated cylinder in connection with a single stroke of the engine.
  • the quantity of fuel injected into a cylinder in connection with a stroke of the engine depends on the length of the on-time and the pressure of the fuel supplied to the injector.
  • the inventive method is initiated and controlled by means of the electronic control unit 110.
  • the inventive method is initiated and controlled by means of an external PC 112.
  • the external computer may be directly connected to the electronic control unit 110 via a link 114, but may also be indirectly connected to the electronic control unit 110 in any suitable manner, such as through an internal vehicle internal network.
  • the communication between the external computer and the engine control unit may be partly or entirely wireless.
  • the inventive method could also be initiated and controlled by the electronic control unit 110 itself or by another electronic control unit comprised in an internal vehicle network, such as an electronic gear box control unit.
  • Figure Ib shows the engine having six cylinders, each cylinder Ca, Cb, Cc, Cd, Ce, and Cf (not shown) being provided with a piston a, b, c, d, e, f, respectively.
  • the six pistons are attached to a crank shaft 50.
  • the crank shaft 50 is attached to a fly wheel 70 being arranged to rotate with the same speed as the crank shaft 50.
  • a sensor unit 80 is provided at a close proximity to the fly wheel 70.
  • the sensor unit 70 is arranged to measure engine speed by detecting time points corresponding to detections of markers equidistantly provided on the fly wheel 70 as depicted in greater detail below.
  • the sensor unit 80 is arranged for communication with the electronic control unit 110 via a link 81.
  • the sensor unit 80 is arranged to continuously transmit detected discrete time points.
  • the sensor unit 80 is arranged to on a regular basis send signals comprising a plurality of detected discrete time points.
  • the electronic control unit is arranged to receive sensed engine data in the form of e.g. a toothed fly wheel signal (TF-signal).
  • TF-signal is received on a data communications port from the engine-speed sensor unit 80 which senses rotation of the engine's toothed fly wheel 70.
  • the engine-speed sensor 80 may be e.g. an inductive type sensor or a Hall-effect sensor.
  • the electronic control unit 110 is arranged to perform a diagnosis test depending upon transmitted discrete time points from the sensor unit 80, so as to determine if one or more injectors associated with a unique cylinder of the engine is malfunctioning.
  • Figure 2 schematically illustrates a side view of the fly wheel of the engine. There is also shown the engine-speed sensor unit 80 arranged for communication with the electronic control unit 110 via the link 81.
  • the flywheel 60 is provided with 60 markers denoted #1, #2, ... , #60, such as teeth or holes. However, since there are four strokes in an engine cycle two turns of the flywheel results in each marker being calculated twice and therefore 120 markers are sensed by the engine-speed sensor unit 80 during an engine cycle.
  • the measurements are denoted #1, #2, ... , #120, wherein #1 and #61, #2 and #62 etc. corresponds to the same marker.
  • the engine-speed sensor unit 80 is arranged to detect a time point corresponding to a marker passing by a predetermined location, e.g. a location schematically indicated at marker #60 (and #120).
  • flywheel 70 corresponds to one engine cycle, which in turn corresponds to two turns of the crankshaft 50. It should be noted that the invention is suitable for various types of flywheels having an arbitrary number of markers.
  • the electronic control unit 110 is arranged to calculate an engine-speed value r ⁇ t) corresponding to each of the teeth i of the flywheel 70, wherein i is an integer in the interval 1-120,.
  • the calculation of the respective engine-speed value is performed depending upon received time point data, which data is communicated by the engine-speed sensor unit.
  • the engine-speed sensor unit 80 is arranged to calculate an engine- speed value T 1 (Y), wherein i is an integer in the interval 1-120, corresponding to each of the teeth of the flywheel 70 and to continuously transmit these values to the electronic control unit 110.
  • T is the transpose
  • the electronic control unit is further arranged to generate a more dense vector s(t).
  • the vector s(t) includes median values of predetermined groups of engine-speed elements of the engine-speed value vector r(t).
  • a median value of the first 20 engine-speed elements T 1 (I), r 2 (t), ,r 20 (t) is generated, denoted s ⁇ t).
  • the second element s 2 (t) consists of a median value of the sensed engine- speed elements r 21 (t), r 22 (t), ' ,r 40 (t), etc.
  • r t (t) is related to a marker #i, among the 120 markers.
  • the engine-speed elements corresponding to different cylinders of the engine may be overlapping.
  • T 1 (t), r 2 (t), , r 25 (t) may be corresponding to the first cylinder Ca and r 21 (t), r 22 (t), ' , r 45 (t) may be corresponding to the second cylinder Cb.
  • s 2 (t) corresponds to the median value of the engine-speed elements f2i(t), r 22 (t), -,T 40 Qi), etc.
  • the comparison value d(t) is defined as:
  • K is a predetermined constant value. According to an embodiment K corresponds to the idle engine speed. For example the idle engine speed is 500 rpm. By choosing an idle speed of 500 rpm the method according to the present invention becomes more robust regarding variation of the engine speed.
  • K is a predetermined numerical value.
  • the value of K may be preset and stored in a memory of the electronic control unit 110.
  • the value of K can e.g. be about 0,01.
  • the vector s 2 (t), ,s 6 (t)] ⁇ is shifted every 20 th engine-speed value.
  • Example 1 Determine the weight vector w
  • the weight vector w is a pre-calculated design parameter, which could be optimized as stated below.
  • the weight vector w is a design parameter which is predetermined by an experimental procedure.
  • the beforehand determined weight vector w is stored in a memory of the electronic control unit 110.
  • a vector w determined in this way contribute with the positive advantage that an easier identification procedure of a malfunctioning cylinder/injector is achieved. This is clearly shown in the graph depicted with reference to Figure 3. Thus, by choosing a weight vector w, as depicted in this example, a value difference between a (highest) value d,(t), corresponding to a malfunctioning cylinder/injector, and another (second highest) value d,(t), is increased. It should be noted that i ⁇ j and that index i refers to the malfunctioning fuel injector. Further, the index j refers to any properly functioning fuel injector.
  • weight parameter w the sum of the elements of w is equal to zero (0), which provides the advantage that in a case wherein an average engine speed signal is constant, i.e. when the engine runs without a malfunctioning fuel injector, for the respective cylinders the detection signal d(t) will be equal to zero (0). Also, the boundary condition implying that the weight vector w should have a norm which is equal to one (1) will be fulfilled.
  • Figure 3 a is an example graph wherein comparison values d(t) corresponding to the six cylinders 1, 2,..., 6 is shown.
  • the second cylinder Cb has a highest comparison value d(t). This indicates that the injector 150b may be injecting an excessive amount of fuel to the second cylinder Cb.
  • ⁇ L ⁇ -L2.
  • a suitably chosen weight vector w contributes to generate a significant difference value ⁇ , which in turn facilitates identification of a malfunctioning cylinder/fuel injector.
  • Figure 3b is an example graph associated with the example illustrated with reference to Figure 3a.
  • the graph depicts that engine speed is increased during the power stroke of the second cylinder Cb.
  • Figure 4 schematically illustrates in greater detail a method for identifying a malfunctioning fuel injector associated with an individual cylinder of a multicylinder combustion engine.
  • the method comprises a first step s410.
  • the step s410 comprises the step of generating a first data set r(t) comprising engine-speed values rl-r20; rl-rl20 corresponding to at least one cylinder of said engine.
  • the engine speed values are generated in real time, sequentially.
  • engine speed values corresponding to one cylinder e.g. T 1 - ⁇ o, corresponding to the first cylinder, are generated substantially at the same time in a batch.
  • the step s415 comprises the step of processing said first data set. After the step s415 a subsequent step s420 is performed.
  • the step s420 comprises the step of generating a second data set s(t) depending upon said first data set r(t).
  • the processing of the first data set according to step s415 involves the process of determining the median value of the first data set so as to generate said second data set.
  • a subsequent step s425 is performed.
  • the step s425 comprises the step of processing said second data set s(t). After the method step s425 a subsequent step s430 is performed.
  • the step s430 comprises the step of establishing a detection value d(t).
  • the processing of the second data set according to step s425 involves the process of establishing a detection value.
  • a subsequent step s435 is performed.
  • the step s435 comprises the step of comparing said detection value d(t) with a predetermined threshold value K. According to an embodiment of the present invention the comparison process involves determining whether the detection value is greater than or equal to the threshold value. After the step s435 a subsequent step s440 is performed.
  • the step s440 comprises the step of identifying at least one malfunctioning fuel injector depending upon said comparison. If the detection value is greater than the threshold value one fuel injector is malfunctioning. Which fuel injector is malfunctioning is determined through the following:
  • the step s445 comprises the step of storing a result of the identification step performed with reference to the step s440.
  • the result of the identification step comprises information about which fuel injector is identified to be malfunctioning, i.e. having a too long on- time, implying that an excessive amount of fuel is injected.
  • the result of the identification step is displayed on a display such that the information can be provided to an operator. Thereafter the method ends.
  • the electronic control unit 110 is also referred to as apparatus.
  • the apparatus comprises a computer program product in the form of a non- volatile memory 520, a data processing device 510 and a read/write memory 550.
  • Nonvolatile memory 520 has a first memory portion 530 wherein a computer program, such as an operating system, is stored for controlling the function of apparatus.
  • apparatus comprises a bus controller, a serial communication port, I/O- means, an A/D-converter, a time date entry and transmission unit, an event counter and an interrupt controller (not shown).
  • Non-volatile memory 520 also has a second memory portion 540.
  • a computer program P comprising routines for identifying a malfunctioning injector/cylinder may be stored in an executable manner or in a compressed state in computer program products in the form of a separate memory 560 and/or in the read/write memory 550.
  • the memory 560 is a non-volatile memory, such as a flash memory, an EPROM, an EEPROM or a ROM.
  • the data processing device 510 performs a certain function it should be understood that the data processing device 510 performs a certain part of the program which is stored in the separate memory 560, or a certain part of the program which is stored in the read/write memory 550.
  • Data processing device 510 may communicate with a data communications port 599 by means of a data bus 515.
  • the non-volatile memory 520 is adapted for communication with the data processing device 510 via a data bus 512.
  • the separate memory 560 is adapted for communication with the data processing device 510 via a data bus 511.
  • the read/write memory 550 is adapted for communication with the data processing device 510 via a data bus 514.
  • data received on the data port 599 When data is received on the data port 599 from the engine speed sensor unit 80 it is temporarily stored in the second memory portion 540. When the received input data has been temporarily stored, the data processing device 510 is set up to perform execution of code in a manner described above. According to a preferred embodiment of the invention, data received on the data port 599 comprises time information associated with the fly wheel 70. This information can be used by the apparatus so as to identify which cylinder of the engine 60 onboard the platform is malfunctioning.
  • Parts of the methods described herein can be performed by apparatus by means of the data processing device 510 running the program stored in the separate memory 560 or the read/write memory 550. When apparatus runs the program, parts of the methods described herein are executed.
  • the apparatus is arranged to run a computer program for identifying a malfunctioning fuel injector associated with an individual cylinder of a multicylinder combustion engine, comprising computer readable program code means for causing the apparatus, an electronic control unit or another computer connected to the electronic control unit to perform the steps of: -generating a first data set r(t) comprising engine-speed values (rl-r20; rl-rl20) corresponding to at least one cylinder of said engine; -processing said first data set (r(t)) so as to generate a second data set (s(t)) depending upon said first data set (r(t));
  • the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of establishing the median value of a chosen number of said engine-speed values (rl-r20; rl-rl20) during the step of processing said first data set (r(t)).
  • the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of weighting of said second data set by means of a weight vector during the step of establishing a detection value.
  • the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of normalizing said detection value during the step of establishing said detection value.
  • the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of resetting said first data set after each engine cycle.
  • the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of determining the malfunctioning of a fuel injector by identifying a high engine speed value relative to a desired value.
  • the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of periodically upgrading the second data set s(t) .
  • the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of identifying at least one malfunctioning fuel injector is established in dependence of the upgrade of s(t).
  • the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of identifying at least one malfunctioning fuel injector is established in dependence of a predetermined validation time.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

The present invention relates to a method for identifying a malfunctioning fuel injector (150a, 150b, 150c, 150d, 150e, 150f) associated with an individual cylinder (Ca, Cb, Cc, Cd, Ce, Cf) of a multicylinder combustion engine (60). The method comprises the step of generating a first data set (r(t)) comprising engine-speed values (rl-r20; rl-rl20) corresponding to at least one cylinder of said engine. The method also comprises the step of processing said first data set (r(t)) so as to generate a second data set (s(t)) depending upon said first data set (r(t)). The method further comprises the steps of processing said second data set (s(t)) so as to establish a detection value (d(t)), and comparing said detection value (d(t)) with a predetermined threshold value (K), and identifying at least one malfunctioning fuel injector depending upon said comparison, and weighting of said second data set by means of a weight vector during the step of establishing the detection value.

Description

Method and computer program product for identifying a malfunctioning cylinder of a multi-cylinder combustion engine
Technical field
The present invention relates to a method for identifying a malfunctioning fuel injector of a cylinder of a multi-cylinder combustion engine. The invention also relates to a computer program product comprising computer program code for implementing a method according to the invention. The invention also relates to a computer. The invention further relates to a platform having a computer.
Background of the invention
When a multi-cylinder combustion engine fails to deliver its rated power, this may be due to the malfunctioning of any of the cylinders of the engine. In the case of a diesel engine, the malfunctioning of a cylinder may be due to overfuelling caused by a faulty fuel injector or to excessive fuel pressure within a fuel supply system of the engine.
US 5095742 discloses a method for diagnosis of faulty ignition in individual cylinders by calculating power loss. According to the method of US 5095742 accelerations of the engine speed are measured. Subsequently an acceleration value of a measurement associated with a particular cylinder of the engine is compared with a median acceleration and the resulting difference is used for a normalized calculation of power loss.
Today, there exists a need to identify a malfunctioning of a cylinder out of a plurality of properly functioning cylinders of an engine. Summary of the invention
An object of the invention is to provide a new and advantageous manner of identifying a malfunctioning fuel injector associated with an individual cylinder of a multicylinder combustion engine.
An object of the invention according to an aspect of the invention is to provide an improved method for diagnosing a multi-cylinder combustion engine.
According to the invention, these objects are achieved by a method for identifying a malfunctioning fuel injector associated with an individual cylinder of a multicylinder combustion engine, comprising the steps of:
-generating a first data set comprising engine- speed values corresponding to at least one cylinder of said engine; -processing said first data set so as to generate a second data set depending upon said first data set;
-processing said second data set so as to establish a detection value;
-comparing said detection value with a predetermined threshold value;
-identifying at least one malfunctioning fuel injector based upon said comparison; -in which said step of establishing a detection value may involve weighting of said second data set by means of a weight vector. By this an erroneous detection of a malfunctioning fuel injector is reduced.
An advantage of the present invention is that the derivative of the engine speed values does not need to be taken into consideration. This thus means that the torque of the crank shaft also does not need to be taken into consideration. An advantage is that the noise reduction is improved.
An advantage of the present invention is also that the number of erroneous detections is reduced. The present invention further provides an improved ability to early detect a malfunctioning cylinder of a multi-cylinder engine, which is highly desirable, not least for the operators of the vehicle, such as a driver of a heavy vehicle.
A beneficial contribution of the invention is that a cost effective solution to the above stated problems is achieved. Existing vehicles may easily be upgraded with relevant software so as to achieve the positive effects of the present invention.
Yet another beneficial contribution of the invention is that the method for identifying a malfunctioning cylinder of a multi-cylinder engine is robust.
Yet another beneficial contribution of the invention is that an erroneous detection of a malfunctioning fuel injector is reduced.
The step of processing said first data set may involve establishing the median value of a chosen number of said engine-speed values. It is an advantage in comparison to using the mean value, as false calculations are diminished in this case. Alternatively other calculation procedures may be used, such as calculating the cylinder wise mean engine speed by measuring the time from marker #1 to #21.
The weight vector may comprise elements, the sum of which is substantially zero (0). The advantage with this is that under normal conditions, when the average engine speed is close to constant, the weighting is close to zero.
The step of establishing said detection value may involve normalizing said detection value. It should be pointed out that the normalization preferably is performed in relation to idle engine speed. This makes the algorithm average speed independent.
Said second data set may constitute a set of elements, each element correlates to an individual cylinder. The method may comprise the step of resetting said first data set after each engine cycle. Advantageously effects from earlier time instants will not affect the performance.
The method may comprise the step of periodically upgrading the second data set.
The step of identifying at least one malfunctioning fuel injector may be established in dependence of the upgrade of the second data set.
The step of identifying at least one malfunctioning fuel injector may be established in dependence of a predetermined validation time. Validation makes detection more robust to false alarms.
The method may be performed on-line, i.e. in real time during operation of the engine. Thus, possible malfunction may be detected at an early stage. This facilitates for the operator to shut off the injector or attend to the problem by replacing the malfunctioning fuel injector.
Additional objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following details, as well as by practice of the invention. While the invention is described below, it should be understood that the invention is not limited to the specific details disclosed. A person skilled in the art having access to the teachings herein will recognise additional applications, modifications and embodiments in other fields, which are within the scope of the invention.
Brief description of the drawings
For a more complete understanding of the present invention and further objects and advantages thereof, reference is now made to the examples shown in the accompanying drawings, in which: Figure Ia schematically illustrates a fuel injection system for a combustion engine according to an aspect of the present invention;
Figure Ib schematically illustrates a combustion engine and a control unit according to an aspect of the present invention;
Figure 2 schematically illustrates a side view of the fuel injection system for a combustion engine shown in Figure 1 according to an aspect of the present invention;
Figure 3a schematically illustrates a graph according to an aspect of the present invention;
Figure 3b schematically illustrates a graph according to an aspect of the present invention;
Figure 4 schematically illustrates a flow chart depicting a method for identifying a malfunctioning cylinder/fuel injector according to an aspect of the present invention; and
Figure 5 schematically illustrates an electronic control unit according to an aspect of the invention.
Detailed description of the drawings
With reference to Figure Ia, a sub-system of a platform 10 is shown. The platform 10 is preferably a ground vehicle, such as a truck or lorry. It should be noted that the platform 10 alternatively can be a water craft or underwater craft, e.g. a ship or submarine. Alternatively the platform 10 can be a power plant. Hereinafter the term "link" refers to a communication link which may be a physical connector, such as an optoelectronic communication wire, or a non-physical connector such as a wireless connection, for example a radio or microwave link. Further, hereinafter the term malfunctioning primarily refers to a too high fuel injection, i.e. the amount of fuel supplied to the cylinder is considerably higher than a desired amount. This kind of malfunction may lead to cylinder/engine breakdown.
Fig. Ia shows a fuel injection system for a combustion engine 60 (shown fig. Ib) in the form of a schematically represented diesel engine having six cylinders. The fuel injection system and the diesel engine are with advantage fitted to heavy vehicle, such as truck, lorry or bus, for propelling the vehicle. The fuel injection system is a so-called Common Rail system and comprises a fuel line for supply of fuel from a fuel tank 115 to the cylinders of the diesel engine. A fuel pump 116 is arranged in the fuel line to convey fuel from the fuel tank via a filter 117 to a high-pressure pump 118. The high pressure pump 118 is adapted to pressurize the fuel so that it enters at high pressure an accumulator tank 120 which takes the form of a so-called Common Rail. The high fuel pressure in the accumulator tank 120 constitutes a power source making it possible for fuel to be injected at high pressure into the respective cylinders of the diesel engine. The fuel in the accumulator tank 120 is intended to be distributed to all the cylinders of the combustion engine 60.
To control the injection of fuel, injection means 150a- 15Of is arranged in each of the connections between the accumulator tank 120 and the respective cylinders of the diesel engine. When an injection means is in an open state, it injects fuel at high pressure into the cylinder concerned. Thus, fuel from the accumulator tank 120 is injected into the combustion spaces of the respective cylinder by means of the injection means which is in the form of electronic injectors which injectors can open and close very quickly. A control unit in the form of an electronic control unit 110 (ECU) is adapted to control the operation of the fuel pump 116, the high pressure pump 118 and the injection means 150a, 150b, 150c, 15Od, 15Oe, and 15Of. A pressure sensor 122 is fitted in the accumulator tank 120 to detect the prevailing pressure therein and to send to the control unit 110 a signal S 122 conveying information about the pressure values detected. On the basis of knowing the pressure in the accumulator tank, the electronic control unit 110 controls the on- time or opening times of each individual electronic injector so that the calculated amount of fuel is supplied with good accuracy to the combustion spaces of the respective cylinders.
In this description, the term "on-time" refers to the opening time of an injector, i.e. the duration of the time period during which the injector is kept open in order to inject fuel into the associated cylinder in connection with a single stroke of the engine. The quantity of fuel injected into a cylinder in connection with a stroke of the engine depends on the length of the on-time and the pressure of the fuel supplied to the injector.
Here, the inventive method is initiated and controlled by means of the electronic control unit 110. Alternatively, the inventive method is initiated and controlled by means of an external PC 112. The external computer may be directly connected to the electronic control unit 110 via a link 114, but may also be indirectly connected to the electronic control unit 110 in any suitable manner, such as through an internal vehicle internal network. The communication between the external computer and the engine control unit may be partly or entirely wireless. The inventive method could also be initiated and controlled by the electronic control unit 110 itself or by another electronic control unit comprised in an internal vehicle network, such as an electronic gear box control unit.
Figure Ib shows the engine having six cylinders, each cylinder Ca, Cb, Cc, Cd, Ce, and Cf (not shown) being provided with a piston a, b, c, d, e, f, respectively. It should be noted that the invention is applicable to any multicylinder combustion engine with an arbitrary number of cylinders. The six pistons are attached to a crank shaft 50. The crank shaft 50 is attached to a fly wheel 70 being arranged to rotate with the same speed as the crank shaft 50. A sensor unit 80 is provided at a close proximity to the fly wheel 70. The sensor unit 70 is arranged to measure engine speed by detecting time points corresponding to detections of markers equidistantly provided on the fly wheel 70 as depicted in greater detail below. The sensor unit 80 is arranged for communication with the electronic control unit 110 via a link 81. The sensor unit 80 is arranged to continuously transmit detected discrete time points. Alternatively, the sensor unit 80 is arranged to on a regular basis send signals comprising a plurality of detected discrete time points.
Thus, the electronic control unit is arranged to receive sensed engine data in the form of e.g. a toothed fly wheel signal (TF-signal). The TF-signal is received on a data communications port from the engine-speed sensor unit 80 which senses rotation of the engine's toothed fly wheel 70. The engine-speed sensor 80 may be e.g. an inductive type sensor or a Hall-effect sensor. Of course there may be more than one engine-speed sensor unit and other positions for measuring engine speed, such as measuring the engine's camshaft speed and the speed of a generator connected to the engine.
The electronic control unit 110 is arranged to perform a diagnosis test depending upon transmitted discrete time points from the sensor unit 80, so as to determine if one or more injectors associated with a unique cylinder of the engine is malfunctioning.
Figure 2 schematically illustrates a side view of the fly wheel of the engine. There is also shown the engine-speed sensor unit 80 arranged for communication with the electronic control unit 110 via the link 81.
The flywheel 60 is provided with 60 markers denoted #1, #2, ... , #60, such as teeth or holes. However, since there are four strokes in an engine cycle two turns of the flywheel results in each marker being calculated twice and therefore 120 markers are sensed by the engine-speed sensor unit 80 during an engine cycle. The measurements are denoted #1, #2, ... , #120, wherein #1 and #61, #2 and #62 etc. corresponds to the same marker. The engine-speed sensor unit 80 is arranged to detect a time point corresponding to a marker passing by a predetermined location, e.g. a location schematically indicated at marker #60 (and #120).
A person skilled in the art thus realizes that two turns of the flywheel 70 correspond to one engine cycle, which in turn corresponds to two turns of the crankshaft 50. It should be noted that the invention is suitable for various types of flywheels having an arbitrary number of markers.
The electronic control unit 110 is arranged to calculate an engine-speed value r^t) corresponding to each of the teeth i of the flywheel 70, wherein i is an integer in the interval 1-120,. The calculation of the respective engine-speed value is performed depending upon received time point data, which data is communicated by the engine-speed sensor unit.
Alternatively, the engine-speed sensor unit 80 is arranged to calculate an engine- speed value T1(Y), wherein i is an integer in the interval 1-120, corresponding to each of the teeth of the flywheel 70 and to continuously transmit these values to the electronic control unit 110.
An engine- speed vector r(t) is generated, wherein
r(fHri(t), r2(t), -,r12O(t)]T
wherein T is the transpose.
The electronic control unit is further arranged to generate a more dense vector s(t). The vector s(t) includes median values of predetermined groups of engine-speed elements of the engine-speed value vector r(t). In this example, a median value of the first 20 engine-speed elements T1(I), r2(t), ,r20(t) is generated, denoted s^t). Similarly, the second element s2(t) consists of a median value of the sensed engine- speed elements r21(t), r22(t), ' ,r40(t), etc.
rt (t) is related to a marker #i, among the 120 markers.
Thus,
S(I)=[S1(I), S2Ct), ,s6(t)]τ, wherein s1(t)=median(r1(t), r2(t), ,r20(t)) s2(t)=median(r21(t), r22(t),- ,r40(t))
s6(t)=median(rlol(t), r1O2(t), -,r12o(t))
It should be noted that the engine-speed elements r^t), r2(t),' , r20(t) corresponds to sensed measurements of the first cylinder Ca as depicted with reference to Figure Ib.
Alternatively the engine-speed elements corresponding to different cylinders of the engine may be overlapping. For example, T1 (t), r2(t), , r25(t) may be corresponding to the first cylinder Ca and r21(t), r22(t), ' , r45(t) may be corresponding to the second cylinder Cb.
Accordingly, s2(t) corresponds to the median value of the engine-speed elements f2i(t), r22(t), -,T40Qi), etc.
Hereby a comparison value d(t) is introduced. The comparison value d(t) is defined as:
Figure imgf000011_0001
wherein w is a weight vector of the same range as s(t). One way of determining w is depicted below with reference to Example 1. K is a predetermined constant value. According to an embodiment K corresponds to the idle engine speed. For example the idle engine speed is 500 rpm. By choosing an idle speed of 500 rpm the method according to the present invention becomes more robust regarding variation of the engine speed.
d{t) > K , where K is a predetermined numerical value. The value of K may be preset and stored in a memory of the electronic control unit 110. The value of K can e.g. be about 0,01.
It should also be noted that:
- 1 < K < 1 , where proper working injectors and cylinders are corresponding to a value close to 1.
According to a preferred embodiment of the invention the vector
Figure imgf000012_0001
s2(t), ,s6(t)]τ is shifted every 20th engine-speed value.
Let t20 be the time it takes to collect 20 new speed samples, e.g. { r21, r22, ,r40}, then the vector s(t) is shifted as s(t+ t20)=[s2(t+ 120), ..., s6(t+ t2o), s^t+ t2o)] .
Example 1. Determine the weight vector w
The weight vector w is a pre-calculated design parameter, which could be optimized as stated below.
max mm _, τ w = arg „2^(0-^-0) w w w ≤ l w i ≠ O „
meaning that a preferred vector w is determined by maximizing the expression: -ji — 1V" is maximized
IHoI
while minimizing the expression:
wτs (t) ,. ' .. , where i ≠ j , and where the index i represents the malfunctioning
IKOl cylinder/fuel injector. Thus, the weight vector w is a design parameter which is predetermined by an experimental procedure. The beforehand determined weight vector w is stored in a memory of the electronic control unit 110.
A vector w determined in this way contribute with the positive advantage that an easier identification procedure of a malfunctioning cylinder/injector is achieved. This is clearly shown in the graph depicted with reference to Figure 3. Thus, by choosing a weight vector w, as depicted in this example, a value difference between a (highest) value d,(t), corresponding to a malfunctioning cylinder/injector, and another (second highest) value d,(t), is increased. It should be noted that i ≠ j and that index i refers to the malfunctioning fuel injector. Further, the index j refers to any properly functioning fuel injector.
According to one example of weight parameter w, the sum of the elements of w is equal to zero (0), which provides the advantage that in a case wherein an average engine speed signal is constant, i.e. when the engine runs without a malfunctioning fuel injector, for the respective cylinders the detection signal d(t) will be equal to zero (0). Also, the boundary condition implying that the weight vector w should have a norm which is equal to one (1) will be fulfilled.
End of Example 1
Figure 3 a is an example graph wherein comparison values d(t) corresponding to the six cylinders 1, 2,..., 6 is shown. In this particular example there is shown that the second cylinder Cb has a highest comparison value d(t). This indicates that the injector 150b may be injecting an excessive amount of fuel to the second cylinder Cb.
There is also illustrated that a level difference between the comparison value d(t) corresponding to the indicated malfunctioning cylinder/fuel injector Cb/ 150b and a second highest comparison value, which in this example corresponds to the fourth cylinder/fuel injector Cd/150d, is L1-L2. The difference between a highest level Ll and a second highest level L2 is denoted φ . Thus, φ=L\-L2. A suitably chosen weight vector w contributes to generate a significant difference value φ , which in turn facilitates identification of a malfunctioning cylinder/fuel injector.
Figure 3b is an example graph associated with the example illustrated with reference to Figure 3a. The graph depicts that engine speed is increased during the power stroke of the second cylinder Cb.
Figure 4 schematically illustrates in greater detail a method for identifying a malfunctioning fuel injector associated with an individual cylinder of a multicylinder combustion engine.
The method comprises a first step s410. The step s410 comprises the step of generating a first data set r(t) comprising engine-speed values rl-r20; rl-rl20 corresponding to at least one cylinder of said engine. According to a first embodiment the engine speed values are generated in real time, sequentially. As an alternative to generating engine speed values sequentially, engine speed values corresponding to one cylinder, e.g. T1-^o, corresponding to the first cylinder, are generated substantially at the same time in a batch. After the method step s410 a subsequent step s415 is performed.
The step s415 comprises the step of processing said first data set. After the step s415 a subsequent step s420 is performed. The step s420 comprises the step of generating a second data set s(t) depending upon said first data set r(t). According to an embodiment of the present invention the processing of the first data set according to step s415 involves the process of determining the median value of the first data set so as to generate said second data set. After the step s420 a subsequent step s425 is performed.
The step s425 comprises the step of processing said second data set s(t). After the method step s425 a subsequent step s430 is performed.
The step s430 comprises the step of establishing a detection value d(t). According to an embodiment of the present invention the processing of the second data set according to step s425 involves the process of establishing a detection value. After the step s430 a subsequent step s435 is performed.
The step s435 comprises the step of comparing said detection value d(t) with a predetermined threshold value K. According to an embodiment of the present invention the comparison process involves determining whether the detection value is greater than or equal to the threshold value. After the step s435 a subsequent step s440 is performed.
The step s440 comprises the step of identifying at least one malfunctioning fuel injector depending upon said comparison. If the detection value is greater than the threshold value one fuel injector is malfunctioning. Which fuel injector is malfunctioning is determined through the following:
Firstly it is, as depicted above, determined whether the detection value is greater than the threshold value K. Secondly it is determined which value s;(t) is corresponding to the detection value d(t) being compared with the threshold value K by identifying the first element in the upgraded vector s(t). The vector s(t) is, as described above upgraded after each twentieth received engine speed value. Thus, it is identified which engine speed values that correlates to the malfunctioning fuel injector. After the step s440 a subsequent step s445 is performed.
The step s445 comprises the step of storing a result of the identification step performed with reference to the step s440. The result of the identification step comprises information about which fuel injector is identified to be malfunctioning, i.e. having a too long on- time, implying that an excessive amount of fuel is injected. According to one embodiment the result of the identification step is displayed on a display such that the information can be provided to an operator. Thereafter the method ends.
With reference to Figure 5, a diagram of one embodiment of the electronic control unit 110 is shown. The electronic control unit 110 is also referred to as apparatus. The apparatus comprises a computer program product in the form of a non- volatile memory 520, a data processing device 510 and a read/write memory 550. Nonvolatile memory 520 has a first memory portion 530 wherein a computer program, such as an operating system, is stored for controlling the function of apparatus. Further, apparatus comprises a bus controller, a serial communication port, I/O- means, an A/D-converter, a time date entry and transmission unit, an event counter and an interrupt controller (not shown). Non-volatile memory 520 also has a second memory portion 540.
A computer program P comprising routines for identifying a malfunctioning injector/cylinder may be stored in an executable manner or in a compressed state in computer program products in the form of a separate memory 560 and/or in the read/write memory 550. The memory 560 is a non-volatile memory, such as a flash memory, an EPROM, an EEPROM or a ROM.
When it is stated that the data processing device 510 performs a certain function it should be understood that the data processing device 510 performs a certain part of the program which is stored in the separate memory 560, or a certain part of the program which is stored in the read/write memory 550.
Data processing device 510 may communicate with a data communications port 599 by means of a data bus 515. The non-volatile memory 520 is adapted for communication with the data processing device 510 via a data bus 512. The separate memory 560 is adapted for communication with the data processing device 510 via a data bus 511. The read/write memory 550 is adapted for communication with the data processing device 510 via a data bus 514.
When data is received on the data port 599 from the engine speed sensor unit 80 it is temporarily stored in the second memory portion 540. When the received input data has been temporarily stored, the data processing device 510 is set up to perform execution of code in a manner described above. According to a preferred embodiment of the invention, data received on the data port 599 comprises time information associated with the fly wheel 70. This information can be used by the apparatus so as to identify which cylinder of the engine 60 onboard the platform is malfunctioning.
Parts of the methods described herein can be performed by apparatus by means of the data processing device 510 running the program stored in the separate memory 560 or the read/write memory 550. When apparatus runs the program, parts of the methods described herein are executed.
According to an aspect of the invention the apparatus is arranged to run a computer program for identifying a malfunctioning fuel injector associated with an individual cylinder of a multicylinder combustion engine, comprising computer readable program code means for causing the apparatus, an electronic control unit or another computer connected to the electronic control unit to perform the steps of: -generating a first data set r(t) comprising engine-speed values (rl-r20; rl-rl20) corresponding to at least one cylinder of said engine; -processing said first data set (r(t)) so as to generate a second data set (s(t)) depending upon said first data set (r(t));
-processing said second data set (s(t)) so as to establish a detection value (d(t)) -comparing said detection value (d(t)) with a predetermined threshold value (K); -identifying at least one malfunctioning fuel injector depending upon said comparison.
According to an aspect of the invention the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of establishing the median value of a chosen number of said engine-speed values (rl-r20; rl-rl20) during the step of processing said first data set (r(t)).
According to an aspect of the invention the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of weighting of said second data set by means of a weight vector during the step of establishing a detection value.
According to an aspect of the invention the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of normalizing said detection value during the step of establishing said detection value.
According to an aspect of the invention the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of resetting said first data set after each engine cycle. According to an aspect of the invention the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of determining the malfunctioning of a fuel injector by identifying a high engine speed value relative to a desired value.
According to an aspect of the invention the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of periodically upgrading the second data set s(t) .
According to an aspect of the invention the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of identifying at least one malfunctioning fuel injector is established in dependence of the upgrade of s(t).
According to an aspect of the invention the apparatus is arranged to run a computer program, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of identifying at least one malfunctioning fuel injector is established in dependence of a predetermined validation time.
The foregoing description of the preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated.

Claims

Claims
1. A method for identifying a malfunctioning fuel injector (150a, 150b, 150c, 150d, 15Oe, 15Of) associated with an individual cylinder (Ca, Cb, Cc, Cd, Ce, Cf) of a multicylinder combustion engine (60), comprising the steps of:
- generating a first data set (r(t)) comprising engine-speed values (rl-r20; rl-rl20) corresponding to at least one cylinder of said engine;
- processing said first data set (r(t)) so as to generate a second data set (s(t)) depending upon said first data set (r(t));
- processing said second data set (s(t)) so as to establish a detection value (d(t));
- comparing said detection value (d(t)) with a predetermined threshold value (K);
- identifying at least one malfunctioning fuel injector depending upon said comparison; - in which said step of establishing a detection value involves weighting of said second data set by means of a weight vector (w).
2. Method according to claim 1 characterized in that the step of processing said first data set (r(t)) involves establishing the median value of a chosen number of said engine-speed values (rl-r20; rl-rl20).
3. Method according to claim 1 or 2 characterized in that the weight vector comprises elements, the sum of which is substantially zero (0).
4. Method according to any of claims 1-3 characterized in that the step of establishing said detection value (d(t)) involves normalizing said detection value.
5. Method according to any of claims 1-4 characterized in that said second data set (s(t)) constitutes a set of elements (sl-s6), each element correlating to an individual cylinder.
6. Method according to any of claims 1-5 characterized by the step of:
- resetting said first data set after each engine cycle.
7. Method according to any of claims 1-6 characterized by the step of: - periodically upgrading the second data set (s(t)).
8. Method according to claim 7 characterized in that the step of identifying at least one malfunctioning fuel injector is established in dependence of the upgrade of the second data set (s(t)).
9. Method according to any of claims 1-8 characterized in that the step of identifying at least one malfunctioning fuel injector is established in dependence of a predetermined validation time.
10. Computer program (P) for identifying a malfunctioning fuel injector (150a,
150b, 150c, 150d, 15Oe, 15Of) associated with an individual cylinder (Ca, Cb, Cc, Cd, Ce, Cf) of a multicylinder combustion engine (60), comprising computer readable program code means for causing an electronic control unit (110) or another computer connected to the electronic control unit to perform the steps of: - generating a first data set (r(t)) comprising engine-speed values (rl-r20; rl-rl20) corresponding to at least one cylinder of said engine;
- processing said first data set (r(t)) so as to generate a second data set (s(t)) depending upon said first data set (r(t));
- processing said second data set (s(t)) so as to establish a detection value (d(t)); - comparing said detection value (d(t)) with a predetermined threshold value (K);
- identifying at least one malfunctioning fuel injector based upon said comparison;
- weighting of said second data set by means of a weight vector during the step of establishing the detection value.
11. Computer program according to claim 10, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of establishing the median value of a chosen number of said engine-speed values (rl-r20; rl-rl20) during the step of processing said first data set (r(t)).
12. Computer program according to claim 10 or 11 , comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of normalizing said detection value during the step of establishing said detection value.
13. Computer program according to any of claims 10-12, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of resetting said first data set after each engine cycle.
14. Computer program according to any of claims 10-13, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of determining the malfunctioning of a fuel injector by identifying a high engine speed value relative to a desired value.
15. Computer program according to any of claims 10-14, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of periodically upgrading the second data set (s(t)).
16. Computer program according to claim 15, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of identifying at least one malfunctioning fuel injector established in dependence of the upgrade of s(t).
17. Computer program according to any of claims 10-16, comprising computer readable means for causing the electronic control unit or another computer connected to the electronic control unit to perform the step of identifying at least one malfunctioning fuel injector established in dependence of a predetermined validation time.
18. Computer program product (550, 560) comprising a computer program (P) according to any of claims 10-17 and a computer readable medium on which the computer program is stored.
19. Computer, such as an embedded electronic control unit or a vehicle external computer comprising a storage means and a computer program according to any of claims 10-18 stored in the storage means.
20. Platform (10) comprising a computer according to claim 19.
21. Platform according to claim 20 wherein said platform is chosen among a group comprising vehicle, water craft and underwater craft, such as truck, ship and submarine respectively, or power plant.
PCT/SE2008/050519 2007-05-09 2008-05-07 Method and computer program product for identifying a malfunctioning cylinder of a multi-cylinder combustion engine Ceased WO2008140403A1 (en)

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