GB2519554A - Method of estimating a leakage of fuel into oil in an internal combustion engine - Google Patents

Method of estimating a leakage of fuel into oil in an internal combustion engine Download PDF

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Publication number
GB2519554A
GB2519554A GB1318803.2A GB201318803A GB2519554A GB 2519554 A GB2519554 A GB 2519554A GB 201318803 A GB201318803 A GB 201318803A GB 2519554 A GB2519554 A GB 2519554A
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GB
United Kingdom
Prior art keywords
fuel
leakage
oil
value
engine
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.)
Withdrawn
Application number
GB1318803.2A
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GB201318803D0 (en
Inventor
Massimiliano Melis
Francesco Concetto Pesce
Salvatore Sannino
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GM Global Technology Operations LLC
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GM Global Technology Operations LLC
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 GM Global Technology Operations LLC filed Critical GM Global Technology Operations LLC
Priority to GB1318803.2A priority Critical patent/GB2519554A/en
Publication of GB201318803D0 publication Critical patent/GB201318803D0/en
Publication of GB2519554A publication Critical patent/GB2519554A/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
    • F01M11/10—Indicating devices; Other safety devices
    • 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
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/16—Controlling lubricant pressure or quantity
    • F01M2001/165—Controlling lubricant pressure or quantity according to fuel dilution in oil
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
    • F01M11/10—Indicating devices; Other safety devices
    • F01M2011/14—Indicating devices; Other safety devices for indicating the necessity to change the oil
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
    • F01M11/10—Indicating devices; Other safety devices
    • F01M2011/14—Indicating devices; Other safety devices for indicating the necessity to change the oil
    • F01M2011/1486—Indicating devices; Other safety devices for indicating the necessity to change the oil by considering duration of operation
    • 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
    • F02D2041/224—Diagnosis of the fuel system
    • F02D2041/225—Leakage detection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0602—Fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0606—Fuel temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
    • F02D2200/101—Engine speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/11—Oil dilution, i.e. prevention thereof or special controls according thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16N—LUBRICATING
    • F16N2200/00—Condition of lubricant
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16N—LUBRICATING
    • F16N2210/00—Applications
    • F16N2210/16—Pumps

Abstract

A method of estimating leakage of fuel into the lubricating oil of an internal combustion engine (110), the internal combustion engine having a fuel pump (180, fig.1) for pumping fuel to a fuel rail (170), comprises the steps of (i) calculating a value of leakage into oil Qleak as a function of an engine speed n, fuel rail pressure prail, fuel temperature T and pump efficiency η, and (ii) correcting the value of leakage into oil Qleak with a correction factor Qleak_kmi, the correction factor depending on the engine ageing, to obtain a corrected value of leakage into oil Qleak_cor. The value Qleak may be calculated by Qleak = (Kleak . Δp . j) / (n . v) where Kleak is a leakage coefficient; Δp is leakage pressure; j is the number of cam lobes, and v is the kinematic viscosity of the fuel.

Description

METHOD OF ESTIMATING A LEAKAGE OF FUEL INTO OIL
(NAN INTERNAL COMBUSTION ENGINE
TECHNICAL FIELD
The present disclosure relates to a method of estimating a leakage of fuel into oil in an internal combustion engine. Particularly, the method is related to engines having a fuel pump integrated in the camshaft area.
BACKGROUND
It is known that modern engines are provided with a fuel injection system for directly injecting the fuel into the cylinders of the engine. The fuel injection system generally comprises a fuel pump, a fuel common rail and a plurality of electrically controlled fuel injectors, which are individually located in a respective cylinder of the engine and which are hydraulically connected to the fuel rail through dedicated injection pipes. The fuel is provided at high pressure to the fuel injector from a fuel rail in fluid communication with a high pressure fuel pump that increases the pressure of the fuel received from a fuel source.
As also known, lubrication is required for correct operation of the various mechanical components of the engine by using suitable lubrication circuits in which a lubricant, for example oil, is provided. In particular, for new diesel engine architecture may be equipped with a fuel pump integrated in the engine structure that is driven by dedicated cam installed on the engine camshaft and directly lubricated by the engine lubricant. Due to the clearance between a pump plunger and a pump compression chamber, fuel leakage into the engine lubricant can be observed.
As welt known, fuel leakage into oil must be avoided in order to prevent a reduced lubricant viscosity caused by the oil dilution and a high lubricant/fuel level In the oil sump. The additional fuel leakage coming from the pump will shorten the engine oil life, due to the subsequent oil dilution.
Fuel leakage into oil due to the effect of the pump plunger can be estimated counting, for each engine operating point, the fuel dropped in the oil on the basis of a model based estimation of pump leakage as a function of pump speed and rail pressure. Nevertheless, current fuel leakage estimation methods underestimate fuel leakages and consequently oil life.
Therefore a need exists for a new method of estimating fuel leakage into oil, which provides a more reliable estimation.
An object of an embodiment of the invention is to provide a method of estimating fuel leakage into oil in an internal combustion engine, which takes into account all relevant parameters influencing such phenomenon, is therefore more reliable and can serve as an input parameter for an oil life monitoring model.
These objects are achieved by a method, by an apparatus, by an internal combustion engine and by an automotive system provided with an electronic control unit able to control the fuel injection system, having the features recited in the independent claims.
The dependent claims delineate preferred anwor especially advantageous aspects.
SUMMARY
An embodiment of the disclosure provides a method of estimating a leakage of fuel into oil of an internal combustion engine, the internal combustion engine having a fuel pump for pumping fuel to a fuel rail, the method comprising the steps of -calculating a value of leakage into oil as a function of an engine speed value, a fuel rail pressure value, a fuel temperature value and a pump efficiency value, -correcting the value of leakage into oil with a correction factor, the correction factor depending on the engine ageing, to obtain a corrected value of leakage into oil.
Consequently, an apparatus is disclosed for estimating a leakage of fuel into oil, the apparatus comprising: -means for calculating a value of leakage into oil as a function of an engine speed value, a fuel rail pressure value, a fuel temperature value and a pump efficiency value, -means for correcting the value of leakage into oil with a correction factor, the correction factor depending on the engine ageing, to obtain a corrected value of leakage into oil.
An advantage of this embodiment is that the method takes into account all relevant parameters for the estimation of the fuel leakage. This allows a proper evaluation of the engine oil life, accounting the effect of the fuel pump integrated into the engine.
According to a further embodiment, said value of leakage into oil is calculated by means of the following equation: QIk=(Kkx Ap x j)I(n x v) Consequently, said means for calculating a value of leakage into oil are configured for using the following equation: QIeaIV(Kleak x Ap x j)I(n x v) An advantage of this embodiment is to provide a mathematical formula which accounts engine operating conditions (engine speed or pump speed and rail pressure), fluid characteristics (kinematic viscosity which depends on the fuel temperature) and characteristic of the fuel pump (a leakage coefficient and the number of lobes of the cam).
According to still another embodiment, said pump efficiency value is calculated by means of the following equation: 1 = (QteoQIeak_new) / Qteo Consequently, said means for calculating a value of leakage into oil are configured for using the following equation: 11 = (QteoQio&new) I Qteo An advantage of this embodiment is that at the end of the production line, the efficiency of the fuel pump is measured in the full pumping point (max. pump speed and pressure). This information is used to scale the leakage model in new condition to take into account the sample to sample variation.
According to a still further embodiment, said correction factor is calculated by means of the following equation: Qleaklcml = QfeaILrnax x kmi / kmL.
Consequently, said means for correcting the value of fuel leakage into oil are configured for using the following equation: Qieatc_icmi = Qleakmax x kmi I kmth, In this way, also the ageing effect is considered by the present method.
A further embodiment of the disclosure provides an internal combustion engine of an automotive system, the internal combustion engine having a fuel pump for pumping fuel to a fuel rail, wherein a leakage of fuel into oil is estimated by a method of according to any of the preceding claims.
The method according to one of its aspects can be carried out with the help of a computer program comprising a program-code for carrying out all the steps of the method described above, and in the form of computer program product comprising the computer program.
The computer program product can be embedded in a control apparatus for an internal combustion engine, comprising an Electronic Control Unit (ECU), a data carrier associated to the ECU, and the computer program stored in a data carrier, so that the control apparatus defines the embodiments described in the same way as the method. In this case, when the control apparatus executes the computer program all the steps of the method described above are carried out.
BRIEF DESCRIPTION OF ThE DRAWINGS
The various embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an automotive system.
Figure 2 is a section of an intemal combustion engine belonging to the automotive system of figure 1.
Figure 3 is a schematic illustration of a fuel pump integrated into the engine.
Figure 4 is a high level flowchart according to an embodiment of the present invention.
Figure 5 is a flowchart according to another embodiment of the invention.
Figure 6 is a graph depicting a comparison between calculated values and experimental values of the fuel leakage.
Figure 7 is a flowchart according to a further embodiment of the invention.
Figure 8 is a flowchart according to still another embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Some embodiments may include an automotive system 100, as shown in Figures land 2, that includes an internal combustion engine (ICE) 110 having an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145. A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150.
A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140.
The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received from a fuel source 190. The fuel injection system 165 with the above disclosed components is known as Common Rail Diesel Injection System (CR System). It is a relative new injection system for passenger cars. The main advantage of this injection system, compared to others, is that due to the high pressure in the system and the electromagnetically controlled injectors it is possible to inject the correct amounts of fuel at exactly the right moment. This implies lower fuel consumption and less emissions.
Each of the cylinders 125 has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.
The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200. An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an exhaust system 270. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.
The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NOx traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters. Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.
The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110 and equipped with a data carrier 40. The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350. a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 445. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR Valve 320, the VGT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.
Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) in communication with a memory system and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the CPU to carryout out the steps of such methods and control the ICE 110.
The program stored in the memory system is transmitted from outside via a cable or in a wireless fashion. Outside the automotive system 100 it is normally visible as a computer program product, which is also called computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, said carrier being transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.
An example of a transitory computer program product is a signal, e.g. an electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code, Carrying such computer program code can be achieved by modulating the signal by a conventional modulated technique such as QPSI< for digital data, such that binary data representing said computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a WiFi connection to a laptop.
In case of a non-transitory computer program product the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or non-permanently stored in a retrievable way In or on this storage medium. The storage medium can be of conventional type known in computer technology such as a flash memory, an Asic, a CD or the like.
Instead of an ECU 450, the automotive system 100 may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an onboard computer, or any processing module that might be deployed in the vehicle.
Figure 3 shows a schematic illustration of a fuel pump 180 integrated into the engine 110.
The fuel pump 180 has a fuel inlet valve 182, a high pressure fuel chamber 183 and a fuel outlet valve 184. Inside the pump 180, a pump plunger 186 is provided and slides along a pump cylinder 185, the pump plunger being acted upon by a cam follower (not shown in the simplified scheme of Fig.3), which is driven by a dedicated cam 188 installed on the engine camshaft 135. Fuel enters the fuel pump 180 from fuel inlet valve 182 (coming from the fuel tank 190) and exit from fuel outlet valve 184 towards fuel rail 170. A clearance 187 between the pump plunger 186 and the pump cylinder 165 is also represented in an enlarged fashion to make it more evident. During normal operation of the fuel pump 180, at every engine cycle, the compression phase of the fuel pump 180 creates different pressures between the compression chamber and the cam follower area; in this case fuel leakage through the clearance 187 of the plunger 186 can be observed. This fuel leakage contributes to oil dilution and the fuel leakage through the clearance 187 of the pump plunger 186 can be g estimated counting, for each engine operating point, the fuel dropped in the oil on the basis of a model based estimation of pump leakage based on pump speed and rail pressure or may be taken from an experimentally determined lookup table thereof.
Figure 4 is a schematic representation of a high level flowchart relative to an embodiment of the invention, namely to a method of estimating fuel leakage into oil due to engine fuel flow into the lubricant caused by the fuel pump 180. Fuel leakages into oil, which are mentioned in the following description, are leakage rates that can be expressed in liter per hour (I/h).
According to an embodiment of the present method estimates fuel leakage into oil by calculating S400 a value of fuel leakage into oil QIeak as a function of an engine speed value n, a fuel rail 170 pressure value prail, a fuel temperature value T and a pump efficiency value , and the correcting S410 the value of fuel leakage into oil with a correction factor, depending on the engine ageing, to obtain a corrected value of fuel leakage into oil.
With reference to Fig. 5, which illustrates a flow chart according to another embodiment of the present invention, the value of fuel leakage into oil Q108k is calculated S402 by means of the following equation: Qleak = (Keak x Ap x j) / (n x v) where: Keak leakage coefficient depending on engine speed and fuel rail pressure Ap leakage pressure (i.e. pressure difference between fuel and oil) n engine speed v kinematic viscosity of fuel number of cam lobes Keak is a leakage coefficient depending on the engine speed n and the rail pressure prail.
Such coefficient is linked to the pump design and shall be experimentally calibrated, knowing the pump design. A map can be built thereof, having two inputs, one for values of engine speed and the other with values of rail pressure, and one output, namely a value representative of the leakage coefficient 4ak Model results show a very good matching with experimental data.
The kinematic viscosity v is the fuel dynamic viscosity divided by the fuel density, measured as centiStokes [cStI. It is strictly related to the fuel temperature, which, as mentioned, is an input parameter of the present method. Kinematic viscosity decreases with the fuel temperature. The viscosity has impact on fuel pump leakage since lower will be the viscosity (because of the temperature increase) higher will be the leakage. In order to properly evaluate the correct fuel leakage quantity, the viscosity map 8401 takes into account the influence of fuel temperature during engine usage. In fact the real time evaluation of viscosity is used for the leakage estimation model.
Fig. 6 is a graph depicting a comparison between calculated values and experimental values of the fuel leakage. In this graph, x-axis represents rail pressure values (expresses in bar, i.e. MPa1) and y-axis shows fuel leakage Qleak values [I/h]. The several curves in the graph represent the calculated behavior of the fuel leakage vs. the rail pressure at different engine speed n values [rpml. The engine speed values grow in the direction of the arrow. The dot values are experimental values of the fuel leakage vs. the rail pressure, always with different values of the engine speed. Having properly calibrated the leakage coefficient Kicak, model results show a very good matching with experimental data.
With reference to Fig. 7 and according to a further embodiment of the present method, the pump efficiency r, is calculated S403 by means of the following equation: I = (QiecQieaiç.new) / Qteo where: Qieak_new fuel leakage of a new fuel pump Q theoretical pump flowrate The pump efficiency in the full pumping point (maximum pump speed and maximum rail pressure) is available by end of line measurements of the fuel pump manufacturers. The usage of this information (stored in a data matrix of the component) is foreseen to scale the leakage model in new condition to take into account the sample to sample variation. Knowing the efficiency the leakage value through the plunger can be evaluated.
As mentioned, the value of the fuel leakage into oil is corrected S410 with a correction factor, depending on the engine ageing, to obtain a corrected value of fuel leakage into oil. Using as input the engine mileage the pump life is evaluated. At first, a conversion between engine mileage and pump cycles is performed. With reference to Fig. 8, knowing the pump life, the leakage increase amount is evaluated 8404 considering the fuel pump delivery and scaling the worst case value Qieajcmax foreseen at the end of life with respect to the mileage. The correction factor Qleak_kmi is calculated by means of the following equation: Qleokkmi = Qieaicn,ax x kmi I kmthr where: maximum fuel leakage kmi current engine mileage kmmr engine mileage threshold Therefore, knowing the maximum fuel leakage at a predetermined mileage (normally this threshold is equal to 250,000 km) it is possible to scale the leakage correction factor according to the current engine mileage.
Summarizing, the present method allows a proper evaluation of the leakage of fuel into oil.
This information can be used for a better estimation of the engine oil life.
While at least one exemplary embodiment has been presented in the foregoing summary * and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.
REFERENCE NUMBERS AND SYMBOLS
data carrier automotive system internal combustion engine 120 engine block cylinder cylinder head camshaft piston 145 crankshaft combustion chamber cam phaser fuel injector fuel rail 180 fuel pump 182 fuel pump inlet valve 183 high pressure fuel chamber 184 fuel pump outlet valve fuel pump cylinder 186 fuel pump plunger 187 clearance 188 fuel pump cam fuel source intake manifold 205 air intake pipe 210 intake port 215 valves 220 port 225 exhaust manifold 230 turbocharger 240 compressor 245 turbocharger shaft 250 turbine 260 intercooler 270 exhaust system 275 exhaust pipe 280 aftertreatment devices 290 VGT actuator 300 exhaust gas recirculation system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow and temperature sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant temperature and level sensors 385 lubricating oil temperature and level sensor 390 metal temperature sensor 400 fuel rail pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensors 440 EGR temperature sensor 445 accelerator position sensor 446 accelerator pedal 450 ECU S400 step S401 step S402 step 8403 step 8404 step 8410 step 500 block 510 block 520 block 530 block Praji fuel rail pressure Qioaic leakage of fuel into oil n engine speed T fuel temperature pump efficiency Qleakkmi correction factor Qieakw corrected leakage of fuel into oil Kesic leakage coefficient depending on engine speed and fuel rail pressure Ap leakage pressure n engine speed v kinematic viscosity of fuel j number of cam lobes Qlealcmax maximum fuel leakage kmi current engine mileage kmthf engine mileage threshold Qie&new fuel leakage of a new fuel pump Q theoretical pump flowrate

Claims (8)

  1. CLAIMS1. Method of estimating a leakage of fuel into oil of an internal combustion engine (110), the internal combustion engine having a fuel pump (180) for pumping fuel to a fuel rail (170), the method comprising the steps of: -calculating a value of leakage into oil (Qicak) as a function of an engine speed value (n), a fuel rail pressure value (pnii), a fuel temperature value (T) and a pump efficiency value (rØ, -correcting the value of leakage into oil (QIeak) with a correction factor (OIeak_kmi), the correction factor depending on the engine ageing, to obtain a corrected value of leakage into oil (QIkwr).
  2. 2. Method according to claim 1, wherein said value of leakage into oil (Qeak) is calculated by means of the following equation: Qleak(Kleak x ap x j)I(n x v) where: Ken leakage coefficient depending on engine speed and leakage pressure leakage pressure n engine speed v kinematic viscosity of fuel number of cam lobes
  3. 3. Method according to any of the preceding claims, wherein said pump efficiency value () is calculated by means of the following equation: 11 (QteoQien new) I Qteo where: Qieaicj,ew fuel leakage of a new fuel pump theoretical pump flowrate
  4. 4. Method according to any of the preceding claims, wherein said correction factor (Qleak_kmi) is calculated by means of the following equation: Qiea'cjcmi = Qleaknlax x kmi / kmthr where: Q_m maximum fuel leakage kmi current engine mileage kmtj,r engine mileage threshold
  5. 5. Internal combustion engine (110) of an automotive system (100), the internal combustion engine having a fuel pump (180) for pumping fuel to a fuel rail (170), wherein a leakage of fuel into oil is estimated by a method of according to any of the preceding claims.
  6. 6. A computer program comprising a computer-code suitable for performing the method according to any of the claims 1-4.
  7. 7. Computer program product on which the computer program according to claim 6 is stored.
  8. 8. Control apparatus for an internal combustion engine, comprising an Electronic Control Unit (450), a data carrier (40) associated with the Electronic Control Unit (450) and a computer program according to claim 6 stored in the data carrier (40).
GB1318803.2A 2013-10-24 2013-10-24 Method of estimating a leakage of fuel into oil in an internal combustion engine Withdrawn GB2519554A (en)

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Citations (1)

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GB2501083A (en) * 2012-04-11 2013-10-16 Gm Global Tech Operations Inc Method of estimating fuel leakage into oil in an internal combustion engine

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2501083A (en) * 2012-04-11 2013-10-16 Gm Global Tech Operations Inc Method of estimating fuel leakage into oil in an internal combustion engine

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