JP2018536114A - Method and apparatus for operating an internal combustion engine, in particular a fuel dual injection internal combustion engine of an automobile - Google Patents

Abstract

The present invention calculates each fuel amount required for intake pipe type fuel metering and direct fuel metering based on the fuel distribution (440), and intake pipe type fuel metering and direct fuel metering. Operation of an internal combustion engine that performs a dual metering supply system based on the above and an exhaust gas recirculation (560) that is supplied again to the internal combustion engine via an inflow passage (535) of an intake pipe (505) when residual gas is generated during combustion Regarding the method, the heat of the recirculated residual gas is added to the fuel that is metered into the inflow passage (535) of the intake pipe (505) to adjust the fuel into the inflow path (535) of the intake pipe (505). Depending on the temperature rise caused by the heat of the recirculated residual gas of the fuel supplied, the fuel distribution is shifted to a higher proportion of intake pipe fuel metering (440).

Description

  The invention relates to a method and a device for operating a fuel dual injection internal combustion engine, in particular of a motor vehicle, as described in the superordinate concept of each independent claim. The invention further covers a computer program for carrying out the method according to the invention, a machine-readable data medium for storing the computer program, and an electronic control device for carrying out the method according to the invention. To do.

2. Description of the Related Art Fuel dual metering supplied by the present invention is a combination of intake pipe injection and direct injection or parallel operation when fuel metering is supplied to an internal combustion engine. In practice, it is known that such internal combustion engines can be configured as a dual system. This dual system can supply fuel to the same cylinder of the internal combustion engine using intake pipe injection (SRE) and direct fuel injection (BDE) in parallel according to the distribution in the mixed mode. . This distribution represents the division of fuel into the amount of fuel that can be supplied to the cylinder using intake pipe injection and the further amount of fuel that can be supplied to the cylinder using direct fuel injection. .

  For example, German Patent Application Publication No. 102010039434 (DE102010039434A1) describes that, in the above-described mixed mode, for example, the distribution of the internal combustion engine is determined in consideration of operating points such as load and / or rotational speed. . In this way, optimal operation of the internal combustion engine corresponding to different operating conditions can be achieved by the above-described mixing mode, with the distribution replaced according to the purpose each time. By utilizing the advantages of both injection systems, optimal mixture formation and combustion is possible. For example, the BDE is more advantageous when the internal combustion engine is in variable operation or at full load operation. This is because BDE can avoid obvious “knocking”. On the other hand, the use of SRE during the partial load mode of the internal combustion engine has the advantage of reducing exhaust gas contamination by particles and / or hydrocarbons (HC). This is because better mixture formation is performed based on the intake pipe length.

  Furthermore, an internal combustion engine in which residual gas generated during combustion is supplied again to the internal combustion engine using exhaust gas recirculation (EGR) is also known. Here, a distinction is made between internal residual gas (internal exhaust gas recirculation) and external residual gas (external exhaust gas recirculation). The internal residual gas remains in the upper dead space of each cylinder after combustion, or is sucked back into the above intake pipe when the intake valve and the exhaust valve are opened at the same time. The gas flows again into the combustion chamber, and the external residual gas is introduced into the intake pipe through the exhaust gas recirculation valve. This residual gas is composed of an inert gas, and is composed of unburned air in the lean mode, that is, when there is excess air. This inert gas component slows the progress of combustion, thereby causing a decrease in the combustion end temperature. Therefore, the emission of nitrogen oxides (NOx) can be reduced by this residual gas component. The point to be emphasized here is that the three-way catalyst cannot basically reduce nitrogen oxide when the air is excessive.

  Also, when the intake pipe pressure becomes lower than the ambient pressure during the intake stroke of the internal combustion engine, particularly when it becomes lower than the pressure in the piston return space, so-called “throttle loss” occurs. This is because each piston must operate against this pressure differential. Further, when the stagnation pressure is generated during the upward movement of the piston in the combustion chamber at the time of discharging the burned gas at a high rotation speed and a high load, a so-called “extrusion loss” occurs. In order to overcome this stagnation pressure, the piston must consume work against the stagnation pressure. As is well known, the throttle loss described above may occur when the throttle valve is open during the BDE mode and when the stratification mode is present, resulting in excessive air, or the fuel vapor-air ratio or In the homogeneous mode where the corresponding lambda value is 1 or less, a large amount of exhaust gas recirculation amount can be used, or can be reduced by increasing the exhaust gas recirculation amount. This is because the intake pipe pressure is increased, which in turn reduces the pressure difference produced in the piston correspondingly.

German Patent Application Publication No. 102010039434

DISCLOSURE OF THE INVENTION The present invention relates to a method and corresponding apparatus for fuel distribution in an internal combustion engine with internal and / or external exhaust gas recirculation (EGR) in fuel dual metering, which is the subject of the present invention. The basic recognition here is that when the internal combustion engine is not yet warmed up, for example during the start-up or during the start-up phase of the internal combustion engine, the evaporation of the fuel introduced into the inflow passage during the SRE mode is relatively poor. As a result, a fuel accumulation phenomenon or a fuel accumulation phenomenon occurs, and this phenomenon increases the proportion of unburned hydrocarbons in the exhaust gas. Similarly, during the BDE mode, the evaporation of the fuel directly introduced into the combustion chamber is relatively poor. As a result, the surface of the combustion chamber is wetted by the fuel, and eventually the number of particles in the exhaust gas is reduced. To increase.

  Another recognition that forms the basis of the present invention is that, especially in the case of high dynamic load switching to high loads, for example in rapid load switching from low loads to high loads, ie "transient mode". Means that if the internal combustion engine or the combustion chamber or piston is still too cold, the fuel will adhere to the surface of the combustion chamber by becoming a higher load point. This takes some time before the combustion chamber surface, including the piston surface, can take the temperature at the new or higher load point. The liquid film formed by adhesion does not evaporate at a sufficient rate and therefore does not burn completely, which ultimately increases the concentration of particles formed in the exhaust gas and / or Solid deposition will occur on the part. This can interfere with the function of the part or cause damage to the part. Further, it is difficult to directly measure the temperature of the combustion chamber or the temperature of the piston as is well known, or it cannot be performed unless significant technical effort and associated costs are applied.

  It should be noted here that the above-mentioned problem of fuel adhesion does not occur in the case of a high load point to a low load point.

  The basic idea of the method disclosed in the present invention is that the inflow of the inflow passage is increased by using the enthalpy or heat quantity of the exhaust gas recirculated to the intake system of the internal combustion engine by the above-mentioned EGR. The metered supply or the injected fuel is evaporated better. As a result, the piston and / or the combustion chamber surface is still too cold due to high load when the inflow passage is still cold during the starting phase of the internal combustion engine or due to the transient mode of the internal combustion engine. Even in this case, the distribution rate can be shifted to a higher proportion of the SRE fuel metering supply. Such a shift can significantly reduce particle emissions and unburned hydrocarbons in the exhaust gas.

  Furthermore, by the above, deposition on the combustion chamber surface and film formation is reduced or avoided, and in the above critical operating conditions, the oil lubrication film washing on the cylinder liner surface caused by the reduction of the BDE mode is performed. Flow is also effectively avoided, which significantly reduces, for example, piston ring and cylinder liner friction.

  The method according to the present invention is particularly useful in dual fuel metering with exhaust gas recirculation, which is the subject of the present application, and which again supplies residual gas formed during combustion to the internal combustion engine via the inlet passage of the intake pipe. Depending on the temperature rise caused by the heat of the recirculated residual gas of the fuel metered into the inflow passage of the fuel, the fuel distribution is shifted to a higher proportion of intake pipe fuel metering Furthermore, it is proposed to apply the heat of the recirculated residual gas to the fuel that is metered into the inflow passage of the intake pipe.

  Here, if it is determined that the internal combustion engine is in the cold start phase, or if the internal combustion engine is determined to be in a transient mode from low load to high load, the fuel distribution is increased to a higher percentage. It is possible to shift to intake pipe type fuel metering supply.

Furthermore, if it is determined that it is in the cold start phase, the temperature can be detected, which is advantageously
The temperature of the intake passage of the internal combustion engine,
·Outside air temperature,
The temperature of the internal combustion engine,
・ The oil temperature of the internal combustion engine,
-It is selected from the group of piston temperatures obtained using model calculation, and depending on the detected temperature, the maximum fuel amount for intake pipe type fuel metering supply (SRE) is obtained and the fuel directly The maximum amount of fuel that can be supplied for metering supply (BDE) is determined, the total amount of fuel to be metered is compared with the fuel amount determined above, and depending on the result of the comparison, It is also possible to replace the excess fuel amount caused by the corresponding increase in fuel metered by intake pipe fuel metering.

  In that case, all of the fuel metering supply during combustion chamber heating should be done by increased intake pipe fuel metering supply (SRE) or by increased fuel direct metering supply (BDE) It should be noted that the above-described piston temperature is particularly important for determining whether to do so. The reason for this is that when the piston is at a relatively low temperature, the intake pipe is increased in amount so that the wetting of the piston is relatively reduced by the formation (attachment) of the fuel liquid film as described above during the BDE mode. This is because system fuel metering (SRE) must be performed.

  Based on the fuel wall film model, how much fuel is deposited in liquid form on the wall film of the intake pipe, and how much fuel is liquidized from the wall film into the combustion chamber by the mass flow of intake air. It is possible to specify whether the gas flows out by evaporation, where the degree of fuel evaporation from the fuel wall film by the intake air and / or air-exhaust gas mixture depends on the temperature of the intake pipe and the thermal enthalpy. Suppose that it depends on the temperature and enthalpy of the intake air and / or air-exhaust gas mixture.

  Further, based on the piston temperature and / or combustion chamber wall temperature model, the accumulated fuel film evaporates or burns in time when the fuel is burned, so that the heat accumulated in the piston and / or combustion chamber wall of the internal combustion engine is reduced. It can also be determined whether it is sufficient.

  With the last two model calculations, the feasibility or operational safety of the method according to the invention can be further improved and, as a result, the above-mentioned exhaust gas values can be further improved.

  If it is not determined that the engine is in the cold start stage, it is possible to check whether the internal combustion engine is in the transient mode state. If it is determined that the engine is in the transient mode state, the intake pipe type fuel metering is performed. The proportion of fuel metered by supply is increased relative to the fuel metered by direct fuel metering.

  In addition, depending on the result of the above comparison, the above-described thermal action or heat input is further enhanced, thereby further increasing the appropriate ratio of exhaust gas recirculation in order to further enhance the above-described evaporation action. You can also. When the EGR ratio increases, the charge pressure and drive time of each of the one / plural intake valves are also adjusted appropriately to ensure the necessary filling of fresh air depending on the current operating point of the internal combustion engine. .

  Adaptation of the distribution rate in the direction of the SRE mode by using the enthalpy or heat input, i.e. the additional heat input to the intake system based on exhaust gas recirculation, to serve for fuel evaporation during the SRE mode as described above Or shift is possible. As a result, it is possible to improve the mixture preparation during the cold start phase or warm-up phase of the internal combustion engine and / or during the above-mentioned transient mode of the internal combustion engine.

  The fuel distribution can also be determined based on the measured or calculated temperature of at least one piston of the internal combustion engine, with the temperature of the at least one piston of the internal combustion engine being based on the transient mode. When it is determined or detected that the fuel has risen, the amount of fuel that is metered by direct fuel metering is gradually increased, and the amount of fuel that is metered by intake pipe fuel metering is gradually increased. Decrease. The basic recognition is that the influence of the piston temperature on the above-mentioned fuel adhesion phenomenon and / or fuel evaporation phenomenon or fuel removal phenomenon is remarkably large.

  As a result, during the above-mentioned (early) operation phase of the internal combustion engine, in addition to the mixing mode at a fixed mixing ratio, the mixing ratio of the both fuel metering and supplying systems is changed during operation of the internal combustion engine as described above. Dynamic or variable mixing modes can be changed. The calculation of each fuel metered through the two fuel metering systems required for this is advantageously carried out under control based on the above-mentioned temperature values or threshold values.

  Due to the above-mentioned adaptation or shifting of the distribution rate, the method according to the invention is during the cold start of the internal combustion engine which is the subject of the present application, of the fuel dual metering system using internal and / or external exhaust gas recirculation as described above. And / or during the transient mode, improved fuel evaporation over the prior art and concomitantly improved mixing preparation of the fuel-air mixture for combustion can be realized.

  The invention can be used in particular in a fuel dual injection system targeted by the invention for an internal combustion engine of a motor vehicle. Furthermore, for example, it can be used in the above-mentioned fuel dual injection type internal combustion engine used in the industrial field such as chemical process technology.

  The computer program according to the present invention is configured to carry out the steps of the above method, particularly when executed on a computing device or a control device. In the electronic control device, the method according to the present invention can be carried out without having to change the structure. In order to do this, a machine-readable data medium is provided, on which the computer program according to the invention is stored. By installing the computer program according to the present invention on the electronic control device, the electronic control device according to the present invention for controlling the fuel dual metering supply that is the object of the present invention using the method according to the present invention is realized. .

  Further advantages and embodiments of the invention can be derived from the description and the accompanying drawings.

  Of course, it should be understood that the features described above and below may not be used only in the combinations described, but may be used in other combinations or alone without departing from the scope of the present invention. It is.

1 is a schematic view of a conventional fuel dual injection device corresponding to a four-cylinder internal combustion engine. FIG. It is a schematic time chart of the fuel injection of a prior art at the time of fuel intake pipe injection. It is a schematic time chart of the fuel injection of a prior art at the time of fuel direct injection. 2 is a flowchart of an embodiment of a method according to the present invention. It is a figure which shows the exhaust gas recirculation system of the external ignition type internal combustion engine of the prior art which can apply or use the method which concerns on this invention.

Description of Embodiments The internal combustion engine shown in FIG. 1 includes four cylinders 11, which are covered by a cylinder head 12. The cylinder head 12 defines a combustion chamber 13 in each cylinder 11 together with a reciprocating piston guided in each cylinder 11, and this combustion chamber 13 is controlled by an intake valve (not shown). It has an inflow opening not shown. The reciprocating piston is not shown in the figure. The inflow opening forms a merging portion of an inflow passage penetrating the cylinder head 12, and this inflow passage is not shown in the figure.

  The fuel injection device in the figure includes an air flow path 18 for supplying combustion air to the combustion chamber 13 of the cylinder 11, and this air flow path 18 communicates with each inflow path on the terminal end side. And a plurality of mutually separated flow paths 17. Further, a first group fuel injection valve 19 that directly injects fuel into each combustion chamber 13 of the cylinder 11 and a second group fuel injection valve 20 that injects fuel into the flow path 17 are arranged. .

  Supply to the first group of fuel injection valves 19 that are directly injected into the cylinder 11 is performed by the fuel high-pressure pump 21, while supply to the second group of fuel injection valves 20 that are injected into the flow path 17 is This is performed by the fuel low pressure pump 22. The fuel low-pressure pump normally disposed in the fuel tank 23 pumps fuel from the fuel tank 23 to the second group of fuel injection valves 20 and the fuel high-pressure pump 21. The injection timing and injection duration of the fuel injection valves 19 and 20 are controlled depending on the operating point of the internal combustion engine by an electronic control unit incorporated in the engine control unit. Basically, the fuel injection is performed by the first group of fuel injection valves 19, and the second group of fuel injection valves 20 does not perform direct fuel injection by the first group of fuel injection valves 19 in a predetermined operation region. It is used only as a supplement to improve the sufficiency and to use a further degree of freedom or injection strategy.

  The second group of fuel injectors 20 is configured as a multi-jet injector that simultaneously discharges or injects at least two separate fuel jets that are angularly shifted from each other. These fuel injectors 20 are typically spray cones. The injected fuel jets 24 and 25 having the following shapes are arranged in the air flow path 18 so as to reach different flow paths. In the case of the internal combustion engine described above, two two-jet injection valves 26 and 27 are provided, and one two-jet injection valve 26 is injected into the flow path 17 communicating with the first and second cylinders 11. In addition, the two two-jet injection valves 26 and 27 are injected into the air passage 18 so that the second two-jet injection valve 27 injects into the passage 17 communicating with the third and fourth cylinders 11. Is placed inside. In order to do this, the flow path 17 is configured such that an assembly position for the two-jet injection valves 26 or 27 is formed between the two directly adjacent flow paths 17.

  In the above-described fuel intake pipe injection of the internal combustion engine to which the present invention is directed, it is also known that the air-fuel mixture is generated in the intake pipe outside the combustion chamber. Each injection valve injects fuel upstream from the intake valve, and the air-fuel mixture flows into the combustion chamber in the intake system through the opened intake valve. The fuel is supplied using a fuel pumping module, which pumps a required amount of fuel from the tank to the injection valve at a predetermined pressure. With the air control, an appropriate amount of air is supplied to the internal combustion engine at any operating point. An injection valve located in the fuel distributor accurately dispenses the desired amount of fuel into the air stream. The above-described engine control device controls the currently required air-fuel mixture based on the torque as the central reference amount. Effective exhaust gas purification is realized by lambda control for always controlling to the stoichiometric air-fuel ratio (λ = 1).

  In contrast, in the case of direct fuel injection, the air-fuel mixture is formed directly in the combustion chamber. Fresh air flows in through the intake valve described above, and fuel is injected into this air flow at a high pressure (typically in the vicinity of 300 bar or in the region of over 300 bar). This allows optimal vortex formation of the air fuel mixture and improved combustion chamber cooling.

  Further, in the case of a four-stroke internal combustion engine (gasoline engine), one operation cycle includes an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke, and each cylinder moves up and down twice and two top dead centers ( It is known to rest at OT) and two bottom dead centers (UT). Therefore, the crankshaft rotates twice in one operation cycle, and the camshaft rotates once. The ignition of the air-fuel mixture introduced into the cylinder is performed at the top dead center where the mixture is just compressed. This is referred to as ignition top dead center (ZOT). On the other hand, there is also a cross top dead center (UeOT). This is a top dead center where both the intake valve and the exhaust valve are open at the time of transition from the exhaust stroke to the intake stroke.

  According to this, ignition is performed at all top dead centers (OT) in at least one cylinder immediately after starting, and a crankshaft angle of 720 ° is set at a specific top dead center, especially every second top dead center. In each case, the ignition timing is shifted. Physical work performed in each cylinder depending on whether the air / fuel mixture is actually ignited at top dead center (OT) where the ignition timing shift occurs or at a crankshaft angle shifted 360 °. Can be identified.

  In FIG. 2, the y direction indicates the intake pipe injection performed at a plurality of different rotational speeds of the internal combustion engine with respect to the crankshaft angle (KW) measured in the unit [°]. As is known, the Otto engine type four-stroke combustion cycle includes a first bottom dead center (UT1), a first top dead center (OT), another bottom dead center (UT2), and another top dead center ( ZOT) includes the crankshaft angle at which the air / fuel mixture existing in the combustion chamber ignites.

  The above-mentioned temporal reference mark is set very differently for each of the two injection systems. For example, in intake pipe injection (SRE), as schematically illustrated in FIG. 2, if injection 200 is performed at four different rotational speeds n = 1000, 2000, 4000 and 7000 rpm, as an example only, Consider the constant time delay component 205 provided before the end 210 of the cycle 225. This is because, in the case of SRE, the injection valve is arranged outside each combustion chamber of the internal combustion engine, so that the fuel must first reach the combustion chamber from the injection position. The additional time required does not change when the rotational speed of the internal combustion engine changes or increases, as can be seen from FIG. Thus, in order to achieve a constant required time 205 at any number of revolutions, the injection is actuated at a correspondingly earlier time, for example at 7000 rpm or after the ignition performed in the preceding ZOT 220. Operate before UT1. The total injection period of the injection cycle in the drawing corresponds to the parenthesis 225 shown in the drawing as already described. 215 is attached to the next ZOT following the previous ZOT 220.

  On the other hand, in gasoline in-cylinder injection (BDE), a (specific) angle mark is experimentally set as a reference mark for each injection 300, as schematically shown in FIG. That is, unlike the SRE, in the BDE, for example, as can be seen from the transition 305 at the end of each injection, a constant time component is not considered. Therefore, in the BDE, the injection can be performed closer to the occurrence of ignition of the ZOT 315, and accordingly, the injection is calculated at a later time. In this embodiment, after the end 310 of the injection cycle 325 shown in the figure, ignition at the next ZOT 315 continues. The ignition timing before the ZOT 315 is the preceding ZOT 320.

Normally, exhaust gas composed of a combusted fuel vapor-air mixture contains water vapor and carbon dioxide (CO ₂ ) in particular. As a result, the heat capacity of the exhaust gas is significantly increased compared to the ambient air. Accordingly, the high-temperature exhaust gas is sent into the intake pipe of the internal combustion engine using the exhaust gas recirculation, whereby a relatively large heat flow is supplied to the intake passage. This heat flow causes the intake pipe inner wall to be quickly heated to a high temperature level, especially already during the start-up phase of the internal combustion engine.

  Furthermore, most of the metered fuel adheres to the inner surface of the intake pipe by the SRE injection process. The higher the inner surface, the faster the fuel introduced by the SRE injection process evaporates and the better the so-called “mixing preparation”, ie the better mixing of fuel vapor, air and recirculated exhaust gas. .

In the dual system described at the beginning, the above-mentioned two allocations, SRE allocation and BDE allocation, are combined in the form of a system or a system component as is well known. This requires in particular an accurate distribution of the total fuel mass that can be used or metered. The total fuel mass KM _ges per cylinder is configured as follows:
KM _ges = KM _SRE + KM _BDE
In the equation, KM _SRE represents the relative fuel mass of the SRE system, and KM _BDE represents the relative fuel mass of the BDE system. Hereinafter, a corresponding processing flow for calculating or allocating the fuel mass required at the time of injection in the dual system will be described with reference to the flowchart shown in FIG.

  After the routine start 400 shown in the figure, it is first checked 405 whether the internal combustion engine is in the cold start phase or has not yet warmed up to the operating temperature. If this condition is not met, it is further checked 407 whether the internal combustion engine is operating in the low load to high load transient mode described above. If both conditions 405 and 407 are not satisfied, the routine ends 410.

If the result of the inspection step 405 shows that it is in the cold start phase, it first detects at least one temperature value using a self-evident sensor system, and
The temperature of the intake passage of the internal combustion engine,
·Outside air temperature,
The temperature of the internal combustion engine,
・ The oil temperature of the internal combustion engine,
Detecting 415 at least one temperature value in the group of piston temperatures determined using the model calculation;

  Based on the temperature value 415 thus detected, a maximum fuel amount for the SRE mode that causes sufficient evaporation of the metered fuel during the SRE mode at the current temperature is determined 420. In that case, based on the fuel wall film model, how much fuel is deposited in liquid form on the wall film of the intake pipe and how much fuel flows out of the wall film by the intake mass flow. Then, it is specified whether the gas flows out of the wall film in a gaseous state by evaporation. The degree of fuel evaporation from the fuel wall film by the intake air and / or air-exhaust gas mixture depends on the temperature and heat enthalpy of the intake pipe and the temperature and heat enthalpy of the intake air and / or air-exhaust gas mixture .

  The parameters relevant for evaporating the fuel present in the intake pipe wall as described above are mainly the following: intake pipe temperature, intake air temperature, gas density, turbulence, and air flow velocity, and thus The engine speed and the valve control time of the intake valve described above. The reason is that the higher the flow velocity and turbulence in the intake pipe, the better the fuel adhering to the wall can be evaporated, and the less the amount of fuel adhering or accumulating on the wall film.

  In addition, the limit of fuel deposition on the wall film that does not cause unwanted fuel accumulation phenomena is also calculated. In this case, it should be noted that the fuel accumulation described above is the amount of liquid fuel that collects directly in the closed intake valve, unlike the fuel deposition that forms the wall film. Based on the difference between the actual value of fuel deposition and the aforementioned maximum limit of fuel deposition, an amount by which the intake pipe injection amount can be increased is calculated. This includes a shift in the injection amount split between direct injection and intake pipe injection.

  Further, 425 determine the maximum amount of fuel that can be supplied during the BDE mode, where the resulting particle emissions are still within acceptable limits. Further, in the present embodiment, based on the piston temperature and / or combustion chamber wall temperature model, the attached fuel film that wets the piston recess or the combustion chamber wall can still evaporate and burn at the appropriate time during the main combustion. Therefore, it is determined whether the heat accumulated on the piston or the combustion chamber wall is sufficient. Otherwise, if the evaporation is too slow, and if the combustion is too slow, the lack of oxygen after the main combustion will cause unwanted particle formation in the exhaust gas, and may also occur on the combustion chamber surface, such as the piston surface Film formation and carbonization occur.

  Therefore, a sudden change from the low load point to the high load point typically involves an increase in the injection amount and an increase in the combustion temperature. In the case of such a sudden fluctuation of the load, for example, the piston is still at the previous or lower temperature level due to the thermal inertia, so that the above-mentioned adhesion phenomenon is further amplified and the end temperature corresponding to the current load is reached. Amplifies until the piston reaches.

  Here, for example, the total amount of fuel to be supplied or injected 430 output from the control device is compared with the above-mentioned maximum amounts 435. If the comparison 435 indicates that the total fuel amount 430 to be metered is greater than the sum of both maximum amounts, the excess fuel amount corresponding to this is determined by the amount of fuel metered during SRE mode. It is replaced by a corresponding increase 440 and an appropriate ratio increase 445 of external EGR recirculation that can also ensure that the additional amount of fuel metered by the SRE can also evaporate.

  The underlying technical action is to heat the intake pipe surface and the fuel vapor-air mixture because the recirculated exhaust gas has a high thermal enthalpy due to its high temperature and water vapor content. Such heating improves the evaporation of the liquid fuel (e.g. so-called wall film and / or fuel spray) adhering in the suction passage. If the above mentioned relative increase of the intake pipe injection amount relative to the total fuel amount to be injected is not sufficient for that purpose, the exhaust gas recirculation rate can be increased, thereby increasing the amount by which the intake pipe injection amount evaporates. . Depending on the corresponding injection time of the intake pipe injection valve, the opening time and / or stroke of the intake valve can also be increased.

  Each of the above models describes the underlying physical relationship, for example using parameter formulas and / or characteristic curves / characteristic maps, or using numerical methods (eg trivial Gaussian methods). ing. Corresponding parameters and characteristic curves / characteristic maps can be pre-datad on the test bench. The numerical model described above can be trained, for example based on the desired initial behavior of one or more initial quantities of the input quantity to be affected. The model data trained in this way can be stored in the control device, and each model can be calculated based on this model data during operation of the internal combustion engine or vehicle.

  The point to be noted here is that, for example, in an operating state or a traveling state in which the piston temperature gradually increases after a sudden change in load, the ratio of the BDE amount to the entire metering supply is also gradually increased to the target value. To gradually reduce the SRE amount and / or the exhaust gas recirculation rate to the target value. These target values are values of the fuel amount distribution to be applied after the end of the piston heating phase, and correspond to the values stored for the steady operation of the internal combustion engine in an appropriate characteristic map.

  It should also be noted that the increase 440 described above is advantageously performed by adapting or changing the distribution or distribution ratio described above.

  If it is not determined that the engine is in the cold start phase, or if the internal combustion engine is determined to be in the above-described transient mode state in the above-described inspection step 407 in the case where it is not in the cold start phase, the intake air is determined in the next step 440. Unless the amount of heat present in the tube is sufficient to evaporate the fuel that is additionally metered during SRE mode, the ratio of fuel relative to BDE mode metered by SRE mode is increased. And the external EGR recirculation rate is also increased 445 as described above.

  It should also be noted that the flowchart shown in FIG. 4 should be applied continuously. For example, when the method described with reference to FIG. 4 is applied, when the piston is heated during the transient mode described above, and when the load suddenly fluctuates (abrupt from low load to high load). In the case of (variation), the above-mentioned EGR measures and / or the above-mentioned increased SRE injection must again be gradually reduced or returned.

  In the EGR system to which the above-described method shown in FIG. 5 can be applied, air and fuel vapor are supplied to the intake pipe 505 through the supply path 500 as is well known. One end 510 of the supply channel 500 communicates with a trivial fuel evaporative storage system (not shown in the figure). A regeneration valve 515 having a variable valve opening cross-sectional area is disposed in the supply channel 500.

There is a throttle valve 520 in the intake pipe 505 as is well known, and the throttle valve 520 can be used to adjust the air supplied to the combustion chamber 525 of the internal combustion engine over the adjustment angle α. Therefore, the upstream of the throttle valve 520, there is an air mass flow 530 near pressure p _U, in the region of the inlet passage 535 downstream of the throttle valve 520, air mass flow, having an intake pipe pressure p _s. The cylinder of the internal combustion engine shown in the figure includes a piston 540, an intake valve 545, and an exhaust valve 550, as is well known. The exhaust gas exhausted through the exhaust valve 550 is sent to an obvious exhaust gas system (not shown) through the outflow passage 565.

  An exhaust gas recirculation path (EGR path) 560 is disposed between the outflow passage 565 and the inflow passage 535, and the exhaust gas recirculated in the exhaust gas recirculation path (EGR path) 560 is combusted in the combustion chamber 525 or the combustion chamber. Supplied again. The recirculation rate or EGR rate can be adjusted using an exhaust gas recirculation valve (EGR valve) 555 having a variable valve opening cross-sectional area, or can be controlled by open loop control or closed loop control.

  The method can be realized in the form of a control program for an electronic control device for controlling an internal combustion engine or in the form of one or more corresponding electronic control units (ECUs).

Further, based on the piston temperature and / or combustion chamber wall temperature model, the accumulated fuel film evaporates or burns in time when the fuel is burned, so that the heat accumulated in the piston and / or combustion chamber wall of the internal combustion engine is reduced. It can also be specified whether or not it is sufficient.

Further, 425 determine the maximum amount of fuel that can be supplied during the BDE mode, where the resulting particle emissions are still within acceptable limits. Further, in the present embodiment, based on the piston temperature and / or combustion chamber wall temperature model, the attached fuel film that wets the piston recess or the combustion chamber wall can still evaporate and burn at the appropriate time during the main combustion. Therefore, it is specified whether the heat accumulated in the piston or the combustion chamber wall is sufficient. Otherwise, if the evaporation is too slow, and if the combustion is too slow, the lack of oxygen after the main combustion will cause unwanted particle formation in the exhaust gas, and may also occur on the combustion chamber surface, such as the piston surface Film formation and carbonization occur.

Claims (15)

A fuel amount required for each of intake pipe type fuel metering and direct fuel metering is calculated based on the fuel distribution (440), intake pipe type fuel dual metering and direct fuel metering,
Exhaust gas recirculation (560) for supplying residual gas formed during combustion to the internal combustion engine again via the inflow passage (535) of the intake pipe (505);
In the operating method of the internal combustion engine,
Heat of the recirculated residual gas is added to the fuel that is metered into the inflow passage (535) of the intake pipe (505), and the inside of the inflow passage (535) of the intake pipe (505) Depending on the temperature rise caused by the heat of the recirculated residual gas of the fuel metered into the fuel, the fuel distribution is shifted to a higher proportion of intake pipe fuel metering (440)
An operation method characterized by that. Using the heating of the inflow passage (535) of the intake pipe (505) increased based on the amount of heat of the recirculated residual gas, the supply was metered by the intake pipe type fuel metering supply Evaporate the fuel,
The operation method according to claim 1. When it is determined that the internal combustion engine is in a cold start phase (405) or when the internal combustion engine is determined to be in a transient mode from low load to high load, the fuel distribution is increased to a higher percentage. Shift to intake pipe fuel metering (440),
The operation method according to claim 1. If it is determined that it is in the cold start phase (405), the temperature is detected (415),
Depending on the detected temperature (415), a maximum fuel amount for the intake pipe fuel metering supply is determined (420);
Determining the maximum amount of fuel that can be supplied for direct fuel metering (425);
A comparison is made between the total amount of fuel to be metered (430) and the determined amount of fuel (420, 425) (435),
Depending on the result of the comparison (435), the excess amount of fuel produced in some cases is replaced (440) by a corresponding increase in the fuel metered by the intake pipe fuel metering.
The operation method according to claim 3. Based on the fuel wall membrane model, the degree of fuel evaporation from the fuel wall membrane by the intake air and / or air-exhaust gas mixture is determined by the temperature and thermal enthalpy of the intake pipe (505) and the intake air and / or air- Assuming that it depends on the temperature and thermal enthalpy of the exhaust gas mixture, how much fuel is deposited in liquid form on the wall film of the intake pipe (505) and how much fuel is on the wall film. To determine whether it flows into the combustion chamber in a liquid state by the mass flow of the intake air and / or in a gaseous state by evaporation from the wall film,
The operation method according to claim 3 or 4. Based on the piston temperature and / or combustion chamber wall temperature model, the heat accumulated in the piston and / or combustion chamber wall of the internal combustion engine is used to evaporate and burn the deposited fuel film in a timely manner during the combustion of the fuel. Determine whether it is enough,
The operation method according to claim 3 or 4. The increase (440) is performed by a change in the fuel distribution between the intake pipe fuel metering supply and the fuel direct metering supply.
The operation method according to any one of claims 4 to 6. The temperature detected (415) is
The temperature of the intake passage of the internal combustion engine,
Outside air temperature,
The temperature of the internal combustion engine,
Oil temperature of the internal combustion engine,
Selected from the group of temperatures determined using model calculations of at least one piston of the internal combustion engine;
The operation method according to any one of claims 4 to 7. If it is not determined that it is in a cold start phase, check whether the internal combustion engine is in a transient mode state;
When it is determined that the engine is in the transient mode state, the proportion of fuel metered by the intake pipe fuel metering supply is increased relative to the fuel metered by the fuel direct metering supply. (440),
The operation method according to any one of claims 1 to 3. Depending on the result of the comparison (435), an appropriate ratio increase of the exhaust gas recirculation (560) is additionally performed (445),
The operation method according to any one of claims 4 to 9. Determining the fuel distribution based on a measured or calculated temperature of at least one piston of the internal combustion engine;
The operation method according to any one of claims 1 to 10. When it is determined or detected that the temperature of the at least one piston of the internal combustion engine has increased based on the transient mode, the amount of fuel metered by the direct fuel metering is gradually increased, and the intake air Gradually reduce the amount of fuel metered by pipe fuel metering,
The operation method according to claim 11.   A computer program configured to carry out the steps of the operating method according to any one of claims 1-12.   A machine-readable data medium storing the computer program according to claim 13.   An electronic control device configured to control fuel dual metering using the method of operation according to any one of claims 1-12.

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