CN107084062A - Method and apparatus for running the internal combustion engine sprayed with dual fuel - Google Patents

Abstract

The invention relates to a method and a device for operating an internal combustion engine with dual intake-pipe-based fuel dosing and direct fuel dosing, wherein the quantity distribution calculation is used for the intake-pipe-based fuel dosing and for the direct fuel dosing respectively required fuel quantity, and the internal combustion engine also has a variable compression of the fuel/air mixture in at least one combustion chamber of the internal combustion engine, wherein it is provided, in particular, to detect (405, 410) the current operating conditions of the internal combustion engine, including the currently existing Compression ( 405 ) and determination ( 420 ) of values assigned to said quantities in relation to detected operating conditions.

Description

Method and device for operating an internal combustion engine with dual fuel injection

technical field

The invention relates to a method and a device for operating an internal combustion engine with a double fuel distribution and variable compression of a fuel/air mixture in a combustion chamber. The subject of the invention is also a computer program, a machine-readable data carrier for storing the computer program, and an electronic controller by means of which the method according to the invention can be carried out.

Background technique

In the dual fuel distribution mentioned here, intake manifold injection and direct injection are coupled or run in parallel in the fuel distribution of the internal combustion engine. It is known from practice that such internal combustion engines can be configured as a dual system, in which mixed operation the fuel can be distributed in parallel by means of intake manifold injection (SRE) and by means of fuel or fuel direct injection (BDE) Delivery to the cylinder block of the internal combustion engine. In this case, the distribution quantity indicates that the fuel is divided into a fuel quantity that can be delivered to the cylinders by means of intake manifold injection and a further fuel quantity that can be delivered to the cylinders by means of direct fuel injection.

It is described, for example, in DE 10 2010 039 434 A1 that the allocation of the internal combustion engine in the described mixed operation is determined taking into account the operating point, for example the load and/or the rotational speed. This mixed operation of the individually implemented distribution quantities thus allows optimum operation of the internal combustion engine for different operating conditions. Optimum mixture formation and combustion is achieved by taking advantage of the advantages of both injection modes. BDE is therefore more advantageous during dynamic operation of the internal combustion engine or during operation under full load, since the known self-ignition of the combustion chamber charge (so-called “knock”) can thereby be avoided. On the other hand, during SRE, the exhaust gas loading with particles and/or hydrocarbons (HC) is advantageously reduced during part-load operation of the internal combustion engine.

The knocking control is used to suppress or avoid the aforementioned knocking by incrementally shifting the ignition timing that is carried out when knocking is detected backwards and then returning to the previous ignition timing. The earliest possible ignition time is determined here using the standard fuel and stored in the characteristic map. As a result, the time course of the combustion can be thermodynamically optimized.

Also known from DE 102 58 872 A1 is an internal combustion engine without a so-called dual fuel distribution but with variable compression or a variable compression ratio of the fuel/air mixture in the combustion chamber or cylinder, in which In this, the position of the crankshaft can be variably adjusted by means of a number of eccentric rings which can be twisted relative to the motor block by means of an adjustment mechanism, so that the so-called "compression volume" and thus also the compression ratio can be varied. As an alternative to the adjustment mechanism, the compression ratio can also be changed by tilting the motor block relative to the crankshaft bearing arrangement or by tilting the cylinder head relative to the motor block or by lifting or lowering the cylinder head relative to the motor block.

Variable compression can also be achieved by camshaft adjustment (phasing) by means of a camshaft phaser or by cam switching by means of a variable valve drive. The compression can also be varied by varying the closing time of an inlet valve arranged on the cylinder block of the internal combustion engine.

Due to the described variable compression, the thermodynamic efficiency can be increased during combustion in the partial load range, thereby resulting in energy consumption advantages and a reduction in CO 2 emissions. However, with an increase in the compression ratio, the final compression temperature also increases, wherein, with an increase in the final compression temperature, the knocking tendency increases again. Therefore, the maximum possible compression ratio is limited by the fuel's propensity to knock. As the rotational speed increases and the load decreases, the tendency to knock is reduced and thus a higher compression can be selected.

Contents of the invention

The invention relates to a method and a corresponding device for fuel distribution in the case of the dual fuel distribution mentioned here of an internal combustion engine with the described variable compression (compressed air) of the fuel/air mixture in the combustion chamber of the internal combustion engine ). This is based on the knowledge or technical effect that the said direct fuel in the knock-limited operating range with an earlier and therefore more fuel-friendly fuel mass conversion The BDE fuel injection system can be operated as a fuel injection system with intake manifold-based fuel distribution (SRE), because in BDE operation the center of gravity of the combustion can be selected, which can be adjusted or controlled via the ignition angle or via the ignition timing earlier than in SRE.

The invention is based here on the recognition that the type of fuel distribution used, that is to say the described BDE operation or the SRE operation, or a combination of both with the stated quantity distribution, has a significant influence on the fuel distribution during combustion. The detonation characteristics described above have a huge influence and thus provide a large latitude for reducing fuel consumption and reducing combustion-induced exhaust emissions.

The real technical cause of this effect is that the tendency to knock in BDE operation can be reduced compared to SRE operation by virtue of the combustion of the fuel directly in the combustion chamber and by means of fuel particles injected or The increased turbulence of the fuel droplets, created by the kinetic energy introduced by the BDE operation, undergoes enhanced and thus faster cooling of the mixture. This effect is firstly thermodynamically favorable during operation of the internal combustion engine at higher loads and in particular leads to lower fuel consumption.

The method according to the invention is based on the solution that, on the basis of the current operating point of the internal combustion engine, the current compression ratio ε (ipsilon), the ambient conditions and/or the early stage of the previous or last combustion, a determined Suitable or even optimal values for the distribution of said amounts. In this case, the described possible advantages in SRE operation with regard to mixture preparation are combined with the described advantages of the higher knock insensitivity of BDE operation. The described early conditions of the final combustion also include the current and/or previous transient behavior or the behavior of the internal combustion engine or the injection system during transient operation, that is to say, for example, a sudden torque request caused by the driver's intention or Sudden load switching.

The method according to the invention proposes in particular to adjust the distribution of the dosed fuel between the intake-pipe-based fuel distribution (SRE) and the direct fuel distribution (BDE) as a function of the present variable compression or compression. Preferably, in the presence of higher compression and simultaneously higher load, the quantity distribution is shifted in the direction of a relatively higher BDE metering and the ignition angle is additionally set further forward. The technical effect described here is based on the fact that in BDE operation the knock limit can be shifted forward, whereby the efficiency of the combustion can be advantageously increased in current knock-limited operation. In this case, the ignition angle is preferably not adjusted forward, but an inefficient backward adjustment of the ignition angle for reducing knocking can be dispensed with, so that the motor can be operated in an optimum operating point.

It should be noted here that, in the present invention, the technical details when realizing the variable compression ratio are not important, and the method according to the invention can therefore use all aspects of variable compression with the advantages described here. in practice where technically possible.

In particular, it is provided in the method according to the invention that the current compression or air pressure is detected (eg read out by the motor controller) and the current load state of the internal combustion engine is detected (eg also read out by the controller). If the two detected values of compression and load in this way exceed empirically predeterminable threshold values, the quantity distribution is changed in the direction of a relatively higher BDE fuel distribution.

As an alternative to a discrete calculation or adaptation of the volume distribution based on the threshold value, a continuous calculation or adaptation of the volume distribution can also take place, more precisely in relation to the compression ratio. Corresponding values, for example optimal values for the quantity distribution, can be stored in corresponding characteristic maps here, more precisely in relation to compression, rotational speed, load, etc.

In the comparison of the detected compression and load for the operation of the internal combustion engine, relevant ambient conditions such as the motor and/or intake air temperature can additionally be taken into account, since these operating parameters have a significant influence on the knock behavior of the internal combustion engine.

Furthermore, the method according to the invention can be used for the respective failure analysis of the cylinders. If, for example, irregular changes in the compression are present in all cylinders at the same time, it can be concluded that, for example, the adjustment mechanism for the variable compression mentioned at the outset is defective. On the other hand, if irregular deviations in the compression ratio ε occur only in one cylinder, it can be concluded that the gas exchange valve and/or the piston ring are leaking, for example, on the relevant cylinder.

In the method according to the invention it can also be provided that the knock behavior of the internal combustion engine is optimized in relation to different operating states of the internal combustion engine or the injection system, the quantity distribution, the indicated early behavior of the combustion and/or the (variable) compression values are stored in characteristic maps, reference characteristic maps, application reference characteristic maps, etc. The values stored there can be learned in a manner known per se by suitable algorithms during operation of the internal combustion engine. As a result, in the case of the described fault, the quantity distribution or the corresponding distribution factor ("split factor") can react quickly or counteract the corresponding fault state while taking into account the knock limit.

Alternatively or additionally, the currently existing compression ratio during operation can be directly derived by simply comparing the currently determined knock limit during continuous operation of the internal combustion engine with the (reference) value stored in the characteristic map. ε. This is based on the idea that a change in the throughput distribution or a corresponding distribution factor can determine the compression ratio.

The values of the knock limit and the distribution factor at the operating point can be stored in the characteristic map as a function of the compression. If one now ascertains the knock limit by means of the variation of the distribution factor, the current or actually existing compression can be deduced by comparing the expected knock limit with the knock limit determined in this way.

With the described procedure for determining the compression ratio ε, the diagnostic function for the variable compression described can be implemented either cyclically, for example once per operating cycle, or only when required, for example Performed when there are combustion problems such as knocking or combustion interruption.

The proposed adaptation or shifting of the distribution factor thus enables the method according to the invention to achieve the operation of the internal combustion engine mentioned here with a dual fuel distribution that is less knock-prone than in the prior art. The combination of the advantages of variable compression and variable fuel distribution results in overall lower consumption, lower exhaust emissions and better driving or operating comfort. As already mentioned, the SRE operation contributes here to a better mixture preparation and the BDE operation contributes to a higher knock insensitivity.

The calculation according to the invention of the two fuel quantities for the intake-pipe-based fuel distribution and for the direct fuel distribution is preferably carried out for each cylinder of the internal combustion engine, that is, continuously or successively .

The invention can be used in particular in the dual fuel injection system mentioned here of an internal combustion engine of a motor vehicle. Furthermore, it can also be used in the industrial field, for example in internal combustion engines with such dual fuel injection used in chemical process technology.

The computer program according to the invention is provided to carry out the individual steps of the method, in particular when the computer program is run on a computer or controller. This makes it possible to carry out the method according to the invention on an electronic controller without having to make structural changes on this electronic controller. For this purpose, a machine-readable data carrier is provided on which the computer program according to the invention is stored.

By running the computer program according to the invention on the electronic controller, an electronic controller according to the invention is obtained which is provided for using the method according to the invention in a The dual fuel distribution mentioned here is controlled in the internal combustion engine.

Other advantages and design solutions of the present invention can be obtained from the specification and drawings.

Of course, the features mentioned above and those still to be explained below can be used not only in the respectively stated combination but also in other combinations or on their own without departing from the framework of the present invention.

Description of drawings

FIG. 1 schematically shows a dual fuel injection system for a four-cylinder internal combustion engine according to the prior art;

Fig. 2 schematically shows the time course of fuel injection when the fuel intake pipe is injected according to the prior art;

FIG. 3 schematically shows the time course of the fuel injection during direct fuel injection according to the prior art;

FIG. 4 shows an embodiment of the method according to the invention by means of a flowchart;

FIG. 5 shows an exemplary embodiment of a (reference) characteristic map according to the invention, which contains previously determined data on the knock behavior of the internal combustion engine as a function of various operating states of the internal combustion engine or the injection system.

detailed description

The internal combustion engine shown in FIG. 1 has four cylinder blocks 11 which are covered by cylinder heads 12 . The cylinder head 12 delimits a combustion chamber 13 in each cylinder block 11 together with a reciprocating piston guided in the cylinder block 11 , not shown here, which has an inlet 15 controlled by an inlet valve 14 . The inlet 15 forms a junction of a feed channel 16 through the cylinder head 12 .

The fuel injection system shown comprises an air flow path 18 for supplying combustion air to the combustion chamber 13 of the cylinder block 11 , which has flow channels separated from one another at the end sides to the individual feed channels 16 17. In addition, a first group of fuel injection valves 19 that inject fuel directly into each of the combustion chambers 13 of the cylinder block 11 and a second group of fuel injection valves 20 that inject fuel into the flow passage 17 are provided.

The fuel injection valves of the first group 19 , which inject directly into the cylinder block 11 , are supplied by the high-pressure fuel pump 21 , while the fuel injection valves of the second group 20 , which inject into the flow passage 17 , are supplied by the low-pressure fuel pump 22 . A low-pressure fuel pump, which is usually arranged in the fuel tank 23 , delivers fuel from the fuel tank 23 on the one hand to the second group of fuel injection valves 20 and on the other hand to the high-pressure fuel pump 21 . The injection times and injection durations of the fuel injection valves 19 , 20 are controlled by an electronic control unit integrated in the motor controller as a function of the operating point of the internal combustion engine, wherein the fuel injection is essentially via the fuel injection valves 19 of the first group Complete, and the fuel injection valves of the second group 20 are only used supplementarily in order to improve the insufficiency of direct fuel injection and to utilize additional degrees of freedom or injection strategies via the fuel injection valves of the first group 19 in a certain operating range.

The fuel injectors 20 of the second group are designed as multi-jet injectors which simultaneously inject or inject at least two separate fuel jets which are angularly offset from one another and which are arranged in the air flow path 18 in such a way that the injected The fuel jets 24, 25, usually in the form of conical sprays, reach different flow channels. In this internal combustion engine there are two double-jet injection valves 26 , 27 which are arranged in the air flow path 18 in such a way that a double-jet injection valve 26 injects into the flow channel 17 leading to the first and second cylinder 11 And the second dual-jet injection valve 27 injects into the flow channel 17 leading to the third and fourth cylinder 11 . For this purpose, the flow channels 17 are designed such that there is an insertion point for the dual jet valve 26 or 27 between two directly adjacent flow channels 17 .

It should be noted that, in the internal combustion engine shown in FIG. 1 , one (shown) fuel injection valve 19 and one (here only two shown here) dual Beam injection valves 26,27.

It is also known that an air-fuel mixture is generated outside the combustion chamber in the intake tract during the described fuel intake manifold injection of the internal combustion engine mentioned here. The individual injection valves inject fuel upstream of the inlet valves, wherein the mixture flows into the combustion chamber in the intake system via the open inlet valves. The fuel supply takes place by means of a fuel delivery module, which delivers the required quantity of fuel at a defined pressure from the tank to the injection valve. Air Control is responsible for supplying the combustion engine with the correct air quality at every operating point. Injection valves arranged on the fuel distributor precisely dose the desired fuel quantity into the air flow. The motor controller regulates the respective required air-fuel mixture on the basis of the torque as a central reference variable. Effective exhaust gas cleaning is achieved with lambda regulation, by means of which the stoichiometric air-fuel ratio (λ=1) is always set.

Accordingly, with direct fuel injection, an air-fuel mixture is formed directly in the combustion chamber. Here, fresh air flows in via the inlet valve, fuel being injected into this air flow at high pressure (typically 200 bar). This achieves an optimal swirl of the air-fuel mixture and better cooling of the combustion chamber.

It is also known that in a four-stroke internal combustion engine (gasoline motor), the working cycle includes the processes of suction, compression, work, and exhaust, wherein each cylinder moves up and down twice and here in two Standstill at top dead center (OT) and both bottom dead centers (UT). The crankshaft thus performs two revolutions and the camshaft one revolution in one working cycle. Ignition of the gas-fuel mixture brought into the cylinder takes place at top dead center, where the mixture is just compressed. Here one refers to ignition top dead center (ZOT). Correspondingly, there is an overlapping top dead center (ÜOT) in which both the inlet valve and the outlet valve are opened during the transition from exhaust to intake.

The ignition is therefore carried out directly after start-up at least in the cylinder at all top dead center (OT), wherein at a specific top dead center, especially at every second top dead center, at a crankshaft angle of 720° , and respectively perform each one movement of the ignition timing. Depending on whether the air-fuel-mixture is actually ignited at top dead center (OT) (where the ignition timing shift is performed) or at a crankshaft angle shifted by 360°, the amount of physical work performed in each cylinder can be concluded reduce.

In FIG. 2 , the y-direction represents the intake manifold injection at different rotational speeds of the internal combustion engine over the crankshaft angle (KW) measured in the unit "degrees". The four-stroke combustion cycle according to the gasoline motor principle is well known to include a first bottom dead center (UT1), a first top dead center (OT), another bottom dead center (UT2) and another top dead center (ZOT). crank angle,

At this crank angle, the air-fuel mixture present in the combustion chamber is ignited.

The mentioned time reference marks are predetermined very differently for the two injection paths. Therefore, in the intake manifold injection (SRE), as shown schematically in FIG. 2 , when injecting 200 at only four different rotational speeds n=1000, 2000, 4000 and 7000 U/min, for example, it is considered that A constant time delay portion 205 is reached before the end 210 of the injection cycle 225 , since the injection valves are arranged at SRE outside the respective combustion chamber of the internal combustion engine and the fuel must therefore first enter the combustion chamber from the injection point. As can be seen in FIG. 2 , this additional time requirement does not change when the rotational speed of the internal combustion engine is changed or increased. The injection is thus triggered correspondingly earlier, e.g. at 7000 U/min even before UT1 after the previous ignition in the previous ZOT 220, thus providing a constant time at all speeds Requires 205. The injection window for the total time of the indicated injection cycle corresponds, as already mentioned, to the brackets 225 drawn. The next ZOT following the previous ZOT 220 is labeled with reference numeral 215 .

In contrast, in the case of gasoline direct injection (BDE), in each injection 300 a (specific) angle marker is predetermined empirically as a reference marker, as schematically shown in FIG. 3 . This means that, in contrast to SRE, in BDE no constant time fraction is taken into account, as can be seen, for example, from the course 305 of the end of the individual injections. In this case, the injection can therefore take place close to the ignition event of ZOT 315 and thus the calculation can be carried out at a correspondingly later time. In the present example, the end 310 of the injection cycle 325 shown here is followed by ignition at the next ZOT 315 . The moment of ignition prior to this ZOT 315 occurred at the preceding ZOT 320 .

The internal combustion engine mentioned here also includes the variable compression described in said DE 102 58 872 A1, during which the crankshaft

The eccentric ring is mounted in the motor housing by means of an eccentric ring, which is itself rotatably mounted in a carrier bearing in the motor housing. The eccentric ring can be turned in a controlled manner by means of an adjustment mechanism so that the position of the crankshaft relative to the motor block changes. The position of the piston in the cylinder of the internal combustion engine and the position of the so-called top dead center (OT) of the piston in the cylinder thus change, as does the compression volume VC contained through said piston in the piston top dead center position . Because the bottom dead center position of the piston changes accordingly, the stroke volume VH does not change as the crankshaft position changes relative to the motor block. Thus a change in the compression volume at a constant stroke volume VH implies a change in the compression ratio ε = (VH + VC)/VC.

Through variable compression, it is possible to increase thermodynamic efficiency during combustion in the part load range. As a result, consumption advantages and reductions in CO2 emissions can be achieved. The higher the compression ratio, the higher the compression end temperature, wherein, as the compression end temperature increases, the risk of the combustion chamber charge itself igniting (knocking) in gasoline motors also increases, so the maximum possible compression ratio is limited by the knocking of the fuel Tendency to limit.

In the case of the dual system mentioned here for the fuel distribution system, the two components described, that is to say the SRE component and the BDE component, are known to be combined in the form of systems or system components. Here, in particular, the correct distribution of the total fuel mass to be supplied or to be metered is required. The total fuel mass KMges for one cylinder consists of:

,

where KM _SRE refers to the associated fuel mass for the SRE path and KM _BDE refers to the associated fuel mass for the BDE path. The corresponding sequence for calculating or distributing the required fuel mass for injection in such a dual system is explained below with the aid of the flow chart shown in FIG. 4 .

In the exemplary embodiment, the routines described next are executed continuously or successively for all cylinders of the internal combustion engine, more precisely for the i-th cylinder in the present case.

After the start 400 of the program, the current value of the compression 405 and the load 410 are checked. Further combustion-determining variables are additionally detected, in particular currently prevailing ambient conditions such as air pressure and/or air temperature, and are taken into account in subsequent steps. In a step 415 it is checked whether the detected compression 405 and at least one other detected variable 410 , currently the load, exceed threshold values predetermined empirically in each case in the preparation phase. These threshold values are determined in such a way that the described knocking during combustion is effectively avoided. If this condition is not met, then jump back to the beginning of the program.

It should be noted here that, as an alternative to the described discrete adaptation, a continuous adaptation is also possible.

But if the condition 415 is fulfilled, the fuel quantity distribution is shifted 420 towards higher BDE injections, that is to say, the arithmetic ratio KM _BDE / KM _SRE resulting from the two above-mentioned parameters, the so-called "distribution factor", is determined by A value predetermined also based on experience has been increased. It can additionally be provided that the ignition timing or ignition angle of the internal combustion engine does not have to be shifted 425 backwards.

On the basis of the distribution factor changed in this way or on the basis of the proportionate fuel quantity of the BDE path, the BDE injection described 440 for the current i-th cylinder and the SRE injection 445 for the remaining fuel quantity are carried out. Afterwards, the routines 405-445 described in 450 are executed for the next, that is to say, currently the i+1th cylinder.

It should be noted that the exact values of the quantity distribution, the change in the ignition timing and the exact threshold values are currently not important, since these values are each dependent on the respective internal combustion engine or the fuel dispenser used.

FIG. 5 shows an exemplary embodiment of a characteristic map according to the invention, in which the knock characteristics of the relevant internal combustion engine previously determined by means of test measurements or empirically determined according to different operating states 500 of the internal combustion engine or the injection system are stored. The data 505. The operating state comprises in this example the value of the quantity distribution KM _BDE /KM _SRE , the value of the compression ε and the value of the early state of the combustion, more precisely the piston Value of the temperature T _k , in this example in "°C". It should be noted here that the piston does not heat up until after a few seconds at the earliest, and even after a few minutes when there is a load jump from a low to a high motor load. In this case, at the beginning of the high load situation, the still cold piston is wetted by the fuel, which is thus vaporized too slowly, which in turn leads to an increase in particle emissions and/or HC/CO emissions, more precisely, The gasification time is so long: until the piston is fully heated.

It should also be noted that the values of these variables stored in the characteristic map can also be learned by means of suitable algorithms during operation of the internal combustion engine.

In the event of a fault as shown in FIG. 4 , the respective fault situation can therefore be counteracted quickly by a targeted change of the distribution factor corresponding to the quantity distribution. The currently existing compression ratio ε can also be derived by comparing the knock limit currently ascertained during the operation of the internal combustion engine with reference values correspondingly stored in the map.

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

Claims (13)

1. the method for running internal combustion engine, the internal combustion engine has the dual fuel distributing portion based on air inlet pipe（20）With it is direct Fuel distributing portion（19）, wherein, in the fuel distributing portion based on air inlet pipe and in the direct fuel distributing portion In, calculate respectively by means of the fuel quantity required for amount distribution, and the internal combustion engine also carries at least one combustion in internal combustion engine Burn the variable compression of indoor fuel/air mixture, it is characterised in that detection（405、410）Including the pressure that there is currently Contracting（405）The current service condition of the internal combustion engine inside, and determine（420）It is related to the service condition detected For the value for the amount distribution being previously mentioned.

2. in accordance with the method for claim 1, it is characterised in that the service condition being previously mentioned of the internal combustion engine, except when Preceding compression ratio ε（Yi Pu sirons）Outside, the current operating point and/or current load and/or ring of the internal combustion engine are included Border condition and/or the early stage situation about the burning in each combustion chamber of the internal combustion engine.

3. in accordance with the method for claim 2, it is characterised in that the described early stage situation of the burning includes internal combustion engine Or the current and/or previous transient response in fuel distributing portion.

4. according to the method described in any one of preceding claims, it is characterised in that detecting first threshold predetermined more than energy During the compression of value, and additional detections to more than can predetermined Second Threshold load when, the amount distribution by discretely or Continuously along the direction movement in the BDE fuel distributings portion through raising（420）.

5. in accordance with the method for claim 4, it is characterised in that the current angle of ignition or time of ignition of the internal combustion engine do not have Have and adjusted backward（425）.

6. according to the method described in any one of preceding claims, it is characterised in that characterize the detonation characteristic of the internal combustion engine The different running statuses of parameter and internal combustion engine or spraying system, the described early stage situation with amount distribution, with burning and with （Variable）Compressed value is relatively stored in performance plot.

7. in accordance with the method for claim 6, it is characterised in that by will be quick-fried what is currently obtained in the operation of internal combustion engine The limit is shaken compared with the knock value being stored in the performance plot, has been inferred in the operation of internal combustion engine there is currently Compression ratio ε（Yi Pu sirons）.

8. in accordance with the method for claim 7, it is characterised in that the value of the limit of detonability in the operating point of internal combustion engine and point Value with factor is relatively stored in the performance plot with the compression, the limit of detonability by the change of allocation factor come Obtain, and pass through the pressure by expected limit of detonability compared with the limit of detonability so obtained relatively to be inferred to physical presence Contracting.

9. according to the method described in claim 7 or 8, it is characterised in that by determining that compression ratio ε is realized to variable compression Diagnostic function, the diagnostic function cyclically or when needed performed.

10. according to the method described in any one of preceding claims, it is characterised in that perform each cylinder body for internal combustion engine For the calculating of the fuel distributing portion based on air inlet pipe and two fuel quantities for direct fuel distributing portion, more specifically Perform continuously or one after the other the calculating.

11. computer program, it is arranged for performing each step of the method as described in any one of claim 1 to 10 Suddenly.

12. machine readable data medium, stores the computer program as described in claim 11 thereon.

13. the controller of electronics, it is arranged for, and is controlled by the method as described in any one of claim 1 to 10 double The fuel distributing portion of weight.