BRPI1002448A2 - process and device for determining a fuel composition or a lambda value - Google Patents

Abstract

PROCESS AND DEVICE FOR DETERMINING A FUEL COMPOSITION OR A LAMBDA VALUE. The present invention relates to a process for determining the composition of a fuel mixture composed of a first and at least a second fuel, for the operation of an internal combustion machine, with known fuel and air ratio or a known lambda value in fuel, in which, through targeted interventions, the smooth operation of the internal combustion machine is negatively influenced, at least temporarily. According to the invention, it is foreseen that the influence will be carried out by means of a variation of the ignition angle and / or by means of a variation of the fuel and air ratio, with the resulting non-smoothness of operation or from a gradient resulting from this for non-smooth operation, a parameter is derived for the composition of the fuel mixture currently existing or a lambda value for the cylinders of the internal combustion machine. The device according to the invention has an engine control unit, with which, through targeted interventions, the smooth operation of the internal combustion machine can be negatively influenced, at least temporarily, and the engine control unit features measurement blocks, with which an ignition angle and / or the fuel and air ratio can be regulated, and a non-smoothness of operation resulting from these measures, or a gradient resulting from this for non-smoothness of operation can be derived a parameter for the composition of the existing fuel mixture, or a lambda value for the cylinders of the internal combustion engine. With the process and the device for carrying out the process, optional statements on the one hand about the fuel composition employed or on the other hand about the fuel and air ratio can be made possible. In addition, other motor parameters can also be calculated with the process. In this case, measures of the same type, respectively, and evaluation strategies can be employed, which can reduce the hardware expenditure on a corresponding motor control unit.

Description

Report of the Invention Patent for "PROCESS AND DEVICE FOR DETERMINING A FUEL COMPOSITION OR LAMBDA VALUE".

State of the Art

The present invention relates to a method for determining a fuel composition of a fuel mixture composed of a first fuel and at least a second fuel for the operation of an internal combustion engine. , with known fuel and air ratios or a known fuel Iambda value, in which by means of targeted interventions the operating smoothness of the internal combustion engine is at least temporarily negatively affected.

The invention furthermore relates to a device for carrying out the process, the device having an engine control unit, with which through interventions aimed at the smooth operation of the internal combustion machine. can be negatively influenced at least temporarily.

Otto engine-based internal combustion engines are generally operated with a hydrocarbon fuel composed of refined petroleum-based fossil fuels. To this fuel is increasingly added alcohol produced from renewable raw materials (plants), for example ethanol or methanol in different mix ratios. In the US and Europe, in general, a mixture of 70% to 85% ethanol and 15 to 30% gasoline under the tradename E85 is employed. Internal combustion engines are designed in such a way that they can be operated with pure gasoline as well as with mixtures up to E85; This is referred to as "flex fuel operation". For economical operation with low emission of noxious substances with simultaneous high engine power, the operating parameters for flex fuel operation need to be adapted to the respective existing fuel mixture. If, for example, there is a stoichiometric air to fuel ratio of 14.7 parts by weight of air per parts of gasoline, in the use of ethanol, however, a part of air of 9 parts by weight needs to be adjusted. In addition, for optimal combustion, the ignition angle of the internal combustion engine must be adapted to the mixing ratio. Due to the different evaporation properties of ethanol and gasoline, during the start-up of the internal combustion engine, depending on the mixing ratio, different enrichment factors need to be predetermined. Also the internal combustion engine's own diagnostics, the so-called on-board diagnostics (OBD), and in this case, especially the diagnosis of the fuel supply system 1 (DKVS), in the case of flex fuel, is affected by the other. fuel ratio and stoichiometric air.

The DKVS evaluates the exceedance of diagnostic limits of mixture adaptation factors. In order to avoid an influence of DKVS, the stoichiometric part needs to be considered through a separate factor (fCOmb.) That compensates for stoichiometry. This factor is determined, for example, after refueling on a fuel adaptation. Therefore, knowledge of the existing fuel mixture ratio is of fundamental importance for the operation of the internal combustion engine.

DE 41 17 440 C2 discloses a process for the adaptive adjustment of an air-fuel mixture for consideration of fuel properties in the operation of an internal combustion machine having a lambda regulator providing a regulating factor FR1 and featuring an adapting integrator, which provides an AF adapting factor with variable adapting speed, which alongside the regulating factor FR, influences the adjustment of the air and fuel mixture. In this case, it is intended to be tested whether the deviation range of the lambda setting exceeds a first limit value and, if so, whether the adaptation speed is set to an increased value until a predetermined condition is fulfilled. , after which the gear is reduced to a low adaptation speed. The process based on this is known as fuel adaptation. The fuel adaptation makes it possible to operate, without interference, internal combustion machines, which can be operated with different fuels. Thus, for example, the injection time during a change from a gasoline fuel to a fuel mixture of 85% ethanol and 15% gasoline needs to be extended by more than 40% to maintain same Iambda values in the exhaust gas. This is based on the different need for air for stoichiometric combustion. According to the process described in patent application DE 41 17 440 C2, a corresponding adaptation intervention is carried out for this purpose. Since during a fuel change, as compared to compensating for aging influences or production influences, very accurate correction of the injection times must be carried out and thus the adaptation intervention in the process suggested for Adaptation speed increases significantly during a recognized fuel change.

Repeated refueling of small amounts of fuel or an influence of the determination of the fill level by a sloping vehicle, however, may lead to erroneous adaptation of the ethanol value and thus also make it difficult to properly adjust the limits. diagnostics for on-board diagnostics. Also, a faulty mixture of fuel components can have an in- terferential influence on adaptation.

Other methods are known from the patent literature which make it possible to conclude on the basis of different mixing ratios of fossil fuels and alcohols, and to adapt accordingly the operating parameters of the internal combustion engine. In particular, in the event of a mismatch, the operating smoothness of the internal combustion engine may be considerably disrupted.

Operating smoothness of an internal combustion machine means the oscillations of the engine moment indicated by the individual combustion. In the case of a 1-cylinder engine, these are the combustion-to-combustion oscillations in the same combustion chamber, for example as a result of an unstable air stream, which may oscillate the moment of energy conversion of the mixture of cycle to cycle. In the case of a multi-cylinder engine, these may also be systematic differences between individual cylinders when, for example, one cylinder is operated more lubricated than the other (s).

In general, operating smoothness is determined from the number of revolutions that result from combustion to combustion. One measure for the number of revolutions is the so-called non-smoothness value. The engine rpm is usually determined by means of a rpm transmission wheel placed on the crankshaft. Also the gradient of non-operating smoothness can be used as a parameter from combustion to combustion with the designation "increased non-operating smoothness".

In engines with pressure indication oscillations can be obtained from combustion to combustion, also by evaluating the combustion chamber pressure (indicated average pressure).

The state of the art is an assessment of non-operating smoothness for the recognition of combustion switches. In particular, in the case of low-running engines (layer operation in direct injection gasoline engines and generally diesel engines), non-operating smoothness is also employed for cylinder moment compensation.

In the engine control apparatus of a gasoline engine a moment model is deposited which calculates the engine momentum produced by the engine in its high pressure cycle. High pressure cycling means the 360 ° KW (KW = crankshaft position) of the lower dead crankshaft (UT) rotation, in which the inlet valve almost closes through the high-speed OT. ignition (OT = top dead center) to the bottom dead center at which the outlet valve opens. For a diesel engine a similar momentum model can be derived.

Therefore, the petrol engine produces a model produced at the high pressure stage, for the moment (Mihd) as follows:

Mihd = Mioptii (Π, nmot) * ETAlam (lambda) * ETAdzw (dZW) (1) where "Mioptn" "ETAlam" and "ETAdzw" are for the following quantities: "Mioptn" is the moment which, in this case of the best possible ignition, is produced in the high pressure cycle at a fuel and air ratio of Iambda = 1.0. This value depends first on the fresh air fill (rl) but also on the engine speed (nmot).

"ETAlam" is the degree of lambda efficiency. Thus, the motor moment dependency is described by the lambda value. In the case of a petrol engine it is shown that with approximately lambda = 0.85 and optimized ignition there is a maximum of momentum. If the mixture is more lubricated (-> shortness of breath) then the momentum drops. If the mixture is depleted -> excess air), the momentum falls in the same way.

"ETAdzw" is the degree of efficiency of the ignition angle. The time produced in the high pressure phase depends in particular on the central point of combustion. At a central combustion point of approximately 8 ° KW after the top dead center (OT) the maximum momentum is reached (—► optimal momentum). In the case of early or late central combustion point, ie at an optimum ignition angle deviation (dZW Φ 0 °) the momentum is reduced.

Since the central combustion point is directly coupled to the ignition angle, in the case of a gasoline engine the behavior of the momentum (Mihd) produced in the high pressure cycle as a function of the ignition angle can also be described. Real (ZWist). Between the ignition angle and the central combustion point is the time for the ignition delay (prior ignition time) and the time to the combustion course results in a conversion rate of 50%. These quantities depend on both the fuel used and the fuel / air ratio.

In the case of a petrol engine the ignition angle deviation (dZW) optimized for:

<formula> formula see original document page 6 </formula> (2) ZWopt = KFzwop (rl, nmot) + dZW0, a + dZWoagr (3) where,

ZWopt is the ignition angle where the maximum momentum is (—► optimized ignition angle), "KFzwop" for a characteristic field for an ignition angle, "dZWola" for an optimized ignition angle offset as a function of Iambda value and "dZWoagr" for optimum ignition angle offset as a function of exhaust gas return rates (AGR rates).

In the case of the diesel engine there is no instant of ignition. However, the center point of combustion may be varied in a targeted manner depending on the injection stroke and, for example, with the aid of non-operating smoothness, the ignition delay or the ignition behavior may be determined.

Thus, DE 29 52 073 A1 discloses a process for optimizing the duty cycle of an internal combustion engine with external ignition. In which the internal combustion engine drive data, and indeed, among other things, the relative momentary position of the crankshaft (crank angle) are measured, are fed to an electronic control unit, and of corresponding mode is actuated at the moment of ignition and / or the amount of fuel driven. In this case, it is envisaged that, around a theoretical approximation of the ignition time and / or around the amount of fuel driven, at least one of these adjustment quantities is varied from duty cycle to duty cycle. , such that with the exception of the crank angle still operating the momentarily indicated pressure or a similarly changing quantity is measured therewith, and the position of the piston determined by the crank angle for each working stroke respectively, the indicated mean pressure or an analogous quantity is calculated, and the sequence of calculated values of the indicated mean pressure is automatically recorded, and the values following each other are compared with each other, and for each operating state - Internal combustion engine operation, the change in the setting quantity is interrupted and the existing setting value is set as soon as the mean pressure indicated reaches a maximum value. The process also makes it possible, among other things, to compare deviations of control parameters in the internal combustion engine control, which arise due to the use of different fuels such as methanol, ethanol and gasoline.

DE 38 33 123 A1 discloses a device for recording fuel properties for an internal combustion internal combustion engine, whereby the amount of air drawn in and the ratio of fuel and air in the exhaust gas are measured, A basic fuel injection amount is calculated on the basis of the amount of air drawn in, and the amount of fuel to be injected is calculated corresponding to the fuel to air ratio. The device is characterized by pressure recording means, cylinder internal pressure recording, crank angle recording means, crank angle recording of the internal combustion engine, and an internal combustion device. which receives signals from the pressure recording means and crank angle recording means and calculates an effective calorific power Q of the fuel in an ignition cycle based on the internal cylinder pressure P (Θ) with a crank angle in the compression and expansion strokes of a crank angle θ and cylinder capacity V (Θ) ignition cycle, and an effective combustion value K or a lower calorific power Hu of the fuel is determined, and the properties at least the effective combustion value K or the lower calorific value Hu or the ratio (Ti / Hu) Ti duration of a combustion injection pulse suitable for lower Hu calorific power.

In the unpublished applicant's patent application, internal designation R.319607 describes a process for determining the composition of a fuel mixture of a first and at least a second fuel for operation. of an internal combustion engine, in which the ignition angle of the internal combustion engine is changed, and by the fact that an oscillation of the non-periodic torsion moment dependent on the ignition angle and / or a non-periodic rotation heterogeneity, and / or a quantity derived therefrom as a characteristic quantity is employed for determining the composition of the fuel mixture. If, in this case, the ignition angle is regulated by the optimized ignition angle in the forward or reverse direction, the operating smoothness of the internal combustion engine decreases. Since the optimum ignition angle as well, octane limits depend on the composition of the fuel mixture, with this it can be concluded on the fuel composition. A variation of the fuel ratio in the case of this process is undoubtedly not foreseen. The aspect of a recognition of Iambda through ignition interventions, likewise, is not mentioned in this document.

Therefore, the task of the invention is to prepare a process which, by assessing the smoothness of operation with interventions aimed at ignition and the amount of injection, makes possible statements about the fuel composition employed, on the one hand, or on the relationship of fuel and air, on the other hand.

Furthermore, it is the task of the invention to prepare a corresponding device for carrying out the process.

Description of the Invention

The process task is solved by the fact that the influence is achieved by varying the ignition angle and / or by varying the fuel and air ratio, and by not operating smoothly resulting from this or a resulting gradient for non-operating smoothness is derived a parameter for the composition of the existing fuel mixture or an Iambda value for the internal combustion engine cylinders.

The device task is solved by the fact that the engine control unit has measuring blocks, with which an ignition angle and / or the fuel and air ratio can be regulated, and a non-operating smoothness. resulting from these measurements, or a resulting gradient for non-operating smoothness, a parameter for the composition of the existing fuel mixture may be derived, or an Iambda value for the internal combustion engine cylinders. Functionality in this case can be implemented as software in the engine control unit.

With the process and the apparatus for carrying out the process optional statements can be made on the one hand on the fuel composition employed or on the other on the fuel and air ratio. In this case, measures of the same type, respectively, and evaluation strategies may be employed, which may reduce hardware expenditure on a corresponding motor control unit.

On the one hand, in this case, the fact that the degree of efficiency of an internal combustion engine is dependent on the ignition angle is used. Starting from an optimally optimized ignition angle, in the event of an alteration of the ignition angle, the efficiency decreases towards an earlier or more monotonously delayed ignition time. In this way, with operating parameters of the internal combustion engine that otherwise remain the same the torsional moment changes, and with maximum efficiency the maximum torsional moment occurs. It is known that, in the case of the maximum torsion moment, the periodic oscillation of the torsion moment is likewise maximal over a cycle of the internal combustion engine. It is known that the optimal ignition angle depends on the composition of the fuel mixture. In addition, differently composed fuel mixtures have a different octane limit. In this case, the octane limit designates the ignition angle at which a specified measurement occurs in the octane combustion of the internal combustion engine. In the case of a delayed ignition, ie clearly after upper dead center (OT), the pressure and temperature in the combustion chamber have dropped again, which increases the ignition delay and the duration of the ignition. Therefore, both an Iambda setting and a fuel setting can be advantageously performed with delayed ignition angle.

On the other hand, a reduction in the fuel and air mixture, that is, an increase in Iambda value leads to an increase in non-operating smoothness. In this case, several fuels have a typical poor operating limit. This limit depends, among other things, on pressure and temperature. By reducing, then, both the ignition delay and the inflammation are greatly delayed, or do not start at all. This leads to extremely dragging combustions or authentic combustion switches which then result in markedly increased non-operating smoothness. Knowledge of the poor operating limit is a clue to the fuel used. In the case of known fuel, however, the poor operating limit can be exploited and thus alternatively set the current fuel-air ratio or lambda value.

During such measures, other influences should certainly be minimized according to the possibility or, at the very least, be known to the maximum so as not to falsify the above results.

Advantageously, in the case of intervention, as described above, fuel properties, poor ignition capacity, ignition delay, ignition behavior and / or ignition are used in a targeted manner. boiling behavior for defining the composition of the currently existing fuel mixture or the lambda value. Thus, the smoothness of cold engine operation in reducing the amount of injection (reduction) in which less volatile fuel (eg E85) may be sharply limited earlier than in the case of a fuel high evaporation pressure or boiling curve that is lower with respect to temperature. In this case, it is also conceivable for the fuel recognition to ignite very early, so that at the time of ignition the heat of compression has not yet fully developed and a high boiling fuel has not yet evaporated sufficiently, which would then be noticeable through a high non-operating smoothness. In addition, it is shown that depending, for example, on the fuel ethanol content, a characteristic non-smoothness course of operation would adjust by warming the engine after starting and during the first warm run. This course can be evaluated for recognition of ethanol content.

In a preferred process variant, the ignition time during intervention is delayed in the direction of the delayed ignition and / or the fuel and air relationship is reduced.

In this case, it may be provided that the timing of the ignition and / or the fuel and air ratio shall be carried out constantly or in stages. Thus, for example, ramps may be made correspondingly, or adjustment may take place in small steps.

In a preferred process variant it is envisaged that upon adjustment of the ignition angle and / or fuel-air ratio, the operating smoothness or the operating non-smoothness gradient by at least compared with a limit value for non-operating smoothness or grading of non-operating smoothness, and when reaching or exceeding the corresponding limit value a poor operating limit or a If the limit for the ignition angle is reached, or if the corresponding limit value is not reached, the ignition timing and / or the fuel / air ratio shall be adjusted again. This achieves that the poor operating limit or the maximum possible ignition delay can be exploited.

In this case, it may be envisaged that a value for the average Iambda value of all cylinders or a characteristic value for the fuel currently used will be calculated from the low operating limit.

In a preferred process variant, the characteristic value for the fuel currently employed is an ethanol content, a methanol content or an ethanol and methanol content. Thus, the process may preferably be employed for determining the composition of a gasoline and ethanol fuel mixture, and / or a gasoline and methanol fuel mixture, and / or a fuel mixture of gasoline, ethanol and methanol. All of these fuels and fuel mixtures show a different independence from the non-smoothness of the ignition angle so that unambiguous fuel or fuel mixture coordination is possible through the described process. These ratios may be advantageously employed, for example, in flex-fuel internal combustion engines, and it may be envisaged that the current fuel-to-air ratio may also be defined if a power probe is used. exhaust gas (lambda probe) may not be ready to be adjusted.

Advantageously, in a one-cylinder internal combustion engine, individual combustions are operated one after the other with delayed ignition angle and / or poor fuel and air ratios.

A particularly small restriction on travel comfort can be obtained by the fact that the ignition angle or lambda value of all cylinders of the internal combustion engine is not regulated, but in a multi-cylinder internal combustion engine a cylinder or a portion of the cylinders is operated with delayed ignition angle relative to the remaining cylinders and / or the fuel-to-air ratio.

A heterogeneity of the internal combustion engine's rotational motion or non-operating smoothness can be determined with a rotary speed sensor, or with a crankshaft angle sensor from the rotational speed, which in general already provided for in the internal combustion engine and therefore do not represent any additional expenditure. For the determination of the torsion moment and its periodic and non-periodic parts, a speed sensor or a combustion chamber pressure sensor may be employed. Adjusting the ignition angle in the forward direction leads to combustion with octane, which also results in reduced operating smoothness and non-periodic oscillation of the number of revolutions and torque. Another clue to the non-smoothness of an internal combustion engine's operation is the oscillations of an indicated average internal combustion engine pressure, which can likewise be evaluated by appropriate sensors and thus provide information the fuel combustion capacity and thereby the type or composition of the fuel currently

A preferred use of the process, as described above with its characteristics, is for use in a diesel internal combustion machine, and instead of the ignition angle the injection stroke is varied. This can determine either the value of Yambda or the fluctuations in the composition of diesel fuel (eg in the use of biodiesel, such as rapeseed oil in the fuel).

Another use of the process, as described above, can be used to determine other engine parameters, in which case the process is performed with the known fuel-air ratio and the Iambda value. known.

In this case, an example of process application predicts a diagnosis of an exhaust gas return rate (AGR), whereby the process is performed with the known fuel-air ratio and the known Iambda value. . In this case, one takes advantage of the fact that, with increasing return rate of exhaust gases, poor operating capacity is reduced and thus the non-smoothness of operation increases. This can be advantageously employed, for example, in adapting the AGR and diagnosing a valve control for an exhaust gas return.

Another embodiment provides a diagnosis of a charge movement valve positioning with the known fuel and air ratio, and the known Iambda value. In this case, one takes advantage of the fact that, with increasing load movement, poor operating capacity increases and thereby reduces non-operating smoothness.

The influences of inert gas rate and / or charge movement valves in the mentioned examples can be minimized by an objective choice of operating point.

The invention will be explained in more detail hereinafter with the aid of an exemplary embodiment shown in the figures. It is shown: in figure 1 a flow diagram of the process according to the invention in schematic representation,

Fig. 2, by way of example, the compression stroke of the combustion chamber, the combustion stroke and momentum as a function of the crank shaft angle with optimized combustion point and

Fig. 3, by way of example, the compression stroke of the combustion chamber, the combustion stroke and momentum with a rather delayed combustion.

The process according to the invention departs from the fact that for the determination of a fuel composition of a fuel mixture with the known fuel-air ratio, or a known fuel Iambda value, a temporary influence The operating smoothness of the internal combustion engine is achieved by varying the ignition angle and / or by varying the fuel-air ratio. From the resulting operating smoothness or a resulting gradient to the operating smoothness are derived a parameter for the currently existing fuel mix composition or an Iambda value for the internal combustion engine cylinders.

Figure 1 schematically shows the sequence of process 1 for determining an Iambda value as the average value across all cylinders of a gasoline internal combustion machine, or optionally for determining the fuel currently employed.

After starting the process 10, first by means of a first query 20, a check is made if there is a stable operating state. If this is the case, by means of a second query 30 a branch occurs, a Iambda determination or a determination of the currently existing fuel occurs.

In the case of lambda determination, in a block of measures

At 40 ° C, a successive deterioration of the inflammation conditions occurs. This is accomplished, for example, by ramp-downing one or more cylinders of the internal combustion engine, with simultaneous lubrication of the other cylinders such that the lambda value remains unchanged through all cylinders. In this case, in this example, it is envisaged that at the same time the ignition angle of the reduced cylinders will be adjusted so that the sensitivity of the non-operating smoothness is maximum in the event of a reduction.

With the detection of the actual operating smoothness 60, the operating non-smoothness is determined, for example, by evaluating the number of revolutions. The non-operating smoothness or the non-operating smoothness gradient is compared with a limit value for the non-operating smoothness or the non-operating-smoothness gradient using at least one comparator 70. No In the case of reaching or exceeding the corresponding limit value, a poor operating limit or a limit for the ignition angle shall be determined. If the corresponding limit value is not reached, the ignition time and / or fuel and air ratio shall be adjusted until the operating non-smoothness or the operating non-smoothness gradient exceeds its value. limit. If this is the case, the lambda value 80 is determined in the operating block, from the lower operating limit a value for the average lambda value of all cylinders is calculated, and the evaluation process is calculated. completed first (close 100).

If, as an alternative to this, a detection of the currently existing fuel occurs, as shown in consultation 30 above, a successive deterioration of the ignition conditions occurs in a block B 50. This is accomplished, for example, by ramping down one or more cylinders of the internal combustion engine, with simultaneous lubrication of the other cylinders, such that the value of Iambda across all cylinders is λ = 1. In this case too, in this embodiment, it is envisaged that at the same time the ignition angle of the reduced cylinders is adjusted so that the sensitivity of the non-operating smoothness in case of a reduction is the maximum. Then, as at the other extension in the course of process 1, the actual operating sensitivity 60 is detected. The non-operating smoothness or the non-operating smoothness gradient is compared to a limit value for non-operating smoothness or operating non-smoothness gradient by at least one comparator 70, where in the case of reaching or exceeding the limit values in the operating block the fuel composition 90 is determined from the poor operating limit A parameter is determined for the fuel currently used, and the evaluation process is likewise terminated first (end 100). Otherwise, another deterioration of the conditions of inflammation occurs.

As a parameter for the fuel currently employed, an ethanol content, a methanol content or an ethanol and methanol content can be defined. In this case, it may be provided that the determined composition of the fuel mixture shall be compared to a composition determined by a fuel type sensor and / or a fuel mixture fuel adaptation, and that it shall be concluded on a function. if the difference between the determined fuel mixture compositions exceeds a specified limit value such that, in the context of a plausibility observation, the composition determined with the aid of the fuel type sensor or fuel adaptation be monitored. For example, a fault adaptation of a mixture failure through fuel adaptation can be undone. The functionality of the process 1 process described above at both extensions, in this case, is advantageously implemented as software in a motor control unit.

2 and 3 show, by way of example, as a sequence of application of the process in flow diagrams 200, a combustion chamber compression 201, a combustion stroke 202 and a moment 203, as a function of a position of the crankshaft KW 204, where the compression of the combustion chamber 201 is represented in mbar, and the momentum is represented with an offset, and expanded (50,000+ 100 * M) in Nm.

Figure 2 shows a compression stroke of the combustion chamber 205, a combustion stroke 206, as well as a momentum stroke 207 of a combustion having an optimized combustion point. Half of the energy in this case is converted at the instant corresponding to a crankshaft position KW 204 of 8 ° according to the upper motor point (OT).

In contrast to this, Figure 3 shows an example for the same quantities with greatly deteriorated combustion through the use of the process, however, with equal total chemical energy. The course of moment 207 shows a sharp reduction from the time course of moment 207 in figure 2 which converts the energy at a later angle of cranks. Delayed ignition, depending on the lambda value and fuel types, produces a longer ignition delay and longer ignition. This leads to a delayed heat conversion in an instant where the plunger has already operated largely downwards, so that the transformation of thermal energy into mechanical work takes place with a markedly worse degree of thermodynamic efficiency, which leads to a sharp reduction in engine momentum. The consequence is an increased operating non-smoothness value that can be evaluated, for example, by evaluating the number of revolutions.

Claims (16)

1. Process for the determination of a fuel composition of a fuel mixture composed of a first and at least a second fuel, for the operation of an internal combustion engine, with known fuel or air ratio; of a known fuel Iambda value, in which through targeted interventions the operating smoothness of the internal combustion engine is at least temporarily negatively influenced, characterized by the fact that the influence is achieved by varying an angle and / or by means of a change in the fuel to air ratio, whereby from a resulting operating non-smoothness or a resulting operating smoothness gradient a parameter is derived for the composition of the fuel mixture. currently existing fuel or an Iambda value for the internal combustion engine cylinders. Process according to Claim 1, characterized in that in the case of the intended intervention, the fuel properties such as low ignition capacity, ignition delay, ignition behavior and / or boiling behavior are used to determining the composition of the currently existing fuel mixture or the lambda value. Process according to Claim 1 or 2, characterized in that for the determination of the composition of the currently existing fuel mixture, after a cold start of the internal combustion engine the boiling behavior or evaporation behavior of the fuel mixture, as well as a characteristic non-smoothness course of operation during a hot run phase of the internal combustion engine. Process according to any one of Claims 1 to -3, characterized in that the ignition time during the intervention is delayed in the direction of the delayed ignition and / or the fuel and air ratio is reduced. Process according to Claim 4, characterized in that the timing of the ignition and / or the fuel-air ratio is carried out constantly or in stages. Method according to any one of claims 1 to 5, characterized in that the non-operating smoothness or the non-operating smoothness gradient is compared with a limit value for the non-operating smoothness or gradient. operating smoothness, and when reaching or exceeding the corresponding limit value, a poor operating limit or limit for the ignition angle is determined, or if the corresponding limit value is not ignition and / or fuel / air ratio. Process according to any one of Claims 1 to 6, characterized in that from the low operating limit a value for the average Iambda value of all cylinders or a characteristic value for the fuel currently employed is calculated. . Process according to Claim 7, characterized in that the characteristic value for the fuel currently employed is an ethanol content, a methanol content or an ethanol and methanol content. Process according to any one of Claims 1 to 8, characterized in that individual combustion engines are operated one after the other with a cylinder, delayed ignition angle and / or fuel ratio, and one another. Poor air. Process according to any one of Claims 1 to 8, characterized in that in a multi-cylinder internal combustion engine, a cylinder or part of the cylinders is operated with a delayed ignition angle relative to the remaining cylinders. / or poor fuel to air ratio. Method according to any one of Claims 1 to 10, characterized in that the non-smoothness of operation is determined by evaluating the number of revolutions. Use of the process as defined in any one of claims 1 to 11, in an internal combustion engine, whereby instead of the ignition angle the injection stroke is varied. Use of the process as defined in any one of claims 1 to 11 and according to claim 12 for determining other engine parameters, the process being carried out with known fuel and air ratio. , and with known Iambda value. Use of the method according to claim 13 for the diagnosis of an exhaust gas return. Use of the method according to claim 13 for positioning the loading motion valve. 16. Apparatus for the determination of a fuel composition of a fuel mixture composed of a first and at least a second fuel for the operation of an internal combustion engine with known fuel or air ratio or of a known fuel Iambda value, which has an engine control unit, with which through targeted interventions the operating smoothness of the internal combustion engine can be negatively influenced, at least temporarily, by the fact that the engine control unit has measuring blocks (40, 50), with which an ignition angle and / or the fuel and air ratio can be adjusted, and a non-operating smoothness resulting from these measurements, or a resulting gradient for non-operating smoothness can be derived a parameter for the composition of the existing fuel mixture, or a Iambda value for internal combustion engine cylinders.