EP3014093B1 - Method for determining the absolute injection quantity in an internal combustion engine and arrangement therefor - Google Patents

Description

State of the art

The run-up test is a well-known diagnostic test for determining the injection quantity error in injectors in an internal combustion engine.

For example, is from the DE 10 2007 010 496 A1 a method for comparative testing of injection combustion engines is known in which the engine is controlled by an electric motor control, which either has self-diagnostic means or is equipped with a connection interface for an external diagnostic device. By means of the self-diagnosis means or the diagnostic device, information can be obtained from the measured and displayable deviations of the respectively defined measured variables when a cylinder is switched off, which indicates that a possible target deviation of the deactivated cylinder is possible. For example, it can be concluded by comparing the maximum speeds achieved during startup test on the relative injection quantity of the individual cylinders. In this case, starting from idling a certain number of injections are made with a predetermined fixed injection quantity, so that the engine accelerated high. One single cylinder is deactivated for each test run. From the achieved maximum speed can be concluded per test run on the relative injection quantity.

However, since the torque demand due to friction and other effects (e.g., from units connected to the engine) is not known, the absolute injection quantity can not be determined.

Therefore, for example, in the case of a four-cylinder engine, if a larger amount was determined for two cylinders relative to the other two cylinders, it remains unclear whether the two smaller injection quantity cylinders have a smaller amount and the larger injection quantity cylinders inject the correct amount or whether the two cylinders with the smaller one Injection amount inject the correct amount and have the cylinder with the larger injection amount more. That is, it is not clear which injectors must be replaced.

The WO 2004/053316 discloses the determination of an injection valve characteristic via the evaluation of speed gradients with fuel cut and continued control of the injector to be checked.

Disclosure of the invention

Thus, it is a possible object of the present invention to propose a method for determining the absolute mean injection quantity of all injectors, in particular the absolute injection quantity of an injector, in order to be able to determine an absolute injection quantity error.
This object is achieved with the features of the independent claims.
Further embodiments are given in the dependent on these dependent claims.
Further features and details of the invention will become apparent from the dependent claims, the description and the drawings. In this case apply
Features and details that are described in connection with the method according to the invention, of course, also in connection with the arrangement according to the invention and in each case vice versa, so that with respect to the disclosure of the individual aspects of the invention always reciprocal reference is or may be.
The inventor has recognized that during the acceleration test essentially from the speed at which the speed decreases, as long as no injection is active, the torque requirement of the engine by friction and connected thereto aggregates and thus of the maximum speed reached directly to the absolute Injection quantity can be deduced. For this purpose, only the knowledge of a predeterminable engine-specific factor f is necessary, which is, inter alia, proportional to the moment of inertia of the engine.
The core idea of the invention consists essentially in depositing the aforementioned predeterminable engine-specific factor f for the respective engine in an engine control unit and / or a workshop diagnostic test apparatus. With the aid of the factor stored for the respective engine, the absolute total injection quantity can thus be determined by means of a run-up test Individual injection quantities of the individual injectors are determined and evaluated at the defined operating point.

It is particularly advantageous that the implementation of the invention, no structural change in existing engine control devices and workshop diagnostic equipment, but only an inventively improved evaluation - possibly depending on existing in the control unit of the engine or the workshop diagnosis functions - e.g. requires the measured data recorded in the known run-up test.

Knowing the absolute injection quantity of the individual injectors, then it can be determined which injectors inject incorrectly. This clearly shows which injector needs to be replaced. So workshop costs can be reduced.

An inventive method for determining the absolute fuel injection quantity of the injectors of an engine of the type of internal combustion engine with a number of cylinders NZ may _comprise the steps of: determining a first absolute total _{injection amount} M _inj ( nz = NZ ) of all injectors based on a run-up test in which all cylinders of the Motors are active, recorded measurement data and a predetermined engine-individual factor f ( nz = NZ ) , which was determined in the event that all cylinders are active. The acquired measurement data are essentially those which are suitable for describing the time profile of the engine speed n ( t ) during the acceleration test, in particular during the startup with active injection and during the fallback to the idling speed during inactive injection.

der Motordrehzahl n(t) während des Hochlaufens mit aktiver Einspritzung (Hochlauf-Phase), eine zweite Änderungsgeschwindigkeit $a_2=2\pi \frac{\mathit{dn}}{\mathit{dt}}$

der Motordrehzahl mit inaktiver Einspritzung (Free-fall-Phase) und einer Leerlaufdrehzahl n_idle des Motors sein. Für den Fachmann ist es selbstverständlich, dass für einzelne oder alle der Messdaten a₁, a₂, n_idle , n_max , äquivalente andere Messwerte bzw. entsprechende Kombinationen von Messwerten verwendet werden können, um den zeitlichen Verlauf der Motordrehzahl hinreichend genau zu beschreiben. Beispielsweise können anhand des Zeitpunkts t ₁ zum Beginn der Hochlauf-Phase, des Zeitpunkts t ₂ am Ende der Hochlauf-Phase bzw. Beginn der Free-fall-Phase sowie des Zeitpunkts t ₃ am Ende der Free-fall-Phase zusammen mit den Messwerten für n_idie und n_max die Änderungsgeschwindigkeiten a ₁ und a ₂ berechnet werden. Mit anderen Worten, reicht es aus anhand des zeitlichen Verlaufs der Motordrehzahl n(t) solche Messwerte zu bestimmen, von denen die Größen a ₁, a ₂, n_idls , n_max in der Auswertung abgeleitet werden können.The measurement data to be acquired during the run-up test can, for example, be a maximum achieved engine speed n _max , a first rate of change $a_1=2\pi \frac{\mathit{dn}}{\mathit{dt}}$

the engine speed n ( t ) during run-up with active injection (run-up phase), a second rate of change $a_2=2\pi \frac{\mathit{dn}}{\mathit{dt}}$

the engine speed with inactive Injection (free-fall phase) and idling speed n _{idle be} the engine. It is obvious to a person skilled in the art that equivalent or different combinations of measured values can be used for individual or all of the measured data a ₁ , a ₂ , n _idle , n _{max in} order to describe the course of the engine speed with sufficient accuracy. For example, based on the time t ₁ at the beginning of the run-up phase, the time t ₂ at the end of the run-up phase or start of the free-fall phase and the time t ₃ at the end of the free-fall phase together with the measured values for n _idie and n _max, the _{rates of} change a ₁ and a _{2 are} calculated. In other words, it is sufficient to use the time curve of the engine speed n (t) to determine those measured values from which the quantities a ₁ , a ₂ , n _idls , n _max can be derived in the evaluation.

For example, during the run-up test, the engine to be tested can be accelerated by means of a defined number N of injections per active cylinder, the maximum speed n _max . is reached (run-up phase). Thereafter, no injections occur until the engine speed is free to fall back to idle speed (free-fall phase); This is evident, for example, from the fact that the idle controller engages again.

Based on the first absolute total _{injection quantity} M _inj ( nz = NZ ), the absolute average injection _quantity per injector m _{inj is} determined by dividing the total injection amount by the number nz of the cylinders of the engine, with active injection, and the total number N of the completed injections per cylinder during startup.

In one development of the method _{according to} the invention, at least one second absolute total _{injection quantity} M _inj ( nz = NZ -1) is determined on the basis of measured data of a further run-up test, in which at least one of the cylinders is inactive, and a predeterminable engine-individual factor f ( nz - 1) determined for the engine on an inactive cylinder. Inactive cylinder here means that in the run-up phase, the injector of this cylinder does not inject fuel into this cylinder. Based on the first and the at least one second absolute total injection _quantity , the absolute injection _quantity and thus the individual injection _{quantity drift of} a specific individual injector m _inj for the cylinder which was inactive when determining the at least one second absolute total injection _quantity can be determined. For this purpose, only the determined second absolute total _{injection quantity} M _inj ( nz = NZ -1) has to be subtracted from the determined first absolute total _{injection quantity} M _inj ( nz - NZ ) and the result divided by the number N of injections per cylinder.

Preferably, the respective absolute total _{injection quantity} M _inj ( nz ) is determined based on an energy balance E.

Preferably, the respective absolute total _{injection quantity} M _inj ( nz ) is determined based on the kinetic energy E _{idle of} the engine at idling speed n _idle .

Preferably, the respective absolute total _{injection quantity} m _inj ( zn ) is determined based on the work W _ext performed by the engine during startup .

Preferably, a torque _requirement M _reto to be provided by the engine is _determined on the basis of the friction and external work based on the second rate of change a ₂ .

It is preferably taken into account that a work performed by the engine until reaching the maximum speed n _max and thus absolute total injection quantity is quadratically dependent on the maximum speed n _max achieved.

ermittelt, wobei f(nz) der konstante vorbestimmte Faktor für den Motor, bei nz aktiven Zylindern, ist,
Der Faktor f ist ein für jeden Motor individueller Faktor, der für jeden Motor vorab bestimmbar ist. Der Faktor f kann in einem Motorsteuergerät und/oder ein Werkstattdiagnosetestgerät zur Verwendung in einem erfindungsgemäßen Verfahren abgespeichert werden. D.h., der Faktor f kann vom Hersteller des Motors vorab für jede Motorausführung basierend auf der während des Hochlaufens insgesamt eingespritzten Kraftstoffmenge M_inj = N ·nz ·m_inj anhand der folgenden Formel bestimmt werden: $$f\left(\mathit{nz}\right)=\frac{N\cdot \mathit{nz}\cdot m_{\mathit{inf}}}{n_{\mathit{max}}^2+\left(n_{\mathit{max}}^2-n_{\mathit{idle}}^2\right)\cdot \frac{a_2}{a_2}-n_{\mathit{idle}}^2}$$

Dabei ist nz die Anzahl der aktiven Zylinder und N die Gesamtzahl der erfolgten Einspritzungen pro aktivem Zylinder während der Hochlaufphase des Motors von der Leerlaufdrehzahl n_idle bis zur maximal erreichten Drehzahl n_max . Die Bestimmung von f(nz) erfolgt idealerweise an einem Fahrzeug dessen Injektoren keine Minder- oder Mehrmenge aufweisen, d.h. jeder Injektor die gleiche, nämlich die vom Motorsteuergerät angeforderte Menge m_inj tatsächlich einspritzt.
Für das erfindungsgemäße Verfahren ist es zur Ermittlung der individuellen Einspritzmenge eines Injektors ausreichend, wenn der Faktor f(nz) für nz = NZ sowie nz = NZ - 1 im Vorhinein bestimmt wird.The determination of the respective absolute total _{injection quantity of} all cylinders M _inj (z n ) is made in particular based on the following relationship $$M_{\mathit{inf}}\left(\mathit{nz}\right)=f\left(\mathit{nz}\right)\cdot \left(n_{\mathit{Max}}^2+\left(n_{\mathit{Max}}^2-n_{\mathit{idle}}^2\right)\cdot \frac{a_2}{a_2}-n_{\mathit{idle}}^2\right)$$

where f ( nz ) is the constant predetermined factor for the engine, for nz active cylinders,
The factor f is an individual factor for each engine, which can be determined in advance for each engine. The factor f can be stored in an engine control unit and / or a workshop diagnostic test apparatus for use in a method according to the invention. That is, the factor f may be determined in advance by the engine manufacturer for each engine design based on the total amount of fuel injected during run-up M _inj = N * nz * m _inj using the following formula: $$f\left(\mathit{nz}\right)=\frac{N\cdot \mathit{nz}\cdot m_{\mathit{inf}}}{n_{\mathit{Max}}^2+\left(n_{\mathit{Max}}^2-n_{\mathit{idle}}^2\right)\cdot \frac{a_2}{a_2}-n_{\mathit{idle}}^2}$$

In this case, nz is the number of active cylinders and N is the total number of completed injections per active cylinder during the acceleration phase of the engine from the idling speed n _idle to the maximum achieved speed n _max . The determination of f ( nz ) ideally takes place on a vehicle whose injectors have no reduced or increased amount, ie each injector injects the same amount, namely the quantity m _inj requested by the engine control unit.
For the method according to the invention, it is sufficient to determine the individual injection quantity of an injector if the factor f ( nz ) for nz = NZ and nz = NZ -1 is determined in advance.

The inventive method can be implemented by means of an arrangement comprising: a suitably programmed workshop diagnostic device, which is connectable to a connection interface of a correspondingly programmed engine control device of a motor. The implementation of the method may be controllably established by the workshop diagnosis device and / or engine control device. At least one predetermined engine individual factor f ( nz ) determined when nz cylinders are active may be stored in the workshop diagnostic device and / or in the engine control device.

The necessary calculations of the injection quantities can be integrated in the software of the engine control unit and / or the workshop diagnostic test apparatus in the form of a correspondingly programmed algorithm as part of a diagnostic module.

That is, the diagnostic module can be integrated as a software module in the software of an engine control unit (ECU-based workshop diagnostic module). After starting by a workshop diagnostics tester connected externally via a diagnostic interface to the engine control unit, the diagnostic module runs completely autonomously in the engine control unit. Upon completion, the diagnostic module returns the test results to the workshop diagnostic tester. Such a ECU-based workshop diagnostic modules differ from simple actuator tests in that the vehicle to be diagnosed in the workshop is offset by the engine control unit into predetermined no-load operating points, impresses actuator excitations and can independently evaluate the result via sensor values with an evaluation logic.

Alternatively, the diagnostic module as a software module can also be integrated into the software of a workshop diagnostic tester (diagnostic tester-based workshop diagnostic module). The functional sequence, the evaluation and the evaluation of the method according to the invention then take place in the workshop diagnostic test apparatus, the measurement data used for the evaluation being determined by means of the engine control unit of sensors present in the vehicle or by additional test sensors.

The invention can be implemented as a computer program product with computer program code such that when the computer program code is executed on a corresponding programmable device, in particular a motor control device and / or a workshop diagnostic test device, this device carries out a method according to the invention.

Brief description of the drawing figures

• Fig. 1 den prinzipiellen Aufbau einer Testanordnung aus einer Motorsteuerungseinrichtung und einem Werkstattdiagnosetesteinrichtung,
• Fig. 2 den zeitlichen Verlauf der Motordrehzahl eines Motors bei einem erfindungsgemäßen Hochlauftest, und
• Fig. 3 ein Ablaufdiagramm einer möglichen Umsetzung des erfindungsgemäßen Verfahrens zur Bestimmung der absoluten Einspritzmenge.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, embodiments of the invention are described in detail. The features mentioned in the claims and in the description may each be essential to the invention individually or in any desired combination. They show (schematically):

• Fig. 1 the basic structure of a test arrangement comprising a motor control device and a workshop diagnostic test device,
• Fig. 2 the time course of the engine speed of a motor in a run-up test according to the invention, and
• Fig. 3 a flowchart of a possible implementation of the inventive method for determining the absolute injection quantity.

embodiments

In the following description, specific details are set forth. It is understood, however, that embodiments of the invention may be used without these specific details. Known circuits, structures and methods are not shown in detail so as not to obscure the understanding of the present description.

FIG. 1 shows the basic structure of a test arrangement of a motor control device and a workshop diagnostic tester.

A motor controller 1 as a motor control device via a diagnostic interface 3 and a diagnostic cable 5 with the external diagnostic device 7 as Workshop diagnostic test device coupled. The engine control 1 is set up for the control of the engine 9 in normal and test mode.

In the embodiment described here, the diagnostic device 7 is configured to send the control data required for a specific diagnosis to the engine control unit 1, to control the test procedures and to retrieve the test results from the engine control unit 1.

The data required for controlling the motor 9 is acquired by the engine controller 1 by means of schematically illustrated sensor inputs 11 to 15. The engine controller 1 is further set up to determine from the acquired data according to control parameters stored in the engine controller 1 for controlling the engine. This can be done by calculation based on stored algorithms, readings from stored tables or maps or the like.

In principle, the controlled engine 9 can be a spark-ignited internal combustion engine (gasoline engine) or a self-igniting internal combustion engine (diesel engine), wherein fuel is injected directly into the cylinders of the engine 9 by means of an injector assigned to the respective cylinder.

The control of the engine 9 is performed by the engine controller 1 via outputs 21 to 25. To illustrate the invention, only the control of a single fuel injector 31 for one of the cylinders of the engine 9 is shown here by way of example schematically. The control of the fuel injector 31 via the control output 21. For example, the engine controller 1 via the output 21, a solenoid valve in the fuel injector 31 drives. Through the solenoid valve, a nozzle needle can be actuated hydraulically, which opens or closes an associated injection nozzle. The opening time and the opening time of the injectors are essential control parameters of the engine. For the present invention, the specific structure of a fuel injector and the underlying injection principle are not important. It may be, for example, a pump-nozzle or common-rail injection system.

By means of the opening duration of the injection nozzle and the injection pressure, the engine control unit 1 essentially determines the amount of fuel injected into the associated cylinder. This in turn affects engine output and torque output.

FIG. 2 shows how the speed runs during a run-up test according to the invention in the simplest case.

bis zu Maximaldrehzahl n_max bei Zeitpunkt i ₂ ansteigt. In der mit "C" markierten Phase, ab Zeitpunkt i ₂ ist die Einspritzung inaktiv, sodass die Drehzahl näherungsweise linear mit der zweiten Steigung a ₂ wieder abfällt. Sobald die Leerlaufdrehzahl zum Zeitpunkt t ₃ wieder auf die Leerlaufdrehzahl n_idle gefallen ist, greift die Leerlaufdrehzahlregelung wieder und hält die Drehzahl stabil (Phase "D").At the beginning, in the phase marked with "A", the engine started is idling, ie the idling control is active and keeps the idling speed n _idle . At the time l ₁ starts the run-up test. In the phase marked "B", injection is active from time l ₁ so that the engine speed of the engine is approximately linear with a constant first slope $a_1=2\pi \frac{\mathit{dn}}{\mathit{dt}}$

rises to maximum speed n _max at time i ₂ . In the phase marked "C", from time i ₂ , the injection is inactive, so that the speed drops approximately linearly with the second slope a ₂ again. As soon as the idling speed has fallen back to the idling speed n _idle at time t ₃ , the idle speed control resumes and keeps the speed stable (phase "D").

wobei f dem unbekannten Trägheitsmoment des Motors entspricht.The torque requirement, which is essentially caused by internal engine friction and by units connected to the engine, can be determined from:

where f corresponds to the unknown moment of inertia of the motor.

The total done by the engine during the phase "B" with active injection, ie when running up work W _ges , corresponds to the sum of the kinetic energy of the rotating motor E _red at maximum speed reached n _max and the external work done W _ext , ie overcoming the friction plus drive of the units, minus the kinetic energy E _{idle of} the engine at idling speed n _idle : $$W_{\mathit{ges}}=e_{\mathit{red}}+W_{\mathit{ext}}-e_{\mathit{idle}}=2{\pi }^2\left(n_{\mathit{Max}}^2\cdot J+\frac{n_{\mathit{Max}}^2-n_{\mathit{idle}}^2}{a_1}\cdot M_{\mathit{reib}}-n_{\mathit{idles}}^2\cdot J\right)$$

The work performed by the engine W _ges is in turn proportional to the total injection quantity of all cylinders M _inj ( zn ), or to the average injection quantity of the cylinders times the number nz of the active cylinders times the number N of all the injections per cylinder:

From this, the absolute total injection quantity can be determined by: $$M_{\mathit{inj}}\left(\mathit{zn}\right)=f\left(\mathit{zn}\right)\cdot \left(n_{\mathit{Max}}^2+\left(n_{\mathit{Max}}^2-n_{\mathit{idle}}^2\right)\cdot \frac{a_2}{a_1}-n_{\mathit{idle}}^2\right)$$

The engine-individual factor f ( zn ) thus contains both the moment of inertia of the engine and the efficiency of the engine, ie the kinetic energy generated per gram of fuel.

The inventor has recognized that the factor f ( zn ) is a constant factor which in particular does not depend on the instantaneous torque requirement of the engine under test. The factor f ( zn ) can therefore be determined once and stored in the control unit of the engine or in the software of a workshop diagnostic tester .

The relationship set in the above formula (4) can be used to express the absolute injection quantity by means of a run-up test to determine measured data. The relationship can basically be integrated into the software of the engine control unit as part of a control unit-based workshop diagnostic module. That is, the diagnostic module is integrated as a software module in the engine control unit and runs after starting by the externally connected workshop diagnostic tester completely self-sufficient in the engine control unit and reports after completion of the result to the diagnostic tester.

Alternatively, integration into a diagnostic tester based workshop diagnostic module is possible, i. the functional sequence, the evaluation and the evaluation of the test according to the invention are carried out in the workshop diagnostic test apparatus, wherein the measured data used for the evaluation can be determined by means of the engine control unit of sensors present in the vehicle or by additional test sensors.

Thus, to implement the invention essentially only an adaptation of existing software in the engine control and / or diagnostic equipment is necessary to implement the inventive method.

FIG. 3 illustrates as a flowchart a possible implementation of the method according to the invention for determining the absolute injection quantity of an injector.

In a first step S1, a first run-up test takes place in which the injection is active for all ZN cylinders of the engine 9 to be tested.

In step S2, from the detected measured variables, namely the first speed a ₁ , at which the speed n in the run-up phase "B" increases, the second speed a ₂ , at which the speed n in the free-fall phase " C "decreases and the maximum speed n _max reached at the end of the run-up phase" B "determines the absolute total _{injection quantity} m _inj . Based on this, the average injection quantity per cylinder or each of the injectors can already be closed.

Then the startup test is repeated in accordance with the number NZ of the cylinders of the engine, wherein in each case the injection is inactive in one of the individual cylinders, ie no injection takes place in a cylinder.

In step S3, a run variable n = 1 is set.

In step S4, it is checked whether the running variable n is greater than the number NZ of the cylinders of the engine. If so, then all other necessary startup tests have been performed and the method continues to step S8. Otherwise, the process goes to step S5.

In step S5, the respective second run-up test n is repeated as in steps S1 and S2, but in contrast to that the cylinder associated with the run variable does not undergo injection, ie zn = NZ -1.

In step S6, the absolute total injection quantity is then determined from the determined measured variables of the currently performed run-up test n .

This is again done by means of relationship (4), using a second factor f ( nz = NZ - 1) instead of the factor f ( nz = NZ ), since the work done by the engine has a different relationship for ZN - 1 active cylinders is considered to be active with NZ active cylinders.

In step S7, the running variable is incremented, that is, n : = n + 1. Thereafter, the process goes to step S4.

In step S8, the individual injection quantity drift for each individual injector is determined on the basis of the determined first absolute total injection quantity and the NZ second absolute total injection quantities. For this purpose, in each case for a particular injector, the second absolute total injection quantity, which was determined in the run-up test in which the cylinder belonging to the injector was inactive, is subtracted from the first absolute total injection quantity and the result is divided by the number N of injections per cylinder.

In step S8, alternatively or additionally, the above relationship (4) may be used to determine the relative quantity differences from the inactive cylinder tests while the absolute injection quantity from the test (steps S1 and S2) with all cylinders NZ is active.

Subsequently, the method ends, wherein the determined results can be output on a display or a printer.

The in Fig. 3 Part of the method denoted by "I" is used to determine the first absolute total injection quantity by means of a test run in which the injection is active in all cylinders.

The in Fig. 3 Part of the method denoted by "II" serves to determine in each case a second absolute total injection quantity by means of a test run in which the injection is inactive in one of the cylinders.

Claims (8)

1. Method for determining the absolute fuel injection quantity of the injectors (31) of an engine (9) of the internal combustion engine type having a number of cylinders NZ, characterized in that a first absolute total injection quantity M_inj (nz = NZ) of all the injectors (31) is determined on the basis of measured data captured in a run-up test, in which all the cylinders of the engine (9) are active, and a predetermined individual engine factor f(nz = NZ) of the engine (9), which was determined for the case in which all the cylinders are active and is stored in a workshop diagnostic device (7) and/or an engine control device (1), wherein the measured data is a maximum engine speed n_max reached, a first rate of change a₁ of the engine speed during the run-up with active injection, a second rate of change a₂ of the engine speed with inactive injection and an idling speed n_idle of the engine (9) or these variables are derived from the captured measured data and are suitable to describe the time profile of the engine speed n(t) during the run-up test,
   wherein the respective absolute injection quantity M_inj(zn) is determined on the basis of the following relationship $$M_{\mathit{inf}}\left(\mathit{nz}\right)=f\left(\mathit{nz}\right)\cdot \left(n_{\mathit{max}}^2+\left(n_{\mathit{max}}^2-n_{\mathit{idle}}^2\right)\cdot \frac{a_2}{a_1}-n_{\mathit{idle}}^2\right)$$

   

   where f(nz) is the constant predetermined factor for the engine with nz active cylinders.
2. Method according to Claim 1,
   that at least a second absolute injection quantity M_inj(nz = NZ - 1) is determined on the basis of measured data from a further run-up test, in which at least one of the cylinders is inactive, and an individual engine factor f(nz - 1), which was determined for the case of an inactive cylinder.
3. Method according to either of Claims 1 and 2,
   characterized in that
   the respective absolute total injection quantity M_inj(nz) is determined on the basis of an energy balance E_ges.
4. Method according to Claim 3,
   characterized in that
   the respective absolute total injection quantity Minj(nz) is determined on the basis of at least one of the kinetic energy E_idle of the engine (9) at idling speed n_idle and the work W_ext performed by the engine (9) during the run-up.
5. Method according to one of the preceding claims,
   characterized in that
   a torque requirement M_reib to be performed by the engine (9) is determined on the basis of friction and external work based on the second rate of change a₂ .
6. Method according to one of the preceding claims,
   characterized in that
   account is taken of the fact that work provided by the engine (9) until the maximum speed n_max is reached, and therefore the absolute total injection quantity, depends on the square of the maximum speed reached n_max.
7. Arrangement for carrying out a method according to one of Claims 1 to 6,
   characterized in that
   an appropriately programmable workshop diagnostic device (7) can be connected via a connection interface (3) to an appropriately programmed engine control device (1) of an engine (9), and the performance of the method can be controlled by the workshop diagnostic device (7) and/or engine control device (7),
   wherein at least one predetermined individual motor factor f(nz), which is proportional to the moment of inertia of the engine when nz cylinders are active, is stored in the workshop diagnostic device (7) and/or in the engine control device (1) .
8. Computer program product with computer program code of a type such that when the computer program code is executed on an appropriately programmable unit (7, 1), in particular a workshop diagnostic device (7) and/or an engine control device (1), this unit executes a method according to one of Claims 1 to 6.

Images