WO2018041584A1

WO2018041584A1 - Determining cylinder switching of an internal combustion engine

Info

Publication number: WO2018041584A1
Application number: PCT/EP2017/070279
Authority: WO
Inventors: Paul Mehringer; Joerg Maas; Udo Schulz; Wolfgang Fischer; Zoltan Ersek
Original assignee: Robert Bosch Gmbh
Priority date: 2016-09-01
Filing date: 2017-08-10
Publication date: 2018-03-08
Also published as: CN109642512A; EP3507478A1; DE102016216517A1

Abstract

The invention relates to a method for determining cylinder switching (128a) in an internal combustion engine (112), by means of a control unit, preferably a regulator (120) of an electric machine (114) coupled to the internal combustion engine (112). Said method comprises the following steps: determining the temporal course of a rotational speed (122) of an electric machine (114) coupled to the internal combustion engine (112); determining at least one speed pattern (128), produced by the internal combustion engine (112), from the temporal course of the rotational speed (122), the speed pattern (128) having an oscillation (O) superimposed on the temporal course of the mean value (D_MD) of the rotational speed (122); then the internal combustion engine (112) is closed to cylinder switching (128a) when a characteristic change in the oscillation (O) is detected for the cylinder switching (128a). Furthermore, the invention relates to a corresponding computing unit (118) which is configured to carry out the method, to an electric machine (114) comprising the computing unit (118) and to a corresponding computer program for enabling the claimed computing unit (118) to carry out said method.

Description

Description title

Determining a cylinder wiring of an internal combustion engine

The present invention relates to a method for determining a cylinder circuit in an internal combustion engine, as well as a computing unit, preferably a controller for an electrical machine and a computer program for performing the method.

State of the art

For regulating the vehicle electrical system voltage in vehicles, electrical machines, in particular externally excited electrical machines, can be used. These have a controller which regulates the excitation current of the electric machine as a function of the vehicle electrical system voltage. Such a machine is known from DE 10 2012 204 751 AI.

Furthermore, so-called intelligent controllers are known, which adjust depending on the respectively detected by the engine control unit operating conditions of the internal combustion engine, the excitation current of the electric machine accordingly to ensure a correspondingly optimized operation of internal combustion engines and electrical machines coupled thereto.

If, in general, an electric machine is mentioned below, this can also be a generator and / or a motor-operated electric machine.

As already mentioned, the detection of these operating states of the internal combustion engine, currently the engine control unit of the internal combustion engine, is incumbent, that recognizes these operating conditions on the basis of its own control specifications, and by means of suitable interfaces makes appropriate specifications with respect to the respective operating state of the internal combustion engine to the controller of the electric machine. As a result, the controller controls the current output of the generator in the electrical system of the motor vehicle via a setpoint voltage specification of the vehicle electrical system voltage.

However, this method is very expensive, since the respective operating conditions of the internal combustion engine are determined only externally in the engine control unit of the internal combustion engine, the determined operating conditions are transmitted to the controller of the electric machine, and then, if necessary, the controller for the respective operating condition of the engine corresponding control specifications on the electric machine.

In addition, a communication link between the controller and the engine control unit must be present and always maintained in order to enable a corresponding control of the electric machine.

It would therefore be desirable that the operating state detection of the internal combustion engine is not based on control specifications of the engine control unit, but on objective state variables or directly based measured variables that reliably reproduce the operating state of the internal combustion engine and autonomously determined by the controller of the electric machine. Furthermore, it would be desirable to carry out corresponding control specifications of the electrical machine coupled to the internal combustion engine directly from the specifically determined measured variables and the resulting operating states of the internal combustion engine.

Disclosure of the invention

Therefore, a method for determining the operating state of cylinder control of an internal combustion engine, as well as a computing unit and a computer program for carrying it out with the features of the independent patent tentansprüche proposed. Advantageous embodiments are the subject of the dependent claims, as well as the following description.

Advantages of the invention

The method is used to determine the operating state cylinder wiring of an internal combustion engine by means of a control unit, wherein preferably the control unit is designed as a controller of an electric machine coupled to an internal combustion engine. Under an operating condition cylinder circuit, a targeted shutdown and / or switching on at least one cylinder of the internal combustion engine to understand, in particular to reduce accordingly fuel consumption (cylinder deactivation), or in the case of an increased torque request to the internal combustion engine, this by a corresponding turning on or connecting to effect of non-active cylinders of the internal combustion engine. In this context, non-active cylinders are understood to mean cylinders which pass only passively in the internal combustion engine without carrying out a combustion process.

The electric machine can be driven by the internal combustion engine, wherein the electric machine with the internal combustion engine firmly connected and can be coupled to the crankshaft, for example by means of a belt drive. It is also possible that the electric machine is coupled via a freewheel to the crankshaft of the internal combustion engine. In a first step of the method, the time profile of a rotational speed of the electric machine coupled to the internal combustion engine is determined.

A determination of the speed is preferably carried out by the time profile of at least one phase signal of the electric machine, wherein the phase signal may be at least one phase voltage or a phase current of the stator-side phase winding of the electric machine. Further, alternatively or cumulatively for determining the rotational speed of the phase signal, a determination of the rotational speed by means of a rotational speed sensor can be made, which can be arranged to determine the rotational speed in or on the electric machine. Following this, in a further method step, a speed pattern effected by the internal combustion engine is determined from the time profile of the determined rotational speed of the electric machine, the rotational speed pattern having an oscillation superimposed on the time curve of the mean value of the rotational speed. By evaluating the speed pattern, a cylinder connection of the internal combustion engine is then concluded when a change in the oscillation which is characteristic of a cylinder configuration is detected over the course of time of the rotational speed.

In this way, can be detected in a very simple manner within the electrical machine, a cylinder circuit of the engine coupled to the engine without this on the data of an external unit, such. B. the engine control unit of the internal combustion engine, must be used. Such a determination is possible because in case of any cylinder wiring of the internal combustion engine, the speed pattern or the speed signature due to the coupling between the electric machine and the internal combustion engine, in particular by a belt drive driving the electric machine, each other.

It has been recognized that a wiring of the cylinders, ie a selective switching on or off of at least one cylinder of the internal combustion engine leaves a specific signature in the form and arrangement of the oscillation or the oscillations, which is superimposed on the mean value of the rotational speed signal. Upon detection of such a signature in the time course of the rotational speed, it can thus be concluded that the cylinder of the internal combustion engine has been primed. It is understood that any standard signatures of a speed curve for comparison with the currently present speed signature of the instantaneous speed can be stored in the arithmetic unit or in the controller of the electric machine to make an adjustment if necessary. The oscillations superimposed on the mean value of the rotational speed, which are caused by the power strokes and / or the compression or decompression of the cylinders of the internal combustion engine, are essentially periodic for static or quasi-static operating states of the internal combustion engine and therefore have at least internal half a corresponding time interval on a clearly definable frequency and amplitude.

In a preferred embodiment of the present invention, in particular, a cylinder circuit of the internal combustion engine is closed when an absence or occurrence of an amplitude, in particular a periodic absence or occurrence of an amplitude, is detected in the time course of the oscillation.

Since the internal combustion engine emits its respective torque impulsively to the crankshaft, the frequency of the torque output is essentially determined by the current speed and the number of cylinders of the internal combustion engine. If a cylinder is connected accordingly, i. switched on or off, with only a passive running of the cylinder is connected within the internal combustion engine at a shutdown, the periodic pattern of the amplitudes of the oscillation is changed accordingly, since the pulse-like torque input corresponding to a larger number (cylinder activation) or a smaller number (cylinder deactivation ) Cylinders is effected. On the basis of such a signature, a cylinder circuit can be reliably detected.

In a further preferred embodiment of the invention is then closed to a cylinder circuit when a characteristic change of the remaining amplitudes in the time course of the oscillation is detected. If the engine slides from an operating range without cylinder deactivation into an operating range with cylinder deactivation, then the remaining active cylinders have to take over the torque of the deactivated cylinders, which then causes the oscillations, in particular the amplitudes of the oscillation in the instantaneous speed of the active remaining Change cylinder, in particular, depending on the respective requested torque increase. In the case of a cylinder engagement, the torque requested by the internal combustion engine is distributed to at least one further cylinder, which leads to a reduction in the amplitudes of the oscillation in the instantaneous speed. This effect can be used alone or in addition as indica- be used for detecting the cylinder deactivation or a cylinder activation.

In a further preferred embodiment of the invention, a cylinder circuit is then closed when a factor influencing the frequency of the oscillation is changed depending on the number of connected cylinders. The frequency of the time average of the speed superimposed oscillation has a frequency fmoment. This follows approximately according to the formula: fmoment = N KW / 60 X number of cylinders / 2, where NK _{w is} the speed of the crankshaft of the internal combustion engine in revolutions per minute. In a coupling of the electric machine to the internal combustion engine by means of a belt drive and pulleys, a possible transmission ratio between the pulleys may also be taken into account when determining the frequency fmoment. According to this functional relationship, it can be seen that when switching on or off, the number of cylinders is increased additively or reduced by subtraction. Such a signature in the speed curve of the internal combustion engine can be detected and closed upon detection in such a signature on a cylinder wiring of the internal combustion engine.

In a further preferred embodiment of the invention, the mean value determined from the time profile of the rotational speed is used as a further criterion for determining a cylinder circuit such that the mean value of the rotational speed is compared with at least a first threshold value and then this further criterion for the presence of a cylinder circuit is affirmative if the mean value of the speed is greater than the threshold value. Furthermore, it is preferable, as part of the determination of the criterion, to perform a comparison of the mean value of the rotational speed with a further threshold value, the further threshold value being greater than the first threshold value, and the first threshold value and the further threshold value being a threshold band or a rotational speed range indicate that typically includes a partial load operation of the internal combustion engine. The criteria mentioned above are preferably sufficient criteria for cylinder wiring. A cylinder circuit is made by the engine control typically in partial load operation of the internal combustion engine, since within this part-load operation, not the full torque that the internal combustion engine is able to deliver is needed. Basically, the part-load operation, the operating state of the internal combustion engine idling operation, the idling operation is usually defined based on speed. Part-load operation is typically associated with a corresponding speed band and torque band, and detection of the average speed curve within that speed band may serve as a sufficient criterion for the presence of a possible cylinder deactivation. In addition, the partial load operation, positive gradients or slopes of the amplitudes, which are correlated with a torque output by the internal combustion engine, have, in turn, can be used to detect the partial load operation or to differentiate between part load operation and idle operation.

Accordingly, the combination of a sufficient criterion, given by a detection that the mean value of the speed within or outside a speed range for a partial load operation, and a necessary criterion, namely that a corresponding signature in the speed curve of the internal combustion engine is detected, certainly the Operating state cylinder circuit of the internal combustion engine to be differentiated from other possible operating conditions of the internal combustion engine.

In a further preferred embodiment, the method has a further method step for controlling the electric machine, wherein the excitation current of the electric machine, in the operating state of the electric machine Beschälten the cylinder of the internal combustion engine is controlled such that the braking torque or that of the internal combustion engine to overcoming drag torque of the electric machine is increased or decreased.

An adaptation of the braking torque or drag torque caused by the electric machine to the internal combustion engine is therefore advantageous, since in the case of an increased torque request to the internal combustion engine and switching on of additional cylinders, a reduction of the output torque of the Internal combustion engine can be avoided by a torque counteracting this torque of the electric machine. Similarly, in the case of a cylinder deactivation, a reduction of the braking torque of the electric machine is advantageous, since the internal combustion engine is in an unstable operating state during the switch-off process and could be further destabilized by an additional application of load by the electric machine.

Accordingly, in the presence of an excess torque of the internal combustion engine, the excitation current of the electric machine and thus the braking torque of the electric machine can be increased, for example, to recover energy. In a regulation of the braking torque of the electric machine via the exciting current, it is particularly preferred that the excitation current under specification of a nominal voltage and / or a nominal current of the motor vehicle electrical system or under specification of a maximum current output, the maximum current output and / or the maximum excitation current, preferably according to operating conditions the internal combustion engine is parameterized, is regulated.

By such energizing current regulation, which is based on a specification of the setpoint voltage or the nominal current of the motor vehicle electrical system, according to a target of a maximum torque to be delivered by the engine or a stabilization of the internal combustion engine, a braking torque-free running the electric machine, for example, in acceleration mode or when switching off be guaranteed at least one cylinder. Also, a recovery of energy in the presence of excess torque, for example in a push operation, is equally possible. Alternatively, such a regulation can also be regulated by regulating a maximum current to be delivered to the motor vehicle electrical system, wherein this maximum current can also be parameterized as a function of the respective operating states of the internal combustion engine. Such a parameterization can either take place numerically, or be implemented by querying the parameters stored, for example, in a stored map. The use of a computing unit, in particular a controller for an electrical machine, which is preferably arranged in the electrical machine, but can also be arranged externally to the electric machine, is for the determination of the operating states cylinder circuit and for a possible resulting control of Braking torque of the electric machine particularly advantageous since this method in a particularly simple manner, the inventive method is feasible.

The arithmetic unit is therefore configured accordingly to execute the method, which means that the arithmetic unit has a corresponding arithmetic processor and / or a corresponding data memory with a computer program stored on it and / or is set up by a corresponding integrated circuit to execute the method according to the invention , The execution of the method in a controller of the electric machine is also advantageous because both the evaluation of the signals, the

Determining the respective operating states and adjusting the electrical machine based on the determined operating conditions can be done without additional external communication connections and independent of an external computing, storage and / or control architecture.

The implementation of the method in the form of a computer program, which is preferably available on a data medium, in particular a memory, in the arithmetic unit for carrying out the method, is advantageous since this causes particularly low costs, in particular if an executing controller still for other tasks is used, and therefore exists anyway. Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, as are frequently known from the prior art.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. The invention is illustrated schematically by means of embodiments in the drawing and will be described below with reference to the drawings.

Brief description of the drawings Figure 1

shows a schematic representation of an operating state-based control of an electric machine by a motor controller by means of a communication link according to the prior art;

FIG. 2a

shows an internal combustion engine and a coupled to the internal combustion engine according to the invention electrical machine in a schematic representation;

FIG. 2b

shows an internal combustion engine and a coupled to the internal combustion engine electric machine, according to a further embodiment in a schematic representation;

Figure 2c

shows an enlarged view of the electric machine of Figure 2b, in a schematic representation;

FIG. 3

shows a time course of a phase voltage of the electric machine, and the speed derived therefrom;

FIG. 4

shows a temporal section of a speed curve of the electric machine, with an exemplary signature for a cylinder circuit; and

FIG. 5

shows a torque-speed diagram of the internal combustion engine. FIG. 1 shows a control known from the prior art for regulating the voltage in a motor vehicle electrical system 10. The motor vehicle electrical system 10 is fed by means of an electric machine 14 coupled to an internal combustion engine 12, wherein the electric machine 14 is driven by the internal combustion engine 12 by means of a coupling element 16, typically a belt drive. For controlling the Bornetzspannung 10, a computing unit 18 is provided in the form of a regulator 20, which adjusts in accordance with the Bornetzspannung 10, the exciter current of the electric machine accordingly.

In order to be able to regulate the regulation or the feeding of electrical energy into the vehicle electrical system 10 as a function of the respective operating states of the internal combustion engine 12, the corresponding operating states of the internal combustion engine 12 are typically determined by a control device 22 assigned to the internal combustion engine 12, whereupon the control device 22 via a communication link 24, control signals to the controller 20 is transmitted to set an excitation current of the electric machine 14 according to the respective operating state of the internal combustion engine 12. In this case, the controller 20 of the electric machine 14 is always passive with respect to a determination of the respective operating states of the internal combustion engine 12 and only configured to increase or to increase the exciter current of the electrical machine in accordance with the respective operating state on the basis of a control by the control device 22 reduce.

FIG. 2 a shows a schematic representation of a construction according to the invention of an internal combustion engine 112 and an electrical machine connected to the internal combustion engine 112, wherein the electric machine 114 is driven by the internal combustion engine 112 by means of a belt 116. The belt is operatively connected to the crankshaft 116 of the internal combustion engine 112 on the engine side. The internal combustion engine 112 outputs the torque to the crankshaft 117 in a pulse-like manner as a result of the working cycle of the exemplary cylinder Z of the internal combustion engine 112. The frequency of the torque Mentabgabe is determined by the current speed of the internal combustion engine 112 and the number of cylinders, ie the number of actively participating in the combustion process cylinder, the internal combustion engine 112. In a four-stroke engine, the frequency of the torque output is approximately determined by the formula:

torque ^- commercial vehicle / 60 X number of cylinders / 2,

where NK _{W is} the rotational speed of the crankshaft 117 of the internal combustion engine 112 in revolutions per minute.

This non-uniform torque output generates a corresponding vibration behavior of the internal combustion engine 112. By the fixed coupling of the electric machine 114 to the internal combustion engine 112 by the coupling element 116 in the form of a belt or a rigid connection of the electric machine 114 and the internal combustion engine 112 (not shown) the corresponding oscillation caused by the pulse-like torque output of the engine 112 is transmitted to the electric machine 114 and its rotational speed 122.

These oscillations are due to the fixed coupling between the electric machine 114 and the engine 112 from the phase signal 121a

(see Figure 3) of the electric machine removed. Likewise, it is alternatively or cumulatively possible to take the rotational speed 122 of the electric machine 114 also by means of a rotational speed sensor 115b (see FIGS. 2b, c). For the purpose of control and evaluation, the electric machine 114 has the inventive calculating unit 118 in the form of a regulator 120, which is set up to determine a time profile of a rotational speed 122 from the phase signal 121 or from the signal of the rotational speed sensor 115b Course of the speed 122 analyzed and from the time course of the speed 122, a speed pattern 128 (see Figure 4) is derived. The speed pattern 128 caused by the engine 112 is remarkable in particular by the fact that, as already mentioned above, this is a substantially periodic oscillation O, to which a frequency fmoment and amplitudes A can be assigned in a first approximation. The oscillations O are superimposed on the mean value DMD of the rotational speed 122 (see FIG. 4).

The arithmetic unit 118 in the form of a controller 120 is also set up to determine the operating state of the cylinder circuit 128a of the internal combustion engine 112 on the basis of the speed pattern 128 derived from the time profile of the rotational speed 122 (see FIG. remote control unit 22, 122 would be required. However, it is understood that a corresponding external control device 122 may be provided with a corresponding communication link 124 to the controller 120 (shown in phantom), wherein a determination of a corresponding operating state of a cylinder 128a in the controller as a redundant determination of such operating state in the controller of the generator and thus can serve outside of the engine control unit, wherein the detection of such a state can in turn be used for further control strategies within the engine controller 122. In principle, however, the electric machine 114 or the computing unit assigned to it is set up to carry out the method steps described above completely independently and autonomously from an external analysis and / or external control unit, such as a motor controller 122. Established means that the arithmetic unit has a corresponding computer processor R and / or a data memory D with a computer program stored thereon in order to carry out the method according to the invention. In addition, the arithmetic unit can be equipped by means of an integrated circuit which is adapted to carry out the method (not shown).

FIG. 2 b describes a further exemplary embodiment similar to FIG. 2 a. Identical or comparable features to FIG. 2a have been identified with the same reference number but with a further letter (b). The electric machine 114b described here differs from the electrical machine 114 described in FIG. 2a, essentially by a further rotational speed sensor 115b, which is connected to the electric machine 114b. The rotational speed sensor 115b is configured to detect the rotational speed of the rotor of the electric machine 114b and to transmit the rotational speed signal 122 determined therefrom to the regulator 118b. The thus determined rotational speed 122 (see FIG. 4) can thus, alternatively or cumulatively, also be used from the phase signal 121 of the electric machine (see FIGS. 2a and 3) to superimpose the time profile of the rotational speed 122 and the rotational speed signal 122 superimposed on it To detect speed pattern 128.

In FIG. 2c, an enlarged view of the electrical machine from FIG. 2b is shown. The arithmetic unit 118b is set up to detect an operating state of the cylinder circuit 128a of the internal combustion engine 112 and to adapt an excitation current IE _IT to the respective operating state of the cylinder circuit 128a of the internal combustion engine 112 based on the detected operating state 128a such that the braking torque or drag torque of the electric machine 112 is increased or increased is reduced. Here, the exciting current IE _IT can by specifying a target voltage Usoii or a target current Isoii of the motor driving ^¬ imaging board network 110b or by specifying a maximum power output with the maximum current output _ΙΜ 3Χ according to the respective operating state of the cylinder switching on or Zylinderausschalten the internal combustion engine can be parameterized 112, can be controlled.

By such control of the excitation current \ E "be ^¬ rests on a specification of the reference voltage Usoii, or the target current Isoii of the vehicle electrical system 110b, a corresponding adjustment of the braking torque or drag torque of the electric machine 114b may be effected such that in the case of an increased torque request to the internal combustion engine 112 or in the state of a cylinder deactivation to reduce fuel consumption, a braking torque-free idling the electric machine 114b is made possible. Optionally, in another operating condition where excess torque is available by the engine 112, e.g. B. in overrun operation of the internal combustion engine 112, this by a corresponding braking torque or drag torque of the electric machine 114b compen- Siert, which in turn, as already described above, can be controlled via an adjustment of the excitation current IE _IT . In particular, the overrun operation can be detected on the basis of the oscillations and in this case, if necessary, even all the cylinders can be switched off, provided that the respective torque request to the internal combustion engine 112 does not preclude such a shutdown.

In addition, such a regulation can also be regulated by regulation of a maximum current ΙΜ _{3Χ to} be delivered to the motor vehicle _electrical system, wherein this maximum current ΙΜ _{3Χ can} in turn be _{parameterized} depending on the respective operating state of the cylinder circuit or the specific states, cylinder activation or cylinder deactivation of the internal combustion engine 112. Such a parameterization can either be done numerically, or be implemented by querying the parameters stored in a stored map (not shown).

The determination of the rotational speed signal 122 from the phase signal 121 of the electric machine 114 is described in more detail in FIG. In the present case, the phase signal 121 is one of the phase voltages 121a, one of the stator windings arranged on the stator side in the electric machine 114. It is understood that for this purpose basically any phase voltage of one or more phases of the electric machine 114, but also the respective phase currents can be used to from the speed signal 122 of the electric machine 114, and the speed signal 122 and the speed pattern 128 of the coupled to this internal combustion engine 112 to determine (not shown). When using more than one phase voltage 121a, a correspondingly higher temporal resolution of the speed signal can be achieved (not shown).

The phase voltage 121a extends in a generator with current output in a first approximation rectangular. An average phase time T phase can be detected at this signal of the phase voltage 121a, which can best be determined on the steep edges of the phase voltage 121a. The phase time Tphase is determined by the speed fluctuation in the form of a operating conditions of the internal combustion engine 112 characteristic speed pattern 128 modulates and maps the current speed via the formula: n _G en = 60 / (TPHASE * PPZ), where nGen is the speed 122 of the electric machine 114 in revolutions per minute, Üb the transmission ratio between crankshaft and generator shaft and PPZ the number of pole pairs of the generator. Correspondingly, the rotational speed ηκνν at the crankshaft 117 of the internal combustion engine results from ηκνν = nGen / Üb. The corresponding values of the rotational speed 122 and a mean rotational speed DMD, which corresponds to the mean value of the rotational speed 122 within the time interval shown by way of example, are also shown in FIG. 3 as points or as a line. The time interval can in particular be selected such that it is averaged over several oscillations.

The speed can preferably be determined digitally. By means of a measurement of the time intervals Tphase of the amplitudes in the phase signal 121 of the electric machine 114, as already described, the instantaneous speed ηκνν can be determined. If parameters such as number of cylinders, transmission ratio and number of pole pairs of the electric machine 114 are known in the detected period, the controller 118 may store a fixed number of rotational speed values in a memory, for example in a shift register (not shown) and at least one maximum within each one oscillation cycle and determine a minimum instantaneous speed.

The maximum and minimum instantaneous speeds are preferably the peak speeds in the respectively recorded time range. The difference between these speeds is a measure of the torque output by the engine 112. Thus, the output torque correlates with the magnitude of the amplitudes of the oscillation. For accurate determination of phase T it is advantageous to ensure a high temporal resolution around the mean value of phase. In this case, for a better resolution, the rotational speed can be determined on the basis of the rising and falling edges of the phase voltage 121a. Basically any number of rotational speed values 122 can be stored in the memory. however, approximately one cycle of vibration should be detected for evaluation.

In order to illustrate that the sampling rate of the generator is sufficient to correspondingly resolve the rotational speed 122 and in particular the oscillations superimposed on the rotational speed, the ratios of the respective frequencies are considered below and compared with the Nyquist criterion. The Nyquist criterion requires that f _e / fmoment> = 2. Relative to the engine speed results in the generator frequency or the frequency of the electric machine with

where ηκνν is the speed of the internal combustion engine. In combination with the equation for fmoment, this results in fe / f moment- 2 * Ub * PPZ / number of cylinders.

Thus, for example, for U n = 3, PPZ = 6, number of cylinders = 4, the quotient fe / fmoment = 9 results. Even with very large high-cylinder engines, such as a 12-cylinder engine, the ratio is fe / fmoment = 3, where again the Nyquist sampling criterion is always met. In particular, in these high-cylinder engines, the cylinder circuit plays for the saving of fuel (cylinder deactivation) or the provision of as much torque (cylinder activation), e.g. during an acceleration process, an important role.

FIG. 4 shows the time profile of a rotational speed 122 of an electrical machine 114. It can be seen here that the mean value DMD of the rotational speed 122, which is superimposed on the rotational speed pattern 128 caused by the internal combustion engine 112. This speed pattern 128 is characterized by an oscillation O with amplitudes A, which is superimposed on the mean value DMD of the rotational speed 122. As already mentioned in the description of FIG. 2a, there is a functional len relationship between the frequency of the oscillation O and the number of cylinders Z, which are actively operated within the internal combustion engine and contribute to the output torque of the internal combustion engine 112. In the present case, the case is shown in which an amplitude A * is not present (shown in phantom), wherein the amplitude A * is associated with the pulse-like torque output of a cylinder Z of the internal combustion engine and the resulting rotational speed fluctuation. Thus, only by detecting a lack of such an amplitude A * on switching off a cylinder Z of the internal combustion engine 112 can be deduced.

The absence of the amplitude can be determined, for example, by comparing the speed curve with reference values. Furthermore, on the basis of the time interval T _ma xmax between at least two maxima n _ma x of the rotational speed 122 and comparison with a reference value and / or by a deviation of the frequency of the oscillation such that a factor zz which influences the frequency f The number of cylinders according to the formula described in FIG. 2a corresponds additively to the number of connected cylinders Z, that is to say the cylinder switched on or off, a cylinder circuit is determined.

On the basis of the respective deviation in the frequency can therefore be deduced directly on the number of cylinders Z and it can directly by comparison, for example, with a reference value, which usually corresponds to the number of cylinders present in the engine 112 and correspondingly in the computing unit 118 within the electric machine 114 can be deposited, be closed.

In addition, even by the absence of the amplitude A * or by the occurrence of an amplitude A *, wherein the absence and addition of the amplitude A * can also be determined by a reference value, on the Einbzw. Shutting down a cylinder Z are closed. Such a determination of an extension of the period Tmaxmax and / or the emergence or absence of an amplitude A * and / or a frequency change, the oscillation O superimposed on the mean value DMD of the rotational speed 122, can be considered as a necessary criterion for the presence of a cylinder circuit 128a become. In addition, the so-called. Negative amplitudes, ie the amplitudes due to the compression work associated with a reduction in speed and thus a negative slope or a negative gradient, to detect a cylinder deactivation or the absence thereof, can be used to detect a cylinder activation. This applies in particular to the case in which the valves of the at least one cylinder are at least temporarily closed and the inactive cylinder performs a corresponding compression work.

As an additional sufficient criterion, it is also possible to use the comparison of the mean value DMD of the rotational speed 122 with a rotational speed band B, which is limited by the threshold values THi and TH2 (see FIG. 5). These threshold values THi and TH2 are further illustrated in FIG. 5, wherein the threshold value THi and TH2 of the rotational speed n, the region of the rotational speed in which the internal combustion engine 112 is in a partial load operation 136, is indicated. By way of example, this region of the part-load operation 136 in FIG. 5, in which the output torque M of the internal combustion engine 112 is plotted against the rotational speed n of the internal combustion engine 112, is shown, wherein the part-load operation is enclosed by the rotational speed by the threshold values THi and TH2 and in the lower one to the middle range of the torque-speed diagram 138 of the internal combustion engine 112. It is understood that the range of the operating state partial load 136 of the internal combustion engine 112 also includes the idling operating state 140. Typically, a cylinder circuit 128a of the internal combustion engine 112 is made precisely in this partial load range 136 of the internal combustion engine, since the potentially possible torque M of the internal combustion engine 112 is not requested here and accordingly a cylinder deactivation for fuel saving can take place. In principle, however, it is also possible to dispense with a cylinder circuit in idling mode 140 in order to increase the smoothness of the internal combustion engine 112.

Accordingly, in a further operating state 142, which corresponds to an increased to a maximum torque requirement M of the internal combustion engine, at least one cylinder Z of the internal combustion engine 112, which is in a passive state and is not present during operation of the internal combustion engine 112. lent runs, be activated to deliver the requested torque M corresponding to the crankshaft of the internal combustion engine. The engine speed increased range region 142 of the internal combustion engine 112 is set on the engine speed 112 side by the threshold values THi * and TH2 *. Thus, one of the necessary criteria for the presence of a cylinder circuit 128a in the form of a missing or additional amplitude A * and / or detection of an extension or shortening of a period T _ma xmax and / or a frequency change of the mean value DMD of the rotational speed 122 superimposed oscillation O and a sufficient criterion of the course of the mean value DMD of the rotational speed 122 in the respective speed band B of a part-load operation 136 or within a range of increased torque request 142 by the internal combustion engine 112, the presence of a cylinder circuit 128a safely determine. In addition, it is understood that the above-described criteria for determining a cylinder circuit 128a of the internal combustion engine 112 can be used alone or in combination with one another. In addition, a common use of these criteria in the course of a redundant determination of operating states or their plausibility may be advantageous (not shown).

Claims

claims

A method of determining a cylinder wiring in an internal combustion engine (112), comprising the steps of:

a) determining the time profile of a rotational speed (122) of an electric machine (114) coupled to the internal combustion engine (112);

b) determining at least one speed pattern (128) caused by the internal combustion engine (112) from the time profile of the rotational speed (122), wherein the rotational speed pattern (128) comprises an oscillation (O.sub.3 superimposed on the time profile of the mean value (DMD) of the rotational speed (122) ) having;

c) in which case a cylinder circuit (128a) of the internal combustion engine (112) is closed when a characteristic of a cylinder circuit (128a) change in the oscillation (O) is detected.

2. The method according to claim 1, characterized in that the time profile of at least one phase signal (121) of an internal combustion engine (112) coupled to the electric machine (114) is determined and the time course of the rotational speed (122) of the electric machine (114) is determined from the phase signal (121).

3. The method according to claim 1, characterized in that the time profile of the rotational speed (122) of the electric machine (114) by means of a on the electric machine (114) arranged speed sensor (115b) is determined.

4. The method according to any one of the preceding claims, wherein a cylinder circuit (128a) comprises turning on at least one cylinder (Z) of the internal combustion engine (112) and / or switching off at least one cylinder (Z) of the internal combustion engine (112).

5. Method according to one of the preceding claims, wherein the oscillation (O) has frequency (f) and amplitude (A), wherein then a cylinder circuit (128a) is closed, if an absence or occurrence of an amplitude (A) , in particular a periodic absence or occurrence of an amplitude (A), in the time course of the oscillation (O) is detected and / or a change in the frequency (f) is recognized such that a frequency influencing factor (Zz) depending on the number of connected cylinders (Z) changed.

6. The method according to any one of the preceding claims, wherein the oscillation (O) frequency (f) and amplitude (A), in which case a Zylinderbe- circuit (128a) is closed when a characteristic change of the remaining amplitudes (A) in time course of the oscillation (O) is detected.

7. The method according to any one of the preceding claims, characterized in that an average value (DMD) of the rotational speed (122) from the time profile of the rotational speed (122) is determined and as a further criterion for determining the Zy- linderbeschaltung (128a) a comparison of Mean value (DMD) of the rotational speed (122) with at least a first threshold (Thi) is used.

8. The method according to claim 7, characterized in that for the further criterion for determining the cylinder circuit (128a), a comparison of the average value (DMD) of the rotational speed (122) with the first threshold value (Thi) and a further threshold value (Thi2) is greater than the threshold (Thi), is used.

9. The method according to any one of claims 1 to 8, characterized in that the first threshold (Thi) and the further threshold (Thi2) are selected such that they limit a typical speed range for a partial load operation (136) of the internal combustion engine (112).

10. The method according to any one of claims 1 to 9, characterized by a further method step comprising the control of the excitation current (IE _IT ) of the electric machine (114) at a Beschaltten (128a) at least one cylinder (Z) of an internal combustion engine (112) such in that the braking torque of the electric machine (114) is adapted to the respective state of the internal combustion engine (112) during charging (128a) of at least one cylinder (Z) of the internal combustion engine (112).

1 1. A method according to claim 10, characterized in that the excitation current (I Err) under specification of a nominal voltage (Usoii) and / or a desired current (Isoii) of the motor vehicle electrical system (110), or under specification of a maximum current output (iMax), wherein the maximum current output ( is _ΙΜ 3Χ) and / or the ma ^¬ ximum excitation current preferably according to the respective state of the internal combustion engine (112) (at a Beschälten 128a) of the internal combustion engine (112) is parameterized at least one cylinder (Z), controlled.

12. arithmetic unit (118), in particular controller (120) for an electrical machine (114), which is adapted by a corresponding integrated circuit and / or by a stored on a memory computer program to perform a method according to any one of the preceding claims.

13. Electrical machine (114), with a computing unit (118) according to claim 12.

A computer program that causes a computing unit (118) to perform a method according to any one of the preceding claims when executed on the computing unit (118).

15. A machine-readable storage medium having a computer program stored thereon according to claim 14.