DE102016216519A1 - Determining a clutch state of a coupled to a clutch to an internal combustion engine drive train of a motor vehicle - Google Patents

Abstract

The invention relates to a method for determining a clutch state (128a to 138a) of a drive train (2) of a motor vehicle (1) coupled to a clutch (4) to an internal combustion engine (112), comprising the steps of: detecting the time profile of one with the rotational speed (nBKM) of the internal combustion engine (112) correlated speed (n), detecting at least one of the internal combustion engine (112) caused speed pattern (128 to 138) from the time course of the speed (nBKM), one of the time course of the mean (DMD) the rotational speed (nBKM) superimposed oscillation (O) having at least one amplitude (A), then to a clutch state (128a to 138a) is closed, if within a time interval (.DELTA.t) a characteristic change in the rotational speed (nBKM) and a characteristic Behavior of the amplitudes (A) is detected. Furthermore, the invention relates to a corresponding arithmetic unit 118, which is set up to carry out the method, to an electrical machine having the arithmetic unit, and to a corresponding computer program for carrying out the method.

Description

The present invention relates to a method for determining a clutch state of a coupled to a clutch to an internal combustion engine drive train of a motor vehicle, and a computer program and a computing unit for its implementation.

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 from the DE 10 2012 204 751 A1 known.

In addition, it is known to detect operating conditions of an internal combustion engine within an engine control unit, which recognizes the operating conditions based on its own control specifications and makes appropriate specifications with respect to the respective operating state of the internal combustion engine to the controller of the electric machine by means of suitable interfaces. A decentralized detection of an operating state of the internal combustion engine, in particular a clutch state of the clutch, which connects the internal combustion engine with a drive train of a motor vehicle, can also be detected by the control and regulating device for controlling and actuating the clutch. Such a coupling detection is for example from the DE 10 2009 046 495 A1 known. In principle, it is desirable to operate an electric machine, which can be operated in particular as a generator and / or motor, and is operatively connected to the internal combustion engine in such a way that the operation of the internal combustion engine is not adversely affected by the operation of the electric machine. For this purpose, it is necessary to recognize critical operating situations of the internal combustion engine, in particular situations in which the coupling state of the engine connecting the internal combustion engine to the drive train clutch to recognize accordingly, and to take into account in the control of the electric machine accordingly. However, such detection is currently only externally possible, for example by the engine control, or the aforementioned control and regulating device for controlling the actuation of the clutch, the clutch states detected from this must be forwarded according to the regulation of the electric machine to the controller of the electric machine ,

However, these methods are very expensive, since the respective coupling states must first be detected or detected externally, the determined coupling states are transmitted to the controller of the electric machine, and then, if necessary, the controller the corresponding default conditions for the respective coupling state to the electric machine performs.

In addition, always a communication link between the controller and the engine control unit must be present and maintained in order to enable a corresponding control of the electric machine. It would therefore be desirable that the operating state detection, in particular the detection of a clutch state of the internal combustion engine is not based on control specifications of the engine control unit or on control specifications of a control and regulating device of the clutch, but on objective state variables or directly based thereon measured variables of the electric machine, the respective Play coupling condition.

In principle, a clutch state is a state in which the internal combustion engine is separated from the drive train by means of the clutch and / or coupled thereto. These conditions are usually transient conditions in which in an uncoupled state, an upshift or downshift in the transmission can be made and after a corresponding switching operation of the engine with the drive train is reconnected by re-engagement. Upshifting is commonly understood to mean gearshifting within a transmission from a smaller to a larger gearbox, whereas a downshifting is understood to mean shifting from a gearbox with a large gearbox to a gearbox with a smaller gearbox.

Disclosure of the invention

A method for determining a clutch state, a drive train of a motor vehicle coupled to a clutch to an internal combustion engine, and a computing unit and a computer program for carrying it out with the features of the independent patent claims are 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 a clutch state of a coupled to a clutch to an internal combustion engine drive train of a motor vehicle, the method preferably by a computing unit, in particular by a controller for an electric machine, which is coupled to the internal combustion engine is executed.

To implement the method, a time profile of a speed correlated with the rotational speed of the internal combustion engine is detected in a first method step. This may be the speed of the internal combustion engine as such or a speed correlated directly with it, e.g. the speed of an electric machine coupled to the internal combustion engine.

The detection of the rotational speed or the chronological progression of the rotational speed of the internal combustion engine can be ensured, for example, by a rotational speed sensor which decreases the rotational speed signal at the crankshaft of the internal combustion engine. However, it is preferred that the rotational speed of the internal combustion engine is determined from its rotational speed of an electric machine coupled to the internal combustion engine. The electric machine can be driven by the internal combustion engine, wherein the electric machine with the internal combustion engine firmly connected, and may be coupled to the crankshaft, for example by means of a belt drive. Thus, the speed of the electric machine to the speed of the internal combustion engine in a fixed ratio. Accordingly, the first method step of determining a time profile of the rotational speed within the electrical machine can be carried out, wherein preferably the rotational speed of the electrical machine is determined from the time profile of at least one phase signal of the electrical machine. In the present case, a phase signal is at least one of the phase voltages and / or one of the phase currents, at least one of the stator-side phase windings of the electrical machine, in particular against a fixed reference potential, such. B. mass, measured. It is also understood that alternatively or cumulatively, the course of the rotational speed of the electric machine by means of a speed sensor, which is either on the internal combustion engine for direct measurement of the speed curve of the rotational speed, or indirectly operatively connected to the electric machine, may be provided.

In a further method step, at least one speed pattern caused by the internal combustion engine is detected from the time profile of the rotational speed of the internal combustion engine, which has an oscillation with at least one amplitude superimposed on the time profile of the mean value of the rotational speed. The mean value of the rotational speed of the internal combustion engine is in this case also determined from the time profile of the rotational speed within a definable time interval, which typically comprises several periods of the oscillation. The determinable time interval can result from a certain number of oscillation periods of the instantaneous speed, but should have at least one oscillation period caused by compressions and decompressions and / or a working stroke of the cylinder of the internal combustion engine.

In a further method step, a clutch state is then concluded when, within a further time interval, a characteristic change in the rotational speed of the internal combustion engine and a characteristic behavior of the amplitudes are detected. It has been recognized that clutch operations, particularly single clutch engagement operations, can be recognized by measurably changing both the amplitudes of the rotational oscillations and the gradient of the speed change within a characteristic period of time that includes the corresponding clutch operation. With a corresponding clutch actuation, traction interruption occurs as a result of a non-actuated accelerator pedal, with the result that the engine speed typically drops at a rather steep gradient towards the idling speed of the internal combustion engine. Within this state, there is no torque request to the internal combustion engine, which is why the ignition and injection of the internal combustion engine is typically deactivated in the time range of the falling speed toward the speed band of the idle control. The load of the internal combustion engine is determined in this state only by the engine friction torque, which is caused in particular by the compression and decompression of the cylinder. Since the output of torque by the internal combustion engine as a rule does not occur within a coupling process, on the one hand a clear decrease in the amplitudes of the rotational speed oscillation can be recognized, since the amplitude height is generally proportional to the output torque of the internal combustion engine.

In addition, given the steeply sloping gradient of the rotational speed in the direction of the idling belt, another criterion is that, in combination with a characteristic change in the amplitude height, a reliable detection of a clutch state is permitted. The characteristic behavior of the rotational speed or amplitudes in relation to a clutch state is to be understood as the above-described changes in the rotational speed or gradient of the rotational speed and / or the change in the mean value of the rotational speed, and the decrease in the amplitude height in comparison to the mean value of the rotational speed associated with such a coupling state. In addition to the mean value of the rotational speed, another suitable reference value can also be used to determine the amplitude.

In a preferred embodiment of the invention, a characteristic behavior of the rotational speed and / or a characteristic behavior of the amplitude before and / or after the time interval, in particular by comparison of the rotational speed and / or amplitudes, before and after the time interval, is also used to determine the coupling state. taken into account when determining the coupling state. By including the rotational speed behavior before and / or after a supposedly characteristic event that takes place within the time interval, a corresponding clutch state can be detected even better. Since the engagement or disengagement is typically used for a gear change, this can be reliably detected by comparing the characteristic speed curves before and after each time interaction. Consequently, when comparing the two speed curves before and after the time interval, and the detection of a jump to higher speeds, a downshift and jump to lower speeds, an upshift within the coupled to the engine transmission can be seen, which in turn draw conclusions allows a corresponding coupling state. Also, due to the duration of the clutch state, for example, compared to a typical switching operation, on further operating conditions of the internal combustion engine, such as the so-called. Sailing be concluded in which the vehicle with an open clutch for a long time (longer than a typical shift lasts) moves. In this case, it can be used as a further recognition criterion that the internal combustion engine is in the idling state or the internal combustion engine has been deactivated for fuel reduction.

In a further preferred embodiment, the characteristic change of the rotational speed is detected when the gradient of the rotational speed exceeds a threshold value. Since, in the state of decoupling of the internal combustion engine, the rotational speed drops towards the idling belt and the braking effect in this state is determined essentially by the friction torque of the internal combustion engine and thus by the compression and decompression of the free-running cylinders, a characteristic gradient of a speed drop can be determined Setting a threshold can serve. Thus, if such a threshold value of a gradient of the rotational speed is exceeded, a necessary condition for the presence of a clutch state is met.

In a further preferred embodiment of the invention, the characteristic behavior of the amplitude or of the amplitudes can be recognized by the fact that a further threshold value is undershot. Another sufficient criterion for determining the clutch state is the decrease in amplitude caused by the lack of torque output by the engine. If the amplitude thus falls below a further threshold value in a characteristic time range, this can serve as a sufficient criterion for determining a coupling state. From a combination of the necessary or sufficient criterion described above, for determining a coupling state, can be concluded very reliably on the presentation of such a coupling state. By further combining the above described characteristic behavior of the rotational speed and the amplitudes before or after the characteristic time interval, detection of the clutch state can be further improved beyond that.

Accordingly, it is preferred in a further embodiment of the invention that a clutch state for gear change is determined in particular on the condition that there is a respectively constant power or increasing power or decreasing power of the internal combustion engine. Since the output power is directly correlated with the output torque and the speed of Brennkraftmasche, and the output torque of the internal combustion engine is in turn connected to the amplitude of the speed signal superimposed oscillations, in addition to the detection of a clutch state can also be recognized whether the high or Downshifting of the transmission by the internal combustion engine, a constant power, an increasing or a decreasing power is transmitted to the drive train.

In a further embodiment of the invention, in a further method step, the exciter current of the electric machine is regulated in a respective clutch state and / or in sequence to a respective clutch state such that the drag torque of the electric machine is adapted to the respective clutch state.

Such recognition and appropriate control of the drag torque of the electric machine is advantageous, as a result, the generator load can be adjusted by a corresponding reduction of the generator excitation upon detection of the closing of a clutch or the opening of a clutch according to the respective state of the internal combustion engine. This is possible both during a clutch state but also after a respective clutch state.

This is particularly advantageous when it is not desired within a clutch state that the speed of the internal combustion engine is reduced too much. In addition, for a Condition in which due to a driver's request, an increased torque to be transmitted by the internal combustion engine and thus a high performance is implemented, advantageously the generator load can be reduced, so that after engaging or disengaging and switching the transmission, the entire possible torque of the internal combustion engine for the propulsion is available. In addition, it is preferred that the excitation current is controlled by specifying a setpoint voltage and / or a nominal current of the motor vehicle electrical system, or by specifying a maximum current output, wherein the maximum current output and / or the maximum exciter current, preferably according to operating conditions, in particular the corresponding coupling states is parameterized.

By such excitation current control, which is based on a specification of the target voltage or the nominal current of the so-called motor vehicle electrical system, a corresponding control of the electric machine, in particular a virtually schleppmomentfreies running the electric machine, especially during acceleration processes of the internal combustion engine, or a corresponding reduction of Bremsmomentbeaufschlagung the electric machine, for example, in idle mode, or be implemented during a clutch state. Alternatively, such a control can also be regulated by regulating a maximum current to be delivered to the motor vehicle electrical system, wherein this maximum current in turn can be parameterized depending on the respective operating states of the internal combustion engine, in particular the clutch states. Such a parameterization can be done either numerically, or be implemented by querying the stored parameters in a stored map.

The use of a computing unit, in particular a controller for an electrical machine, which is preferably arranged in the electric machine, but can also be arranged externally to the electric machine, is for the determination of the coupling states and for any resulting control of the drag torque or the 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 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 thereon, and / or is set up by a corresponding integrated circuit to execute the method according to the invention. The integrated circuit can in this case be designed in particular as an ASIC (Application Specific Integrated Circuit). The execution of the method in a controller of the electric machine is also advantageous because both the evaluation of the signals, the determination of the respective clutch states and adjusting the electrical machine based on the determined clutch states, without additional external communication connections and independent of an external computational, Memory, and / or rule architecture can be done.

The implementation of the method in the form of a computer program, which is preferably available on a data carrier, in particular a memory, in the arithmetic unit for executing the method, is advantageous, since this causes particularly low costs, especially 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 / or 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.

Brief description of the drawings

1a shows a schematic representation of a motor vehicle with an internal combustion engine, which is coupled by means of a clutch to a drive train, and an electric machine coupled to the internal combustion engine;

1b shows the internal combustion engine with the electrical machine coupled therein 1a in an enlarged view in frontal view;

2a shows an internal combustion engine and a coupled to the internal combustion engine according to the invention electrical machine in a first schematic representation;

2 B shows an internal combustion engine and coupled to the internal combustion engine electric machine according to a further embodiment in a schematic representation:

2c shows a coupled to a vehicle electrical system in to 2c enlarged schematic representation;

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

4a to f show a plurality of exemplary operating states of the internal combustion engine in which the speed curve is interrupted by coupling states, which can be determined by means of a method according to the invention; and

5 shows an enlarged view of a characteristic time interval of at least one operating state 4 ,

In 1a is a motor vehicle 1 represented by an internal combustion engine 12 is driven. For this purpose, the internal combustion engine 12 to a drive train 2 coupled, via the means of a clutch 4 and a gearbox 6 that of the internal combustion engine 12 generated torque for driving the motor vehicle 1 on the wheels 8th is transmitted. For permanent supply of a motor vehicle electrical system 10 with electrical energy, is also to the internal combustion engine 12 a generator-operated electric machine 14 coupled. The internal combustion engine 12 with the electrical machine coupled thereto is for explaining an already known control for controlling the voltage in a motor vehicle electrical system 10 in one too 1a shown enlarged view. As already mentioned, the motor vehicle electrical system 10 by means of the internal combustion engine 12 coupled electric machine 14 fed, the electric machine 14 by means of a coupling element 16 , typically a belt drive, by the internal combustion engine 12 is driven. For controlling the vehicle electrical system voltage 10 is an arithmetic unit 18 in the form of a regulator 20 provided that adjusts the excitation current of the electric machine in accordance with the vehicle electrical system voltage accordingly.

To the regulation or the feeding of electrical energy into the vehicle electrical system 10 depending on the respective operating states of the internal combustion engine 12 or coupling states of the coupling 4 To be able to regulate, typically the corresponding states by an internal combustion engine 12 or the clutch 4 associated control unit 22 determined, whereupon the control unit 22 via a communication connection 24 Control signals to the controller 20 transmitted to a field current of the electric machine 14 according to the respective operating state or coupling state. Here is the controller 20 the electric machine 14 or a corresponding external to the electrical machine 14 Arranged arithmetic unit (not shown), with respect to a determination of the respective operating and / or coupling states always passive and only set up for it, based on a control by the control unit 22 the excitation current of the electric machine 14 increase or decrease according to the respective operating and / or coupling state.

In 2a is a schematic representation of a structure of an internal combustion engine according to the invention 112 and one with the internal combustion engine 112 connected electrical machine 114 shown, the electric machine 114 by means of a belt 116 from the internal combustion engine 112 is driven. The belt 116 is the engine side with the crankshaft 117 the internal combustion engine 112 operatively connected. The internal combustion engine 112 are due to the power strokes and / or by the compression of the respective cylinder of the internal combustion engine 112 , the torque pulses from the crankshaft. The frequency of the torque output of the cylinder to the crankshaft is determined by the current speed of the internal combustion engine 112 and the number of cylinders of the internal combustion engine 112 certainly. In a four-stroke engine, the frequency of the torque output is determined according to the formula: f _moment = n _KW / 60 × number of cylinders / 2, where n _{KW is} the speed of the crankshaft in revolutions per minute and the speed n _{Bkm of} the internal combustion engine 112 equivalent.

This non-uniform torque output generates a corresponding vibration behavior of the internal combustion engine 112 , Due to the fixed coupling of the electric machine 114 with the internal combustion engine 112 through the coupling element 116 in the form of a belt or a rigid connection of the electrical machine 114 and the internal combustion engine 112 (not shown), the corresponding oscillation, by the pulse-like torque output of the internal combustion engine 112 is caused on the electric machine 114 and transmit their speed n _gene .

These oscillations are due to the fixed coupling between the electric machine 114 and the internal combustion engine 112 from the phase signal 120a (see. 3 ) of the electric machine 114 derivable.

The inventive method is based on a computing unit 118 described on which the process is carried out. For control and assignment, the electric machine points 114 the computing unit according to the invention 118 in the form of a regulator 120 on. The arithmetic unit 118 is set to off the phase signal 121 a time course of a speed 122 to investigate. As already mentioned, the speed is 122 or n _{gene of} the electric machine in the case of a belt drive between the electric machine 114 and the internal combustion engine 112 via a corresponding gear ratio with each other correlated. Accordingly, with knowledge of this ratio and determination of the speed 122 the electric machine 114 , directly the speed n _{BKM of} the internal combustion engine 112 determined.

The time course of the speed 122 is through the arithmetic unit 118 analyzed and from the time course of the speed 122 becomes a speed pattern 128 to 138 (see. 4 and 5 ) derived from the characteristic impulsive vibrations of the internal combustion engine 112 arises.

In addition, the speed patterns indicate 128 to 138 in addition to the oscillations, a characteristic behavior of the speed n _BKM or the speed 122 or n _gene of the internal combustion engine 112 directly coupled electric machine 114 on, on a corresponding coupling state 128a to 138a is due. Such a characteristic behavior of the speed 122 is such that the speed within a characteristic time interval .DELTA.t has a steeply decreasing gradient of the speed or a steeply decreasing slope of the speed (see 4a -F and 5 ).

Thus, the gradient of the speed or the sharply varying slope of the speed 122 within a characteristic time interval Δt as a sufficient criterion for the presence of a clutch state 128a to 138a be used. In addition, the speed patterns indicate 128 to 138 the characteristic oscillations mentioned above with corresponding amplitudes A (A ₁ -A ₃ ) and ripples W (cf. 4a -F and 5 ). The ripple or the amplitudes A of the oscillation are particularly simple by comparison with a mean value D _{MD of} the rotational speed 122 quantifiable, wherein the arithmetic unit 118 is adapted to determine a corresponding average value D _{MD of} the speed, and this, if necessary, to save.

The mean value D _{MD of} the speed 122 , can be determined within a definable time interval, wherein the time interval for determining the average value D _{MD of} the rotational speed 122 a plurality of oscillations, but at least one oscillation O, should have. Furthermore, the amplitude A of the oscillation O or its ripple W by the arithmetic unit 118 be determined. The amplitude A (see. 5 ), is the difference in magnitude of at least a maximum of the oscillation O to the average value D _{MD of} the rotational speed 122 and the ripple W is approximately twice the amplitude A.

In a decoupled state in which the internal combustion engine 114 through the clutch 4 is separated from the transmission and no torque is transmitted, takes the oscillation O or the ripple W of the temporal speed curve 122 clearly off. In extreme cases, when disengaging the clutch 4 even the ignition and / or the injection of the internal combustion engine is deactivated, which is why the speed ripple W is no longer due to the working cycles of the internal combustion engine 112 , but only by the compression and decompression of the cylinder comes about. Such a decrease in the oscillations O in the speed band can be considered as a necessary criterion for the presence of a clutch state. As a further sufficient criterion is added that, as already mentioned, the time course of the speed 122 falls within the time interval At with a very strong gradient towards idle speed. Basically, these two criteria are a selection criterion for such a coupling state 128a to 138a to recognize. The detection can basically be made on the basis of threshold values, wherein for the gradient of the rotational speed 122 a threshold value S ₁ can be defined, wherein when this threshold value S _{1 is} exceeded, the presence of a rotational speed gradient criterion for the detection of a clutch state 128a to 138a can be accepted.

Furthermore, a further threshold value S ₂ can be provided for the amplitudes A, it being possible to conclude correspondingly when the threshold value S ₂ falls below the presence of a coupling state. The threshold values S ₁ and S ₂ may be based on engine parameters of the internal combustion engine 112 or the electric machine 114 be chosen such that a coupling state 128a to 138a safe from other operating conditions of the internal combustion engine 114 can be distinguished. Clues, for example, for the threshold value S ₁ here offers the gradient for a drop in the internal combustion engine 114 at a deactivated ignition or injection, wherein the drop or gradient of the speed 122 within this range essentially by the friction moments within the internal combustion engine 112 or the braking torques of the units coupled thereto, in particular the electric machine 114 be effected. The same applies to the threshold value S ₂ , which is based on knowledge of the machine parameters in particular the ripple W of the speed 122 based on the compression and / or decompression or a low torque output of the internal combustion engine 114 can be set appropriately to a clutch state 128a to 138a to recognize safely.

In 2 B is another, to 2a similar embodiment shown. Same or comparable features too 2a were hereby identified with the same reference number but with a further letter (b). The electric machine 114b has a speed sensor 115b on that with the electric machine 114b connected is. The speed sensor 115b is set to the electric machine so that it is the speed n _{gene of} the rotor of the electric machine 114b can determine. The means of the speed sensor 115b determined speed n _gene or 122 (see. 3 ) can be used as well as by means of a phase signal 121 determined speed are used to the clutch states 128a to 138a to investigate.

This results in an alternative source of supply speed 122 , either alternatively or cumulatively for determining the speed 122 from the phase signal 121 can be used.

In 2c another embodiment of the present invention is shown. Same or comparable features too 2a respectively. 2 B were marked with the same reference number but with a further letter c. It is further simplified assuming that in the case of a cumulative determination of the speed 122 through the phase signal 122 and the speed sensor 115b ( 2 B ), the respective coupling state 128a and 132a through the arithmetic unit 118c is determined.

The arithmetic unit 118c in the form of a regulator 120c an electric machine 114c is formed, is also adapted to the respective coupling state 128a to 138a (see. 5 ) and on the basis of the detected clutch condition 128a to 138a the internal combustion engine 112 , an excitation current I _ERR such a respective coupling state 128a to 138a the internal combustion engine 112 adapt that the braking torque of the electric machine 114 depending on the coupling state 128a to 138a can be increased or decreased.

Here, the excitation current under specification of a _target voltage U _target or an I _{target of} the vehicle electrical system 110c or under specification of a maximum current output I _Max , wherein the maximum current output I _Max according to operating conditions of the internal combustion engine 112 can be parameterized.

By such a regulation of the exciter current I _Err , which is based on a specification of the _setpoint voltage U _setpoint or of the setpoint current I _{setpoint of} the motor vehicle electrical system 110c is based, a nearly braking torque-free or schleppmomentfreies running the electric machine 114a be implemented in the acceleration mode of the internal combustion engine or in idle mode accordingly simple. Alternatively, such a regulation can also be regulated by means of a regulation of a maximum current I _{Max to} be delivered to the motor vehicle vehicle network, this maximum current I _Max in turn being dependent on the respective clutch states 128a to 138a the internal combustion engine 112 can be parameterized. Such a parameterization can either take place numerically or be converted by querying the parameters stored in a stored map (not shown).

The determination of the speed signal 122 from a phase signal 121 the electric machine 114 is in 3 described in more detail. At the phase signal 121 this is one of the phase voltages 121 the electric machine 114 , It is understood that in principle any desired phase voltage of one or more phases of the electrical machine 114 , But also the respective phase currents are usable, in order therefrom the speed signal of the electric machine 114 as well as the speed signal and the speed pattern 128 to 138 the coupled to this internal combustion engine 112 to be determined (not shown). When using more than one phase voltage, a correspondingly higher temporal resolution of the speed signal can be achieved (not shown).

The phase voltage 121 runs in a generator with current output in the first approximation rectangular. At this signal of the phase voltage 121 For example, a mean phase time T _{phase can be} detected, these being best on the steep slopes of the phase voltage 121 can be determined. The phase T _phase is due to the speed fluctuation in the form of one for the respective operating conditions of the internal combustion engine 112 characteristic speed pattern 128 - 136 modulates and maps the current speed, according to the relation: n _KW = 60 / (T _PHASE × PPZ × U) where n _{kw is} the crankshaft speed in revolutions per minute, the transmission ratio between crankshaft and generator shaft or pulley RS and PPZ is the number of pole pairs of the electric machine 114 , The corresponding values of the speed 122 and a medium speed 122a , which is the mean D _{MD of} the speed 122 within a time interval, are in 3 also shown 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 T _{phase of} the amplitudes in the phase signal 121 the electric machine 114 , as already described, the instantaneous speed n _KW can be determined. If parameters such as number of cylinders, transmission ratio Ub and pole pair number PPZ of the electric machine 114 known in the recorded period, the controller 118 a fixed number of speed values in a memory, for example in a shift register, store (not shown) and at least within a vibration cycle each have a maximum and a minimum instantaneous speed of the electric machine 114 and / or the internal combustion engine 112 determine. 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 that by the internal combustion engine 112 delivered torque (ripple W). For accurate determination of T _phase , it is advantageous to ensure a high temporal resolution around the mean of T _phase . Here, for a better resolution, the speed based on the rising and falling edges of the phase voltage 121 be determined. In principle, any number of rpm values can be detected in the memory, although approximately one complete cycle of a vibration should be recorded for an evaluation.

To show that the sampling rate of the generator is sufficient for the speed 122 and in particular to resolve the oscillations superimposed on the rotational speed correspondingly, the ratios of the corresponding frequencies are to be considered below and compared with the Nyquist criterion. The Nyquist criterion requires that f _el / f _moment > = 2. Relative to the engine speed results in the generator frequency or the frequency of the electric machine with f _el = n _KW / 60 · Üb · PPZ, where n _{KW is} the speed of the internal combustion engine.

In combination with the equation for f _moment results f _el / f _moment = 2 · Üb · PPZ / number of cylinders.

Thus, for example, for U n = 3, PP Z = 6, number of cylinders = 4, the quotient f _el / f _moment = 9 results. Even with very large high-cylinder engines, for example, a 12-cylinder engine, the ratio f _el / f _moment = 3, where also the Nyquist sampling criterion is always met.

In the 4a to f are exemplarily several coupling states 128a to 138a described. In the respective ordinates are exemplary the speed 122 and time is plotted in the abscissa. The coupling conditions 128a to 138a be based on the speed curve n _{gene of} an electric machine 114 and the characteristic rotational speed curve during a time interval Δt and the characteristic amplitudes A ₁ , A ₂ , A _{3 of} an oscillation O before a clutch state, during a clutch state and after a clutch state. Basically, the coupling states 128a to 138a for coupling operations of couplings 4 , in particular single clutches, characteristic. As already mentioned, in the respective observation periods of the speed curve shown in each case 122 both the oscillation O and the amplitudes A ₁ to A ₃ measurably changed. Basically, however, it is understood that not necessarily the speed curve 122 an electric machine 114 must be used, but also directly the speed n _BKM the internal combustion engine 112 for determining the coupling states 128a to 138a can be used.

By operating the clutch 4 , it comes to a so-called clutch state 128a to 138a and subsequently to a short traction interruption in the drive train 2 , In addition, it comes due to a possibly not actuated accelerator pedal to a decreasing speed 122 , wherein the speed n _BKM or the speed correlated thereto 122 in the direction of idle speed band L drops. The gradient G of the waste depends essentially on the engine friction moment, which is determined by the compression or decompression of the cylinders or by other friction losses, but also by the friction losses of other units connected to the internal combustion engine 112 are coupled, such. B. the electric machine 114 to be determined.

In general, within this waste in the time interval .DELTA.t the ignition and the injection of the internal combustion engine 112 disabled until the engine speed n _BKM reaches the speed range L of the idle controller, or is engaged again. As is known, the engine power P = 2π × n _BKM × M, where n _BKM the speed of the internal combustion engine 112 and M is the load of the internal combustion engine 112 or whose output torque is.

In 4a) is a first clutch state 128a in which, within the time interval .DELTA.t, a disengaging and engaging operation for upshifting within the transmission 6 is effected. The upshift generally refers to the gear shift from a low gear ratio to a higher gear ratio, whereas a downshift refers to the gear shift from a higher gear ratio to a lower gear speed. The switching process in 4a is also under the additional boundary condition of a substantially constant power of the internal combustion engine 114 carried out. It can be seen that in the time range before the switching operation within the time interval .DELTA.t the amplitude A _{1 of} the oscillation O in comparison to the amplitude A ₃ after the switching operation is relatively small. This is because of the low speed 122 after the coupling process 128a and the constant power of the internal combustion engine 112 The torque M must be increased accordingly to meet the previously described equation. The increased torque is again with an increased oscillation A ₃ in the time course of the speed 122 associated.

Within the coupling process 128a during the time interval .DELTA.t has the speed curve 122 only slightest amplitude A _2, which is substantially of the compression or decompression of the cylinders of the internal combustion engine 112 come (cf. 5 ). In addition, has within the time interval .DELTA.t the speed curve 122 a steep gradient G up to the re-engagement within the clutch state 128a steeply towards idle speed L drops. Both the characteristic amplitude A ₂ and the gradient G can be used as necessary and sufficient criteria for such a coupling state 128a to recognize. Incidentally, the characteristic amplitudes A ₁ and A ₃ , which suggest a switching operation under the given boundary conditions, can be used as additional criteria in order to further validate such a coupling process. The aforementioned findings, in principle apply to the others, in the 4b to f illustrated coupling states 130a to 138a ,

In 4b) is a downshift at constant power P and a corresponding further clutch state 130a shown. The coupling state 130a as such, in turn, based on the gradient G of the time course of the speed 122 and the characteristic amplitude A ₂ in the time interval .DELTA.t correspondingly recognizable. The course of the amplitudes A ₁ and A ₃ before and after the coupling state 130a , have characteristic amplitudes A ₁ and A ₃ , the amplitudes A ₁ before the coupling state 130a are greater than the amplitudes A ₃ after the coupling state 130a , which in turn is due to the boundary condition of constant power P.

In 4c) is another coupling condition 132a with a corresponding speed pattern 132 the speed 122 shown. Here, an upshift is shown with increasing power P. It is again the coupling state 132a within the time interval Δt with sharply decreasing speed 122 shown with speed gradient G and corresponding amplitude curve A ₂ , as he has also previously described in a similar form. The speed curve A ₁ and A ₃ before or after the clutch state 132a , have corresponding amplitudes A ₁ and A ₃ , wherein the amplitudes A ₁ are correspondingly smaller in comparison to the amplitudes A ₃ , which in turn results from the power relation (before to after) of the previously described equation.

In 4d) is another coupling condition 134a for an upshift with decreasing power P of the internal combustion engine 112 shown. The coupling state 134a with the associated speed pattern 134 is shown within the time interval .DELTA.t, wherein the speed curve 122 a steeply falling gradient G and a corresponding characteristic amplitude A ₂ in the time domain .DELTA.t has. The amplitudes A ₁ and A ₃ before and after the coupling state 134a are so pronounced that the amplitudes A ₃ in comparison to the amplitudes A _{1 are} greater, in turn, the power relation P of the internal combustion engine 112 to fulfill. Depending on the gear ratio and corresponding speed 122 However, the output torque M of the internal combustion engine 112 and therefore also the corresponding amplitudes A ₁ and A ₃ vary accordingly.

In 4e) is another coupling condition 136a with the associated speed pattern 136 shown, wherein the coupling state within the time interval .DELTA.t with gradient G and amplitude A _{2 is} shown. The speed curve 122 Hereby shows a typical process of downshifting with increasing power P of the internal combustion engine 112 , The amplitudes A ₁ before the coupling state 136a within the time interval Δt are slightly larger than the amplitudes A ₃ after the coupling state 136a , as well as the speed 122 has increased.

In 4f) is another exemplary clutch state 138a with the speed curve 138 shown. The coupling state 138a is within the time interval At with the characteristic amplitude A _{2 of} the speed 122 and the steeply down to the idle speed L falling speed 122 shown with gradient G The associated switching operation is a downshift with decreasing power P of the internal combustion engine 112 , It can be seen that the amplitude A ₁ before the switching process due to the lower speed 122 , is slightly larger than after the switching process (amplitude A ₃ ). Basically, it is understood that even more switching operations with varying power P are conceivable, which basically a similar course of the speed 122 and in which the switching operations can be detected in a comparable manner.

In 5 is an enlarged view of the characteristic time interval .DELTA.t with the speed curve 122 shown. It can be seen that, for example, the speed thresholds S ₁ for the detection of the gradient G of the speed 122 , which corresponds approximately to the slope of the average speed D _MD , and a speed threshold band S ₂ for defining the characteristic amplitudes A _{2 are} respectively indicated, which serve the corresponding detection criteria for a detection of a clutch state 128a to 138a set. The speed threshold band S ₂ here has a lower threshold S ₂₁ and an upper threshold S ₂₂ . As already mentioned, the threshold values S ₁ and S _{2 can be set} according to the system parameters of the internal combustion engine 112 be selected to a corresponding coupling state 128a to 138a to detect safely.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102012204751 A1 [0002]
• DE 102009046495 A1 [0003]

Claims (12)

Method for determining a coupling state ( 128a . 130a . 132a . 134a . 136a . 138a ) one with a clutch ( 4 ) to an internal combustion engine ( 112 ) coupled powertrain ( 2 ) of a motor vehicle ( 1 ), comprising the steps of: a) detecting the time course of a speed (n _BKM ) of the internal combustion engine ( 112 ) correlated speed (s); b) detecting at least one of the internal combustion engine ( 112 ) caused speed pattern ( 128 . 130 . 132 . 134 . 136 . 138 ) from the time profile of the rotational speed (n), which has an oscillation (O) with at least one amplitude (A) superimposed on the time profile of the mean value (D _MD ) of the rotational speed (n); c) in which case a coupling state ( 128a . 130a . 132a . 134a . 136a . 138a ) is closed, if within a time interval (.DELTA.t) a characteristic change of the rotational speed (n) and a characteristic behavior of the amplitudes (A) is detected. A method according to claim 1, characterized in that in addition a characteristic behavior of the rotational speed (n) and / or a characteristic behavior of the amplitude (A) before and / or after the time interval (.DELTA.t), in particular by comparing the rotational speed (n) and the Amplitudes (A) before and / or after the time interval (Δt), when determining the coupling state ( 128a . 130a . 132a . 134a . 136a . 138a ) is taken into account. A method according to claim 1 or 2, characterized in that the characteristic variation of the speed (n) is detected when the gradient of the rotational speed (n), in particular the gradient of the mean (D _MD) of the speed (n), a threshold value ( S ₁ ). Method according to one of claims 1 to 3, characterized in that the characteristic behavior of the amplitude (A) is detected when the amplitude (A) falls below a threshold value (S ₂ ). Method according to one of claims 1 to 4, characterized in that the speed (n _BKM ) of the internal combustion engine ( 112 ) correlated speed (s) from a speed ( 122 ) one with the internal combustion engine ( 112 ) coupled electric machine ( 114 ), in particular from the temporal course of at least one phase signal ( 121 ) of the electric machine ( 114 ) and / or by means of a speed sensor (S), is determined. Method according to one of claims 1 to 5, characterized in that a coupling state ( 128a . 130a . 132a . 134a . 136a . 138a ) for the gear change of a transmission ( 6 ), in particular at a constant or increasing or decreasing power P of the internal combustion engine ( 112 ), is determined. Method according to one of Claims 1 to 8, characterized by a further method step comprising the regulation of the exciter current (I _Err ) of the electrical machine ( 114 ) in a respective coupling state ( 128a . 130a . 132a . 134a . 136a . 138a ) and / or in sequence to a respective coupling state ( 128a . 130a . 132a . 134a . 136a . 138a ) such that the drag torque of the electric machine ( 114 ) to the respective coupling state ( 128a . 130a . 132a . 134a . 136a . 138a ) is adjusted. A method according to claim 7, characterized in that the excitation current (I _Err ) under specification of a _desired voltage (U _Soll ) and / or a desired current (I _Soll ) of the motor vehicle electrical system ( 110 ), or with specification of a maximum current output (I _max ), wherein the maximum current output (I _max ) and / or the maximum excitation current preferably according to operating states ( 128a . 132a ) of the internal combustion engine ( 112 ) is parameterized. Arithmetic unit ( 118 ), in particular regulators ( 120 ) for an electric machine ( 114 ), which is set up by a corresponding integrated circuit and / or by a computer program stored on a memory to carry out a method according to one of the preceding claims. Electric machine ( 114 ), with a computing unit ( 118 ) according to claim 9. Computer program that causes a computer unit to carry out a method according to one of the preceding claims, when it is stored on the computer unit ( 118 ) is performed. Machine-readable storage medium with a computer program stored thereon according to claim 11.

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