DE102017222834A1 - Method for determining a direction of rotation of a crankshaft of an internal combustion engine - Google Patents

Abstract

The invention relates to a method for determining a direction of rotation (α, α) of a shaft (17), in particular a crankshaft (17 ') of an internal combustion engine (112), comprising an electric machine (30) comprising a rotor (32) and a Stator (33) with at least one phase winding (U, V, W) is coupled directly or translated, wherein at least one phase signal (Uu, Uv, Uw, lu, Iv, I) of the electric machine (30) at least one value (W , W, W, W, W, Wuo, Wvo, Wwo) occurring at least once per revolution of the rotor (32), wherein an occurrence time of at least one value (W, W, W, W, W, W , W, W, W) of a phase signal (U, U, U, I, I, I) and at least one further criterion for determining the direction of rotation (α, α) is used. Furthermore, the invention relates to a corresponding arithmetic unit, which is set up to carry out the method, and to a computer program for carrying out the method.

Description

The present invention relates to a method for determining a direction of rotation of a shaft, in particular a crankshaft, which is coupled to an electric machine comprising a rotor and a stator with at least one phase winding, directly or translated.

State of the art

The rotational angular position and the rotational speed of the crankshaft of an internal combustion engine are essential input variables for many functions of the electronic engine control. For their determination, marks may be provided on a body rotating with the crankshaft of the internal combustion engine at equal angular intervals. The passing of a mark as a result of the crankshaft rotation, can be detected by a sensor and passed as an electrical signal to an evaluation electronics.

For the respective rotational angle position of the crankshaft, this electronics determines the respective marked signal for the marking or measures a time difference between two markings and can determine the angular velocity and therefrom the rotational speed due to the known angular distance between two markings. In motor vehicles, in particular motorcycles, mopeds or motorcycles, the markings can be provided, for example, by teeth of a metal gear, a so-called donor wheel, which cause a change in the magnetic field as a result of their movement in the sensor. A gap of some teeth can serve as a reference mark for the detection of the absolute position.

While cars usually use 60-2 teeth (uniform distribution of 60 teeth, with two left out), motorcycles and motorcycles, for example, also use 36-2, 24-2 or 12-3 teeth. In this indirect principle of the rotational speed determination or rotational angular position determination of the crankshaft, the resolution of the rotational speed signal or the absolute detection of the rotational angular position is determined by the number of teeth and by a reliable detection of the reference mark. These systems are typically invariant with respect to the direction of rotation, which is why the direction of rotation of the shaft, or a change in the direction of rotation of the shaft alone based on the signals caused by the teeth can not be determined.

In any modern vehicle with internal combustion engine, a generator is installed, which is driven by the rotation of the crankshaft. This provides electrical signals and is used to supply the vehicle with electrical energy and charging the vehicle battery. The intended operation of a vehicle without this generator, is not possible or only for a short time.

A use of the electrical output variables of a driven via the crankshaft electric machine (generator), for example, in the EP 0 664 887 B1 used for speed determination. For this purpose, a phase of the generator is provided as a reference to which a pulsating DC voltage is applied.

It would therefore be desirable to provide a possibility, even without the use of additional components, a direction of rotation of the rotor of the electric machine or the crankshaft of the internal combustion engine, which is used to control an internal combustion engine to obtain.

Disclosure of the invention

According to the invention, a method with the features of claim 1 is proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

In a method for determining the direction of rotation of a shaft, preferably a crankshaft of an internal combustion engine, in particular an internal combustion engine of a motorcycle, which with an electric machine comprising a rotor and a stator with at least one phase winding directly or translated, but with a fixed angular relation between the rotor electric machine and the crankshaft of the internal combustion engine, is determined from at least one phase signal of the electric machine at least one value, which occurs in each case at least once per revolution of the rotor, wherein an occurrence time of at least one value of a phase signal and at least one further criterion for determining the direction of rotation of the shaft is used.

It is understood that the shaft may be either the crankshaft of the internal combustion engine or the shaft of the rotor, which is fixedly coupled to the crankshaft of the internal combustion engine for transmitting rotary motion. In the context of the invention, the at least one value is associated with a rising edge of the phase signal, with a falling edge of the phase signal and / or with zero crossings of the phase signal, wherein the rising edges, and / or the falling edges of the phase signal and / or the zero crossings of the Phase signal can be used to determine the direction of rotation of the shaft. These Embodiment is particularly advantageous because both rising edges, falling edges and zero crossings of the phase signal in the voltage signals of the electric machine are particularly easy and accurate detectable, which makes a determination of a direction of rotation of the shaft accordingly predictable.

The method is particularly suitable for detecting reverse rotations of the crankshaft of the internal combustion engine, which may occur during operation of the internal combustion engine or deactivation of the internal combustion engine. Without the method according to the invention, the knowledge about the exact position of the crankshaft is lost in a reverse rotation of the crankshaft, since such a reverse rotation of the crankshaft is not readily recognizable due to the known from the prior art, typically rotationally invariant systems. If a reverse rotation of the crankshaft, for example, in the operating state "engine stop" - engine is deactivated - on, the internal combustion engine at the subsequent start longer, z. Example, be coupled by a coupled to the engine starter, before again a fiducial on the speed sensor is reached, whereby a synchronization state is triggered in the engine control unit and a proper injection and ignition can be done in the renewed power stroke.

This delays the starting process and the time to reach a desired speed, as z. B. may be in idle state, unnecessary. Thus, the method has the advantage that within fractions of a total revolution of the crankshaft reverse rotation of the same can be seen, whereby always the exact crankshaft position is recorded during operation and a startup can be done correspondingly faster. In this way, a desired speed of the internal combustion engine can be achieved even faster.

Special advantages unfolds the method also for motorcycles or other light motorcycles. A corresponding motor protection can be used within the scope of the invention e.g. be ensured that, for example, when starting the internal combustion engine, at least one of the pistons does not overcome the ignition TDC and turns back. In this state, there should be no ignition of the fuel-air mixture in the piston, since otherwise the ignited mixture would discharge into the fresh air path after the backward compression stroke, whereby a corresponding damage of the same could be caused.

As already mentioned, the method can basically be used to determine the direction of rotation of the shaft, in particular the crankshaft of an internal combustion engine. In particular, however, can reverse rotation of the crankshaft, against the conditional by the internal combustion engine preferred direction of rotation, be reliably detected. Such rotational movement contrary to the usual preferred direction of the internal combustion engine, hereinafter referred to as reverse rotations, z. B. occur when switching off the engine. This happens because the crankshaft of the internal combustion engine before the final rest position after stopping, for example, the ignition experiences a return torque, which is caused by at least one of the cylinders of the internal combustion engine, which act as a gas spring. Another situation in which it can come to a reverse rotation of the crankshaft is a movement of the vehicle in the off state of the internal combustion engine with the drive train closed. This can lead to an adjustment of the rest position assumed during deactivation of the internal combustion engine, which must first be synchronized again when the engine is restarted as part of the speed detection by means of the control unit in order to adjust the actual position of the crankshaft accordingly.

Even with an aborted engine start, in which an intervening in the engine starter, is spouted so early that at least one of the pistons does not overcome the ignition TDC and consequently does not start the entire engine, can to a corresponding reverse rotation due to in the at least come a cylinder compressed air-fuel mixture (gas spring).

Even during operation of the internal combustion engine, it can come to a reverse rotation of the crankshaft in particular at idle at low speed of the internal combustion engine when passes through a sudden opening of the throttle too large a filling in at least one of the combustion chambers. In particular, in engines with a high compression ratio and / or low cylinders and / or a large cylinder volume, such conditions can be easily adjusted.

Such states can be detected simply and reliably in the context of the aforementioned method. The aforementioned method is particularly suitable for systems in which a speed detection is already implemented in the context of the electric machine.

In particular, the disadvantages described in the context of the aforementioned operating states can be prevented by means of the method, wherein advantageously only system components, in the form of an electric machine and / or a further speed sensor, in particular an inductive speed sensor, can be used.

In a further preferred embodiment of the invention is used as another criterion of the waveform of the speed sensor, in particular an inductive speed sensor, for determining the direction of rotation of the shaft. This embodiment is advantageous because even systems with an inductive speed sensor and an electric machine, which is always present in such systems for supplying power to a vehicle electrical system, can be used to reliably detect a reverse rotation of the internal combustion engine. In this case, it is basically sufficient if the electric machine is a single-phase electric machine, and based on the one phase, the phase signals and the signals of the speed sensor are used to determine the direction of rotation of the crankshaft. This makes this embodiment particularly advantageous since the requirements for the electric machine are reduced to a minimum, since only one phase for determining the direction of rotation of the crankshaft in combination with the inductive speed sensor is required. The electric machine may also be a multi-phase electric machine, wherein only one or two of the phases and the signal of a corresponding speed sensor are used to determine a reverse rotation of the internal combustion engine.

In a further preferred embodiment, in the presence of a first gradient type of slope in the inductive speed sensor waveform in the time domain after occurrence of the value associated with the generator phase voltage, forward rotation of the shaft or in the presence of another gradient slope type in the waveform of the induced voltage of the speed sensor in the time domain after the occurrence of the value of the at least one phase signal, which is different from the first Gradientenart, closed on a reverse rotation of the shaft. The respective gradients are positive or negative gradients in the waveform. Depending on the phase position of the signal curves of the induction transmitter or the phase signals, positive or negative gradients can thus be associated with a forward or reverse rotation. A forward rotation, as already defined, is the usual preferred direction of rotation of the internal combustion engine during its operation. A reverse rotation of the shaft is thus a rotational movement in the opposite direction to the preferred direction. The gradient of the slope is the respective slope in the waveform of the respective signals, i. Waveform of the induced voltage or waveform of the respective phase signal. This embodiment is particularly advantageous since a corresponding rotational movement can be recognized from it particularly simply and reliably.

In a further embodiment, at least two further values of the phase signal are used as a further criterion, wherein the first value and the two further values are derived from respectively different phase signals, wherein based on the chronological order of the first value and the two further values on the direction of rotation of the shaft is closed. Since the occurrence of the phase signals in a three-phase or multi-phase electric machine is not invariant under a change in the direction of rotation, it can be concluded that there are forward or reverse rotation of the shaft due to the sequence of characteristic values of the various phase signals. The above-mentioned embodiment is particularly advantageous because only on the basis of the phase signals of the electric machine on the direction of rotation of the rotor and thus also on the direction of rotation of the shaft connected to the rotor, in particular the crankshaft of the internal combustion engine, can be closed without it another sensor, in particular an inductive speed sensor required.

In a further embodiment, at least one further value of the phase signal is used as a further criterion, wherein the first value and the second value are derived from respectively different phase signals, the flank (rising or falling) of the second one being based on the edge type or the type of gradient Value that follows the direction of rotation in time to the first value. Since the occurrence of the phase signals in a three-phase or multi-phase electric machine is not invariant under a change in the direction of rotation, the direction of rotation can be deduced due to the edge type of the second value. The aforementioned embodiment is advantageous if not all phases of a generator for speed and position detection of the shaft to be used, but only the information of the direction of rotation to be extracted.

In a further preferred embodiment, if there is an immediate timing of the first value, the second value, and the further value, the shaft is rotated backward, or if there is an immediate timing of the first value, the further value, and the second value Forward rotation of the shaft closed. The above-mentioned embodiment is particularly advantageous because it is possible to deduce the direction of rotation of the shaft only on the basis of a sequence of the occurrence of the respective values relative to one another, as a result of which a particularly simple and robust recognition of the shaft is possible Direction of rotation of the electric machine can be implemented.

In a further preferred embodiment of the method, the direction of rotation of the crankshaft is used for controlling the internal combustion engine, in particular for controlling the ignition and / or the injection of at least one cylinder of the internal combustion engine. A detection and processing of the phase signals of the electric machine, in particular by an engine control unit, can be used in accordance with the control of the ignition or the torque control of the internal combustion engine in a control unit of the internal combustion engine. A corresponding control in a higher-level control device, in particular an engine control unit, is particularly preferred, since this is already present and can be accessed according to the system resources, whereby the corresponding functionalities for detecting the direction of rotation and for controlling the internal combustion engine can be summarized in a control unit, which results in synergy effects with regard to a shared rule and communication structure.

For this purpose, the used arithmetic unit, which is preferably designed as a motor control device for the internal combustion engine, a corresponding integrated circuit and / or stored on a memory computer program which is or are set up to carry out the method steps described above or are.

The implementation of the method in the form of a computer program, which is preferably stored on a data carrier, in particular a memory in the form of software, and in the arithmetic unit for performing the method is available or the provision of an integrated circuit, in particular an ASIC (Application Specific Integrated Circuit ), is advantageous because this causes very low costs, especially if an executive controller is still used for other tasks and therefore already 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.

list of figures

• 1 schematically shows a sensor wheel with sensor, in particular for speed determination;
• 2a to c show a schematic representation of an electric machine coupled to an internal combustion engine ( a . b ), and the associated signal curves ( c );
• 3 schematically shows an electric machine, with the corresponding associated phase signals;
• 4a and 4b show possible voltage curves of the phases of a three-phase electric machine (a) and an enlarged representation of one of the phases (b);
• 5 shows a system comprising an electric machine and an inductive sensor for detecting the direction of rotation of the crankshaft of the internal combustion engine, according to a first embodiment;
• 6 shows a system comprising a multi-phase electric machine for detecting the direction of rotation of the crankshaft of the internal combustion engine, according to a further embodiment;
• 7a . 7b show phase curves of various phase signals of the electric machine and a signal of an inductive speed sensor in a forward rotation (a) or a reverse rotation (b) of the rotor of the electric machine; and
• 8a . 8b show phase curves of different phase signals of the electric machine 7a and 7 b in an enlarged, idealized representation.

Embodiment (s) of the invention

In 1 are schematically a donor wheel 20 and an associated inductive sensor 10 a speed sensor G shown, as used in the prior art for speed determination or for the approximate determination of the rotational angular position of the crankshaft. The donor wheel 20 is firmly connected to a crankshaft of an internal combustion engine and the sensor 10 is fixed in a suitable place.

The donor wheel 20 , usually made of a ferromagnetic material, has teeth 22 on the outside at a distance 21 between two teeth 22 are arranged. At one point on the outside, the sender wheel points 20 a gap 23 in the length of a predetermined number of teeth. This gap 23 serves as a reference mark for detecting an absolute position of the encoder wheel 20 ,

The sensor 10 has a bar magnet 11 on, on which a soft magnetic pole pin 12 is appropriate. The pole pin 12 in turn is from an induction coil 13 surround. When the encoder wheel rotates, teeth alternate 22 and between each two teeth lying voids on the induction coil 13 of the sensor 10 past. As the donor wheel and thus the teeth 22 are made of a ferromagnetic material, a signal is induced during rotation in the coil, which between a tooth 22 and an air gap can be distinguished.

By correlating a time difference between two teeth at an angle included by these two teeth, the angular velocity and, moreover, also the corresponding angular position of the crankshaft can be approximately calculated.

At the gap 23 the induced signal in the induction coil has a different course than in the otherwise alternating with empty spaces teeth 22 , In this way, an absolute position mark, but only in relation to a full crankshaft revolution, possible. Alone from the output signals in the form of an induced voltage U _Ind (cf 7a and 7b) the direction of rotation of the Gebberrads is not readable, because the induced voltage U _Ind Due to geometry, it is invariant under changes of the direction of rotation.

In 2a is an internal combustion engine 112 pictured, to which directly or translated coupled an electric machine 30 Tied, the electric machine 30 through the crankshaft 17 ' the internal combustion engine 112 is driven. Thus, the speed indicates _gene the electric machine 30 and the speed n _BKM the crankshaft 17 ' and the angular position θ _{1 of} the rotor of the electric machine 30 and the rotational angular position θ of the crankshaft 17 ' a fixed relationship to each other. The electric machine 30 is also a charge controller LR assigned to the battery B within the electrical system 110 , according to the remaining capacity of the battery B , energized.

Furthermore, a computing unit, in particular an engine control unit 122 provided the data over a communication connection 124 with the electric machine 30 or with the internal combustion engine 112 exchanged and set up, the internal combustion engine 112 and the electric machine 30 to control accordingly. Also external sensor data, such as a sensor 10 for inductive detection of the speed n _BKM the internal combustion engine 112 or the preferably firmly coupled electrical machine 30 ( _EM ) can also be in the communication link 124 Being integrated, being based on that of the electric machine 30 and / or the other sensor data of the sensor 10 , the engine control unit 122 Control signals for controlling the internal combustion engine 112 sent to the same. The direction of rotation α ₊ . α _- of the rotor 32 and its wave 17 is also indicated, where α ₊ a forward rotation in the preferred direction of the internal combustion engine 112 and α _- describes a reverse rotation in the opposite direction. The rotational angular position θ of the crankshaft 17 ' or θ _{1 of} the rotor 32 are also indicated.

In 2 B is the electric machine 30 again schematically shown in enlarged form. The electric machine 30 has a shaft 17 having rotor 32 with a field winding and a stator 33 with stator windings U . V . W on. It is therefore a foreign-excited machine, as is customary especially in motor vehicles. In particular, for motorcycles, especially in small and light motorcycles, however, motors are usually used with permanent magnets, ie permanent-magnet electric machine. In principle, both types of electrical machines can be used within the scope of the invention, wherein in particular the method according to the invention does not depend on the use of the respective type of electrical machine, for example a permanently excited electrical machine or a separately excited electrical machine.

Exemplary is the electric machine 30 designed as an alternator, in which three mutually phase-shifted by 120 ° phase voltage signals are induced. Such three-phase generators are commonly used as generators in modern motor vehicles and are suitable for carrying out a method according to the invention. In the context of the invention, basically all electric machines can be used independently of the number of their phases, wherein in particular the method according to the invention does not depend on the use of the respective type of electrical machine.

The three phases of the alternator 30 are with U . V . W designated. About as plus diodes 34 and minus diodes 35 trained rectifying element, the strained at the phases voltages are rectified. Between the poles B + and B- is thus a generator voltage U _G , where the negative pole is grounded. From such a three-phase generator 30 For example, a battery B or other consumers within the electrical system 110 provided.

In 2c are three diagrams showing the associated voltage waveforms with respect to the rotation angle of the rotor 32 the electric machine 30 demonstrate. The upper diagram shows the voltage curves at the phases U . V . W entered. It is generally understood that the numbers and ranges of values given in this diagram and in the subsequent diagrams are merely exemplary, and therefore do not limit the invention in principle.

In the middle diagram is the generator voltage U _G , which is formed by the envelopes of the positive and negative half-waves of the voltage waveforms U, V, W shown.

Finally, in the lower diagram is the rectified generator voltage U _G- (see. 2a) , together with the RMS value U _Geff this generator voltage U _G- that between B + and B- abutment shown.

In 3 is schematically the stator 33 with the phases U . V . W , as well as the plus diodes 34 and minus diodes 35 out 2 B shown. Basically, it is understood that the rectifier elements shown here in the form of positive diodes 34 and minus diodes 35 in the case of an active rectifier also as transistors, in particular MOSFETs (metal oxide semiconductor field effect transistor) may be formed (not shown). In addition, the following nomenclature of the occurring voltages and currents is shown.

U _U . U _V . U _W alternatively denote the phase voltages of the associated phases U . V . W as between an outer conductor and the neutral point of the stator 33 fall off. UUV . And many more . U _WU , denote the voltages between two phases or their associated outer conductors.

I _U . I _V . I _W denote the phase currents from the respective outer conductor of a phase U . V . W to the star point. I denotes the total current of all phases after rectification.

In 4a are now three phase voltages uu . uv . Uwmit Potential reference to B- shown in three diagrams versus the time, as they occur in a generator with a Außenpolläufer with six permanent magnets. This illustration of an electric machine 30 , with a three-phase stator winding 33 is merely to be seen by way of example, wherein in principle, without limitation of generality, the method according to the invention can also be carried out on a generator with a correspondingly needs-based number of phases or permanent magnets or exciter coils. Likewise, instead of a star connection of the stator coils, it is also possible to select a triangular connection or other types of connection.

In an electric machine 30 with current output, is the course of the phase voltages U _U . U _V . U _W in a first approximation rectangular. This is explained in particular by the fact that either the plus or the minus diodes conduct in the direction of flow through the generator voltage, and therefore either approximately 15-16 volts (battery charging voltage at 12V lead-acid accumulator and voltage at plus diodes), or minus 0.7-1 Volt (voltage to negative diodes) is measured. Reference potential of the measurement is in each case mass. Other reference potentials such as the star point of the stator can also be selected. However, these deviate waveforms do not change the evaluable information, their extraction and evaluation.

Basically, the phase signals ( U _U . U _V . U _W . I _U . I _V . I _W ) can be won in different ways. For example, it is possible to determine the phase voltages against one another ( UUV . Uuw . Uwu ), a determination of the phase voltages across the diodes of a connected rectifier against its output terminals ( B + B- ), if the stator of the electrical machine is in star connection with a detectable star point, a consideration of the output voltage of the strands against the neutral point ( uu . uv . uw ) or a comparable evaluation of the phase currents.

In 4b are the phase voltages uu . uv . uw out 4a plotted together in a diagram. Here, the uniform phase offset can be clearly seen.

During a full turn of the rotor 32 the electric machine 30 , the voltage signals are repeated six times by six magnets (in particular permanent magnets), the so-called pole pairs. Accordingly occur per phase, ie per phase voltage uu . uv . uw per revolution of the rotor 32 six falling flanks FL _D and six rising flanks Flu (for the respective phases FLuu . FLvu . FLwu and FL _UD . FL _VD . FL _WD ) on.

These flanks define an angular section, namely exactly the angular section which is covered by the magnets along the radial circumference of the stator. Accordingly, it is possible to detect the respective flanks Flu , or. FL _D , with knowledge of an absolute reference point per revolution, for example, based on a reference magnet with deviating from the other magnets characteristic of the phase voltage uu . uv , Uwgekeinsigns be determined.

With suitable means now both the falling edges can FL _D as well as the rising flanks FLu be recognized. For example, a TTL signal can be generated for each phase voltage by means of a so-called Schmitt trigger and sent to a control unit, in particular to the engine control unit 122 to be transmitted. The required Schmitt triggers can either be integrated in the control unit or in the control electronics, for example a control unit, a controller for the battery voltage and / or in the case of an active rectifier, in the respective generator controller or externally assigned to this. The individual TTL signals can in particular for the case of using a control device, in particular an engine control unit 122 (see. 2a) , via a respective line, or summarized by an upstream combination electronics or other suitable, via only one data line 124 (see. 2a) be transmitted.

In 4b are the ends of the respective falling edges of the phase voltage U _U . U _V . U _W each values W _U . W _V . W _W assigned as well W _ud . W _Vd . W _Wd be designated. Likewise, corresponding values can also be given to the rising edges FLu _WUu . W _Vu . W _Wu be assigned. These values can be used to detect the direction of rotation α ₊ . α _- of the rotor 32 or the coupled thereto crankshaft 17 ' serve. Also a recognition of the angular position α ₁ of the rotor 32 from the plateau areas of the phase signals or other areas in between is possible. Likewise, the values can also be used, based on time differences Δt ₁ . Δt ₂ . Δt ₃ , the speed of the electric machine 30 to investigate. The direction of rotation α ₊ is hereinafter referred to as forward direction without restriction of generality. This is the typical direction of rotation of an internal combustion engine 112 or the electrical machine coupled thereto 30 during operation. The direction of rotation α _- is the corresponding opposite direction and is referred to as the reverse direction.

This occurs in a uniform arrangement of the six permanent magnets in the electric machine 30 , a total of 18 falling flanks FL _d and thus 18 associated values per revolution at equal distances from each other. While a time difference Δt ₁ . Δt ₂ , or Δt ₃ Thus, an angle 360 ° / 18 = 20 ° is swept over. As already mentioned, this can also be used to detect the direction of rotation α ₊ . α _- of the rotor 32 are used, wherein the 20 ° determined by way of example represents the detectable angle increment. In addition, this also allows the angular velocity ω _i determine. This results from ω _i = 20 ° / Δt _i and the associated speed _i from n _i = ω _i / 360 ° ▪ 60s / min in revolutions per minute.

It is basically understood that as an alternative to the falling edges FL _D also the rising flanks FLu of the respective phases U . V . W to determine the direction of rotation α ₊ . α _- of the rotor 32 as well as to determine the instantaneous speed _gene the electric machine 30 are usable. Due to the double number of values per revolution, this results in a higher resolution, both the direction of rotation α ₊ . α _- of the rotor 32 , as well as the speed _gene , In addition, the edges of the phases can be evaluated in a variety of other ways, for example, by the time intervals of the rising edges Flu and falling flanks FL _D each of the same phases or of the respective phases to each other or by the time interval of rising edges Flu or falling flanks FL _D the same phase, or all phases together.

In addition to the rising flanks Flu and falling flanks FL _D can for determining as such or an improved resolution of the determination of the direction of rotation α ₊ . α _- of the rotor 32 or a speed detection _gene , also the zero crossings W _U0 . W _V0 . W _W0 the phase signals Uu, Uv, Uw are used.

The direction of rotation α ₊ . α _- of the rotor 32 and its wave 17 and thus the rotational angular position θ of the crankshaft 17 ' or θ _{1 of} the rotor 32 , can be derived from the electrical signals of the electric machine 30 , in particular the phase voltages uu , Uv, Uw, and the associated phase currents I _U . I _V . I _W in isolation, according to a first embodiment (see. 6 ) and / or as a combination of at least one of the phase voltages U _U . U _V . U _W , or the associated phase currents I _U . I _V . I _W and the voltage signal U _ind a speed sensor 10 , According to another embodiment (see. 5 ), determine.

It is understood that other pole pairs can occur, the number of magnets, rising and falling edges changes accordingly to the above embodiment.

In 5 is the topology of a first embodiment for determining the direction of rotation α ₊ . α _- of the rotor 32 the electric machine 30 specified. This topology has a speed sensor G comprising an inductive sensor 10 and a donor wheel 20 used to determine the speed of the crankshaft of the internal combustion engine 112 is set up (compare 1 ). The signals U _ind of the speed sensor G are sent to an engine control unit 122 transmitted for further processing. Furthermore, the electric machine has 30 , which is present as a three-phase electric machine with the phases U, V and W is formed, the downstream rectifier 34 . 35 (see 2 B) and a corresponding charge controller LR for a battery B on which the corresponding components, in particular the control unit 122 supplied with electrical energy. Between the charge controller LR and the engine control 122 is a data connection 124 provided that either pre-processed speed data n from the phase voltages or the respective phase signals directly to the engine control unit 122 passes. Basically, it should be noted that for the in 5 described embodiment for detecting the direction of rotation α ₊ . α _- On the basis of the speed sensor G and the electric machine, an electric machine with at least one phase is required, whereby the number of phases, such as presently indicated U, V, W could still be reduced.

In 6 is described a further topology according to another embodiment, in which for detecting the direction of rotation α ₊ . α _- the electric machine 30 only on the phase signals U . V . W is used. Incidentally, the description of the respective component in the description of the embodiment will be made 5 directed.

In 7a are the waveforms of the phase voltages U _u . U _v . U _w and by the speed sensor 10 obtained induction signal U _ind for a backward rotation α _- ( 7a) and for a forward-turning α ₊ (see 7b) rotor 32 an electric machine shown. As characteristic values for the respective phase signals U _u . U _v . U _w In this case, the zero crossings of the phase voltage W _u0 . W _v0 . W _w0 used. In principle, however, the ascending or falling edges of the phase voltages (cf. . as a characteristic value for the phase signal U _u . U _v . U _w be used.

Here it can be seen that the zero crossings in a reverse-rotating rotor 32 in reverse direction α _- the characteristic periodic sequence of zero crossings W _u0 to W _w0 the respective phases U . V . W . U, V . W . U . V . W with increasing time. When the rotor rotates forward 32 in the so-called forward direction α ₊ is the time sequence of the zero crossings W _u0 to W _w0 U . W . V . U . W . V etc. Based on this characteristic, according to the other embodiment, the direction of rotation of the rotor can be assured 32 and thus the crankshaft 17 ' the internal combustion engine 112 be determined according to the further embodiment.

According to the further embodiment may from 7a be deduced that a reverse direction α _- is present, for example, when the zero crossing W _u0 a zero crossing W _v0 with falling gradient follows. Conversely shows 7b that a forward direction α ₊ is present when on the zero crossing W _u0 a zero crossing W _v0 with increasing gradient follows.

For better illustration of the phase signals relative to each other, the phase voltages became U _u . U _v . U _w and the respective zero crossings in idealized form for forward rotation α ₊ in 8a and in 8b for a reverse rotation α _- of the rotor 32 once again magnified and idealized shown as a course of sinusoidal curves. In the same way, the other characteristic values can be left _WUu . W _ud . W _Vu . W _Vd . W _Wu . W _Wd for direction of rotation detection α ₊ . α _- use.

According to the first embodiment, the determination of the rotational direction α ₊ , α _- on the basis of in 5 illustrated embodiment illustrated.

In the 7a and b is an angle offset β or β indicating the displacement between the coordinate system of the inductive signal U _ind and the phase position of the phase voltages U _u . U _v . U _w the electric machine 30 indicates. It can be seen here that the signal voltage U _ind of the speed sensor 10 after the zero crossing of an exemplarily selected phase, in this case U for forward-rotating shaft U ₊ always increases and with reverse rotating shaft U - always drops. Assuming now that in principle a phase shift between the induced voltage U _ind and the phase position of the respective phases is present in the generator, ie, β ≠ 0, it can, on the basis of the aforementioned correlation of the zero crossings of the respective phase and the temporally subsequent gradient in the induced voltage signal U _ind on a forward turn α ₊ or a reverse rotation α _- getting closed. Basically, this is understood to be the detection of a forward or reverse rotation α ₊ or. α _- the wave any disturbances, such. B. the exact knowledge of the Polradwinkels can be neglected in a load generator in the first approximation, or if known are also considered.

In some cases, the signal voltage U _ind of the speed sensor 10 only on zero crossings with a Gradientart, only falling or only rising, evaluated. If, for example, only gradients of increasing nature are evaluated, it follows 7a that in the reverse direction α _- a much greater time between a zero crossing of a generator phase and the following zero crossing of the signal voltage U _ind is as between a zero crossing of the signal voltage U _ind and the subsequent zero crossing of a generator phase. Out 7b results directly that for the reverse direction of rotation (forward direction of rotation α ₊ ) there is an inverse ratio of the time intervals. Thus, even in cases where only one Gradientenart the signal voltage U _ind of the speed sensor 10 is evaluated, be closed in combination with the signals of at least one generator phase to the direction of rotation.

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Cited patent literature

• EP 0664887 B1 [0006]

Claims (11)

Method for determining a direction of rotation (α ₊ α _-) of a shaft (17), in particular a crankshaft (17 ') of an internal combustion engine (112) with an electric machine (30) comprising a rotor (32) and a stator ( 33) with at least one phase winding (U, V, W) is coupled directly or translated, wherein at least one phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) of the electric machine (30) at least a value ( _WUu , W _Ud , W _Vu , W _Vd , W _Wu , W _Wd , W _U0 , W _V0 , W _W0 ) which occurs at least once per revolution of the rotor (32), wherein a time of occurrence of at least one Value ( _WUu , W _Ud , W _Vu , W _Vd , W _Wu , W _Wd , Wuo, Wvo, Wwo) of a phase signal (Uu, Uv, Uw, Iu, Iv, I _W ) and at least one further criterion (K) for determining the direction of rotation (α ₊ , α _- ) of the shaft (17) is used. Method according to Claim 1 Wherein the at least one value (W _Uu, W _Ud, W _Vu, W _Vd, W _Wu, W _Wd, Wuo, Wvo, WWo) having rising flanks (Fl _Uu, Fl _Vu, Fl _Wu) of the phase signal (U _U, U _V , U _W , I _U , I _V , I _W ), falling edges (Fl _Ud , Fl _Vd , Fl _Wd ) of the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) and or zero crossings (Fl _Uo , Fl _V0 , Fl _W0 ) of the phase signal (Uu, Uv, Uw, Iu, Iv, I _W ) are associated, wherein the rising edges (Fl _Uu , Fl _Vu , Fl _Wu ) of the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) and / or the falling edges (Fl _Ud , Fl _Vd , Fl _Wd ) of the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) and / or the zero crossings (Fluo, Flvo, Flwo) of the phase signal (Uu, Uv, Uw, Iu, Iv, I _W ) are used to determine the direction of rotation (α ₊ , α _- ). Method according to Claim 1 or 2 , wherein as a further criterion (K) of the waveform (U _ind ) of a speed sensor (G), in particular an inductive speed sensor (10), for determining the direction of rotation (α ₊ , α _- ) of the shaft (17) is used. Method according to Claim 3 wherein, in the presence of a first gradient of the slope in the waveform (U _ind ) in the time domain after the occurrence of the value (W _Uu , W _Ud , W _Vu , W _Vd , W _Wu , W _Wd , W _U0 , W _V0 , W _W0 on a forward rotation (α ₊ ) of the shaft (17) or in the presence of another gradient of the slope in the waveform (U _ind ) in the time domain after the occurrence of the value (W _Uu , W _Ud , W _Vu , W _Vd , W _Wu , W _Wd , W _U0 , W _V0 , W _W0 ) on a reverse rotation (α _- ) of the shaft (17) is closed. Method according to one of the preceding claims, wherein as an additional criterion (K) at least two further values (W _Uu, W _Ud, W _Vu, W _Vd, W _Wu, W _Wd, W _U0, Wvo, WWo) are used, wherein the first Value (W _Uu , W _Ud , Wuo) and the two other values (W _Vu , W _Vd , W _Wu , W _Wd , W _V0 , W _W0 ) from respectively different phase signals (Uu, Uv, Uw, lu, Iv, I _W) are derived, which (based on the temporal order of the first value W _{U U,} W _Ud, Wuo) and the other two values (W _Vu, W _Vd, W _Wu, W _Wd, W _V0, W _W0) (to the direction of rotation α ₊ , α _- ) of the shaft (17) is closed. Method according to Claim 5 wherein, in the presence of an immediate time sequence of the first value ( _WUu , W _Ud , W _U0 ), the second value (W _Vu , W _Vd , W _V0 ) and the further value (W _Wu , W _Wd , W _W0 ) on a reverse rotation (α _- ) of the shaft (17) or in the presence of an immediate temporal sequence of the first value (W _Uu , W _Ud , W _U0 ), the further value (W _Wu , W _Wd , W _W0 ) and the second Value (W _Vu , W _Vd , W _V0 ) on a forward rotation (α ₊ ) of the shaft (17) is closed. Method according to one of the preceding claims, wherein as a further criterion at least one further value (W _Uu , W _Ud , Wuo) of the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) is used, wherein the first value (W _Uu , W _Ud , W _U0 ) and the second value (W _Uu , W _Ud , Wuo) are derived from respectively different phase signals (Uu, Uv, U _W , I _U , I _V , I _W ), wherein based on the edge type, which is associated with the second value ( _WUu , W _Ud , W _U0 ), which follows in time to the first value (W _Uu , W _Ud , Wuo), the direction of rotation (α ₊ , α _- ) closed becomes. Method according to one of the preceding claims, wherein the direction of rotation (α ₊ , α _- ) of the shaft (17) for controlling the internal combustion engine (112), in particular for controlling the ignition and / or the injection of at least one cylinder of the internal combustion engine (112) used becomes. Arithmetic unit, preferably an engine control unit (122) for an internal combustion engine (12), which is configured 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. Computer program that causes a computing unit, a method according to one of Claims 1 to 8th when executed on the computing unit. Machine-readable storage medium with a computer program stored thereon Claim 10 ,

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