EP2867681A2

EP2867681A2 - Method for determining a speed of a compressor

Info

Publication number: EP2867681A2
Application number: EP13726179.8A
Authority: EP
Inventors: Michael Baeuerle; Michael Nau
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2012-07-02
Filing date: 2013-05-28
Publication date: 2015-05-06
Also published as: US20150276785A1; CN104541171A; DE102012211425A1; WO2014005767A2; WO2014005767A3

Abstract

The invention relates to a method for determining a speed (n_ATL) of a compressor (20), in particular of a turbo charger (20) of an internal combustion engine (10). In the internal combustion engine (10) a flow and/or a pressure of air fed to the internal combustion engine (10) is detected and an associated flow signal (U_LM) and/or pressure signal (U_P) is produced. The speed (n_ATL) of the compressor (20) is determined from a periodic variation (U_n) of at least one portion of the flow signal (U_LM) and/or of the pressure signal (U_P). The flow and/or the pressure is captured upstream the compressor (20). The invention further relates to an internal combustion engine (10), which comprises a compressor (20) that is arranged in an air supply channel (16) for supplying air to a combustion chamber (14) of the internal combustion engine (10), a pressure sensor (34) for detecting a pressure of the air supplied to the combustion space (14) and for producing an associated pressure signal (U_P) and/or a flow sensor (62) for detecting a flow of the air supplied to the combustion space (14) and for producing an associated flow signal (U_LM). The internal combustion engine (10) further comprises an evaluation circuit for determining a speed (n_ATL) of the compressor (20). The speed (n_ATL) of the compressor can be determined from a periodic variation (U_N) of at least one portion of the flow signal (U_LM) and/or the pressure signal (U_P). The flow sensor (62) and/or the pressure sensor (34) in the air supply channel (16) are arranged upstream of the compressor (20) in a common housing.

Description

Description title

Method for determining a speed of a compressor Prior art

In internal combustion engines, for example gasoline and diesel piston engines, the air charge in a combustion chamber of the internal combustion engine is increased by the use of a compressor, such as an exhaust gas turbocharger to increase the power. The pressure with which the air is forced into the combustion chamber of the internal combustion engine is also referred to as boost pressure and generally measured in the vicinity of the combustion chamber by a pressure sensor. The pressure signal is supplied to a closed loop, which controls the exhaust gas turbocharger and thus sets a desired boost pressure.

In particular exhaust gas turbocharger have a pronounced time constant, so react relatively slow to changed control signals, which makes it difficult to control the boost pressure. Therefore, it is advantageous if a direct state variable of the exhaust gas turbocharger to be controlled is detected. Particularly suitable for this is the speed of the

Compressor of the exhaust turbocharger. The knowledge of the compressor speed is of particular interest, since during operation of the turbocharger a certain maximum speed threshold must not be exceeded, otherwise the turbocharger may be damaged due to the exceeding of critical stresses in the compressor wheel, a deformation of the compressor wheel, resulting in a strip of the Rotor leads to the housing.

The compressor speed can be calculated in principle by means of a known compressor map, provided certain variables, such as the pressure before and after the compressor, the air mass flow through the compressor and the temperature in front of the compressor are known. Based on these quantities, the location of an operating point in the Compressor map and thus the speed of the compressor known without a sensor for speed determination must be used.

To limit the speed of the exhaust gas turbocharger is usually a

Ambient pressure sensor used. Typically, this sits in the engine control unit to keep the wiring costs low. The problem here is the fact that different load conditions of the air filter, such as moisture, ice or dirt, which are relevant to the compressor of the exhaust gas turbocharger

Do not take air pressure into account. Therefore, in some cases, this ambient pressure sensor is integrated into the air filter box. In the integration of the

Ambient pressure sensor in the air filter box, however, is opposite to the mounting in the

Engine control unit requires additional cabling. Other, the exhaust gas turbocharger speed determining factors, such. B. Tolerances of the pressure sensors, d. H. Pressure sensors for determining the pressure of the environment and the boost pressure, and Liedergradtoleranzen the engine are and can not be detected.

Accordingly, the above-described estimation of the rotational speed of the exhaust gas turbocharger is associated with significant inaccuracies. These are in addition to the tolerances of the above-mentioned sensors, the inaccuracies in the compressor map, tolerances of

Timing or modeling inaccuracies. Furthermore, this is the ignorance of the exact loading condition of the air filter. For example, a drenched air filter leads to a considerable increase in the supercharging speed, without this being taken into account using the previously mentioned variables when recourse is made to the compressor map. Even with leakage upstream of the compressor, the supercharger speed increases without this being detected.

Because of the described inaccuracy of the estimated supercharger speed and to avoid exceeding the maximum speed for reasons of strength criticality, in today's applications, a safety margin of about 5% to 10% of

Maximum speed reserved. As a result, the rated power of the engine may already have to be limited at geodetic sea level.

In addition, the maximum engine torque or the required air charge with increasing geodetic height can not be maintained to the same extent as would be possible with a full utilization of the supercharger maximum speed. These effects are becoming more and more relevant with the currently observed increase in superchargers and further reductions in engine displacement and increase in the degree of downsizing. In addition, in the described application approach with safety precaution however, it is not possible to safely avoid supercharger overrun if leakage occurs downstream of the supercharger or if the pressure drop at the air cleaner greatly increases as a result of, for example, complete soaking or even freezing. In order to avoid the described safety distance from the maximum speed and the resulting disadvantages, an accurate measurement of the speed is required. For this purpose, various sensor concepts are known, such as inductive sensors and eddy current sensors, however, because of the resulting additional costs so far no spread in the mass market of the charged

Vehicle engines have found. In contrast, however, are

Vehicle applications are known in which, although no speed sensor, but an additional pressure sensor for measuring the pressure downstream of the air filter is used. Thus, the loading condition of the air filter can be accurately detected and the method described above for determining the speed by recourse to the compressor map is more accurate. The effects of sensor tolerances

Inaccuracies in the compressor map, tolerances of the timing,

Model inaccuracies and the effects of leaks on the supercharger speed remain. As a result, in this approach the

Safety distance to the maximum speed with the negative consequences described limited reduced, but not avoided.

Despite the numerous advantages of the known from the prior art method for determining the speed of a compressor, these therefore still include

Potential for improvement.

Disclosure of the invention

Therefore, a method for determining a rotational speed of a compressor, in particular a turbocharger, an internal combustion engine and an internal combustion engine is proposed, which at least largely avoids the disadvantages of known methods and strategies for determining the rotational speed of a compressor and with which in particular the above-mentioned safety distance to the maximum rotational speed the compressor can be avoided or at least significantly reduced. The aim of the present invention is to determine the speed of the compressor without the use of another sensor. The method for determining a rotational speed of a compressor, in particular a turbocharger, an internal combustion engine, in which a flow signal of the

Internal combustion engine supplied air and a pressure signal is generated, wherein the

Speed of the compressor is determined from a periodic fluctuation of at least a portion of the flow signal and / or pressure signal is characterized in that the flow and / or the pressure upstream of the compressor is detected.

The internal combustion engine may include an air filter, wherein the flow signal and / or the pressure are detected in a region downstream of the air filter. From the pressure signal and a pressure signal of an ambient pressure sensor, a pressure difference or pressure ratio can be determined and from this a functional state of the air filter can be determined. The periodic fluctuations can be caused by a

High pass filtering are separated from the flow signal and / or the pressure signal. A frequency of the periodic fluctuations can be determined by a frequency analysis, in particular a Fourier transformation. The speed of the compressor can be obtained by dividing the frequency by a number of the blades of the compressor. The speed of the compressor can be determined from a periodic fluctuation of at least a portion of the flow signal and the pressure signal. An internal combustion engine according to the invention comprises a compressor, which in a

An air supply passage for supplying air to a combustion chamber of the internal combustion engine is arranged, a pressure sensor for detecting a pressure of the combustion chamber supplied air and for generating an associated pressure signal and / or a flow sensor for detecting a flow of the combustion chamber, the supplied air and for generating an associated flow signal wherein the internal combustion engine further comprises an evaluation circuit for determining the rotational speed of the compressor, wherein the rotational speed of the compressor from a periodic fluctuation of at least a portion of the flow signal and / or pressure signal can be determined, the flow sensor and / or the pressure sensor in the air supply passage in a

Region are arranged upstream of the compressor.

The evaluation circuit for determining the rotational speed of the compressor can be arranged in a control and / or regulating device of the internal combustion engine, a sensor housing for the flow sensor and / or the pressure sensor or in a separate component. The internal combustion engine may include the flow sensor and the Include pressure sensor, wherein the flow sensor and the pressure sensor are integrated in a common sensor housing.

In the context of the present invention, a flow signal is to be understood as a signal that any physically and / or chemically measurable property of a flow indicates an air supplied to a combustion chamber of an internal combustion engine and qualifies or quantifies it. In particular, this may be a flow velocity and / or an air mass flow and / or a

Act air flow. In other words, the flow signal is at least one signal selected from a mass flow signal, volume flow signal and

Flow rate signal. A mass flow is usually given in kg / h and indicates an air mass that flows through a measuring cross-sectional area in a certain time. A volume flow is usually given in m ³ / h. A volume flow indicates an air volume that flows through a measuring cross-sectional area in a certain time. The flow rate is usually expressed in m / s. In particular, the sensed and signal-converted flow characteristics relate to periodically fluctuating flow characteristics.

In the context of the present invention, a periodic fluctuation is to be understood as an alternating component of a signal which is generated by the periodic pressure waves of the compressor. The pressure waves are through the individual

Compressor blades of the compressor caused.

By upstream of the compressor is meant a position in an air supply duct which is earlier than the air flowing in the main flow direction

Reached compressor. The position refers exclusively to one

Air supply duct and not to a position in a supply channel one

Exhaust gas recirculation. Analogously, downstream of the air filter is to be understood a position in an air supply channel which reaches the air flowing in the main flow direction later than the air filter.

In the context of the present invention, the main flow direction is to be understood as meaning the local flow direction of the fluid medium at the location of the sensor, whereby, for example, local irregularities can be disregarded. Especially In the main flow direction, the local average transport direction of the flowing fluid medium can thus be understood.

In the context of the present invention, analog-to-digital conversion means the conversion of analog input signals into digital data or a data stream, which can then be further processed or stored. For this purpose, usually a so-called analog-to-digital converter is used. The analog-to-digital converter quantizes a continuous input signal, such as an electrical voltage, in both time and signal magnitude. Each signal is therefore represented by the conversion in a signal-time diagram in a sequence of points with stepped horizontal and vertical distances. The quantization means that a delimited step-by-step store of values is transferred to a likewise delimited but stepped value store. In quantization, the previously infinitely variable size in a system assumes discrete and therefore isolably separated values.

In the context of the present invention, a high-pass filter is to be understood as a filter which allows signal components with frequencies above its cut-off frequency to pass approximately unattenuated and attenuates components having lower frequencies. The

Cutoff frequency is the value of the frequency above which the signal amplitude or the modulation amplitude at the output of a component drops below a certain value. For example, in a simple RC or RL high pass filter, the

Voltage transfer factor the maximum value 1. At the cutoff frequency, the

i

transmitted amplitude to the v '^ - times value. Analogously, a low-pass filter in the context of the present invention is to be understood as a filter which allows signal components with frequencies below their cut-off frequency to pass approximately unattenuated, but attenuates components with higher frequencies.

Within the scope of the present invention, a Fourier transformation is to be understood as meaning a method of Fourier analysis which makes it possible to decompose continuous signals into a continuous spectrum.

According to the invention, it is proposed that the flow characteristic and / or the pressure upstream of the compressor be detected. In this case, the indication upstream of the compressor refers to a position in a feed channel for feeding of air, in particular ambient air, to a combustion chamber of the internal combustion engine. In this case, the indication upstream is to be seen in time, so that the air first reaches the specified position and then the compressor. A basic idea of the present invention is that the rotating blades of the compressor generate pressure waves which propagate in the compressed air downstream of the compressor and in the ambient air upstream of the compressor. Core of the present

It is therefore invention, this pressure pulsation by a particular thermally suitable positioning of the pressure sensor downstream of an air filter and

Measure upstream of the compressor and determine therefrom the speed of the turbocharger by suitable means of signal processing. The periodic

Fluctuations can be detected by an air mass meter and / or a pressure sensor. Advantageously, the periodic fluctuations of both sensors are then detected. The signal processing in the sensor can be done locally, in the engine control unit or in an additional component. An essential advantage of the invention is therefore that in addition to the determination of the mean pressure downstream of the air filter, the accurate detection of the

Air filter loading state allows, in addition, a speed of the exhaust gas turbocharger can be determined without the need for another sensor. This has in the

Comparison to the speed detection by means of a pressure sensor downstream of the

Compressor has the advantage that only intake air with significantly lower temperatures reaches the pressure sensor and this applied, whereas a pressure sensor downstream of the compressor comparatively high temperatures due to

Air compression is exposed. Brief description of the drawings

Further optional details and features of the invention will become apparent from the following description of preferred embodiments, which are shown schematically in the figures. Show it:

1 is a schematic representation of an internal combustion engine with an exhaust gas turbocharger and a pressure sensor,

2 is a schematic representation of a compressor and its outlet area,

3 is another schematic view of a compressor, 4 shows a flow chart of a method for determining a rotational speed of a compressor,

Fig. 5 is a schematic representation of an internal combustion engine with an exhaust gas turbocharger and a pressure sensor according to a second embodiment of the invention, and

6 shows a further flowchart of a method for determining a rotational speed of a compressor

Embodiments of the invention

Fig. 1 shows an internal combustion engine 10. It is used to drive a motor vehicle, not shown. The internal combustion engine 10 may be formed as a gasoline internal combustion engine with intake manifold injection, diesel internal combustion engine or internal combustion engine with direct fuel injection.

The internal combustion engine 10 comprises a plurality of cylinders 12, which comprise a combustion chamber 14. Combustion air passes into the combustion chamber 14 via a

Air supply passage 16 and by an inlet valve not shown in detail. Of the

Air supply passage 16 may be formed, for example, as an intake passage.

Immediately upstream of the intake valve, fuel is injected through an injector (not shown) connected to a fuel system. Upstream of the injector is located in the air supply passage 16, a throttle valve 18th

An in the combustion chamber 14 befindliches fuel-air mixture is ignited by a spark plug, which is connected to an ignition system. Hot combustion exhaust gases are discharged from the combustion chamber 14 through an exhaust valve and an exhaust pipe. In the exhaust pipe, a turbine is arranged.

In the air supply passage 16, a compressor 20 is further arranged, which is mechanically connected to the turbine. The turbine and compressor 20 together form an exhaust gas turbocharger 22. For compressing the air, the compressor 20 has a plurality of compressor blades 24, as shown for example in FIG. 2 or 3. The heated by the compression intake air is through a charge air cooler 26, which in the Air supply passage 16 is disposed between the compressor 20 and the throttle valve 18, cooled.

The operation of the internal combustion engine 10 is controlled by a control and / or

Control device 28 controlled and / or regulated. In particular, the throttle valve 18, the injector, the ignition system and the like of the control and / or

Control device 28 controlled. For this purpose, the control and / or regulating device 28 receives signals from various sensors. For example, located upstream of an air filter 30, which is disposed upstream of the compressor 20, a

Ambient pressure sensor 32, between the air filter 30 and the compressor

Pressure sensor 34, between the charge air cooler 26 and the throttle valve 18 a

Boost pressure sensor 36 and between the throttle valve 18 and the combustion chamber 14, a further pressure sensor 38 for determining the pressure of the throttled charge air. From a pressure signal of the pressure sensor 34 and a signal of the ambient pressure sensor 32, a pressure difference can be determined and from this a functional state of the air filter 30 can be determined. For example, the pressure sensors 32, 34, 36, 38 may be designed and operate like pressure sensors described in Konrad Reif (ed.): Sensors in the

Motor vehicle, 1st edition 2010, pp 80-82 and 134-136 are described. By the compressor 20, the combustion chamber 14 supplied combustion air is compressed, which allows a higher power of the internal combustion engine 10. The pressure of the compressed air in the cargo space 14, d. H. the boost pressure is provided in a manner to be described in more detail by the pressure sensors 36 and 38 and adjusted in a closed loop by the control and / or regulating device 28.

In order to achieve as fast and precise control of the charge pressure, this is not only on the basis of the provided by the pressure sensors 36, 38

Boost pressure, but also regulated on the basis of the current speed of the compressor 20. The boost pressure p _L and the rotational speed η _Α τι_ be determined based on a provided by the pressure sensor 34 signal U _P using a method which will now be explained in more detail with reference to Figures 2 to 4.

FIG. 2 shows the compressor 20 and, by way of example, a compressor blade 24. Each time, for example, when a compressor blade 24 has passed a certain position in an axial compressor, the speed and therefore also the speed change Pressure of the extracted air. This leads to periodic pressure fluctuations whose periods are related to the speed of the compressor 20. This relationship is exploited according to the invention for obtaining the rotational speed of the compressor 20. In principle, it has been found, for example, by means of a knock sensor that the pressure vibrations propagate as structure-borne noise onto a compressor housing 40. This is illustrated schematically, for example, in FIG. 2 at a compressor tongue 42 which delimits an outlet 44 from the compressor 20. In particular, Fig. 2 shows a static pressure distribution 46 and the propagation of pressure waves 48 to the compressor housing 40. However, it has been found by these measurements that the

Pressure oscillations also spread upstream of the compressor 20. FIG. 3 shows, for example, schematically how an exemplary recorded body sound signal 50 looks over time in the area of the compressor tongue 42.

Now, it is proposed according to the invention to determine a rotational speed η _Α τι_ of the compressor 20 by means of the pressure sensor 34 arranged upstream thereof. More specifically, the rotational speed η _Α τι_ of the compressor 20 is determined by an evaluation circuit not shown in detail. The evaluation circuit may be located in a control and / or regulating device, which has the control and / or regulating device 28. Alternatively, the evaluation circuit can be located in a sensor housing for the pressure sensor 34 or in a separate component. The corresponding method is shown schematically in FIG. 4. First, the pressure signal U _{P of} the pressure sensor 34 is subjected to A D conversion (analog-to-digital conversion) in step 52. By means of a high-pass filter 54, periodic fluctuations U _n , ie alternating components, of the signal U _{P are then} separated. These periodic fluctuations U _n are caused by the pressure waves of the compressor 20, which through the individual compressor blades 24 of the

Compressor 20 caused. In order for these periodic fluctuations U _n to be detected by the pressure sensor 34, it is necessary to arrange them comparatively close to the compressor 20, as shown in FIG. 1. In addition, the pressure sensor 34 must have a corresponding dynamics.

The periodic variations separated by the high-pass filter 54 are now subjected to a Fourier transform at step 56, which determines the frequency F of the periodic variations. This frequency F is the product of the speed η _Α τι_ and the number n _{s of} the compressor blades 24. Therefore, at step 58, the determined frequency F is divided by the number n _{s of} the compressor blades 24, which finally to the speed η _Α τι_ the compressor 20 leads. As already mentioned above, the signal U _{P of} the pressure sensor 34 is also used to determine the charge pressure p _L , which prevails immediately upstream of the intake valve or in the combustion chamber 14 itself. For this purpose, the signal U _{p is} subjected to low-pass filtering in step 60, which results in an average value U _p _ _{m of} the pressure signal U _p . This mean value U _p _ _m corresponds to the pressure between the compressor 20 and the charge air cooler 26. In order to obtain the pressure immediately upstream of the intake valve, the value U _p _ _{m is} subjected to a correction at step 62. For example, the value U _p _ _{m is applied} with a correction factor K multiplicatively or additively. The correction factor K is used during the design of the parameters of the control and / or

Control device 40, for example, on a Motorprüf determined by the pressure before and after the intercooler 26 at different operating conditions of

Internal combustion engine 10 is measured. The correction factor K may in turn depend on operating variables, for example on an air mass flow dm / dt, which is detected by a hot film air mass meter 64. Alternatively, the pressure can also be determined by means of the pressure sensor 38.

Fig. 5 shows another possible embodiment of the present invention.

Hereinafter, only the differences from the internal combustion engine 10 of the first embodiment will be described and the same components are given the same reference numerals.

In the internal combustion engine 10 of the second embodiment is located upstream of the compressor 20, a so-called hot film air mass meter 62, as described for example in Konrad Reif (ed.): Sensors in the motor vehicle, 1. Edition 2010, pp. 156-158. Such Heißfiluuftmassenmesser 62 are usually based on a sensor chip, in particular a silicon sensor chip, with a measuring surface, which is overflowed by the flowing fluid medium. The sensor chip usually comprises at least one heating element and at least two temperature sensors, which are arranged, for example, on the measuring surface of the sensor chip. From one

Asymmetry of the temperature profile detected by the temperature sensors, which is influenced by the flow of the fluid medium, can be concluded that a mass flow and / or volume flow of the fluid medium.

Heißfileinuftmassenmesser are usually designed as plug-in sensor, which is fixed or replaceable in the air supply passage 16 can be introduced. The hot-film air mass meter 62 is configured to detect an air mass flow of intake air flowing through the air supply passage 16 and generate a flow signal indicative of the air mass flow. Again, the generate

Compressor blades 24 a pressure pulse, which upstream in the

Air supply duct 16 can spread to the hot film air mass meter 62. This pressure pulse is periodic and can be determined as a so-called rotary sound frequency. By means of the above-mentioned method, the sought-after useful signal can be separated from interfering signals on the basis of the air mass meter signal, as will be described in more detail below with reference to FIG. 6. More specifically, the speed of the compressor is determined by an evaluation circuit. The evaluation circuit may be located in a control and / or regulating device, which has the control and / or regulating device 28. Alternatively, the evaluation circuit in a sensor housing for the

Hot-film air mass meter 62 or in a separate component. First, the flow signal ULM of the air mass meter 62 is subjected to A / D conversion (analog-to-digital conversion) in step 66. By means of a high-pass filter 68, periodic fluctuations U _N , ie alternating components, of the flow signal ULM are then separated. These periodic fluctuations U _N are caused by the pressure waves of the compressor 20, which are caused by the individual compressor blades 24 of the compressor 20.

The periodic fluctuations separated by the high-pass filter 68 are now subjected to a Fourier transformation at step 70, which determines the frequency F of the periodic fluctuations. This frequency F is the product of the speed n _A TL and the number n _{s of} the compressor blades 24. Therefore, at step 72, the determined frequency F is divided by the number n _{s of} the compressor blades 24, which finally to the speed n _A TL of the compressor 20 leads.

Is a sound propagation upstream of the compressor 20 is not or only insufficiently ensured, for example, because the speed of the compressor 20 is too small or disturbing influences are too large, the speed detection is conventionally made on the basis of the measured average air pressure on the known modulation of the speed of the compressor 20. The tolerance influences of this modulation on the speed are taken into account via corresponding safety distances. The air mass meter 62 can detect, for example, flow signals in the relevant speed or frequency range up to approximately 25 kHz. It is conceivable to combine a rotational speed determination of the compressor 20 by means of the above-described pressure sensor 34 and the air mass meter 62 described, since these increase the signal-to-noise ratio or ensure the uniqueness of a separated signal component. For example, the above pressure sensor 34 may be integrated into the housing of the air mass meter 62. It should be noted that the useful signals are phase-shifted. In particular, the pressure signal is leading with respect to the mass flow signal, which must be taken into account accordingly.

Claims

claims

1 . Method for determining a rotational speed (η _Α τι_) of a compressor (20), in particular of a turbocharger (20), an internal combustion engine (10), in which detects a flow and / or pressure of the internal combustion engine (10) supplied air and an associated Flow signal (ULM) and / or pressure signal (U _P ) is generated, wherein the rotational speed (η _Α τι_) of the compressor (20) from a periodic fluctuation (U _n ) at least a portion of the flow signal (ULM) and / or the pressure signal ( U _P ) is determined

characterized in that

the flow and / or the pressure upstream of the compressor (20) is detected.

2. Method according to the preceding claim, wherein the internal combustion engine (10) comprises an air filter (30), wherein the flow and / or the pressure downstream of the air filter (30) is detected.

3. The method according to the preceding claim, wherein from the pressure signal (U _P ) and a pressure signal of an ambient pressure sensor (32) determines a pressure difference or pressure ratio and from this a functional state of the air filter (30) is determined.

4. The method according to any one of the preceding claims, wherein the periodic

Variations (U _N ) are separated by a high-pass filtering of the flow signal (ULM) and / or the pressure signal (U _P ).

5. The method according to the preceding claim, wherein a frequency (F) of the

periodic fluctuations (U _N ) by a frequency analysis, in particular a Fourier transform, is determined.

6. The method according to one of the two preceding claims, wherein the speed (n _A TL) of the compressor (20) by dividing the frequency (F) by a number of

Blades (n _s ) of the compressor (20) is obtained.

7. The method according to any one of the preceding claims, wherein the rotational speed (η _Α τι_) of the compressor (20) from a periodic fluctuation (U _N ) of at least a portion of the flow signal (ULM) and the pressure signal (U _P ) is determined.

8. internal combustion engine (10) comprising a compressor (20) in a

Air supply passage (16) for supplying air to a combustion chamber (14) of the internal combustion engine (10) is arranged, a pressure sensor (34) for detecting a pressure of the combustion chamber (14) supplied air and for generating an associated pressure signal (U _P ) and or a flow sensor (62) for detecting a flow of the air supplied to the combustion chamber (14) and for generating an associated flow signal (ULM), wherein the internal combustion engine (10) further comprises an evaluation circuit for determining a rotational speed (η _Α τ _ί ) of the compressor (20), wherein the rotational speed (η _Α τ _ί ) of the compressor (20) from a periodic fluctuation (U _N ) of at least a portion of the flow signal (ULM) and / or the pressure signal (U _P ) can be determined, characterized that

the flow sensor (62) and / or the pressure sensor (34) are arranged in the air supply passage (16) upstream of the compressor (20).

9. Internal combustion engine (10) according to the preceding claim, wherein the

Evaluation circuit for determining the rotational speed (η _Α τ _ί ) of the compressor (20) in a control and / or regulating device of the internal combustion engine (10), a sensor housing for the flow sensor (62) and / or the pressure sensor (34) or in one of them is arranged separate component.

10. Internal combustion engine (10) according to one of the two preceding claims,

comprising the flow sensor (62) and the pressure sensor (34), wherein the

Flow sensor (62) and the pressure sensor (34) in a common

Sensor housing are integrated.