WO2008125571A2

WO2008125571A2 - Turbocharger, turbocharged internal combustion engine, method and use

Info

Publication number: WO2008125571A2
Application number: PCT/EP2008/054299
Authority: WO
Inventors: Francis Heyes; Norbert Huber; Achim Koch; Georg Mehne; Gerhard Schopp; Markus Teiner
Original assignee: Napier Turbochargers Limited; Continental Automotive Gmbh
Priority date: 2007-04-16
Filing date: 2008-04-09
Publication date: 2008-10-23
Also published as: WO2008125571A3; DE102007017828A1

Abstract

The invention relates to a turbocharger for a turbochargeable internal combustion engine (30), comprising at least one fresh air intake for taking in fresh air, at least one compressor for compressing the fresh air taken in, the compressor being connected downstream of the fresh air intake in the flow direction of the fresh air, further comprising at least one fresh air outlet, which is connected downstream of the compressor in the flow direction and via which fresh air compressed in the compressor can be supplied to an air intake side of the internal combustion engine (30), and further comprising at least one bypass device for bridging at least one compressor, the bypass device being configured to conduct at least a portion of the fresh air supplied past the compressor during operation. The invention further relates to such an internal combustion engine (30), to a method for operating such a turbocharger, and to a use.

Description

description

Turbocharger, turbocharged internal combustion engine, method and use

The invention relates to a turbocharger for a turbochargeable internal combustion engine and such an internal combustion engine. The invention further relates to a method for operating such a turbocharger and a use.

In conventional, non-supercharged internal combustion engines (gasoline or diesel engine), a negative pressure in the intake tract is generated during intake of air, which increases with increasing speed and limits the theoretically achievable performance of the engine. One way to counteract this and thus achieve an increase in performance is the use of an exhaust gas turbocharger. An exhaust gas turbocharger (ATL) or turbocharger for short is a charging system for an internal combustion engine, by means of which the cylinders of the internal combustion engine are subjected to an increased charge air pressure.

The detailed structure and operation of such a turbocharger is widely known and will therefore be explained only briefly. A turbocharger consists of a (exhaust gas) turbine in the exhaust gas flow (outflow path), which is connected via a common shaft to a compressor in the intake tract (inflow path). The turbine is set in rotation by the exhaust gas flow of the engine and thus drives the compressor. The compressor increases the pressure in the intake tract of the engine, so that through this compression during the intake stroke, a larger amount of air enters the cylinders of the internal combustion engine than in a conventional naturally aspirated engine. This provides more oxygen for combustion. This increases the mean pressure of the engine and its torque, which significantly increases the output. The feeding of a larger amount of fresh air associated with the compression process is called charging. The energy for the charge is taken from the turbine through the fast-flowing, hot exhaust gases. This energy, which would otherwise be lost through the exhaust system, is used to reduce intake losses. This type of charging increases the overall efficiency of a turbocharged internal combustion engine.

Although many turbochargers have already solved many problems and difficulties, there are still some unresolved problems. The same high demands are placed on the mode of operation of drive units equipped with exhaust-gas turbochargers as on equivalent-performance conventional internal combustion engines. This leads to the fact that the full charge air pressure of the exhaust gas turbocharger even at very low engine speeds must be available to achieve a required engine performance. This leads to the following problem:

When accelerating from low speeds, the correct amount of exhaust gas is missing in the discharge path in order to generate the boost pressure in the intake path for the intake fresh air. Only when, for example, with increasing speed, a sufficiently strong exhaust gas flow is available, set the desired compression of the intake fresh air and thus the desired charge. This lack of power at low speeds is generally referred to as turbo lag. Also, generally, this charge is only delayed when suddenly accelerating, since the internal combustion engine consumes the fresh air much faster than compressed air can be provided by the compressor. That is, the pressure PE applied to the compressor on the input side is higher than the pressure PA of the fresh air provided by the compressor on the output side. Only after a sufficiently high exhaust gas flow has settled on the downstream side of the turbine does a sufficient pressure PA ≥ PE also appear on the upstream side of the compressor.

Characterized in that at low speeds, the pressure PA is lower than the pressure PE, the compressor throttles the internal combustion engine, instead of this compressed air supply and thus to contribute to a performance increase. Due to the fact that the internal combustion engine is throttled, it can also provide less exhaust gas on the exhaust gas side, which in turn leads to a lower rotational speed of the turbine. This, in turn, has a negative effect on the rotational speed of the compressor and thus on the compressed air.

This peculiarity of a turbocharger can for example be compensated to a large extent by specially provided control systems, such as a variable turbine geometry (VTG), through the use of very small turbochargers and / or specially shaped channels in the cylinder head.

Against this background, it is an object of the present invention, as far as possible to reduce the undesirable effect of the turbo lag in turbochargers, in particular in other ways.

According to the invention, this object is achieved by a turbocharger having the features of patent claim 1, by a turbo-charged internal combustion engine having the features of patent claim 15 and / or by a method having the features of patent claim 20 and / or by a use having the features of patent claim 28.

Accordingly, it is provided:

- A turbocharger for a turbo-superchargeable internal combustion engine, having at least one fresh air inlet for sucking fresh air, with at least one compressor for compressing the intake fresh air, which is arranged in the flow direction of the fresh air behind the fresh air inlet, with at least one fresh air outlet, which is arranged in the flow direction behind the compressor is and can be supplied via the fresh air compressed in the compressor to an air inlet side of the internal combustion engine, with at least one bypass device for bridging at least one compressor, which is designed to be in Operation to pass at least a portion of the supplied fresh air to the compressor.

- A turbo-charged internal combustion engine, with at least one turbocharger according to the invention whose compressor is on the other side connected to an air inlet side of the internal combustion engine and the turbine is connected downstream with an exhaust gas outlet side of the internal combustion engine.

A method for operating a turbocharger, which has a bypass device for bridging a compressor on a fresh air side of the turbocharger, with a first operating mode in which the bypass device is closed and the intake fresh air via that through the

Bypasseinrichtung bridged compressor is passed, with a second operating mode in which the bypass device is opened and the fresh air sucked in, at least partially passed through the bypass device.

- A use of a bypass device, in particular a bypass valve and / or a Bypassrohrschalters and / or a bypass damper, for bridging a compressor, in particular the high-pressure compressor, a turbocharger.

The idea on which the present invention is based is to provide at least one bypass device on the compressor side, that is to say in the inflow path of a turbocharger. This bypass device is designed to bridge the compressor when required, that is, in this case, the sucked or already pre-compressed fresh air is at least partially bypassed the compressor in the flow path and fed, for example, directly to the engine in unenriched form. This way can be too big

Pressure difference between the inlet side of the compressor and the outlet side is prevented or at least reduced. In this way, on the outlet side of the dichters against the inlet side not too much negative pressure, whereby the engine is not throttled thereby. The particular advantage is therefore that the bypass device according to the invention avoids a turbo lag, which typically exists at low rotational speeds of the turbocharger, as far as possible or at least significantly reduces it. This operation of the turbocharger is particularly relevant at low speeds of the turbocharger and thus when accelerating from low speeds.

Due to the reduced negative pressure between the compressor outlet and the engine intake, less oil is sucked out of the bearings of the turbocharger. Otherwise, this oil would undesirably pass into the combustion chamber of the engine via the fresh air compressed by the compressor. This improves the overall combustion process in the engine as a whole.

Another advantage is that the bypass device according to the invention significantly reduces in a turbocharger caused by the turbocharger noise production.

Advantageous embodiments and modifications of the invention will become apparent from the other dependent claims and from the description in conjunction with the drawings.

In a typical embodiment of the turbocharger and the internal combustion engine, a control device is provided which controls the function of the bypass device. This control device may for example be part of the turbocharger or the internal combustion engine. Typically, however, the control device is designed as part of the engine control system for controlling both the internal combustion engine and the turbocharger. Such a control device, which controls, for example, the opening and closing of the bypass device, can be designed mechanically or also electrically. In the case of an electrically formed control device, the bypass device contains, for example, an electric by the control device controllable actuator. In this case, this control device can be a program-controlled unit, for example a microcontroller or microprocessor.

For example, in a typical embodiment, the bypass device may include a bypass valve, a bypass tube switch, a bypass door, or the like. It would also be conceivable to combine these elements. These ele- ments are preferably designed to be controllable via the control device.

In a particularly preferred embodiment, the turbocharger has at least two turbocharger stages. Each of these (successively arranged) turbocharger stages includes a compressor and a turbine, each coupled to each other via a common shaft (e.g., mechanical). In two-stage turbochargers, the two turbocharger stages can be operated simultaneously or only one of the turbocharger stages can be active at a time. Two-stage turbochargers have over single-stage turbochargers on the advantage that thereby a better and more effective control of the charge can be realized, whereby the turbo lag can be further reduced overall.

In a typical embodiment, one of the turbocharger stages is designed as a high-pressure stage with a high-pressure turbine and a high-pressure compressor. Another stage is formed as a low pressure stage with a low pressure turbine and a low pressure compressor. High-pressure turbine and high-pressure compressor on the one hand and low-pressure turbine and low-pressure compressor on the other hand are each coupled to one another via a common shaft.

In a typical embodiment of the at least two-stage turbocharger, the bypass device bridges at least the compressor of the high-pressure stage. In an alternative embodiment, in the case of at least two-stage turbocharging, a single bypass device is provided which bridges both the low-pressure compressor and the high-pressure compressor.

A further, likewise alternative embodiment provides at least two bypass devices in the case of the at least two-stage turbocharger. In this case, a first bypass device is designed to bridge the low-pressure compressor and a second bypass device is designed to bridge the high-pressure compressor.

In a preferred embodiment, at least one of the bypass devices is designed to block in reverse relative to the flow direction of the fresh air. In the case of a closed bypass device, compressed fresh air, which is provided on the outlet side by the compressor bridged via the bypass device, can not pass again via this bypass device to the respective inlet side of the compressor.

In a further, likewise preferred embodiment, the bypass device can be operated as throttle device for the internal combustion engine. For example, the turbocharger can be controlled via the control device so that the

Turbocharger acts as an engine brake by in the event that a braking operation is indicated by closing the bypass device artificially creates a negative pressure between the respective compressor and the internal combustion engine, which would lead to a total throttling of the internal combustion engine.

In a typical embodiment, a first pipe for connecting the fresh air inlet to the inlet side of the compressor and a second pipe for connecting the outlet side of the compressor with the fresh air outlet or with another compressor are provided. Further, at least one bypass pipe is provided as part of the bypass device, which via a first branch pipe branches off from the first pipe and which opens via a second branch pipe in the second pipe.

In a typical embodiment, the turbocharger has an air filter. This air filter is arranged in the Anströmpfad between the fresh air inlet and the compressor. The bypass pipe branches off in the flow direction of the fresh air to the air filter. This air filter is used to clean the intake air so as to prevent the smallest dust particles and particles from getting into the compressor wheel operated at very high speeds, which can lead to damage or even destruction of the compressor wheel.

In a likewise preferred embodiment, a charge air cooler is arranged in the inflow path between the compressor, in particular the high-pressure compressor, and the fresh air outlet. The charge air cooler typically opens immediately before the inlet of the internal combustion engine and serves the purpose of cooling the compressed air supplied to the internal combustion engine, which becomes very hot at very high rotational speeds of the turbocharger and thus may under certain circumstances reduce the power of the internal combustion engine. The bypass pipe is arranged here in the flow direction of the fresh air in front of the intercooler.

In a likewise typical embodiment, the turbocharger according to the invention has a further bypass device, which is arranged in the outflow path of the turbocharger and which is designed to bridge a turbine of the turbocharger. This further bypass device is often referred to as wastegate and serves the boost pressure control. The wastegate may have, for example, a bypass valve, a flap or a bypass tube switch. This bypass valve usually bridges the exhaust gas turbine by means of a dedicated pipe. At a set boost pressure, this bypass valve is opened by a sender on the compressor side and then passes the exhaust gas over the By- pass pipe and the bypass valve past the turbine directly into the exhaust, which prevents a further increase in turbine speed. This prevents the turbocharger and thus the turbocharger compressor from turning higher and higher and, due to the positive feedback between turbine revolution speed and compressor revolution speed, the compressor reaches its delivery limit and exceeds the engine's mechanical and thermal limits which may result in destroying the turbocharger and the engine.

In a particularly preferred embodiment, a first measuring device is provided. This first measuring device is designed to measure a speed of a turbine wheel of the turbocharger, for example the speed of the turbine wheel of the high-pressure turbine. The controller controls the bypass device depending on the measured turbine wheel speed. In this way, depending on the speed control of the bypass device, whether it is closed, opened or partially open, be made specifically in accordance with the turbine wheel speed.

In a further, likewise advantageous embodiment, a second measuring device is provided, which measures the air mass flow conducted through the bypass device and / or through the compressor. This measured air mass flow, which is also referred to in the English literature as Air Mass Flow (AMF), refers to the air flow rate of the compressor or the bypass device. Depending on the air mass flow determined in this way, the function of the bypass device can thus also be specifically tuned to it. Preferably, the bypass device is controlled both in accordance with the determined air mass flow and thus the air flow rate and the speed of the turbine wheel.

In the method according to the invention for operating a turbocharger, a first operating mode and a second operating mode are provided. provided in the first operating mode, the bypass device is closed and the intake fresh air is passed completely over the bridgeable by the bypass compressor and in the second operating mode, the bypass device is opened and the intake fresh air is at least partially passed through the bypass device. According to the invention, a third operating mode is now also provided-as a special case of the second operating mode-in which the fresh air sucked in is conducted past the compressor exclusively via the bypass device. In the third operating mode, therefore, no fresh air passes through the compressor. This can be realized, for example, by a controllable flap mounted on the inlet of the compressor (switch, valve or the like).

In a particularly preferred embodiment, a first threshold of an air flow in the Anströmpfad is specified. The turbocharger is operated here in the third operating mode, provided that the measured, that is current air flow rate of the fresh air in the Anströmpfad is below the first threshold.

Additionally or alternatively, a second threshold of the air flow in the Anströmpfad is given, which is greater than the first threshold. The turbocharger is operated in the first operating mode as long as the current air flow in the inflow path is greater than the second threshold.

If the current air flow rate of the fresh air in the inflow path is in the range between the first and second threshold, then the turbocharger is operated in the second operating mode.

Instead of using the two thresholds, only one threshold would be conceivable above which the turbocharger is operated eg in the first operating mode and below which the turbocharger is operated, for example, in the second or in the third operating mode. Variations on this would of course also be conceivable, for example the use of more than two thresholds or the introduction of a switching hysteresis for the Switching between the different operating modes when exceeding or falling below one of the thresholds.

In an additional, alternative embodiment of the method according to the invention, the turbocharger is operated in the second operating mode as long as the measured, current air flow through the compressor is less than the air flow through the bypass device in the Anströmpfad.

In a further advantageous refinement, the current air flow rate passed through the bypass device and / or through the compressor is measured and evaluated, for example, with regard to the correspondingly predetermined thresholds. This typically takes place in specially designed measuring devices and in a corresponding evaluation device.

The invention will be explained in more detail with reference to the embodiments indicated in the figures of the drawings. It shows:

Fig. 1 is a schematic representation of a general first embodiment of a turbocharger according to the invention;

FIG. 2 shows a schematic illustration of a second exemplary embodiment of a turbocharger according to the invention; FIG.

3 is a schematic representation of a third embodiment of a turbocharger according to the invention;

4 shows a schematic representation of a fourth exemplary embodiment of a turbocharger according to the invention;

5 is a schematic representation of a fifth embodiment of a turbocharger according to the invention; Fig. 6 is a schematic representation of a sixth embodiment of a turbocharger according to the invention;

7A is a schematic representation of a first operating mode of a turbocharger according to the invention;

7B is a schematic representation of a second operating mode of a turbocharger according to the invention.

In the figures of the drawings, identical and functionally identical elements, features and sizes - unless otherwise indicated - have been given the same reference numerals.

Fig. 1 shows a schematic representation of a first general embodiment of a highly simplified turbocharger according to the invention, which has only the essential components of a turbocharger.

In Fig. 1, the turbocharger is designated by reference numeral 10. The turbocharger 10 has, in a known manner, a compressor 11 and a turbine 12, which are mechanically coupled to one another via a common shaft 13. The compressor 11 is arranged in an inflow path 14 and the turbine 12 in a discharge path 15. The turbocharger 10 in Fig. 1 is formed in one stage, that is, it has only a compressor 11 and a turbine 12.

The inflow path 14 of the turbocharger 10 is defined between a fresh air inlet 16, via which fresh air is drawn in, and a fresh air outlet 17, via which fresh air compressed by the compressor 11 is provided by the turbocharger 10. This discharged, compressed fresh air is fed to a fresh air inlet side of an internal combustion engine (not shown in FIG. 1). The discharge path 15 of the turbocharger 10 is defined between an exhaust gas inlet 18, via which exhaust gas generated by the internal combustion engine (not shown in FIG. 1) is introduced into the turbocharger is, and an exhaust outlet 19, through which the exhaust gas can flow. The Anströmpfad is often referred to as intake, fresh air side or charge air side. The outflow path is often referred to as exhaust path or exhaust side.

With regard to the terminology chosen in the present patent application, a respective compressor has an inlet on the inlet side and an outlet on the outlet side. The flow direction is determined on the compressor side in each case by the flow air of the fresh air, that is towards the internal combustion engine. In all figures of the drawing, the flow direction of the fresh air and the exhaust gas is represented by corresponding arrows in the pipes. The respective fresh air is designated by reference numeral 20 and the respective exhaust air with reference numeral 21.

Between the fresh air inlet 16 and the inlet of the compressor 11, a first pipe 20 a is provided, within which the fresh air supplied to the compressor 11 has a pressure P 1 and a temperature T 1. Further, another pipe 20 b is provided between the outlet of the compressor 11 and the fresh air outlet 17. The compressor 11 is designed to compress the fresh air 20 supplied to it via the pipeline 20a and to provide it in compacted form via the pipeline 20b on the outlet side.

In the same way, a pipeline 21b is provided between the exhaust gas inlet 18 and the turbine 12, and a second pipeline 20a is provided between the turbine 12 and the exhaust gas outlet 19.

According to the invention, the turbocharger 10 has a bypass device 22. The bypass device 22 includes a bypass switch 23, which may be formed, for example, as a bypass valve, bypass valve, bypass tube switch 23 or the like. The bypass device 22 is adapted to the fresh air flow 20 depending on the mode of operation at least partially pass via corresponding pipes 24a, 24b and the bypass switch 23. For this purpose, a bypass pipe 24 a branches off from the first pipe 20 a via a pipe branch, which opens into the pipe switch 23. From there, a second bypass pipe 24b leads via a second pipe branch 25b back into the second pipe 20b.

The bypass device 22 can, as will be described in detail below, be operated in different operating modes. For example, the bypass device 22 may be fully open, fully closed, or partially open and closed. Depending on the operating mode, the fresh air 20 supplied via the fresh air inlet 16 thus flows completely through the compressor 11, completely through the bypass device 22 or both via the compressor 11 and via the bypass device 22.

2 shows a schematic illustration with a second exemplary embodiment of a single-stage turbocharger according to the invention. In contrast to FIG. 1, the internal combustion engine 30 is additionally shown in the exemplary embodiment in FIG. 2. The engine block of the internal combustion engine 30 has in the present embodiment, four cylinders, which is to be understood only by way of example. Also, the internal combustion engine 30 and the coupling to the turbocharger 10 via the intake manifold and the exhaust manifold is shown only schematically and greatly simplified.

The engine block 31 of the engine 30 has an air inlet side 32 and an exhaust gas outlet side 33. The air inlet side 32 is here connected to the fresh air outlet 17 of the turbocharger 10 so that the fresh air 20 compressed by the turbocharger 10 can be supplied to the engine block 31 via corresponding fresh air manifolds (shown only schematically). The exhaust gas outlet side 33 is connected to the exhaust gas inlet 18 of the turbocharger 10. In the exemplary embodiment in FIG. 2, an air filter 34 is furthermore provided in the first pipeline 20a, that is to say between the fresh air inlet 16 and the compressor 11, which is designed to filter the intake air and thus to clean it.

Further, in the pipeline 20 b, that is, between the compressor 11 and the fresh air outlet 17 and thus immediately before the internal combustion engine 30, a charge air cooler 35 is provided. This intercooler 35 cools the air which is typically highly heated at very high rotational speeds by the compressor 11, so that optimum combustion can take place in the engine block 31.

In the discharge path 15, a further bypass device 36 is further provided, which has a so-called wastegate valve 37 between the two bypass pipes 37a, 37b. Exhaust gas can bypass the turbine 12 via this additional bypass device 36 and thus prevent the turbine 12 from reaching excessive rotational speeds and thus bringing the engine beyond its power limit.

Further, in the pipeline 21a on the downstream side, an exhaust system 38, such as a catalyst, Abgasfilter- ter, exhaust and the like, is provided.

In contrast to FIGS. 1 and 2, in the third exemplary embodiment in FIG. 3 the turbocharger 10 has a two-stage design, that is to say it has two turbocharger stages 40, 41. Each turbocharger stage 40, 41 has its own compressor IIa, IIb and its own turbine 12a, 12b, which are coupled to each other within the respective stage 40, 41 via a common shaft 13a, 13b. In this case, the first turbocharger stage 40 is designed as a low-pressure stage 40 and comprises a low-pressure compressor IIa and a low-pressure turbine 12a. The second turbocharger stage 41, which is connected directly to the air inlet side 32 and the exhaust gas outlet side 33 of the internal combustion engine 30, is designed as a high-pressure stage 40b formed and includes a high pressure compressor IIb and a high pressure turbine 12b.

According to the invention, only the high-pressure stage 40b has a bypass device 22 in FIG. Thus, the sucked fresh air in the low pressure stage 40a is always passed through the low pressure compressor IIa. Depending on the operation of the bypass device 22, the air compressed in the low-pressure compressor IIa is conducted either exclusively via the bypass device 22, exclusively via the high-pressure compressor IIb or through both the high-pressure compressor IIb and the bypass device 22.

In FIG. 3, both the high-pressure stage 40b and the low-pressure stage 40a each have their own wastegate bypass means 36a, 36b.

In the fourth exemplary embodiment in FIG. 4, the turbocharger 10 has a single bypass device 22, in which case the bypass device 22 equally bridges both the low-pressure compressor IIa and the high-pressure compressor IIb. The sucked air can thus be passed either via the two compressors IIa, IIb or uncompressed via the bypass device 22.

In contrast to FIGS. 3 and 4, in the fifth exemplary embodiment in FIG. 5 the turbocharger has two bypass devices 22a, 22b. Each of these bypass devices 22a, 22b is in each case assigned to a single compressor IIa, IIb and designed to just bridge its associated compressor IIa, IIb. These two bypass devices 22a, 22b can preferably be operated separately from one another. In this way, a stepped connection of the respective compressor IIa, IIb is possible. For example, it would be conceivable that at very low rotational speeds of the turbocharger 10, the air is supplied via both bypass devices 22a, 22b directly to the internal combustion engine 30. With increasing speeds, first the bypass device 22a for the low-pressure Closer closed, so that the fresh air sucked 20 is first passed through the low pressure compressor IIa. Subsequently, this air compressed in the low-pressure compressor IIa is guided past the high-pressure compressor IIb via the second bypass device 22b. With further increasing speeds then the second bypass device 22b can be closed, so that the fresh air is completely supplied via both compressors IIa, IIb of the internal combustion engine. At high speeds, a very high compression of the intake fresh air 20 is possible.

6 shows a greatly simplified sixth exemplary embodiment of an arrangement with a turbocharger according to the invention. This arrangement comprises three measuring devices 50, 51, 52.

The first measuring device 50 is designed to determine the air flow rate on the inflow side 14. For this purpose, the first measuring device 50 is connected on the input side to the pipeline 20a in order to measure the air mass flow in this pipeline 20a. Depending on the determined air mass flow, the first measuring device 50 generates a measuring signal Ml.

The second measuring device 51 is designed to determine the rotational speed of the turbine 12 and thus also of the compressor 11. For this purpose, the second is

Measuring device 51 on the input side connected to the common shaft 13 to receive their angular velocity. Depending on the recorded angular velocity, the second measuring device 51 generates a second measuring signal M2.

The third measuring device 52 is designed to determine the air pressure at the fresh air outlet side 17 of the turbocharger 10. For this purpose, the third measuring device 52 is connected to the pipeline 20b, there to determine the pressure P2. Depending on the determined pressure P2, the third measuring device 52 generates a third measuring signal M3. The arrangement in FIG. 6 furthermore has a control device 53. The control device 53 may be part of the turbocharger 10 or the internal combustion engine 30 or may be designed as a separate control device, for example as part of the engine control. The control device 53 is designed to control the bypass device 22 in accordance with a control signal S1. This control signal Sl is generated in accordance with at least one of the measurement signals Ml - M3. Depending on these measurement signals M1-M3, the control signal S1 controls the bypass device 22 into an open, partially closed or completely closed state and thus regulates the flow of fresh air on the inflow side 14 such that fresh air intake is either only via the compressor 11 , only via the bypass device 22 or through both the compressor 11 and the bypass device 22 flows.

With reference to FIGS. 7A and 7B, two schematic representations for the operation of a bypass device according to the invention 22 equipped, for example, one-stage trained

Turbocharger 10 shown, which is assumed here by a single-stage turbocharger 10 as shown in FIG. Furthermore, these modes of operation assume that to control the

Bypasseinrichtung 22 only the air flow in Anströmpfad 14 is used. Additionally or alternatively, of course, the pressure P2 and / or the rotational speed can be used here.

First operating mode:

The bypass device 22 is closed, so that the sucked fresh air flows exclusively through the compressor 11.

Second operating mode: The bypass device 22 is open, so that the fresh air can flow both via the bypass device 22 and the compressor 11.

Third operating mode:

The bypass device 22 is closed and the inlet side of the compressor 11 is closed via a flap (not shown in FIG. 1). In this case, the sucked fresh air flows exclusively through the bypass device 22.

In FIG. 7A, a threshold SW for the air flow AMF is specified. If the fresh air flow flowing through the pipeline 20a and thus the air flow AMF are above this threshold SW, then the turbocharger is operated in the first operating mode; if it is below it, it is operated in the second operating mode.

In contrast to this, in the exemplary embodiment in FIG. 7B, two thresholds SW1, SW2 are specified, wherein the first threshold SW1 defines a larger air flow rate than the second threshold SW2, ie. SW1> SW2. If the measured, that is, the current air flow rate AMF through the pipeline 20a is greater than the threshold SW1, then the turbocharger 10 is operated in the first operating mode. If the measured air flow rate AMF is less than the second threshold SW2, then the turbocharger 10 is operated in the third operating mode. If the measured air flow rate AMF is in the range between the first threshold SW1 and the second threshold SW2, then the turbocharger 10 is operated in the second operating mode.

The present invention should not be limited to the above embodiments, but may of course be modified in many ways.

Claims

claims

1. turbocharger (10) for a turbo-superchargeable internal combustion engine (30),

with at least one fresh air inlet (16) for drawing in fresh air (20),

with at least one compressor (11) for compressing the sucked-in fresh air (20) which is arranged in the flow direction of the fresh air (20) behind the fresh air inlet (16),

with at least one fresh air outlet (17) which is arranged behind the compressor (11) in the flow direction and via which fresh air (20) compressed in the compressor (11) can be fed to an air inlet side (32) of the internal combustion engine (30),

with at least one bypass device (22) for bridging at least one compressor (11), which is designed to pass at least part of the supplied fresh air (20) past the compressor (11) during operation.

2. Turbocharger according to claim 1, characterized in that a control device (53) is provided, which controls the function of the bypass device (22).

3. A turbocharger according to one of the preceding claims, since the brake means is that the bypass device (22) has a bypass valve (23) and / or a bypass tube switch (23) and / or a bypass flap (23).

4. The turbocharger according to claim 1, characterized in that the turbocharger (10) has at least two turbocharger stages (40, 41), each turbocharger stage (40, 41) having a turbocharger stage (40, 41). denser (IIa, IIb) and a turbine (12a, 12b) which are coupled to each other via a common shaft (13a, 13b).

5. A turbocharger according to claim 4, characterized in that one of the turbocharger stages (40, 41) as a high pressure stage (41) with a high pressure turbine (12b) and a high pressure compressor (IIb) and another of the turbocharger stages (40, 41) as a low pressure stage (40 ) is formed with a low pressure turbine (12a) and a low pressure compressor (IIa).

6. The turbocharger according to claim 5, characterized in that it can be controlled that the bypass device (22) bridges the high-pressure compressor (IIb).

7. turbocharger according to one of claims 5 or 6, characterized in that a single bypass device (22) is provided and the only bypass device (22) bridges both the low-pressure compressor (IIa) and the high-pressure compressor (IIb).

8. Turbocharger according to one of claims 5 or 6, since you ge chnetz ch net, that at least two bypass devices (22a, 22b) are provided, of which a first bypass device (22a) the low-pressure compressor (IIa) and a second bypass device ( 22b) bridges the high-pressure compressor (IIb).

9. Turbocharger according to one of the preceding claims, characterized in that the bypass device (22) with respect to the flow direction of the fresh air (20) is formed locking backward.

10. Turbocharger according to one of the preceding claims, since you ch rete ge cht that the bypass device (22) as a throttle device for the internal combustion engine (30) is operable.

11. A turbocharger according to one of the preceding claims, characterized in that a first pipe (20a) for connecting the fresh air inlet (16) to the inlet side of the compressor (11, IIa) and a second pipe (20b ) are provided for connecting the outlet side of the compressor (11, IIa) with the fresh air outlet (18) or with a further compressor (IIb) and that at least one bypass pipe (24a, 24b) is provided as part of the bypass device (22) which branches off via a first branch pipe (25a) from the first pipe (20a) and which opens into the second pipe (20b) via a second pipe branch (25b).

12. A turbocharger according to claim 11, characterized in that there is an additional air filter (34) between the fresh air inlet (16) and the compressor (11) and the bypass pipe (24a, 24b) in the flow direction of the fresh air (20 ) branches off after the air filter (34).

13. Turbocharger according to one of claims 11 or 12, characterized in that between the compressor (11), in particular the high-pressure compressor (IIb), and the fresh air outlet (17) a charge air cooler (35) is arranged and the bypass pipe (24a, 24b) in the flow direction of the fresh air (20) before the intercooler (35) opens.

14. Turbocharger according to one of the preceding claims, characterized in that at least one further bypass device (36) is provided, which bridges a turbine (12) of the turbocharger (10).

15. Turbocharged internal combustion engine (30), with at least one turbocharger (10) according to one of the preceding claims, the compressor (11) is connected upstream with an air inlet side (32) of the internal combustion engine and the turbine (12) downstream with an exhaust gas outlet side of the internal combustion engine ( 30) is connected.

16. Internal combustion engine according to claim 15, characterized in that a control device (53) is provided, which controls the function of the bypass device (22).

17. Internal combustion engine according to one of claims 15 or 16, characterized in that a first measuring device (51) is provided, which measures the speed of a turbine wheel of the turbine (12), wherein the control device (53), the bypass device (22) depending on the controlled by the first measuring device (51) measured speed.

18. Internal combustion engine according to any one of claims 15-17, characterized in that a second measuring device (50) is provided, which determines the by the bypass device (22) and / or through the compressor (11) directed air flow.

19. Internal combustion engine according to any one of claims 15 - 18, characterized in that a third measuring device (52) is provided which measures the charge air pressure of the fresh air (20) in the region of the fresh air outlet (17).

20. A method for operating a turbocharger (10), in particular a turbocharger (10) according to one of claims 1 to 14, on a fresh air side (14) of the turbocharger (10) a bypass device (22) for bridging a compressor (11) of the Turbocharger (10), with a first operating mode, in which the bypass device (22) is closed and the fresh air (20) sucked in is passed through the compressor (11) which can be bridged by the bypass device (22), with a second operating mode, in which the bypass device (22) is open and the sucked fresh air (20) is at least partially passed through the bypass device (22).

21. The method according to claim 20, characterized in that a third operating mode is provided, in which the sucked fresh air (20) exclusively via the bypass device (22) to the compressor (11) is passed over.

22. The method according to any one of claims 20 or 21, characterized in that a first threshold (SWL) of an air flow in the Anströmpfad (14) is specified and that the turbocharger (10) is operated in the third operating mode, provided that the air flow rate of the fresh air (20 ) is in the Anströmpfad (14) below the first threshold (SWl).

23. The method according to any one of claims 20 - 22, characterized in that a second threshold (SW2) of an air flow in the Anströmpfad (14) is predetermined, wherein the second threshold (SW2) is greater than the first threshold (SWl), and that the turbocharger (10) is operated in the first operating mode, as far as the air flow rate of the fresh air (20) in the inflow path (14) is above the second threshold (SW2).

24. The method according to any one of claims 20 - 23, characterized in that the turbocharger (10) is operated in the second operating mode, provided that the air flow rate of the fresh air (20) in the Anströmpfad (14) in the region between the first and the second threshold (SWL , SW2) is.

25. The method according to any one of claims 20 - 24, characterized in that the turbocharger (10) is operated in the second operating mode as long as in the Anströmpfad (14), the air flow through the compressor (11) is less than the air flow through the bypass device (22 ).

26. The method according to any one of claims 20-25, characterized in that by the bypass device (22) and / or by the compressor (11) conducted current air flow rate is measured and evaluated.

27. The method according to any one of claims 20 - 26, characterized in that the bypass device (22) is operated as a throttle.

28. Use of a bypass device (22), in particular of a by-pass valve (23) and / or a bypass tube switch

(23) and / or a bypass flap (23), for bridging a compressor (11), in particular the high-pressure compressor (IIb), a turbocharger (10).