WO2003044348A1

WO2003044348A1 - Method for charge exchange in a piston-type internal combustion engine and charge exchange system suitable for carrying out said method

Info

Publication number: WO2003044348A1
Application number: PCT/EP2002/013028
Authority: WO
Inventors: Oskar Schatz
Original assignee: Schatz Thermo Engineering
Priority date: 2001-11-20
Filing date: 2002-11-20
Publication date: 2003-05-30
Also published as: DE10156839A1

Abstract

The invention relates to a method for charge exchange in a piston-type internal combustion engine, whereby charge air is supplied to a combustion chamber (10), comprising at least one inlet valve (14) and one exhaust valve (16),through an air filter (12). The charge air is supplied selectively, either through a compressor branch (28a) of a charging system, comprising a compressor (22) for the charge air and a drive unit (20) for the compressor, or through a naturally-aspirated branch (28b), which circumvents the compressor (22) as a bypass. Closing bodies (32, 30) are provided in both the compressor branch (28b) and the naturally-aspirated branch (28a). The speed of the charging system is dependent on the compressor load and the closing bodies (32, 30) are alternately opened in a controlled manner by means of a controller (34).

Description

DESCRIPTION

Process for changing the charge in an internal combustion engine of the piston type and suitable charge change system for carrying out the process.

According to the preamble of claim 1, the invention relates to a method for changing the charge in an internal combustion engine of the piston type in which charge air is supplied to a combustion chamber having at least one intake valve and one exhaust valve via an air filter, and the charge air is optionally guided either via a compressor branch of a supercharger system which contains a compressor for the charge air and a drive unit assigned to the compressor, or via a suction air branch which bypasses the compressor, and with blocking elements in the compressor branch and in the suction air branch, and a charge exchange system suitable for carrying out the method.

Such a method has previously been used in particular in large diesel engines in connection with mechanical compressors for the purpose of recharging, i.e. In each cycle, the cylinder was first filled with suction air, then the suction air branch was closed and, after the suction air, compressed air from the compressor branch was introduced into the combustion chamber to increase the pressure. The locking devices are therefore opened and closed in each cycle depending on the crank angle. The purpose of this approach was to reduce consumption compared to a conventionally charged engine. Recently, the reloading has come into discussion again, in particular for motor vehicle engines, with it being proposed in connection with the exhaust gas turbochargers customary today.

The use of the exhaust gas turbocharger suffers from a problem inherent in these superchargers, namely that it runs at a relatively low speed at low engine load and in particular at low engine speeds and is then virtually ineffective. With these superchargers, a certain speed is set for a given drive power and a given load torque of the compressor. If the delivery capacity of the compressor is to be increased, the speed of the charger and the drive power must be increased accordingly. It would then require a lot of energy to respond quickly enough to a higher load requirement, that is, the required one Minimum speed to be accelerated at which the compressor has the desired effect. If - what happens relatively often in motor vehicle engines - the engine is suddenly loaded and possibly also accelerated, it takes a very long time for the exhaust gas turbocharger to ramp up to the required power, ie to supply a sufficient amount of air with sufficient pressure. This is the cause of the notorious weak start of engines equipped with turbochargers, which shows up when the vehicle is to be accelerated from a standing start. It is also noticeable when there is a sudden need for power while driving, especially when the engine is running at low speed and low load.

Because of the weak starting, it has already been proposed to temporarily support the drive of the compressor by means of an electric auxiliary motor, a so-called e-booster. This is associated with corresponding additional costs, takes up valuable space, increases the weight of the vehicle and extracts electrical energy from the electrical on-board system, which is undesirable particularly in the starting phase, when there is a high demand for electrical energy anyway.

The disadvantage of requiring a relatively long start-up time under load is not only associated with turbo drive machines, but also turbo work machines. It will also be noticeable if you assign an electric motor to a turbo compressor instead of an exhaust gas turbine.

The invention is generally based on the object to operate internal combustion engines of the piston type with turbo compressors with the simplest and cheapest possible design of the system in such a way that high torques are available even at low engine speeds, unsteady processes (sudden load changes) are coped with as well as possible, without delay optimal adaptation of the gas exchange to the respective operating situation is made possible and at the same time the desire for the most economical and low-emission engines is met.

The solution to this problem is according to the characterizing part of claim 1 is that using the above-mentioned method by a control device, the locking members are mutually opened in a controlled, independent of the working cycle of the engine. This opens up the possibility of supplying the charge air to the combustion chamber during certain operating periods of the engine either via the suction air branch or the compressor branch. According to an advantageous embodiment, the control device switches off the compressor on the air side in the case of predetermined operating states of the engine, while the drive of the charging system is maintained. The compressor is preferably switched off by closing the blocking member in the compressor branch. In order to prevent the compressor, which is still driven, from pumping, the compressor can be short-circuited, for example by a recirculating air valve known per se.

The invention increases the speed at which the speed of the supercharger and thus the delivery rate of the compressor is increased to the required extent by relieving the compressor for a short time, while the resulting delivery rate is taken over by the intake of a corresponding amount of air by the engine. As soon as the supercharger has reached the desired speed, the compressor can be loaded again, leaving it open whether the possibility of air intake of the engine from the environment, i.e. bypassing the compressor, for optimal adjustment of the gas exchange as an alternative function besides the supply of compressed combustion air is maintained or not. With the solution according to the invention, two problems that can be derived from the introductory explanations can be overcome: on the one hand, the charger system must be accelerated as quickly as possible in order to overcome the weakness in starting, which can be achieved by switching off the compressor on the air side in the start-up phase, because this means that the compressor hardly loaded drive unit can reach its operating speed very quickly. On the other hand, switching off the compressor on the air side during engine operation with low load and / or low engine speed can prevent the speed of the charger system from dropping below the minimum speed at which the compressor is ready to produce the desired delivery rate.

A particularly advantageous embodiment of the invention is therefore that the speed of the drive unit is determined by a sensor and a control parameter dependent on this speed is entered into a control device and the

Control device is only able to open the compressor branch when the

Speed of the drive unit has reached a predetermined operating speed.

Another very advantageous embodiment is that the speed of the charger system is limited to a predetermined maximum value and that at lower Engine load, when the air supply to the compressor is not required, the blocking element in the compressor branch is closed in order to remove the compressor from the charge air flow, while the exhaust gas flow drives the compressor, so that the compressor can maintain its operating speed relatively unloaded during engine operation. The automatic speed limitation ensures that the unloaded compressor does not exceed its permissible maximum speed.

For engines whose compressor branch contains an air collector, it must be taken into account that the air density in the air collector determines the degree of charging in the engine, even if additional dynamic compression takes place in the combustion chamber. There is therefore a need to increase the air density in the air collector as quickly as possible above the value in part-load operation when changing from part-load to full-load operation by the compressor used. This requires additional compressor energy for a short time. There is therefore an advantageous embodiment of the invention in that when the blocking member in the compressor branch is closed, the speed of the supercharger system is increased compared to the operating speed when the charge air is supplied via the compressor branch. This prevents the compressor speed from dropping undesirably below the specified operating speed during the transition from part load to full load.

A further advantageous embodiment consists in that the blocking element in the suction air line is opened with a time delay compared to the assigned inlet valve on the combustion chamber and is closed before the dynamically compressed air volume flows back from the combustion chamber. This procedure, which is known per se, initially creates a negative pressure in the combustion chamber, which leads to the fact that, after the blocking member has been opened, the air present at the blocking member flows into the combustion chamber at a higher speed and is compressed by its inherent kinetic energy when it hits the combustion chamber boundary. By closing the blocking element in good time, this compression can be used to increase performance, which is particularly advantageous in the phase in which there is an increased power requirement for starting up the compressor, which in turn cannot contribute to satisfying this power requirement because it is still operating speed has not reached. With the improvement in the performance of the engine during transient operation, the advantageous possibilities of this gas exchange process have not yet been exhausted after it has kept two different combustion air sources available during the engine's operating time, once the compressor has reached its operating speed after starting the engine Selection can be used via the control device, namely the suction air branch and the compressor branch with compressed air. It is therefore possible, depending on the current operating situation of the engine, to select the most favorable charge exchange method. In particular, the engine can be operated not only with charging, but in particular also with recharging, both statically and optionally dynamically. It is a further advantageous embodiment of the invention that after reaching the operating speed of the compressor with a suitable operating situation of the engine, the blocking member in the suction air branch is opened and closed prematurely for each suction stroke in the combustion chamber, whereupon the blocking member in the compressor branch is opened and reloaded for compressed air is closed again.

A particularly advantageous further embodiment consists in that the air from the suction air branch is introduced into the combustion chamber via a first inlet valve and the compressed air from the compressor branch is introduced into the combustion chamber via a second inlet valve, so that the combustion chamber is suction air or compressed as required and at selectable times

Air can be supplied.

In order to improve the emission behavior, in the part-load range, exhaust gas can be exhausted from an exhaust gas recirculation line that can be blocked against backflow into a direction connected to the inlet valve in the direction of the air filter

Shutoff closed area can be introduced, even if during the

Suction strokes are fed to the engine at least a portion of compressed charge air.

The invention also relates to a charge exchange system

Internal combustion engine of the piston type, in particular for carrying out the method explained above, with at least one combustion chamber having at least one inlet valve and one outlet valve and a compressor arranged between an air filter and the inlet valve, the charge air supply to the engine being divided into two parallel line branches, the first of which is the compressor branch leads over the compressor and the second bypasses the compressor as a suction air branch. The invention consists in that the suction air branch and the compressor branch each contain a shut-off device and that at least the shut-off device in the compressor branch can be controlled and the shut-off devices are assigned a control such that only one of the shut-off devices can be opened at the same time , wherein the compressor is preferably part of a charger system to which a sensor for monitoring the compressor speed is assigned, that this sensor is in signal connection with a control unit and the control unit is suitable for opening the shut-off device in the compressor branch only when the sensor signal indicates that the Compressor has reached a predetermined operating speed.

Further expedient configurations consist in the fact that the shut-off element in the suction air branch is a check valve and that both shut-off elements can be controlled.

According to a particularly preferred embodiment, the control unit is suitable for receiving information about the operating state of the engine via a signal input, for closing the blocking element in the compressor branch if this operating state does not require the compressor to be supplied with air, and for limiting the speed of the exhaust gas turbine to a predetermined maximum value ,

A variant of the gas exchange system is that the line branches unite upstream of the inlet valve, but according to an advantageous embodiment, each of the line branches is assigned an inlet valve on the combustion chamber, whereby according to a preferred development, the inlet valves of both line branches are variably controllable inlet valves which are the control device Take over the function of the blocking organs.

Another expedient embodiment consists in that an exhaust gas recirculation provided with a non-return valve, which is expediently provided with a pressure regulator, opens between one of the blocking members and the inlet valve assigned to it.

In order to be able to use dynamic effects when changing the charge, according to a further expedient embodiment, the suction air branch between the air filter and the shut-off device contains an air collector with a subsequent oscillating tube. The compressor branch between the compressor and the shut-off device preferably contains an air collector with a subsequent oscillating tube and the shut-off device is an air cycle valve.

If the supercharger system is a turbocharger, for special applications in which the additional effort is justified, an electric acceleration motor can be assigned to the compressor to further shorten the response time of the turbocharger, and the drive connection between the compressor and an exhaust gas turbine can be provided with a freewheel.

Based on the following description of the embodiments of the invention shown in the drawing, this will be explained in more detail.

1 shows a schematic illustration of an internal combustion engine with a charge exchange system according to the invention with a suction air branch and a compressor branch, the combustion chamber having an inlet valve, FIG. 2 shows an illustration of an internal combustion engine similar to FIG

Combustion chamber is provided with two intake and exhaust valves, Fig. 3rd a schematic representation of a three-cylinder engine with a gas exchange system according to the invention, Fig. 4 shows a variant of the gas exchange system using the example of a

3-cylinder engine, FIG. 5 a representation similar to FIG. 2 of a charge exchange system according to the invention with the possibility of exhaust gas recirculation,

Fig. 6 shows a charge exchange system according to the invention with an electric motor for

Acceleration of the compressor,

Fig. 7 shows a charge exchange system according to the invention with a volume store in the bypass, F Fiigg. 8 8 shows a variant of the charge exchange system shown in FIG. 7,

9 shows a charge exchange system according to the invention with a storage volume downstream of the compressor,

Fig. 10 is a graphical representation of the air expenditure as a function of

Engine speed and charge exchange method and F Fiigg .. 1 111 a variant of the charge exchange system shown in Fig. 9. In the following description, corresponding elements are identified in the individual figures with the same reference numbers.

In the basic configuration shown in FIG. 1 of a charge exchange system suitable for realizing the invention, 10 denotes the combustion chamber in which a piston (not shown) can be moved. The combustion air is fed to the system via an air filter 12 and can enter the combustion chamber 10 during the opening phase of an intake valve 14. When the exhaust valve 16 is open, the exhaust gases flow out of the combustion chamber 10 into an exhaust gas line 18. They can be used in a turbine 20 to drive a compressor 22, by means of which the charge air can be compressed. Turbine 20 and compressor 22 together form the turbocharger. The drive connection between the turbine 20 and the compressor 22 is designated by 24. In the example shown, the exhaust gases can be discharged via a line branch 18a of the exhaust gas line arranged parallel to the turbine 20 or can be conducted via a line branch 18b over the turbine. By means of an adjustable control element 26 in this line branch 18a, the admission of the turbine 20 can be adjusted according to the power requirement. However, it is also possible, for example, to regulate the turbine by adjusting the turbine blades.

The charge air line 28 running between the air filter 12 and the inlet valve 14 on the combustion chamber 10 is likewise in two parallel line branches 28a and 28b

^• divided, the line branch 28b, also called the compressor branch, containing the compressor 22, while the line branch 28a, also called the suction air branch, bypasses the compressor 22 as a bypass. The flow through the suction air branch 28a can be opened or closed by a controllable blocking member 30. Likewise, the flow through the compressor branch 28b can be opened or closed by a blocking member 32. The valve 32 is to be understood symbolically in order to express the possibility of being able to switch off the compressor branch 28b. It must be assumed here that the compressor 22 can be short-circuited, for example by a recirculating air valve known per se, which, like a charge air cooler following the compressor 22, is not shown to simplify the illustration. The locking members 30 and 32 are coordinated by a control device 34 such that only one of the two locking members can be opened. The control device 34 is connected via a signal line 36 to a sensor 38 which is suitable for generating a signal which is dependent on the speed of the compressor 22 and which indicates to the control device 34 whether the speed of the compressor 22 has reached a predetermined operating speed which of the compressors 22 is capable of delivering sufficient compressor output. The blocking member 32 in the compressor branch 28b can only be opened when this operating speed has been reached or exceeded. Otherwise, the air supply to the combustion chamber 10 takes place via the suction air branch 28a with the blocking member 30 open. The acceleration phase of the compressor is noticeably shortened because the drive energy emitted by the turbine 20 after the setting of a pressure equilibrium on the compressor, apart from the resulting frictional losses, without further delivery capacity for acceleration of the compressor 22 is used.

Via a signal line 40, the control device 34 receives information about the

Operating state of the engine. With a low engine load, when the air delivery of the compressor is not required, the control device 34 closes the blocking member 32 in the compressor branch 28b and at the same time opens the blocking member 30 in the suction air branch 28a, whereby the compressor 22 is relieved, while at the same time it continues to be driven by the exhaust gas turbine 20 , So that it does not exceed the permissible maximum speed, the compressor speed is also monitored via the sensor 38 and a signal is sent to the control element 26 via a signal line 42 in order to limit the speed accordingly.

In the event of a sudden increase in the engine load, the control device 34 closes via a

Control line 41, the blocking member 30 in the suction air branch 28a and at the same time opens the blocking member 32 in the compressor branch 28b, the compressor 22 already being at its full operating speed and requiring no time-consuming acceleration.

In the variant shown in FIG. 2, the combustion chamber 10 has two inlet valves

14a and 14b, and two exhaust valves 16a and 16b. The channels of the exhaust gas line 18 connected to the exhaust valves 16a and 16b are first brought together before the exhaust gas line 18 is divided into the line branches 18a and 18b for regulating the turbine 20. O 03/044348

On the inlet side of the combustion chamber 10, the suction air branch 28a bypassing the compressor 22 is connected to the inlet valve 14a, and the compressor branch 28b is connected to the inlet valve 14b. The blocking member 30 is connected upstream of the inlet valve 14a, the blocking member 32 is connected upstream of the inlet valve 14b, these blocking members being actuated in the same way as has already been described for the arrangement shown in FIG. 1. To simplify the illustration, the control device 34 with its signal lines 36, 40, 41 and 42 is only shown in FIG. 1 in order to explain its function. In the arrangements according to FIGS. 2 to 9 it is assumed that there is a corresponding device for the valves which require control. In the arrangement according to FIG. 2, if only a charging operation is desired, only a control of the blocking member 32 is necessary so that the compressor branch 28b is only opened when the compressor 22 has reached its operating speed. The shut-off device 30, on the other hand, can be designed as an inexpensive check valve which, on the one hand, permits suction operation and, on the other hand, prevents the return flow of compressed air to the air filter 12.

The arrangement according to FIG. 2 can also be operated with two controllable air lines in order to effect recharging. The locking member 30 is then closed early on each suction stroke and then compressed air is refilled by opening the locking member 32 late.

Although only one combustion chamber 10 is always shown in FIGS. 1, 2 and 5 to 9, no restriction is to be seen therein. 3 shows in principle the same arrangement that is shown in FIG. 2 for a combustion chamber 10 in its application in a three-cylinder engine. FIG. 4 shows a variant of this, in which, in contrast to FIG. 3, the inlet valves 14a and 14b are designed as variably controllable valves, so that they can take over the task of the blocking members 30 and 32 in FIG. 3. Variable inlet valves are expensive, which is why it can be more advantageous to connect conventional inlet valves with interdependent, mutually opening blocking members 30 and 32. After all, it should be noted that it is fundamentally possible to replace the inlet valves 14a and 14b with their associated and upstream blocking elements 30 and 32 by variable inlet valves, unless - as in the case of FIG. 5 explained in more detail below - exhaust gas recirculation a separate locking member between the confluence of an exhaust gas recirculation line 44 in the charge air line leading to the inlet valve and the air filter 12 is required. In the variant shown in FIG. 5, the exhaust line 1.8 is connected through this return line 44 to the section of the suction air branch 28a located between the blocking member 30 and the inlet valve 14a. The return line 44 contains a pressure control device 46. Before the return line 44 opens into the 5 suction air branch 28a, the return line 44 contains a shut-off device 48, preferably a check valve, which can also be controlled if necessary. The shut-off device 48 on the one hand enables exhaust gas to be returned to the combustion chamber 10, while on the other hand it prevents charge air from escaping via the return line 44 and the exhaust gas line 18. The exhaust gas recirculation is used for emission reasons, in the 0 partial load range, when there is no maximum air requirement of the engine.

So far, exhaust gas recirculation has not become known in the case of supercharged engines, because in such engines the pressure in the intake line is above atmospheric pressure and intake of exhaust gas is therefore not possible. When using the method 5 according to the invention - as shown in FIG. 5 - the return line 44 can open downstream of the blocking member 30 into the suction air branch 28a, but it can also open downstream of the shutoff member 32 into the compressor branch 28b if the engine is operated with recharging or the shut-off device 32 opens later than the inlet valve 14, so that the exhaust gas can reach the combustion chamber 10 before the shut-off device 32 allows compressed air to enter this line branch.

In engine operation with exhaust gas recirculation and recharging, the shut-off elements 30 and 32 are initially closed at the start of the suction stroke in the arrangement shown in FIG. 5, while the open shut-off element 48 prevents the inflow of exhaust gas into the

! 5 combustion chamber 10 enables. The shut-off device 48 is preferably closed before the shut-off device 30 is opened in order to allow air to be drawn in. The shut-off device 30 is closed again while the suction stroke continues. In the area of the bottom dead center of the piston movement, the shut-off device 32 is briefly opened for reloading. The blocking elements 30 and 32 can be used as controlled check valves or as

D air cycle valves should be designed.

If, in special cases, the additional material and space requirements and the load on the electrical system appear to be justifiable, an auxiliary electric drive 50 can be provided - as shown in FIG. 6 - for an additional acceleration of the compressor 22, in which case the drive connection 24 between the turbine 20 and the compressor 22 is provided with a freewheel 52 which, if necessary, allows the compressor 22 to overtake the turbine 20.

7 to 9 show arrangements which each contain an air collector 54 with a subsequent oscillating tube section 56.

The arrangements according to FIGS. 7 and 8 contain the air collector 54 in the suction air branch 28a with an oscillating tube section 56 in front of the shut-off device 30 designed as a check valve. The shut-off device 32 is a controlled check valve. As long as the combustion chamber 10 is supplied via the suction air branch 28a, the late opening of the shut-off element 30 in connection with the pressure wave forming in the oscillating tube section 56 leads to dynamic charging in the combustion chamber 10. During a suction stroke, the blocking element 30 opens once.

8, in contrast to the arrangement according to FIG. 7, is as

Shut-off device 30 an air cycle valve is provided. This valve can be opened twice during the suction stroke and thus operated with early inlet closing and then late inlet opening. With the compressor branch 28b switched off, this also leads to dynamic charging each time the shut-off element 30 is opened.

The arrangement according to FIG. 9 contains the air collector 54 and the oscillating tube section 56 in the compressor branch 28b. , The shut-off device 32 is an air cycle valve, the shut-off device 30 can be a controlled check valve or also an air cycle valve. The combustion chamber 10 can first be supplied with suction air from the suction air branch 28a, whereupon after the shut-off member 30 has been closed and the shut-off member 32 has been opened by the pressure wave from the compressor branch 28b, dynamic recharging takes place. If the combustion chamber 10 is filled only via the compressor branch 28b, a dynamic supercharging can also be carried out with this arrangement via the compressor branch 28b.

In order to demonstrate the versatile possibilities that open up when the invention is applied, the graphic representation in FIG. 10 shows the achievable air expenditure with different charging methods for a speed range from 0.5 to 2.5 × 10 ³ rpm. Due lowermost curve 1 shows how during suction of about 1, 25 x 10 ³ U / min of air consumption gradually increases from about 0.5 to 0.9 at 2 x 10 ³ U / min increases. The one above Curve 2 located shows that with dynamic charging from the suction air branch with late inlet opening and early inlet closing, a somewhat higher air expenditure can be achieved. Curve 3 shows how a much steeper increase in air consumption is possible by charging by means of the compressor, which value is 1.0 at 1.5 × 10 ³ rpm and already at approximately 1.85 × 10 ³ rpm Value 1, 8 reached. Curve 4 shows the superiority of the recharging from the compressor branch, which begins at 1.25 × 10 ³ rpm with an air consumption of approximately 1.5 and reaches 1.8 at 1.5 × 10 ³ rpm. The point N denotes the standard load in city operation, which shows an air consumption of 0.4 at 2 x 10 ³ U / min. The vertical line shows the increase in air demand with a sudden load requirement at constant speed. The charger cannot initially satisfy this air requirement immediately, so that in this case the invention can be used by switching to reloading. This means that the loader conveys approximately the same amount of air, but at the beginning of the suction stroke an amount of air of the order (density) of ρ = 0.75 is sucked in during the next work cycle, so that from one cycle to the next the air is conveyed around it Amount 0.75 increased suddenly.

In the variant of FIG. 9 shown in FIG. 11, it is provided that the suction air branch 28a serving to supply the combustion chambers 10 of a multi-cylinder engine with suction air, which is connected to the cylinder inlet valves 14a via branches 64, and that for supplying the combustion chambers 10 with compressed air Air-serving compressor branch 28b, which leads to an air collector 54, from which oscillating tubes 56 lead to the cylinder inlet valves 14b, are switched on or off alternately for all combustion chambers 10 of the engine by the mode switches 30 and 32 for suction or compressor operation can. A check valve is normally provided in each branch 64 in order to prevent the backflow of compressed air from the combustion chamber 10 to the mode switch 30. However, as shown in FIG. 11, an air cycle valve 60 can also be provided instead of a check valve in order to enable dynamic charging even when the compressor is switched off. In each intake pipe 56, an air cycle valve 62 is connected upstream of the cylinder inlet valve 14b. If the operating mode switch 32 is closed, the compressor 22 is short-circuited via a connection (not shown) between the suction and pressure-side connection, so that it can be driven by the turbine 20 without load. The speed is increased by the control member 26 compared to the operating speed during compressor operation in the direction of the mechanical and thermal limit speed so that when switching to compressor operation by opening the mode switch 32 and g easy closing of the Mode switch 30, the air density in the collector 54 quickly increases to the desired level without the compressor speed falling below the operating speed.

Claims

CLAIMS:

1. Process for changing the charge in a piston-type internal combustion engine, in which a combustion chamber (10) having at least one inlet valve (14) and one outlet valve (16) is provided via an air filter (12)

Charge air is supplied and the charge air is either guided via a compressor branch (28b) of a charger system which contains a compressor (22) for the charge air and a drive unit (20) assigned to the compressor, or via a suction air branch (28a), which as Bypass bypasses the compressor (22), and with blocking elements (32, 30) in the

Compressor branch (28b) and in the suction air branch (28a), characterized in that the blocking members (32, 30) are opened alternately in a controlled manner by a control device (34).

2. The method according to claim 1, characterized in that the control device switches off the compressor on the air side at predetermined operating conditions of the engine while the drive of the charging system is maintained.

3 The method according to claim 2, characterized in that the compressor is switched off by closing the locking member (32) in the compressor branch (28b).

4. The method according to claim 3, characterized in that the speed of the drive unit is determined by a sensor (38) and one of these

Speed-dependent control parameters are entered into a control device (34) and the control device (34) is only able to open the compressor branch (28b) when the speed of the drive unit (20) has reached a predetermined operating speed.

Method according to one of claims 3 or 4, characterized in that the speed of the charger system (20, 22) to a predetermined O 03/044348

The maximum value is limited and that at low engine loads, when the air delivery of the compressor (23) is not required, the blocking member (32) in the compressor branch (28b) is closed.

6. The method according to claim 5 for gas exchange in an engine, the compressor branch (28b) contains an air collector (54), characterized in that when the locking member (32) in the compressor branch (28b) the speed of the charger system (20, 22) compared to Operating speed with charge air supply via the compressor branch (28b) is increased.

7. The method according to any one of claims 1 to 6, characterized in that the blocking member (30) in the suction air branch (28a) with a time delay compared to the associated inlet valve (14, 14a) on the combustion chamber and before the backflow of the thereby dynamically compressed

Air volume from the combustion chamber (10) is closed

8. The method according to claim 7, characterized in that it is used in the starting phase until the compressor (22) has reached its operating speed.

9. The method according to any one of claims 1 to 5, characterized in that after reaching the operating speed of the compressor (22) with a suitable operating situation of the engine at each suction stroke, the blocking member (30) in the suction air branch (28 a) is opened and then compressed for recharging

Air the blocking member (32) in the compressor branch (28b) is opened and closed again.

10. The method according to any one of the preceding claims, characterized in that the air from the suction air branch (28a) via a first

Inlet valve (14a) and the compressed air from the compressor branch (28b) is introduced into the combustion chamber (10) via a second inlet valve (14b).

11. The method according to any one of the preceding claims, characterized in that in the partial load range at the beginning of the suction phase from a lockable against backflow exhaust gas recirculation line (44) exhaust gas in a with the inlet valve (14a, 14b) in connection, in the direction of

Air filter (12) is introduced through a shut-off device (30, 32) closed area.

12. Charge exchange system of an internal combustion engine of the piston type, in particular for carrying out the method according to one of the preceding claims, with at least one at least one inlet valve (14; 14a, 14b) and one outlet valve (16; 16a, 16b) having a combustion chamber (10) and an intermediate one an air filter (12) and the inlet valve (14; 14b) arranged compressor (22), wherein the charge air supply of the engine is divided into two parallel line branches, the first as a compressor branch (28b) over the compressor (22) and the second as a suction air branch (28a) bypasses the compressor, characterized in that the suction air branch (28a) and the compressor branch (28b) each contain a shut-off element (30, 32) and that at least the shut-off element (32) in the compressor branch (28b) can be controlled and the

Shut-off devices (30, 32) a control (34) is assigned such that only one of the shut-off devices can be open at the same time.

13. Charge exchange system according to claim 12, characterized in that the compressor (22) is part of a charger system (20, 22), the speed of which is dependent on the compressor load and which is assigned a sensor (38) for monitoring the compressor speed, that this sensor (38) is in signal connection with a control unit (34) and the control unit (34) is suitable for opening the shut-off device (32) in the compressor branch (28b) only when the sensor signal indicates that the compressor (22) has reached a predetermined operating speed Has.

14. Charge exchange system according to claim 13, characterized in that the shut-off element (30) in the suction air branch (28a) is a check valve.

15. Charge exchange system according to one of claims 12 to 14, characterized in that both locking members (30, 32) can be controlled.

16. Charge exchange system according to one of claims 13 to 15, characterized in that the control unit is suitable for receiving information about the operating state of the engine via a signal input, to close the blocking member (32) in the compressor branch (28b) when this operating state involves air delivery of the compressor (22) does not require, and limit the speed of the exhaust gas turbine (20) to a predetermined maximum value.

17. Charge exchange system according to one of claims 12 to 16, characterized in that the line branches 28a, 28b) unite before the inlet valve (14).

18. Charge exchange system according to one of claims 12 to 16, characterized in that each of the line branches (28a, 28b) has an inlet valve

(14a, 14b) is assigned to the combustion chamber (10).

19. Charge exchange system according to one of claims 12 to 16 and claim 17, characterized in that the inlet valves (14a, 14b) of both line branches (28a, 28b) by the control device (34) are variably controllable inlet valves which take over the function of the blocking members.

20. Charge exchange system according to claim 18, characterized in that between one of the locking members (30, 32) and that assigned to it

Inlet valve (14a, 14b) opens an exhaust gas recirculation (44) provided with a non-return valve.

21. Charge exchange system according to claim 19, characterized in that the exhaust gas recirculation (44) is provided with a pressure regulator (46). '

22. Charge exchange system according to one of claims 13 to 19, characterized in that the suction air branch (28a) between the air filter (12) and shut-off device (30) contains an air collector (54) with a subsequent oscillating tube (56).

23. Charge exchange system according to one of claims 13 to 19, characterized in that the compressor branch (28b) between the compressor (22) and the shut-off device (32) contains an air collector (54) with a subsequent oscillating tube (56) and the shut-off device (32) contains an air cycle valve is.

24. Charge exchange system according to one of claims 13 to 23, characterized in that the charger system (20, 22) is a turbocharger and the compressor is associated with an electric acceleration motor and that the drive connection between the compressor and an exhaust gas turbine is provided with a freewheel.