METHOD FOR OPERATING A SUPERCHARGED INTERNAL COMBUSTION ENGINE AND DEVICE FOR PROVIDING COMBUSTION AIR FOR A SUPERCHARGED INTERNAL COMBUSTION ENGINE

Abstract

The disclosure relates to a method for operating a supercharged internal combustion engine having at least one cylinder group with a number n of combustion chambers, wherein, during a first operating state, all n combustion chambers are supplied with combustion air via a primary charge air path and, during a second operating state, only a portion of the n combustion chambers are supplied with combustion air from the primary charge air path and another portion of the n combustion chambers are supplied with combustion air from a separate compressed air reservoir.

Claims

1. A method for operating a supercharged internal combustion engine having at least one cylinder group with a number of n combustion chambers, wherein, during a first operating state, all n combustion chambers are supplied with combustion air via a primary charge air path and, during a second operating state, only a portion of the n combustion chambers are supplied with combustion air from the primary charge air path and another portion of the n combustion chambers are supplied with combustion air from a separate compressed air reservoir.

2. The method according to claim 1, wherein the n combustion chambers are an integral part of a cylinder bank of the supercharged internal combustion engine, wherein the n combustion chambers comprise all combustion chambers of the cylinder bank arranged in a row or only a portion of combustion chambers of the cylinder bank arranged in the row, or the n combustion chambers are in each case arranged in opposite positions in a plurality of rows.

3. The method according to claim 1, wherein the number n is an even or odd number, wherein in the second operating state an air supply to the n combustion chambers is divided symmetrically or asymmetrically from the primary charge air path and the separate compressed air reservoir.

4. The method according to claim 3, wherein in the second operating state the air supply to a respective combustion chamber is independent or largely independent of whether this combustion chamber is supplied via the primary charge air path or from the compressed air reservoir.

5. The method according to claim 1, wherein a transition from the first into the second operating state is triggered on account of a short-term significant rise in a target power output of the internal combustion engine.

6. The method according to claim 1, wherein the n combustion chambers are supplied by two or more separate air manifolds, wherein the primary charge air path in the first operating state is split over two or more separate paths to supply the two or more air manifolds in parallel and in the second operating state the primary charge air path supplies charge air to only one or at least only a portion of the two or more separate air manifolds supplied with charge air in the first operating state, whereas the other portion of the two or more separate air manifolds is supplied from the compressed air reservoir.

7. The method according to claim 1, wherein in low-load operation a cylinder deactivation is performed, wherein an active cylinder group, depending on the operating state, is supplied with combustion air either only via the primary charge air path or alternatively is supplied with combustion air via the primary charge air path and at the same time from the compressed air reservoir.

8. The method according to claim 1, wherein the compressed air reservoir can be supercharged by a separate compressed air source with ambient air and/or by the primary charge air path, wherein a supercharging is performed if a pressure level within the compressed air reservoir below a minimum threshold value, wherein a supercharging of the compressed air reservoir via the primary charge air path is provided only in a lower pressure range, whereas the compressed air reservoir is supercharged via the separate compressed air source.

9. The method according to claim 1, wherein, depending on an air volume currently provided from the compressed air reservoir, a second charge air compressor acting in the primary charge air path is actuated temporally in parallel, and/or wherein, depending on the air volume currently provided from the primary charge air path, a valve is actuated temporally in parallel or a valve arrangement is actuated temporally in parallel in order to adapt the air volume.

10. The method according to claim 1, wherein the air stored in the compressed air reservoir is heated.

11. The method according to claim 1, wherein, during a third operating state, only those combustion chambers of the n combustion chambers that draw their combustion air from the compressed air reservoir are supplied with fuel.

12. A device for providing combustion air in a supercharged internal combustion engine having at least one cylinder group comprising a number n of combustion chambers, wherein the device contains two or more separate air manifolds, a primary charge air path containing at least one apparatus for compressing the charge air, and at least one compressed air reservoir, wherein a valve arrangement is provided in order to supply the two or more air manifolds selectively with combustion air through the primary charge air path or alternatively to supply only a portion of the separate air manifolds with combustion air from the primary charge air path, while (i) the entire remaining portion of the separate air manifolds or (ii) only a sub-group of the remaining portion of the separate air manifolds can be supplied with combustion air from the compressed air reservoir.

13. The device according to claim 12, wherein the n combustion chambers are an integral part of a cylinder bank of the internal combustion engine, wherein the n combustion chambers comprise all combustion chambers of the cylinder bank arranged in a row or only a portion of the combustion chambers of the cylinder bank arranged in a row, or the n combustion chambers are in each case arranged in opposite positions in a plurality of rows of multiple cylinder banks.

14. The device according to claim 12, wherein the device has a controller which is configured to carry out a method wherein, during a first operating state, all n combustion chambers are supplied with combustion air via a primary charge air path and, during a second operating state, only a portion of the n combustion chambers are supplied with combustion air from the primary charge air path and another portion of the n combustion chambers are supplied with combustion air from a separate compressed air reservoir.

15. The device according to claim 14, wherein the compressed air reservoir is connected to at least one of the air manifolds via at least one compressed air control valve, wherein the compressed air control valve is actuatable by the controller.

16. The device according to claim 15, wherein the primary charge air path of a combustion chamber group is permanently fluidically connected to at least one or a portion of the air manifolds and at least one charge air control valve is provided in the fluid connection to at least one other air manifold.

17. The device according to claim 16, wherein the charge air control valve is directly connected to the compressed air control valve.

18. The device according to claim 16, wherein the charge air control valve is externally actuatable or is configured as a non-return valve.

19. The device according to claim 12, wherein the compressed air reservoir is connected to a compressed air source that is separate or is already provided otherwise, and/or is connectable to the primary charge air path for supercharging the compressed air reservoir, wherein the compressed air source can be driven via a power take-off of the internal combustion engine.

20. The device according to claim 19, wherein two or more charge air compressors connected in series are provided in the primary charge air path, wherein at least one of the charge air compressors can be operated according to the requirements.

21. An internal combustion engine comprising at least one device according to claim 1.

22. The internal combustion engine according to claim 21, wherein the internal combustion engine comprises a plurality of combustion chamber groups each having at least a number n of combustion chambers, wherein each combustion chamber group comprises a device for providing combustion air in the supercharged internal combustion engine, wherein the device contains two or more separate air manifolds, a primary charge air path containing at least one apparatus for compressing the charge air, and at least one compressed air reservoir, wherein a valve arrangement is provided in order to supply the two or more air manifolds selectively with combustion air through the primary charge air path or alternatively to supply only a portion of the separate air manifolds with combustion air from the primary charge air path, while (i) the entire remaining portion of the separate air manifolds or (ii) only a sub-group of the remaining portion of the separate air manifolds can be supplied with combustion air from the compressed air reservoir.

23. The internal combustion engine according to claim 22, wherein the compressed air reservoirs of the at least two devices can be supercharged by a common external pressure source.

24. A system which is operated by a dynamically operated internal combustion engine, in particular in an on-road, off-road or an off-highway system with a device according to for providing combustion air in the supercharged internal combustion engine, wherein the device contains two or more separate air manifolds, a primary charge air path containing at least one apparatus for compressing the charge air, and at least one compressed air reservoir, wherein a valve arrangement is provided in order to supply the two or more air manifolds selectively with combustion air through the primary charge air path or alternatively to supply only a portion of the separate air manifolds with combustion air from the primary charge air path, while (i) the entire remaining portion of the separate air manifolds or (ii) only a sub-group of the remaining portion of the separate air manifolds can be supplied with combustion air from the compressed air reservoir.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0047] Further advantages and features of the disclosure will be explained in greater detail below with reference to an exemplary embodiment shown in the figures, in which:

[0048] FIG. 1: shows a first exemplary embodiment of an internal combustion engine according to the prior art;

[0049] FIG. 2: shows a second exemplary embodiment of an internal combustion engine known from the prior art;

[0050] FIG. 3: shows a first exemplary embodiment of an internal combustion engine according to the disclosure;

[0051] FIG. 4: shows a second exemplary embodiment of an internal combustion engine according to the disclosure;

[0052] FIG. 5: shows a schematic representation illustrating the combination of the method according to the disclosure with a possible cylinder deactivation; and

[0053] FIG. 6: shows a third exemplary embodiment of an internal combustion engine according to the disclosure;

[0054] FIG. 7: shows a fourth exemplary embodiment of an internal combustion engine according to the disclosure.

DETAILED DESCRIPTION

[0055] A method or a device for increasing the dynamics of an internal combustion engine represents an essential core aspect of the disclosure. An important component of the disclosure is at least one additional compressed air reservoir from which combustion air can be supplied to the combustion chambers temporarily and additively to the primary charge air path. In the event of a requirement for a correspondingly strongly pronounced increase in the target power output of the internal combustion engine—more precisely expressed in the event of a correspondingly strong level increase in the target power output in the presence of a large time gradient—a boost process takes place to better overcome the so-called ‘turbo lag’, in which compressed air is taken from the compressed air reservoir and is used as additional charge air, i.e. Is added to the charge air flowing in via the regular (primary) air path. The volume of the increased air supply into the combustion chambers is matched by an increase in fuel supply.

[0056] The core of the disclosure is evident in the overall topology of the air path at the component level. The arrangement of a topology according to the disclosure has the effect that the compressed air provided during a boost process is already directly supplied to the combustion; however, in doing so, it is only supplied to a portion of the existing combustion chambers of the internal combustion engine, whereas the remaining others or a portion of the remaining combustion chambers continue to receive their charge air via the regular air path, i.e. the air path on which the charge air compressor of the exhaust gas turbocharger acts.

[0057] This offers the great advantage that, even during a boost process, in which the total air supply to the combustion chambers is supported by taking compressed air from the compressed air reservoir,

[0058] the currently available air mass flow, which is available via the regular air path, can continue to be used and at the same time

[0059] the air volume taken additionally from the compressed air reservoir can be fed directly into the relevant combustion chambers of the internal combustion engine, i.e. it can already be used additively on the air side and thus

[0060] the turbine of the exhaust gas turbocharger can immediately draw a higher energy volume from the exhaust gas.

[0061] The specific exemplary embodiment of FIGS. 3, 4 shows a six-cylinder in-line engine as an example. In a simple embodiment, it is an internal combustion engine supercharged in a single stage by means of an exhaust gas turbocharger 22. The exhaust gas turbocharger 22 comprises a turbine 22a which is driven by the exhaust gas supplied from the exhaust gas collector 35. The mechanical power available as a result drives the charge air compressor 22b. A split 23, 23′ of the air path extending via the charge air compressor 22b ensures that a group of combustion chambers 21 is supplied with air via separate air manifolds 24A and 24B. The provision of charge air via the charge air compressor 22b is understood as a primary charge air path or regular charge air path in the exemplary embodiment shown.

[0062] In a basic consideration of the disclosure, the second charge air compressor 25 shown in FIG. 3 can be disregarded. Detailed explanations will be provided later in the context of a modified exemplary embodiment. If an additional second charge air compressor 25 is not provided, the upper pressure side of the charge air compressor 22b of the exhaust gas turbocharger 22 is connected to the inlet of the charge air cooler 26 with regard to the air path. In the case of a closed compressed air control valve 27, the air supply of the activated combustion chambers 21 takes place exclusively via the charge air compressor 22b, wherein it is provided in a possible embodiment of the disclosure that the charge air control valve 28 is permanently open during normal operation of the internal combustion engine. Therefore, in a simple embodiment, this can be configured as a passive non-return valve which, in the event of a higher pressure on its right-hand side compared to its left-hand side, blocks the air path extending from the charge air compressor 22b to the air manifold 24B and otherwise releases this air path.

[0063] In an alternative embodiment, which, however, is not the central focus of the disclosure, the charge air control valve 28 can be externally controllable via an optional interface 28a. Such an external actuation means 28a may allow the closing of the charge air control valve 28 even if there is no positive pressure on the right side thereof. However, the use of such a valve type may be used which, in the event of an overpressure prevailing on the right-hand side of the charge air control valve 28 compared to the pressure level prevailing on the left-hand side, closes automatically and remains closed until the pressure level on the right-hand side falls below a value which is slightly greater than that of the pressure level on the left-hand side. In particular, such an embodiment of the charge air control valve 28 which closes within the shortest possible time when a pressure wave with a correspondingly strongly pronounced pressure level arrives on the right side may be used.

[0064] Optionally, the device according to the disclosure is configured in such a way that, when the charge air control valve 28 is open, the air distribution between the individual air manifolds 24A, 24B and between the combustion chambers 21 is as uniform as possible. More precisely, the device according to the disclosure could optionally be configured accordingly in such a way that, when a charge air control valve 28 is open and a compressed air control valve 27 is closed, the air supply to a combustion chamber is independent of whether it receives its combustion air via the air manifold 24A or 24B, provided that all other influencing parameters are the same, such as the air valve control times, the pressure of the charge air at the charge air outlet of the exhaust gas turbocharger, etc.

[0065] If the load profile to be produced by the internal combustion engine has a comparatively low dynamic and no supercharging of the compressed air reservoir 2 using the charge air compressor 22b is currently or generally intended, the compressed air control valve 27 remains closed. The right-hand port of the compressed air control valve 27 is connected to a compressed air reservoir 2. Alternatively or additionally, the compressed air reservoir 2 can be supercharged via a compressed air source 3, for example an air compressor. The compressed air source 3 is connected to the compressed air reservoir 2 via a non-return valve 29. An air supply from the compressed air source 3 is provided when the pressure level in the compressed air reservoir 2 has fallen below a certain threshold value S1 and continues until a certain threshold value S2 has been reached.

[0066] The compressed air control valve 27 is opened and closed remotely via the control interface 27a and is determined via a control system. In the event of a failure of the control signal for the compressed air control valve 27, this should close and remain permanently closed.

[0067] If a correspondingly fast increase in power output by a correspondingly high absolute amount is demanded from the internal combustion engine, the intervention of the system according to the disclosure causes an increased dynamic for an increase in its power output, wherein this dynamic increase is dependent on the currently present speed-torque operating point. Using the system according to the disclosure, a very clear approximation to the setpoint of the speed-torque trajectory curve is achieved even in the case of demanded power increases that are extremely difficult or virtually impossible to fulfil.

[0068] The presence of a correspondingly strongly pronounced time gradient of the target power output by a correspondingly high absolute amount causes the compressed air control valve 27 to open. This in turn triggers a pressure wave that reaches the charge air control valve 28, causing it to close. As a result, the charge air provided via the regular air path only reaches the three left combustion chambers 21 shown here, which are connected to the air manifold 24A, whereas the three right combustion chambers 21 obtain their charge air exclusively from the compressed air reservoir 2 via the air manifold 24B. Such an option allows a very significant increase in the air supply to the combustion chambers 21 of the internal combustion engine, moreover within a very short reaction time.

[0069] In an embodiment, a compressed air control valve 27 is located within the air path from the compressed air reservoir 2 and is configured in particular as a controllable compressed air control valve 27 or is embedded in a control circuit. Based on this, the system can be configured to distribute air as evenly as possible between the two air manifolds 24A, 24B and thus the corresponding combustion chamber groups. An air supply that ideally has the same volume for each combustion chamber 21 in relation to the cycle clearly only results in stationary operation of the internal combustion engine.

[0070] In order to be able to use the possibility of a quasi abrupt rise to a very significantly increased air supply volume to achieve a desired dynamic increase in the power output of an internal combustion engine, the engine must be equipped with a fuel supply system that allows a correspondingly dynamic increase in the fuel supply rate.

[0071] As already indicated above, the second charge air compressor 25 shown in FIG. 3 acting as a further compressor stage is merely optional. In the case of two-stage supercharging, the primary air path—as shown in FIG. 3—can have a so-called intercooler (not present in FIG. 3) in relation to the air flow direction between the first charge air compressor 22b and the second charge air compressor 25, wherein the supply of cooling power or the dissipation of waste heat takes place as required. The second charge air compressor 25 can be driven, for example, by means of an electric motor 25a.

[0072] If the internal combustion engine operates in a low to middle load operation and with comparatively low dynamics, the air to the n combustion chambers 21 is optionally supplied using only the charge air compressor 22b of the exhaust gas turbocharger 22. Of course, a temporary bypass of the compression stage of the charge air compressor 25 is fluidically advantageous if the charge air required by the internal combustion engine can already be provided using only the charge air compressor 22b. For the sake of simplicity, the bypass is not shown in the circuit diagram in FIG. 3.

[0073] In the case of briefly occurring power peaks demanded by the internal combustion engine, depending on the time gradient and the amplitude of a particular power peak as well as depending on the system designs of the charge air compressor 25, operable according to the requirements, and of the device with which an increase in the air supply into the combustion chambers 21 of the internal combustion engine is possible by means of a compressed air withdrawal from the compressed air reservoir 2, one of these two boost systems or both boost systems ([a] the charge air compressor 25 operable according to the requirements and [b] the system which allows an increase in the air supply volume into the combustion chambers 21 of the internal combustion engine by means of a compressed air withdrawal from the compressed air reservoir 2) is used in order to achieve a shorter rise time of the power output of the internal combustion engine by means of an increase in the fuel injection volume thus possible or admissible. The same applies if there is a correspondingly strongly pronounced time gradient of the power output of the internal combustion engine in order to be able to provide a correspondingly increased level of its power output in the short term in accordance with the target specification.

[0074] As can be seen in FIG. 3, in this exemplary embodiment the compressed air which can be taken from the compressed air reservoir 2 can be supplied only to the three combustion chambers 21 arranged on the right-hand side, whereas the common air supply via the charge air compressor 22b of the exhaust gas turbocharger 22 and the charge air compressor 25 operable according to the requirements can be supplied to all combustion chambers 21 or alternatively to the three left-hand combustion chambers 21, which can be reached via the air manifold 24a. Accordingly, in an advantageous configuration—naturally assuming a charged compressed air reservoir 2—starting from the compressed air reservoir 2, an air supply to the three combustion chambers 21 arranged on the right-hand side is possible which is approximately of the same magnitude as the air supply to the three combustion chambers 21 arranged on the left-hand side by a joint use of the exhaust gas turbocharger 22 and of the second charge air compressor 25, which is operable according to the requirements. Alternatively or additionally, in an advantageous configuration, within a range of the power output of the internal combustion engine in which the predominant or the clearly predominant energy conversion of the internal combustion engine is present, the air supply of the combustion chambers 21 can be covered with respect to an operation with a moderate dynamic using the exhaust gas turbocharger 22 alone. Alternatively or additionally, in an advantageous configuration, the air supply to the combustion chambers 21, which is required over a longer period of time—starting from an order of magnitude of, for example, 10 seconds up to continuous operation—can be covered with simultaneous use of the exhaust gas turbocharger 22 and of the charge air compressor 25, which is operable according to the requirements.

[0075] If the engine application envisages operation of the electrically driven charge air compressor 25 also outside of short acceleration processes, it makes sense to integrate a so-called ‘intercooler’ in the primary air path, i.e. a cooler through which the charge air flow passes after leaving the compressor 22b of the exhaust gas turbocharger 22 and before flowing into the externally driven charge air compressor 25.

[0076] Such an overall system, in which the air supply to the combustion chambers 21—as described above—is staggered in three parts, offers the advantage that the exhaust gas turbocharger 22 and the additionally connectable charge air compressor 25 operate within a restricted operating range and can accordingly be designed more favorably and/or are operated collectively under a higher efficiency. Within a certain range (i) in relation to the level of the air mass flow required to support the exhaust gas turbocharger 22 and (ii) up to a certain duration of this support, this can be operated optionally using the second charge air compressor 25, which is operable according to the requirements, and/or the compressed air which can be drawn from the compressed air reservoir 2. The degree of freedom that exists here offers a certain potential for optimization which, taking into account one or more different aspects, makes a selection as to whether short-term support of the exhaust gas turbocharger 22 for supplying air to the combustion chambers 21 is to be provided by using the second charge air compressor 25, which is operable according to the requirements, or the compressed air that can be drawn from the compressed air reservoir 2 or a certain division between these two systems with regard to air supply. Possible criteria for such a division are, without claiming to be exhaustive, an energy consideration, a wear consideration, etc. In the simplest case, such considerations can be made on the basis of an estimated constant value, in a somewhat differentiated consideration by means of a characteristic diagram or by means of a so-called cost function, which in an embodiment even takes into account component ageing or an extrapolated remaining component service life.

[0077] The boost system according to the disclosure can also advantageously be used for an internal combustion engine which is appropriately equipped to allow deactivation of a cylinder group containing at least one cylinder during its partial load operation. An exemplary embodiment configured for this purpose is shown in FIG. 4. Here too, as in FIG. 3, the principle is explained on the basis of a 6-cylinder in-line engine. Components that are functionally identical in terms of their effect on the overall system are marked by identical reference signs in FIGS. 3 and 4.

[0078] The internal combustion engine of FIG. 4 also has two separate air manifolds 24A and 24B. If the internal combustion engine has already been operated in the upper load range for a considerable time, the two charge air control valves 30 and 31 are open, so that downstream of the charge air compressor 22b a split 23′ of the charge air flow into two partial flows takes place, but all combustion chambers 21 are nevertheless supplied exclusively by the air compressed via the charge air compressor 22b of the exhaust gas turbocharger 22. In a lower partial load operation of the internal combustion engine, there is a corresponding position of the charge air control valves 30 and 31 (only one of the charge air control valves 30, 31 is open), in which the charge air reaches either those combustion chambers 21 that are accessible via the air manifold 24A or those combustion chambers 21 that are accessible via the air manifold 24B. The compressed air control valves 32 and 33 remain closed. The intake and exhaust valves of the deactivated cylinders 21 may remain permanently closed for the duration of that cylinder deactivation. If necessary, the compressed air source 3 is used to feed air into the compressed air reservoir 2 until a certain pressure level has been reached therein.

[0079] Based on the operating situation that the charge air control valve 30 is open and the charge air control valve 31 is closed and consequently only the left three cylinders are active whereas the right three cylinders are deactivated, there is now a sharp rise in the target power output of the internal combustion engine. As soon as the strong rise in the target power output is detected in a corresponding evaluation unit, the compressed air control valve 32 is opened via a corresponding actuator and the three remaining cylinders are activated, i.e. the fuel supply and the valve movements of the inlet and outlet valves are activated, while the valve position of the charge air control valves 30 and 31 is maintained. As already mentioned, this results in an addition of the two air volumes. The supply path of the first air volume runs via the charge air compressor 22b extending through the air manifold 24A into the combustion chambers 21 accessible via said manifold. Via the second air path, which is completely separate from the first air path under the premise of the position of the charge air control valves 30, 31 and of the compressed air control valves 32, 33 mentioned here, air originating from the compressed air reservoir 2 reaches the combustion chambers 21 of the internal combustion engine accessible via the air manifold 24B. Due to the design of the exemplary embodiment according to FIG. 4, there is a valve position of the charge air control valves 30, 31 and compressed air control valves 32, 33 by which, as an alternative to the foregoing, a modified constellation exists, in which the charge air provided via the charge air compressor 22b of the exhaust gas turbocharger 22 can be supplied exclusively to the combustion chambers 21 connected via the air manifold 24B and an exclusive inflow of the air which can be taken from the compressed air reservoir 2 into the combustion chambers 21 connected via the air manifold 24A is possible.

[0080] With regard to the basic functionality, there is no need for a crosswise exchange of the combustion chamber groups supplied via the charge air compressor 22b and of the combustion chamber groups supplied via the compressed air reservoir 2 for a use of the system solution according to the disclosure. In the application, during partial load operation, in which only a portion of the cylinders 21 is operated, a regular exchange of the operating mode (i) cylinders with fuel supply present and (ii) deactivated fuel supply is advisable, since otherwise many such loads, which lead to ageing of the engine components, are less distributed, but rather more focused on certain partial areas of the combustion engine, which is equally reflected in the component wear. Another significant advantage of this mode of operation is that the operating temperature of the cylinders that are deactivated is at least approximately maintained.

[0081] For clarification of the aforementioned cylinder deactivation, please refer to the schematic diagram in FIG. 5. The principle of cylinder deactivation is shown here on the basis of a V16 internal combustion engine. Sensible deactivation patterns of the combustion chambers are shown here under a) and b). In the first example a), all cylinders of one bank remain active, while the second cylinder bank is completely deactivated. However, according to the second example b), it may also be useful to deactivate cylinders of both the first and the second cylinder bank, wherein here specifically the first four cylinders of the first bank remain active while cylinders 5 to 8 are deactivated. For the second bank, the cylinders 1 to 4 are deactivated instead, while cylinders 5 to 8 remain active. The deactivation patterns explained above assumed a suitable crankshaft spider (crank) in conjunction with a suitable firing sequence.

[0082] FIG. 6 shows an embodiment of the disclosure for a V16 internal combustion engine. The internal combustion engine comprises n=8 combustion chambers 21 per cylinder bank. The illustrated system according to the disclosure now comprises exactly one device according to the disclosure per cylinder bank, i.e. a separate primary charge air path is provided per cylinder bank. The separate primary charge air paths each comprise an exhaust gas turbocharger 22′, 22″ as well as a charge air cooler 26′, 26″ in order to be able to supply charge air to the two air manifolds 24A′, 24B′ and 24A″, 24B″, respectively. Likewise, a separate compressed air reservoir 2′, 2″ is provided for each cylinder bank. The two devices according to the disclosure are constructed and function as shown in the embodiment from FIG. 3. A structurally possible and, at the same time, with a corresponding design, technically sensible cylinder deactivation pattern for the V16 internal combustion engine shown in FIG. 6 is illustrated in the lower schematic diagram of FIG. 5. For these reasons, a more detailed description can be omitted here. Only the second compressor 25 shown in FIG. 3 is not shown in FIG. 6. However, it would be possible to integrate a second compressor stage in each or only one of the devices shown in FIG. 6.

[0083] In the exemplary embodiment shown in FIG. 6, the two compressed air reservoirs 2′, 2″ can be recharged via the same air compressor 3′. The presence of two separate (independently operable) compressed air reservoirs 2′, 2″ can be advantageous for reasons of installation space, for example.

[0084] FIG. 7 shows an embodiment of the disclosure for a V10 internal combustion engine comprising five combustion chambers 21 per cylinder bank and two devices according to the disclosure. However, in this exemplary embodiment, a device according to the disclosure does not serve to supply air to such combustion chambers, which are each arranged in one and the same bank. Instead, a combustion chamber group of which the air supply is provided via a shared device according to the disclosure contains combustion chambers 21 which, although locally adjacent, are arranged in two different cylinder banks.

[0085] Lastly, two comments on FIGS. 6 and 8 should not go unmentioned: In an actual implementation of a V16 internal combustion engine according to the disclosure, which is designed in accordance with FIG. 6, the air supply to the combustion chambers 21 would certainly be placed between the two cylinder banks so that the exhaust gas, due to its high temperature, can be discharged from the central region of the internal combustion engine over the shortest possible distance in each case. However, the representation chosen in FIG. 6 increases the clarity of the air paths shown in terms of circuit layout. In this respect, the circuit diagram of the V10 internal combustion engine shown in FIG. 7 is oriented rather towards an actual implementation. In this circuit diagram, the air is distributed to the various combustion chambers 21 starting from the central region, while the exhaust gas is discharged to outside the combustion engine. For the sake of clarity, however, the two air sections, each equipped with a device according to the disclosure, are drawn on two diametrical sides of the internal combustion engine in that diagram, which would clearly be less practicable in an actual set-up.

[0086] The advantages of the disclosure can be summarized again compactly below:

[0087] When the boost system according to the disclosure in FIG. 3 is actuated, air is supplied to the combustion chambers 21 simultaneously in an additively acting manner by means of the primary air path via the charge air compressor 22b of the exhaust gas turbocharger 22 and from the compressed air reservoir 2. By contrast, the prior art boost system according to FIG. 1 has a substituting effect because, during boost operation, the air supply via the regular air path is overridden.

[0088] Clearly—as already mentioned—the increased air supply to the combustion chambers during a boost operation takes place under a coordinated increase in the fuel supply volume. In the boost system according to the disclosure, the increased air supply volume resulting from an activation of the boost function is directly supplied to the combustion chambers 21. Consequently, a boost operation of an internal combustion engine according to the disclosure leads to an increased release of thermal energy within the combustion chambers 21, which is available to the exhaust gas aftertreatment system. By contrast, a prior art system according to FIG. 2, in which the compressed air which can be taken from the compressed air reservoir unit 2 is fed directly into the exhaust gas path of the internal combustion engine, leads to a very significant reduction in the exhaust gas temperature.

[0089] From the perspective of the combustion chambers, boost operation means a particularly rapid increase in the volume of the supplied fuel-air mixture, which results in an increase in the formation of nitrogen oxides. Consequently, the supply rate of the reducing agent must or would have to be significantly increased so that (almost) complete degradation of the nitrogen oxides can take place, which is mandatory for compliance with the binding exhaust emission regulations. This is not a problem if the exhaust gas temperature is sufficiently high, whereas an exhaust gas temperature that is too low must be avoided at all costs.

[0090] If, however, the exhaust gas temperature or the temperature in the exhaust gas aftertreatment system is too low for the quantity of nitrogen oxides contained in the exhaust gas, then—without taking the thermal conditions into account—a purely quantitatively sufficiently high reducing agent supply rate would by no means result in a sufficiently high conversion rate of the nitrogen oxides. Such a mode of operation would even be counter-productive in several ways. The volume of reducing agent supplied, which in any case cannot contribute to the reduction of nitrogen oxides, would cause a lowering of the already too low temperature in the exhaust gas aftertreatment system and thus trigger a further weakening of the conversion rate. Furthermore, a portion of the supplied reducing agent, which does not participate in the chemical reduction for the degradation of nitrogen oxides, adheres to the catalyst surface, which cumulatively leads to the ineffectiveness of the catalyst. Consequently, an excess of reducing agent must be avoided as far as possible, wherein the purely quantitative consideration must be supplemented with a consideration of the temperature influence.

[0091] If the temperature within the exhaust gas aftertreatment system is too low to achieve a (practically) complete reduction of nitrogen oxides, a corresponding reduction of the reducing agent supply rate is the least worst option. Nevertheless, it is not possible to comply with bindingly applicable emission regulations, which prohibits the operation of such an internal combustion engine.

[0092] Accordingly, the system according to the disclosure has the advantages and resulting advantages of the two previously known systems. Furthermore, the disadvantages and consequential disadvantages of the two already known systems do not exist in the system according to the disclosure. It should be noted that with regard to the system solution according to FIG. 1, a compressed air reservoir 2 used for this purpose must have a substantially higher storage capacity (for example using an increased reservoir volume and/or an increased pressure level) so that an increase in dynamics comparable to that of the system according to the disclosure can be achieved with this already known system. Consequently, in the embodiment according to FIG. 1, a longer period of time must be accepted until the boost function is available again or a correspondingly more complex on-board device, for example an air compressor, must be used, with which a higher air supply rate into the pressure reservoir 2 is possible and, if necessary, a higher pressure level can be generated.

[0093] It should also be noted that, with regard to the system solution according to FIG. 2, an exhaust gas turbocharger 1 must be used which must be equipped with two turbine wheels in order to allow the boost system to be used as additively as possible. In order to ensure high availability of the boost function under the aspect of mandatory compliance with exhaust gas limits, the exhaust gas path and the compressed air path must be hermetically separated from each other. This requires an adaptation of the exhaust gas turbocharger 1, the effort for which is very high.

LIST OF REFERENCE CHARACTERS

[0094] exhaust gas turbocharger 1 [0095] compressed air reservoir 2, 2′, 2″ [0096] compressed air source 3, 3′, 3″ [0097] switching elements 4, 5, 6 [0098] air manifold 7 [0099] combustion chamber 8 [0100] exhaust gas collector 10 [0101] combustion chamber 21 [0102] exhaust gas turbocharger 22, 22′, 22″ [0103] turbine 22a [0104] charge air compressor 22b [0105] split 23 [0106] air manifold 24A, 24B, 24A′, 24B′, 24A″ 24B″ [0107] charge air compressor 25 [0108] electric motor 25a [0109] charge air cooler 26, 26′, 26″ [0110] compressed air control valve 27, 27′, 27″, 32, 33 [0111] control interface 27a [0112] charge air control valve 28, 28′, 28″, 30, 31 [0113] control interface 28a [0114] non-return valve 29, 29′, 29″ [0115] exhaust gas collector 35