DE102019124961B4 - Drive arrangement with switchable exhaust valves - Google Patents

Abstract

Drive arrangement (8), having- an internal combustion engine (10) with at least four cylinders (1, 2, 3, 4), each having a first (R) and at least one second (L) exhaust valve, and with an exhaust manifold (20) for discharging the exhaust gases, - an exhaust gas turbocharger (12) with a mono-scroll turbine (18), which is connected to the first (R) and second (L) exhaust valves of the internal combustion engine via the exhaust manifold for exhaust gas routing, - a control unit (11 ), which is set up to a) activate all exhaust valves (R, L) of the cylinders in a high-load mode (200), andb) in a partial-load mode (200) for one, several or all cylinders (1, 2, 3, 4 ) to activate the first exhaust valve (R) and to deactivate the second exhaust valve (L), characterized in that the first exhaust valves (R) are operated with a first exhaust timing (T1) that is shorter than a second exhaust timing (T2), with which the second outlet valves (L) are operated.

Description

The invention relates to a drive arrangement with an internal combustion engine with at least four cylinders, each with a first and at least one second exhaust valve. Furthermore, the invention relates to a motor vehicle with such a drive arrangement.

Various operating methods for such drive assemblies are well known. In addition, internal combustion engines are known in which the gas exchange valves are actuated via switchable rocker arms. In an activated state, such rocker arms interact with a camshaft and can thus actuate the gas exchange valves. In a deactivated state, the rocker arms do not actuate the gas exchange valves, regardless of the position of the camshaft. The exhaust valves can also be deactivated via other mechanisms such as sliding cams.

An internal combustion engine equipped with such rocker arms can therefore assume two operating states. The gas exchange valves are activated in normal operation and deactivated in deactivation operation. The deactivation mode can e.g. B. be used for a reduction of an engine drag torque.

However, if both exhaust valves are either activated together or deactivated together, the required power cannot be provided as efficiently as possible in every operating state of the internal combustion engine. Likewise, an optimal ratio of favorable fuel consumption and environmentally friendly emission behavior cannot be achieved in every operating condition.

From the DE 10 2016 219 343 A1 a method is known in which the internal combustion engine is operated as a function of an engine speed and an engine load and comprises at least two cylinders, each with a first and a second exhaust valve. In a full load mode, all exhaust valves of all cylinders are activated, while in a part load mode only the first exhaust valves and not the second exhaust valves of all cylinders are activated.

In modern, supercharged internal combustion engines with more than three cylinders, exhaust manifolds with separate ignition sequences are normally used, which are connected to a multi-flow (twin flow or segment) turbine of an exhaust gas turbocharger and/or to several exhaust gas turbochargers. This avoids the conflict of objectives between long exhaust valve timing for good gas exchange at high power on the one hand and avoiding the pushing back of residual gas from the cylinder that is fired next at low power on the other hand, which can lead to power loss and combustion instabilities. In the case of a flow separation, long exhaust control times also bring gas exchange and thus fuel consumption advantages in the partial load.

In return, however, disadvantages in the build-up of back pressure at high power levels, in the thermodynamics of the turbine, and in terms of complexity and the costs of the associated drive arrangement are accepted.

The DE 196 51 148 A1 relates to a method for operating a multi-cylinder internal combustion engine, preferably an Otto engine, with two intake and two exhaust valves per cylinder, a turbocharger and a downstream exhaust gas purification system with a catalytic converter.

The DE 10 2013 009 227 A1 relates to a method for controlling the valves of a reciprocating internal combustion engine with a plurality of valves, each of which can be switched on and off as desired and independently of the others, with defined combinations of valves being switched on and off in every driving state achieving operation in the optimum efficiency range of the internal combustion engine shall be.

Proceeding from this, it is an object of the invention to achieve a further improvement in the operation of the internal combustion engines and drive systems mentioned at the outset.

This object is achieved by a drive assembly having the features of claim 1 and a motor vehicle having the features of claim 12.

According to one embodiment, a method for operating an internal combustion engine of a drive arrangement depending on a load mode is provided. The internal combustion engine has at least two cylinders, each with a first and a second exhaust valve.

1. a) Aktivieren aller Auslassventile der Zylinder in einem Hochlastmodus, und
2. b) Aktivieren des ersten Auslassventils und Deaktivieren des zweiten Auslassventils eines, mehrerer oder aller Zylinder in einem Teillastmodus.

The method comprises at least the following steps:

1. a) activating all exhaust valves of the cylinders in a high load mode, and
2. b) activating the first exhaust valve and deactivating the second exhaust valve of one, several or all cylinders in a partial load mode.

A high-load mode is to be understood in particular as an operating mode of the internal combustion engine that is activated when the internal combustion engine is operated under full load or in a higher part-load range. A partial load mode is to be understood in particular as an operating mode of the internal combustion engine which is activated when the internal combustion engine is operated in a lower partial load range or under low load, no load or possibly in overrun mode.

In both, in particular all, load modes, the first exhaust valves are operated with a first exhaust control time that is shorter than a second exhaust control time with which the second exhaust valves are operated. In particular, the different exhaust control times and thus in particular also different valve lift profiles are achieved by different forms of the cams on a camshaft.

As a result, an exhaust gas turbocharger with a mono-scroll turbine can also be used in engines with more than one cylinder group. Because of the shorter exhaust control time of the first exhaust valves - which are operated in part-load mode without opening the second exhaust valves - there is no undesired crosstalk of the exhaust gas in partial-load operation into the subsequently igniting cylinder, even without a complete flow separation up to the turbine of the exhaust gas turbocharger. Likewise, a larger exhaust gas impulse on the turbine of an exhaust gas turbocharger and thus a good low-load torque ("low end torque") can be achieved. In high-load operation, on the other hand, the good efficiency of a mono-scroll turbine combined with a high performance potential can be exploited.

The drive arrangement has an internal combustion engine. The internal combustion engine has at least four, in particular five or six or eight, cylinders, with in particular two cylinders of the internal combustion engine being assigned to a cylinder group. Each cylinder has a first and at least one second exhaust valve.

According to one embodiment, the internal combustion engine is a four-cylinder with two cylinder groups or a six-cylinder with three cylinder groups. The cylinder groups are assigned in particular in such a way that cylinders that fire in a temporally adjacent manner are not in one group.

In addition, the internal combustion engine has a control unit that differs from known control units at least in that it is set up to operate the internal combustion engine with a method according to one embodiment of the invention.

According to one aspect of the invention, a drive arrangement is provided, comprising an internal combustion engine according to an embodiment of the invention, which has an exhaust manifold for discharging the exhaust gases, and an exhaust gas turbocharger with a mono-scroll turbine, which is connected via the exhaust manifold for exhaust gas routing to the first and second Exhaust valves of the internal combustion engine is connected. A mono-scroll turbine typically has better efficiency and higher thermo-mechanical strength than a twin scroll or segment turbine for the same size. In addition, it is simpler in construction and therefore cheaper.

According to a further aspect, a motor vehicle is provided with a drive arrangement according to an embodiment of the invention.

The invention is based, among other things, on the consideration that turbocharged four-cylinders with the previously known operating strategies to achieve low fuel consumption and environmentally friendly emission values require a flow-separated turbine of the exhaust gas turbocharger and thus also a flow-separated exhaust manifold. By sending the exhaust gases of adjacent firing cylinders over long distances in this way, crosstalk of the exhaust gases into the next firing cylinder can be avoided and a long exhaust timing for good gas exchange can still be maintained.

The invention is now based, among other things, on the idea of resolving the conflict of objectives between a long exhaust control time for a good gas exchange on the one hand and avoiding crosstalk of exhaust gases into the next firing cylinder on the other in a different way.

This is described below using a four-cylinder in-line engine as an example. According to the invention - especially below a switching point to be determined - in a partial load mode via a valve deactivation of one of the exhaust valves of a cylinder - for example by means of suitably controlled exhaust rocker arms - the valve is deactivated with a long exhaust control time for a good gas exchange. The exhaust rocker arms can be shifted, for example, by means of a shift shaft or another suitable device known per se.

The exhaust gas only flows out via the valve with a short opening duration, which prevents residual gas from flowing back. In a high-load mode - i.e. in particular above the switching point - all valves are activated and the advantages of the long opening duration in connection with the good efficiency and throughput behavior of a mono-scroll turbine are used. Depending on the operating point in the map and the driver's wishes, the point at which to switch between four- and eight-valve operation is determined according to criteria for maximizing torque or minimizing fuel consumption. In particular, several engine parameters are included in the decision, individually and/or weighted or combined in a weighted or unweighted manner, which are listed in the next paragraph.

According to one embodiment, a switching point with regard to the load mode is determined as a function of one or more engine parameters and/or boundary conditions from the operation and/or the environment of the engine, in particular as a function of an existing engine torque and/or a load request and/or a speed and /or a residual gas content and/or a boost pressure requirement and/or a back pressure and/or a center of combustion and/or a wastegate position and/or a lift of the intake valves and/or a spreading of the intake and exhaust camshafts and/or a rate an external EGR and/or a position of a variable turbine nozzle. According to one embodiment, at least one existing engine torque and one speed are taken into account as engine parameters for determining the load mode. Depending on the operating point in the map and the driver's request, the switchover can take place according to criteria for maximizing torque or minimizing consumption.

The internal combustion engine can thus be operated efficiently in terms of fuel consumption and emissions, since it can be operated in part-load mode if required, without having the disadvantages of the known solutions mentioned.

In the present case, deactivation means in particular that the exhaust valve is closed independently of a camshaft rotational position. In the present case, activating means in particular that the exhaust valve can be opened and closed depending on a rotational position of a camshaft. The engine speed is in particular an actual engine speed, and the engine load is in particular an actual engine load.

According to one embodiment, the first exhaust valves are operated, in particular during the first exhaust control time, with a first valve lift curve that differs from a second valve lift curve, with which the second exhaust valves are operated, in particular during the second exhaust control time, with regard to a lift maximum and/or a lift gradient differs when opening and/or when closing.

As a result, for example, the slightly stronger throttling can be compensated for by the shorter first exhaust control time at partial load. It is also possible to compensate for the slightly weaker back pressure reduction than with eight "long" exhaust valve timings (for four-cylinder engines).

According to one embodiment, the first and second exhaust valves are each assigned a suitable switching device, such as a rocker arm and/or a sliding cam or a fully variable valve train, with the drag device of the second exhaust valves being designed as an outlet switching rocker arm or as a sliding cam arrangement or with a fully variable valve train, so that in particular the second outlet valves can be activated and deactivated by activating and deactivating the respectively associated switching device.

According to one embodiment, the first outlet valves cannot be activated and deactivated by activating and deactivating the respectively associated switching device. This allows the first switching devices to be designed in a simple, smaller and cheaper manner.

According to an alternative embodiment, the first exhaust valves can be activated and deactivated by activating and deactivating the respectively associated switching device—similar to the second exhaust valves, in particular by the switching devices of the first exhaust valves being designed as exhaust rocker arms. This enables consumption- and emission-optimized engine towing.

According to one embodiment, the switching device can actuate the exhaust valve in an activated state in cooperation with a camshaft, and does not actuate the exhaust valve in a deactivated state, regardless of a position of the camshaft.

According to one embodiment, the internal combustion engine has an adjustment device, for example an adjustment shaft, which is set up to activate all exhaust valves of all cylinders in a high-load mode and to activate the first exhaust valve of the cylinders of one, several or all cylinder groups and the second in a part-load mode to deactivate the exhaust valve of the cylinders of these cylinder groups. This supports operation with one or more deactivated cylinder groups. This operating mode is also provided in a “toggle” mode with alternately deactivated cylinder groups.

According to one embodiment, the mono-scroll turbine has an adjustable guide wheel, ie it is designed in particular as a VTG turbine. By adjusting the angle of attack of the turbine blades of the guide wheel, the momentum transfer from the exhaust gas to the turbine can be optimized and the response of the turbine can thus be improved.

According to one embodiment, the exhaust manifold is a split flow exhaust manifold. That means in particular that the exhaust gas flows of all cylinders are brought together at least essentially only at a connection point of the exhaust manifold to the exhaust gas turbocharger. Due to the relatively late merging of the flows, the impulse transmission to the turbine blades can be improved.

In particular, with regard to an exhaust gas flow in the exhaust manifold, the exhaust gas flows of a first cylinder group (with cylinders that do not fire immediately one after the other with regard to a cylinder sequence) are first combined to form a first group flow and the exhaust gas flows of a second cylinder group to form a second group flow. The two group flows are then brought together, in particular at a distance from the starting points of the respective group flow. In addition to the improved impulse transmission, such a design of the exhaust manifold also counteracts the tendency of the system to crosstalk.

• 1 zeigt schematisch eine Antriebsanordnung nach einer beispielhaften Ausführung der Erfindung in einem Teillastmodus.
• 2 zeigt schematisch die Antriebsanordnung nach 1 in einem Hochlastmodus.
• 3 zeigt schematisch einen schaltbaren Schlepphebel eines zweiten Auslassventils in seiner Einbauumgebung eines der Zylinder im Verbrennungsmotor der Antriebsanordnung nach 1.
• 4 zeigt zur Verdeutlichung eines Verfahrens nach einer beispielhaften Ausführung der Erfindung ein Diagramm, in welchem der Hubverlauf der Auslassventile des Verbrennungsmotors der Antriebsanordnung nach 1 über den Kurbelwinkel dargestellt ist.
• 5 zeigt zur Verdeutlichung des Verfahrens ein Diagramm, in welchem die Zuteilung der verschiedenen Lastmodi in Abhängigkeit von einer Motordrehzahl und einem Motormoment dargestellt ist.

Further advantages and application possibilities of the invention result from the following description in connection with the figures.

• 1 shows schematically a drive arrangement according to an exemplary embodiment of the invention in a partial load mode.
• 2 shows the drive arrangement schematically 1 in a high load mode.
• 3 shows schematically a switchable rocker arm of a second exhaust valve in its installation environment of one of the cylinders in the internal combustion engine of the drive arrangement 1 .
• 4 shows a diagram to illustrate a method according to an exemplary embodiment of the invention, in which the stroke profile of the exhaust valves of the internal combustion engine of the drive arrangement 1 is shown over the crank angle.
• 5 shows a diagram to clarify the method, in which the allocation of the various load modes is shown as a function of an engine speed and an engine torque.

The 1 and 2 show a drive arrangement 8 with an internal combustion engine 10 designed as a four-cylinder engine, which has four cylinders 1, 2, 3 and 4. Each of cylinders 1-4 includes a first exhaust valve R and a second exhaust valve L.

In addition, the drive arrangement 8 has an exhaust gas turbocharger 12 with a mono-scroll turbine 18 (ie with a single inlet on the turbine inlet housing 16 on the turbine 18 of the exhaust gas turbocharger 12). The first exhaust valves R and the second exhaust valves R are flow-connectable to the turbine inlet housing 16 via an exhaust manifold 20 . A wastegate 22 for bypassing the turbine 18 branches off between the exhaust manifold 20 and the turbine inlet housing 16 of the turbine 18 .

Downstream of the turbine 18 there is an exhaust aftertreatment system with a close-coupled catalytic converter 24 and an underfloor catalytic converter 25 .

A compressor 26 of the exhaust gas turbocharger 12 compresses ambient air, which is derived from an intake silencer 27, and supplies it via an intercooler 28 and a throttle valve 29 to the cylinders 1-4.

Exhaust manifold 20 is designed as an exhaust gas manifold with separate flows, with the exhaust gas flows of a first cylinder group (cylinders 2 and 3) leading to a first group flow 5 and the exhaust gas flows of a second cylinder group (cylinders 1 and 4) leading to a second group flow 6 with regard to an exhaust gas flow in exhaust manifold 20 are brought together, and then spaced from the starting points of the respective group flow 5 or 6, the two group flows are brought together.

In a similar exemplary embodiment, the two cylinder flows of one of the group flows can also be fed individually to another group flow that has already been combined, or all the individual cylinder flows can be brought together at a junction point. Ultimately, it is relevant that the individual flows or the group flows are only brought together as close as possible to the turbine inlet housing 16 of the turbine 18 of the exhaust gas turbocharger 12, in particular only immediately before a branch to a waste gate 22.

The first exhaust valves R and the second exhaust valves L are operated by means of a valve train 30 (cf 3 ), which has a not-shown first switching device (embodied, for example, as a rocker arm) for the first exhaust valves R and switching device 32, embodied, for example, as an exhaust rocker arm, for the second exhaust valves L.

Depending on a load mode, either all exhaust valves R, L of cylinders 1-4 are activated in a high-load mode 200, or the first exhaust valves R are activated in a part-load mode 100 and the second exhaust valves L are deactivated.

The partial load mode 100 is in 1 shown. The second exhaust valves L filled in black symbolize that they are not actuated in part-load mode 100 independently of the rotation of a camshaft 36 (ie a valve lift of the second exhaust valves L is constantly zero in part-load mode 100).

High load mode 200 is in 2 shown. The second outlet valves L filled in white symbolize that these contours of the camshaft 36 constructed accordingly in the high-load mode 200 are actuated.

To switch between the load modes 100 and 200, a switchable second rocker arm 32 works on a valve stem 34 in the valve train 30. The valve stem 34 is shown as representative of each of the second outlet valves L.

In an activated state, the rocker arm 32 is actuated by a camshaft 36 . The rocker arm 32 then moves the valve stem 34 in such a way that the associated second outlet valve L is opened and closed. In a deactivated state, the rocker arm 32 does not actuate the valve stem 34 regardless of a rotational position of the camshaft 36 .

The rocker arm 32 is switched between its activated state and its deactivated state by an adjusting device 38 designed as an adjusting shaft in the exemplary embodiment. For this purpose, the adjusting device 38 comprises a switching contour 40, which is designed as a switching cam in the present exemplary embodiment.

The adjustment shaft 38 extends essentially over the entire width of the cylinders 1-4 of the internal combustion engine 10.

A number of switching contours 40 corresponding to the number of outlet valves L and R are formed on the adjusting device 38 . In the case of the internal combustion engine 10 there are eight switching contours 40 on the adjustment device 38 .

In the exemplary embodiment, the adjusting device 38 is designed in such a way that a rotational position of the adjusting device 38 corresponds to each of the described load modes 100, 200 of the internal combustion engine 10.

In order to carry out the invention, it is not absolutely necessary for the first towing devices (not shown) for the first outlet valves R not to be switchable. However, these shift levers can be designed analogously to the second shift lever 32 if operating cases with a complete engine shutdown, for example during overrun operation, are to be provided for the internal combustion engine.

In the present exemplary embodiment, the first exhaust valves R are operated with a first exhaust control time T1, which is shorter than a second exhaust control time T2, with which the second exhaust valves L are operated. The first exhaust control time T1 is based on a crank angle KW, regardless of whether the drive arrangement 8 is operated in the part-load mode 100 or in the high-load mode 200 . In high-load mode 200, second exhaust control time T2 is constant in relation to crank angle KW. In part load mode 100, the second exhaust timing is zero because the second exhaust valves L are not raised.

In the chart 400 of the 4 a stroke H of the exhaust valves R and L is entered via the crank angle KW of the camshaft 36 . A first stroke curve H1 of the first exhaust valves R and a second stroke curve H2 of the second exhaust valves L are shown for the high-load mode 200 .

Due to the shorter first exhaust control time T1, crosstalk of exhaust gas from the previously fired cylinder into the cylinder with the currently open first exhaust valve R can be avoided in the part-load mode 100.

In the high-load mode 200, on the other hand, a good gas exchange can be ensured by the longer second exhaust control time T2.

In the exemplary embodiment shown (continuous lines), both outlet valves R and L are operated with the same maximum lift Hmax.

In another exemplary embodiment, however, it would also be conceivable for the first exhaust valves R to be operated with a lift curve H1′ with a larger maximum lift Hmax′, in particular to compensate for a (possibly even) shorter first exhaust control time T1′ during gas exchange. This would then also be associated with a steeper lift gradient. This variant is shown in diagram 400 with a dashed line.

In the chart 500 of the 5 is shown in simplified form as a switching point (in the form of a switching line S here) with regard to load mode 100 or 200 as a function of a number of engine parameters M and/or n and/or RG and/or LB and/or GD and/or SV and/or SW and/or HE and/or SN and/or RA and/or PT is determined by the control unit 11. This list of motor parameters is an example of the version shown. In other versions, other engine parameters can be used in whole or in part.

Diagram 500 shows an engine characteristics map in which engine torque M is plotted against engine speed n. Below a line of maximum engine torque (limit torque 501), the engine torque-speed field is divided by the switching line S into a range in which internal combustion engine 10 is operated in part-load mode 100 and a range in which internal combustion engine 10 is operated in high-load mode 200.

This two-dimensional representation is used, among other things, to simply convey the principle of switching between the two load modes 100 and 200 at the shifting line S. The shifting line S is calculated by the control unit 11 as a function of the plotted engine parameters M and n, among other things. In the exemplary embodiment, various other engine parameters are included in the calculation of the switching point S, such as a residual gas content (RG) and/or a boost pressure requirement (LB) and/or a back pressure (GD) and/or a center of combustion (SV) and/or or a wastegate position (SW) and/or a lift of the intake valves (HE) and/or a spread of the intake and exhaust camshafts (SN) and/or a rate of external EGR (RA) and/or a position (PT) a variable turbine guide wheel. Other engine parameters or boundary conditions that have not been mentioned before can also be included in the calculation of the switching point. In different exemplary embodiments, different, in particular more or fewer, parameters can be taken into account. Depending on the operating point in the map and the driver's wishes, switching between the load modes takes place according to criteria for maximizing torque or minimizing consumption.

By using different exhaust control times T1 and T2 in the high-load mode 200 and by switching off the longer open second exhaust valves L in the partial-load mode 100, an exhaust gas turbocharger with a mono-scroll turbine 18 can also be used in engines with more than one cylinder group 5, 6. A mono-scroll turbine typically has better efficiency, higher thermo-mechanical strength and lower costs than a twin scroll or segment turbine of the same size.

1. 1) Ermitteln von Ausprägungen derjenigen Motorkenngrößen 501, 502, die für die Bestimmung des Lastmodus herangezogen werden; 2) Bestimmung des zu verwendenden Lastmodus (also entweder Teillastmodus 100 oder Hochlastmodus 200) in Abhängigkeit von den ermittelten Ausprägungen der herangezogenen Motorkenngrößen; 3) Ansteuern der Verstellwelle 38 zum Aktivieren oder Deaktivieren der zweiten Auslassventile L in Abhängigkeit von dem bestimmten Lastmodus. Falls die Turbine 18 des Abgasturboladers 12 mit einem variablen Leitrad ausgebildet ist, kann die Steuereinheit 11 zudem dazu eingerichtet sein, eine Winkelstellung der Schaufeln des Leitrads unter anderem in Abhängigkeit von dem bestimmten Lastmodus 100 oder 200 zu verstellen.

A control unit 11 of the internal combustion engine 10 is in particular also designed as a control unit of the drive arrangement 8 . It can also be embodied as an interactive or separately working part of a higher-level engine control of internal combustion engine 10 . For the purposes of the drive arrangement 8 described in the exemplary embodiments, the control unit is set up in particular for the following tasks:

1. 1) determining characteristics of those motor parameters 501, 502 that are used to determine the load mode; 2) Determination of the load mode to be used (i.e. either part-load mode 100 or high-load mode 200) as a function of the determined characteristics of the engine parameters used; 3) Controlling the adjustment shaft 38 to activate or deactivate the second exhaust valves L depending on the specific load mode. If the turbine 18 of the exhaust gas turbocharger 12 is designed with a variable guide wheel, the control unit 11 can also be set up to adjust an angular position of the blades of the guide wheel depending on the specific load mode 100 or 200, among other things.

Reference List

1-4

cylinder

5

first group flood

6

second group flood

8th

drive assembly

10

combustion engine

11

control unit

12

exhaust gas turbocharger

16

turbine inlet casing

18

Mono scroll turbine

20

exhaust manifold

22

wastegate

24

close-coupled catalytic converter

25

underbody catalyst

26

compressor

27

intake silencer

28

intercooler

29

throttle

30

valve train

32

Switching device (e.g. switchable, second rocker arm)

34

valve stem

36

camshaft

38

Adjusting device (e.g. adjusting shaft)

40

switching contour

100

partial load mode

200

high load mode

400

Stroke curve crank angle diagram

500

Engine torque engine speed diagram

501

Limit engine torque over the speed

R

first exhaust valves

T1

first, shorter exhaust timing

H1

first stroke

L

second exhaust valves

T2

second, shorter exhaust valve timing

H2

second stroke course

Hmax

maximum valve lift

week

crank angle

M

engine torque

n

engine speed

S

Switching point, especially switching line

RG

residual gas content

LB

boost demand

DG

back pressure

SV

center of combustion

SW

wastegate position

HE

intake valve lift

SN

Spreading of the intake and exhaust camshafts

RA

Rate of an external EGR

pt

Position of a variable turbine nozzle

Claims (12)

Drive arrangement (8), having - an internal combustion engine (10) with at least four cylinders (1, 2, 3, 4), each having a first (R) and at least one second (L) exhaust valve, and with an exhaust manifold (20) for discharging the exhaust gases, - an exhaust gas turbocharger (12) with a mono-scroll turbine (18), which is connected to the first (R) and second (L) exhaust valves of the internal combustion engine via the exhaust manifold for exhaust gas routing, - a control unit (11 ), which is set up to a) activate all exhaust valves (R, L) of the cylinders in a high-load mode (200), and b) in a partial-load mode (200) for one, several or all cylinders (1, 2, 3, 4) to activate the first exhaust valve (R) and to deactivate the second exhaust valve (L), characterized in that the first exhaust valves (R) are operated with a first exhaust timing (T1) that is shorter than a second exhaust timing (T2) , with which the second exhaust valves (L) are operated. Drive arrangement according to claim 1 , characterized in that the control unit is set up to operate the first exhaust valves (R) with a first valve lift curve (H1) which differs from a second valve lift curve (H2) with which the second exhaust valves (L) are operated with respect to a Lift maximum and / or a lift gradient differs when NEN and / or when closing. Drive arrangement according to one of the preceding claims, characterized in that the control unit is set up to determine a switching point (S) with regard to the load mode as a function of one or more engine parameters (M, n). Drive arrangement according to claim 3 , characterized in that the control unit is set up to take into account at least one engine torque (M) present and one engine speed (n) present as engine parameters (M, n) for determining the load mode. Drive arrangement according to one of the preceding claims, characterized in that the first and second exhaust valves are each assigned a switching device, the switching device of the second exhaust valves (L) being designed as a switchable rocker arm (32) or as a sliding cam arrangement or with a fully variable valve train. Drive arrangement according to claim 5 , characterized in that the first outlet valves (R) can be activated and deactivated by activating and deactivating the respectively associated switching device. Drive arrangement according to claim 5 or 6 , characterized in that the switching device (32) can actuate the outlet valve (R, L) in an activated state in cooperation with a camshaft (36), and in a deactivated state the outlet valve is not actuated independently of a position of the camshaft. Drive arrangement according to one of Claims 5 until 7 , Characterized by an adjusting device (38) which is adapted in one High-load mode (200) to activate all exhaust valves (R, L) of all cylinders (1, 2, 3, 4), and in a part-load mode (200) to activate the first exhaust valve (R) of the cylinders of one, several or all cylinder groups and that to deactivate the second exhaust valve (L) of the cylinders of these cylinder groups. Drive arrangement according to one of the preceding claims, characterized in that the mono-scroll turbine (18) has an adjustable guide wheel. Drive arrangement according to one of the preceding claims, characterized in that the exhaust manifold (20) is a partial flow separated exhaust manifold. Drive arrangement according to claim 10 , characterized in that first the exhaust gas flows of a first cylinder group are merged into a first group flow 5 and the exhaust gas flows of a second cylinder group into a second group flow 6, and then the two group flows 5, 6 are merged. Motor vehicle, characterized by a drive arrangement (8) according to one of the preceding claims.

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