DE102011115206A1 - Exhaust gas turbocharger for internal combustion engine, has two valves that are formed such that respective opening states of valves are set differently depending on the state of engine for optimized adjustment of operating parameters - Google Patents

Abstract

The turbocharger (4) has an exhaust gas turbine (16) connected to the exhaust gas lines (12,14) of engine (2) and having exhaust gas flows (18,20). A valve (32) is arranged for variable adjustment of the exhaust gas flow (20) between closed and open positions, and a valve (34) is arranged for variable adjustment of both exhaust gas flows to be supplied to the exhaust gas turbine. For optimized adjustment of operating parameters, the valves are formed such that the respective opening states of valves are set differently depending on the state of the engine.

Description

The invention relates to an exhaust gas turbocharger for an internal combustion engine having two exhaust gas flows and valve devices for variable adjustment of the exhaust gas flow to be supplied to the exhaust gas stream.

In the prior art, it is known to provide internal combustion engines with exhaust gas turbochargers for increasing the specific power and the efficiency.

From the publication DE 198 57 234 C2 For example, an exhaust gas turbocharger for an internal combustion engine is known, the exhaust gas turbine comprises a double-flow spiral channel, each exhaust gas flow communicates in the spiral channel, each with an exhaust pipe, is fed via the exhaust gas from each cylinder bank of the internal combustion engine. One of the two exhaust gas lines is connected to an exhaust gas recirculation line for returning exhaust gas into the intake tract, wherein the recirculated exhaust gas mass flow is to be adjusted via a valve device. In addition, a bypass bypassing the exhaust gas turbine is provided, which is to be opened via a bypass valve, which is connected to both exhaust gas lines.

A double-flow gas turbine of an exhaust gas turbocharger is also from the DE 198 36 677 A1 known. According to this publication, a rotary valve is placed on a turbine housing, which lies in the flow path of a bypass to the exhaust gas turbine and has a hollow cylindrical rotary body with two outflow openings for each exhaust gas flow. The outflow openings are introduced as grooves in the wall of the rotary body, which extend in the circumferential direction of the rotary body and are arranged parallel to each other and both have the same length. During a rotation of the rotary body, the outflow openings come simultaneously in the opening and in the blocking position, so that both exhaust gas flows are discharged uniformly via the bypass.

Furthermore, from the DE 101 32 672 A1 an exhaust gas turbocharger, in which a turbine volute in the exhaust gas turbine includes two exhaust gas passages communicating with a respective exhaust pipe of the exhaust line, wherein an adjustable between a blocking position and an open position valve means for variable adjustment of the exhaust gas to be supplied exhaust gas mass flow is provided, wherein the valve housing of the valve device forms a common component with the turbine housing of the exhaust gas turbine. The valve device may comprise a valve which regulates the amount of recirculated exhaust gas and another valve which is arranged in the branch of a bypass from the second exhaust line for bypassing the exhaust gas turbine. Both valves can be adjusted via an actuator between a blocking position and an open position, wherein the adjusting movement of the two actuators coupled or alternatively can be formed independently operable.

In the known dual-flow turbochargers, it is customary to provide a flood for exhaust gas recirculation and another flood for the discharge of the exhaust gas via an exhaust. With the help of the exhaust gas recirculation can be a performance and consumption optimization achieve and good emission values.

With the requirement of higher exhaust gas recirculation rates at low speeds, the provision of a bypass control valve in the exhaust gas recirculation branch may be expedient, since otherwise high pressure prevails in front of the turbine at high speeds, which leads to increased charge exchange losses.

In the prior art is described to actuate the valve means for the exhaust gas recirculation flow and for the Auspuffflut always at the same time. However, it has been shown that with the existing systems, the boost pressure in the rated power range can not be sufficiently adjusted with all turbine designs, since the exhaust gas bypassing the turbine via the valve directly depends on the exhaust gas recirculation. The system is set to specific parameters here. It has also been shown that instabilities in emissions control can occur with existing systems.

The object of the invention is therefore to at least partially overcome the disadvantages known from the prior art and to provide an exhaust gas turbocharger which can be better adjusted than the known exhaust gas turbocharger and combines a better response with lower tolerances in the emission control.

The object is achieved by an exhaust gas turbocharger according to claim 1. Further developments of the invention are the subject of the dependent claims.

An inventive exhaust gas turbocharger for an internal combustion engine has an exhaust gas turbine, which can be driven by the exhaust gas of the internal combustion engine. The exhaust gas turbine is provided for arrangement in an exhaust line of the internal combustion engine and drives a compressor, which can be arranged in an intake tract of the internal combustion engine. For this purpose, exhaust gas turbine and compressors are coupled to each other in a force-transmitting manner, which can be accomplished via a common shaft.

The exhaust gas turbine has a turbine volute with two exhaust gas flows, which are provided for fluid communication with one exhaust pipe of the exhaust line of the internal combustion engine, wherein each provided for each exhaust gas flow between a closed position and an open position adjustable valve device for variable adjustment of the exhaust gas flows supplied exhaust gas stream.

With the help of the valve devices, the amount of exhaust gas that can be supplied to the exhaust gas turbine via the respective floods can be set. If an overpressure is present in the exhaust gas flows in front of the turbine wheel, the overpressure can be reduced by means of the valve devices. Such overpressure can arise, for example, in overrun when the fresh air supply is throttled, for example by means of throttle valves, but the engine continues to run and increases the pressure on the exhaust side of the engine. Such valve devices are also commonly referred to as "wastegate" in the jargon, because over them an overpressure in front of the turbine wheel can be derived unused.

According to the invention, it is provided that the valve devices are designed such that the respective opening states of the valve devices can be set differently depending on the state of the internal combustion engine. In this way, it becomes possible to adjust the exhaust gas pressures in the two floods as required, depending on the respective requirements, whereby the adjustable engine map is considerably increased. An internal combustion engine equipped with an exhaust gas turbocharger according to the invention can thus have improved exhaust gas values and higher efficiency in the different load states. Thus, the exhaust gas turbocharger according to the invention may be designed so that in a Abgasrückführungszweig a desired high exhaust gas pressure is applied, whereas the valve means of the other flood is already open to reduce the exhaust gas pressure on the exhaust gas turbine and the associated charge pressure.

According to a first possible embodiment of the invention can be provided that the two exhaust gas flows have different clear cross-sections. Thus, the respective exhaust gas flow can be adjusted to the different exhaust gas recirculation quantities and the boost pressure, and charge exchange losses can be reduced.

According to another possible embodiment of the invention can be provided that an exhaust gas flow is formed for connection to an exhaust gas recirculation train of the internal combustion engine and the other exhaust gas flow for connection to an exhaust line of the internal combustion engine. If the exhaust gas flows have different cross sections, it may be provided that the exhaust gas flow for connection to the exhaust gas recirculation train has a smaller cross section than the exhaust gas flow for connection to an exhaust line of the internal combustion engine.

According to a further possible embodiment of the invention, the exhaust gas recirculation line associated with the valve device may be designed such that it opens at a different time than the exhaust line associated with the valve device. In particular, this may be a later point in time, so that the valve device provided in the exhaust gas line is already open, while the valve device arranged in the exhaust gas recirculation line is still closed. In this way, the pressure in the exhaust gas recirculation can be kept sufficiently high at low speeds to meet the requirements for efficient and ecological engine operation.

The two valve devices can be arranged in a common housing, which reduces the space required for the exhaust gas turbocharger according to the invention.

According to another possible embodiment of the invention it can be provided that the two valve devices have actuators operable independently of one another. In this way it is possible to control the valve devices completely individually and to set optimal conditions in the two exhaust gas lines and on the exhaust gas turbine.

Alternatively it can be provided that the valve devices have a common actuator. Although this reduces the variability of the system, but leads to a cost reduction, since only one actuator instead of two actuators for operating the exhaust gas turbocharger according to the invention is required. Even with systems according to the invention with only one actuator, improvements in performance, efficiency and exhaust gas behavior can be achieved.

One way to construct the exhaust gas turbocharger according to the invention with a common actuator is to rigidly connect one of the valve means with the actuator, whereas the other valve means is connected by means of a spring element with the actuator. The other valve device is only opened when the prestressed spring force is overcome, so that with the help of this system, an adjustment of the opening times of the first valve device and the second valve device can be achieved. Different spring systems or elastic system can be used for this purpose.

An alternative possibility of constructing a valve device with an actuator is to actuate the valve device by means of a common rotary valve, which has an opening bore for each valve device, wherein the opening bores have an angular offset. When the opening bores partially or completely overlap a valve seat of the valve means, the valve means is opened. Depending on the set angle of rotation, one valve device can thus be opened or partially opened, or depending on how the opening bores are arranged and / or dimensioned, the other valve device or both valve devices.

A further alternative possibility is that the valve devices have a common, axially actuated spool valve, which holds the valve devices closed or open. In this way, one valve can already be opened while the other valve is still closed.

A further alternative embodiment can provide that the valve devices each have a rotatably mounted disc with at least one opening, wherein the openings are angularly offset from each other or angularly offset from one another are adjustable. An adjustment of the angular offset can be achieved by means of an actuator and a gear that connects the discs together. In this case, an embodiment with an actuator can be realized, otherwise two actuators are needed.

As actuators may be provided, inter alia, electrical actuators, but also under or overpressure systems, which in turn can be operated actively or passively. For passive pressure systems, for example, exhaust gas pressure or boost pressure may be used to actuate the valve devices.

The invention will be explained with reference to several embodiments. Here are shown schematically:

1 a schematic diagram of an internal combustion engine with an exhaust gas turbocharger according to the invention;

2 a first alternative embodiment for actuating the two valve devices by means of two separate actuators;

3 an embodiment for actuating the two valve means by means of a common actuator and a spring system;

4 an embodiment for actuating the valve means by means of a rotary valve;

5 an embodiment for actuating the valve means by means of a piston valve;

6a . 6b an embodiment for actuating the valve means by means of rotatably mounted discs and

7 schematic operating characteristics for operation of the exhaust gas turbocharger according to the invention.

In the different embodiments, identical or equivalent components are provided with the same reference numerals for the sake of clarity.

1 shows a schematic representation of an internal combustion engine 2 , with an exhaust gas turbocharger according to the invention 4 (Components dashed framed) is equipped.

The internal combustion engine 2 has six cylinders 6 on that from an entry side 8th be supplied with fresh air, or at exhaust gas recirculation with fresh air and cooled exhaust gas, and those on an exhaust gas side 10 the exhaust gases are removed. The exhaust side 10 has two exhaust lines, a first exhaust line 12 and a second exhaust line 14 on.

The erfindungemäße exhaust gas turbocharger 4 has an exhaust gas turbine, not shown, and a compressor, not shown. The exhaust gas turbine, not shown, has a turbine wheel in an exhaust gas turbine housing not shown in detail 16 on, that of two formed in the exhaust gas turbine housing not shown floods, a first flood 18 and a second flood 20 , is flown by exhaust air. The first flood 18 is with the first exhaust system 12 fluidly connected, the second tide 20 with the second exhaust system 14 , The first flood 18 may be smaller than the second tide in some embodiments 20 to the ratio of the usual amounts of exhaust gas in the first exhaust line 12 opposite the second exhaust line 14 To take into account and a good flow velocity of the turbine wheel 16 to reach in both floods.

The turbine wheel 16 is by means of a wave 22 with a compressor wheel 24 connected to the compressor, not shown, in a fresh air branch of the internal combustion engine 2 is arranged. The air compressed by the compressor becomes a charge air cooler 26 which reduces the temperature of the compressed air and increases the density of oxygen in the compressed air.

The first exhaust system 12 has an exhaust gas recirculation, with the help of which exhaust gas in the input side 8th is returned. With the help of a control valve 28 For example, the exhaust gas amount that is recirculated is adjusted depending on the engine conditions. The recirculated exhaust gas is in an exhaust gas cooler 30 cooled down before it reaches the cylinders 6 on the input side 8th is forwarded.

The floods each have valves, the first flood 18 a first valve 32 and the second flood 20 a second valve 34 , with the help of which exhaust gas from the first exhaust line 12 and the second exhaust line 14 in an exhaust pipe 36 are conductive. The first valve 32 and the second valve 34 thus enable the pressure on the turbine wheel 16 to adjust. If the pressure is too high, the first valve can 32 and the second valve 34 partially or completely open and the exhaust gas is at the turbine wheel 16 over in the one exhaust line 36 directed. Possible embodiments of the valve system with the two valves are in the following 2 to 6 shown.

2 shows a possible embodiment of a valve system of the exhaust gas turbocharger according to the invention.

The first valve 32 and the second valve 34 each have valve disc, the first valve a first valve disc 38 and the second valve has a second valve disk 40 , on, by means of independent actuators, a first actuator 42 and a second actuator 44 , are operable and the first valve 32 and the second valve 34 open and close. In the illustrated embodiment, the first valve disc 38 and the second valve plate 40 operated by a linkage, however, other embodiments are also conceivable.

Dashed a possible valve constellation is shown, in which the the exhaust line 14 associated second valve 34 already open, whereas that the exhaust gas recirculation train 12 associated first valve 32 is still closed.

The first actuator 42 and the second actuator 44 be from a control unit 46 , For example, the engine control, operated.

3 shows an alternative embodiment using poppet valves with a single actuator 48 ,

The second valve disk 40 of the second valve 34 is by means of a non-flexible linkage to the single actuator 48 arranged so that every movement of the single actuator 48 a movement of the second valve disc 40 and thus opening and closing of the second valve 34 entails.

The first valve plate 38 of the first valve 32 is by means of a linkage and an additional spring 50 on the single actuator 48 arranged, so first the preloaded spring 50 is pressed before the first valve plate 38 is also operated. The first valve plate 38 opens later than the second valve disc in the embodiment shown 40 , The second valve disk 40 is directly with the single actuator 48 connected.

4 shows a further alternative embodiment of the valve system of an exhaust gas turbocharger according to the invention, in which a rotary valve 52 is provided, which is rotatable in a channel 54 is arranged.

The rotary valve 52 is by means of the single actuator 48 turned and has holes, a first hole 54 and a second hole 56 , on, in another channel 58 (shown in dashed lines) open, which is the first valve 32 and the second valve 34 in the open state with the exhaust line 36 connect.

The first hole 54 and the second hole 56 have an angular offset to each other, so that the first valve 32 and the second valve 34 be opened at different times. The bores, unlike those shown, may be single or both may be elongated bores to allow the first valve 32 and the second valve 34 are open at the same time.

5 shows a further possible embodiment of the valve system of an exhaust gas turbocharger according to the invention.

In the embodiment shown is a piston valve 60 provided the first valve 32 and the second valve 34 to the exhaust line 36 opens. The actuation of the piston valve 60 can be made via a rack and pinion, in which one from the single actuator 48 driven gear 62 with a tooth section 64 interacts.

The piston valve 60 may have either a control edge or offset in the direction of displacement floods to the first valve 32 and the second valve 34 with the exhaust pipe 36 strömungszuverbinden.

6 shows a further possible embodiment of the valve system of an exhaust gas turbocharger according to the invention.

In this embodiment, axially spaced are two disks, a first disk 66 and a second disc 68 rotatably disposed, wherein the first disc 66 a first slot 70 and the second disc 68 a second slot 72 (shown in dashed lines).

The first disc 66 and the second disc 68 can be rotated independently of each other by means of two actuators or be coupled together by means of a toothed rack, so that the first disc 66 and the second disc 68 can be actuated by means of a common actuator.

In 6a have the first slot 70 and the second slot 72 the first disc 66 or second disc 68 no overlap on, in 6b have the first disc 66 and second disc 68 twisted relative to each other and the first slot 70 or the second slot 72 overlap in sections.

7 shows a diagram in which the opening cross sections A of the first valve 32 and the second valve 34 over an opening angle α of the second valve 34 the second exhaust line 14 are applied.

It can be seen that the first valve 32 only opens when the second valve 34 already a bit open. The opening cross-section of the first valve 32 is lower overall because the associated flood has a smaller diameter than that of the flood to the second valve 34 ,

The different, dashed curves show different opening cross-sections of the first valve 32 relative to the second valve 34 ,

A starting point of opening the first valve 32 must be set with an actuator.

In fully variable systems with two actuators, the starting point of opening the first valve may be 32 be moved further, which is symbolized by the arrows.

LIST OF REFERENCE NUMBERS

2

Internal combustion engine

4

turbocharger

6

cylinder

8th

input side

10

exhaust side

12, 14

first, second exhaust line

16

turbine

18, 20

first, second tide

22

wave

24

compressor

26

Intercooler

28

control valve

30

exhaust gas cooler

32, 34

first, second valve

36

exhaust train

38, 40

first, second valve disc

42, 44

first, second actuator

46

control unit

48

third actuator

50

feather

52

rotary vane

54, 56

first, second hole

58

channel

60

spool

62

gear

64

tooth portion

66, 68

first, second slices

70, 72

first, second slot

α

opening angle

A

Opening cross-section

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19857234 C2 [0003]
• DE 19836677 A1 [0004]
• DE 10132672 A1 [0005]

Claims (10)

Exhaust gas turbocharger for an internal combustion engine, with one of the exhaust gas of the internal combustion engine ( 2 ) drivable exhaust gas turbine, which can be connected to a first exhaust gas line ( 12 ) and a second exhaust line ( 14 ) of the internal combustion engine ( 2 ), and a compressor drivable by the exhaust gas turbine, for the arrangement in an intake tract ( 8th ) of the internal combustion engine ( 2 ), wherein the exhaust gas turbine turbine a turbine with a first exhaust gas flow ( 18 ) and a second exhaust gas flow ( 20 ) for fluid communication with the first exhaust line ( 12 ) and the second exhaust line ( 14 ) are provided, for the first exhaust gas flow ( 18 ) adjustable between a closed position and an open position first valve means and for the second exhaust gas flow ( 20 ) an adjustable between a closed position and an open position second valve device ( 34 ) for changeable adjustment of the exhaust gas flows ( 18 . 20 ) is to be supplied to the exhaust gas stream, characterized in that the first valve device ( 32 ) and the second valve device ( 34 ) are formed such that the respective opening states of the first valve devices ( 32 ) or the second valve device ( 34 ) depending on the state of the internal combustion engine ( 2 ) are adjustable. Exhaust gas turbocharger according to claim 1, characterized in that the first exhaust gas flow ( 18 ) and the second exhaust gas flow ( 20 ) have different cross sections. Exhaust gas turbocharger according to claim 1 or 2, characterized in that the first exhaust gas flow ( 18 ) for connection to a first exhaust gas line ( 12 ) of the internal combustion engine ( 2 ) and the second exhaust gas flow ( 20 ) for connection to a second exhaust line ( 14 ) of the internal combustion engine ( 2 ) is trained. Exhaust gas turbocharger according to claim 3, characterized in that the first exhaust line ( 12 ) associated first valve device ( 32 ) is designed such that it opens at a different time than that of the second exhaust gas line ( 14 ) associated second valve device ( 34 ). Exhaust gas turbocharger according to one of claims 1 to 4, characterized in that the first valve device ( 32 ) and the second valve device ( 34 ) Actuators which can be actuated independently of each other ( 42 . 44 ) exhibit. Exhaust gas turbocharger according to one of claims 1 to 4, characterized in that the first valve device ( 32 ) and the second valve device ( 34 ) a common actuator ( 48 ) exhibit. Exhaust gas turbocharger according to claim 6, characterized in that a second valve device ( 34 ) rigidly with the actuator ( 48 ), the first valve device ( 32 ) by means of a spring element ( 50 ) with the actuator ( 48 ) connected is. Exhaust gas turbocharger according to claim 6, characterized in that the first valve device ( 32 ) and the second valve device ( 34 ) a common rotary valve ( 52 ), which for the first valve device ( 32 ) and the second valve device ( 34 ) an opening bore ( 54 . 56 ), wherein the opening bores ( 54 . 56 ) have an angular offset. Exhaust gas turbocharger according to claim 6, characterized in that the first valve device ( 32 ) and the second valve device ( 34 ) a common piston valve ( 60 ) exhibit. Exhaust gas turbocharger according to one of the preceding claims, characterized in that the first valve device ( 32 ) and the second valve device ( 34 ) each a rotatably mounted disc ( 66 . 68 ) with at least one opening ( 70 . 72 ), wherein the openings ( 70 . 72 ) are angularly offset from each other or are adjustable.

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