WO2014131790A1

WO2014131790A1 - Internal combustion engine

Info

Publication number: WO2014131790A1
Application number: PCT/EP2014/053708
Authority: WO
Inventors: Michael Greiner; Oliver Hinrichs; Jasper Kammeyer; Peter Alberti
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2013-02-28
Filing date: 2014-02-26
Publication date: 2014-09-04
Also published as: EP2981699B1; EP2981699A1; CN105026743A; DE102013003418A1; KR101951074B1; CN105026743B; KR20150119950A

Abstract

The invention relates to an internal combustion engine with a combustion engine, an exhaust gas line, a fresh gas line, a turbocharger with a turbine integrated into the exhaust gas line, a compressor integrated into the fresh gas line, and a trim plate (12), by means of which the cross section of the compressor inflow can be adjusted. The internal combustion engine is characterized by a low-pressure exhaust gas recirculation system, by means of which exhaust gas downstream of the turbine is removed from the exhaust gas line and can be introduced into the fresh gas line upstream of the compressor, wherein an opening of the low-pressure exhaust gas recirculation system is arranged in the region of the trim plate (12).

Description

description

Internal combustion engine

The invention relates to an internal combustion engine with an internal combustion engine, a

Exhaust line, a fresh gas train, an exhaust gas turbocharger with a turbine integrated into the exhaust line and a compressor integrated in the fresh gas train, and with a trim plate, through which the cross section of the compressor inlet is variable.

In a compressor, the fresh gas supplied via the fresh gas train of the internal combustion engine is compressed. Here, the pressure increase of the speed of the impeller of the

Compressor as well as the mass flow of the guided over the impeller fresh gas. In the direction of the surge limit of the compressor map, the inflow of the leading edges of the impeller blades takes place on the pressure side as a result of the inflow velocity decreasing relative to the peripheral velocity. the incidence of

Flow is steadily increasing. From an operating point-dependent limit value of the incidence, the surge line, the flow at the entry edges triggers and the flow in the compressor becomes unstable.

In the region of the surge line, a return flow region of low-pulsation fluid is formed in the region of the housing contour of the compressor. This so-called backflow bubble leads to a drop in compressor efficiency due to swirl and mixing losses in the direction of the pumping limit. In the area of the hub contour of the impeller, however, there is also a pulse-rich and low-loss core flow through the compressor near the pumping limit, which determines the mass flow rate and the pressure build-up.

A trim controller is used to shift the surge limit of a compressor map in the direction of low mass flows at high pressure conditions. At the same time, a trim control can increase the compressor efficiency in the area of the pumping limit. For this purpose, a trim plate comprises a device by means of which the inflow cross-section, in which the impeller of the compressor is impinged, can be changed. Due to the nozzle effect of the trim adjuster achieved in this way, with increasing control intervention (reduction of the inflow cross section), the compressor inflow can be influenced more strongly by the flow cross section of the impeller close to the hub

Be focused compressor impeller. As a result, less fluid flows into the low-pulse and lossy region of the backflow bubble, and the core flow in the region near the hub is accelerated and thereby additionally stabilized. The acceleration of the flow in the Near-hub area of the compressor has in addition a suction-side displacement of the

Compressor flow result, which can contribute to a further stabilization of the flow. The stabilization of the core flow leads to the desired displacement of the

Pumping limit of the compressor map to lower mass flows of the exhaust gas. If not desired control intervention (Trimsteller fully open) as possible, the entire cross-section of the fresh gas line is released before the compressor, so that in the

Compressor inflow as possible no additional friction or throttle losses occur. The compressor efficiency and the width of the compressor map are therefore not significantly adversely affected in the direction of Stopfgrenze by the Trimsteller.

By shifting the surge line and the simultaneous increase of the

Compressor efficiency by means of a Trimstellers the dynamic response and the partial load operation of supercharged internal combustion engines can be improved. Due to the improved system efficiency, the exhaust back pressure can be lowered in the partial load range, whereby the consumption of the internal combustion engine decreases. By the

Efficiency increase and the shift of the surge line can be the maximum

Motor torque already achieved at lower engine speeds and thus the transient response of the internal combustion engine can be improved.

A generic internal combustion engine is known from DE 10 2010 026 176 A1. The trim controller there comprises a cone, which in one embodiment consists of a plurality of lamellae. The lamellae are arranged in two layers, wherein the lamellae of each layer are spaced apart from one another and the two layers are offset in relation to each other in rotation so that the lamellae of one layer cover the distances between the lamellae of the respective other layer. By means of a displaceable in the longitudinal axial direction, the fins on the outside surrounding ring, the outlet cross-section of the cone forming ends of the fins can be moved radially. This changes the size of the

Outlet cross section and thus the flow cross section, in which the impeller of the compressor is flown.

In today's internal combustion engines, a low-pressure exhaust gas recirculation (LP EGR) is increasingly used to achieve legally prescribed emission limits. The exhaust gas taken downstream of a turbine of an exhaust-gas turbocharger is introduced via a feed upstream of the compressor of the exhaust-gas turbocharger and drawn in by it with the fresh gas. The introduction of the recirculated exhaust gas should be as close as possible in front of the compressor in order to avoid or keep unwanted condensate formation in the fresh gas. For the regulation of the D-EGR rate, a control valve is usually integrated into the LP EGR introduction before the compressor entry. Both the supply line of the LP EGR and the Trimsteller should function as closely as possible be arranged in front of the impeller of the compressor, which is a competing

Construction space situation has.

Based on this prior art, the present invention seeks to provide an advantageous way to integrate a LP EGR in a generic

Specify internal combustion engine.

This object is achieved by an internal combustion engine according to independent claim 1. Advantageous embodiments thereof are the subject of the dependent

Claims and will become apparent from the following description of the invention.

A generic internal combustion engine with (at least) an internal combustion engine, (at least) an exhaust line, (at least) a fresh gas train, (at least) an exhaust gas turbocharger with (at least) a turbine integrated into the exhaust gas line and

(At least) one integrated in the fresh gas line compressor (in particular

Radial compressor), as well as with (at least) a trim plate, through which the cross section of the compressor inlet is variable, according to the invention (at least) one

Low pressure exhaust gas recirculation (ND-EGR), through the exhaust gas downstream of the turbine taken from the exhaust line and upstream of the compressor in the fresh gas train can be introduced, wherein (at least) a mouth of the LP-EGR in the region of the Trimstellers, i. in the same section of the fresh gas train as the Trimsteller or the cross section of

Compressor inflow changing element of the trim adjuster is arranged.

By integrating the mouth of the LP EGR in the Trimsteller can be achieved that both the Trimsteller and the mouth of the LP EGR are arranged as close to the inlet side of the compressor impeller. The space competition of these two components is thereby solved.

The inventive design of an internal combustion engine, further advantages can be achieved, as shown below. In particular, can

be advantageously provided that the integration of the mouth and the design of the Trimstellers or the cross section of the compressor flow changing element is selected such that by means of the Trimstellers and the amount of introduced into the fresh gas exhaust gas is controlled or regulated. Thus, the movable compressor inflow varying member may preferably be arranged and configured to serve as a control valve or control valve for the LP EGR. This embodiment is in particular advantageously implementable, because the operating ranges of the internal combustion engine, in which a LP EGR is usefully used, regularly correlate with a corresponding operation of the compressor in the vicinity of the surge limit. In particular, an increase in the LP EGR rate may be associated with a shift in the operating point of the compressor

Compressor map correlate in the direction of the surge limit, so that it may preferably be provided that the Trimsteller in a reduction of the cross-section of the

Compressor current increase a passage cross-section for the exhaust gas. Thus, the amount of exhaust gas recirculated via the LP EGR can be increased in proportion to the reduction of the inflow section by the trim plate.

In operating conditions of the internal combustion engine, in which a reduction of the

Flow cross-section for the operation of the compressor is no longer necessary and thus should also be avoided to avoid throttling losses is regularly no

Exhaust gas recirculation via the LP EGR more necessary. Preferably, therefore, it can be provided that the passage cross-section is completely closed by means of the trim adjuster.

In a preferred embodiment, the trim plate can have a funnel-shaped wall system arranged inside a tubular housing (a section of the fresh gas line), wherein an outlet cross section of the wall system is variable by a more or less spreading of the wall system and wherein the passage cross section for the exhaust gas between the wall system and the housing is formed. Particularly preferably, the mouth of the LP-EGR can be arranged in the region of the wall system.

Thus, the wall system may serve as a valve body of an EGR valve for the LP EGR, with the wall system at full spread, i. the largest possible flow cross-section of the compressor impeller, a portion of the housing uses as a valve seat. This represents a structurally simple and therefore cost-effective realization of a regulation of the recirculated exhaust gas by means of the trim adjuster. However, even if the trim adjuster can assume the function of an EGR valve, a separate EGR valve can be provided. This can be particularly advantageous if a control of the LP EGR independent of the trim actuator or of its influence on the EGR feedback rate is to be achieved.

In a preferred embodiment, the wall system may have a plurality of first

Wall elements which are circumferentially spaced from each other in a ring-shaped, and a plurality of second wall elements which are circumferentially spaced from each other in a ring-shaped, wherein the second wall elements cover the distances between the first wall elements. Furthermore, the trim plate can have an adjusting device (eg, electrically, pneumatically or hydraulically actuated), by means of which the ends of the first and / or second wall elements forming the outlet cross-section are in Radial direction are displaced. In this way, an adjustable, funnel-shaped wall system can be created in a structurally simple manner, which makes do without the use of highly elastic materials, such as elastomers. The wall elements can thus advantageously be formed from a substantially rigid material and in particular metal (s) (eg steel).

The Verstelivorrichtung may have a position detection, which can avoid the respective position of the wall system to a control electronics (for example, engine control) of the internal combustion engine to set a targeted adjustment of the trim adjuster to the operating point of the internal combustion engine.

In order to be able to absorb the angular change that results from the change in the outlet cross section of the wall element, it can furthermore preferably be provided that the wall elements are rotatably mounted on the end forming an inlet cross section of the wall system.

It can be particularly preferably provided that at least some of the wall elements are mounted rocker-like, so that in a radial, inwardly directed displacement of the outlet cross-section forming ends of these wall elements, the inlet cross-section forming ends of these wall elements are displaced radially outwards, resulting in an elastic Bias (at least) connected to a spring element. As a result, a rotatable mounting can be realized with a spring action of the wall system in its open position in a simple manner.

The wall elements can (at least partially) at the the inlet cross section of the

Wallsystems forming end also be firmly clamped, the angle change is absorbed by an elastic deformation of the wall elements. Since the deformation in this case is comparatively small, this can also be achieved with wall elements made of e.g. Metal (s) can be realized. As a result, if necessary, an additional spring element for

Be charged to the wall system in its open position.

Preferably, it can be provided that the wall elements have a U-shaped cross-section, wherein the ends of the free legs of each first wall element rest on a respective second wall element (and vice versa). Thereby, the resistance for the sliding relative movement between the first wall elements and the second

Wall elements are kept small. In addition, this can limit the maximum spread of the wall system. A preferred because structurally simple embodiment of the adjusting device may comprise an adjusting ring with one or more guide grooves, wherein the first and / or second wall elements are guided in the guide grooves, that a rotation of the adjusting ring to a radial displacement of the outlet cross-section forming ends of the first and / or second wall elements leads.

The embodiments of the Trimstellers according to the claims 7 to 1 1 is independent of the mouth of the LP-EGR in the area of the trim adjuster and has over the known trim actuators relevant advantages. These embodiments thus represent independent inventions.

The present invention will be explained in more detail with reference to embodiments shown in the drawings. In the drawings shows:

Fig. 1: in a schematic representation of a Trimsteller with fully open

Outlet cross-section and a compressor of an inventive

Internal combustion engine in a first embodiment;

FIG. 2 shows a cross section through the trim plate according to FIG. 1 along the sectional plane II-II in FIG. 1; FIG.

Fig. 3: the unit of Trimsteller and compressor of FIG. 1, but with reduced

Outlet cross-section of the trim adjuster;

4 shows a cross section through the trim plate according to FIG. 3 along the sectional plane IV-IV in FIG. 3;

Fig. 5: a Trimsteller with fully open outlet cross section and a

Compressor of an internal combustion engine according to the invention in a second embodiment;

Fig. 6: the unit of Trimsteller and compressor of FIG. 5, but with reduced

Outlet cross-section of the trim adjuster;

Fig. 7: In a first perspective view of an adjustable wall system and a

Adjusting device of a trim plate for an internal combustion engine according to the invention in a third embodiment; and 8 shows the unit of wall system and adjusting device according to FIG. 7 in a second perspective view.

1 and 3 show in a schematic longitudinal section a radial compressor 10 and a first embodiment of a Trimstellers 12 for an inventive

Internal combustion engine.

The trim plate 12 comprises a tubular housing 14 which is upstream of the

Radial compressor 1 can be integrated into a fresh gas line of the internal combustion engine. In this case, the housing 14 is connected downstream with the radial compressor 10 directly on the inlet side. Within the housing 14, a wall system 16 is arranged in the present

Embodiment, two half-shell or Schaufeiförmige wall elements 18 includes, which are rotatably mounted at its upstream end to the inside of the housing 14. At these ends, both wall elements 18 have a substantially semicircular cross-section. In the direction of the downstream end, the lengths of the part-circular cross-sections of the wall elements 18 decrease continuously, the

Length reduction of the wall element 18 shown in FIGS. 1 to 4 above is higher than that of the lower wall element 18. This allows the upper wall member 18 to be submerged in the lower wall member 18 (see Figure 4) when the wall members 18 are pivoted inwardly by means of an adjustment device, not shown, whereby the free, downstream ends are radially (with respect to the longitudinal axis 20 of the trimmer ) move inwards. By pivoting the size of the outlet cross-section of the wall system 16 and the trim plate 12 relative to the fully open position, as shown in FIG. 1, is reduced (see Fig .. 3). At the same time, the shape of the outlet cross-section changes from essentially circular to elliptical. The reduction of the outlet cross section leads to a focus of the fresh gas flowing through the trim plate 12 on the central portion of an impeller 22 of the centrifugal compressor 10 and thus to a reduction of the inflow cross section of the centrifugal compressor 10 in comparison to the fully open position of the trim adjuster 12th

The lower wall element 18 also serves as an EGR valve of a LP EGR, which opens into the housing 14 in the region of the wall system 16 of the trim actuator 12. When the trimmer 12 is fully open, the lower wall element 18 completely covers the mouth 24 of the LP-EGR, so that essentially no exhaust gas recirculation takes place. With increasing reduction of the outlet cross section of the trim adjuster 12, the lower wall element 18 releases a widening, part-circular annular gap through which exhaust gas from the LP EGR can flow into the centrifugal compressor 10. 5 and 6 show a radial compressor 10 and a trim plate 12 in a comparison with the embodiment according to FIGS. 1 to 4 modified embodiment.

The trim plate 12 includes a housing 14 that is housed in one of a housing 26 of the

Radial compressor 10 trained receptacle is immovably arranged. Within the housing 14 of the Trimstellers 12, a funnel-shaped wall system 16 is arranged, which is formed from a plurality of strip-shaped wall elements 28, 30 with part-circular cross-sections. The wall system 16 corresponds to the wall system 16, as shown in FIGS. 7 and 8. The wall elements 28, 30 are arranged in two coaxial, circular layers and have a U-shaped cross-section, i. these include in addition to a strip-shaped, in cross-section part-circular base portion still two thereof approximately at a right angle extending leg, the legs of the (first)

Wall elements 28 of the first, inner layer are directed radially outward, while the legs of the (second) wall elements 30 of the second, outer layer are directed radially inwardly. The wall elements 28, 30 of each of the two layers are also spaced apart from one another, with a rotational offset being provided between the two layers, so that the wall elements 28, 30 of each layer the

Cover spaces between the other layers. This results in a

Essentially closed, funnel-shaped wall system 16. The wall elements 28, 30 of the two layers contact via the comparatively small-area end edges of the legs, whereby a relatively low-resistance sliding of the wall elements 28, 30 can be achieved on each other. In addition, the legs of the wall elements 28, 30 form end stops which limit the spreading of the wall system 16.

A more or less successful spreading of the funnel-shaped wall system 16, even in the fully opened state, i. a radial displacement of the free, downstream ends of the wall elements 28, 30 takes place in the embodiment according to FIGS. 5 and 6 by means of a sliding ring 32, which surrounds the wall elements 28, 30 on the outside and by means of an adjusting device 34 in the direction of its longitudinal axis is displaceable. The

Upstream ends of the wall elements 28, 30 are rotatably or pivotably mounted, so that the adjusting by the radial displacement of the free ends angle change is not compensated by means of a deformation of the wall elements 28, 30. As a bearing element for the rotatable or rocker-like storage is a bearing ring 36 which has a number of wall elements 28, 30 corresponding number of slot-shaped openings through which narrow end portions of the wall elements 28, 30 extend. By means of a spring ring 38, e.g. made of an elastomer, the wall system 16 is acted upon in its fully open position (see Fig. 5). The spring ring 38 is formed by the end portions of each of the first

Wall elements 28 embraced approximately semicircular. As a result of the rocker-like storage of Wall elements 28, 30 in the bearing ring 36 performs an inwardly directed, radial

Moving the free ends of the wall elements 28, 30 to an outwardly directed, radial displacement of the end portions and thus to an elastic circumferential magnification in conjunction with an (increasing) elastic bias of the spring ring 38th

In the housing 26 of the radial compressor 10 extends an orifice passage 40, which is provided for connection to a LP EGR of an internal combustion engine according to the invention. The mouth channel 40 opens in the region of the wall system 16 in the housing 14 of the

Trimstellers 12. Exiting the mouth channel 40 exhaust gas can thus spread in a ring surrounding the wall system 16 annular space 42. In the fully open state of the trimmer 12, the free ends of the wall elements 28, 30 bear against an edge 44 of an inlet channel of the radial compressor 10. An overflow of the exhaust gas from the annular space 42 in the inlet channel of the centrifugal compressor 10 is thereby largely avoided. With increasing reduction of the outlet cross section of the Trimstellers 12 due to a displacement of the free ends of the wall elements 28, 30 radially inwardly a widening circular annular gap is released, can flow through the exhaust gas from the annular space 42 in the centrifugal compressor 10.

FIGS. 7 and 8 show an alternative embodiment of an adjusting device 34, as can be used in a trim plate 12 according to FIGS. 5 and 6. The adjusting device 34 comprises an adjusting ring 46 which is one of the number of second

Wall elements 30 corresponding number of obliquely extending guide grooves 48 has. In each of the guide grooves 48, a guide pin 50 is slidably mounted. The

Guide pins 50 are each a mounting arm 52 with one of the second

Wall elements 30 connected. As a result of the oblique orientation of the guide grooves 48, a rotation of the adjusting ring 46 leads to a radial displacement of the guide pins 50 and thus of the second wall elements 30. The second wall elements 30 take with a radial displacement inwardly the first wall elements 28 with. In a radial

On the other hand, displacement towards the outside by means of the spring ring 38 ensures that the first wall elements 28 follow the movement of the second wall elements 30. Radial compressor

Trimsteller

casing

wall system

wall element

longitudinal axis

Wheel

muzzle

casing

first wall element

second wall element

sliding ring

adjustment

bearing ring

spring washer

estuary channel

annulus

edge

adjusting

guide

guide pins

Mounting Arm

Claims

claims

1. internal combustion engine with an internal combustion engine, an exhaust line, a

Fresh gas train, an exhaust gas turbocharger with a turbine integrated into the exhaust line and a compressor integrated in the fresh gas train, and with a Trimsteller (12) through which the cross section of the compressor inlet is variable, characterized by a low-pressure exhaust gas recirculation, downstream of the exhaust gas from the turbine exhaust gas taken and upstream of the compressor in the

Frischgaststrang is introduced, with an opening of the low-pressure exhaust gas recirculation in the region of the Trimstellers (12) is arranged.

2. Internal combustion engine according to claim 1, characterized in that by means of

Trimstellers (12) and the amount of introduced into the fresh gas exhaust gas is adjustable.

3. Internal combustion engine according to claim 2, characterized in that the trim plate (12) at a reduction of the cross section of the compressor inlet a

Enlarged passage for the exhaust gas.

4. Internal combustion engine according to claim 3, characterized in that the

Passage cross section by means of the Trimstellers (12) is completely closed.

5. Internal combustion engine according to one of the preceding claims, characterized

in that the trim plate (12) has a funnel-shaped wall system (16) which is arranged inside a tubular housing (14), wherein an outlet cross section of the wall system (16) is produced by a more or less spreading of the wall structure

Is wall system (16) is variable and wherein the passage cross-section for the exhaust gas between the wall system (16) and the housing (14) is formed.

6. Internal combustion engine according to claim 5, characterized in that the mouth (24) of the low-pressure exhaust gas recirculation is arranged on the outside in the region of the wall system (16) and / or that the wall system (16) has a plurality of first wall elements (28) which are spaced in the circumferential direction are arranged annularly from one another, and a plurality of second wall elements (30) which are circumferentially spaced from one another annularly, wherein the second wall elements (30) cover the distances between the first wall elements (28) and that the Trimsteller (12) an adjusting device (34), by means of which the Outlet cross-section forming ends of the first wall elements (28) and / or second wall elements (30) are displaceable in the radial direction.

7. Internal combustion engine according to claim 6, characterized in that the

Wall elements (28, 30) are rotatably mounted on the one inlet cross-section of the wall system (16) forming end.

8. Internal combustion engine according to claim 7, characterized in that at least some of the wall elements (28, 30) are mounted rocker-like, so that in a radial, inwardly directed displacement of the outlet cross-section forming ends of these wall elements (28, 30) forming the inlet cross-section Ends of this

Wall elements (28, 30) are moved radially outward, which is connected to a resilient bias of a spring element.

9. Internal combustion engine according to one of claims 6 to 8, characterized in that the wall elements (28, 30) have a U-shaped cross-section.

10. Internal combustion engine according to one of claims 6 to 9, characterized in that the adjusting device (34) has an adjusting ring (46) with one or more

Guide grooves (48), wherein the first and / or second wall elements (28, 30) are guided in one or more of the guide grooves (48) such that a rotation of the adjusting ring (46) to a radial displacement of the outlet cross-section forming ends first wall elements (28) and / or second wall elements (30) leads in the radial direction.