KR101951074B1

KR101951074B1 - Internal combustion engine

Info

Publication number: KR101951074B1
Application number: KR1020157026220A
Authority: KR
Inventors: 미햐엘 그라이너; 올리버 힌리히스; 야스퍼 캄마이어; 페터 알베르티
Original assignee: 폭스바겐 악티엔 게젤샤프트
Priority date: 2013-02-28
Filing date: 2014-02-26
Publication date: 2019-02-21
Also published as: DE102013003418A1; KR20150119950A; CN105026743A; WO2014131790A1; CN105026743B; EP2981699B1; EP2981699A1

Abstract

The present invention relates to a combustion engine, an exhaust gas line, a fresh gas line, a turbocharger with a turbine integrated in the exhaust gas line, and a compressor incorporated in the fresh gas line, and a trim plate 12 ), Characterized in that the internal combustion engine according to the present invention is provided with a low-pressure exhaust gas recirculation device in which the exhaust gas is removed from the exhaust gas line downstream of the turbine by the low-pressure exhaust gas recirculation device May be introduced into the fresh gas line upstream of the compressor and the opening of the low pressure exhaust gas recirculation apparatus is disposed within the region of the trim plate 12. [

Description

Internal combustion engine {INTERNAL COMBUSTION ENGINE}

The present invention relates to a combustion engine, an exhaust gas line, a fresh gas line, a turbocharger with a turbine integrated in the exhaust gas line, and a compressor incorporated in the fresh gas line, and a trim plate (trim plate of the internal combustion engine.

In the compressor, the drawn gas supplied through the fresh gas line of the combustion engine is compressed. At this time, the pressure increase depends on the number of revolutions of the compressor impeller and the mass flow rate of the fresh gas guided through the impeller. In the surge limit direction of the compressor characteristic map, the inflow at the leading edge of the impeller blade is increased in the discharge side due to the inflow velocity decreasing in proportion to the circumferential velocity, that is, the inflow occurrence rate continues to increase . From the limit of the operating point-dependent incidence rate, that is, from the surge limit, the flow at the leading edge is divided and the flow in the compressor becomes unstable.

In the surge limit region, a backflow zone of fluid with a small momentum in the housing contour area of the compressor is formed. Such so-called countercurrent bubbles cause the compressor efficiency to decrease in the direction of the surge limit due to eddy currents and mixing losses. However, in the region of the hub contour of the impeller, a core flow that is rich in momentum and relatively low in loss near the surge limit passes through the compressor, and the core flow determines mass flow rate and pressure formation.

The trim plate is used to move the surge limit of the compressor characteristic map in the direction of low mass flow rate when the pressure ratio is high. At the same time, the trim plate can cause an increase in compressor efficiency in the surge limit region. To this end, the trim plate includes a device capable of varying the inlet cross-sectional area through which the compressor impeller is introduced. With the nozzle effect of the trim plate obtained in this way, the compressor inflow can be more concentrated in the flow cross-sectional area near the hub of the compressor impeller as the control interference increases (reduction in inlet cross-sectional area). Thereby, less fluid flows into the region accompanied by loss of motion of the backflow bubble, and further stabilization is achieved by accelerating the core flow in the region close to the hub. The acceleration of the compressor flow in the region near the hub further moves the compressor inlet to the intake side, which can contribute to continued flow stabilization. Stabilization of the core flow allows the surge limit of the compressor characteristic map to be shifted as desired to a lesser exhaust gas mass flow rate. If no control interference is desired (the trim plate is fully open), the entire cross-section of the fresh gas line upstream of the compressor is maximally open, so that no further frictional losses or throttling losses occur at the compressor inlet. As a result, the width of the compressor efficiency and compressor characteristics map is not significantly affected by the trim plate in the direction of the braking limit.

The dynamic response characteristic and the partial load mode of the supercharged internal combustion engine can be improved by the movement of the surge limit using the trim plate and the simultaneous increase of the compressor efficiency. Due to the improved system efficiency, the back pressure of the exhaust gas in the partial load region drops, thereby reducing the consumption of the internal combustion engine. Through the increase of the efficiency and the movement of the surge limit, it is possible to reach the maximum engine torque already at the lower engine speed, whereby the transient response characteristic of the internal combustion engine can be improved.

A homogeneous internal combustion engine is known from German Published Patent Application DE 10 2010 026 176 A1. The trim plates disclosed in this document include, in one embodiment, a plurality of thin plate-formed cones. These thin plates are arranged in two layers, in which the thin plates of each layer are spaced from one another and the plates of one layer cover the gaps of the plates of the other individual layers as the two layers are rotationally offset relative to one another. The ends of the plates forming the outlet cross-section of the cone can be displaced radially using a ring displaceable in the longitudinal direction and enclosing the plates in the outer surface. As a result, the size of the outlet cross-section is changed, thereby changing the size of the inlet cross-sectional area flowing into the impeller of the compressor.

In recent combustion engines, the use of low-pressure exhaust gas recirculation (LP-EGR) has been increasing in order to reach the regulated gas emission limit value. Exhaust gas removed from the turbocharger downstream of the turbocharger is introduced through an inlet in front of the compressor of the turbocharger and the drawn gas is sucked by the compressor. In this case, the inflow of the recirculated exhaust gas should preferably be made near the front of the compressor, in order to prevent or keep undesired condensate formation in the fresh gas. For control of the LP-EGR ratio, a control valve is usually incorporated in the LP-EGR inlet in front of the compressor inlet.

In addition to the LP-EGR supply line, the trim plate also has to be disposed as close as possible to the front of the compressor impeller in relation to the function, resulting in conflicting installation space conditions.

An object of the present invention based on the above prior art is to provide a desirable possibility of integrating LP-EGR into a conventional internal combustion engine.

The above problem is solved by the internal combustion engine according to claim 1. Preferred embodiments of this internal combustion engine are subject to dependent claims and are described in the following description of the invention.

(One or more) turbochargers integrated in the exhaust gas line, (one or more) turbochargers incorporated in the exhaust gas line, and (iii) exhaust gas lines integrated in the exhaust gas line (At least one) compressor (particularly a centrifugal compressor), and a trim plate (at least one) capable of varying the cross-sectional area of the compressor inlet are provided in accordance with the present invention in the form of a low pressure exhaust gas recirculation (LP- EGR), the exhaust gas can be removed from the exhaust gas line downstream of the turbine and introduced into the fresh gas line upstream of the compressor by the low pressure exhaust gas recirculation device, wherein the LP- The opening is in the region of the trim plate, that is, the same as the trim plate, or the trim plate section The same as the ash, within the section of the fresh gas line.

By integrating the opening of the LP-EGR into the inside of the trim plate, the opening of the LP-EGR as well as the trim plate can be arranged as close as possible to the inflow side of the compressor impeller. As a result, space conflicts between the two components are eliminated.

Through the embodiment of the internal combustion engine according to the present invention, further advantages as described below can be obtained. Particularly preferably, the shape of the element that adjusts the shape of the trim plate and the cross-sectional area of the compressor inlet so as to allow the opening of the exhaust gas flowing into the fresh gas line using the trim plate, May be proposed. Accordingly, the movable element for regulating the compressor inflow can preferably be arranged and formed such that the element is used as an open-circuit control valve or a closed-loop control valve for LP-EGR. Such a configuration can be particularly advantageously modified because the operating regions of the combustion engine in which the LP-EGR can be usefully used are regularly correlated with the corresponding mode of the compressor near the surge limit. In particular, an increase in the LP-EGR-ratio can be correlated with the movement of the compressor operating point in the surge limit direction of the compressor operating point, and as a result, the cross-section of the compressor inlet is preferably reduced, And expand it. Accordingly, the amount of exhaust gas recirculated through the LP-EGR can increase in proportion to the reduction of the inlet cross-section by the trim plate.

In the operating state of the combustion engine, in which the reduction of the inlet cross section for the operation of the compressor is no longer necessary and thus the reduction of the inlet cross section is to be avoided in order to avoid throttling losses, Gas recirculation is no longer necessary. Therefore, preferably, the trim plate can be used to completely close the perfusion cross-section.

In one preferred embodiment, the trim plate may have a funnel-shaped wall system disposed within a tubular housing (one section of the drafting gas line), and the outlet cross-section of the wall system is configured such that the wall system is expanded And in this case a cross-sectional flow cross-section for the exhaust gas is formed between the wall system and the housing. Particularly preferably, the opening of the LP-EGR at this time can be arranged in the region of the wall system. Accordingly, the wall system can be used as the valve body of the EGR valve for LP-EGR, where the wall system can be used when the expansion is complete, in other words when the inflow cross section of the compressor impeller is at its maximum, Section as a valve seat. This makes it possible to control the exhaust gas recirculated by using the trim plate in a simple and therefore economical manner. Even if the trim plate can function as an EGR valve, a separate EGR valve can be provided. This may be particularly desirable where control of the LP-EGR must be performed independent of the effects of the trim plate on the trim plate or EGR-recycle.

In one preferred embodiment, the wall system may have a plurality of first wall elements arranged annularly spaced apart in the circumferential direction and a plurality of second wall elements arranged annularly spaced apart in the circumferential direction, The second wall elements cover the gap of the first wall elements. In addition, the trim plate may have an adjusting device (e. G., Electrically, pneumatically or hydraulically actuated) which limits the ends of the first and / or second wall elements forming the outlet cross- . &Lt; / RTI > In this way, an adjustable funnel-shaped wall system can be made structurally simple, and such a wall system can be made sufficiently without the use of a highly elastic material such as an elastomer. Thus, the wall elements are preferably formed of a generally rigid material and in particular metal (s) (e.g., steel).

The adjustment device may be provided with a position identification device which is adapted to provide an electronic control system of the internal combustion engine (for example an engine control device) with a control system for the wall system Individual locations can be fed back.

More preferably, the wall elements can be rotatably supported at the end forming the inlet cross-section of the wall system so as to be able to accommodate the angular variation resulting from the adjustment of the outlet cross-sectional area of the wall element.

In this case particularly preferably at least a few wall elements are formed in the form of a rocker so that when the ends of these wall elements forming the outlet cross section move radially inward, The ends can move radially outward, which is associated with an elastic preload of the spring element (s). Thereby, the rotatable support in which the wall system is spring biased to the open position can be simply realized.

The wall elements may be secured (at least partially) to the end forming the inlet cross-section of the wall system, in which case an angular change due to the elastic deformation of the wall elements is accommodated. In this case, since the deformation is relatively small, the acceptance of the angular variation can be realized even when the wall elements are formed of, for example, metal (s). Thereby, in some cases an additional spring element for pressing the wall system to the open position can be omitted.

Preferably, the wall elements may have a U-shaped cross-section, in which case the ends of the free legs of each first wall element are each raised on one second wall element (and vice versa). Thereby, the resistance for the slidable relative movement between the first wall element and the second wall element can be kept small. Also, this can limit the maximum expansion of the wall system.

One structurally simple preferred embodiment of the adjusting device can comprise an adjusting ring with one or more guide grooves, in which case the first and / or second wall elements are arranged such that the rotation of the adjusting ring forms the outlet cross- The ends of the first and / or second wall elements are guided in the guide groove to move radially.

Embodiments of the trim plate according to claims 7 to 11 are independent of the opening of the LP-EGR in the region of the trim plate and have associated advantages over known trim plates. Thus, these embodiments are inventions independent of known trim plates.

The present invention will be described in detail below with reference to the embodiments shown in the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows schematically a compressor of a internal combustion engine according to the invention in a first embodiment, and a trim plate with a fully open outlet cross section;
Fig. 2 shows a cross-sectional view of the trim plate according to Fig. 1 cut along the cutting plane II-II in Fig. 1;
Figure 3 shows a unit in a state in which the outlet cross-section of the trim plate is reduced, although it consists of the trim plate and the compressor according to Figure 1;
Figure 4 shows a cross-sectional view of the trim plate according to Figure 3 cut along the cutting plane IV-IV of Figure 3;
Figure 5 shows a compressor of the internal combustion engine according to the invention and a trim plate with a fully open outlet cross section in a second embodiment;
Figure 6 shows a unit in a state in which the outlet cross-section of the trim plate is reduced, although it consists of the trim plate and the compressor according to Figure 5;
Figure 7 shows a third embodiment of the adjustment device and the adjustable wall system for a trim plate for an internal combustion engine according to the present invention in a first perspective view; And
Fig. 8 is a second perspective view of a unit made up of the wall system and the adjusting device according to Fig. 7;

Figures 1 and 3 show a first embodiment of a trim plate 12 for an internal combustion engine according to the invention and a schematic longitudinal section view of a centrifugal compressor 10.

The trim plate 12 comprises a tubular housing 14 which can be integrated within the draft gas line of the internal combustion engine upstream of the centrifugal compressor 1. At this time, the housing 14 is directly connected to the centrifugal compressor 10 at the inlet side toward the downstream side. Inside the housing 14 is disposed a wall system 16 which in this embodiment comprises two wall elements 18 in the form of half-shells or blades, And is rotatably supported on the inner surface of the housing 14 at one end thereof. At these ends, the two wall elements 18 have a substantially semicircular cross section. The length of the cross-section of the partial circle shape of the wall element 18 is continuously shortened in the direction of the downstream end, in this case the width of the wall element 18 shown in the upper part of FIGS. 1 to 4, Is greater than the shortening width of the element (18). This is because the wall elements 18 can be pivoted inwardly by means of an adjustment device not shown in the figure so that when the downstream free ends move radially inwardly (with respect to the longitudinal axis 20 of the trim plate) Allowing the top wall element 18 to lock into the bottom wall element 18 (see FIG. 4). This pivoting operation reduces the size of the outlet cross-section of the wall system 16 or trim plate 12 relative to the fully open position as shown in FIG. 1 (see FIG. 3). At the same time, the shape change of the outlet cross section is made substantially from a circular shape to an elliptical shape. Reduction of the outlet cross section causes the draft gas flowing through the trim plate 12 to be concentrated in the central section of the impeller 22 of the centrifugal compressor 10, thereby allowing the trim plate 12 to be centrifuged Thereby reducing the inflow cross-sectional area of the compressor (10).

The lower wall section 18 is also used as the EGR valve of the LP-EGR in communication with the interior of the housing 14 in the region of the wall section 16 of the trim plate 12. [ In the fully open state of the trim plate 12, the lower wall element 18 completely covers the opening 24 of the LP-EGR, so that exhaust gas recirculation is virtually never achieved at all. As the outlet cross-section of the trim plate 12 is gradually reduced, the lower wall element 18 opens an annular gap that extends into a partial circle, and exhaust gas from the LP-EGR flows through the annular gap into the centrifugal compressor 10, Lt; / RTI >

Figures 5 and 6 show the centrifugal compressor 10 and the trim plate 12 in a modified embodiment for the embodiment according to Figures 1-4.

The trim plate 12 includes a housing 14 which is immovably disposed within a receiving portion formed by the housing 26 of the centrifugal compressor 10. A funnel-shaped wall system 16 is arranged inside the housing 14 of the trim plate 12 and is formed from a plurality of wall elements 28, 30 in the form of strips having a partial circular cross- . The wall system 16 corresponds to the wall system 16 as shown in Figs. The wall elements 28, 30 are arranged in two coaxial circular layers and have a U-shaped cross section, that is to say that they are each in the form of a strip of circular cross section, , Further comprising two legs extending substantially at right angles from the base section, wherein the legs of the first layer (first) wall element 28 of the inner layer in this case are directed radially outward, The legs of the (second) wall element 30 of the second layer are oriented radially inward. The two wall elements 28, 30 of the two layers are also spaced apart from each other, in this case by providing a rotational offset between the two layers, The wall elements 28 and 30 each cover an intermediate space of the other layer. Thereby, a substantially closed funnel-shaped wall system 16 appears. The two-layer wall elements 28, 30 contact each other through the relatively small end edges of the legs, so that the wall elements 28, 30 can slide above each other with relatively no resistance. In addition, the legs of the wall elements 28, 30 form an end stop that limits the expansion of the wall system 16.

The expansion of the funnel-shaped wall system 16 is done more or less, i. E., The radial movement of the free end downstream of the wall elements 28, 30, In this embodiment by a sliding ring 32 which surrounds the wall elements 28 and 30 from the outside and can be moved in the direction of its longitudinal axis by the adjusting device 34. [ The upstream end portions of the wall elements 28 and 30 are rotatably or pivotably supported so that the angular change that is set by the radial movement of the free ends results in a deformation of the wall elements 28 and 30 It is not compensated by. As a support element for rotatable support or rocker-shaped support, a support ring 36 having a number of slot-like openings corresponding to the number of wall elements 28, 30 is used and the slot- So that the narrow and long end sections of the wall elements 28, 30 extend. For example, by means of a spring ring 38 made of an elastomer, the wall system 16 is moved to its fully open position (see Fig. 5). The spring ring 38 is surrounded by an end section of each first wall element 28 in a generally semicircular shape. Since the wall elements 28 and 30 are supported in the form of a rocker within the support ring 36, the radial movement movement towards the interior of the free ends of the wall elements 28 and 30 results in radial movement Causing an elastic circumferential expansion with the elastic preload of the spring ring 38 (increased).

In the housing 26 of the centrifugal compressor 10, an opening channel 40 provided for connection to the LP-EGR of the internal combustion engine according to the present invention extends. The open channel 40 communicates with the interior of the housing 14 of the trim plate 12 in the area of the wall system 16. Thereby, the exhaust gas discharged from the opening channel 40 can be expanded inside the annular space 42 annularly surrounding the wall system 16. [0050] With the trim plate 12 fully open, the free ends of the wall elements 28, 30 abut one edge 44 of one inlet channel of the centrifugal compressor 10. Thereby, exhaust gas is prevented from overflowing from the annular space 42 into the inlet channel of the centrifugal compressor 10 as a whole. As the free end portions of the wall elements 28, 30 move radially inwardly, the outlet cross-section of the trim plate 12 is gradually reduced, so that an annular gap extending in a circular shape is opened, Can be introduced into the centrifugal compressor (10) from the annular space (42).

7 and 8, there is shown an alternative embodiment of an adjustment device 34 as can be used in the trim plate 12 according to Figs. 5 and 6. Fig. The adjustment device 34 comprises an adjustment ring 46 which has a number of angled guide grooves 48 corresponding to the number of the second wall elements 30. A guide bolt 50 is movably supported in each of the guide grooves 48. The guide bolts 50 are each connected to one of the second wall elements 30 through a single fixed arm 52. The guide groove 48 is angled so that rotation of the adjustment ring 46 causes radial movement of the guide bolt 50 and the second wall element 30 therewith. The second wall element (30) moves with the first wall element (28) when moving radially inward. In contrast, when moving radially outward, actuation with the spring ring 38 causes the first wall element 28 to follow the movement of the second wall element 30.

10: Centrifugal compressor
12: Trim plate
14: Housing
16: Wall system
18: Wall elements
20:
22: Impeller
24: opening
26: Housing
28: first wall element
30: second wall element
32: Sliding ring
34: adjusting device
36: Support ring
38: Spring ring
40: opening channel
42: annular space
44: Edge
46: adjusting ring
48: Guide groove
50: Guide bolt
52: Fixed arm

Claims

A turbocharger equipped with a combustion engine, an exhaust gas line, a fresh gas line, a turbine integrated with the exhaust gas line, and a compressor 10 integrated in the fresh gas line, and a trim plate 12 capable of adjusting the cross section of the compressor inlet In one internal combustion engine,
The internal combustion engine has a low pressure exhaust gas recirculation device in which the exhaust gas is removed from the exhaust gas line downstream of the turbine and can be introduced into the fresh gas line upstream of the compressor, An opening of the gas recirculation device is disposed in the region of the trim plate 12,
By means of the trim plate 12, the amount of exhaust gas flowing into the fresh gas line can be controlled,
The reduction of the cross-section of the outlet of the trim plate (12) causes the draft gas flowing through the trim plate (12) to be concentrated in the central section of the impeller (22) of the compressor (10).

delete

2. An internal combustion engine according to claim 1, characterized in that the trim plate (12) enlarges the cross-section of the cross-section for the exhaust gas when the cross-section of the compressor inlet is reduced.

4. An internal combustion engine as set forth in claim 3, characterized in that said cross section can be completely closed by the trim plate (12).

The system of any one of claims 1, 3, and 4, wherein the trim plate (12) has a funnel-shaped wall system (16) disposed within the tubular housing (14) Characterized in that the outlet cross section of the wall system (16) can be adjusted due to more or less expansion of the wall system (16) and a cross-sectional flow cross section for the exhaust gas is formed between the wall system (16) and the housing , Internal combustion engine.

6. A method as claimed in claim 5, wherein the opening (24) of the low pressure exhaust gas recirculation device is disposed in the region of the wall system (16) at the outer surface, or the wall system (16) And a plurality of second wall elements (30) annularly spaced circumferentially spaced apart from one another, said second wall elements (30) having a first wall element (28) , And the trim plate 12 is provided with a first wall element 28 or a second wall element 30 or a first wall element 28 and a second wall element 30 which form an outlet cross- 30. The internal combustion engine as set forth in claim 1, wherein the adjustment device (34) is configured to allow the ends of the first and second drive wheels (30, 30) to be moved radially.

7. An internal combustion engine according to claim 6, characterized in that the wall elements (28, 30) are rotatably supported at the ends forming the inlet cross-section of the wall system (16).

8. A method according to claim 7, characterized in that at least some of the wall elements (28, 30) are supported in a rocker shape so that when the ends of the wall elements (28, 30) forming the outlet cross- The ends of the wall elements (28, 30) forming the inlet cross section are moved radially outward, which is associated with the elastic initial stress of the spring element.

7. An internal combustion engine according to claim 6, characterized in that the wall elements (28, 30) have a U-shaped cross section.

7. A device according to claim 6, characterized in that the adjusting device (34) comprises an adjusting ring (46) having one or more guide grooves (48), the first wall element (28) or the second wall element The first wall element 28 and the second wall element 30 are connected to the ends of the first wall element 28 or the second wall element 30 forming the outlet cross section, Is guided in one or more guide grooves (48) such that the ends of the second wall element (30) are moved radially due to rotation of the adjustment ring (46).