WO2009043487A1

WO2009043487A1 - Multi-stage supercharging group, multi-stage supercharging device, and supercharging system

Info

Publication number: WO2009043487A1
Application number: PCT/EP2008/007856
Authority: WO
Inventors: Joachim Huster; Georg Ruetz; Jürgen Wegner; Rolf Müller; Rainer Lutz
Original assignee: Behr Gmbh & Co. Kg; Mtu Friedrichshafen Gmbh
Priority date: 2007-09-27
Filing date: 2008-09-19
Publication date: 2009-04-09
Also published as: DE102007046667A1

Abstract

The invention relates to a multi-stage supercharging group (10, 10', 10') for an internal combustion engine for charging the internal combustion engine with a fluid, particularly an exhaust gas, comprising at least one high-pressure turbine (1) and a low-pressure turbine (2) disposed downstream of the high-pressure turbine (1), wherein a fluid outlet (1.1) of the high-pressure turbine (1) is fluidically connected to a fluid inlet (2.1) of the low-pressure turbine (2) and an admixture supply line (3, 15, 17) is provided for a bypass fluid (13). In order to fluidically improve the flow behavior between the fluid outlet (1.1) of the high-pressure turbine (1) and the fluid inlet (2.1) of the low-pressure turbine (2) and thus improve the efficiency of the supercharging group (10, 10', 10') while reducing flow losses, the invention provides for the admixture supply line (3, 15, 17) to be disposed between the fluid outlet (1.1) of the high-pressure turbine (1) and the fluid inlet (2.1) of the low-pressure turbine (2) and for the high-pressure turbine (1) to be configured in the form of a radial turbine and for the low-pressure turbine (2) to be configured in the form of an axial turbine. An optimization of installation space is also achieved in that a contact path (5) is configured between the fluid outlet (1.1) of the high-pressure turbine (1) and the fluid inlet (2.1) of the low-pressure turbine (2) in a comparably space-saving manner, or said contact path may be omitted.

Description

Multi-stage charging group, Multi-stage charging device and

charging system

The invention relates to a multi-stage Aufladegruppe for an internal combustion engine for impinging with a fluid of the internal combustion engine at least comprising a high-pressure turbine and the high-pressure turbine downstream downstream low-pressure turbine, wherein a fluid outlet cler high-pressure turbine with a fluid inlet of the low-pressure turbine is fluidly connected and a Zumischzuführung is provided for a bypass fluid , The invention further relates to a multi-stage charging device for an internal combustion engine having at least two turbochargers arranged in series with a multi-stage charging group. Furthermore, the invention relates to a charging system.

An initially mentioned two-stage charging group proves to be a comparatively powerful option in comparison with a single-stage charging group. However, it has been shown that - for example, in a realization of the Aufladegruppe means of two radial turbines - comparatively much space is claimed, although basically the arrangement of two radial turbines is fluidically advantageous. Between the high-pressure turbine and the low-pressure turbine, an arrangement of a mixing feed, which is designed as a downstream outlet of a bypass line for bypassing the high-pressure turbine, may be provided. EP 1 710 415 A1 discloses a multistage charging group of the type initially mentioned, in which fluid flow from a fluid outlet of the high-pressure turbine, on the one hand, and a bypass fluid from an admix supply, on the other hand, are supplied separately and independently of one another to the fluid inlet of the low-pressure turbine, where appropriate, a guide element can be provided separately.

Such an embodiment has proven to be relatively expensive and is still in need of improvement.

It is desirable to have a fluid-technically improved connection of the admixing feed while nevertheless making space-saving design of the multistage recharging group.

At this point, the invention is based, whose task is to provide a multi-stage Aufladegruppe the aforementioned type and a multi-stage supercharger and a charging system in which a Zumischzuführung is fluidly connected in an improved manner and can be realized comparatively space-saving.

Regarding the multistage Aufladegruppe the object is achieved by the invention with a Aufladegruppe of the type mentioned, in accordance with the invention the Zumischzuführung between the fluid outlet of the high-pressure turbine and the fluid inlet of the low-pressure turbine is arranged and the high-pressure turbine in the form of a radial turbine and the low-pressure turbine in the form of an axial turbine is formed.

The invention is based on the consideration that in the proposed combination of a radial High-pressure turbine and a low-pressure axial turbine can realize a particularly space-saving multi-stage Aufladegruppe, which also allows the possibility of a particularly space-saving and technically advantageous connection of Zumischzuführung. In addition, it has been recognized that the admixing supply can be used in a particularly advantageous manner for a fluidically advantageous design of the area between the fluid outlet of the high-pressure turbine and the fluid inlet of the low-pressure turbine. The invention is based on the consideration that a swirling flow, as usually occurs at the outlet of a radial turbine, and / or the admixture of a fluid in a conventional mixing feed for a bypass fluid can lead to flow disturbances and this optionally to a reduction of the efficiency , in particular the axial turbine, can lead. Nevertheless, according to the proposed concept, the invention surprisingly assumes that the admixing feed can be utilized to a particularly advantageous improvement in the flow guidance between the outlet of the high-pressure turbine and the inlet of the low-pressure turbine and can be accommodated in a space-saving manner.

Advantageous developments of the invention can be found in the dependent claims and specify in particular advantageous ways to realize the above-described concept within the scope of the problem and with regard to further advantages.

Preferably, a calming section is arranged between the fluid outlet of the high-pressure turbine and the fluid inlet of the low-pressure turbine, and the admixing feed is arranged in the region of the calming section. This has the advantage that an additional space for the Zumischzuführung can be omitted. It has also been found that in this case a fluid bypass can also be realized in a practically space-neutral manner in the case of a charging system that is still to be explained. Preferably, the fluid outlet of the high pressure turbine and the fluid inlet of the low pressure turbine are axially formed and axially fluidly connected. This allows a fluidically particularly advantageous design of the Aufladegruppe under particularly expedient arrangement of a calming section for attaching the Zumischzuführung. In particular, it has proved to be advantageous to arrange the high-pressure turbine and the low-pressure turbine facing one another on an axis, which can be used to a particularly compact design of the Aufladegruppe.

The low-pressure turbine is preferably upstream upstream of a flow guiding and / or settling element, in particular arranged in the region of a calming section. In particular, the Strömungsleit- and / or reassurance element may have the Zumischzuführung.

In a particularly preferred first variant of this development, the admixing feed can be formed in the form of a pitot tube.

In a particularly preferred second variant of this development, the admixing feed can be formed in the form of an annular space with one or more radially distributed outlets or gaps around the calming section.

The aforementioned variants of a flow-guiding and / or calming element in combination with the admixing feed, preferably in the region of a calming section, according to the concept of the invention allows a hitherto unknown compact realization of a multi-stage recharging group with advantageously minimized space and advantageously optimized flow conditions - despite the comparatively unfavorable flow problem with a combination of a radial and axial turbine. In addition, it has proven to be uncritical with regard to the installation space situation to also provide flow guidance and / or settling elements for further improvement of the flow, which have no admixing feed, for example a guide blade, a nozzle ring or a grid structure.

The invention leads to a multi-stage charging device for an internal combustion engine for applying a fluid of the internal combustion engine, in particular an exhaust gas with at least two turbochargers arranged in series, comprising the multistage charging group according to the above-described concept of the invention or an illustrated embodiment and an associated multi-stage series of Verdichtem.

In particular, it is provided that an air outlet of the compressor of a first turbocharger is fluidly connected to the air inlet of the compressor of a second turbocharger.

Preferably, the high pressure turbine and the low pressure turbine are each drive connected to a compressor. It has been found that in the combination provided according to the concept of the invention

Radial turbine and an axial turbine, the at least two exhaust gas turbochargers arranged in series can be arranged on an axis. This leads to the previously explained, particularly space-saving realization of the charging device.

The concept of the invention also leads to a supercharging system, in particular an exhaust gas recirculation system and charge air supply system, for an internal combustion engine for the application of a fluid. The charging system has an exhaust gas recirculation, a charge air intake, and at least one heat exchanger and a charging group of the type described above and / or a charging device of the type described above on. A heat exchanger is preferably formed in the form of an exhaust gas heat exchanger and / or a charge air heat exchanger.

The multistage charging group is preferably arranged downstream of a fluid outlet of the internal combustion engine for acting on the fluid of the internal combustion engine. In particular, in the supercharging system, a fluid bypass, preferably a bypass which is regulated, for example, by means of a throttle valve, is provided, which opens downstream into the admixing feed.

Embodiments of the invention will now be described below with reference to the drawing. This is not necessarily to scale the embodiments, but the drawing, where appropriate for explanation, executed in a schematized and / or slightly distorted form. With regard to additions to the teachings directly recognizable from the drawing reference is made to the relevant prior art. It should be noted that various modifications and changes may be made in the form and detail of an embodiment without departing from the general idea of the invention. The features disclosed in the description, the drawings and the claims features of the invention may be essential both individually and in any combination for the development of the invention. In addition, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiments shown and described below or limited to an article which would be limited in comparison with the subject matter claimed in the claims. For the given design ranges, even values within the limits are to be disclosed as limit values and can be used and claimed as desired. In detail, the drawing shows in:

Fig. 1: a first embodiment of a multi-stage Aufladegruppe for an internal combustion engine for applying to a fluid of the internal combustion engine according to the concept of the invention, which is still in need of improvement;

2 shows a particularly preferred embodiment of a multistage charging group according to a first variant of the invention;

3 shows a particularly preferred embodiment of a multistage charging group according to a second variant of the invention;

A charging system has an internal combustion engine downstream downstream exhaust gas recirculation system, which is acted upon by an exhaust gas. For this purpose, a high-pressure turbine downstream of the exhaust gas outlet side of an internal combustion engine, the exhaust gas outlet is exhaust-connected to an exhaust gas inlet of the low-pressure turbine. Upstream of the high-pressure turbine branches off an exhaust gas bypass, which - for example via a throttle valve or a control valve of another type - can be used in a controlled manner for fluidic bypassing of the high pressure turbine under direct supply of an engine exhaust gas outlet side exhaust gas to the low pressure turbine. For this purpose, the exhaust gas bypass is fluidly connected to a Zumischzuführung for the bypass exhaust. According to the concept of the invention, the admixing feed is arranged between the exhaust gas outlet of the high-pressure turbine and the exhaust gas inlet of the low-pressure turbine. The exiting the high-pressure turbine exhaust gas is provided for supply to the exhaust gas inlet of the low-pressure turbine. The high-pressure turbine and the low-pressure turbine are each drive-connected to a compressor. With the interposition of a respective charge air heat exchanger, the compressors are part of a charge air supply system arranged upstream of an engine inlet.

The above arrangement of a high pressure turbine 1 and a low pressure turbine 2 is shown in detail in FIG. According to the concept of the invention, in the embodiment of a charging group 10 shown in FIG. 1, it is provided that the high-pressure turbine 1 is in the form of a radial turbine and the low-pressure turbine 2 is in the form of an axial turbine. The low-pressure turbine 2 is presently shown with a rotor 2.2 and attached turbine blades 2.3 and vanes 2.4. The high-pressure turbine 1 is shown here with an arranged on an axis 1.2 impeller 1.3.

In the present case, the exhaust gas outlet-side exhaust gas 11 is fed to the high-pressure turbine 1 and fed via the exhaust gas outlet 1.1 of the high-pressure turbine via a settling section 5 to the fluid inlet 2.1 of the axial turbine 2. In the area of the calming section 5, an admixing feed 3 for a bypass exhaust gas 13 present in an exhaust gas bypass 7 is arranged. The invention has recognized that the flow guidance between the high-pressure turbine 1 and the low-pressure turbine 2 according to the embodiment shown in FIG. 1 is not yet ideal. Reason is the partially swirling flow 12 at the output 1.1 of the high-pressure turbine formed as a radial turbine 1 and possibly caused by flow separation 14 flow disturbances 16 in the Zumischzuführung 3. This can lead to a reduction in the efficiency of the low-pressure turbine 2. In the further FIGS. 2 and 3, the same reference numerals are used for the same parts or parts of the same function.

In order to improve the flow behavior in the region of the calming section 5 between the radial turbine 1 and the axial turbine 2, according to the embodiment of a charging group 10 'of the first variant, a flow guiding and calming element in the form of a pitot tube combined with an admixing feed 15 is provided. By pitot tube, it is possible in the context of the first variant - as well as by similarly acting other, not shown Zumischzuführungen 15 - a waste stream 13 coaxially in the flow 12 of the calming section 5 on the output side of the high-pressure turbine 1 introduce. As a result, the illustrated in Fig. 1 disturbances 16 of the flow 12, for example, a flow separation 14, avoided and in addition equalization of the flow 12, for example, while inhibiting a twist propagation through the projecting into the flow 12 Pitot tube.

Fig. 3 shows a particularly preferred embodiment of a Aufladegruppe 10 "according to a second variant of the invention, wherein the

Zumischzuführung 17 as an annular space with radially distributed outlets 19 or

Columns formed around the calming section 5 around. This ensures that the bypass exhaust gas 13 can be admitted in a particularly advantageous manner to an edge region of the calming section 5 and thus the flow 12 can be supplied. The edge area near the

Outlet 19 occupies - due to its total circumference arrangement - a comparatively large flow space and the bypass exhaust gas is thus supplied under reduced pressure conditions, resulting in an advantageously reduced influence on the flow 12. An inlet of the bypass exhaust gas 13, which is made transverse to the flow 12 - as in FIG. 1 - is largely avoided since this is practically pressure-adapted in the

Edge region of the flow 12 rises. On a modified for Fig. 2 Way is also a comparatively trouble-minimizing supply of the bypass exhaust gas 13 via the admixing 17 allows.

In addition, not shown Strömungsleit- and / or reassurance elements such as vanes or a nozzle ring or a lattice structure and other such, not explained in detail here

Means for homogenizing and / or calming a flow 12 im

Be arranged region of the calming section 5, in order to realize in combination or alternatively to the embodiments of Fig. 2 and Fig. 3 - for example in an embodiment of Fig. 1 - a particularly space-saving and fluidically advantageous Zumischzuführung.

In summary, the invention is based on a multi-stage Aufladegruppe 10, 10 ', 10 "for an internal combustion engine for impinging with a fluid of the internal combustion engine, in particular an exhaust gas, comprising at least one high-pressure turbine 1 and one of the high-pressure turbine 1 downstream of the downstream low-pressure turbine 2, wherein a fluid outlet 1.1 of the high-pressure turbine 1 is fluid-connected to a fluid inlet 2.1 of the low-pressure turbine 2 and an admixing feed 3, 15, 17 is provided for a bypass fluid 13. To improve the flow behavior between the fluid outlet 1.1 of the high-pressure turbine 1 and the fluid inlet 2.1 of the low-pressure turbine 2 and thus to improve the efficiency of the Aufladegruppe 10, 10 ', 10 "while reducing flow losses, the invention provides that the Zumischzuführung 3, 15, 17 angeord between the fluid outlet 1.1 of the high-pressure turbine 1 and the fluid inlet 2.1 of the low-pressure turbine 2 is net and the high-pressure turbine 1 is formed in the form of a radial turbine and the low-pressure turbine 2 in the form of an axial turbine. It is also achieved a space optimization that a calming section 5 between the fluid outlet 1.1 of the high-pressure turbine 1 and the fluid inlet 2.1 of the low-pressure turbine 2 is designed comparatively space-saving or can be omitted.

Claims

Patent claims

1. Multi-stage Aufladegruppe (10, 10 ', 10 ") for an internal combustion engine for acting on a fluid of the internal combustion engine, in particular an exhaust gas, at least comprising a high-pressure turbine (1) and one of the high-pressure turbine (1) downstream fluid-downstream

Low-pressure turbine (2), wherein a fluid outlet (1.1) of the high-pressure turbine (1) with a fluid inlet (2.1) of the low-pressure turbine (2) is fluidly connected and a Zumischzuführung (3, 15, 17) is provided for a bypass fluid (13) characterized in that the

Zumischzuführung (3, 15, 17) between the fluid outlet (1.1) of the high pressure turbine (1) and the fluid inlet (2.1) of the low pressure turbine (2) is arranged and the high pressure turbine (1) in the form of a radial turbine and the low pressure turbine (2) in the form an axial turbine is formed.

2. Aufladegruppe according to claim 1, characterized in that a calming section between the fluid outlet (1.9) of the high-pressure turbine (1) and the fluid inlet (2.1) of the low-pressure turbine (2) is arranged and the Zumischzuführung

(3, 15, 17) is arranged in the region of a calming section (5).

3. Aufladegruppe according to claim 1 or 2, characterized in that the fluid outlet (1.1) of the high-pressure turbine (1) and the fluid inlet (2.1) of the low-pressure turbine (2) are axially formed and axially fluid-connected.

4. Aufladegruppe according to one of claims 1 to 3, characterized in that the high-pressure turbine (1) and the low-pressure turbine (2) are arranged opposite one another on an axis.

5. Aufladegruppe according to one of claims 1 to 4, characterized in that the low-pressure turbine (2) fluid upstream a Strömungsleit- and / or

Calming element is connected upstream, in particular in the region of a calming section (5) is arranged.

6. Aufladegruppe according to one of claims 1 to 5, characterized in that a Strömungsleit- and / or

Calming the Zumischzuführung (3, 15, 17).

7. Aufladegruppe according to one of claims 1 to 6, characterized in that a Strömungsleit- and / or reassurance element in the form of one or more of the elements selected from the group consisting of: vane, nozzle ring, grid structure, Pitot tube, radial gap; is formed.

8. Multistage charging device for an internal combustion engine for acting on a fluid of the internal combustion engine, in particular an exhaust gas, with at least two turbochargers arranged in series, comprising the multi-stage Aufladegruppe (10, 10 ', 10 ") according to one of claims 1 to 7 and one of these associated multi-stage series of compressors, in particular, an air outlet of the compressor of a first

Turbocharger is fluidly connected to the air inlet of the compressor of a second turbocharger.

9. A charging device according to claim 7, characterized in that the high-pressure turbine (1) and the low-pressure turbine (2) is in each case drive-connected to a compressor.

10. A charging device according to claim 7, characterized in that the at least two exhaust gas turbochargers arranged in series are arranged on an axis.

11. Aufladesystem, in particular exhaust gas recirculation system and

Charge air supply system, for an internal combustion engine for impinging with a fluid, comprising an exhaust gas recirculation, a charge air intake, at least one heat exchanger, in particular an exhaust gas heat exchanger and / or a charge air heat exchanger, and a

Charging group according to one of claims 1 to 7 and / or a charging device according to one of claims 8 to 10.

12. Charging system according to claim 11, characterized in that the multi-stage Aufladegruppe is arranged downstream of a fluid outlet of the internal combustion engine for acting on the fluid of the internal combustion engine.

13. Charging system according to claim 11 or 12, characterized by a fluid bypass, in particular one with the

Zumischzuführung connected fluid bypass (7).