EP1201881A2 - Turbocharger - Google Patents

Abstract

The exhaust gas turbo charger, for an internal combustion motor, has a turbine with a turbine wheel (4), a spiral housing and a guide (5) to direct the exhaust gas flow to the wheel. The guide system has at least two groups of jets (11,12) aligned directly at the outer periphery of the turbine wheel. The jets (11) of the first group are positioned at equal angular intervals around the wheel, with further controlled jets (12) between them. The spiral housing is in two flow paths (9,10), with a flow connection between them and the jets, to link the paths separately or together to the motor exhaust.

Description

The invention relates to an exhaust gas turbocharger for an internal combustion engine Combustion according to the preamble of claim 1.

It is known that the performance, consumption and exhaust values of internal combustion engines be improved with internal combustion with exhaust gas turbochargers can. However, it has been found that it is not easy to do so Exhaust gas turbochargers designed so that they are satisfactory in all operating areas Results are achieved. To remedy this disadvantage, turbochargers are with variable turbine geometry have been proposed, in which the Flow cross section in front of the turbine impeller can be changed. Although so that a significant improvement can be achieved is the effect of such Turbocharger especially in the partial load range (low mass throughput at low engine speed) still unsatisfactory. One reason is that due to the adjustable guide vanes a compromise inevitably the exhaust gas energy formation (pressure / speed) when flowing through the narrow Guide vane column must be entered up to the turbine wheel. The axial Clearance of the guide vanes in the turbine housing results in additional losses. Furthermore, The service life of such turbochargers is limited, especially when the turbocharger is used Guide device is a large load of gas forces.

From DE 39 07 504 A an exhaust gas turbine is known which has a double-flow spiral casing having. A flood can be switched off by a flap. Both floods open into a common flow cross-section that extends over the extends over the entire circumference of the impeller. This particularly occurs in Partial load significant losses due to premature relaxation of the exhaust gas flow are caused.

EP 0 196 183 B shows a turbocharger in which the flow cross section can also be changed. In addition to the disadvantages described above here comes the uneven application of the circumferential direction Impeller added, which causes a one-sided mechanical load on the bearing. The same applies to a solution as disclosed in US 4,512,714 A. is.

Furthermore, DE 197 17 559 A describes a turbocharger with two flows are alternately exposed to exhaust gas, with one flood surrounding the other and is connected to it via openings. Such a turbocharger is due the flow losses and the premature expansion of the exhaust gas unsatisfactory efficiency.

DE 42 42 494 C also shows an adjustable flow guide for the Impeller of an exhaust gas turbocharger that can be switched via various floods can be formed, can be flowed to. It can thus be achieved that the Exhaust gas turbocharger is optimally operated in wide areas of the engine map. However, if individual floods are blocked off, the impeller becomes asymmetrical flowed to, which leads to an increased bearing load and a loss of efficiency leads.

The object of the invention is to avoid these disadvantages and an exhaust gas turbocharger to create one in a wide range of operating conditions has good efficiency. In particular, in the low speed range Internal combustion engine to achieve the greatest possible power on the turbine, a quick response and a favorable torque curve to reach. It should be a strength solution and a long lifespan can be achieved.

According to the invention, this is achieved in that the nozzles of a first group are arranged at even angular intervals around the impeller and that between these nozzles, further nozzles are provided which are designed to be controllable are.

The solution according to the invention ensures that in all operating states a centrally symmetrical flow to the impeller is guaranteed, which results in a correspondingly low bearing load, so that a long service life is achieved. The inflow cross-section can optimally match the respective Exhaust gas flow can be adjusted, but always the optimal flow technology Flow conditions up to the turbine wheel inlet are given. In particular all nozzles always show the optimal, i.e. generally minimal Distance to the impeller.

It is preferably provided that the guide device consists of at least two Groups of nozzles exist that are directly on the outer circumference of the impeller are directed, and that the volute is divided into at least two floods each of which is in flow communication with a group of nozzles stands, and that further a switching device is provided to individual or all floods of the volute with the internal combustion engine on the exhaust gas side connect to. In particular, the nozzles are through fixed guide vanes educated. This makes a particularly simple, fluidically advantageous Construction reached. Since the guide device has no moving parts, one is such a solution is particularly robust and in particular for use in commercial vehicles suitable.

Optimal efficiency is achieved when the width of the nozzles is in the axial direction that corresponds to the circumference of the impeller. In this way, the Exhaust gas expansion practically exclusively as a thermodynamic process in the impeller so that no cross-sectional jumps occur.

A particularly good adaptation of the turbocharger to the respective operating condition the internal combustion engine can be achieved in that the first Group of nozzles, the second group and any other groups a different one Have number of nozzles. Alternatively, or in addition, can it can also be provided that the nozzles of the first group, the nozzles of the second Group and the nozzles of any other groups a different width in Have circumferential direction.

A particularly simple construction of the invention is characterized in that that the switching device by a motor-operated Flap is formed.

It has also proven to be advantageous if the width of the nozzles is circumferential at least the circumferential distance of the blades of the impeller equivalent.

Furthermore, it is advantageous if in the partial load range with low mass throughputs electromotive support of the turbine is provided. For example can an electric motor directly into the connection between the impeller and the turbine be integrated.

In a particularly preferred embodiment variant of the invention, that the guide device has a plurality of fixed nozzles, which are immediate are directed to the outer periphery of the impeller, as well as several pivoting guide vanes, which are arranged around the impeller and which in can be brought into a position in which the volute almost exclusively through the fixed nozzles are in flow connection with the impeller. This Solution stands out compared to known turbochargers with variable turbine geometry characterized by the fact that even with a small gas throughput optimal flow conditions are given for the impeller, because the nozzles in terms of distance to the impeller, the flow angle and the cross-sectional area are optimized. This allows the internal combustion engine to operate even at low speeds high turbine speeds and thus high boost pressures can be achieved. With higher gas throughput, the guide vanes are opened to allow larger flow cross-sections to reach.

An optimal flow to the impeller in the lowest area of the gas flow can be achieved when the pivoting vanes are in one position can be brought in which they seal against each other and / or at the fixed nozzles issue. The inflow then takes place exclusively through the nozzles.

It is known that it depends on the number of cylinders of the internal combustion engine The exhaust gases of groups can be favorable for gas dynamic reasons of cylinders separately from each other to the turbocharger. So at Six-cylinder machines Groups of three cylinders with the same ignition intervals can be summarized, or with five-cylinder machines two groups of two cylinders and another group of one cylinder consist. It is therefore preferred if the switching device is in at least one Position each of the floods with a group of cylinders of the internal combustion engine combines. In this way, the gas flows are not only up to the turbocharger but ultimately separated from each other until just before the impeller entry. With low gas throughput, however, the exhaust gas flows of all cylinders are converted into one Flood summarized, since here the highest possible turbine speed is in the foreground.

A further preferred embodiment variant looks downstream of the switching device in the area of a flood a blow-off valve in front of the predetermined pressure in the flood opens. This ensures that additional to the possible power levels of the turbine by switching the individual Floods are given, an additional stage for highest exhaust gas flows is created the blow-off valve, the so-called waste gate, is opened is. Therefore, it is not necessary to set the turbine to the highest possible exhaust gas flow to be designed, so that with a somewhat smaller turbine found the sufficiency can be. This enables an additional improvement in the response behavior and the possibility of a finer gradation of the turbine performance. A particular advantage is that only a partial flow of the exhaust gas is influenced by the waste gate. Due to the strict separation of the exhaust gas flows of the individual floods up to the assigned nozzles, each corresponding Impact sectors of the impeller, e.g. a situation with kick-down achieved that the flood with waste gate through the switching device is not applied, and in the other flood or the other floods higher exhaust gas pressure can be achieved than the opening pressure of the waste gate pretends.

An optimal loading of the turbine is achieved in that preferably the switching device has a predetermined position, in the high Gas throughput the pressure in both floods is approximately the same. Such Position of the switching device can be by a catch or a preprogrammed Setting must be specified. When the blow-off device is closed the switching device is in a central position when there is a high gas throughput, to apply both floods evenly. Once the blow off device, i.e. the waste gate opens, it is advantageous to slightly favor the gas flows to redirect the flood in which the waste gate is located. To this Even with the waste gate open, even application can occur the turbine can be guaranteed.

Fig. 1

einen Längsschnitt durch einen erfindungsgemäßen Abgasturbolader; Fig. 2 schematisch einen Schnitt nach Linie II-II in Fig. 1;

Fig. 3 bis 5

Details von erfindungsgemäßen Abgasturboladern;

Fig. 6

eine Ausführungsvariante der Erfindung in einem Schnitt entsprechend der Fig. 2; und

Fig. 7

eine weitere Ausführungsvariante der Erfindung im Schnitt.

The invention is explained in more detail below on the basis of the embodiment variants shown in the figures. Show it:

Fig. 1

a longitudinal section through an exhaust gas turbocharger according to the invention; Fig. 2 shows schematically a section along line II-II in Fig. 1;

3 to 5

Details of exhaust gas turbochargers according to the invention;

Fig. 6

an embodiment of the invention in a section corresponding to FIG. 2; and

Fig. 7

a further embodiment of the invention in section.

The exhaust gas turbocharger generally has a turbine 1, which also has a shaft 2 is connected to a compressor 3 and drives it. In the turbine 1 is a Impeller 4 is provided, which has a guide device 5, which consists of guide vanes 6 exists, with the exhaust gas of an internal combustion engine, not shown becomes. After flowing through the impeller 4, the exhaust gas flows in one axial opening 7 from. The exhaust gas becomes a guide device via a spiral housing 8 5 guided, in which two floods 9, 10 arranged side by side in the axial direction are separated from each other by a partition 14. The turbine 1 is connected upstream of an adapter 21 which, in addition to the flap 13, has a relief valve 20 records. This relief valve 20 is shown as a flap valve that as mechanically actuated or as electromagnetic actuated by the engine control Valve can be executed. It is also possible in a known way Way to provide mechanical control over the boost pressure, or simply use a pressure relief valve. The gas flow from the blow-off valve 20 opens into an exhaust pipe 22 downstream of the turbine 1.

It can be seen from FIG. 2 that a total of nine stationary guide blades 6 are arranged at uniform angular intervals around the impeller 4, so that 6 nozzles 11, 12 are formed between these guide vanes, which on the Impeller 4 are directed. The nozzles 11 of the first group stand with the first Flood 9 in fluid communication. There are two nozzles between the nozzles 11 12 of another group arranged in flow communication with the second flood 10 stand. In this way, the impeller 4 depending on the operating state the internal combustion engine via three nozzles 11 of the first group, over six Nozzles 12 of the second group or applied to all nine nozzles 11, 12 become. This allows a high speed even with a low exhaust gas flow the impeller 4 and thus a favorable boost pressure and a quick response can be achieved. It is obvious to a person skilled in the art that the control ratio 1: 2: 3 can be changed as required, for example can that between the nozzles 11 of the first group, for example three nozzles 12 of the second group can be arranged. Furthermore, the width of each Nozzles are designed differently in the circumferential direction. It is essential that all guide blades 6 have an optimal gap width s to the outer circumference of the impeller 4.

A motor-driven flap 13 can be seen schematically from FIG. 3, with which the exhaust gas flow in the first flood 9 or in the second flood 10 or in the Middle position in both floods 9, 10 can be steered. 3 is with solid lines show a position of the flap 13 in which the exhaust gas flow into the first flood 9 to act on the first group of nozzles 11 is set. Another position is shown with broken lines, in the the exhaust gas flow into the second flood 10 to act on the second group of Nozzles 12 is directed. The flap 13 can be arranged directly in the housing of the turbine 1 be, also be provided in a special adapter housing that to the flue gas turbocharger according to the invention is flanged or in the exhaust manifold of the internal combustion engine.

In the variant of FIG. 4, the upstream side of the flap 13 is in two Channels 15, 16 divided into different groups of not shown Guide cylinders of the internal combustion engine. In the position shown Flap 13, the two channels 15, 16 are combined in the first flood 9. With a high gas throughput, the channels 15, 16 are separated from one another with the Floods 9, 10 connected, which additionally has a gas dynamic effect double-flow turbine housings can be used.

FIG. 5 essentially corresponds to FIG. 3, but with the flap 13 in is shown in a position in which it is at the highest exhaust gas flow and open Blow-off valve is located. The exhaust gas flow becomes the first flood 9 somewhat throttled and an additional exhaust gas stream redirected to the second flood 10. Downstream of the waste gate, which is not shown in FIG. 5, therefore results approximately a uniform pressure level in both floods 9, 10.

6 shows an embodiment in which the locking body 30 is in the axial direction can be inserted into the first nozzles 11 in order to largely close them. The strength of the engine braking effect can also be continuously adjusted by that the blocking bodies 30 are immersed at different depths in the nozzles 11. An optimal engine braking effect is achieved when the switching device 13 directs the entire exhaust gas flow onto the first nozzles 11 and thus the nozzles 12 switches off the second group. In this way, the relief valve 20 deactivated.

7, like the other design variants, has a Turbine 1, which is connected via a shaft 2 to a compressor, not shown and drives it. An impeller 4 is provided in the turbine 1, that via a guide device 5, which consists of pivotable guide vanes 6, with the exhaust gas of an internal combustion engine, not shown. In the illustrated embodiment, a total of twelve guide blades 6 are provided, arranged in groups of three blades around the impeller 4 are. Nozzles 11 are arranged between the individual groups of guide blades 6, which are formed from fixed guide vanes 6a.

In the position of the pivoting guide vanes drawn with solid lines 6, the volute casing 8 is only connected to the impeller 4 via the nozzles 11 in connection, since the guide blades seal against one another and at the nozzles 11 issue. The impeller 4 is therefore flowed only through the nozzles 11, the radial gap s and the inflow angle are optimized. With higher gas throughput are the pivotable guide vanes 6 simultaneously or one after the other opened, as shown partly by broken lines, to one to provide the corresponding flow cross-section.

The present invention makes it possible, even at low engine speeds and thus a low exhaust gas flow a high turbine speed and thus a good one To achieve responsiveness and optimal charging.

Claims (19)

Exhaust gas turbocharger for an internal combustion engine, with a turbine (1) which has an impeller (4), a volute casing (8) and a guide device (5) to direct the exhaust gas flow onto the impeller (4), which guide device ( 8) consists of at least two groups of nozzles (11, 12) which are directed directly onto the outer circumference of the impeller (4), characterized in that the nozzles (11) of a first group are arranged at uniform angular intervals around the impeller (4) are arranged and that between these nozzles (11) further nozzles (12) are provided which are designed to be controllable. Exhaust gas turbocharger according to claim 1, characterized in that the spiral housing (8) is divided into at least two floods (9, 10), each of which is in flow connection with a respective group of nozzles (11, 12), and in addition a switching device ( 13) is provided in order to connect individual or all flows (9, 10) of the volute casing (8) to the internal combustion engine on the exhaust gas side. Exhaust gas turbocharger according to one of claims 1 or 2, characterized in that the nozzles (11, 12) are formed by stationary guide vanes (6). Exhaust gas turbocharger according to one of claims 1 to 3, characterized in that the width of the nozzles (11, 12) corresponds in the axial direction to that of the impeller (4) on its circumference. Exhaust gas turbocharger according to one of claims 1 to 4, characterized in that a first group of nozzles, a second group and any further groups have a different number of nozzles (11, 12). Exhaust gas turbocharger according to one of claims 1 to 5, characterized in that the nozzles (11) of a first group, the nozzles (12) of a second group and the nozzles of any further groups have a different width in the circumferential direction. Exhaust gas turbocharger according to one of claims 1 to 6, characterized in that the switching device is formed by a motor-operated flap (13). Exhaust gas turbocharger according to one of claims 1 to 7, characterized in that the width of the nozzles (11, 12) corresponds in the circumferential direction at least to the circumferential distance of the blades of the impeller (4). Exhaust gas turbocharger according to one of claims 1 to 8, characterized in that a plurality of pivotable guide vanes (6) are provided which are arranged around the impeller (4) and which can be brought into a position in which the spiral housing (8) is almost exclusively through the fixed nozzles (11) are in flow connection with the impeller (4). Exhaust gas turbocharger according to Claim 9, characterized in that the pivotable guide vanes (6) can be brought into a position in which they bear against one another and / or against the fixed nozzles (11). Exhaust gas turbocharger according to one of claims 9 or 10, characterized in that at least one, preferably three pivotable guide vanes (6) are provided between each two fixed nozzles (11). Exhaust gas turbocharger according to one of claims 9 to 11, characterized in that the pivotable guide vanes (6) can be actuated simultaneously or in a predefinable chronological order. Exhaust gas turbocharger according to one of claims 1 to 12, characterized in that an electromotive support of the turbine (1) is provided in the partial load range with low mass throughputs. Exhaust gas turbocharger according to one of claims 1 to 13, characterized in that the spiral housing (8) is divided into at least two floods (9, 10), each of which is in flow connection with a group of nozzles (11, 12) in each case, by individual or to connect all the floods (9, 10) of the volute (8) to the internal combustion engine on the exhaust gas side and that a blow-off valve (20) is provided downstream of the switching device (13) in the region of a flood (9), which in the case of a predetermined pressure in the Flood (9) opens. Exhaust gas turbocharger according to one of claims 1 to 14, characterized in that two or more passages (9, 10) are provided which are arranged side by side in the axial direction. Exhaust gas turbocharger according to one of claims 1 to 15, characterized in that the switching device (13) has a predetermined position in which the pressure in both floods is approximately the same at high gas throughput. Exhaust gas turbocharger according to one of claims 1 to 16, characterized in that there is further provided an engine braking device which has blocking bodies (30) which can preferably be inserted in a group of nozzles (11) in the axial direction. Exhaust gas turbocharger according to one of claims 1 to 17, characterized in that a two-stage supercharging is provided and a further exhaust gas turbocharger is connected upstream as a high-pressure stage. Exhaust gas turbocharger according to one of claims 1 to 17, characterized in that a two-stage supercharging is provided and a further exhaust gas turbocharger is connected downstream as a low-pressure stage.

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