TURBINE FOR AN EXHAUST GAS TURBOCHARGER

Abstract

In a turbine for an exhaust gas turbocharger having a turbine housing including a turbine wheel with blades, each having a leading edge and a trailing edge, an adjusting device is provided controlling the flow to the leading blade edges of the turbine wheel and also a device for controlling the flow from the trailing edges of the turbine wheel blades, both devices are coupled to one another so as to be adjustable by a single actuator.

Description

This is a Continuation-In-Part application of pending international patent application PCT/EP2011/008095 filed Dec. 6, 2011 and claiming the priority of German patent application 10 2011 014 458.7 filed Mar. 19, 2011.

BACKGROUND OF THE INVENTION

The invention relates to a turbine for an exhaust gas turbocharger including a turbine wheel with impeller blades having leading and trailing edges and guiding the flow of exhaust gas through the turbine.

It is known from the series production of internal combustion engines to use exhaust gas turbochargers having a turbine which is drivable by exhaust gas from the internal combustion engine. The turbine may have at least one adjusting device situated, for example, upstream of a turbine wheel of the turbine in the direction of the flow of the exhaust gas, and by means of which flow conditions, in particular upstream from the turbine wheel, may be influenced. Thus, the turbine may be adapted to a plurality of different operating points of the internal combustion engine, so that the turbine, and thus the internal combustion engine, may be operated in a particularly efficient manner, i.e., with low fuel consumption and therefore low CO₂ emissions. The adjusting device thus represents a variability which allows an advantageous thermodynamic adaptation of the turbine to a particular operating point. This variability results in options for influencing the so-called reaction level of the turbine, which represents a primary variable for efficiency-optimized operation.

In addition, it is necessary to provide a certain throughput range of the turbine in order to meet particularly large load and speed range requirements of the internal combustion engine. To also meet in particular requirements at low loads and/or speeds of the internal combustion engines. It is possible, for example, to provide for a high exhaust gas backup level of the turbine, which, however, is accompanied by a low throughput parameter of the turbine.

WO 2006/133838 A1 discloses an exhaust gas turbine in an exhaust gas turbocharger, having a turbine wheel which is rotatably mounted in a housing, to which exhaust gas, which is discharged by the exhaust gas turbine via an outlet channel, is supplied via an inlet duct The exhaust gas turbine has a turbine inlet cross section which is formed in the transition area from the inlet duct to the turbine wheel between two lateral duct walls, and in which a guide vane structure and an axial slide which cooperates with the guide vane structure and is adjustable in the axial direction is situated, one of the guide walls of the turbine inlet passage being displaceable and being formed by the axial slide. The guide vane structure is fixedly mounted to the housing in the turbine inlet cross section, so that the axial slide is situated at the side facing the outlet channel, and the boundary wall of the turbine inlet cross section, which is fixed to the housing and faces away from the outlet channel, is axially flush with the turbine blades of the turbine wheel.

The known turbines which have a corresponding adjusting device have further potential for reducing their installation space requirements, In addition, they have further potential for providing more efficient operation.

It is the principal object of the present invention, therefore to provide a turbine for an exhaust gas turbocharger which requires less installation space and is more efficient in its operation.

SUMMARY OF THE INVENTION

In a turbine for an exhaust gas turbocharger having a turbine housing including a turbine wheel with blades, each having a leading edge and a trailing edge, an adjusting device is provided controlling the flow to the leading blade edges of the turbine wheel and also a device for controlling the flow from the trailing edges of the turbine wheel blades, both devices are coupled to one another so as to be adjustable by a single actuator.

Such a turbine for an exhaust gas turbocharger includes a turbine housing and a turbine wheel. The turbine wheel is accommodated, at least in parts, in the turbine housing and is rotatable about a rotational axis. The turbine wheel has at least one impeller blade with a leading edge, and a trailing edge which turbine wheel is driven by the exhaust gas flowing from the turbine housing over the impeller blade via the leading edge and off from the impeller blade via its trailing edge.

According to the invention, an adjusting device is provided by means of which the trailing edge of the guide blade of the turbine wheel may be fluidly enabled, at least in parts, in a first position, and on the other hand may be at least essentially fluidly blocked in at least one second position of the adjusting device In other words, in a first position of the adjusting device in which the trailing edge is fluidly enabled at least in parts, exhaust gas may flow off a larger length range of the trailing edge than in the second position of the adjusting device, in which the trailing edge is at least essentially fluidly blocked.

The adjusting device of the turbine according to the invention, which is, for example, a radial turbine allows the turbine to be adapted as needed and in a particularly large operating range to a plurality of different operating points of, for example, a unit associated with the turbine, in particular an internal combustion engine or a fuel cell, via the exhaust gas of which the turbine is driven. This is accompanied by a more efficient operation of the turbine and thus of the unit, so that the unit may be operated with low energy consumption. If the unit is an internal combustion engine, for example, this means particularly low fuel consumption and low CO₂ emissions of the internal combustion engine.

In addition, the turbine according to the invention, in which the adjusting device is situated for example downstream of the turbine wheel, requires less installation space, which assists in avoiding and solving packaging problems, in particular in a space-critical area such as an engine compartment of a motor vehicle.

Furthermore, due to the corresponding arrangement and configuration of the adjusting device, the turbine according to the invention may be designed with a particularly low weight, which keeps the weight of the motor vehicle low. This results in more efficient operation of the unit for driving the motor vehicle. In addition, the flow conditions in the turbine wheel outlet area may be set in a particularly advantageous manner by the adjusting device, which is rotatable about the rotational axis, resulting in more efficient operation of the turbine according to the invention.

The adjusting device of the turbine according to the invention provides a turbine wheel outlet variability which has only a small number of parts and thus a low level of complexity, which is accompanied by high functional reliability. This is advantageous for the service life of the adjusting device, and thus, of the overall turbine. In other words, the adjusting device is in particular mechanically reliable and has only low costs.

By means of the adjusting device, a throughput of the turbine is adjustable, in that the trailing edge is fluidly enabled or, on the other hand fluidly blocked, at least in parts. Due to the different positions of the adjusting device, a particularly good throughput range of the turbine may thus be provided, so that the turbine may be adapted to a plurality of different operating points of the unit associated with it.

The turbine and the unit associated with it may thus be operated more efficiently. In low speed and load ranges, a relatively high back-up effect may be set by the adjusting device with only a small throughput parameter, while in high speed and load ranges of the internal combustion engine, a throughput parameter which is higher in comparison may be set with only a small accumulation effect. The turbine also requires less installation space and has a very low weight, since the adjusting device is situated in a manner which optimizes the installation space.

In one advantageous embodiment of the invention, the adjusting device is rotatable about the rotational axis of the turbine wheel, and is situated at least partially in the area around the turbine wheel outlet area. Flow conditions in the turbine wheel outlet area are variably adjustable by means of the adjusting device. This keeps the installation space requirements of the turbine particularly low. In addition, the turbine thus has a high level of robustness against mechanical and/or thermal stresses, which is accompanied by very good functional reliability, even over a long service life.

As a result of the enabling and, on the other hand, blocking of the trailing edge, a contour of the turbine wheel may be varied, and therefore a flow-off surface of the turbine wheel over which exhaust gas which may flow off via the turbine wheel may be variably adjusted and thus adapted to different operating points. Due to this variation in the contour, by means of which the flow-off surface is increased or decreased and trailing edges are thus added or removed, the throughput parameter of the turbine may be adjusted as needed, thus achieving particularly efficient operation of the turbine. This results in an increase in efficiency of the turbine, since the so-called reaction level of the turbine may be influenced in this way.

On account of the adjustability of the throughput parameter, the turbine thus has an optimized operating range due to adapting the reaction level. In addition, this results in turbine efficiency advantages and improved charge pressure build-up due to a compressor, which is associated with, and drivable by, the turbine for compressing air to be supplied to the unit, and also results in corresponding low fuel consumption and reduced CO₂ emissions.

In one advantageous embodiment of the invention, a further adjusting device situated, at least in part, in the turbine wheel inlet area is provided, by means of which flow conditions in the turbine wheel inlet area upstream of the turbine wheel are variably adjustable. A fully variable turbine is thus provided which may be adapted to different operating points in a particularly advantageous manner and in a particularly large operating range. This results in a particularly efficient operation with low energy consumption, in particular low fuel consumption, of the unit associated with the turbine accompanied by low CO₂ emissions.

For example, an effective flow cross section upstream of the turbine wheel in the direction of flow of the exhaust gas through the turbine is adjustable by means of the further adjusting device, so that the accumulation effect as well as the throughput parameter of the turbine according to the invention may also be variably adjusted.

The further adjusting device includes, for example, a blocking element, in particular a tongue, which is rotatable about the rotational axis of the turbine wheel and by means of which the effective flow cross section is adjustable. The blocking element is connected to an adjusting ring, for example, which is rotatable about the rotational axis of the turbine wheel and by means of which the blocking element is movable, in particular rotatable, for variably adjusting the effective flow cross section. The turbine according to the invention is thus designed as a so-called tongue diverler turbine which is adaptable to different operating points in a particularly flexible manner and which has a low level of complexity, which benefits the functional reliability and thus the service life of the turbine.

In another advantageous embodiment of the invention, the first adjusting device and the further adjusting device are coupled to one another and are activatable, in particular movable, by means of an actuator, in particular only one actuator, of the turbine which is shared by the adjusting devices. The coupling of the adjusting devices thus allows only one control element, for example an actuator, in particular an electric motor, to be used for moving the adjusting devices to adjust the effective flow cross section or for enabling or blocking the trailing edge. It may be provided that the adjusting devices are simultaneously movable due to the coupling. Different displacement distances of the adjusting devices may be provided by appropriate gear ratios and/or coupling devices.

Combining the first adjusting device, and thus the variability in the turbine wheel outlet area, with the further adjusting device, and thus the variability in the turbine wheel inlet area, allows full variability of a throughput characteristic and reaction characteristic of the turbine according to the invention, and thus a particularly good option for influencing the efficiency curve. In the turbine according to the invention, this full variability is provided using particularly simple and inexpensive means in the form of the tongue diverter as the further adjusting device, as well as the first adjusting device, so that the turbine has high robustness and reliability.

The adjusting devices are, for example, electrically and/or pneumatically and/or hydraulically and/or mechanically coupled to one another. The electrical coupling has the advantage that a response is made particularly quickly to changing operating points of the unit associated with the turbine, and the adjusting devices may be adjusted in a correspondingly rapid manner. In addition, a particularly inexpensive coupling is thus provided.

The pneumatic and/or hydraulic coupling has the advantage that particularly high actuating forces together with activating forces that are particularly low in comparison may be provided in order to adjust the effective flow cross section and/or to enable or block the trailing edge, i.e., variably adjust the flow conditions in the turbine wheel outlet area.

The mechanical coupling has the advantage of particularly low costs as well as particularly high robustness and reliability, which is conducive to the high functional reliability of the turbine according to the invention, even at high stress levels and over a long service life.

In another particularly advantageous embodiment of the invention, the guide blade of the turbine wheel has an outer contour having at least one length range, extending essentially parallel to the rotational axis, as the leading edge, and having a length range extending essentially radially as the trailing edge, whereby, between the length range extending essentially parallel to the rotational axis and the length range extending essentially radially, at least one further length range is provided as a further trailing edge, and which defines an angle α_K with the rotational axis, where α_K is in a range 20°<α_K<90°. The at least essentially radially extending trailing edge (length range) represents a primary trailing edge which, for example, is at least practically never fluidly blocked, and also not fluidly blockable by the first adjusting device. The further trailing edge (length range) represents a secondary trailing edge which may be fluidly enabled, at least in parts, by means of the first adjusting device, and on the other hand may be at least fluidly blocked. For this purpose, the trailing edge is overlapped or covered, at least in parts, by the first adjusting device, this overlap or cover being variably adjustable in order to enable or block the trailing edge to a greater or lesser extent.

The angle α_K or the corresponding angular range represents a very important option for influencing the optimization of the turbine wheel, since the through flow conditions as well as in particular discharge flow conditions of the turbine wheel can be influenced by the angle α_K. Accordingly, extremely favorable through flow conditions are present in the mentioned angular range, by means of which the turbine wheel allows particularly efficient and efficiency-optimized operation of the turbine, and thus, of the unit associated with the turbine.

It may be provided that the further trailing edge may be fluidly enabled and on the other hand at least essentially fluidly blocked by means of the first adjusting device, in that the trailing edge is more or less overlapped or covered by means of the first adjusting device, whereby, for example, only the further trailing edge, and not also the first trailing edge, may be fluidly enabled, or on the other hand, fluidly blocked. It may likewise be provided that the first trailing edge may also be fluidly enabled, or on the other hand, fluidly blocked by means of the first adjusting device, the further trailing edge advantageously being correspondingly adjustable, i.e., capable of being fluidly enabled, or on the other hand, fluidly blocked, with respect to the first trailing edge, predominantly by means of the first adjusting device.

If the first adjusting device includes a first adjusting element, in particular a first adjusting ring, which is rotationally fixed relative to the turbine housing, and at least one second adjusting element, in particular a second adjusting ring, which is rotatable about the rotational axis relative to the first adjusting element, an option which is particularly uncomplicated, inexpensive, and reliable is provided for adjusting the flow conditions in the turbine wheel outlet area, for example by fluidly blocking or, on the other hand, enabling a flow past the trailing edge.

The first adjusting device has for example an adjustment range, in particular an adjustment angle range, with a first end position and a second end position. In other words, the first adjusting device is movable, in particular rotatable about the rotational axis, in the adjustment range between the end positions. It may be provided that the first adjusting device is movable into the end positions, and also into at least one intermediate position in the adjustment range between the end positions. The first adjusting device is preferably continuously adjustable in the adjustment range, so that a plurality of different positions of the first adjusting device may be provided to be able to adapt the turbine to different operating points in a particularly advantageous manner. It is likewise possible to adjust the first adjusting device in the adjustment range in a stepped manner, which is accompanied by particularly low costs for the turbine.

If the first adjusting device is adjustable in an adjustment range of 20° about the rotational axis, i.e., the first adjusting device has an adjustment angle of 20°, this is advantageous since the turbine may be adapted to different operating points in a particularly simple and cost-effective manner, while at the same time the installation space requirements of the turbine and its costs may be kept low.

Further advantages, features, and particulars of the invention will become apparent from the following description of an exemplary embodiment thereof with reference to the accompanying drawings. The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the figures and/or shown in the figures are usable not only in the particular stated combination, but also in other combinations or alone without departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic illustration of an internal combustion engine having an exhaust gas turbocharger which includes a turbine through which exhaust gas from the internal combustion engine may flow, the turbine having an adjusting device, which is rotatable about a rotational axis of a turbine wheel of the turbine and situated, at least in part, in a turbine wheel outlet area downstream from the turbine wheel, by means of which flow conditions in particular in the turbine wheel outlet area are variably adjustable;

FIG. 2 shows a section of a schematic longitudinal view of the turbine according to FIG. 1; and

FIG. 3 shows a section of a schematic sectional view of the turbine according to FIG. 2 along a sectional line A-B illustrated in FIG. 2.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

FIG. 1 shows an internal combustion engine 10, designed as a reciprocating piston machine, which may be a diesel engine, gasoline engine, diesel-gasoline engine, or some other type of internal combustion engine. The internal combustion engine 10 is used, for example, to drive a motor vehicle, in particular a passenger vehicle. To this end, the internal combustion engine 10 can be supplied with fuel which is delivered to at least one combustion chamber, in particular a cylinder, of the internal combustion engine 10. Air drawn in from the surroundings by the internal combustion engine 10 is also supplied to the combustion chamber of the internal combustion engine 10 as indicated by a directional arrow 12.

The air initially flows through an air filter 16 situated in an intake tract 14 of the internal combustion engine 10 for cleaning the air. Following the air filter 16, the air is conducted via appropriate intake piping to a compressor 20 of an exhaust gas turbocharger 22 situated in the intake tract 14, as indicated by a directional arrow 18 in FIG. 1.

The air is compressed by means of a compressor wheel of the compressor 20, whereby the air is also heated. To increase the degree of compression of the air, a charge air cooler 24 is situated in the intake tract 14 downstream from the compressor 20; the compressed air flows through the charge air cooler, which cools the compressed air before it is ultimately supplied to the at least one combustion chamber of the internal combustion engine 10 via the intake piping. This is represented by a directional arrow 26.

Supplying the compressed air and the fuel to the at least one combustion chamber results in a fuel-air mixture which ignites by auto-ignition, for example, or which is ignited by means of an ignition device and thus combusted. The combustion results in an exhaust gas which flows out of the combustion chamber and into exhaust piping of an exhaust tract 28 of the internal combustion engine 10, as indicated by a directional arrow 30.

The exhaust gas is conducted via the exhaust piping in the exhaust tract 28 to a turbine 32 of the exhaust gas turbocharger 22, the turbine being drivable by the exhaust gas. The turbine 32 includes a turbine housing 76 (FIG. 2) in which a turbine wheel 74 is accommodated so as to be rotatable about a rotational axis. The turbine wheel 74 is connected to a shaft 4 of the exhaust gas turbocharger 22 in a rotationally fixed manner, and may be acted on, and thus driven, by the exhaust gas,

The compressor wheel of the compressor 20 is likewise connected to the shaft 34 in a rotationally fixed manner, so that the compressor wheel and thus the compressor 20 may be driven by the turbine wheel 74, i.e., the turbine 32.

A branch point 36 is situated in the exhaust tract 30, upstream from the turbine 32 in the direction of flow of the exhaust gas through the exhaust tract 28, and is associated with an exhaust gas recirculation device 38. At the branch point 36, an exhaust gas recirculation line 40 of the exhaust gas recirculation device 38 is fluidly connected to the exhaust piping of the exhaust tract 28. On the other hand, the exhaust gas recirculation line 40 is fluidly connected to the intake piping of the intake tract 14 at an inlet point 42. By means of the exhaust gas recirculation device 38, exhaust gas from the exhaust tract 28 is thus recirculatable to the intake tract 14 and is introducible into the intake tract 14. The air flowing through the intake tract 14 may thus be acted on by exhaust gas from the internal combustion engine 10, so that nitrogen oxides and particulate emissions from the internal combustion engine 10 may be kept low.

For setting a quantity of exhaust gas to be recirculated as needed, the exhaust gas recirculation device 38 includes an exhaust gas recirculation valve 44 which is situated in the exhaust gas recirculation line 40 and by means of which a flow cross section, through which exhaust gas to be recirculated flows, is variably adjustable. An exhaust gas recirculation cooler 46 is situated in the exhaust gas recirculation line 40 between the inlet point 42 and the branch point 36, downstream from the exhaust gas recirculation valve 44 in the direction of flow of the exhaust gas through the exhaust gas recirculation line 40; the exhaust gas recirculation cooler cools the exhaust gas to be recirculated. Since the branch point 36 is situated upstream from the turbine 32, high-pressure exhaust gas recirculation is provided by means of which particularly large quantities of exhaust gas are recirculated.

The internal combustion engine 10 includes a regulating device 48 by means of which the internal combustion engine 10 and the exhaust gas recirculation valve 44 can be regulated, as indicated by arrows 50 and 52 in FIG. 1.

The turbine 32 has an adjusting device 54 situated, at least in part, upstream from the turbine wheel 74 in the direction of flow of the exhaust gas through the turbine 32. In addition, the turbine 32 includes an adjusting device 56 situated, at least in part, downstream from the turbine wheel 74 in the direction of flow of the exhaust gas through the turbine 32. Flow conditions upstream and downstream from the turbine wheel 74 are variably adjustable by means of the adjusting devices 54 and 56, so that the turbine 32 may be adapted to a plurality of different operating points of the internal combustion engine 10. In this way the turbine 32 is operable in a particularly effective and efficiency-optimized manner, which is accompanied by efficient operation of the internal combustion engine 10. This results in particularly low fuel consumption, and thus low CO₂ emissions, of the internal combustion engine 10.

As is apparent from FIG. 1, the adjusting devices 54 and 56 are coupled to one another by means of a coupling device 58, so that the adjusting devices 54 and 56 are activatable by means of a single actuator which is shared by the adjusting devices 54 and 56. For this purpose, the coupling device 58 includes an actuating part 60 which is operated by an actuator, for example an electric motor. The actuating part 60 is rotatable by means of the actuator, for example, as indicated by an arrow 62, and/or is translationally movable by means of the actuator, as indicated by a directional arrow 64. A dashed line 66 indicates that the actuator is controlled by the regulating device 48 so that it is able to adapt the turbine 32, as needed, to an existing operating point of the internal combustion engine 10.

After the exhaust gas has passed through the turbine 32 and has been expanded in the turbine, it is further conducted via the exhaust piping to an exhaust after-treatment device 68, situated in the exhaust tract 28, as indicated by a directional arrow 70. The exhaust after-treatment device 68 includes, for example, a catalytic converter, in particular an oxidation catalytic converter, and a particle filter by means of which the exhaust gas is cleaned before it is discharged to the environment, as indicated by a directional arrow 72.

The adjusting device 54 of the turbine 32 is, for example, a so-called tongue diverter which has an adjusting ring that is rotatable about a rotational axis 73. The rotational axis 73 is also associated with the compressor wheel and the turbine wheel 74. In other words, the compressor wheel, the turbine wheel 74, and the shaft 34 rotate about the rotational axis 73 during operation of the exhaust gas turbocharger 22.

Connected to the adjusting ring is at least one so-called tongue which is rotatable about the rotational axis 73 via the adjusting ring, and by means of which an effective flow cross section upstream from the turbine wheel 74 is variably adjustable.

The adjusting device 56 is designed, for example, as a so-called rotary vane, which is explained in conjunction with FIG. 2 and FIG. 3. A wheel outlet cross section of the turbine wheel 74 is variably adjustable by means of the adjusting device 56.

As is apparent from FIG. 2, the adjusting device 56, designed as a rotary vane, includes a first adjusting ring 78 which is rotatable about the rotational axis 73 relative to the turbine housing 76 and relative to the turbine wheel 74. In addition, the adjusting device 56 includes an adjusting ring 80 which is fixed relative to the housing 76.

The turbine wheel 74 has a plurality of impeller blades 82 which are uniformly distributed over the periphery of the turbine wheel 74 in the peripheral direction of the turbine wheel 74, as indicated by a directional arrow 84. The impeller blades 82 have an outer contour 86 which has a first length range 88 extending at least essentially parallel to the rotational axis 73. A leading edge 90 of the impeller blade 82 is formed by the length range 88; the exhaust gas may flow against the guide blade 32 for driving the turbine wheel 74, For this purpose, the exhaust gas is supplied [to the] turbine wheel 74 via an annular nozzle 92.

In addition, the outer contour 86 has a length range 94 which forms a trailing edge 96 of the impeller blade 82. The exhaust gas may flow off from the impeller blades 82 via the trailing edge 96. The length range 94, and thus the trailing edge 96, extends at least essentially in the radial direction of the turbine wheel, as indicated by a directional arrow 98. The length range 94, which extends at least essentially in the radial direction, may, for example, define an angle with the rotational axis 73 which is in a range from equal to or greater than, 80 degrees up to and including 100 degrees.

In the axial direction of the turbine wheel 74, as indicated by a directional arrow 99, a length range 100 is provided between the length ranges 88 and 94, and adjoins the length range 88 and is adjoined by the length range 94 of the impeller blade 82. The length range 100 forms a further trailing edge 102 of the impeller blade 82, via which the exhaust gas may flow off the turbine wheel 74 or the impeller blade 82.

The length range 100, and thus the trailing edge 102, defines, for example, an angle α_K with the rotational axis 73 which, for example, is greater than 20 degrees and less than or at least essentially equal to 90 degrees. Favorable through-flow conditions of the turbine wheel 74 for the exhaust gas are provided in this way.

The adjusting ring 78 includes cover elements 104 by means of which the respective corresponding trailing edges 102 may be fluidly overlapped, in particular completely, and in particular may be completely enabled. For this purpose, the adjusting ring 78 may be rotated about the rotational axis 73, according to a directional arrow 106, into a respective end position. In addition, it is possible to set the adjusting ring 78 in a plurality of intermediate positions between the end positions in order to thus enable the trailing edges 102 of the impeller blades 82, at least in parts, to overlap or cover same in parts. Due to the different positions of the adjusting ring 78, it is possible to set different overflow gas quantities of the exhaust gas which flow off from the turbine wheel 74 or the impeller blades 82 via the trailing edge 102. Variability in a turbine wheel outlet area 108 is thus provided which is combined with variability in a turbine wheel inlet area 110, which is specified by the adjusting device 54.

The turbine 32 is thus designed as a fully variable turbine 32 which may be adapted in a particularly flexible manner to different operating points of the internal combustion engine 10. In particular, the variability provided by the adjusting device 56 in the turbine wheel outlet area 108 is characterized by only very small installation space requirements, so that the overall turbine 32, and thus the overall exhaust gas turbocharger 22, requires only a very small installation space, in particular in the axial direction. In addition, as a result of the adjusting device 56 designed as a rotary vane, the complexity thereof as well as the number of parts, the weight, and the costs may be kept low, which contributes to a high level of functional reliability of the turbine 32.

Figure illustrates one of the end positions of the adjusting ring 78, in which the trailing edges 102 of the rotor blades 82 are completely fluidly enabled. In this end position designed as an open position, the turbine 32 has a maximum throughput parameter.

If the adjusting ring 78 is displaced into the other of the end positions, in which the trailing edges 102 are at least essentially completely covered or overlapped, and thus at least essentially completely fluidly blocked, a minimum throughput parameter of the turbine 32 is provided. The turbine 32 then has a particularly high accumulation effect, which is conducive to efficient operation, in particular at low load and/or speed ranges of the internal combustion engine 10. Providing the high throughput parameter is beneficial for efficient operation of the turbine 32 at high load and/or speed ranges.

As is apparent in particular from FIG. 3, the cover elements 104 are spaced apart from one another in the peripheral direction (directional arrow 84) and are at least essentially uniformly distributed over the periphery of the turbine wheel 74. In this way, a respective through flow channel 112 is formed between the cover elements 104 in the peripheral direction, and exhaust gas may flow through the through flow channel in positions of the adjusting ring 78 in which flowing off of the exhaust gas from the impeller blades 82 via the trailing edges 102 is made possible, at least in parts

The through flow channels 102 have a diffuser-like design, for example, so that they represent diffuser channels. The through flow channels 112 designed as diffuser channels, for example, have a trailing edge 114 in each case which has a very thin design.

Due to the covering or overlapping and enabling the trailing edges 102, flow openings, so to speak, are enabled or fluidly closed, at least in parts, so that the throughput parameter of the turbine 32 may be influenced and the turbine 32 may be adapted to operating points of the internal combustion engine 10 in a particularly efficient manner. In other words, as a result of the rotation of the adjusting ring 78, a contour of the turbine wheel 74 is variably adjusted and trailing edges 102 are added or removed, so that flow-off surfaces are increased or decreased. As a result, the turbine has a particularly high throughput range, so that it may be efficiently be operated in low speed and/or load ranges as well as in high speed and/or load ranges, and also in intermediate speed and/or load ranges.

The adjusting device 56 has nine so-called blocking sectors which are formed by the cover elements 104. The adjusting ring 78 is adjustable in an adjustment angle range of 20 degrees. This means that the adjusting ring may be rotated overall by 20 degrees relative to the adjusting ring 80, corresponding to the directional arrow 84. This allows complete overlapping as well as complete enabling of the trailing edges 102. In the position of complete enabling, a maximum cross-sectional opening of 50% of the projected ring surface area is achieved, as illustrated with reference to FIG. 3. In this position, the turbine 32 has a maximum possible flow cross section over the trailing edges 102.

As indicated in FIG. 2, the stationary adjusting ring 80 has a relatively small thickness so that sector pockets 116 do not constitute excessively large sources of loss for the flow of the exhaust gas via the trailing edges 102.

In this regard, refinements, not illustrated in FIG. 2 and FIG. 3, are possible in which the cover elements 104 or corresponding blocking surfaces of the adjusting ring 78 increasingly submerge into the free sector pockets 116 due to an in particular small axial motion during rotation of the adjusting ring 78, so that interfering edges for gap flows of the trailing edges 102 or of the outer contour 86 are at least essentially avoided in the position in which the trailing edges 102 are completely overlapped.

As is apparent from FIG. 2, the turbine 32, at least in parts, includes no adjusting device such as the adjusting device 54 upstream from the turbine wheel 74 for variably adjusting the flow conditions upstream from the turbine wheel 74. It is understood, however, that an adjusting device such as the adjusting device 54 may be provided to be able to variably adjust the flow conditions at least essentially upstream from the turbine wheel 74.

As is apparent from FIG. 1, the turbine 32 is associated with the internal combustion engine 10. It is understood, however, that the turbine 32 may also be associated with a fuel cell, for example, the turbine 32 or the turbine wheel 74 then being drivable by exhaust gas from the fuel cell, and the turbine 32 then being adaptable to different operating points of the fuel cell in a particularly efficient and flexible manner. In addition, the turbine 32 may be associated with other types of units which emit exhaust gas, and may be drivable by the exhaust gas from these units.

Claims

1. A turbine (32) for an exhaust gas turbocharger (22), having a turbine housing (76), a turbine wheel (74) accommodated in the turbine housing (76) and being rotatable about a rotational axis (73), the turbine wheel having blades (82) each with a leading edge (90) and a trailing edge (96, 102) and being driven by exhaust gas flowing from the turbine housing (76) to the turbine wheel (74) and reaching the turbine wheel blade at the leading edge (90) and leaving the turbine wheel blade via the trailing edge (96, 102), an adjusting device (56) movable between a first position in which the trailing edge (96, 102) of the impeller blade (82) of the turbine wheel is enabled fluidly and a second position in which it is at least essentially fluidly blocked, and a further adjusting device (54) situated in a turbine wheel inlet area (110) for variably adjusting the flow conditions in the turbine wheel inlet area (110) upstream of the turbine wheel (74), the first adjusting device and the second adjusting device (54, 56) being coupled to one another and being operable by means of a single actuator.

2. The turbine (32) according to claim 1, wherein the adjusting device (56) is situated, at least in parts, in a turbine wheel outlet area (108) and is rotatable about the rotational axis (73) of the turbine wheel (74).

3. The turbine (32) according, to claim 1, wherein the adjusting devices (54, 56) are one of electrically, pneumatically, hydraulically and mechanically coupled to one another.

4. The turbine (32) according to claim 1, wherein the second adjusting device (54) is rotatable about the rotational axis (73) of the turbine wheel (74) for variably adjusting the flow conditions in the turbine wheel inlet area (110)

5. The turbine (32) according to claim 1, wherein the turbine wheel blade (82) of the turbine wheel (74) has an outer contour (86) of at least one length range (88), extending essentially parallel to the rotational axis (73), and having as the leading edge (90), and having a length range (94) extending essentially radially as the trailing edge (96), whereby between the length range (88) extending essentially parallel to the rotational axis (73) and the length range (94) extending essentially radially, at least one further length range (100) is provided forming a further trailing edge (102), and defining an angle αK with the rotational axis (73), where αK is in a range 20°<αK≦90°.

6. The turbine (32) according to claim 5, wherein the further trailing edge (102) may be selectively essentially fluidly enabled, or essentially fluidly blocked, by means of the single adjusting device (56).

7. The turbine (32) according to claim 1, wherein the adjusting device (56) includes a first adjusting element (80) which is rotationally fixed relative to the turbine housing (76), and at least one second adjusting element (78) which is rotatable about the rotational axis (73) relative to the first adjusting element (80).

8. The turbine (32) according to claim 1, wherein the adjusting device (56) is adjustable about the rotational axis (73) in an adjustment range of 20 degrees.