Abstract:
In a turbine for an exhaust gas turbocharger having a turbine housing with a turbine rotor rotatable supported therein and including spiral channels for directing exhaust gas onto the turbine wheel, at least one annular blocking element is supported between the spiral channels and the turbine wheel so as to be rotatable in the peripheral direction of the turbine wheel and additionally movable in the axial direction of the turbine wheel for a controlling the exhaust gas flow to the turbine wheel between impulse turbine mode when extended into the space between the turbine wheel and the spiral chamber and an accumulation made when retracted, with the gas flow through the turbine wheel or by-passing the turbine wheel being adjustable by rotation of the blocking element.

Description:
This is a Continuation-In-Part application of pending international patent application PCT/EP2011/006093 filed Dec. 6, 2011 and claiming the priority of German patent application 10 2011 010 744.4 filed Feb. 9, 2011. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a turbine for an exhaust gas turbocharger having a spiral channel for supplying exhaust gas to a turbine wheel and being provided with an annular blocking element which surrounds the turbine wheel and is rotatably supported for controlling the admission of exhaust gas to the turbine wheel and also to an exhaust gas turbocharger having such a turbine. 
     DE 25 39 711 A1 discloses a spiral housing for turbomachines, in particular in an exhaust gas turbocharger, having a cross section which is adjustable at least in parts, at least one tongue being provided which is slidingly guided at the radially inner wall of the spiral housing and displaceable in connection with this wall in the peripheral direction. 
     An internal combustion engine for a motor vehicle is known from DE 10 2008 039 085 A1 having an exhaust gas turbocharger which includes a compressor disposed in an intake tract of the internal combustion engine and a turbine in an exhaust tract of the internal combustion engine. The turbine has a turbine housing which includes a spiral channel which is coupled to an exhaust line of the exhaust tract. A turbine wheel is situated within an accommodation space in the turbine housing, and a compressor wheel of the compressor is connected to the turbine wheel in a rotationally fixed manner via a shaft and may be acted on by exhaust gas of the internal combustion engine The turbine includes an adjusting device by means of which a spiral inlet cross section of the spiral channel as well as a nozzle cross section of the spiral channel are jointly adjustable with respect to the accommodation space. 
     To keep the fuel consumption of internal combustion engines, and thus their CO 2  emissions, low, the internal combustion engines are provided with charging devices so that the internal combustion engines are suppliable with compressed air, which by means of the exhaust gas of the internal combustion engine is compressed via a corresponding exhaust gas turbocharger. Thus, the internal combustion engines may be designed according to the so-called downsizing principle, which means that the internal combustion engines have a relatively small volume but are able to provide particularly high power and torque. Thus, the internal combustion engines have very high specific power and torque. As a result, the requirements for the charging devices are continually increasing, in particular with regard to adaptability of the charging devices to different operating points so that efficient operation of the charging devices is achievable. 
     SUMMARY OF THE INVENTION 
     In a turbine for an exhaust gas turbocharger having a turbine housing with a turbine rotor rotatably supported therein and including spiral channels for directing exhaust gas onto the turbine wheel, at least one annular blocking element is supported between the spiral channels and the turbine wheel so as to be rotatable in the peripheral direction of the turbine wheel and additionally movable in the axial direction of the turbine wheel for a controlling the exhaust gas flow to the turbine wheel between impulse turbine mode when extended into the space between the turbine wheel and the spiral chamber and an accumulation made when retracted, with the gas flow through the turbine wheel or by-passing the turbine wheel being adjustable by rotation of the blocking element. 
     Such a turbine for an exhaust gas turbocharger, in particular for an internal combustion engine or a fuel cell, includes at least one turbine housing, having an accommodation space, which includes at least one spiral channel through which exhaust gas may flow. The spiral channel has a flow cross section via which a turbine wheel which is accommodated, at least in parts, in the accommodation space and which is rotatable about a rotational axis may be acted on by the exhaust gas. The turbine also includes at least one blocking element which is rotatable about the rotational axis of the turbine wheel, at least essentially in the peripheral direction of the accommodation space, and by means of which the flow cross section is adjustable. 
     According to the invention, it is provided that the blocking element is additionally movable, in particular displaceable, in the axial direction of the turbine wheel between at least one first position and one second position. This means that the blocking element is not only rotatable relative to the turbine housing in the peripheral direction of the accommodation space, but is also movable, in particular displaceable, relative to the turbine housing in the axial direction of the turbine wheel. This provides for a particularly extensive and flexible adjustment capability of the blocking element, so that the turbine may be adapted to different operating points, in particular to the internal combustion engine associated with it, in a particularly flexible manner according to demand and in a particularly large range. This results in more efficient operation of the turbine according to the invention, at least essentially in the entire characteristic map of the internal combustion engine, which is accompanied by reduced fuel consumption and reduced CO 2  emissions of the internal combustion engine. 
     The blocking element allows the in particular narrowest flow cross section in the direction of flow of the exhaust gas through the turbine housing to be variably set upstream from the turbine wheel, so that the so-called throughput parameter of the turbine as well as its accumulation behavior may be adjusted, and adapted to an existing operating point, in particular of the internal combustion engine. 
     The turbine according to the invention is thus a variable turbine, which in particular due to the wide range of adjustability of the blocking element in the peripheral direction of the accommodation space as well as in the axial direction of the turbine wheel has a very high throughput range, which is accompanied by more efficient operation. The turbine according to the invention is usable in internal combustion engines which are designed as gasoline engines, diesel engines, diesel-gasoline engines, or other types of internal combustion engines. The turbine according to the invention is particularly advantageous for use in gasoline engines, since gasoline engines in particular require a much larger throughput range of the turbine than is the case for diesel engines, for example. The turbine according to the invention is able to meet these requirements for the throughput range, so that the turbine, and thus the internal combustion engine, may be operated in a particularly efficient manner. 
     The turbine according to the invention also has the advantage that it has very high operational reliability, in particular with regard to adjustment characteristics of the blocking element. The blocking element provides relatively uncomplicated, simple, and robust adjustability of the turbine, so that even for particularly demanding criteria, for example for gasoline engines in which exhaust gas temperatures of up to 1050° C. are present, the rotatability in the peripheral direction as well as the axial motion of the blocking element is provided, even over a high service life and under high loads. 
     The turbine according to the invention thus has particularly advantageous thermodynamic behavior, and a high throughput range coefficient of φmax/φmin, which preferably is in a range from equal to or greater than 4.5 up to and including 6. The term φ max  refers to the maximum settable throughput parameter of the turbine according to the invention due to rotation and movement of the blocking element, while φ min  refers to the minimum settable throughput parameter of the turbine according to the invention due to rotation and movement of the blocking element. 
     Furthermore, the turbine according to the invention has proven extremely advantageous due to the fact that only a small number of control elements, referred to as actuators, are provided and necessary, which keeps the application effort for the turbine according to the invention, and thus its costs, low. In addition, the turbine together with the blocking element has only very small installation space requirements and a low weight, which benefits the efficient operation of the turbine and of the internal combustion engine associated with it. 
     In one advantageous embodiment of the invention, in the axial direction the blocking element is movable solely between the first position, in which the blocking element is situated, at least in parts, in a turbine wheel inlet area, and the second position, in which the blocking element is at a distance from, in particular completely remote from, the turbine wheel inlet area with respect to the first position. This means that in the first position, the in particular narrowest flow cross section is adjustable upstream from the turbine wheel by means of the blocking element, the in particular narrowest flow cross section being formed or delimited, for example, in parts by a wall of the spiral channel which is fixed relative to the turbine housing, and in parts by the blocking element which is movable (rotatable and movable in the axial direction) relative to the turbine housing. In the first position, the in particular narrowest flow cross section may be variably set upstream from the turbine wheel by rotating the blocking element, in order to be able to adapt the turbine according to the invention to different operating points of the internal combustion engine in a particularly flexible manner according to demand. 
     In the second position, the blocking element is in particular completely remote from the turbine wheel inlet area, so that the in particular narrowest flow cross section upstream from the turbine wheel is formed or delimited in particular solely by walls of the spiral channel which are fixed relative to the turbine housing. In this way, a particularly high throughput range of the turbine according to the invention together with a very large maximum settable throughput parameter (φ max ) and with a minimum throughput parameter (φ min ) which is particularly small in comparison may be achieved in combination with influencing of an advantageous, appropriate effect characteristic, in particular for customary displacement paths of the corresponding actuator for the requirements of the internal combustion engine. For diesel engine applications, a throughput range coefficient of at least essentially 4 may thus be achieved. For gasoline engine applications, a throughput range coefficient of at least 5 is achievable due to the described movability of the blocking element. The turbine according to the invention may thus be used even for very high exhaust gas mass flows, which occur in particular in gasoline engines, and may ensure efficient operation with low energy consumption. 
     This is achieved in a particularly simple and cost-effective manner, since the blocking element is movable only, i.e., exclusively, in the axial direction between the first position and the second position. This keeps the level of control and regulation effort, and thus the application effort, for the turbine according to the invention low, which is accompanied by low costs. 
     A so-called tongue diverter mode of the turbine according to the invention may be carried out in the first position of the blocking element. In the first position of the blocking element, which is designed as an airfoil-shaped tongue, for example, by rotating the blocking element the flow cross section of the spiral channel may be adjusted according to demand, and set to the existing operating point as well as to a charge pressure requirement of the internal combustion engine. 
     If the turbine has at least two ducts which are fluidly separate from one another, at least in parts, and via which the exhaust gas may be led to the turbine wheel, in the tongue diverter mode a duct separation is provided almost to the turbine wheel. 
     In the second position, the blocking element is situated at a distance, for example, from a nozzle via which the exhaust gas flows against the turbine wheel essentially in the radial direction thereof, so that the exhaust gas does not, and in contrast to the first position, no longer, flows against and around the blocking element. The nozzle is, for example, a ring-shaped inflow channel upstream from the turbine wheel. As a result, the flow cross section is set or settable to be even greater compared to the first position. If the turbine, as previously described, has at least the two ducts, in the second position a fluid connection of the individual ducts may be provided upstream from the turbine wheel. An accumulation charge mode of the turbine may be set due to this connection of the ducts, so that the exhaust gas upstream from the turbine wheel initially is accumulated or collected due to the connection of he ducts, and only then does it flow against the turbine wheel for driving same. 
     At this point it is noted that the turbine housing may have a plurality of spiral channels having a respective flow cross section, at least one blocking element advantageously being associated with each of the flow cross sections, by means of which the respective flow cross section is variably settable in the first position by rotating the corresponding blocking element in the peripheral direction of the accommodation space of the turbine wheel, and in particular about the rotational axis thereof. 
     It may be provided that the turbine includes two ducts, at least two spiral channels as sub-ducts being associated with one duct. This means that this duct is then fluidly connected to the two spiral channels, so that the exhaust gas may flow from the duct into the two spiral channels, the duct upstream from the turbine wheel thus being divided into the two spiral channels. 
     The spiral channels are also referred to as segments, since they allow flow against the turbine wheel over its periphery in the peripheral direction thereof via the individual segments provided by the spiral channels. If the turbine includes multiple spiral channels, i.e., segments, a multisegment turbine is thus provided which allows particularly advantageous flow against the turbine wheel and particularly advantageous charging of the internal combustion engine. 
     In one advantageous embodiment of the invention, the blocking element is connected to an adjusting part, in particular an adjusting ring, which is movable together with the blocking element, by means of which the blocking element is rotatable in the peripheral direction and movable in the axial direction. A bypass channel of the turbine via which exhaust gas may bypass the turbine wheel is fluidly blocked, in particular continuously, by means of the adjusting part in one of the positions, in particular in the first position. In addition, a flow cross section of the bypass channel may be fluidly enabled, at least in parts, in the other of the positions, in particular in the second position, by means of the adjusting part. In other words, the flow cross section in the first position is fluidly blocked, so that exhaust gas does not flow through the bypass channel, and therefore exhaust gas is not able to bypass the turbine wheel without driving the turbine wheel. 
     In the second position, in which the at least one blocking element is in particular completely remote from the nozzle, the flow cross section is enabled or may be enabled, at least in parts, so that in the second position it is possible for exhaust gas to flow through the bypass channel, and thus for this exhaust gas to bypass the turbine wheel without driving it. So-called bypassing of the turbine wheel is thus achieved, so that a particularly large throughput parameter is settable. This is accompanied by the provision of a particularly high throughput range of the turbine according to the invention, which is designed as a radial turbine, for example, so that the turbine is adjustable according to demand at operating points of the internal combustion engine at least essentially in the entire characteristic map of the internal combustion engine. It may be provided that the turbine also has at least two or more bypass channels which in the first position are fluidly blocked, and which in the second position are or may be fluidly enabled, at least in parts. 
     For fluidly blocking or fluidly enabling the at least one bypass channel, i.e., its flow cross section, it may be provided that the adjusting part, in particular the adjusting ring, has an opening which is delimited by walls of the adjusting part. In the first position the flow cross section of the bypass channel is in particular completely covered and thus fluidly blocked by the walls of the adjusting part. For enabling the flow cross section, i.e., the bypass channel, in the second position, the opening in the adjusting part may be moved into alignment, at least in parts, with the flow cross section of the bypass channel, and thus with the bypass channel, so that the exhaust gas may flow through the bypass channel and the adjusting part via its opening. 
     During this bypassing of the turbine wheel, for example exhaust gas is branched off from the spiral channel, and downstream from the turbine wheel is supplied to a turbine wheel outlet area or turbine outlet area positioned in the turbine housing downstream from the turbine wheel. For this purpose, the bypass channel has, for example, an inlet cross section via which the bypass channel opens into the spiral channel. In addition, it may be provided that the bypass channel has an outlet cross section via which the bypass channel opens into the turbine outlet area, at least in parts, downstream from the turbine wheel. The exhaust gas may flow from the spiral channel, via the inlet cross section, into the bypass channel and flow out of the bypass channel via the outlet cross section. 
     The adjusting part, in particular the adjusting ring, is accommodated, at least in parts, in particular completely, in the turbine housing so as to be movable relative thereto, the turbine housing being movable together with the blocking element for moving the blocking element between the first position and the second position as well as moving the blocking element in the axial direction of the turbine wheel. For rotating the blocking element, the adjusting part is rotatable in the peripheral direction of the accommodation space, in particular about the rotational axis of the turbine wheel For this purpose, the adjusting part cooperates, for example, with an actuator, in particular a motor, which is able to rotate the adjusting part. Due to the connection with the blocking element, the rotation of the adjusting part causes the blocking element to correspondingly rotate. This is particularly advantageous when the turbine according to the invention includes a plurality of blocking elements which are then preferably connected to the adjusting part and movable via the adjusting part, i.e., rotatable in the peripheral direction and also movable in the axial direction. Thus, it is only necessary for the adjusting part to cooperate with the actuator and for the adjusting part to be moved, which causes a motion of all blocking elements together with the adjusting part. 
     The flow cross section of the bypass channel is preferably settable in the other of the positions, in particular in the second position, by means of the adjusting part. If the adjusting part is rotated, for example, the flow cross section may be variably set by rotating the adjusting part. It may be provided that the adjusting part (and thus the blocking elements) may be moved, in particular rotated, in the other of the positions, in particular in the second position, between a first rotational position of the adjusting part, provided as an end position of an adjustment angle range of the adjusting part, and a further rotational position, provided as a further end position of the adjustment angle range. In one of these rotational positions the opening in the adjusting part is in alignment, at least in parts, with the flow cross section of the bypass channel, so that exhaust gas may flow through the bypass channel while bypassing the turbine wheel. In contrast, the flow cross section is narrowed, in particular fluidly blocked, in the further rotational position, so that a small volume flow or mass flow of the exhaust gas, or no exhaust gas, is able to flow through the bypass channel. In the first rotational position it may be provided that the flow cross section is completely enabled, so that the flow cross section or the bypass channel experiences no throttling by the adjusting part, and a particularly large quantity of exhaust gas is able to flow through the bypass channel. 
     The adjusting part for setting the flow cross section of the bypass channel is also preferably rotatable into at least one intermediate position between rotational positions designed as end positions, so that the flow cross section of the bypass channel may in particular be set according to demand. The flow cross section may particularly advantageously be set at least essentially in a stepless manner and/or at least essentially continuously between the end positions in the adjustment angle range of the adjusting part, so that by rotating the adjusting part in one rotational direction, the flow cross section, for example starting from a completely fluid blocking of the flow cross section, is successively enabled and thus the flow cross section is successively enlarged until, for example, it is maximally, and in particular completely, enabled. If the adjusting part is rotated, for example, into a second rotational direction opposite from this rotational direction, the flow cross section of the bypass channel, starting from an in particular complete enabling of the flow cross section, is successively narrowed and thus reduced until the flow cross section is completely fluidly blocked, for example, so that exhaust gas is not, or is no longer, able to flow through the bypass channel. 
     This adjustability of the bypass channel provides further adjustability of the turbine for setting its throughput parameter according to demand, which in particular benefits the efficient operation of the turbine according to the invention, and thus the operation of the internal combustion engine with low fuel consumption and low CO 2  emissions. 
     If the adjusting part is rotated in the second position, in which the blocking element is at a distance from the turbine wheel inlet area, this is accompanied by a rotation of the blocking element. However, since the blocking element is at a distance from the turbine wheel inlet area, the rotation of the adjusting part does not result in adjustment of the in particular narrowest flow cross section of the spiral channel upstream from the turbine wheel. 
     For achieving a small adjustment angle range, the bypass channel may particularly advantageously be fluidly blocked or enabled by rotating the adjusting part in a first rotational direction, the first rotational direction of the adjusting part being opposite from a second rotational direction of a subsequent or preceding movement of the blocking element. That is, for example for opening the bypass channel, starting from a bypass channel which is blocked by the adjusting part and a blocking element positioned in the nozzle, initially the blocking element is maximally rotated in a first rotational direction. The blocking element is subsequently axially displaced so that the nozzle is completely open, This operation is followed by a rotation of the adjusting part in a second rotational direction, in particular the second rotational direction being opposite from the first rotational direction, so that a small adjustment angle range is sufficient for achieving a large throughput range coefficient. This allows small displacement paths, which in turn results in less wear. 
     Based on the above-mentioned tongue diverter mode of the turbine according to the invention, it may be provided that the bypass channel, which represents a so-called wastegate of the turbine, is fluidly blocked. In the accumulation charge mode it may be provided that the bypass channel is initially fluidly blocked. If the adjusting part is then appropriately rotated and the flow cross section is fluidly enabled, the turbine wheel is bypassed in the accumulation charge mode, also referred to as accumulation turbine mode, so that the throughput parameter is successively increased by successively enabling the flow cross section of the bypass channel, thus allowing a particularly large maximum throughput parameter to be set. This is accompanied by a particularly large throughput range ratio. 
     In another advantageous embodiment of the invention, a receiving part, in particular a matrix, is provided in which the blocking element is accommodated, at least in parts, at least in one of the positions, in particular in the second position, the receiving part, in particular the matrix, being fixed in the axial direction and rotatable in the peripheral direction of the accommodation space. On the one hand, the matrix allows the blocking element to be accommodated in the second position, thus minimizing or avoiding vortex formation or other types of power losses, so that the exhaust gas may flow against the turbine wheel via the nozzle, for example, in a particularly flow-optimized manner. On the other hand, the matrix, i.e., the receiving part, allows rotation of the blocking element in particular into the second position, and thus the rotation of the adjusting part, so that the flow cross section of the bypass channel may be variably set. The receiving part is fixed in the axial direction, so that the blocking element moves relative to the matrix during a motion from the first position into the second position. 
     The nozzle or a supply channel via which the exhaust gas is supplied to the turbine wheel is delimited in parts by a wall which extends at least essentially radially with respect to the turbine wheel. In addition, the nozzle or the supply channel may be delimited, at least in parts, by an at least essentially radially extending wall of the blocking element, so that undesirable vortex formation or other types of power losses does/do not result in the turbine wheel inlet area, and [exhaust gas] may flow against the turbine wheel, in particular in the second position of the blocking element, in a flow-optimized manner. Leakage flow of the exhaust gas is also avoided in this way. 
     In another advantageous embodiment of the invention, the turbine has at least two ducts which are fluidly separate from one another, at least in parts, and via which the turbine wheel may be acted on by exhaust gas. In one of the positions, in particular in the first position, the turbine is operable in a pulse charging mode, also referred to as pulse turbine mode, so that pulse charging of the internal combustion engine is made possible. In the other of the positions, in particular in the second position, the turbine is operable in an accumulation turbine mode, so that accumulation charging of the internal combustion engine is made possible. In one of the positions, in particular in the first position, the ducts are fluidly separate from one another until shortly, in particular directly, upstream from the turbine wheel, resulting in pulse turbine mode. If the blocking element is moved in the axial direction into the other of the positions, in particular into the second position, the ducts are fluidly connected to one another upstream from the turbine wheel, thus forming a collection chamber, so to speak, in which the exhaust gas upstream from the turbine wheel is initially collected and accumulated, and only then flows against the turbine wheel. Exhaust gas may overflow from one of the ducts or from corresponding segments of this duct into the second duct or into corresponding segments of the second duct. The turbine according to the invention thus has particularly high flexibility with regard to adaptability to different operating points of the internal combustion engine in order to achieve efficient operation which is low in fuel consumption and CO 2  emissions. 
     In another advantageous embodiment, it is provided that in pulse turbine mode, a throughput parameter of the turbine which increases with rotation is settable by rotating the blocking element in a rotational direction, and in accumulation turbine mode, a throughput parameter of the turbine which decreases with rotation is settable by rotating the blocking element in this rotational direction. 
     If the blocking element is in the first position, for example, and the blocking element is rotated in this rotational direction, for example the flow cross section of the spiral channel is thus successively enabled, so that the throughput parameter of the turbine successively increases. 
     If the blocking element is in the second position and the blocking element, and thus the adjusting part, is rotated in this rotational direction, for example the flow cross section of the bypass channel is thus successively decreased, starting from a fluid enabling of the bypass channel, so that the throughput parameter of the turbine according to the invention is decreased upon rotation in this rotational direction, since an increasingly lower mass flow or volume flow of the exhaust gas is able to flow through the bypass channel, until the bypass channel is, for example, completely fluidly blocked. Conversely, this means that in the second position of the blocking element, rotating the blocking element, and thus the adjusting part, in a rotational direction opposite from the above-mentioned rotational direction likewise results in a throughput parameter of the turbine which increases with rotation, since during the rotation of the blocking element and of the adjusting part in this further rotational direction which is opposite from the first rotational direction, the flow cross section of the bypass channel is successively enabled, and therefore an increasingly greater mass flow or volume flow of the exhaust gas is able to flow through the bypass channel, resulting in a throughput parameter of the turbine according to the invention which becomes increasingly larger. In this way, the turbine is particularly advantageously settable, and adaptable to different operating points of the internal combustion engine. 
     The bypass channel is preferably integrated at least in parts, in particular completely, into the turbine housing. This means that the bypass channel extends within the turbine housing at least in parts, in particular completely, and is delimited by corresponding walls of the turbine housing. 
     The second aspect of the invention relates to an exhaust gas turbocharger, in particular for an internal combustion engine or for a fuel cell, having a turbine according to the invention. Advantageous embodiments of the first aspect of the invention are to be regarded as advantageous embodiments of the second aspect of the invention, and vice versa. For moving the blocking element, and thus the adjusting part, from the first position into the second position, it may be provided that the blocking element and the adjusting part are moved, in particular displaced, in the direction of a turbine outlet of the turbine in the axial direction of the turbine wheel. Correspondingly, when moving from the second position into the first position, the blocking element and the adjusting part are moved, in particular displaced, in the opposite direction, this direction pointing, for example, toward a bearing housing of the exhaust gas turbocharger in which a shaft of the exhaust gas turbocharger is rotatably mounted. 
     This shaft on the one hand is connected in a rotationally fixed manner to the turbine wheel, and on the other hand is connected in a rotationally fixed manner to a compressor wheel of a compressor of the exhaust gas turbocharger, so that the compressor wheel, and thus the compressor, may be driven by the turbine wheel via the shaft due to the turbine wheel being acted on by the exhaust gas. It is thus possible to utilize the energy contained in the exhaust gas of the internal combustion engine or of the fuel cell in order to efficiently compress air to be supplied to the internal combustion engine or to the fuel cell, so that particularly high specific power and torque of the internal combustion engine or of the fuel cell may be provided. 
     Further advantages, features, and particulars of the invention will become more readily apparent from the following description of a preferred exemplary embodiment thereof with reference to the accompanying drawings. The features and feature combinations mentioned above, 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 cross-sectional view of a turbine according to the invention of an exhaust gas turbocharger for an internal combustion engine, which includes an adjusting device which is rotatable, at least partially, in the peripheral direction of a turbine wheel of the turbine about a rotational axis thereof, and which is displaceable between two positions in the axial direction of the turbine wheel, with the adjusting device in a first position of the positions; 
         FIG. 2  shows a schematic cross-sectional view of the turbine according to  FIG. 1 , with the adjusting device in the second of the positions; 
         FIG. 3  shows a schematic cross-sectional view of the turbine according to  FIGS. 1 and 2 , with bypass channels of the turbine fluidly enabled, so that exhaust gas may bypass the turbine wheel without driving the turbine wheel; 
         FIG. 4  shows part of a schematic longitudinal sectional view of another embodiment of the turbine according to  FIGS. 1 through 3 , with the adjusting device in the first position; 
         FIG. 5  shows part of a schematic longitudinal sectional view of the turbine according to  FIG. 4 , with the adjusting device in the second position; 
         FIG. 6  shows part of a schematic longitudinal sectional view of the turbine according to  FIGS. 4 and 5 , with the adjusting device in the first position; 
         FIG. 7  shows part of a schematic cross-sectional view of the turbine according to  FIG. 6  along a sectional line A-A in  FIG. 6 ; 
         FIG. 8  shows part of a schematic longitudinal sectional view of the turbine according to  FIGS. 4 through 7 , with the adjusting device in the second position and a bypass channel of the turbine fluidly blocked; 
         FIG. 9  shows part of a schematic cross-sectional view of the turbine according to  FIG. 8  along a sectional line A-A in  FIG. 8 ; 
         FIG. 10  shows part of a schematic longitudinal sectional view of the turbine position and the bypass channel fluidly enabled; 
         FIG. 11  shows part of a schematic cross-sectional view of the turbine according to  FIGS. 4 through 9  with the adjusting device in the second according to  FIG. 10  along a sectional line A-A in  FIG. 10 ; 
         FIGS. 12   a  to  12   d  each show part of a schematic cross-sectional view of the turbine according to  FIGS. 4 through 11 , with the adjusting device in the second position and with a different rotational position of the adjusting device in the second position being illustrated in each of  FIGS. 12   a  to  12   d;  and 
         FIG. 13  shows a respective curve of a throughput characteristic value of the turbine according to  FIGS. 1 through 12  over an angle of rotation of the tongue diverter in the first position and in the second position of the adjusting device. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 1  shows a turbine  10  for an exhaust gas turbocharger of an internal combustion engine which is designed as a reciprocating piston machine, for example, and as a gasoline engine, for example. The turbine  10  includes a turbine housing  12  which has a first duct  16  and a second duct  14 . Exhaust gas from the internal combustion engine is able to flow through the first duct  16  and the second duct  14 . If the internal combustion engine has four cylinders, for example, in which combustion processes take place, exhaust gas from two of the cylinders, for example the first and the fourth cylinders, is associated with the first duct  16  and flows through this first duct  16 , whereas exhaust gas from the other cylinders, for example the second and the third cylinders, is associated with the second duct  14  and flows through the second duct  14 . The turbine housing  12  also has four spiral channels, a first spiral channel  18 , a second spiral channel  20 , a third spiral channel  22 , and a fourth spiral channel  24 , via which a turbine wheel  26 , which is accommodated in an accommodation space  28  formed by the turbine housing  12  and which is rotatable about a rotational axis  30 , may be acted on by exhaust gas. For this purpose, the first spiral channel  18  and the second spiral channel through the first duct  16  is able to overflow into the first spiral channel  18  and the second spiral channel  20 . In other words, the first duct  16  is divided into the first spiral channel  18  and the second spiral channel  20  downstream from an inlet cross section A E1  of the first duct  16  and upstream from the turbine wheel  26 , so that the first duct  16  upstream from the first spiral channel  18  and the second spiral channel  20  functions as a supply and collection channel for the first spiral channel  18  and the second spiral channel  20 . On the other hand, the first spiral channel  18  and the second spiral channel  20  open into the accommodation space  28 , so that the exhaust gas is able to flow from the first spiral channel  18  and the second spiral channel  20  into the accommodation space  28 , and to flow radially inwardly against the turbine wheel. The turbine  10  is thus a radial turbine. 
     The same applies for the second duct  14  and the third spiral channel  22  and fourth spiral channel  24 . On the one hand, the third spiral channel  22  and the fourth spiral channel  24  are fluidly connected to the second duct  14 , so that the duct is divided into the third spiral channel  22  and the fourth spiral channel  24  downstream from an inlet cross section A E2  and upstream from the turbine wheel  26 . Thus, the second duct  14  upstream from the third spiral channel  22  and the fourth spiral channel  24  also functions as a supply and collection channel for these two spiral channels. On the other hand, the third spiral channel  22  and the fourth spiral channel  24  open into the accommodation space  28  and are thus fluidly connected thereto, so that exhaust gas flowing through the second duct  14  and the third spiral channel  22  and the fourth spiral channel  24  flows into the accommodation space  28 , and is thus able to flow against and drive the turbine wheel  26  at least essentially in the radial inward direction. 
     As is apparent from  FIG. 1 , outlet cross sections A of the spiral channels  18 ,  20 ,  22 ,  24  are uniformly distributed one behind the other over the periphery of the turbine wheel  26  in the peripheral direction of the turbine wheel  26 , indicated by a directional arrow  34 . The outlet cross sections A are situated at the same level in the axial direction of the turbine wheel  26 , as indicated by a directional arrow  36 . 
     To be able to flexibly adapt the turbine  10  to different operating points of the internal combustion engine according to demand, in particular in light of a pronounced non-steady-state characteristic of the gasoline engine, and thus to be able to at least essentially always efficiently operate in the entire characteristic map of the internal combustion engine, the turbine  10  includes an adjusting device  38  in the form of a tongue diverter. The device  38  includes airfoil-shaped blocking elements  40  which are referred to as tongues, each blocking element  40  being associated with one of the spiral channels  18 ,  20 ,  22 ,  24  and a respective turbine inlet cross section A. 
     The blocking elements  40  are fixedly connected to an adjusting ring  42 , not illustrated in  FIG. 1  but illustrated in  FIG. 4 . In addition, the blocking elements  40  and the adjusting ring  42  are rotatable about the rotational axis  30  of the turbine wheel  26  in the peripheral direction of the turbine wheel  26  (directional arrow  34 ). A narrowest flow cross section in the direction of flow of the exhaust gas through the spiral channels  18 ,  20 ,  22 ,  24  may be variably set upstream from the turbine wheel  26  by rotating the blocking elements  40  via the adjusting ring  42 , which is rotatable together with the blocking elements  40 , since the adjusting device  38  and the adjusting ring  42 , and the blocking elements  40  are rotatable at least essentially continuously and in a stepless manner in an adjustment angle range of at least essentially 60°, for example. 
     In  FIG. 1  the blocking elements  40  are in a rotational position of the adjustment angle range, provided as a first end position, in which a minimally adjustable flow cross section A min  of the spiral channels  18 ,  20 ,  22 ,  24  is set. If the blocking elements  40  and the adjusting ring  42  are successively rotated in the peripheral direction, starting from this first end position, in the direction of a directional arrow  44 , this is accompanied by a successive enlargement of the narrowest flow cross section of the spiral channels  18 ,  20 ,  22 ,  24  upstream from the turbine wheel  26 . 
     This setting of the narrowest flow cross section is possible in a first position of the adjusting device  38  relative to the axial direction of the turbine wheel  26 . In this first position of the adjusting device  38 , the narrowest flow cross section on the one hand is delimited by walls  46  which are fixed relative to the turbine housing  12  and which delimit the spiral channels  18 ,  20 ,  22 ,  24 , at least in parts, and [on the other hand] is delimited in parts by the blocking elements  40 , In the first axial position of the adjusting device  38 , exhaust gas flowing through the spiral channels  18 ,  20 ,  22 ,  24  flows against and around the blocking elements  40 . 
     The turbine  10  also includes bypass channels  48  which are fluidly connected to the second duct  14  and the first duct  16  at branch points  50 . Exhaust gas is able to flow from the ducts  14 ,  16  into the bypass channels  48  at the branch points  50 , as the result of which exhaust gas is branched from the ducts  14 ,  16  upstream from the turbine wheel  26 . The bypass channels  48  allow exhaust gas to bypass the turbine wheel  26  without acting on, and driving, the turbine wheel. For this purpose, the bypass channels  48  open into a turbine wheel outlet area  54  ( FIG. 4 ) downstream from the turbine wheel  26  at inlet points  52  ( FIG. 4 ). 
     Valve devices  56  are situated in the bypass channels  48 , by means of which a flow cross section Au of the bypass channels  48  is variably settable. The valve devices  56  are able to fluidly block the flow cross sections A U  so that no exhaust gas may flow through the bypass channels  48 . Likewise, the valve devices  56  allow the flow cross sections A u  to be fluidly enabled, at least in parts, so that exhaust gas can flow through the bypass channels  48  and thus bypass the turbine wheel  26 . As shown in  FIG. 1 , the valve devices  56  are in a position which blocks the bypass channels  48  so that no exhaust gas is able to flow through the bypass channels  48 . 
     In the first position of the adjusting device  38 , in which the narrowest flow cross section upstream from the turbine wheel  26  is variably settable by means of the blocking elements  40 , a so-called tongue diverter mode of the turbine  10  is provided. A throughput parameter, which is also referred to as a throughput characteristic value φ, may thus be variably set by rotating the adjusting ring  42  and the adjusting [sic; blocking] elements  40 . 
       FIG. 2  shows the turbine  10  with the adjusting device  38  set in a second position in the axial direction of the turbine wheel  26 , as indicated by the directional arrow  36 . The adjusting device  38  is movable, in particular displaceable, solely between the first position and the second position in the axial direction of the turbine wheel  26 . In the second position the blocking elements  40  are at a distance from a turbine wheel inlet area  58 , so that they no longer protrude into a ring nozzle  60  ( FIG. 4 ) above the turbine wheel  26  as in the first position, and in comparison to the first position, exhaust gas no longer flows, or flows only in a very small area, against or around the blocking elements. Although the adjusting ring  42  and the blocking elements  40  are also rotatable about the rotational axis  30  in the peripheral direction in the second position, this rotation, does not, or no longer, cause(s) a change in the narrowest flow cross section upstream from the turbine wheel  26 . The narrowest flow cross section is denoted by reference character AF in  FIG. 2 , and is delimited by the walls  46  which are fixed relative to the turbine housing  12 , and is no longer delimited in parts by the blocking elements  40 . 
     In the second position of the adjusting device  38 , a so-called backpressure or accumulation turbine mode of the turbine  10  is achieved in which the internal combustion engine is charged by accumulation charging. The ducts  14 ,  16 , i.e., the spiral channels  18 ,  20 ,  22 ,  24 , now are no longer fluidly separate from one another until directly upstream from the turbine wheel  26 , as in the first position of the adjusting device  38 , but instead are fluidly connected to one another in the turbine wheel inlet area  58  upstream from the turbine wheel  26 . In other words, the second duct  14  is in direct fluid connection with the first duct  16  above the turbine wheel  26 . Exhaust gas may thus flow from the second duct  14 , i.e., the third spiral channel  22  and the fourth spiral channel  24 , of which segments are illustrated, into the first duct  16 , i.e., the first spiral channel  18  and the second spiral channel  20 , of which segments are likewise illustrated, and vice versa. This flow of the exhaust gas is indicated by directional arrows  62  in  FIG. 2 . 
     The turbine  10  according to  FIG. 3  is likewise operated in accumulation turbine mode, in which the ducts  14 ,  16  are fluidly connected to one another. In contrast to an impulse turbine mode according to  FIG. 2 , however, the valve devices  56  are open, so that the bypass channels are open. Thus, exhaust gas can flow from the ducts  14 ,  16  into the bypass channels  48 , and bypass the turbine wheel  26  without driving it. 
     The bypass channels  48  are advantageously integrated at least in parts, in particular completely, into the turbine housing  12 , and extend within the turbine housing  12 , which keeps the installation space requirements of the turbine  10  small. 
     The throughput parameter of the turbine  10  may be increased by displacing the adjusting device  38  from the first position shown in  FIG. 1  into the second position shown in  FIGS. 2 and 3 . If the bypass channels  48  are additionally fluidly enabled, as illustrated in  FIG. 3 , this is accompanied by a further increase in the throughput parameter (throughput characteristic value φ) of the turbine  10 . In combination with the setting of the narrowest flow cross section by the blocking elements  40  in the first position of the adjusting device  38 , the turbine  10  thus has a very high throughput range with a very high throughput coefficient φ max /φ min , where φ max  denotes the largest possible settable throughput characteristic value and φ min  denotes the smallest possible settable throughput characteristic value of the turbine  10 . 
     The smallest possible settable throughput characteristic value φ min  is set, for example, when the bypass channels  48  are fluidly blocked by means of the valve devices  56 , so that no exhaust gas can flow through the bypass channels  48 , and when the adjusting ring  42  and the blocking elements  40  are in the first end position shown in  FIG. 1 . 
     Starting from this first end position, in the first position of the adjusting device  38  the blocking elements  40  and the adjusting ring  42  are rotatable into a rotational position which is provided as a further end position, resulting in a larger cross sectional setting compared to the narrowest flow cross section A min . This cross section is then the largest possible setting of the narrowest flow cross section upstream from the turbine wheel  26  in the first position of the adjusting device  38 . In this end position, the turbine  10  has a larger throughput parameter compared to the first end position. 
     However, this throughput parameter may be increased even further. The largest possible settable throughput parameter of the turbine  10  is set, for example, when the adjusting device  38  is in its second position and the bypass channels  48  are maximally enabled by means of the valve devices  56 , for example by fully opening the valves of the bypass channels  48 . This is shown with reference to  FIG. 3 . 
       FIG. 4  shows an alternative embodiment of the turbine  10  according to  FIGS. 1 through 3  in the impulse turbine mode, with the bypass channel  48  fluidly blocked and with exhaust gas unable to flow through from the duct  14 , for example. 
     As is apparent from  FIG. 4 , the adjusting ring  42  and the blocking elements  40  are formed together as one piece. The adjusting device  38 , referred to as a tongue diverter, is guided in the axial direction on a contour sleeve  64  of the turbine  10 , as indicated by the directional arrow  36 . The contour sleeve  64  is designed as a separate part with respect to the turbine housing  12 , and delimits an inner contour in the turbine wheel outlet area  54 , so that after the exhaust gas acts on and drives the turbine wheel  26 , it may flow away from the turbine wheel in a flow-optimized manner. The contour sleeve  64  is centered in the turbine housing  12 . 
       FIG. 4  schematically illustrates an actuating part  66  via which the adjusting device  38  may be axially displaced solely between the first position and the second position. In addition,  FIG. 4  illustrates a further actuating part  68  via which the adjusting device  38  may be rotated about the rotational axis  30  in the peripheral direction of the turbine wheel  26 , as indicated by a directional arrow  70  in  FIG. 4 . 
     In addition, a matrix  72  is provided which likewise is rotatable together with the adjusting ring  42  and the blocking element  40  relative to the turbine housing  12 , about the rotational axis  30  in the peripheral direction. However, in the axial direction the matrix  42  is fixed relative to the turbine housing  12 . The matrix  72  has openings  74  which correspond in each case to the blocking elements  40  and in which the blocking elements  40  may be accommodated, in particular in the second position. The matrix  72  also has a wall  76 , facing the ring nozzle  60 , which delimits the ring nozzle in parts in the axial direction. 
     In the second position illustrated in  FIG. 5 , for example, the ring nozzle  60  is also delimited in the axial direction by an end face-side wall  78  of the blocking element  40  or blocking elements  40 . Thus, although the exhaust gas which flows through the ring nozzle  60  flows, at least in parts, against the blocking elements  40  in the second position, the exhaust gas does not flow around the blocking elements as in the first position, and the blocking elements are completely remote from the ring nozzle  60 . 
     The contour sleeve  64  has a first opening  80  which corresponds to the bypass channel  48  in the turbine housing  12 . However, an overflow of exhaust gas, which flows into the bypass channel  48 , into the first opening  80  is prevented due to the fact that a wall  82  of the adjusting ring  42  fluidly blocks the bypass channel  48 . 
     Depending on the position of the adjusting device  38  in the axial direction and the angle of rotation of the adjusting ring  42 , the bypass channel  48  is fluidly enabled, at least in parts, or in contrast is in particular completely fluidly blocked, so that bypassing the turbine wheel  26  via the bypass channel  48  and the first opening  80  is made possible or prevented, respectively. 
     For this purpose, the adjusting ring  42  likewise has a second opening  84  which is delimited by the wall  82 . If the adjusting device  38  is moved into the second position in the axial direction and rotated into a corresponding rotational position in the adjustment angle range, the second opening  84  may be moved, at least in parts, into alignment with the bypass channel  48  and with the first opening  80  in the contour sleeve  64 , so that an overflow of exhaust gas from the bypass channel  48  via the second opening  84  into the first opening  80  and from the first opening into the turbine wheel outlet area  54  is made possible. As a result, exhaust gas can flow into the turbine wheel outlet area  54  at the inlet point  52 . Also, the valve functionality of variably setting the flow cross section Au of the bypass channel  48  is integrated into the adjusting ring  42  of the adjusting device  38 . 
     For moving the adjusting device  38  from the first position shown in  FIG. 4  into the second position shown in  FIG. 5 , for example, the adjusting device  48  is axially displaced in the direction of a turbine outlet  86  of the turbine  10 , as indicated by a directional arrow  88 . For moving the adjusting device  38  from the second position into the first position, the adjusting device  38  is displaced in the axial direction toward a bearing housing  90  of the exhaust gas turbocharger, as indicated by a directional arrow  92 , 
       FIG. 5  shows the turbine  10  according to  FIG. 4 , with the adjusting device  38  in the second position and the bypass channel  48  or the bypass channels  48  fluidly enabled. This means that the exhaust gas flowing through the duct  14  partially flows against the turbine wheel  26  and drives same, as indicated by a directional arrow  94 . A portion of the exhaust gas also flows through the bypass channel  48 , the second opening  84 , and the first opening  80  into the turbine wheel outlet area  54 , as indicated by a directional arrow  96 . 
     The flow cross section A U  of the bypass channel  48  may be variably set by rotating the adjusting device  38  and the adjusting ring  42 , and thus the blocking elements  40 , into the second position of the adjusting device  38  shown in  FIG. 5 . 
       FIGS. 6 and 7  show once again that in the first position of the adjusting device  38  (of the tongue diverter), the bypass channel  48  is always fluidly blocked, and cannot be enabled, even only in parts, not even by rotating the adjusting ring  42  and the blocking elements  40 . In other words, the bypass channel  48  in the tongue diverter mode of the turbine  10  is always fluidly blocked, and also cannot be enabled. 
       FIGS. 8 and 9  show the turbine  10  with the adjusting device  38  in the second position, in which the bypass channel  48  is fluidly blocked but may also be fluidly enabled, at least in parts, in order to bypass the turbine wheel. As is apparent from  FIGS. 8 and 9  in conjunction with  FIGS. 10 and 11  the opening  84  in the adjusting ring  42  may be moved in the direction of a directional arrow  98  toward the bypass channel  48  and the first opening  80 , and aligned, in at least in parts, in particular completely, with the bypass channel  48  and the first opening  80 , by rotating the adjusting ring in the peripheral direction (directional arrow  34 ), as illustrated with reference to  FIGS. 10 and 11 . 
     As is likewise apparent from  FIGS. 8 through 11 , the first opening  80  and the bypass channel  48  are at least essentially in flush alignment with one another, so that when the second opening  84  is completely aligned with the first opening  80  and the bypass channel  48 , at least essentially no interfering edges are present for the exhaust gas flowing through the bypass channel  48 , the second opening  84 , and the first opening  80 . In addition to the complete fluid blocking of the bypass channel  48  and the complete fluid enabling thereof shown in  FIGS. 8 and 9 , the adjusting ring, and thus the second opening  84 , may be rotated into intermediate positions, so that the second opening  84  is in alignment with the first opening  80  and the bypass channel  48  only in parts, and the bypass channel  48  and the first opening  80  are overlapped in parts by the wall of the adjusting ring  42 . This is illustrated with reference to  FIGS. 12   a - d.    
     According to illustration  12   a,  the turbine  10  is in its tongue diverter mode, with the adjusting device  38  in its first axial position, The bypass channel  48  is always fluidly blocked. The tongue diverter mode is accompanied by a pulse turbine mode of the turbine  10  in which the turbine  10  is operable in a pulse charging mode. 
       FIG. 12   b  shows the turbine  10  in its accumulation turbine mode, in which the turbine  10  is operated in an accumulation charge mode and the adjusting device  38  is in its second axial position, However, the bypass channel  48  is fluidly blocked by the adjusting ring  42 , and there is no bypassing of the turbine wheel  26 . 
       FIG. 12   c  shows the turbine  10  in its accumulation turbine mode, with the bypass channel  48  fluidly enabled in parts by an appropriate setting of the adjusting ring  42  as a result of the second opening  84  being in alignment, in parts, with the first opening  80  and the bypass channel  48 . This results in a flow cross section A U  of the bypass channel  48  which is larger compared to the fluid blocking of the bypass channel  48 , but smaller compared to a cornplete fluid enabling of the bypass channel  48 . 
     According to  FIG. 12   d , the turbine  10  is in its accumulation turbine mode, in which the adjusting device  38  is set in the second axial position. The bypass channel  48  is now completely fluidly enabled, so that a maximum settable quantity of exhaust gas is branched from the duct  14  and bypasses the turbine wheel  26 . 
       FIG. 13  shows a diagram  100  in which the adjustment angle range β of the adjusting device  38 , and thus of the blocking elements  40  and of the adjusting ring  42 , is illustrated on the abscissa  102 . The adjustment angle range β is delimited on the one hand by a first rotational position βmin, which represents an end position of the adjusting device  38  in the adjustment angle range β. On the other hand, the adjustment angle range β is delimited by a second rotational position β max,  which represents a further end position of the adjusting device  38  in the adjustment angle range β. In other words, the adjusting device  38  is rotatable in the peripheral direction between the rotational positions β min  and β max , whereby also at least practically any rotational position of the adjustment angle range β between the end positions is settable. 
     The throughput characteristic value φ of the turbine  10  is illustrated on the ordinate  104  of the diagram  100 . The smallest possible throughput characteristic value φ min  and the largest possible throughput characteristic value φ max  may be set by displacing the adjusting device  38  in the axial direction between the first position and the second position, and by rotating the adjusting device  38  within the adjustment angle range β. 
     When the turbine  10  is in its tongue diverter mode, i.e., with the adjusting device  38  displaced into the first position and the bypass channel  48  or the bypass channels  48  fluidly blocked, this results in a curve  106  of the throughput characteristic value φ illustrated in the diagram  100 . Starting from a small rotational position, a small angle of rotation, of the adjusting device  38  toward a comparatively larger rotational position or angle of rotation of the adjusting device  38 , the flow cross section (neck cross section) of the spiral channels  18 ,  20 ,  22 ,  24 , and thus the throughput characteristic value φ, successively increases. In other words, an increase in the angle of rotation is accompanied by an increase of the throughput characteristic value φ, with the bypass channel  48  always being closed. For the rotational position β max , i.e., this maximum angle of rotation of the adjusting device  38  for a fluidly closed bypass channel  48 , the maximum possible narrowest flow cross section is set upstream from the turbine wheel  26 , so that in the first axial position of the adjusting device  38  a maximum throughput characteristic value φ ZS  relative to the first position is provided. 
     On this basis, the throughput characteristic value φ may be further increased by axially displacing the tongue diverter (the adjusting device  38 ) in the direction of the turbine outlet  86 , so that the blocking elements  40  are remote from the ring nozzle  60 . If the bypass channel  48  or the bypass channels  48  is/are still fluidly blocked in this state (second axial position of the adjusting device  38 ), a throughput parameter φ ST  is provided which is larger than the throughput characteristic value φ ZS , with the turbine  10  in its accumulation turbine mode. If the rotational position is once again decreased, starting from the maximum rotational position β max  of the adjusting device  38 , with an increasingly smaller rotational position or increasingly smaller rotational angle of the adjusting device  38 , the bypass channel  48  or the bypass channels  48  is/are progressively enabled, resulting in an increasingly larger flow cross section A U  of the bypass channels  48 . This is accompanied by a further increase in the throughput characteristic value φ until ultimately, at the minimum rotational position β min , the bypass channel  48  or the bypass channels  48  is/are maximally fluidly enabled and the maximum possible throughput characteristic value φ max  of the turbine  10  is set. A range  108  in which the accumulation turbine mode of the turbine  10  is present is particularly apparent from the diagram  100 . Also particularly apparent from the diagram  100  is a further range  110  in which the tongue diverter mode or the pulse turbine mode of the turbine  10  is present. 
     The throughput characteristic value φ is decreased, starting from the maximum possible maximal throughput characteristic value φ max , in a manner analogous to that described above. The bypass channel  48  or the bypass channels  48  is/are initially successively closed and fluidly blocked by increasing the rotational position, i.e., the angle of rotation, of the adjusting device  38 , and the adjusting device  38  is subsequently displaced in the axial direction toward the bearing housing, and the throughput characteristic value φ is reduced by decreasing the rotational position, i.e., the angle of rotation, until ultimately the smallest possible throughput characteristic value φ min  is set at the smallest possible rotational angle. 
     For an adjustment angle range β or rotational angle range of the adjusting device  38 , which has a maximum value of 60°, for example, which is limited by the operating principle, this operating strategy allows a particularly large throughput range coefficient φ max /φ min . 
     Likewise, a large throughput range coefficient φ max /φ min  could also be achieved by initially rotating the blocking element  40  in a first rotational direction and subsequently enabling the nozzle  60  due to an axial motion, followed by the adjusting part  42  enabling the bypass channel  48  due to a rotational motion in a second rotational direction which, however, corresponds to the first rotational direction.