WO2017050931A1

WO2017050931A1 - Turbine having a ceramic turbine rotor

Info

Publication number: WO2017050931A1
Application number: PCT/EP2016/072601
Authority: WO
Inventors: Maximilian Wutzow
Original assignee: Mp-Engineering Gmbh
Priority date: 2015-09-22
Filing date: 2016-09-22
Publication date: 2017-03-30
Also published as: EP3353383A1; DE102015116019A1

Abstract

The invention relates to a rotor unit (1) for a turbine, in particular a turbocharger, and to a method for producing said rotor unit. The rotor unit comprises a turbine rotor (2) produced from ceramic and a shaft (3) produced from metal, wherein the shaft has a hollow-cylinder segment (31), wherein the turbine rotor has a turbine wheel (26) and a cylinder segment (21), which is arranged in the hollow-cylinder segment and is fastened with respect thereto, wherein the rotor unit extends in an axial direction from the turbine side (A) of the rotor unit, which is formed by the turbine rotor, to the working side (B) of the rotor unit, which is formed by the shaft. On the working side of the rotor unit, the rotor unit has an external thread (32) for screwing a nut (8) on and a fastening device (33), which is accessible from the working side and is integrated in the shaft and is designed to fasten the rotor unit form the working side while the nut is being screwed on, wherein the fastening device has, in particular, a length in the axial direction that is at least as great the diameter of the external thread of the shaft.

Description

Turbine with ceramic turbine rotor

The invention relates to a rotor for a turbine, in particular for a turbocharger, according to the preamble of claim 1 and a turbine with such a rotor and method for producing such a rotor and such a turbine.

The invention relates to a rotor which is suitable for use in a turbine. The runner is thus to

Realization of such a turbine suitable. The rotor comprises a turbine wheel and a shaft fixed against rotation on the turbine wheel. In the realization of a turbine, a working element is pushed onto the shaft of the rotor and fixed thereto. The basic principle of each turbine consists in that it has the turbine wheel on its turbine side and the working element on its working side, wherein the turbine wheel and the working element are connected to one another in a rotationally fixed manner via the shaft. The turbine is arranged as intended to a gas flow, that the

Gas flow is passed over the turbine wheel. The turbine wheel is designed to be rotated by the gas flow and the working element via the shaft

drives. For example, radial turbines are known in which the Turbine is designed so that the gas flow to the

Turbine wheel is to be supplied in the radial direction and exits the turbine wheel in the axial direction for driving the turbine. For example, axial turbines are known in which the turbine wheel is designed so that the gas flow is to be directed in the axial direction of the turbine wheel for driving the turbine wheel. There are also radial-axial turbines are known in which the turbine wheel is designed so that for driving the turbine, the gas flow is to be directed in the radial direction of the turbine wheel and exits the turbine wheel with a significant axial component, wherein the turbine wheel by both the radial gas flow as well as by the axial component of the outflowing gas flow is driven. The axial direction refers to the axis about which the turbine wheel is rotatably mounted. The working element is often designed as a compressor wheel, can be compressed by the air, for example

Intake air that is supplied to a motor. However, there are also turbines such as turboprops or

Power generation turbines are known in which the

Working element as a propeller or rotor of a

Power generator may be formed.

For example, the turbine can be considered a turbocharger

be educated. In a turbocharger that is

Working element designed as a compressor wheel. Turbochargers are used to increase the efficiency of internal combustion engines, for example in internal combustion engines of

Motor vehicles, aircraft or other machinery drives. In most cases, such turbochargers are as a radial turbine

educated. Turbine wheel and compressor wheel are connected by a shaft. The turbocharger will

intended so relative to the engine arranged that

Exhaust gases are directed from the engine to the turbine wheel and drive the turbine wheel to a rotation. Accordingly, the compressor wheel connected to the turbine wheel rotates, thereby compressing the intake air supplied to the engine. By its basic principle, the turbocharger thus uses the energy contained in the engine exhaust gases by being converted by the turbine wheel into rotational energy, with which the compressor then improves the air supply to the engine and thus the efficiency / performance of the engine.

Generic turbines have a body group comprising a housing and a rotatably mounted to the housing running gear. The running gear includes the runner and the

Working element, wherein rotor and working element are rotationally connected to each other. The runner includes shaft and turbine wheel. Generic turbochargers have such a body group, a turbine housing and a compressor housing. The turbine housing is on the turbine side of the

Hull group arranged and adapted to direct the exhaust gases flowing from the engine to the turbine wheel to ensure the most efficient drive of the

Turbine wheel through the exhaust gases. The compressor housing is on the working side, also called the compressor side, the

Hull group arranged and trained by the

Compressor wheel compressed air as efficiently as possible to supply the engine. Generic runners have in their use in

Turbochargers or other turbines high speeds, for example, at large diameters, z. B. of about 80 mm, speeds of over 50,000 revolutions per minute,

for example, with small diameters, z. B. of about 30 mm, speeds over 300.00 revolutions per minute. Therefore, the permanent guarantee of a very good storage of the running gear to the housing of the body group of a turbine required. In addition, for the best possible response is desirable that the runner

has the lowest possible moment of inertia. In addition, runners must be designed so that the extremely high gas temperatures, often well over 800 ° C, which rest against the turbine wheel, cause no damage to the turbine wheel. Furthermore, generic runners and

Generic turbines always construct against the background of a series production, creating special

Requirements are placed on the simplicity of manufacture and assembly.

Conventional runners and conventional turbines become

at least not all described to them

Sufficiently adequate requirements. Although turbines are known, for example, whose rotor is a shaft made of steel and a turbine wheel of a

high temperature resistant metal alloy, such as

for example, a filing date as Inconel alloy (eg Inconel 713C) or an alloy known as MAR alloy. This can effectively prevent damage to the turbine by hot gas streams. However, such high temperature resistant

Alloys a high density, which is detrimental to the moment of inertia of the rotor and thus the response of the turbine. Also, in generic turbines due to the design of generic runner, a significant heat input from that of the turbine wheel

flowing gas stream into the body of the hull group of the

Turbine, so that consuming cooling measures of the housing, such as the provision of a separate

Water cooling in the housing, are required. This applies in particular to turbines designed as turbochargers, which are used in internal combustion engines. Such Turbochargers are usually powered by engine oil

Internal combustion engine at its bearings, over which the

Tool z is rotatably mounted around housing, lubricated and thereby cooled. In addition, usually is a separate

Water cooling provided for cooling the turbocharger. When switching off the engine cooling ends by the engine oil but abruptly. Therefore are appropriate

Cooling measures, for example, a corresponding

designed water cooling, required for the

Hull group after turning off the turbocharger when the engine is hot running takes no damage, for example, by Lagerverkokung by coking of too hot engine oil at the bearing point, which is closest to the turbine side. Furthermore, there are in such generic turbines

significant friction losses between the metal of the rotor and sealing rings, which seal the rotor against a housing. In the prior art, attempts have also been made to realize turbines in which at least a portion of a. Ceramics and a _. other section are made of a metal. However, the production of such turbines has proven to be costly and the connection of the different sections difficult, it has been found particularly problematic that ceramic components are severely vulnerable to breakage and therefore very easy to damage in the manufacturing process and also in the application of such turbines or even a failure of such a turbine can come.

The present invention has for its object to provide a rotor for a turbine, the

Realization of a turbine allowed and at least partially solves at least one of the above problems. Furthermore, the present invention has for its object to provide a turbine, the at least one of at least partially corrects the above problems. Furthermore, the present invention is based on the object, a method for producing such a rotor and a method for producing such a turbine

provide.

As a solution, at least one of the aforementioned

Invention underlying tasks, the invention proposes a runner with the features of claim 1. Of the

Runner is suitable for use in a turbine, in particular in a turbocharger. The rotor comprises a turbine rotor made of ceramic and a shaft made of metal. As the ceramics, a silicon nitride ceramics (Si ₃ N ₄ ) is particularly preferable because such ceramics have a high strength. For example, at the filing date, such a ceramic is known by the manufacturer FCT under the material designation "SN-Pu." However, other suitable silicon nitride ceramics are known from other manufacturers with similar material properties.The shaft can be made from metal used in conventional turbochargers for the shaft be made,

for example from steel known or "42CrMo4" or "31CrMoV9" or similar. The shaft has a hollow cylinder section. The turbine rotor has a turbine wheel and a cylinder section. The turbine wheel is arranged axially relative to the axis of the cylinder section adjacent to the cylinder section. Of the

Cylinder portion of the turbine rotor is in the

Hollow cylinder section of the shaft arranged and fixed to this. Preferably, the axes of the cylinder portion and the hollow cylinder portion coincide. The fixation between the cylinder portion and hollow cylinder portion is preferably formed so that cylinder portion and

Hollow cylinder section are fixed positionally fixed to each other, so that they can perform relative to each other in the intended use of the rotor no relative movement. The

Fixation between hollow cylinder section and

Cylinder section can, for example, by soldering,

Gluing or shrinking of the hollow cylinder portion made on the cylinder portion. The rotor extends in an axial direction, which preferably coincides with the axes of the cylinder portion and the hollow cylinder portion, from its turbine side formed by the turbine rotor to its working side formed by the shaft. The runner thus has one

Turbine side and a working side, which limit the rotor in the axial direction. The axial end at the

Turbine side is formed by the turbine rotor, the axial end of the rotor at the working side by the shaft.

According to the invention, the runner has, from the working side, an external thread for screwing on a nut and a fixing device accessible from the working side, which is integrated in the shaft and for fixing the runner in a rotationally fixed manner from the working side during the operation

Screwing the nut is formed. Depending on

provided direction of rotation of the rotor, the external thread may be formed as a left or right-hand thread. Particularly preferably, the fixing device has a length in the axial direction, which corresponds at least to the diameter of the external thread of the shaft, wherein here

of course the outer diameter is meant. The fixing device is in particular integrally manufactured in one piece with the shaft. In particular, the axial

Extent of the external thread is limited to an area outside the fixing device. The fixing device thus has in particular no external thread. In particular, the external thread through the fixing of the Working side of the rotor axially spaced. In particular, the fixing device rests on the working side and the external thread on the fixing device. In particular, the maximum diameter perpendicular to the axial direction of the fixing device is smaller than the outer diameter of the

External thread. The fixing device may for example be designed as a pin, which is encompassed by the shaft and is arranged to the working side next to the external thread. At such a pin can then a corresponding

trained fixing tool can be attached, with which the shaft is held against rotation, while a nut is screwed onto the external thread. For example, such a pin has a cross-section perpendicular to the axial

Direction with an ellipse shape, a polygonal shape, a shape with regular polygon, in particular octagonal, hexagon or square, having, as a fixing tool, a tool with a recess with a corresponding cross section can be used. For example, the pin may also have a circular cross-section and by special fixing tools, such as

Klemmfixierwerkzeuge be held. For example, the fixing device can also be realized by a slot or Phillips on the working side of the shaft into which a corresponding screwdriver can engage. For example, the fixing device by a radially within the shaft and axially over a certain

Length range extending excavation with certain

Cross section, for example, oval, polygonal, regular polygon, in particular octagonal, hexagonal or square cross-section, be realized, in which then a fixing tool with a corresponding cross-section can be introduced for rotationally fixed fixing the shaft from the working side, while the mother on the

External thread is screwed. It is essential that the Fixing device is provided on the working side of the shaft and is accessible from the working side, while the nut is screwed onto the external thread, so that the shaft and thus the rotor from the working side

rotationally fixed by a fixing tool can be fixed while the nut is screwed onto the external thread.

The inventor has realized that the provision of a ceramic turbine rotor has significant advantages. First, ceramics have a much lower density than conventionally used high temperature resistant

Metal alloys, in one embodiment, only about 60% of the density of a conventional inconel alloy, whereby the moment of inertia of the rotor is reduced and thus the response of a turbine with a rotor according to the invention can be significantly improved compared to the response of conventional turbines. In addition, it has been found to be particularly advantageous that in the

Concerning a sealing ring on the turbine rotor friction is substantially reduced when the turbine rotor is made of a ceramic compared to a metal turbine rotor. In particular, the inventor has recognized that at the same time the temperature stability of the turbine wheel can be substantially improved by providing a ceramic turbine rotor. While usually for the

Turbine used metal alloys, such as

For example, Inconel or MAR have a temperature resistance up to a temperature of about 980 ° C (Inconel) or about 1050 ° C (MAR), ceramics have a significantly improved temperature resistance, in particular a temperature resistance up to temperatures of 1200 ° C.

Inventive runners can thus be exposed to much higher temperatures on their turbine side without the turbine wheel being damaged. This can For example, be particularly advantageous for the use of inventive rotor in turbochargers, since exhaust gas streams with significantly higher exhaust gas temperatures of up to 1200 ° C can be passed to the turbine wheel, whereby the

Efficiency of the internal combustion engine due to the higher

Exhaust gas temperatures can be improved. In addition, the inventor has recognized that ceramics exist which have a poor thermal conductivity, so that by providing a ceramic turbine rotor of such a ceramic, the heat input from the gases into the rotor

and / or the housing of a turbine, in which the

Inventive runner is used, if possible

can be kept low. The invention thus relates both to a turbine rotor made of a highly thermally conductive ceramic as well as to a turbine rotor with a poor thermal conductivity ceramic, the latter brings the advantage of a lower heat input into the housing with it. The invention is further based on the finding that it is particularly advantageous if such a fixation of the working element on the rotor is ensured that regardless of a temperature-dependent expansion behavior of the working element this working element is always fixed with a constant bias as possible on the rotor. The inventor has recognized that for this purpose the provision of a shaft made of steel is particularly advantageous, since the temperature-dependent expansion behavior of the shaft made of steel, a temperature-dependent expansion behavior of the

Working elements, such as a compressor wheel made of aluminum, can be compensated so that at least over a temperature range that is relevant for the intended use of a runner realized for this purpose, as constant as possible bias on the working element for fixing the working element to the rotor

can be guaranteed. The invention is thus further the special finding that the combination of a turbine rotor made of ceramic with a shaft made of steel brings particular advantages. Furthermore, lies the

The invention is based on the recognition that s s s for the mounting of a working element on the rotor of a turbine for

Ensuring a predefined fixation of the individual components is required that a non-rotating

Fixation of the rotor takes place while the nut is screwed onto the external thread to the working element

rotationally fixed and fixed in position on the rotor. The inventor has recognized that the rotationally fixed fixation of the rotor via the fixing device permits a substantially precise tightening of the nut for predefined fixing of a working element to the rotor, than with a fixing via a ceramic turbine rotor or

Fix over the attached to the runner

Work item is possible. By providing a

certain minimum axial length of the fixing device can moreover be ensured - that of the

Working side of a particularly reliable fixation of the rotor over the shaft, namely on the fixing device of the shaft can be done.

Particularly preferred are all edges of the shaft, with which it rests against the turbine rotor, rounded. As a result, a notch effect in the ceramic, which can lead to breakage, can be effectively prevented.

In one embodiment, the turbine rotor has one between the turbine wheel and the cylinder portion

Intermediate section on, with the diameter of the

Turbine rotor in a centrifuge section of

Increases intermediate portion in the axial direction to the turbine side up to a first maximum and then below Forming a maximum edge formed by the maximum decreases, wherein a circumferential receiving groove is provided axially between the peripheral edge and the turbine wheel in the intermediate portion for receiving at least one sealing ring, wherein in particular the diameter of the

Intermediate portion in the receiving groove is larger than in the cylinder portion. The edge is thereby formed, that the diameter of the intermediate portion of the

Turbine rotor increases to a maximum, then over a certain axial range, the value of the maximum retains and then decreases. The axial region with the value of the maximum for the diameter preferably has an axial length of not more than 2 mm, in particular 1 mm. By the centrifuge section is ensured in the intended use of the rotor that oil, which is provided for lubrication of bearings over which the rotor is guided in a housing of a turbine, due to the typically high speed of the rotor at least a predominant proportion not until Turbine wheel can get there as it is a

Centrifugal force undergoes and because the edge forms a trailing edge, from which via the centrifugal force

Accelerated oil resulting from the bearing lubrication, is thrown radially and can then be collected. The provision of the circumferential receiving groove between the centrifuge section and the turbine wheel allows the use of sealing rings in the receiving groove, so that at least almost any oil, despite the

Providing the centrifugal still in the axial direction beyond the centrifuge section on the

Turbine rotor should flow towards the turbine wheel, can not get to the turbine side of the turbine wheel. As a result, contamination of the turbine wheel driving gases can be prevented by engine oil as best as possible. In addition, this can reduce oil consumption be minimized.

With the present invention, it has been recognized that it is particularly advantageous to provide the centrifuge section and the circumferential receiving groove in the ceramic rotor made of ceramic. For one thing is by it

ensures that when using a poor thermal conductivity ceramic, this poor thermal conductivity ceramic extends from the turbine wheel into the housing, since the centrifuge section and the receiving groove

must of course be arranged axially within the housing. The heat input from the exhaust gases into the housing of a body group of a turbine can thus by the

described embodiment of the rotor according to the invention additionally be particularly reduced by that

Contact point between rotor and housing of the fuselage group, which is closest to the exhaust gases, takes place in the field of ceramics. This contact point is usually formed by the sealing rings or the sealing ring, which are arranged in the receiving groove and abut the rotor and on the housing. The fact that the ceramic extends from the turbine wheel to the receiving groove and beyond, it can be ensured when using a corresponding ceramic that up to the contact point, namely up to the receiving groove and the therein in a conventional

Turbine arranged sealing rings (or sealing ring), the heat input from the exhaust gases is kept as low as possible in the housing. The described embodiment of a rotor according to the invention can contribute in particular to the fact that a turbine can be realized in which no separate water cooling in addition to cooling by the engine oil is provided, since the heat input into the housing of the turbine can be kept so low that even without the Provide a separate water cooling a Overheating of the bearing between rotor and housing, which is closest to the turbine side, can be prevented. On the other hand, due to the good sliding properties of ceramic surfaces by providing the receiving groove in the turbine rotor made of ceramic, the friction between a fixed to the housing sealing ring and an inner wall of the

Receiving groove on which it rests for sealing, be reduced. It should be noted that friction is generated by sealing rings, which are arranged in the receiving groove. These seals are mostly fixed in position in the

Housing held and lie with an axial end face on an inner wall of ahmenut on. Upon rotation of the tool relative to the housing thus turns the

Turbine rotor relative to the sealing rings, while the

Seal rings remain fixed to the housing. It thus creates friction on the contact surfaces between sealing rings and receiving groove. By providing the receiving groove in the

Ceramic turbine rotor may be due to the good

- Sliding properties of ceramics this friction clearly

be reduced compared to a use of

conventional runners, in which the receiving groove is provided in a metal-made component. In a turbine according to the invention, in which a rotor according to the invention is used, particularly preferably the sealing rings or the sealing ring as a ceramic sealing ring

be formed, whereby the friction between the sealing ring and receiving groove can be further reduced. By the

Reducing the friction between the rotor and housing of a turbine can further improve the response of the turbine. In addition, the turbine rotor of the relatively light ceramic extends over a wide area in which it is forced to have a large diameter in the housing. This allows the turbine rotor

be made more resistant, thereby breaking the Turbine wheel can be prevented by turbine rotor. Furthermore, this can be realized by a very low moment of inertia.

In one embodiment, the diameter of the

Turbine rotor in a axially between the cylinder portion and the centrifuge section and axially adjacent to the centrifuge section portion in the axial direction to the turbine side down. This can be made possible that in the manufacturing process of the rotor, the rotor in an area which is axially adjacent to the working side

Centrifuge section is arranged, can be ground to adjust as exact as possible fit this area without this, the centrifuge section is damaged, which could lead to an impairment of the function of the centrifuge section.

In one embodiment, the turbine rotor axially between the cylinder portion and the centrifuge portion on a bearing portion which is formed in the manner of a cylinder and having a diameter which is greater than the diameter of the cylinder portion and smaller than the diameter at the maximum. In particular, is the

Bearing portion with its first axial side immediately adjacent to the cylinder portion and with its second axial side directly to said, axially on the

Centrifuge section adjacent section. Through the cylindrical bearing portion is in this

Embodiment allows the turbine rotor with its bearing portion in a conventional radial bearing, which may be formed, for example, as a bronze bearing, in particular as a bronze ring, inserted, so that with this embodiment of the rotor according to the invention, a turbine can be realized in which the bearing portion via a radial bearing directly to the housing of the

Turbocharger communicates. The radial bearing can then be separated only by an oil film of the bearing portion and the housing, so that the housing and the

Bearing section only provided by the interposed

Radial bearings are separated. This embodiment brings several special advantages. On the one hand, by providing a low thermal conductivity ceramic of the turbine rotor, a low heat input through the

Turbine rotor in the radial bearing at the bearing section

to be guaranteed. On the other hand, this allows

Embodiment, that the turbine rotor extends into the housing of a turbocharger over a wide axial region in which it has a large diameter. Consequently, this embodiment of the rotor allows the realization of a particularly durable runner, as the

Turbine rotor over a wide axial range has a large diameter, whereby a fracture of the turbine rotor can be prevented as well as possible. In addition, this allows the moment of inertia be kept even lower, whereby the response of a turbine with such a rotor can be further improved. In addition, the axially successive arrangement of cylinder section, bearing section and centrifuge section, wherein in particular between the bearing section and centrifuge section of the

arranged axially disposed on the centrifuge section portion is arranged such that a fixation of the

Turbine rotor on the shaft can be made via the cylinder portion and a discharge of the oil running in the bearing can be carried out through the centrifuge section, so that leakage of oil into the gases on the turbine side of the

Runner when using the rotor in a turbine can be largely avoided. This allows the

Oil consumption can be minimized and pollution of the gases be largely prevented by oil. By providing a larger diameter in the bearing section than in the. Cylinder section can also be ensured that the hollow cylinder portion of the shaft on the

Cylinder portion can be applied without the outer diameter of the hollow cylinder needs to be provided larger than the diameter of the bearing portion. In one embodiment, the diameter of the

Bearing section identical to the outer diameter of the

Hollow cylinder section of the shaft. This may be the special one

Advantage bring with it that a first radial bearing on the bearing portion and a second radial bearing on the

Hollow cylinder portion of the shaft can be arranged, wherein both radial bearings can be formed identically and thus can be arranged in a tube designed as a tube with a constant diameter tube portion of the housing. The provision of the axially adjacent to the centrifuge section, in which the diameter of the

Turbine rotor decreases starting from the bearing portion in the axial direction to the turbine side, which is then arranged in the axial direction of the centrifuge section in which the diameter increases toward the turbine side, brings with it a further particular advantage. Thus, after the shaft is connected to the turbine rotor by inserting the cylinder portion of the turbine rotor into the hollow cylindrical portion of the shaft, the rotor may be allowed to abut on the bearing portion and the rotor

Hollow cylinder section can be ground simultaneously, so that the realization of an identical diameter of bearing section and hollow cylinder section can be carried out particularly precisely and easily.

In one embodiment, the diameter of the

Turbine rotor starting from the turned to the turbine side End of the hollow cylindrical portion such a course in the axial direction that the diameter first decreases in the axial direction toward the turbine side and then increases until it is greater than that of the

Turbine side facing end of the hollow cylinder section.

The end of the hollow cylinder section of the shaft facing the turbine side is therefore preferably axially of the shaft

Bearing portion of the turbine rotor spaced. In the axial region in which the turbine rotor has the described larger diameter than at the end facing the turbine side of the hollow cylinder portion forms the

Turbine rotor off the bearing section. Particularly preferably, the diameter of the turbine rotor, starting from the end of the hollow cylinder section facing the turbine side, initially decreases in the axial direction toward the turbine side, in particular steadily until it reaches a minimum, whereafter it steadily increases until the formation of the turbine

Bearing section. The diameter thus reaches after its increase its maximum when reaching the diameter of the bearing portion and retains this maximum on the axial

Length of the bearing section at. This course is particularly preferably continuous and thus not stepped. About the corresponding course of the diameter of the

Turbine rotor can be particularly effectively ensured that the wave with its turbine facing end of its hollow cylinder portion does not exert such a notch effect on the turbine rotor, which poses a risk of breakage of the turbine rotor in the manufacture and in particular in the use of the turbine rotor in a rotor or a turbine , The inventor has recognized that it is particularly advantageous for this purpose that in the ceramic of the

Turbine rotor as described course of the

Diameter is provided so that the outer contour of the turbine rotor from the radial center to the Turbine side facing end of the hollow cylinder portion can extend. Particularly preferably, the course of the diameter of the turbine rotor with a continuous contour in the course of the diameter of the

Hollow cylinder section of the shaft over, so that there is no sharp edge at the transition between turbine rotor and shaft. Particularly preferred is thus the tangent of the course of the diameter of the shaft, d. H. the course of the outside of the shaft, at the transition between shaft and turbine rotor identical to the tangent of the course of the diameter, d. H. the course of the outside, the turbine rotor at this transition. The transition refers to the point along the axial direction, on the outside of the rotor, the shaft and the turbine rotor adjacent to each other. Due to the configuration of the described embodiment, cracking in the ceramic of the turbine rotor due to an action of the shaft is particularly effectively prevented. Such a course of the diameter of the turbine rotor between the to

Turbine side facing end of the hollow cylinder portion and the bearing portion, in particular at the transition between the shaft and turbine rotor, proved, which has a radius of curvature which is at least a quarter of the diameter of the turbine rotor in the bearing portion. Particularly preferably, the course of the diameter of the

Turbine rotor in the said region at any point on a radius of curvature which is smaller than a quarter of the diameter of the turbine rotor in the bearing portion. It has proven to be particularly advantageous that the diameter of the turbine rotor, starting from the end of the hollow cylinder section facing the turbine side, initially decreases by at least 0.1 mm, in particular between 0.1 mm and 0.3 mm, before it then, as explained, increases. Of course, it is general Particularly advantageous that the turbine rotor at least in an axial portion, by the axial length of the hollow cylinder portion, bearing portion and

Centrifuge section is defined, is formed rotationally symmetrical about the axial direction. The inventor has further recognized that it is particularly advantageous for the production of a rotor according to the invention that in one

Step of the hollow cylinder portion of the shaft is pushed onto the cylinder portion of the turbine rotor for connecting shaft and turbine rotor to each other until the hollow cylinder section with its facing the turbine side axial end against the turbine rotor, in particular against the bearing portion of the turbine rotor, presses, after the fixation of the turbine rotor and Shaft to each other by means of a grinding process, such an outer contour of the rotor is generated, that the diameter of the turbine rotor starting from the turbine side facing the end of the hollow cylinder portion has such a profile in the axial direction, that the

Diameter first in the axial direction to

Turbine side decreases and then increases until it is greater than at the end facing the turbine side of the hollow cylindrical portion, in particular the profile of the diameter of the turbine rotor between the

Turbine side facing end of the hollow cylindrical portion and the bearing portion has a radius of curvature which is at least a quarter of the diameter of the turbine rotor in the bearing portion. In this manufacturing method is thus in a first working section of

Hollow cylinder portion of the shaft pushed onto the cylinder portion of the turbine rotor until it, as explained, presses against the turbine rotor, which then in a

subsequent second step of the described grinding process is performed. After completing the first Working step is the hollow cylinder portion of the shaft with its facing the turbine side axial end axially on the bearing portion of the turbine rotor directly or indirectly. For this purpose, the turbine rotor can, for example, during the first working step, a step between

Have bearing portion and cylinder portion over which the diameter of the turbine rotor gradually increases from the cylinder portion to the bearing portion. In this case, the hollow cylinder after completion of the first working step with its facing the turbine side end face, i. with its end facing the turbine side, abut directly or indirectly at this stage. This allows a particularly robust fixation of the turbine rotor and shaft to each other be realized and beyond a compact design as possible with the lowest possible material and material weight while ensuring a very good

Fixation. In addition, this can ensure a high accuracy of fit. In the case of direct contact, the axial end of the hollow cylinder section is directly in contact

Contact with the warehouse section. In an indirect

Concerns is the axial end of the hollow cylinder portion in direct contact with a fitting body, such as a fitting ring, which in turn is in direct contact with the bearing portion itself. During the second step can then by means of the grinding organg existing during the first step of the turbine rotor stage

be ground to generate the explained profile of the diameter of the turbine rotor, while at the same time such a contour can be ground at the facing to the turbine side axial end of the shaft, that the diameter of the shaft in a facing on the turbine side end portion of the hollow cylinder portion via a curved Course in the axial direction towards the turbine side steadily reduced until the turbine side turned End of the hollow cylinder section. The inventive method described is a simple,

non-destructive and high-precision manufacture of a

Runner invention allows. Because in that in the first step the wave with her

Hollow cylinder section on the cylinder section of

Turbine rotor is pushed until the

Hollow cylinder section of the shaft frontally on the

Turbine rotor is applied, the axial position of the shaft and turbine rotor to each other can be determined very precisely. Here are the turbine rotor and just the

Hollow cylinder section during the first step, a sufficient material thickness and thus strength, which is particularly advantageous for the precise determination of the axial position of the shaft and turbine rotor. It should be noted that the hollow cylinder portion of the shaft has a very small cylinder wall thickness, in particular a cylinder wall thickness between 0.4 mm and 1 mm, so that it is of considerable importance that this

Hollow cylinder portion during the first step at its end facing the turbine side if possible not ground so that this is accompanied by a reduction of the cylinder wall thickness and thus a weakening of this end, so that a hard stop of this end on the turbine rotor is possible. By the following

Grinding after fixation of shaft and

Turbine rotor to each other is then ensured that the shaft exerts no adverse notch effect on the turbine rotor. This procedure has proven to be special

favorably proved that the length of the

Hollow cylinder section not precise on the

Cylinder section of the turbine rotor needs to be matched, since the achievable axial positioning of the shaft relative to the turbine rotor not by a stop the cylinder portion at the end of the hollow cylinder portion, but by a stop of the end face of

Hollow cylinder section is realized on the shaft. The hollow cylinder portion or the hollow of the shaft for generating the hollow cylinder portion can thus be achieved in a simple manner by rubbing or honing, as at the end of the hollow cylinder portion, d. H. at the bottom of the

Hollow cylinder section defining "blind hole", a

Freigangs is provided in which is not arranged in the finished rotor, the cylinder portion of the turbine rotor.

In one embodiment, the hollow cylinder portion of the shaft is at least 0.5 times its clear

Inside diameter on the working side over the

Cylinder section of the turbine rotor before. Of the

Cylinder section of the turbine rotor fills the

Hollow cylinder section of the shaft thus not completely out. This can be partly because of the lower

Material use in the shaft to an even lighter design and thus lead to a lower moment of inertia of the rotor.

Particularly preferably, the hollow cylinder portion of the shaft in its portion with which it protrudes on the working side over the cylinder portion, a through its

Hollow cylinder shell through vent hole on.

Alternatively or additionally, on the inside of the

Hollow cylinder portion of the shaft or be provided on the outside of the cylinder portion of the turbine rotor an axially extending groove. Preferably, two such grooves are provided, which are provided on opposite sides, so that no imbalance arises during a rotation of the rotor. Accordingly, two vent holes be provided, which on opposite sides and thus mirror-symmetrical to the axial direction about the axis

are arranged. In a preferred embodiment, a plurality of such grooves and / or several such

Vent holes provided, wherein the grooves and / or the vent holes are arranged in pairs symmetrically about the axis. As a result, as explained, an imbalance in the runner can be prevented particularly effectively. The axially extending channel or the axially extending channels can be realized by suitable measures in the rotor. In one embodiment, an axially extending channel is realized in that the cylinder section does not have a circular cross-section but one on one side

having flattened cross-section, whereby a groove between the hollow cylinder portion and cylinder portion

is formed. Accordingly, two such grooves can be realized by two corresponding flattenings. An axially extending groove may also be formed, for example, as a groove spiral on the outside of the cylinder portion of the turbine rotor, d. H. as a groove, which runs spirally along the outside and thus extends axially. By appropriate measures, the introduction of the

Cylinder section in the hollow cylinder section to be particularly simplified, as a result of compression of air in the hollow cylinder portion in the insertion of the

Cylinder section can be prevented. In such measures it is essential that the clear cross-section of the at least one vent hole provided or the at least one channel provided is so large that the air from the hollow cylinder section can escape sufficiently quickly when the cylinder section in the

Hollow cylinder section is introduced. This is especially in the high-precision production of a rotor according to the invention of particular advantage, since in the postponement of the Hollow cylinder section on the cylinder section of

Has hollow cylinder portion only an extremely small allowance when it is pushed over the cylinder portion, so that virtually no air flow between the hollow cylinder portion and cylinder portion and thus from the

Hollow cylinder section can escape. It goes without saying that this is of particular advantage in a particularly advantageous embodiment of the rotor according to the invention, in which the allowance during the sliding of the hollow cylinder portion on the cylinder portion is very small, whereby a corresponding precision in the manufacture of the rotor is accompanied. To be particularly advantageous has been found to provide a clear cross-section of the at least one vent hole or the at least one channel, the at least one-seventh of the clear

Cross-section of the interior of the hollow cylinder portion is, in particular between a fifth and a

Seventh of the clear cross-section of the interior of the

Hohlzyli-Nderabschnitts. In the provision of such a clear cross-section of the at least one vent hole or the at least one channel is simultaneously a.

sufficiently rapid escape of air from the

Hollow cylinder portion and the greatest possible stability of the hollow cylinder portion and the cylinder portion in the hollow cylinder portion allows. In the provision of a plurality of vent holes and / or a plurality of grooves corresponding to the common clear cross-section of all vent holes and / or grooves at least one-seventh of the clear cross-section of the interior of the

Hollow cylinder portion, in particular between one fifth and one seventh of the clear cross section of the interior of the hollow cylinder portion.

In one embodiment, the hollow cylinder portion surrounds the shaft the cylinder section of the turbine rotor

circumferentially closed, in particular in an axial

Section continuous closed. This axial

Section of the hollow cylinder can cover in particular the entire cylinder portion and thus uninterrupted

enclose. By the described embodiment, the rotor can be configured particularly robust.

Preferably, the shaft has at least one axial

Expansion portion which is offset from the hollow cylinder portion axially to the working side, wherein the

Diameter and the axial length of the expansion section are coordinated so that over a

Temperature range between -20 ° C and + 250 ° C the

Expansion behavior of the expansion section the

Stretching behavior of a fixed to the runner

Working element so far corresponds that within this temperature range, the working element with a strain in the expansion portion generating bias is fixed to the rotor without the yield strength of the steel of the shaft is achieved in the expansion section. The

Geometry of the expansion section is thus under

Considering the material properties of the steel and the properties of the working element set. Such an axial expansion section may enable a nut to be screwed onto the external thread of the shaft, thereby creating an expansion in the expansion section of the shaft, so that a particularly reliable fixation of the rotor in a body group can be made possible. The inventor has just recognized that the provision of an axial expansion section is particularly advantageous just when a ceramic turbine rotor is used, so that the combination of a metal-made shaft with an expansion section provided there and a Ceramic-made turbine rotor brings special benefits.

In one embodiment, the cylinder portion of the turbine rotor has an axial length that is between 1.5 times and 3.5 times, in particular between 2 times and 3 times the diameter of the

Cylinder section is. As a result, a particularly good fixation of the turbine rotor on the shaft and the use of the smallest possible amount of material can be made possible. The inventor has recognized that the ratio of the length of the

Cylinder section is particularly relevant to the diameter of the cylinder portion, since the fixing length over which the turbine rotor is fixed to the shaft, and which is predetermined over the length of the cylinder portion, is to be provided depending on the diameter of the cylinder portion to a stable coherent runner to

realize. The embodiment described is particularly advantageous in a realization of the fixation between the turbine rotor and shaft by means of shrinking the hollow cylinder portion on the cylinder portion, since it can be ensured over the specified conditions by the resulting adjustment of the pressure that the cylinder portion are completely inserted into the hollow cylinder section can before the hollow cylinder section shrinks on the cylinder portion. In addition, this can be a fixation by means of adhesive or soldering a

sufficient guide length be provided.

The invention further relates to a turbine, the one

Hull group comprising a runner according to the invention. The fuselage group features the runner, a housing and a

Work item on. The rotor is arranged axially in sections within the housing and over at least two Radial bearing rotatably guided to the housing. The two

Radial bearings are preferably axially spaced from each other. The radial bearings can each be connected as separate individual pieces or alternatively via connecting sections

be formed integrally. Particularly preferred are the radial bearings both the housing and the runner

rotatable. The working element is arranged on the working side of the rotor facing side of the housing and fixed to the shaft. It is essential that the

Working element is rotationally fixed to the shaft. The

Working element and the runner together form a running tool. The housing may particularly preferably have a tubular portion in which the radial bearings are arranged, wherein the rotor in the realization of the turbine by the

Tubular section is inserted therethrough. In the turbine, the turbine wheel on the one axial side and the

Working element arranged on the other axial side of the housing. About a nut working element, housing and runners axially position fes.t are screwed to each other, with the running gear can rotate relative to the housing.

Particularly preferred is a thrust bearing between the

Working element and the housing provided over which the axial position of rotor and working element is held relative to the housing. The thrust bearing may for example comprise an intermediate piece and a bronze disk, wherein the

Shaft axially offset to the working side of the hollow cylinder portion has a step with which they on the

Intermediate piece is applied, wherein the working element is pressed on one axial side and the shaft with the step to the other axial side of the intermediate piece. The

Bronze disc has a central passage through which passes the intermediate piece, wherein the intermediate piece has a groove in which the bronze disc is arranged, so that the bronze disc through the guide in the groove with a game of up to - led mm to the intermediate piece

^ 100 ^y

is. The bronze disk is further fixed axially to the housing by a rear wall. By the thrust bearing described thus the relative position of the running gear is fixed to the housing with respect to the axial direction, whereas the running gear can rotate relative to the housing about the axial direction. There are also other implementation possibilities of thrust bearings known in the art. The turbine according to the invention has the particular advantage that it has a very good response thanks to the use of the rotor according to the invention and, moreover, when using a poorly heat-conducting ceramic a smaller

Heat input from the turbine side, along which hot exhaust gases flow, takes place in the housing of the turbine.

Particularly preferably, the housing has an access for engine oil for lubricating the radial bearings, wherein the housing is designed so that it can be cooled only by the engine oil. The housing can thus for example be designed so that no connection and no

corresponding channel guide is provided for a water cooling in the housing. As a result, the implementation of the turbine, in particular of the turbocharger, can be particularly simplified. Also, the installation of the turbocharger in a motor vehicle can be particularly simplified. The realization of a turbine according to the invention, which is cooled exclusively by engine oil and not by other cooling devices, is possible in particular when using a poorly heat-conductive ceramic for the production of the turbine rotor of the rotor according to the invention, as a result

prevented by the gases that drive the turbine, such heat input into the rotor and above by means of one or more sealing rings in the

Housing takes place, that the bearings, in particular that of the Turbine side nearest bearing where turbine can be damaged.

In one embodiment, a first of the radial bearings between the housing and the shaft is provided, wherein a second of the radial bearings between the housing and the

Storage section is provided. This is the first one

Radial bearings in particular each only by an oil film of the housing and shaft and the second radial bearing in particular only by an oil film of the housing and

Storage section separated. This can - as above for

corresponding embodiment of the invention runner explained - a particularly good response of the

Turbine and in particular a particularly low heat input to be realized in the turbine. In particular, at least one of the radial bearings may be formed as a ring which has on its outer side at its annular jacket a circumferential groove, wherein in the groove circumferentially offset from each other Ölzuführlöcher are provided. Preferably, such a radial bearing is axially fixed in the housing so that a

Oil supply hole opens into the housing in the channel. By providing gutter and provided in the gutter

Ölzuführlöchern in the radial bearing can then an oil lubrication of the radial bearing by engine oil, by the

Oil supply hole in the housing is fed to the radial bearing, be particularly easy.

In one embodiment, in the receiving groove, which is provided in the intermediate portion of the turbine rotor, at least one sealing ring is arranged, which rests directly on the turbine rotor and directly on the housing. By at least one sealing ring can be ensured that as possible no engine oil that has moved axially to the turbine side over the centrifuge section out in the on the turbine wheel can flow gases. For example, two sealing rings axially adjacent to each other in the

Be arranged receiving groove. For example, the

at least one sealing ring, in particular all sealing rings, be designed as a piston ring. For example, the at least one sealing ring, in particular all sealing rings, be made of steel. Particularly preferably, the at least one sealing ring, in particular all sealing rings, made of ceramic, whereby a friction between

Seal and runner can be kept very low.

In one embodiment, the turbine comprises a nut, which is screwed onto the external thread and over which the working element is fixed to the shaft, wherein in particular the working element through the nut to a for

Turbine side facing side of an intermediate piece is pressed, in particular, the shaft is pressed with a radially extending projection against a working side of the intermediate piece facing side of the intermediate piece. The intermediate piece may for example consist of two parts, namely an axial disc, to which the shaft is pressed, and a main piece, to which the

Work wheel is pressed. As a result, a groove can be formed in the intermediate piece in a particularly simple manner in which a bronze disk of a thrust bearing can run. By providing the nut, a fixation of the running gear to the housing can be realized in a particularly simple and reliable manner, wherein the provision of a thrust bearing, for example as explained above for thrust bearing, can be made particularly simple and robust by the intermediate piece.

In one embodiment, the shaft is at its

Turbine side with a fixing device forming axial fixing section at least 1.5 times the diameter of the external thread over the external thread before. Alternatively, or in one embodiment, the fixing device is provided as a cavity in the shaft, which extends in the axial direction by at least 1 times the diameter, which of course is based on the outer diameter of the external thread radially inside the shaft. As for the runner according to the invention above

is explained in this realization of the turbine is a particularly simple and reliable non-destructive

Manufacture of the turbine allows, since in the manufacture of the turbine, the rotor can be held against rotation from the working side, while the mother on the

External thread is screwed on, so that a purposeful

Determination of the mother without load for this not

suitable components of the turbine can be done.

The invention further relates to a method for producing a rotor according to the invention. In the method according to the invention, the hollow cylinder section of the shaft is pushed onto the cylinder section of the turbine rotor for

Connecting shaft and turbine rotor to each other. In the method according to the invention, the hollow cylinder portion of the shaft is at a temperature of at least 300 ° C,

In particular, brought between 350 ° C and 450 ° C and kept heated to this temperature during the

Hollow cylinder section is pushed onto the cylinder section. At the same time, during the postponing of the

Hollow cylinder section on the cylinder section of

Turbine rotor at a temperature between 10 ° C and 50 ° C, in particular between 15 ° C and 40 ° C held. In particular, the turbine rotor is thereby kept at room temperature, i. that no tempering adjustment measure to

Setting a specific temperature of the turbine rotor is made while the hollow cylinder portion is pushed onto the cylinder portion. Particularly preferably, the sliding of the hollow cylinder section onto the cylinder section is completed in less than 3 s

carried out. This can cause a warming of the

Cylinder section be sufficiently prevented. The

inventive method allows a special

simple manufacture of the rotor and beyond a realization of a rotor in which the turbine rotor and shaft are reliably fixed to each other.

The invention further relates to a method for producing a rotor according to the invention, in which the

Hollow cylinder portion of the shaft is pushed onto the cylinder portion of the turbine rotor until it with its axial end face against the bearing portion of the

Turbine rotor presses. This inventive method is in particular with the aforementioned inventive

Method for producing a rotor according to the invention can be combined. The pressing can be done directly or indirectly via a fitting body between hollow cylinder section and bearing section. In a preferred

Embodiment is then ground after the fixation of the turbine rotor and shaft to each other, the rotor in the region of the hollow cylindrical portion and the bearing portion by a single grinding operation to produce in this area a uniform diameter of the rotor. In this inventive method, the realization of a rotor is possible, which has a very precise constant diameter over a range at the following radial bearings can be arranged to produce a turbocharger. In a further preferred embodiment, which is combinable with the aforementioned, is after

Successful fixation of turbine rotor and shaft to each other produces by means of a grinding process such an outer contour of the rotor, that the diameter of the turbine rotor, starting from the end facing the turbine side

Has hollow cylinder portion such a profile in the axial direction, that the diameter first decreases in the axial direction to the turbine side and

then increases until it is bigger than at the

Turbine side facing end of the hollow cylinder portion, in particular the course of the diameter of the

Turbine rotor between the turbine side facing the end of the hollow cylindrical portion and the bearing portion has a radius of curvature which is at least a quarter of the diameter of the turbine rotor in the bearing portion. As explained above for the embodiment of the rotor according to the invention, thereby a notch effect of the shaft, the risk of breakage causing damage to the

Turbine rotor can cause, be prevented. In a combination of the described particularly preferred

Embodiments are particularly preferred according to

Fixing of turbine rotor and shaft to each other first described the grinding process for generating a uniform diameter in the region of the hollow cylinder portion and the bearing portion and then the grinding process for generating the described course of the diameter of the turbine rotor starting from the turbine side facing the end of the hollow cylinder section. Generally, in the method according to the invention, the turbine rotor is particularly preferably used in the first working step

used partially processed state in which it has the cylinder portion at its facing the compressor side axial end. During the second step, i. After fixation of shaft and turbine rotor to each other, then takes place via further grinding operations a

Fine machining of at least the turbine rotor while For example, the said profile of the outer diameter of the turbine rotor is ground and / or the rotor, as explained, is ground in the said region for producing a uniform diameter and / or the centrifuge section and / or the receiving groove for the

Sealing ring to be ground. For this purpose, the turbine rotor particularly preferably has a rotationally symmetrical axis at its axial end facing the turbine side

Centering on and in particular the shaft at its end facing the compressor side also a

rotationally symmetric centering on. The

Centering devices, for example, by a conical centering, in particular a conical

Recess, be realized with an opening angle between 40 ° and 70 ° in the turbine rotor or the shaft. Particularly preferably, the turbine rotor at his to

Compressor side facing axial end a first

Centering device and at his to the turbine side

end of a second centering, which are each rotationally symmetric, so that the turbine rotor during the partial processing to reach the state of the turbine rotor, for the first step

is required, reliable rotationally symmetric can be performed.

The invention further relates to a method for producing a turbine according to the invention, in particular one

turbocharger according to the invention. In this case, the rotor is introduced with its working side in the housing and performed by the housing in a first step. In a second, subsequent step, the working element, in particular compressor wheel, of the

Arbeitsseite pushed onto the runner or

shrunk. In this case, the working element may be preferred be kept heated. In a third, after that

The next step will be the mother of the

Working side screwed onto the external thread, while the runner is held against rotation of the working side of the fixing device. In one embodiment, the fixing device is formed as a hexagon, which during the third step with a hex wrench

is held. In one embodiment, the

Fixing device designed as a thread, are bolted to the two lock nuts against each other and held during the third step by a fixing tool. In this embodiment, the two lock nuts between the second and the third

Working step on the thread of the fixing device

screwed and countered each other. In a

Embodiment be before the first step

Radial bearing in a tube section of the housing

introduced and axially fixed therein, after which in the first step .. the rotor is inserted into the tube section and performed by the tube section. After the first step and before the second step, a thrust bearing is pushed from the working side of the rotor. Due to the various embodiments of the method according to the invention, a turbine according to the invention, in particular a turbocharger according to the invention, can be produced in a particularly simple, precise and cost-effective manner.

The invention will be explained in more detail with reference to three figures.

FIG. 1 shows a schematic diagram of an embodiment of a rotor according to the invention; Figure 2: in a schematic schematic diagram

an embodiment of a turbine according to the invention;

Figure 3: in a schematic schematic diagram

a further embodiment of a

inventive turbine;

Figure 4: in a schematic schematic diagram

another embodiment of a

inventive rotor; Figure 5: in schematic schematic diagrams

various illustrations for explaining an embodiment of the method according to the invention;

Figure 6: in schematic schematic diagrams

Examples of turbine wheels used according to the invention.

In Figure 1 comprising the figure la and Figure lb an inventive rotor 1 is shown. Figure la shows the components of the illustrated rotor 1, namely the shaft 3 and the turbine rotor 2, before they are assembled to realize the rotor 1 and fixed together. FIG. 1b shows the finished rotor 1. As can be seen from FIG. 1, the turbine rotor 2 has a

Cylinder portion 21 and a turbine 26 on. The

Turbine wheel 26 forms the turbine side A of the rotor 1. The cylinder section 21 is arranged axially offset from the working side B toward the turbine wheel 26. A bearing portion 22 abuts axially directly on the cylinder portion 21, wherein a step between the cylinder portion 21 and

Bearing portion 22 is formed. Between the

Bearing portion 22 and the turbine 26 is also a Centrifuge section 23, an edge 24 and a receiving groove 25 are arranged. From the bearing portion 22 of the takes

Diameter of the turbine rotor 2 to the turbine side in an axially adjacent to the centrifuge section 23

Section off. In the Zentrif genabschnitt 23 takes the

Diameter of the turbine rotor 2 to a maximum towards, through which the peripheral edge 24 is formed. Oil, which in a turbine 100 - as exemplified in the turbocharger 100 in Figures 2 and 3 - on the

Warehouse section 22 runs over the

Centrifuge section 23 with a rotation of the rotor radially thrown away and rips off at the edge 24, so that only a very small proportion of this oil can ever reach into an axial region between the edge 24 and the turbine wheel 26. For this purpose, a receiving groove 25 is provided for receiving sealing rings, via which an escape of oil from a turbine 100 can be at least largely avoided.

Furthermore, it can be seen from FIG. 1 that the shaft 3 has a fixing device 33 on the working side B, which adjoins the working side B in an axial direction adjacent to

External thread 32 is arranged on the shaft 3. The

Fixing device 33 is thus located directly on the working side B, and the external thread 32 is spaced from the working side B by the fixing device 33. The rotor 1 can thus be held against rotation by means of the fixing device 33, while a nut 8 - as shown in FIGS. 2 and 3 - is screwed onto the rotor 1 or the external thread 32 of the rotor 1 to realize a turbine. Furthermore, the shaft 3 has an expansion section 34, in which the shaft 3 has a smaller diameter, so that the shaft is deliberately provided via this

Expansion section 34 by appropriately screwing a Nut 8 can be stretched on the external thread 32, so that in the realization of a turbine - as shown in Figures 2 and 3 - a controlled tightening of the rotor 1 and the compressor wheel 5 to the housing 4 is made possible.

Furthermore, the shaft 3 has a hollow cylinder section 31, in which the cylinder section 21 of the turbine rotor 2

is arranged. The arrangement of the cylinder section 21 in the hollow cylinder section 31 ensures a reliable fixation of the turbine rotor 2 to the shaft 3. The hollow cylinder portion 31 further has a vent hole 35 through which air can escape while the

Cylinder portion 21 in the hollow cylinder portion 31st

is introduced. In the described embodiment of the rotor 1 according to the invention, the hollow cylinder section 31 bears against the bearing section 22 with its axial end face. In addition, bearing section 22 and

Hollow cylinder section 31 an identical diameter. This is ensured by the fact that the rotor 1 is ground after assembling and fixing each other from turbine rotor 2 to shaft 3 in a single step in its area comprising bearing portion 22 and hollow cylindrical portion 31, whereby a constant diameter of the rotor 1 in this area are set very precisely can. FIG. 2 shows an embodiment of a turbocharger 100 according to the invention as an example of an inventive device

Turbine shown. In Figure 2, the turbocharger 100 is shown in its assembled state. From Figure 2 it can be seen that the turbine wheel 26 is disposed on one axial side of the housing 4, while that as

Working element provided compressor wheel 5 is arranged on the other axial side of the housing 4. The rotor 1 is rotatable relative to the housing 4 via the radial bearings 6, 7 stored. The second radial bearing 7 is that of the turbine side A closest radial bearing. The first radial bearing 6 is arranged between the housing 4 and the hollow cylinder section 31. The second radial bearing 7 is between the

Housing 4 and the bearing portion 22 is arranged. Of the

Turbine rotor 2 thus extends with a large

Diameter over a wide axial range within the housing 4, whereby on the one hand due to the lightweight ceramic of the turbine rotor 2, a low moment of inertia of the

Runner 1 and thus a good response of the

Turbocharger 100 is realized, and partly because of the poorly used in this embodiment

thermally conductive ceramic, a low heat input from the turbine side A due to the applied exhaust gases in the housing 4 of the turbocharger 100. Axially, the rotor 1 is fixed relative to the housing 4 by a thrust bearing comprising a bronze disk 12 and an intermediate piece, which by a main piece 9 and an axial disc 11 is formed. The bronze disk 12 extends in a groove formed by the axial disk 11 and the main piece 9 of the intermediate piece and is held by the rear wall 10 on the housing 4. As a result, the power tool, which is formed by rotor 1 with compressor wheel 5, axially fixed with a clearance of less than ^ mm fixed position to the housing 4, but at the same time rotatable about the axial direction to the housing 4. The fixation is done by screwing a nut 8 on the

External thread 32 of the shaft 3. It is from the working side B of the rotor 1 by means of the fixing 33rd

held while the nut 8 is screwed onto the external thread 32. The screwing of the nut 8 is carried out with a predefined torque and tightening angle, whereby a predefined strain in the expansion portion 34 of the shaft 3 and thus a predefined bias on the compressor wheel 5 is adjusted relative to the housing 4, with which it is pressed against the main piece 9 of the intermediate piece. For the sake of simplicity, the sealing ring in the

Receiving groove 25 not shown in Figure 2. FIG. 3 shows a further embodiment of a

Turbocharger 100 according to the invention shown. Of the

The turbocharger 100 according to the invention according to FIG. 3 differs from the turbocharger 100 according to the invention according to FIG. 2 exclusively in the design of the rotor 1

Contrary to the rotor 1 used in the turbocharger 100 according to FIG. 2, the rotor 1 used in the turbocharger 100 according to FIG. 3 has no bearing section 22. Instead, the turbine rotor 2 is formed so that its first axial end is formed by the cylinder portion 21, to which the centrifuge section 23 adjoins axially. Axially in the direction of the turbine side A toward the centrifuge section 23, the turbine rotor follows

2 of the rotor 1 according to Figure 3 as well as the rotor 1 according to Figure 2, an edge 24 and a receiving groove 25 and the turbine 26 on. The turbine 26 also forms in this rotor 1, the turbine side A of the rotor 1. Der

For simplicity, the sealing ring is not shown in the receiving groove 25 in Figure 2.

The cylinder section 21 is at the in FIG. 3

completely described within the

Hollow cylinder section 31 is arranged so that the fixation between the turbine rotor 2 and shaft 3 via the arrangement of the cylinder portion 21 in the hollow cylinder portion 31 and the relative fixing of these two sections takes place to each other. In contrast, in the embodiment according to FIG

3 both radial bearings 6,7 each directly on the

Hollow cylinder section 31 and on the housing 4 at. None of them Radial bearing 6, 7 is located directly on the turbine rotor 2. Compared to the turbocharger 100 according to Figure 2, in the turbocharger 100 according to Figure 3, the rotor 1 on a larger moment of inertia, since a larger proportion of the material of the rotor 1 of the heavier metal of the shaft 3 and not made of ceramic, there from ceramics

existing turbine rotor 2 does not form the bearing portion 22 for the second radial bearing 7. In this way, furthermore, the turbine rotor 2 is made less stable, so that this turbocharger 100 is suitable only for certain purposes. In addition, in the turbocharger 100 according to FIG. 3, a larger heat input into the second radial bearing 7 can take place since this second radial bearing 7 is not connected exclusively via ceramic as the only heat-conducting material. However, the turbocharger 100 according to FIG. 3 can be realized in a simple manner such that the region in which the two axial bearings 6, 7 are located has one

has consistently constant diameter, since this

Diameter can be adjusted only by the design of the metal-made shaft 3. In the turbocharger 100 shown in FIG

Water cooling 41, as known in conventional turbochargers, provided.

4a, 4b and 4c, schematic cross-sectional views and enlarged sections of this cross-section of a further embodiment of a rotor 1 according to the invention are shown in FIGS

shown. FIG. 4 a shows the position of the enlarged detail shown in FIG

dashed, marked with "X" frame displayed, while the location of the enlarged section shown in Figure 4c is indicated by a dashed, marked with "Y" frame. The embodiment according to FIG. 4 differs from the embodiment according to FIG. 1 in that the end of the hollow cylinder section 31 facing the turbine side A of the shaft 3 extends axially from the bearing section 22 of FIG

Turbine rotor 2 is spaced. This spacing is evident in particular from FIG. 4b. The rotor 1 according to Figure 4 is prepared by the shaft 3 in a first step with its hollow cylindrical portion 31 on the

Cylinder portion 21 of the turbine rotor 2 is pushed axially until the axial, the turbine side facing A

Front side of the hollow cylinder portion 31 on the

Bearing portion 22 of the turbine rotor 2 with a

Pressing force is applied, then in a second

Step of the runner is ground below

Reduction of its diameter, whereby the contour shown in Figure 4b and thus the enlarged in Figure 4b illustrated course of the diameter of the turbine rotor 2 is made. During this grinding operation, in the present case, said axial distance is generated by grinding both the turbine rotor 2 and the shaft 3 during the grinding process. During this

Grinding process, the turbine rotor 2 is ground so that its final realized diameter, starting from the axial end of the hollow cylinder portion 31, which faces the turbine side A, first decreases over a portion away, until it by the radial distance u, d. H. relative to the diameter by the distance 2 u (u in the present case is about 0.05 mm), of the diameter at the

said axial end of the hollow cylinder portion 31st

differs, after which the diameter of the

Turbine rotor 2 increases again. In general, a decrease in the radius of at least 0.05 mm, in particular between 0.05 mm and 0.15 mm is particularly advantageous, ie the decrease of the diameter by at least 0.1 mm, in particular between 0.1 and 0.3 mm, before the diameter increases again. In this case, the profile of the diameter of the turbine rotor 2 between the end facing the turbine side A of the hollow cylindrical portion 31 and the bearing portion 22 has a radius of curvature which is continuously at least a quarter of the diameter D of the turbine rotor 2 in the

Bearing portion 22 is. In the present case is the

Radius of curvature 3 mm, while the diameter of the

Bearing portion 22 of the turbine rotor is 12 mm. As explained above, the embodiment of the embodiment according to FIG. 4 has the particular advantage that a notch effect of the shaft 3 at the end of its

Hollow cylinder section 31 on the turbine rotor 2 is avoided as much as possible to cracking in the

Prevent turbine rotor 2 at the transition from the hollow cylinder portion 31 to the bearing portion 22. As explained in the general description to be particularly advantageous, and in the present embodiment is actually realized ^■ show the shaft 3 at the end of its hollow cylinder portion 31 and the turbine rotor 2 each have a diameter which such changes in function of the position along the axial direction, that the courses of the

Diameter of shaft 3 and turbine rotor 2 at the transition from the shaft 3 to the turbine rotor 2 have the same tangent, thereby preventing the shaft 3 is pressed with a sharp edge against the turbine rotor 2 and thus exerts an adverse notch effect on the turbine rotor 2.

From FIG. 4 c, it can be seen in particular that the

Diameter of the turbine rotor 2 in an axial on the

Centrifugal section 23 abutting portion in the axial direction toward the turbine side first decreases, after which then increases the diameter under Training of the centrifuge section 23 takes place. In this case, the radius in the mentioned axial section decreases by the amount v, in the present case by 0.05 mm. In general, the decrease of the radius by at least 0.05 mm, in particular between 0.05 mm and 0.15 mm is particularly advantageous, ie the decrease in the

Diameter by at least 0.1 mm, in particular between 0.1 and 0.3 mm. This ensures that in the precise setting of the diameter of the bearing portion during which the bearing portion is radially ground, no damage to the centrifuge section 23 takes place. The in

4c shows the course of the diameter, in which the radius initially decreases from the bearing section 22 by the amount v, represents the profile of the diameter in the finally produced rotor 1 according to FIG. 4a. It should be noted at this point that in the FIGS various figures of Figure 4, as well as in the

5, an allowance, which is finally ground in the finishing for the production of the rotor 1, is shown by a dashed allowance line.

In Figure 5 are in various schematic

Schematics Illustrations of the rotor 1 or components of the rotor 1 according to different stages of

Manufacturing process of the rotor 1 shown. In Figure 5a, the turbine rotor 2 is shown in its partially processed state. The turbine rotor 2 is first by means of

Injection molding is produced from a ceramic and then processed in a grinding process by removing the drawn in Figure 5a dashed lines allowance for generating the cylinder portion 21 of the turbine rotor 2. From Figure 5a is already apparent that the turbine rotor 2 facing on its side B to work End a first

Centering device 201 and at its to Turbine side A turned end a second

Centering device 202 which are each configured in the manner of a cone. These centering devices 201, 202 serve to guide the turbine rotor 2 during the

Grinding process as rotationally symmetrical as possible

To give outer contour. In Figure 5b is the

Connection process during which the shaft 3 is connected to the turbine rotor 2 by the

Hollow cylinder section 31 is pushed axially onto the cylinder section 21. In this case, the shaft 3 is held with a first mounting tool 51 and axially thereto

Turbine rotor 2 is displaced, while the turbine rotor 2 is held with a second mounting tool 52 which is inserted in a recess of the turbine rotor 2, in which the second centering device 202 is located. At this point it should be noted that the design of this

Recess and the interaction of this recess with the second mounting tool 52 is generally advantageous for various embodiments of the invention, and accordingly also an inventive

Manufacturing process taking advantage of this

Cooperation or these embodiments is generally particularly advantageous. This embodiment consists in that the turbine rotor 2 has at its end facing the turbine side A a cylindrical portion in which a recess is provided. This cylinder-like section and the recess are shaped like this

formed corresponding to the second mounting tool 52 that the mounting tool 52 rests with a ring portion laterally outwardly on the cylindrical portion of the turbine rotor 2 and at the same time with a pin at the axial end and thus the bottom of the recess, while

at the same time the pin is continuously spaced from the radial side walls of the recess. This embodiment brings the particular advantage that the turbine rotor 2 is held on the second mounting tool 52 such that an axial force for pushing the hollow cylinder portion 31 can be exerted on the cylinder portion 21 on the turbine rotor 2, and the

Turbine rotor 2 is guided radially without it too

Tensions in the turbine rotor 2 comes. Because the

between the pin and the radial side walls of the

Recess continuously provided air gap prevents, in conjunction with the concern of the ring portion of the cylinder-like portion, that the pin in the recess tilted and thereby causes a strain in the turbine rotor 2. Starting from Figure 5b, the shaft 3 is displaced axially relative to the turbine rotor 2 until the

Hollow cylinder section 31 of the shaft 3 with his to

Turbine side A facing axial end abuts the bearing portion 22 of the turbine rotor 2. This condition is shown in FIG. 5c. Subsequently, in a subsequent step, the shaft 3 is tensioned into a collet 53, while a centering tip 54 is arranged on the centering device 202 of the turbine rotor 2, after which a rotational movement of the collet 53 then takes place

Fine machining of the rotor 1 by means of a grinding process takes place. The structure for this step is shown in Figure 5d. In Figure 5d is also finished

processed rotor 1 shown, as it is also shown in Figure 4c. In this finished rotor 1, the above-described contours of the outside of the rotor 1 and thus the course of the diameter of the rotor 1 were realized by means of grinding operations.

In Figure 6 comprising Figures 6a and 6b are two examples of the configuration of the turbine wheel 26 of a

Inventive runner 1 or an inventive Turbine 100 shown. The turbine wheel 26 according to FIG. 6a is designed as a radial turbine wheel, the turbine wheel 26 according to FIG. 6b as an axial turbine wheel. The turbine wheel 26 may alternatively be designed, for example, as an axial-radial turbine wheel.

Turbine with ceramic turbine rotor

LIST OF REFERENCE NUMBERS

1 runner

2 turbine rotor

3 wave

4 housing

5 compressor wheel

6 radial bearings

7 radial bearings

8 mother

9 main piece

10 back wall

11 axial disc

12 bronze disc

21 cylinder section

22 bearing section

23 Centrifuge section

24 edge

25 receiving groove

26 turbine wheel

31 hollow cylinder section

32 external thread

33 fixing device

34 stretch section 35 vent hole

41 water cooling

51 first assembly tool

52 second assembly tool

53 collet

54 center point

00 turbocharger

01 first centering device 02 second centering device

A turbine side

B work page

u distance

V distance

D diameter

Claims

Turbine with ceramic turbine rotor claims

1. rotor (1) for a turbine, in particular a

Turbocharger (100), the rotor (1) comprising a turbine rotor made of ceramic (2) and a shaft made of metal (3), wherein the shaft (3) has a

Hollow cylinder section (31), wherein the turbine rotor (2) has a turbine wheel (26) and a cylinder portion (21) _', which is arranged in the hollow cylindrical portion (31) and fixed thereto, wherein the rotor (1) in an axial Direction from its turbine side (A), which is formed by the turbine rotor (2), to its working side (B), which is formed by the shaft (3), characterized in that the rotor (1) on its working side (B) has an external thread (32) for screwing a nut (8) and from the working side (B) from accessible fixing device (33) which is integrated in the shaft (3) and the

Fixing the rotor (1) from the working side (B) during the screwing of the nut (8) is formed, wherein the fixing device (33) in particular a length in has the axial direction which corresponds at least to the diameter of the external thread (32) of the shaft (3).

2. rotor (1) according to claim 1, characterized in that the turbine rotor (2) between the turbine wheel (26) and the cylinder portion (21) has an intermediate portion, wherein the diameter of the turbine rotor (2) in one

Centrifuge section (23) of the intermediate section increases in the axial direction toward the turbine side (A) to a first maximum and then decreases to form a peripheral edge (24) formed by the maximum, wherein axially between the peripheral edge (24) and the turbine wheel (26) in the intermediate portion a circumferential receiving groove (25) is provided for receiving at least one sealing ring, wherein in particular the diameter of the

Intermediate portion in the receiving groove (25) is greater than in the cylinder portion (21).

3. rotor (1) according to claim 2, characterized in that the diameter of the turbine rotor (2) in an axially between the cylinder portion (21) and the

Centrifuge section (23) lying and axially on the

Centrifuge section (23) abutting portion in the axial direction to the turbine side (A) decreases.

4. rotor (1) according to any one of claims 2 or 3, characterized in that the turbine rotor (2) axially between the cylinder portion (21) and the centrifuge portion (23) has a bearing portion (22) which is formed in the manner of a cylinder and has a diameter which is larger than that

Diameter of the cylinder portion (21) and smaller than the diameter at the maximum.

5. rotor (1) according to claim 4, characterized in that the diameter of the bearing portion (22) is identical to the outer diameter of the hollow cylindrical portion (31) of the shaft (3).

6. rotor (1) according to any one of the preceding claims, characterized in that the diameter (D) initially decreases in the axial direction to the turbine side (A) and then increases until it is greater than at the end facing the turbine side (A) of the hollow cylinder section (31), wherein in particular the course of the diameter of the turbine rotor (2) between the turbine side (A) facing the end of the

Hollow cylinder portion (31) and the bearing portion (22) has a radius of curvature which is at least a quarter of the diameter (D) of the turbine rotor (2) in the

Bearing portion (22) is.

7. Rotor according to claim 6, characterized in that the diameter of the shaft (3) in one of the turbine side (A) facing end portion of the

Hollow cylinder section (31) over a curved course in the axial direction to the turbine side (A) towards continuously reduced to the turbine side (A) facing the end of the Hollow cylinder section (31).

8. rotor (1) according to one of the preceding claims, characterized in that the hollow cylindrical portion (31) of the shaft (3) by at least 0.5 times its clear inner diameter at the

Working side (B) over the cylinder portion (21) of

Turbine rotor (2) protrudes, in particular the

Hollow cylinder section (31) of the shaft (3) in his

Section with which he at work page (B) on the

Cylinder portion (21) protrudes, one through his

Has hollow cylinder shell through the vent hole (35), and / or on the inside of the

Hollow cylinder section (31) or on the outside of the

Cylinder section (21) is provided an axially extending groove.

9. rotor (1) according to one of the preceding claims, characterized in that the shaft (3) has at least one axial expansion portion (34) which is offset from the hollow cylinder portion (31) axially to the working side (B), wherein the diameter and the axial length of the expansion section (34) are coordinated so that over a temperature range between -20 ° C and + 250 ° C, the expansion behavior of

Stretching section (34) corresponds to the expansion behavior of a fixed to the rotor (1) working element so far that within this temperature range, the working element with a strain in the expansion section (34) generating bias on the rotor (1) is fixed without the yield strength of the steel of the shaft in that

Stretching section (34) is achieved.

10. rotor (1) according to one of the preceding claims, characterized in that the cylinder portion (21) of the turbine rotor (2) has an axial length which is between 1.5 times and 3.5 times, in particular between the 2 Times and 3 times the diameter of the cylinder portion (21).

11. A turbine (100) comprising a body group with a

Rotor (1) according to one of the preceding claims, wherein the body group comprises the rotor (1), a housing (4) and a

Working element, in particular a compressor wheel (5) comprises, wherein the rotor (1) axially in sections within the housing (4) and at least two radial bearings (6, 7) rotatably guided to the housing (4), wherein the working element ( 5) on the working side (B) of the rotor (1) facing side of the housing (4) and fixed to the shaft (3).

12. turbine (100) according to claim 11, characterized in that the housing (4) has an access for engine oil for lubricating the radial bearings (6, 7), wherein the housing (4) is formed so that it exclusively by the engine oil is coolable.

13. Turbine (100) according to any one of claims 11 or 12, wherein the rotor (1) has at least the features according to claim 4, characterized in that a first of the radial bearing (6) between the housing (4) and the shaft (3 ) and a second of the radial bearings (7) between the housing (4) and the bearing portion (22) is arranged, wherein in particular at least one of the radial bearing (6, 7) is formed as a ring having on its outer side an annular groove on its outer surface, wherein in the groove circumferentially offset from each other Ölzuführlöcher

are provided.

14. Turbine (100) according to any one of claims 11 to 13, wherein the rotor (1) has at least the features according to claim 2, characterized in that in the receiving groove (25) at least one sealing ring is arranged directly on the turbine rotor ( 2) and

directly against the housing (4).

15. Turbine (100) according to one of claims 11 to 14, characterized in that the turbine (100) comprises a nut (8), which on the

External thread (32) is screwed and over the the

Working element (5) is fixed to the shaft (3), wherein in particular the working element (5) through the nut (8) to a turbine side (A) facing side of a

Intermediate piece is pressed, in particular, the shaft (3) having a radially extending

Protrusion is pressed against a working side (B) of the intermediate piece facing side of the intermediate piece.

16. Turbine (100) according to claim 15, characterized in that the shaft (3) on its turbine side (A) with a fixing device (33) forming the axial fixing section at least 1.5 times the diameter of the external thread (32) protrudes beyond the external thread (32) or that the fixing device (33) is provided as a cavity in the shaft (3), which in the axial direction

at least 1 times the diameter of the external thread (32) extends radially inside the shaft (3).

17. A method for producing a rotor (1) according to one of claims 1 to 10, characterized in that the hollow cylinder portion (31) of the shaft (3) on the

Cylinder portion (21) of the turbine rotor (2) is pushed to connect shaft (3) and turbine rotor (2) to each other, while the shaft (3) is kept heated to at least 300 ° C, in particular 350 ° C to 450 ° C, and while the turbine rotor (2) is maintained at a temperature between 10 ° C and 50 ° C, in particular between 15 ° C and 40 ° C, in particular is kept at room temperature.

18. A method for producing a rotor (1) according to any one of claims 4 to 10, characterized in that the hollow cylinder portion (31) of the shaft (3) on the

Cylinder portion (21) of the turbine rotor (2) is pushed until it with its axial end face against the

Turbine rotor (2), in particular against the bearing section

(22) of the turbine rotor (2) presses, wherein in particular after the fixation of turbine rotor (2) and shaft (3) to each other, the rotor (1) in the region of

Hollow cylinder section (31) and the bearing section (22) is ground by a single grinding operation to produce in this area a uniform diameter of the rotor (1).

19. A method for producing a rotor (1) according to

Claim 18, characterized in that after the fixation of turbine rotor (2) and shaft (3) to each other by means of a grinding process such

Outside contour of the rotor (1) is generated that the

Diameter of the turbine rotor starting from the to

Turbine side (A) facing end of the hollow cylinder portion (31) has such a course in the axial direction, that the diameter initially decreases in the axial direction to the turbine side (A) and then increases until it is greater than at the turbine side (A) facing

End of the hollow cylinder section (31), wherein in particular the profile of the diameter of the turbine rotor (2) between the turbine side (A) facing the end of the

Bearing portion (22) is.

20. A method for producing a turbine (100) according to any one of claims 11 to 16, characterized in that introduced in a first step, the rotor (1) with its working side (B) in the housing (4) and through the housing (4 ), in a second

Step the work element (5) from the working side (B) on the rotor (1) is pushed, wherein in one third step, the nut (8) from the working side (B) on the external thread (32) is screwed while the rotor (1) from the working side (B) on the

Fixing device (33) is held against rotation.