EP3702589B1 - Steam expander and valve shaft guide for a steam expander - Google Patents

Steam expander and valve shaft guide for a steam expander Download PDF

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Publication number
EP3702589B1
EP3702589B1 EP20150411.5A EP20150411A EP3702589B1 EP 3702589 B1 EP3702589 B1 EP 3702589B1 EP 20150411 A EP20150411 A EP 20150411A EP 3702589 B1 EP3702589 B1 EP 3702589B1
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EP
European Patent Office
Prior art keywords
valve
housing
valve seat
valve shaft
opening
Prior art date
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Application number
EP20150411.5A
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German (de)
French (fr)
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EP3702589A1 (en
Inventor
Richard Langlechner
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Langlechner GmbH and Co KG
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Langlechner GmbH and Co KG
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Publication of EP3702589A1 publication Critical patent/EP3702589A1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/08—Valves guides; Sealing of valve stem, e.g. sealing by lubricant
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B29/00—Machines or engines with pertinent characteristics other than those provided for in preceding main groups
    • F01B29/08—Reciprocating-piston machines or engines not otherwise provided for
    • F01B29/10—Engines
    • F01B29/12—Steam engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2303/00—Manufacturing of components used in valve arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2820/00—Details on specific features characterising valve gear arrangements
    • F01L2820/01—Absolute values

Definitions

  • the present invention relates to a valve stem guide for a steam expander according to the preamble of claim 1, and to a steam expander with such a valve stem guide.
  • Generic valve stem guides are used to guide the valve stem of an inlet valve or outlet valve of a steam expander in a piston engine design, also known as a steam engine.
  • a valve stem has an end region on the valve body side and an end region remote therefrom and correspondingly remote from the valve body, between which the region of the valve stem guided by means of the valve stem guide generally extends.
  • the end area of the valve stem on the valve body side carries and/or actuates a valve body which, together with a valve seat of the valve, opens and closes an inlet or an outlet for the working medium steam of the steam expander, so that it can enter or leave the cylinder chamber in individual cycles (strokes). of the vapor expander depending on whether it is an inlet valve or an outlet valve.
  • the valve stem guide is often provided with or formed by a sliding bushing which is inserted into a housing, for example a crankcase, of the steam expander.
  • a housing for example a crankcase
  • the insertion is done by producing a press fit, that is, constructing a so-called interference fit between the sliding bush and the housing surrounding it, in order to achieve a non-positive connection.
  • the housing is provided with an opening, in particular a bore, for the sliding bush and the sliding bush is greatly cooled before it is inserted, the housing being able to be heated at the same time, so that the sliding bush contracts and the opening in the housing in particular widens, so that the sliding bush can be inserted into the opening. after one Temperature equalization between the sliding bush and the housing results in the desired press fit.
  • valve stem guide is based on a solution that has been customary in practice for many decades, in practice in recent years there have been irregularly occurring efficiency losses in the operation of steam expanders, the cause of which was initially unclear. After there was also damage to the inlet valves and outlet valves, which led to a failure of the steam expander, investigations have shown that the opening and closing behavior of individual inlet valves and outlet valves has changed during operation of the steam expander.
  • DE 10 2014 218 365 A1 the aforementioned problems are due to the fact that the press fit of the sliding bushing in the housing temporarily loosened due to temperature expansion of the housing, so that the sliding bushing could be displaced within the housing when the sliding bushing was subjected to force via the frictional forces of the valve stem. As the temperature conditions changed during further operation, the press fit was re-established, but now with a different position of the sliding bush within the housing.
  • DE 10 2014 218 365 A1 therefore proposes to screw the bushing into the housing, directly or indirectly. The indirect screwing can be done by screwing the slide bushing into a valve seat ring.
  • the documents KR 101 193 713 B1 and DE 22 16 512 A1 disclose valve guides in which the slide bushing is inserted into the valve seat. .
  • the present invention is based on the object of specifying a valve stem guide for a steam expander which avoids the problem of wear and leakage in the area of the valve seat ring.
  • the valve stem guide should be characterized by a particularly reliable operation of the corresponding valves with a long service life.
  • valve stem guide having the features of claim 1.
  • Advantageous and particularly expedient configurations and a steam expander according to the invention with such a valve stem guide are specified in the dependent claims.
  • a valve stem guide according to the invention for a steam expander has a housing which is, for example, part of the crankcase of the steam expander.
  • An opening running in the housing is provided for receiving a valve stem, the opening running in particular in the direction of a longitudinal axis of the housing.
  • a slide bushing is inserted into the opening, which bushing has an inner guide surface for forming a slide bearing for the valve stem.
  • the valve stem can thus slide with its outer surface directly on the inner guide surface of the sliding bush, with a material pairing advantageously being selected at this interface or this sliding bearing that offers favorable lubricating properties.
  • the bushing is made of brass and the housing is made of steel.
  • the sliding bush is screwed into the housing either directly, i.e. the sliding bush and the housing each have a thread, with the two threads being in engagement with one another, or indirectly, i.e. the sliding bush having a thread which a thread of a counter element cooperates, which in turn is locked in place in the housing.
  • the sliding bushing is only plugged into the valve seat ring, that is to say it is plugged in without a screw connection.
  • the sliding bushing is inserted loosely into the valve seat ring, ie with play between the sliding bushing and the valve seat ring.
  • the valve seat ring has, for example, a central bore that has a diameter that is larger than the outer diameter of the sliding bush, at least in the end facing the valve seat ring.
  • the diameter of the bore in the valve seat ring is at least 1/100 mm or 1/10 mm larger than the outer diameter of the sliding bush.
  • the sliding bush By (loosely) inserting the sliding bush into the valve seat ring, the sliding bush is guided laterally, in particular over the entire circumference at its end facing the valve seat ring, so that leverage forces previously acting on the sliding bush are safely dissipated without bending the sliding bush.
  • the slide bushing in the area of the end facing the valve seat ring is surrounded on the one hand by the material of the valve seat ring and on the other hand surrounded by the material of the housing adjacent to the valve seat ring. Accordingly, no free space remains radially outside of the sliding bush within the housing.
  • the sliding bush carries an external thread on an outer surface, by means of which the sliding bush is screwed into an internal thread provided in the opening.
  • the external thread on the sliding bush extends over only part of the axial length of the sliding bush. This is beneficial in order to reduce an undesirable introduction of force into the thread as a result of thermal expansion over the length of the thread.
  • the internal thread also extends in the housing only over part of the axial extent of the sliding bush or of the axial section which faces the sliding bush in the opening.
  • the sliding bush has a stop, by means of which it strikes the housing when the sliding bush is screwed into the housing or when the sliding bush is screwed into the housing.
  • the stop can be designed, for example, in the form of a collar protruding in the radial direction on the sliding bush. The stop strikes, for example, on the face side against a surface of the housing surrounding the opening.
  • the sliding bush can have a carrier profile on one axial end.
  • the driver profile can have the shape of an external hexagon, for example.
  • other profiles are also possible, for example an internal drive such as a hexagon socket or torx (hexalobular socket).
  • Other external drives are also possible.
  • the carrier profile is provided on the axial end of the sliding bush, on which the external thread and in particular the stop is positioned.
  • valve seat ring used according to the invention coaxially with the sliding bush in the housing preferably forms a valve seat for the inlet valve or outlet valve, to which the valve stem is assigned.
  • the valve stem carries, for example, as initially described, a valve body at its axial end, which is advantageously more or less enclosed by the valve seat ring, which then, together with the valve seat, more or less restricts the opening cross section of the valve depending on the relative position of the valve body to the valve seat .
  • the opening in the housing can be expanded in steps at its axial end facing the valve seat ring, so that the diameter of the opening increases in one step to a comparatively larger diameter, which is adapted to the outside diameter of the valve seat ring.
  • the valve seat ring can be pressed into the opening in the housing, ie an undersized fit is provided between the outside diameter of the valve seat ring and the inside diameter of the opening, in particular the extension in the opening.
  • valve stem guides in a steam expander it is not absolutely necessary for all valve stem guides in a steam expander to be designed with slide bushings inserted into the valve seat inserts. Rather, only part of the valve stem guides can be designed accordingly, whereas in another part of the valve stem guides an axial gap is provided between the valve seat ring and the slide bush, namely in those valve stem guides on which a lower leverage acts.
  • a steam expander has at least one cylinder or a plurality of cylinders, for example two cylinders, each having a Have cylinder space and a cylinder piston.
  • the cylinder piston is displaced by steam expansion in the cylinder chamber and can drive a crankshaft.
  • the or each cylinder space is connected via an inlet valve to a vapor supply of the vapor expander and via an outlet valve to a vapor outlet of the vapor expander.
  • At least one inlet valve which blocks the steam supply after the cylinder chamber has been filled with steam, and/or an exhaust valve, which blocks the steam discharge after the steam has been discharged from the cylinder chamber, has/have a valve seat, a valve body and a valve body on the valve body for its movement relative to the valve seat connected valve stem, which is slidably mounted in a valve stem guide according to the invention.
  • FIG. 1 the area of an inlet valve 15 of a vapor expander is shown.
  • the inlet valve 15 opens and closes the flow cross-section for steam of a steam supply 18, via which the steam is conducted into the cylinder space 19 of the steam expander.
  • the expanding steam moves the cylinder piston 20 along the cylinder liner 21 and thus drives a piston rod 22, not shown in detail here crankshaft on.
  • the cylinder liner 21 forms a pairing with the outer surface 23 of the cylinder piston 20 that is optimized with regard to the sliding properties. However, this is not absolutely necessary, rather the cylinder piston 20 could also slide directly on a surface of the housing 1 .
  • a slide bushing 5 is also inserted into the housing 1, in which the valve stem 4 of the inlet valve 15 slides.
  • the sliding bushing 5 has sliding elements 24 inserted, which form a sliding bearing for the valve stem 4 .
  • the sliding elements 24 have a guide surface 6 for the valve stem 4 .
  • this is not absolutely necessary, rather the valve stem 4 could also slide directly in the base body of the sliding bush 5 so that the inner surface 25 would form the guide surface for the valve stem 4 .
  • the valve stem 4 carries the valve body 17 at one axial end, which cooperates with the valve seat 12 in order to adjust the flow cross-section in the vapor supply 18 by varying the distance between the valve body 17 and the valve seat 12 .
  • the valve seat 12 is formed here by a valve seat ring 11 which is inserted into the housing 1, but could also be implemented directly in the housing 1.
  • the slide bushing 5 is not extended to the valve seat ring 11 and inserted into it, but rather a distance is provided between the slide bushing 5 and the valve seat ring 11 .
  • the other features shown here can also be provided in a valve stem guide designed according to the invention.
  • a spring element 26 which acts here to close the inlet valve 15 .
  • the inlet valve 15 by applying a force by means of a not shown here Camshaft are opened on the valve stem 4 against the force of the spring element 26, here in the form of a compression spring.
  • the sliding bush 5 has an external thread 8 over a partial area of the axial section of the outer surface 7 inserted into the opening 3 in the housing 1, here over significantly less than half the axial length of the inserted outer surface 7, which thread into an internal thread 9 in the opening 3 is screwed in in such a way that the sliding bushing 5 with the protruding collar 27 strikes and is braced against an end face of the housing in the axial direction of the opening 3 .
  • This also prevents the slide bush 5 from slipping within the opening 3 when the housing 1 is heated more in the area of the opening 3 due to the proximity to the cylinder chamber 19 and the steam supply 18 than the slide bush 5 used and is therefore subject to greater thermal expansion.
  • valve stem guides of the steam expander are shown, the two middle valve stem guides shown being designed according to the invention, while the two outer ones are different.
  • Corresponding elements are numbered with corresponding reference characters.
  • sliding bushes 5 In the embodiment according to figure 2 Four openings 3 with inserted sliding bushes 5 are provided, with the two middle ones serving to guide the valve stem 4 of an intake valve 15 and the two outer ones to guide a valve stem 4 of exhaust valves 16.
  • the sliding bushes 5 in turn have a collar 27 as a stop, for Tensioning of the respective sliding bush 5 in the housing 1 when the sliding bush 5 is screwed with its external thread 8 into the internal thread 9 in the opening 3.
  • a driver profile 10 for example in the form of an external hexagon, which offers a drive for screwing the sliding bush 5 into the housing 1 .
  • valve seat ring 11 is inserted into the opening 3 next to the sliding bush 5, which forms a valve seat 12.
  • the shape largely corresponds to that of the valve seat ring 11 according to FIG figure 1 .
  • the valve stem guide has an axial gap 14 between the slide bushings 5 and the valve seat rings 11 .
  • the two inner valve seat rings 11, on the other hand, have a significantly greater axial extension (extension in the direction of the longitudinal axis 2) and, in contrast to the outer valve seat rings 11, are not flush with the housing 1, but protrude from it and protrude into an attached cover .
  • Deviating from the representation according to the figure 1 is in the embodiment according to figure 2 the guiding surface 6 of the sliding bushes 5 is formed directly by the inner surface 25 of the sliding bushes 5.
  • the two outer sliding bushes 5 are surrounded only by the housing 1 in the circumferential direction.
  • the two inner slide bushings 5, on the other hand, extend into the respective valve seat ring 11 and are inserted into it.
  • the respective valve seat ring 11 causes a radial guidance of the sliding bush 5 and prevents the same from bending.
  • the sliding bush 5 is inserted "freely" into the valve seat ring 11, without a screw connection or an undercut, so that different thermal expansions of the sliding bush 5 and the valve seat ring 11 or the housing 1 are not impeded and the sliding bush 5 moves in the direction of the longitudinal axis 2 in the Valve seat ring 11 can move.
  • crankshaft 28 is also shown, which is driven by the cylinder pistons, not shown here, via the piston rods.
  • camshaft 29 is also shown, the cam (not in the Individual but only partially shown) actuate the valve stems 4 against the force of the spring elements 26 .
  • the spring elements 26 are supported outside of the collar 27 enclosing it on the front side of the housing 1 .

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Lift Valve (AREA)
  • Details Of Valves (AREA)

Description

Die vorliegende Erfindung betrifft eine Ventilschaftführung für einen Dampfexpander gemäß dem Oberbegriff von Anspruch 1, sowie einen Dampfexpander mit einer solchen Ventilschaftführung.The present invention relates to a valve stem guide for a steam expander according to the preamble of claim 1, and to a steam expander with such a valve stem guide.

Gattungsgemäße Ventilschaftführungen werden dazu verwendet, den Ventilschaft eines Einlassventils oder Auslassventils eines Dampfexpanders in Kolbenmaschinenbauart, auch Dampfmotor genannt, zu führen. Ein solcher Ventilschaft weist einen ventilkörperseitigen Endbereich und einen diesem abgewandten, entsprechend ventilkörperfernen Endbereich auf, zwischen denen sich in der Regel der mittels der Ventilschaftführung geführte Bereich des Ventilschafts erstreckt. Der ventilkörperseitige Endbereich des Ventilschafts trägt und/oder betätigt einen Ventilkörper, der zusammen mit einem Ventilsitz des Ventils einen Einlass oder einen Auslass für das Arbeitsmedium Dampf des Dampfexpanders öffnet und schließt, damit dieses in einzelnen Zyklen (Takten) in den Zylinderraum oder aus dem Zylinderraum des Dampfexpanders strömen kann, je nachdem, ob es sich um ein Einlassventil oder ein Auslassventil handelt.Generic valve stem guides are used to guide the valve stem of an inlet valve or outlet valve of a steam expander in a piston engine design, also known as a steam engine. Such a valve stem has an end region on the valve body side and an end region remote therefrom and correspondingly remote from the valve body, between which the region of the valve stem guided by means of the valve stem guide generally extends. The end area of the valve stem on the valve body side carries and/or actuates a valve body which, together with a valve seat of the valve, opens and closes an inlet or an outlet for the working medium steam of the steam expander, so that it can enter or leave the cylinder chamber in individual cycles (strokes). of the vapor expander depending on whether it is an inlet valve or an outlet valve.

Da an eine solche Ventilschaftführung besondere Gleitanforderungen gestellt werden, wird die Ventilschaftführung häufig mit einer Gleitbuchse versehen oder durch diese gebildet, die in ein Gehäuse, beispielsweise Kurbelgehäuse, des Dampfexpanders eingesetzt ist. Herkömmlich erfolgt das Einsetzen durch Herstellung eines Presssitzes, das heißt das Konstruieren einer sogenannten Übermaßpassung zwischen der Gleitbuchse und des diese umgebenden Gehäuses, um eine kraftschlüssige Verbindung zu erreichen. In der Regel wird das Gehäuse mit einer Öffnung, insbesondere Bohrung, für die Gleitbuchse versehen und die Gleitbuchse wird vor ihrem Einsetzen stark abgekühlt, wobei das Gehäuse gleichzeitig erwärmt werden kann, sodass sich die Gleitbuchse zusammenzieht und die Öffnung in dem Gehäuse insbesondere aufweitet, sodass die Gleitbuchse in die Öffnung eingesetzt werden kann. Nach einem Temperaturausgleich zwischen der Gleitbuchse und dem Gehäuse ergibt sich der gewünschte Presssitz.Since special sliding requirements are placed on such a valve stem guide, the valve stem guide is often provided with or formed by a sliding bushing which is inserted into a housing, for example a crankcase, of the steam expander. Conventionally, the insertion is done by producing a press fit, that is, constructing a so-called interference fit between the sliding bush and the housing surrounding it, in order to achieve a non-positive connection. As a rule, the housing is provided with an opening, in particular a bore, for the sliding bush and the sliding bush is greatly cooled before it is inserted, the housing being able to be heated at the same time, so that the sliding bush contracts and the opening in the housing in particular widens, so that the sliding bush can be inserted into the opening. after one Temperature equalization between the sliding bush and the housing results in the desired press fit.

Obwohl mit dieser Art der Ausführungsform einer Ventilschaftführung auf eine in der Praxis seit vielen Jahrzehnten übliche Lösung zurückgegriffen wurde, haben sich in der Praxis in jüngerer Zeit beim Betrieb von Dampfexpandern unregelmäßig auftretende Wirkungsgradverluste ergeben, deren Ursache zunächst unklar war. Nachdem es zum Teil auch Beschädigungen an den Einlassventilen und Auslassventilen gab, die zu einem Ausfall des Dampfexpanders führten, haben Untersuchungen ergeben, dass sich während des Betriebs des Dampfexpanders das Öffnungsverhalten und Schließverhalten einzelner Einlassventile und Auslassventile geändert hat.Although this type of embodiment of a valve stem guide is based on a solution that has been customary in practice for many decades, in practice in recent years there have been irregularly occurring efficiency losses in the operation of steam expanders, the cause of which was initially unclear. After there was also damage to the inlet valves and outlet valves, which led to a failure of the steam expander, investigations have shown that the opening and closing behavior of individual inlet valves and outlet valves has changed during operation of the steam expander.

Gemäß DE 10 2014 218 365 A1 sind die zuvor genannten Probleme darauf zurückzuführen, dass durch eine Temperaturdehnung des Gehäuses sich der Presssitz der Gleitbuchse im Gehäuse vorübergehend gelöst hat, sodass durch eine Kraftbeaufschlagung der Gleitbuchse über die Reibkräfte des Ventilschafts eine Verlagerung der Gleitbuchse innerhalb des Gehäuses stattfinden konnte. Durch im weiteren Betrieb geänderte Temperaturbedingungen wurde der Presssitz erneut hergestellt, jetzt jedoch mit einer anderen Position der Gleitbuchse innerhalb des Gehäuses. DE 10 2014 218 365 A1 schlägt daher vor, die Gleitbuchse in das Gehäuse einzuschrauben, unmittelbar oder mittelbar. Das mittelbare Einschrauben kann durch Einschrauben der Gleitbuchse in einen Ventilsitzring erfolgen.According to DE 10 2014 218 365 A1 the aforementioned problems are due to the fact that the press fit of the sliding bushing in the housing temporarily loosened due to temperature expansion of the housing, so that the sliding bushing could be displaced within the housing when the sliding bushing was subjected to force via the frictional forces of the valve stem. As the temperature conditions changed during further operation, the press fit was re-established, but now with a different position of the sliding bush within the housing. DE 10 2014 218 365 A1 therefore proposes to screw the bushing into the housing, directly or indirectly. The indirect screwing can be done by screwing the slide bushing into a valve seat ring.

Die in der DE 10 2014 218 365 A1 vorgeschlagene Ausführungsform, bei welcher insbesondere ein Abstand zwischen der Gleitbuchse und dem Ventilsitzring vorgesehen ist, um thermische Relativdehnungen nicht zu behindern, hat sich in der Praxis als anfällig für Verschleiß und nachfolgend eine Undichtigkeit im Bereich des Ventilsitzringes herausgestellt. Die Ursache war zunächst unbekannt.The one in the DE 10 2014 218 365 A1 The proposed embodiment, in which in particular a distance is provided between the sliding bush and the valve seat ring so as not to impede relative thermal expansion, has proven in practice to be susceptible to wear and subsequent leakage in the area of the valve seat ring. The cause was initially unknown.

Die Dokumente KR 101 193 713 B1 und DE 22 16 512 A1 offenbaren Ventilführungen, in denen die Gleitbuchse jeweils in den Ventilsitz eingesteckt ist. . Der vorliegenden Erfindung liegt die Aufgabe zugrunde, eine Ventilschaftführung für einen Dampfexpander anzugeben, welcher das Problem des Verschleißes und der Undichtigkeit im Bereich des Ventilsitzringes vermeidet. Die Ventilschaftführung soll sich durch einen besonders zuverlässigen Betrieb der entsprechenden Ventile mit einer hohen Lebensdauer auszeichnen.The documents KR 101 193 713 B1 and DE 22 16 512 A1 disclose valve guides in which the slide bushing is inserted into the valve seat. . The present invention is based on the object of specifying a valve stem guide for a steam expander which avoids the problem of wear and leakage in the area of the valve seat ring. The valve stem guide should be characterized by a particularly reliable operation of the corresponding valves with a long service life.

Die erfindungsgemäße Aufgabe wird durch eine Ventilschaftführung mit den Merkmalen von Anspruch 1 gelöst. In den abhängigen Ansprüchen sind vorteilhafte und besonders zweckmäßige Ausgestaltungen sowie ein erfindungsgemäßer Dampfexpander mit einer solchen Ventilschaftführung angegeben.The object according to the invention is achieved by a valve stem guide having the features of claim 1. Advantageous and particularly expedient configurations and a steam expander according to the invention with such a valve stem guide are specified in the dependent claims.

Im Einzelnen weist eine erfindungsgemäße Ventilschaftführung für einen Dampfexpander ein Gehäuse auf, das beispielsweise Bestandteil des Kurbelgehäuses des Dampfexpanders ist. Es ist eine im Gehäuse verlaufende Öffnung zur Aufnahme eines Ventilschafts vorgesehen, wobei die Öffnung insbesondere in Richtung einer Längsachse des Gehäuses verläuft.In detail, a valve stem guide according to the invention for a steam expander has a housing which is, for example, part of the crankcase of the steam expander. An opening running in the housing is provided for receiving a valve stem, the opening running in particular in the direction of a longitudinal axis of the housing.

In die Öffnung ist erfindungsgemäß eine Gleitbuchse eingesetzt, die eine innere Führungsfläche zur Ausbildung eines Gleitlagers für den Ventilschaft aufweist. Somit kann der Ventilschaft mit seiner äußeren Oberfläche unmittelbar auf der inneren Führungsoberfläche der Gleitbuchse gleiten, wobei vorteilhaft eine Werkstoffpaarung an dieser Schnittstelle beziehungsweise diesem Gleitlager gewählt wird, die günstige Schmiereigenschaften bietet. Beispielswiese ist die Gleitbuchse aus Messing hergestellt und das Gehäuse aus Stahl.According to the invention, a slide bushing is inserted into the opening, which bushing has an inner guide surface for forming a slide bearing for the valve stem. The valve stem can thus slide with its outer surface directly on the inner guide surface of the sliding bush, with a material pairing advantageously being selected at this interface or this sliding bearing that offers favorable lubricating properties. For example, the bushing is made of brass and the housing is made of steel.

Erfindungsgemäß ist die Gleitbuchse in das Gehäuse eingeschraubt, entweder unmittelbar, das heißt, dass die Gleitbuchse und das Gehäuse jeweils ein Gewinde aufweisen, wobei die beiden Gewinde miteinander im Eingriff stehen, oder mittelbar, das heißt, dass die Gleitbuchse ein Gewinde aufweist, das mit einem Gewinde eines Konterelementes zusammenarbeitet, das wiederum ortsfest im Gehäuse verriegelt ist.According to the invention, the sliding bush is screwed into the housing either directly, i.e. the sliding bush and the housing each have a thread, with the two threads being in engagement with one another, or indirectly, i.e. the sliding bush having a thread which a thread of a counter element cooperates, which in turn is locked in place in the housing.

Erfindungsgemäß ist die Gleitbuchse in den Ventilsitzring nur eingesteckt, das heißt frei von einer Verschraubung eingesteckt. Insbesondere ist die Gleitbuchse lose in den Ventilsitzring eingesteckt, also mit einem Spiel zwischen der Gleitbuchse und dem Ventilsitzring.According to the invention, the sliding bushing is only plugged into the valve seat ring, that is to say it is plugged in without a screw connection. In particular, the sliding bushing is inserted loosely into the valve seat ring, ie with play between the sliding bushing and the valve seat ring.

Der Ventilsitzring weist beispielsweise eine zentrale Bohrung auf, die einen Durchmesser aufweist, der größer ist als der Außendurchmesser der Gleitbuchse, zumindest in dem dem Ventilsitzring zugewandten Ende. Beispielsweise ist der Durchmesser der Bohrung im Ventilsitzring um wenigstens 1/100 mm oder 1/10 mm größer als der Außendurchmesser der Gleitbuchse.The valve seat ring has, for example, a central bore that has a diameter that is larger than the outer diameter of the sliding bush, at least in the end facing the valve seat ring. For example, the diameter of the bore in the valve seat ring is at least 1/100 mm or 1/10 mm larger than the outer diameter of the sliding bush.

Durch das (lose) Einstecken der Gleitbuchse in den Ventilsitzring wird die Gleitbuchse seitlich, insbesondere vollumfänglich an ihrem dem Ventilsitzring zugewandten Ende geführt, sodass bisher auf die Gleitbuchse wirkende Hebelkräfte sicher ohne Verbiegung der Gleitbuchse abgeleitet werden. Insbesondere wird die Gleitbuchse im Bereich des dem Ventilsitzring zugewandten Endes zum einen vom Material des Ventilsitzrings umschlossen und zum anderen angrenzend an den Ventilsitzring vom Material des Gehäuses umschlossen. Es verbleibt demnach kein Freiraum radial außerhalb der Gleitbuchse innerhalb des Gehäuses.By (loosely) inserting the sliding bush into the valve seat ring, the sliding bush is guided laterally, in particular over the entire circumference at its end facing the valve seat ring, so that leverage forces previously acting on the sliding bush are safely dissipated without bending the sliding bush. In particular, the slide bushing in the area of the end facing the valve seat ring is surrounded on the one hand by the material of the valve seat ring and on the other hand surrounded by the material of the housing adjacent to the valve seat ring. Accordingly, no free space remains radially outside of the sliding bush within the housing.

Gemäß einer vorteilhaften Ausführungsform der Erfindung trägt die Gleitbuchse auf einer äußeren Oberfläche ein Außengewinde, mittels welchem die Gleitbuchse in ein in der Öffnung vorgesehenes Innengewinde eingeschraubt ist. Vorteilhaft erstreckt sich das Außengewinde auf der Gleitbuchse nur über einen Teil der axialen Länge der Gleitbuchse. Dies ist günstig, um eine unerwünschte Krafteinleitung in das Gewinde infolge thermischer Dehnungen über der Gewindelänge zu reduzieren. Insbesondere erstreckt sich auch das Innengewinde in dem Gehäuse nur über einen Teil der axialen Erstreckung der Gleitbuchse beziehungsweise des axialen Abschnitts, welchem die Gleitbuchse in der Öffnung gegenübersteht.According to an advantageous embodiment of the invention, the sliding bush carries an external thread on an outer surface, by means of which the sliding bush is screwed into an internal thread provided in the opening. Advantageously, the external thread on the sliding bush extends over only part of the axial length of the sliding bush. This is beneficial in order to reduce an undesirable introduction of force into the thread as a result of thermal expansion over the length of the thread. In particular, the internal thread also extends in the housing only over part of the axial extent of the sliding bush or of the axial section which faces the sliding bush in the opening.

Gemäß einer vorteilhaften Ausführungsform weist die Gleitbuchse einen Anschlag auf, mittels welchem sie beim Einschrauben der Gleitbuchse in das Gehäuse beziehungsweise im eingeschraubten Zustand der Gleitbuchse in dem Gehäuse am Gehäuse anschlägt. Der Anschlag kann beispielsweise in Form eines in Radialrichtung auf der Gleitbuchse hervorstehenden Bundes ausgeführt sein. Der Anschlag schlägt beispielsweise stirnseitig an einer die Öffnung umschließenden Fläche des Gehäuses an.According to an advantageous embodiment, the sliding bush has a stop, by means of which it strikes the housing when the sliding bush is screwed into the housing or when the sliding bush is screwed into the housing. The stop can be designed, for example, in the form of a collar protruding in the radial direction on the sliding bush. The stop strikes, for example, on the face side against a surface of the housing surrounding the opening.

Im Hinblick auf die im Betrieb auftretenden thermischen Dehnungen ist es besonders günstig, wenn das Außengewinde auf der Gleitbuchse in Axialrichtung an den Anschlag angrenzt. Hierdurch kann die Gefahr eines Lösens einer durch Einschrauben in das Gehäuse verspannten Gleitbuchse minimiert werden und nachteilige thermische Dehnungen in dem Gewinde werden reduziert.With regard to the thermal expansions that occur during operation, it is particularly advantageous if the external thread on the sliding bush is adjacent to the stop in the axial direction. As a result, the risk of loosening of a slide bush that has been clamped by being screwed into the housing can be minimized and disadvantageous thermal expansions in the thread are reduced.

Um die Gleitbuchse in das Gehäuse einschrauben zu können und insbesondere mit ihrem Anschlag gegen das Gehäuse verspannen zu können, kann die Gleitbuchse an einem axialen Ende ein Mitnahmeprofil aufweisen. Das Mitnahmeprofil kann beispielsweise die Form eines Außensechskants aufweisen. Jedoch sind auch andere Profile möglich, beispielsweise ein Innenantrieb wie Innensechskant oder Torx (Innensechsrund). Auch andere Außenantriebe sind möglich.In order to be able to screw the sliding bush into the housing and in particular to be able to brace it against the housing with its stop, the sliding bush can have a carrier profile on one axial end. The driver profile can have the shape of an external hexagon, for example. However, other profiles are also possible, for example an internal drive such as a hexagon socket or torx (hexalobular socket). Other external drives are also possible.

Gemäß einer Ausführungsform ist das Mitnahmeprofil an dem axialen Ende der Gleitbuchse vorgesehen, an dem das Außengewinde und insbesondere der Anschlag positioniert ist.According to one embodiment, the carrier profile is provided on the axial end of the sliding bush, on which the external thread and in particular the stop is positioned.

Der gemäß der Erfindung koaxial zur Gleitbuchse im Gehäuse eingesetzte Ventilsitzring bildet bevorzugt einen Ventilsitz für das Einlassventil oder Auslassventil aus, welchem der Ventilschaft zugeordnet ist. Der Ventilschaft trägt beispielsweise, wie eingangs dargestellt, an seinem axialen Ende, das vorteilhaft vom Ventilsitzring mehr oder minder umschlossen wird, einen Ventilkörper, der dann zusammen mit dem Ventilsitz den Öffnungsquerschnitt des Ventils in Abhängigkeit der relativen Position des Ventilkörpers zum Ventilsitz mehr oder minder beschränkt.The valve seat ring used according to the invention coaxially with the sliding bush in the housing preferably forms a valve seat for the inlet valve or outlet valve, to which the valve stem is assigned. The valve stem carries, for example, as initially described, a valve body at its axial end, which is advantageously more or less enclosed by the valve seat ring, which then, together with the valve seat, more or less restricts the opening cross section of the valve depending on the relative position of the valve body to the valve seat .

Um den Ventilsitzring aufzunehmen, kann die Öffnung im Gehäuse an ihrem dem Ventilsitzring zugewandten axialen Ende stufenförmig erweitert ausgeführt sein, sodass sich der Durchmesser der Öffnung in einer Stufe auf einen vergleichsweise größeren Durchmesser erweitert, der dem Außendurchmesser des Ventilsitzringes angepasst ist. Der Ventilsitzring kann gemäß einer Ausführungsform in die Öffnung im Gehäuse eingepresst sein, das heißt zwischen dem Außendurchmesser des Ventilsitzringes und dem Innendurchmesser der Öffnung, insbesondere der Erweiterung in der Öffnung ist eine Untermaßpassung vorgesehen. Jedoch ist es auch möglich, den Ventilsitzring anders in das Gehäuse einzubringen, beispielsweise einzukleben, zu verstemmen, anzuschweißen oder einzuschrauben.In order to accommodate the valve seat ring, the opening in the housing can be expanded in steps at its axial end facing the valve seat ring, so that the diameter of the opening increases in one step to a comparatively larger diameter, which is adapted to the outside diameter of the valve seat ring. According to one embodiment, the valve seat ring can be pressed into the opening in the housing, ie an undersized fit is provided between the outside diameter of the valve seat ring and the inside diameter of the opening, in particular the extension in the opening. However, it is also possible to introduce the valve seat ring into the housing in a different way, for example by gluing, caulking, welding or screwing.

Es ist nicht zwingend notwendig, dass in einem Dampfexpander alle Ventilschaftführungen mit in die Ventilsitzringe eingesteckten Gleitbuchsen ausgeführt sind. Vielmehr kann nur ein Teil der Ventilschaftführungen entsprechend ausgeführt sein, wohingegen bei einem anderen Teil der Ventilschaftführungen ein Axialspalt zwischen dem Ventilsitzring und der Gleitbuchse vorgesehen ist, nämlich bei solchen Ventilschaftführungen, auf die eine geringere Hebelkraft wirkt.It is not absolutely necessary for all valve stem guides in a steam expander to be designed with slide bushings inserted into the valve seat inserts. Rather, only part of the valve stem guides can be designed accordingly, whereas in another part of the valve stem guides an axial gap is provided between the valve seat ring and the slide bush, namely in those valve stem guides on which a lower leverage acts.

Ein erfindungsgemäßer Dampfexpander weist wenigstens einen Zylinder oder eine Vielzahl von Zylindern, beispielsweise zwei Zylinder, auf, die jeweils einen Zylinderraum und einen Zylinderkolben aufweisen. Durch Dampfexpansion in dem Zylinderraum wird der Zylinderkolben verschoben und kann eine Kurbelwelle antreiben.A steam expander according to the invention has at least one cylinder or a plurality of cylinders, for example two cylinders, each having a Have cylinder space and a cylinder piston. The cylinder piston is displaced by steam expansion in the cylinder chamber and can drive a crankshaft.

Der oder jeder Zylinderraum ist über ein Einlassventil mit einer Dampfzufuhr des Dampfexpanders und über ein Auslassventil mit einer Dampfabfuhr des Dampfexpanders verbunden. Wenigstens ein Einlassventil, das die Dampfzufuhr nach dem Befüllen des Zylinderraumes mit Dampf absperrt, und/oder ein Auslassventil, das die Dampfabfuhr nach dem Abführen des Dampfes aus dem Zylinderraum versperrt, weist/weisen einen Ventilsitz, einen Ventilkörper und einen am Ventilkörper zu dessen Bewegung relativ zum Ventilsitz angeschlossenen Ventilschaft auf, der in einer erfindungsgemäßen Ventilschaftführung gleitbar gelagert ist.The or each cylinder space is connected via an inlet valve to a vapor supply of the vapor expander and via an outlet valve to a vapor outlet of the vapor expander. At least one inlet valve, which blocks the steam supply after the cylinder chamber has been filled with steam, and/or an exhaust valve, which blocks the steam discharge after the steam has been discharged from the cylinder chamber, has/have a valve seat, a valve body and a valve body on the valve body for its movement relative to the valve seat connected valve stem, which is slidably mounted in a valve stem guide according to the invention.

Die Erfindung soll nachfolgend anhand von Ausführungsbeispielen und den Figuren exemplarisch erläutert werden.The invention is to be explained below by way of example using exemplary embodiments and the figures.

Es zeigen:

Figur 1
einen Teil eines Dampfexpanders im Bereich des Einlassventils, jedoch noch ohne die erfindungsgemäße Ventilschaftführung;
Figur 2
ein Ausführungsbeispiel eines Dampfexpanders mit zwei erfindungsgemäß ausgeführten Ventilschaftführungen.
Show it:
figure 1
a part of a vapor expander in the area of the intake valve, but still without the valve stem guide according to the invention;
figure 2
an embodiment of a steam expander with two valve stem guides designed according to the invention.

In der Figur 1 ist der Bereich eines Einlassventils 15 eines Dampfexpanders dargestellt. Das Einlassventil 15 öffnet und verschließt den Strömungsquerschnitt für Dampf einer Dampfzufuhr 18, über welche der Dampf in den Zylinderraum 19 des Dampfexpanders geleitet wird. Im Zylinderraum 19 bewegt der expandierende Dampf den Zylinderkolben 20 entlang der Zylinderbuchse 21 und treibt damit über die Kolbenstange 22 eine hier nicht näher dargestellte Kurbelwelle an. Die Zylinderbuchse 21 bildet mit der äußeren Oberfläche 23 des Zylinderkolbens 20 eine hinsichtlich der Gleiteigenschaften optimierte Paarung. Dies ist jedoch nicht zwingend notwendig, vielmehr könnte der Zylinderkolben 20 auch unmittelbar an einer Oberfläche des Gehäuses 1 gleiten.In the figure 1 the area of an inlet valve 15 of a vapor expander is shown. The inlet valve 15 opens and closes the flow cross-section for steam of a steam supply 18, via which the steam is conducted into the cylinder space 19 of the steam expander. In the cylinder chamber 19, the expanding steam moves the cylinder piston 20 along the cylinder liner 21 and thus drives a piston rod 22, not shown in detail here crankshaft on. The cylinder liner 21 forms a pairing with the outer surface 23 of the cylinder piston 20 that is optimized with regard to the sliding properties. However, this is not absolutely necessary, rather the cylinder piston 20 could also slide directly on a surface of the housing 1 .

In das Gehäuse 1 ist ferner eine Gleitbuchse 5 eingesetzt, in welcher der Ventilschaft 4 des Einlassventils 15 gleitet. Im gezeigten Ausführungsbeispiel weist die Gleitbuchse 5 eingesetzte Gleitelemente 24 auf, die ein Gleitlager für den Ventilschaft 4 bilden. Demnach weisen die Gleitelemente 24 eine Führungsoberfläche 6 für den Ventilschaft 4 auf. Dies ist jedoch nicht zwingend notwendig, vielmehr könnte der Ventilschaft 4 auch unmittelbar im Grundkörper der Gleitbuchse 5 gleiten, sodass die innere Oberfläche 25 die Führungsoberfläche für den Ventilschaft 4 bilden würde.A slide bushing 5 is also inserted into the housing 1, in which the valve stem 4 of the inlet valve 15 slides. In the exemplary embodiment shown, the sliding bushing 5 has sliding elements 24 inserted, which form a sliding bearing for the valve stem 4 . Accordingly, the sliding elements 24 have a guide surface 6 for the valve stem 4 . However, this is not absolutely necessary, rather the valve stem 4 could also slide directly in the base body of the sliding bush 5 so that the inner surface 25 would form the guide surface for the valve stem 4 .

Der Ventilschaft 4 trägt an einem axialen Ende den Ventilkörper 17, der mit dem Ventilsitz 12 zusammenarbeitet, um durch Variieren des Abstands des Ventilkörpers 17 zum Ventilsitz 12 den Strömungsquerschnitt in der Dampfzufuhr 18 einzustellen. Der Ventilsitz 12 wird hier durch einen Ventilsitzring 11, der in das Gehäuse 1 eingesetzt ist, gebildet, könnte jedoch auch unmittelbar im Gehäuse 1 ausgeführt sein.The valve stem 4 carries the valve body 17 at one axial end, which cooperates with the valve seat 12 in order to adjust the flow cross-section in the vapor supply 18 by varying the distance between the valve body 17 and the valve seat 12 . The valve seat 12 is formed here by a valve seat ring 11 which is inserted into the housing 1, but could also be implemented directly in the housing 1.

Abweichend von der vorliegenden Erfindung ist die Gleitbuchse 5 nicht bis zum Ventilsitzring 11 verlängert und in diesen eingesteckt, sondern es ist ein Abstand zwischen der Gleitbuchse 5 und dem Ventilsitzring 11 vorgesehen. Die übrigen hier dargestellten Merkmale können jedoch auch bei einer erfindungsgemäß ausgeführten Ventilschaftführung vorgesehen werden.Deviating from the present invention, the slide bushing 5 is not extended to the valve seat ring 11 and inserted into it, but rather a distance is provided between the slide bushing 5 and the valve seat ring 11 . However, the other features shown here can also be provided in a valve stem guide designed according to the invention.

Am anderen Ende des Ventilschafts 4 ist ein Federelement 26 vorgesehen, das hier im Sinne eines Schließens des Einlassventils 15 wirkt. Somit kann das Einlassventil 15 durch Aufbringen einer Kraft mittels einer hier nicht dargestellten Nockenwelle auf den Ventilschaft 4 entgegen der Kraft des Federelementes 26, hier in Form einer Druckfeder, geöffnet werden.At the other end of the valve stem 4 there is a spring element 26 which acts here to close the inlet valve 15 . Thus, the inlet valve 15 by applying a force by means of a not shown here Camshaft are opened on the valve stem 4 against the force of the spring element 26, here in the form of a compression spring.

Die Gleitbuchse 5 weist über einen Teilbereich des axialen Abschnitts der in die Öffnung 3 im Gehäuse 1 eingefügten äußeren Oberfläche 7, hier über deutlich weniger als die halbe axiale Länge der eingefügten äußeren Oberfläche 7 ein Außengewinde 8 auf, das in ein Innengewinde 9 in der Öffnung 3 eingeschraubt ist, und zwar derart, dass die Gleitbuchse 5 mit dem vorstehenden Bund 27 an einer Stirnseite des Gehäuses in Axialrichtung der Öffnung 3 anschlägt und verspannt ist. Hierdurch wird auch dann ein Verrutschen der Gleitbuchse 5 innerhalb der Öffnung 3 verhindert, wenn das Gehäuse 1 im Bereich der Öffnung 3 aufgrund der Nähe zum Zylinderraum 19 und zur Dampfzufuhr 18 stärker erwärmt wird als die eingesetzte Gleitbuchse 5 und damit einer stärkeren Wärmedehnung unterliegt.The sliding bush 5 has an external thread 8 over a partial area of the axial section of the outer surface 7 inserted into the opening 3 in the housing 1, here over significantly less than half the axial length of the inserted outer surface 7, which thread into an internal thread 9 in the opening 3 is screwed in in such a way that the sliding bushing 5 with the protruding collar 27 strikes and is braced against an end face of the housing in the axial direction of the opening 3 . This also prevents the slide bush 5 from slipping within the opening 3 when the housing 1 is heated more in the area of the opening 3 due to the proximity to the cylinder chamber 19 and the steam supply 18 than the slide bush 5 used and is therefore subject to greater thermal expansion.

In der Figur 2 sind weitere Ventilschaftführungen des Dampfexpanders gezeigt, wobei die beiden mittleren dargestellten Ventilschaftführungen erfindungsgemäß ausgeführt sind, die beiden äußeren hingegen abweichend. Sich entsprechende Elemente sind mit sich entsprechenden Bezugszeichen beziffert.In the figure 2 further valve stem guides of the steam expander are shown, the two middle valve stem guides shown being designed according to the invention, while the two outer ones are different. Corresponding elements are numbered with corresponding reference characters.

Beim Ausführungsbeispiel gemäß der Figur 2 sind vier Öffnungen 3 mit eingesetzten Gleitbuchsen 5 vorgesehen, wobei die beiden mittleren zur Führung des Ventilschafts 4 jeweils eines Einlassventils 15 dienen und die beiden äußeren zur Führung eines Ventilschafts 4 von Auslassventilen 16. Die Gleitbuchsen 5 weisen wiederum einen Bund 27 als Anschlag auf, zum Verspannen der jeweiligen Gleitbuchse 5 im Gehäuse 1, wenn die Gleitbuchse 5 mit ihrem Außengewinde 8 in das Innengewinde 9 in der Öffnung 3 eingeschraubt wird. Im Bereich des axialen Endes der Gleitbuchse 5 mit dem Bund 27 ist ein Mitnahmeprofil 10, beispielsweise in Form eines Außensechskants, vorgesehen, der einen Antrieb zum Einschrauben der Gleitbuchse 5 in das Gehäuse 1 bietet.In the embodiment according to figure 2 Four openings 3 with inserted sliding bushes 5 are provided, with the two middle ones serving to guide the valve stem 4 of an intake valve 15 and the two outer ones to guide a valve stem 4 of exhaust valves 16. The sliding bushes 5 in turn have a collar 27 as a stop, for Tensioning of the respective sliding bush 5 in the housing 1 when the sliding bush 5 is screwed with its external thread 8 into the internal thread 9 in the opening 3. In the area of the axial end of the sliding bush 5 with the collar 27 there is a driver profile 10 , for example in the form of an external hexagon, which offers a drive for screwing the sliding bush 5 into the housing 1 .

In Richtung der Längsachse 2 jeder Öffnung 3 ist neben der Gleitbuchse 5 ein Ventilsitzring 11 in die Öffnung 3 eingefügt, der einen Ventilsitz 12 ausbildet. Bei den Ventilsitzringen 11, die koaxial zu den Gleitbuchsen 5 der äußeren Öffnungen 3 in das Gehäuse 1 eingesetzt sind, entspricht die Gestalt weitgehend jener des Ventilsitzringes 11 gemäß der Figur 1. Die Ventilschaftführung weist einen Axialspalt 14 zwischen den Gleitbuchsen 5 und den Ventilsitzringen 11 auf. Die beiden inneren Ventilsitzringe 11 hingegen weisen eine deutlich größere axiale Erstreckung (Erstreckung in Richtung der Längsachse 2) auf und schließen im Gegensatz zu den äußeren Ventilsitzringen 11 nicht bündig mit dem Gehäuse 1 ab, sondern stehen aus diesem hervor und ragen in einen aufgesetzten Deckel hinein.In the direction of the longitudinal axis 2 of each opening 3, a valve seat ring 11 is inserted into the opening 3 next to the sliding bush 5, which forms a valve seat 12. In the valve seat rings 11, which are used coaxially to the sliding bushings 5 of the outer openings 3 in the housing 1, the shape largely corresponds to that of the valve seat ring 11 according to FIG figure 1 . The valve stem guide has an axial gap 14 between the slide bushings 5 and the valve seat rings 11 . The two inner valve seat rings 11, on the other hand, have a significantly greater axial extension (extension in the direction of the longitudinal axis 2) and, in contrast to the outer valve seat rings 11, are not flush with the housing 1, but protrude from it and protrude into an attached cover .

Abweichend von der Darstellung gemäß der Figur 1 wird beim Ausführungsbeispiel gemäß der Figur 2 die Führungsoberfläche 6 der Gleitbuchsen 5 unmittelbar durch die innere Oberfläche 25 der Gleitbuchsen 5 gebildet.Deviating from the representation according to the figure 1 is in the embodiment according to figure 2 the guiding surface 6 of the sliding bushes 5 is formed directly by the inner surface 25 of the sliding bushes 5.

Die beiden äußeren Gleitbuchsen 5 werden in Umfangsrichtung nur vom Gehäuse 1 umschlossen. Die beiden inneren Gleitbuchsen 5 hingegen erstrecken sich bis in den jeweiligen Ventilsitzring 11 hinein und sind in diesen eingesteckt. Damit bewirkt der jeweilige Ventilsitzring 11 eine radiale Führung der Gleitbuchse 5 und verhindert ein Verbiegen derselben. Die Gleitbuchse 5 ist dabei "frei" in den Ventilsitzring 11 eingesteckt, ohne eine Verschraubung oder eine Hinterschneidung, sodass unterschiedliche thermische Dehnungen der Gleitbuchse 5 und des Ventilsitzringes 11 beziehungsweise des Gehäuses 1 nicht behindert werden und sich die Gleitbuchse 5 in Richtung der Längsachse 2 im Ventilsitzring 11 bewegen kann.The two outer sliding bushes 5 are surrounded only by the housing 1 in the circumferential direction. The two inner slide bushings 5, on the other hand, extend into the respective valve seat ring 11 and are inserted into it. Thus, the respective valve seat ring 11 causes a radial guidance of the sliding bush 5 and prevents the same from bending. The sliding bush 5 is inserted "freely" into the valve seat ring 11, without a screw connection or an undercut, so that different thermal expansions of the sliding bush 5 and the valve seat ring 11 or the housing 1 are not impeded and the sliding bush 5 moves in the direction of the longitudinal axis 2 in the Valve seat ring 11 can move.

In der Figur 2 ist ferner die Position der Kurbelwelle 28 gezeigt, die durch die hier nicht gezeigten Zylinderkolben über die Kolbenstangen angetrieben wird. Ferner ist auch die Position der Nockenwelle 29 gezeigt, deren Nocken (nicht im Einzelnen sondern nur ansatzweise dargestellt) die Ventilschäfte 4 entgegen der Kraft der Federelemente 26 betätigen. Die Federelemente 26 stützen sich außerhalb des Bundes 27 diesen umschließend stirnseitig am Gehäuse 1 ab.In the figure 2 the position of the crankshaft 28 is also shown, which is driven by the cylinder pistons, not shown here, via the piston rods. Furthermore, the position of the camshaft 29 is also shown, the cam (not in the Individual but only partially shown) actuate the valve stems 4 against the force of the spring elements 26 . The spring elements 26 are supported outside of the collar 27 enclosing it on the front side of the housing 1 .

Claims (9)

  1. Valve shaft guide for a steam expander
    having a housing (1);
    having at least one opening (3) extending in the housing (1) for receiving a valve shaft (4); wherein
    a sliding bushing (5) is inserted into the opening (3), which sliding bushing (5) has an inner guide surface (6) for forming a sliding bearing for the valve shaft (4);
    the sliding bushing (5) is screwed directly or indirectly into the housing (1); wherein
    a valve seat ring (11) is inserted coaxially to the sliding bushing (5) into the opening (3) in the housing (1);
    characterized in that
    the sliding bushing (5) is only plugged into the valve seat ring (11).
  2. Valve shaft guide according to claim 1, characterized in that the sliding bushing (5) has an external thread (8) on an external surface (7), by means of which the sliding bushing (5) is screwed into an internal thread (9) introduced into the opening (3).
  3. Valve shaft guide according to claim 2, characterized in that the external thread (8) and in particular also the internal thread (9) extend only over a part of the axial extent of the opening (3) in the housing (1) and only over a part of the axial extent of the sliding bushing (5).
  4. Valve shaft guide according to claim 3, characterized in that the sliding bushing (5) has a stop, in particular in the form of a collar (27) projecting in the radial direction, with which it abuts against the housing (1) when the sliding bushing (5) is screwed into the housing (1), and in that the external thread (8) adjoins the stop in the axial direction.
  5. Valve shaft guide according to one of the claims 1 to 4, characterized in that the sliding bushing (5) has a driving profile (10) at one axial end, in particular in the form of an external hexagon.
  6. Valve shaft guide according to one of the claims 1 to 5, characterized in that the opening (3) is of step-shaped design, in particular at one of its axial ends, having an extension (13) into which the valve seat ring (11) is inserted.
  7. Valve shaft guide according to claim 6, characterized in that the valve seat ring (11) is pressed into the opening (3), in particular with an interference fit.
  8. Valve shaft guide according to one of claims 1 to 7, characterized in that the sliding bushing (5) is inserted into the valve seat ring (11) with a clearance.
  9. Steam expander
    having at least one or a plurality of cylinders comprising a cylinder chamber (19) and a cylinder piston (20), wherein the cylinder chamber (19) is connected to a steam supply (18) via an inlet valve (15) and an outlet valve (16) is connected to a steam discharge, and at least one inlet valve (15) and/or one outlet valve (16) comprise(s) a valve seat (12), a valve body (17) and a valve shaft (4) which is connected to the valve body (17) for movement thereof relative to the valve seat (12) and which is slidably mounted in a valve shaft guide according to one of claims 1 to 8.
EP20150411.5A 2019-03-01 2020-01-07 Steam expander and valve shaft guide for a steam expander Active EP3702589B1 (en)

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Application Number Priority Date Filing Date Title
DE102019202834.9A DE102019202834A1 (en) 2019-03-01 2019-03-01 Valve stem guide for a steam expander and steam expander

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EP3702589A1 EP3702589A1 (en) 2020-09-02
EP3702589B1 true EP3702589B1 (en) 2022-02-23

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Publication number Priority date Publication date Assignee Title
US6135080A (en) * 1998-12-14 2000-10-24 Kallina; Henry D. Valve guide system and method

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DE102019202834A1 (en) 2020-09-03

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