EP1239137B1 - Piston and cylinders for a Stirling engine - Google Patents

Piston and cylinders for a Stirling engine Download PDF

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Publication number
EP1239137B1
EP1239137B1 EP02400014A EP02400014A EP1239137B1 EP 1239137 B1 EP1239137 B1 EP 1239137B1 EP 02400014 A EP02400014 A EP 02400014A EP 02400014 A EP02400014 A EP 02400014A EP 1239137 B1 EP1239137 B1 EP 1239137B1
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EP
European Patent Office
Prior art keywords
piston
working
stroke
skirt
stirling engine
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Expired - Lifetime
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EP02400014A
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German (de)
French (fr)
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EP1239137A2 (en
EP1239137A3 (en
Inventor
Andreas Baumüller
Andreas Laug
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Cleanergy AB
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Cleanergy AB
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Publication of EP1239137A3 publication Critical patent/EP1239137A3/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G1/00—Hot gas positive-displacement engine plants
    • F02G1/04—Hot gas positive-displacement engine plants of closed-cycle type
    • F02G1/043—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
    • F02G1/053—Component parts or details
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G1/00—Hot gas positive-displacement engine plants
    • F02G1/04—Hot gas positive-displacement engine plants of closed-cycle type
    • F02G1/043—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G2243/00—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes
    • F02G2243/30—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G2244/00—Machines having two pistons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G2244/00—Machines having two pistons
    • F02G2244/02—Single-acting two piston engines
    • F02G2244/06—Single-acting two piston engines of stationary cylinder type
    • F02G2244/10—Single-acting two piston engines of stationary cylinder type having cylinders in V-arrangement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G2270/00—Constructional features
    • F02G2270/40—Piston assemblies
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G2270/00—Constructional features
    • F02G2270/45—Piston rods
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2225/00—Synthetic polymers, e.g. plastics; Rubber
    • F05C2225/04—PTFE [PolyTetraFluorEthylene]

Definitions

  • Stirling engines is particularly advantageous if it is possible to make the service life and service intervals much greater than in conventional gasoline or diesel engines.
  • the invention has for its object to provide a Stirling engine with increased life and larger service intervals.
  • a piston of a Stirling engine with a piston head, with a piston skirt, wherein piston skirt has a lower edge, wherein in the piston skirt at least one annular groove for receiving a piston ring is present, and wherein the piston is coupled via a piston rod, a crosshead and a connecting rod or directly via a connecting rod with a crankshaft, thereby solved in that the distance of the annular groove which is arranged closest to the crankshaft and the lower edge of the piston shaft is between 0.66 x piston stroke and 1.5 x piston stroke, more preferably between 0.9 x piston stroke and 1.1 x piston stroke.
  • This structural design of the piston skirt ensures that the cylinder running surface is completely or almost completely covered by the piston skirt in the region which is swept by the piston ring (s). This improves the heat dissipation.
  • the piston skirt has a sleeve at its end opposite the piston head, so that the length of the piston skirt according to the invention can be achieved by a sleeve which is easy to produce.
  • this embodiment of the invention a per se known piston for a Stirling engine in accordance with the invention can be improved. Since the sleeve, apart from the inertial forces, is not subject to any significant high stresses, it can be made very thin-walled.
  • the Stirling engine according to Fig. 1 has a crankcase 1, in which a crankshaft 3 is rotatably mounted. At a crank pin 5 of the crankshaft 3, a first connecting rod 7 and a second connecting rod 9 are rotatably mounted.
  • the first connecting rod 7 is connected via a first crosshead 10 and a first piston rod 11 with a compression piston 12.
  • the second connecting rod 9 is connected via a second crosshead 13 and a second piston rod 14 with a working piston 15.
  • the structural design of compression piston 12 and piston 15 is in connection with Fig. 1 is not relevant and will therefore not be explained further here.
  • the compression piston 12 runs in a compression cylinder 16, while the working piston 15 is running in a working cylinder 17.
  • the crankshaft 3 and the crank pin 5 are lubricated with oil, while the compression piston 12 and the working piston 15 run dry in the compression cylinder 16 or in the working cylinder 17.
  • the working gas can be pushed back and forth. It takes in the Fig. 1 Not shown working gas when moving from the compression cylinder 16 in the working cylinder 17 heat from a regenerator 21 and heats up to about 650 ° Celsius.
  • the regenerator 21 is generally composed of a packet of wire screens, which in Fig. 1 are not shown in detail.
  • any heat source with a sufficient temperature level can be used as heat source in a Stirling engine, in the exemplary embodiment according to FIG Fig. 1 a burner is used (not shown), which can burn a gaseous or liquid fuel.
  • the so-called high temperature range of the Stirling engine is protected by a thermal insulation 27 against heat loss.
  • FIG. 2 shows a view of a compression piston 12 according to the invention with a first guide band 29, a first piston ring 31 and a second piston ring 33.
  • the guide band 29 serves to guide the compression piston 12 in the cylinder, not shown.
  • the first piston ring 31 and the second piston ring 33 serve to seal the in FIG. 2 located on the left of the piston 12 working space, in FIG. 2 is not shown, to the right of the piston 12 located, also not dargestellen crankcase 1 of the Stirling engine.
  • the guide band 29 and the piston rings 31 and 33 are each received in annular grooves in a known manner.
  • FIG. 2 only the Ring groove 35 of the second piston ring 33 marked with reference lines and a reference numeral.
  • a sleeve 39 is attached to a piston shaft 41 of the piston 12.
  • the sleeve 39 may be more connected to the piston shaft 41 by welding, in particular electron beam welding, pressing, soldering and others.
  • the sleeve 39 has a lower edge 43, which has a to the annular groove 35 with a designated "A" distance. This distance "A” is inventively dimensioned so that it is between 0.66 x piston stroke to 1.5 X piston stroke.
  • the distance "A” in the size according to the invention ensures that the region of the illustrated cylinder running surface swept by the piston rings 29, 31 and 33 is covered during operation by the piston shaft 41 or the sleeve 39 so that no oil is present this area of the cylinder surface can knock down.
  • the precipitation of oil on this area of the cylinder surface is undesirable because parts of this oil precipitate can dissolve in the working gas and then precipitate in the regenerator and char there. This leads to functional impairments of the Stirling engine and reductions in efficiency and performance of the Stirling engine.
  • FIG. 3 an embodiment of a working piston 17 according to the invention is shown in longitudinal section. Some components are given the same reference numbers and only the differences are explained below to avoid repetition.
  • a piston dome 45 is placed above the piston head 37, which reduces the heat transfer between working gas (not shown) and the working cylinder 17.
  • the piston shaft 41 two annular grooves 35 and 47 are inserted.
  • the wide annular groove 47 serves to receive a guide band of Teflon (in Fig. 3 not shown), which assumes the leadership of the working piston 17 in the cylinder, not shown.
  • the annular groove 35 receives a piston ring (not shown), which serves to seal the working space relative to the crankcase.
  • a sleeve 39 is attached to the piston shaft 41.
  • the distance "A" is measured according to the same rules as based on the embodiment according to FIG. 2 explained.
  • FIG. 3 is also an internal thread 49 shown, in which a piston rod, not shown, can be screwed.
  • the long piston shaft 41 also improves the cooling of the piston rings.
  • the inventive design of a piston skirt can also be used in piston compressors for compressing a wide variety of gases. Even with reciprocating compressors, it is namely undesirable that the gases to be compressed absorb oil.

Abstract

The piston and cylinder unit includes a piston with at least one piston ring groove (35). The spacing between the piston ring groove closest to the crankshaft and the bottom edge (43) of the piston body (41) is between 0.66 and 1.5 times the piston stroke, preferably between 0.9 and 1.1 times the piston stroke. The cylinder is made of globular gray-cast iron, and its running surface is induction-hardened.

Description

Der Einsatz von Stirling-Motoren ist inbesondere dann von Vorteil, wenn es gelingt, die Lebensdauer und die Serviceintervalle sehr viel größer als bei konventionellen Otto-oder Dieselmotoren zu gestalten.The use of Stirling engines is particularly advantageous if it is possible to make the service life and service intervals much greater than in conventional gasoline or diesel engines.

Der Erfindung liegt die Aufgabe zugrunde, einen Stirling-Motor mit erhöhter Lebensdauer und größeren Serviceintervallen bereitzustellen.The invention has for its object to provide a Stirling engine with increased life and larger service intervals.

Diese Aufgabe wird erfindungsgemäß gelöst, durch einen Kolben eines Stirling-Motors, mit einem Kolbenboden, mit einem Kolbenschaft, wobei bei Kolbenschaft eine Unterkante aufweist, wobei in dem Kolbenschaft mindestens eine Ringnut zur Aufnahme eines Kolbenrings vorhanden ist, und wobei der Kolben über eine Kolbenstange, einen Kreuzkopf und ein Pleuel oder unmittelbar über ein Pleuel mit einer Kurbelwelle gekoppelt ist, dadurch gelöst, dass der Abstand der Ringnut, die am nächsten zur Kurbelwelle angeordnet ist und der Unterkante des Kolbenschafts zwischen 0,66 x Kolbenhub und 1,5 x Kolbenhub, besonders bevorzugt zwischen 0,9 x Kolbenhub und 1,1 x Kolbenhub, beträgt.This object is achieved by a piston of a Stirling engine, with a piston head, with a piston skirt, wherein piston skirt has a lower edge, wherein in the piston skirt at least one annular groove for receiving a piston ring is present, and wherein the piston is coupled via a piston rod, a crosshead and a connecting rod or directly via a connecting rod with a crankshaft, thereby solved in that the distance of the annular groove which is arranged closest to the crankshaft and the lower edge of the piston shaft is between 0.66 x piston stroke and 1.5 x piston stroke, more preferably between 0.9 x piston stroke and 1.1 x piston stroke.

Durch diese konstruktive Ausgestaltung des Kolbenschafts ist gewährleistet, dass die Zylinderlauffläche in dem Bereich, welcher von dem oder den Kolbenringen überstrichen wird, vollständig oder nahezu vollständig vom Kolbenschaft abgedeckt wird. Dadurch wird die Wärmeabfuhr verbesssert.This structural design of the piston skirt ensures that the cylinder running surface is completely or almost completely covered by the piston skirt in the region which is swept by the piston ring (s). This improves the heat dissipation.

Außerdem wird verhindert, dass sich Öl auf dem von den Kolbenringen überstrichenen Bereich der Zylinderlauffläche niederschlagen kann. In Folge dessen kann das Öl auch nicht in Kontakt mit dem oberhalb des Kolbenbodens befindlichen Arbeitsgas gelangen und dieses verunreinigen. Sobald nämlich in dem Arbeitsgas Ölspuren vorhanden sind, ist die Funktion des Stirlings-Motors zumindest beeinträchtigt, da sich Ölnebel erfahrungsgemäß sehr leicht am Regenerator niederschlagen, dort verkohlen und somit den Strömungswiderstand für das Arbeitsgas beim Durchströmen des Regenerators deutlich erhöhen. Außerdem wird der Wärmeübergang zwischen dem Speichermaterial des Regenerators und dem Arbeitsgas drastisch verschlechtert. Beide Effekte führen zu einer unerwünschten Einbuße bei Wirkungsgrad und Leistung des Stirling-Motors.It also prevents oil from precipitating on the area of the cylinder surface swept by the piston rings. As a result, the oil can not come into contact with the above the piston head working gas and contaminate it. As soon as in the working gas traces of oil are present, the function of the Stirling engine is at least impaired, since oil mist experience reflected very easily reflected on the regenerator, there char and thus the Increase flow resistance for the working gas when flowing through the regenerator significantly. In addition, the heat transfer between the storage material of the regenerator and the working gas is drastically deteriorated. Both effects lead to an undesirable loss in efficiency and performance of the Stirling engine.

Nach einer Variante der Erfindung ist vorgesehen, dass der Kolbenschaft an seinem dem Kolbenboden entgegengesetzten Ende eine Hülse aufweist, so dass die erfindungsgemäße Länge des Kolbenschafts durch eine einfach herzustellende Hülse erreicht werden kann. Außerdem kann durch diese erfindungsgemäße Ausgestaltung ein an sich bekannter Kolben für einen Stirling-Motor in erfindungsgemäßer Weise ertüchtigt werden. Da die Hülse, abgesehen von den Massenkräften, keinen nennenswerten hohen Beanspruchungen ausgesetzt ist, kann sie sehr dünnwandig ausgeführt werden.According to a variant of the invention it is provided that the piston skirt has a sleeve at its end opposite the piston head, so that the length of the piston skirt according to the invention can be achieved by a sleeve which is easy to produce. In addition, this embodiment of the invention, a per se known piston for a Stirling engine in accordance with the invention can be improved. Since the sleeve, apart from the inertial forces, is not subject to any significant high stresses, it can be made very thin-walled.

Es hat sich als vorteilhaft erwiesen, die Hülse und den Kolben durch Elektronenstrahlschweißen miteinander zu verbinden. Alternativ können auch andere Fügeverfahren eingesetzt werden.It has proven to be advantageous to connect the sleeve and the piston by electron beam welding together. Alternatively, other joining methods can be used.

Weitere Ausgestaltungen der Erfindung sehen vor, dass auf dem Kolbenboden ein Kolbendom aufgesetzt ist, dass der Kolben ein Verdichtungskolben ist, und/oder dass der Kolben ein Arbeitskolben ist, so dass die Vorteile der Erfindung für die genannten Kolbentypen nutzbar gemacht werden können.Further embodiments of the invention provide that on the piston head, a piston dome is placed, that the piston is a compression piston, and / or that the piston is a working piston, so that the advantages of the invention for the mentioned piston types can be used.

Weitere Vorteile und vorteilhafte Ausgestaltungen der Erfindung sind der nachfolgenden Zeichnung, deren Beschreibung und den Patentansprüchen entnehmbar.Further advantages and advantageous embodiments of the invention are the following drawings, the description and the claims removable.

Es zeigen:Show it:

Figur 1FIG. 1
ein Ausführungsbeispiel eines Stirling-Motors nach dem Stand der Technik mit V-Anordnung der Zylinder im Querschnitt,An embodiment of a Stirling engine according to the prior art with V-arrangement of the cylinder in cross section,
Figur 2FIG. 2
eine Seitenansicht eines Ausführungsbeispiels eines erfindungsgemäßen Verdichtungskolbens, unda side view of an embodiment of a compression piston according to the invention, and
Figur 3FIG. 3
einen Querschnitt durch ein Ausführungsbeispiel eines erfindungsgemäßen Arbeitskolbens.a cross section through an embodiment of a working piston according to the invention.

Der Stirlingmotor gemäß Fig. 1 weist ein Kurbelgehäuse 1 auf, in dem eine Kurbelwelle 3 drehbar gelagert ist. An einem Hubzapfen 5 der Kurbelwelle 3 sind ein erstes Pleuel 7 und ein zweites Pleuel 9 drehbar gelagert. Das erste Pleuel 7 ist über einen ersten Kreuzkopf 10 und eine erste Kolbenstange 11 mit einem Verdichtungskolben 12 verbunden. Das zweite Pleuel 9 ist über einen zweiten Kreuzkopf 13 und eine zweite Kolbenstange 14 mit einem Arbeitskolben 15 verbunden. Die konstruktive Ausgestaltung von Verdichtungskolben 12 und Arbeitskolben 15 ist im Zusammenhang mit Fig. 1 nicht von Bedeutung und wird deshalb an dieser Stelle nicht näher erläutert. Der Verdichtungskolben 12 läuft in einem Verdichtungszylinder 16, während der Arbeitskolben 15 in einem Arbeitszylinder 17 läuft. Die Kurbelwelle 3 und der Hubzapfen 5 sind ölgeschmiert, während der Verdichtungskolben 12 und der Arbeitskolben 15 trocken im Verdichtungszylinder 16 bzw. im Arbeitszylinder 17 laufen.The Stirling engine according to Fig. 1 has a crankcase 1, in which a crankshaft 3 is rotatably mounted. At a crank pin 5 of the crankshaft 3, a first connecting rod 7 and a second connecting rod 9 are rotatably mounted. The first connecting rod 7 is connected via a first crosshead 10 and a first piston rod 11 with a compression piston 12. The second connecting rod 9 is connected via a second crosshead 13 and a second piston rod 14 with a working piston 15. The structural design of compression piston 12 and piston 15 is in connection with Fig. 1 is not relevant and will therefore not be explained further here. The compression piston 12 runs in a compression cylinder 16, while the working piston 15 is running in a working cylinder 17. The crankshaft 3 and the crank pin 5 are lubricated with oil, while the compression piston 12 and the working piston 15 run dry in the compression cylinder 16 or in the working cylinder 17.

Zwischen dem Verdichtungszylinder 16 und dem Arbeitszylinder 17 kann das Arbeitsgas hin- und hergeschoben werden. Dabei nimmt das in Fig. 1 nicht dargestellte Arbeitsgas beim Verschieben aus dem Verdichtungszylinder 16 in den Arbeitszylinder 17 Wärme aus einem Regenerator 21 auf und erwärmt sich dabei auf etwa 650° Celsius. Der Regenerator 21 besteht im Allgemeinen aus einem Paket von Drahtsieben, die in Fig. 1 nicht im Einzelnen dargestellt sind. Anschließend wird das Arbeitsgas in einem Erhitzer 23, der bei dem Ausführungsbeispiel gemäß Fig. 1 aus verrippten Rohren gebildet wird, auf etwa 650° Celsius erwärmt. Diese Erwärmung erfolgt durch Wärmeübertragung von einem in Fig. 1 nicht dargestellten Brenner über den Erhitzer 23 auf das Arbeitsgas. Gleichzeitig erfolgt eine annähernd isotherme Expansion des Arbeitsgases im Arbeitszylinder 17, wodurch mechanische Arbeit vom Arbeitsgas auf den Arbeitskolben 15 übertragen wird. Anschließend wird das Arbeitsgas vom Arbeitszylinder 17 in den Verdichtungszylinder 16 zurückgeschoben, wobei das Arbeitsgas Wärme an den Regenerator 21 überträgt und anschließend von einem Arbeitsgaskühler 25 abgekühlt wird.Between the compression cylinder 16 and the working cylinder 17, the working gas can be pushed back and forth. It takes in the Fig. 1 Not shown working gas when moving from the compression cylinder 16 in the working cylinder 17 heat from a regenerator 21 and heats up to about 650 ° Celsius. The regenerator 21 is generally composed of a packet of wire screens, which in Fig. 1 are not shown in detail. Subsequently, the working gas in a heater 23, which in the embodiment according to Fig. 1 made of finned tubes, heated to about 650 ° Celsius. This heating takes place by heat transfer from an in Fig. 1 not shown burner via the heater 23 to the working gas. At the same time there is an approximately isothermal expansion of the working gas in the working cylinder 17, whereby mechanical work is transmitted from the working gas to the working piston 15. Subsequently, the working gas is pushed back from the working cylinder 17 in the compression cylinder 16, wherein the working gas heat to the Regenerator 21 transmits and is then cooled by a working gas cooler 25.

Als Wärmequelle kann bei einem Stirlingmotor prinzipiell jede Wärmequelle mit ausreichendem Temperaturniveau herangezogen werden, bei dem Ausführungsbeispiel gemäß Fig. 1 wird ein Brenner eingesetzt (nicht dargestellt), der einen gasförmigen oder flüssigen Brennstoff verbrennen kann. Der sogenannte Hochtemperaturbereich des Stirlingmotors ist durch eine Wärmedämmung 27 gegen Wärmeverluste geschützt.In principle, any heat source with a sufficient temperature level can be used as heat source in a Stirling engine, in the exemplary embodiment according to FIG Fig. 1 a burner is used (not shown), which can burn a gaseous or liquid fuel. The so-called high temperature range of the Stirling engine is protected by a thermal insulation 27 against heat loss.

Figur 2 zeigt eine Ansicht eines erfindungsgemäßen Verdichtungskolbens 12 mit einem ersten Führungsband 29, einem ersten Kolbenring 31 und einem zweiten Kolbenring 33. Das Führungsband 29 dient der Führung des Verdichtungskolbens 12 in dem nicht dargestellten Zylinder. Der erste Kolbenring 31 und der zweite Kolbenring 33 dienen zur Abdichtung des in Figur 2 links des Kolbens 12 befindlichen Arbeitsraums, der in Figur 2 nicht dargestellt ist, zu dem rechts des Kolbens 12 befindlichen, ebenfalls nicht dargestellen Kurbelgehäuse 1 des Stirling-Motors. Das Führungsband 29 und die Kolbenringe 31 und 33 sind jeweils in Ringnuten in ansich bekannter Weise aufgenommen. FIG. 2 shows a view of a compression piston 12 according to the invention with a first guide band 29, a first piston ring 31 and a second piston ring 33. The guide band 29 serves to guide the compression piston 12 in the cylinder, not shown. The first piston ring 31 and the second piston ring 33 serve to seal the in FIG. 2 located on the left of the piston 12 working space, in FIG. 2 is not shown, to the right of the piston 12 located, also not dargestellen crankcase 1 of the Stirling engine. The guide band 29 and the piston rings 31 and 33 are each received in annular grooves in a known manner.

Aus Gründen der Übersichtlichkeit wird in Figur 2 nur die Ringnut 35 des zweiten Kolbenrings 33 mit Bezugslinien und einem Bezugszeichen gekennzeichnet. An dem einem Kolbenboden 37 des Verdichtungskolbens 12 entgegengesetzten Ende desselben ist eine Hülse 39 an einem Kolbenschaft 41 des Kolbens 12 angesetzt. Die Hülse 39 kann durch Schweißen, insbesondere Elektronenstrahlschweißen, Verpressen, Löten und Anderes mehr mit dem Kolbenschaft 41 verbunden sein. Die Hülse 39 weist eine Unterkante 43 auf, die zu der Ringnut 35 einen mit in "A" bezeichneten Abstand aufweist. Dieser Abstand "A" wird erfindungsgemäß so bemessen, dass er zwischen 0,66 x Kolbenhub bis 1,5 X Kolbenhub beträgt. Als ein besonders vorteilhafter Kompromiss zwischen Größe des Abstands "A" und erforderlichem Bauaufwand hat sich eine Größe des Abstands "A" von 0,9 x Kolbenhub bis 1,1 x Kolbenhub herausgestellt. Durch den Abstand "A" in der erfindungsgemäßen Größe ist gewährleistet, dass der von den Kolbenringen 29, 31 und 33 überstrichene Bereich der dargestellten Zylinderlauffläche im Betrieb mit von den Kolbenschaft 41, bzw. der Hülse 39 überdeckt ist, so dass sich kein Öl auf diesen Bereich der Zylinderlauffläche niederschlagen kann. Das Niederschlagen von Öl auf diesen Bereich der Zylinderlauffläche ist unerwünscht, weil sich Teile dieses Ölniederschlags im Arbeitsgas lösen können und sich anschließend im Regenerator niederschlagen und dort verkohlen können. Dies führt zu Funktionsbeeinträchtigungen des Stirling-Motors sowie Verringerungen des Wirkungsgrads und der Leistung des Stirling-Motors.For clarity, in FIG. 2 only the Ring groove 35 of the second piston ring 33 marked with reference lines and a reference numeral. At the same end opposite a piston head 37 of the compression piston 12, a sleeve 39 is attached to a piston shaft 41 of the piston 12. The sleeve 39 may be more connected to the piston shaft 41 by welding, in particular electron beam welding, pressing, soldering and others. The sleeve 39 has a lower edge 43, which has a to the annular groove 35 with a designated "A" distance. This distance "A" is inventively dimensioned so that it is between 0.66 x piston stroke to 1.5 X piston stroke. As a particularly advantageous compromise between the size of the distance "A" and the required construction cost, a size of the distance "A" from 0.9 x piston stroke to 1.1 x piston stroke has been found. The distance "A" in the size according to the invention ensures that the region of the illustrated cylinder running surface swept by the piston rings 29, 31 and 33 is covered during operation by the piston shaft 41 or the sleeve 39 so that no oil is present this area of the cylinder surface can knock down. The precipitation of oil on this area of the cylinder surface is undesirable because parts of this oil precipitate can dissolve in the working gas and then precipitate in the regenerator and char there. This leads to functional impairments of the Stirling engine and reductions in efficiency and performance of the Stirling engine.

Die Figur 3 ist ein Ausführungsbeispiel eines erfindungsgemäßen Arbeitskolbens 17 im Längsschnitt dargestellt. Einige Bauteile werden mit gleichen Bezugszeichen versehen und im Folgenden werden nur die Unterschiede erläutert, um Wiederholungen zu vermeiden. An dem Arbeitskolben 17 ist oberhalb des Kolbenbodens 37 ein Kolbendom 45 aufgesetzt, welcher die Wärmeübertragung zwischen Arbeitsgas (nicht dargestellt) und dem Arbeitszylinder 17 verringert. Im Kolbenschaft 41 sind zwei Ringnuten 35 und 47 eingestochen. Die breite Ringnut 47 dient zur Aufnahme eines Führungsbands aus Teflon (in Fig. 3 nicht dargestellt), das die Führung des Arbeitskolbens 17 in dem nicht dargestellten Zylinder übernimmt. Die Ringnut 35 nimmt einen Kolbenring (nicht dargestellt) auf, der zur Abdichtung des Arbeitsraums gegenüber dem Kurbelgehäuse dient. Auch bei diesem Ausführungsbeispiel ist eine Hülse 39 an dem Kolbenschaft 41 angebracht. Der Abstand "A" bemisst sich nach den gleichen Regeln wie anhand des Ausführungsbeispiels gemäß Figur 2 erläutert. In Figur 3 ist auch ein Innengewinde 49 dargestellt, in welches eine nicht dargestellte Kolbenstange eingeschraubt werden kann. Durch den langen Kolbenschaft 41 wird außerdem die Kühlung der Kolbenringe verbessert.The FIG. 3 an embodiment of a working piston 17 according to the invention is shown in longitudinal section. Some components are given the same reference numbers and only the differences are explained below to avoid repetition. On the working piston 17, a piston dome 45 is placed above the piston head 37, which reduces the heat transfer between working gas (not shown) and the working cylinder 17. In the piston shaft 41, two annular grooves 35 and 47 are inserted. The wide annular groove 47 serves to receive a guide band of Teflon (in Fig. 3 not shown), which assumes the leadership of the working piston 17 in the cylinder, not shown. The annular groove 35 receives a piston ring (not shown), which serves to seal the working space relative to the crankcase. Also in this embodiment, a sleeve 39 is attached to the piston shaft 41. The distance "A" is measured according to the same rules as based on the embodiment according to FIG. 2 explained. In FIG. 3 is also an internal thread 49 shown, in which a piston rod, not shown, can be screwed. The long piston shaft 41 also improves the cooling of the piston rings.

Die erfindungsgemäße Ausgestaltung eines Kolbenschafts kann auch bei Kolbenverdichtern zum Verdichten unterschiedlichster Gase eingesetzt werden. Auch bei Kolbenverdichtern ist es nämlich unerwünscht, dass die zu verdichtenden Gase Öl aufnehmen.The inventive design of a piston skirt can also be used in piston compressors for compressing a wide variety of gases. Even with reciprocating compressors, it is namely undesirable that the gases to be compressed absorb oil.

Claims (6)

  1. Piston for a Stirling engine having a piston base (37) and a piston skirt (41), wherein the piston skirt (41) has a lower edge (43), wherein at least one ring groove (35) for receiving a piston ring (33) is present in the piston skirt (41) and wherein the piston is coupled via a piston rod (11, 14), a crosshead (10, 13) and a connecting rod (7, 9), or directly via a connecting rod (7, 9), to a crankshaft (3), characterised in that the spacing between the ring groove (35), which is disposed closest to the crankshaft (3) and the lower edge (43) of the piston skirt (41), amounts to between 0.66 x the piston stroke and 1.5 x the piston stroke, preferably to between 0.9 x the piston stroke and 1.1 x the piston stroke.
  2. Piston in accordance with claim 1, characterised in that the piston skirt (41) has a sleeve (39) at its end opposite from the piston base (37).
  3. Piston in accordance with claim 1 or claim 2, characterised in that a piston crown (45) is mounted on the piston base (37).
  4. Piston in accordance with one of the preceding claims, characterised in that the piston is a compression piston (12).
  5. Piston in accordance with one of the claims 1 to 3, characterised in that the piston is a working piston (13).
  6. Piston in accordance with one of the claims 1 to 3, characterised in that the piston is a displacement piston.
EP02400014A 2001-03-05 2002-03-05 Piston and cylinders for a Stirling engine Expired - Lifetime EP1239137B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10110446A DE10110446A1 (en) 2001-03-05 2001-03-05 Pistons and cylinders for a Stirling engine
DE10110446 2001-03-05

Publications (3)

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EP1239137A2 EP1239137A2 (en) 2002-09-11
EP1239137A3 EP1239137A3 (en) 2003-05-28
EP1239137B1 true EP1239137B1 (en) 2009-05-27

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EP02400014A Expired - Lifetime EP1239137B1 (en) 2001-03-05 2002-03-05 Piston and cylinders for a Stirling engine

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EP (1) EP1239137B1 (en)
AT (1) ATE432413T1 (en)
DE (2) DE10110446A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102041370B (en) * 2010-11-12 2012-05-23 江南大学 Steel-top aluminium-skirt piston ring groove induction strengthened self-tempering preventor
SE541814C2 (en) * 2018-01-02 2019-12-17 Maston AB Stirling engine comprising a transition flow element
SE541815C2 (en) * 2018-01-02 2019-12-17 Maston AB Stirling engine comprising a metal foam regenerator
SE541816C2 (en) * 2018-01-02 2019-12-17 Maston AB A Stirling engine arranged with a gas channel comprising three heat exchangers

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR935169A (en) * 1945-10-29 1948-06-11 Philips Nv Improvements to hot gas piston machines
CH347677A (en) * 1956-01-24 1960-07-15 Energy Limited Hot gas piston machine with external heating
DE2851806A1 (en) * 1978-11-30 1980-06-12 Briggs & Stratton Corp Combustion or solar energy Stirling engine - has hot exhaust passed to cold space which is replenished with fresh gas for next stroke
JPS5896148A (en) * 1981-12-02 1983-06-08 Aisin Seiki Co Ltd Piston of gas engine
US5755100A (en) * 1997-03-24 1998-05-26 Stirling Marine Power Limited Hermetically sealed stirling engine generator

Also Published As

Publication number Publication date
ATE432413T1 (en) 2009-06-15
DE50213570D1 (en) 2009-07-09
DE10110446A1 (en) 2002-09-19
EP1239137A2 (en) 2002-09-11
EP1239137A3 (en) 2003-05-28

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