EP0151952B1 - Insulated piston for internal combustion engines - Google Patents

Insulated piston for internal combustion engines Download PDF

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Publication number
EP0151952B1
EP0151952B1 EP85100435A EP85100435A EP0151952B1 EP 0151952 B1 EP0151952 B1 EP 0151952B1 EP 85100435 A EP85100435 A EP 85100435A EP 85100435 A EP85100435 A EP 85100435A EP 0151952 B1 EP0151952 B1 EP 0151952B1
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EP
European Patent Office
Prior art keywords
heat shield
piston
ceramic
layer
metal
Prior art date
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Expired
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EP85100435A
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German (de)
French (fr)
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EP0151952A1 (en
Inventor
Hans. Dr.-Ing. Zeilinger
Edwin. Dipl.-Ing. Erben
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MT Aerospace AG
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MAN Technologie AG
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Publication of EP0151952A1 publication Critical patent/EP0151952A1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B77/00—Component parts, details or accessories, not otherwise provided for
    • F02B77/02—Surface coverings of combustion-gas-swept parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/10—Pistons  having surface coverings
    • F02F3/12—Pistons  having surface coverings on piston heads
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F7/00—Casings, e.g. crankcases or frames
    • F02F7/0085—Materials for constructing engines or their parts
    • F02F7/0087—Ceramic materials
    • 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
    • F05C2201/00—Metals
    • F05C2201/02—Light metals
    • F05C2201/021—Aluminium
    • 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
    • F05C2203/00—Non-metallic inorganic materials
    • F05C2203/08—Ceramics; Oxides
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49229—Prime mover or fluid pump making
    • Y10T29/49249—Piston making
    • Y10T29/49256—Piston making with assembly or composite article making
    • Y10T29/49258—Piston making with assembly or composite article making with thermal barrier or heat flow provision

Definitions

  • the invention relates to a method for producing a piston of an internal combustion engine provided with a metal-ceramic heat shield.
  • a piston with a ceramic piston crown is known from US-PS-4404262.
  • the latter is formed by a ceramic disc, which is prefabricated, in such a way that the end face later facing the brake chamber is almost completely smooth, i. H. is not porous, furthermore the highest density of the ceramic material is given in this area and this density decreases towards the other end face, at the same time the porosity increases.
  • This prefabricated ceramic plate is then placed in a mold, into which molten metal, in particular aluminum, is then introduced and the shape of the piston base body is shaped by a stamp.
  • the liquid metal also penetrates into the porous contact zone of the ceramic disk under the pressure of the plunger, so that after the metal material has cooled down, it has a certain interlocking with the pores of the ceramic disk.
  • a piston for internal combustion engines is also known from DE-PS 869 570, which is either sintered in one piece, entirely from a mixture of metal powder and ceramic powder, the proportion of which increases from 0 to 100% from below towards the piston crown , or is made in two parts.
  • the lower piston part is sintered from metal powder
  • the upper piston part is also produced from a mixture of metal powder and ceramic powder by sintering, the proportion of the ceramic powder increasing from 0 to 100% towards the piston crown.
  • the upper piston part therefore has a purely metallic layer in its area to be connected to the lower piston part and a purely ceramic boundary layer on the piston head. The upper piston part and lower piston part are then connected to one another either by sintering or welding.
  • a ceramic insert body as a heat shield for. B. known for an internal combustion engine piston, which is made exclusively of PSZ (partially stabilized zirconium oxide) and then optionally introduced with a metallic intermediate layer in an already prefabricated, prepared for receiving base body.
  • PSZ partially stabilized zirconium oxide
  • a metallic intermediate layer cannot be satisfactory in this case either.
  • the character of such an intermediate layer is only briefly indicated in this document in page 5, lines 29 to 34. Accordingly, a metallic layer is to be sprayed on the purely ceramic PSZ insert body at the connection surface by "metal spraying". The PSZ insert body coated in this way is then inserted into the piston base body and its metallic surface is brought into contact with the material of the piston base body. Then the connection point is heated so that an intermetallic connection is established.
  • a prefabricated ceramic body is likewise only subsequently provided with a metallic layer, this material being applied in a pasty form and then being connected to the ceramic body in an appropriate atmosphere with the supply of heat .
  • This ceramic body pre-coated in this way is connected to a metallic body via a layer of solder material.
  • a method for producing a piston of an internal combustion engine provided with a metal-ceramic heat shield in which first the thin heat shield from at least one layer, which is adapted to its outer shape according to the shape of the piston crown or the combustion chamber bowl on the piston crown side purely ceramic material and at least one layer of metallic or metal-ceramic material is produced by pressing and heating these layer materials.
  • This heat shield thus obtained is turned with its metallic side to a prefabricated piston body, connected to the latter for example by welding or soldering.
  • Piston body material intermetallic with the material of the metallic or metal-ceramic layer of the heat shield.
  • the thin heat shield is to be understood as a flat body, the length and width dimensions of which are many times larger than its thickness dimension.
  • Ceramic material with a conductivity value ⁇ of ⁇ 2 to 3 W / m ° K is preferably used for its ceramic layer component in order to achieve excellent thermal insulation. These values are met, for example, by using the following - known - ceramic materials, such as Zr Si 0 4 , aluminum titanate, silicon nitride, the synthetic Al-Si mixed oxide of the formula 3 A1 2 0 3 .2Si0 2 known as "Mullite”, and Partially modified Zr0 2 , which is known as PSZ (partially stabilized zirconium oxide) and has Ca0 and / or Mg0 as stabilizers.
  • PSZ partially stabilized zirconium oxide
  • the metallic component of the metal-ceramic material of the heat-insulating heat shield consists of or preferably contains iron or iron alloys, while cast aluminum alloys can advantageously be used as the piston material.
  • cast aluminum alloys can advantageously be used as the piston material.
  • silumin can be used, but other cast aluminum alloys can also be used, for example eutectic Al-Si alloys with 11 to 13% Si and minor additions of Cu, Ni and Mg or hypereutectic Al-Si alloys with about 17 up to 25% Si and minor additions of Cu, Ni and Mg or aluminum-copper alloys such as Al Cu 4 with Ni and Mg additions
  • the hot isostatic pressing of the porous layer body is generally carried out at temperatures of about 1000 to 1450, preferably from about 1200 to 1350 and in particular at 1300 ° C.
  • the pressures to be used are usually in the range from about 1000 to 1500, preferably in the range from about 1200 to 1300, bar.
  • a combustion bowl insert made of Zr0 2 was provided with a suitable mandrel on the inside. Then carbonyl iron powder was applied on the outside using a molybdenum capsule. The sample thus prepared and encapsulated was then placed in a hot isostatic press. The HIPEN itself was carried out at temperatures between 1200 and 1300 ° C, at pressures between 1000 and 1500 bar, the pressing time was 1-2 hours. The composite combustion chamber bowl produced in this way was poured into silumin and showed very good adhesive strength, this connection strength corresponding to the strength of the piston material.
  • a pre-shaped combustion bowl insert made of Zr0 2 was provided with a suitable mandrel on the inside.
  • This composite combustion chamber trough was cast in silumin and showed very good connection strength, which is equivalent to the strength of the piston material.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung eines mit einem metall-keramischen Hitzeschild versehenen Kolbens einer Brennkraftmaschine.The invention relates to a method for producing a piston of an internal combustion engine provided with a metal-ceramic heat shield.

Zur Herstellung kolbenbodenseitig thermisch durch einen Hitzeschild isolierter Brennkraftmaschinenkolben sind aus der Literatur eine Reihe von Vorschlägen bekannt, die jedoch alle aus verschiedensten Gründen nicht zu befriedigen vermögen, weil sich die Verbindungsqualität zwischen Hitzeschild und Kolbenkörper als zu schlecht und den hohen thermischen sowie dynamischen Belastungen im Motorenbetrieb als nicht gewachsen erwies.A number of proposals are known from the literature for the production of internal combustion engine pistons which are thermally insulated by a heat shield on the piston crown, but all of them are unsatisfactory for a variety of reasons because the quality of the connection between the heat shield and the piston body is too poor and the high thermal and dynamic loads in engine operation proved not to have grown.

So ist es beispielsweise aus der "Motortechnischen Zeitschrift MTZ 44 (1983) 6, Seite 228, linke und mittlere Spalte" bekannt, einen Kolben für Dieselmotoren nach der dortigen Kompositbauweise herzustellen, wobei der später die Brennraummulde bedeckende keramische Hitzeschild zunächst als dünne Schale vorgefertigt und diese Schale dann mit dem metallischen Kolbenwerkstoff umgossen wird. Dabei ergibt sich zwischen der reinkeramischen Schale und dem Kolbenkörper lediglich ein rein formschlüssiger Verbund.For example, it is known from "Motortechnische Zeitschrift MTZ 44 (1983) 6, page 228, left and middle column" to produce a piston for diesel engines according to the composite construction there, the ceramic heat shield which later covering the combustion chamber bowl first being prefabricated as a thin shell and this shell is then encapsulated with the metallic piston material. The result is only a purely positive connection between the ceramic bowl and the piston body.

Aus der US-PS-4404262 ist die Herstellung eines Kolbens mit keramischem Kolbenboden bekannt. Letzterer ist durch eine keramische Scheibe gebildet, die vorgefertigt wird, und zwar in der Weise, daß die später dem Bremsraum zugewandte Stirnfläche nahezu vollständig glatt, d. h. nicht porös ist, ferner in diesem Bereich die höchste Dichte des Keramikmaterials gegeben ist und diese Dichte zur anderen Stirnseite hin abnimmt, gleichzeitig die Porösität größer wird. Diese vorgefertigte Keramikplatte wird dann in eine Form gegeben, in die dann von oben her geschmolzenes Metall, insbesondere Aluminium, eingebracht und durch einen Stempel die Form des Kolbengrundkörpers ausgeformt wird. Das flüssige Metall dringt dabei auch unter dem Druck des Stempels in die poröse Kontaktzone der keramischen Scheibe ein, so daß nach Erkalten des Metallwerkstoffes eine gewisse Verzahnung desselben mit den Poren der Keramikscheibe gegeben ist.The production of a piston with a ceramic piston crown is known from US-PS-4404262. The latter is formed by a ceramic disc, which is prefabricated, in such a way that the end face later facing the brake chamber is almost completely smooth, i. H. is not porous, furthermore the highest density of the ceramic material is given in this area and this density decreases towards the other end face, at the same time the porosity increases. This prefabricated ceramic plate is then placed in a mold, into which molten metal, in particular aluminum, is then introduced and the shape of the piston base body is shaped by a stamp. The liquid metal also penetrates into the porous contact zone of the ceramic disk under the pressure of the plunger, so that after the metal material has cooled down, it has a certain interlocking with the pores of the ceramic disk.

Des weiteren ist aus der DE-PS 869 570 jedoch auch schon ein Kolben für Brennkraftmaschinen bekannt, der entweder einstückig, ganz aus einer Mischung von Metallpulver und keramischem Pulver, dessen Anteil von unten gegen den Kolbenboden hin von 0 bis 100 % zunimmt, gesintert ist, oder zweiteilig hergestellt ist. Im letzteren Fall wird das Kolbenunterteil aus Metallpulver gesintert, während das Kolbenoberteil aus einer Mischung von Metallpulver und keramischem Pulver ebenfalls durch Sintern hergestellt wird, wobei der Anteil des keramischen Pulvers zum Kolbenboden hin von 0 bis 100 % zunimmt. Das Kolbenoberteil weist mithin in seinem mit dem Kolbenunterteil zu verbindenden Bereich eine rein metallische Schicht und am Kolbenboden eine rein keramische Grenzschicht auf. Das Kolbenoberteil und Kolbenunterteil werden dann entweder durch Sintern oder Schweißen miteinander verbunden.Furthermore, a piston for internal combustion engines is also known from DE-PS 869 570, which is either sintered in one piece, entirely from a mixture of metal powder and ceramic powder, the proportion of which increases from 0 to 100% from below towards the piston crown , or is made in two parts. In the latter case, the lower piston part is sintered from metal powder, while the upper piston part is also produced from a mixture of metal powder and ceramic powder by sintering, the proportion of the ceramic powder increasing from 0 to 100% towards the piston crown. The upper piston part therefore has a purely metallic layer in its area to be connected to the lower piston part and a purely ceramic boundary layer on the piston head. The upper piston part and lower piston part are then connected to one another either by sintering or welding.

Des weiteren ist aus der EP-0 066 022 A 1 ein keramischer Einsatzkörper als Hitzeschild, z. B. für einen Brennkraftmaschinenkolben bekannt, der ausschließlich aus PSZ (partial stabilized zirkonoxide) hergestellt und dann gegebenenfalls mit einer metallischen Zwischenschicht in einen bereits vorgefertigten, für Aufnahme vorbereiteten Grundkörper eingebracht wird. Ohne das Vorsehen dieser metallischen Zwischenschicht würden die gleichen Nachteile wie bei dem eingangs diskutierten, aus der "MTZ 44 (1983) 6, Seite 228" bekannten Kompositkolben auftreten. Aber auch das Vorsehen einer metallischen Zwischenschicht kann in diesem Fall nicht befriedigen. Der Charakter einer solchen Zwischenschicht ist in dieser Schrift lediglich in Seite 5, Zeilen 29 bis 34, kurz angedeutet. Demnach soll auf dem rein keramischen PSZ-Einsatzkörper an der Verbindungsoberfläche eine metallische Schicht aufgespritzt werden durch "metal spraying". Danach wird der so beschichtete PSZ-Einsatzkörper in den Kolbengrundkörper eingesetzt und mit seiner metallischen Oberfläche mit dem Material des Kolbengrundkörpers in Kontakt gebracht. Dann wird die Verbindungsstelle erwärmt, so daß eine intermetallische Verbindung zustande kommt.Furthermore, from EP-0 066 022 A 1 a ceramic insert body as a heat shield, for. B. known for an internal combustion engine piston, which is made exclusively of PSZ (partially stabilized zirconium oxide) and then optionally introduced with a metallic intermediate layer in an already prefabricated, prepared for receiving base body. Without the provision of this metallic intermediate layer, the same disadvantages would arise as in the case of the composite piston discussed at the beginning, known from "MTZ 44 (1983) 6, page 228". However, the provision of a metallic intermediate layer cannot be satisfactory in this case either. The character of such an intermediate layer is only briefly indicated in this document in page 5, lines 29 to 34. Accordingly, a metallic layer is to be sprayed on the purely ceramic PSZ insert body at the connection surface by "metal spraying". The PSZ insert body coated in this way is then inserted into the piston base body and its metallic surface is brought into contact with the material of the piston base body. Then the connection point is heated so that an intermetallic connection is established.

Bei einer weiteren, aus der EP-0 083 834 A 1 bekannten Herstellungsart für einen Schichtkörper wird ein vorgefertigter Keramikkörper ebenfalls erst nachher mit einer metallischen Schicht versehen, wobei dieses Material in pastöser Form aufgebracht und dann unter Wärmezufuhr in entsprechender Atmosphäre mit dem Keramikkörper verbunden wird. Dieser so vorbeschichtete Keramikkörper wird über eine Lotmaterialschicht mit einem metallischen Körper verbunden.In a further type of production for a laminate, which is known from EP-0 083 834 A1, a prefabricated ceramic body is likewise only subsequently provided with a metallic layer, this material being applied in a pasty form and then being connected to the ceramic body in an appropriate atmosphere with the supply of heat . This ceramic body pre-coated in this way is connected to a metallic body via a layer of solder material.

Schließlich ist aus der FR-A-992 440 ein Verfahren zur Herstellung eines mit einem metallkeramischen Hitzeschildes versehenen Kolbens einer Brennkraftmaschine bekannt, bei dem zunächst der dünne, seiner äußeren Gestalt nach der Form des Kolbenbodens bzw. der kolbenbodenseitigen Brennraummulde angeglichene Hitzeschild aus wenigstens einer Schicht rein keramischen Materials und wenigstens einer Schicht metallischen bzw. metallkeramischen Materials durch Pressen und Erhitzen dieser Schichtmaterialien hergestellt wird.Finally, from FR-A-992 440 a method for producing a piston of an internal combustion engine provided with a metal-ceramic heat shield is known, in which first the thin heat shield from at least one layer, which is adapted to its outer shape according to the shape of the piston crown or the combustion chamber bowl on the piston crown side purely ceramic material and at least one layer of metallic or metal-ceramic material is produced by pressing and heating these layer materials.

Dieser so erhaltene Hitzeschild wird mit seiner metallischen Seite einem vorgefertigten Kolbenkörper zugewandt, mit letzteren zum Beispiel durch Anschweißen oder Anlöten verbunden.This heat shield thus obtained is turned with its metallic side to a prefabricated piston body, connected to the latter for example by welding or soldering.

Es ist nach alledem deshalb Aufgabe der Erfindung, ein Verfahren für die Herstellung eines Kolbens für Brennkraftmaschinen anzugeben, bei dem der Boden des Kolbens bzw. in dessen Brennraummulde ein wärmeisolierender Hitzeschild so angebracht wird, daß dieser selbst und dessen Verbindung mit dem Kolbenkörper im Motorenbetrieb auch höchsten thermomechanischen Wechselbeanspruchungen standhält.It is therefore an object of the invention to provide a method for producing a piston for internal combustion engines, in which the bottom of the piston or in the piston A heat-insulating heat shield is attached to the combustion chamber cavity in such a way that it itself and its connection to the piston body withstand the highest thermomechanical alternating stresses during engine operation.

Diese Aufgabe ist erfindungsgemäß dadurch gelöst, daß

  • a) zunächst der Hitzeschild mit den Schichten aus besagten Materialien durch heißisostatisches Pressen derselben hergestellt wird, und dann
  • b) an der metallischen bzw. metallkeramischen Schicht des vorgefertigten Hitzeschildes in einer Gußform der Kolbenkörper angegossen wird und sich dabei das geschmolzene
This object is achieved in that
  • a) the heat shield with the layers of said materials is first produced by hot isostatic pressing thereof, and then
  • b) the piston body is cast on the metallic or metal-ceramic layer of the prefabricated heat shield in a casting mold and the molten mass is thereby formed

Kolbenkörpermaterial mit dem Material der metallischen bzw. metallkeramischen Schicht des Hitzeschildes intermetallisch verbindet.Piston body material intermetallic with the material of the metallic or metal-ceramic layer of the heat shield.

Es sei an dieser Stelle darauf hingewiesen, daß das Herstellen eines metallbeschichteten Keramikkörpers als solches durch Heißpressen aus der US-PS 4 055 451 bekannt ist.It should be pointed out at this point that the manufacture of a metal-coated ceramic body as such by hot pressing is known from US Pat. No. 4,055,451.

Durch das erfindungsgemäße Angießen des Kolbenkörpers an den Hitzeschild ist lediglich eine Gußform notwendig, in der sich das geschmolzene Kolbenkörpermaterial mit dem metallischen bzw. metallkeramischen Material des Hitzeschildes innig intermetallisch verbindet.By casting the piston body onto the heat shield in accordance with the invention, only a casting mold is necessary in which the molten piston body material intimately intermetallic bonds with the metallic or metal-ceramic material of the heat shield.

Es ergibt sich somit eine bisher nicht bekannte äußerst hohe Verbindungsqualität zwischen Hitzeschild und Kolbenwerkstoff.The result is an extremely high quality of connection between the heat shield and the piston material, which was previously unknown.

Der dünne Hitzeschild ist als flächenhaft ausgebildeter Körper zu verstehen, dessen Längen- und Breitenabmessungen um ein Vielfaches größer sind als seine Dickenabmessung. Es wird für dessen keramische Schichtkomponente vorzugsweise keramisches Material mit einem Leitfähigkeitswertλ von < 2 bis 3 W/m° K verwendet, um eine hervorragende Wärmedämmung zu erzielen. Diese Werte werden beispielsweise durch Verwendung folgender - bekannter - keramischer Stoffe erfüllt, wie Zr Si 04, Aluminiumtitanat, Siliziumnitrid, das unter der Bezeichnung "Mullit" bekannte synthetische AI-Si-Mischoxid der Formel 3 A1203.2Si02, sowie teilmodifiziertes Zr02, das als PSZ (partial stabilized zirkonoxide) bekannt ist und Ca0 und/oder Mg0 als Stabilisatoren aufweist.The thin heat shield is to be understood as a flat body, the length and width dimensions of which are many times larger than its thickness dimension. Ceramic material with a conductivity value λ of <2 to 3 W / m ° K is preferably used for its ceramic layer component in order to achieve excellent thermal insulation. These values are met, for example, by using the following - known - ceramic materials, such as Zr Si 0 4 , aluminum titanate, silicon nitride, the synthetic Al-Si mixed oxide of the formula 3 A1 2 0 3 .2Si0 2 known as "Mullite", and Partially modified Zr0 2 , which is known as PSZ (partially stabilized zirconium oxide) and has Ca0 and / or Mg0 as stabilizers.

Die metallische Komponente des metallkeramischen Stoffes des wärmeisolierenden Hitzeschildes besteht aus bzw. enthält vorzugsweise Eisen oder Eisenlegierungen, während als Kolbenwerkstoff AI-Gußlegierungen mit Vorteil anwendbar sind. Als solches kommt Silumin in Frage, aber es können auch andere AI-Gußlegierungen verwendet werden, beispielsweise eutektische AI-Si-Legierungen mit 11 bis 13 % Si und kleineren Zusätzen von Cu, Ni und Mg oder übereutektische AI-Si-Legierungen mit etwa 17 bis 25 % Si und kleineren Zusätzen von Cu, Ni und Mg oder Aluminium-Kupferlegierungen wie AI Cu 4 mit Ni- und Mg-ZusätzenThe metallic component of the metal-ceramic material of the heat-insulating heat shield consists of or preferably contains iron or iron alloys, while cast aluminum alloys can advantageously be used as the piston material. As such, silumin can be used, but other cast aluminum alloys can also be used, for example eutectic Al-Si alloys with 11 to 13% Si and minor additions of Cu, Ni and Mg or hypereutectic Al-Si alloys with about 17 up to 25% Si and minor additions of Cu, Ni and Mg or aluminum-copper alloys such as Al Cu 4 with Ni and Mg additions

Bei einer bevorzugten Verwendung von Eisen bzw. Eisenlegierungen als metallische bzw. metallkeramische Komponente der heißisostatisch verpreßten Schichten des Hitzeschildes und einer AI-Gußlegierung als Kolbenwerkstoff bilden sich dann beim Aufgießen des geschmolzenen Kolbenmetalls auf den Preßkörper, analog dem AI-Fin-Verfahren (US-Patentschrift 2 455 457) intermetallische Fe-AI-Verbindungen, welche eine besonders feste mechanische Verbindung zwischen Kolbenmetall und wärmeisolierendem Hitzeschild gewährleisten. Aber auch unter Verwendung anderer Kolbenmetalle und metallkeramischer Stoffe lassen sich Bindefestigkeiten zwischen Kolben und Hitzeschild erzielen, welche den bisher erzielten Bindefestigkeiten in jedem Falle überlegen sind.With a preferred use of iron or iron alloys as the metallic or metal-ceramic component of the hot isostatically pressed layers of the heat shield and an Al casting alloy as the piston material, then when the molten piston metal is poured onto the pressing body, analogously to the AI-Fin process (US Patent Specification 2,455,457) intermetallic Fe-Al compounds which ensure a particularly strong mechanical connection between the piston metal and the heat-insulating heat shield. But even with the use of other piston metals and metal-ceramic materials, bond strengths between the piston and the heat shield can be achieved, which are superior to the bond strengths achieved so far in any case.

Das heißisostatische Verpressen des porösen Schichtkörpers (Hitzeschild) erfolgt im allgemeinen bei Temperaturen von etwa 1000 bis 1450, vorzugsweise von etwa 1200 bis 1350 und insbesondere bei 1300°C. Die dabei anzuwendenden Drücke liegen gewöhnlich im Bereich von etwa 1000 bis 1500, vorzugsweise im Bereich von etwa 1200 bis 1300 bar.The hot isostatic pressing of the porous layer body (heat shield) is generally carried out at temperatures of about 1000 to 1450, preferably from about 1200 to 1350 and in particular at 1300 ° C. The pressures to be used are usually in the range from about 1000 to 1500, preferably in the range from about 1200 to 1300, bar.

Die Erfindung sei nunmehr durch die nachfolgenden Beispiele näher erläutert:The invention will now be explained in more detail by the following examples:

Beispiel 1:Example 1:

Ein Brennraummuldeneinsatz aus Zr02 wurde innseitig mit einem passenden Dorn versehen. Danach wurde außenseitig mittels einer Molybdänkapsel Carbonyleisenpulver aufgebracht. Die so präparierte und gekapselte Probe wurde dann in eine heißisostatische Presse eingesetzt. Das HIPEN selbst erfolgte bei Temperaturen zwischen 1200 und 1300°C, bei Drücken zwischen 1000 und 1500 bar, die Preßzeit betrug 1 - 2 Stunden. Die so hergestellte Verbundbrennraummulde wurde in Silumin eingegossen und zeigte sehr gute Haftfestigkeit, wobei diese Verbindungsfestigkeit der Festigkeit des Kolbenwerkstoffes entspricht.A combustion bowl insert made of Zr0 2 was provided with a suitable mandrel on the inside. Then carbonyl iron powder was applied on the outside using a molybdenum capsule. The sample thus prepared and encapsulated was then placed in a hot isostatic press. The HIPEN itself was carried out at temperatures between 1200 and 1300 ° C, at pressures between 1000 and 1500 bar, the pressing time was 1-2 hours. The composite combustion chamber bowl produced in this way was poured into silumin and showed very good adhesive strength, this connection strength corresponding to the strength of the piston material.

Beispiel 2:Example 2:

Ein vorgeformter Brennraummuldeneinsatz aus Zr02 wurde innseitig mit einem passenden Dorn versehen. Außenseitig wurde mittels einer Molybdänkapsel ein Gemisch aus Carbonyleisenpulver und Zr02-Pulver, bei einem Carbonyleisenpulvergehalt von 10 - 90-%, aufgebracht. Nach Einsetzen in die heißisostatische Presse erfolgte das Pressen wie in Beispiel 1. Auch diese Verbundbrennraummulde wurde in Silumin eingegossen und zeigte sehr gute Verbindfestigkeit, die der Festigkeit des Kolbenwerkstoffes gleichkommt.A pre-shaped combustion bowl insert made of Zr0 2 was provided with a suitable mandrel on the inside. A mixture of carbonyl iron powder and Zr0 2 powder, with a carbonyl iron powder content of 10 - 90%, was applied on the outside using a molybdenum capsule. After insertion into the hot isostatic press, the pressing was carried out as in Example 1. This composite combustion chamber trough was cast in silumin and showed very good connection strength, which is equivalent to the strength of the piston material.

Claims (4)

1. A method of producing a piston - provided with a metal-ceramic heat shield - of an internal combustion engine, in which the thin heat shield adapted in its external shaping to the shape of the piston base or the combustion chamber hollow on the side of the piston base is first produced from at least one layer of purely ceramic material and at least one layer of metallic or metal-ceramic material by pressing and heating the said layer materials and the said heat shield is then joined to the piston, characterized in that
a) the heat shield is first produced with the layers of the said materials by hot-isostatic pressing thereof, and
b) the piston body is then integrally cast on the metallic or metal-ceramic layer of the previously produced heat shield in a casting mould and the molten piston body material is joined intermetallically to the material of the metallic or metal-ceramic layer of the heat shield.
2. A method according to Claim 1, characterized in that the hot-isostatic pressing is performed in order to produce the heat shield at a pressure of approximately 1000 to 1500 bar and a temperature of approximately 1000 to 1450° C.
3. A method according to Claim 1 or 2, characterized in that the thin heat shield is produced from ceramic laminated material with a thermal conductivity of approximately 2 to 3 W/m° K such as PSZ (partial stabilized zircon [sic - zirconium] oxide), an Al-Si mixed oxide of the formula 3 A1203 x 2 Si02, Zr Si 04, aluminium titanate or silicon nitride and metallic layer or component material of iron or iron alloys.
4. A method according to Claim 1, characterized in that the piston body is integrally cast onto the previously produced heat shield by a material melt of AI casting alloys such as AI Si 12 Cu Mg Ni, Al Si 18 Cu Mg Ni, Al Si 25 Cu Mg Ni or AI Cu 4 Ni Mg.
EP85100435A 1984-02-07 1985-01-17 Insulated piston for internal combustion engines Expired EP0151952B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843404121 DE3404121A1 (en) 1984-02-07 1984-02-07 HEAT-INSULATING PISTON FOR INTERNAL COMBUSTION ENGINES
DE3404121 1984-02-07

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EP0151952A1 EP0151952A1 (en) 1985-08-21
EP0151952B1 true EP0151952B1 (en) 1989-03-29

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EP (1) EP0151952B1 (en)
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DE (2) DE3404121A1 (en)

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Also Published As

Publication number Publication date
EP0151952A1 (en) 1985-08-21
JPS60187740A (en) 1985-09-25
DE3404121A1 (en) 1985-08-08
DE3569144D1 (en) 1989-05-03
US4651630A (en) 1987-03-24

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