EP2454464A1 - Multi-part piston for an internal combustion engine and method for the production thereof - Google Patents

Multi-part piston for an internal combustion engine and method for the production thereof

Info

Publication number
EP2454464A1
EP2454464A1 EP10742706A EP10742706A EP2454464A1 EP 2454464 A1 EP2454464 A1 EP 2454464A1 EP 10742706 A EP10742706 A EP 10742706A EP 10742706 A EP10742706 A EP 10742706A EP 2454464 A1 EP2454464 A1 EP 2454464A1
Authority
EP
European Patent Office
Prior art keywords
piston
temperature
joining
cooling
solder material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP10742706A
Other languages
German (de)
French (fr)
Inventor
Joachim Schulz
Jochen Kortas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mahle International GmbH
Original Assignee
Mahle International GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mahle International GmbH filed Critical Mahle International GmbH
Publication of EP2454464A1 publication Critical patent/EP2454464A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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 
    • 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 
    • F02F3/0015—Multi-part pistons
    • F02F3/003—Multi-part pistons the parts being connected by casting, brazing, welding or clamping
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • 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
    • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
    • F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
    • F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
    • F02B23/0672—Omega-piston bowl, i.e. the combustion space having a central projection pointing towards the cylinder head and the surrounding wall being inclined towards the cylinder center axis
    • 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
    • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
    • F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
    • F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
    • F02B23/0678—Unconventional, complex or non-rotationally symmetrical shapes of the combustion space, e.g. flower like, having special shapes related to the orientation of the fuel spray jets
    • F02B23/0693—Unconventional, complex or non-rotationally symmetrical shapes of the combustion space, e.g. flower like, having special shapes related to the orientation of the fuel spray jets the combustion space consisting of step-wise widened multiple zones of different depth
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • 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
    • Y10T29/49252—Multi-element piston making
    • 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
    • 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
    • Y10T29/49263—Piston making with assembly or composite article making by coating or cladding

Definitions

  • the present invention relates to a multi-piece piston for an internal combustion engine and to a method for producing such a piston.
  • connection of upper piston part and lower piston part can cause problems here, as explained in detail in EP 1 483 493 B1.
  • the piston upper part and the piston lower part can, for example, be welded together or screwed together, wherein each of these connection techniques has specific advantages and disadvantages.
  • From the international patent application PCT / DE2008 / 01394 it is also known to connect the upper piston part and the lower piston part by means of a solder material with each other. However, no information is given about the process parameters.
  • the object of the present invention is to provide a simplified soldering method for producing a multi-part piston, which ensures a reliable solder joint between the piston top and piston lower part with the least possible effort.
  • the solution consists in a method with the features of claim 1 and in a producible according to this method piston.
  • a piston upper part and a lower piston part are produced, each with an inner support member with joining surfaces and an outer support member with joining surfaces, further that a high temperature solder material is applied in the region of at least one joining surface, that the piston upper part and the lower piston part by producing a Contact between the joining surfaces are assembled into a piston body, which is then placed in a vacuum oven and after evacuation of the vacuum furnace at a pressure of at most 10 ⁇ 2 mbar to a brazing temperature of at most 1300 0 C. is heated. Thereafter, the soldered flask is cooled at a pressure of at most 10 ⁇ 2 mbar until complete solidification of the high temperature soldering material.
  • the desired material properties of the base material of the piston according to the invention are set after heating in a vacuum oven so that no further heat treatment, in particular no flash annealing, is more necessary and the base material after the soldering process still optimal values especially with regard to its strength, hardness and Has morphology.
  • the process according to the invention is therefore of shorter duration and also less expensive than the processes known in the prior art.
  • solder materials based on nickel, cobalt and / or copper are preferred.
  • An example of a suitable solder material is the nickel-based solder L-BNi2 (according to EN 1044 or DIN 8513). With this solder material, especially when using AFP steel, a particularly strong and reliable connection between the piston upper part and piston lower part is achieved.
  • the manner of applying the solder material is at the discretion of the person skilled in the art.
  • the brazing material can, for example, be applied flatly to the at least one joining surface, in particular brushed on or printed by means of a stamp.
  • the brazing material can also be introduced into at least one depot depression arranged in the region of at least one joining surface.
  • the at least one depot recess can be designed to be particularly simple in manufacturing technology as a circumferential or rectilinear groove or as a dome-shaped depression.
  • the upper piston part and / or the lower piston part are expediently provided with at least one centering surface in order to simplify the assembly of upper piston part and lower piston part and the correct orientation of piston upper part and lower piston part to ensure each other in a particularly simple manner.
  • the at least one centering surface can also be provided with solder material. In particular, if the at least one centering surface meets at an angle to a joining surface, the solder material can be expediently mounted at an angle.
  • the piston body is preferably heated in the vacuum furnace to a brazing temperature of at least 1000 0 C in order to achieve optimum distribution of the solder material by means of the action during the soldering operation capillary forces. It is expedient to keep the soldering temperature constant for at least 5 minutes.
  • annular inner support elements can be provided which delimit an outer circumferential cooling channel and an inner cooling space.
  • central inner support elements may also be provided which delimit an outer circumferential cooling channel which extends over a large area below the piston crown. In both cases, a particularly good cooling effect is caused by the cooling oil circulating in the cooling channel or cooling space.
  • the piston according to the invention preferably consists of a steel base material with a ferritic-pearlitic structure, for example an AFP steel.
  • the hardness of the base material desired by the method according to the invention is preferably 230 HB to 300 HB.
  • FIG. 1 shows a section through a first embodiment of a piston according to the invention.
  • FIG. 2 shows a section through a second embodiment of a piston according to the invention
  • 3 shows a temperature-time diagram of the cooling phase of the method according to the invention.
  • FIG. 1 shows a first exemplary embodiment of a piston 10 according to the invention in a representation as a composite piston body before the soldering process.
  • the piston 10 is composed of a piston upper part 11 and a piston lower part 12, which are forged in the embodiment of an AFP steel.
  • the piston upper part 11 has a combustion bowl 13, a peripheral top land 14 and a circumferential ring section 15.
  • the piston lower part 12 has a piston shaft 16 and hubs 17 with hub bores 18 for receiving a piston pin (not shown).
  • the upper piston part 11 and the lower piston part 12 form a peripheral outer cooling channel 19 and a central inner cooling space 21.
  • the piston upper part 11 has an inner support element 22 and an outer support element 23.
  • the inner support element 22 is arranged on the underside of the piston upper part 11 in an annular circumferential manner and has a joining surface 24.
  • the inner support member 22 further forms a part of the peripheral wall of the inner cooling space 21.
  • the outer support member 23 of the piston upper part 11 is formed in the embodiment within the ring portion 15 and has a joining surface 25.
  • the inner support element 22 also has overflow channels 31 for the passage of cooling oil from the outer cooling channel 19 into the inner cooling space 21.
  • the lower piston part 12 likewise has an inner support element 26 and an outer support element 27.
  • the inner support element 26 is arranged circumferentially on the upper side of the piston lower part 12 and has a joining surface 28.
  • the inner support member 26 further forms a part of the circumferential wall of the inner cooling space 21.
  • the outer support member 27 is formed in the embodiment within the ring portion 15 and has a joining surface 29. Centering surface 32
  • the inner support element 26 also has a circumferential centering surface 32, which in the exemplary embodiment is at right angles to the joining surface 28.
  • a circumferential collar can be attached to the lower piston part 12, with which the joining surface 29 is widened radially and a larger surface area for the application of soldering. material offers. The federal government is after the soldering process, for example. In the finishing of the piston, removed again (not shown).
  • the piston 10 is shown as a composite piston body before the soldering process.
  • the high-temperature solder material is applied in the form of a solder deposits 33 in the angle between the joining surface 28 and centering surface 32 of the inner support member 26 of the piston base 12.
  • the solder material can be applied as a circulating solder deposit 33 or in the form of a plurality of point or line-shaped solder deposits.
  • solder material in the form of a thin layer on at least one of the outer joining surfaces 25 and 29 of the upper piston part 11 and / or lower piston part 12 is applied (not shown).
  • the brazing material can also be applied exclusively flat on the joining surfaces, without providing Lotdepots.
  • FIG. 2 shows a second exemplary embodiment of a piston 110 according to the invention in a representation as a composite piston body before the soldering process.
  • the piston 110 essentially corresponds to the piston 10 according to FIG. 1.
  • the upper piston part 11 and the lower piston part 12 only form a peripheral outer cooling channel 119.
  • the piston upper part 11 on an inner support member 122, which is arranged centrally on the underside of the piston upper part 11 and with a joining surface 124.
  • the lower piston part 12 has an inner support element 126, which is arranged centrally on the upper side of the piston lower part 12 and provided with a joining surface 128.
  • the resulting cooling channel 119 extends particularly widely under the combustion bowl 13, resulting in an efficient cooling effect.
  • the outer support member 123 of the piston upper part 11 is formed in this embodiment below the ring portion 15.
  • the outer support element 123 has a joining surface 125 and a circumferential centering surface 134, which in the exemplary embodiment is at right angles to the joining surface 125.
  • the outer support member 127 of the piston lower part 12 is accordingly also formed below the ring portion 15 and has a joining surface 129.
  • the piston 110 is also shown as a composite piston body before the soldering process.
  • the high-temperature solder material in the form of a solder deposit 133 is applied in the angle between the joining surface 125 and the centering surface 134 of the outer support element 123 of the piston upper part 11.
  • the solder material can be applied as a circulating solder deposit 133 or in the form of a plurality of point or line-shaped solder deposits.
  • a further dome-shaped solder deposit 135 filled with solder material is provided in the joining surface 128 of the central support member of the piston lower part 12.
  • the upper piston part 11 and the lower piston part 12 are brought along their joining surfaces 124, 125 and 128, 129 into contact and assembled to form a piston body, wherein the centering surface 134 ensures the correct orientation of piston upper part 11 and piston lower part 12.
  • the soldering method for manufacturing the pistons 10, 110 was performed as follows in this embodiment.
  • the basic material chosen was AFM 38MnVS6 according to DIN-EN10267 and material number 1.1303.
  • As a high-temperature solder material the nickel-based solder L-BNi2 according to EN 1044 and DIN 8513 was selected.
  • the target composition of this solder material is 7 wt .-% chromium, 3.1 wt .-% boron, 4.5 wt .-% silicon, 3 wt .-% iron and at most 0.06 wt .-% carbon and nickel to 100 % By weight (all percentages based on the solder material).
  • the range of the melting temperature along the solidus-liquidus line in the melt diagram is 970 0 C to 1000 0 C.
  • the range of the soldering temperature is 1010 ° C to 1180 ° C.
  • the piston bodies were placed in a known high-temperature vacuum furnace with a cooling gas device.
  • the vacuum oven was evacuated until a pressure of about 5x10 3 mbar was reached.
  • the vacuum oven was heated to a soldering temperature of 1150 0 C.
  • the pressure was at most 10 '2 mbar during the heating phase.
  • the soldering temperature was min in the exemplary embodiment 15 to 60 held min constant, where the pressure is up to about 5x10 "4 mbar sank. Then, the vacuum oven was cooled (see FIG.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)

Abstract

The present invention relates to a method for producing a multi-part piston (10, 110) for an internal combustion engine, comprising the following method steps: producing an upper piston part (11) and a lower piston part (12), each having an inner support element (22, 26; 122, 126) having joining surfaces (24, 28; 124, 128) and an outer support element (23, 27; 123, 127) having joining surfaces (25, 29; 125, 129), applying a high-temperature solder material in the area of at least one joining surface (24, 28 or 25, 29; 124, 128 or 125, 129), assembling the upper piston part (11) and the lower piston part (12) to form a piston body by establishing a contact between the joining surfaces (24, 28 or 25, 29; 124, 128 or 125, 129), placing the piston body in a vacuum furnace and evacuating the vacuum furnace; heating the piston body at a pressure of at most 10-2 mbar to a soldering temperature of at most 1300°C; cooling the soldered piston (10, 110) at a pressure of at most 10-2 mbar until the high-temperature solder material is completely solidified. The present invention further relates to a piston (10, 110) that can be produced by means of said method.

Description

Mehrteiliger Kolben für einen Verbrennungsmotor und  Multi-part piston for an internal combustion engine and
Verfahren zu seiner Herstellung  Process for its preparation
Die vorliegende Erfindung betrifft einen mehrteiligen Kolben für einen Verbrennungsmotor sowie ein Verfahren zur Herstellung eines solchen Kolbens. The present invention relates to a multi-piece piston for an internal combustion engine and to a method for producing such a piston.
Die Verbindung von Kolbenoberteil und Kolbenunterteil kann hierbei Probleme bereiten, wie es in der EP 1 483 493 B1 ausführlich erläutert ist. Das Kolbenoberteil und das Kolbenunterteil können bspw. miteinander verschweißt oder miteinander verschraubt sein, wobei jede dieser Verbindungstechniken spezifische Vor- und Nachteile aufweist. Aus der internationalen Patentanmeldung PCT/DE2008/01394 ist es ferner bekannt, das Kolbenoberteil und das Kolbenunterteil mittels eines Lotwerkstoffs miteinander zu verbinden. Es werden jedoch keine Angaben zu den Verfahrensparametern gemacht. The connection of upper piston part and lower piston part can cause problems here, as explained in detail in EP 1 483 493 B1. The piston upper part and the piston lower part can, for example, be welded together or screwed together, wherein each of these connection techniques has specific advantages and disadvantages. From the international patent application PCT / DE2008 / 01394 it is also known to connect the upper piston part and the lower piston part by means of a solder material with each other. However, no information is given about the process parameters.
Die Aufgabe der vorliegenden Erfindung besteht darin, ein vereinfachtes Lötverfahren zur Herstellung eines mehrteiligen Kolbens bereitzustellen, das bei möglichst geringem Aufwand eine zuverlässige Lötverbindung zwischen Kolbenoberteil und Kolbenunterteil gewährleistet. The object of the present invention is to provide a simplified soldering method for producing a multi-part piston, which ensures a reliable solder joint between the piston top and piston lower part with the least possible effort.
Die Lösung besteht in einem Verfahren mit den Merkmalen des Patentanspruchs 1 und in einem gemäß diesem Verfahren herstellbaren Kolben. The solution consists in a method with the features of claim 1 and in a producible according to this method piston.
Erfindungsgemäß ist vorgesehen, dass zunächst ein Kolbenoberteil und ein Kolbenunterteil mit jeweils einem inneren Stützelement mit Fügeflächen und einem äußeren Stützelement mit Fügeflächen hergestellt werden, dass ferner ein Hochtemperatur- Lotwerkstoff im Bereich mindestens einer Fügefläche aufgebracht wird, dass das Kolbenoberteil und das Kolbenunterteil durch Herstellen eines Kontakts zwischen den Fügeflächen zu einem Kolbenkörper zusammengesetzt werden, der anschließend in einen Vakuumofen verbracht und nach Evakuieren des Vakuumofens bei einem Druck von höchstens 10~2 mbar auf eine Löttemperatur von höchstens 13000C erwärmt wird. Danach wird der gelötete Kolben bei einem Druck von höchstens 10~2 mbar bis zur vollständigen Erstarrung des Hochtemperatur-Lotwerkstoffs abgekühlt. According to the invention, it is provided that first a piston upper part and a lower piston part are produced, each with an inner support member with joining surfaces and an outer support member with joining surfaces, further that a high temperature solder material is applied in the region of at least one joining surface, that the piston upper part and the lower piston part by producing a Contact between the joining surfaces are assembled into a piston body, which is then placed in a vacuum oven and after evacuation of the vacuum furnace at a pressure of at most 10 ~ 2 mbar to a brazing temperature of at most 1300 0 C. is heated. Thereafter, the soldered flask is cooled at a pressure of at most 10 ~ 2 mbar until complete solidification of the high temperature soldering material.
Durch das erfindungsgemäße Verfahren werden die gewünschten Werkstoffeigenschaften des Grundwerkstoffs des erfindungsgemäßen Kolbens nach dem Erwärmen im Vakuumofen so eingestellt, dass keine weitere Wärmebehandlung, insbesondere kein Entspannungsglühen, mehr notwendig ist und der Grundwerkstoff nach dem Lötvorgang dennoch möglichst optimale Werte insbesondere bezüglich seiner Festigkeit, Härte und Gefügemorphologie aufweist. Das erfindungsgemäße Verfahren ist somit von kürzerer Dauer und auch kostengünstiger als die im Stand der Technik bekannten Verfahren. By the method according to the invention, the desired material properties of the base material of the piston according to the invention are set after heating in a vacuum oven so that no further heat treatment, in particular no flash annealing, is more necessary and the base material after the soldering process still optimal values especially with regard to its strength, hardness and Has morphology. The process according to the invention is therefore of shorter duration and also less expensive than the processes known in the prior art.
Vorteilhafte Weiterbildungen ergeben sich aus den Unteransprüchen. Advantageous developments emerge from the subclaims.
Grundsätzlich sind alle bekannten Hochtemperatur-Lotwerkstoffe geeignet. Es werden jedoch Lotwerkstoffe auf der Basis von Nickel, Kobalt und/oder Kupfer bevorzugt. Ein Beispiel für einen geeigneten Lotwerkstoff ist das Nickelbasislot L-BNi2 (gemäß EN 1044 bzw. DIN 8513). Mit diesem Lotwerkstoff wird, insbesondere bei Verwendung von AFP-Stahl, eine besonders feste und zuverlässige Verbindung zwischen Kolbenoberteil und Kolbenunterteil erzielt. In principle, all known high-temperature brazing materials are suitable. However, solder materials based on nickel, cobalt and / or copper are preferred. An example of a suitable solder material is the nickel-based solder L-BNi2 (according to EN 1044 or DIN 8513). With this solder material, especially when using AFP steel, a particularly strong and reliable connection between the piston upper part and piston lower part is achieved.
Die Art und Weise des Auftragens des Lotwerkstoffs steht im Belieben des Fachmanns. Der Lotwerkstoff kann bspw. flächig auf die mindestens eine Fügefläche aufgetragen, insbesondere aufgestrichen oder mittels Stempel aufgedruckt werden. Der Lotwerkstoff kann aber auch in mindestens eine im Bereich mindestens einer Fügefläche angeordnete Depotvertiefung eingebracht werden. Hierbei kann die mindestens eine Depotvertiefung in herstellungstechnisch besonders einfacher Weise als umlaufende oder geradlinige Nut oder als kalottenförmige Vertiefung ausgebildet sein. The manner of applying the solder material is at the discretion of the person skilled in the art. The brazing material can, for example, be applied flatly to the at least one joining surface, in particular brushed on or printed by means of a stamp. However, the brazing material can also be introduced into at least one depot depression arranged in the region of at least one joining surface. In this case, the at least one depot recess can be designed to be particularly simple in manufacturing technology as a circumferential or rectilinear groove or as a dome-shaped depression.
Das Kolbenoberteil und/oder das Kolbenunterteil sind zweckmäßigerweise mit mindestens einer Zentrierfläche versehen, um das Zusammensetzen von Kolbenoberteil und Kolbenunterteil zu vereinfachen und die korrekte Orientierung von Kolbenoberteil und Kolbenunterteil zueinander auf besonders einfache Weise zu gewährleisten. Zur Optimierung der Lotverbindung kann die mindestens eine Zentrierfläche ebenfalls mit Lotwerkstoff versehen werden. Insbesondere wenn die mindestens eine Zentrierfläche in einem Winkel auf eine Fügefläche trifft, kann der Lotwerkstoff zweckmäßigerweise im Winkel angebracht werden. The upper piston part and / or the lower piston part are expediently provided with at least one centering surface in order to simplify the assembly of upper piston part and lower piston part and the correct orientation of piston upper part and lower piston part to ensure each other in a particularly simple manner. To optimize the solder connection, the at least one centering surface can also be provided with solder material. In particular, if the at least one centering surface meets at an angle to a joining surface, the solder material can be expediently mounted at an angle.
Der Kolbenkörper wird im Vakuumofen vorzugsweise auf eine Löttemperatur von mindestens 10000C erwärmt, um eine optimale Verteilung des Lotwerkstoffs mittels der während des Lötvorgangs wirkenden Kapillarkräfte zu erzielen. Es ist zweckmäßig, die Löttemperatur über mindestens 5 min konstant zu halten. The piston body is preferably heated in the vacuum furnace to a brazing temperature of at least 1000 0 C in order to achieve optimum distribution of the solder material by means of the action during the soldering operation capillary forces. It is expedient to keep the soldering temperature constant for at least 5 minutes.
Das erfindungsgemäße Verfahren ist für alle mehrteiligen Kolben geeignet. Es können bspw. ringförmige innere Stützelemente vorgesehen sein, die einen äußeren umlaufenden Kühlkanal und einen inneren Kühlraum begrenzen. Es können aber auch mittige innere Stützelemente vorgesehen sein, die einen äußeren umlaufenden Kühlkanal begrenzen, welcher sich über einen großen Bereich unterhalb des Kolbenbodens erstreckt. In beiden Fällen wird eine besonders gute Kühlwirkung durch das im Kühlkanal bzw. Kühlraum zirkulierende Kühlöl bewirkt. The method according to the invention is suitable for all multi-part pistons. For example, annular inner support elements can be provided which delimit an outer circumferential cooling channel and an inner cooling space. However, central inner support elements may also be provided which delimit an outer circumferential cooling channel which extends over a large area below the piston crown. In both cases, a particularly good cooling effect is caused by the cooling oil circulating in the cooling channel or cooling space.
Der erfindungsgemäße Kolben besteht vorzugsweise aus einem Stahl- Grundwerkstoff mit ferritisch-perlitischem Gefüge, bspw. einem AFP-Stahl. Die mit dem erfindungsgemäßen Verfahren angestrebte Härte des Grundwerkstoffs beträgt vorzugsweise 230 HB bis 300 HB. The piston according to the invention preferably consists of a steel base material with a ferritic-pearlitic structure, for example an AFP steel. The hardness of the base material desired by the method according to the invention is preferably 230 HB to 300 HB.
Ausführungsbeispiele der Erfindung werden im Folgenden anhand der beigefügten Zeichnungen näher erläutert. Es zeigen in einer schematischen, nicht maßstabsgetreuen Darstellung: Embodiments of the invention are explained in more detail below with reference to the accompanying drawings. In a schematic, not to scale representation:
Fig. 1 einen Schnitt durch ein erstes Ausführungsbeispiel eines erfindungsgemäßen Kolbens; 1 shows a section through a first embodiment of a piston according to the invention.
Fig. 2 einen Schnitt durch ein zweites Ausführungsbeispiel eines erfindungsgemäßen Kolbens; Fig. 3 ein Temperatur-Zeit-Diagramm der Abkühlphase des erfindungsgemäßen Verfahrens. 2 shows a section through a second embodiment of a piston according to the invention; 3 shows a temperature-time diagram of the cooling phase of the method according to the invention.
Figur 1 zeigt ein erstes Ausführungsbeispiel eines erfindungsgemäßen Kolbens 10 in einer Darstellung als zusammengesetzter Kolbenkörper vor dem Lötvorgang. Der Kolben 10 setzt sich zusammen aus einem Kolbenoberteil 11 und einem Kolbenunterteil 12, die im Ausführungsbeispiel aus einem AFP-Stahl geschmiedet sind. Das Kolbenoberteil 11 weist eine Verbrennungsmulde 13, einen umlaufenden Feuersteg 14 und eine umlaufende Ringpartie 15 auf. Das Kolbenunterteil 12 weist einen Kolbenschaft 16 und Naben 17 mit Nabenbohrungen 18 zur Aufnahme eines Kolbenbolzens (nicht dargestellt) auf. Das Kolbenoberteil 11 und das Kolbenunterteil 12 bilden einen umlaufenden äußeren Kühlkanal 19 und einen zentrischen inneren Kühlraum 21. FIG. 1 shows a first exemplary embodiment of a piston 10 according to the invention in a representation as a composite piston body before the soldering process. The piston 10 is composed of a piston upper part 11 and a piston lower part 12, which are forged in the embodiment of an AFP steel. The piston upper part 11 has a combustion bowl 13, a peripheral top land 14 and a circumferential ring section 15. The piston lower part 12 has a piston shaft 16 and hubs 17 with hub bores 18 for receiving a piston pin (not shown). The upper piston part 11 and the lower piston part 12 form a peripheral outer cooling channel 19 and a central inner cooling space 21.
Das Kolbenoberteil 11 weist ein inneres Stützelement 22 und ein äußeres Stützelement 23 auf. Das innere Stützelement 22 ist an der Unterseite des Kolbenoberteils 11 ringförmig umlaufend angeordnet und weist eine Fügefläche 24 auf. Das innere Stützelement 22 bildet ferner einen Teil der umlaufenden Wand des inneren Kühlraums 21. Das äußere Stützelement 23 des Kolbenoberteils 11 ist im Ausführungsbeispiel innerhalb der Ringpartie 15 ausgebildet und weist eine Fügefläche 25 auf. Das innere Stützelement 22 weist ferner Überlaufkanäle 31 zum Übertritt von Kühlöl aus dem äußeren Kühlkanal 19 in den inneren Kühlraum 21 auf. The piston upper part 11 has an inner support element 22 and an outer support element 23. The inner support element 22 is arranged on the underside of the piston upper part 11 in an annular circumferential manner and has a joining surface 24. The inner support member 22 further forms a part of the peripheral wall of the inner cooling space 21. The outer support member 23 of the piston upper part 11 is formed in the embodiment within the ring portion 15 and has a joining surface 25. The inner support element 22 also has overflow channels 31 for the passage of cooling oil from the outer cooling channel 19 into the inner cooling space 21.
Das Kolbenunterteil 12 weist ebenfalls ein inneres Stützelement 26 und ein äußeres Stützelement 27 auf. Das innere Stützelement 26 ist an der Oberseite des Kolbenunterteils 12 umlaufend angeordnet und weist eine Fügefläche 28 auf. Das innere Stützelement 26 bildet ferner einen Teil der umlaufenden Wand des inneren Kühlraums 21. Das äußere Stützelement 27 ist im Ausführungsbeispiel innerhalb der Ringpartie 15 ausgebildet und weist eine Fügefläche 29 auf. Zentrierfläche 32 Das innere Stützelement 26 weist ferner eine umlaufende Zentrierfläche 32 auf, die im Ausführungsbeispiel im rechten Winkel auf der Fügefläche 28 steht. Ferner kann am Kolbenunterteil 12 ein umlaufender Bund angebracht sein, mit dem die Fügefläche 29 radial verbreitert wird und eine größere Oberfläche für das Auftragen des Lot- werkstoffs bietet. Der Bund wird nach dem Lötvorgang, bspw. bei der Fertigbearbeitung des Kolbens, wieder entfernt (nicht dargestellt). The lower piston part 12 likewise has an inner support element 26 and an outer support element 27. The inner support element 26 is arranged circumferentially on the upper side of the piston lower part 12 and has a joining surface 28. The inner support member 26 further forms a part of the circumferential wall of the inner cooling space 21. The outer support member 27 is formed in the embodiment within the ring portion 15 and has a joining surface 29. Centering surface 32 The inner support element 26 also has a circumferential centering surface 32, which in the exemplary embodiment is at right angles to the joining surface 28. Furthermore, a circumferential collar can be attached to the lower piston part 12, with which the joining surface 29 is widened radially and a larger surface area for the application of soldering. material offers. The federal government is after the soldering process, for example. In the finishing of the piston, removed again (not shown).
In Figur 1 ist der Kolben 10 als zusammengesetzter Kolbenkörper vor dem Lötvorgang dargestellt. Bei diesem Ausführungsbeispiel wird der Hochtemperatur- Lotwerkstoff in Form eine Lotdepots 33 in den Winkel zwischen Fügefläche 28 und Zentrierfläche 32 des inneren Stützelements 26 des Kolbenunterteils 12 aufgetragen. Der Lotwerkstoff kann als ein umlaufendes Lotdepot 33 oder in Form mehrerer punkt- oder linienförmiger Lotdepots aufgetragen werden. Zusätzlich wird im Ausführungsbeispiel Lotwerkstoff in Form einer dünnen Schicht auf mindestens eine der äußeren Fügeflächen 25 bzw. 29 des Kolbenoberteils 11 und/oder Kolbenunterteils 12 aufgetragen (nicht dargestellt). Dies ist jedoch nicht zwingend erforderlich. In einer anderen Variante kann der Lotwerkstoff auch ausschließlich flächig auf die Fügeflächen aufgetragen werden, ohne Lotdepots vorzusehen. In Figure 1, the piston 10 is shown as a composite piston body before the soldering process. In this embodiment, the high-temperature solder material is applied in the form of a solder deposits 33 in the angle between the joining surface 28 and centering surface 32 of the inner support member 26 of the piston base 12. The solder material can be applied as a circulating solder deposit 33 or in the form of a plurality of point or line-shaped solder deposits. In addition, in the exemplary embodiment solder material in the form of a thin layer on at least one of the outer joining surfaces 25 and 29 of the upper piston part 11 and / or lower piston part 12 is applied (not shown). However, this is not mandatory. In another variant, the brazing material can also be applied exclusively flat on the joining surfaces, without providing Lotdepots.
Anschließend werden das Kolbenoberteil 11 und das Kolbenunterteil 12 entlang ihrer Fügeflächen 24, 25 bzw. 28, 29 in Kontakt gebracht und zu einem Kolbenkörper zusammengesetzt, wobei die Zentrierfläche 32 die korrekte Orientierung von Kolbenoberteil 11 und Kolbenunterteil 12 gewährleistet. Subsequently, the upper piston part 11 and the lower piston part 12 are brought along their joining surfaces 24, 25 and 28, 29 into contact and assembled to form a piston body, wherein the centering surface 32 ensures the correct orientation of piston upper part 11 and piston lower part 12.
Figur 2 zeigt ein zweites Ausführungsbeispiel eines erfindungsgemäßen Kolbens 110 in einer Darstellung als zusammengesetzter Kolbenkörper vor dem Lötvorgang. Der Kolben 110 entspricht im Wesentlichen dem Kolben 10 gemäß Figur 1. FIG. 2 shows a second exemplary embodiment of a piston 110 according to the invention in a representation as a composite piston body before the soldering process. The piston 110 essentially corresponds to the piston 10 according to FIG. 1.
Der wichtigste Unterschied besteht darin, dass das Kolbenoberteil 11 und das Kolbenunterteil 12 lediglich einen umlaufenden äußeren Kühlkanal 119 bilden. Hierfür weist das Kolbenoberteil 11 ein inneres Stützelement 122 auf, das an der Unterseite des Kolbenoberteils 11 mittig angeordnet und mit einer Fügefläche 124 auf. Dementsprechend weist das Kolbenunterteil 12 ein inneres Stützelement 126 auf, das an der Oberseite des Kolbenunterteils 12 mittig angeordnet und mit einer Fügefläche 128 versehen ist. Der resultierende Kühlkanal 119 erstreckt sich dementsprechend besonders weitläufig unter der Verbrennungsmulde 13, so dass sich eine effiziente Kühlwirkung ergibt. Ein weiterer Unterschied besteht darin, dass das äußere Stützelement 123 des Kolbenoberteils 11 bei diesem Ausführungsbeispiel unterhalb der Ringpartie 15 ausgebildet ist. Das äußere Stützelement 123 weist eine Fügefläche 125 und eine umlaufende Zentrierfläche 134 auf, die im Ausführungsbeispiel im rechten Winkel auf der Fügefläche 125 steht. Das äußere Stützelement 127 des Kolbenunterteils 12 ist dementsprechend ebenfalls unterhalb der Ringpartie 15 ausgebildet und weist eine Fügefläche 129 auf. The most important difference is that the upper piston part 11 and the lower piston part 12 only form a peripheral outer cooling channel 119. For this purpose, the piston upper part 11 on an inner support member 122, which is arranged centrally on the underside of the piston upper part 11 and with a joining surface 124. Accordingly, the lower piston part 12 has an inner support element 126, which is arranged centrally on the upper side of the piston lower part 12 and provided with a joining surface 128. Accordingly, the resulting cooling channel 119 extends particularly widely under the combustion bowl 13, resulting in an efficient cooling effect. Another difference is that the outer support member 123 of the piston upper part 11 is formed in this embodiment below the ring portion 15. The outer support element 123 has a joining surface 125 and a circumferential centering surface 134, which in the exemplary embodiment is at right angles to the joining surface 125. The outer support member 127 of the piston lower part 12 is accordingly also formed below the ring portion 15 and has a joining surface 129.
In Figur 2 ist der Kolben 110 ebenfalls als zusammengesetzter Kolbenkörper vor dem Lötvorgang dargestellt. Bei diesem Ausführungsbeispiel wird der Hochtemperatur-Lotwerkstoff in Form eines Lotdepots 133 in den Winkel zwischen Fügefläche 125 und Zentrierfläche 134 des äußeren Stützelements 123 des Kolbenoberteils 11 aufgetragen. Der Lotwerkstoff kann als ein umlaufendes Lotdepot 133 oder in Form mehrerer punkt- oder linienförmiger Lotdepots aufgetragen werden. Ferner ist bei diesem Ausführungsbeispiel in der Fügefläche 128 des mittigen Stützelements des Kolbenunterteils 12 ein weiteres kalottenförmiges, mit Lotwerkstoff gefülltes Lotdepot 135 vorgesehen. In Figure 2, the piston 110 is also shown as a composite piston body before the soldering process. In this exemplary embodiment, the high-temperature solder material in the form of a solder deposit 133 is applied in the angle between the joining surface 125 and the centering surface 134 of the outer support element 123 of the piston upper part 11. The solder material can be applied as a circulating solder deposit 133 or in the form of a plurality of point or line-shaped solder deposits. Further, in this embodiment, in the joining surface 128 of the central support member of the piston lower part 12, a further dome-shaped solder deposit 135 filled with solder material is provided.
Anschließend werden das Kolbenoberteil 11 und das Kolbenunterteil 12 entlang ihrer Fügeflächen 124, 125 bzw. 128, 129 in Kontakt gebracht und zu einem Kolbenkörper zusammengesetzt, wobei die Zentrierfläche 134 die korrekte Orientierung von Kolbenoberteil 11 und Kolbenunterteil 12 gewährleistet. Subsequently, the upper piston part 11 and the lower piston part 12 are brought along their joining surfaces 124, 125 and 128, 129 into contact and assembled to form a piston body, wherein the centering surface 134 ensures the correct orientation of piston upper part 11 and piston lower part 12.
Das Lötverfahren zum Herstellen der Kolben 10, 110 wurde bei diesen Ausführungsbeispiel wie folgt durchgeführt. Als Grundwerkstoff wurde der AFP-Stahl 38MnVS6 gemäß DIN-EN10267 und Werkstoffnummer 1.1303 gewählt. Als Hochtemperatur- Lotwerkstoff wurde das Nickelbasislot L-BNi2 gemäß EN 1044 bzw. DIN 8513 gewählt. Die Sollzusammensetzung dieses Lotwerkstoffs beträgt 7 Gew.-% Chrom, 3,1 Gew.-% Bor, 4,5 Gew.-% Silizium, 3 Gew.-% Eisen und maximal 0,06 Gew.-% Kohlenstoff sowie Nickel bis 100 Gew.-% (alle Prozentangaben bezogen auf den Lotwerkstoff). Der Bereich der Schmelztemperatur entlang der Solidus-Liquidus-Linie im Schmelzdiagramm beträgt 9700C bis 10000C. Der Bereich der Löttemperatur beträgt 1010°C bis 1180°C. Die Kolbenkörper wurden in einen an sich bekannten Hochtemperatur-Vakuumofen mit Kühlgasvorrichtung verbracht. Der Vakuumofen wurde evakuiert, bis ein Druck von etwa 5x103 mbar erreicht war. Dann wurde der Vakuumofen auf eine Löttemperatur von 11500C aufgeheizt. Der Druck betrug während der Aufheizphase höchstens 10'2 mbar. Die Löttemperatur wurde im Ausführungsbeispiel 15 min bis 60 min konstant gehalten, wobei der Druck bis auf etwa 5x10"4 mbar sank. Dann wurde der Vakuumofen abgekühlt (vgl. Figur 3), bis der Lotwerkstoff vollkommen erstarrt war (im Ausführungsbeispiel ca. 9600C). Ab dieser Temperatur kann durch Einblasen von Kühlgas, bspw. Stickstoff, eine beschleunigte Abkühlung herbeigeführt werden. Der Abkühlprozess wurde so gesteuert, dass die resultierenden Kolben 10, 110 eine ferri- tisch-perlitische Gefügeausbildung im AFP-Stahl und eine Härte von 230 HB bis 300 HB aufwiesen. The soldering method for manufacturing the pistons 10, 110 was performed as follows in this embodiment. The basic material chosen was AFM 38MnVS6 according to DIN-EN10267 and material number 1.1303. As a high-temperature solder material, the nickel-based solder L-BNi2 according to EN 1044 and DIN 8513 was selected. The target composition of this solder material is 7 wt .-% chromium, 3.1 wt .-% boron, 4.5 wt .-% silicon, 3 wt .-% iron and at most 0.06 wt .-% carbon and nickel to 100 % By weight (all percentages based on the solder material). The range of the melting temperature along the solidus-liquidus line in the melt diagram is 970 0 C to 1000 0 C. The range of the soldering temperature is 1010 ° C to 1180 ° C. The piston bodies were placed in a known high-temperature vacuum furnace with a cooling gas device. The vacuum oven was evacuated until a pressure of about 5x10 3 mbar was reached. Then the vacuum oven was heated to a soldering temperature of 1150 0 C. The pressure was at most 10 '2 mbar during the heating phase. The soldering temperature was min in the exemplary embodiment 15 to 60 held min constant, where the pressure is up to about 5x10 "4 mbar sank. Then, the vacuum oven was cooled (see FIG. 3) until the brazing filler material was completely solidifies (in the embodiment about 960 0 C. From this temperature, an accelerated cooling can be brought about by blowing in cooling gas, for example nitrogen The cooling process was controlled so that the resulting pistons 10, 110 have a microstructure of the ferrite-pearlitic structure in AFP steel and a hardness of 230 HB to 300 HB.
Bei der Steuerung des Abkühlprozesses sind in der Regel verschiedene, dem Fachmann bekannte Parameter zu berücksichtigen. Am einfachsten ist die Orientierung an so genannten, dem Fachmann bekannten, Zeit-Temperatur-Umwandlungs- Diagrammen (ZTU), die in der Regel vom Hersteller des Grundwerkstoffs zur Verfügung gestellt werden, wie es auch beim AFP-Stahl 38MnVS6 der Fall ist. Als wesentliche Parameter zu berücksichtigen sind aber auch der Aufbau des Vakuumofens sowie Größe, Geometrie und Anzahl der zu verarbeitenden Werkstücke, da diese Parameter die Wärmekapazitäten der Werkstücke beeinflussen. Auch physikalische Effekte wie Wärmeleitung und Wärmestrahlung sowie durch Gefügeumwandlungen bedingte thermische Effekte beeinflussen den Abkühlungsprozess, da sie sich über den jeweiligen Temperaturbereich nicht immer linear verändern. When controlling the cooling process, as a rule, various parameters known to the person skilled in the art are to be taken into account. The easiest way is the orientation on so-called, time-temperature conversion diagrams (ZTU) known to those skilled in the art, which are usually provided by the manufacturer of the base material, as is the case with the AFP steel 38MnVS6. However, the design of the vacuum furnace, as well as the size, geometry and number of workpieces to be processed, must also be taken into consideration as important parameters, since these parameters influence the heat capacities of the workpieces. Physical effects such as heat conduction and heat radiation as well as thermal effects due to microstructural changes also influence the cooling process since they do not always change linearly over the respective temperature range.

Claims

Patentansprüche claims
1. Verfahren zur Herstellung eines mehrteiligen Kolbens (10, 110) für einen Verbrennungsmotor mit den folgenden Verfahrensschritten: A method of manufacturing a multi-piece piston (10, 110) for an internal combustion engine, comprising the steps of:
a) Herstellen eines Kolbenoberteils (11 ) und eines Kolbenunterteils (12) mit jeweils einem inneren Stützelement (22, 26; 122, 126) mit Fügeflächen (24, 28; 124, 128) und einem äußeren Stützelement (23, 27; 123, 127) mit Fügeflächen (25, 29; 125, 129),  a) producing a piston upper part (11) and a lower piston part (12) each having an inner support element (22, 26; 122, 126) with joining surfaces (24, 28, 124, 128) and an outer support element (23, 27; 127) with joining surfaces (25, 29; 125, 129),
b) Aufbringen eines Hochtemperatur-Lotwerkstoffs im Bereich mindestens einer Fügefläche (24, 28 bzw. 25, 29; 124, 128 bzw. 125,129), c) Zusammensetzen von Kolbenoberteil (11) und Kolbenunterteil (12) zu einem Kolbenkörper durch Herstellen eines Kontakts zwischen den Fügeflächen (24, 28 bzw. 25, 29; 124, 128 bzw. 125,129),  b) applying a high-temperature brazing material in the region of at least one joining surface (24, 28 or 25, 29; 124, 128 or 125, 129), c) assembling the piston upper part (11) and lower piston part (12) to form a piston body by making a contact between the joining surfaces (24, 28 or 25, 29, 124, 128 and 125, 129, respectively),
d) Verbringen des Kolbenkörpers in einen Vakuumofen und Evakuieren des Vakuumofens;  d) moving the piston body into a vacuum oven and evacuating the vacuum furnace;
e) Erwärmen des Kolbenkörpers bei einem Druck von höchstens 10'2 mbar auf eine Löttemperatur von höchstens 13000C; e) heating the piston body at a pressure of at most 10 '2 mbar to a soldering temperature of at most 1300 0 C;
f) Abkühlen des gelöteten Kolbens (10, 110) bei einem Druck von höchstens 10~2 mbar bis zur vollständigen Erstarrung des Hochtemperatur- Lotwerkstoffs. f) cooling the soldered bulb (10, 110) at a pressure of at most 10 ~ 2 mbar until complete solidification of the high temperature soldering material.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass ein Hochtemperatur-Lotwerkstoff auf der Basis von Nickel, Kobalt und/oder Kupfer verwendet wird. 2. The method according to claim 1, characterized in that a high-temperature brazing material based on nickel, cobalt and / or copper is used.
3. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Lotwerkstoff flächig auf die mindestens eine Fügefläche (24, 28 bzw. 25, 29; 124, 128 bzw. 125,129) aufgetragen wird. 3. The method according to any one of the preceding claims, characterized in that the solder material is applied flat on the at least one joining surface (24, 28 or 25, 29, 124, 128 and 125.129).
4. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Lotwerkstoff in mindestens eine im Bereich mindestens einer Fügefläche angeordnete Depotvertiefung (33, 133, 135) eingebracht wird. 4. The method according to any one of the preceding claims, characterized in that the brazing material is placed in at least one in the region of at least one joining surface arranged Depotvertiefung (33, 133, 135).
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass die mindestens eine Depotvertiefung (33, 133, 135) als umlaufende oder geradlinige Nut oder als kalottenförmige Vertiefung ausgebildet wird. 5. The method according to claim 4, characterized in that the at least one depot recess (33, 133, 135) is formed as a circumferential or rectilinear groove or as a dome-shaped depression.
6. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das Kolbenoberteil (11) und/oder das Kolbenunterteil (12) mit mindestens einer Zentrierfläche (32, 134) versehen wird. 6. The method according to any one of the preceding claims, characterized in that the piston upper part (11) and / or the lower piston part (12) with at least one centering surface (32, 134) is provided.
7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, dass die mindestens eine Zentrierfläche (32, 134) mit Lotwerkstoff versehen wird. 7. The method according to claim 6, characterized in that the at least one centering surface (32, 134) is provided with solder material.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, dass die mindestens eine Zentrierfläche (32, 134) in einem Winkel auf eine Fügefläche (28, 125) trifft und der Lotwerkstoff im Winkel angebracht wird. 8. The method according to claim 7, characterized in that the at least one centering surface (32, 134) meets at an angle to a joining surface (28, 125) and the solder material is mounted at an angle.
9. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Kolbenkörper auf eine Löttemperatur von mindestens 10000C erwärmt wird. 9. The method according to any one of the preceding claims, characterized in that the piston body is heated to a soldering temperature of at least 1000 0 C.
10. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Löttemperatur mindestens 5 min konstant gehalten wird. 10. The method according to any one of the preceding claims, characterized in that the soldering temperature is kept constant for at least 5 min.
11. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass eine Abkühlgeschwindigkeit von 1 °C/min bis 50°C/min gewählt wird. 11. The method according to any one of the preceding claims, characterized in that a cooling rate of 1 ° C / min to 50 ° C / min is selected.
12. Mehrteiliger Kolben (10, 110) für einen Verbrennungsmotor, herstellbar durch ein Verfahren nach einem der Ansprüche 1 bis 11. 12. Multi-part piston (10, 110) for an internal combustion engine, producible by a method according to one of claims 1 to 11.
13. Kolben nach Anspruch 12, dadurch gekennzeichnet, dass ringförmige innere Stützelemente (22, 26) vorgesehen sind, die einen äußeren umlaufenden Kühlkanal (19) und einen inneren Kühlraum (21 ) begrenzen. 13. Piston according to claim 12, characterized in that annular inner support elements (22, 26) are provided which define an outer circumferential cooling channel (19) and an inner cooling space (21).
14. Kolben nach Anspruch 12, dadurch gekennzeichnet, dass mittige innere Stützelemente (122, 126) vorgesehen sind, die einen äußeren umlaufenden Kühlkanal (119) begrenzen. 14. Piston according to claim 12, characterized in that central inner support elements (122, 126) are provided, which delimit an outer circumferential cooling channel (119).
15. Kolben nach einem der Ansprüche 12 bis 14, dadurch gekennzeichnet, dass er aus einem Stahl-Grundwerkstoff mit ferritisch-perlitischem Gefüge und einer Härte von 230 HB bis 300 HB, insbesondere aus einem AFP-Stahl, besteht. 15. Piston according to one of claims 12 to 14, characterized in that it consists of a steel base material with a ferritic-pearlitic structure and a hardness of 230 HB to 300 HB, in particular of an AFP steel.
EP10742706A 2009-07-14 2010-06-29 Multi-part piston for an internal combustion engine and method for the production thereof Withdrawn EP2454464A1 (en)

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CN102483009B (en) 2015-04-22
WO2011006469A1 (en) 2011-01-20
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DE102009032941A1 (en) 2011-01-20
JP2012533020A (en) 2012-12-20

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