EP2864618A2 - Piston for an internal combustion engine - Google Patents

Piston for an internal combustion engine

Info

Publication number
EP2864618A2
EP2864618A2 EP13745565.5A EP13745565A EP2864618A2 EP 2864618 A2 EP2864618 A2 EP 2864618A2 EP 13745565 A EP13745565 A EP 13745565A EP 2864618 A2 EP2864618 A2 EP 2864618A2
Authority
EP
European Patent Office
Prior art keywords
piston
cooling channel
coolant
bore
piston according
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.)
Granted
Application number
EP13745565.5A
Other languages
German (de)
French (fr)
Other versions
EP2864618B1 (en
Inventor
Ulrich Bischofberger
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 EP2864618A2 publication Critical patent/EP2864618A2/en
Application granted granted Critical
Publication of EP2864618B1 publication Critical patent/EP2864618B1/en
Not-in-force legal-status Critical Current
Anticipated expiration legal-status Critical

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 
    • F02F3/16—Pistons  having cooling means
    • F02F3/18—Pistons  having cooling means the means being a liquid or solid coolant, e.g. sodium, in a closed chamber in piston
    • 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 
    • F02F3/16—Pistons  having cooling means
    • F02F3/20—Pistons  having cooling means the means being a fluid flowing through or along piston
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F01P3/06—Arrangements for cooling pistons
    • F01P3/10—Cooling by flow of coolant through 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 
    • F02F3/26—Pistons  having combustion chamber in piston head
    • 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
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • 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 
    • F02F3/16—Pistons  having cooling means
    • F02F3/20—Pistons  having cooling means the means being a fluid flowing through or along piston
    • F02F3/22—Pistons  having cooling means the means being a fluid flowing through or along piston the fluid being liquid
    • 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
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
    • F05C2201/0448—Steel

Definitions

  • the present invention relates to a piston for an internal combustion engine, having a piston head and a piston skirt, wherein the piston head has a circumferential annular portion and in the region of the annular part a circumferential cooling channel, wherein the piston skirt has hub bores provided with piston bosses, which have hub connections on the underside of the piston head are arranged, wherein the piston hubs are interconnected via running surfaces.
  • the object of the present invention is to develop a generic piston so that sets a more uniform temperature distribution between the piston head and the piston skirt during operation.
  • the solution is that extending in the region of the annular part wall of the cooling channel has an inclination and with the piston central axis forms an acute angle that at least one outwardly closed bore is provided, which is arranged between a tread and a hub bore, that the at least a bore opens into the cooling channel, that the cooling channel and the at least one bore contain a coolant in the form of a low-melting metal or a low-melting metal alloy.
  • the piston according to the invention is characterized in that the heat generated in the region of the piston crown is guided via the piston head into the piston and discharged via the comparatively large-area running surfaces. This will be in the
  • the inventively provided inclination of running in the region of the ring wall wall of the cooling channel causes the coolant during engine operation during its downward movement this area largely not touched and in the upward movement only to a small extent.
  • the coolant will be more in the
  • the inclination forms a blind spot between the coolant moving during engine operation and the wall of the cooling channel extending in the region of the annular part, so that the moving coolant has no or only little contact with the wall region lying in the blind spot.
  • the additional heating of the area between the piston hub and the piston shaft causes an additional thermal expansion of the piston shaft and thereby reduces the warm play between piston and cylinder. This is particularly advantageous when a crankcase made of a light metal material, for example. An aluminum-based material, with a higher coefficient of thermal expansion than that of the piston material is used.
  • the angle enclosed by the wall of the cooling passage extending in the region of the annular part with the piston center axis is preferably not more than 10 ° in order to avoid an excessive narrowing of the cooling passage and a concomitant reduction of the cooling power.
  • the inclination of this wall preferably begins at the level of the upper edge of the lowest annular groove of the ring part. If a combustion bowl is provided, it is advantageous if the in the
  • Low melting metals suitable for use as refrigerants are especially sodium or potassium.
  • low-melting metal alloys in particular Galinstan® alloys, low melting bismuth alloys and sodium-potassium alloys can be used.
  • GalinstanO alloys are gallium, indium and tin alloy systems that are liquid at room temperature. These alloys consist of 65 wt% to 95 wt% gallium, 5 wt% to 26 wt% indium and 0 wt% to 16 wt% tin. Preferred alloys are, for example, those with 68% by weight to 69% by weight of gallium, 21% by weight to 22% by weight of indium and 9.5% by weight to 10.5% by weight of tin ( Mp -19 ° C), 62% by weight of gallium, 22% by weight of indium and 16% by weight of tin (mp 10.7 ° C.) and 59.6% by weight of gallium, 26% by weight. % Indium and 14.4% by weight tin (ternary eutectic, mp 11 ° C).
  • Low melting bismuth alloys are well known. These include, for example, LBE (eutectic bismuth-lead alloy, mp. 124 ° C), Roses metal (50 wt .-% bismuth, 28 wt .-% lead and 22 wt .-% tin, mp.
  • Orion metal 42 wt% bismuth, 42 wt% lead and 16 wt% tin, mp 108 ° C
  • Quick solder 52 weight percent bismuth, 32 weight percent lead and 16 weight percent tin, mp 96 ° C
  • d'Arcets metal 50 weight percent bismuth, 25 weight percent lead and 25 wt% tin
  • Wood's metal 50 wt% bismuth, 25 wt% lead, 12.5 wt% tin and 12.5 wt% cadmium, mp 71 ° C
  • Lipowitz metal 50 wt% bismuth, 27 wt% lead, 13 wt% tin and 10 wt% cadmium, mp 70 ° C
  • Harper's metal 44 wt% bismuth, 25 wt%).
  • Suitable sodium-potassium alloys may contain from 40% to 90% by weight of potassium. Particularly suitable is the eutectic alloy NaK with 78 wt .-% potassium and 22 wt .-% sodium (mp. -12.6 ° C).
  • the coolant may additionally contain lithium and / or lithium nitride. If nitrogen is used as a protective gas during filling, this can react with the lithium to lithium nitride and be removed in this way from the cooling channel.
  • the coolant may further contain sodium oxides and / or potassium oxides if, during filling, any existing dry air has reacted with the coolant.
  • four holes are provided, which are arranged between a running surface and a hub bore in order to achieve a particularly uniform temperature distribution in the piston.
  • the amount of coolant taken up in the cooling channel or in the at least one bore depends on its thermal conductivity and the degree of desired temperature control.
  • the coolant has a filling level up to half the height of the cooling channel in order to achieve the desired shaker effect and thus a particularly effective heat distribution in the piston.
  • FIG. 1 shows an embodiment of a piston according to the invention, partly in section;
  • Figure 2 is a section along the line II - II in Figure 1.
  • 3 shows a section along the line III - III in Figure 2;
  • FIG. 4 shows an enlarged partial view of a bore according to FIG. 3 in section
  • Fig. 5 is an enlarged partial view of the cooling channel according to Figure 3 in section.
  • Figures 1 to 5 show an embodiment of a piston 10 according to the invention.
  • the piston 10 may be a one-piece or multi-piece piston.
  • the piston 10 can be made of an iron-based material and / or a light metal material, wherein the iron-based material is preferred.
  • FIGS. 1 to 3 show a one-part box piston 10.
  • the piston 10 has a piston head 11 with a piston crown 12 having a combustion bowl 13, a peripheral land 14 and a ring 15 for receiving piston rings (not shown). In the amount of the ring section 15, a circumferential cooling channel 23 is provided.
  • the piston 10 further includes a piston stem 16 with piston bosses 17 and hub bores 18 for receiving a piston pin (not shown).
  • the piston hubs 17 are connected via hub connections 19 with the bottom 11 a of the piston head.
  • the piston hubs 17 are connected to one another via running surfaces 21, 22 (cf., in particular, FIG.
  • the extending in the region of the ring portion 15 wall 23a of the cooling channel 23 has an inclination and closes with the piston center axis M an acute angle ⁇ of up to 10 °.
  • the inclination begins approximately in the region of the upper edge of the lowermost annular groove 15a of the annular part 15 and continues up to the upper end of the cooling channel 23.
  • the extending in the combustion bowl 13 wall 23b of the cooling channel 23 extends parallel to the contour of the wall 13a of the combustion bowl thirteenth
  • the piston shaft 16 has four holes 24a, 24b, 24c, 24d in the exemplary embodiment.
  • the bores 24a-d in the exemplary embodiment extend approximately axially and parallel to the piston center axis M.
  • the bores 24a-d may, however, also extend inclined at an angle to the piston center axis M.
  • the bores 24a-d are arranged between a running surface 21, 22 and a hub bore 18.
  • the bores 24a-d open into the cooling channel 23rd
  • the piston 10 may for example be cast in a conventional manner, wherein the cooling channel 23 and the bores 24a-d can be introduced in a conventional manner by means of a salt core. It is essential that at least one bore 24a has an opening 25 to the outside.
  • the coolant 27, namely a low-melting metal or a low-melting metal alloy, as enumerated by way of example above is filled through the opening 25 into the bore 24a. From there, the coolant 27 is distributed in the cooling channel 23 and in the further holes 24b-d.
  • the opening 25 is then sealed, in the embodiment by means of a pressed-steel ball 26.
  • the opening 25 can also be closed, for example. By welding a lid or pressing a cap (not shown).
  • the size of the holes 24a-d and the filling amount of the coolant 27 depend on the size and the material of the piston 10. On average, about. 10g to 40g coolant 27 per piston 10 required.
  • the cooling capacity can be controlled by the amount of the added coolant 27 in consideration of its thermal conductivity coefficient. For example. is a level in the cooling channel 23 suitable, which corresponds approximately to half the height of the cooling channel 23. In this case, during operation, the known shaker effect can additionally be used for a particularly effective heat distribution in the piston. For sodium as coolant 27 with a temperature in operation of 220 ° C results in a cooling capacity of 350kW / m 2, a maximum surface temperature of the piston 10 of about 260 ° C.
  • the underside 11a of the piston head 11 can be cooled by injection with cooling oil.
  • a lance is inserted through the opening 25 and purged by means of nitrogen or other suitable inert gas or by means of dry air.
  • protective gas for example nitrogen, inert gas or dry air
  • Another method for filling the bore 24a is characterized in that after flushing with nitrogen, inert gas or dry air, the bores 24a-d and the cooling channel 23 are evacuated and the coolant 27 is introduced in a vacuum.
  • the coolant 27 can move more easily in the cooling channel 23 back and forth and in the bores 24a-d in and out, since it is not hindered by existing inert gas.

Landscapes

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

Abstract

The invention relates to a piston (10,) for an internal combustion engine, comprising a piston head (11) and a piston skirt (16), said piston head (11) having a peripheral annular part (15) and in the region of said annular part (15), a peripheral cooling channel (23). The piston skirt (16) comprises piston bores (17) provided with hub bores (18), which are arranged over the hub connections (19) on the underside (11a) of the piston head (11). Said piston hubs (17) are interconnected over the running surfaces (21, 22). According to the invention, the wall (23a) of the cooling channel (23) which extends in the region of the annular part (15) comprises an inclined portion and together with the central axis of the piston (M), forms an acute angle (a). At least one bore (24a, 24b, 24c, 24d) which is closed towards the outside is arranged between a running surface (21, 22) and a hub bore (18) such that the at least one bore (24a, 24b, 24c, 24d) leads into the cooling channel (23), and that the cooling channel (23) and the at least one bore (24a, 24b, 24c, 24d) contain a coolant (27) in the form of a metal or a metal alloy which have a low-melting point.

Description

Kolben für einen Verbrennungsmotor  Piston for an internal combustion engine
Die vorliegende Erfindung betrifft einen Kolben für einen Verbrennungsmotor, mit einem Kolbenkopf und einem Kolbenschaft, wobei der Kolbenkopf eine umlaufende Ringpartie sowie im Bereich der Ringpartie einen umlaufenden Kühlkanal aufweist, wobei der Kolbenschaft mit Nabenbohrungen versehene Kolbennaben aufweist, die über Nabenanbindungen an der Unterseite des Kolbenkopfes angeordnet sind, wobei die Kolbennaben über Laufflächen miteinander verbunden sind. The present invention relates to a piston for an internal combustion engine, having a piston head and a piston skirt, wherein the piston head has a circumferential annular portion and in the region of the annular part a circumferential cooling channel, wherein the piston skirt has hub bores provided with piston bosses, which have hub connections on the underside of the piston head are arranged, wherein the piston hubs are interconnected via running surfaces.
In modernen Verbrennungsmotoren sind die Kolben im Bereich der Kolbenböden immer höheren Temperaturbelastungen ausgesetzt. Dies führt im Betrieb zu erheblichen Temperaturunterschieden zwischen dem Kolbenkopf und dem Kolbenschaft. Damit ist auch das Einbauspiel der Kolben im kalten Motor unterschiedlich zum Einbauspiel im warmen Motor. In modern internal combustion engines, the pistons in the region of the piston crowns are exposed to ever higher temperature loads. This results in operation to significant temperature differences between the piston head and the piston skirt. Thus, the installation play of the pistons in the cold engine is different to the installation play in the warm engine.
Die Aufgabe der vorliegenden Erfindung besteht darin, einen gattungsgemäßen Kolben so weiterzuentwickeln, dass sich im Betrieb eine gleichmäßigere Temperaturverteilung zwischen dem Kolbenkopf und dem Kolbenschaft einstellt. The object of the present invention is to develop a generic piston so that sets a more uniform temperature distribution between the piston head and the piston skirt during operation.
Die Lösung besteht darin, dass die im Bereich der Ringpartie verlaufende Wand des Kühlkanals eine Neigung aufweist und mit der Kolbenmittelachse einen spitzen Winkel einschließt, dass mindestens eine nach außen verschlossene Bohrung vorgesehen ist, die zwischen einer Lauffläche und einer Nabenbohrung angeordnet ist, dass die mindestens eine Bohrung in den Kühlkanal mündet, dass der Kühlkanal und die mindestens eine Bohrung ein Kühlmittel in Form eines niedrig schmelzenden Metalls oder einer niedrig schmelzenden Metalllegierung enthalten. The solution is that extending in the region of the annular part wall of the cooling channel has an inclination and with the piston central axis forms an acute angle that at least one outwardly closed bore is provided, which is arranged between a tread and a hub bore, that the at least a bore opens into the cooling channel, that the cooling channel and the at least one bore contain a coolant in the form of a low-melting metal or a low-melting metal alloy.
Der erfindungsgemäße Kolben zeichnet sich dadurch aus, dass die im Bereich des Kolbenbodens erzeugte Wärme über den Kolbenkopf in den Kolben geleitet und über die vergleichsweise großflächigen Laufflächen abgegeben wird. Damit wird im The piston according to the invention is characterized in that the heat generated in the region of the piston crown is guided via the piston head into the piston and discharged via the comparatively large-area running surfaces. This will be in the
Bestätigungskopie| Betrieb eine gleichmäßigere Wärmeverteilung über den gesamten Kolben erreicht. Ferner wird eine effektivere Kühlung des gesamten Kolbens erzielt. Confirmation copy | Operation achieved a more even heat distribution over the entire piston. Furthermore, a more effective cooling of the entire piston is achieved.
Die erfindungsgemäß vorgesehene Neigung der im Bereich der Ringpartie verlaufenden Wand des Kühlkanals bewirkt, dass das Kühlmittel im Motorbetrieb bei seiner Abwärtsbewegung diesen Bereich weitgehend nicht und bei der Aufwärtsbewegung nur in einem geringen Ausmaß berührt. Das Kühlmittel wird sich vielmehr im The inventively provided inclination of running in the region of the ring wall wall of the cooling channel causes the coolant during engine operation during its downward movement this area largely not touched and in the upward movement only to a small extent. The coolant will be more in the
Wesentlichen linear nach oben bzw. unten bewegen. Die erfindungsgemäß vorgesehene Neigung bildet also zwischen dem im Motorbetrieb bewegten Kühlmittel und der im Bereich der Ringpartie verlaufenden Wand des Kühlkanals einen toten Winkel, so dass das sich bewegende Kühlmittel mit den im toten Winkel liegenden Wandbereich keinen oder nur wenig Kontakt hat. Dadurch werden eine Überhitzung der Ringpartie und die damit einhergehende Gefahr der Ölkohlebildung im Bereich der Ringnuten und Ringstege vermieden. Move linearly up or down. Thus, according to the invention, the inclination forms a blind spot between the coolant moving during engine operation and the wall of the cooling channel extending in the region of the annular part, so that the moving coolant has no or only little contact with the wall region lying in the blind spot. As a result, overheating of the ring and the associated risk of carbon formation in the ring grooves and ring lands are avoided.
Wenn zusätzlich die Unterseite des Kolbenkopfes mit Kühlöl gekühlt wird, wird die Bildung von Ölkohle vermieden. Insgesamt ist außerdem der Kühlölverbrauch reduziert. In addition, if the bottom of the piston head is cooled with cooling oil, the formation of oil carbon is avoided. Overall, the cooling oil consumption is also reduced.
Durch die zusätzliche Erwärmung des Bereiches zwischen Kolbennabe und Kolbenschaft wird eine zusätzliche thermische Ausdehnung des Kolbenschafts bewirkt und dadurch das Warmspiel zwischen Kolben und Zylinder reduziert. Dies ist insbesondere dann von Vorteil, wenn ein Kurbelgehäuse aus einem Leichtmetallwerkstoff, bspw. einem aluminiumbasierten Werkstoff, mit einem höheren Wärmeausdehnungskoeffizienten als dem des Kolbenwerkstoffs verwendet wird. The additional heating of the area between the piston hub and the piston shaft causes an additional thermal expansion of the piston shaft and thereby reduces the warm play between piston and cylinder. This is particularly advantageous when a crankcase made of a light metal material, for example. An aluminum-based material, with a higher coefficient of thermal expansion than that of the piston material is used.
Vorteilhafte Weiterbildungen ergeben sich aus den Unteransprüchen. Advantageous developments emerge from the subclaims.
Der Winkel, den die im Bereich der Ringpartie verlaufende Wand des Kühlkanals mit der Kolbenmittelachse einschließt, beträgt vorzugsweise nicht mehr als 10°, um eine übermäßige Verengung des Kühlkanals und eine damit einhergehende Reduzierung der Kühlleistung zu vermeiden. Aus demselben Grund beginnt die Neigung dieser Wand vorzugsweise in Höhe der Oberkante der untersten Ringnut der Ringpartie. Wenn eine Verbrennungsmulde vorgesehen ist, ist es von Vorteil, wenn die im The angle enclosed by the wall of the cooling passage extending in the region of the annular part with the piston center axis is preferably not more than 10 ° in order to avoid an excessive narrowing of the cooling passage and a concomitant reduction of the cooling power. For the same reason, the inclination of this wall preferably begins at the level of the upper edge of the lowest annular groove of the ring part. If a combustion bowl is provided, it is advantageous if the in the
Bereich der Verbrennungsmulde verlaufende Wand des Kühlkanals zur Kontur der Wand der Verbrennungsmulde parallel verläuft, um den Wärmeübergang zwischen der Verbrennungsmulde und dem im Kühlkanal aufgenommenen Kühlmittel zu optimieren. Runs the region of the combustion bowl extending wall of the cooling channel to the contour of the wall of the combustion bowl parallel to optimize the heat transfer between the combustion bowl and the coolant received in the cooling channel.
Niedrig schmelzende Metalle, die zur Verwendung als Kühlmittel geeignet sind, sind insbesondere Natrium oder Kalium. Als niedrig schmelzende Metalllegierungen können insbesondere Galinstan®-Legierungen, niedrig schmelzende Bismut-Legierungen und Natrium-Kalium-Legierungen eingesetzt werden. Low melting metals suitable for use as refrigerants are especially sodium or potassium. As low-melting metal alloys in particular Galinstan® alloys, low melting bismuth alloys and sodium-potassium alloys can be used.
Als sog. GalinstanO-Legierungen werden Legierungssysteme aus Gallium, Indium und Zinn bezeichnet, die bei Raumtemperatur flüssig sind. Diese Legierungen bestehen aus 65 Gew.-% bis 95 Gew.-% Gallium, 5 Gew.-% bis 26 Gew.-% Indium und 0 Gew.-% bis 16 Gew.-% Zinn. Bevorzugte Legierungen sind bspw. solche mit 68 Gew.-% bis 69 Gew.-% Gallium, 21 Gew.-% bis 22 Gew.-% Indium und 9,5 Gew.-% bis 10,5 Gew.-% Zinn (Schmp. -19°C), 62 Gew.-% Gallium, 22 Gew.-% Indium und 16 Gew.-% Zinn (Schmp.10,7°C) sowie 59,6 Gew.-% Gallium, 26 Gew.-% Indium und 14,4 Gew.%- Zinn (ternäres Eutektikum, Schmp. 11°C). GalinstanO alloys are gallium, indium and tin alloy systems that are liquid at room temperature. These alloys consist of 65 wt% to 95 wt% gallium, 5 wt% to 26 wt% indium and 0 wt% to 16 wt% tin. Preferred alloys are, for example, those with 68% by weight to 69% by weight of gallium, 21% by weight to 22% by weight of indium and 9.5% by weight to 10.5% by weight of tin ( Mp -19 ° C), 62% by weight of gallium, 22% by weight of indium and 16% by weight of tin (mp 10.7 ° C.) and 59.6% by weight of gallium, 26% by weight. % Indium and 14.4% by weight tin (ternary eutectic, mp 11 ° C).
Niedrig schmelzende Bismut-Legierungen sind zahlreich bekannt. Dazu gehören bspw. LBE (eutektische Bismut-Blei-Legierung, Schmp. 124°C), Roses Metall (50 Gew.-% Bismut, 28 Gew.-% Blei und 22 Gew.-% Zinn, Schmp. 98°C), Orionmetall (42 Gew.-% Bismut, 42 Gew.-% Blei und 16 Gew.-% Zinn, Schmp. 108°C); Schnelllot (52 Gew.-% Bismut, 32 Gew.-% Blei und 16 Gew.-% Zinn, Schmp. 96°C), d'Arcets- Metall (50 Gew.-% Bismut, 25 Gew.-% Blei und 25 Gew.-% Zinn), Woodsches Metall (50 Gew.-% Bismut, 25 Gew.-% Blei, 12,5 Gew.-% Zinn und 12,5 Gew.-% Cadmium, Schmp. 71 °C), Lipowitzmetall (50 Gew.-% Bismut, 27 Gew.-% Blei, 13 Gew.-% Zinn und 10 Gew.-% Cadmium, Schmp. 70°C), Harpers Metall (44 Gew.-% Bismut, 25 Gew.-% Blei, 25 Gew.-% Zinn und 6 Gew.-% Cadmium, Schmp. 75°C), Cerrolow 117 (44,7 Gew.-% Bismut, 22,6 Gew.-% Blei, 19,1 Gew.-% Indium, 8,3 Gew.-% Zinn und 5,3 Gew.-% Cadmium, Schmp. 47°C); Cerrolow 174 (57 Gew.-% Bismut, 26 Gew.-% Indium, 17 Gew.-% Zinn, Schmp. 78,9°C), Fields Metall (32 Gew.-% Bismut, 51 Gew.-% Indium, 17 Gew.-% Zinn, Schmp. 62°C) sowie die Walkerlegierung (45 Gew.-% Bismut, 28 Gew.-% Blei, 22 Gew.-% Zinn und 5 Gew.-% Antimon). Low melting bismuth alloys are well known. These include, for example, LBE (eutectic bismuth-lead alloy, mp. 124 ° C), Roses metal (50 wt .-% bismuth, 28 wt .-% lead and 22 wt .-% tin, mp. 98 ° C) Orion metal (42 wt% bismuth, 42 wt% lead and 16 wt% tin, mp 108 ° C); Quick solder (52 weight percent bismuth, 32 weight percent lead and 16 weight percent tin, mp 96 ° C), d'Arcets metal (50 weight percent bismuth, 25 weight percent lead and 25 wt% tin), Wood's metal (50 wt% bismuth, 25 wt% lead, 12.5 wt% tin and 12.5 wt% cadmium, mp 71 ° C), Lipowitz metal (50 wt% bismuth, 27 wt% lead, 13 wt% tin and 10 wt% cadmium, mp 70 ° C), Harper's metal (44 wt% bismuth, 25 wt%). -% lead, 25 wt .-% tin and 6 wt .-% cadmium, mp. 75 ° C), Cerrolow 117 (44.7 wt .-% bismuth, 22.6 wt .-% lead, 19.1 wt Indium, 8.3 wt% tin, and 5.3 wt% cadmium, mp 47 ° C); Cerrolow 174 (57 wt% bismuth, 26 wt% indium, 17 wt% tin, mp 78.9 ° C), Fields metal (32 wt% bismuth, 51 Wt .-% indium, 17 wt .-% tin, mp 62 ° C) and the Walker alloy (45 wt .-% bismuth, 28 wt .-% lead, 22 wt .-% tin and 5 wt .-% antimony ).
Geeignete Natrium-Kalium-Legierungen können 40 Gew.-% bis 90 Gew.-% Kalium enthalten. Besonders geeignet ist die eutektische Legierung NaK mit 78 Gew.-% Kalium und 22 Gew.-% Natrium (Schmp. -12,6°C). Suitable sodium-potassium alloys may contain from 40% to 90% by weight of potassium. Particularly suitable is the eutectic alloy NaK with 78 wt .-% potassium and 22 wt .-% sodium (mp. -12.6 ° C).
Das Kühlmittel kann zusätzlich Lithium und/oder Lithiumnitrid enthalten. Falls beim Befüllen Stickstoff als Schutzgas verwendet wird, kann dieses mit dem Lithium zu Lithiumnitrid abreagieren und auf diese Weise aus dem Kühlkanal entfernt werden. The coolant may additionally contain lithium and / or lithium nitride. If nitrogen is used as a protective gas during filling, this can react with the lithium to lithium nitride and be removed in this way from the cooling channel.
Das Kühlmittel kann ferner Natriumoxide und/oder Kaliumoxide enthalten, falls während des Befüllens ggf. vorhandene trockene Luft mit dem Kühlmittel reagiert hat. The coolant may further contain sodium oxides and / or potassium oxides if, during filling, any existing dry air has reacted with the coolant.
Vorzugsweise sind vier Bohrungen vorgesehen, die zwischen einer Lauffläche und einer Nabenbohrung angeordnet sind, um eine besonders gleichmäßige Temperaturverteilung im Kolben zu erreichen. Preferably, four holes are provided, which are arranged between a running surface and a hub bore in order to achieve a particularly uniform temperature distribution in the piston.
Die Menge des im Kühlkanal bzw. in der mindestens einen Bohrung aufgenommenen Kühlmittels hängt von seiner Wärmeleitfähigkeit und dem Grad der gewünschten Temperatursteuerung ab. Vorzugsweise weist das Kühlmittel eine Füllhöhe bis zur halben Höhe des Kühlkanals auf, um den erwünschten Shaker-Effekt und damit eine besonders wirksame Wärmeverteilung im Kolben zu erzielen. The amount of coolant taken up in the cooling channel or in the at least one bore depends on its thermal conductivity and the degree of desired temperature control. Preferably, the coolant has a filling level up to half the height of the cooling channel in order to achieve the desired shaker effect and thus a particularly effective heat distribution in the piston.
Insbesondere wenn der Anteil der Verbrennungswärme, welcher während des Motorbetriebs in den Kolben abfließt, begrenzt werden soll, kann dies mit der Menge an eingefülltem Kühlmittel gesteuert werden. Es hat sich gezeigt, dass mitunter bereits eine Füllung von 3% bis 10% des Kühlkanalvolumens mit dem Kühlmittel ausreicht, um die Funktion des Kolbens sicherzustellen. In particular, if the proportion of the heat of combustion, which flows into the piston during engine operation, should be limited, this can be controlled by the amount of coolant introduced. It has been found that sometimes even a filling of 3% to 10% of the cooling channel volume with the coolant is sufficient to ensure the function of the piston.
Ein Ausführungsbeispiel der vorliegenden Erfindung wird im Folgenden anhand der beigefügten Zeichnungen näher erläutert. Es zeigen in einer schematischen, nicht maßstabsgetreuen Darstellung: Fig. 1 ein Ausführungsbeispiel eines erfindungsgemäßen Kolbens, teilweise im Schnitt; An embodiment of the present invention will be explained in more detail below with reference to the accompanying drawings. In a schematic, not to scale representation: Fig. 1 shows an embodiment of a piston according to the invention, partly in section;
Fig. 2 einen Schnitt entlang der Linie II - II in Figur 1; Fig. 3 einen Schnitt entlang der Linie III - III in Figur 2; Figure 2 is a section along the line II - II in Figure 1. 3 shows a section along the line III - III in Figure 2;
Fig. 4 eine vergrößerte Teildarstellung einer Bohrung gemäß Figur 3 im Schnitt; 4 shows an enlarged partial view of a bore according to FIG. 3 in section;
Fig. 5 eine vergrößerte Teildarstellung des Kühlkanals gemäß Figur 3 im Schnitt. Fig. 5 is an enlarged partial view of the cooling channel according to Figure 3 in section.
Die Figuren 1 bis 5 zeigen ein Ausführungsbeispiel eines erfindungsgemäßen Kolbens 10. Der Kolben 10 kann ein einteiliger oder mehrteiliger Kolben sein. Der Kolben 10 kann aus einem eisen basierten Werkstoff und/oder einem Leichtmetallwerkstoff hergestellt sein, wobei der eisenbasierte Werkstoff bevorzugt ist. Figures 1 to 5 show an embodiment of a piston 10 according to the invention. The piston 10 may be a one-piece or multi-piece piston. The piston 10 can be made of an iron-based material and / or a light metal material, wherein the iron-based material is preferred.
Die Figuren 1 bis 3 zeigen beispielhaft einen einteiligen Kastenkolben 10. Der Kolben 10 weist einen Kolbenkopf 11 mit einem eine Verbrennungsmulde 13 aufweisenden Kolbenboden 12, einem umlaufenden Feuersteg 14 und einer Ringpartie 15 zur Aufnahme von Kolbenringen (nicht dargestellt) auf. In Höhe der Ringpartie 15 ist ein umlaufender Kühlkanal 23 vorgesehen. Der Kolben 10 weist ferner einen Kolbenschaft 16 mit Kolbennaben 17 und Nabenbohrungen 18 zur Aufnahme eines Kolbenbolzens (nicht dargestellt) auf. Die Kolbennaben 17 sind über Nabenanbindungen 19 mit der Unterseite 11a des Kolbenkopfes verbunden. Die Kolbennaben 17 sind über Laufflächen 21 , 22 miteinander verbunden (vgl. insbesondere Figur 2). By way of example, FIGS. 1 to 3 show a one-part box piston 10. The piston 10 has a piston head 11 with a piston crown 12 having a combustion bowl 13, a peripheral land 14 and a ring 15 for receiving piston rings (not shown). In the amount of the ring section 15, a circumferential cooling channel 23 is provided. The piston 10 further includes a piston stem 16 with piston bosses 17 and hub bores 18 for receiving a piston pin (not shown). The piston hubs 17 are connected via hub connections 19 with the bottom 11 a of the piston head. The piston hubs 17 are connected to one another via running surfaces 21, 22 (cf., in particular, FIG.
Die im Bereich der Ringpartie 15 verlaufende Wand 23a des Kühlkanals 23 weist eine Neigung auf und schließt mit der Kolbenmittelachse M einen spitzen Winkel α von bis zu 10° ein. Die Neigung beginnt etwa im Bereich der Oberkante der untersten Ringnut 15a der Ringpartie 15 und setzt bis zum oberen Ende des Kühlkanals 23 fort. Die im Bereich der Verbrennungsmulde 13 verlaufende Wand 23b des Kühlkanals 23 verläuft parallel zur Kontur der Wand 13a der Verbrennungsmulde 13. Der Kolbenschaft 16 weist im Ausführungsbeispiel vier Bohrungen 24a, 24b, 24c, 24d auf. Die Bohrungen 24a-d verlaufen im Ausführungsbeispiel in etwa axial und parallel zur Kolbenmittelachse M. Die Bohrungen 24a-d können aber auch geneigt unter einem Winkel zur Kolbenmittelachse M verlaufen. Die Bohrungen 24a-d sind zwischen einer Lauffläche 21 , 22 und einer Nabenbohrung 18 angeordnet. Die Bohrungen 24a-d münden in den Kühlkanal 23. The extending in the region of the ring portion 15 wall 23a of the cooling channel 23 has an inclination and closes with the piston center axis M an acute angle α of up to 10 °. The inclination begins approximately in the region of the upper edge of the lowermost annular groove 15a of the annular part 15 and continues up to the upper end of the cooling channel 23. The extending in the combustion bowl 13 wall 23b of the cooling channel 23 extends parallel to the contour of the wall 13a of the combustion bowl thirteenth The piston shaft 16 has four holes 24a, 24b, 24c, 24d in the exemplary embodiment. The bores 24a-d in the exemplary embodiment extend approximately axially and parallel to the piston center axis M. The bores 24a-d may, however, also extend inclined at an angle to the piston center axis M. The bores 24a-d are arranged between a running surface 21, 22 and a hub bore 18. The bores 24a-d open into the cooling channel 23rd
Im Ausführungsbeispiel kann der Kolbens 10 bspw. in an sich bekannter Weise gegossen sein, wobei der Kühlkanal 23 und die Bohrungen 24a-d in an sich bekannter Weise mittels eines Salzkerns eingebracht werden können. Wesentlich ist, dass zumindest eine Bohrung 24a eine Öffnung 25 nach außen aufweist. Erfindungsgemäß wird das Kühlmittel 27, nämlich ein niedrig schmelzendes Metall oder eine niedrig schmelzende Metalllegierung, wie sie weiter oben beispielhaft aufgezählt sind, durch die Öffnung 25 in die Bohrung 24a gefüllt. Von dort aus verteilt sich das Kühlmittel 27 im Kühlkanal 23 sowie in den weiteren Bohrungen 24b-d. Die Öffnung 25 wird anschließend dicht verschlossen, im Ausführungsbeispiel mittels einer ein- gepressten Stahlkugel 26. Die Öffnung 25 kann auch bspw. durch Aufschweißen eines Deckels oder Einpressen einer Kappe verschlossen werden (nicht dargestellt). In the exemplary embodiment, the piston 10 may for example be cast in a conventional manner, wherein the cooling channel 23 and the bores 24a-d can be introduced in a conventional manner by means of a salt core. It is essential that at least one bore 24a has an opening 25 to the outside. According to the invention, the coolant 27, namely a low-melting metal or a low-melting metal alloy, as enumerated by way of example above, is filled through the opening 25 into the bore 24a. From there, the coolant 27 is distributed in the cooling channel 23 and in the further holes 24b-d. The opening 25 is then sealed, in the embodiment by means of a pressed-steel ball 26. The opening 25 can also be closed, for example. By welding a lid or pressing a cap (not shown).
Die Größe der Bohrungen 24a-d und die Füllmenge des Kühlmittels 27 richten sich nach der Größe und dem Werkstoff des Kolbens 10. Durchschnittlich werden etwa. 10g bis 40g Kühlmittel 27 pro Kolben 10 benötigt. Die Kühlleistung kann über die Menge des zugegebenen Kühlmittels 27 unter Berücksichtigung seines Wärmeleitfähigkeitskoeffizienten gesteuert werden. Bspw. ist ein Füllstand im Kühlkanal 23 geeignet, der in etwa der halben Höhe des Kühlkanals 23 entspricht. In diesem Fall kann im Betrieb der an sich bekannte Shaker-Effekt für eine besonders wirksame Wärmeverteilung im Kolben zusätzlich genutzt werden. Für Natrium als Kühlmittel 27 mit einer Temperatur im Betrieb von 220°C ergibt sich bei einer Kühlleistung von 350kW/m2 eine maximale Oberflächentemperatur des Kolbens 10 von etwa 260°C. The size of the holes 24a-d and the filling amount of the coolant 27 depend on the size and the material of the piston 10. On average, about. 10g to 40g coolant 27 per piston 10 required. The cooling capacity can be controlled by the amount of the added coolant 27 in consideration of its thermal conductivity coefficient. For example. is a level in the cooling channel 23 suitable, which corresponds approximately to half the height of the cooling channel 23. In this case, during operation, the known shaker effect can additionally be used for a particularly effective heat distribution in the piston. For sodium as coolant 27 with a temperature in operation of 220 ° C results in a cooling capacity of 350kW / m 2, a maximum surface temperature of the piston 10 of about 260 ° C.
Zusätzlich kann die Unterseite 11a des Kolbenkopfes 11 durch Anspritzen mit Kühlöl gekühlt werden. Zum Befüllen der Bohrung 24a wird durch die Öffnung 25 eine Lanze eingeführt und mittels Stickstoff oder mittels eines anderen geeigneten Inertgases oder mittels trockener Luft gespült. Zur Einführung des Kühlmittels 27 wird dieses unter Schutzgas (bspw. Stickstoff, Inertgas oder trockene Luft) durch die Öffnung 25 geleitet, so dass das Kühlmittel 27 in die Bohrung 24a bzw. den Kühlkanal 23 aufgenommen wird. In addition, the underside 11a of the piston head 11 can be cooled by injection with cooling oil. To fill the bore 24a, a lance is inserted through the opening 25 and purged by means of nitrogen or other suitable inert gas or by means of dry air. To introduce the coolant 27, it is passed through the opening 25 under protective gas (for example nitrogen, inert gas or dry air), so that the coolant 27 is received in the bore 24a or the cooling channel 23.
Ein weiteres Verfahren zum Befüllen der Bohrung 24a zeichnet sich dadurch aus, dass nach dem Spülen mit Stickstoff, Inertgas oder trockener Luft die Bohrungen 24a-d und der Kühlkanal 23 evakuiert werden und das Kühlmittel 27 im Vakuum eingebracht wird. Damit kann sich das Kühlmittel 27 leichter im Kühlkanal 23 hin und her und in den Bohrungen 24a-d hinein und hinaus bewegen, da es nicht durch vorhandenes Schutzgas behindert wird. Another method for filling the bore 24a is characterized in that after flushing with nitrogen, inert gas or dry air, the bores 24a-d and the cooling channel 23 are evacuated and the coolant 27 is introduced in a vacuum. Thus, the coolant 27 can move more easily in the cooling channel 23 back and forth and in the bores 24a-d in and out, since it is not hindered by existing inert gas.
Eine andere Möglichkeit, das Schutzgas aus dem Kühlkanal 23 bzw. den Bohrungen 24a-d zu entfernen, besteht darin, dass Stickstoff oder trockene Luft (d.h. im Another way to remove the protective gas from the cooling channel 23 or the bores 24a-d is that nitrogen or dry air (i.e.
Wesentlichen eine Mischung aus Stickstoff und Sauerstoff) als Schutzgas zu verwenden und dem Kühlmittel 27 eine kleine Menge Lithium zuzusetzen, erfahrungsgemäß etwa 1 ,8mg bis 2,0mg Lithium pro Kubikzentimeter Gasraum (d.h. Volumen des Kühlkanal 23 plus Volumen der Bohrungen 24a-d). Während bspw. Natrium und Kalium mit Sauerstoff zu Oxiden reagieren, reagiert das Lithium mit Stickstoff zu Lithiumnitrid. Das Schutzgas wird somit praktisch vollständig als Feststoff im Kühlmittel 27 gebunden. Essentially a mixture of nitrogen and oxygen) as a shielding gas and adding a small amount of lithium to the coolant 27 has been found to contain about 1.8mg to 2.0mg of lithium per cubic centimeter of gas space (i.e., volume of cooling channel 23 plus volume of bores 24a-d). While, for example, sodium and potassium react with oxygen to form oxides, the lithium reacts with nitrogen to form lithium nitride. The protective gas is thus almost completely bound as a solid in the coolant 27.

Claims

Patentansprüche claims
1. Kolben (10) für einen Verbrennungsmotor, mit einem Kolbenkopf (11) und 1. piston (10) for an internal combustion engine, with a piston head (11) and
einem Kolbenschaft (16), wobei der Kolbenkopf (11) eine umlaufende Ringpartie (15) sowie im Bereich der Ringpartie (15) einen umlaufenden Kühlkanal (23) aufweist, wobei der Kolbenschaft (16) mit Nabenbohrungen (18) versehene Kolbennaben (17) aufweist, die über Nabenanbindungen (19) an der Unterseite (11a) des Kolbenkopfes (11) angeordnet sind, wobei die Kolbennaben (17) über Laufflächen (21, 22) miteinander verbunden sind, dadurch gekennzeichnet, dass die im Bereich der Ringpartie (15) verlaufende Wand (23a) des Kühlkanals (23) eine Neigung aufweist und mit der Kolbenmittelachse (M) einen spitzen Winkel (a) einschließt, dass mindestens eine nach außen verschlossene Bohrung (24a, 24b, 24c, 24d) vorgesehen ist, die zwischen einer Lauffläche (21, 22) und einer Nabenbohrung (18) angeordnet ist, dass die mindestens eine Bohrung (24a, 24b, 24c, 24d) in den Kühlkanal (23) mündet, und dass der Kühlkanal (23) und die mindestens eine Bohrung (24a, 24b, 24c, 24d) ein Kühlmittel (27) in Form eines niedrig schmelzenden Metalls oder einer niedrig schmelzenden Metalllegierung enthalten.  a piston shaft (16), wherein the piston head (11) has a circumferential annular portion (15) and in the region of the annular portion (15) a circumferential cooling channel (23), wherein the piston shaft (16) with hub bores (18) provided with piston hubs (17) which are arranged via hub connections (19) on the underside (11a) of the piston head (11), wherein the piston hubs (17) are connected to one another via running surfaces (21, 22), characterized in that in the region of the ring portion (15 ) extending wall (23a) of the cooling channel (23) has an inclination and with the piston central axis (M) forms an acute angle (a) that at least one outwardly closed bore (24a, 24b, 24c, 24d) is provided, the between a running surface (21, 22) and a hub bore (18) is arranged, that the at least one bore (24a, 24b, 24c, 24d) opens into the cooling channel (23), and that the cooling channel (23) and the at least one bore (24a, 24b, 24c, 24d) a coolant (27) i n form of a low-melting point metal or a low-melting point metal alloy.
2. Kolben nach Anspruch 1 , dadurch gekennzeichnet, dass der Winkel (a) maximal 10° beträgt. 2. Piston according to claim 1, characterized in that the angle (a) is a maximum of 10 °.
3. Kolben nach Anspruch 1 , dadurch gekennzeichnet, dass die Neigung der Wand (23a) in Höhe der der Oberkante der untersten Ringnut (15a) der Ringpartie (15) beginnt. 3. Piston according to claim 1, characterized in that the inclination of the wall (23 a) in height of the upper edge of the lowermost annular groove (15 a) of the ring portion (15) begins.
4. Kolben nach Anspruch 1, dadurch gekennzeichnet, dass im Kolbenkopf (11) eine Verbrennungsmulde (13) vorgesehen ist und dass die im Bereich der Verbrennungsmulde (13) verlaufende Wand (23b) des Kühlkanals (23) zur Kontur der Wand (13a) Verbrennungsmulde (13) parallel verläuft. 4. Piston according to claim 1, characterized in that in the piston head (11) a combustion bowl (13) is provided and that in the region of the combustion bowl (13) extending wall (23b) of the cooling channel (23) to the contour of the wall (13a) Combustion body (13) runs parallel.
5. Kolben nach Anspruch 1 , dadurch gekennzeichnet, dass als niedrig schmelzendes Metall Natrium oder Kalium enthalten ist. 5. Piston according to claim 1, characterized in that is contained as low-melting metal sodium or potassium.
6. Kolben nach Anspruchl , dadurch gekennzeichnet, dass die niedrig schmelzende Metalllegierung aus der Gruppe umfassend Galinstan®-Legierungen, niedrig schmelzende Bismut-Legierungen und Natrium-Kalium-Legierungen ausgewählt ist. 6. Piston according Anspruchl, characterized in that the low-melting metal alloy from the group comprising Galinstan® alloys, low melting bismuth alloys and sodium-potassium alloys is selected.
7. Kolben nach Anspruch 1 , dadurch gekennzeichnet, dass das Kühlmittel (27) Lithium und/oder Lithiumnitrid enthält. 7. Piston according to claim 1, characterized in that the coolant (27) contains lithium and / or lithium nitride.
8. Kolben nach Anspruch 1 , dadurch gekennzeichnet, dass das Kühlmittel (27) Natriumoxide und/oder Kaliumoxide enthält. 8. Piston according to claim 1, characterized in that the coolant (27) contains sodium oxides and / or potassium oxides.
9. Kolben nach Anspruch 1 , dadurch gekennzeichnet, dass vier Bohrungen (24a, 24b, 24c, 24d) vorgesehen sind, die zwischen einer Lauffläche (21 , 22) und einer Nabenbohrung (18) angeordnet sind. 9. Piston according to claim 1, characterized in that four bores (24a, 24b, 24c, 24d) are provided, which are arranged between a running surface (21, 22) and a hub bore (18).
10. Kolben nach Anspruch 1 , dadurch gekennzeichnet, dass das Kühlmittel (27) eine Füllhöhe bis zur halben Höhe des Kühlkanals (23) aufweist. 10. Piston according to claim 1, characterized in that the coolant (27) has a filling level up to half the height of the cooling channel (23).
11. Kolben nach Anspruch 1 , dadurch gekennzeichnet, dass das Kühlmittel (27) eine Füllmenge von 3% bis 10% des Volumens des Kühlkanals (23) aufweist. 11. Piston according to claim 1, characterized in that the coolant (27) has a capacity of 3% to 10% of the volume of the cooling channel (23).
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WO2013167103A2 (en) 2013-11-14
KR20150006860A (en) 2015-01-19
CN104379917A (en) 2015-02-25
US20150128892A1 (en) 2015-05-14
US9494106B2 (en) 2016-11-15
JP2015516050A (en) 2015-06-04
WO2013167103A3 (en) 2014-02-13
CN104379917B (en) 2017-07-14
BR112014027523A2 (en) 2017-06-27
JP6293121B2 (en) 2018-03-14
EP2864618B1 (en) 2017-01-04
DE102012008945A1 (en) 2013-11-07

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