EP1864003A1 - Gas shuttle valve provided with an anti-corrosive layer - Google Patents

Gas shuttle valve provided with an anti-corrosive layer

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Publication number
EP1864003A1
EP1864003A1 EP06707539A EP06707539A EP1864003A1 EP 1864003 A1 EP1864003 A1 EP 1864003A1 EP 06707539 A EP06707539 A EP 06707539A EP 06707539 A EP06707539 A EP 06707539A EP 1864003 A1 EP1864003 A1 EP 1864003A1
Authority
EP
European Patent Office
Prior art keywords
valve
layer
nitriding
gas exchange
nitride
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Withdrawn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
EP06707539A
Other languages
German (de)
French (fr)
Inventor
Anja LÜPFERT
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.)
MAN Energy Solutions SE
Original Assignee
MAN B&W Diesel GmbH
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Filing date
Publication date
Application filed by MAN B&W Diesel GmbH filed Critical MAN B&W Diesel GmbH
Publication of EP1864003A1 publication Critical patent/EP1864003A1/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/32—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for rotating lift valves, e.g. to diminish wear
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/28—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in one step
    • C23C8/30—Carbo-nitriding
    • C23C8/32—Carbo-nitriding of ferrous surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/02—Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials
    • F01L3/04—Coated valve members or valve-seats
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/06—Valve members or valve-seats with means for guiding or deflecting the medium controlled thereby, e.g. producing a rotary motion of the drawn-in cylinder charge
    • 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

Definitions

  • the invention relates to a gas exchange valve of an internal combustion engine with a valve cone substantially from a valve stem, which merges into a valve plate to form a groove.
  • valve element on the sealing surface is armored with a particularly resistant CrNi alloy.
  • the other parts of the gas exchange valve are subject to different requirements in terms of warm, long-term and corrosion resistance.
  • different requirements with respect to the thermal, fatigue and corrosion resistance at the various temperature zones of the valve cone are taken into account by the fact that the valve disk is made of a high-temperature and erosion-resistant material, while the valve stem together with the propeller of a material with low notch sensitivity and high fatigue strength that is, has sufficient toughness to meet the bending stresses occurring in this area.
  • a material of a typical valve steel or of a superalloy, such as NiCr2OTiAI and for the valve stem with propeller a material from a typical valve steel, such as X45CrSi9-3 used.
  • steels made of a nickel-based alloy are very expensive in order to avoid the corrosion load, so that largely where tolerable the gas exchange valve is just made of the typical valve steel, such as X45CrSi9-3.
  • valve stem and groove are attacked by wet corrosion (condensation) due to dew point of the combustion gases during engine standstill.
  • plasma nitriding / plasma nitrocarburizing is understood to mean hardening of surface layers of steels in which nitrogen or carbon atoms diffuse in and thereby react with iron in a thin surface layer to form nitrides or carbonitrides, the bonding layer (VS).
  • the nitrogen is only partially precipitated as a nitride during cooling and then causes the increase in hardness.
  • the hardness itself depends on the type of nitrides.
  • nitriding times and layers differ. In other words, there is a diffusion saturation of the surface layer of a material with nitrogen to increase hardness, wear resistance, fatigue strength or corrosion resistance.
  • the surface layer after nitriding / nitrocarburizing consists of an outer nitride or carbonitride layer (bonding layer) and a subsequent layer of nitrogen-enriched mixed crystals and precipitated nitrides (diffusion layer).
  • the nitriding times can be shortened (plasma nitriding at 450 ° C to 55O 0 C).
  • nitrocarburizing in which the treating agent in addition to nitrogen containing and carbon-donating components (plasma nitrocarburizing at 500 0 C to 59 ° C 1 0 preferably at about 520 ° C) may be in powder, salt bath, gas or plasma is just nitrocarburized.
  • valve body of the gas exchange valve is made in one piece and armored as described above, the valve plate to the sealing surface or the seating area, so in a preferred manner, the nitride or carbonitride completely on the valve stem and the groove provided to the armored sealing surface.
  • the gas exchange valve in particular an exhaust valve (1) for an internal combustion engine, has a rotary device in the form of a propeller (3) arranged on its valve stem (2).
  • the valve disk (4) is chamfered on its sealing surface (5).
  • the blades (6) of the propeller (3) are milled out of the rotary shape of the propeller.
  • valve disk (4) is made of a high-temperature and erosion-resistant material, while the valve stem (2) together with the propeller (3) consists of a material with low notch sensitivity and high fatigue strength, ie has sufficient toughness to meet the bending stresses occurring in this area.
  • a material of a typical valve steel or of a superalloy such as, for example, is used.
  • the valve disk (4) is connected to the valve stem (2) by friction welding (7).
  • the valve cone is provided with a corrosion protection layer in the form of a nitriding layer (8), whereby the corrosion protection layer is obtained by reacting the nitride-forming base alloy by plasma nitriding or plasma nitrocarburizing in a nitrogen or nitrogen-carbon atmosphere is generated.
  • the complete valve stem (2) is provided with the nitriding layer (8) until friction welding (7), at which the hot-work steel material is limited, the region of the groove (11) remains open.
  • the two end faces on the valve plate (4) and on the valve stem (2) remain recessed with respect to the nitride or carbonitride layer (8).
  • the complete valve plug (1) except for the armored valve seat portion (5) of the valve disc (4) and to the plate bottom and the valve stem end face with the nitriding layer (8) may be provided.
  • the surface is converted in such a way that a hard, wear-resistant edge layer is formed.
  • the valve plug blank is processed either partially in the form of the valve stem or complete with valve stem (2) and valve disc (4) through all manufacturing steps, so that it is present in its final surface roughness, followed by plasma nitriding or Plasmanitrocarburieren.
  • plasma nitriding or Plasmanitrocarburieren Aftertreatment of the nitrided gas exchange valve is possible but not necessary (however, the aftertreatment in the areas of the gas exchange valve to be protected from corrosion should not be carried out in order not to remove the connection layer produced).
  • the valve plug (1) can be ground after nitriding.
  • the nitriding layer has a diffusion layer (9) with a thickness (nitriding hardening depth) of 0.1 mm to 0.3 mm and a connecting layer (10) constructed thereon of 3 ⁇ m to 15 ⁇ m as characteristic of the anticorrosion layers produced and has a surface hardness greater than 750 HV (Vickers).
  • plasma nitrocarburization with the addition of carbon is preferable.
  • plasma nitriding or plasmanitrocarburizing the valve plug (1) a significantly improved corrosion protection and an increase in the fatigue strength is achieved, ie longer maintenance intervals or component life are achieved and counteracted cracking by bending stress.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Lift Valve (AREA)

Abstract

The invention relates to a gas shuttle valve for an internal combustion engine comprising a valve cone which substantially consists of a valve shaft projected in a valve disc in such a way that a hollow cone is formed. The valve cone or at least the shaft thereof is made of a typical valve steel consisting of a nitride forming base alloy up to the hollow cone area. The aim of said invention is to improve said gas shuttle valve in such a way that even the parts made of the typical valve steel exhibit a good anti-corrosive protection. For this purpose, the valve cone is provided at least partial area with an anti-corrosive layer in the form of a nitride layer, which is produced by the nitride forming base alloy conversion by plasma nitriding or plasma nitrocarburising in a nitrogenous atmosphere.

Description

Gaswechselventil mit Korrosionsschutzschicht Gas exchange valve with corrosion protection layer
Die Erfindung betrifft ein Gaswechselventil einer Brennkraftmaschine mit einem Ventilkegel im Wesentlichen aus einem Ventilschaft, der unter Ausbildung einer Hohlkehle in einen Ventilteller übergeht.The invention relates to a gas exchange valve of an internal combustion engine with a valve cone substantially from a valve stem, which merges into a valve plate to form a groove.
Gaswechselventile, also Ein- und Auslassventile zum Öffnen und Schließen des Gaskanals der Brennkraftmaschine sind großen mechanischen und thermischen Beanspruchungen und Korrosionsangriffen durch die Verbrennungsgase ausgesetzt. Nur hochlegierte Stähle großer Warmfestigkeit und guter Zunderbeständigkeit sind den Belastungen insbesondere der Auslassventile gewachsen.Gas exchange valves, so inlet and outlet valves for opening and closing the gas channel of the internal combustion engine are exposed to large mechanical and thermal stresses and corrosion attacks by the combustion gases. Only high-alloyed steels of high heat resistance and good scaling resistance are able to cope with the stresses, in particular of the exhaust valves.
Zur Erhöhung der Lebensdauer solcher Gaswechselventile sind bereits mehrere Maßnahmen bekannt geworden. So ist beispielsweise der Ventiltelier an der Dichtfläche mit einer besonders widerstandsfähigen CrNi-Legierung gepanzert.To increase the life of such gas exchange valves several measures have already become known. For example, the valve element on the sealing surface is armored with a particularly resistant CrNi alloy.
Wie beispielsweise die DE 43 41 811 A1 vorschlägt, lässt sich zusätzlich zur oben beschriebenen Panzerung bei hochbelasteten Motoren die Lebensdauer des Aus- lassventils durch eine Drehvorrichtung in Form eines Propellers, der am Ventilschaft angebracht ist, um ein Mehrfaches vergrößern. Wegen der Zwangsdrehung durch das ausströmende Abgas, das den Propeller anregt, bleiben Ventilschaftende und Teller frei von Ablagerungen und es kann keine einseitige Erwärmung den Teller undicht werden lassen.For example, as DE 43 41 811 A1 suggests, in addition to the armor described above in highly loaded engines, the life of the discharge valve by a rotating device in the form of a propeller, which is mounted on the valve stem, increase by a multiple. Because of the forced rotation by the outflowing exhaust gas, which excites the propeller, valve stem end and plate remain free of deposits and it can not be one-sided heating the plate to leak.
Doch auch die anderen Teile des Gaswechselventils sind unterschiedlichen Anforderungen hinsichtlich Warm-, Dauer- und Korrosionsfestigkeit unterworfen. Bekanntlich werden unterschiedliche Anforderungen hinsichtlich der Warm-, Dauer- und Korrosionsfestigkeit an den verschiedenen Temperaturzonen des Ventilkegels dadurch berücksichtigt, dass der Ventilteller aus einem hochtemperatur- und abbrandfesten Werkstoff hergestellt ist, während der Ventilschaft mitsamt dem Propeller aus einem Werkstoff mit geringer Kerbempfindlichkeit und hoher Dauerfestigkeit besteht, d.h. eine ausreichende Zähigkeit aufweist, um den in diesem Bereich auftretenden Biegespannungen zu begegnen. Vorzugsweise wird für den Ventilteller ein Material aus einem typischen Ventilstahl oder aus einer Superlegie- rung, wie z.B. NiCr2OTiAI und für den Ventilschaft mit Propeller ein Werkstoff aus einem typischen Ventilstahl, wie z.B. X45CrSi9-3 verwendet. Denn bekanntlich sind Stähle aus einer Nickel-Basis-Legierung zur Vermeidung der Korrosionsbelastung sehr teuer, so dass weitgehend wo verkraftbar das Gaswechselventil eben aus dem typischen Ventilstahl, wie z.B. X45CrSi9-3 gefertigt ist.But the other parts of the gas exchange valve are subject to different requirements in terms of warm, long-term and corrosion resistance. As is known, different requirements with respect to the thermal, fatigue and corrosion resistance at the various temperature zones of the valve cone are taken into account by the fact that the valve disk is made of a high-temperature and erosion-resistant material, while the valve stem together with the propeller of a material with low notch sensitivity and high fatigue strength that is, has sufficient toughness to meet the bending stresses occurring in this area. Preferably, for the valve disk, a material of a typical valve steel or of a superalloy, such as NiCr2OTiAI and for the valve stem with propeller, a material from a typical valve steel, such as X45CrSi9-3 used. For it is well known that steels made of a nickel-based alloy are very expensive in order to avoid the corrosion load, so that largely where tolerable the gas exchange valve is just made of the typical valve steel, such as X45CrSi9-3.
Desweiteren wurde bereits erkannt, dass ein weiterer Aspekt der Beanspruchung eines Gaswechselventils darin besteht, dass Ventilschaft und Hohlkehle durch Nasskorrosion (Kondensation) wegen Taupunktunterschreitung der Verbrennungsgase während des Motorstillstands angegriffen werden.Furthermore, it has already been recognized that another aspect of the stress of a gas exchange valve is that the valve stem and groove are attacked by wet corrosion (condensation) due to dew point of the combustion gases during engine standstill.
Andererseits sind allerdings schon Härteverfahren in Form von Plasmanitrieren oder Plasmanitrocarburieren bei nitridbildenden Stählen bekannt.On the other hand, however, hardening processes in the form of plasma nitriding or plasma nitrocarburizing are already known in nitride-forming steels.
Allgemein versteht man unter Plasmanitrieren / Plasmanitrocarburieren ein Härten von Oberflächenschichten von Stählen, wobei Stickstoff- bzw. Kohlenstoffatome eindiffundieren und dabei in einer dünnen Oberflächenschicht mit Eisen zu Nitriden bzw. Carbonitriden reagieren, der Verbindungsschicht (VS). In der sich daran anschließenden Diffusionsschicht (DS) wird der Stickstoff erst beim Abkühlen teilweise als Nitrid ausgeschieden und bewirkt dann die Härtesteigerung. Die Härte selbst hängt von der Art der Nitride ab. Je nachdem wie der Stickstoff mit dem Stahl zur Reaktion gebracht wird, unterscheiden sich Nitrierzeiten und -schicht. lit anderen Worten, es erfolgt eine Diffusionssättigung der Randschicht eines Werkstoffes mit Stickstoff, um Härte, Verschleißwiderstand, Dauerfestigkeit oder Korrosionsbeständigkeit zu erhöhen. Die Randschicht besteht nach dem Nitrieren / Nitrocarburieren aus einer äußeren Nitrid- bzw. Carbonitridschicht (Verbindungsschicht) und einer anschließenden Schicht aus Stickstoff angereicherten Mischkristallen und ausgeschiedenen Nitriden (Diffusionsschicht).In general, plasma nitriding / plasma nitrocarburizing is understood to mean hardening of surface layers of steels in which nitrogen or carbon atoms diffuse in and thereby react with iron in a thin surface layer to form nitrides or carbonitrides, the bonding layer (VS). In the subsequent diffusion layer (DS), the nitrogen is only partially precipitated as a nitride during cooling and then causes the increase in hardness. The hardness itself depends on the type of nitrides. Depending on how the nitrogen is reacted with the steel, nitriding times and layers differ. In other words, there is a diffusion saturation of the surface layer of a material with nitrogen to increase hardness, wear resistance, fatigue strength or corrosion resistance. The surface layer after nitriding / nitrocarburizing consists of an outer nitride or carbonitride layer (bonding layer) and a subsequent layer of nitrogen-enriched mixed crystals and precipitated nitrides (diffusion layer).
Durch Ionisation des Stickstoffs durch Glimmentladung, das sog. Plasmanitrieren, können die Nitrierzeiten verkürzt werden (Plasmanitrieren bei 450°C bis 55O0C).By ionization of the nitrogen by glow discharge, the so-called plasma nitriding, the nitriding times can be shortened (plasma nitriding at 450 ° C to 55O 0 C).
Beim Nitrokarburieren, bei dem das Behandlungsmittel außer Stickstoff auch Kohlenstoff abgebende Bestandteile enthält, kann in Pulver, Salzbad, Gas oder Plasma eben nitrocarburiert werden (Plasmanitrocarburieren bei 5000C bis 59O0C1 vorzugsweise bei ca. 520°C).When nitrocarburizing in which the treating agent in addition to nitrogen containing and carbon-donating components (plasma nitrocarburizing at 500 0 C to 59 ° C 1 0 preferably at about 520 ° C) may be in powder, salt bath, gas or plasma is just nitrocarburized.
Hiervon ausgehend ist es die Aufgabe der vorliegenden Erfindung, ein gattungsbildendes Gaswechselventil dahingehend weiterzubilden, dass auch dessen Teile, die aus eingangs beschriebenen typischen Ventilstählen bestehen, einen guten Korrosionsschutz aufweisen.On this basis, it is the object of the present invention to develop a generic gas exchange valve to the effect that even its parts, which consist of the above-described typical valve steels, have good corrosion protection.
Diese Aufgabe wird durch die kennzeichnenden Merkmale des Anspruchs 1 für ein Gaswechselventil der gattungsgemäßen Art gelöst.This object is achieved by the characterizing features of claim 1 for a gas exchange valve of the generic type.
Ist der Ventilkörper des Gaswechselventils eben einstückig ausgeführt und wie eingangs beschrieben der Ventilteller an der Dichtfläche bzw. am Sitzbereich gepanzert, so ist in bevorzugter Weise die Nitrid- bzw. Carbonitridschicht komplett am Ventilschaft und der Hohlkehle bis zur gepanzerten Dichtfläche vorgesehen.If the valve body of the gas exchange valve is made in one piece and armored as described above, the valve plate to the sealing surface or the seating area, so in a preferred manner, the nitride or carbonitride completely on the valve stem and the groove provided to the armored sealing surface.
Die Erfindung wird anhand der einzigen Figur erläutert: Das Gaswechselventil, insbesondere ein Auslassventil (1 ) für eine Brennkraftmaschine weist eine Dreh Vorrichtung in Form eines auf ihrem Ventilschaft (2) angeordneten Propellers (3) auf. Der Ventilteller (4) ist an seiner Dichtfläche (5) gepan- zeit Die Flügel (6) des Propellers (3) sind aus der Drehform des Propellers herausgefräst.The invention will be explained with reference to the single figure: The gas exchange valve, in particular an exhaust valve (1) for an internal combustion engine, has a rotary device in the form of a propeller (3) arranged on its valve stem (2). The valve disk (4) is chamfered on its sealing surface (5). The blades (6) of the propeller (3) are milled out of the rotary shape of the propeller.
Des weiteren werden unterschiedliche Anforderungen hinsichtlich Warm-, Dauer- und Korrosionsfestigkeit an den verschiedenen Temperaturzonen des Ventilkegels (1 ) dadurch berücksichtigt, dass der Ventilteller (4) aus einem hochtemperatur- und abbrandfesten Werkstoff hergestellt ist, während der Ventilschaft (2) mitsamt dem Propeller (3) aus einem Werkstoff mit geringer Kerbempfindlichkeit und hoher Dauerfestigkeit besteht, d.h. eine ausreichende Zähigkeit aufweist, um den in diesem Bereich auftretenden Biegespannungen zu begegnen. Vorzugsweise wird für den Ventilteller (4) ein Material aus einem typischen Ventilstahl oder aus einer Su- perlegierung, wie z.B. NiCr2OTiAI und für den Ventilschaft (2) mit Propeller (3) ein Werkstoff aus einem Warmarbeitsstahl, wie z.B. X45CrSi9-3 verwendet. Der Ventilteller (4) ist mit dem Ventilschaft (2) durch eine Reibschweißung (7) verbunden.Furthermore, different requirements in terms of thermal stability, durability and corrosion resistance at the various temperature zones of the valve plug (1) are taken into account in that the valve disk (4) is made of a high-temperature and erosion-resistant material, while the valve stem (2) together with the propeller (3) consists of a material with low notch sensitivity and high fatigue strength, ie has sufficient toughness to meet the bending stresses occurring in this area. Preferably, for the valve disk (4), a material of a typical valve steel or of a superalloy, such as, for example, is used. NiCr2OTiAI and for the valve stem (2) with propeller (3) a material of a hot work tool steel, such as X45CrSi9-3 used. The valve disk (4) is connected to the valve stem (2) by friction welding (7).
Bei dem hier beispielhaft gezeigten Auslassventil (1 ) ist der Ventilkegel zumindest in Teilbereichen mit einer Korrosionsschutzschicht in Form einer Nitrierschicht (8) versehen, wobei die Korrosionsschutzschicht durch Umsetzung der nitridbildenden Basislegierung durch Plasmanitrieren oder Plasmanitrocarburieren in einer Stickstoff- bzw. Stickstoff-Kohlenstoff-Atmosphäre erzeugt ist.In the case of the outlet valve (1) shown here by way of example, the valve cone is provided with a corrosion protection layer in the form of a nitriding layer (8), whereby the corrosion protection layer is obtained by reacting the nitride-forming base alloy by plasma nitriding or plasma nitrocarburizing in a nitrogen or nitrogen-carbon atmosphere is generated.
In bevorzugter Weise ist hier bei der zweistückigen Ausführung eines Gaswechselventils der komplette Ventilschaft (2) bis zur Reibschweißung (7), an der eben der Warmarbeitsstahlwerkstoff begrenzt ist, mit der Nitrierschicht (8) versehen, der Bereich der Hohlkehle (11) bleibt offen. Natürlich können allgemein sowohl bei der einstückigen, als auch bei der mehrstückigen Ausführung eines Gaswechselventils die beiden Stirnseiten am Ventilteller (4) und am Ventilschaft (2) bezüglich der Nitrid- bzw. Carbonitridschicht (8) ausgespart bleiben.Preferably, in the case of the two-piece design of a gas exchange valve, the complete valve stem (2) is provided with the nitriding layer (8) until friction welding (7), at which the hot-work steel material is limited, the region of the groove (11) remains open. Of course, in general, both in the one-piece, as well as in the multi-piece design of a gas exchange valve the two end faces on the valve plate (4) and on the valve stem (2) remain recessed with respect to the nitride or carbonitride layer (8).
Es kann aber auch, bevorzugt bei der einstückigen Ausführung, der komplette Ventilkegel (1 ) bis auf den gepanzerten Ventilsitzbereich (5) des Ventiltellers (4) sowie bis auf dessen Tellerboden und der Ventilschaftstirnseite mit der Nitrierschicht (8) versehen sein.But it can also, preferably in the one-piece design, the complete valve plug (1) except for the armored valve seat portion (5) of the valve disc (4) and to the plate bottom and the valve stem end face with the nitriding layer (8) may be provided.
Bei dem erfindungsgemäßen Gaswechselventil wird die Oberfläche in der Weise umgewandelt, dass eine harte, verschleißbeständige Randschicht entsteht. Dazu wird der Ventilkegelrohling entweder teilweise in Form des Ventilschafts oder komplett mit Ventilschaft (2) und Ventilteller (4) über alle Fertigungsschritte hin bearbeitet, so dass er in seiner endgültigen Oberflächenrauheit vorliegt, anschließend erfolgt das Plasmanitrieren bzw. Plasmanitrocarburieren. Eine Nachbehand- lung des nitrierten Gaswechselventils ist möglich aber nicht notwendig (allerdings sollte die Nachbehandlung in den vor Korrosion zu schützenden Bereichen des Gaswechselventils jedoch nicht vorgenommen werden, um die erzeugte Verbindungsschicht nicht zu entfernen). Beispielsweise kann der Ventilkegel (1) nach dem Nitrieren geschliffen werden.In the gas exchange valve according to the invention, the surface is converted in such a way that a hard, wear-resistant edge layer is formed. For this purpose, the valve plug blank is processed either partially in the form of the valve stem or complete with valve stem (2) and valve disc (4) through all manufacturing steps, so that it is present in its final surface roughness, followed by plasma nitriding or Plasmanitrocarburieren. Aftertreatment of the nitrided gas exchange valve is possible but not necessary (however, the aftertreatment in the areas of the gas exchange valve to be protected from corrosion should not be carried out in order not to remove the connection layer produced). For example, the valve plug (1) can be ground after nitriding.
Es kann als charakteristisch für die erzeugten Korrosionsschutzschichten angegeben werden, dass die Nitrierschicht eine Diffusionsschicht (9) mit einer Dicke (Nitrierhärtetiefe) von 0,1 mm bis 0,3 mm und eine darauf aufgebaute Verbindungsschicht (10) von 3 μm bis 15 μm aufweist und eine Oberflächenhärte größer als 750 HV (Vickers) bietet.It may be stated that the nitriding layer has a diffusion layer (9) with a thickness (nitriding hardening depth) of 0.1 mm to 0.3 mm and a connecting layer (10) constructed thereon of 3 μm to 15 μm as characteristic of the anticorrosion layers produced and has a surface hardness greater than 750 HV (Vickers).
Wenn für die Verbindungsschicht eine Dicke um die 10 μm erreicht werden soll, ist das Plasmanitrocarburieren unter Zugabe von Kohlenstoff vorzuziehen. Durch das Plasmanitrieren bzw. Plasmanitrocarburieren des Ventilkegels (1 ) wird ein deutlich verbesserter Korrosionsschutz und eine Erhöhung der Dauerwechselfestigkeit erreicht, d.h. längere Wartungsintervalle bzw. Bauteillebensdauer werden erreicht und der Rissbildung durch Biegebelastung entgegen gewirkt. If a thickness of about 10 μm is to be achieved for the bonding layer, plasma nitrocarburization with the addition of carbon is preferable. By plasma nitriding or plasmanitrocarburizing the valve plug (1) a significantly improved corrosion protection and an increase in the fatigue strength is achieved, ie longer maintenance intervals or component life are achieved and counteracted cracking by bending stress.

Claims

Patentansprüche claims
1. Gaswechselventil einer Brennkraftmaschine mit einem Ventilkegel (1 ) im Wesentlichen aus einem Ventilschaft (2), der unter Ausbildung einer Hohlkehle (1 1 ) in einen Ventilteller (4) übergeht und der Ventiikegel (1 ) oder zumindest der Ventilschaft; (2) bis in den Bereich der Hohlkehle (11 ) aus einem typischen1. Gas exchange valve of an internal combustion engine having a valve cone (1) substantially of a valve stem (2), the formation of a groove (1 1) in a valve plate (4) merges and the Ventiiegegel (1) or at least the valve stem; (2) to the area of the groove (11) from a typical
Ventilstahl aus einer nitridbildenden Basislegierung gefertigt ist, dadurch gekennzeichnet, dass der Ventilkegel (1 ) zumindest in Teilbereichen mit einer Korrosionsschutzschicht (8) in Form einer Nitrid- bzw. Carbonitridschicht versehen ist, wobei die Korrosionsschutzschicht (8) durch Umsetzung der nitrid- bildenden Basislegierung durch Plasmanitrieren oder Plasmanitrocarburieren in einer Stickstoffatmosphäre erzeugt ist.Valve steel is made of a nitride-forming base alloy, characterized in that the valve cone (1) is provided at least in some areas with a corrosion protection layer (8) in the form of a nitride or carbonitride, wherein the corrosion protection layer (8) by reacting the nitride-forming base alloy by plasma nitriding or plasma nitrocarburizing in a nitrogen atmosphere.
2. Gaswechselventil nach Anspruch 1 , dadurch gekennzeichnet, dass bei einer einstückigen Ausführung der komplette Ventilkegel (1 ) bis auf einen gepanzerten Ventilsitzbereich des Ventiltellers (4) sowie bis auf dessen Tellerboden und der Ventilschaftstirnseite mit der Nitrierschicht (8) versehen ist.2. Gas exchange valve according to claim 1, characterized in that in a one-piece design of the complete valve plug (1) except for an armored valve seat portion of the valve disc (4) and up to the plate bottom and the valve stem end face with the nitriding layer (8) is provided.
3. Gaswechselventil nach Anspruch 1 , dadurch gekennzeichnet, dass bei einer zweistückigen Ausführung der Ventilschaft (2) zumindest an seinen mit den Verbrennungsgasen in Kontakt kommenden Aussenflächen komplett bis zu einer Grenzfläche (7), an der eben der Warmarbeitsstahlwerkstoff begrenzt ist, mit der Nitrierschicht (8) versehen ist, während der Ventilteller (4) und eventuell der Bereich der Hohlkehle (11 ) hinsichtlich der Nitrierschicht (8) offen bleibt.3. Gas exchange valve according to claim 1, characterized in that in a two-piece design of the valve stem (2) at least at its coming into contact with the combustion gases outer surfaces completely up to an interface (7) on which just the hot-work steel material is limited, with the nitriding (8) is provided, while the valve disc (4) and possibly the region of the groove (11) with respect to the nitriding layer (8) remains open.
4. Gaswechselventil nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Nitrierschicht (8) eine Diffusionsschichtdicke (9) (Nit- rierhärtetiefe) von 0,1 mm bis 0,3 mm und eine darauf aufgebaute Verbindungsschicht (10) von 3 μm bis 15 μm aufweist und eine Oberflächenhärte größer als 750 HV (Vickers) bietet. 4. Gas exchange valve according to one of the preceding claims, characterized in that the nitriding layer (8) has a diffusion layer thickness (9) (nitration hardening depth) of 0.1 mm to 0.3 mm and a connection layer (10) constructed thereon of 3 μm to 15 microns and a surface hardness greater than 750 HV (Vickers) offers.
EP06707539A 2005-03-18 2006-03-14 Gas shuttle valve provided with an anti-corrosive layer Withdrawn EP1864003A1 (en)

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DE102005013088A DE102005013088B4 (en) 2005-03-18 2005-03-18 Gas exchange valve with corrosion protection layer
PCT/EP2006/002292 WO2006097264A1 (en) 2005-03-18 2006-03-14 Gas shuttle valve provided with an anti-corrosive layer

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KR20070112287A (en) 2007-11-22
DE102005013088B4 (en) 2006-12-28
JP2008533372A (en) 2008-08-21
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DE102005013088A1 (en) 2006-09-21
WO2006097264A1 (en) 2006-09-21

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