EP0334064B1 - Element in the valve gear of an internalcombustion engine - Google Patents

Element in the valve gear of an internalcombustion engine Download PDF

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Publication number
EP0334064B1
EP0334064B1 EP89103613A EP89103613A EP0334064B1 EP 0334064 B1 EP0334064 B1 EP 0334064B1 EP 89103613 A EP89103613 A EP 89103613A EP 89103613 A EP89103613 A EP 89103613A EP 0334064 B1 EP0334064 B1 EP 0334064B1
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EP
European Patent Office
Prior art keywords
component
coating
layer
control cam
valve gear
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.)
Expired - Lifetime
Application number
EP89103613A
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German (de)
French (fr)
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EP0334064A1 (en
Inventor
Norbert Dipl.-Chem.Dr. Geheeb
Ernst Dipl.-Ing.Dr. Mayer
Uwe Dipl.-Ing. Köhler
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.)
INA Waelzlager Schaeffler OHG
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INA Waelzlager Schaeffler OHG
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Publication of EP0334064A1 publication Critical patent/EP0334064A1/en
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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
    • F01L1/20—Adjusting or compensating clearance
    • F01L1/22—Adjusting or compensating clearance automatically, e.g. mechanically
    • F01L1/24—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically
    • F01L1/245—Hydraulic tappets
    • F01L1/25—Hydraulic tappets between cam and valve stem
    • 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
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/14—Tappets; Push rods
    • F01L1/16—Silencing impact; Reducing wear

Definitions

  • the invention relates to a component in the valve timing drive of an internal combustion engine, against the surface of which a control cam runs, in particular a tappet, a metallic coating having a layer thickness of at most 5 ⁇ m being applied to the surface against which the control cam runs.
  • the invention is based on the object of proposing a surface coating for components of this type which, in addition to favorable wear behavior, also ensures high flexural fatigue strength, compressive strength and thus long service life of the component.
  • the coating is a chrome layer with a layer thickness of preferably 2.5 microns, which consists of several layers applied one after the other, at least the first layer directly applied to the material of the component is free of microcracks, and the last layer has micro cracks.
  • a layer thickness of preferably 2.5 microns which consists of several layers applied one after the other, at least the first layer directly applied to the material of the component is free of microcracks, and the last layer has micro cracks.
  • the micro-crack-free first layer can expediently be applied by electrolytic metal deposition (electroplating) with a current density of approximately 15 A / dm 2, while the outer layer, which has at least 600 cracks / cm, is electroplated with a current density of less than 15 A / dm2 can be applied.
  • the chromium-coated component is expediently heated after the electroplating and kept at a temperature of approximately 120 ° C. for four hours before being allowed to cool in air.
  • valve train with a tappet is shown in longitudinal section:
  • the tappet 3 which contains a hydraulic valve clearance compensation element in a known manner, is mounted so as to be longitudinally displaceable.
  • the control cam 5 runs on the flat bottom 4 of the tappet 3, while the tappet, on the other hand, bears against the stem 6 of a control valve.
  • the bottom 4 of the tappet 3 is provided with a thin chrome layer 7 according to the invention.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)

Description

Die Erfindung betrifft ein Bauteil im Ventilsteuertrieb einer Brennkraftmaschine, gegen dessen Oberfläche ein Steuernocken anläuft, insbesondere einen Tassenstößel, wobei auf die Oberfläche, gegen die der Steuernocken anläuft, eine metallische Beschichtung mit einer Schichtdicke von maximal 5 µm aufgebracht ist.The invention relates to a component in the valve timing drive of an internal combustion engine, against the surface of which a control cam runs, in particular a tappet, a metallic coating having a layer thickness of at most 5 μm being applied to the surface against which the control cam runs.

Bei derartigen bekannten Bauteilen, insbesondere auch bei den neuerdings häufig verwendeten Tassenstößeln, stellt man fest, daß an der Fläche, an welcher der Steuernocken anläuft, auch unter günstigen Schmierbedingungen starker Verschleiß auftritt. Man hat versucht, dagegen anzugehen, indem man dieser Oberfläche z.B. durch Phosphatieren oder Cadmieren günstigere Gleiteigenschaften gegeben hat. Man hat auch bereits vorgeschlagen, diese Oberflächen mit einer weichen Metallschicht, z.B. aus Kupfer, Zinn oder Blei mit einer Schichtdicke von wenigen µm zu versehen (GB-A-1044692). Alle diese Maßnahmen hatten jedoch nur geringen, insbesondere zeitlich eingeschränkten Erfolg.With known components of this type, in particular also with the cup tappets that have recently been used frequently, it is found that severe wear occurs on the surface on which the control cam runs, even under favorable lubrication conditions. An attempt has been made to tackle this by e.g. has given more favorable sliding properties by phosphating or cadmium coating. It has also been proposed to cover these surfaces with a soft metal layer, e.g. made of copper, tin or lead with a layer thickness of a few µm (GB-A-1044692). However, all of these measures had little, especially limited, success.

Es wurde auch vorgeschlagen, die Ventilschäfte von Steuerventilen zur Verschleißminderung mit einer Chromschicht zu versehen (Automotive Engineering, Band 94, Mai 1986, Seiten 40-45, Society of Automotive Engineers, Inc., Dallas, Texas, US; "Valve gear materials: An over-view"). Auch an den Oberflächen, gegen die der Steuernocken anläuft, hat man durch Hartverchromen versucht, den Verschleiß zu verringern, denn es war bekannt, daß Hartchromschichten sehr günstige Verschleißeigenschaften besitzen. Man hat dazu die für Hartchrom bewährten Schichtdicken von 10 µm und mehr aufgetragen. Die einschlägige Literatur nennt für Hartchromschichten Schichtdicken von 10 µm bis zu mehreren mm ("Galvanisierte Produkte" Gütesicherung RAL-RG 660, Teil 1 und Teil 2, Ausgabe November 1986, Deutsches Institut für Gütesicherung und Kennzeichnung). Diese sonst erfolgreiche Oberflächenbeschichtung brachte in der Praxis keinen Erfolg, weil die Chromschicht nach relativ kurzer Betriebsdauer abplatzte und damit den Verschleiß zusätzlich beschleunigte. Das Abplatzen der Chromschicht ist darauf zurückzuführen, daß die Oberfläche, auf die sie aufgebracht wurde, insbesondere der Boden von Tassenstößeln im Betrieb Durchbiegungen einer Größenordnung erleidet, welche eine bekannte Hartchromschicht nicht unbeschädigt mitmachen kann. Es kommt deshalb zu Rissen und Abplatzungen.It has also been proposed to provide the valve stems of control valves with a chrome layer to reduce wear (Automotive Engineering, Volume 94, May 1986, pages 40-45, Society of Automotive Engineers, Inc., Dallas, Texas, US; "Valve gear materials: An over-view "). Hard chrome plating has also been used on the surfaces against which the control cam runs to reduce wear, since it was known that hard chrome layers have very favorable wear properties. The layer thicknesses of 10 µm and more, which have been tried and tested for hard chrome, have been applied. The relevant literature lists layer thicknesses of 10 µm to several for hard chrome layers mm ("Galvanized Products" Quality Assurance RAL-RG 660, Part 1 and Part 2, November 1986 Edition, German Institute for Quality Assurance and Labeling). This otherwise successful surface coating was unsuccessful in practice because the chrome layer flaked off after a relatively short period of operation and thus additionally accelerated wear. The flaking of the chrome layer is due to the fact that the surface to which it was applied, in particular the bottom of cup tappets, undergoes deflections of an order of magnitude in operation which a known hard chrome layer cannot withstand undamaged. This leads to cracks and flaking.

Der Erfindung liegt die Aufgabe zugrunde, für derartige Bauteile eine Oberflächenbeschichtung vorzuschlagen, die neben günstigem Verschleißverhalten auch hohe Biegedauerfestigkeit, Druckfestigkeit und damit lange Lebensdauer des Bauteiles gewährleistet.The invention is based on the object of proposing a surface coating for components of this type which, in addition to favorable wear behavior, also ensures high flexural fatigue strength, compressive strength and thus long service life of the component.

Nach der Erfindung wird dieses Ziel dadurch erreicht, daß die Beschichtung eine Chromschicht mit einer Schichtdicke von vorzugsweise 2,5 µm ist, die aus mehreren nacheinander aufgebrachten Lagen besteht, von denen wenigstens die erste unmittelbar auf den Werkstoff des Bauteils aufgebrachte Lage mikrorißfrei ist, und die letzte Lage Mikrorisse aufweist. Die Praxis hat gezeigt, daß eine derartige Schicht in der Lage ist, die an dem Bauteil, insbesondere am Boden eines Tassenstößels, auftretenden Verformungen und Drücke an den Stellen der Krafteinleitung zu ertragen, ohne daß schädliche Einflüsse auf die Lebensdauer der Chromschicht wirksam werden. Es wurden vielmehr im Versuch Standzeiten festgestellt, die weitaus höher lagen, als bei herkömmlichen Tassenstößeln ohne Oberflächenbehandlung.According to the invention, this aim is achieved in that the coating is a chrome layer with a layer thickness of preferably 2.5 microns, which consists of several layers applied one after the other, at least the first layer directly applied to the material of the component is free of microcracks, and the last layer has micro cracks. Practice has shown that such a layer is able to withstand the deformations and pressures occurring on the component, in particular at the bottom of a tappet, at the points where force is applied, without having any detrimental effects on the life of the chrome layer. Rather, the service life was determined in the test, which was far higher than that of conventional tappets without surface treatment.

Als besonders zweckmäßig hat es sich gezeigt, wenn die zuletzt aufgebrachte Lage wenigstens 600 Risse/cm aufweist.It has proven particularly expedient if the last layer applied has at least 600 cracks / cm.

Zweckmäßigerweise läßt sich die mikrorißfreie erste Lage durch elektrolytische Metallbscheidung (galvanisch) mit einer Stromdichte von ungefähr 15 A/dm² aufbringen, während die äußere, wenigstens 600 Risse/cm aufweisende Lage galvanisch mit einer Stromdichte von weniger als 15 A/dm² aufgebracht werden kann.The micro-crack-free first layer can expediently be applied by electrolytic metal deposition (electroplating) with a current density of approximately 15 A / dm 2, while the outer layer, which has at least 600 cracks / cm, is electroplated with a current density of less than 15 A / dm² can be applied.

Um die Gefahr einer durch Wasserstoff verursachten Schädigung des Grundwerkstoffs zu vermindern, wird das mit Chrom fertig beschichtete Bauteil nach dem Galvanisieren zweckmäßigerweise erwärmt und vier Stunden lang auf einer Temperatur von ungefähr 120°C gehalten, bevor man es an der Luft abkühlen läßt.In order to reduce the risk of damage to the base material caused by hydrogen, the chromium-coated component is expediently heated after the electroplating and kept at a temperature of approximately 120 ° C. for four hours before being allowed to cool in air.

In der Zeichnung ist ein Ventiltrieb mit einem Tassenstößel im Längsschnitt dargestellt:In the drawing, a valve train with a tappet is shown in longitudinal section:

In einer Bohrung 1 des Zylinderkopfes 2 ist der Tassenstößel 3, der in bekannter Weise ein hydraulisches Ventilspielausgleichselement enthält, längsverschieblich gelagert. Auf dem ebenen Boden 4 des Tassenstößels 3 läuft der Steuernocken 5 an, während der Tassenstößel andererseits gegen den Schaft 6 eines Steuerventiles anliegt. Der Boden 4 des Tassenstößels 3 ist erfindungsgemäß mit einer dünnen Chromschicht 7 versehen.In a bore 1 of the cylinder head 2, the tappet 3, which contains a hydraulic valve clearance compensation element in a known manner, is mounted so as to be longitudinally displaceable. The control cam 5 runs on the flat bottom 4 of the tappet 3, while the tappet, on the other hand, bears against the stem 6 of a control valve. The bottom 4 of the tappet 3 is provided with a thin chrome layer 7 according to the invention.

Claims (2)

1. Component in the valve control gear of an internal combustion engine, against the surface (4) of which component, in particular a cup tappet (3), there runs a control cam (5), a metallic coating with a maximum coating thickness of 5 µm being applied to the surface (4) contacted by the control cam (5), characterized in that the coating is a chromium coating (7) with a coating thickness of preferably 2.5 µm which consists of several successively applied layers of which at least the first layer applied directly to the material of the component is free of microcracks, and the last layer contains microcracks.
2. Component according to claim 1, characterized in that the last layer applied contains at least 600 craks/cm.
EP89103613A 1988-03-23 1989-03-02 Element in the valve gear of an internalcombustion engine Expired - Lifetime EP0334064B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3809702A DE3809702A1 (en) 1988-03-23 1988-03-23 COMPONENT IN THE VALVE CONTROL DRIVE OF AN INTERNAL COMBUSTION ENGINE
DE3809702 1988-03-23

Publications (2)

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EP0334064A1 EP0334064A1 (en) 1989-09-27
EP0334064B1 true EP0334064B1 (en) 1991-12-27

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EP89103613A Expired - Lifetime EP0334064B1 (en) 1988-03-23 1989-03-02 Element in the valve gear of an internalcombustion engine

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US (1) US4876996A (en)
EP (1) EP0334064B1 (en)
DE (2) DE3809702A1 (en)

Families Citing this family (18)

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IT1230012B (en) * 1989-04-20 1991-09-20 Eaton Automotive Spa HYDRAULIC TAPPET WITH OIL SUCTION DUCT, FROM THE EXTERNAL TANK TO THE INTERNAL TANK WITHOUT INCLUSIONS OF AIR BUBBLES, MADE BY MECHANICAL PROCESSING.
DE4117425C1 (en) * 1991-05-28 1992-07-30 Fa. Carl Freudenberg, 6940 Weinheim, De
DE4118776A1 (en) * 1991-06-07 1992-12-10 Schaeffler Waelzlager Kg MECHANICAL VALVE TUNEL FOR AN INTERNAL COMBUSTION ENGINE
DE4220584C2 (en) * 1992-06-24 2001-02-01 Schaeffler Waelzlager Ohg Valve train of an internal combustion engine
US5226389A (en) * 1992-11-04 1993-07-13 Eaton Corporation Direct acting tappet
US5237967A (en) * 1993-01-08 1993-08-24 Ford Motor Company Powertrain component with amorphous hydrogenated carbon film
US5249554A (en) * 1993-01-08 1993-10-05 Ford Motor Company Powertrain component with adherent film having a graded composition
DE4302877C2 (en) * 1993-02-02 1996-04-11 Schaeffler Waelzlager Kg Pestle
US5289804A (en) * 1993-03-25 1994-03-01 Fuji Oozx Inc. Tappet in an internal combustion engine
US5743224A (en) * 1993-09-14 1998-04-28 Unisia Jecs Corporation Valve lifter surface and processing method thereof
DE9317325U1 (en) * 1993-11-12 1994-01-05 INA Wälzlager Schaeffler KG, 91074 Herzogenaurach Tappet for a valve train of an internal combustion engine
US6119644A (en) * 1997-05-22 2000-09-19 Ina Walzlager Schaeffler Ohg Hydraulic clearance compensation element
IT1302651B1 (en) * 1998-10-13 2000-09-29 Eaton Automotive Spa HYDRAULIC TAPPETS WITH CONTROLLED HEIGHT LOSS.
WO2001048267A1 (en) * 1999-12-27 2001-07-05 Nippon Piston Ring Co., Ltd. Sliding member
JP4059621B2 (en) * 2000-09-29 2008-03-12 日本ピストンリング株式会社 Chromium plating sliding member and manufacturing method thereof
US20050084610A1 (en) * 2002-08-13 2005-04-21 Selitser Simon I. Atmospheric pressure molecular layer CVD
DE10249761A1 (en) * 2002-10-25 2004-05-13 Ina-Schaeffler Kg Cam follower of a valve train of an internal combustion engine
DE102004028221A1 (en) 2004-06-09 2005-12-29 Ina-Schaeffler Kg Highly stressed engine component

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1425653A1 (en) * 1963-07-08 1969-01-23 Richard Kuechen Sen Valve drive with hydraulic backlash compensation

Family Cites Families (8)

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US32167A (en) * 1861-04-23 Thomas h
US3131470A (en) * 1960-12-09 1964-05-05 Burgess Norton Mfg Co Method of making valve lifters
GB1044692A (en) * 1964-02-18 1966-10-05 Daimler Benz Ag Improvements relating to cam devices
US3545415A (en) * 1967-04-08 1970-12-08 Nippon Piston Ring Co Ltd Valve lifter with thin plastic coating
US4230491A (en) * 1979-01-08 1980-10-28 Stanadyne, Inc. Internal combustion engine tappet comprising a sintered powdered metal wear resistant composition
US4367701A (en) * 1979-12-05 1983-01-11 Eaton Corporation Acting valve gear
US4688526A (en) * 1983-12-07 1987-08-25 Eaton Corporation Self-contained hydraulic bucket lifter
JPS62255507A (en) * 1986-04-30 1987-11-07 Hitachi Ltd Manufacture of valve lifter

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
DE1425653A1 (en) * 1963-07-08 1969-01-23 Richard Kuechen Sen Valve drive with hydraulic backlash compensation

Also Published As

Publication number Publication date
DE58900604D1 (en) 1992-02-06
US4876996A (en) 1989-10-31
DE3809702A1 (en) 1989-10-05
EP0334064A1 (en) 1989-09-27

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