EP0334064A1 - 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
EP0334064A1
EP0334064A1 EP89103613A EP89103613A EP0334064A1 EP 0334064 A1 EP0334064 A1 EP 0334064A1 EP 89103613 A EP89103613 A EP 89103613A EP 89103613 A EP89103613 A EP 89103613A EP 0334064 A1 EP0334064 A1 EP 0334064A1
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EP
European Patent Office
Prior art keywords
layer
component
control cam
chrome
tappet
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
EP89103613A
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German (de)
French (fr)
Other versions
EP0334064B1 (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
Original Assignee
INA Waelzlager Schaeffler OHG
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Publication date
Application filed by INA Waelzlager Schaeffler OHG filed Critical INA Waelzlager Schaeffler OHG
Publication of EP0334064A1 publication Critical patent/EP0334064A1/en
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Publication of EP0334064B1 publication Critical patent/EP0334064B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • F01L1/20—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 bucket tappet.
  • 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.
  • this aim is achieved in that a chrome layer with a layer thickness of at most 5 ⁇ m, preferably 2.5 ⁇ m, is applied to the surface of the component against which the control cam runs.
  • a chrome layer with a layer thickness of at most 5 ⁇ m, preferably 2.5 ⁇ m is applied to the surface of the component against which the control cam runs.
  • the chrome layer consists of a plurality of layers applied one after the other, at least the last of which, which forms the sliding surface for the control cam, has microcracks. It has been shown that it is of great importance for the sliding properties on the surface of the chrome layer that there are microcracks in which lubricant can accumulate. On the other hand, for the durability of the chrome layer, it is essential that the first layer, which creates the connection to the material of the component, is free of microcracks, in order to avoid micro-notching and thus starting points for a possible peeling of the layer.
  • 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 shaft 6 of a control valve.
  • the bottom 4 of the tappet 3 is provided with a thin chrome layer 7 according to the invention.

Abstract

Bei einem Bauteil im Ventilsteuertrieb einer Brennkraftmaschine, gegen dessen Oberfläche (4) ein Steuernocken (5) anläuft, insbesondere einem Tassenstößel (3), wird zur Verbesserung des Verschleißverhaltens und damit zur Erzielung einer langen Lebensdauer auf die Oberfläche (4), gegen die der Steuernocken (5) anläuft, eine Chromschicht (7) mit einer Schichtdicke von maximal 5 µm, vorzugsweise 2,5 µm aufgebracht.In the case of a component in the valve control drive of an internal combustion engine, against whose surface (4) a control cam (5) starts, in particular a tappet (3), the surface (4) against which the Control cam (5) starts, a chrome layer (7) with a layer thickness of at most 5 microns, preferably 2.5 microns applied.

Description

Die Erfindung betrifft ein Bauteil im Ventilsteuertrieb einer Brennkraft­maschine, gegen dessen Oberfläche ein Steuernocken anläuft, insbesondere einen Tassenstößel.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 bucket tappet.

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. Dies hatte jedoch nur geringen, insbesondere zeitlich eingeschränkten Erfolg. Man versuchte auch den Verschleiß durch Hartverchromen der Oberfläche, gegen die der Steuernocken anläuft, 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 un­ beschädigt mitmachen kann. Es kommt deshalb zu Rissen und Abplatzungen.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. Attempts have been made to tackle this by using this surface e.g. B. has given more favorable sliding properties by phosphating or cadmium coating. However, this had little, especially limited, success. Attempts have also been made to reduce the wear by hard chrome plating of the surface against which the control cam runs, since it was known that hard chrome plating had 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 up to several mm for hard chrome layers ("Galvanized products" quality assurance RAL-RG 660, part 1 and part 2, edition November 1986, 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 does not can take part damaged. 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 auf die Ober­fläche des Bauteiles, gegen die der Steuernocken anläuft, eine Chrom­schicht mit einer Schichtdicke von maximal 5 µm, vorzugsweise 2,5 µm aufgebracht ist. Die Praxis hat gezeigt, daß eine derart dünne 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 a chrome layer with a layer thickness of at most 5 μm, preferably 2.5 μm, is applied to the surface of the component against which the control cam runs. Practice has shown that such a thin layer is able to withstand the deformations and pressures that occur on the component, in particular on the bottom of a cup 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 erwiesen, wenn die Chromschicht aus mehreren nacheinander aufgebrachten Lagen besteht, von denen wenigstens die letzte, die die Gleitfläche für den Steuernocken bildet, Mikrorisse aufweist. Es hat sich gezeigt, daß es für die Gleiteigenschaften an der Oberfläche der Chromschicht von großer Bedeutung ist, daß dort Mikrorisse vorhanden sind, in denen sich Schmierstoff ansammeln kann. Für die Haltbarkeit der Chromschicht ist es andrerseits von wesentlicher Bedeutung, daß die erste, die Verbindung zu dem Werkstoff des Bauteiles herstellende Lage mikrorißfrei ist, um so Mikrokerbwirkung und damit Ansatzpunkte für ein eventuelles Abplatzen der Schicht zu vermeiden.It has proven to be particularly expedient if the chrome layer consists of a plurality of layers applied one after the other, at least the last of which, which forms the sliding surface for the control cam, has microcracks. It has been shown that it is of great importance for the sliding properties on the surface of the chrome layer that there are microcracks in which lubricant can accumulate. On the other hand, for the durability of the chrome layer, it is essential that the first layer, which creates the connection to the material of the component, is free of microcracks, in order to avoid micro-notching and thus starting points for a possible peeling of the layer.

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 Metallabscheidung (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 shaft 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 (4)

1. Bauteil im Ventilsteuertrieb einer Brennkraftmaschine, gegen dessen Oberfläche (4) ein Steuernocken (5) anläuft, insbesondere Tassenstößel (3), dadurch gekennzeichnet, daß auf die Oberfläche (4), gegen die der Steuer­nocken (5) anläuft, eine Chromschicht (7) mit einer Schichtdicke von maximal 5 µm, vorzugsweise 2,5 µm aufgebracht ist.1. component in the valve timing drive of an internal combustion engine, against whose surface (4) a control cam (5) starts, in particular bucket tappet (3), characterized in that on the surface (4) against which the control cam (5) runs, a chrome layer ( 7) is applied with a layer thickness of at most 5 µm, preferably 2.5 µm. 2. Bauteil nach Anspruch 1, dadurch gekennzeichnet, daß die Chromschicht (7) aus mehreren nacheinander aufgebrachten Lagen besteht, von denen wenigstens die letzte Mikrorisse aufweist.2. Component according to claim 1, characterized in that the chrome layer (7) consists of several successively applied layers, of which at least the last has micro cracks. 3. Bauteil nach Anspruch 2, dadurch gekennzeichnet, daß die zuletzt aufgebrachte Lage wenigstens 600 Risse/cm aufweist.3. Component according to claim 2, characterized in that the last applied layer has at least 600 cracks / cm. 4. Bauteil nach einem der vorhergehenden Ansprüche, dadurch gekenn­zeichnet, daß wenigstens die erste unmittelbar auf den Werkstoff des Bau­teils aufgebrachte Lage mikrorißfrei ist.4. Component according to one of the preceding claims, characterized in that at least the first layer applied directly to the material of the component is free of microcracks.
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
DE3809702 1988-03-23
DE3809702A DE3809702A1 (en) 1988-03-23 1988-03-23 COMPONENT IN THE VALVE CONTROL DRIVE OF AN INTERNAL COMBUSTION ENGINE

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

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0396288B1 (en) * 1989-04-20 1993-06-16 Eaton Engine Lifters Spa Hydraulic tappet
US5267538A (en) * 1991-06-07 1993-12-07 Ina Walzlager Schaeffler Kg Mechanical valve tappet for an internal combustion engine
DE4498820D2 (en) * 1993-11-12 1997-07-24 Schaeffler Waelzlager Kg Tappet for a valve train of an internal combustion engine
WO2005121383A1 (en) 2004-06-09 2005-12-22 Schaeffler Kg Heavy-duty engine component

Families Citing this family (14)

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Publication number Priority date Publication date Assignee Title
DE4117425C1 (en) * 1991-05-28 1992-07-30 Fa. Carl Freudenberg, 6940 Weinheim, De
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
US5249554A (en) * 1993-01-08 1993-10-05 Ford Motor Company Powertrain component with adherent film having a graded composition
US5237967A (en) * 1993-01-08 1993-08-24 Ford Motor Company Powertrain component with amorphous hydrogenated carbon film
DE4302877C2 (en) * 1993-02-02 1996-04-11 Schaeffler Waelzlager Kg Pestle
EP0618351B1 (en) * 1993-03-25 1997-08-06 Fuji Oozx Inc. Tappets for use in internal combustion engines
US5743224A (en) * 1993-09-14 1998-04-28 Unisia Jecs Corporation Valve lifter surface and processing method thereof
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.
KR100444566B1 (en) * 1999-12-27 2004-08-16 닛폰 피스톤 린구 가부시키가이샤 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

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GB1044692A (en) * 1964-02-18 1966-10-05 Daimler Benz Ag Improvements relating to cam devices

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Non-Patent Citations (3)

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Title
AUTOMOTIVE ENGINEERING, Band 94, Mai 1986, Seiten 40-45, Society of automotive Engineers, Inc., Dallas, Texas, US; "Valve gear materials: An overview" *
PATENT ABSTRACTS OF JAPAN, Band 11, Nr. 330 (M-636)[2777], 28. Oktober 1987; & JP-A-62 111 106 (HITACHI LTD) 22-05-1987 *
PATENT ABSTRACTS OF JAPAN, Band 9, Nr. 103 (M-377)[1826], 8. Mai 1985, Seite 153 M 377; & JP-A-59 229 009 (TOYOTA JIDOSHA K.K.) 22-12-1984 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0396288B1 (en) * 1989-04-20 1993-06-16 Eaton Engine Lifters Spa Hydraulic tappet
US5267538A (en) * 1991-06-07 1993-12-07 Ina Walzlager Schaeffler Kg Mechanical valve tappet for an internal combustion engine
DE4498820D2 (en) * 1993-11-12 1997-07-24 Schaeffler Waelzlager Kg Tappet for a valve train of an internal combustion engine
WO2005121383A1 (en) 2004-06-09 2005-12-22 Schaeffler Kg Heavy-duty engine component

Also Published As

Publication number Publication date
DE3809702A1 (en) 1989-10-05
DE58900604D1 (en) 1992-02-06
US4876996A (en) 1989-10-31
EP0334064B1 (en) 1991-12-27

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