EP0504709A1 - Poppet valve drive - Google Patents

Poppet valve drive Download PDF

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Publication number
EP0504709A1
EP0504709A1 EP92104064A EP92104064A EP0504709A1 EP 0504709 A1 EP0504709 A1 EP 0504709A1 EP 92104064 A EP92104064 A EP 92104064A EP 92104064 A EP92104064 A EP 92104064A EP 0504709 A1 EP0504709 A1 EP 0504709A1
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EP
European Patent Office
Prior art keywords
valve drive
valve
cam
stop
camshaft
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Withdrawn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
EP92104064A
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German (de)
French (fr)
Inventor
Dieter Voigt
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Individual
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Individual
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Publication date
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Publication of EP0504709A1 publication Critical patent/EP0504709A1/en
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    • 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
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L1/053—Camshafts overhead type
    • 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
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • 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
    • 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
    • F01L1/26—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder
    • 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
    • F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
    • F02B2275/20—SOHC [Single overhead camshaft]
    • 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
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F1/42—Shape or arrangement of intake or exhaust channels in cylinder heads
    • F02F1/4214—Shape or arrangement of intake or exhaust channels in cylinder heads specially adapted for four or more valves per cylinder
    • 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
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F2001/244—Arrangement of valve stems in cylinder heads
    • F02F2001/245—Arrangement of valve stems in cylinder heads the valve stems being orientated at an angle with the cylinder axis

Definitions

  • the maintenance-free valve trains of modern series internal combustion engines are equipped with hydraulic lash adjusters, which automatically compensate for changes in length between the valve seat in the combustion chamber and the cam base circuit. For this purpose, they are spread in the longitudinal direction by springs and the oil pressure introduced and, if necessary, can also be shortened by means of defined leakage losses.
  • Orientation for the required length correction is carried out by contact of the valve drive element to be actuated (tappet, rocker arm, rocker arm) with the base circle area of the cam, whereby a certain minimum contact pressure is necessary for perfect functioning in the entire operating range of the machine.
  • the existing cam base circle contact in the hydraulic lash adjuster elements increases the friction in the valve train compared to conventional valve lashes, so that especially in multi-valve internal combustion engines there is a negative influence on fuel consumption.
  • the invention has for its object to provide a generic valve train that works with low wear and loss.
  • valve train according to the invention avoids the above-mentioned disadvantages in that the longitudinal orientation of the play compensation element no longer takes place on the rotating base circle region of the cam, but on a stationary stop for the valve train member.
  • the previous cam base circle area is practically meaningless and can therefore be omitted, which results in new designs for camshafts.
  • FIG. 1 the guide provided in the cylinder head 2 for the bucket tappet 3, which is relatively wide in this exemplary embodiment and contains two conventional hydraulic valve lash adjustment elements and is therefore not to be described.
  • the clearance compensation elements are connected via the bore 4 to the lubricating or cooling oil circuit of the reciprocating piston internal combustion engine, which is otherwise not shown. In this case, the elements are used for automatic play compensation of two lift valves, the shafts of which are indicated at 5 and 6.
  • valve closing springs 7 and 8 By the valve closing springs 7 and 8, the elements in the upward direction, ie. H. in the direction of the cam 10 carried by the camshaft 9, acted upon by force.
  • the camshaft 9 is held in split bearings, one bearing part being incorporated in the cylinder head 2 and the second bearing part being formed by the bridge 11 which is screwed onto the first bearing part.
  • Each bearing part forms a semicircular bearing shell, so that the parting plane formed by the surface 12 represents a plane of symmetry of the bearing.
  • each of the two valve stems 20 and 21 is assigned an individual bucket tappet 22 or 23 equipped with a hydraulic play compensation element; these in turn are under the effect of individual, differently designed cams 24 and 25 of the camshaft 26.
  • Both bucket tappets 22 and 23 have in common the mounted stop 27 provided between the cams 24 and 25, the effective surface 28 of which is selected so that it extends somewhat below the height of the base circle regions 29 and 30 of the cams 24 and 25 when the lift valves are closed .
  • FIG. 4 A similar construction is shown in FIG. 4, but with the difference that the two-part bearing 40 for the camshaft 41 with the cams 42 and 43 with its lower surface 44 in FIG. 4, and the upwardly facing surface 45 of the guide 46 for the two cup tappets 47 and 48 provided with play compensation elements coincide, forming the stop for them.
  • the contact between the tappets 47 and 48 on the one hand and the base circle regions of their cams 42 and 43 on the other hand is eliminated when the valves are closed.
  • camshaft construction according to FIG. 5 is also possible, the cam 50 of which has an area drawn in relative to the theoretical base circle 51, which area is used to accommodate a fastening element for the cam 50, here a hexagon head 52 of the screw 53. Understandably, other fastening options, for example by welding, soldering or gluing, are also possible for the cam 50 on the actual camshaft 54.
  • the rocker arm 62 which is provided with a hydraulic valve play compensation element 63, is used for power transmission between the cam 60 and the valve stem 61.
  • the lever 62 is supported on the stop 64 near the cam, so that a narrow gap 65 is maintained when the valve is closed.
  • bearings 73 which encompass the camshaft 70 in one piece and are screwed onto the cylinder head 72 by means of screws 74, are used to fasten the camshaft 70 to the flat surface 71 of the cylinder head 72.
  • the camshaft here has a constant diameter, at least in its area enclosed by the bearings 73 and the cams 75, which form separately manufactured components, so that the camshaft 70 can be fitted with the bearings 73 and the cams 75 by threading, as it were.
  • the longitudinal axis 76 of the valve drive member 77 extends obliquely to the plane surface 71.
  • a recess 79 is incorporated, the orientation of which corresponds to the orientation of the longitudinal axis 76 or the direction of movement of the valve drive element 77. This ensures a flat contact of the upper end face of the respective valve drive element on the stop face 78.
  • the invention accordingly provides a generic valve train which is optimized in terms of wear and efficiency without impairing its favorable properties.

Abstract

A poppet valve drive contains a cam (10) with a base circle region (19) and a hydraulic valve clearance compensating element in a valve drive member (3) with a bearing surface (14) for the cam (10). In order to avoid disadvantageous contact between the bearing surface (14) and the base circle region (13) during the phases in which the compensating element is being adjusted, the valve drive member is assigned a stop (15, 16) which is effective during these phases. <IMAGE>

Description

Die wartungsfreien Ventiltriebe moderner Serien-Brennkraftmaschinen sind mit hydraulischen Spielausgleichselementen bestückt, die auftretende Längenänderungen zwischen dem im Brennraum befindlichen Ventilsitz und dem Nockengrundkreis selbsttätig ausgleichen. Hierzu werden sie durch Federn und den eingeleiteten Öldruck in Längsrichtung gespreizt und können über definierte Leckageverluste bei Bedarf auch Verkürzungen realisieren.The maintenance-free valve trains of modern series internal combustion engines are equipped with hydraulic lash adjusters, which automatically compensate for changes in length between the valve seat in the combustion chamber and the cam base circuit. For this purpose, they are spread in the longitudinal direction by springs and the oil pressure introduced and, if necessary, can also be shortened by means of defined leakage losses.

Die Orientierung für die jeweils erforderliche Längenkorrektur erfolgt durch Kontakt des zu betätigenden Ventiltriebsgliedes (Stößel, Kipphebel, Schlepphebel) mit dem Grundkreisbereich des Nockens, wobei eine gewisse Mindestanpreßkraft für eine einwandfreie Funktion im gesamten Betriebsbereich der Maschine nötig ist.Orientation for the required length correction is carried out by contact of the valve drive element to be actuated (tappet, rocker arm, rocker arm) with the base circle area of the cam, whereby a certain minimum contact pressure is necessary for perfect functioning in the entire operating range of the machine.

Aufgrund der theoretischen Linienberührung zwischen dem Nockengrundkreisbereich und dem zu betätigenden Ventiltriebsglied treten dabei relativ hohe Flächenpressungen auf, die insbesondere am Ventiltriebsglied Maßnahmen gegen Verschleiß erfordern. Auch darf der rotierende Nockengrundkreisbereich als Orientierungskontur für das Spielausgleichselement keinen Schlag aufweisen.Due to the theoretical line contact between the cam base circle area and the valve drive element to be actuated, relatively high surface pressures occur which require measures against wear, in particular on the valve drive element. Also, the rotating cam base circle area as an orientation contour for the play compensation element must not have any impact.

Der bei den hydraulischen Spielausgleichselementen vorhandene Nockengrundkreiskontakt erhöht gegenüber herkömmlichen, spielbehafteten Ventiltrieben die Reibung im Ventiltrieb, so daß insbesondere bei vielventiligen Brennkraftmaschinen ein negativer Einfluß auf den Kraftstoffverbrauch gegeben ist.The existing cam base circle contact in the hydraulic lash adjuster elements increases the friction in the valve train compared to conventional valve lashes, so that especially in multi-valve internal combustion engines there is a negative influence on fuel consumption.

Der Erfindung liegt die Aufgabe zugrunde, einen gattungsgemäßen Ventiltrieb zu schaffen, der verschleiß- und verlustarm arbeitet.The invention has for its object to provide a generic valve train that works with low wear and loss.

Die erfindungsgemäße Aufgabenlösung besteht in den kennzeichnenden Merkmalen des Hauptanspruchs, vorteilhafte Ausführungen beschreiben die Unteransprüche.The task solution according to the invention consists in the characterizing features of the main claim, advantageous embodiments describe the subclaims.

Der erfindungsgemäße Ventiltrieb vermeidet die vorgenannten Nachteile, indem die Längsorientierung des Spielausgleichselementes nicht mehr am rotierenden Grundkreisbereich des Nockens, sondern an einem ruhenden Anschlag für das Ventiltriebsglied erfolgt. Der bisherige Nockengrundkreisbereich wird praktisch bedeutungslos und kann somit entfallen, wodurch sich neue Gestaltungen für Nockenwellen ergeben.The valve train according to the invention avoids the above-mentioned disadvantages in that the longitudinal orientation of the play compensation element no longer takes place on the rotating base circle region of the cam, but on a stationary stop for the valve train member. The previous cam base circle area is practically meaningless and can therefore be omitted, which results in new designs for camshafts.

Mehrere Ausführungsbeispiele der Erfindung werden im folgenden anhand der Zeichnung erläutert. Es zeigen:

  • Figur 1 einen Querschnitt durch den hier interessierenden Bereich des Zylinderkopfs einer Kraftfahrzeug-Brennkraftmaschine,
  • Figur 2 einen teilweisen Längsschnitt durch den interessierenden Bereich eines Zylinderkopfes,
  • Figur 3 die Draufsicht zu Figur 2,
  • Figur 4 ein anderes Ausführungsbeispiel der Erfindung im Längsschnitt,
  • Figur 5 einen Querschnitt durch eine im Rahmen der Erfindung zu verwendende Nockenwellenkonstruktion,
  • Figur 6 eine Realisierung der Erfindung bei einem Kipphebel und
  • Figur 7 einen Querschnitt durch ein weiteres Ausführungsbeispiel.
Several embodiments of the invention are explained below with reference to the drawing. Show it:
  • 1 shows a cross section through the region of interest of the cylinder head of a motor vehicle internal combustion engine,
  • FIG. 2 shows a partial longitudinal section through the region of interest of a cylinder head,
  • FIG. 3 shows the top view of FIG. 2,
  • FIG. 4 shows another embodiment of the invention in longitudinal section,
  • FIG. 5 shows a cross section through a camshaft construction to be used in the context of the invention,
  • Figure 6 shows an implementation of the invention in a rocker arm and
  • Figure 7 shows a cross section through a further embodiment.

Betrachtet man zunächst Figur 1, so erkennt man bei 1 die im Zylinderkopf 2 vorgesehene Führung für den in diesem Ausführungsbeispiel relativ breiten, zwei übliche hydraulische Ventilspielausgleichselemente enthaltenden Tassenstößel 3 bekannten und daher nicht zu beschreibenden Aufbaus. Über die Bohrung 4 sind die Spielausgleichselemente an den Schmier- bzw. Kühlölkreislauf der im übrigen nicht dargestellten Hubkolbenbrennkraftmaschine angeschlossen. In diesem Fall dienen die Elemente zum selbsttätigen Spielausgleich von zwei Hubventilen, deren Schäfte bei 5 und 6 angedeutet sind.Looking first at FIG. 1, one can see at 1 the guide provided in the cylinder head 2 for the bucket tappet 3, which is relatively wide in this exemplary embodiment and contains two conventional hydraulic valve lash adjustment elements and is therefore not to be described. The clearance compensation elements are connected via the bore 4 to the lubricating or cooling oil circuit of the reciprocating piston internal combustion engine, which is otherwise not shown. In this case, the elements are used for automatic play compensation of two lift valves, the shafts of which are indicated at 5 and 6.

Durch die Ventilschließfedern 7 und 8 sind die Elemente in Richtung nach oben, d. h. in Richtung auf den von der Nockenwelle 9 getragenen Nocken 10, kraftbeaufschlagt. Die Nockenwelle 9 ist in geteilten Lagern gehalten, wobei ein Lagerteil in den Zylinderkopf 2 eingearbeitet ist und der zweite Lagerteil durch die Brücke 11 gebildet wird, die an den ersten Lagerteil angeschraubt ist. Jeder Lagerteil bildet eine halbkreisförmige Lagerschale, so daß die durch die Fläche 12 gebildete Teilungsebene eine Symmetrieebene des Lagers darstellt.By the valve closing springs 7 and 8, the elements in the upward direction, ie. H. in the direction of the cam 10 carried by the camshaft 9, acted upon by force. The camshaft 9 is held in split bearings, one bearing part being incorporated in the cylinder head 2 and the second bearing part being formed by the bridge 11 which is screwed onto the first bearing part. Each bearing part forms a semicircular bearing shell, so that the parting plane formed by the surface 12 represents a plane of symmetry of the bearing.

In der dargestellten Lage des Nockens 10 ist angenommen, daß sich die Ventile in Schließstellung befinden; wie erkennbar, steht der Nocken 10 mit seinem Grundkreisbereich 13 der Auflagefläche 14 des Tassenstößels 3 gegenüber. In Abweichung vom Stand der Technik besteht jedoch jetzt kein Kontakt zwischen dem Grundkreisbereich 13 und der Auflage 14, da sich der Tassenstößel 3 an in diesem Ausführungsbeispiel zwei angeschraubten Anschlägen 15 und 16 abstützt, deren wirksame Flächen 17 und 18 in Höhe der Fläche 12 verlaufen. Die Auflagefläche 14 ist in Bezug auf die Anschläge 15 und 16 so gelegt, daß zwischen ihr und dem Grundkreisbereich 13 des Nockens 10 ein kleiner Spalt 19 verbleibt, also während der Schließphase der Ventile und damit während des Einstellvorgangs der Spielausgleichselemente kein Verschleiß und Leistungsverlust hervorrufender Kontakt zwischen Nocken und Tassenstößel 3 vorhanden ist. Da dieser Spalt nur klein ist und die Mittelebene der Nockenwelle 9, d. h. die Fläche 12, zusammenfällt mit den wirksamen Anschlagsflächen 17 und 18, ergibt sich trotz dieser Vermeidung eines Kontakts zwischen der Auflagefläche 14 einerseits und dem Grundkreisbereich 13 des Nockens andererseits für die Orientierung des Spielausgleichselements eine relativ genaue Simultation der Verhältnisse, die beim Stand der Technik durch die Heranziehung des Nockengrundkreisbereichs als Anschlagfläche vorliegen.In the position of the cam 10 shown, it is assumed that the valves are in the closed position; as can be seen, the cam 10 with its base circle region 13 faces the contact surface 14 of the tappet 3. In deviation from the prior art, however, there is now no contact between the base circle region 13 and the support 14, since the cup tappet 3 is supported on two screwed-on stops 15 and 16 in this exemplary embodiment, the effective surfaces 17 and 18 of which extend at the surface 12. The bearing surface 14 is placed in relation to the stops 15 and 16 so that a small gap 19 remains between it and the base circle region 13 of the cam 10, i.e. during the closing phase of the valves and thus during the adjustment process of the play compensation elements, there is no contact causing wear and loss of power between cam and tappet 3 is present. Since this gap is only small and the central plane of the camshaft 9, i. H. the surface 12, which coincides with the effective stop surfaces 17 and 18, results in a relatively precise simulation of the conditions in the prior art, despite this avoidance of contact between the bearing surface 14 on the one hand and the base circle region 13 of the cam on the other hand for the orientation of the play compensation element the use of the cam base circle area is available as a stop surface.

Die Konstruktion nach Figur 2 vermeidet derartige hochliegende Anschläge ("Obenführung"), die bei üblichen in Draufsicht runden Spielausgleichselementen mit relativ geringem Durchmesser schwer unterzubringen sind. In der Konstruktion nach Figur 2 ist jedem der beiden Ventilschäfte 20 und 21 ein individueller, mit einem hydraulisches Spielausgleichselement bestückter Tassenstößel 22 bzw. 23 zugeordnet; diese wiederum stehen unter der Wirkung individueller, unterschiedlich ausgebildeter Nocken 24 und 25 der Nockenwelle 26.The construction according to FIG. 2 avoids such high-lying stops ("top guide"), which are difficult to accommodate with conventional clearance compensation elements with a relatively small diameter which are round in plan view. In the construction according to FIG. 2, each of the two valve stems 20 and 21 is assigned an individual bucket tappet 22 or 23 equipped with a hydraulic play compensation element; these in turn are under the effect of individual, differently designed cams 24 and 25 of the camshaft 26.

Beiden Tassenstößeln 22 und 23 gemeinsam ist der zwischen den Nocken 24 und 25 vorgesehene montierte Anschlag 27, wobei dessen wirksame Fläche 28 so gewählt ist, daß sie etwas unter der Höhe der Grundkreisbereiche 29 und 30 der Nocken 24 und 25 im geschlossenen Zustand der Hubventile verläuft.Both bucket tappets 22 and 23 have in common the mounted stop 27 provided between the cams 24 and 25, the effective surface 28 of which is selected so that it extends somewhat below the height of the base circle regions 29 and 30 of the cams 24 and 25 when the lift valves are closed .

Eine ähnliche Konstruktion zeigt Figur 4, jedoch mit dem Unterschied, daß das zweigeteilte Lager 40 für die Nockenwelle 41 mit den Nocken 42 und 43 mit seiner in Figur 4 unteren Fläche 44, die mit der nach oben weisenden Fläche 45 der Führung 46 für die beiden mit Spielausgleichselementen versehenen Tassenstößel 47 und 48 zusammenfällt, den Anschlag für diese bildet. Auch hier ist demgemäß der Berührungskontakt zwischen den Tassenstößeln 47 und 48 einerseits und den Grundkreisbereichen ihrer Nocken 42 und 43 andererseits bei geschlossenen Ventilen aufgehoben.A similar construction is shown in FIG. 4, but with the difference that the two-part bearing 40 for the camshaft 41 with the cams 42 and 43 with its lower surface 44 in FIG. 4, and the upwardly facing surface 45 of the guide 46 for the two cup tappets 47 and 48 provided with play compensation elements coincide, forming the stop for them. Here, too, the contact between the tappets 47 and 48 on the one hand and the base circle regions of their cams 42 and 43 on the other hand is eliminated when the valves are closed.

Im Hinblick auf diesen Tatbestand ist auch eine Nockenwellenkonstruktion gemäß Figur 5 möglich, deren Nocken 50 einen gegenüber dem theoretischen Grundkreis 51 eingezogenen Bereich besitzt, der zur Unterbringung eines Befestigungselements für den Nocken 50, hier eines Sechskantkopfes 52 der Schraube 53, ausgenutzt wird. Verständlicherweise sind auch andere Befestigungsmöglichkeiten, beispielsweise durch Schweißen, Löten oder Kleben, für den Nocken 50 an der eigentlichen Nockenwelle 54 möglich.In view of this fact, a camshaft construction according to FIG. 5 is also possible, the cam 50 of which has an area drawn in relative to the theoretical base circle 51, which area is used to accommodate a fastening element for the cam 50, here a hexagon head 52 of the screw 53. Understandably, other fastening options, for example by welding, soldering or gluing, are also possible for the cam 50 on the actual camshaft 54.

In Figur 6 dient zur Kraftübertragung zwischen Nocken 60 und Ventilschaft 61 der Kipphebel 62, der mit einem hydraulischen Ventilspielausgleichselement 63 versehen ist. Während Grundkreisphasen des Nockens 60 stützt sich der Hebel 62 an dem nockennahen Anschlag 64 ab, so daß ein schmaler Spalt 65 bei geschlossenem Ventil gewahrt ist.In FIG. 6, the rocker arm 62, which is provided with a hydraulic valve play compensation element 63, is used for power transmission between the cam 60 and the valve stem 61. During base circle phases of the cam 60, the lever 62 is supported on the stop 64 near the cam, so that a narrow gap 65 is maintained when the valve is closed.

In dem Ausführungsbeispiel nach Figur 7 schließlich dienen zur Befestigung der Nockenwelle 70 an der Planfläche 71 des Zylinderkopfes 72 die Nockenwelle 70 einteilig umgreifende Lager 73, die mittels Schrauben 74 am Zylinderkopf 72 festgeschraubt sind. Die Nockenwelle besitzt hier zumindest in ihrem von den Lagern 73 und den Nocken 75, die gesondert gefertigte Bauteile bilden, umschlossenen Bereich einen konstanten Durchmesser, so daß die Nockenwelle 70 mit den Lagern 73 und den Nocken 75 gleichsam durch Auffädeln bestückt werden kann.Finally, in the exemplary embodiment according to FIG. 7, bearings 73, which encompass the camshaft 70 in one piece and are screwed onto the cylinder head 72 by means of screws 74, are used to fasten the camshaft 70 to the flat surface 71 of the cylinder head 72. The camshaft here has a constant diameter, at least in its area enclosed by the bearings 73 and the cams 75, which form separately manufactured components, so that the camshaft 70 can be fitted with the bearings 73 and the cams 75 by threading, as it were.

In diesem Ausführungsbeispiel ist angenommen, daß die Längsachse 76 des Ventiltriebsglieds 77 schräg zur Planfläche 71 verläuft. Zur Bildung des Anschlags 78 für ein Ventiltriebsglied, daß in Figur 7 vor der Zeichenebene liegt, und entsprechend auch für das hinter der Zeichenebene liegende Ventiltriebsglied 77 ist an der Unterseite des einteiligen Lagers 73, d. h. unterhalb des Verlaufs der Nockenwelle 70, eine Vertiefung 79 eingearbeitet, deren Ausrichtung der Ausrichtung der Längsachse 76 bzw. der Bewegungsrichtung des Ventiltriebsglieds 77 entspricht. Dadurch wird eine flächige Auflage der oberen Stirnfläche des jeweiligen Ventiltriebsglieds auf der Anschlagfläche 78 sichergestellt.In this exemplary embodiment, it is assumed that the longitudinal axis 76 of the valve drive member 77 extends obliquely to the plane surface 71. To form the stop 78 for a valve drive member that lies in front of the drawing plane in FIG. 7, and accordingly also for the valve drive member 77 lying behind the drawing plane, on the underside of the one-piece bearing 73, i. H. Below the course of the camshaft 70, a recess 79 is incorporated, the orientation of which corresponds to the orientation of the longitudinal axis 76 or the direction of movement of the valve drive element 77. This ensures a flat contact of the upper end face of the respective valve drive element on the stop face 78.

Verständlicherweise ist es auch möglich, eine senkrecht zur Ebene der Figur 4 weisende durchgehende Ausnehmung 79 zur Bildung von Anschlägen für zwei in dieser Richtung aufeinanderfolgende Ventiltriebsglieder vorzusehen.Understandably, it is also possible to provide a continuous recess 79 pointing perpendicular to the plane of FIG. 4 to form stops for two valve drive elements which follow one another in this direction.

Diese Ausführungsformen der Erfindung bietet eine Reihe von Vorteilen: So sind Herstellung und Bearbeitung des einteiligen Lagers vereinfacht, Zentrierschrauben für die Lagerbefestigung am Zylinderkopf können entfallen, und schließlich können die Nockenwelle, die Lager, die Nocken und die Anschläge für die Ventiltriebsglieder zu einer Vormontageeinheit zusammengefaßt werden. Ergänzend sei darauf hingewiesen, daß infolge Fehlens einer Lagertrennfuge auch die Lagerfunktionssicherheit verbessert ist.These embodiments of the invention offer a number of advantages: production and machining of the one-piece bearing are simplified, centering screws for the bearing attachment on the cylinder head can be omitted, and finally the camshaft, the bearings, the cams and the stops for the valve drive elements can be combined to form a pre-assembly unit will. In addition, it should be noted that also due to the lack of a bearing joint the warehouse functional reliability is improved.

Mit der Erfindung ist demgemäß ein gattungsgemäßer Ventiltrieb geschaffen, der ohne Beeinträchtigung der günstigen Eigenschaften desselben hinsichtlich Verschleiß und Wirkungsgrad optimiert ist.The invention accordingly provides a generic valve train which is optimized in terms of wear and efficiency without impairing its favorable properties.

Claims (9)

Ventiltrieb für ein Hubventil, insbesondere ein Ladungswechselventil einer Brennkraftmaschine, mit zumindest einem das Ventil über ein Ventiltriebsglied mit einem hydraulischen Spielausgleichselement entgegen der Kraft einer Ventilfeder betätigenden Nocken, dadurch gekennzeichnet, daß ein ruhender Anschlag (15, 16) für das Ventiltriebsglied (3) vorgesehen ist, an dem sich dieses während der Grundkreisphase des Nockens (10) unter Wahrung eines Spalts (19) zum Nockengrundkreisbereich (13) abstützt.Valve train for a lift valve, in particular a charge exchange valve of an internal combustion engine, with at least one cam actuating the valve via a valve drive member with a hydraulic lash adjuster against the force of a valve spring, characterized in that a stationary stop (15, 16) is provided for the valve drive member (3) on which this is supported during the base circle phase of the cam (10) while maintaining a gap (19) to the cam base circle area (13). Ventiltrieb nach Anspruch 1, dadurch gekennzeichnet, daß bei einem Tassenstößel (3) als Ventiltriebsglied der Anschlag (44) durch ein Lager (40) für eine den Nocken (42, 43) tragende Nockenwelle (41) gebildet ist.Valve drive according to Claim 1, characterized in that, in the case of a bucket tappet (3) as the valve drive member, the stop (44) is formed by a bearing (40) for a camshaft (41) carrying the cams (42, 43). Ventiltrieb nach Anspruch 1, dadurch gekennzeichnet, daß bei einem Tassenstößel (22, 23) als Ventiltriebsglied der Anschlag durch ein scheibenähnliches Bauteil (27) gebildet ist.Valve drive according to Claim 1, characterized in that in the case of a bucket tappet (22, 23) as the valve drive member, the stop is formed by a disk-like component (27). Ventiltrieb nach Anspruch 2 oder 3, dadurch gekennzeichnet, daß ein Anschlag (27) zwei einander benachbarten Ventiltriebsgliedern (22, 23) gemeinsam ist.Valve train according to claim 2 or 3, characterized in that a stop (27) is common to two adjacent valve train members (22, 23). Ventiltrieb nach einem der Ansprüche 2 bis 4, dadurch gekennzeichnet, daß bei einem mehreren Ventilen gemeinsamen, in Draufsicht länglichen Tassenstößel (3) diesem zwei Anschläge (15, 16) in vorzugsweise symmetrischer Anordnung zugeordnet sind.Valve drive according to one of claims 2 to 4, characterized in that in the case of a plurality of valves common cup tappet (3) which is elongated in plan view, two stops (15, 16) are assigned to it, preferably in a symmetrical arrangement. Ventiltrieb nach Anspruch 1, dadurch gekennzeichnet, daß bei einem Ventiltriebsglied nach Art eines Schlepp- oder Kipphebels (62) der Anschlag (64) an einer nockennahen Stelle liegt.Valve drive according to claim 1, characterized in that in the case of a valve drive member in the manner of a rocker arm or rocker arm (62), the stop (64) lies at a point close to the cam. Ventiltrieb nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß der Nocken (50) einen eingezogenen Grundkreisbereich besitzt.Valve train according to one of claims 1 to 6, characterized in that the cam (50) has a retracted base circle region. Ventiltrieb nach Anspruch 2 oder 4, dadurch gekennzeichnet, daß das Lager (73) zur Bildung des Anschlags in einem die Nockenwelle (70) untergreifenden Bereich zur teilweisen Aufnahme des Ventiltriebsglieds (77) während der Grundkreisphasen des Nockens (75) eine Vertiefung (79) besitzt, die in Bewegungsrichtung des Ventiltriebsglieds (77) ausgerichtet ist.Valve drive according to claim 2 or 4, characterized in that the bearing (73) for forming the stop in an area under the camshaft (70) for partially receiving the valve drive member (77) during the base circle phases of the cam (75) has a recess (79) has, which is aligned in the direction of movement of the valve drive member (77). Ventiltrieb nach Anspruch 8, dadurch gekennzeichnet, daß bei einer nachträglich mit Nocken (75) bestückten Nockenwelle (70), deren Durchmesser im Bereich der Nocken (75) und der Lager (73) konstant ist, zumindest einzelne Lager (73) die Nockenwelle (70) einteilig umschließend ausgebildet sind, so daß Nockenwelle (70), Nocken (75), Lager (73) und Anschläge (78) eine Vormontageeinheit bilden.Valve drive according to claim 8, characterized in that in the case of a camshaft (70) subsequently fitted with cams (75), the diameter of which is constant in the area of the cams (75) and the bearings (73), at least individual bearings (73) have the camshaft ( 70) are formed in one piece, so that camshaft (70), cam (75), bearing (73) and stops (78) form a pre-assembly unit.
EP92104064A 1991-03-13 1992-03-10 Poppet valve drive Withdrawn EP0504709A1 (en)

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DE4108051 1991-03-13
DE4108051 1991-03-13

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