FR2667112A1 - Valve-operating cam for an internal-combustion engine - Google Patents

Valve-operating cam for an internal-combustion engine Download PDF

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Publication number
FR2667112A1
FR2667112A1 FR9011658A FR9011658A FR2667112A1 FR 2667112 A1 FR2667112 A1 FR 2667112A1 FR 9011658 A FR9011658 A FR 9011658A FR 9011658 A FR9011658 A FR 9011658A FR 2667112 A1 FR2667112 A1 FR 2667112A1
Authority
FR
France
Prior art keywords
cam
valve
valve control
transmission member
width
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
FR9011658A
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French (fr)
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FR2667112B1 (en
Inventor
Delgado Antonio
Houdard Herve
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.)
Renault SAS
Regie Nationale des Usines Renault
Original Assignee
Renault SAS
Regie Nationale des Usines Renault
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Renault SAS, Regie Nationale des Usines Renault filed Critical Renault SAS
Priority to FR9011658A priority Critical patent/FR2667112B1/en
Publication of FR2667112A1 publication Critical patent/FR2667112A1/en
Application granted granted Critical
Publication of FR2667112B1 publication Critical patent/FR2667112B1/en
Anticipated expiration legal-status Critical
Expired - Fee Related 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
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/08—Shape of cams

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)

Abstract

Valve-operating cam for an internal-combustion engine, which the valve (2) is opened against the force of a spring (3) through the use of a transmission member (4) of the tappet, rocker, or rocker arm type, characterised in that the surface for contact with said transmission member exhibits zones of reduced width.

Description

AME DE 9011PADsUN MOIEUR A aOMBUSrION
INTERNE
La présente invention se rapporte aux moteurs à combustion interne, équipant notamment les véhicules automobiles, et elle concerne en particulier la configuration des cames commandant les soupapes de distribution.SOUL OF 9011PADs A BETTER AUSBUSRION
INTERNAL
The present invention relates to internal combustion engines, fitted in particular to motor vehicles, and it relates in particular to the configuration of the cams controlling the distribution valves.

Les moteurs à combustion interne à fonctionnement cyclique utilisent traditionnellement des distributions à soupapes commandées par des arbres à cames.Cyclically operated internal combustion engines traditionally use valve distributions controlled by camshafts.

Chaque soupape est ouverte contre la force d'un ressort par l'intermédiaire d'un organe de transmission disposé entre la came de commande et la soupape, organe de transmission qui peut être un poussoir, un culbuteur, un linguet....Each valve is opened against the force of a spring by means of a transmission member disposed between the control cam and the valve, a transmission member which can be a pusher, a rocker arm, a latch, etc.

Les accélérations élevées provoquées par la transformation du mouvement de rotation de la came en un mouvement alternatif à la soupape donnent naissance à des contraintes très importantes dans les organes de distribution, qui entraînent notamment un frottement élevé des organes coopérant la came et l'organe de transmission et ceci malgré la présence de lubrifiant. Ce frottement est source de consommation d'énergie et d'usure de pièces.The high accelerations caused by the transformation of the rotational movement of the cam into an alternative movement to the valve give rise to very high stresses in the distribution members, which in particular cause high friction of the members cooperating with the cam and the stop member. transmission, despite the presence of lubricant. This friction is a source of energy consumption and wear of parts.

Pour s'attaquer à ces causes de frottement on a particulièrement étudié le profil des cames, on peut citer par exemple la came "polydyne" mise au point par Dudley,
Thoren, Engemann et Stoddart. Cependant si le profil de la came permet de supprimer certaines sources de frottement, il ne peut supprimer le frottement hydrodynamique ou élasto hydrodynamique du lubrifiant. En effet le coefficient de frottement des organes en contact varie avec la viscosité du lubrifiant, la vitesse de glissement des organes coopérants, liée au régime moteur,et à la pression de Hertz. To tackle these causes of friction, we have particularly studied the profile of the cams, we can cite for example the "polydyne" cam developed by Dudley,
Thoren, Engemann and Stoddart. However, if the profile of the cam makes it possible to eliminate certain sources of friction, it cannot eliminate the hydrodynamic or elasto hydrodynamic friction of the lubricant. Indeed the coefficient of friction of the organs in contact varies with the viscosity of the lubricant, the sliding speed of the cooperating organs, linked to the engine speed, and to the Hertz pressure.

La présente invention vise à limiter les frottements excessifs entre la came et l'organe de transmission d'une manière simple et peu onéreuse et cela quelque soit la loi de came choisie.The present invention aims to limit excessive friction between the cam and the transmission member in a simple and inexpensive manner, regardless of the cam law chosen.

La came de commande de soupape d'un moteur à combustion interne selon l'invention ouvre la soupape contre la force d'un ressort par l'intermédiaire d'un organe de transmission de type : poussoir, linguet ou culbuteur.The valve control cam of an internal combustion engine according to the invention opens the valve against the force of a spring by means of a transmission member of the type: pusher, latch or rocker arm.

Selon l'invention cette came présente une surface de contact avec ledit organe de transmission comportant des zones de largeur réduite.According to the invention, this cam has a contact surface with said transmission member comprising areas of reduced width.

Selon une caractéristique de l'invention ces zones de largeur réduite correspondent à des zones où la pression de
Hertz entre la came et l'organe de transmission sont les plus faibles.According to a characteristic of the invention, these reduced width zones correspond to zones where the pressure of
Hertz between the cam and the transmission member are the weakest.

L'invention sera mieux comprise à l'étude de la description de plusieurs modes de réalisation de l'invention pris à titre nullement limitatifs et illustrés par le dessin annexé dans lequel: - la figure 1 représente la courbe de variation du
coefficient de frottement entre les organes coopérants; - la figure 2 est une vue en coupe partielle d'une culasse
équipée d'une came classique et d'une came selon
l'invention; - Les figures 3 à 6 représentent plusieurs surfaces
développées de cames suivant l'invention. The invention will be better understood on studying the description of several embodiments of the invention taken in no way limiting and illustrated by the appended drawing in which: - Figure 1 represents the variation curve of the
coefficient of friction between the cooperating members; - Figure 2 is a partial sectional view of a cylinder head
equipped with a conventional cam and a cam according to
the invention; - Figures 3 to 6 represent several surfaces
developed cams according to the invention.

La figure 1 montre l'évolution du coefficient de frottement
F entre la came et l'organe de transmission, en fonction de
S = V.N avec V la viscosité du lubrifiant, N le régime
P moteur et P la pression de Hertz.Figure 1 shows the evolution of the coefficient of friction
F between the cam and the transmission member, depending on
S = VN with V the viscosity of the lubricant, N the speed
P motor and P the Hertz pressure.

On distingue sur cette courbe schématiquement trois zones: - de O à A: zone de frottement et d'usure élevés, le
frottement est dit sec; - de A à B : zone de frottement faible et d'usure moyenne,
le frottement est élasto hydrodynamique; - à partir de B zone de frottement élevée et d'usure
faible, le frottement est hydrodynamique.There are three zones on this curve, schematically: - from O to A: high friction and wear zone, the
friction is said to be dry; - from A to B: low friction zone and medium wear,
friction is elasto hydrodynamic; - from B high friction and wear area
low, friction is hydrodynamic.

Au vue de la courbe on constate que pour une viscosité et un régime donnés le coefficient de frottement augmente dès qu'on s'éloigne en plus ou en moins d'une plage de pressions.In view of the curve, it can be seen that for a given viscosity and speed the coefficient of friction increases as soon as one moves away from it in more or less of a range of pressures.

I1 convient donc si on veut diminuer les frottements excessifs, de limiter les variations de pression de Hertz et en particulier les diminutions. Les pressions étant directement liées à la surface de contact de la came la régulation de la pression est obtenue par le travail de la surface de contact tout au long du profil de la came. It is therefore suitable if it is desired to reduce excessive friction, to limit the variations in Hertz pressure and in particular the decreases. The pressures being directly linked to the contact surface of the cam, the pressure regulation is obtained by working the contact surface all along the profile of the cam.

La figure 2 montre une came classique (1) de commande d'une soupape (2) d'un moteur à combustion interne non figuré. La came (1) ouvre la soupape (2) contre la force d'un ressort (3) par l'intermédiaire d'un linguet (4) monté dans la culasse (5). Figure 2 shows a conventional cam (1) for controlling a valve (2) of an internal combustion engine not shown. The cam (1) opens the valve (2) against the force of a spring (3) by means of a latch (4) mounted in the cylinder head (5).

Le profil de la came (1) comprend 4 secteurs principaux. Un premier secteur - circulaire (I) constituant le dos de la came (1) sur lequel repose le linguet quand la soupape (2) est fermée en appui sur son siège (6).The profile of the cam (1) comprises 4 main sectors. A first circular sector (I) constituting the back of the cam (1) on which the latch rests when the valve (2) is closed resting on its seat (6).

Un second secteur circulaire (IV) formant le "nez" de la came sur lequel appuie le linguet quand la soupape est ouverte.A second circular sector (IV) forming the "nose" of the cam on which the latch presses when the valve is open.

Deux rampes ou flancs (11, m) permettant de passer de l'un à l'autre des secteurs précédents.Two ramps or sides (11, m) allowing to pass from one to the other of the preceding sectors.

La répartition des pressions de Hertz le long de la came est la suivante : pressions faibles au dos de la came et pressions élevées au niveau des flancs et du nez. Pour ce qui est des flancs on distingue deux zones une première zone au voisinage du dos où les pressions sont maximales et une seconde zone au voisinage du nez où les pressions sont peu importantes.The distribution of Hertz pressures along the cam is as follows: low pressures at the back of the cam and high pressures at the sides and nose. As far as the sides are concerned, there are two zones: a first zone in the vicinity of the back where the pressures are maximum and a second zone in the vicinity of the nose where the pressures are low.

Le travail des surfaces de contact consiste donc à ajuster la largeur de la surface de la came en fonction des pressions. Cet ajustement s'opère notamment en réduisant cette largeur là où les contraintes sont minimales, d'où la came (7) suivant l'invention, présentant un dos de surface de contact réduit.The work of the contact surfaces therefore consists in adjusting the width of the surface of the cam as a function of the pressures. This adjustment takes place in particular by reducing this width where the stresses are minimal, hence the cam (7) according to the invention, having a reduced contact surface back.

Les figures 3 et 6 montrent différentes solutions mettant en oeuvre le principe de l'invention.Figures 3 and 6 show different solutions implementing the principle of the invention.

Les figures montrent uniquement la surface de contact des cames selon différents modes de réalisation. Ces surfaces sont présentées sous formes développées, les secteurs formant le nez étant positionnés au centre. Selon la figure 5 la surface de contact a été réduite uniformément le long du dos (I) de la came (1), comme la came (7) de la figure 2 et cette surface réduite s'étend au voisinage du centre de la came. Selon - la figure 6 la surface a été réduite au dos (I) de la came et dans les zones des flancs (II, III) au voisinage du nez (IV).The figures show only the contact surface of the cams according to different embodiments. These surfaces are presented in developed forms, the sectors forming the nose being positioned in the center. According to FIG. 5, the contact surface has been reduced uniformly along the back (I) of the cam (1), like the cam (7) of FIG. 2 and this reduced surface extends in the vicinity of the center of the cam. . According to - Figure 6 the surface has been reduced at the back (I) of the cam and in the areas of the sides (II, III) in the vicinity of the nose (IV).

La figure 3 montre une came similaire à celle de la figure 5 mais la surface réduite est décentrée et s'étend au voisinage de l'un des bords latéraux de la came. Cette disposition dissymétrique des surfaces de contact présente l'avantage supplémentaire, lorsque l'organe de transmission est un poussoir, d'entraîner la rotation du poussoir ce qui permet de répartir le frottement et donc l'usure sur une plus large surface. La figure 4 décrit un autre agencement permettant de déplacer les points d'appui de la came sur l'organe de transmission : les surfaces de moindre largeur évoluent d'un bord à l'autre en diagonale le long du dos.Figure 3 shows a cam similar to that of Figure 5 but the reduced surface is offset and extends in the vicinity of one of the side edges of the cam. This asymmetrical arrangement of the contact surfaces has the additional advantage, when the transmission member is a pusher, of causing the pusher to rotate, which makes it possible to distribute friction and therefore wear over a larger surface. FIG. 4 describes another arrangement making it possible to move the support points of the cam on the transmission member: the narrower surfaces move from one edge to the other diagonally along the back.

La réalisation de telles surfaces de came peut facilement être réalisée soit par une meule de rectifieuse profilée, soit directement par forgeage, moulage ou encore par frittage.The production of such cam surfaces can easily be carried out either by a profiled grinding wheel, or directly by forging, molding or even by sintering.

I1 est évident que l'invention n'est pas limitée aux réalisations décrites et qu'on peut y apporter d'autres variantes d'exécution.  It is obvious that the invention is not limited to the embodiments described and that other variant embodiments can be made to it.

Claims (3)

REVENDICATIONS de largeur réduite. avec ledit organe de transmission présente des zones culbuteur, caractérisé en ce que la surface de contact organe de transmission (4) de type poussoir, linguet ou la force d'un ressort (3) par l'intermédiaire d'un interne, par laquelle la soupape (2) est ouverte contreCLAIMS of reduced width. with said transmission member has rocker zones, characterized in that the contact surface of the transmission member (4) of the pusher, latch type or the force of a spring (3) via an internal, by which the valve (2) is open against [1] Came de commande de soupape d'un moteur à combustion[1] Valve control cam of a combustion engine faibles. weak. la came et l'organe de transmission sont les plus the cam and the transmission member are the most correspondent à des zones où la pression de Hertz entre correspond to areas where the Hertz pressure enters caractérisée en ce que les zones de largeur réduites characterized in that the reduced width zones [2] Came de commande de soupape selon la revendication 1[2] Valve control cam according to claim 1 le premier secteur circulaire ou "dos" (I). the first circular sector or "back" (I). que la largeur de la surface de contact est réduite dans that the width of the contact surface is reduced in desdits secteurs circulaires (I, IV), caractérisée en ce of said circular sectors (I, IV), characterized in that deux rampes (II, III) pour passer de l'un à l'autre two ramps (II, III) to go from one to the other l'organe de transmission quand la soupape est ouverte et the transmission member when the valve is open and secteur circulaire (IV), "le nez", sur lequel appuie circular sector (IV), "the nose", on which rests transmission quand la soupape est fermée, un second transmission when the valve is closed, a second circulaire (I), "le dos", sur lequel repose l'organe de circular (I), "the back", on which rests the subdivisé en plusieurs secteurs un premier secteur subdivided into several sectors a first sector revendications 1 à 2 le profil de la came étant claims 1 to 2 the profile of the cam being [3] Came de commande de soupape selon l'une quelconque des[3] Valve control cam according to any one of circulaire (IV).  circular (IV). rampes (II, III), au voisinage du second secteur ramps (II, III), in the vicinity of the second sector contact est réduite dans les secteurs constituant les contact is reduced in the sectors constituting the caractérisée en ce que la largeur de la surface de characterized in that the width of the surface of [4j Came de commande de soupape selon la revendication 3 [4d Valve control cam according to claim 3 médiane de la came. median of the cam. de moindre largeur s'étendent au voisinage de la partie narrower extend in the vicinity of the part revendications 1 à 4 caractérisée en ce que les surfaces claims 1 to 4 characterized in that the surfaces [5] Came de commande de soupape selon l'une quelconque des[5] Valve control cam according to any one of proximité de l'un des bords latéraux de la came. near one of the side edges of the cam. de moindre largeur sont excentrées et s'étendent à of lesser width are offset and extend to revendications 1 à 4 caractérisée en ce que les surfaces claims 1 to 4 characterized in that the surfaces [6] Came de commande de soupape selon l'une quelconque des[6] Valve control cam according to any one of l'organe de transmission.  the transmission organ. came de manière à déplacer la surface de frottement sur cam so as to move the friction surface on de moindre largeur évoluent d'un bord à l'autre de la of smaller width evolve from one edge to the other of the revendications 1 à 4 caractérisée en ce que les surfaces claims 1 to 4 characterized in that the surfaces [71 Came de commande de soupape selon l'une quelconque des [71 Valve control cam according to any one of
FR9011658A 1990-09-21 1990-09-21 VALVE CONTROL CAM OF AN INTERNAL COMBUSTION ENGINE. Expired - Fee Related FR2667112B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
FR9011658A FR2667112B1 (en) 1990-09-21 1990-09-21 VALVE CONTROL CAM OF AN INTERNAL COMBUSTION ENGINE.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR9011658A FR2667112B1 (en) 1990-09-21 1990-09-21 VALVE CONTROL CAM OF AN INTERNAL COMBUSTION ENGINE.

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FR2667112A1 true FR2667112A1 (en) 1992-03-27
FR2667112B1 FR2667112B1 (en) 1994-09-23

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008122653A1 (en) * 2007-04-10 2008-10-16 Mahle International Gmbh Cam for a camshaft or control shaft
EP2078830A3 (en) * 2008-01-10 2010-04-21 Aichi Machine Industry Co. Ltd. Camshaft and camshaft manufacturing method
GB2565581A (en) * 2017-08-17 2019-02-20 Jaguar Land Rover Ltd Improvements relating to cams for engines
GB2565582A (en) * 2017-08-17 2019-02-20 Jaguar Land Rover Ltd Improvements relating to cams for engines
DE102018212824A1 (en) * 2017-08-17 2019-06-19 Jaguar Land Rover Limited IMPROVEMENTS RELATED TO CAMS WITH ENGINES

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3241712A1 (en) * 1982-11-11 1984-05-17 Audi Nsu Auto Union Ag, 7107 Neckarsulm Cam shaft, in particular for the actuation of intake/exhaust valves on internal combustion engines
DE3309503A1 (en) * 1983-03-17 1984-09-20 Bayerische Motoren Werke AG, 8000 München Timing cam for valve-timing mechanisms of internal combustion engines
DE3444901A1 (en) * 1984-12-08 1986-06-12 Audi AG, 8070 Ingolstadt Cam control

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3241712A1 (en) * 1982-11-11 1984-05-17 Audi Nsu Auto Union Ag, 7107 Neckarsulm Cam shaft, in particular for the actuation of intake/exhaust valves on internal combustion engines
DE3309503A1 (en) * 1983-03-17 1984-09-20 Bayerische Motoren Werke AG, 8000 München Timing cam for valve-timing mechanisms of internal combustion engines
DE3444901A1 (en) * 1984-12-08 1986-06-12 Audi AG, 8070 Ingolstadt Cam control

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008122653A1 (en) * 2007-04-10 2008-10-16 Mahle International Gmbh Cam for a camshaft or control shaft
EP2078830A3 (en) * 2008-01-10 2010-04-21 Aichi Machine Industry Co. Ltd. Camshaft and camshaft manufacturing method
US7938091B2 (en) 2008-01-10 2011-05-10 Aichi Machine Industry Co., Ltd. Camshaft and camshaft manufacturing method
GB2565581A (en) * 2017-08-17 2019-02-20 Jaguar Land Rover Ltd Improvements relating to cams for engines
GB2565582A (en) * 2017-08-17 2019-02-20 Jaguar Land Rover Ltd Improvements relating to cams for engines
DE102018212824A1 (en) * 2017-08-17 2019-06-19 Jaguar Land Rover Limited IMPROVEMENTS RELATED TO CAMS WITH ENGINES
GB2565581B (en) * 2017-08-17 2020-03-18 Jaguar Land Rover Ltd Cam member with varying width

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