EP0287425B1 - Method for moulding a rocker arm for internal combustion engine and mould structure for executing the moulding procedure - Google Patents

Method for moulding a rocker arm for internal combustion engine and mould structure for executing the moulding procedure Download PDF

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Publication number
EP0287425B1
EP0287425B1 EP88400791A EP88400791A EP0287425B1 EP 0287425 B1 EP0287425 B1 EP 0287425B1 EP 88400791 A EP88400791 A EP 88400791A EP 88400791 A EP88400791 A EP 88400791A EP 0287425 B1 EP0287425 B1 EP 0287425B1
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EP
European Patent Office
Prior art keywords
reinforcing element
rocker arm
pusher
spindle
forming
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
EP88400791A
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German (de)
French (fr)
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EP0287425A1 (en
Inventor
Jean Dupin
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.)
Automobiles Peugeot SA
Automobiles Citroen SA
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Automobiles Peugeot SA
Automobiles Citroen SA
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Publication of EP0287425A1 publication Critical patent/EP0287425A1/en
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Classifications

    • 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
    • F02F7/00—Casings, e.g. crankcases or frames
    • F02F7/0085—Materials for constructing engines or their parts
    • F02F7/0087—Ceramic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/22—Dies; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
    • B22D17/24—Accessories for locating and holding cores or inserts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D19/00—Casting in, on, or around objects which form part of the product
    • 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
    • F01L1/18—Rocking arms or levers
    • F01L1/181—Centre pivot rocking arms
    • 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
    • F01L2303/00—Manufacturing of components used in valve arrangements
    • 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
    • F01L2303/00—Manufacturing of components used in valve arrangements
    • F01L2303/01—Tools for producing, mounting or adjusting, e.g. some part of the distribution

Definitions

  • the present invention relates to a method of molding a rocker arm for an internal combustion engine according to the preamble of claim 1 and a mold structure for the implementation of such a method according to the preamble of claim 3.
  • Rockers of the type comprising a lever body comprising a first branch cooperating with a cam of an engine camshaft and a second branch cooperating with a valve stem, the lever body, of light alloy, being produced by a pressure shell molding process.
  • the branch cooperating with the cam has an extremely hard reinforcement element resistant to wear by friction with the cam and inserted during casting in the light alloy rocker arm.
  • the reinforcing element is made of sintered material, carbide or special cast iron.
  • the above materials constituting the reinforcing element have not always been entirely satisfactory, thus leading manufacturers to use ceramic reinforcing elements having better wear behavior than the metallic materials mentioned above, provided that the friction surface of the reinforcing element is close to the "mirror polish".
  • the polish of the friction surface of the reinforcing element is obtained according to a known method before the positioning of the latter in the rocker arm, which means that the reinforcing element will not be machined after casting or molding the rocker arm. All machining of the rocker arm will therefore be carried out starting from the reinforcing element.
  • the ceramic reinforcing element is extremely hard and fragile and non-magnetic, it is necessary to hold it firmly in the mold without risk of breaking.
  • the pads obtained after "mirror-polished" machining cannot have absolutely identical dimensions, it is necessary to provide a device which makes it possible to compensate for the differences in dimensions of the pads.
  • DE-A-35 20 484 describes a method of molding a rocker arm, one of the branches of which comprises a ceramic reinforcing element which is secured to it during the molding operation.
  • the reinforcing element is arranged on a thermally insulating element also made of ceramic.
  • the reinforcing element is brought to a temperature corresponding to the melting temperature of the material used to pour the rocker arm and the insulating element has the function of avoiding any heat loss between the reinforcing element and the mold.
  • This earlier application also mentions that it is known to fix the reinforcing element in the mold during the operation of molding the rocker arm.
  • the reinforcing element is fixed in the mold by means of the insulating element having an appropriate shape complementary to that of the curved lower part of the reinforcing element.
  • the insulating element does not allow the reinforcement element to be held firmly in the mold and it is necessary to provide several insulating elements to take account of the differences in dimensions of the reinforcement elements.
  • the present invention solves the above problems by proposing a method of molding a rocker arm for an internal combustion engine, characterized in that it consists in firmly holding the ceramic reinforcing element, the friction surface of which with the cam is previously polished, in the mold at least during the molding operation of the rocker arm by a spindle member in forced support on the end of the reinforcing element opposite to the friction surface thereof.
  • a protruding part of the branch of the rocker arm cooperating with the cam opposite the reinforcement element and comprising a surface which is preferably flat, perpendicular to the axis. longitudinal of the reinforcing element.
  • the mold structure for implementing the method defined above, of the type comprising two upper and lower half-molds, is characterized in that it comprises a device for holding the reinforcing element in one of the half-molds, comprising the aforementioned spindle part disposed on the end of the reinforcement element and a pusher assembly above the spindle part to maintain the latter in forced support on the reinforcement element.
  • the pusher assembly comprises an elongated pusher in the extension of the part forming spindle, an elastic pre-stressed return means bearing on the elongated pusher and a member for prestressing the elastic means secured to the half-mold.
  • the aforementioned elastic return means makes it possible to compensate for the size differences between two pads.
  • the molding structure 1 for the die casting of the light alloy constituting the rocker includes two upper and lower half-molds only the lower mold 2 being visible in the figure.
  • Reference 3 designates a ceramic reinforcing element which must be secured, after molding, to the branch of the lever body of the rocker arm cooperating with a cam of an internal combustion engine cam shaft.
  • This reinforcing element comprises a rubbing surface 3a intended to cooperate with the cam and previously polished according to a known method.
  • This rubbing surface has a convex or convex shape fitting into a corresponding cavity 2a of the lower half-mold 2.
  • the reinforcing element 3 further comprises a part forming an anchoring tail 3b of the element at the end of the branch of the rocker arm cooperating with the cam and situated opposite the friction surface 3a.
  • a device forming a pusher 4 exerts a thrust on a part forming a spindle 5 so as to maintain it in forced support on the part forming an anchor tail 3b of the reinforcing element 3.
  • the part forming a spindle 5 located in the longitudinal axis of the reinforcing element 3 is preferably of circular cross section, it being understood that any other shape of section (oval-rectangular-etc ...) is suitable.
  • the pusher device 4 comprises from bottom to top relative to FIG. 1 and along the longitudinal axis of the reinforcing element 3 an elongated pusher 4a, the lower end of which bears on the upper part of the part forming spindle 5 and carrying at its upper end a head 4a1, an elastic prestressed return means 4b bearing on the head 4a1 of the elongated plunger and a prestressing member 4c of the elastic means 4b, the member 4c being movable and slipping off at when the mold is opened.
  • the prestressing member 4c can be formed by a screw or any other mechanical means for adjusting the prestressing of the elastic means 4b which can be formed by a compression spring or by elastic steel washers of the Belleville type.
  • the prestressing member 4c, the elastic return means 4b and the head 4a1 of the pusher 4a are housed in a bore 4d of the lower half-mold 2 while the elongated part of the pusher 4a passes through a further bore 4e smaller diameter than that of bore 4d starting from the bottom of the latter and opening into the hollow of the mold, the lower end of the elongated part projecting into the hollow of the mold.
  • the pusher assembly 4 maintains forced support of the spindle portion 5 on the reinforcing element 3 which is thus firmly held in the cavity 2a of the lower half-mold 2.
  • FIG. 1 also shows the presence of a flat wall 1a produced in the hollow of the lower half-mold 2 perpendicular to the longitudinal axis of the reinforcing element 3, the bore 4e emerging through this wall.
  • the wall 1a is connected to the curved wall defining the upper end of the branch of the rocker arm cooperating with the cam by a flat wall 1b.
  • the part forming an anchor tail 3b of the reinforcing element 3 will be embedded with the pin-forming part 5 in the material of the rocker arm (see FIG. 2 ), which spindle part 5 will be of sufficient diameter to withstand the shocks resulting from the arrival of the material injected under pressure.
  • FIG. 3 represents the rocker arm 6 obtained after molding.
  • the rocker body comprises the branch 6a cooperating with the stem of a valve and the branch 6b cooperating with the cam of a camshaft and provided at its lower end with the ceramic reinforcing element 3.
  • the reference 6c denotes the projecting part from molding obtained from the walls 1a and 1b of the half-mold 2.
  • This projecting part mainly comprises a flat surface 6c1 situated opposite the reinforcing element 3 perpendicularly to the longitudinal axis thereof.
  • the spindle part was extracted during molding by conventional extractor devices not shown. There remains a hole delimited by the dotted lines and overhung by an orifice 6d opening onto the surface 6c1, which orifice was defined during molding by the lower end part of the elongated pusher 4a.
  • the presence of the flat surface 6c1 has the advantage of facilitating the holding in position of the rocker arm 6 during its machining.
  • This positioning is obtained by first placing the rubbing surface 3a of the reinforcing element 3 on a corresponding bearing surface A in the form of a V as shown in FIG. 3 or of concave shape and by maintaining the end of the branch 6a of the rocker arm between two opposite positioning keys 7. A part forming a clamping finger 8 and placed in abutment on the surface 6c1 and exerts pressure thereon by means of suitable means (not shown) for firmly pressing the 'reinforcing element 3 against the bearing surface A, thereby proceeding to the final machining of the rocker arm 6.
  • suitable means not shown
  • the surface 6v1 instead of being planar can for example be slightly curved, the plane tangent to the surface 6v1 at the point of intersection thereof with the longitudinal axis of the spindle being perpendicular said axis.
  • the pusher device 4 can also be constituted, for example, by a hydraulic or pneumatic piston device bearing on the spindle 5.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)

Description

La présente invention concerne un procédé de moulage d'un culbuteur pour moteur à combustion interne selon le préambule de la revendication 1 et une structure de moule pour la mise en oeuvre d'un tel procédé selon le préambule de la revendication 3.The present invention relates to a method of molding a rocker arm for an internal combustion engine according to the preamble of claim 1 and a mold structure for the implementation of such a method according to the preamble of claim 3.

On connaît des culbuteurs du type comprenant un corps de levier comprenant une première branche coopérant avec une came d'un arbre à cames du moteur et une seconde branche coopérant avec une queue de soupape, le corps de levier, en alliage léger, étant réalisé par un procédé de moulage en coquille sous pression. La branche coopérant avec la came comporte un élément de renforcement extrêmement dur résistant à l'usure par frottement avec la came et inséré à la coulée dans le culbuteur en alliage léger. Pour cela, l'élément de renforcement est en matériau fritté, carbure ou en fonte spéciale.Rockers of the type are known comprising a lever body comprising a first branch cooperating with a cam of an engine camshaft and a second branch cooperating with a valve stem, the lever body, of light alloy, being produced by a pressure shell molding process. The branch cooperating with the cam has an extremely hard reinforcement element resistant to wear by friction with the cam and inserted during casting in the light alloy rocker arm. For this, the reinforcing element is made of sintered material, carbide or special cast iron.

Cependant, les matériaux ci-dessus constituant l'élément de renforcement n'ont pas toujours donné entière satisfaction amenant ainsi les constructeurs à utiliser des éléments de renforcement en céramique ayant un meilleur comportement à l'usure que les matériaux métalliques ci-nommés, à condition que la surface frottante de l'élément de renforcement soit proche du "poli-miroir". Le poli de la surface frottante de l'élément de renforcement est obtenu selon un procédé connu avant la mise en place de celui-ci dans le culbuteur ce qui signifie que l'élément de renforcement ne sera pas usiné après coulée ou moulage du culbuteur. Tout l'usinage du culbuteur se fera donc en partant de l'élément de renforcement.However, the above materials constituting the reinforcing element have not always been entirely satisfactory, thus leading manufacturers to use ceramic reinforcing elements having better wear behavior than the metallic materials mentioned above, provided that the friction surface of the reinforcing element is close to the "mirror polish". The polish of the friction surface of the reinforcing element is obtained according to a known method before the positioning of the latter in the rocker arm, which means that the reinforcing element will not be machined after casting or molding the rocker arm. All machining of the rocker arm will therefore be carried out starting from the reinforcing element.

Toutefois, dans la mesure où l'élément de renforcement en céramique est extrêmement dur et fragile et amagnétique, il est nécessaire de le maintenir fermement dans le moule sans risques de rupture.However, since the ceramic reinforcing element is extremely hard and fragile and non-magnetic, it is necessary to hold it firmly in the mold without risk of breaking.

En outre, les patins obtenus après usinage "poli-miroir" ne pouvant pas avoir des dimensions absolument identiques, il faut prévoir un dispositif qui permette de compenser les différences de cotes des patins.In addition, the pads obtained after "mirror-polished" machining cannot have absolutely identical dimensions, it is necessary to provide a device which makes it possible to compensate for the differences in dimensions of the pads.

DE-A-35 20 484 décrit un procédé de moulage d'un culbuteur, dont l'une des branches comporte un élément de renforcement en céramique qui lui est solidarisé lors de l'opération de moulage. L'élément de renforcement est disposé sur un élément thermiquement isolant également en céramique. Selon ce procédé connu, on porte l'élément de renforcement à une température correspondant à la température de fusion de la matière utilisée pour couler le culbuteur et l'élément isolant a pour fonction d'éviter toute déperdition thermique entre l'élément de renforcement et le moule. Cette demande antérieure mentionne également qu'il est connu de fixer l'élément de renforcement dans le moule pendant l'opération de moulage du culbuteur. Pour cela, l'élément de renforcement est fixé dans le moule par l'intermédiaire de l'élément isolant ayant une forme appropriée complémentaire de celle de la partie inférieure bombée de l'élément de renforcement.DE-A-35 20 484 describes a method of molding a rocker arm, one of the branches of which comprises a ceramic reinforcing element which is secured to it during the molding operation. The reinforcing element is arranged on a thermally insulating element also made of ceramic. According to this known method, the reinforcing element is brought to a temperature corresponding to the melting temperature of the material used to pour the rocker arm and the insulating element has the function of avoiding any heat loss between the reinforcing element and the mold. This earlier application also mentions that it is known to fix the reinforcing element in the mold during the operation of molding the rocker arm. For this, the reinforcing element is fixed in the mold by means of the insulating element having an appropriate shape complementary to that of the curved lower part of the reinforcing element.

Cependant, l'élément isolant ne permet pas de maintenir fermement dans le moule l'élément de renforcement et il est nécessaire de prévoir plusieurs éléments isolants pour tenir compte des différences de cotes des éléments de renforcement.However, the insulating element does not allow the reinforcement element to be held firmly in the mold and it is necessary to provide several insulating elements to take account of the differences in dimensions of the reinforcement elements.

PATENT ABSTRACTS OF JAPAN vol. 9, n° 252 (M-420) 1975 concerne la fixation dans un moule d'un noyau en sable (2) à l'aide de doigts de verrouillage (5) actionnés par des ressorts (6) maintenant respectivement des parties en saillie (2a) du noyau (2) dans des évidements correspondants du chapeau de moulage (1a).PATENT ABSTRACTS OF JAPAN vol. 9, n ° 252 (M-420) 1975 relates to the fixing in a mold of a sand core (2) by means of locking fingers (5) actuated by springs (6) holding respectively projecting parts (2a) of the core (2) in corresponding recesses of the molding cap (1a).

Cet abrégé descriptif antérieur ne se rapporte pas du tout au problème de moulage de culbuteurs,dont l'une des branches comporte un élément de renforcement en céramique.This previous descriptive abstract does not relate at all to the problem of molding rocker arms, one of the branches of which has a ceramic reinforcing element.

La présente invention résout les problèmes ci-dessus en proposant un procédé de moulage d'un culbuteur pour moteur à combustion interne caractérisé en ce qu'il consiste à maintenir fermement l'élément de renforcement en céramique, dont la surface frottante avec la came est préalablement polie, dans le moule au moins pendant l'opération de moulage du culbuteur par un organe formant broche en appui forcé sur l'extrémité de l'élément de renforcement opposée à la surface frottante de celui-ci.The present invention solves the above problems by proposing a method of molding a rocker arm for an internal combustion engine, characterized in that it consists in firmly holding the ceramic reinforcing element, the friction surface of which with the cam is previously polished, in the mold at least during the molding operation of the rocker arm by a spindle member in forced support on the end of the reinforcing element opposite to the friction surface thereof.

Selon une caractéristique du procédé de moulage de l'invention, on réalise une partie faisant saillie de la branche du culbuteur coopérant avec la came à l'opposé de l'élément de renforcement et comportant une surface de préférence plane, perpendiculaire à l'axe longitudinal de l'élément de renforcement.According to a characteristic of the molding method of the invention, there is provided a protruding part of the branch of the rocker arm cooperating with the cam opposite the reinforcement element and comprising a surface which is preferably flat, perpendicular to the axis. longitudinal of the reinforcing element.

La structure de moule pour la mise en oeuvre du procédé ci-dessus défini, du type comprenant deux demi-moules supérieur et inférieur, est caractérisée en ce qu'elle comprend un dispositif de maintien de l'élément de renforcement dans l'un des demi-moules, comprenant la partie formant broche précitée disposée sur l'extrémité de l'élément de renforcement et un ensemble formant poussoir au-dessus de la partie formant broche pour maintenir celle-ci en appui forcé sur l'élément de renforcement.The mold structure for implementing the method defined above, of the type comprising two upper and lower half-molds, is characterized in that it comprises a device for holding the reinforcing element in one of the half-molds, comprising the aforementioned spindle part disposed on the end of the reinforcement element and a pusher assembly above the spindle part to maintain the latter in forced support on the reinforcement element.

Selon une caractéristique de la structure de moule, l'ensemble formant poussoir comprend un poussoir allongé dans le prolongement de la partie formant broche, un moyen élastique de rappel précontraint en appui sur le poussoir allongé et un organe de précontrainte du moyen élastique solidaire du demi-moule.According to a characteristic of the mold structure, the pusher assembly comprises an elongated pusher in the extension of the part forming spindle, an elastic pre-stressed return means bearing on the elongated pusher and a member for prestressing the elastic means secured to the half-mold.

Le moyen élastique de rappel précité permet de compenser les différences de dimensions entre deux patins.The aforementioned elastic return means makes it possible to compensate for the size differences between two pads.

L'invention sera mieux comprise, et d'autres buts, caractéristiques, détails et avantages de celle-ci apparaîtront plus clairement au cours de la description explicative qui va suivre faite en référence aux dessins schématiques annexés donnés uniquement à titre d'exemple illustrant un mode de réalisation de l'invention, et dans lesquels:

  • La figure 1 est une vue en coupe longitudinale représentant notamment le dispositif de maintien de l'élément de renforcement en céramique dans la structure de moule selon l'invention;
  • La figure 2 est une vue en coupe de l'extrémité de la branche du culbuteur munie de l'élément de renforcement en céramique; et
  • La figure 3 représente schématiquement le positionnement du culbuteur en vue de son usinage.
The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly during the explanatory description which follows, made with reference to the appended schematic drawings given solely by way of example illustrating a embodiment of the invention, and in which:
  • Figure 1 is a longitudinal sectional view showing in particular the device for holding the ceramic reinforcing element in the mold structure according to the invention;
  • Figure 2 is a sectional view of the end of the rocker arm provided with the ceramic reinforcing element; and
  • FIG. 3 schematically represents the positioning of the rocker arm for its machining.

En se référant à la figure 1, la structure de moulage 1 pour la coulée sous pression de l'alliage léger constituant le culbuteur comprend deux demi-moules supérieur et inférieur seul le moule inférieur 2 étant visible sur la figure.Referring to Figure 1, the molding structure 1 for the die casting of the light alloy constituting the rocker includes two upper and lower half-molds only the lower mold 2 being visible in the figure.

La référence 3 désigne un élément de renforcement en céramique qui doit être solidarisé, après moulage, de la branche du corps de levier du culbuteur coopérant avec une came d'un arbre à came de moteur à combustion interne. Cet élément de renforcement comprend une surface frottante 3a destinée à coopérer avec la came et préalablement polie suivant un procédé connu. Cette surface frottante présente une forme bombée ou convexe s'adaptant dans une cavité correspondante 2a du demi-moule inférieur 2. L'élément de renforcement 3 comprend de plus une partie formant queue d'ancrage 3b de l'élément à l'extrémité de la branche du culbuteur coopérant avec la came et située à l'opposé de la surface frottante 3a.Reference 3 designates a ceramic reinforcing element which must be secured, after molding, to the branch of the lever body of the rocker arm cooperating with a cam of an internal combustion engine cam shaft. This reinforcing element comprises a rubbing surface 3a intended to cooperate with the cam and previously polished according to a known method. This rubbing surface has a convex or convex shape fitting into a corresponding cavity 2a of the lower half-mold 2. The reinforcing element 3 further comprises a part forming an anchoring tail 3b of the element at the end of the branch of the rocker arm cooperating with the cam and situated opposite the friction surface 3a.

Selon l'invention, un dispositif formant poussoir 4 exerce une poussée sur une partie formant broche 5 de façon à maintenir celle-ci en appui forcé sur la partie formant queue d'ancrage 3b de l'élément de renforcement 3. La partie formant broche 5 située dans l'axe longitudinal de l'élément de renforcement 3 est de préférence à section transversale circulaire étant bien entendu que toute autre forme de section (ovale-rectangulaire-etc...) convient.According to the invention, a device forming a pusher 4 exerts a thrust on a part forming a spindle 5 so as to maintain it in forced support on the part forming an anchor tail 3b of the reinforcing element 3. The part forming a spindle 5 located in the longitudinal axis of the reinforcing element 3 is preferably of circular cross section, it being understood that any other shape of section (oval-rectangular-etc ...) is suitable.

Le dispositif formant poussoir 4 comprend de bas en haut par rapport à la figure 1 et suivant l'axe longitudinal de l'élément de renforcement 3 un poussoir allongé 4a, dont l'extrémité inférieure vient en appui sur la partie supérieure de la partie formant broche 5 et portant à son extrémité supérieure une tête 4a1, un moyen élastique de rappel précontraint 4b en appui sur la tête 4a1 du poussoir allongé et un organe de précontrainte 4c du moyen élastique 4b, l'organe 4c étant mobile et s'éclipsant au moment de l'ouverture du moule. L'organe de précontrainte 4c peut être formé par une vis ou toute autre moyen mécanique de réglage de la précontrainte du moyen élastique 4b qui peut être formé par un ressort de compression ou par des rondelles élastiques en acier du type Belleville. L'organe de précontrainte 4c, le moyen élastique de rappel 4b et la tête 4a1 du poussoir 4a sont logés dans un alésage 4d du demi-moule inférieur 2 tandis que la partie allongée du poussoir 4a passe à travers un alésage 4e de plus faible diamètre que celui de l'alésage 4d partant du fond de ce dernier et débouchant dans le creux du moule, l'extrémité inférieure de la partie allongée faisant saillie dans le creux du moule.The pusher device 4 comprises from bottom to top relative to FIG. 1 and along the longitudinal axis of the reinforcing element 3 an elongated pusher 4a, the lower end of which bears on the upper part of the part forming spindle 5 and carrying at its upper end a head 4a1, an elastic prestressed return means 4b bearing on the head 4a1 of the elongated plunger and a prestressing member 4c of the elastic means 4b, the member 4c being movable and slipping off at when the mold is opened. The prestressing member 4c can be formed by a screw or any other mechanical means for adjusting the prestressing of the elastic means 4b which can be formed by a compression spring or by elastic steel washers of the Belleville type. The prestressing member 4c, the elastic return means 4b and the head 4a1 of the pusher 4a are housed in a bore 4d of the lower half-mold 2 while the elongated part of the pusher 4a passes through a further bore 4e smaller diameter than that of bore 4d starting from the bottom of the latter and opening into the hollow of the mold, the lower end of the elongated part projecting into the hollow of the mold.

On comprend que l'ensemble formant poussoir 4 maintient en appui forcé la partie formant broche 5 sur l'élément de renforcement 3 qui se trouve ainsi fermement maintenu dans la cavité 2a du demi-moule inférieur 2.It will be understood that the pusher assembly 4 maintains forced support of the spindle portion 5 on the reinforcing element 3 which is thus firmly held in the cavity 2a of the lower half-mold 2.

La figure 1 montre également la présence d'un paroi plane 1a réalisée dans le creux du demi-moule inféreur 2 de façon perpendiculaire à l'axe longitudinal de l'élément de renforcement 3, l'alésage 4e débouchant à travers cette paroi. La paroi 1a se raccorde à la paroi courbe définissant l'extrémité supérieure de la branche du culbuteur coopérant avec la came par une paroi plane 1b.FIG. 1 also shows the presence of a flat wall 1a produced in the hollow of the lower half-mold 2 perpendicular to the longitudinal axis of the reinforcing element 3, the bore 4e emerging through this wall. The wall 1a is connected to the curved wall defining the upper end of the branch of the rocker arm cooperating with the cam by a flat wall 1b.

Lors de l'injection sous pression de la matière en alliage léger constituant le culbuteur, la partie formant queue d'ancrage 3b de l'élément de renforcement 3 sera noyée avec la partie formant broche 5 dans la matière du culbuteur (voir la figure 2), laquelle partie formant broche 5 sera d'un diamètre suffisant pour résister aux chocs consécutifs à l'arrivée de la matière injectée sous pression.During the injection under pressure of the light alloy material constituting the rocker arm, the part forming an anchor tail 3b of the reinforcing element 3 will be embedded with the pin-forming part 5 in the material of the rocker arm (see FIG. 2 ), which spindle part 5 will be of sufficient diameter to withstand the shocks resulting from the arrival of the material injected under pressure.

La figure 3 représente le culbuteur 6 obtenu après moulage. Le corps du culbuteur comporte la branche 6a coopérant avec la queue d'une soupape et la branche 6b coopérant avec la came d'un arbre à cames et munie à son extrémité inférieure de l'élément de renforcement en céramique 3. La référence 6c désigne la partie en saillie venant de moulage obtenue à partir des parois 1a et 1b du demi-moule 2. Cette partie faisant saillie comporte principalement une surface plane 6c1 située à l'opposé de l'élément de renforcement 3 de façon perpendiculaire à l'axe longitudinal de celui-ci. La partie formant broche a été extraite lors du moulage par des dispositifs extracteurs classiques non représentés. Il subsiste un trou délimité par les traits pointillés et surplombé d'un orifice 6d débouchant à la surface 6c1, lequel orifice a été défini lors du moulage par la partie extrême inférieure du poussoir allongé 4a.FIG. 3 represents the rocker arm 6 obtained after molding. The rocker body comprises the branch 6a cooperating with the stem of a valve and the branch 6b cooperating with the cam of a camshaft and provided at its lower end with the ceramic reinforcing element 3. The reference 6c denotes the projecting part from molding obtained from the walls 1a and 1b of the half-mold 2. This projecting part mainly comprises a flat surface 6c1 situated opposite the reinforcing element 3 perpendicularly to the longitudinal axis thereof. The spindle part was extracted during molding by conventional extractor devices not shown. There remains a hole delimited by the dotted lines and overhung by an orifice 6d opening onto the surface 6c1, which orifice was defined during molding by the lower end part of the elongated pusher 4a.

La présence de la surface plane 6c1 a pour avantage de faciliter le maintien en position du culbuteur 6 lors de son usinage.The presence of the flat surface 6c1 has the advantage of facilitating the holding in position of the rocker arm 6 during its machining.

Ce positionnement est obtenu en disposant tout d'abord la surface frottante 3a de l'élément de renforcement 3 sur une surface d'appui correspondante A en forme de V comme représenté en figure 3 ou de forme concave et en maintenant l'extrémité de la branche 6a du culbuteur entre deux touches de positionnement opposées 7. Une partie formant doigt de serrage 8 et disposée en appui sur la surface 6c1 et exerce une pression sur celle-ci à l'aide de moyens appropriés (non représentés) pour presser fermement l'élément de renforcement 3 contre la surface d'appui A, pour ainsi procéder à l'usinage final du culbuteur 6. Bien entendu, d'autres modifications peuvent être apportées sans sortir du cadre de la présente invention.This positioning is obtained by first placing the rubbing surface 3a of the reinforcing element 3 on a corresponding bearing surface A in the form of a V as shown in FIG. 3 or of concave shape and by maintaining the end of the branch 6a of the rocker arm between two opposite positioning keys 7. A part forming a clamping finger 8 and placed in abutment on the surface 6c1 and exerts pressure thereon by means of suitable means (not shown) for firmly pressing the 'reinforcing element 3 against the bearing surface A, thereby proceeding to the final machining of the rocker arm 6. Of course, other modifications can be made without departing from the scope of the present invention.

Ainsi, la surface 6c1 au lieu d'être plane peut être par exemple légèrement courbe, le plan tangent à la surface 6c1 au point d'intersection de celle-ci avec l'axe longitudinal de la broche étant perpendiculaire audit axe.Thus, the surface 6v1 instead of being planar can for example be slightly curved, the plane tangent to the surface 6v1 at the point of intersection thereof with the longitudinal axis of the spindle being perpendicular said axis.

De plus, le dispositif formant poussoir 4 peut être également constitué par exemple par un dispositif hydraulique ou pneumatique à piston venant en appui sur la broche 5.In addition, the pusher device 4 can also be constituted, for example, by a hydraulic or pneumatic piston device bearing on the spindle 5.

Claims (7)

1. A method for casting a rocker arm for an internal combustion engine, which rocker arm includes a lever body an arm of which intended to co-operate with a cam of a camshaft has a reinforcing element in particular in ceramic, characterized in that it consists in firmly maintaining the ceramic reinforcing element (3) the surface (3a) of which in contact with the cam is previously polished, in the mold (1, 2) at least during the rocker arm molding operation with a spindle-forming means (5) located in the molding cavity arid forcibly urged against the end of the reinforcing element (3) opposite to the friction surface (3a) thereof.
2. A method according to claim 1, characterized in that it consists in forming a part (6c) projecting from said arm (6b) of the rocker arm (6) opposite to the reinforcing element (3) and having a preferably plane surface (6c1) perpendicular to the longitudinal axis of the reinforcing element (3).
3. A mould structure for carrying out the method according to claim 1 or 2, having two lower and upper half molds, characterized in that it comprises a device (4; 5) for maintaining the element (3) in one (2) of the half molds, including said spindle-forming part (5) disposed on the end of the reinforcing element (3) and a pusher-forming assembly (4) above the spindle-forming part (5) to forcibly urge the latter against the reinforcing element (3).
4. Structure according to claim 3, characterized in that the pusher-forming assembly (4) includes an elongated pusher (4a) along the extension of the spindle-forming part (5), a prestressed return resilient means (4b) urged against the elongated pusher (4a) and a means (4c) for prestressing the resilient means (4b) fixed to the half mold (1).
5. Structure according to claim 3 or 4, characterized in that the pusher-forming assembly (4) is located in the lower half mold (2) and in that the reinforcing element (3) has its polished surface (3a) urged against a cavity (2a).
6. Structure according to one of claims 3 to 5, characterized in that the resilient means (4b) is constituted by a compression spring, steel resilient washers or analogous.
7. Structure according to claim 3, characterized in that the pusher-forming assembly (4) is constituted by a hydraulic or pneumatic device with a piston resting on the spindle-forming means (5).
EP88400791A 1987-04-14 1988-03-31 Method for moulding a rocker arm for internal combustion engine and mould structure for executing the moulding procedure Expired - Lifetime EP0287425B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8705300 1987-04-14
FR8705300A FR2613963B1 (en) 1987-04-14 1987-04-14 METHOD FOR MOLDING AND MACHINING A ROCKER FOR INTERNAL COMBUSTION ENGINE, MOLD STRUCTURE FOR IMPLEMENTING THE MOLDING METHOD AND ROCKER OBTAINED ACCORDING TO MOLDING AND MACHINING PROCESSES

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EP0287425A1 EP0287425A1 (en) 1988-10-19
EP0287425B1 true EP0287425B1 (en) 1991-04-24

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US (1) US4905751A (en)
EP (1) EP0287425B1 (en)
DE (1) DE3862506D1 (en)
ES (1) ES2022652B3 (en)
FR (1) FR2613963B1 (en)

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Also Published As

Publication number Publication date
ES2022652B3 (en) 1991-12-01
US4905751A (en) 1990-03-06
DE3862506D1 (en) 1991-05-29
FR2613963B1 (en) 1991-02-08
FR2613963A1 (en) 1988-10-21
EP0287425A1 (en) 1988-10-19

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