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
  • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/10—Cores; Manufacture or installation of cores
  • B22C9/103—Multipart cores
• • 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
  • B22D19/0009—Cylinders, pistons

Definitions

• the present invention relates to a process for the production of castings and relates more particularly to a process for casting a cylinder head for an internal combustion engine, as well as a core for the implementation of this process, making it possible to improve the dimensional accuracy of all combustion chambers, intake ducts, exhaust ducts.
• an internal combustion engine cylinder head is carried out in a mold comprising at least one core for each of the sub-assemblies of combustion chambers, intake ducts and exhaust ducts.
• the core defining the shapes of the combustion chambers is often produced by an imprint integrated into the sole (metal bottom) of the mold.
• Such devices have the disadvantage of being sensitive to differences in positioning of the cores relative to each other, these positioning differences arising either from inaccuracies during the positioning of the cores in the mold, or from movements of the cores during the casting of the metal caused by the difference in density between the cores and the cast metal.
• These differences in positioning of the cores forming the intake and exhaust ducts generally cause a shift between the position of the valve seat linked to the combustion chamber and the end of the intake or exhaust duct which disturbs the air flow and deteriorates engine performance.
• This disturbance generated by the spoiler is less significant than that previously created by the offset of one end of the conduit with the valve seat but is nevertheless penalizing in the case of conduits and valves of small diameter.
• the object of the present invention is therefore to propose a method for casting a cylinder head as well as a core making it possible to directly obtain a good location of the valve seats with respect to the intake and exhaust ducts so as to eliminate calibration machining and obtain better gas flow.
• the carrying out this process and its associated core remaining simple and economical to carry out.
• the method according to the invention relates to the molding of an internal combustion engine cylinder head, of the type by which a metal alloy is poured into a mold containing non-fusible cores corresponding in particular to the recessed parts of the cylinder head such as the combustion chambers , intake pipes, exhaust pipes and water or oil chambers.
• the method is characterized in that a single monobloc core integrates the shapes defining both the combustion chambers and the intake ducts.
• the one-piece core also incorporates the shapes defining the exhaust ducts.
• valve seats of the cylinder head are produced by rings added and inserted during casting, said rings being supported by the monobloc core.
• the monobloc core also incorporates the adapted shapes defining the gross reference frame used for machining starts.
• the invention also relates to a core intended to be used for the implementation of the method defined above and characterized in that it is of the one-piece type and incorporates the shapes defining both the combustion chambers and the ducts of admission.
• the monobloc core also incorporates the shapes defining the exhaust ducts and supports the rings serving as valve seats.
• the monobloc core also incorporates the adapted shapes defining the gross reference frame used for the machining starts.
• said monobloc core is produced in a core box and consists of compressed sand and agglomerated with a binder such as resin.
• FIG. 1 shows a schematic perspective view of a particular embodiment of a one-piece core used for molding an internal combustion engine cylinder head according to one invention
• - Figure 2 is a top view of the one-piece core shown in Figure 1, -
• FIG. 3 is a side view of the one-piece core shown in Figure 1;
• FIG. 4 is a top view of a molding device used for the implementation of the method, -
• FIG. 5 shows a cross section along the line V-V of the molding device shown in Figure 4;
• FIG. 6 represents a partial view in longitudinal section of the molding device along line VI-VI of FIG. 4.
• FIG. 1 shows a particular embodiment of a core 1 for the production by molding of an internal combustion engine cylinder head according to the invention.
• FIGS. 1 to 3 we see a core 1 of the monobloc type used for molding a cylinder head of internal combustion engine type four cylinders in line and four valves per cylinder.
• the monobloc core 1 of FIGS. 1 to 3 comprises four identical parts 4 regularly spaced apart, arranged in the same alignment, and defining the four combustion chambers of the cylinder head to be molded.
• Each combustion chamber 4 of the monobloc core 1 is connected in its upper part to two arms 2 and to an arm 3 respectively defining the two intake ducts and the two Siamese exhaust ducts of the cylinder head to be molded.
• rings 7, not shown in FIGS. 1 and 2 are arranged around the intake 2 and exhaust 3 conduits, against the combustion chambers 4 of the monobloc core 1
• These rings 7 are made of material suitable for the production of a valve seat and allow the valve seats to be inserted during the casting of the cylinder head.
• the monobloc core 1 comprises a part 5 disposed under the combustion chambers 4. This part 5 extends mainly in the direction of the neighboring combustion chambers 4 to form a base 5 supporting the combustion chambers 4 to a suitable distance.
• the base 5 also extends transversely to form arms 6, the ends 8 of which define the raw reference frame used for the machining starts.
• the thickness of the base 5 is chosen according to the rigidity and the strength of the monobloc core 1 desired.
• the core 1 as shown in Figures 1 to 3 can be produced in a known manner in a core box with compressed sand and agglomerated with a binder.
• Figures 4 to 6 show a particular embodiment of a molding device using the one-piece core 1 for implementing the method of molding a cylinder head according to
• FIG. 4 presents more particularly a mold seen from above when only the one-piece core 1 is put in place.
• This mold comprises four movable lateral mold elements 11, 12, 16 and 17 which can move apart to facilitate demolding of the cylinder head and a lower mold element or sole 10 having a flat surface 15 forming the lower face of the cylinder head to be molded .
• FIG. 5 shows a section of the mold of FIG. 4 when the various conventional cores necessary for molding the water chamber of the cylinder head are put in place.
• the mold comprises a movable upper mold element 13, not shown in FIG. 4, closing the mold to define the thickness of the walls of the cylinder head to be molded and the volume of the oil chamber. Filling holes, not shown in the figure, are formed through the upper mold element to allow the casting operation.
• the movable lateral mold element 11 has a cavity allowing the free end of the arms 2 to hold in position, forming the intake ducts when the mold is closed.
• the movable lateral mold element 12 has a cavity allowing the free end of the arms 3 making the exhaust ducts to be held in position.
• the sole 10 has a cavity 14 for receiving the one-piece core 1 before the mold is closed and the casting operation.
• the shape and volume of the cavity 14 are adapted and adjusted to the base 5 and to the arms 6 of the one-piece core 1 as shown in FIGS. 1 to 3, so that the base 5 and the arms 6 are integrally arranged in the cavity 14 of the sole 10 when the one-piece core 1 is placed in the mold.
• the method of production by molding of the cylinder head comprises the following operations:
• the molding process thus produced makes it possible to obtain a cylinder head having an excellent location of the rings 7 forming the valve seats with respect to the intake 2 and exhaust 3 conduits.
• the latter being molded directly by the monobloc core l and the rings 7, inserted during casting, being supported by this same monobloc core 1, the dimensional accuracy of the combustion chamber, valve seats, intake ducts, exhaust ducts is independent of the location of the different cores present in the mold and depends solely on the quality of production of the monobloc core 1.
• This molding process using the monobloc core 1 therefore makes it possible to dispense with the calibration machining usually necessary with the conventional cylinder head molding processes using several cores for the conduits and the combustion chamber.
• the use of the monobloc core 1 also makes it possible to produce a connection between the conduits and the combustion chamber, the aerodynamics of which are optimized so as to offer very little resistance to the flow of air.
• the monobloc core 1 also defines the raw reference frame used for the machining starts, which makes it possible to eliminate the localization uncertainties linked to the use of different cores and to obtain better localization of all the machining operations.
• the invention is in no way limited to the embodiment described and illustrated, which has been given only by way of example.
• the method of using a monobloc core integrating the shapes defining both the combustion chambers, the intake ducts and the exhaust ducts can be used in other types of molds such as pressure casting or squeeze-casting or sand molds (green or self-hardening).

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=9494239

Family Applications (1)

Country Status (7)

Families Citing this family (10)

Family Cites Families (5)

• 1996
  • 1996-07-19 FR FR9609071A patent/FR2751251B1/fr not_active Expired - Fee Related
• 1997
  • 1997-07-11 WO PCT/FR1997/001273 patent/WO1998003290A1/fr active IP Right Grant
  • 1997-07-11 ES ES97932896T patent/ES2192689T3/es not_active Expired - Lifetime
  • 1997-07-11 JP JP10506624A patent/JP2000514898A/ja active Pending
  • 1997-07-11 BR BR9710505A patent/BR9710505A/pt not_active IP Right Cessation
  • 1997-07-11 EP EP97932896A patent/EP0958076B1/de not_active Expired - Lifetime
  • 1997-07-11 DE DE69719375T patent/DE69719375T2/de not_active Expired - Lifetime

Non-Patent Citations (1)

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