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
  • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
  • F01L3/08—Valves guides; Sealing of valve stem, e.g. sealing by lubricant
• • 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
• • 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
  • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
  • F01L3/22—Valve-seats not provided for in preceding subgroups of this group; Fixing of valve-seats

Definitions

• the invention relates to a method for producing cylinder heads for internal combustion engines according to the preamble of patent claim 1.
• valve seat ring The known method of pulling in valve seats or hollow cylindrical valve guides requires considerable manufacturing outlay, e.g. B. machining of valve seat ring, Vent i If ⁇ h tion and cylinder head in order to comply with the necessary installation tolerances, and also correct positioning before installing the rings or valve guides in the cylinder head.
• manufacturing outlay e.g. B. machining of valve seat ring, Vent i If ⁇ h tion and cylinder head in order to comply with the necessary installation tolerances, and also correct positioning before installing the rings or valve guides in the cylinder head.
• a surface treatment e.g. B. by Läserumschme or alloy, considerable amounts of energy are required, which makes this method appear very uneconomical with an efficiency of 3%.
• ASSEMBLY COPY Pour high density into the cylinder heads, however, there is no intimate connection between the cylinder head material and the valve seat ring (DE 39 37 402 A1). Essentially, the ring in the cylinder head only holds by mechanical clamping, as a result of which there is no intimate contact with the cylinder head and there is therefore a risk of the rings falling out.
• This solution also has the disadvantage of an oxidized transition from the valve seat ring to the cylinder head; the resulting layer has an insulating effect and prevents a high conductive heat transfer.
• the invention will remedy these disadvantages.
• the object of the invention is accordingly to develop a solution for the design of cylinder heads in which by direct pouring of valve seats and valve guides the manufacturing outlay can be reduced and yet an intimate connection of the vent can be achieved and the valve guides on the cylinder head material, thus increasing the thermal conductivity.
• Valve seat rings and valve guides with an open Pore volumes of 5 to 15% are used.
• liquid aluminum penetrates into the pores of the tempered Venti seat rings and Venti l guides and fills them. This creates an intimate connection between the two materials.
• the thermal conductivity of the materials increases by the proportion of infiltrated aluminum.
• an insulating intermediate layer in the area of the cylinder head and valve seat or valve guide is avoided, as a result of which the heat conduction from the above-mentioned component to the cooling circuit in the cylinder head is increased. Machining steps, both in cylinder head machining and in the manufacture of valve seat rings or valve guides, can be dispensed with.
• the invention also offers the possibility of using ceramic materials based on iron or copper instead of conventional seat ring and guide materials, which are specifically designed for infiltration through liquid light metals.
• Liquid aluminum can be poured into the mold either under gravity or under pressure, optionally with variable pressure ratios.
• valve seat rings and valve guides it is advisable to heat valve seat rings and valve guides before pouring. This can be done either after inserting it with the mold or before inserting it into the mold. According to an advantageous further education, it is possible to adjust the pore volume of valve seat rings and valve guides in a graded manner, ie that the area with high thermal and mechanical loads has a smaller pore volume, eg. B. of ⁇ 2%, while the areas towards the cylinder head have a pore volume in the above-described limit range.
• valve seats and / or valve guides can be generated during a repressing process.
• Fig. 1 a tendon at the i c ht of a cylinder head in
• Fig is a schematic diagram for the production of graded porosity.
• the drawing shows a section of a section in the area of an intake or exhaust port of a cylinder head after the casting process.
• the casting core 2 with stepped sections has not yet been removed from the solidified aluminum melt 1.
• the casting core 2 contains an upper cylindrical section 3 and below it a second cylindrical section 4 with a larger diameter.
• the transition between the two sections 3, 4 forms a flat annular shoulder 5, while the second section 4 connects at its lower end via an annular shoulder 6 to the outer lateral surface of the cylindrical casting core 2.
• a prefabricated valve guide 7 is placed on the upper section 3 and a prefabricated valve seat ring 8 is placed on the lower section 4.
• a prefabricated valve guide 7 is placed on the upper section 3 and a prefabricated valve seat ring 8 is placed on the lower section 4.
• the corner region between the cylindrical section 4 and the annular shoulder 6 is designed in accordance with the contour of the valve seat ring 8.
• valve 8 and the valve guide 7 are manufactured with an open pore volume of 5 to 15% and preheated before insertion.
• liquid aluminum penetrates into the pores of the temperature-controlled valve rings and guides 8, 7 and fills them. What is important here is the even distribution of the filled pores and sufficient basic strength of the components to be poured in.
• the pore volume of the valve components in a graded manner, ie. that is, the area with the high thermal and mechanical stress has a pore volume of ⁇ 2%, while the area towards the cylinder head has a pore volume in the limit range described above. This can be achieved by different degrees of compression during a subsequent pressing process, which is explained below with reference to the schematic representation in FIG. 2.
• a powder mixture consisting of a mixture specially composed for valve seat rings Egg-based alloying is pressed in a mold 9 to a density of, for example, 6.4 to 6.8 g / cm 3 in accordance with stage 1 of FIG. 2 with a stamp 10 to form a body 11 with an inclined surface.
• This green body is then sintered in a stage 2 at a temperature between 900 and 1200 ° C.
• the sintered blank is obtained in a stage 3 with the aid of a stamp 12, after which only a geometrically predetermined area of the ring is deformed.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)
• Nonmetallic Welding Materials (AREA)
• Combustion Methods Of Internal-Combustion Engines (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=7789822

Family Applications (1)

Country Status (9)

Families Citing this family (20)

Family Cites Families (11)

• 1996
  • 1996-03-29 DE DE19612500A patent/DE19612500A1/de not_active Withdrawn
• 1997
  • 1997-03-26 DE DE59700975T patent/DE59700975D1/de not_active Expired - Fee Related
  • 1997-03-26 KR KR1019980707753A patent/KR20000005112A/ko not_active Application Discontinuation
  • 1997-03-26 ES ES97916394T patent/ES2144312T3/es not_active Expired - Lifetime
  • 1997-03-26 JP JP9534911A patent/JP2000507504A/ja active Pending
  • 1997-03-26 AT AT97916394T patent/ATE188537T1/de not_active IP Right Cessation
  • 1997-03-26 WO PCT/EP1997/001540 patent/WO1997037107A1/fr not_active Application Discontinuation
  • 1997-03-26 US US09/155,382 patent/US6112803A/en not_active Expired - Fee Related
  • 1997-03-26 EP EP97916394A patent/EP0890020B1/fr not_active Expired - Lifetime
  • 1997-03-26 PT PT97916394T patent/PT890020E/pt unknown

Non-Patent Citations (1)

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