Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
• • 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
  • F01L3/02—Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12458—All metal or with adjacent metals having composition, density, or hardness gradient

Definitions

• BACKGROUND (a) Field of the invention This invention relates to valve seat material for an internal combustion engine.
• a valve seat of an internal combustion engine is low alloy cast irons (for example, Cu-Cr-Mo, Ni-Cr-Mo) in the case of light loads and a high alloy, such as high Cr, cast iron or cast steel in the case of heavy loads.
• a valve seat is exposed to the combustion gases in an internal combustion engine and is subjected, under a high temperature of between at least 200 C. and an estimated maximum of 700 C., to impact of an engine valve face and sliding abrasion by rotation of the valve.
• the lead 3,725,048 Patented Apr. 3, 1973 the valve from the valve seat surface is worsened and the valve temperature and the valve seat temperature are greatly increased, whereby a rapid abrasion is caused and the tappet clearance becomes zero and the engine function is lost.
• An object of the invention is. to provide a composition of valve seat material which avoids the above deficiencies.
• the valve seat material is constituted of lead, copper and carbon with the balance being iron.
• Table 1 shows the relation of different fuels and valve and valve seat temperatures and Table 2 shows abrasion degrees in actual machine endurance tests for conventional materials and for materials according to this invention.
• Table 3 shows the composition of the adhered matter on the sliding surface in the same test, and the adhered matter is considered to be a combustion product and a sliding surface portion product.
• valve seat made of conventional SKD 1 material in such that the valve face temperature and the valve seat temperature, which are not great when lead-added gasoline is used, increase substantially when non-lead gasoline or propane is used.
• a valve seat made of material containing Cu and Pb produces lowered temperatures, even when non-lead gasoline is used, as compared to the temperatures when the valve seat is made of SKD 1 material and lead-added gasoline is used.
• valve seat material contains Pb but not Cu.
• a valve seat made of the material containing Cu and Pb and lower in temperature as mentioned above is small in abrasion degree and is extremely improved in duration time in comparison with the valve seat of the conventional materials.
• This invention has a first characteristic feature that Cu and Pb are contained in an alloy for a valve seat material, and thereby, even in an internal combustion engine using non-lead gasoline, the valve seat surface temperature can be equal to or lower than the temperature in the case of using lead-added gasoline, and thus the life can be improved.
• the heat conductivity of the material itself is improved in that Cu is distributed to the alloy grain bound aries, and by virtue of the improved heat conductivity, the heat radiating effect from the valve seat is greatly improved, whereby it becomes possible for the valve seat surface temperature to become lowered more than about 100 C. in comparison with the conventional material.
• Pb has in itself a lubrictaing effect and presents, even in the case of using non-lead gasoline, an excellent lubricating effect as a compound at the combustion temperature and additionally by its coexistence wtih a Cu compound as mentioned above, this effect is not obtained if the lead content is below 0.3% by weight whereas practical strength is difiicult to obtain if the lead content is above 20% by weight.
• the range of the lead must be 03-20% by weight.
• Cu has a lubricating efiTect similar to Pb and improves the heat conductivity by existing in the alloy grain boundaries, but it does not contribute to the lubricating effect and heat conductivity because it is dissolved in Fe in solid solution, when the copper content is below 5% weight, and a practical strength for the valve seat is difficult to obtain if the copper content is above 45% by weight. Thus, the range of the copper must be 5-45% by weight.
• a Fe-Cu alloy matrix is low in hardness, and therefore C must be contained in the alloy to provide the necessary abrasion resistance for the valve seat material.
• C is in solid solution in Fe, the carbon is not effective if the content thereof is below 0.2% and it makes the material brittle if it is present in an amount above 4%.
• the range of carbon therefore is 0.24% and preferably 0.22%.
• additives improve the strength and abrasion resistance of the material by existing in the Fe-Cu-C alloy in the form of a solid solution or an intermetallic compound, or independently, and also serve as an anti-friction material in the form of a combustion product.
• valve seat material in the tables Two examples of the valve seat material in the tables are manfactured by the following processes:
• composition of 25% by weight of Cu, 4% weight of Pb, 1% by weight of C and the balance Fe is manufactured by producing a mixed powder of the above composition and forming it into a mold product of 7.0 gr./cc. which is sintered for about 30 minutes at a temperature of 1120 C. within a reducing atmosphere.
• the composition of 20% by weight of Cu, 5% by weight of Cr, 2% by weight of Pb, 1% by weight of C and the balance Fe is manufactured by producing a mixed powder of the above composition and forming a mold product of the same of a density of 7.0 gr./cc. which is sintered for about 30 minutes at 1250 C. Within a reduring atmosphere.
• Pb and Cu are uniformly distributed within the valve seat by this powder formation and sintering process, and first Pb is exuded by the action of the combustion gas, oil, heat, striking and sliding of the valve against the seat at the time of operation of the engine, and then Pb which contains Cu is exuded and additionally their chemical compounds are formed on the surface for exhibiting a lubricating effect.
• the lubricating and anti-friction effects depend on the Pb and Cu, and it is not always necessary to disperse the same throughout the entire valve seat but the seat may be modified so that a powder layer containing Pb and Cu is formed only on the surface at the time of molding of the mixed powder before sintered, or after a sintered product not containing Pb and Cu is formed, the product is impregnated with Pb and Cu at the outer surface thereof. It may be contemplated that Pb and Cu are separately used for mixing or impregnation, but this may be modified by using these elements in the form of a composition of Pb-Cu coexistence (for example, Kelmet alloy).
• valve seat material of this invention can be manufactured easily and economically by a powder metallurgy process as mentioned above, the material may be manufactured by other processes such as a casting process or the like. Additionally, it is of course permissible that, when the elements are present within the range disclosed, other additives can be incorporated and a reinforcing treatment or working can be additionally employed.
• An alloy for a valve seat of an internal combustion engine consisting essentially of 03-20% by weight lead, 5 to 45% by weight copper, 0.2-4% by weight of carbon with the balance being iron, the alloy being capable of forming lubricant films of compounds of lead and copper for use with non-leaded gasoline to reduce wear of the valve seat.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=13729574

Family Applications (1)

Country Status (7)

Cited By (1)

Families Citing this family (1)

• 1970
  • 1970-09-15 JP JP45080841A patent/JPS5031847B1/ja active Pending
• 1971
  • 1971-09-09 AU AU33304/71A patent/AU470320B2/en not_active Expired
  • 1971-09-14 CA CA122,820A patent/CA955080A/en not_active Expired
  • 1971-09-14 US US00180467A patent/US3725048A/en not_active Expired - Lifetime
  • 1971-09-14 DE DE2145944A patent/DE2145944C3/de not_active Expired
  • 1971-09-15 FR FR7133292A patent/FR2107723A5/fr not_active Expired
  • 1971-09-15 GB GB4306971A patent/GB1367115A/en not_active Expired

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