Valves and valve actuation – Valve – Materials
Reexamination Certificate
1999-02-25
2001-02-13
Fox, John (Department: 3753)
Valves and valve actuation
Valve
Materials
C123S188300
Reexamination Certificate
active
06186478
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an Al alloy poppet valve, and especially to an Al alloy poppet valve that provides high strength and high wear resistance.
An intake poppet valve that has relatively low heat load is made of Al alloy to decrease inertia mass in a valve operating system, thereby decreasing engine performance. However, Al alloy valve has low mechanical strength and wear resistance, thereby decreasing durability and reliability.
A poppet valve is made of metal matrix composite (MMC) in which ceramic particles or whiskers are added to heat-treatable Al alloy such as JIS-2000 Alloy (Al-Cu-Mg), JIS-4000 alloy (Al-Si), JIS-6000 alloy (Al-Mg-Si) or JIS-7000 alloy (Al-Zn-Mg-Cu) under Japanese Industrial Standards (JIS). The poppet valve is subjected to melting such as T6 treatment under JIS to increase strength and wear resistance.
In the poppet valve ceramic particles are added to heat-treatable Al alloy and subjected to melting, working temperature of a valve head 250 to 300° C. is higher than solution treatment temperature of 150 to 200° C. when it is used as an intake valve for an engine, so that hardness of the poppet valve increased by solution treatment gradually decreases, and a valve face which requires wear resistance is worn early so that durability is decreased.
To solve the problems, a metal that has wear resistance is padded, or a hardened layer is formed by an alloy which contains reinforcement element. However, the valve head must be heated to temperature above solution treatment temperature, and strength of the whole valve head is decreased.
SUMMARY OF THE INVENTION
To overcome the disadvantage, it is an object to provide a wear-resistant durable Al alloy poppet valve to prevent decrease in hardness at working temperature of an engine.
According to the present invention, there is provided an Al alloy poppet valve which comprises a valve head and a valve stem, at least said valve head being made of material of non-heat-treatable Al alloy, ceramic particles being uniformly dispersed in the material
The material is strengthened by the ceramic particles to increase mechanical strength and to minimize decrease in hardness owing to working temperature of an engine, thereby increasing durability and reliability.
REFERENCES:
patent: 4838936 (1989-06-01), Akechi
patent: 5076866 (1991-12-01), Koike et al.
patent: 5409661 (1995-04-01), Imahashi et al.
patent: 0 566 098 (1993-10-01), None
European Search Report Communications for XS 9930142110 MA “Abstract/Zusammenfassung/Abrege” No. 99301421.6 (Modified by the Search Division) for Fuji Oozx Inc.
US XP-002104156 “Aluminium” by J.E. Hatch, 1984 “American Society For Metals”, No. 143820, p. 355-p. 360.
Asanuma Hiroaki
Hamada Akihiro
Fox John
Fuji Oozx Inc.
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