Valves and valve actuation – Valve – Materials
Reexamination Certificate
2000-05-12
2001-10-23
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Valve
Materials
C075S246000
Reexamination Certificate
active
06305666
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve seat made of Fe-based sintered alloy, as a structural member for internal combustion engines such as diesel engines, gasoline engines and the like.
2. Description of the Background
As disclosed in, for example, Japanese Unexamined Patent Publication No. 55-164063, Japanese Unexamined Patent Publication No. 58-178073 and the like, many valve seats have been proposed which are made of hard-particle dispersing type Fe-based sintered alloys as valve seats for internal combustion engines made of Fe-based sintered alloy. Recently, however, not only the production of internal combustion engines has greatly increased, but also the size of the engines has increased, which means that the valve seats, which are a structural member of the internal combustion engines, are compelled to operate in the environment of higher temperatures. However, when the conventional Fe-based sintered alloy valve seats and many other valve seats are used in the higher temperature environment of these engines, they are abruptly worn and their effective lives end in a relatively short period of time. A need continues to exist for valve seats of improved wear resistance, when exposed to higher temperature engine operating conditions.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide valve seats for internal combustion engines which exhibit excellent wear resistance, even when exposed to high temperature engine operating environments.
Briefly, this object and other objects of the present invention as hereinafter will become more readily apparent can be attained by valve seats for the internal combustion engine which are an Fe-based sintered alloy comprising, on a weight percent basis:
C:
0.5-2%,
Si:
0.05-1%
Co:
8-16%,
Cr:
2-8%,
Mo:
1.5-6%,
W:
1.5-6%,
Ni:
0.5-2%,
Nb:
0.05-1%, and
calcium fluoride: 1-15%, with the balance Fe and the inevitable impurities, wherein the Fe-based sintered alloy of the invention, having the above-described composition, has a structure in which Co-based alloy hard particles A, which comprise Co—Mo—Cr alloy and have high temperature wear resistance, and Cr-based alloy hard particles B, which comprise Cr—W—Co—Fe alloy and have ordinary temperature wear resistance, are dispersed and distributed in an alloy steel base in a total amount of 6-26 area percent when they are observed on a structural photograph recorded by an optical microscope. In the alloy, the ratio of hard particles A to total hard particles is 25-75 area percent. Further, calcium fluoride particles are dispersed and distributed in the alloy steel base at a ratio of 3-45 area percent, and the Fe-based sintered alloy has a porosity of 5-25%.
REFERENCES:
patent: 4204031 (1980-05-01), Takemura et al.
patent: 4233073 (1980-11-01), Takemura
patent: 4546737 (1985-10-01), Kazouka et al.
patent: 4671491 (1987-06-01), Kuroishi et al.
patent: 4734968 (1988-04-01), Kuroishi et al.
patent: 4915735 (1990-04-01), Motooka
patent: 5031878 (1991-07-01), Ishikawa et al.
patent: 3-225008 (1991-10-01), None
Keasel Eric
Mitsubishi Materials Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Shaver Kevin
LandOfFree
Valve seat made of Fe-based sintered alloy excellent in wear... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Valve seat made of Fe-based sintered alloy excellent in wear..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Valve seat made of Fe-based sintered alloy excellent in wear... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584481