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(11) | EP 2 146 087 A8 |
(12) | CORRECTED EUROPEAN PATENT APPLICATION |
Note: Bibliography reflects the latest situation |
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(54) | Fuel injection device for diesel engine, method for manufacturing the same, and valve unit |
(57) Wear and spalling are to be prevented at seat portions of a fuel injection device
for a diesel engine. In a fuel injection device for a diesel engine wherein a needle
valve is moved in the inside of a nozzle body to which fuel is supplied, to open or
close seat faces through which the nozzle body and the needle valve come into contact
with each other, thereby controlling injection of fuel from nozzle holes opening to
the nozzle body, the portion serving as the seat portion of the nozzle body and the
portion serving as the seat portion of the needle valve are formed of a nitrided alloy
steel, and a compound layer and a first layer in a diffusion layer are removed from
a surface of each of the seat portions. Since a second layer having high toughness
serves as a seat face, both wear resistance and fatigue resistance are improved and
particularly it is possible to prevent spalling of the seat portion of the nozzle
body.
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