PURPOSE: To improve the high-speed response of a fuel injection valve without damaging the magnetic characteristics of whole magnetic circuit members by forming a layer of high electric resistance only on the surface parts of a york, a core, a plunger, and the like composing the magnetic circuit members of an electromagnetic valve.
CONSTITUTION: By using electromagnetic stainless steel on the market (representative composition: 13 Cr-Fe), a york 2, a core 3 and a plunger 4 are processed by parallel knurling work 10 with 1mm pich and 0.5mm groove depth on their surface layer parts, and magnetically annealed at 1,000°C and 1h to be constructed as an electromagnetic valve. The response speed of the electromagnetic valve is fairly improved, especially improving the time required for opening even by 30%. The flow line of the eddy-current is much prolonged, and highly improved in the resistance by the knurling work. The eddy-current as well as the delay of magnetic flux are also enormously reduced to improve the response of magnetic flux. The response speed of the electromagnetic valve processed by gilding and diffusion is improved at the same time.
MITSUOKA KATSUYA
MOMONO MASAYOSHI
