| 摘要 |
PURPOSE:To permit to reduce effectively the noise of an engine which is due to the delay of ignition by a method wherein the atomization of the fuel injected out of the nozzle is promoted without deteriorating the injection rate remarakbly due to the adhesion of carbon. CONSTITUTION:The outer peripheral surface 7a of a small diametral column 7 for a needle valve 6 is provided with a plurality of surface machining sections 9 with predetermined spaces along the circumferential direction thereof in order to divide an annular gap 8 into wide sections 8a and narrow sections 8b. Respective surface machining sections 9 are flat surfaces formed by cutting partially the arc of the outer peripheral surface 7a of the small diametral column 7 and are ground by a surface grinding work in parallel to the axis of the needle valve 6. According to this method, a perfect clogging due to the accumulation of carbon will never be generated in the wide sections 8a. |
