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Mechanical Science HandbooksMechanical Science Handbooks 10000 Part 6

Tham khảo tài liệu 'mechanical science handbooksmechanical science handbooks 10000 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Diesel Engine Fundamentals DOE-HDBK-1018 1-93 DIESEL ENGINE SPEED FUEL CONTROLS AND PROTECTION Figure 26 Fuel Injector Cutaway Rev. 0 Page 31 ME-01 DIESEL ENGINE SPEED DOE-HDBK-1018 1-93 Diesel Engine Fundamentals FUEL CONTROLS AND PROTECTION The motion of the injector rocker arm not shown is transmitted to the plunger by the injector follower which bears against the follower spring. As the plunger moves downward under pressure of the injector rocker arm a portion of the fuel trapped under the plunger is displaced into the supply chamber through the lower port until the port is closed off by the lower end of the plunger. The fuel trapped below the plunger is then forced up through the central bore of the plunger and back out the upper port until the upper port is closed off by the downward motion of the plunger. With the upper and lower ports both closed off the remaining fuel under the plunger is subjected to an increase in pressure by the downward motion of the plunger. When sufficient pressure has built up the injector valve is lifted off its seat and the fuel is forced through small orifices in the spray tip and atomized into the combustion chamber. A check valve mounted in the spray tip prevents air in the combustion chamber from flowing back into the fuel injector. The plunger is then returned back to its original position by the injector follower spring. On the return upward movement of the plunger the high pressure cylinder within the bushing is again filled with fresh fuel oil through the ports. The constant circulation of fresh cool fuel through the injector renews the fuel supply in the chamber and helps cool the injector. The fuel flow also effectively removes all traces of air that might otherwise accumulate in the system. The fuel injector outlet opening through which the excess fuel returns to the fuel return manifold and then back to the fuel tank is adjacent to the inlet opening and contains a filter element exactly the same as the one on the fuel