| 摘要 |
PURPOSE: A variable injector for a diesel engine is provided to adjust the length of a nozzle of the injector according to the driving condition of the engine, thereby improving the fuel ratio and reducing the smoke. CONSTITUTION: A variable injector for a diesel engine is composed of a body(31) having a receiving space(36) at the lower side, an inner nozzle body(40) receiving a needle(46) at inner and lower side and having an injection nozzle(47) at the lower end, a lower cap(50) having a spring chamber(51) at the center of the upper side, an NTP(Nozzle Tip Protrusion) control spring(49), and an NTP control chamber(36). A solenoid opening/closing unit comprising a ball member(32), a pilot needle(33), an electromagnet(34), and a valve spring(35) is formed to open/close a fuel return path according to the signal from the electronic control unit. After the inner nozzle body(40) is inserted into the receiving space(36), the lower cap fixes the inner nozzle body(40). The NTP control spring(49) is received in the spring chamber to resiliently support a stopper(48) of the inner nozzle body(40). The inner nozzle body(40) is operated downwardly by the fuel pressure applied from the inlet path(38). When the engine is rotated at a high speed, the NTP is increased with the pressure supplied to the NTP control chamber(37) pressing the NTP control spring(49). When the engine is rotated at a middle or low speed, the NTP is decreased with the force of the NTP control spring(49) formed larger than the pressure supplied to the NTP control chamber(37).
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