Fuel injection nozzle

摘要

A fuel injection nozzle of this invention includes a nozzle housing which defines therein a fuel sump chamber, stepped cylinder bore and fuel passage connected at one end to the sump chamber and at the other end to a smaller diameter bore section of a stepped bore. A stepped plunger is fitted into the stepped cylinder bore to define a pump chamber communicating with the fuel passage and a main fuel chamber into which the main fuel is supplied from a fuel injection pump. An auxiliary fuel is supplied from a feed pump through the fuel passage into the sump chamber and pump chamber. A nozzle needle is located within the nozzle housing and is responsive to a fuel pressure within the sump chamber to cause it to be lifted to permit an injection hole to be opened. The nozzle needle is urged under a predetermined force of a pressure spring in a direction in which the injection hole is blocked. The urging force of the pressure spring is set to be greater than the pressure of the auxiliary fuel supplied from the feed pump and smaller than the pressure of the main fuel supplied from the fuel injection pump. The main fuel chamber, when the plunger is moved a predetermined distance responsive to the fuel pressure within the main fuel chamber, is permitted to be connected to the fuel passage.