FUEL INJECTION NOZZLE FOR DIESEL ENGINE

PURPOSE:To permit to prevent sudden change of a lift immediately after opening a valve by communicating an oil pressure chamber, formed at the back side of a needle valve, with an independent oil pressure source through a choke. CONSTITUTION:Fuel in a pump housing for the fuel injection pump 22 is being introduced into the oil pressure chamber 29 at the back side of a free piston 27. When the free piston 27 rises, the fuel in the oil pressure chamber 29 is compressed, therefore, a fuel pressure is increased and, as a result, the rising of the free piston is restricted. After the fuel pressure in the oil pressure chamber 29 has been increased, the fuel flows out of the oil pressure chamber 29 gradually under being choked by a choking path 33, therefore, the free piston 27 rises gradually. Accordingly, the lifting speed of the needle valve 14 is restricted by the outflow speed of the fuel, which is generated by the choking of the choking path 33, and the abrupt change of the lift may be avoided.