Fuel injection valve having injection rate increasing stepwise

Abstract

Abstract PURPOSE:To reduce combustion noise by providing a differential pressure type injection valve with a relief path serving to release fuel in the pressure chamber at the time of lifting a nozzle needle and providing a fuel supply path leading to a pressure chamber with a throttle, in a diesel engine. CONSTITUTION:Pressurized fuel from an injection pump flows into a pressure chamber 44 via paths 50, 52, 54, 56, 60, and 58, and a needle 18 is lifted, when the fuel pressure reaches valve opening pressure, to permit injection from an injection hole 26 to be started. Simultaneously, the fuel in the pressure chamber 44 is released via a relief path 62, and a gap 66, while the pressure in the pressure chamber is temporarily reduced since an axial groove 58 acts as a constriction, and thus the needle 18 is closed. In succession, when the pressure in the pressure chamber 44 exceeds the valve opening pressure due to the fuel flow thereinto from the constriction 58, the needle 18 is again lifted. Thereupon, a discharge stroke of the injection pump is advanced, and a discharge amount thereof is increased to permit the amount of fuel flowing into the pressure chamber via the groove 58 to be increased, whereby pressure drop is not so rapid, and hence drawing effect of the groove 58 is relatively reduced for stepwise increasing an injection rate.

Inventors

• 👤 Yasuo Sato
• 👤 康夫 佐藤

Bibliographic Details