FUEL-CONTROL SERVO VALVE, AND FUEL INJECTOR PROVIDED WITH SUCH SERVO VALVE

摘要

A fuel control servo valve and a fuel injector having the same are provided to improve balance of the servo valve and operation and durability of an injection device. A servo valve(7) for fuel control includes an actuator unit(14), valve bodies(8,28), and an opening/closing unit(17). The valve bodies include a stem(33) extended in a longitudinal axis direction, and provided with an internal passage(26) for communication of fuel. The valve bodies are mounted on a fixed position. The opening/closing unit is coupled to a lengthwise outer surface(34) in a substantially fluid-tight way such that the opening/closing unit is movable between an end-of-travel closing position and an end-of-travel opening position by the movement of the actuator unit. In the end-of-travel closing position, an outlet port is closed such that the axial resultant pressure by the pressure of fuel becomes zero. The internal passage includes at least two radial channels(39) connected to the outlet port via a lengthwise outer surface of the stem. Each radial channel has a first portion(42) having a calibrated length and diameter.