| 摘要 |
PURPOSE:To suppress combustion noise and to prevent deterioration of the engine stability by forming a tapered surface, the angle of taper increasing as approaching the injection port, at the throttle part of valve element and the injection port and thereby always maintaining good preliminary injection. CONSTITUTION:The angle theta1 of a tapered surface 13A at the injection port 6 is formed larger than that theta2 of the tapered surface 13B at the throttle part 4. Accordingly ring-shaped gap 8 between the jet hole 6 and throttle part 4 increases proportional to the increment in the lift of valve element 2. As a result, eventual production of carbon layer 14 attached to the valve seat 1, jet hole 6 or throttle part 4 does not hinder microjetting of the fuel in valve chest 9 through this increasing gap 8 even with a minor lift because the width of the gap 8 increases as the valve element 2 lifts. Thus a secure preliminary injection is obtained. |
