| 摘要 |
PURPOSE:To ensure a necessary maximum injection amount further with control accuracy improved at the time of low speed rotation by providing an injection amount control means which controls a fuel injection amount in a manner wherein the higher is generated a fuel pressure the larger ratio of an increase of the fuel pressure to an increase of the fuel injection amount per one time is increased. CONSTITUTION:An electromagnetic valve 27 is energized with a valve plate 33b rising, when a fine hole 28b is opened, high pressure fuel in a back pressure chamber 28a, passing through the hole 28b, is allowed to flow out in a valve chamber 29. Accordingly, a pressure in the chamber 28a is decreased, and an injection valve unit 26 is retracted against resultant force of an urging spring 36 and a control spring 44 by a fuel pressure with seal parts 26b, 30c of an injection nozzle opened. Fuel is injected from a clearance between a nozzle hole 30b and a straight part 26c, while a moving amount of the valve unit 26 is small generated, and from a clearance with a tapered part 26e when the moving amount is increased. Now when a fuel pressure in an accumulator chamber 38 is increased, the spring 44 is contracted by moving an upper spring seat 35 with a set load of the spring 36 decreased by that contraction, and urging force to a closing side of the valve unit 26 is weakened with the nozzle larger opened.
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