Fuel injection device

Claim 1

A fuel injection device for injecting pressurized fuel into a combustion chamber of an internal combustion engine, comprising: a pump housing; a pump cylinder provided in said pump housing; a pump plunger fitted in said pump cylinder to be reciprocal therein, said pump plunger defining a fuel pressurizing chamber for receiving the fuel in said pump cylinder; pressurizing means for reciprocating said pump plunger in said pump cylinder in synchronism with operation of the engine, thereby pressurizing the fuel in the fuel pressurizing chamber to supply the pressurized fuel to the combustion chamber; and an accumulator for accumulating part of the pressurized fuel delivered from the fuel pressurizing chamber to the combustion chamber, said accumulator including cylinder means having a first cylinder portion and a second cylinder portion, piston means having an accumulator piston, said accumulator piston having first and second piston portions for reciprocating in said first and second cylinder portions, respectively, said first piston portion defining an accumulation chamber in said first cylinder portion which receives the part of the pressurized fuel pressurized by the fuel pressurizing chamber, said second piston portion being pivotal in said second cylinder portion and defining a fluid-tight chamber filled with a fluid therein, said second cylinder portion having a spill port, the spill port being capable of communicating with the fluid-tight chamber and closed by a predetermined position of said second piston portion upon pivotal movement of said second piston portion, whereby the fluid in the fluid-tight chamber is spilled through the spill port when the spill port is opened, so that said accumulator piston is moved by a pressure of the pressurized fuel in the accumulation chamber so as to increase a volume of the accumulation chamber, and the fluid-tight chamber is closed when the spill port is closed, so that movement of said accumulator piston is interrupted, supplying means for supplying a pressurized fluid whose pressure is adjusted in accordance with a given operating state of the engine, and adjusting means having a fluid pressure chamber which receives the pressurized fluid so as to adjust a pivotal position of said second piston portion in accordance with a variation in pressure of the pressurized fluid in the fluid pressure chamber, thereby adjusting an axial displacing distance of said accumulator piston until said second piston portion closes the spill port.