US 4,069,800 AGranted

Fuel injection apparatus

AssigneeDiesel Kiki Co., Ltd.

InventorsFumio Kanda, Nobuhiro Kaibara, Seibi Ohki, Kazuo Okamoto, Akira Suzuki

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Abstract

A servo piston is driven to compress fuel in a pressure chamber which communicates with a needle valve which is spring biased to block communication between the pressure chamber and a fuel injection nozzle. When the fuel pressure exceeds a value equivalent to the preload of the spring, the pressurized fuel moves the needle valve off its seat so that fuel from the pressure chamber is injected into an engine through the injection nozzle. Further movement of the servo piston unblocks a port to allow fuel at supply pressure to act on the needle valve in the same direction as the spring to sharply seat the needle valve and cleanly terminate fuel injection. Further movement of the servo piston uncovers another port so that the pressure chamber is depressurized through connection with the supply and the needle valve is firmly held on its seat.

Claims20

Dependent claims

A fuel injection apparatus comprising:

a body;
a piston member slidable in the body to define therewith a variable volume pressure chamber;
an injection valve means exposed to a fuel pressure in the pressure chamber and slidable in the body to control communication between the pressure chamber and a fuel injection nozzle;
the body further defining a spring chamber communicating with the injection valve member;
a spring disposed in the spring chamber urging the injection valve member to block communication between the pressure chamber and the fuel injection nozzle;
drive means to move the piston member in an inlet stroke to increase a volume of the pressure chamber and in an injection stroke to decrease the volume of the pressure chamber;
first valve means to communicate the pressure chamber with a fuel supply passageway during the inlet stroke;
the fuel pressure in the pressure chamber increasing during a first portion of the injection stroke so as to move the injection valve member against a force of the spring to communicate the pressure chamber with the fuel injection nozzle;
second valve means to communicate the spring chamber with the fuel supply passageway during a second part of the injection stroke so that a fuel pressure in the spring chamber acts on the valve member in a same direction as the force of the spring;
third valve means to communicate the spring chamber with a fuel return passageway during the inlet stroke;
and
fourth valve means to communicate the pressure chamber with the fuel supply passageway during a third portion of the injection stroke.

9 more elements

Dependencies are inferred from the claim text.