초록 ▼

A fuel injection system for an internal combustion engine of the type so-called unit injector wherein the overflow of fuel under high pressure from a plunger chamber defines the fuel injection cut-off. In order to perform the sharp cut-off, an overflow passage is increased in cross sectional area, a

A fuel injection system for an internal combustion engine of the type so-called unit injector wherein the overflow of fuel under high pressure from a plunger chamber defines the fuel injection cut-off. In order to perform the sharp cut-off, an overflow passage is increased in cross sectional area, and in order to prevent the overflow from the plunger chamber while the fuel is being charged into it, a flow control means such as a spool type directional control valve is inserted into the overflow passage so that when the fuel is being charged into the plunger chamber the communication between the overflow passage and a fuel tank may be positively interrupted. In addition, in order to prevent the fuel recharge with the resulting secondary injection, a flow control means such as a solenoid operated directional control valve is inserted into a fuel supply line communicating between a fuel delivery source and the plunger chamber such that as long as the fuel injection continues or when the fuel injection is zto be completed, the communication between the plunger chamber and the fuel delivery source may be completely cut off.

대표청구항 ▼

In a fuel injection system for an internal combustion engine of the type comprising: at least one fuel injection nozzle attached to the engine for injecting fuel under high pressure into the engine; means operated in synchronism with the operation of the engine for charging the fuel to said fuel inj

In a fuel injection system for an internal combustion engine of the type comprising: at least one fuel injection nozzle attached to the engine for injecting fuel under high pressure into the engine; means operated in synchronism with the operation of the engine for charging the fuel to said fuel injection nozzle in a quantity depending upon the operating condition of the engine, said fuel charging means including a first cylinder, a plunger slidably fitted into said first cylinder for reciprocal movement therein and defining in said first cylinder a plunger chamber which is communicated with said fuel injection nozzle, a second cylinder having a bore diameter greater than that of said first cylinder, a piston slidably fitted into said second cylinder for reciprocal movement therein and defining in said second cylinder a piston chamber, means for operatively connecting said piston to said plunger in such a relation that the volume of said plunger chamber decreases as the volume of said piston chamber increases, a fuel overflow port formed through the cylinder wall of said first cylinder, a fuel overflow passage formed in said plunger and adapted to establish the communication between said plunger chamber and said fuel overflow port when said plunger is in a predetermined position near the end of the forward stroke of said plunger; a fuel supply means including a fuel tank, means for pumping fuel from said fuel tank and delivering fuel under a predetermined pressure and a fuel supply line for communicating said pumping means with said plunger chamber of said fuel charging means; a fuel overflow line connected to said fuel overflow port of said fuel charging means; and fluid control means for admitting and exhausting working fluid into and from said piston chamber in synchronism with the engine operation and depending upon the operating condition of the engine thereby controlling the reciprocal movement of said piston; an improvement comprising a valve means provided in said fuel overflow line for opening or closing said fuel overflow line and a valve operating means for operating said valve means in such a way that said valve means closes said fuel overflow line at least when the fuel is being charged into said plunger chamber through said fuel supply line and opens said fuel overflow line at least when said plunger in the forward stroke has been displaced to said predetermined position.