초록 ▼

An improved fuel injector for providing precise control over injection timing, quantity and rate shape is provided which includes a piezoelectric actuator for compressing actuating fluid in an actuating fluid circuit which includes a fluid chamber positioned adjacent a needle valve element and fluid

An improved fuel injector for providing precise control over injection timing, quantity and rate shape is provided which includes a piezoelectric actuator for compressing actuating fluid in an actuating fluid circuit which includes a fluid chamber positioned adjacent a needle valve element and fluidically separate from a fuel supply circuit for supplying high pressure fuel for injection. Actuating fluid pressure in the chamber acts on the needle valve element to initiate injection. A fuel pressure balancing device is provided for balancing the fuel pressure forces acting on the needle valve element while the element is in both the closed and open positions thereby permitting the piezoelectric actuator to more precisely and predictably control the rate of movement, and the extent of movement, of the needle valve element.

대표청구항 ▼

[ We claim:] [1.] A fuel injector for injecting high pressure fuel into a combustion chamber of an internal combustion engine, comprising:an injector body containing an injector cavity, an injector orifice communicating with one end of said injector cavity and a fuel supply circuit for supplying fue

[ We claim:] [1.] A fuel injector for injecting high pressure fuel into a combustion chamber of an internal combustion engine, comprising:an injector body containing an injector cavity, an injector orifice communicating with one end of said injector cavity and a fuel supply circuit for supplying fuel for injection through said injector orifice;a needle valve element positioned in said injector cavity and including a first end positioned adjacent said injector orifice and a second end positioned opposite said first end, said needle valve element operable to be placed in an open position in which fuel may flow from said fuel supply circuit through said injector orifice into the combustion chamber and a closed position in which fuel flow through said injector orifice is blocked;a needle valve actuating means for moving said nozzle valve element between said open position and said closed positions, said needle valve actuating means including a piezoelectric actuator capable of contraction and expansion, an actuating piston associated with said piezoelectric actuator for advancing and retracting along with said piezoelectric actuator, and an actuating fluid circuit fluidically separate from said fuel supply circuit, said actuating fluid circuit including a first actuating fluid chamber positioned adjacent one end of said actuator piston, a second actuating fluid chamber positioned adjacent said needle valve element between said first and second ends, and a fluid passage connecting said first and said second actuating fluid chambers, wherein expansion of said piezoelectric actuator causes advancement of said actuator piston and pressurization of actuating fluid in said first and said second actuating fluid chambers, said actuating fluid pressure in said second actuating fluid chamber creating actuating fluid pressure forces acting on said needle valve element to cause movement of said needle valve element from said closed position toward said open position, wherein said needle valve element moves toward said piezoelectric actuator when moving toward said open position.