Piezoelectric fuel injector valve

A liquid fuel injector valve for an internal combustion engine, said valve comprising:

• a. a generally cylindrical valve body adapted to contain liquid fuel therein under pressure, said valve body having a liquid fuel inlet port and a liquid fuel outlet port;
• b. a valve needle movable axially between a first position where said needle closes said outlet port and a second position where said outlet port is open;
• c. a piezoelectric element in the form of a stack of coaxial piezoelectric discs cooperative with said needle for effecting movement of said needle to said second position in response to an electrical potential imposed across said element;
• d. a spring cooperative with said element to maintain said needle in said first position in the absence of said imposed potential;
• e. an axially extending passageway through said stack;
• f. a piston positioned within said passageway and having a portion in engagement with said spring, said piston attached to said stack for axial movement therewith;
• and
• g. a liquid chamber positioned axially between said piston and said needle wherein movement of said piston in a direction away from said outlet port effects a reduction in liquid pressure within said chamber thereby creating a differential pressure across said needle in a manner to effect said movement of said needle to said second position.