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. an axially extending passageway through said stack;
• e. a piston positioned within said passageway and attached to said stack for axial movement therewith;
• f. 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;
• and
• g. a vaulted spring washer cooperative with said element and said piston such that movement of said element in response to said potential effects the application of a force against said washer in a manner to effect the vaulting of said washer in the direction of movement of said element and such that, upon removal of said potential, a reverse vaulting of said washer is effected biasing said valve needle toward its closed position.