Piezoelectric fuel injector valve

Claim 1

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.