A gasoline unit injector comprising an outer, electrically conductive bellows, defining a variable volume fluid chamber, for reciprocating a piston within a pressure chamber to increase the fuel pressure in various downstream cavities. Various bellows are disposed within such chambers and are deformable...http://www.google.com/patents/US4877187?utm_source=gb-gplus-sharePatent US4877187 - Unit injector for gasoline engines
