Electrically-controlled fuel injection device - has sliding piston clamped by piezoelectric expansion for accurate control of injected quantity of fuel

摘要

The device comprises a combined pump and injection jet, with a sliding piston (3). This incorporates a stack (5) of piezoelectric discs (6) which are selectively supplied with an operating voltage to cause expansion of the disc stack (5) and clamp the piston (3) to the walls of the guide block. The piston (3) comprises a hollow element (4) containing the piezoelectric disc stack (5) positioned between the base of the hollow element (4) and a pressure plate (7) acted on by an anvil (8) via a rubber washer (9). The walls of the hollow element (4) are resilient to allow them to be pushed outwards to clamp the piston (3) upon expansion of the disc stack (5). The position of the piston can be varied to correspond to the amount of fuel to be injected, for accurate fuel dosing.