Internal combustion engine fuel injector for common rail system has control valve and hydraulic circuit receiving high-pressure fuel which passes to injection valve and working spaces over pistons

摘要

The fuel injection system (1) incorporates a high- pressure feed line (5) and a high-pressure injection line (6) receiving fuel from the common rail fuel supply (3). A valve actuator (31) presses on a rod (61) which holds a first piston (36) forming part of a hydraulic coupling (35). High-pressure fuel may flow to a first chamber (80) over the first piston. The fuel flows from a chamber under the piston through a connecting channel (84) to a second chamber (83) under a second piston (37). This presses on a rod (63) which may open a control valve (41) with a conical valve head (53) engaging a conical valve seat. When the valve is open fuel may flow out through a leakage channel (55). The injection valve (9) has a needle (11) with two conical surfaces (12,15) controlling the flow of fuel from an annular chamber (14) to the injection nozzle (13).