Patent ID: 8839763

Claim:
A dual fuel injector comprising: an injector body that defines a liquid fuel inlet, a gaseous fuel inlet, a liquid nozzle outlet set, a gaseous nozzle outlet set, a liquid drain outlet and a gaseous drain outlet, and having disposed therein a first control chamber and a second control chamber; a liquid direct operating check valve with a liquid check valve member positioned in the injector body with a closing hydraulic surface exposed to fluid pressure in the first control chamber, and being movable between a closed position in contact with a first seat to fluidly block the liquid fuel inlet to the liquid nozzle outlet set, and an open position out of contact with the first seat to fluidly connect the liquid fuel inlet to the liquid nozzle outlet set; a gaseous direct operating check valve with a gaseous check valve member positioned in the injector body with a closing pneumatic surface exposed to fluid pressure in the second control chamber, and being movable between a closed position in contact with a second seat to fluidly block the gaseous fuel inlet to the gaseous nozzle outlet set, and an open position out of contact with the second seat to fluidly connect the gaseous fuel inlet to the gaseous nozzle outlet set; a first control valve member movable between a closed position at which the first control chamber is fluidly blocked to the liquid drain outlet, and an open position at which the first control chamber is fluidly connected to the liquid drain outlet; a second control valve member movable between a closed position at which the second control chamber is fluidly blocked to the gaseous drain outlet, and an open position at which the second control chamber is fluidly connected to the gaseous drain outlet; and wherein the liquid check valve member is fluidly isolated from both the gaseous fuel inlet and the gaseous drain outlet.