Gaseous and liquid fuel injector

A hydraulically actuated dual fuel injector for an internal combustion engine. More particularly, the application pertains to a hydraulically actuated injector for injecting controlled quantities of a first fuel and of a second fuel into an internal combustion diesel engine at different times. A dual fuel injector comprising: (a) an injector body; (b) an inlet port in the injector body for enabling pressurized hydraulic fluid from a hydraulic fluid source to be introduced into the interior of the injector body, the hydraulic fluid being of sufficient pressure to maintain injection valves in the injector body in a closed position until actuated; (c) a first inlet port in the injector body for enabling a first fuel to be introduced into the interior of the injector body; (d) a first injection valve in the injector body connected to the second inlet port for controlling injection of the first fuel from the injector through a first fuel ejection port; (e) a second inlet port in the injector body for enabling a second fuel to be introduced into the interior of the injector body; (f) a second injection valve in the injector body connected to the second inlet port for controlling injection of the second fuel from the injector through a second fuel ejection port; (g) a first control valve which causes the hydraulic fluid to actuate the first injection valve; (h) a second control valve which causes the hydraulic fluid to actuate the second injection valve; (i) a metering device in the injector body for metering the amount of first fuel injected by the first injection valve; and (j) a seal in the injector body which prevents leakage of the second fuel into the first fuel.