Hydraulically-actuated fuel injector with direct control needle valve

摘要

A fuel injection system includes a plurality of hydraulically actuated fuel injectors with direct control needle valves. Each injector has an injector body that defines an actuation fluid inlet, a fuel supply passage and a needle control chamber. A needle valve member is movably mounted in the injector body and has a closing hydraulic surface exposed to pressure in the needle control chamber. Each injector also includes a relatively slow moving actuation fluid control valve member and a relatively fast moving needle control valve member. A source of low pressure fluid is connected to the fuel supply passage, and a source of high pressure fluid is connected to the actuation fluid inlet.