Solenoid operated unit injector having distinct timing, metering and injection periods

A fuel injector having variable metering and timing, comprising:

• (a) an injector body containing an injector cavity and including a fluid timing circuit and a fluid metering circuit communicating with the injector cavity, and further including an injector nozzle communicating with one end of the injector cavity;
• (b) valve means movable between an open position wherein fluid may flow therethrough to both said fluid timing circuit and said fluid metering circuit, and a closed position wherein fluid is blocked from flowing therethrough to both of said circuits;
• and
• (c) plunger means mounted for reciprocal movement within the injector cavity, said plunger means comprising inner and outer plunger sections, a variable volume timing chamber being formed in said injector cavity between said inner and outer plunger sections and a variable volume injection chamber being formed in said injector cavity between said inner plunger section and an end of the injector cavity;
• wherein said plunger means is operable to be placed in a first condition establishing a timing period during which fluid may flow through said timing circuit into said timing chamber, but fluid is blocked thereby from flowing through said metering circuit into said metering chamber, is operable to be placed in a second condition establishing a metering period, distinct from said timing period, during which said flow into said timing chamber is blocked thereby and fluid may flow through said metering circuit into said metering chamber, and is operable to be placed in a third condition wherein fluid flow through both circuits to both said chambers is blocked thereby for producing injection of the fluid in said metering chamber through the injector nozzle;
• and wherein the valve means is operable independent of the condition of said plunger means;
• whereby said plunger means determines the chamber to which fluid passing through said valve means is delivered and said valve means is operable to control the amount of fluid delivered to the chamber determined by the condition of the plunger means.