Double pulsing electronic unit injector solenoid valve to fill timing chamber before metering chamber

Claim 1

A fuel injector having an injection stroke and a retraction stroke for use in an internal combustion engine, said injector comprising: an injector body having a bore formed therein; a timing plunger disposed at a first location within said bore, said timing plunger being freely slidable within said bore during the retraction stroke; a metering piston slidably disposed at a second location within said bore; a timing chamber defined in said bore between said timing plunger and said metering piston; means for biasing said metering piston away from said timing plunger with a variable force; a metering chamber defined in said bore below said metering piston, said metering chamber and said timing chamber having minimum volumes at the beginning of the retraction stroke, said volumes being increasable as said injector travels through the retraction stroke; a passage formed in said injector body for providing continuous fuel communication to said metering chamber; and control means for permitting and inhibiting the passage of fuel into said timing chamber, wherein said control means permits the passage of fuel into said timing chamber at the beginning of the retraction stroke thereby forcing said timing plunger away from said metering piston and decreasing said biasing force of said biasing means, and further wherein said control means inhibits the passage of fuel into said timing chamber near the end of the retraction stroke thereby forcing a predetermined quantity of fuel into said metering chamber and causing said metering piston to move toward said timing plunger, whereby a predetermined quantity of fuel is metered into said metering chamber after said force of said biasing means has decreased, said predetermined quantity of fuel being thereafter injected into the engine during the subsequent injection stroke.

Claim 8

A method of metering a predetermined quantity of fuel into a fuel injector during the retraction stroke for subsequent injection into an internal combustion engine at low engine rpm, wherein the injector includes a metering chamber in continuous fluid communication with a pressurized fuel source, a timing chamber, and control means for controlling the delivery pressurized fuel to either the timing chamber or the metering chamber, the method comprising the steps of: (a) determining the engine rpm; (b) performing the steps (c)-(f) so long as said the engine rpm is less than a predetermined value; (c) determining the beginning of the retraction stroke; (d) enabling said control means to deliver pressurized fuel to said timing chamber at the beginning of the retraction stroke; (e) disabling said control means from delivering pressurized fuel to said timing chamber near the end of the retraction stroke thereby enabling fuel to enter said metering chamber; and (f) enabling said control means to deliver pressurized fuel to said timing chamber after a predetermined volume of fuel has been metered into said metering chamber.

Claim 9

A method of metering a predetermined quantity of fuel into a fuel injector during the retraction stroke for subsequent injection into an internal combustion engine at low engine rpm, wherein the injector includes a metering chamber in continuous fluid communication with a pressurized fuel source, a timing chamber, and control means for controlling the delivery pressurized fuel to either the timing chamber or the metering chamber, the method comprising the steps of: (a) determining the engine rpm; (b) performing the steps (c)-(f) so long as said the engine rpm is less than a predetermined value; (c) determining the beginning of the retraction stroke; (d) enabling said control means to deliver pressurized fuel to said timing chamber at the beginning of the retraction stroke; (e) disabling said control means from delivering pressurized fuel to said timing chamber near the end of the retraction stroke thereby enabling fuel to enter said metering chamber; and (f) enabling said control means to deliver pressurized fuel to said timing chamber after a predetermined volume of fuel has been metered into said metering chamber.