Solenoid operated pump-line-nozzle fuel injection system and inline pump therefor

Claim 1

A pump-line-nozzle fuel injection system comprising a high pressure inline fuel pump having a plurality of high pressure pumping cylinder units, each of which comprises a plunger assembly reciprocatingly mounted within a cylinder bore, and a low pressure fuel supply pump connected to each cylinder; wherein each plunger assembly comprises a timing plunger, a floating metering plunger, and a cam for driving said timing plunger, a variable volume timing chamber being defined in said cylinder bore between an end of the timing plunger and a first end of the metering plunger, and a variable volume metering chamber being defined in said cylinder bore between a second end of the metering plunger and a delivery valve at an outlet end of the respective cylinder; wherein said supply pump is connected to a group of said high pressure pumping cylinder units via a fueling solenoid valve means for controlling flow to the metering chamber of the high pressure pumping cylinder units of said group via a fuel supply branch of a fuel supply flow path from the supply pump containing a check valve between the fueling solenoid means and each metering chamber in a manner enabling a flow of fuel to enter said metering chamber during a retraction stroke of the plunger assembly; wherein said timing chamber is connected to a supply of timing fluid via a timing flow path containing a timing solenoid valve means for controlling flow to the timing chamber of the high pressure pumping cylinder units of said group via a second check valve located between the timing solenoid valve means and each timing chamber in a manner enabling a flow of timing fluid to enter said timing chamber during the retraction stroke of the plunger assembly; wherein electronic control means is provided for opening and closing said fueling and timing solenoid valve means for providing a required amount of fuel to said metering chamber and a required amount of timing fluid to said timing chamber during the retraction stroke of the plunger assembly of each of the pumping cylinder units of the group; wherein said delivery valve is responsive to the pressure of fuel in said metering chamber for enabling delivery of fuel to a respective fuel injector via a high pressure delivery line when the pressure of fuel in said metering chamber exceeds a predetermined value during a compression stroke of the plunger assembly; and wherein the cams for the high pressure pumping cylinder units of said group are configured relative to each other as a means for producing injection of fuel from each pumping cylinder by compression of fuel in said metering chamber and for producing the retraction stroke of each plunger assembly of the group while all of the other plunger assemblies of the group are in a maximally inwardly displaced, end of the compression stroke position.