Intensified high-pressure common-rail supply pump

A method of receiving low-pressure fuel from a fuel source and of producing intensified high-pressure fuel from a pump of the type having a plurality of low-pressure bores with respective low-pressure pumping plungers movably disposed therein, an intensifier bore with an intensifier piston movably disposed therein and a high-pressure bore with a high-pressure pumping plunger movably disposed therein, the pump operating in alternating fuel-in-take and fuel-pumping phases of operation, said method comprising:

• transferring fuel into the low-pressure and high-pressure bores during the in-take phase of operation;
• transferring fuel from the low-pressure bores into the intensifier bore during the pumping phase of operation;
• urging the intensifier piston into a bottom dead center position within the intensifier bore during the in-take phase of operation whereby fuel is displaced from the intensifier bore into the low-pressure bores, the low-pressure plungers are urged into a bottom dead center position by the displaced fuel and fuel is permitted to enter the low-pressure bores;
• and
• moving the low-pressure plungers from the bottom dead center position to a top dead center position during the pumping phase of operation whereby fuel from the low-pressure bores is displaced into the intensifier bore, urging the intensifier piston into a top dead center position, and the high-pressure pumping plungers are urged into a top dead center position such that the fuel within the high-pressure bore is pressurized and discharged from the high-pressure bore for subsequent use.

A fuel-pressure intensifier assembly for use with a fuel pump sub-assembly of the type having a pump body defining a cam box, a rotary drive shaft with at least one cam attached thereto and disposed within the cam box for driving the intensifier assembly in alternating fuel-intake and fuel-pumping phases of operation, at least one low-pressure fuel supply, at least one cam follower assembly disposed within the cam box and driven by the cam, said intensifier assembly comprising:

• a body which defines at least one low-pressure bore, a metered fuel circuit, at least one intensifier bore fluidly connected to said low-pressure bore and selectively fluidly connected to said metered fuel circuit, a poppet-valve assembly bore, at least one high-pressure bore in selective fluid communication with said metered fuel circuit via said poppet-valve bore and an outlet port in selective fluid communication with said high-pressure bore via said poppet-valve bore;
• a fuel pre-metering device for receiving fuel from the low-pressure fuel supply and delivering metered low-pressure fuel to said metered fuel circuit;
• a poppet-valve assembly movably disposed within said poppet-valve bore for permitting selective fluid communication between said metered fuel circuit and said high-pressure bore and between said high-pressure bore and said outlet port whereby low-pressure fuel may enter said high-pressure bore during said in-take phase of operation and whereby high-pressure fuel may exit said high-pressure bore during said pumping phase of operation;
• at least one low-pressure pumping plunger, each of said plungers being movably disposed within one of said low-pressure bores and being driven by one of the cam follower assemblies whereby fuel is delivered into said low-pressure bore during said in-take phase of operation and pumped therefrom into said intensifier bore during said pumping phase of operation;
• an intensifier piston movably disposed within said intensifier bore, said piston being driven in a first direction by fuel displaced from said low-pressure bore during said pumping phase of operation;
• a piston-bias member for resiliently urging said piston in a second direction which is opposite to said first direction, said piston-bias member being disposed within said intensifier bore;
• means for venting fuel from the intensifier piston to the fuel supply;
• and
• a high-pressure pumping plunger movably disposed within at least one of said high-pressure bore and said intensifier bore and presenting a surface area toward said outlet port, said high-pressure pumping plunger surface area being smaller than said low-pressure pumping plunger surface area, said high-pressure pumping plunger being driven by said intensifier piston such that fuel is transferred into said high-pressure pumping plunger bore via said poppet-valve assembly during said in-take phase of operation and such that fuel is pumped into said outlet port via said poppet-valve assembly during said pumping phase of operation.