Variable displacement high pressure pump for fuel injection systems

A variable displacement high pressure pump for a common rail fuel injection .system comprising a low pressure pump having an outlet which is connected to a fuel supply inlet of each of a plurality of high pressure pumping elements;

• wherein each of the pumping elements has a pumping plunger that is mounted for reciprocation in a bore;
• wherein a variable volume pumping chamber, into which fuel from said low pressure pump is metered via said fuel supply inlet, is formed in said bore between an end of the pumping plunger and an outlet of the pumping element through which fuel pressurized by said pumping plunger is supplied to a common rail of a fuel injection system;
• wherein a rotary cam-driven roller tappet for producing pumping displacement of the pumping plunger is connected to each pumping plunger by a separated link in a manner permitting the pumping plunger to float relative to the roller, tappet during at least a portion of each pumping cycle;
• and wherein, for metering of fuel into the pumping chamber on a time-pressure basis, a single solenoid valve is provided for controlling a time metered flow of a constant-pressure supply of fuel from the outlet of the low pressure pump to the pumping chamber of each of the pumping elements, a check valve being located at each fuel supply inlet for preventing a return flow of fuel from the pumping chamber.

A variable displacement high pressure pump for a fuel injection system comprising a low pressure pump having an outlet which is connected to a fuel supply inlet of each of a plurality of high pressure pumping elements;

• wherein each of the pumping elements has a pumping plunger that is mounted for reciprocation in a bore;
• wherein a variable volume pumping chamber, into which fuel from said low pressure pump is metered via said fuel supply inlet, is formed in said bore between an end of the pumping plunger and an outlet of the pumping element through which fuel pressurized by said pumping plunger is supplied to an accumulator of a fuel injection system;
• wherein a rotary cam-driven roller tappet for producing pumping displacement of the pumping plunger is connected to each pumping plunger by a separated link in a manner permitting the pumping plunger to float relative to the roller tappet during at least a portion of each pumping cycle;
• and wherein, for metering of fuel into the pumping chamber on a time-pressure basis, a single solenoid valve is provided for controlling a time metered flow of a constant-pressure supply of fuel from the outlet of the low pressure pump to the pumping chamber of each of the pumping elements, a check valve being located at each fuel supply inlet for preventing a return flow of fuel from the pumping chamber.