Patent ID: 6899083
Filing Date: 2005-05-31
Classification: F02D,F02M

Abstract:
1. In a high pressure common rail fuel supply system for delivering fuel to an internal combustion engine having a plurality of combustion cylinders and a respective plurality of fuel injectors fluidly connected to the common rail for injecting fuel into the cylinders at the pressure of the common rail for operating the engine at speeds ranging from cranking speed to a maximum speed, the system including a high pressure fuel supply pump with radial pistons reciprocating in pumping chambers and driven by the engine at a pump speed proportional to the engine speed, a method of pumping fuel to the common rail at a rail target pressure, comprising: continuously delivering feed fuel at a low pressure, to an inlet port of the pump; during operation of the engine in a low speed range below a transition speed, (a) (1) filling each pumping chamber during a charging phase, from inlet passages in fluid communication with the inlet port, (2) pressurizing the charged fuel in the pumping chambers by displacing the respective pistons during a discharge phase, and (3) delivering the discharged fuel to a discharge passageway in fluid communication with the common rail, and (b) maintaining the rail target pressure by continually diverting at least some of the pressurized fuel in at least one of the discharge passage or the common rail, to a low pressure sink; during operation of the engine in a high-speed range above the transition speed, (c) (1) partially filling each pumping chamber during the charging phase, from said inlet passages, (2) pressurizing the charged fuel in the pumping chambers by displacing the respective pistons during the discharge phase, and (3) delivering the discharged fuel to the discharge passageway, and (d) maintaining the rail target pressure by continually diverting at least some of the pressurized fuel in at least one of the discharge passage or the common rail, to the low pressure sink.