Patent ID: 7350505
Filing Date: 2008-04-01
Classification: F02M

Abstract:
1. A common rail fuel pump for supplying fuel to a common rail fuel volume of an internal combustion engine, the fuel pump comprising: a pumping plunger that is reciprocable within a plunger bore provided in a pump housing under the influence of a cam drive arrangement to cause fuel pressurization within a pump chamber, wherein the drive arrangement includes a cam driven drive member coupled to the plunger to impart drive thereto, in use, so that the plunger performs a pumping cycle including a pumping stroke and a return stroke; an inlet metering valve operable to permit control of the quantity of fuel supplied to the pump chamber during the return stroke of the plunger; and an outlet valve for controlling the supply of pressurized fuel from the pump chamber, through an outlet passage to the common rail fuel volume during the pumping stroke in circumstances in which the inlet metering valve is closed; wherein the outlet passage communicates with a pump outlet that is substantially co-axially aligned with the inlet metering valve and the plunger; wherein the inlet metering valve is operable: i) to open during the return stroke to permit fuel to be supplied to the pump chamber from a low pressure source, and ii) to close part way through the return stroke in order to meter the quantity of fuel that is supplied to the pump chamber during the return stroke.