Fluid pump control apparatus and method

Abstract

An amount of pressurized fluid is pumped by a high-pressure fluid pump to a common rail in an engine by using a multi-functional control circuit (ECU) that improves the controllability of fluid pumped to the common rail such that a target pressure in the common rail is achieved notwithstanding the loss of fuel injected from the common rail into the engine's cylinders nor the variety of pressure losses or deviations occurring throughout the system. The ECU sets a base fluid pumping amount based on a target value of pressure in the common rail and an amount of fluid ejected from the common rail. The ECU also calculates a fluid pumping amount required to cause the actual pressure of the common rail to follow a change of a target pressure of the common rail according to the amount of change of the target pressure. The ECU sets the sum of the basic fluid pumping amount, the required fluid pumping amount and a carried-over amount of fluid, as a set value of the fluid pumping amount to achieve target pressure in the common rail. If the set value of the fluid pumping amount exceeds a predetermined capacity of the fluid pump, the ECU sets a difference between the set value of the fluid pumping amount and the predetermined capacity as the carried-over amount of fluid that is carried over to a next setting of fluid pumping amount, thereby reflecting the difference therebetween in a next set value of the fluid pumping amount so that the target pressure in the common rail may be achieved via a plurality of pumping sequences including any carried over fluid amounts.