Method for controlling fuel rail pressure

A fuel delivery system comprising:

• a fuel rail adapted to deliver fuel to fuel injectors of an automotive vehicle, a fuel pump adapted to deliver fuel to said fuel rail, a fuel pressure sensor adapted to measure the fuel rail pressure, a low-pass filter adapted to filter the output of said fuel pressure sensor to filter out pulses due to the opening and closing of the fuel injectors, and a fuel pump motor controller having:
• a feed forward controller adapted to provide a feed forward signal having fuel pump motor control parameters based upon a set-point fuel pressure and the average fuel flow through said system;
• a first summing junction adapted to compare the fuel rail pressure to the set-point fuel pressure and to generate an error value based upon the difference between the fuel rail pressure and the set-point fuel pressure;
• a feed back controller adapted to receive the error value and to generate a feed back control signal;
• a second summing junction adapted to receive the feed back control signal from said feed back controller and the feed forward control signal from the feed forward controller and to modify the fuel pump motor control parameters of the feed forward control signal based upon the feed back control signal to generate a motor controller signal;
• and
• a fuel pump motor controller driver adapted to receive the motor controller signal and to control the speed of said fuel pump based upon the motor controller signal.

A method of controlling the fuel pressure within a fuel delivery system having a fuel pump which delivers fuel to a fuel rail and fuel injectors of an internal combustion engine comprising:

• providing a set-point fuel pressure;
• providing the estimated average fuel flow through the system;
• generating a feed forward control signal based upon the set-point fuel pressure and the average fuel flow;
• measuring the fuel rail pressure with a fuel pressure sensor;
• comparing the fuel rail pressure to the set-point fuel pressure and generating an error signal based upon the difference between the fuel rail pressure and the set-point fuel pressure;
• modifying the feed forward control signal based upon the error signal thereby generating a motor controller signal and sending the motor control signal to the fuel pump motor;
• detecting pulses in the signal from the fuel pressure sensor to establish when the fuel injectors open and close;
• measuring the time between when an injector opens and closes to determine how long the injector is open;
• using the injector flow rate and the injector open time to calculate the average fuel flow.