Flexible fuel control system with fuel transit delay compensation

Apparatus for delaying a time-varying digitally-expressed input variable by a duration established by a varying digital duration control value, comprising in combination:

• counter means for storing said varying digital duration control value;
• decrementing means for decrementing said counter at a fixed rate;
• means responsive to said decrementing means for generating a timing signal each time the value stored in said counter is decremented to zero;
• a first-in, first-out stack comprising a predetermined number of storage cells;
• means for storing a current value of said time-varying digital input variable in said stack upon each occurrence of said timing signal;
• means for removing from said stack the least recently stored one of said variables upon each occurrence of said timing signal, said least recently stored one of said variables being a delayed replica of said input variable.

A method for controlling an engine, the method comprising the steps of:

• supplying fuel to said engine via a fuel supply line, said fuel having a variable type and a variable temperature;
• generating a first control signal indicative of the temperature of said fuel;
• generating a second control signal indicative of a characteristic of said fuel at a sensing position on said fuel supply line;
• generating an estimate of the time required to transport fuel from said sensing position to said engine based on the current value of said first control signal,
• generating an engine control signal in response to said second control signal, said engine control signal manifesting changes at times delayed from changes manifested by said second control signal by a delay interval having a duration corresponding to said estimate.