Highly accurate continuous-flow vaporized fuel supply for large dynamic power ranges

An accurate gaseous fuel flow control for spark-ignited internal combustion engines, said accurate gaseous fuel flow control producing controlled flow based on an engine control signal that represents the instantaneously desired flowrate for the gaseous fuel supply flow, said accurate gaseous fuel flow control comprising:

• a. a unitary valve block assembly defining a fuel flow inlet for receiving the gaseous fuel supply flow into said unitary valve block assembly, a fuel flow outlet for discharging the fuel supply flow from said unitary valve block assembly toward the internal combustion engine, and a continuous fluid passage between said fuel flow inlet and said fuel flow outlet for allowing continuous flow of the gaseous fuel supply flow toward the internal combustion engine;
• b. a valve comprising at least a first stage gaseous fuel flow control and a second stage gaseous fuel flow control within said unitary valve block assembly, said first stage gaseous fuel flow control defining a first part of said continuous fluid passage including at least a first variable effective valve opening, said second stage gaseous fuel flow control defining a second part of said continuous fluid passage including at least a second variable effective valve opening, said first part of said continuous fluid passage being positioned fluidically downstream of said fuel flow inlet but fluidically upstream of said second part of said continuous fluid passage, said second part of said continuous fluid passage being positioned fluidically downstream of said first part of said continuous fluid passage but fluidically upstream of said fuel flow outlet, said first stage gaseous fuel flow control comprising a first stage actuator, and said second stage gaseous fuel flow control comprising a second stage actuator;
• c. a first stage actuator control operatively connected to control said first stage actuator of said first stage gaseous fuel flow control;
• d. a second stage actuator control operatively connected to control said second stage actuator of said second stage gaseous fuel flow control;
• and
• e. a logic controller associated with said first stage actuator control and said second stage actuator control;
• f. said unitary valve block assembly containing said first stage gaseous fuel flow control, said second stage gaseous fuel flow control, and said logic controller;
• g. said unitary valve block assembly further defining an interstage part of said continuous fluid passage, said interstage part being between said first part and said second part of said continuous fluid passage;
• h. said first stage gaseous fuel flow control comprising an electronic pressure regulator whereby said first stage actuator control is operatively associated with said first stage actuator to control the pressure of the gaseous fuel supply flow in said interstage part of said continuous fluid passage based at least in part on a condition sensed downstream of said first variable effective valve opening, said first stage gaseous fuel flow control being capable of reducing the pressure of the gaseous fuel supply flow through said first part of said continuous fluid passage in an amount that corresponds to a first turndown ratio for said first stage gaseous fuel flow control;
• i. said second stage actuator comprising a fast-acting actuator operable to vary an effective area of said second variable effective valve opening based at least in part on a condition sensed downstream of said second variable effective valve opening, said second stage gaseous fuel flow control being capable of producing a controlled flowrate of the gaseous fuel flow discharged from said second stage gaseous fuel flow control corresponding to a second turndown ratio for said second stage gaseous fuel flow control;
• j. said logic controller having a signal port for receiving the engine control signal representing the instantaneously desired flowrate for the gaseous fuel supply flow;
• and
• k. said logic controller being programmed to interdependently coordinate operation of said first stage flow control and said second stage flow control by varying actuation of both said first stage actuator and said second stage actuator and to thereby concurrently (i) achieve choked flow through said second stage gaseous fuel flow control and (ii) produce a flow rate of the gaseous fuel flow from said second stage gaseous fuel flow control that corresponds to the instantaneously desired flowrate for the gaseous fuel supply flow.