Constant-speed multi-pressure fuel injection system for improved dynamic range in internal combustion engine

A method to modify a standard fuel injection system of internal combustion engine that has a fuel pump pumping pressurized fuel from fuel tank through main fuel line to the fuel rail in fluid communication with fuel injectors which may have a pressure regulator, to save fuel in city driving to reduce the amount of pollutant released to the air in metropolitan areas, comprising,

• setting fuel pump at a predetermined substantially constant speed ω,
• creating a fuel return path with flow restraint from main fuel line including fuel pump outlet avoiding the fuel rail, to the fuel supply including the fuel pump inlet, to divert sufficient amount of fuel pre-set by the selected flow constraint in the fuel return to form a continuous recirculation loop to stabilize fuel pump operation so that the system will always be able to deliver sufficient amount of fuel at the pre-set pressure level PH from fuel pump outlet to the fuel rail and fuel injectors under the constant speed pump for a wide range of operating conditions at PH (controlled by the pulse width of fuel pulses),
• installing a fuel by-pass path with a normally closed binary control valve and a flow constraint provided by an orifice of predetermined diameter, a needle-valve-like device, or a device compressing on the fuel by-pass path, from the main fuel line, avoiding the fuel rail including outlet of the fuel pump, to the fuel supply including inlet of the fuel pump in parallel with the fuel return path, and
• opening the normally closed binary control in the fuel by-pass path on demand, creating additional recirculation loop to instantly reduce the fuel pressure from PH to a pre-set pressure level PL from fuel pump outlet through main fuel line to fuel rail and fuel injectors, yet PL is higher than the minimum pressure required to produce fine fuel spray, when the engine is warm and the amount of fuel pulse on demand is less than the maximum amount fuel pulse allowed in PL, thus widening the operating dynamic range of fuel injection by enabling to choose pressure level and vary pulse width under PH and under PL per engine fuel demand and driving conditions, delivering smaller amount of fuel per pulse at minimum pulse width at PL when the gas pedal is released including idle, to save fuel and provide cleaner air in city driving, and potentially able to eliminate a pressure regulator to reduce manufacturing cost.

A method to modify a fuel delivery system of aircraft engines making use of a fuel injection system, that has a main fuel line connecting from the fuel pump outlet in fluid communication to fuel injectors of the engine, to save fuel when the aircraft is sitting idle at the terminal or on the taxi runway, comprising,

• setting fuel pump at a predetermined substantially low speed typically used for idling,
• installing a fuel by-pass line with flow restraint and a normally closed binary control valve from the main fuel line including outlet of the fuel pump, avoiding proximity of hot engine and fuel injectors, to the fuel supply including the inlet of the fuel pump, and
• opening the normally closed binary control valve in fuel by-pass on demand when engine is warm, creating a fuel by-pass and a recirculation loop to reduce and stabilize fuel pressure in the main fuel line to fuel injectors to a pre-set level PL determined by flow constraint in fuel by-pass path, yet PL is higher than the minimum pressure required to produce fine fuel spray;
• thus delivering smaller amount of fuel per pulse at minimum pulse width when engine is warm to keep engine and other accessories running, thus saving fuel when idle and releasing less amount of pollutant to the air in the airport and in metropolitan areas.

A method for modifying a fuel delivery system in high performance vehicle that is capable of supplying large amounts of air to engine's cylinders which enables it to deliver on-demand a burst of super power beyond maximum engine rating for a short duration, while at the same time still able to achieve fuel saving and provide cleaner air in city driving, comprising:

• setting fuel pump at a predetermined substantially constant speed Ω1,
• installing a normally open fuel-return path with flow restraint, from the main fuel line, avoiding fuel rail, including the outlet of the fuel pump, to fuel supply including the inlet of the fuel pump, and avoiding the fuel rail which diverts sufficient amount of fuel to form a continuous recirculation loop setting the fuel pump to a stable operating region to deliver sufficient amount of fuel at the pre-set pressure level PH at all times to fuel rail and fuel injectors when the fuel return path is open,
• installing at least one fuel by-pass line from the main fuel line, back to the fuel supply or the intake side of the fuel pump, avoiding fuel rail, having flow restraint and a normally closed binary control valve so that opening the normally closed binary electronic valve on demand when the engine is warm reduces the fuel pressure on the main fuel line to a pre-set pressure PL1, thus saving fuel every time gas pedal is released and during idling to achieve fuel efficiency in city-driving,
• installing a normally open instantly responding binary control valve in the fuel return path,
• closing on demand all valves in the normally open fuel return path and the fuel by-pass line to create a highest pressure state P01>PH1 to deliver largest amount of fuel pulses, and
• providing means to determine when the full opening of any throttle valve and air accessories, such as a turbo charger, super charger are operable and coordinating their operations for maximum air supply to maintain adequate fuel/air ratio, wherein the means is Engine Management Control, thus enabling a burst of super power beyond the maximum engine rating for a short duration when all valves are closed.