Abstract: An electrically-controlled fuel injector comprising a balanced pressure sl valve that alternately connects an injector plunger control chamber to fuel supply pressure or drain pressure, thereby putting the injector plunger in the closed mode or the injection mode. Fuel pressure is utilized so that the spool valve can be operated (moved) by a relatively small size solenoid. This injector is particularly designed for use in electronic fuel injection systems.

Abstract: A piston engine timed fuel injection system wherein highly compressed fuel, .g. at 20,000 p.s.i., is temporarily stored in a chamber isolated from the pressure source. A flow valve is opened to permit part of the stored fuel to expand into the combustion space. Spring force closes the valve while the injection pressure is relativey high, e.g. about 3000 p.s.i. Fuel injection pressure at beginning of the injection period may be very high, e.g. 20,000 p.s.i., thereby promoting improved fuel atomization, shorter ignition delay, lower rate of pressure rise in the combustion space, smoother combustion, and lower peak pressure in the combustion chamber. By injecting fuel from an "isolated" chamber it is possible to accurately limit the quantity in accordance with compressibility factors.