Port fuel injection is gaining wide acceptance as the best solution to the difficult problem of metering fuel with enough accuracy to achieve acceptable exhaust emissions, fuel economy, power and driveability. Since it delivers fuel directly to the intake valves, port injection allows intake manifold designers to concentrate solely on air flow. Thus, cylinder-to-cylinder fuel distribution is enhanced, and performance can be optimized.
Unfortunately, a multi-point injection system requires the use of one injector for each cylinder. Since presently available OEM injectors are expensive, due to difficult manufacturing techniques, the component costs for a port injection system can be quite high. In addition, projections of future injector usage indicate that supplies may eventually limit possible applications. Finally, the design of the presently available OEM injector may not readily lend itself to substantial future improvements in performance.
United Technologies has developed a new line of fuel injectors to address the cost and performance considerations of present injector designs. The Alpha Series injector utilizes new technology, simplified assembly and fabrication techniques, and low-cost components to achieve its goals. Although originally intended as a direct replacement for present technology injectors, the Alpha, as a result of its unique design, has demonstrated improved performance, and can thus meet the expanded requirements of today's emission-controlled, turbocharged engines.
This paper presents the Alpha injector, describes its features and performance, and explores some of its applications.