Direct injection fuel injector spray nozzle and method

Abstract

A direct injection fuel injector spray nozzle assembly and method of operation wherein the nozzle assembly comprises a three hole swirler with a central valve guide, a convergent swirl chamber, a conical nozzle valve and a conical valve seat. High pressure fuel at, for example, 10 MPa is delivered to the injector and passes through internal passages with a negligible pressure drop until reaching the nozzle assembly. The size, configuration and orientation of the swirl chamber and swirler holes are selected to achieve a desired swirl intensity at the nozzle exit. At least 30 percent and preferably about half of the fuel pressure, 5 MPa, is consumed in passing through the swirler holes and developing the swirl motion. The remaining pressure drop of at least 30 percent, preferably half, 5 MPa, occurs at the sealing point of the valve head against the valve seat. The outwardly opening conical injection valve and seat, together with the high pressure, combine to provide essentially separate control of the elements of fuel droplet size, spray penetration and spray angle. Swirl intensity adjusted by varying the swirler hole locations can serve as a primary control factor for spray penetration. The cone angles of the valve and seat act as a primary control for spray angle. Droplet size is directly affected by the valve opening which determines the liquid sheet thickness of fuel passing through the spray nozzle, as well as by the fuel pressure drop through the nozzle.