| 摘要 |
<p>A fuel injector mountable with respect to a combustion chamber for delivering fuel thereto, the combustion chamber comprising a chamber ceiling (30) and a chamber wall, the fuel injector comprising a nozzle body (21) having a primary nozzle axis (A- A); a first outlet opening (23; 33) having a first axis (27; 37); a second outlet opening (24; 34) having a second axis (28; 38); and means for controlling fuel delivery through the first and second outlet openings (23, 24; 33, 34). The means for controlling fuel delivery comprises an inner valve needle and an outer valve needle, and is arranged to permit fuel delivery from only the first outlet opening (23, 33), or through both the first and second outlet openings (23, 24; 33, 34) together. The first and second outlet openings (23, 24; 33, 34) are oriented such that, in use, when fuel delivery is permitted through only said first outlet opening (23; 33), a first spray formation is injected along the first axis (27; 37), the first spray formation reaching a first target distance below said chamber ceiling (30) at a radial distance from the primary nozzle axis (A-A). When fuel delivery is permitted through both openings (23, 24; 33, 34) together, respective first and second spray formations are injected along the respective first and second axes (27, 28; 37, 38) to merge externally of the injector so as to give rise to a combined spray formation having a third axis (29; 39). The combined spray formation reaches a second targetdistance below said chamber ceiling (30) at said radial distance from the primary nozzle axis (A-A), and is substantially equivalent to a spray formation delivered as if from a single outlet opening having a diameter greater than that of the first outlet opening (23; 33). The first target distance is less than the second target distance.</p> |
