| 摘要 |
<p>A fuel injector for an internal combustion engine comprises a nozzle body (14) having a spray tip (18) with at least one spray orifice (28) and a needle (22) slideably arranged in said nozzle body (14) in order to control the spray orifice (28). A control chamber (40) is associated with the needle (22), which, in use, is filled with high-pressure fuel in order to exert, at least indirectly, a pressure force on said needle (22) in its closing direction; the control chamber (40) being in communication with a high pressure fuel channel (34) through an inlet restrictor INO (70) and with a low pressure drain through an outlet restrictor SPO (72) via a control valve (46) to selectively allow or hinder the flow of fuel out of the control chamber through the outlet restrictor (72). The inlet restrictor (70) and outlet restrictor (72) have respective geometries that are designed so that the ratio of outlet fuel flow rate over inlet fuel flow rate increases at low fuel temperatures, as compared to normal fuel temperatures at same fuel pressure, in order to cause a greater pressure reduction in the control chamber (40).</p> |
