| 摘要 |
An injection nozzle for injecting fuel into a combustion chamber of an internal combustion engine is disclosed. The injection nozzle comprises a nozzle body (13) having a bore (17) for receiving fuel from a supply line (12) for pressurised fuel, an outlet (16) from the bore (17) for delivering fuel to the combustion chamber, in use, and a valve needle (15) slidable within the bore (17) between a closed state in which fuel flow through the outlet (16) into the combustion chamber is prevented, and an injecting state in which fuel flow through the outlet (16) into the combustion chamber is enabled. Movement of the valve needle (15) is controllable by varying the fuel pressure within a control chamber, in use. The valve needle (15) comprises a needle guide portion (22) arranged to guide sliding movement of the valve needle (15) within the bore (17). The injection nozzle also comprises a restriction (21a) within the bore (17) for restricting the flow of fuel through the bore (17). The restriction is defined by a restrictive element (21) which is movable with the needle (15) and is located upstream of the needle guide portion (22). When the needle (15) is in the injecting state in use, the fuel pressure at the outlet (16) is substantially the same as the pressure of fuel in the bore (17) immediately downstream of the restrictive element (21) and is less than the pressure of fuel supplied to the bore (17) from the supply line (12). |
