FUEL INJECTION NOZZLE

PROBLEM TO BE SOLVED: To prevent lowering of a flow rate coefficient even when an injection pressure is increased, in a fuel injection nozzle for injecting a fuel into an internal combustion engine.SOLUTION: In a nozzle including a first structure, for example, a turning radius R is determined so as to satisfy an inequality 0.083 mm≤R≤0.150 mm, so that a flow rate coefficient Cd can be made 0.82 or more even when an injection pressure is increased to 220 MPa. Further by determining the turning radius R so as to satisfy an inequality 0.088 mm≤R≤0.150 mm, the flow rate coefficient Cd can be made 0.82 or more even when the injection pressure is increased to 240 Mpa. Furthermore by determining the turning radius R so as to satisfy an inequality 0.100 mm≤R≤0.150 mm, the flow rate coefficient Cd can be made 0.82 or more even when the injection pressure is increased to 260 Mpa.