US Patent 10047714 Fuel injector

An injection hole of a fuel injector includes: an inner hole section extending from an inner surface of a bottom wall of an injector tip obliquely away from a first side relative to a normal line of the inner surface to define a first inner side wall surface on the first side forming an obtuse angle with the inner surface and a second inner side wall surface on a second side opposite to the first side forming an acute angle with the inner surface; a middle hole section including a first middle side wall surface extending obliquely from the first inner side wall surface toward the first side; and an outer hole section including a first outer side wall surface extending obliquely from the first middle side wall surface toward the first side. A recess is formed on a radially outer side of an inner end of the inner hole section.