Abstract: 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.

Abstract: 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.

Abstract: An injector includes a nozzle distal end portion. The nozzle distal end portion has an inner surface and an outer surface. The inner surface has a valve seat which has an annular shape on the inner surface. The nozzle distal end portion has a plurality of injection holes penetrating through the nozzle distal end portion. Each of the plurality of injection holes is defined by a hole wall which has a hole-wall inner portion and a hole-wall outer portion. An angle between the inner surface and the hole-wall inner portion is an acute angle. An angle between the inner surface and the hole-wall outer portion is an obtuse angle. A first recess portion is provided on the inner surface to extend to the hole-wall outer portion.

Abstract: A valve operating system in a multicylinder internal combustion engine, including an air pressure chamber biasing each engine valve in a closed direction thereof. The air pressure chambers are formed in a member positioned between the engine valves and the cam shaft and the member is formed with an air supply passage connected to the air pressure chambers for supplying air thereto and a relief passage connected to the air pressure chambers for releasing air therefrom. Air relief valves are provided in the member for individually releasing air from the air pressure chambers to the relief passage. A pressure control valve is connected to the relief passage for controlling pressure in the air pressure chambers for improving the accuracy of the operation of the relief valves and the control of the pressure in each the plurality of air pressure chambers.