The invention relates to a fuel injector (10), comprising a nozzle body (12) in which a blind hole (19) is formed, wherein at least one injection opening (14) leads off same, comprising a nozzle needle (25; 25a to 25c) that is reciprocatingly movable along a longitudinal axis (18), wherein the nozzle needle (25; 25a-25c) has a valve seat (29) which forms a sealing seat (26) with a seating surface (21) in the nozzle body (12) in a lowered position of the nozzle needle (25; 25a-25c), and comprising at least one borehole (34; 34a-34c) in the nozzle needle (25; 25a-25c), wherein at least some portions of a borehole inlet (36) of the at least one borehole (34; 34a-34c) are located in the region of the seating surface (21) when the sealing seat (26) is formed, and a borehole outlet (40) of the at least one borehole (34; 34a-34c) is located below the valve seat (29) of the nozzle needle (25; 25a-25c) in the direction of the longitudinal axis (18).

A fuel gas injection arrangement directly injects a gaseous fuel into a combustion chamber of an internal combustion engine. The fuel gas has a nozzle cap having a body part with an inner circumferential side partly defining an inner volume, an inlet for receiving gaseous fuel and at least one outlet at an axial end portion of the nozzle cap; an inlet valve arrangement at least partly accommodated in the body part. The inlet valve arrangement is movable between a closed position in which a portion of the inlet valve arrangement is in abutment with a valve seat of the nozzle cap to prevent fuel gas from entering the inlet, and an open position in which the fuel gas is allowed to flow between the inlet and the at least one outlet. The nozzle cap has a flow-guiding portion on the inner circumferential side and the inlet valve arrangement has a corresponding protruding flow-guiding portion protruding radially towards the inner circumferential side. The nozzle cap flow-guiding portion and the valve protruding flow-guiding portion cooperate to redirect gaseous fuel received from the inlet towards the at least one outlet such that gaseous fuel jets exiting the at least one outlet converge towards a geometrical intersection-axial center region.

A fuel injection arrangement admits a flow of hydrogen into a combustion chamber of hydrogen internal combustion engine. The fuel injection arrangement has a nozzle cap and an inlet valve arrangement. An inner surface of the nozzle cap comprises a nozzle protrusion protruding radially towards an envelope surface of a flow guiding portion of the inlet valve arrangement. The nozzle protrusion is arranged axially between a valve protrusion of the inlet valve arrangement and an outlet of the nozzle cap. The valve protrusion and the nozzle protrusion at least partly overlap in a radial direction.

A nozzle cap for a fuel gas injection arrangement of an internal combustion engine has: a body part defining an inner volume for accommodating a part of a movable valve arrangement, an inlet for receiving gaseous fuel, and at least one outlet arranged at an axial end portion of the nozzle cap. The at least one outlet permits discharge of one or more gas jets of fuel into a combustion chamber of the internal combustion engine. The axial end portion of the nozzle cap has a radial protrusion extending from an inner side of the nozzle cap towards an axial center axis and is delimited in a circumferential direction by axially-extending side sections, said radial protrusion having an inner surface region for reducing a crossflow of the fuel gas flow inside the nozzle cap and guiding said fuel gas flow towards the at least one outlet.

A Laval shape is formed between the nozzle seat surface and needle tip portion. An injection hole also has the Laval shape. When the needle lift amount is small, a fuel flow velocity reaches an acoustic velocity in valve-opening portion. The fuel flow velocity further accelerated to a supersonic velocity at the Laval shape. When the needle lift amount is large, the fuel flows into the injection hole without a velocity decrease. Thus, the fuel flow velocity reaches the supersonic velocity at the Laval shape.

In a fuel injection valve, it is possible to obtain spray in which the penetrating force of injected fuel is suppressed. The fuel injection valve includes a valve seat that forms a gap with a valve body, the gap allowing fuel to pass therethrough, and multiple injection holes that are located further downstream from the gap. The fuel to which pressure is applied flows out from the injection holes. When the flow velocity of the fuel in the gap formed between the valve body and the valve seat is indicated by meters per second, the flow velocity is set to be greater than a value obtained by multiplying the square root of the pressure applied to the fuel by 28. In this manner, the flow velocity in the gap increases, and flow velocity distribution inside the injection hole is uniformized, thereby suppressing an increase in penetration.

A fuel injection arrangement admits a flow of hydrogen into a combustion chamber of hydrogen internal combustion engine. The fuel injection arrangement has a nozzle cap and an inlet valve arrangement. An inner surface of the nozzle cap comprises a nozzle protrusion protruding radially towards an envelope surface of a flow guiding portion of the inlet valve arrangement. The nozzle protrusion is arranged axially between a valve protrusion of the inlet valve arrangement and an outlet of the nozzle cap. The valve protrusion and the nozzle protrusion at least partly overlap in a radial direction.