A roller tappet for a fuel unit pump of an internal combustion engine is provided with a roller tappet bore for inserting the roller tappet within the internal combustion engine. The roller tappet includes a roller tappet body having a body longitudinal axis for connecting the roller tappet to a reciprocating element of the fuel unit pump. A cam roller contacts a cam lobe of a rotatable shaft of the internal combustion engine. The cam roller is rotatably mounted to the roller tappet body around a cam roller rotation axis. The external surface of the roller tappet body is configured to allow tilting of the roller tappet within the roller tappet bore for aligning the roller tappet with respect to the cam lobe of the rotatable shaft.

Methods and systems are provided for a direct injection fuel pump. The methods and system control pressure within a compression chamber so as to improve fuel pump lubrication.

It is important not to form the partial bump in the collision structural part, however the fixed core and the movable core are relatively inclined due to an accumulation of tolerances and therefore even if each collision structural part of the fixed core and the movable core in formed in a flat shape, the fixed core and the movable core are contacted with not the whole of the collision structural parts but a part of the collision structural parts at the moment of the collision. In a case in which the collision structural part is formed in a ring shape or an intermittent ring shape, the fixed core and the movable core are contacted with each other at outer peripheral parts. Thus, when the fixed core and the movable core are collided with each other, a high stress is applied to the outer peripheral parts contacted first. Accordingly, the shape of the outer peripheral parts of the collision structural parts is important, however since such a part, which is a tiny protruding shape, requires high processing accuracy, to reduce stress occurred during collision while keeping productivity is difficult. In the present invention, an R-shaped part and a flat part are provided in order from an outer peripheral side of a collision structural part. Further, the R-shaped part and the flat part are connected in a tangent manner.

Systems and methods are provided for operating a direct injection fuel pump. One example system comprises an accumulator positioned within a bore of the direct injection fuel pump in a coaxial manner wherein the accumulator is positioned downstream from a solenoid activated check valve. The accumulator may regulate pressure in a compression chamber of the direct injection fuel pump and a high pressure fuel rail when the direct injection fuel pump is operating in a default pressure mode.

There is provided a valve assembly comprising a valve housing. The valve housing comprises a fluid inlet, a fluid outlet, a valve opening, and a valve seat surrounding the valve opening, The valve opening is disposed between the fluid inlet and the fluid outlet. The valve assembly further comprises a ball valve element disposed within the valve housing, a spring arranged to urge the ball valve element onto the valve seat to close the valve opening, and a drive pin having a first end and a second end, the drive pin being aligned with the valve opening. The valve assembly is movable between a closed position, in which the ball valve element is held in the valve seat by the spring, closing the valve opening, and an open position, in which the first end of the drive pin extends through the valve opening to push the ball valve element away from the valve seat, opening the valve opening. At least one of the spring, ball valve element, valve seat, and first end of the drive pin includes a hard surface treatment. There is also provided a fluid injection system for injecting a fluid comprising a source of a fluid and a valve assembly, the source of a fluid being connected to the fluid inlet of the valve assembly.

A fuel injector for gaseous fuel is provided. The fuel injector includes at least one valve having a valve seat and a plunger that engages the seat to prevent gaseous fuel flow and is displaced from the seat to permit gaseous fuel flow. Displacement of the plunger away from the seat to open the at least one valve is resisted by a first plunger control mechanism and then a second plunger control mechanism depending on the distance the plunger is lifted from the seat.

A fuel injector includes a body having a fuel injection port, and a seal ring on the body. The body has a diameter-shrink portion of which an outer diameter is shrunk. The seal ring is engaged with the diameter-shrink portion. The diameter-shrink portion has a radially concaved annular groove with which a tip end portion of the seal ring is engaged. It is restricted that the seal ring is rubbed against an inner surface of the assembling hole and the seal ring is damaged.

A fuel pump assembly for an internal combustion engine includes a fuel pump housing, a cylindrical bore defined in the fuel pump housing, and a tappet assembly received in the cylindrical bore. The tappet assembly includes a one-piece shoe having a recess disposed in a bottom portion thereof, and a roller that is partially received within the recess and configured to rotate about a roller axis.

The cam follower roller device including a body, a shaft mounted on the body, a roller mounted on the shaft in a rotationally movable manner, and at least one friction element mounted on the shaft axially between the roller and the body. The friction element is separate from the body and from the roller.

A fluid injector for a combustion engine includes a central longitudinal axis, an injection valve housing with an injection valve cavity, a valve needle axially movable within the injection valve cavity, and an electromagnetic actuator unit that actuates the valve needle. The electromagnetic actuator unit includes a pole piece fixedly coupled to the injection valve housing and an armature axially movable within the injection valve cavity and operable to displace the valve needle. The pole piece has a first contact surface and the armature has a second contact surface which are directed opposite each other, wherein one of the two contact surfaces is designed to have a contact angle of less than 90 with a given fluid, and wherein the other of the two contact surfaces is designed to have a contact angle of at least 90 with the given fluid.