A cap assembly adapted to be fixed on the body member of a pressure regulating valve defines an internal cylindrical volume for enclosing a magnetic plunger member. The cap assembly includes a cylindrical magnetic cap member in which is totally inserted a non-magnetic cylindrical tube member, the tube member being adapted to be fixed on the valve body member.

A fuel-injection system comprises a control unit that controls the injection of a fuel cylinder of an engine such that an injection volume of the fuel is injected into one of the cylinders during each work cycle of the engine. To this end, the control unit actuates an inlet valve and/or outlet valve such that, during pump strokes of a high-pressure pump which follow one another, a different high-pressure volume of the fuel per pump stroke is delivered into a pressure accumulator during at least two consecutive work cycles. The high-pressure volume that is produced per work cycle corresponds to the injection volume that is removed from the pressure accumulator per work cycle and is constant during each of the consecutive work cycles.

Methods and systems are provided for adjusting operation of fuel injectors of an internal combustion engine to reduce injector ticking noise during direct injection fuel rail pressure release. The method includes first reducing a significant part of the direct injection fuel rail pressure via a mechanical high pressure pump relief valve and only if further pressure relief is required then intermittently activating the direct injector to inject in small amount of fuel. Due to the reduced frequency of activation and small pulse-widths, the impact force transmitted from injectors to cylinder head is small thereby reducing the objectionable ticking noise.

An object is to suppress cavitation generated at a distal end portion of a seat face when a valve body and a seat portion collide with each other. In a relief valve of a fuel pump, an intersection between the seat face and a flow channel hole is formed at a position more distant than the seat portion formed of the valve body in a valve closing state and the seat face in order to suppress generation of cavitation bubbles when the valve body improves and releases high-pressure fuel.

A fuel injection system for a reciprocating engine, comprising injectors for injecting pressurized fuel into the cylinders of the engine, a high pressure pump for pressurizing fuel to be injected, a supply pipe for feeding fuel from the high pressure pump toward the injectors and feed pipes for feeding fuel from the supply pipe to the injectors. The first ends of the feed pipes are connected to the injectors and the second ends to the supply pipe. Each fuel injector is provided with a pressure accumulator.

A pressure reducing valve control apparatus is provided for a fuel supply system having a common rail and a pressure reducing valve to control rail pressure in the common rail by controlling a current supply state of the pressure reducing valve. The pressure reducing valve operates to open a valve body for discharging fuel from the common rail against a biasing force applied in a valve-closing direction by fuel-generated valve-opening force biasing the valve body in a valve-opening direction by the rail pressure and an electromagnetic force generated by current supply to an electromagnetic coil. The ECU starts to open the valve body during a period of holding a hold value by holding current supplied to the electromagnetic coil at a predetermined hold value after starting current supply to the electromagnetic coil. The ECU sets the hold value to increase as the rail pressure decreases.

A pressurized fuel system for an engine includes a fuel pump in a pump protection device structured to drain pressurized fuel from a common rail to provide fuel flow through the fuel pump that limits cavitation. The device includes a valve mechanism having a first valve and a second valve that are movable to an open position and a closed position respectively, in response to valve opening and valve closing rail pressures. The active pressure range of the device may be a medium pressure range.

A system and method are provided for controlling fuel rail pressure in a common rail fuel injection system. A desired rail pressure value is determined based on signals produced by one or more sensors, a feedback PCV control signal is determined based on a difference between the desired rail pressure value and a fuel rail pressure signal, a feedforward PCV signal is determined based on the desired rail pressure value, and a PCV control signal for controlling a pressure control valve fluidly coupled to the fuel rail is determined based on the feedback PCV control signal and the feedforward PCV control signal. The pressure control valve signal is correlated with the temperature of fuel exiting the pressure control valve such that operation of the pressure control valve in response to the PCV control signal results in a valve outlet orifice size which controls the temperature exiting fuel.

An injection system for an internal combustion engine including at least one injector and a high-pressure accumulator, which has a fluid connection to the at least one injector on the one side and has a fluid connection to a fuel reservoir via a high-pressure pump on the other side, wherein a suction throttle is associated with the high-pressure pump as a first pressure-setting element. At least two pressure control valves are provided, via which the high-pressure accumulator can be brought into fluid connection with the fuel reservoir.

Aspects and embodiments disclosed herein indicate a correlation exists between a specific gravity of combustible fuel and the occurrence of low-speed pre-ignition (LSPI) within engines. Thus techniques are disclosed herein for online measurement of the specific gravity of fuel within an engine, and allow for preventative measures to be executed to minimize or otherwise mitigate the incidence of LSPI when the calculated specific gravity of the fuel exceeds a predefined threshold. In an embodiment, the preventative measures may include, for example, altering or otherwise adjusting an engine map such that an injection timing scheme injects less poor-quality fuel into engine cylinders, thus advantageously preventing the engine from operating at full-power when conditions for LSPI are present.