Various methods and systems are provided for a pressure relief valve of a fuel system. In one example, a valve includes a first chamber in fluid communication with a first fuel line, a second chamber in fluid communication with a second fuel line and in fluid communication with a fuel storage tank, a piston separating the first chamber from the second chamber, and a needle coupled to the piston and controlling a flow passage between the second fuel line and the second chamber, where the piston and needle are sized such that a force applied on the piston by the first chamber parallel to an axis of movement of the piston maintains the needle in a closed position when the first fuel line flows fuel at a first pressure and the second fuel line flows fuel at a second pressure, the second pressure greater than the first pressure.

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.

A control device is applied for an internal combustion engine which is provided with a high-pressure fuel pump driven by a driving shaft of the internal combustion engine to discharge a fuel pressurized in a pressurizing chamber, an accumulator accumulating a high-pressure fuel discharged from the high-pressure fuel pump, and a relief valve which is opened when a fuel pressure in the accumulator is higher than a specified pressure in order to return the fuel in the accumulator to a specified chamber where a fuel has lower pressure than a fuel in the pressurizing chamber. An idle speed of the internal combustion engine is increased to a specified speed when the fuel pressure in the accumulator has been higher than a determination pressure, which is lower than the specified pressure, for a first period or longer.

A pressure release valve, having three or more cavities is described. The pressure release valve comprises a valve body with at least three valve cavities for fluid. The first valve cavity contains high-pressure fluid and the second cavity contains low-pressure fluid. The first, second, and third cavities are separate and apart from one another. The pressure release valve further includes a movable valve body shaft with a valve hammer and an elastic spring body. The pressure release valve further includes a channel and a valve port, wherein when pressure is applied to the movable valve body shaft, the movable valve body shaft is actuated to press against the valve hammer forcing the valve hammer to move opening the port allowing fluid to flow from the first cavity, to the second cavity and the third cavity.

An electrically driven solenoid coupled to a spring-operated valve, regulates pressure in an accumulator by opening when a predefined threshold pressure in a pressure accumulator is exceeded. The solenoid provides an assistive force to a spring-closed valve, reducing the amount of pressure required to open the valve responsive to the amount of current provided to the solenoid. The threshold pressure at which the valve opens is thus determined by the amount of current provided to the solenoid. Increasing the current decreases the threshold pressure; decreasing the current increases the threshold pressure.

A two-position gate valve has a gate defining a full-flow passageway therethrough and defining a restricted-flow passageway therethrough, without defining a closed position. The full-flow passageway has an entrance with a first area and an exit with a second area, the second area being smaller than the first area, and the full-flow passageway continuously tapers from the entrance to the exit thereof. The restricted-flow passageway has an entrance with a third area and has an exit with a fourth area, the fourth area being smaller than the first area, the second area, and the third area, and the restricted-flow passageway continuously tapers from the entrance to the exit thereof. Flow through the full-flow passageway is in a first direction and flow through the restricted-flow passageway is also in the first direction and the ratio of the fourth area to the second area is in a range of 5 to 15.

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.

Various methods and systems are provided for a pressure relief valve of a fuel system. In one example, a valve includes a first chamber in fluid communication with a first fuel line, a second chamber in fluid communication with a second fuel line and in fluid communication with a fuel storage tank, a piston separating the first chamber from the second chamber, and a needle coupled to the piston and controlling a flow passage between the second fuel line and the second chamber, where the piston and needle are sized such that a force applied on the piston by the first chamber parallel to an axis of movement of the piston maintains the needle in a closed position when the first fuel line flows fuel at a first pressure and the second fuel line flows fuel at a second pressure, the second pressure greater than the first pressure.

A control device is applied for an internal combustion engine which is provided with a high-pressure fuel pump driven by a driving shaft of the internal combustion engine to discharge a fuel pressurized in a pressurizing chamber, an accumulator accumulating a high-pressure fuel discharged from the high-pressure fuel pump, and a relief valve which is opened when a fuel pressure in the accumulator is higher than a specified pressure in order to return the fuel in the accumulator to a specified chamber where a fuel has lower pressure than a fuel in the pressurizing chamber. An idle speed of the internal combustion engine is increased to a specified speed when the fuel pressure in the accumulator has been higher than a determination pressure, which is lower than the specified pressure, for a first period or longer.

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.