Pressure relief valve system

A system, comprising:

• an engine;
• a fuel rail to supply fuel to a plurality of fuel injectors of the engine;
• a high pressure fuel pump to supply fuel to the fuel rail;
• a low pressure fuel pump to supply fuel from a fuel storage tank to the high pressure fuel pump;
• and
• a pressure relief valve having a first chamber and a second chamber and fluidically coupled to the low pressure fuel pump at the first chamber and to the fuel rail and the fuel storage tank at the second chamber, the pressure relief valve including a piston coupled directly to a needle, the piston dividing the first chamber from the second chamber, the needle controlling a flow passage between the second chamber and the fuel rail, the pressure relief valve configured to:
• be in a closed position during engine priming, engine cranking, and engine operation via the fluidic coupling between the low pressure pump and the first chamber, thereby to maintain pressure in the fuel rail,
• automatically open upon engine shutdown via the fluidic coupling between the fuel rail and the second chamber, thereby releasing a pressure in the fuel rail,
• wherein the pressure relief valve is configured to be in the closed position during engine operation when the pressure in the fuel rail is less than an upper threshold pressure and to automatically open during engine operation when the pressure in the fuel rail increases above the upper threshold pressure;
• and
• wherein, during priming prior to engine cranking, the high pressure fuel pump is deactivated and the low pressure fuel pump is operated to supply fuel at a first pressure to the pressure relief valve, the fuel at the first pressure applying a force to close the pressure relief valve, wherein during engine cranking, the low pressure fuel pump is operated to supply fuel at the first pressure and the high pressure fuel pump is activated to supply fuel at a second pressure to the pressure relief valve, wherein during engine operation, the low pressure fuel pump is operated to supply fuel at the first pressure and the high pressure fuel pump is operated to supply fuel at a third pressure, the second pressure and the third pressure each higher than the first pressure and wherein the fuel supplied at the first pressure is supplied at a pressure in a range of 5-7 bar, the fuel supplied at the second pressure is supplied at a pressure in a range of 700-1000 bar, and the fuel supplied at the third pressure is supplied at a pressure in a range of 2200-2750 bar.

A system, comprising:

• an engine;
• a fuel rail to supply fuel to a plurality of fuel injectors of the engine;
• a high pressure fuel pump to supply fuel to the fuel rail;
• a low pressure fuel pump to supply fuel from a fuel storage tank to the high pressure fuel pump;
• and
• a pressure relief valve positioned at the fuel rail and comprising:
• a first chamber fluidically coupled to the low pressure fuel pump via a first opening coupling the first chamber to a low pressure fuel line, the low pressure fuel line in fluid communication with the fuel storage tank, where the low pressure fuel line is adapted to receive fuel from the low pressure fuel pump;
• a second chamber fluidically coupled to the fuel rail via a second opening in the second chamber and the fuel storage tank via a third opening in the second chamber;
• a piston separating the first chamber from the second chamber;
• and
• a needle including a first end directly coupled to the piston and a second end including a tapered tip, the needle configured to control a flow passage between the second chamber and the fuel rail via interaction of the tapered tip with the second opening, where the piston and the needle are sized such that a force applied on the piston by the first chamber maintains the needle in a closed position when the low pressure fuel pump supplies fuel to the first chamber at a first pressure, even when the high pressure fuel pump supplies fuel to the fuel rail and pressure relief valve at a second pressure that is greater than the first pressure.