High pressure fuel storage (Rail) is a volumetric storage of high pressure fuel

At the same time, the accumulator smooths out pressure fluctuations that occur due to the pulsating fuel supply from the injection pump,

and also due to the operation of the injectors during injection due to the non-synchronism of the pressure pulses of the fuel doses coming from the injection pump and consumed through the injectors, as well as due to the multiple excess of the mass of fuel in the accumulator and playing the role of a damper for small pressure pulses doses of fuel supplied and consumed.

High Pressure Fuel Accumulator

Figure 1 - High Pressure Fuel Accumulator

The accumulator (fuel rail) 1 in general has the shape of a pipe, at the ends of which a fuel pressure sensor 7 and a pressure limiting valve 5 are installed.

The fittings for connecting high-pressure fuel lines 2 are located along the generatrix of the pipe perimeter; 3 and backflow fitting 4.

Fuel from the injection pump is directed through the high pressure line to the inlet fittings 3 of the accumulator.

The fuel accumulator communicates with the injectors via high pressure fuel lines connected to the accumulator outlet fittings.

High pressure fuel pump schematic diagram

Figure 2 - Schematic diagram of the high pressure fuel pump.

The volume of the accumulator is constantly filled with pressurized fuel.

The value of this pressure is maintained at a constant level and can be controlled by valve 8 (Figure 2) depending on the parameters of the diesel engine.

The pressure relief valve acts as a pressure reducing (safety) valve.

The valve body on the accumulator side has a channel closed by the cone of the valve core 6.

A spring presses the cone firmly against the valve seat at normal operating pressure so that the accumulator remains closed.

In the event that the pressure in the accumulator exceeds the working value, the cone moves away from the seat under the action of pressure and the fuel under high pressure is discharged into the backflow line.

As a result, the fuel pressure in the accumulator decreases.