Location
The fuel system high pressure pump (1) is located at the rear on the left side of the crankcase and is driven via the gearwheel drive.
Shown on engine 471.9 |
1 | Fuel system high pressure pump |
B | Fuel feed (thrust side) |
C | Fuel high pressure |
D | Fuel return |
W47.20-1084-76
Task
The fuel high-pressure pump (1) supplies the high-pressure fuel circuit with fuel and ensures that the fuel required for combustion is available under all operating conditions in sufficient quantities and with the required pressure to the cylinder 1 fuel injector (Y608), cylinder 2 fuel injector (Y609), cylinder 3 fuel injector (Y610), cylinder 4 fuel injector (Y611), cylinder 5 fuel injector (Y612) and cylinder 6 fuel injector (Y613).
Structure
1 | Fuel system high pressure pump |
2 | Fuel high pressure pump housing |
3 | Suction valves |
4 | High-pressure pistons |
5 | Compression springs |
6 | Roller tappet |
7 | Camshaft |
8 | High-pressure valve |
9 | High-pressure connection |
W07.20-1000-81
Function
Camshaft (7) of fuel high-pressure pump (1) is driven by gearwheel drive.
The fuel is compressed by two high-pressure pistons (4) and routed via the respective high-pressure connection (9) and the corresponding high-pressure lines to the rail.
Via the two compression springs (5), the two roller tappets (6) are pressed onto the double cams of the camshaft (7) which are offset to each other by 90°. Two power strokes thus occur per high-pressure piston (4) during a camshaft rotation.
If a high-pressure piston (4) is in the downward movement, the fuel can flow via the corresponding suction valve (3) into the clearance volume via the high-pressure piston (4).
If the high-pressure piston (4) changes to upward movement, the corresponding suction valve (3) is closed by the corresponding compression pressure and the fuel is compressed until the high-pressure valve (8) opens a transfer duct between the high pressure chamber and the corresponding high-pressure connection (9). The high compression fuel can now flow into the rail.
If the high-pressure piston (4) again changes to downward movement, the transfer duct is closed by the spring-loaded high-pressure valve (8) and new fuel can flow into the clearance volume through the now opening suction valve (3).