GF47.10-P-3004MAR On-Board Refueling Vapor Recovery Function

GF47.10-P-3004MAR On-board Refueling Vapor Recovery Function
- MODEL 230.470 with ENGINE 156.981 as of Model Year 09 /AEJ 08 model refinement package
- with CODE (494) USA version





Schematic diagram of fuel tank aeration and ventilation
1 Activated charcoal canister chamber 1
2 Activated charcoal canister chamber 2
45 Fuel filler neck
45/1 Recirculation line (for air drawn in when refueling)
45/2 Float with flap
58 Fluid reservoir
75 Fuel tank
75/1 Safety valve (rollover valve)
75/2 Fuel retention valve
77 Activated charcoal canister
B4/3 Fuel tank pressure sensor
Y58/1 Purge control valve
Y58/4 Activated charcoal filter shutoff valve
A Air admission line and vent line
B Purge line

On-board refueling vapor recovery, general points
The legislator requires that the refueling vapors in the vehicle are collected (ORVR = Onboard Refueling Vapor Recovery). Fuel and refueling vapors must be separated in order to prevent fuel from flowing into the activated charcoal canister due to inappropriate refueling or a defective nozzle.

On-board refueling vapor recovery, function sequence
Thanks to its shape, the fuel filler neck functions as a suction jet pump. The fuel out of the nozzle accelerates through this in the filler neck and air is suctioned around the nozzle.
As a result of this air intake (in the fuel tank) around the nozzle, refueling vapors are not able to rise up at the fuel filler neck and escape into the atmosphere.
The fuel vapors flow through two safety valves (rollover valves), the fuel-retention valve and the aeration/vent line to the activated charcoal canister, where they are stored.

If fuel gets into the two safety valves at the top (when fueling, braking, accelerating or cornering), these close off the aeration/vent line to the activated charcoal canister. As a result, fuel is not able to enter the activated charcoal canister.
The fuel retention valve also prevents fuel from flowing into the activated charcoal canister.

When the fuel tank is full, a float with flap closes off the fuel filler neck. This ensures that the refueling nozzle shuts off more rapidly and overfilling is largely prevented.

In the event of an accident (rollover), the safety valve closes off the ventilation system and thus prevents fuel from escaping.

For enabled purging the refueling vapors are suctioned out and burnt together with the fuel gases out of the activated charcoal canister via the purge line by the engine.