On-Board Refueling Vapor Recovery Function

On-Board Refueling Vapor Recovery Function

MODEL 129 with ENGINE 112, 113 with CODE (494a) USA version
MODEL 170 up to 31.8.00 with ENGINE 111, 112 with CODE (494a) USA version
MODEL 210.2 with ENGINE 112, 113 with CODE (494a) USA version
MODEL 210.0 up to 31.5.01 with ENGINE 112, 113 with CODE (494a) USA version
MODEL 220 up to 31.8.00 with ENGINE 112, 113, 137 with CODE (494a) USA version
MODEL 215 up to 31.8.00 with ENGINE 137, 113 with CODE (494a) USA version




Shown on Model 210 sedan
45 Filler neck (connection for collecting fuel vapors when refueling)
45/1 Flap
45/2 Float with flap
45/3 Corrugated tube
45/4 Pressure relief valve (in top insert integrated at corrugated tube, release pressure approx. 60 - 90 mbar)
75 Fuel tank
77 Activated charcoal canister 77/1 Pressure relief valve (release pressure approx. 30 - 40 mbar)
82 Pressure relief valve in ORVR vent line (release pressure approx. 60 - 90 mbar)
Y58/1 Purge control valve
Y58/4 Activated charcoal canister shutoff valve
A Nozzle, extraction through metal tube
B Nozzle, extraction through rubber boot (overflow not recognizable)
a ORVR vent line (from filler neck to activated charcoal canister)
b Hose line to pressure relief valve
c Fuel overflow line to atmosphere
d to engine
e Fuel overflow line to atmosphere (to tank recess)
f Fuel tank air admission line

Task
- The legislator requires, that the refueling gases in the vehicle are collected (ORVR = Onboard Refueling Vapor Recovery).
- Separate fuel and refueling gases to prevent fuel from flowing into the activated charcoal canister due to inappropriate refueling or a defective nozzle.

Note: Ending refueling when the refueling nozzle switches off and the fuel tank is full! On no account overfilling fuel tank as a result of refueling nozzle being switched on several times.

Function
The fuel vapors are recovered at the filler neck (45) and passed along a ventilation hose (a) to the activated charcoal canister. An insert inserted in the filler neck prevents, that when refueling fuel flows to the activated charcoal canister.To do this the fuel vapors in the filler neck are diverted several times in order to separate the gases from the fuel. The connection to the activated charcoal canister is shut off by a flap (45/1) when driving. It is opened by the gasoline pump nozzle when refueling.

Additional measures if fuel tank is overfilled
- If the fuel tank is full, the float (45/2) closes with flap the filler neck below. This ensures that the refueling nozzle shuts off more rapidly and overfilling is largely prevented.
- A too high level of fuel in the filler neck presses open the pressure relief valve (45/4). Fuel flows to atmosphere at the nozzle. End refueling! On nozzles fitted with rubber boot (B) this overflowing is no longer recognizable.
- A too high pressure in the ORVR vent line (a) acts on the diaphragm in the pressure relief valve (82). If the diaphragm lifts off because of excessively high pressure, the pressure is released at the fuel tank recess (e) and below the wheelhouse to atmosphere (c). End refueling!
- If the pressure is too high in the activated charcoal canister (77), the pressure relief valve (77/1) opens. The pressure is reduced through the activated charcoal canister shutoff valve (Y58/4) to atmosphere (c).