3308474 - 1080E evaporation control system (Automatic transmission)

OPERATION

The vapours coming from the tank through the two multi-purpose valves (1) are sent to the separator (2).The condensed vapours in the separator fall back into the tank.Uncondensed vapours are sent through the pipe (3) to the canister (4), where they are absorbed and stored by the activated charcoal.

The vapours flow towards the following components, via the solenoid valve (5), operated by the injection control unit:

  • the chamber via the pipe (6), when the engine is "naturally aspirated", with single-acting valve (8) closed and (7) open.
  • the turbocharger air inlet hose via the pipe (9), together with the oil vapours, when the engine is "supercharged", with single-acting valve (7) closed and (8) open.

MULTI-PURPOSE VALVES

The functions of the two multi-purpose valves are:

  • pressurization of the tank
  • sealing
  • seal in the event of roll-over

Pressurizing the tank

The tank is maintained at a pressure of 30-45 mbar by means of a fluorosilicone rubber valve, which rests on a sealing edge.The valve is supported by a stainless steel plate and counteracted by a spring.When the pressure in the tank exceeds the specified value, it overcomes the resistance of the spring and the valve is able to rise, allowing vapours to flow to the canister.When the pressure returns to the correct limits, the valve closes again.

Sealing

Under particular driving conditions, a vacuum could be created in the tank because of:

  • temperature changes
  • fuel consumption.
In this case, the valve's function is to restore the pressure of the tank by allowing air in.A fault in this function could cause the engine to miss or stall, because of difficulties in supplying the fuel pump.This function is carried out by the "goose beak" valve formed directly out of the fluorosilicone rubber.

Seal in the event of roll-over

The roll-over function prevents fuel from leaking from the tank if the vehicle overturns or is on a very steep slope.During normal driving of the vehicle (bends, acceleration, braking, etc.), the fuel is shaken up and may spill into the canister.The high sensitivity of the roll-over prevents this spillage.The roll-over closure angle is less than 33°.

CANISTER

Mounted in the front right wheelarch, this consists of an activated-charcoal filter element which absorbs the fuel vapours coming from the separator.A one-way valve allows external (scrubbing) air to enter during vapour intake.
1, From the multi-purpose valve 2, To the solenoid 3, One-way scrubbing valve

FUEL VAPOUR SOLENOID VALVE

This is mounted at the bottom of the modular inlet manifold, and is controlled by the fuel injection control unit.The function of the solenoid is to allow the passage of fuel vapours stored in the engine intake canister.If there is no supply, the solenoid is in the open position; when the ignition key is in the ON position, the solenoid closes, ready for operation.If energized, the electromagnet (1) attracts the shutter (2), which overcomes the load of the flat spring (3) and closes the hole (4), preventing the passage of fuel vapours.