184000270 - INTRODUCTION - ENGINE AIR SUPPLY CIRCUIT

CONSTRUCTION FEATURES

The intake air is filtered and directed to the exhaust gas turbocharger.Before reaching the engine, the compressed air is cooled in the air/air heat exchanger.1. Complete air cleaner2. Air flow meter3. Turbocharger4. Air-air heat exchanger (intercooler)5. Modular intake chamber6. Pneumatically-controlled throttle body

PNEUMATICALLY-CONTROLLED THROTTLE BODY

To reduce engine noise when it is being switched off (noise produced by the DVA flywheel), a butterfly has been introduced in the inlet duct with the task of stopping the flow of air to the cylinders.

Composition

The system consists of:1. Throttle body2. Pneumatic actuator3. Connecting pipe between pneumatic actuator and Pierburg solenoid4. Pierburg solenoid valve operated by engine management control unit for sending vacuum to pneumatic actuator)5. Pipe connecting Pierburg solenoid to vacuum reservoir6. Connecting pipe between vacuum reservoir and vacuum unit

Operation

With the engine switched off, the butterfly is open because there is no vacuum.With the engine running, the throttle is open because, as the Pierburg solenoid valve is not supplied, it prevents the vacuum from reaching the pneumatic actuator.Vacuum is generated in the reservoir whilst the engine is running.Whilst the engine is being switched off (when the key is turned to the OFF position), the control unit keeps the actuator relay feed supplied for 4 or 5 seconds and, at the same time, places the Pierburg solenoid valve to earth which, on opening, sends the vacuum, which has accumulated in the vacuum reservoir, to the pneumatic actuator which closes the throttle interrupting the flow of air to the cylinders.