Design And Function: Compressor
To produce an engine with high torque from very low revs, we have chosen to use a compressor belt-driven by the crankshaft. The working range of the compressor is from 0-3500 r/min of the engine. The ratio means that 3500 r/min at the crankshaft provides 23000 r/min at the compressor. At engine speeds above 3500 r/min, the compressor is always disengaged mechanically via the electrical clutch.
Compressor
- Inlet
- Exhaust
- Pinion gear
- Clutch
- Contact
- Pulley
The compressor is made by Eaton and works according to the Roots principle. A Roots compressor is basically a piston pump that moves a volume of air in pockets between the rotors from inlet to outlet with no internal compression. Instead the compressor creates boost by pushing more air into the intake manifold than the engine currently can use. This in turn creates a pressure higher than the current atmospheric pressure in the intake manifold.
The compressor is normally engaged directly from idle to ensure good response (does not apply at activated ECO+). Otherwise, engagement/disengagement is controlled strictly according to the torque request. Engagement occurs if the torque request to the engine control module (ECM) is above 130 Nm and the engine speed is less than 2400 r/min at the same time. Disengagement occurs if the torque request has decreased to less than 90 Nm.
At speeds above 2400 r/min the compressor only engages if the demand exceeds what the turbo can deliver alone. At high torque requests at speeds above 2600 r/min the compressor does not activate. The compressor can however be switched on if activation occurred earlier at an acceleration from low speed. At engine speeds above 3500 r/min, the compressor is always disengaged mechanically via the electrical clutch.