4.4 Operating modes and control mode
4.4.1 Machine operating modes
The machine operates in the following modes:
■ WARM-UP
─ The inlet valve is nearly fully closed.
─ The minimum intake air volume escapes via the venting valve.
─ The engine runs at minimum speed.
■ LOAD
─ The inlet valve is open.
─ The engine runs at maximum speed.
─ The airend delivers compressed air.
■ MODULATING
─ With the help of a control valve (the proportional controller) the degree of opening of the
inlet valve is steplessly varied in response to the air demand.
─ The load and fuel consumption of the engine rises and falls with the air demand.
─ The airend delivers compressed air.
■ IDLE
─ The inlet valve is closed.
─ The control valve opens, allowing pressure in the oil separator tank to be applied to the inlet
valve.
─ Compressed air then flows in a closed circuit through the airend, the oil separator tank and
the control valve.
─ The pressure in the oil separator tank remains constant.
─ The engine runs at minimum speed.
■ RUN-ON PERIOD/STANDSTILL
─ The inlet valve closes.
─ The venting valve opens to depressurize the machine.
─ Machine cools down.
─ The engine stops.
4.4.2 MODULATING control
The control system regulates the volume of air generated to match the actual demand. The ma‐
chine keeps the working pressure constant by continuously varying the volumetric flow rate within
the machine's regulating range, independent of the air demand.
With the help of an electrical control valve (the proportional controller), the opening and closing of
the inlet valve is continuously varied in response to the actual air demand. The airend provides
compressed air for connected consumers.
This continuous delivery regulation minimizes the fuel consumption of the engine. The load and
fuel consumption of the engine rises and falls with the air demand.
4
Design and Function
4.4
Operating modes and control mode
No.: 901765 05 USE
Operator Manual Screw Compressor
M114 SIGMA CONTROL SMART
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