4.4 Operating modes and control mode
4.4.1 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/STOPPED
─ The inlet valve closes.
─ The venting valve opens to de-pressurise 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 varying the volume of compressed air delivered,
thereby matching the air demand.
With the help of a mechanical control valve (the proportional controller), the opening and closing of
the inlet valve is continuously varied in relation to the actual air demand. The airend provides com‐
pressed air for connected consumers.
This stepless delivery regulation minimises fuel consumption of the engine. The load and fuel con‐
sumption of the engine rises and falls with the air demand.
4 Design and Function
4.4 Operating modes and control mode
44
Operator manual Portable compressor
M 64 No.: 9_5898 26 E
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