MAN B&W MC/MC-C two-stroke engines, has an algorithm controlling cylinder oil dosage proportional to the sulphur content in the fuel. This algorithm is referred to as Alpha Adaptive Cylinder-oil Control (Alpha ACC).
The following two criteria determine the control:
• The cylinder oil dosage shall be proportional to the sulphur percentage in the fuel
• The cylinder oil dosage shall be proportional to the engine load (i.e. the amount of fuel entering the cylinders)
The
system is based on an injector which injects a specific volume of oil into each
cylinder on each ( though more normally alternate) revolution of the engine.
Oil is supplied to the injector via a pump or pumps. A computer, which is
synchronised to the engine at TDC each revolution, finitely controls the timing
. Generally most efficient period for lubrication is taken at the point when
the top rings are adjacent to the injection points.
The
injection period is governed by the opening of a return or 'dump' solenoid
which relieves system pressure.
Quantity
can be adjusted by manually limiting the stroke of the main lubricator piston,
by altering the injection period or by the use of multiple mini-injections per
revolution.
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