FLUID COUPLING WITH DELAYED-FILL CHAMBER
ADVANTAGES
4
TRANSFLUID FLUID COUPLINGS WITH A DELAYED FILL
CHAMBER
With the standard circuit in a maximum oil fill condition, fluid
couplings may transmit over 200% of the nominal motor torque. It
is possible to decrease the starting torque down to 160% of the
nominal torque, by decreasing oil fill. This, however, leads to higher
slip and working temperature in the fluid coupling, during the
steady running conditions.
The most convenient solution to provide lower starting torque while
maintaining low slip at steady running is to provide a delayed fill
chamber mounted on the main circuit. This chamber holds a
percentage of the oil which at start-up is gradually released into the
main circuit through calibrated bleed orifices as the coupling
spins. For couplings sized 15CK and above these orifices are set in
externally mounted valves.
The external mounting provides easy adjustment of the orifice size
which controls starting time and the maximum transmitted torque.
When the coupling is at rest, the delay fill chamber contains a
percentage of oil quantity in the main circuit (Fig. 4a). This reduces
the torque the coupling transmits and allows the motor to quickly
reach its steady running speed, as if it was started without load.
As the coupling accelerates, the oil flows from the delay fill
chamber to the main circuit (Fig. 4b) at a rate proportional to the
coupling’s rotational speed.
The oil continues to transfer from the delay fill chamber the to the
main circuit emptying the delay fill chamber. Once all the oil is in
the main circuit (Fig. 4c) the coupling is then transmitting 100% of
the motor torque and the minimum slip value is reached.
With a single delay fill chamber, the ratio between starting and
nominal torque may reach 150 %. This ratio can be reduced to 120 %
with a double delay fill chamber. This lower start-up torque
results from a smaller amount of oil in the main circuit due to more
oil in the bigger delay fill chamber.
Fluid couplings with single or double delay fill chamber provide
very smooth start-ups with low start-up torque transmission, and
this makes them excellent for applications with high inertia loads
and for use on belt conveyors.
The single size chamber is available from size 11CK and above.
The double size chamber is available from size 15CCK and above
SUMMARY OF THE ADVANTAGES GIVEN BY FLUID
COUPLINGS:
– Very smooth start-ups
– Reduction of absorbed current during the starting phase: the
motor starts with very low load
– Protection of the motor and the driven machine from jams and
overloads
– Utilization of asynchronous squirrel cage motors instead of
special motors with soft start devices
– Longer life and up time of the whole drive train, thanks to the
protection provided by the fluid coupling
– Energy saving, due to current peak reduction
– Limits starting torque to 120% with a double delayed fill
chamber
– Same torque at input and output: the motor can supply the
maximum torque even when load is jammed
– Torsional vibration absorption for internal combustion engines,
thanks to the presence of a fluid as a power transmission
element
– Possibility to achieve a high number of start-ups, or reversal of
the rotational direction.
– Load balancing with dual motor dr ive: fluid couplings
automatically adjust load speed to the individual motor’ s speed
– High efficiency and minimum maintenance
– Viton rotating seals and O-rings
– High resistance to corrosion by using cast aluminum for the
major coupling parts and providing anticorrosion treatment on
smaller cast iron and steel parts
ACCELERATION
valve
calibrated plug
All oil in circuit
into main circuit
Oil drains from chamber
for initial start
Oil available
use after start
Oil in reserve for
Fig. 4 c
RUNNING
Fig. 4 b
Fig. 4 a
AT REST
Pag.4
Fig. 4 a
AT REST
Fig. 4 b
ACCELERATION
Fig. 4 c
RUNNING
Содержание CCKSD-QD
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