85
30 - Solution System
Dust Guard Option
The Dust Guard option is available only on cylindrical machines with side sweep A water mist is sprayed in
front of the side broom, and controlled by a solenoid just above the broom The option pump at the rear of the
machine pressurizes the water The wash hose option cannot be added to a machine that has Dust Guard
EcoFlex Option
Machines that have the EcoFlex option have on-board detergent mixing using a pump-driven detergent
injection system The detergent is stored in the removable detergent tank below the operator’s seat, which
has a suction hose from the detergent pumps The detergent pumps draw the liquid from the detergent tank
and inject it into the solution line before the solution solenoid. The flow rate of the detergent is controlled by
the Main Machine Controller using PWM
There are two detergent pumps that operate
in parallel to deliver detergent to the scrub
deck Each pump uses a solenoid-driven
diaphragm with one-way check valves As
the solenoid oscillates in and out, it drives
a flexible diaphragm that draws fluid in
during the retraction stroke, and drives
fluid out during the compression stroke. The
check valves allow fluid to enter only though
the inlet port, and exit only through the
outlet port
Unlike an AC solenoid that moves its
plunger the same direction regardless
of the electrical polarity, a DC solenoid
changes its direction of travel depending
on the electrical polarity of the coil Even though the EcoFlex pumps use DC solenoids, they still contain a
mechanical return spring to return the plunger to its relaxed state when no power is present
In many other machines, the solenoid is actively driven in only one direction (usually intake), but passively
returned via the return spring (usually exhaust). For higher flow rates, the SC6000 machine uses AC-
Driven, Active-Return solenoid pumps. So even though the return spring already wants to “Passively” drive
the plunger outward, the Main Machine Controller “Actively” pushes the plunger back out. So in effect, the
pumps are DC solenoids driven by an AC square-wave signal
In the forward-bias direction, with positive-to-positive and negative-to-negative, as shown above; the
solenoid plunger retracts away from the diaphragm. This results in a suction at the inlet port, and fluid is
drawn into the cavity caused by the diaphragm
If voltage is simply removed at this point, the return spring will passively push the plunger forward, and
the spring pressure will push the fluid out of the outlet port. However, if the solenoid is reverse-biased with
positive-to-negative and negative-to-positive, the plunger is actively pushed forward with a greater force
than what the spring alone can impart Because this is the compression stroke of the diaphragm, the pump
can pump faster/harder against any resistance of the outlet tubing This active-return also permits the pump
to operate at a higher PWM frequency for higher flow rates.
One thing to note about troubleshooting any solenoid driven pump, is that if the solenoid is already in its
relaxed (compression) stroke, energizing the coil in the reverse-bias direction will not give any outward
appearance that the solenoid was activated, because it is already driven in that same direction So if
manually powering the coil, make sure to check both polarities before concluding whether the solenoid has
failed or not
Outlet
Inlet
Pos
Neg
Diaphragm
Solenoid
