Markem Imaje 9020, User Manual, Page: 141 / 182

Hydraulics
A36163-B
141/182
■ Ink circuit: principle of operation
The core of this ink circuit comprises of two separate diaphragm pumps operated by a
single motor. Nine solenoid valves located around these pumps (controlled by software)
transfer fluids between the various tanks.
The "air pump" is primarily used to generate a negative pressure in the buffer tank. This
negative pressure generates suction in the recovery gutter and is also used to draw up
make up when starting and stopping the jet in order to rinse the modulation assembly and
the head solenoid valves.
The "ink pump" pressurizes the ink in the accumulator and handles all transfers of fluid
between the various tanks.
As the two pumps use a single motor/piston, if only one value of the positive or negative
pressure must be changed, the software manages the opening and closing of the solenoid
valves in order to correct one value without changing the other
EXAMPLE: If the negative pressure needs to be increased but the pressure value
is correct:
- during the common intake stroke of the pumps
- open solenoid valve AS 5 (air intake in buffer tank)
- open solenoid valve TA 2 (ink intake in buffer tank)
- during the common discharge stroke of the pumps
- close AS 5 and open RE 6 (discharge air into condenser)
- leave TA 2 open (discharge ink in buffer tank)
NOTE: A pump cannot operate if all the solenoid valves connected to it are
closed.
NOTE: All the solenoid valves may be tested manually.