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the ability to evaluate the signal from an external air pressure
switch to monitor the oil+air system. The electrical connections
are established via DIN connection plugs or screwed glands.
3.4 Gear pump unit without control unit
Gear pump units without an integrated electronic control unit
are controlled by the control unit of the machine to which the
gear pump unit is connected. The machine control unit controls
the pump cycle time, the pump delay time, and the interval time
of the gear pump unit according to the lubricant required by the
lubrication points. The pump cycle time, referred to as the
contact time, consists of the pressure build-up time and the
pump delay time. The monitoring time consists of the period
between switching on the gear pump motor and establishment
of the maximum pressure built-up time. A fault signal will be
issued if the maximum pressure build-up time elapses without
the pressure switch closing.
The interval time is the period between two pump cycle times
(contact time).
A lubricating cycle consists of the operating time and the
interval time.
When setting the interval time, the pump cycle time, and the
pump delay time, comply with the S3 duty type permitted for
the gear pump motor. Consult the “Technical data” chapter for
information on the operating mode.
With regard to monitoring pressure build-up in the main
lubricant line during a lubrication cycle, note that several
seconds may pass after the gear pump motor is switched on
before the pressure switch responds. A fixed monitoring time
for lubricant pressure build-up is recommended so that the
machine control unit waits until this time has elapsed to issue a
fault notification if the required lubricant pressure is not
reached. A period of approx. 60 seconds is recommended. The
pressure switch responds once the required lubricant pressure
has been reached. If the required lubricant pressure is not
reached, the machine must be shut down to prevent
underlubrication of the bearings.
To prevent underlubrication of the bearings in the oil +air pump
design (MKL without control unit), the monitoring of minimum
air pressure of the supplied compressed air must be configured
so that the machine is shut down if there is no air pressure or
the pressure drops too low. Ensure that a time buffer is stored
in the machine control unit to level out brief pressure
fluctuations in the compressed air supply.
In order to prevent underlubrication of the bearings, monitoring
of the minimum fill level of the lubricant reservoir must be
configured in such a way that the machine is shut down if the fill
level is too low.
3.5 Gear pump unit with control unit
(IG/IZ38, IGZ36, IG54)
Gear pump units with a control unit contain a programmable
electronic control unit that can be used to control and monitor
the gear pump unit. Electronic control units are designed as
pulse generators/pulse counters (contactors/contact counters).
In the case of pulse generators (contactors), the length of
the interval is determined by the unit itself, by starting an
operating time after certain periods of time specified by the
operator.
Depending on the model design, the electronic control unit
could allow configuration of the interval time, the pump delay
time, and the number of prelubrication cycles. One or more
prelubrication cycles with short interval times can be triggered
prior to starting up the machine.
Prelubrication cycles ensure that, prior to actually starting the
machine, a sufficient quantity of lubricant is built up in the
lubricant lines and metering devices or (in oil+air centralized
lubrication systems) a fully developed oil streak is formed in the
lubrication point lines. The pump cycle time is 60 seconds and
cannot be changed.
In the case of pulse counters (contact counters), the
interval time is determined by the machine, which sends pulses
to the control unit while the machine is in operation. The control
unit counts the pulses that are received on the machine contact
(MK or MKPV) and starts a contact time after the pre-set
number of pulses. The operator can set the number of incoming
pulses to be counted.
Some of the control units allow the connection of monitoring
units. The monitoring units are connected electrically on the
terminal strip of the electronic control unit of the gear pump
unit. The control unit directly monitors the operation of the oil
pressure switch, the pressure switch for minimum air pressure
(both possible on MKL design), and the lubricant level switch.
Gear pump units with an electronic control unit are supplied
with all , internal wiring fully connected. Depending on the
model design of the electronic control unit, a signal line for fault
monitoring could be connected to the electronic control unit for
connection to the machine control unit. The signal line comes
out through a screwed gland mounted on the gear pump unit.
Details on the function and operation of the electronic control
unit can be found in the assembly instructions for the electronic
control unit, which are included in the scope of delivery of a
gear pump unit.
3.6 Control unit designs with their basic
settings
Control unit: IG38-30-I
Description: The IG38-30-I is used as a pulse generator
Functions:
• Adjustable interval time
• Interval time extension
• Pump cycle time limitation
• Pressure build-up monitoring
• Fill level monitoring (NC contact)
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