Schmalz SMPi 20, Operating Instruction, Page: 11 / 50

S
CHMALZ
SCP
I
/ SMP
I
3-11
General function description
V
ACUUM GENERATION
(
WORKPIECE PICK
-
UP
)
The ejector is designed for handling parts using a vacuum together with suction systems.
The Venturi nozzle is activated by the "suction" signal input. On IMP versions, the "suction"
signal input is evaluated for its pulse. This means that "suction" mode is activated on the
ejector when an pulse of at least 50 ms is present. A longer pulse does not affect functional-
ity.
An integrated sensor records the vacuum generated by the Venturi nozzle. This is evaluated
by an electronics system and forms the basis of the system status display.
The ejector is available with (RD ejectors) and without (VD ejectors) the air-saving function.
On versions with the air-saving function, the ejector automatically regulates the vacuum
when in suction mode. The electronics system switches the Venturi nozzle off when the H1
switching point set by the user is reached.

The set switching point H1 might be exceeded considerably before the vacuum
is switched off when small volumes are to be evacuated. This system behaviour
does not constitute an error.
When objects with solid surfaces are picked up, the integrated non-return valve prevents the
vacuum from dropping. If the system vacuum drops below the switching point [H1-h1] due to
leaks, the Venturi nozzle is switched back on.
When in automatic mode, the ejector maintains "suction" mode if the power supply fails.
This prevents objects that have been picked up from falling off the suction pad in the event
of a power supply failure. This also applies when the ejector was set to “Venturi nozzle inac-
tive” with air-saving mode activated. In this case, the ejector switches to “Venturi nozzle ac-
tive” (i.e. continuous suction). The energy required to actuate the suction valve (pulse valve)
is supplied in this case by integrated capacitors. When the power supply returns, the ejector
remains in automatic mode with activated air-saving function. If the ejector is in "blow-off"
mode when the power supply fails, the blow-
off is stopped and the ejector is set to “Pneu-
matically OFF”. This prevents unnecessary consumption of compressed air, thus saving
energy and additional costs. When the power supply returns, the ejector remains in the
“Pneumatically OFF” state.
The power supply is monitored by the electronics system. If the power supply drops below
approximately 21 V, then the air-saving function is deactivated. The suction and blow-off
signal inputs are also no longer processed.