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5.3.
The mode of operation of the
electronic controller
The electronic controller (see Fig. 1: ) analyzes two clock signals from
the gasoline pump computer and uses two electrical PWM control
signals to control the flow opening of the associated control valves
(explosion-protected proportional valve Type 2832, 2832EV, 6022)
and therefore the volumetric flow of the returned gasoline vapor.
The control also features two so-called diesel inputs. If this input is
active, activation of the control valves is suppressed.
Fig. 1:
Electronic controller Type 1094 EV
10
English
Type 1094 EV
System Description
5.4.
Mode of operation of a gasoline
pump with vapor recovery
To ensure uniform extraction in the whole control area, a linear char-
acteristic is required.
The originally non-linear valve flow - gas flow characteristic must
therefore be corrected. To do this, various points of the characteristic
are automatically stored in the controller memory when the system is
calibrated with the manual control unit (Type MKNE-1094) . The number
of points depends on the characteristic and is specified by the manual
control unit. The characteristic is also corrected automatically by linear
interpolation between these points.
At the start of the fueling process the amount of delivered gasoline is
calculated in the controller from the measured pulse rate.
Taking into account the linearized characteristic and the K-factor of
the suction rate, the set-point value for the valve flow can now be
determined, and the proportional valve can be activated for extraction
of the gasoline vapor.
With the activation of the proportional valve the vacuum pump is also
started to generate an underpressure.
At the end of the fueling process the gasoline pump computer no
longer generates any pulses and the proportional valve for vapor
recovery is closed.
The vacuum pump is also switched off after the overtravel time.
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