Burkert Type 1094 - Manual (Page 8)

6 - 1094
english
one or more pulse generator
lines from the pulse generator/
petrol pump computer
Control electronics
2.3 Principle of operation of a petrol pump with vapour recovery
The valve flow - gas flow characteristic of a pump installation is originally non-linear. In
order to ensure an even suction over the complete control range, a linear characteris-
tic is needed. To do this, various points on the characteristic are automatically stored
in the controller memory when dimensioning the installation with the control unit. The
number of points depends on the characteristic, and will be automatically determined
by the control unit. The correction of the characteristic also takes place automatically
through linear interpolation between these points.
At the start of the refuelling process, the quantity of petrol tanked will be calculated in
the controller from the measured pulse rate. Taking the linearised characteristic and
the K-factor of the suction rate into account, the set-value for the valve flow can now
be determined, and the proportional valve can be controlled for the suction of the
petrol vapour. Together with the control of the proportional valve, the vacuum pump
will also be put into operation to generate an underpressure. At the end of the refuel-
ling procedure, the petrol pump computer no longer generates any pulses and the
proportional valve for the vapour recovery will be closed. The vacuum pump will also
be switched off with an after-run time delay.
Figure 2: Functional diagram for a petrol pump with vapour recovery
Suction line
Proportional
valve
(Type 2332)
Vacuum pump
Power supply for the vacuum pump
24 V DC contactor/
relay for switching the
pump motor
24 V DC
power supply
(Type 1610)
To the
ground
tank