Component Technical Manual
TQM for Fuel Dispensers
Document Ref 942175-001 Rev 3
Page 2-3
2.3
The Pulser
2.3.1
MECHANICAL DESCRIPTION
The pulser is mounted in the pressure moulded TQM control housing, which
has three integrated chambers:
•
Control Valve Chamber - the control valve opens and closes the four chambers
for the piston movement
•
Gear Chamber - the rotational movement is transmitted to an optical mechanical
totaliser by a worm-driven shaft and to the magnetic wheel of the pulser
•
Electronic Chamber - mechanical rotation is transformed into electrical
information
The piston movement is transformed by the two crank shafts and three gear
wheels into a rotation of the main drive shaft. A gear wheel is mounted on the
top end of this shaft. This gear drives both the magnetic wheel shaft and the
totaliser shaft. A mechanical totaliser can be connected directly or via a flexible
cable on each end of the totaliser shaft. The mechanical totaliser counts 0.5
litres per revolution of the meter. The opposite side (or both sides) of this
totaliser shaft can be closed by a plug, which can be sealed. The totaliser shaft
is rotated with a constant ratio of 1:0.05.
The magnetic wheel shaft is driven with a ratio of 1:2.5. A sensor is assembled,
next to the magnetic wheel, to transform the rotation into an electrical signal,
which is transferred to the dispenser calculator. One pulse of this sensor
represents one centilitre (1 cl) i.e. 100 pulses per litre.
2.3.2
ELECTRICAL DESCRIPTION
The pulser electronics translate the magnetic field changes into proper “cl”
pulses required by the calculator. The pulser electronics can be divided into the
several functional blocks. The functions of the different blocks are described
in this section. All digital functions of the pulser
electronics are integrated in
an Asic. The pulser has an operating voltage of 24V dc.
forward
count
backward
count
sensor defect
overflow
pulse line
A and B
not
comparator
disable
output
driver
error
T
timer
hall effect sensor
(fault detection)
hall effect sensors
magnetic disk
digital
filter
sequence
detector
+ - cl=20 cl=0
backward flow
count (centilitres)
Asic parts
