7
This requires using sophisticated evaluation algorithm,
instead of using simple identification of limit value.
Other requirements for tire pressure monitoring
systems of utility vehicles:
•
exact wheel identification for vehicles with more
than 10 wheels or with double wheels
•
high efficiency of wireless data transport
•
pressure range 2 - 14 bars
•
Identification of tire pressure fluctuation based
on load and tire wear.
This function requires complicated "evaluative
algorithm".
•
Wheel modules must be mounted flexible with
respect to different types and locations of tire
valves on rims, different rim designs and
frequent wheel changes and must allow easy
exchange.
1.1
System architecture
WABCO system is based on one electronic circuit 446
220 00x 0, so called control unit, which receives wireless
data transmitted by wheel modules. Wheel modules 960
730 00x 0 are connected to the wheel valves by hoses.
Pressure information is processed by algorithms stored
in control unit.
The information is sent through CAN bus to display unit
446 221 000 0. Display unit consists of one display, two
indicators, one buzzer and two buttons.
Warning massages of different levels are displayed;
indicator colour and type of audio signal shows
seriousness of the problem:
•
Red light and 1 minute long audio signal
indicates serious defect; the vehicle must be
stopped immediately (possible threat to lives
and vehicle).
•
Yellow light and 10 minutes long audio signal
indicates smaller defect; the vehicle should be
slowed down and lower pressure adjusted.
Defects found by IVTM system are stored in electronic
memory (EEPROM) for diagnostic purposes.
System functions
IVTM
1.
Wheel module
fro wheel
Control unit
Trailer
Vehicle
Control unit
Display:
« Standalone » or integrated
IVTM system
Vehicle
CAN bus
IVTM system
Trailer
CAN bus or
HF wireless data transfer
from trailer control unit
to vehicle control unit