Abstract
VisiTyre is a
Battery-Less Tyre Pressure Monitoring System featuring inductively coupled circuits for the
non-contact transmission of power and data across a vehicle’s rotating wheel
chassis boundary. The system’s unique electromagnetic coupling obviates the need
for any wheel module sensor batteries and allows instant monitoring and
reporting of every tyre’s status immediately the vehicle’s ignition is switched
on.
System Components
The VisiTyre
system is comprised of five main assemblies:
1.
Electronic Control
Unit
2.
Caliper Coil
3.
Rim Coil
4.
Rim Sensors
5.
Twisted Pair Wiring
Harness
The VisiTyre
Electronic Control Unit is a microprocessor controller unit which interfaces the
brake caliper mounted reader Coils - and a spare wheel mounted reader Coil - to
the vehicle’s instrument cluster display system. This is a chassis mounted
electronic module powered from the vehicle’s battery. The module’s software
receives and analyzes tyre data for Pressure and Temperature activation floor
threshold alarm conditions.
The module has
various interfaces for use by OEMs, which include, CAN Bus 2.0B, Tell-Tale LED &
Audio Out, Flash Memory Programming Port and optional LCD Display.
Each VisiTyre
Caliper Coil is energized in sequence by the VisiTyre Electronic Control Unit in
order to supply energy to its adjacent rim coil over the air gap which exists at
the rotating wheel chassis boundary.
Each VisiTyre
Rim Coil supplies inductively coupled energy from its adjacent caliper coil to
its respective rim sensor.
VisiTyre’s Rim
Sensor is a high accuracy pressure and temperature sensor subsystem based on
micro-machined silicon technology. It has a digital core with a 2-terminal
interface for the simultaneous supply of power and transmission of data.
A simple Twisted
Pair Wiring Harness is used to connect the VisiTyre Enabled Brake Caliper
mounted Coils to the VisiTyre Electronic Control Module.
VisiTyre 2 Terminal P&T Sensor
VisiTyre’s
Inductively Coupled 2 terminal pressure and temperature sensor, has low
sensitivity drift with change in temperature over the automotive temperature
range of –40oC to +125oC.
The sensor has a
digital core with a 2-terminal interface for the simultaneous supply of power
and transmission of data. The device assumes an unreliable communication channel
to the VisiTyre Electronic Control Unit and embeds a Cyclic Redundancy Check
within the datagram.
The sensor is
engineered to meet the difficult and demanding automotive environment where
there are extremes of vibration, temperature ranges, electrostatic discharges as
well as petro-chemical liquid and solid substances in the tyre zone.
The 2 terminal
interface is accomplished through a package design that directly connects to an
external wheel mounted Sensor Coil assembly.
VisiTyre System Features are
summarized as follows :
·
Inductive coupling
with no requirement for sensor subsystem batteries;
·
Measures pressure
and temperature data continuously in real time immediately after ignition on;
·
Transmits data as a
digital datagram with an embedded cyclic redundancy check (CRC);
·
Transparent tyre
rotation without the need to reprogram tyre position;
·
Transparent to tyre construction types and ferrous or carbon black content;
·
Not subject to
being deafened by radio frequency sources;
·
Zero maintenance
with highly predictable and reliable system performance over the vehicle’s life;
·
Sensor packaging
with negligible added weight to affect wheel’s balance;
·
Reports normal and
abnormal conditions simultaneously on all tyres including spare tyre;
·
High reliability of
sensor due to micro machined silicon fabrication processes;
·
High yield of
sensor subsystem in mass production.
VisiTyre EMC S-01 Sensor Specification