The Tire Safety System TSS Now also for commer- cial vehicles

Sonderdruck TSS en 24.06.2003 9:27 Uhr Seite 2
ATZ/MTZ
Printed in Germany 01.06.2003 Bestell- Nr. 5 000 001 075
The Tire Safety
System TSS
Now also for commercial vehicles
Reprint from ATZ / MTZ Special
Edition "System Partners"
BERU Aktiengesellschaft
Mörikestrasse 155,
D-71636 Ludwigsburg
Postfach 229,
D-71602 Ludwigsburg
Phone: ++49/7141/132-693
Fax:
++49/7141/132-220
E-Mail: [email protected]
www.beru.com
Perfection
built in
www.beru.com
BERU
Tire Safety System
The authors
Dipl. Ing (FH) Stephan
Schneider is Product
Manager Tire Safety
Systems (TSS) with
the Beru AG in Ludwigsburg.
The Tire Safety
System TSS
Now also for
commercial vehicles
Low tire pressure is often the cause of breakdowns
and serious accidents. The Tire Safety System (TSS)
from Beru AG permanently monitors the tire
pressure and makes an important contribution to
road safety. It has already been approved by big car
manufacturers as original equipment. Now the TSS
is also available to be used as original equipment
for all classes of commercial vehicles – including
trailers and semi-trailers.
1 Introduction
Next to the human tragedies surrounding
accidents with commercial vehicles and
the general costs these create, there are
additional costs. Per year about 65,000 tire
failures occur, mostly caused by neglected
maintenance, leads to considerable additional costs for the trucking industry.
Not only are the investment costs high,
a long distance truck with trailer has 12
wheels or more. The running cost can also
increase considerably, as a result of improper tire pressure.
Because of the great increased rolling resistance, a deficient pressure of just 0.2 bar can
lead to an increase in fuel consumption of
one percent. If the deficiency is 0.6 bar, the
fuel consumption increases by four percent.
According to Continental, the truck tires
presently available on the market have differences in rolling resistance of about ten
percent. An unfavorably fitted semi-trailer
can therefore increase fuel costs by more
than 1,500 Euro per year at an annual
mileage of 150,000 km (93,750 miles). If, in
addition you have poor maintenance such
2
as too low a tire pressure these costs increase further and the performance life of the
tires is reduced by ten percent at 0.2 bar
below nominal pressure and by 45 percent
at 0.6 bar below nominal pressure. Improper tire pressure can very often be observed
on the inside tires of twin tires on an axle
because, for one thing, the valves are difficult to reach for maintenance.
2. Special conditions for
trucks with trailers and
semi-trucks
Truck drivers often do not notice when tire
defects on trailers or semi-trailers occur,
gradually or suddenly during a trip. Other
motorists often have to alert the drivers to
smoking or blocked wheels – often associated with misunderstandings and additional hazards to road safety. If the trailer
starts swerving when a tire bursts, the
instability due to a sudden, uncontrollable
shift in weight is also transferred to the
vehicle pulling the trailer. This often has
serious consequences such as the trailer
separating from the truck and/or rocking
Dipl. Ing. (FH) Thomas
Kienzle is Senior
Account Manager
Commercial Vehicles
with the Beru AG in
Ludwigsburg.
Beru AG
he Beru AG is the world’s
leading manufacturer of
glow plugs for diesel engines
with an estimated 40% market
share. n ignition technology for
internal combustion engines
Beru is one of the four leading
providers in Europe. Beru is
expanding strongly into the
electronics field, concentrating
on complete electronic systems
such as the Instant Start
System ISS for diesel engines
and the tire safety system TSS
for cars and commercial
vehicles. Both systems are
already in operation, the TSS
for commercial vehicles for the
first time in the Mercedes Benz
Actros. The new electronics
site of the company in Bretten,
Baden-Württemberg, and the
Beru Microelectrónica in Spain
are the competence centers for
the development and production of hybrid circuits, electronic
controls and systems. Beru is
headquartered in Ludwigsburg,
Baden-Württemberg. Company
sales increased continuously in
the past. With 303.1 million
Euro in 2001/2002 sales were
9.6% above the previous year’s
figure. By 2004/2005 sales are
expected to be increased to
above 500 million Euro.
T
System Partners 2003
right up to tipping over. The rocking
vehicle may also greatly endanger other
motorists.
Semi-trucks are more stable in the initial phases of tire damage due to their better
coupling to the truck and the absence of
independent steering. However, once they
start swerving as a result of a burst tire at
high speed and heavily laden, it is usually
too late.
3 Behavior of the tire at
low pressure
The more pressure a tire loses, the softer it
becomes. Under high stress and uneven
loading of the transported goods, overheating with increased shoulder wear quickly
occurs.
With the result that the tire can catch
fire and/or the tread can come off and
the tire burst. But even if a detached
tread does not cause an accident, it causes so much damage to the vehicle superstructure and everything “around the
wheel” that the economic consequences
are considerable.
Driving with insufficient air pressure
can also cause serious damage inside the
tire which is difficult or impossible to
detect from the outside without intensive diagnosis. Tires have good memories;
every damage weakens the tire, often
with tragic results. Driving for too long
with too little pressure causes hidden
damage to the tires which can not be
fixed later by correcting the pressure –
realistically the tire is unfit for the road
and a hazard to all motorists.
vents accurate steering. The vehicle breaks out because the side wall deforms to
a much greater degree as a result of the
lack of pressure. The tire is unable to
transfer the transverse and lateral forces
quickly enough and becomes “spongy”.
The increased reaction time in the event
of a sudden emergency or in the long
term the danger of an unexpected blowout due to overexertion is an extreme
accident hazard.
4.2 Stability in a curve
The change in load reaction provoked by
suddenly taking your foot off the accelerator in a curve overexerts the transverse
and lateral stability of the tires. Coupled
with low tire pressure, this could cause
under steering and swerving of the back
up to a total loss of stability. If this is
accompanied by a shift in load on trucks
and transporters, the masses are out of
control once they start moving – with
catastrophic consequences.
4.3 Aquaplaning
The tires lose direct contact with the
road surface at a certain speed on wet
and snow covered roads. Water covering
of only 2 mm is enough, steering is
increasingly inaccurate, the vehicle
starts to swim and neither steering nor
braking are possible. The lower the tire
pressure, the sooner aquaplaning starts –
to the driver’s surprise who is usually
completely overwhelmed. Scarred road
surfaces and puddles increase this fatal
effect, with total loss of steering and brakes, a truck careers completely out of
control.
4.4
Impairment of road
safety by breakdowns
Broken down vehicles at the roadside,
are generally collision hazards for other
motorists. Passengers and people who
got out of the vehicle and helpers especially are in great danger. The ADAC assisted at more than 3.5 million breakdowns in 2001 – wheels and tires were the
cause in about 234,500 cases (6.7%).
You will often see tires, complete treads
or whole truck tires at the side of the
road and on highways. The remnants of
burst tires are often spread hundreds of
yards over the asphalt where they can be
the cause of further accidents, figure 1.
According to the German Association of
Commercial Goods Traffic, Logistics and
Disposal there were about 550,000 trucks
over 7.5 tons payload with the potential
to leave behind dangerous tire remains
on motorways. In the Hamburg region
alone, road maintenance workers remove about 8 tons of tire remains a year
from a mere 50 mile stretch of highway.
The perpetrators usually remain anonymous – unless they have become the victims of their own tire damage.
4 Impairment of road safety
4.1 Track stability
4.4 Impairment of road safety by breakdowns
Examinations conducted by various tire
manufacturers and the Association for
Technical Supervision (GTÜ) on the effects of tire defects – such as low tire pressure – on road safety have revealed a
direct relationship with the track stability during evasive maneuvers. The results
of these conducted with passenger
vehicles, most certainly apply equally to
light commercial vehicles and especially
the fast transporters. However, they can
generally also be applied to the situation
for heavy goods vehicles – under additional consideration of much higher forces,
masses and weights to which the tires
are subjected. It is crucial to observe the
proper tire pressure, as suggested by the
manufacturer, in order to be able to navigate the test course safely. A drop in
pressure of just 0.5 bar on both axles pre-
Offprint from ATZ and MTZ
Figure 1: Tire remains on the motorway are often the cause of accidents
3
6 Permanent tire pressure inspection
5. Permanent tire pressure
control
Low tire pressure can be avoided with
the Tire Safety System from Beru AG; it
permanently monitors the tire pressure
while driving and at a standstill. The
system warns the driver reliably when
tire pressure is too low and in the event
of tire damage. In the latter case, early
enough that accidents – for instance
due to
burst tires – can to be avoided. The Beru
system is the only one approved for standard installation in private vehicles by
Audi, BMW, DaimlerChrysler, Porsche and
VW. It is now also available for standard
installation on original equipment (not for
retrofitting!) in all classes trucks and trailers, as well as semi-trucks: beginning mid
2003 in the Mercedes Benz Actros, figure 2,
with super single tires and from the beginning of 2004 in the Schmitz Cargobull
semi-trailer, figure 3.
5.1 Functional principle of
the TSS
Figure 2: The new Actros 1844 LS is equipped with super single tires, a
specially developed emergency system and a tire safety system from Beru
Figure 3: The tire condition on the Schmitz Cargobull can be monitored
from the beginning of 2004 by a satellite-aided telemetry
5.1 Functional principle of the TSS
Figure 4: Rear
axle and super
single tires of the
new Actros 1844
LS (wheel
electronics
marked red)
4
A battery-powered wheel electronic inside the tire measures the pressure and
temperature in the tire at short intervals,
figure 4. Together with the individual
identification of the electronics in the
wheel and data of the remaining life of
the battery, these values are sent by
radio data telegrams to the antenna
where they are converted into a signal
and sent to the central control unit for
evaluation. The control unit evaluates
the data telegrams, identifies the sender
and decides whether or not the driver
needs to be informed.
Every wheel is monitored separately. The
air pressure is converted to standard
pressure by a temperature factor. The set
point for the tire pressure is specified either by the driver by pressing a button or
at the factory as a vehicle specific nominal pressure. A plausibility check and
permanent monitoring prevents possible input errors by the driver. If the
nominal pressure is not reached when
the tire is pumped up, the system
prompts the driver to correct.
5.2 Warning of loss of
pressure
A “burst tire” is usually the direct result of
a rapid loss in pressure of more than 0.4
bar per minute. As soon as the rapid drop
in pressure starts, a “hard warning”
appears in the display on the instrument
panel: “Tire defect, stop immediately”. In
System Partners 2003
5.3 The system components
vehicle-internal
data bus,
KL 15, KL 30, KL 31
control unit
transmission of wheel
electronics data
by HF signal
(433 MHz,
Frequency
Shift Keying)
digital antenna 1
digital antenna 2
the case of a slow (creeping) loss in pressure which is not yet a
safety hazard, the driver gets a “soft warning”; he is urged to
increase the tire pressure at the next opportunity. The warning
appears for the first time when the pressure in the tire falls 0.4
bar below the nominal pressure. The warning is repeated every
time the ignition is switched on and at certain intervals while
driving. If the pressure drop exceeds 0.8 bar the warning becomes more urgent,
for example in red instead of yellow. If the pressure loss occurs
when the vehicle is standing, the driver will be warned before
driving away.
digital antenna 3
5.3 The system components
digital antenna 4
wheel electronics
Figure 5: System components of the tire safety
system from Beru for commercial vehicles.
The Tire Safety System TSS consists of a central control unit,
wheel electronics fixed to every wheel and an HF receiver unit
per axle group, figure 5. The wheel electronics is designed for
installation in almost any wheel rim. The service life of the electronics is three to five years and can be used at temperatures of
–40 to +170 °C in the tire.
Since the wheel electronics are mounted inside the tire they are
protected against ambient influences such as splashing water
and salt and mechanical stress as it occurs especially on construction site vehicles. This also applies for possible vandalism.
■
5
Sonderdruck TSS en 24.06.2003 9:27 Uhr Seite 2
ATZ/MTZ
Printed in Germany 01.06.2003 Bestell- Nr. 5 000 001 075
The Tire Safety
System TSS
Now also for commercial vehicles
Reprint from ATZ / MTZ Special
Edition "System Partners"
BERU Aktiengesellschaft
Mörikestrasse 155,
D-71636 Ludwigsburg
Postfach 229,
D-71602 Ludwigsburg
Phone: ++49/7141/132-693
Fax:
++49/7141/132-220
E-Mail: [email protected]
www.beru.com
Perfection
built in
www.beru.com