Self-Study Programme 28 Octavia ESP.pdf

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SP28-03
ESP is the acronym for:
"Electronic
Stability Programme".
The driver's first duty is, and continues to be,
to adopt a responsible style of driving which
matches road conditions and the traffic
situation.
What we wish to present to you in this Self
Study Programme is how ESP is based on the
tried-and-tested antilock brake system ABS
with its related systems of TCS, EDL, EBD and
EBC, the physical laws which apply in this
case, and how the system operates.
The system is designed to assist the driver in
dealing with difficult and unexpected
situations, such as when a wild animal crosses
the road in front. It is designed to compensate
for over-reactions and to help avoiding
unstable vehicle states. At the same time,
though, ESP is not able to outsmart the
applicable laws of Nature.
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Contents
Introduction
Physical Principles
Vehicle Dynamic Control
System Overview
Design and Operation
Control loop
Control unit
Steering angle sensor
Lateral acceleration sensor
Yaw rate sensor
Longitudinal acceleration sensor
TCS/ESP pushbutton
Brake pressure sensor
Active brake servo unit with
brake master cylinder
Brake light suppression relay
Hydraulic unit
Function Plan
Self-Diagnosis
Service
Test Your Knowledge
ESP Glossary
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You will find notes on inspection and
maintenance, setting and repair instructions
in the Workshop Manual.
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Introduction
A look back
The technical advances in automotive
engineering have resulted in ever more
powerful and higher-performance vehicles
being available on the market. This confronted
designers, at a very early stage, with the
question of how this technology can remain
controllable for the "normal driver".
In other words:
Which systems are best able to ensure
optimal braking and assistance for the driver?
That is why, even as long ago as the 20s and
40s there were the first mechanical
developments of ABS systems. They were not
up to the task, however, because of their inert
reactions.
It was the mid-60s when automobile
designers worldwide began the development
of automatic wheel lock systems, and
electronic signal processing became a reality
with the aid of new semiconductor elements.
This gave rise to the first ABS systems, which
have progressively become more powerful
and more efficient since then with the
advances in digital technology. The first
Škoda
vehicle fitted with ABS was the Felicia. Today,
it is not only ABS, but also the associated
systems of EDL, EBD, TCS and EBC, which are
already considered as normal features of a
modern car.
The outcome of this development through to
production maturity, is the ESP, although the
ideas of the engineers already go far beyond
this.
What can ESP achieve?
The
Electronic Stability Programme
is one of
the active safety features of a modern car.
We also talk in this connection of a "vehicle
dynamic system".
To put it in a greatly simplified way, it is an
"anti-skid programme".
It detects the risk of the vehicle skidding and
specifically compensates for the risk of the
vehicle breaking away.
Advantages:
–
It is not a stand-alone system, but is based
on the other traction systems, in other
words it also embraces their performance
features.
It relieves the strain on the driver.
The driver maintains control over the
vehicle.
The risk of an accident resulting from an
over-reaction on the part of the driver, is
reduced.
SP28-09
SP5-99
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The acronyms of the vehicle dynamic systems
Here is a brief explanation of the system
acronyms and the function of the individual
systems.
ABS
Antilock Brake System
It prevents the wheels from locking during a
brake application. Even at full braking power,
directional stability and steerability are
maintained.
ESP
Electronic Stability Programme
It prevents the vehicle from skidding by
specifically controlling the brakes and the
engine management system (term used by
Audi, VW, Ford, Mercedes).
Other manufacturers use the following
abbreviations for their systems:
–
–
–
–
–
AHS
Active Handling System (Chevrolet)
DSC
Dynamic Stability Control
(BMW)
PSM
Porsche Stability Management
(Porsche)
VDC
Vehicle Dynamics Control (Subaru)
VSC
Vehicle Stability Control (Lexus)
TCS
Traction Control System
It prevents the driven wheels from slipping,
for example on ice or gravel, by controlling
the brakes and the engine management
system.
EBC
EBD
Electronic Brake
Force
Distribution
prevents the rear wheels from over-braking
before the ABS takes effect, or also in certain
cases where the ABS is not operating because
of possible faults.
Engine Braking Control
This system prevents the driven wheels from
locking as a result of the braking power of the
engine if the accelerator peal is released
suddenly or if the car is braked with a gear
engaged.
EDL
Electronic Differential Lock
It makes it possible to start off even on road
surfaces which offer differing levels of grip, by
braking the wheel which is slipping.
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Introduction
Two different systems of ESP are used within
the Group:
– CONTINENTAL TEVES
– BOSCH.
For your information a brief description of the
fundamental difference between the two
systems and the vehicle models in which the
different systems are installed, before we
concentrate our attention on the ESP in the
OCTAVIA.
What is the difference between the two
systems?
In order to prevent a vehicle from skidding, a
vehicle dynamic system such as ESP must be
able to actively control the brakes within a
fraction of a second. The pressure is built up by
the ABS hydraulic pump. It is important that an
adequate pre-pressure exists at the inlet side of
the pump in order to improve the delivery of
the pump, particularly at low temperatures.
CONTINENTAL TEVES system
CONTINENTAL
TEVES
ŠkodaOctavia*
Golf ’98
Audi A3, Audi TT
New Beetle
Seat Toledo
It is in how this pre-pressure is produced that
a fundamental difference exists between the
systems from CONTINENTAL TEVES and
BOSCH.
BOSCH
Audi A8
Audi A6
Audi A4
Passat ’97
*
The MK 20 or MK 60 system from
CONTINENTAL TEVES is used on the
ŠkodaOctavia
.
BOSCH system
SP28-15
SP28-16
The system is used in the MK 20 and
MK 60 versions. In the MK 20 the pre-
pressure is built up by means of an active
brake servo unit, which is also known as
an active booster (pre-pressure booster).
On the MK 60 the pre-pressure is
produced by the ABS hydraulic pump.
Hydraulic unit and control unit for ABS
with EDL/TCS/ESP form a single unit.
The pre-pressure is produced by means
of a pre-pressure pump.
It is known as the vehicle dynamic
control hydraulic pump and is located
below the hydraulic unit.
The control unit for ABS with EDL/TCS/
ESP is separate from the hydraulic unit.
More recent BOSCH systems also
operate without a pre-pressure pump.
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