Eficiencia En Motores

Gasoline-engine management

Emission Control

Technical Instruction

Published by:
© Robert Bosch GmbH, 1999
Postfach 30 02 20,
D-70442 Stuttgart.
Automotive Equipment Business Sector,
Department for Automotive Services,
Technical Publications (KH/PDI2).
Editor-in-Chief:
Dipl.-Ing. (FH) Horst Bauer.
Editors:
Dipl.-Ing. (BA) Jürgen Crepin,
Dipl.-Ing. Karl-Heinz Dietsche,Dipl.-Holzw. Folkhart Dinkler.
Authors:
Dr. rer. nat. H. Schwarz,
Dipl.-Ing. (FH) D. Günther,
Dr.-Ing. G. König,
Dipl.-Ing. E. Schnaibel,
Dipl.-Ing. (FH) W. Dieter.
Presentation:
Dipl.-Ing. (FH) Ulrich Adler,
Berthold Gauder, Leinfelden-Echterdingen.
Translation:
Peter Girling.
Technical graphics:
Bauer & Partner, Stuttgart.
Unless otherwise stated, the above are all
employees of RobertBosch GmbH, Stuttgart.
All rights reserved.
Reproduction, duplication, and translation of this
publication, including excerpts therefrom, is only to
ensue with our previous written consent and with
particulars of source. Illustrations, descriptions,
schematic diagrams and other data only serve for
explanatory purposes and for presentation of the
text. They cannot be used as the basis fordesign,
installation, and scope of delivery. Robert Bosch
GmbH undertakes no liability for conformity of the
contents with national or local regulations. We
reserve the right to make changes.
Printed in Germany.
Imprimé en Allemagne.
3rd Edition, September 1999.
English translation of the German edition dated:
March 1999.

Emissions Control
for gasoline engines

Today, environmentalprotection is
becoming increasingly important.
This fact also applies equally in the
field of automotive engineering. Such
terms as “greenhouse effect”, “toxic
emissions”, “ozone”, and “acid rain”
are everyday keywords from the environmental protection vocabulary.
The protection of our environment is
a matter of concern which is of equal
importance not only for politicians,
but also forengineers and vehicle
operators. Even though the motor
vehicle is responsible for only a relatively low proportion of total pollutant
emissions, for years now a systematic reduction of the gasoline engine’s
emissions has been taking place.
These reductions went hand in hand
with successive tightening of the
emissions limits by the lawmakers in
the various countries. All pollutantreductionmeasures are aimed at
achieving a minimum of emissions,
while at the same time ensuring minimum fuel consumption, high mileages, and excellent driveability.
This manual describes how the engine’s concept and its operating conditions influence the pollutant emissions, how exhaust-gas treatment
operates, and how exhaust-gas composition is measured.

Combustion in the gasoline engineSpark-ignition or Otto-cycle engine
2
Engine design
4
Operating conditions
8
Fuels for gasoline engines
12
Emissions-control technology
Exhaust-gas constituents
14
Exhaust-gas treatment
16
Testing exhaust and evaporative
emissions
27

Combustion in
the gasoline
engine

Combustion in
the gasoline engine
The spark-ignition
or Otto-cycle engine
Operating concept
The spark-ignition orOtto-cycle1)
powerplant is an internal-combustion (IC)
engine that relies on an externallygenerated ignition spark to transform the
chemical energy contained in fuel into
kinetic energy.
Today’s standard spark-ignition engines
employ manifold injection for mixture
formation outside the combustion
chamber. The mixture formation system
produces an air/fuel mixture (based on
gasoline or agaseous fuel), which is
then drawn into the engine by the suction
generated as the pistons descend. The
future will see increasing application of
systems that inject the fuel directly into the
combustion chamber as an alternate
concept. As the piston rises, it compresses
the mixture in preparation for the timed
ignition process, in which externallygenerated energy initiates combustion via...