Page 8 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey

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Preface

The dramatic evolution of catalytic converters in the last thirty years was a result of a need
worldwide to reduce pollution created by the exhaust gases of internal combustion engines.
Environmental concerns have led American, Japanese and European Union (EU) legislation to
pose continuously stricter emission limits for petrol engines in the last decades.

The catalytic converter has become the most important means of exhaust treatment to achieve
the desired emission limits. The international legislation has also created a need for a regular
assessment of the efficiency of the catalytic converter in order to detect a deterioration of its
conversion efficiency as soon as this deterioration takes place. The assessment of conversion
efficiency of a catalytic converter can take place during normal driving of a vehicle (on-board
diagnosis or OBD) or in a workshop by specialized technicians. The most important methods
nowadays are the OBD methods.

This book is an attempt to describe the evolution of methods concerned with on-board (OBD)
and non-OBD monitoring and diagnosing of the efficiency of catalytic converters of internal
combustion engines based mainly on patents and published patent applications. A limited
amount of non-patent literature has been also used. All patent and non-patent documents cited
in this book originate from the systematically classified documentation of the European Patent
Ofice (EPO). For the Japanese patent literature the technical abstracts published in English by
the Japanese Patent Office have been used.

The presentation has been focused on the sequence of steps used by each method to assess the
conversion efficiency of a catalytic converter. Only a limited number of engine measuring set-
ups and associated instruments used are described in detail to reduce the material to a
manageable size. It should be noted that no verification of the feasibility of a method or a
device or a measuring instrument or even the operation of a device or a measuring instrument
is needed to render them patentable.

The methods in each part are presented in chronological order per patent applicant. This helps
to evaluate how the patent applicant has improved his methods over time. The patent or patent
application number, the name of the applicant and the date of publication are indicated for each
document cited in the book. A patent number index, an inventors index, a company index and a