Ingo Gorille Robert Bosch GmbH (Schwieberdingen/Germany) Downloaded from SAE International by University of Michigan, Monday, September 17, 2018The appearance of the code at the bottom of the first page of this paper indicates SAE's consent that copies of the paper may be made for persona! or internal use, or for the personal or internal use of specific clients. This consent is given on the con­ dition, however, that the copier pay the stated per article copy fee through the Copyright Clearance Center, Inc., Operations Center, P.O. Box 765, Schenectady, N.Y. 12301, for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collective works, or for resale. Papers published prior to 1978 may also be copied at a per paper fee of $2.50 under the above stated conditions. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Order Department. To obtain quantity reprint rates, permission to reprint a technical paper or per­ mission to use copyrighted SAE publications in other works, contact the SAE Publications Division. ISSN 0148-7191 Copyright© 1980 Society of Automotive Engineers, Inc. Downloaded from SAE International by University of Michigan, Monday, September 17, 2018Ingo Gorilfe Robert Bosch GmbH (Schwieberdingen/Germany) The main incentive for fuel injection used to be increased engine power. Today, the engine de­ signer's principal goal is to achieve a better fuel economy and to obey the emission regulations. Both tasks clearly require a significant improvement of the combustion process. In the case of the gasoline engine, to which we shall restrict ourselves here, the combustion is controlled by the ignition timing and by the preparation of the fuel/air mixture. Both these factors ought to be optimized, once the mechanical construction of the engine is defined by its designer. A separate optimization of ignition and injection is insufficient; only by developing a joint optimization strategy can one expect to control the combustion process according to the specific requirements of the engine, thus utilizing the fuel as economically as possible. With this idea in mind, it seems natural to use a single electronic control system in order to simultaneously handle both fuel management and ignition timing. Such a combined system, called MOTRONIC, has been is series production at BOSCH since mid- 1979. It is the first of a new generation of sophisti­ cated electronic control systems that promise signifi­ cant improvements in engine control in the years to come. THE SYSTEM CONCEPT As fuel management at BOSCH means fuel in­ jection, the MOTRONIC-system contains an electro­nic fuel injection system, whereas the ignition Is based on electronic control of the advance angle. Fig. 1 shows the system schematic. It contains the well known components of the L~Jetronic on the fuel injection side, and some less known components on the ignition side. The main input to the injection system is the load signal generated by a highly accurate, vane type air flow meter. The other signals describing the state of the engine are engine speed, coolant temperature, inlet air temperature, and the status of the throttle switch. As these signals are necessary to characterize the state of the engine, they are advantageously used in common by the ignition and the injection, provi­ ding both enhanced system performance as well as reduced sensor count and costs. Until recently, spark advance was governed by engine speed and load only. Today, a more sophistica­ ted approach is possible, since the availability of sen­ sors required for fuel injection affords a more com­ plete knowledge of the state of the engine, and hence an improved ignition control. All