Robert Boschgmbh

Walter Viess

Siegfried Rohde

Jorg Bonitz

Bernhard Miller

Robert H Entenmann

Stefan Unland

Rochus Knab

Herbert Schramm

Matthias Philipp

Jurgen Zimmermann

Hans-Ernst Beyer

Walter Kunzel

Alfred Mahlberg

Wolfgang Kugler

Siegmar Forster

Herbert Winter

Hans Rauch

Hans Koehnle

Geza Killi

Robert Entemann

An exhaust-gas recirculation system includes means for diagnosing the system based upon temperature values measured in the exhaust-gas return duct when certain conditions exist. A differential value between the actual temperature in the exhaust-gas return duct and a reference temperature, which indicates the possible beginning of diagnosis, is provided for a flow-through test. The differential value is then fed to a low-pass filter. If the conditions for a diagnosis are satisfied, it is determined whether the recirculation system is in order based upon a comparison of the differential value to a threshold value. A leak test of the exhaust-gas return valve can likewise be performed based upon the differential value of the two temperatures.

Exhaust-gas recirculation system for an internal combustion engine

Method for recognizing the power stroke of a cylinder of an internal

A first control unit of a multiple function control system for a motor vehicle engine controls a function, such as fuel injection, for which it is desirable to provide an engine load signal measured by the amount of air drawn or forced into the engine per unit of time, determined by what is generally known as an air quantity meter. A second control unit of the control system controls the timing of an electrical ignition system for which it has been conventional to supply an engine load signal derived from a pressure transducer. In order to dispense with the pressure transducer and to make both control units subject to adaptive correction of the air quantity signal, the output of the air quantity meter is furnished to the second control system for modification therein by the computation facilities normally included in modern ignition control systems so as to shift or expand the range of engine load signals obtained from the air quantity meter to provide the same degree of resolution as would be available from a pressure transducer. For adaptive correction, the engine-load-to-engine-speed characteristic at a predetermined position of the throttle valve at or near full load is stored, both to provide a plausibility check of the system when the engine is operating at or near full load, and to provide for a correction of the engine load signal of a kind which would minimize the difference between the actual and reference characteristic lines when the engine is operating at or near full load.

Control system for an extrinsic-ignition internal combustion engine

Control of a microcomputer performing a wide variety of functions in a motor vehicle in which the sequences of input and output signals intersect in time, instead of being performed by an elaborate input/output unit, is performed in the microcomputer itself with the help of a timing signal generator operating at a sub-multiple of the microcomputer clock frequency and producing a sequence of timing signals, each of which serve as an interrupt signal to the microprocessor of the microcomputer to initiate an interrupt program for scanning inputs and preparing outputs. After this short interrupt program, the main program is resumed. In the interrupt program each of a number of registers, respectively serving separate inputs or outputs, are decremented or incremented, having been set at particular values at the beginning of each interrupt program. Some registers are set at two different values in alternation in succeeding interrupt intervals. Engine speed determination is produced by counting the number of interrupt signals during the passage of a prolonged signal representing a certain angle of shaft rotation. The frequency of timing signals is varied in steps in accordance with engine speed.

Method of controlling a microprocessor to monitor input signals at

To provide for adaptive change of the operating characteristics of an engine, so that it will operate at its optimum effectiveness, just below the knocking limit, while reliably preventing knocking thereof, a computer receives engine data from respective sensors and a knock sensor (5), from which the computer calculates, based on data stored in a memory (3), operating parameters for the engine (1). The engine is, for example, an Otto-type internal combustion engine (ICE) or a Diesel engine. The operating characteristics, as computer-modified based on sensed knocking, and the modification data, are then placed into the memory to modify the basic memory content. Preferably, the memory has a basic memory content section and a programmable differential or modification section, in which algebraic constants or modifying factors are stored, based on actual experience of operation of the engine, just under the knocking limit. Thus, the stored data on which the engine operation is controlled is continuously up-dated based on actual engine operating conditions, and thereby compensating for ageing, wear and tear of parts, different fuels, or environmental conditions or the like. The computer can likewise recognize substantial deviation of the modified characteristics from the basic characteristics and, if the modifications exceed a certain limit, provide an error or malfunction output signal to an error or malfunction output indicator (9, 4) and go into a fail-safe mode.

Engine knock control method and system with fail-safe mode

To prevent slow reestablishment of operating conditions which might lead to knocking of an internal combustion engine if the internal combustion engine operates under transient conditions, for example under conditions of rapid acceleration, the reestablishment rate of an operating control signal, for example ignition timing which, after retardation, is again advanced, transient speed changes are sensed in a differentiator (17) and, if so sensed, cause reestablishment of prior operating condition at a faster rate (f3) than otherwise, normally set into the system (see f2, FIG. 2). Additionally, the reference level of a comparator which compares sensed engine vibration signals with a reference can be increased so that, due to increased engine noise, erroneous knocking signals will not be generated by the comparator. Function generators (18, 19) which provide changed reference levels or signal weighting levels as a function of the degree or characteristics of transience, are preferably provided so that the system will respond dynamically.

Method and system to prevent knocking operation of an internal

A demodulated audio signal for detection of engine-knock is digitalized to produce a sequence of digital signals corresponding to the various cylinders of the engine in turn. These digital signals are recursively filtered by applying a factor k to a newer value and its complement (1-k) to an older value from the same cylinder or a value obtained therefrom by partial filtering and the sum of the two factor-modified terms is formed to provide a reference value with which the most recent digital signal is compared, to produce an indication of engine-knock when the latter exceeds a reference value by a predetermined amount. The factor k is varied in accordance with acceleration of engine speed or with the level of signals from the vibration sensor that exists before the application of automatic gain control prior to integration. The system, which can be implemented mostly in the software of a microcomputer, also includes provisions for adjusting from time to time minimum reference signal values for each of the cylinders, which are to be substituted for the reference signal values contemporaneously produced by recursive filtering if the latter fail to exceed the former in magnitude, and also for determining, at appropriate times, failures of the knock detection system from the absence of normal variations between the integrated signals from the respective cylinders, and providing corrective action in response thereto.

Method for detecting engine knock in internal combustion engines

A cyclical input signal for the microcomputer of a motor vehicle is caused to reset the microcomputer for avoiding persistence of errors. Another portion of the same periodic signal can advantageously be furnished to the external interrupt input of the microcomputer.

Cyclical reset of vehicular microcomputers for economic error immunity

To recognize knocking conditions in signals derived from a knock sensor, which signals representative of knocking may be masked by background or noise signals, and to clearly distinguish the knocking signal from background or noise signals, the knocking signals are integrated with respect to measuring or strobing intervals during a predetermined angle of crankshaft rotation, digitized in an A/D converter (7) and then compared in a comparator (9) with the same signals which have been passed through a low-pass digital filter (8) to compare the integrated, digitized signal of a then occurring combustion process or event with similar signals of prior combustion processes or events to thereby recognize and distinguish knocking signal conditions from noise signal conditions; digital filtering and comparison as well as sequence timing can be carried out in a single microprocessor (FIGS. 2:14), earlier combustion events being weighted in accordance with the remoteness of their occurrence and/or engine speed and engine loading, the reference signal, for example, being generated in accordance with the formula:

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Schwieberdingen, Germany

Walter Viess