EP0367973B1 - Method for detecting and processing the rotation speed of multicylinder combustion engines - Google Patents

Method for detecting and processing the rotation speed of multicylinder combustion engines Download PDF

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Publication number
EP0367973B1
EP0367973B1 EP89118008A EP89118008A EP0367973B1 EP 0367973 B1 EP0367973 B1 EP 0367973B1 EP 89118008 A EP89118008 A EP 89118008A EP 89118008 A EP89118008 A EP 89118008A EP 0367973 B1 EP0367973 B1 EP 0367973B1
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Prior art keywords
internal combustion
teeth
results
combustion engine
values
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German (de)
French (fr)
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EP0367973A1 (en
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Christoph Burckhardt
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Daimler Benz AG
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Daimler Benz AG
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0097—Electrical control of supply of combustible mixture or its constituents using means for generating speed signals

Definitions

  • the invention relates to a method for detecting and evaluating the speed in multi-cylinder internal combustion engines according to the preamble of claim 1 and a device for performing the method.
  • DE-OS 3221640 describes a method and a device for controlling an internal combustion engine.
  • a controlled variable of an internal combustion engine is continuously changed by a calculated value by enlarging and reducing it by a certain amount.
  • the internal combustion engine is operated with this changing controlled variable and the effects of the controlled variable change are observed on the operation of the internal combustion engine by repeated detection and evaluation of the speed. Based on this evaluation, the controlled variable is changed in the direction of an optimal value.
  • the detection and evaluation of the speed takes place in such a way that the speed of the internal combustion engine is determined in several counting periods in each of a predetermined operating period, the corresponding speed values are compared with one another within each operating period and the result of the comparison for determining a direction of change of the controlled variable for a subsequent operating period is used.
  • the object of the invention is to develop a method of the generic type which allows the evaluation of the speed to be used for different control purposes while avoiding the disadvantages mentioned above.
  • one work cycle is divided into several equally large intervals.
  • the rotary movement of the internal combustion engine is detected by suitable sensors and the times required for each of the predetermined intervals of the working cycle are measured. These measured values within each work cycle are stored in the order of their determination in successive memory register cells of a control device.
  • the times required for the individual intervals of the new work cycle are measured again.
  • the next method step then compares the corresponding measured times of the last work cycle with the values of the previous work cycle located in the memory register cells and, after subtraction has been carried out, replaces the stored values with the respectively newly obtained values, e.g. by overwriting the memory register contents.
  • the comparison values obtained in this way can then be used for control purposes for the internal combustion engine.
  • FIG. 1 shows a schematic diagram of a device according to the invention with an internal combustion engine 1 and an associated injection pump 2.
  • a ring gear coupled to the output shaft of the internal combustion engine 1, for example a starter gear 3, makes it possible to detect the speed of the internal combustion engine 1 with the aid of a suitable sensor 4, which can be, for example, an inductive sensor, and to the control unit 5, in which the measured Speed values are saved to pass on.
  • the control unit 5 also carries out an evaluation of the rotational speed values by means of algorithms and comparison operations and forwards the results of this evaluation to a unit 6 for controlling corresponding actuators on the internal combustion engine 1, such as the injection pump 2.
  • the functional diagram shown in Figure 2 shows a speed sensor 4, which detects the speed of a device coupled to the output shaft of an internal combustion engine, such as a starter gear.
  • the signal curve of the inductive sensor 4, for example, shown in this block is converted in a pulse shaper 7 to the signal curve shown there. After they have been divided in a frequency divider 8, the pulses from the pulse shaper 7 control a gate circuit 9, by means of which the counting pulses generated in a generator 10 reach a counter 11.
  • the length of the counting intervals ie the number of teeth of the starter gear that pass the sensor 4 during an interval, is chosen so that the ratio of the number k of these teeth is an integer divisor of the total number of teeth i of the starter gear.
  • This ratio i / k forms the divider ratio of the frequency divider 8.
  • a work cycle of the internal combustion engine - corresponding to two crankshaft revolutions in a four-stroke internal combustion engine - is divided into individual, equally large intervals during which the counting pulses from the generator 10 to the counter 11 arrive.
  • the counter reading of the counter 11 is a measure of the rotational speed of the starter gear and thus also of the internal combustion engine. It behaves inversely proportional to the speed of rotation of the internal combustion engine.
  • the measurement results of the rotational speeds in the individual Intervals of each work cycle, that is to say the counter readings for these intervals successively arrive on the one hand via a shift register 12 to a read distributor 13 and on the other hand to a subtractor 14.
  • the read-in distributor 13 gives all the measurement results of an interval one after the other to one of the successive memory register cells R 1, ..., R n of a memory register 15.
  • the measurement result of the first interval is therefore stored in the register cell R 1, that of the second interval in R 2, etc.
  • n 2i / k memory register cells, where i is the total number of teeth of the starter gear and k is the number of teeth of the starter gear, which Set counting interval, mean.
  • the individual measurement results of the intervals of the current work cycle are compared with the corresponding measurement results of the previous work cycle read out from the register 15 via a read distributor 16 coupled to the read distributor 13 with the aid of the subtractor 14 compared and evaluated for control purposes on the internal combustion engine.
  • the measurement result of each interval of the current work cycle controlled by the shift register 12, is passed to the memory register 15 and overwrites the value of the previous interval there until the results of the entire current work cycle are stored in the register 15.
  • This process is then continued periodically for each further work cycle, so that each interval of a previous work cycle is always compared with the corresponding interval of the subsequent work cycle. From this comparison, knowledge about the rotational irregularity of the internal combustion engine can be obtained, which are then evaluated for control purposes.
  • each measurement result can be unambiguously assigned to a specific cylinder or even a specific work cycle of a cylinder and - again by comparing the corresponding measurement results from successive work cycles - irregularities in the operating behavior of an individual cylinder, for example due to loss of compression, can be recognized and for control purposes, eg by means of multiple injection.
  • the mean 17 is used to form the mean value from the measurement results of all intervals of a work cycle and this mean value a is stored for a certain number m of work cycles in individual memory register cells R al ,... R on a shift register.
  • the low-pass filter 18 determines a weighted averaged speed from the memory contents of the register cells R a multiplied by the register-related weighting factor n the internal combustion engine, and in a differentiator 19, the first time derivative d n / dt this average speed.
  • Both the signal of the medium speed n , as well as that of the derivative d n / dt are supplied as input variables to a schematically represented characteristic field 20 or 21, the characteristic for the signal of the average speed n
  • the characteristic for the signal of the average speed n can have the course shown in Figure 4 and the characteristic for the signal of the derivative d n / dt, for example, the course shown in Figure 5.
  • the output variables determined from the characteristic curves n v or d n v / dt arrive at a summing point 22 and from there to a comparator or subtractor 23, which uses this signal and the results described above to compare the rotational speeds of the individual corresponding intervals that come from the subtractor 14 in the output stage 24 for control purposes generated manipulated variables of the internal combustion engine.
  • FIG. 3 shows a modification of the functional diagram according to FIG. 2, parts which match are provided with the same reference numerals as in FIG. 2.
  • the mean speed n and the derivative derived from it d n / dt not obtained from the averaged interval measured values a, but the speed pulses go directly from the pulse shaper 7 via a further gate circuit 25 and a separate counter 26 to the low-pass filter 18, where they are processed to the required values.
  • the acquisition and evaluation of the measurement results of certain intervals of the periodically recurring work cycles can be suspended in a simple manner, thereby computing time for other tasks, such as for diagnostic purposes or for obtaining of transmission time for serial interfaces.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Testing Of Engines (AREA)

Abstract

The invention relates to a method for detecting and processing the rotation speed of a multicylinder combustion engine. The rotation speed values of individual equal intervals of each work cycle of the combustion engine are stored in separate successive storage registers, compared with the corresponding values of the intervals of the following work cycle and processed for control purposes. <IMAGE>

Description

Die Erfindung betrifft ein Verfahren zur Erfassung und Auswertung der Drehzahl bei Mehrzylinder-Brennkraftmaschinen nach dem Oberbegriff des Patentanspruchs 1 sowie eine Vorrichtung zur Durchführung des Verfahrens.The invention relates to a method for detecting and evaluating the speed in multi-cylinder internal combustion engines according to the preamble of claim 1 and a device for performing the method.

Verfahren zur Regelung von Brennkraftmaschinen, bei denen bestimmte Betriebsparameter wiederholt gemessen, verglichen und zu Regelzwecken ausgewertet werden, sowie Vorrichtungen zur Durchführung solcher Verfahren sind schon mehrfach bekannt.Methods for regulating internal combustion engines, in which certain operating parameters are repeatedly measured, compared and evaluated for control purposes, and devices for carrying out such methods are already known several times.

So beschreibt z.B. die DE-OS 3221640 ein Verfahren und eine Vorrichtung zur Regelung einer Brennkraftmaschine. Eine Regelgröße einer Brennkraftmaschine wird hierbei kontinuierlich um einen berechneten Wert durch Vergrößern und Verkleinern um einen bestimmten Betrag geändert. Die Brennkraftmaschine wird mit dieser sich ändernden Regelgröße betrieben und es werden die Auswirkungen der Regelgrößenänderung auf den Betrieb der Brennkraftmaschine durch wiederholtes Erfassen und Auswerten der Drehzahl beobachtet. Aufgrund dieser Auswertung wird die Regelgröße in Richtung eines Optimalwertes hin verändert. Die Erfassung und Auswertung der Drehzahl erfolgt dabei derart, daß in jeder einer vorgegebenen Betriebsperiode in mehreren Zählperioden die Drehzahl der Brennkraftmaschine ermittelt wird, die entsprechenden Drehzahlwerte innerhalb jeder Betriebsperiode miteinander verglichen werden und das Ergebnis des Vergleichs zur Festlegung einer Änderungsrichtung der Regelgröße für eine darauffolgende Betriebsperiode benutzt wird. Die Dauer einer derartigen Betriebsperiode, innerhalb derer die Drehzahldifferenz ausgewertet wird sowie die Zählperiode selbst, erstreckt sich dabei über eine Anzahl von Zündvorgängen, so daß bei diesem Verfahren Drehzahländerungstendenzen bzw. Beschleunigungswerte nicht mehrmals pro Motorumdrehung ermittelt werden können und somit auch keine zeitkritischen Regelungsaufgaben, wie z.B. eine Antiruckelregelung, durchgeführt werden können. Ein weiterer Nachteil dieses Verfahrens ist, daß keine Aussagen gemacht werden können in Bezug auf die durch bestimmte einzelne Zylinder hervorgerufenen Drehungleichförmigkeiten der Brennkraftmaschine.For example, DE-OS 3221640 describes a method and a device for controlling an internal combustion engine. A controlled variable of an internal combustion engine is continuously changed by a calculated value by enlarging and reducing it by a certain amount. The internal combustion engine is operated with this changing controlled variable and the effects of the controlled variable change are observed on the operation of the internal combustion engine by repeated detection and evaluation of the speed. Based on this evaluation, the controlled variable is changed in the direction of an optimal value. The detection and evaluation of the speed takes place in such a way that the speed of the internal combustion engine is determined in several counting periods in each of a predetermined operating period, the corresponding speed values are compared with one another within each operating period and the result of the comparison for determining a direction of change of the controlled variable for a subsequent operating period is used. The duration of such an operating period, within which the speed difference is evaluated, as well as the counting period itself, extends over a number of ignition processes, so that with this method, speed change tendencies or acceleration values cannot be determined several times per engine revolution and therefore no time-critical control tasks, such as For example, anti-jerk control can be carried out. Another disadvantage of this method is that no statements can be made with regard to the rotational irregularities of the internal combustion engine caused by certain individual cylinders.

Aufgabe der Erfindung ist es, ein Verfahren der gattungs-gemäßen Art auszubilden, das es gestattet, die Auswertung der Drehzahl unter Vermeidung der oben genannten Nachteile zu unterschiedlichen Regelzwecken zu benutzen.The object of the invention is to develop a method of the generic type which allows the evaluation of the speed to be used for different control purposes while avoiding the disadvantages mentioned above.

Die Aufgabe wird erfindungsgemäß durch die im kennzeichnenden Teil des Patentanspruchs 1 bzw. des nebengeordneten Anspruchs 7 gelöst. Weitere Vorteile und Ausführungsformen sind Gegenstand der Unteransprüche und der Beschreibung.The object is achieved by the characterizing part of claim 1 and the independent claim 7. Further advantages and embodiments are the subject of the dependent claims and the description.

Bei einer Mehrzylinder-Brennkraftmaschine wird ein Arbeitsspiel in mehrere gleich große Intervalle aufgeteilt. Über geeignete Sensoren wird die Drehbewegung der Brennkraftmaschine erfaßt und es werden die für jedes der vorbestimmten Intervalle des Arbeitsspieles erforderlichen Zeiten gemessen. Diese Meßwerte innerhalb eines jeden Arbeitsspieles werden in der Reihenfolge ihrer Ermittlung in aufeinanderfolgenden Speicherregisterzellen eines Steuergeräts abgelegt. Im darauffolgenden Arbeitsspiel werden wieder von Neuem die für die einzelnen Intervalle des neuen Arbeitsspieles erforderlichen Zeiten gemessen. Der nächste Verfahrensschritt vergleicht dann jeweils die entsprechenden gemessenen Zeiten des letzten Arbeitsspiels mit den in den Speicherregisterzellen befindlichen Werten des vorangegangenen Arbeitsspiels und ersetzt nach durchgeführter Subtraktion die gespeicherten Werte durch die jeweils neu gewonnenen Werte, z.B. durch Überschreiben der Speicherregisterinhalte. Die derart gewonnenen Vergleichswerte können sodann zu Regelungszwecken für die Brennkraftmaschine benutzt werden.In a multi-cylinder internal combustion engine, one work cycle is divided into several equally large intervals. The rotary movement of the internal combustion engine is detected by suitable sensors and the times required for each of the predetermined intervals of the working cycle are measured. These measured values within each work cycle are stored in the order of their determination in successive memory register cells of a control device. In the subsequent work cycle, the times required for the individual intervals of the new work cycle are measured again. The next method step then compares the corresponding measured times of the last work cycle with the values of the previous work cycle located in the memory register cells and, after subtraction has been carried out, replaces the stored values with the respectively newly obtained values, e.g. by overwriting the memory register contents. The comparison values obtained in this way can then be used for control purposes for the internal combustion engine.

Ein Ausführungsbeispiel der Erfindung sei nachstehend anhand der Zeichnung beschrieben. Es zeigt

Fig. 1
eine Prinzipdarstellung einer erfindungsgemäßen Vorrichtung
Fig. 2
einen Funktionsplan des erfindungsgemäßen Verfahrens
Fig. 3
einen Funktionsplan des Verfahrens nach Figur 2 in abgewandelter Form
Fig. 4
ein Beispiel für eine die mittlere Drehzahl n beeinflussende Kennlinie
Fig. 5
ein Beispiel für eine die zeitliche Ableitung dn/dt beeinflussende Kennlinie.

An embodiment of the invention is described below with reference to the drawing. It shows
Fig. 1
a schematic diagram of a device according to the invention
Fig. 2
a functional diagram of the inventive method
Fig. 3
a functional diagram of the method of Figure 2 in a modified form
Fig. 4
an example of a mean speed n influencing characteristic
Fig. 5
an example of a time derivative d n / dt influencing characteristic.

In der Figur 1 ist in einer Prinzipskizze eine erfindungsgemäße Vorrichtung mit einer Brennkraftmaschine 1 sowie einer dazugehörigen Einspritzpumpe 2 zu sehen. Ein mit der Abtriebswelle der Brennkraftmaschine 1 gekuppelter Zahnkranz, z.B. eines Anlasserzahnrads 3, ermöglicht es, mit Hilfe eines geeigneten Sensors 4, der z.B. ein induktiver Sensor sein kann, die Drehzahl der Brennkraftmaschine 1 zu erfassen und an das Steuergerät 5, in welchem die gemessenen Drehzahlwerte gespeichert werden, weiterzugeben. Das Steuergerät 5 führt auch eine Auswertung der Drehzahlwerte mittels Algorithmen und Vergleichsoperationen durch und gibt die Ergebnisse dieser Auswertung an eine Einheit 6 zum Ansteuern entsprechender Stellglieder an der Brennkraftmaschine 1, wie z.B. der Einspritzpumpe 2, weiter.1 shows a schematic diagram of a device according to the invention with an internal combustion engine 1 and an associated injection pump 2. A ring gear coupled to the output shaft of the internal combustion engine 1, for example a starter gear 3, makes it possible to detect the speed of the internal combustion engine 1 with the aid of a suitable sensor 4, which can be, for example, an inductive sensor, and to the control unit 5, in which the measured Speed values are saved to pass on. The control unit 5 also carries out an evaluation of the rotational speed values by means of algorithms and comparison operations and forwards the results of this evaluation to a unit 6 for controlling corresponding actuators on the internal combustion engine 1, such as the injection pump 2.

Der in Figur 2 dargestellte Funktionsplan zeigt einen Drehzahlsensor 4, der die Drehzahl einer mit der Abtriebswelle einer Brennkraftmaschine gekuppelten Einrichtung, wie z.B. eines Anlasserzahnrads, erfaßt. Der in diesem Block dargestellte Signalverlauf des z.B. induktiven Sensors 4 wird in einem Impulsformer 7 zu dem dort dargestellten Signalverlauf umgeformt. Die Impulse aus dem Impulsformer 7 steuern, nachdem sie in einem Frequenzteiler 8 geteilt wurden, eine Torschaltung 9, mittels derer die in einem Generator 10 erzeugten Zählimpulse an einen Zähler 11 gelangen. Die Länge der Zählintervalle, d.h. die Anzahl der Zähne des Anlasserzahnrads, die während eines Intervalls den Sensor 4 passieren, ist so gewählt, daß das Verhältnis der Anzahl k dieser Zähne ein ganzzahliger Teiler der Gesamtzähnezahl i des Anlasserzahnrads ist. Auf diese Weise ist ein Betrieb ohne sog. Jitter, d.h. ohne Synchronisationsfehler gewährleistet. Dieses Verhältnis i/k bildet das Teilerverhältnis des Frequenzteilers 8. Mit Hilfe dieses Frequenzteilers 8 wird also ein Arbeitsspiel der Brennkraftmaschine -entsprechend zwei Kurbelwellenumdrehungen bei einer Viertakt-Brennkraftmaschine- in einzelne, gleich große Intervalle unterteilt, während derer die Zählimpulse des Generators 10 zum Zähler 11 gelangen. Durch die feste Frequenz des Zählimpulsgenerators 10 ist der Zählerstand des Zählers 11 ein Maß für die Drehgeschwindigkeit des Anlasserzahnrads und somit auch der Brennkraftmaschine. Er verhält sich dabei umgekehrt proportional zur Drehgeschwindigkeit der Brennkraftmaschine. Die Meßergebnisse der Drehgeschwindigkeiten in den einzelnen Intervallen jedes Arbeitsspieles, d.h. die Zählerstände für diese Intervalle gelangen nacheinander einerseits über ein Schieberegister 12 zu einem Einleseverteiler 13 und andererseits zu einem Subtrahierer 14.The functional diagram shown in Figure 2 shows a speed sensor 4, which detects the speed of a device coupled to the output shaft of an internal combustion engine, such as a starter gear. The signal curve of the inductive sensor 4, for example, shown in this block is converted in a pulse shaper 7 to the signal curve shown there. After they have been divided in a frequency divider 8, the pulses from the pulse shaper 7 control a gate circuit 9, by means of which the counting pulses generated in a generator 10 reach a counter 11. The length of the counting intervals, ie the number of teeth of the starter gear that pass the sensor 4 during an interval, is chosen so that the ratio of the number k of these teeth is an integer divisor of the total number of teeth i of the starter gear. In this way, operation without so-called jitter, ie without synchronization errors, is guaranteed. This ratio i / k forms the divider ratio of the frequency divider 8. With the aid of this frequency divider 8, a work cycle of the internal combustion engine - corresponding to two crankshaft revolutions in a four-stroke internal combustion engine - is divided into individual, equally large intervals during which the counting pulses from the generator 10 to the counter 11 arrive. Due to the fixed frequency of the counting pulse generator 10, the counter reading of the counter 11 is a measure of the rotational speed of the starter gear and thus also of the internal combustion engine. It behaves inversely proportional to the speed of rotation of the internal combustion engine. The measurement results of the rotational speeds in the individual Intervals of each work cycle, that is to say the counter readings for these intervals successively arrive on the one hand via a shift register 12 to a read distributor 13 and on the other hand to a subtractor 14.

Der Einleseverteiler 13 gibt alle Meßergebnisse eines Intervalls nacheinander an jeweils eine der aufeinanderfolgenden Speicherregisterzellen R₁,...,Rn eines Speicherregisters 15. Das Meßergebnis des ersten Intervalls wird also in der Registerzelle R₁ abgespeichert, das des zweiten Intervalls in R₂ usw. Bei einer Viertakt-Brennkraftmaschine, deren Kurbelwelle und damit auch das Anlasserzahnrad zwei Umdrehungen pro Arbeitsspiel durchläuft, sind zur vollständigen Speicherung aller Meßergebnisse eines Arbeitsspieles n = 2i/k Speicherregisterzellen erforderlich, wobei i die Gesamtzähnezahl des Anlasserzahnrads und k die Anzahl der Zähne des Anlasserzahnrads, die das Zählintervall festlegen, bedeuten. Bei einer Gesamtzähnezahl von beispielsweise i = 144 Zähnen des Anlasserzahnrads und einem gewählten k = 24 Zähnen für jedes Zählintervall sind demnach 2i/k = 12 Registerzellen R₁ bis R₁₂ zur Speicherung der Meßwerte eines Arbeitsspieles notwendig.The read-in distributor 13 gives all the measurement results of an interval one after the other to one of the successive memory register cells R 1, ..., R n of a memory register 15. The measurement result of the first interval is therefore stored in the register cell R 1, that of the second interval in R 2, etc. With one Four-stroke internal combustion engine, whose crankshaft and thus also the starter gear runs through two revolutions per work cycle, are required for the complete storage of all measurement results of one work cycle n = 2i / k memory register cells, where i is the total number of teeth of the starter gear and k is the number of teeth of the starter gear, which Set counting interval, mean. With a total number of teeth of, for example, i = 144 teeth of the starter gear and a selected k = 24 teeth for each counting interval, 2i / k = 12 register cells R₁ to R₁₂ are therefore necessary for storing the measured values of a working cycle.

In einem darauffolgenden Verfahrensschritt werden die einzelnen Meßergebnisse der Intervalle des momentanen Arbeitsspiels mit den über einen mit dem Einleseverteiler 13 gekoppelten Ausleseverteiler 16 aus dem Register 15 ausgelesenen entsprechenden Meßergebnissen des vorangegangenen Arbeitsspiels mit Hilfe des Subtrahierers 14 verglichen und zu Regelzwecken an der Brennkraftmaschine ausgewertet. Nach erfolgtem Vergleich wird das Meßergebnis jedes Intervalls des aktuellen Arbeitsspiels, über das Schieberegister 12 gesteuert, an das Speicherregister 15 gegeben und überschreibt dort den Wert des vorangegangenen Intervalls bis die Ergebnisse des gesamten aktuellen Arbeitsspiels im Register 15 gespeichert sind. Dieses Verfahren wird dann für jedes weitere Arbeitsspiel periodisch fortgesetzt, wobei also immer jedes Intervall eines vorangegangenen Arbeitsspiels mit dem entsprechenden Intervall des darauffolgenden Arbeitsspiels verglichen wird. Aus diesem Vergleich können Erkenntnisse über die Drehungleichförmigkeit der Brennkraftmaschine gewonnen werden, die dann zu Regelzwecken ausgewertet werden.In a subsequent process step, the individual measurement results of the intervals of the current work cycle are compared with the corresponding measurement results of the previous work cycle read out from the register 15 via a read distributor 16 coupled to the read distributor 13 with the aid of the subtractor 14 compared and evaluated for control purposes on the internal combustion engine. After the comparison has been made, the measurement result of each interval of the current work cycle, controlled by the shift register 12, is passed to the memory register 15 and overwrites the value of the previous interval there until the results of the entire current work cycle are stored in the register 15. This process is then continued periodically for each further work cycle, so that each interval of a previous work cycle is always compared with the corresponding interval of the subsequent work cycle. From this comparison, knowledge about the rotational irregularity of the internal combustion engine can be obtained, which are then evaluated for control purposes.

Dadurch, daß die genannten Messungen mehrmals während jedes Arbeitsspiels gemacht werden, können Drehzahländerungen frühzeitig erkannt werden und durch Beobachtung der Änderungstendenzen können gewollte Drehzahländerungen, wie sie z.B. die Folge eines Beschleunigungsvorganges sind, einfach und sicher von Drehungleichförmigkeiten unterschieden werden. Dies ist insbesondere beiniedrigen Drehzahlen von großer Bedeutung, da in diesem Fall das Störsignal, d.h. die Drehungleichförmigkeit, das Nutzdrehzahlsignal um ein Mehrfaches überwiegen kann. Ein weiterer Vorteil des erfindungsgemäßen Verfahrens ist darin zu sehen, daß es die Möglichkeit bietet, auch Ungleichförmigkeiten im Betriebsverhalten einzelner Zylinder festzustellen. Dies geschieht in einfacher Weise dadurch, daß das Verhältnis der Gesamtzähnezahl i des Anlasserzahnrads zur Anzahl k der Zähne in jedem Zählintervall gleich der Zylinderzahl der Brennkraftmaschine oder einem Vielfachen davon ist. Auf diese Weise läßt sich jedes Meßergebnis eindeutig einem bestimmten Zylinder bzw. sogar einem bestimmten Arbeitstakt eines Zylinders zuordnen und es können -wiederum durch Vergleich der entsprechenden Meßergebnisse von aufeinanderfolgenden Arbeitsspielen- Ungleichförmigkeiten im Betriebsverhalten eines einzelnen Zylinders, z.B. durch Kompressionsverlust, erkannt und zu Regelzwecken, z.B. mittels Mehreinspritzung, genutzt werden.Because the measurements mentioned are made several times during each work cycle, speed changes can be recognized at an early stage and by observing the change tendencies, desired speed changes, such as those resulting from an acceleration process, can be easily and reliably distinguished from rotational irregularities. This is particularly important at low speeds, since in this case the interference signal, ie the rotational non-uniformity, can outweigh the useful speed signal by a multiple. Another advantage of the method according to the invention can be seen in the fact that it offers the possibility of also determining irregularities in the operating behavior of individual cylinders. This happens in a simple way that the relationship the total number of teeth i of the starter gear to the number k of teeth in each counting interval is equal to the number of cylinders of the internal combustion engine or a multiple thereof. In this way, each measurement result can be unambiguously assigned to a specific cylinder or even a specific work cycle of a cylinder and - again by comparing the corresponding measurement results from successive work cycles - irregularities in the operating behavior of an individual cylinder, for example due to loss of compression, can be recognized and for control purposes, eg by means of multiple injection.

Aus den Meßergebnissen aller Intervalle eines Arbeitsspiels wird mit Hilfe des Glieds 17 jeweils der Mittelwert gebildet und dieser Mittelwert a für eine bestimmte Anzahl m von Arbeitsspielen in einzelnen Speicherregisterzellen Ral,...,Ram eines Schieberegisters gespeichert. Nach Ablauf einer bestimmten vorgebbaren Zeit bzw. einer bestimmten Anzahl von Arbeitsspielen ermittelt der Tiefpaß 18 aus den mit registerbezogenem Gewichtungsfaktor multiplizierten Speicherinhalten der Registerzellen Ra eine gewichtet gemittelte Drehzahl n der Brennkraftmaschine, sowie in einem Differenzierglied 19 die erste zeitliche Ableitung dn/dt dieser mittleren Drehzahl.The mean 17 is used to form the mean value from the measurement results of all intervals of a work cycle and this mean value a is stored for a certain number m of work cycles in individual memory register cells R al ,... R on a shift register. After a certain predeterminable time or a certain number of work cycles have elapsed, the low-pass filter 18 determines a weighted averaged speed from the memory contents of the register cells R a multiplied by the register-related weighting factor n the internal combustion engine, and in a differentiator 19, the first time derivative d n / dt this average speed.

Sowohl das Signal der mittleren Drehzahl n, als auch das der Ableitung dn/dt werden als Eingangsgröße je einem schematisch dargestellten Kennlinienfeld 20 bzw. 21 zugeführt, wobei die Kennlinie für das Signal der mittleren Drehzahl n z.B. den in Figur 4 gezeigten Verlauf aufweisen kann und die Kennlinie für das Signal der Ableitung dn/dt beispielsweise den in Figur 5 gezeigten Verlauf. Die aus den Kennlinien ermittelten Ausgangsgrößen n v bzw. dn v/dt gelangen zu einem Summierpunkt 22 und von dort aus zu einem Komparator bzw. Subtrahierer 23, der aus diesem Signal und den oben beschriebenen Ergebnissen des Vergleichs der Drehgeschwindigkeiten der einzelnen entsprechenden Intervalle, die vom Subtrahierer 14 stammen, in der Endstufe 24 zur Regelung der Brennkraftmaschine aufzubereitende Stellgrößen erzeugt.Both the signal of the medium speed n , as well as that of the derivative d n / dt are supplied as input variables to a schematically represented characteristic field 20 or 21, the characteristic for the signal of the average speed n For example, can have the course shown in Figure 4 and the characteristic for the signal of the derivative d n / dt, for example, the course shown in Figure 5. The output variables determined from the characteristic curves n v or d n v / dt arrive at a summing point 22 and from there to a comparator or subtractor 23, which uses this signal and the results described above to compare the rotational speeds of the individual corresponding intervals that come from the subtractor 14 in the output stage 24 for control purposes generated manipulated variables of the internal combustion engine.

Figur 3 zeigt eine Abwandlung des Funktionsplans nach Figur 2, wobei übereinstimmende Teile mit den gleichen Bezugszeichen wie in Figur 2 versehen sind. Im Unterschied zum Ausführungsbeispiel nach Figur 2 wird hierbei die mittlere Drehzahl n und die daraus ermittelte Ableitung dn/dt nicht aus den gemittelten Intervall-Meßwerten a gewonnen, sondern die Drehzahlimpulse gelangen direkt vom Impulsformer 7 über eine weitere Torschaltung 25 und einen eigenen Zähler 26 zum Tiefpaß 18, wo sie zu den erforderlichen Werten weiterverarbeitet werden.FIG. 3 shows a modification of the functional diagram according to FIG. 2, parts which match are provided with the same reference numerals as in FIG. 2. In contrast to the embodiment of Figure 2, the mean speed n and the derivative derived from it d n / dt not obtained from the averaged interval measured values a, but the speed pulses go directly from the pulse shaper 7 via a further gate circuit 25 and a separate counter 26 to the low-pass filter 18, where they are processed to the required values.

Bei einer möglichen Realisierung des Verfahrens mit Hilfe eines programmierbaren Mikroprozessors kann auf einfache Weise die Erfassung und Auswertung der Meßergebnisse bestimmter Intervalle der periodisch wiederkehrenden Arbeitsspiele ausgesetzt werden, um dadurch Rechenzeit für andere Aufgaben, wie z.B. für Diagnosezwecke oder zur Gewinnung von Übertragungszeit für serielle Schnittstellen, zu schaffen.In the case of a possible implementation of the method with the aid of a programmable microprocessor, the acquisition and evaluation of the measurement results of certain intervals of the periodically recurring work cycles can be suspended in a simple manner, thereby computing time for other tasks, such as for diagnostic purposes or for obtaining of transmission time for serial interfaces.

Desweiteren ist es bei dem Einsatz eines Mikroprozessors möglich, einfache, jedoch echtzeitkritische Operationen, wie z.B. die Zähl- oder Vergleichsoperationen innerhalb des Verfahrens, über Hard- bzw. Firmware zu realisieren, während aufwendigere und rechenzeitintensive Operationen, wie sie z.B. die Mittelwertbildung und die Differenzierung darstellen, im Hintergrund über Softwarerealisierung ablaufen, um dann als Vergleichs- bzw. Korrekturwert im Komparator/ Subtrahierer 23 Berücksichtigung zu finden.Furthermore, when using a microprocessor, it is possible to perform simple but real-time-critical operations, such as the counting or comparison operations within the method to be implemented via hardware or firmware, while more complex and computation-intensive operations, such as those e.g. represent the averaging and differentiation, run in the background via software implementation in order to then be taken into account as a comparison or correction value in the comparator / subtractor 23.

Claims (10)

1. A method of detection and evaluation of the rotational speed in multicylinder internal combustion engines with a sensor for detecting the rotational speed, a control unit with memory registers for storing the measured rotational speed values and with a comparator for evaluating the stored values of specific memory registers and momentary values, as well as with a unit for driving corresponding regulating units with the results of this evaluation to influence the internal combustion engine, the following recurrent steps being performed:
a) measurement of the times required for specific successive intervals of equal length of a working cycle;
b) storage of these measuring results in separate successive memory registers (R₁,...,Rn);
c) repetition of step a) for the following operational cycle, characterized by
d) subtraction of the corresponding individual measuring results of the two successive operational cycles and replacement of the measuring results of the preceding operational cycle stored in the corresponding registers (R₁,....,Rn) by the corresponding measuring results of the following operational cycle;
e) evaluation of the result of the comparison for regulation purposes.
2. A method according to claim 1, characterised by the measurement of the time required for the passing by of a specific number (k) of teeth of a toothed crown coupled with the power take-off of the internal combustion engine.
3. A method according to claim 1 or 2, characterised in that comparison is effected of the individual measuring results with a comparison value obtained from the weighted mean values (n) from the measurement results of the preceding operational cycles.
4. A method according to one of claims 1 to 3, characterised in that comparison is effected of the individual measurement results with a comparison value obtained from the weighted mean values of the time derivations (dn/dt) from the measurement results of the preceding operational cycles.
5. A method according to one of claims 1 to 4, characterised in that the process steps of specific intervals of the periodically recurring operational cycles are set out.
6. A method according to one of claims 1 to 5, characterised in that time-critical simple process steps are performed by hard/firmware, whereas computing time intensive, non-time-critical process steps are performed by software and take place in the background.
7. An apparatus for the detection and evaluation of rotational speed in multicylinder internal combustion engines with a sensor for detecting the rotational speed, a control unit with memory registers for storing the measured rotational speed values, and with a comparator for evaluating the stored values of specific memory registers and momentary values, as well as with a unit for driving corresponding regulating units with the results of this evaluation to influence the internal combustion engine, for carrying out the method according to claim 1, the following means being provided:
a) means for the measurement of the times required for specific successive intervals of equal length of an operational cycle;
b) means for the storage of these measurement results in separate successive memory registers (R₁,...,Rn);
c) means for the repetition of step a) for the following operational cycle, characterized by
d) means for the subtraction of the corresponding individual measurement results of the two successive operational cycles and replacement of the measurement results of the preceding operational cycle stored in the corresponding registers (R₁,....,Rn) by the corresponding measurement results of the following operational cycle;
e) means for the evaluation of the result of the comparison for regulation purposes.
8. An apparatus according to claim 7, characterized in that, for measuring time, the teeth of a starter toothed wheel (3) are detected by a sensor (4), and the number (k) of the teeth detected during the respective individual measurements is a divisor of the total number of teeth (i) of the starter toothed wheel (3).
9. An apparatus according to claim 7 or 8, characterized in that, for measuring time, the teeth of a starter toothed wheel (3) are detected by a sensor (4), and the ratio of the total number of teeth (i) of the starter toothed wheel (3) to the number (k) of the teeth detected for an individual measurement corresponds to the cylinder number of the internal combustion engine (1) or to a multiple thereof.
10. An apparatus according to one of claims 7 to 9, characterized in that the sensor (4) is an inductive sensor.
EP89118008A 1988-10-14 1989-09-28 Method for detecting and processing the rotation speed of multicylinder combustion engines Expired - Lifetime EP0367973B1 (en)

Priority Applications (1)

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AT89118008T ATE70896T1 (en) 1988-10-14 1989-09-28 PROCEDURE FOR DETECTING AND EVALUATING THE RPM IN MULTI-CYLINDER COMBUSTION ENGINES.

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DE3835002A DE3835002C3 (en) 1988-10-14 1988-10-14 Process for recording and evaluating the speed in multi-cylinder internal combustion engines
DE3835002 1988-10-14

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EP0367973B1 true EP0367973B1 (en) 1991-12-27

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DE4319677C2 (en) * 1993-06-14 2002-08-01 Bosch Gmbh Robert Method and device for regulating the smooth running of an internal combustion engine
DE19959679A1 (en) * 1999-12-10 2001-06-21 Bosch Gmbh Robert Method and device for suppressing speed fluctuations
DE10143953B4 (en) * 2001-09-07 2005-12-29 Siemens Ag Speed detection method
DE10218641B4 (en) * 2002-04-25 2006-11-30 Bayerische Motoren Werke Ag Engine speed determination
DE102019201149A1 (en) * 2019-01-30 2020-07-30 Robert Bosch Gmbh Method for diagnosing a leak in a cylinder of an internal combustion engine

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DE3835002C2 (en) 1991-05-08
DE58900633D1 (en) 1992-02-06
DE3835002A1 (en) 1990-04-19
DE3835002C3 (en) 1994-02-24
EP0367973A1 (en) 1990-05-16
ATE70896T1 (en) 1992-01-15

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