EP0119297B1 - Measurement apparatus for continuously determining operating parameters of a combustion engine - Google Patents

Measurement apparatus for continuously determining operating parameters of a combustion engine Download PDF

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Publication number
EP0119297B1
EP0119297B1 EP83110244A EP83110244A EP0119297B1 EP 0119297 B1 EP0119297 B1 EP 0119297B1 EP 83110244 A EP83110244 A EP 83110244A EP 83110244 A EP83110244 A EP 83110244A EP 0119297 B1 EP0119297 B1 EP 0119297B1
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EP
European Patent Office
Prior art keywords
measurement apparatus
sensor
transistor
current source
coupling device
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EP83110244A
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German (de)
French (fr)
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EP0119297A2 (en
EP0119297A3 (en
Inventor
Ulrich Flaig
Werner Fischer
Johannes Locher
Wolfgang Schmidt
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Robert Bosch GmbH
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Robert Bosch GmbH
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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
    • F02D41/20—Output circuits, e.g. for controlling currents in command coils
    • 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
    • F02D41/20—Output circuits, e.g. for controlling currents in command coils
    • F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2055—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit with means for determining actual opening or closing time
    • 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
    • F02D41/20—Output circuits, e.g. for controlling currents in command coils
    • F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2058—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit using information of the actual current value

Definitions

  • the invention is based on a measuring device according to claim 1, first part (compare DE-OS-3 032 381), in particular a measuring device for an internal combustion engine equipped with injection valves for detecting the start of injection with a nozzle needle controlled by a power source Path-voltage converter.
  • the current sources commonly used in this connection are known, for example, from Tietze-Schenk, Semiconductor Circuit Technology, 4th Edition, page 53ff.
  • the use of a Zener diode to determine the base potential of the transistor has proven to be particularly advantageous, so that the control of the transistor is largely independent of small fluctuations in the operating voltage.
  • the amplitudes of the useful signals have a speed-dependent behavior.
  • Such comparators equipped with speed-dependent thresholds are known per se, for example from DE-OS 24 49 836, and a speed-controlled power supply is also known, for example, from EP-A 68 323 (cf. FIG. 4).
  • the measuring device according to the invention for detecting the time of injection with the characterizing features of the main claim has the advantage that a significantly improved useful signal to interference signal ratio is achieved by using a regulated current source stabilized against supply voltage fluctuations.
  • Another advantage of the invention lies in the fact that the current source can be controlled as a function of the speed. With suitable dimensioning of this control, a useful signal amplitude independent of the speed can be realized.
  • FIG. 1 shows a block diagram of a control device of a diesel internal combustion engine
  • FIG. 2 shows a refined block diagram of the evaluation stage of the needle lift sensor in two exemplary embodiments
  • FIG. 3 shows a detailed exemplary embodiment of the current source
  • FIG. 4 shows several exemplary embodiments of the means for stabilizing the current source against supply voltage fluctuations.
  • 10 denotes the internal combustion engine itself, to which an air intake pipe 11 leads and an exhaust pipe 12 leads away.
  • the internal combustion engine 10 is bridged with an exhaust gas recirculation line 13, so that the mixing ratio of exhaust gas to fresh air can be adjusted by means of a mixing flap 15 actuated by an exhaust gas recirculation control stage 14.
  • the fuel pressure required for injection is built up by a pump 16 which is connected to a tank 17 on the suction side.
  • a quantity control stage 18 and an injection start regulator 19 provide the control or regulating signals for the pump 16.
  • a speed sensor 24, an accelerator pedal position sensor 20 and a needle stroke sensor 21 are used as measured value sensors.
  • the needle stroke sensor 21 is followed by an evaluation stage 23, which supplies the start of injection actual value of the start of injection 19.
  • the output of the speed sensor 19 is connected to the exhaust gas recirculation stage 14, the quantity control stage 18, the injection start controller 19, the evaluation stage 23 and the load detection stage 22.
  • this evaluation stage 23 conventional structure is not among all in the Motor vehicle occurring conditions works satisfactorily.
  • the invention relates to an improvement of this evaluation stage 23, which is shown in more detail in the exemplary embodiments in FIGS. 2a and 2b.
  • the needle stroke sensor 21, which is designed as an inductive transmitter in both exemplary embodiments FIGS. 2a and 2b, is fed by a current source 30 or 30 '.
  • the capacitively decoupled voltage drop occurring at the inductor is inverted by an amplifier stage 31 and converted into digital information by a monoflop 32 or 32 'provided with a threshold switch.
  • the induction voltage occurring at the needle stroke sensor 21 should be based on a temporal change in the inductance generated only by the movement of the nozzle needle. However, this requires a constant or only very slowly changing current flow through the inductor. This condition is only met to a limited extent by the known power sources used in automotive electronics. Especially in special situations, such as B. when the supply voltage drops when the internal combustion engine starts, these unregulated current sources are not able to suppress interference pulses located on the supply voltage. These disadvantages are avoided by the arrangement according to the invention in FIG. 3.
  • the signal tapped via the inductance has a speed-dependent amplitude.
  • a speed-dependent threshold switch in the Monoflop 32 instead of a constant threshold value.
  • Another object of the invention is to use the speed signal in the sense of controlling the current source 30 'that the induction signal picked up via the coil already has a speed-independent amplitude.
  • regulation of, for example, the peak value or the mean value of the voltage drop coupled out on the inductance can be carried out.
  • the current source delivers more or less current in such a way that the signal amplitude assumes a constant value despite fluctuations in the various parameters (speed, temperature, sensor spread).
  • the measuring device can be used with all sensors controlled by a current source, e.g. B. with Hall sensors, inductive sensors, NTC (PTC) sensors or sensors provided with heating elements of constant heating power regardless of their application z.
  • B. can be used as a speed sensor, knock sensor, temperature sensor or mass flow sensor.
  • FIG. 3 shows a circuit diagram of the current source 30 according to the invention, in which the series arrangement comprising a resistor 40, a pnp transistor 41 and the needle stroke sensor 21 is connected between the supply voltage and ground.
  • the output voltage U ′′ present at the collector of transistor 41 is led via a low-pass filter consisting of a resistor 42 and a capacitor 43 to the positive input of an operational amplifier 44.
  • the negative input of the operational amplifier 44 is the center tap of a voltage divider from the resistors 45 which is supplied with the supply voltage and 46 connected.
  • the output signal fed back to the minus input of the operational amplifier 44 via a resistor 47 controls the base of the transistor 41 via a resistor 48.
  • the base of the transistor 41 is connected to the supply voltage via a coupling device 49 to be described in more detail.
  • 50 and 51 denote Zener diodes which can be inserted parallel to the coupling device 49 and / or to the resistor 46. It is also provided to apply a speed-dependent signal to the positive input of the operational amplifier 44 via a resistor 52 and a diode 53.
  • the DC voltage component of the output voltage is fed back to the positive input of operational amplifier 44.
  • the operational amplifier 44 controls the transistor 41 in such a way that the voltage U "applied to the collector is equal to the reference voltage applied to the minus input generated by the voltage divider from the resistors 45 and 46.
  • the reference voltage at the minus input of the operational amplifier drops 44 to smaller values, the transistor 41 is controlled somewhat further into the blocking region until U A again has the same value as the reference voltage, thereby ensuring that the transistor does not operate in the switched-on state, but always in the most favorable modulation range, even in the event of strong supply voltage dips becomes.
  • a current limitation of the current source is provided.
  • the Zener diode 50 and / or the Zener diode 51 are used for this purpose.
  • FIG. 4 shows some exemplary embodiments of this coupling device 49.
  • this coupling device consists of a capacitor which should be quite large due to the low impedance of the base and which is therefore expediently designed as an electrolytic capacitor.
  • an operational amplifier operated as an impedance converter with a capacitor connected downstream of the output is used.
  • the transistor 41 is designed as a field effect transistor in accordance with FIG. 4c, because of the high impedance of the gate, very small, interference-free and inexpensive capacitors can be used for coupling.
  • the measuring device With the aid of the measuring device according to the invention for detecting the injection time, a considerable improvement in the useful signal to interference signal ratio is achieved.
  • the measuring device remains functional even in extreme but unavoidable situations in motor vehicle operation.
  • the speed-dependent control of the current source also proves to be advantageous, with which it is possible to generate an injection start signal with a speed-independent amplitude over the entire speed range of the internal combustion engine.
  • the influence of further parameters, such as temperature, sensor spread, etc. on the signal amplitude can be switched off, so that digitizing the useful signal with constant accuracy (no time error due to different signal amplitudes with constant trigger threshold of the monoflops) is considerably simplified .

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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 Or Calibration Of Command Recording Devices (AREA)
  • Testing Of Engines (AREA)

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einer Meßeinrichtung gemäß Anspruch 1, erster Teil (vergleiche DE-OS-3 032 381), insbesondere von einer Meßeinrichtung für eine mit Einspritzventilen ausgestattete Brennkraftmaschine zum Erfassen des Spritzbeginns mit einem, von einer Stromquelle angesteuerten, auf die Düsennadel empfindlichen Weg-Spannungs-Wandler.The invention is based on a measuring device according to claim 1, first part (compare DE-OS-3 032 381), in particular a measuring device for an internal combustion engine equipped with injection valves for detecting the start of injection with a nozzle needle controlled by a power source Path-voltage converter.

Aus der DE-OS 30 32 381 ist eine Meßeinrichtung an einer Brennkraftmaschine zur dauernden Erfassung des Düsennadelhubs mit einem Nadelhubsensor 49, der an eine Stromquelle 48 angeschlossen ist (vgl. Figur 4) bekannt. Diese Stromquelle ist als Konstantstromquelle ausgebildet.From DE-OS 30 32 381 a measuring device on an internal combustion engine for the continuous detection of the nozzle needle stroke with a needle stroke sensor 49, which is connected to a current source 48 (cf. FIG. 4), is known. This current source is designed as a constant current source.

Die in diesem Zusammenhang üblicherweise verwendeten Stromquellen sind beispielsweise aus Tietze-Schenk, Halbleiterschaltungstechnik, 4. Auflage, Seite 53ff bekannt. Als vorteilhaft erweist sich insbesondere der Einsatz einer Zenerdiode zur Bestimmung des Basispotentials des Transistors, so daß die Ansteuerung des Transistors weitgehend unabhängig von kleinen Betriebsspannungsschwankungen ist.The current sources commonly used in this connection are known, for example, from Tietze-Schenk, Semiconductor Circuit Technology, 4th Edition, page 53ff. The use of a Zener diode to determine the base potential of the transistor has proven to be particularly advantageous, so that the control of the transistor is largely independent of small fluctuations in the operating voltage.

Die bekannten Einrichtungen haben jedoch im rauhen Kraftfahrzeugbetrieb folgende Nachteile aufgewiesen:However, the known devices have the following disadvantages in rough motor vehicle operation:

Infolge von Temperaturdriften sämtlicher Bauteile der Stromquelle und insbesondere bei niedrigen Batteriespannungen, wie sie beispielsweise im Startfall auftreten, arbeitet diese Stromquelle unbefriedigend. So wird beim Absinken der Batteriespannung auf niedrige Werte der Transistor der Stromquelle voll durchgeschaltet und alle auf der Versorgungsspannung befindlichen Störsignale werden als Nutzsignale ausgewertet.As a result of temperature drifts of all components of the power source and in particular at low battery voltages, such as occur, for example, when starting, this power source works unsatisfactorily. Thus, when the battery voltage drops to low values, the transistor of the current source is fully switched on and all interference signals on the supply voltage are evaluated as useful signals.

Weiterhin erweist es sich als nachteilig, daß die Amplituden der Nutzsignale ein drehzahlabhängiges Verhalten aufweisen. Hieraus folgt die Notwendigkeit, entweder die für eine digitale Signalweiterverarbeitung verwendeten Komparatoren mit drehzahlabhängigen Schwellen auszurüsten, um größere Fehler in der Spritzbeginnbestimmung zu vermeiden oder eine drehzahlgeregelte Stromversorgung des Sensors vorzusehen. Derartige mit drehzahlabhängigen Schwellen ausgestattete Komparatoren sind an sich beispielsweise aus der DE-OS 24 49 836 bekannt und auch eine drehzahlgeregelte Stromversorgung ist beispielsweise aus der EP-A 68 323 bekannt (vgl. Figur 4).Furthermore, it proves to be disadvantageous that the amplitudes of the useful signals have a speed-dependent behavior. This results in the need either to equip the comparators used for digital signal processing with speed-dependent thresholds in order to avoid major errors in the start of injection determination or to provide a speed-controlled power supply for the sensor. Such comparators equipped with speed-dependent thresholds are known per se, for example from DE-OS 24 49 836, and a speed-controlled power supply is also known, for example, from EP-A 68 323 (cf. FIG. 4).

Aus «Electronic Industries, Band 22, Nr. 12, Dezember 63, Seiten 63 und 64" ist eine Schaltungsanordnung bekannt, mit deren Hilfe zur Vermeidung von Störsignalen in Stromversorgungsanlagen die Versorgungsspannungsschwankungen mit Hilfe eines Kondensators auf die Basis eines Transistors eingekoppelt werden (siehe z. B. Figur 1, Signal an Basis von T2). Vorteile der ErfindungFrom "Electronic Industries, Volume 22, No. 12, December 63, pages 63 and 64 " a circuit arrangement is known, with the help of which to avoid interference signals in power supply systems, the supply voltage fluctuations are coupled in with the aid of a capacitor on the base of a transistor (see e.g. 1, signal based on T2) Advantages of the invention

Die erfindungsgemäße Meßeinrichtung zur Erfassung des Einspritzzeitpunktes mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß durch die Verwendung einer geregelten und gegen Versorgungsspannungsschwankungen stabilisierten Stromquelle ein erheblich verbessertes Nutzsignal zu Störsignal-Verhältnis erreicht wird.The measuring device according to the invention for detecting the time of injection with the characterizing features of the main claim has the advantage that a significantly improved useful signal to interference signal ratio is achieved by using a regulated current source stabilized against supply voltage fluctuations.

Ein weiterer Vorteil der Erfindung besteht in der Tatsache, daß die Stromquelle als Funktion der Drehzahl steuerbar ist. Bei geeigneter Dimensionierung dieser Steuerung läßt sich eine von der Drehzahl unabhängige Nutzsignalamplitude realisieren.Another advantage of the invention lies in the fact that the current source can be controlled as a function of the speed. With suitable dimensioning of this control, a useful signal amplitude independent of the speed can be realized.

Durch die in den Unteransprüchen aufgeführten Maßnahmen ist eine vorteilhafte Weiterbildung und Verbesserung der im Haupt- und Nebenanspruch angegebenen Einrichtung zum Erfassen des Einspritzzeitpunktes möglich. So hat es sich aufgrund von Problemen mit der Verlustleistung des Transistors als günstig erwiesen, die Stromquelle mit einer Strombegrenzung auszustatten.The measures listed in the subclaims enable advantageous further development and improvement of the device specified in the main and subclaim for detecting the injection time. Because of problems with the power loss of the transistor, it has proven advantageous to provide the current source with a current limiter.

Weitere vorteilhafte Ausgestaltungen ergeben sich aus der nachfolgenden Beschreibung der Ausführungsbeispiele und den zugehörigen Zeichnungen.Further advantageous configurations result from the following description of the exemplary embodiments and the associated drawings.

Zeichnungdrawing

Es zeigen Figur 1 ein Blockschaltbild einer Steuereinrichtung einer Dieselbrennkraftmaschine, Figur 2 ein verfeinertes Blockschaltbild der Auswertestufe des Nadelhubsensors in zwei Ausführungsbeispielen, Figur 3 ein detailliertes Ausführungsbeispiel der Stromquelle und Figur 4 mehrere Ausführungsbeispiele der Mittel zur Stabilisierung der Stromquelle gegen Versorgungsspannungsschwankungen.FIG. 1 shows a block diagram of a control device of a diesel internal combustion engine, FIG. 2 shows a refined block diagram of the evaluation stage of the needle lift sensor in two exemplary embodiments, FIG. 3 shows a detailed exemplary embodiment of the current source and FIG. 4 shows several exemplary embodiments of the means for stabilizing the current source against supply voltage fluctuations.

Beschreibung der AusführungsbeispieleDescription of the embodiments

In Figur 1 ist mit 10 die Brennkraftmaschine an sich bezeichnet, zu der ein Luftansaugrohr 11 hin-und ein Abgasrohr 12 wegführt. Die Brennkraftmaschine 10 ist mit einer Abgasrückführleitung 13 überbrückt, so daß das Mischungsverhältnis von Abgas zu Frischluft mittels einer von einer Abgasrückführungssteuerstufe 14 betätigten Mischklappe 15 eingestellt werden kann. Der zur Einspritzung notwendige Kraftstoffdruck wird von einer Pumpe 16 aufgebaut, die ansaugseitig mit einem Tank 17 verbunden ist. Eine Mengensteuerstufe 18 und ein Spritzbeginnregler 19 liefern die Steuer- bzw. Regelsignale für die Pumpe 16.In FIG. 1, 10 denotes the internal combustion engine itself, to which an air intake pipe 11 leads and an exhaust pipe 12 leads away. The internal combustion engine 10 is bridged with an exhaust gas recirculation line 13, so that the mixing ratio of exhaust gas to fresh air can be adjusted by means of a mixing flap 15 actuated by an exhaust gas recirculation control stage 14. The fuel pressure required for injection is built up by a pump 16 which is connected to a tank 17 on the suction side. A quantity control stage 18 and an injection start regulator 19 provide the control or regulating signals for the pump 16.

Im vorliegenden Ausführungsbeispiel dienen als Meßwertaufnehmer ein Drehzahlsensor 24, ein Fahrpedalstellungssensor 20 sowie ein Nadelhubsensor 21. Die Ausgangssignale des Fahrpedalstellungssensors 20 werden von einer Lasterkennungsstufe 22 ausgewertet, die ihrerseits ausgangsseitig mit der Abgasrückführungssteuerstufe 14, der Mengensteuerstufe 18 und dem Spritzbeginnregler 19 verbunden ist. Dem Nadelhubsensor 21 ist eine Auswertestufe 23 nachgeschaltet, die dem Spritzbeginnregler 19 den Spritzbeginn-Istwert liefert. Der Ausgang des Drehzahlsensors 19 ist mit der Abgasrückführungsstufe 14, der Mengensteuerstufe 18, dem Spritzbeginnregler 19, der Auswertestufe 23 und der Lasterkennungsstufe 22 verbunden.In the present exemplary embodiment, a speed sensor 24, an accelerator pedal position sensor 20 and a needle stroke sensor 21 are used as measured value sensors. The needle stroke sensor 21 is followed by an evaluation stage 23, which supplies the start of injection actual value of the start of injection 19. The output of the speed sensor 19 is connected to the exhaust gas recirculation stage 14, the quantity control stage 18, the injection start controller 19, the evaluation stage 23 and the load detection stage 22.

Es hat sich nun gezeigt, daß diese Auswertestufe 23 herkömmlichen Aufbaus nicht unter allen im Kraftfahrzeug vorkommenen Bedingungen zufriedenstellend arbeitet. Die Erfindung bezieht sich auf eine Verbesserung dieser Auswertestufe 23, die in den Ausführungsbeispielen Figur 2a und 2b detaillierter dargestellt ist.It has now been shown that this evaluation stage 23 conventional structure is not among all in the Motor vehicle occurring conditions works satisfactorily. The invention relates to an improvement of this evaluation stage 23, which is shown in more detail in the exemplary embodiments in FIGS. 2a and 2b.

Der Nadelhubsensor 21, der in beiden Ausführungsbeispielen Figur 2a und 2b als Induktivgeber ausgebildet ist, wird von einer Stromquelle 30 bzw. 30' gespeist. Der an der Induktivität auftretende, kapazitiv ausgekoppelte Spannungsabfall wird von einer Verstärkerstufe 31 invertiert und von einem mit einem Schwellwertschalter versehenen Monoflop 32 bzw. 32' in eine Digitalinformation gewandelt. Im Idealfall sollte die am Nadelhubsensor 21 auftretende Induktionsspannung auf einer, nur durch die Bewegung der Düsennadel erzeugten zeitlichen Änderung der Induktivität beruhen. Dies setzt jedoch einen konstanten, bzw. nur sehr langsam zeitlich veränderlichen Stromfluß durch die Induktivität voraus. Diese Bedingung wird durch die bekannten, in der Kraftfahrzeugelektronik verwendeten Stromquellen nur beschränkt erfüllt. Gerade in Sondersituationen, wie z. B. beim Absinken der Versorgungsspannung im Startfall der Brennkraftmaschine sind diese ungeregelten Stromquellen nicht in der Lage, auf der Versorgungsspannung befindliche Störimpulse zu unterdrücken. Diese Nachteile werden von der erfindungsgemäßen Anordnung in Figur 3 vermieden.The needle stroke sensor 21, which is designed as an inductive transmitter in both exemplary embodiments FIGS. 2a and 2b, is fed by a current source 30 or 30 '. The capacitively decoupled voltage drop occurring at the inductor is inverted by an amplifier stage 31 and converted into digital information by a monoflop 32 or 32 'provided with a threshold switch. Ideally, the induction voltage occurring at the needle stroke sensor 21 should be based on a temporal change in the inductance generated only by the movement of the nozzle needle. However, this requires a constant or only very slowly changing current flow through the inductor. This condition is only met to a limited extent by the known power sources used in automotive electronics. Especially in special situations, such as B. when the supply voltage drops when the internal combustion engine starts, these unregulated current sources are not able to suppress interference pulses located on the supply voltage. These disadvantages are avoided by the arrangement according to the invention in FIG. 3.

Weiterhin ist bekannt, daß das über der Induktivität abgegriffene Signal eine drehzahlabhängige Amplitude aufweist. Zur Vermeidung von daraus resultierenden Fehlern bei der Spritzbeginnauswertung ist es erforderlich, bei dem Monoflop 32 anstelle eines konstanten Schwellwertes einen drehzahlabhängigen Schwellwertschalter zu verwenden. Ein weiterer Gegenstand der Erfindung ist es, das Drehzahlsignal in dem Sinne zur Steuerung der Stromquelle 30' zu verwenden, daß schon das über der Spule abgegriffene Induktionssignal eine drehzahlunabhängige Amplitude aufweist. Um auch die Amplitudenabhängigkeit von anderen Parametern wie Temperatur oder auch Geberstreuungen auszuschalten, kann eine Regelung beispielsweise des Spitzenwertes oder des Mittelwertes des an der Induktivität ausgekoppelten Spannungsabfalls durchgeführt werden. In Abhängigkeit vom Wert der ausgekoppelten Wechselspannung liefert die Stromquelle mehr oder weniger Strom in der Weise, daß die Signalamplitude trotz Schwankungen der verschiedenen Parameter (Drehzahl, Temperatur, Geberstreuung) einen konstanten Wert annimmt. Dies hat den Vorteil, daß bei der anschließenden Digitalisierung des analogen Nutzsignals die Schwelle der Monoflops 32, 32' auf einen festen, nicht von Exemplar zu Exemplar neu festzulegenden Wert eingestellt werden kann.It is also known that the signal tapped via the inductance has a speed-dependent amplitude. To avoid the resulting errors in the evaluation of the start of injection, it is necessary to use a speed-dependent threshold switch in the Monoflop 32 instead of a constant threshold value. Another object of the invention is to use the speed signal in the sense of controlling the current source 30 'that the induction signal picked up via the coil already has a speed-independent amplitude. In order to also switch off the amplitude dependency of other parameters such as temperature or sensor spreading, regulation of, for example, the peak value or the mean value of the voltage drop coupled out on the inductance can be carried out. Depending on the value of the extracted AC voltage, the current source delivers more or less current in such a way that the signal amplitude assumes a constant value despite fluctuations in the various parameters (speed, temperature, sensor spread). This has the advantage that, during the subsequent digitization of the analog useful signal, the threshold of the monoflops 32, 32 'can be set to a fixed value which is not to be redefined from copy to copy.

Darüber hinaus ist eine verallgemeinerte, nicht auf die Erfassung des Spritzbeginns bezogene Anwendungsmöglichkeit dieser Meßeinrichtung denkbar. Die Meßeinrichtung kann bei allen mit einer Stromquelle angesteuerten Sensoren, so z. B. bei Hall-Sensoren, Induktiv-Sensoren, NTC-(PTC)-Sensoren oder auch mit Heizelementen konstanter Heizleistung versehenen Sensoren unabhängig von ihrer Anwendung z. B. als Drehzahlsensor, Klopfsensor, Temperatursensor oder auch Massendurchflußsensor eingesetzt werden.In addition, a generalized application of this measuring device, which is not related to the detection of the start of injection, is conceivable. The measuring device can be used with all sensors controlled by a current source, e.g. B. with Hall sensors, inductive sensors, NTC (PTC) sensors or sensors provided with heating elements of constant heating power regardless of their application z. B. can be used as a speed sensor, knock sensor, temperature sensor or mass flow sensor.

Figur 3 zeigt ein Schaltbild der erfindungsgemäßen Stromquelle 30, in der die Serienanordnung aus einem Widerstand 40, einen pnp-Transistor 41 und dem Nadelhubsensor 21 zwischen Versorgungsspannung und Masse geschaltet ist. Die am Kollektor des Transistors 41 anliegende Ausgangsspannung U" wird über einen aus einem Widerstand 42 und einem Kondensator 43 bestehenden Tiefpaß auf den Pluseingang eines Operationsverstärkers 44 geführt. Der Minuseingang des Operationsverstärkers 44 ist mit dem Mittelabgriff eines mit der Versorgungsspannung beaufschlagten Spannungsteilers aus den Widerständen 45 und 46 verbunden.FIG. 3 shows a circuit diagram of the current source 30 according to the invention, in which the series arrangement comprising a resistor 40, a pnp transistor 41 and the needle stroke sensor 21 is connected between the supply voltage and ground. The output voltage U ″ present at the collector of transistor 41 is led via a low-pass filter consisting of a resistor 42 and a capacitor 43 to the positive input of an operational amplifier 44. The negative input of the operational amplifier 44 is the center tap of a voltage divider from the resistors 45 which is supplied with the supply voltage and 46 connected.

Das über einen Widerstand 47 auf den Minuseingang des Operationsverstärkers 44 rückgekoppelte Ausgangssignal steuert über einen Widerstand 48 die Basis des Transistors 41. Über eine noch näher zu beschreibende Kopplungseinrichtung 49 ist die Basis des Transistors 41 mit der Versorgungsspannung verbunden.The output signal fed back to the minus input of the operational amplifier 44 via a resistor 47 controls the base of the transistor 41 via a resistor 48. The base of the transistor 41 is connected to the supply voltage via a coupling device 49 to be described in more detail.

Weitere mögliche Ausbildungen der Stromquelle sind durch die gestrichelt eingefügten Bauelemente möglich. Mit 50 und 51 sind Zenerdioden bezeichnet, die parallel zur Koppeleinrichtung 49 und/oder zum Widerstand 46 eingefügt werden können. Weiterhin ist vorgesehen, den Pluseingang des Operationsverstärkers 44 über einen Widerstand 52 und eine Diode 53 mit einem drehzahlabhängigen Signal zu beaufschlagen.Further possible designs of the current source are possible by means of the components inserted in dashed lines. 50 and 51 denote Zener diodes which can be inserted parallel to the coupling device 49 and / or to the resistor 46. It is also provided to apply a speed-dependent signal to the positive input of the operational amplifier 44 via a resistor 52 and a diode 53.

Die Funktionsweise der Schaltung von Figur 3 ist im folgenden beschrieben.The operation of the circuit of Figure 3 is described below.

Über den Tiefpaß bestehend aus Widerstand 42 und Kondensator 43 wird der Gleichspannungsanteil der Ausgangsspannung auf den Pluseingang des Operationsverstärkers 44 rückgekoppelt. Der Operationsverstärker 44 steuert den Transistor 41 in der Weise an, daß die am Kollektor anliegende Spannung U" gleich der am Minuseingang anliegenden, durch den Spannungsteiler aus den Widerständen 45 und 46 erzeugten Referenzspannung ist. Sinkt z. B. die Referenzspannung am Minuseingang des Operationsverstärkers 44 auf kleinere Werte ab, so wird der Transistor 41 etwas weiter in den Sperrbereich gesteuert bis UA wieder den gleichen Wert wie die Referenzspannung besitzt. Dadurch ist gewährleistet, daß der Transistor selbst bei starken Versorgungsspannungseinbrüchen nicht im durchgeschalteten Zustand sondern immer im günstigsten Aussteuerungsbereich betrieben wird.Via the low-pass filter consisting of resistor 42 and capacitor 43, the DC voltage component of the output voltage is fed back to the positive input of operational amplifier 44. The operational amplifier 44 controls the transistor 41 in such a way that the voltage U "applied to the collector is equal to the reference voltage applied to the minus input generated by the voltage divider from the resistors 45 and 46. For example, the reference voltage at the minus input of the operational amplifier drops 44 to smaller values, the transistor 41 is controlled somewhat further into the blocking region until U A again has the same value as the reference voltage, thereby ensuring that the transistor does not operate in the switched-on state, but always in the most favorable modulation range, even in the event of strong supply voltage dips becomes.

Zum Schutz des Transistors 41 bzw. des Nadelhubsensors 21 vor Überlast ist eine Strombegrenzung der Stromquelle vorgesehen. Hierzu dienen die Zenerdiode 50 und/oder die Zenerdiode 51. Weiterhin besteht die Möglichkeit, den Pluseingang des Operationsverstärkers 44 mit einem drehzahlabhängigen Signal zu beaufschlagen, so daß der in dem Nadelhubsensor fließende Strom als Funktion der Drehzahl gesteuert wird.To protect the transistor 41 or the needle stroke sensor 21 from overload, a current limitation of the current source is provided. The Zener diode 50 and / or the Zener diode 51 are used for this purpose. There is also the possibility of applying a speed-dependent signal to the positive input of the operational amplifier 44, so that the current flowing in the needle stroke sensor is controlled as a function of the speed.

Es hat sich auch als zweckmäßig erwiesen, zwischen die Basis und dem Emitter des Transistors 41 eine Koppeleinrichtung 49 einzufügen, um die Basis mit der Versorgungsspannung überlagerten Störimpulsen zu beaufschlagen. Dies hat zur Folge, daß Störimpulse nicht am Kollektor des Transistors 41 auftreten und eine sichere Nutzsignalauswertung gewährleistet ist.It has also proven expedient to insert a coupling device 49 between the base and the emitter of the transistor 41 in order to apply interference pulses superimposed on the supply voltage to the base. The result of this is that interference pulses do not occur at the collector of transistor 41 and reliable useful signal evaluation is ensured.

In Figur 4 sind einige Ausführungsbeispiele dieser Koppeleinrichtung 49 wiedergegeben. Im einfachsten Fall 4a besteht diese Koppeleinrichtung aus einem Kondensator, der wegen der Niederohmigkeit der Basis recht groß dimensioniert sein sollte und somit zweckmäßigerweise als Elektrolytkondensator ausgebildet ist.FIG. 4 shows some exemplary embodiments of this coupling device 49. In the simplest case 4a, this coupling device consists of a capacitor which should be quite large due to the low impedance of the base and which is therefore expediently designed as an electrolytic capacitor.

In einer anderen Ausführungsform der Koppeleinrichtung 4b wird ein als Impedanzwandler betriebener Operationsverstärker mit einem dem Ausgang nachgeschalteten Kondensator verwendet. Es kann in verschiedenen Anwendungsfällen günstig sein, wegen der hohen Zuverlässigkeit von Operationsverstärkern diese den Elektrolytkondensatoren vorzuziehen.In another embodiment of the coupling device 4b, an operational amplifier operated as an impedance converter with a capacitor connected downstream of the output is used. In various applications, it can be advantageous to choose operational amplifiers over electrolytic capacitors because of the high reliability of operational amplifiers.

Ist der Transistor 41 gemäß Figur 4c als Feldeffekttransistor ausgebildet, so können wegen der Hochohmigkeit des Gates sehr klein dimensionierte, störsichere und kostengünstige Kondensatoren zur Kopplung benutzt werden.If the transistor 41 is designed as a field effect transistor in accordance with FIG. 4c, because of the high impedance of the gate, very small, interference-free and inexpensive capacitors can be used for coupling.

Mit Hilfe der erfindungsgemäßen Meßeinrichtung zur Erfassung des Einspritzzeitpunktes wird eine erhebliche Verbesserung des Nutzsignal zu Störsignal-Verhältnisses erreicht. Selbst in extremen, im Kraftfahrzeugbetrieb jedoch unvermeidbaren Situationen bleibt die Meßeinrichtung funktionstüchtig. Vorteilhaft erweist sich auch die drehzahlabhängige Steuerung der Stromquelle, mit der es möglich ist, über den gesamten Drehzahlbereich der Brennkraftmaschine ein Spritzbeginnsignal mit einer drehzahlunabhängigen Amplitude zu erzeugen. Im Falle einer geregelten Wechselspannungsstabilisierung des analogen Nutzsignals läßt sich der Einfluß weiterer Parameter, wie Temperatur, Geberstreuung usw. auf die Signalamplitude ausschalten, so daß eine Digitalisierung des Nutzsignals bei gleichbleibender Genauigkeit (kein Zeitfehler durch verschiedene Signalamplituden bei konstanter Triggerschwelle der Monoflops) erheblich vereinfacht wird.With the aid of the measuring device according to the invention for detecting the injection time, a considerable improvement in the useful signal to interference signal ratio is achieved. The measuring device remains functional even in extreme but unavoidable situations in motor vehicle operation. The speed-dependent control of the current source also proves to be advantageous, with which it is possible to generate an injection start signal with a speed-independent amplitude over the entire speed range of the internal combustion engine. In the case of regulated AC voltage stabilization of the analog useful signal, the influence of further parameters, such as temperature, sensor spread, etc. on the signal amplitude can be switched off, so that digitizing the useful signal with constant accuracy (no time error due to different signal amplitudes with constant trigger threshold of the monoflops) is considerably simplified .

Claims (7)

1. Measurement apparatus for continuously determining operating parameters of a combustion engine, with a sensor (21), which is driven by a current source (30) connected to supply voltage (UB) and which emits output signals (UA) which indicate changes of an operating parameter, characterized in that the current source contains a series circuit of a transistor (41) and a resistor (40) which is connected between the supply voltage (UB) and earth via the sensor, that the output signal (UA) of the sensor (21) is connected via a low-pass filter (42, 43) to the first input of an operational amplifier (44) of a comparator circuit, the second input of which is supplied with a supply-voltage- dependent reference voltage via a voltage divider (45, 46) and the output of which is connected to the base of the transistor (41) which, in turn, is connected to the supply voltage (Us) via a coupling device (49).
2. Measurement apparatus according to Claim 1, characterized in that the positive input of the operational amplifier (44) of the current source (30) is supplied via the series circuit of a resistor (52) and a diode (53) with a speed-dependent and/ or temperature-dependent signal and/or a signal dependent on production tolerances of the measurement value sensor (21), which influences the output current of the current source in such a manner that the signal amplitude which can be picked up across the sensor (21) is stabilized.
3. Measurement apparatus according to Claim 1, characterized in that the coupling device (49) consists of a capacitor, preferably an electrolytic capacitor.
4. Measurement apparatus according to Claim 1, characterized in that the coupling device consists of a series circuit of an operational amplifier, operated as impedance converter, and a capacitor.
5. Measurement apparatus according to Claim 1, characterized in that the coupling device, in the case where a field-effect transistor is used as transistor (41), consists of a capacitor of relatively small capacitance and is connected between the connections (S) and (G) of the field-effect transistor (Figure 4c).
6. Measurement apparatus according to Claim 1, characterized in that the measurement apparatus contains a threshold switch (32) the switching threshold of which can be adjusted in dependence on speed.
7. Measurement apparatus according to one of the preceding claims, characterized in that, for the purpose of current limiting, Zener diodes (50, 51) are used which, on the one hand, are connected in parallel with the coupling device (49) and, on the other hand, are connected between the negative input of the operational amplifier (44) and earth.
EP83110244A 1982-11-16 1983-10-14 Measurement apparatus for continuously determining operating parameters of a combustion engine Expired EP0119297B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19823242317 DE3242317A1 (en) 1982-11-16 1982-11-16 MEASURING DEVICE ON AN INTERNAL COMBUSTION ENGINE FOR THE CONTINUOUS DETECTION OF OPERATING PARAMETERS
DE3242317 1982-11-16

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EP0119297A2 EP0119297A2 (en) 1984-09-26
EP0119297A3 EP0119297A3 (en) 1986-08-13
EP0119297B1 true EP0119297B1 (en) 1989-05-03

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EP (1) EP0119297B1 (en)
JP (1) JPS59101000A (en)
DE (2) DE3242317A1 (en)

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US4687994A (en) * 1984-07-23 1987-08-18 George D. Wolff Position sensor for a fuel injection element in an internal combustion engine
DE3508335A1 (en) * 1985-03-08 1986-09-11 Voest-Alpine Friedmann GmbH, Linz CIRCUIT ARRANGEMENT FOR DETECTING THE CURRENT CHANGE SIGNALS OF A NEEDLE LIFT SENSOR THROUGH A CONSTANT DC VOLTAGE OF AN INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE3517509C2 (en) * 1985-05-15 1997-08-07 Bosch Gmbh Robert Measuring device on a motor vehicle for recording operating parameters
DE3523535A1 (en) * 1985-07-02 1987-01-15 Bosch Gmbh Robert CONTROL ARRANGEMENT FOR AN INTERNAL COMBUSTION ENGINE
DE3605995C2 (en) * 1986-02-25 1996-11-14 Teves Gmbh Alfred Device for measuring the angular velocity of a rotating body
DE19544845C1 (en) * 1995-12-01 1997-05-28 Daimler Benz Ag Method and device for checking the wiring of solenoid-operated injection valves
US7861578B2 (en) * 2008-07-29 2011-01-04 General Electric Company Methods and systems for estimating operating parameters of an engine
DE102011082455B4 (en) * 2011-09-09 2014-02-13 Continental Automotive Gmbh Method for monitoring an injection quantity of a fluid and injection system for injecting an injection quantity of a fluid
GB2554916B (en) * 2016-10-14 2020-01-29 Delphi Automotive Systems Lux Method and apparatus to detect impedance of contact between injector valve moving parts

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US3011486A (en) * 1956-09-24 1961-12-05 Bendix Corp Fuel injection system for internal combustion engines
DE2449836A1 (en) * 1974-10-19 1976-04-29 Bosch Gmbh Robert DEVICE FOR REGULATING THE OPERATING BEHAVIOR OF AN COMBUSTION ENGINE
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DE3242317A1 (en) 1984-05-17
DE3379797D1 (en) 1989-06-08
EP0119297A2 (en) 1984-09-26
EP0119297A3 (en) 1986-08-13
US4541271A (en) 1985-09-17
JPS59101000A (en) 1984-06-11

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