EP0197315B1 - Device for modifying the operating parameters in an internal-combustion engine - Google Patents

Device for modifying the operating parameters in an internal-combustion engine Download PDF

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Publication number
EP0197315B1
EP0197315B1 EP86103080A EP86103080A EP0197315B1 EP 0197315 B1 EP0197315 B1 EP 0197315B1 EP 86103080 A EP86103080 A EP 86103080A EP 86103080 A EP86103080 A EP 86103080A EP 0197315 B1 EP0197315 B1 EP 0197315B1
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EP
European Patent Office
Prior art keywords
load
combustion engine
internal combustion
sensor
control unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP86103080A
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German (de)
French (fr)
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EP0197315A2 (en
EP0197315A3 (en
Inventor
Hans-Ernst Dipl.-Ing. Beyer
Jörg Dipl.-Ing. Bonitz
Robert Dipl.-Ing. Entenmann
Siegmar Dip.-Ing. Förster
Rochus Knab
Walter Dr. Dipl.-Phys. Künzel
Wolfgang Kugler
Alfred Dr. Mahlberg
Bernhard Miller
Matthias Dipl.-Ing. Philipp
Siegfried Dr. Rohde
Stefan Dipl.-Ing. Unland
Walter Dipl.-Ing. Viess
Herbert Dipl.-Ing. Winter
Jürgen Dr. Dipl.-Phys. Zimmermann
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP0197315A2 publication Critical patent/EP0197315A2/en
Publication of EP0197315A3 publication Critical patent/EP0197315A3/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P5/00—Advancing or retarding ignition; Control therefor
    • F02P5/04—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions
    • F02P5/045—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions combined with electronic control of other engine functions, e.g. fuel injection
    • 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
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
    • F02D41/266—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor the computer being backed-up or assisted by another circuit, e.g. analogue
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P15/00—Electric spark ignition having characteristics not provided for in, or of interest apart from, groups F02P1/00 - F02P13/00 and combined with layout of ignition circuits
    • F02P15/008—Reserve ignition systems; Redundancy of some ignition devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B1/00—Engines characterised by fuel-air mixture compression
    • F02B1/02—Engines characterised by fuel-air mixture compression with positive ignition
    • F02B1/04—Engines characterised by fuel-air mixture compression with positive ignition with fuel-air mixture admission into cylinder

Definitions

  • the invention relates to a device for a spark ignition internal combustion engine according to the preamble of the main claim.
  • Devices of this type are already being used in series by various motor vehicle manufacturers to influence the operating parameters of different types of internal combustion engines. These vehicles include the Volvo B200E (Europe), the Audi 200 Turbo and the VW Rabbit GTI, both of which are exported to the USA.
  • Volvo B200E European
  • Audi 200 Turbo the Audi 200 Turbo
  • VW Rabbit GTI both of which are exported to the USA.
  • the two control units work largely independently of one another, so to speak, they can also be used individually as independent components, so when the two control units are used together, the fact exists that two different sensors are used for one and the same control unit input information.
  • the control unit since it is essentially responsible for the ignition, to use a pressure sensor mounted in the intake pipe of the internal combustion engine as the load signal sensor.
  • a pressure sensor can of course also be used as the load sensor for the second control device which essentially influences the fuel-air mixture supplied to the internal combustion engine, but it has proven to be advantageous to record the amount of air sucked in by the internal combustion engine as load information.
  • a known air volume meter which is designed as a flap in the intake manifold of the internal combustion engine, or a hot wire air mass meter is used.
  • load detection for example detection of the throttle valve position or the like, are also conceivable.
  • a control unit with two microprocessors is already known from SAE paper 83 0422, EFI for the 80's ⁇ A Base Model Fuel Control System, one microprocessor calculating injection pulses, while the other microprocessor performs other functions, for example operating the gasoline pump.
  • these microprocessors are connected to one another via a data line, and operating parameters can also be exchanged via this data line.
  • the device according to the invention with the characterizing features of the main claim allows a considerably cheaper manufacture of control units.
  • the measure according to the invention makes it possible to produce and operate two independent control devices and still reduce the number of sensors. This reduces sources of error due to sensor failures.
  • the load information is processed by the second control device as a relative value. This largely mitigates the spread of specimens of the load sensor.
  • the output signals of the load sensor are subjected to a corrective influence which is based on a comparison of the setpoint and actual value load characteristics of the load sensor. This ensures excellent stability of the sensor system in relation to time.
  • an internal combustion engine shown symbolically is identified by reference number 10.
  • the air necessary for the combustion of the fuel enters the internal combustion engine 10 through an intake pipe 11.
  • a sensor 12 for detecting the amount of air sucked in by the internal combustion engine is installed in the intake pipe 11, a throttle valve 13 with a throttle valve switch 14 downstream of the sensor 12 and a sensor 15 for detecting the pressure present in the intake pipe 11 downstream of the throttle valve 13.
  • An exhaust gas duct 16 is provided on the output side of the internal combustion engine 10 for the outlet of the exhaust gases of the internal combustion engine 10.
  • a first control unit 17 is used to influence the fuel-air mixture and, in the present exemplary embodiment, supplies signals for actuating injection valves 18a and thereby influences the amount of fuel injected into the working cylinders of the internal combustion engine.
  • the invention is not limited to a single-cylinder injection system, as shown in the exemplary embodiment in FIG. 1. Based on the present disclosure of the inventive concept, it can equally well be transferred to systems with intake manifold injection or with continuous single-cylinder injection (in contrast to intermittent single-cylinder injection) without inventive step.
  • the first control device 17 receives various input information, namely information 19 regarding the battery voltage, information 20 regarding the speed, information 21 regarding the load, which in the present exemplary embodiment is derived from the sensor 12, information 22 regarding the intake air temperature, information 23 regarding the throttle valve position of the throttle valve 13, which are derived from the throttle valve position sensor 14, are supplied with information 24 relating to the engine temperature and further unspecified information 26.
  • information 19 regarding the battery voltage information 20 regarding the speed
  • information 21 regarding the load which in the present exemplary embodiment is derived from the sensor 12
  • information 22 regarding the intake air temperature information 22 regarding the intake air temperature
  • information 23 regarding the throttle valve position of the throttle valve 13 which are derived from the throttle valve position sensor 14
  • further output variables 27 are provided with which the fuel-air ratio is to be influenced.
  • these output variables can be used to control the speed via a controllable air bypass (not shown in the drawing) or to control an exhaust gas recirculation system.
  • a controllable air bypass not shown in the drawing
  • the second control unit 18 essentially provides output signals for actuating the ignition units 29 of the internal combustion engine as a function of the input information speed or degrees crankshaft angle 20, the battery voltage 19 and other input variables 30 not specified in more detail, the information about the fuel metering or about the boost pressure of an in include the charger, not shown, or about the tendency of the internal combustion engine to knock. Other output variables can be used to regulate the boost pressure or other operating parameters of the internal combustion engine or for knock control.
  • FIG. 1 a shows the state of the art from which sensors the two control units obtain their load information. While the first control device 17 obtains its load information from the sensor 12 for the intake air quantity, the load information for the second control device 18 is derived from the pressure sensor 15 for measuring the intake pressure in the intake pipe 11 of the internal combustion engine 10.
  • FIG. 1b shows part of the improvement of the present invention over the prior art, namely since the load information for the second control device 18 is also derived from the sensor 12 for measuring the amount of air drawn in by the internal combustion engine 10.
  • the pressure sensor 15 is saved and thus a more economical production and greater interference immunity of the combination of the two control devices is ensured.
  • the invention does not consist exclusively in replacing the load sensor for the second control unit 18, but also in achieving an adaptation, in particular in terms of hardware, of this second control unit 18 to the changed characteristics of the load input information of the sensor 12.
  • the following criteria are in the foreground for an adaptation: Due to the changed load input information, no far-reaching changes in the hardware structure of the second control device 18 should be carried out. Rather, the adaptation should essentially be implemented through software changes.
  • the accuracy of response of the second control unit 18 to the new load information should at least not deteriorate compared to the version according to the prior art and it should be largely independent of production variations of the sensor 12.
  • the block circuit structure of the two control devices 17, 18 is shown schematically. Since the interior of the first control device 17 is of no interest in the determination of the fuel-air mixture in the present case, it is represented by a block 40 (black box). The input information already mentioned, in particular information 19 relating to the battery voltage and information 21 relating to the load, are fed to this block 40. All other input information should be disregarded for the following consideration.
  • the block 40 controls output stages 41, which in turn are connected to the injection valves 18a. Further output stages 42 for actuating further actuators 43 are provided.
  • a load signal is taken from the sensor 12 for detecting the amount of air sucked in; which is available at the center tap of a potentiometer coupled to the moving part of the air flow meter.
  • This potentiometer of the sensor 12 is in series with a protective resistor R1, which in turn is connected to a reference voltage source U1, which is fed by the battery voltage UB.
  • the voltage applied to the center tap of the potentiometer of the sensor 12 is thus a measure of the deflection of the movable part of the air flow meter and thus contains information about the load. If sensors are used to detect the intake air quantity of the internal combustion engine, which are based on another measuring principle, for example on the hot wire principle or the vortex principle, then these are processed further as equivalent load information.
  • the structure of the second control device 18 is shown in somewhat more detail in FIG.
  • the input variables 19, 21 and further input variables 30, for example for knock control, are converted into digital variables in an analog-digital converter 45.
  • the information 20 about the speed and the crankshaft angle degrees, which is already largely digital due to the sensor characteristic, is fed to a pulse shaper 46, which essentially normalizes the pulse shape of the input pulses. All signals in digital form are fed to an input unit 47, which is connected to an output unit 49 via an input / output unit 48.
  • These units 47, 48, 49 form the periphery of a digital signal processing unit, which is constructed from the central unit 50, read-only memories 51, operating data memories 52, a bus 53, all of which are connected to one another in terms of data.
  • the read-only memory 51 In the read-only memory 51, all programs and all characteristic data, characteristic curve setpoints, etc. are stored in a captive manner, while the data supplied by the sensors are stored in the read / write memory 52 until they are called up by the microprocessor or replaced by more current data. In the central processing unit 50, the arithmetic and logical operations are carried out with the data fed in.
  • the output unit 49 In turn controls various output stages 54, 55, which are used for ignition 56 or to control other actuators 57, for example to control the boost pressure.
  • the output signal of the sensor 12 for detecting the amount of intake air is also supplied to the second control unit as load information 21. Since the second control device 18 has a reference voltage source U2 that is independent of the reference voltage source U1 of the first control device 17, care must be taken because of the tolerance in the output voltage of these reference voltage sources that the input signal for the second control device 18 in no case assumes values that exceed the current value of the reference voltage source U2. For this reason, a voltage divider circuit consisting of resistors R2 and R3 is provided, which divides the output voltage of the load sensor down by a certain proportion.
  • a second signal path 58 is provided, which supplies the voltage applied to the total resistance of the potentiometer of the sensor 12 to the second control device 18.
  • a further voltage divider circuit consisting of the resistors R2 ', R3' is provided.
  • these two pieces of information 21, 58 are essentially divided by one another, so that a measurement variable which is independent of the absolute value of the total resistance of the potentiometer of the sensor 12 is available as load information.
  • both control units now calculate output variables for controlling the actuators.
  • characteristic maps are provided in particular for the second control device 18 of interest, in which, for example, the ignition timing is stored in degrees crankshaft angle as a function of the load and speed in the read-only memory means 51, 52.
  • FIG. 3a An example of such a map is shown in FIG. 3a, in which the map values are stored as a function of the speed and the output signals of a pressure sensor as a load sensor.
  • the map values are stored as a function of the speed and the output signals of a pressure sensor as a load sensor.
  • eight load ranges L1 to L8 and eight speed ranges can be distinguished in the present case, so that a total of 64 map values are stored.
  • the load signals for map control are now derived from an air quantity sensor, in particular an air flap sensor, instead of a pressure sensor, the map takes on the form shown in FIG. 3b due to the completely different output signal characteristics of the air volume sensor.
  • this figure clarifies that a load range, for example load range L1, can no longer be described by a fixed output voltage value over the entire speed range, but that the voltage values per load range assume a wide, speed-dependent bandwidth.
  • the output signal characteristic of the air flow sensor is designed in such a way that the output values of the air flow sensor in the various speed ranges do not even cover the full maximum possible range of the possible output values accept. It follows from this that in order to achieve the same resolution as is possible with a pressure sensor as a load sensor, a much larger memory is required for storing the map values.
  • the output signals of the sensor 12 in the second control unit are influenced by computing functions according to the invention, so that the output characteristic of the sensor 12 can be changed .
  • the method for changing the output signal characteristic of the air quantity sensor is explained in more detail below with reference to FIG. 3b.
  • the possible range of values for the output values of the air flow sensor in the individual speed ranges is applied with individual, in particular speed-dependent, additive variables C1 (n1), ..., C1 (n8), ... such that, for example, the lowest values of all value ranges have a common, identical value accept.
  • This can be, for example, the zero line in the coordinate system shown, or it can also be another basic variable that appears to be advantageous.
  • the individual possible values of each speed-dependent value range are acted upon by a speed-dependent multiplicative variable C2 (n1), ..., C2 (n8), ... in order to adapt the speed-dependent value ranges to one another.
  • the multiplicative constant C2 can also assume a value that is constant for all speed ranges, in particular if the variation of the individual speed-dependent value ranges of the output signals of the air quantity sensor is essentially the same or has negligible differences from one another. This additive and / or multiplicative change in the output signals of the air flow sensor ensures that the value set in the individual speed ranges becomes essentially identical.
  • a match between setpoint and actual value can be achieved by adding a correction element AC1 to the quantities for additive influencing C1 (n).
  • the full-load characteristic curve can in particular be stored as the setpoint characteristic curve, the position of the throttle valve 13 being monitored by the throttle valve position sensor 14 in order to detect the full-load case. If the throttle valve is fully open, there is a full load and the described target / actual value comparison can be carried out. In a first approximation, this correction can be valid for the entire speed range, i.e. that all additive C1 (n) are modified with one and the same correction value AC1.
  • the correction value ⁇ C1 / 2 (n) is determined in such a way that the difference between the setpoint and actual value of the load characteristic is eliminated.
  • the invention allows an air quantity sensor to be used instead of an additional pressure sensor for load detection without having to sacrifice accuracy and long-term stability.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einer Vorrichtung für eine fremdgezündete Brennkraftmaschine nach der Gattung des Hauptanspruchs. Derartige Vorrichtungen werden bereits von verschiedenen Kraftfahrzeugherstellern zur Beeinflussung von Betriebsparametern verschiedener Brennkraftmaschinentypen in Serie eingesetzt. Zu diesen Kraftfahrzeugen gehören unter anderem der Volvo B200E (Europa) sowie der Audi 200 Turbo und der VW Rabbit GTI, die beide nach USA exportiert werden. Durch die Verwendung von zwei Steuergeräten, von denen das eine wenigstens für die Beeinflussung des der Brennkraftmaschine zugeführten Kraftstoff-Luft-Gemisches und das andere für die Beeinflussung der Zündung der Brennkraftmaschine verantwortlich ist, wird eine hohe Flexibilität dadurch erreicht, daß jedes der beiden Steuergeräte individuell an verschiedene Anforderungen der Kraftfahrzeughersteller angepaßte werden kann. Da die beiden Steuergeräte weitgehend unabhängig voneinander arbeiten, sozusagen als eigenständige Komponenten auch einzeln eingesetzt werden können, liegt beim gemeinsamen Einsatz der beiden Steuergeräte der Sachverhalt vor, daß für ein und dieselbe Steuergeräteeingangsinformation zwei verschiedene Sensoren eingesetzt werden. So ist es beispielsweise üblich, für das Steuergerät, da im wesentlichen für die Zündung zuständig ist, als Lastsignalsensor einen im Ansaugrohr der Brennkraftmaschine angebrachten Drucksensor zu verwenden. Für das, im wesentlichen das der Brennkraftmaschine zugeführte Kraftstoff-Luft-Gemisch beeinflussende zweite Steurgerät kann als Lastsensor natürlich auch ein Drucksensor eingesetzt werden, es hat sich jedoch als vorteilhaft erwiesen, als Lastinformation die von der Brennkraftmaschine angesaugte Luftmenge zu erfassen. Hierzu wird beispielsweise ein an sich bekannter Luftmengenmesser, der als Klappe im Saugrohr der Brennkraftmaschine ausgebildet ist oder ein Hitzdraht-Luftmassenmesser verwendet. Natürlich sind auch andere Arten der Lasterfassung, beispielsweise eine Erfassung der Drosselklappenstellung oder ähnliches denkbar.The invention relates to a device for a spark ignition internal combustion engine according to the preamble of the main claim. Devices of this type are already being used in series by various motor vehicle manufacturers to influence the operating parameters of different types of internal combustion engines. These vehicles include the Volvo B200E (Europe), the Audi 200 Turbo and the VW Rabbit GTI, both of which are exported to the USA. Through the use of two control devices, one of which is responsible at least for influencing the fuel-air mixture supplied to the internal combustion engine and the other for influencing the ignition of the internal combustion engine, a high degree of flexibility is achieved in that each of the two control devices is individual can be adapted to various requirements of the motor vehicle manufacturers. Since the two control units work largely independently of one another, so to speak, they can also be used individually as independent components, so when the two control units are used together, the fact exists that two different sensors are used for one and the same control unit input information. For example, it is customary for the control unit, since it is essentially responsible for the ignition, to use a pressure sensor mounted in the intake pipe of the internal combustion engine as the load signal sensor. A pressure sensor can of course also be used as the load sensor for the second control device which essentially influences the fuel-air mixture supplied to the internal combustion engine, but it has proven to be advantageous to record the amount of air sucked in by the internal combustion engine as load information. For this purpose, for example, a known air volume meter, which is designed as a flap in the intake manifold of the internal combustion engine, or a hot wire air mass meter is used. Of course, other types of load detection, for example detection of the throttle valve position or the like, are also conceivable.

Es besteht nun das Bestreben, anstelle von zwei verschiedenen Lastsensoren nur einen einzigen Lastsensor für beide Steuergeräte einzusetzen, um eine noch wirtschaftlichere Fertigung dieser Systeme zu gewährleisten. Allerdings sollen dadurch keine oder nur minimale, insbesondere hardwaremäßige Änderungen im Aufbau der Steuergeräte durchgeführt werden, da beide Steuergeräte an sich eigenständige Komponenten bleiben und zur wirtschaftlichen Fertigung auch weitgehend gleiche Bauteile unabhängig vom speziellen Einsatz aufweisen sollen.There is now an effort to use only one load sensor for both control units instead of two different load sensors in order to ensure an even more economical production of these systems. However, no or only minimal, in particular hardware, changes are to be made in the structure of the control units, since both control units themselves remain independent components and, for economical production, should also have largely the same components regardless of the specific application.

Aus dem SAE-Paper 83 0422, EFI for the 80's―A Base Model Fuel Control System ist bereits ein Steuergerät mit zwei Mikroprozessoren bekannt, wobei der eine Mikroprozessor Einspritzimpulse berechnet, während der andere Mikroprozessor weitere Funktionen wahrnimmt, beispielsweise die Benzinpumpe betreibt. Um beide Mikroprozessoren betreiben zu können, stehen diese Mikroprozessoren über eine Datenleitung miteinander in Verbindung, wobei über diese Datenleitung, auch Betriebsparameter ausgetauscht werden können.A control unit with two microprocessors is already known from SAE paper 83 0422, EFI for the 80's ― A Base Model Fuel Control System, one microprocessor calculating injection pulses, while the other microprocessor performs other functions, for example operating the gasoline pump. In order to be able to operate both microprocessors, these microprocessors are connected to one another via a data line, and operating parameters can also be exchanged via this data line.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Vorrichtung mit den kennzeichnenden Merkmalen des Hauptanspruchs läßt eine erheblich preisgünstigere Fertigung von Steuergeräten erreichen. Durch die erfindungsgemäße Maßnahme ist es nämlich möglich, zwei unabhängige Steuergeräte herzustellen und zu betreiben und trotzdem die Zahl der Sensoren zu reduzieren. Dadurch werden Fehlerquellen aufgrund von Ausfällen von Sensoren reduziert. Eine wesentlichen Ausgestaltung der Erfindung ist auch, daß die Lastinformation vom zweiten Steuergerät als Reiativwert verarbeitet wird. Hierdurch werden Exemplarstreuungen des Lastsensors weitgehend entschärft.The device according to the invention with the characterizing features of the main claim allows a considerably cheaper manufacture of control units. The measure according to the invention makes it possible to produce and operate two independent control devices and still reduce the number of sensors. This reduces sources of error due to sensor failures. It is also an essential embodiment of the invention that the load information is processed by the second control device as a relative value. This largely mitigates the spread of specimens of the load sensor.

Als sehr vorteilhaft ist weiterhin anzusehen, daß die Ausgangssignale des Lastsensors mit additiven bzw. multiplikativen Größen beaufschlagt sind, die darüber hinaus noch eine Abhängigkeit von der Drehzahl der Brennkraftmaschine aufweisen können. Durch geeignete Festlegung dieser Größen, die in vorteilhafter Weise in Speichermitteln des Steuergerätes abgelegt sind, kann eine Anpassung des Wertevorrats der Ausgangssignale des Lastsensors an die Gegebenheiten der Steuergeräte erzielt werden unter Gewährleistung einer sehr hohen Verarbeitungsgenauigkeit bei einem minimalen schaltungstechnischen Aufwand.It is also to be regarded as very advantageous that additive or multiplicative quantities are applied to the output signals of the load sensor, which can also have a dependency on the speed of the internal combustion engine. By appropriately defining these variables, which are advantageously stored in memory means of the control unit, an adaptation of the value set of the output signals of the load sensor to the conditions of the control units can be achieved while ensuring a very high processing accuracy with minimal circuitry outlay.

Weiterhin ist sehr vorteilhaft, daß die Ausgangssignale des Lastsensors einer korrigierenden Beeinflussung unterworfen sind, die auf einem Vergleich der Soll- und Istwertlastkennlinien des Lastsensors beruht. Hierdurch wird eine hervorragende Stabilität des Sensorsystems bezogen auf die Zeit gewährleistet.It is also very advantageous that the output signals of the load sensor are subjected to a corrective influence which is based on a comparison of the setpoint and actual value load characteristics of the load sensor. This ensures excellent stability of the sensor system in relation to time.

Weitere Vorteile der Erfindung und zweckmäßige Ausgestaltungen ergeben sich in Verbindung mit den Unteransprüchen aus der nachfolgenden Beschreibung der Ausführungsbeispiele.Further advantages of the invention and expedient configurations result in connection with the subclaims from the following description of the exemplary embodiments.

Zeichnungdrawing

Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen:

  • Figur 1 eine schematische Darstellung einer Brennkraftmaschine mit zwei Steuergeräten und verschiedenen Signalgebern,
  • Figur 1a den bekannten Stand der Technik bezüglich der Lastsignalgewinnung für die beiden Steuergeräte,
  • Figur 1 b die erfindungsgemäße Vorrichtung zur Gewinnung der Lastinformation für die beiden Steuergeräte,
  • Figur 2 ein grobes Blockschaltbild der beiden Steuergeräten mit einer Signalanpassung für die Ausgangssignale des Lastsensors,
  • Figur 3a ein Drehzahllastkennfeld für beispielsweise den Zündzeitpunkt, wobei das Lastsignal entsprechend dem bekannten Stand der Technik von einem Drucksensor abgeleitet wird,
  • Figur 3b ein zu Figur 3a äquivalentes Kennfeld, wobei in diesem Fall die Lastinformation von einem Luftmengenmesser abgeleitet wird,
  • Figur 4 einen Ausschnitt der Figur 3b zur Erläuterung zur korrigierenden Beeinflussung der Ausgangssignale des Lastsensors.
Embodiments of the invention are shown in the drawing and explained in more detail in the following description. Show it:
  • FIG. 1 shows a schematic illustration of an internal combustion engine with two control devices and different signal transmitters,
  • FIG. 1 a shows the known prior art with regard to the generation of load signals for the two control units,
  • 1b shows the device according to the invention for obtaining the load information for the two control units,
  • FIG. 2 shows a rough block diagram of the two control devices with a signal adaptation for the output signals of the load sensor,
  • 3a shows a speed load map for, for example, the ignition timing, the load signal being derived from a pressure sensor in accordance with the known prior art,
  • FIG. 3b shows a map which is equivalent to FIG. 3a, in which case the load information is derived from an air flow meter,
  • Figure 4 shows a detail of Figure 3b to explain the corrective influence on the output signals of the load sensor.

Beschreibung der AusführungsbeispieleDescription of the embodiments

In Figur 1 isteine symbolisch dargestellte Brennkraftmaschine mit der Bezugsziffer 10 gekennzeichnet. Eingangsseitig tritt durch ein Ansaugrohr 11 die zur Verbrennung des Kraftstoffs notwendige Luft in die Brennkraftmaschine 10 ein. Im Ansaugrohr 11 ist ein Sensor 12 zur Erfassung der von der Brennkraftmaschine angesaugten Luftmenge, stromab vom Sensor 12 eine Drosselklappe 13 mit einem Drosselklappenschalter 14 sowie stromab von der Drosselklappe 13 ein Sensor 15 zur Erfassung des im Ansaugrohr 11 vorhandenen Drucks angebracht. Ausgangsseitig der Brennkraftmaschine 10 ist ein Abgaskanal 16 für den Auslaß der Abgase der Brennkraftmaschine 10 vorgesehen.In Figure 1, an internal combustion engine shown symbolically is identified by reference number 10. On the input side, the air necessary for the combustion of the fuel enters the internal combustion engine 10 through an intake pipe 11. A sensor 12 for detecting the amount of air sucked in by the internal combustion engine is installed in the intake pipe 11, a throttle valve 13 with a throttle valve switch 14 downstream of the sensor 12 and a sensor 15 for detecting the pressure present in the intake pipe 11 downstream of the throttle valve 13. An exhaust gas duct 16 is provided on the output side of the internal combustion engine 10 for the outlet of the exhaust gases of the internal combustion engine 10.

Ein erstes Steuergerät 17 dient zur Beeinflussung des Kraftstoff-Luft-Gemisches und liefert im vorliegenden Ausführungsbeispiel Signale zur Ansteuerung von Einspritzventilen 18a und beeinflußt dadurch die in die Arbeitszylinder der Brennkraftmaschine eingespritzte Kraftstoffmenge. Natürlich ist die Erfindung nicht auf eine Einzelzylindereinspritzanlage, wie sie im Ausführungsbeispiel der Figur 1 dargestellt ist, beschränkt. Sie läßt sich aufgrund der vorliegenden Offenbarung des Erfindungsgedankens ohne erfinderisches Zutun ebensogut auf Anlagen mit Saugrohreinspritzung oder mit kontinuierlicher Einzelzylindereinspritzung (im Gegensatz zur intermittierender Einzelzylindereinspritzung) übertragen.A first control unit 17 is used to influence the fuel-air mixture and, in the present exemplary embodiment, supplies signals for actuating injection valves 18a and thereby influences the amount of fuel injected into the working cylinders of the internal combustion engine. Of course, the invention is not limited to a single-cylinder injection system, as shown in the exemplary embodiment in FIG. 1. Based on the present disclosure of the inventive concept, it can equally well be transferred to systems with intake manifold injection or with continuous single-cylinder injection (in contrast to intermittent single-cylinder injection) without inventive step.

Dem ersten Steuergerät 17 werden verschiedene Eingangsinformationen, nämlich Informationen 19 bezüglich der Batteriespannung, Informationen 20 bezüglich der Drehzahl, Informationen 21 bezüglich der Last, die im vorliegenden Ausführungsbeispiel vom Sensor 12 abgeleitet werden, Informationen 22 bezüglich der Ansauglufttemperatur, Informationen 23 bezüglich der Drosselklappenstellung der Drosselklappe 13, die vom Drosselklappenstellungssensor 14 abgeleitet werden, Informationen 24 bezüglich der Motortemperatur und weitere nicht näher spezifizierte Informationen 26 zugeführt. Neben der Ausgabe der Einspritzzeiten für die Einspritzventile 18a sind weitere Ausgabegrößen 27 vorgesehen, mit denen das Kraftstoff-Luft-Verhältnis zu beeinflussen ist. Beispielsweise kann mittels dieser Ausgabegrößen eine Drehzahlregelung über einen in der Zeichnung nicht dargestellten steuerbaren Luftbypaß oder eine Steuerung einer Abgasrückführung durchgeführt werden. Der Einfachheit halber soll im weiteren jedoch nur auf die Steuerung der Kraftstoffzumessung eingegangen werden.The first control device 17 receives various input information, namely information 19 regarding the battery voltage, information 20 regarding the speed, information 21 regarding the load, which in the present exemplary embodiment is derived from the sensor 12, information 22 regarding the intake air temperature, information 23 regarding the throttle valve position of the throttle valve 13, which are derived from the throttle valve position sensor 14, are supplied with information 24 relating to the engine temperature and further unspecified information 26. In addition to the output of the injection times for the injection valves 18a, further output variables 27 are provided with which the fuel-air ratio is to be influenced. For example, these output variables can be used to control the speed via a controllable air bypass (not shown in the drawing) or to control an exhaust gas recirculation system. For the sake of simplicity, however, only the control of the fuel metering will be discussed below.

Das zweite Steuergerät 18 liefert im wesentlichen Ausgangssignale zur Ansteuerung der Zündungseinheiten 29 der Brennkraftmaschine in Abhängigkeit von der Eingangsinformation Drehzahl bzw. Grad Kurbelwellenwinkel 20, der Batteriespannung 19 und von anderen nicht näher spezifizierten Eingangsgrößen 30, die Informationen über die Kraftstoffzumessung oder über den Ladedruck eines in der Zeichnung nicht dargestellten Laders oder über die Klopfneigung der Brennkraftmaschine beinhalten. Weitere Ausgabegrößen können zur Regelung des Ladedrucks oder anderer Betriebsparameter der Brennkraftmaschine oder für eine Klopfregelung dienen.The second control unit 18 essentially provides output signals for actuating the ignition units 29 of the internal combustion engine as a function of the input information speed or degrees crankshaft angle 20, the battery voltage 19 and other input variables 30 not specified in more detail, the information about the fuel metering or about the boost pressure of an in include the charger, not shown, or about the tendency of the internal combustion engine to knock. Other output variables can be used to regulate the boost pressure or other operating parameters of the internal combustion engine or for knock control.

In Figur 1 a ist als Stand der Technik dargestellt, von welchen Sensoren die beiden Steuergeräte ihre Lastinformation beziehen. Während das erste Steuergerät 17 seine Lastinformation vom Sensor 12 für die angesaugte Luftmenge bezieht, wird die Lastinformation für das zweite Steuergerät 18 vom Drucksensor 15 zur Messung des Ansaugdrucks im Ansaugrohr 11 der Brennkraftmaschine 10 abgeleitet.FIG. 1 a shows the state of the art from which sensors the two control units obtain their load information. While the first control device 17 obtains its load information from the sensor 12 for the intake air quantity, the load information for the second control device 18 is derived from the pressure sensor 15 for measuring the intake pressure in the intake pipe 11 of the internal combustion engine 10.

In Figur 1b ist ein Teil der Verbesserung der vorliegenden Erfindung gegenüber dem Stand der Technik dargestellt, nämlich da die Lastinformation für das zweite Steuergerät 18 ebenfalls vom Sensor 12 zur Messung der von der Brennkraftmaschine 10 angesaugten Luftmenge abgeleitetwird. Hierdurch wird, wie symbolisch in der Figur 1 b dargestellt ist, der Drucksensor 15 eingespart und damit eine wirtschaftlichere Fertigung und größere Störsicherheit der Kombination der beiden Steuergeräte gewährleistet. Allerdings besteht die Erfindung nicht ausschließlich in einem Austausch des Lastsensors für das zweite Steuergerät 18, sondern auch darin, eine insbesondere hardwaremäßig unaufwendige Anpassung dieses zweiten Steuergerätes 18 an die geänderte Charakteristik der Lasteingangsinformation des Sensors 12 zu erzielen. Für eine Anpassung stehen folgende Kriterien im Vordergrund: Aufgrund der geänderten Lasteingangsinformation sollen keine weitgreifenden Änderungen im hardwaremäßigem Aufbau des zweiten Steuergerätes 18 durchgeführt werden. Die Anpassung soll vielmehr im wesentlichen durch softwaremäßige Änderungen realisiert werden. Die Ansprechgenauigkeit des zweiten Steuergerätes 18 auf die neue Lastinformation soll sich gegenüber der Version gemäß dem Stand der Technik wenigstens nicht verschlechtern und es soll eine weitgehende Unabhängigkeitvon Fertigungsstreuungen des Sensors 12 gewährleistet sein.FIG. 1b shows part of the improvement of the present invention over the prior art, namely since the load information for the second control device 18 is also derived from the sensor 12 for measuring the amount of air drawn in by the internal combustion engine 10. As a result, as is symbolically represented in FIG. 1b, the pressure sensor 15 is saved and thus a more economical production and greater interference immunity of the combination of the two control devices is ensured. However, the invention does not consist exclusively in replacing the load sensor for the second control unit 18, but also in achieving an adaptation, in particular in terms of hardware, of this second control unit 18 to the changed characteristics of the load input information of the sensor 12. The following criteria are in the foreground for an adaptation: Due to the changed load input information, no far-reaching changes in the hardware structure of the second control device 18 should be carried out. Rather, the adaptation should essentially be implemented through software changes. The accuracy of response of the second control unit 18 to the new load information should at least not deteriorate compared to the version according to the prior art and it should be largely independent of production variations of the sensor 12.

In Figur 2 ist der blockschaltmäßige Aufbau der beiden Steuergeräte 17, 18 schematisch dargestellt. Da das Innenleben des ersten Steuergerätes 17 für die Bestimmung des Kraftstoff-Luft-Gemisches im vorliegenden Fall nicht näher interessiert, ist es durch einen Block 40 (black box) dargestellt. Diesem Block 40 werden die schon erwähnten Eingangsinformationen, insbesondere Informationen 19 bezüglich der Batteriespannung und Informationen 21 bezüglich der Last zugeführt. Alle weiteren Eingangsinformationen sollen für die folgende Betrachtung außer Acht bleiben. Ausgangsseitig steuert der Block 40 Endstufen 41 an, die ihrerseits an die Einspritzventile 18a angeschlossen sind. Weitere Endstufen 42 zur Betätigung weiterer Stellglieder 43 sind vorgesehen.In Figure 2, the block circuit structure of the two control devices 17, 18 is shown schematically. Since the interior of the first control device 17 is of no interest in the determination of the fuel-air mixture in the present case, it is represented by a block 40 (black box). The input information already mentioned, in particular information 19 relating to the battery voltage and information 21 relating to the load, are fed to this block 40. All other input information should be disregarded for the following consideration. On the output side, the block 40 controls output stages 41, which in turn are connected to the injection valves 18a. Further output stages 42 for actuating further actuators 43 are provided.

Vom Sensor 12 zur Erfassung der angesaugten Luftmenge wird ein Lastsignal abgenommen; das am Mittelabgriff eines mit dem beweglichen Teil des Luftmengenmessers gekoppelten Potentiometers zur Verfügung steht. Dieses Potentiometer des Sensors 12 liegt in Serie mit einem Schutzweiderstand R1, der seinerseits an eine Referenzspannungsquelle U1, die von der Batteriespannung UB gespeist wird, angeschlossen ist. Die am Mittelabgriff des Potentiometers des Sensors 12 anliegende Spannung ist somit ein Maß für die Auslenkung des beweglichen Teils des Luftmengenmessers und beinhaltet somit eine Information über die Last. Sollten Sensoren zur Erfassung der angesaugten Luftmenge der Brennkraftmaschine eingesetzt werden, die auf einem anderen Meßprinzip beispielsweise auf dem Hitzdrahtprinzip oder dem Vortexprinzip basieren, so werden diese als äquivalente Lastinformationen weiterverarbeitet.A load signal is taken from the sensor 12 for detecting the amount of air sucked in; which is available at the center tap of a potentiometer coupled to the moving part of the air flow meter. This potentiometer of the sensor 12 is in series with a protective resistor R1, which in turn is connected to a reference voltage source U1, which is fed by the battery voltage UB. The voltage applied to the center tap of the potentiometer of the sensor 12 is thus a measure of the deflection of the movable part of the air flow meter and thus contains information about the load. If sensors are used to detect the intake air quantity of the internal combustion engine, which are based on another measuring principle, for example on the hot wire principle or the vortex principle, then these are processed further as equivalent load information.

Der Aufbau des zweiten Steuergerätes 18 ist in Figur 2 etwas detaillierter dargestellt. Die Eingangsgrößen 19, 21 und weitere Eingangsgrößen 30 beispielsweise für eine Klopfregelung werden in einem Analog-Digital-Wandler 45 in digitale Größen umgesetzt. Die aufgrund der Gebercharakteristik schon weitgehend digital vorliegende Informationen 20 über die Drehzahl und die Kurbelwellenwinkelgrade werden einem Impulsformer 46 zugeführt, der die Pulsform der Eingangspulse im wesentlichen normiert. Alle in digitaler Form vorliegenden Signale werden einer Eingabeeinheit 47 zugeführt, die über eine Ein/Ausgabe-Einheit 48 mit einer Ausgabeeinheit 49 in Verbindung steht. Diese Einheiten 47, 48, 49 bilden die Peripherie einer digitalen Signalverarbeitungseinheit, die aus der Zentraleinheit 50, Festwertspeichern 51, Betriebsdatenspeichern 52, einem Bus 53, die alle datenmäßig miteinander in Verbindung stehen, aufgebaut ist. Im Festwertspeicher 51 sind alle Programme und alle Kenndaten, Kennliniensollwerte usw. unverlierbar gespeichert, während im Schreib/Lese-Speicher 52 die von den Sensoren gelieferten Daten gespeichert werden, bis sie vom Mikroprozessor abgerufen oder durch aktuellere Daten ersetzt werden. In der Zentraleinheit 50 werden die arithmetischen und logischen Operationen mit den eingespeisten Daten durchgeführt. Die Ausgabeeinheit 49 steuert ihrerseits wiederum verschiedene Endstufen 54, 55 an, die zur Zündung 56 oder zur Ansteuerung anderer Stellglieder 57, beispielsweise zur Steuerung des Ladedrucks dienen.The structure of the second control device 18 is shown in somewhat more detail in FIG. The input variables 19, 21 and further input variables 30, for example for knock control, are converted into digital variables in an analog-digital converter 45. The information 20 about the speed and the crankshaft angle degrees, which is already largely digital due to the sensor characteristic, is fed to a pulse shaper 46, which essentially normalizes the pulse shape of the input pulses. All signals in digital form are fed to an input unit 47, which is connected to an output unit 49 via an input / output unit 48. These units 47, 48, 49 form the periphery of a digital signal processing unit, which is constructed from the central unit 50, read-only memories 51, operating data memories 52, a bus 53, all of which are connected to one another in terms of data. In the read-only memory 51, all programs and all characteristic data, characteristic curve setpoints, etc. are stored in a captive manner, while the data supplied by the sensors are stored in the read / write memory 52 until they are called up by the microprocessor or replaced by more current data. In the central processing unit 50, the arithmetic and logical operations are carried out with the data fed in. The output unit 49 in turn controls various output stages 54, 55, which are used for ignition 56 or to control other actuators 57, for example to control the boost pressure.

Dem zweiten Steuergerät wird ebenfalls als Lastinformation 21 das Ausgangssignal des Sensors 12 zur Erfassung der Ansaugluftmenge zugeführt. Da das zweite Steuergerät 18 eine von der Referenzspannungsquelle U1 des ersten Steuergerätes 17 unabhängige Referenzspannungsquelle U2 aufweist, muß wegen der Toleranz in der Ausgangsspannung dieser Referenzspannungsquellen dafür Sorge getragen werden, daß das Eingangssignal für das zweite Steuergerät 18 in keinem Fall Werte annimmt, die oberhalb dem aktuellen Wert der Referenzspannungsquelle U2 liegen. Aus diesem Grunde ist eine Spannungsteilerschaltung bestehend aus den Widerständen R2 und R3 vorgesehen, die die Ausgangsspannung des Lastsensors um einen gewissen Anteil herunterteilt. Damit darüber hinaus eine Unabhängigkeit des Lastsignals vom Absolutwert des im Sensor 12 angeordneten Potentiometers gegeben ist, ist ein zweiter Signalpfad 58 vorgesehen, der die am Gesamtwiderstand des Potentiometers des Sensors 12 anliegende Spannung dem zweiten Steuergerät 18 zuführt. Damit auch dieser Spannungswert den Referenzspannungswert U2 nicht überschreiten kann, ist eine weitere Spannungsteilerschaltung bestehend aus den Widerständen R2', R3'vorgesehen. Im Steuergerät 18 werden diese beiden Informationen 21, 58 im wesentlichen durcheinander dividiert, so daß eine vom Absolutwert des Gesamtwiderstandes des Potentiometers des Sensor 12 unabhängige Meßgröße als Lastinformation zur Verfügung steht. In Abhängigkeit von den verschiedenen Eingangsinformationen berechnen nun beide Steuergeräte Ausgabegrößen zur Ansteuerung der Stellglieder. Hierfür sind insbesondere beim hier interessierenden zweiten Steuergerät 18 Kennfelder vorgesehen, in denen beispielsweise der Zündzeitpunkt in Grad Kurbelwellenwinkel als Funktion der Last und Drehzahl in den Festwertspeichermitteln 51, 52 abgelegt sind.The output signal of the sensor 12 for detecting the amount of intake air is also supplied to the second control unit as load information 21. Since the second control device 18 has a reference voltage source U2 that is independent of the reference voltage source U1 of the first control device 17, care must be taken because of the tolerance in the output voltage of these reference voltage sources that the input signal for the second control device 18 in no case assumes values that exceed the current value of the reference voltage source U2. For this reason, a voltage divider circuit consisting of resistors R2 and R3 is provided, which divides the output voltage of the load sensor down by a certain proportion. So that the load signal is also independent of the absolute value of the potentiometer arranged in the sensor 12, a second signal path 58 is provided, which supplies the voltage applied to the total resistance of the potentiometer of the sensor 12 to the second control device 18. In order that this voltage value cannot exceed the reference voltage value U2, a further voltage divider circuit consisting of the resistors R2 ', R3' is provided. In the control unit 18, these two pieces of information 21, 58 are essentially divided by one another, so that a measurement variable which is independent of the absolute value of the total resistance of the potentiometer of the sensor 12 is available as load information. Depending on the various input information, both control units now calculate output variables for controlling the actuators. For this purpose, characteristic maps are provided in particular for the second control device 18 of interest, in which, for example, the ignition timing is stored in degrees crankshaft angle as a function of the load and speed in the read-only memory means 51, 52.

Ein Beispiel für ein derartiges Kennfeld ist in Figur 3a dargestellt, in dem die Kennfeldwerte als Funktion der Drehzahl und der Ausgangssignale eines Drucksensors als Lastsensor abgelegt sind. In Abhängigkeit vom Ausgangssignal des Drucksensors können im vorliegenden Fall acht Lastbereiche L1 bis L8 und acht Drehzahlbereiche unterschieden werden, so daß insgesamt 64 Kennfeldwerte Abgespeichert sind. Natürlich ist es möglich, zur feineren Abstufung zwischen den einzelnen Kennfeldwerten zu interpolieren. Werden nun die Lastsignale zur Kennfeldansteuerung anstelle von einem Drucksensor von einem Luftmengensensor, insbesondere von einem Luftklappensensor abgeleitet, so nimmt das Kennfeld aufgrund der völlig anderen Ausgangssignalcharakteristik des Luftmengensensors die in Figur 3b dargestellte Form an. Insbesondere verdeutlicht diese Figur, daß ein Lastbereich, beispielsweise der Lastbereich L1 nicht mehr durch einen festen Ausgangsspannungswert über den ganzen Drehzahlbereich beschreibbar ist, sondern daß die Spannungswerte pro Lastbereich eine weite, drehzahlabhängige Bandbreite annehmen. Darüber hinaus wird verdeutlicht, daß die Ausgangssignalcharacteristik des Luftmengensensors derart gestaltet ist, daß die Ausgangswerte des Luftmengensensors in den verschiedenen Drehzahlbereichen gar nicht die volle maximale mögliche Bandbreite der möglichen Ausgangswerte annehmen. Hieraus folgt, daß zur Erzielung der gleichen Auflösung, wie sie mit einem Drucksensor als Lastsensor möglich ist, ein wesentlich größerer Speicher zur Abspeicherung der Kennfeldwerte erforderlich ist. Da der Speicherplatz der heutigen Systeme noch rar ist, und auch hardwaremäßigen Änderungen, beispielsweise durch Einbau weiterer Speicherbausteine im Steuergerät, vermieden werden sollen, werden erfindungsgemäß die Ausgangssignale des Sensors 12 im zweiten Steuergerät durch Rechenfunktionen beeinflußt, so daß die Ausgangscharakteristik des Sensors 12 änderbar ist. Dadurch wird letztendlich erreicht, daß der Wertevorrat der Ausgangssignale des Luftmengensensors in der Weise drehzahlabhängig komprimiert und verschoben wird, daß eine optimale Nutzung des vorhandenen Speicherplatzes bei gleichbleibender Auflösung gegenüber einer Drucksensor-Version zur Lasterfassung gewährleistet ist. Das Verfahren zur Änderung der Ausgangssignalcharakteristik des Luftmengensensors wird im folgenden anhand der Figur 3b näher erläutert.An example of such a map is shown in FIG. 3a, in which the map values are stored as a function of the speed and the output signals of a pressure sensor as a load sensor. Depending on the output signal of the pressure sensor, eight load ranges L1 to L8 and eight speed ranges can be distinguished in the present case, so that a total of 64 map values are stored. Of course, it is possible to interpolate between the individual map values for finer gradation. If the load signals for map control are now derived from an air quantity sensor, in particular an air flap sensor, instead of a pressure sensor, the map takes on the form shown in FIG. 3b due to the completely different output signal characteristics of the air volume sensor. In particular, this figure clarifies that a load range, for example load range L1, can no longer be described by a fixed output voltage value over the entire speed range, but that the voltage values per load range assume a wide, speed-dependent bandwidth. In addition, it is clarified that the output signal characteristic of the air flow sensor is designed in such a way that the output values of the air flow sensor in the various speed ranges do not even cover the full maximum possible range of the possible output values accept. It follows from this that in order to achieve the same resolution as is possible with a pressure sensor as a load sensor, a much larger memory is required for storing the map values. Since the storage space of today's systems is still scarce, and hardware changes, for example by installing additional memory modules in the control unit, are to be avoided, the output signals of the sensor 12 in the second control unit are influenced by computing functions according to the invention, so that the output characteristic of the sensor 12 can be changed . This ultimately ensures that the value set of the output signals of the air flow sensor is compressed and shifted in a manner dependent on the speed in such a way that an optimal use of the available storage space is ensured with a constant resolution compared to a pressure sensor version for load detection. The method for changing the output signal characteristic of the air quantity sensor is explained in more detail below with reference to FIG. 3b.

Der in den einzelnen Drehzahlbereichen mögliche Wertevorrat der Ausgangswerte des Luftmengensensors wird mit einzelnen, insbesondere drehzahlabhängigen additiven Größen C1 (n1),..., C1 (n8),... derart beaufschlagt, daß beispielsweise die niedrigsten Werte aller Wertebereiche einen gemeinsamen gleichen Wert annehmen. Dies kann beispielsweise die Nullinie im abgebildeten Koordinatensystem oder aber auch eine andere, vorteilhaft erscheinende Basisgröße sein. In einem zweiten Schritt werden die einzelnen möglichen Werte eines jeden drehzahlabhängigen Wertebereiches durch die Beaufschlagung mit einer insbesondere drehzahlabhängigen multiplikativen Größe C2 (n1), ..., C2 (n8), ... beaufschlagt, um die drehzahlabhängigen Wertebereiche aneinander anzupassen. In einer einfachen Version kann die multiplikative Konstante C2 auch einen für alle Drehzahlbereiche konstanten Wert annehmen, insbesondere dann, wenn die Variation der einzelnen drehzahlabhängigen Wertbereiche der Ausgangssignale des Luftmengensensors im wesentlichen gleich ist oder vernachlässigbare Unterschiede voneinander aufweist. Durch diese additive und/oder multiplikative Änderung der Ausgangssignale des Luftmengensensors wird erreicht, daß der Wertevorrat in den einzelnen Drehzahlbereichen im wesentlichen identisch wird.The possible range of values for the output values of the air flow sensor in the individual speed ranges is applied with individual, in particular speed-dependent, additive variables C1 (n1), ..., C1 (n8), ... such that, for example, the lowest values of all value ranges have a common, identical value accept. This can be, for example, the zero line in the coordinate system shown, or it can also be another basic variable that appears to be advantageous. In a second step, the individual possible values of each speed-dependent value range are acted upon by a speed-dependent multiplicative variable C2 (n1), ..., C2 (n8), ... in order to adapt the speed-dependent value ranges to one another. In a simple version, the multiplicative constant C2 can also assume a value that is constant for all speed ranges, in particular if the variation of the individual speed-dependent value ranges of the output signals of the air quantity sensor is essentially the same or has negligible differences from one another. This additive and / or multiplicative change in the output signals of the air flow sensor ensures that the value set in the individual speed ranges becomes essentially identical.

Nach einer experimentiellen Bestimmung der Größen C1 (n) und C2 (n) und Abspeicherung dieser Größen in den Festwertspeichermitteln 51 bzw. 52 ist dann eine Anordnung der Kennfeldwerte möglich, wie sie in Figur 3a in bezug auf die Druckgeberversion dargestellt ist. Auch die Genauigkeit, d.h. die Quantisierung bleibt erhalten, so daß mittels dieser softwaremäßigen Transformation der Ausgangssignale des Luftmengensensors eine zur Druckgeber-Version identischer Kennfeldanordnung möglich ist. Darüber hinaus ist es möglich, diese Größen C1 (n), C2 (n) mittels adaptiver Regelstrategien an zeitliche Veränderung anzupassen. Derartige adaptive Regelstrategien sind beispielsweise in der Patentanmeldung P 34 08 215.8 dargestellt, die als Referenz vom Fachmann herangezogen werden kann und deren Offenbarungsgehalt damit Bestandteil dieser Anmeldung ist.After an experimental determination of the variables C1 (n) and C2 (n) and storage of these variables in the read-only memory means 51 and 52, an arrangement of the map values is then possible, as shown in FIG. 3a in relation to the pressure transmitter version. The accuracy, i.e. the quantization is retained, so that by means of this software-based transformation of the output signals of the air quantity sensor, a map arrangement identical to the pressure transmitter version is possible. In addition, it is possible to adapt these variables C1 (n), C2 (n) to changes over time using adaptive control strategies. Such adaptive control strategies are shown, for example, in patent application P 34 08 215.8, which can be used as a reference by a person skilled in the art and whose disclosure content is therefore part of this application.

Eine weitere vorteilhafte Ausgestaltung der Erfindung wird anhand der Figur 4 im folgenden näher erläutert. Mögliche Fehlerquellen in den Ausgangswerten des Luftmengensensors sind beispielsweise darin begründet, daß sich die Stellung des Potentiometers in bezug auf die Stellung der Klappe des Luftmengenmessers im Ansaugkanal verändern kann. Eine hieraus resultierende Dejustage würde zu einer falschen Zuordnung von Kennfeldwerten und Last führen. Auch andere Langzeiteinflüsse können eine Verfälschung des Ausgangssignals des Sensors herbeiführen. Um diese Effekte zu eliminieren, wird erfindungsgemäß eine Plausibilitätsprüfung des Luftmengensensorsignals durchgeführt, indem die Werte einer in den Festwertspeichermitteln 51, 52 abgespeicherten Lastkennlinie mit den Istwerten des Luftmengensensors insbesondere drehzahlabhängig vergleichen werden. Wird dabei eine nach der Plausibilitätsprüfung noch zulässig Abweichung gegenüber einem der Sollwerte festgestellt, so läßt sich durch Addition eines Korrekturgliedes AC1 zu den Größen zur additiven Beeinflussung C1 (n) eine Übereinstimmung zwischen Soll- und Istwert erreichen. Als Sollwertkennlinie kann insbesondere die Vollastkennlinie abgespeicher werden, wobei zur Detektion des Vollastfalles die Stellung der Drosselklappe 13 mittels des Drosselklappenstellungssensors 14 überwacht wird. Ist die Drosselklappe voll geöffnet, so liegt der Vollastfall vor und der beschriebene Soll-Istwertvergleich kann durchgeführt werden. Diese Korrektur kann in erster Näherung für den gesamten Drehzahlbereich gültig sein, d.h. daß alle additiven C1 (n) mit ein und demselben Korrekturwert AC1 modifiziert werden. In einer höheren Näherung ist es darüber hinaus möglich und sehr vorteilhaft, auch den Korrekturwert AC1 drehzahlabhängig zu bestimmen, so daß für jeden Drehzahlbereich ein Korrekturwert AC1 (n) gültig ist. Darüberhinaus hat es sich in verschiedenen Anwendungsfällen als vorteilhaft erwiesen, eine multiplikative Korrekturgröße ΔC2 einzuführen, die in analoger Weise C2 (n) drehzahlabhängig bzw. -unabhängig beeinflußt. Mittels dieser adaptiven Korrekturen der Istwert-Vollastlinie des Luftmengensensors mit einer im Speicher abgelegten Sollwert-Vollastkennlinie ist es möglich, trotz Toleranzen im Meßsystem des Luftmengensensors die korrekten Vollast bzw. oberen Teillastwerte eines Kennfeldes auszugeben. Die Bestimmung des Korrekturwertes ΔC1/2 (n) erfolgt in der Weise, daß die Differenz zwischen dem Soll- und Istwert der Lastkennlinie eliminiert wird. Insgesamt gesehen läßt sich durch die Erfindung ein Luftmengensensor anstelle eines zusätzlichen Drucksensors zur Lasterfassung einsetzen ohne Einbußen in der Genauigkeit und Langzeitstabilität aufzuweisen.A further advantageous embodiment of the invention is explained in more detail below with reference to FIG. 4. Possible sources of error in the output values of the air flow sensor are based, for example, on the fact that the position of the potentiometer can change with respect to the position of the flap of the air flow meter in the intake duct. A resulting misalignment would lead to an incorrect assignment of map values and load. Other long-term influences can also falsify the output signal of the sensor. In order to eliminate these effects, a plausibility check of the air quantity sensor signal is carried out according to the invention by comparing the values of a load characteristic stored in the read-only memory means 51, 52 with the actual values of the air quantity sensor, in particular as a function of speed. If a deviation from one of the setpoints that is still permissible after the plausibility check is determined, then a match between setpoint and actual value can be achieved by adding a correction element AC1 to the quantities for additive influencing C1 (n). The full-load characteristic curve can in particular be stored as the setpoint characteristic curve, the position of the throttle valve 13 being monitored by the throttle valve position sensor 14 in order to detect the full-load case. If the throttle valve is fully open, there is a full load and the described target / actual value comparison can be carried out. In a first approximation, this correction can be valid for the entire speed range, i.e. that all additive C1 (n) are modified with one and the same correction value AC1. In a higher approximation, it is also possible and very advantageous to also determine the correction value AC1 as a function of the speed, so that a correction value AC1 (n) is valid for each speed range. In addition, it has proven to be advantageous in various applications to introduce a multiplicative correction variable ΔC2 which, in an analogous manner, influences or depends on the speed (C2). By means of these adaptive corrections of the actual value full load line of the air quantity sensor with a set point full load characteristic line stored in the memory, it is possible to output the correct full load or upper part load values of a characteristic map despite tolerances in the measuring system of the air quantity sensor. The correction value ΔC1 / 2 (n) is determined in such a way that the difference between the setpoint and actual value of the load characteristic is eliminated. Overall, the invention allows an air quantity sensor to be used instead of an additional pressure sensor for load detection without having to sacrifice accuracy and long-term stability.

Claims (13)

1. Device for a spark-ignited internal combustion engine, comprising a first control unit for modifying at least the fuel-air mixture supplied to the internal combustion engine, at least as a function of a quantity characterizing the load of the internal combustion engine, in which device the load information, as an output quantity of an air-quantity sensor for the air quantity drawn in by the internal combustion engine, is fed to the first control unit, and a second control unit, essentially independent in functional sequence from the first control unit, for modifying at least the ignition point of the internal combustion engine, in which arrangement the second control unit has at least one microcomputer and memories, and at least data for the ignition point of the internal combustion engine are stored in the memories as a function of at least load and speed information, characterized in that the load information for the second control unit is obtained from the air-quantity sensor (12) which supplies the load information for the first control unit (17), and in that, in the second control unit (18), the values of the output signals of the air-quantity sensor (12) are loaded with an additive quantity (C1) or multiplicative quantity (C2), and in that the quantities (C1, C2) are functionally dependent upon the speed of the internal combustion engine, the output signals loaded in this way being used during access for the data for the ignition point.
2. Device according to Claim 1, characterized in that the quantities (C1, C2) are determined via adaptive control strategies.
3. Device according to either of Claim 1 or 2, characterized in that the quantities are stored in memories.
4. Device according to one of the preceding claims, characterized in that the additive (C1) or multiplicative quantity (C2) for modifying the transmission characteristic of the load sensor (12) is determined in such a way that the stock of values of the output signals of the load sensor (12) is essentially not dependent upon the speed of the internal combustion engine.
5. Device according to one of the preceding claims, characterized in that the load sensor (2) has a potentiometer at which the load information can be tapped.
6. Device according to Claim 5, characterized in that the voltage appearing at the centre tap of the potentiometer and the voltage dropping over the entire potentiometer resistance are fed to the second control unit (18) for processing.
7. Device according to Claim 6, characterized in that the two voltages fed to the control unit (18) are divided by one another.
8. Device according to one of the preceding Claims, characterized in that, for a certain load operation of the internal combustion engine, the actual values of the load sensor (12) are com- .pared with a stored desired-value characteristic load curve and, as a function of the result of this comparison, a correcting modification (AC) of the transmission characteristic of the load sensor (12) is possible.
9. Device according to Claim 8, characterized in that, for the correcting modification, additive correction values (ΔC1) are applied to the output signal of the load sensor (12).
10. Device according to either of Claim 8 or 9, characterized in that, for the correcting modification, multiplicative correction values (AC2) are applied to the output signal of the load sensor (12).
11. Device according to either of Claim 9 or 10, characterized in that the correction values (AC1, ΔC2) are functionally dependent upon the speed of the internal combustion engine.
12. Device according to one of Claims 8 to 11, characterized in that the correcting modification is carried out in full-load or upper partial-load operation of the internal combustion engine.
13. Device according to one of Claims 8 to 12, characterized in that the correcting modification is carried out in such a way that the difference between the desired and actual values of the characteristic load curve is minimized.
EP86103080A 1985-04-12 1986-03-07 Device for modifying the operating parameters in an internal-combustion engine Expired - Lifetime EP0197315B1 (en)

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DE19853513086 DE3513086A1 (en) 1985-04-12 1985-04-12 DEVICE FOR AN INTERNAL COMBUSTION ENGINE FOR INFLUENCING OPERATING PARAMETERS
DE3513086 1985-04-12

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EP0197315A3 EP0197315A3 (en) 1988-03-02
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EP0197315A2 (en) 1986-10-15
EP0197315A3 (en) 1988-03-02
US4762105A (en) 1988-08-09
DE3513086A1 (en) 1986-10-16
DE3673206D1 (en) 1990-09-13
DE3513086C2 (en) 1988-06-01

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