EP0750105B1 - Verfahren und Vorrichtung zum Kalibrieren eines Drehgebers - Google Patents

Verfahren und Vorrichtung zum Kalibrieren eines Drehgebers Download PDF

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Publication number
EP0750105B1
EP0750105B1 EP19960303794 EP96303794A EP0750105B1 EP 0750105 B1 EP0750105 B1 EP 0750105B1 EP 19960303794 EP19960303794 EP 19960303794 EP 96303794 A EP96303794 A EP 96303794A EP 0750105 B1 EP0750105 B1 EP 0750105B1
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Prior art keywords
rotary element
time periods
markers
engine
revolution
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EP19960303794
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English (en)
French (fr)
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EP0750105A1 (de
Inventor
Benjamin James Bradshaw
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Sagem SA
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Sagem SA
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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
    • F02D41/009—Electrical control of supply of combustible mixture or its constituents using means for generating position or synchronisation signals

Definitions

  • the present invention relates to a method of and an apparatus for calibrating a rotary position transducer.
  • Modern internal combustion engines of both spark-ignition and compression-ignition types are controlled by engine management systems based on programmed data processors, for instance microcomputers.
  • engine management systems control the amount of air/fuel mixture supplied to the cylinders of the engine and the timing of ignition in each cylinder.
  • the engine management system requires signals which indicate the position of the engine output shaft.
  • a known type of rotary position transducer comprises a toothed wheel, for instance mounted on an engine crankshaft.
  • a variable reluctance transducer cooperates with the toothed wheel to supply a signal, for instance corresponding to the leading edge of each tooth as it passes the sensor.
  • the toothed wheel is machined so that the teeth are nominally equi-angularly spaced.
  • the angular spacing of the teeth is subject to unpredictable errors. In the absence of calibration to assess and compensate for such errors, the sensor output signals supply position information to the engine management system which is affected by these tolerances and this results in reduced accuracy of control of the engine.
  • DE 4 221 891 discloses a calibration technique in which the time for a complete revolution of a toothed wheel is compared with the time period between consecutive passages of the teeth past the sensor. Differences between the times for each such "sector" and the expected average time for each sector calculated from the time for one complete revolution of the wheel are attributed to tooth errors. To eliminate errors which occur when the engine speed is increasing or decreasing during the calibration, it is possible to perform three successive 360° measurements spaced 120° apart for a six cylinder engine. The error calculations are performed and then averaged.
  • GB 2 134 265 discloses an arrangement for generating rotational speed data for an internal combustion engine. This technique attempts to compensate for cyclic speed variations but does not perform a calibration of position sensing.
  • GB 2 198 241 discloses an arrangement for calculating correction coefficients for tooth spacing which assumes uniform crankshaft speed throughout a full revolution of the crankshaft. However, errors arise because of the cyclic nature of the actual crankshaft speed.
  • US 5 117 681 discloses a technique which performs calibration during engine rotation without combustion processes. Performing such calibration with a closed throttle and with fuelling cut off is said to minimise the effects of compression ratio differences among the cylinders of the engine. Calibration is performed by comparing the time period for individual sectors between consecutive teeth with a time period which is unaffected by tooth errors, such as that corresponding to a whole number of engine revolutions. The latter measurement is then compared with an individual sector measurement which is, as far as possible, centred within the measurement without tooth errors. Differences in average speed are assumed to be caused by tooth errors. This technique assumes linear decrease in velocity i.e. constant deceleration, but requires that the individual sector measurement be centralised within, for instance, a 360° measurement.
  • the teeth correspond to top dead centre positions of various engine cylinders.
  • three teeth and hence three sectors are provided on the toothed wheel so that this requirement can be achieved.
  • this requirement cannot be met.
  • a method of calibrating a rotary position transducer comprising a rotary element having a plurality of markers and a sensor cooperating with the rotary element to produce a position signal when each marker passes the sensor, comprising the steps of:
  • the rotary element may be driven by an internal combustion engine under closed throttle fuel cut-off conditions. Such conditions provide substantially constant deceleration with respect to revolutions of the crankshaft.
  • the rotary element may comprise a toothed wheel and the sensor may comprise a variable reluctance sensor.
  • the markers may be nominally equi-angularly spaced.
  • the number of markers may be equal to the number of firing events per revolution of an engine crankshaft.
  • the first and second revolutions of the engine may be consecutive revolutions.
  • the determining step may comprise performing the following calculation: where:
  • an apparatus for calibrating a rotary position transducer comprising a rotary element having a plurality of markers and a sensor according to the independent apparatus claim.
  • calibration is required only once for each rotary position transducer, it may be performed repeatedly, for instance each time an internal combustion engine is operated in closed throttle fuel cut-off conditions of sufficient duration or once when such conditions occur during each time the engine is operated. Thus, if the rotary element has to be changed, the new element can be automatically recalibrated without requiring any operator intervention.
  • the calibration as described above may be performed several times and an average calibration obtained.
  • the rotary position transducer shown in Figure 1 is intended for use with an internal combustion engine and comprises a toothed wheel 1 which is mounted on an engine crankshaft and which cooperates with a variable reluctance sensor 2. Teeth 3 to 6 are formed in the circumference of the wheel 1 and the passage of the teeth past the sensor 2 is detected. In particular, the output signal of the sensor 2 is processed by suitable electronic circuitry to determine the passage of the leading edge of each tooth past the sensor 2.
  • the teeth 3 to 6 are nominally equi-angularly spaced about the axis of the wheel 1.
  • the angular spacings ⁇ 1 to ⁇ 4 between consecutive pairs of teeth are nominally all equal to 90 degrees.
  • manufacturing tolerances result in errors such that the actual angular spacings ⁇ 1 to ⁇ 4 differ from 90 degrees by respective angular errors ⁇ 1 to ⁇ 4 .
  • Figure 2 shows the wheel 1 mounted on the crankshaft 7 of an eight cylinder internal combustion engine 8.
  • the sensor 2 is connected to an engine management system 9 which supplies control signals to the engine 8 for controlling the air/fuel ratio and quantity of mixture supplied to the cylinders of the engine 8 and the ignition timing of the engine.
  • the engine management system 9 may be of any suitable type and many such systems are known.
  • the engine management system 9 is further connected to a position transducer 10 which determines the position of an accelerator pedal 11 or throttle valve operated by a vehicle driver.
  • the driver produces an engine demand signal by operating the accelerator pedal 11.
  • the position of the accelerator pedal 11, which corresponds to the driver demand is determined by the position transducer 10 and supplied to the engine management system 9, which controls the ignition and fuelling of the engine 8 in accordance with the driver demand and other parameters, such as engine output speed, crankshaft position, engine temperature, etc.
  • the engine management system 9 is based on a microcontroller which is suitably programmed to perform engine management operation.
  • the microcontroller is further programmed to perform calibration of the angular separations ⁇ 1 to ⁇ 4 of the teeth 3 to 6 on the wheel 1. It is thus possible to incorporate such calibration by providing appropriate additional software within the engine management system 9 so that no additional hardware is required.
  • the engine management system 9 detects when the accelerator pedal 11 is at its normal rest position corresponding to zero driver demand and the engine is in a fuel cut-off condition. The engine management system performs the calibration provided the driver demand remains at zero for a sufficient number of revolutions of the engine crankshaft 7.
  • the engine management system 9 measures the time periods between the passage of consecutive ones of the teeth 3 to 6 for at least two complete revolutions of the crankshaft 7 with the engine 8 operating under closed throttle fuel cut-off conditions.
  • the measured time periods are represented herein after by t 1 to t 8 .
  • Figure 3 is a graph showing engine speed in revolutions per minute against time in seconds and shows the effect of closing the throttle and cutting off fuel at the two second point on the horizontal axis.
  • the reduction in engine speed is non-linear i.e. deceleration with respect to time is not constant.
  • Figure 4 shows the same speed graph as Figure 3 but plotted against top dead centre (TDC) number on the horizontal axis, which corresponds to plotting engine speed against the number of engine revolutions.
  • TDC top dead centre
  • the technique may be performed at any time during conditions of overrun i.e. closed throttle fuel cut-off operation of the engine, preferably with the engine disconnected from the road wheels by a transmission system.
  • calibration of the wheel is required only once and with the engine disconnected from the road wheels by a transmission system.
  • calibration of the wheel is required only once and need not be repeated unless the existing wheel is replaced by a new wheel, it may be convenient to perform the calibration once after each time the engine is operated.

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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)

Claims (10)

  1. Verfahren zum Eichen eines Drehpositionsgebers mit einem Drehelement (1), das mehrere Markierungen (3, 4, 5, 6) und einen mit dem Drehelement (1) zusammenwirkenden Sensor (2) aufweist, um ein Positionssignal zu erzeugen, wenn jede Markierung (3, 4, 5, 6) den Sensor (2) passiert, mit den folgenden Schritten:
    Drehen des Drehelements (1) mit im wesentlichen konstanter Verzögerung;
    Messen von ersten Zeitabschnitten zwischen aufeinanderfolgenden Positionssignalen während einer ersten Umdrehung des Drehelements (1);
    Messen von zweiten Zeitabschnitten zwischen aufeinanderfolgenden Positionssignalen während einer zweiten Umdrehung des Drehelements (1) nach der ersten Umdrehung; und
    Bestimmen von korrigierten Winkelabständen zwischen den Markierungen (3, 4, 5, 6) aus den ersten und zweiten Zeitabschnitten durch Berechnung von mittleren Geschwindigkeiten während der ersten und zweiten Zeitabschnitte, Subtraktion der mittleren Geschwindigkeit für jeden der zweiten Zeitabschnitte von der mittleren Geschwindigkeit für den entsprechenden von den ersten Zeitabschnitten, um mehrere Geschwindigkeitsdifferenzen zu erhalten, und Gleichsetzen der Geschwindigkeitsdifferenzen unter Verwendung der Annahme, daß die Verzögerung des Drehelements (1) konstant ist, sowie der Tatsache, daß für eine volle Umdrehung des Drehelements die Summe der korrigierten Winkelabstände zwischen den Markierungen (3, 4, 5, 6) gleich 360° ist.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die erste und die zweite Umdrehung aufeinanderfolgende Umdrehungen sind.
  3. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß der Bestimmungsschritt die Berechnung des Winkelabstands n zwischen aufeinanderfolgenden Markierungen (3, 4, 5, 6) nach der folgenden Formel aufweist:
    Figure 00160001
    Dabei bedeuten:
    N die Anzahl der Markierungen (3, 4, 5, 6) an dem Drehelement (1);
    t1n den ersten Zeitabschnitt, der dem n-ten Winkelabstand n entspricht;
    t2n den zweiten Zeitabschnitt, der dem n-ten Winkelabstand n entspricht;
    n = 1, 2, ..., N; und
    X ein Winkelmaß einer einzelnen Umdrehung.
  4. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die Markierungen (3, 4, 5, 6) nominell gleiche Winkelabstände aufweisen.
  5. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das Drehelement ein Zahnrad (1) aufweist.
  6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß der Sensor einen Sensor (2) mit veränderlicher Reluktanz aufweist.
  7. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das Drehelement (1) durch einen Verbrennungsmotor (8) bei geschlossener Drosselklappe und gesperrter Kraftstoffzufuhr angetrieben wird.
  8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß die Anzahl der Markierungen (3, 4, 5, 6) gleich der Anzahl der Zündungsereignisse pro Umdrehung einer Motorkurbelwelle ist.
  9. Vorrichtung zum Eichen eines Drehpositionsgebers mit einem Drehelement (1), das mehrere Markierungen (3, 4, 5, 6) und einen mit dem Drehelement (1) zusammenwirkenden Sensor (2) aufweist, um ein Positionssignal zu erzeugen, wenn jede Markierung (3, 4, 5, 6) den Sensor (2) passiert, wobei die Vorrichtung aufweist: eine Einrichtung zum Messen von ersten Zeitabschnitten zwischen aufeinanderfolgenden Positionssignalen während einer ersten Umdrehung des Drehelements (1); eine Einrichtung zum Messen von zweiten Zeitabschnitten zwischen aufeinanderfolgenden Positionssignalen während einer zweiten Umdrehung des Drehelements (1) nach der ersten Umdrehung; und eine Bestimmungseinrichtung zum Bestimmen von korrigierten Winkelabständen zwischen den Markierungen (3, 4, 5, 6) aus den ersten und zweiten Zeitabschnitten bei einer Drehung des Drehelements (1) mit im wesentlichen konstanter Verzögerung, wobei die Tatsache benutzt wird, daß für eine volle Umdrehung des Drehelements (1) die Summe der korrigierten Winkelabstände zwischen den Markierungen (3, 4, 5, 6) gleich 360° ist; und eine Einrichtung zum Subtrahieren der mittleren Geschwindigkeiten für jeden der zweiten Zeitabschnitte von der mittleren Geschwindigkeit für den entsprechenden von den ersten Zeitabschnitten, um mehrere Geschwindigkeitsdifferenzen zu erhalten, und zum Gleichsetzen der Geschwindigkeitsdifferenzen.
  10. Vorrichtung nach Anspruch 9 für einen Drehpositionsgeber eines Verbrennungsmotors (8), dadurch gekennzeichnet, daß sie innerhalb eines Motorführungssystem (9) des Motors (8) realisiert ist.
EP19960303794 1995-06-21 1996-05-28 Verfahren und Vorrichtung zum Kalibrieren eines Drehgebers Expired - Lifetime EP0750105B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9512652.0A GB9512652D0 (en) 1995-06-21 1995-06-21 A method of and an apparatus for calibrating a rotary position transducer
GB9512652 1995-06-21

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EP0750105A1 EP0750105A1 (de) 1996-12-27
EP0750105B1 true EP0750105B1 (de) 2000-04-19

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Publication number Priority date Publication date Assignee Title
DE19734595A1 (de) * 1997-08-09 1999-02-11 Bosch Gmbh Robert Verfahren zur Ermittlung von Segmentzeiten
DE19802109C2 (de) * 1998-01-21 2000-12-21 Siemens Ag Verfahren zur Adaption von mechanischen Toleranzen bei der Zeitmessung an sich drehenden Wellen

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US5117681A (en) * 1990-10-01 1992-06-02 Ford Motor Company Correction of systematic position-sensing errors in internal combustion engines
DE4133679A1 (de) * 1991-10-11 1993-04-22 Bosch Gmbh Robert Verfahren zur adaption von mechanischen toleranzen eines geberrades

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DE69607788T2 (de) 2000-11-16
DE69607788D1 (de) 2000-05-25
GB9512652D0 (en) 1995-08-23

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