WO1999001774A1 - Diagnostic device for detecting errors in an induction sensor - Google Patents

Diagnostic device for detecting errors in an induction sensor Download PDF

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Publication number
WO1999001774A1
WO1999001774A1 PCT/DE1998/001836 DE9801836W WO9901774A1 WO 1999001774 A1 WO1999001774 A1 WO 1999001774A1 DE 9801836 W DE9801836 W DE 9801836W WO 9901774 A1 WO9901774 A1 WO 9901774A1
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Prior art keywords
voltage
diagnostic
vdiag
diagnostic device
vref
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PCT/DE1998/001836
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German (de)
French (fr)
Inventor
Alfons Fisch
Horst Punzmann
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Siemens Aktiengesellschaft
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Publication of WO1999001774A1 publication Critical patent/WO1999001774A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/488—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by variable reluctance detectors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/171—Detecting parameters used in the regulation; Measuring values used in the regulation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P21/00—Testing or calibrating of apparatus or devices covered by the preceding groups
    • G01P21/02—Testing or calibrating of apparatus or devices covered by the preceding groups of speedometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
    • G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
    • G01R31/2829—Testing of circuits in sensor or actuator systems

Definitions

  • the invention relates to a diagnostic device for detecting incorrect conclusions in an inductive sensor according to the preamble of claim 1.
  • Inductive sensors are used, for example, in motor vehicle electronics to measure the position and speed of the crankshaft of an internal combustion engine in order to control or regulate ignition or fuel injection. They are also used in the measurement of wheel speed for processing n anti-lock braking systems (ABS) and traction control systems (ASR).
  • ABS anti-lock braking systems
  • ASR traction control systems
  • the inductive sensor consists of a coil winding with a magnetized core, on which a sensor element m in the form of a gearwheel synchronized with the crankshaft or the wheel, the flanks of which induce a characteristic voltage when the inductive sensor m moves past the coil winding.
  • the course of this induction voltage is generally meandering and can be regarded as sinusoidal in a first approximation.
  • the evaluation electronics which contain a comparator circuit, which are connected downstream of the inductive sensor, mainly detect the zero crossings of the induction voltage (the sensor signal) and form them into a digital output signal which is fed to further control or regulating devices.
  • the subsequent processing of the digital output signal of the comparator connected downstream of the inductive sensor usually takes place in a microcontroller of an engine control unit, by means of which the ignition and fuel injection are controlled.
  • the cables are fed to the inductive sensors in the motor vehicle via cable harnesses with shielded cables, where necessary.
  • a method and a device for testing the sensitivity of inductive sensors is known.
  • a first signal proportional to the amplitude of the voltage generated by the sensor and, at the same time, a second signal proportional to the frequency of the pulses are formed.
  • a third signal is formed from the ratio of the first to the second signal, which is compared with a predetermined variable, which is typical for the sensor type, the difference between the third signal and the typical variable being used as a good criterion.
  • the three signals are formed simultaneously by means of a coil as a low-pass filter, which is connected with a shunt between the connections of the inductive sensor, an evaluation unit being connected to the connection point between the coil and the resistor.
  • This method and the associated device serve the purpose of being able to check the sensitivity of the inductive sensor in the frequency or speed range of interest, in particular at low speeds. It should also be checked whether, for example, the wheel sensors in anti-lock braking systems (ABS) emit sufficiently high signals so that the position of the wheel sensor can also be checked with respect to the sensor element connected to the wheel.
  • ABS anti-lock braking systems
  • the present invention is therefore based on the object of a diagnostic device for detecting incorrect conclusions and
  • the diagnostic device consists of a series circuit connected between the connections of the inductive sensor and composed of two identical components or component combinations (resistors, capacitors, coils), the connection point of which is connected to a reference voltage source via a further resistor At this connection point, a diagnostic voltage can be tapped, which can be evaluated in a discrimination device for the diagnosis of characteristic incorrect conclusions.
  • the series circuit consists of a “symmetrical” voltage divider consisting of two resistors of the same size, the tapping of which is connected to the connection of the reference voltage source via a further resistor.
  • the tapped diagnostic voltage can be evaluated in a discrimination circuit, for example by comparison with threshold values or after digitization, for example in a microcontroller, by means of a program and the errors can be displayed.
  • the diagnostic device has the essential advantage that a large number of characteristic incorrect conclusions (interruption or termination of the coil winding or a supply line to the supply voltage or to ground reference potential) can be detected, evaluated and displayed with relatively few components.
  • An embodiment of the invention is shown in the single figure and shows a basic circuit diagram of the diagnostic device according to the invention.
  • the reference number 1 shows an inductive sensor with its coil winding and the magnetized core, on which the transmitter element 2 can be moved past.
  • the transmitter element 2 is, for example, a gear wheel connected to a crankshaft or a flywheel of an internal combustion engine with a characteristic gap, which is used to determine the position of the crankshaft, in particular to determine the top dead center.
  • the reference numerals 10 and 11 identify connecting lines between the sensor 1 and an evaluation electronics 3.
  • Reference numerals 5 and 6 identify the connections of the inductive sensor 1.
  • the connecting lines 10 and 11 lead via two resistors R4 and R5 to a downstream evaluation electronics 3, which is operated with a supply voltage Vsupply.
  • the evaluation electronics 3 essentially consist of a comparator 9, at the output of which a digital output signal Vout for processing the sensor output signal in a subsequent, not shown provided control or regulating device is provided.
  • Antiparallel diodes D1 and D2 are connected between the non-inverting (+) and inverting (-) input of the comparator 9, essentially for better detection of the zero crossings of the sensor output signal for its digitization.
  • a capacitor C2 is connected between the two inputs of the comparator 9 and between each input (+, -) of the comparator 9 and ground reference potential there is a capacitor C1 or C3.
  • the capacitors C1, C2, C3 in cooperation with the resistors R4 and R5 have a low-pass characteristic in order to suppress high-frequency components of the inductive sensor signal or interference.
  • the diagnostic device consists of the series connection between the connecting lines 10 and 11 of the inductive sensor 1 and consists of two resistors R2 and R3, the connection point 8 of which is connected to a reference voltage source Vref via a further resistor R1.
  • the diagnostic voltage Vdiag can be tapped off at this connection 8 and is used to diagnose characteristic incorrect conclusions of the above. Type can be evaluated in a discrimination facility D, as will be described below.
  • a capacitor C4 is connected between terminal 8 and ground reference potential to suppress high-frequency interference.
  • the supply voltage source Vsupply and the reference voltage source Vref have common ground reference potential.
  • a compensating current flows between the supply voltage source Vsupply and the reference voltage source Vref via the resistors R1 and the parallel connection of R2 and R3, which produces a voltage drop across all resistors.
  • the existing shield cable as capacitive coupling also to ground reference potential.
  • the AC voltage generated by the inductive sensor 1 becomes highly asymmetrical and can be evaluated in the discrimination device D with a further logic gate circuit or, after analog-digital conversion, can be processed into an error signal by means of a program, for example in a microcontroller.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

According to the invention a transmitter element (2) can be moved past an induction sensor (1) and a digital output signal (Vout) can be generated by means of an electronic evaluation circuit (3). Between the connecting lines (10, 11) of said induction sensor a symmetrical voltage divider (R2, R3) is positioned, the tapping point (8) of which is connected to a reference voltage source (Vref) via a resistor (R1). The diagnostic voltage (Vdiag) which can be tapped at the level of the tapping point (8) is evaluated in a discrimination unit (D) positioned downstream so as to detect characteristic errors.

Description

Beschreibungdescription
Diagnoseeinrichtung zur Erkennung von Fehlschlüssen bei einem induktiven SensorDiagnostic device for detecting faulty conclusions in an inductive sensor
Die Erfindung betrifft eine Diagnoseeinrichtung zur Erkennung von Fehlschlüssen bei einem induktiven Sensor nach dem Oberbegriff von Anspruch 1.The invention relates to a diagnostic device for detecting incorrect conclusions in an inductive sensor according to the preamble of claim 1.
Induktive Sensoren werden beispielsweise in der Kraftfahrzeug-Elektronik dazu verwendet, die Position und Geschwindigkeit der Kurbelwelle einer Brennkraftmaschine zu messen, um damit Zündung oder Kraftstoffeinspritzung zu steuern oder zu regeln. Sie finden auch Verwendung bei der Messung von Rad- drehgeschwmdigkeit zur Verarbeitung n Antiblockiersystemen (ABS) und Antriebsschlupfregelsystemen (ASR) .Inductive sensors are used, for example, in motor vehicle electronics to measure the position and speed of the crankshaft of an internal combustion engine in order to control or regulate ignition or fuel injection. They are also used in the measurement of wheel speed for processing n anti-lock braking systems (ABS) and traction control systems (ASR).
Der induktive Sensor besteht dabei aus einer Spulenwicklung mit einem magnetisierten Kern, an dem ein Geberelement m Form eines mit der Kurbelwelle oder4 dem Rad synchronlaufenden Zahnrades, dessen Flanken beim Vorbeibewegen am induktiven Sensor m dessen Spulenwicklung eine charakteristische Spannung induzieren. Der Verlauf dieser Induktionsspannung ist m der Regel maanderformig und kann in erster Näherung als sinusförmig betrachtet werden. Über eine dem induktiven Sensor nachgeschaltete Auswerteelektronik, die eine Kompara- torschaltung enthalt, werden hauptsächlich die Nulldurchgange der Induktionsspannung (des Sensorsignals) erfaßt und zu einem digitalen Ausgangssignal geformt, das weiteren Steuer- oder Regeleinrichtungen zugeführt wird.The inductive sensor consists of a coil winding with a magnetized core, on which a sensor element m in the form of a gearwheel synchronized with the crankshaft or the wheel, the flanks of which induce a characteristic voltage when the inductive sensor m moves past the coil winding. The course of this induction voltage is generally meandering and can be regarded as sinusoidal in a first approximation. The evaluation electronics, which contain a comparator circuit, which are connected downstream of the inductive sensor, mainly detect the zero crossings of the induction voltage (the sensor signal) and form them into a digital output signal which is fed to further control or regulating devices.
Üblicherweise erfolgt die nachfolgende Verarbeitung des digitalen Ausgangssignals des dem induktiven Sensor nachgeschalteten Komparators in einem Microcontroller eines Motorsteuer- gerats, von welchem Zündung und Kraftstoffeinspritzung gesteuert werden. Die Leitungszufuhrungen zu den induktiven Sensoren im Kraftfahrzeug erfolgt über Kabelbaume mit geschirmten Leitungen, wo erforderlich.The subsequent processing of the digital output signal of the comparator connected downstream of the inductive sensor usually takes place in a microcontroller of an engine control unit, by means of which the ignition and fuel injection are controlled. The cables are fed to the inductive sensors in the motor vehicle via cable harnesses with shielded cables, where necessary.
Aus der DE-PS 28 41 289 ist ein Verfahren und eine Verrichtung zum Prüfen der Empfindlichkeit von induktiven Sensoren bekannt. Dabei werden ein der Amplitude der vom Sensor erzeugten Spannung proportionales erstes Signal und gleichzeitig ein der Frequenz der Impulse proportionales zweites Si- gnal gebildet. Aus dem Verhältnis von erstem zu zweitem Signal wird ein drittes Signal gebildet, das mit einer vorgegebenen, für die Sensorbauart typischen Große verglichen wird, wobei d e Differenz zwischen drittem Signal und typischer Große als Gutekriterium verwendet wird. Die Bildung der drei Signale erfolgt gleichzeitig mittels einer Spule als Tiefpaß, die mit einem Nebenwiderstand zwischen die Anschlüsse des induktiven Sensors geschaltet ist, wobei am Verbindungspunkt von Spule und Widerstand eine Auswerteeinheit angeschlossen ist. Dieses Verfahren und die zugehörige Vorrichtung dienen dem Zweck, eine Überprüfung der Empfindlichkeit des induktiven Sensors im interessierenden Frequenz- oder Drehzahlbe- reich, insbesondere bei niedrigen Drehzahlen vornehmen zu können. Ferner soll überprüft werden, ob beispielsweise von den Radsensoren bei Antiblockiersystemen (ABS) genügend hohe Signale abgegeben werden, so daß auch die Stellung des Radsensors bezuglich des mit dem Rad vebundenen Geberelements geprüft werden kann. In der genannten Veröffentlichung werden Fehlerquellen, die im wesentlichen direkt im induktiven Sensor oder im Zusa menspiel von Sensor und Geberelement ihre Begründung haben, detektiert und ausgewertet.From DE-PS 28 41 289 a method and a device for testing the sensitivity of inductive sensors is known. A first signal proportional to the amplitude of the voltage generated by the sensor and, at the same time, a second signal proportional to the frequency of the pulses are formed. A third signal is formed from the ratio of the first to the second signal, which is compared with a predetermined variable, which is typical for the sensor type, the difference between the third signal and the typical variable being used as a good criterion. The three signals are formed simultaneously by means of a coil as a low-pass filter, which is connected with a shunt between the connections of the inductive sensor, an evaluation unit being connected to the connection point between the coil and the resistor. This method and the associated device serve the purpose of being able to check the sensitivity of the inductive sensor in the frequency or speed range of interest, in particular at low speeds. It should also be checked whether, for example, the wheel sensors in anti-lock braking systems (ABS) emit sufficiently high signals so that the position of the wheel sensor can also be checked with respect to the sensor element connected to the wheel. In the publication mentioned, sources of error which are essentially based directly in the inductive sensor or in the interplay of sensor and sensor element are detected and evaluated.
Aus der DE 195 26 435 AI ist eine Schaltungsanordnung zur Fehler- oder Leckstromerkennung auf der Versorgungsleitung einer elektronischen Schaltung bei abgeschalteter Versor- gungsspannung bekannt. Mit der Versorgungsleitung ist sowohl eine von einer Hilfsspannung gespeiste Stromquelle als auch ein nach Masse führender Spannungsteiler verbunden, über des- sen Abgriff das sich bei abgeschalteter Versorgungsspannung auf der Versorgungsleitung einstellende Potential mittels eines Potentialmonitors ermittelt und ausgewertet wird. Mit dieser Schaltung sind bei eingeschalteter Versorgungsspannung weder Schlüsse zur Batteriespannung oder zum Massepotential noch Leitungsunterbrechungen detektierbarFrom DE 195 26 435 AI a circuit arrangement for fault or leakage current detection on the supply line of an electronic circuit when the supply voltage is switched off is known. Both a current source fed by an auxiliary voltage and a voltage divider leading to ground are connected to the supply line, via which Tapping the potential arising on the supply line when the supply voltage is switched off is determined and evaluated by means of a potential monitor. With this circuit, when the supply voltage is switched on, no conclusions about the battery voltage or the ground potential nor line interruptions can be detected
Im Zuge der Entwicklung elektronischer Komponenten für die Kraftfahrzeug-Elektronik hat sich das Erfordernis gezeigt, Fehlschlüsse bei induktiven Sensoren, beispielsweise Schlüsse zur Batteriespannung oder zu Masse, die an beliebigen Stellen im Sensor oder dessen Verbindungsleitungen auftreten können, aber auch Leitungsunterbrechungen in den Verbindungsleitungen nicht nur im Stillstand, sondern auch während des Betriebes erfaßbar, auswertbar und anzeigbar zu machen.In the course of the development of electronic components for motor vehicle electronics, the need has arisen for faulty conclusions in inductive sensors, for example, conclusions regarding battery voltage or ground, which can occur anywhere in the sensor or its connecting lines, but also not only for line interruptions in the connecting lines at standstill, but also to make it detectable, evaluable and displayable during operation.
Der vorliegenden Erfindung liegt daher die Aufgabe zugrunde, eine Diagnoseeinrichtung zur Erkennung von Fehlschlüssen undThe present invention is therefore based on the object of a diagnostic device for detecting incorrect conclusions and
Leitungsunterbrechungen an induktiven Sensoren und ihren Zu- leitungen bei eingeschalteter Versorgungsspannung anzugeben.Specify line interruptions on inductive sensors and their supply lines when the supply voltage is switched on.
Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß die Diagnoseeinrichtung aus einer zwischen die Anschlüsse des induktiven Sensors geschalteten Reihenschaltung aus zwei glei- chen Bauelementen oder Bauelementkombinationen (Widerständen, Kondensatoren, Spulen) besteht, deren Verbindungspunkt über einen weiteren Widerstand mit einer Referenzspannungsquelle verbunden ist, wobei an diesem Verbindungspunkt eine Diagnosespannung abgreifbar ist, die zur Diagnose von charakteri- stischen Fehlschlüssen in einer Diskriminierungseinrichtung auswertbar ist.This object is achieved according to the invention in that the diagnostic device consists of a series circuit connected between the connections of the inductive sensor and composed of two identical components or component combinations (resistors, capacitors, coils), the connection point of which is connected to a reference voltage source via a further resistor At this connection point, a diagnostic voltage can be tapped, which can be evaluated in a discrimination device for the diagnosis of characteristic incorrect conclusions.
In einer bevorzugten Ausführungsform besteht die Reihenschaltung aus einem „symmetrischen" Spannungsteiler aus zwei gleich großen Widerständen, dessen Abgriff über einen weiteren Widerstand mit dem Anschluß der Referenzspannungsquelle verbunden ist. Die abgegriffene Diagnosespannung kann in einer Diskriminierungsschaltung, beispielsweise durch Vergleich mit Schwellwerten oder nach Digitalisierung, beispielsweise in einem Microcontroller, mittels eines Programms ausgewertet und die Fehler zur Anzeige gebracht werden.In a preferred embodiment, the series circuit consists of a “symmetrical” voltage divider consisting of two resistors of the same size, the tapping of which is connected to the connection of the reference voltage source via a further resistor. The tapped diagnostic voltage can be evaluated in a discrimination circuit, for example by comparison with threshold values or after digitization, for example in a microcontroller, by means of a program and the errors can be displayed.
Die erfindungsgemäße Diagnoseeinrichtung hat den wesentlichen Vorteil, daß mit relativ wenigen Bauelementen eine Vielzahl von charakteristischen Fehlschlüssen (Unterbrechung oder Schluß der Spulenwicklung oder einer Versorgungsleitung zur Versorgungsspannung oder zu Massebezugspotential) erfaßbar, auswertbar und anzeigbar sind.The diagnostic device according to the invention has the essential advantage that a large number of characteristic incorrect conclusions (interruption or termination of the coil winding or a supply line to the supply voltage or to ground reference potential) can be detected, evaluated and displayed with relatively few components.
Weitere vorteilhafte Ausgestaltungen der Erfindung ergeben sich aus den Unteransprüchen.Further advantageous embodiments of the invention result from the subclaims.
Ein Ausführungsbeispiel der Erfindung ist in der einzigen Figur dargestellt und zeigt ein Prinzipschaltbild der erfindungsgemäßen Diagnoseeinrichtung .An embodiment of the invention is shown in the single figure and shows a basic circuit diagram of the diagnostic device according to the invention.
Das Bezugszeichen 1 zeigt einen induktiven Sensor mit seiner Spulenwicklung und dem magnetisierten Kern, an dem das Geberelement 2 vorbeibewegbar ist. Das Geberelement 2 ist beispielsweise ein mit einer Kurbelwelle oder einem Schwungrad einer Brennkraftmaschine verbundenes Zahnrad mit einer charakteristischen Lücke, die der Positionsbestimmung der Kurbelwelle, insbesondere Festlegung des oberen Totpunkts, dient. Mit den Bezugszeichen 10 und 11 sind Verbindungsleitungen zwischen dem Sensor 1 und einer Auswerteelektronik 3 gekennzeichnet. Bezugszeichen 5 und 6 kennzeichnen die Anschlüsse des induktiven Sensors 1. Die Verbindungsleitungen 10 und 11 führen über zwei Widerstände R4 und R5 an eine nachgeschaltete Auswerteelektronik 3, die mit einer Versorgungsspannung Vsupply betrieben ist. Die Auswerteelektronik 3 besteht im wesentlichen aus einem Komparator 9, an dessen Ausgang ein digitales Ausgangssignal Vout zur Verarbeitung des Sensorausgangssignals in einer nachfolgenden, nicht dar- gestellten Steuer- oder Regeleinrichtung bereitgestellt wird. Zwischen nichtinvertierendem (+) und invertierendem (-) Eingang des Komparators 9 sind antiparallele Dioden Dl und D2 geschaltet, im wesentlichen zur besseren Erfassung der Null- durchgänge des Sensorausgangssignals zu dessen Digitalisierung. Außerdem ist zwischen die beiden Eingänge des Komparators 9 ein Kondensator C2 geschaltet und zwischen jedem Eingang (+,-)des Komparators 9 und Massebezugspotential liegt ein Kondensator Cl bzw. C3. Die Kondensatoren C1,C2,C3 im Zu- sammenwirken mit den Widerständen R4 und R5 haben eine Tiefpaßcharakteristik, um hochfrequete Anteile des induktiven Sensorsignals oder Störungen auszublenden.The reference number 1 shows an inductive sensor with its coil winding and the magnetized core, on which the transmitter element 2 can be moved past. The transmitter element 2 is, for example, a gear wheel connected to a crankshaft or a flywheel of an internal combustion engine with a characteristic gap, which is used to determine the position of the crankshaft, in particular to determine the top dead center. The reference numerals 10 and 11 identify connecting lines between the sensor 1 and an evaluation electronics 3. Reference numerals 5 and 6 identify the connections of the inductive sensor 1. The connecting lines 10 and 11 lead via two resistors R4 and R5 to a downstream evaluation electronics 3, which is operated with a supply voltage Vsupply. The evaluation electronics 3 essentially consist of a comparator 9, at the output of which a digital output signal Vout for processing the sensor output signal in a subsequent, not shown provided control or regulating device is provided. Antiparallel diodes D1 and D2 are connected between the non-inverting (+) and inverting (-) input of the comparator 9, essentially for better detection of the zero crossings of the sensor output signal for its digitization. In addition, a capacitor C2 is connected between the two inputs of the comparator 9 and between each input (+, -) of the comparator 9 and ground reference potential there is a capacitor C1 or C3. The capacitors C1, C2, C3 in cooperation with the resistors R4 and R5 have a low-pass characteristic in order to suppress high-frequency components of the inductive sensor signal or interference.
Erfindungsgemäß besteht die Diagnoseeinrichtung aus der zwi- sehen die Verbindungsleitungen 10 und 11 des induktiven Sensors 1 geschalteten Reihenschaltung aus zwei Widerständen R2 und R3, deren Verbindungspunkt 8 über einen weiteren Widerstand Rl mit einer Referenzspannungsquelle Vref verbunden ist. An diesem Anschluß 8 ist die Diagnosespannung Vdiag ab- greifbar, die zur Diagnose von charakteristischen Fehlschlüssen der o.g. Art in einer Diskriminierungseinrichtung D auswertbar ist, wie nachstehend beschrieben wird. Zwischen Anschluß 8 und Massebezugspotential ist aus Gründen der elektromagnetischen Verträglichkeit zur Ausblendung hochfrequen- ter Störungen ein Kondensator C4 geschaltet.According to the invention, the diagnostic device consists of the series connection between the connecting lines 10 and 11 of the inductive sensor 1 and consists of two resistors R2 and R3, the connection point 8 of which is connected to a reference voltage source Vref via a further resistor R1. The diagnostic voltage Vdiag can be tapped off at this connection 8 and is used to diagnose characteristic incorrect conclusions of the above. Type can be evaluated in a discrimination facility D, as will be described below. For reasons of electromagnetic compatibility, a capacitor C4 is connected between terminal 8 and ground reference potential to suppress high-frequency interference.
Nachstehend wird die Funktionsweise der erfindungsgemäßen Diagnoseeinrichtung beschrieben.The functioning of the diagnostic device according to the invention is described below.
Der Spannungsteiler R2, R3 ist symmetrisch, d.h., R2 = R3, und im fehlerlosen Normalbetrieb, wenn keine Fehlschlüsse vorhanden sind, entspricht die Diagnosespannung Vdiag oder deren Mittelwert dem Wert der Referenzspannung Vref.The voltage divider R2, R3 is symmetrical, i.e., R2 = R3, and in normal normal operation, if there are no false conclusions, the diagnostic voltage Vdiag or its mean value corresponds to the value of the reference voltage Vref.
Die Versorgungsspannungsquelle Vsupply und die Referenzspannungsquelle Vref haben gemeinsames Massebezugspotential. Bei einem Kurzschluß zwischen einer der Verbindungsleitungen 10 oder 11 und der Versorgungsspannungsquelle Vsupply fließt zwischen Versorgungsspannungsquelle Vsupply und Referenzspannungsquelle Vref über die Widerstände Rl und die Parallelschaltung von R2 und R3 ein Ausgleichsstrom, der an allen Widerständen einen Spannungsabfall erzeugt. Die Diagnosespannung Vdiag am Verbindungspunkt 8 entspricht dann der Summe von Referenzspannung Vref und der am Widerstand Rl abfallenden Spannung V(R1) : Vdiag = Vref + V(R1) .The supply voltage source Vsupply and the reference voltage source Vref have common ground reference potential. In the event of a short circuit between one of the connecting lines 10 or 11 and the supply voltage source Vsupply, a compensating current flows between the supply voltage source Vsupply and the reference voltage source Vref via the resistors R1 and the parallel connection of R2 and R3, which produces a voltage drop across all resistors. The diagnostic voltage Vdiag at the connection point 8 then corresponds to the sum of the reference voltage Vref and the voltage V (R1) dropping across the resistor R1: Vdiag = Vref + V (R1).
Bei einem angenommenen Kurzschluß zwischen einer der Verbindungsleitungen 10 oder 11 und Massebezugspotential fließt ein Strom von der Referenzspannungsquelle Vref über Widerstand Rl und die Parallelschaltung von R2 und R3 zum Massebezugspoten- tial. Die Diagnosespannung Vdiag am Verbindungspunkt 8 ist dann um den Spannungsabfall V(R1) am Widerstand Rl kleiner als die Referenzspannung Vref: Vdiag = Vref - V(R1).In the event of an assumed short circuit between one of the connecting lines 10 or 11 and ground reference potential, a current flows from the reference voltage source Vref via resistor R1 and the parallel connection of R2 and R3 to the ground reference potential. The diagnostic voltage Vdiag at the connection point 8 is then smaller than the reference voltage Vref by the voltage drop V (R1) across the resistor R1: Vdiag = Vref - V (R1).
Im Betrieb bei rotierendem Geberelement 2 entsteht eine vom induktiven Sensor 1 erzeugte symmetrische Wechselspannung, die im fehlerfreien Fall die Diagnosespannung Vdiag am Verbindungspunkt 8 nicht verändert.During operation with the encoder element 2 rotating, a symmetrical alternating voltage is generated by the inductive sensor 1, which does not change the diagnostic voltage Vdiag at the connection point 8 in the fault-free case.
Falls eine der Verbindungsleitungen 10 oder 11 unterbrochen ist, wirkt sich die i.d.R. vorhandene Schirmleitung als kapazitive Ankopplung u.a. auch zu Massebezugspotential aus. Dabei wird die vom induktiven Sensor 1 erzeugte Wechselspannung stark unsymmetrisch und kann in der Diskriminierungseinrichtung D mit einer weiteren logischen Gatterschaltung ausgewer- tet oder nach Analog-Digital-Wandlung mittels eines Programms, beispielsweise in einem Microcontroller, zu einem Fehlersignal verarbeitet werden. If one of the connecting lines 10 or 11 is interrupted, the existing shield cable as capacitive coupling also to ground reference potential. The AC voltage generated by the inductive sensor 1 becomes highly asymmetrical and can be evaluated in the discrimination device D with a further logic gate circuit or, after analog-digital conversion, can be processed into an error signal by means of a program, for example in a microcontroller.

Claims

Patentansprüche claims
1. Diagnoseeinrichtung für einen induktiven Sensor (1), an dem ein Geberelement (2) vorbeibewegbar ist, insbesondere für einen in einem Kraftfahrzeug verwendeten Drehzahl- oder Positionsgeber zur Erkennung von Kurzschlüssen zur Versorgungsspannung (Vsupply) oder zum Massepotential oder von Unterbrechungen der Verbindungsleitungen (10, 11), über welche der Sensor (1) mit einer an einer Versorgungsspannung (Vsupply) liegenden Auswerteelektronik (3) für das Ausgangssignal des induktiven Sensors (1) verbunden ist, d a d u r c h g e k e n n z e i c h n e t ,1.Diagnostic device for an inductive sensor (1), on which an encoder element (2) can be moved, in particular for a speed or position encoder used in a motor vehicle to detect short circuits to the supply voltage (Vsupply) or to the ground potential or interruptions in the connecting lines ( 10, 11), via which the sensor (1) is connected to evaluation electronics (3) connected to a supply voltage (Vsupply) for the output signal of the inductive sensor (1), characterized in that
- daß zwischen die Verbindungsleitungen (10, 11) eine Reihen- Schaltung (7) aus zwei elektrischen Bauelementen (R2, R3) oder Bauelementkombinationen geschaltet ist,- That between the connecting lines (10, 11) a series circuit (7) made of two electrical components (R2, R3) or component combinations is connected,
- daß der Verbindungspunkt (8) der Bauelemente (R2, R3) oder Bauelementkombinationen über einen Widerstand (Rl) mit einer Referenzspannungsquelle (Vref) verbunden ist, - daß an dem Verbindungspunkt (8) eine im Fehlerfall von der Referenzspannung (Vref) abweichende Diagnosespannung (Vdiag) abgreifbar ist, und- That the connection point (8) of the components (R2, R3) or component combinations via a resistor (R1) is connected to a reference voltage source (Vref), - that at the connection point (8) a diagnostic voltage deviating from the reference voltage (Vref) in the event of an error (Vdiag) can be tapped, and
- daß eine Diskriminierungseinrichtung (D) vorgesehen ist, in welcher Fehlschlüsse durch Vergleich der Diagnosespannung (Vdiag) mit vorgegebenen Schwellwerten erkennbar und anzeigbar (L) sind.- That a discrimination device (D) is provided, in which false conclusions can be recognized and displayed (L) by comparing the diagnostic voltage (Vdiag) with predetermined threshold values.
2. Diagnoseeinrichtung nach Anspruch 1, dadurch gekennzeich- net, daß die Reihenschaltung (7) symmetrisch aufgebaut ist2. Diagnostic device according to claim 1, characterized in that the series circuit (7) is constructed symmetrically
(R2 = R3) , und daß im fehlerfreien Fall die Diagnosespannung (Vdiag) der Referenzspannung (Vref) entspricht. (R2 = R3), and that in the faultless case the diagnostic voltage (Vdiag) corresponds to the reference voltage (Vref).
3. Diagnoseeinrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Bauelemente der Reihenschaltung (7) zwei Widerstände (R2, R3) sind.3. Diagnostic device according to claim 1 or 2, characterized in that the components of the series circuit (7) are two resistors (R2, R3).
4. Diagnoseeinrichtung nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Versorgungsspannungsquelle (Vsupply) und die Referenzspannungsquelle (Vref) gemeinsames Massebezugspotential haben.4. Diagnostic device according to one of claims 1 to 3, characterized in that the supply voltage source (Vsupply) and the reference voltage source (Vref) have common ground reference potential.
5. Diagnoseeinrichtung nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Diagnosespannung (Vdiag) bei einem Kurzschluß zwischen einer Verbindungsleitung (10, 11) und der Versorgungsspannungsquelle (Vsupply) einen Wert5. Diagnostic device according to one of claims 1 to 4, characterized in that the diagnostic voltage (Vdiag) in the event of a short circuit between a connecting line (10, 11) and the supply voltage source (Vsupply) a value
Vref + V(R1) und bei einem Kurzschluß zwischen einer Verbindungsleitung (10, 11) und dem Massebezugspotential einen Wert Vref - V(R1) annimmt.Vref + V (R1) and assumes a value Vref - V (R1) in the event of a short circuit between a connecting line (10, 11) and the ground reference potential.
6. Diagnoseeinrichtung nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß bei einer Unterbrechung einer Verbindungsleitung (10, 11) der bei bewegtem Geberelement (2) vom induktiven Sensor 1 erzeugte Wechselspannungsanteil der Diagnosespannung (Vdiag) unsymmetrisch ist.6. Diagnostic device according to one of claims 1 to 5, characterized in that in the event of an interruption in a connecting line (10, 11), the AC voltage component of the diagnostic voltage (Vdiag) generated by the inductive sensor 1 when the encoder element (2) moves is asymmetrical.
7. Diagnoseeinrichtung nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß Fehlschlüsse durch Auswertung der Diagnosespannung (Vdiag) in der Diskriminierungseinrichtung7. Diagnostic device according to one of claims 1 to 6, characterized in that false conclusions by evaluating the diagnostic voltage (Vdiag) in the discrimination device
(D) mittels eines Programms erkennbar und anzeigbar (L) sind. (D) are recognizable and displayable by means of a program (L).
PCT/DE1998/001836 1997-07-02 1998-07-02 Diagnostic device for detecting errors in an induction sensor WO1999001774A1 (en)

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DE19728256.3 1997-07-02

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US10377360B1 (en) 2018-07-04 2019-08-13 Nxp Usa, Inc. Resistive short circuit immunity for wheel speed sensor interface on braking system
EP3590776A1 (en) * 2018-07-04 2020-01-08 NXP USA, Inc. Resistive short circuit immunity for wheel speed sensor interface on braking system
CN110687312A (en) * 2018-07-04 2020-01-14 恩智浦美国有限公司 Resistive short circuit immunity of wheel speed sensor interface on a braking system
CN110687312B (en) * 2018-07-04 2024-06-11 恩智浦美国有限公司 Method and system for detecting and responding to resistive shorts of wheel speed sensors
DE102018132775A1 (en) * 2018-12-19 2020-06-25 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Circuit device for a vehicle and method for operating a circuit device
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CN114152777A (en) * 2021-11-19 2022-03-08 中国北方发动机研究所(天津) Circuit for testing and automatically detecting magnetoelectric rotation speed sensor

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