WO1987006348A1 - Detecteur de vitesse avec compensation de derive - Google Patents

Detecteur de vitesse avec compensation de derive Download PDF

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Publication number
WO1987006348A1
WO1987006348A1 PCT/US1986/001331 US8601331W WO8706348A1 WO 1987006348 A1 WO1987006348 A1 WO 1987006348A1 US 8601331 W US8601331 W US 8601331W WO 8706348 A1 WO8706348 A1 WO 8706348A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
output
input
comparator
pass filter
Prior art date
Application number
PCT/US1986/001331
Other languages
English (en)
Inventor
Bernard L. Luebbering
Stephen W. Rector
Original Assignee
Caterpillar Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Caterpillar Inc. filed Critical Caterpillar Inc.
Publication of WO1987006348A1 publication Critical patent/WO1987006348A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P1/00—Details of instruments
    • G01P1/006—Details of instruments used for thermal compensation
    • 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
    • G01P3/487—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 rotating magnets

Definitions

  • This invention relates generally to a variable threshold switching circuit, and more particularly, to the incorporation of the circuit with a Hall effect sensor for use as a speed sensor.
  • Zero crossing detectors are well-known in the art and are used, for example, to synchronize digital circuits to a sinusoidal input signal.
  • the input signal and reference signal will drift due to aging components, changes in temperature or humidity, and current leakage of the components. The result of drifting is a distorted and inaccurate output.
  • automatic drift correction circuits have been developed.
  • Some designers have resorted to great complexity in an effort to correct drift. Usually this results in high cost and large circuit size.
  • Zero crossing detectors employ simpler circuits. These designs do not eliminate drift of the input, reference, or output signals. Instead, they decrease drift by a moderate factor over a conventional detector. For example, a zero crossing detector, described in U.S. Patent No. 4,345,169 published August 17, 1982 by Saleh, gives a 2:1 improvement over conventional detectors. This is due to the circuit's comparison method. Instead of comparing the input signal with a reference level, it compares the input signal with its inverse; thus, the circuit obtains twice the resolution.
  • the present invention is directed to over- coming one or more of the problems as set forth above.
  • an apparatus which detects the velocity of a rotatable gear.
  • the apparatus includes a Hall effect device disposed adjacent the rotatable gear and adapted to deliver an analog AC signal having a frequency correlative to the velocity of the rotatable gear.
  • a means receives the AC signal and delivers a signal which has a magnitude correlative to the DC component of the AC signal.
  • the AC and DC signals are compared by an additional means which delivers a digital signal having a frequency correlative to the velocity of the rotatable gear.
  • Fig. 1 shows a block diagram type schematic of the functional structure of the tracking threshold switching circuit
  • Fig. 2 shows a detailed schematic of the preferred embodiment of the tracking threshold switching circuit
  • Fig. 3A shows drift of the input to a conventional zero crossing detector and its associated output
  • Fig. 3B shows drift of the input to the tracking threshold switching circuit and its associated output.
  • Fig. 1 illustrates a tracking threshold switching circuit 11 which is comprised of a signal source 12, an amplifier 14, a low pass filter 16, a signal comparator 18, and an output stage 20.
  • the signal source 12 senses a change in flux density between the gear 22 and a magnet (not shown) , as the gear teeth 21 of the gear 22 pass the source 12.
  • the toothed gear 22 passes the sensing end of the source 12, which produces a sinusoidal signal, one period per tooth, on a line 24.
  • the output of the signal source 12 delivers a sinusoidal output signal on a line 24 where the frequency of the signal is directly related to the rotational velocity of the gear 22.
  • This sinusoidal signal is the input to the amplifier 14 which intensifies the signal and delivers it to the comparator 18 on a line 26.
  • a means 27 also receives the AC signal from the amplifier 14 and delivers a signal which has a magnitude correlative to the DC component of the AC signal.
  • the means 27 includes the low pass filter 16 connected to the output of the amplifier 14 via a line 28.
  • the low pass filter 16 isolates the DC component of the sinusoidal signal and delivers it to a means 29 which compares the AC and DC signals and delivers a digital signal which has a frequency correlative to the velocity of the rotatable gear 22.
  • the means 29 includes the comparator 18 which compares the voltage from the amplifier 14 to its DC component.
  • a square wave of the same frequency as the input sinusoidal signal is produced and can be used by a digital logic circuit to determine the speed of the gear 22. Any of a wide variety of digital circuits may be employed and, for example, can be of the form which determine the duration between pulses, counts the number of pulses occurring within a preselected time duration, or determines the time duration for counting a preselected number of pulses. Selection of the particular digital circuit is left to the discretion of the designer as to which circuit best fits the intended application.
  • the square wave is delivered to an output stage 20 which tailors the voltage level and driving capability of the signal to the needs of the digital logic system (not shown) which will extract the gear speed information from the signal.
  • the output stage 20 delivers the signal over a line 32.
  • the signal source 12 is preferably a Hall effect device 34 biased by a magnet (not shown) , with a positive voltage input from "A", a ground input, and a pair of output lines 36,38.
  • the output lines 36,38 are connected to the amplifier 14 which is shown to be a differential amplifier 40.
  • the inverting input of the differential amplifier 40 is connected to line 36 via a resistor 42 and to its own output through a feedback resistor 44.
  • the noninverting input is connected to the line 38 through the resistor 46 and to ground through a resistor 48.
  • the output of the differential amplifier 40 is proportional to the difference between the voltages on the lines 36,38.
  • the low pass filter 16 is preferably a simple RC circuit and includes a resistor 52 connected between the output of differential amplifier 40 and the inverting input of the comparator 18 and a capacitor 54 connected between ground and the inverting input of the comparator 18.
  • the comparator 18 compares the voltage from the differential amplifier 40 to the DC value of that voltage. When the sinusoidal voltage at the noninverting input of the comparator 18 is greater than the output of the filter 16, the output of the comparator 18 is "high”. Similarly, when the noninverting input voltage is less than the output of the filter 16, the output of the comparator 18 is "low”.
  • a positve feedback resistor 56 interconnects the noninverting input and the output of the comparator 18, thus enhancing the switching times of the comparator 18.
  • the square wave produced by the comparator 18 is fed to the output driver 20 on the line 30.
  • the driver 20 includes a resistor 58 connected between the output of the comparator 18 and a base of a transistor 60.
  • a pair of serially connected diodes 62,64 interconnect the base of the transistor 60 to ground.
  • the transistor 60 has an emitter connected to ground via a resistor 66.
  • the diodes 62,64 produce a voltage drop across the resistor 66 and the base-emitter junction of transistor 60 equal to the voltage drop of the two diodes 62,64. Should the voltage drop across the resistor 66 rise above the voltage drop across one of the diodes 62,64, transistor 60 will be biased "off".
  • the resistor 66 and diodes 62,64 provide a current limiting circuit for short circuit protection.
  • the transistor 60 also has a collector connected to an output B and to system voltage A through a pull up resistor 68.
  • the output line B is normally "high” until such time as the output of the comparator 18 is sufficient to bias the transistor 60 "on”. With transistor 60 biased “on”, the output line B is pulled “low” through the resistor 66 to ground.
  • the tracking threshold switching circuit 11 proves to be particularly useful in environments subject to wide variations in operating temperatures and electrical noise.
  • An engine speed sensor constitutes one such application.
  • a Hall effect device 34 and biasing magnet are mounted adjacent a rotating gear 22. As the gear teeth 21 pass the Hall effect device 34, the flux density changes through the Hall cell 34 between the gear 22 and the magnet.
  • the Hall effect device 34 outputs a voltage, proportional to the product of the perpendicular component of the magnetic flux density and the current through the Hall cell 34, to a signal amplifier 14.
  • a detector receives the amplified voltage signal and compares it with a fixed reference voltage to detect zero crossings. However, the amplified signal tends to drift as illustrated in Fig. 3A.
  • a low pass filter 16 separates the DC component from the amplified voltage signal.
  • the DC component represents a variable reference voltage corresponding to the drift of the sinusoid as shown in Fig. 3B. Therefore, the comparator transmits an undistorted square wave signal since the threshold reference tracks the input signal.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)

Abstract

Un appareil (10) transforme un signal d'entrée sinusoïdal en un signal (numérique) d'ondes rectangulaires. A la différence des détecteurs de franchissement de zéro classique, le signal de sortie de l'appareil (10) n'est pas affecté par la dérive du signal d'entrée. Le signal d'entrée sinusoïdal est comparé avec sa propre valeur c.c. au lieu d'une tension de référence fixe. La composante c.c. du signal sinusoïdal extraite par un filtre passe-bas (16) est délivré à une entrée d'un comparateur (18) pour servir de zéro de référence variable. A mesure que la sinusoïde subit une dérive, sa tension de référence subit une dérive correspondante. En conséquence, le comparateur (18) produit un signal d'ondes rectangulaires non déformé d'une fréquence corrélative à la fréquence du signal sinusoïdal. L'appareil (10) se révèle particulièrement utile dans l'application du type détecteur de régime moteur, où on peut s'attendre à une large plage de température de fonctionnement.
PCT/US1986/001331 1986-04-10 1986-06-23 Detecteur de vitesse avec compensation de derive WO1987006348A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US85030486A 1986-04-10 1986-04-10
US850,304 1986-04-10

Publications (1)

Publication Number Publication Date
WO1987006348A1 true WO1987006348A1 (fr) 1987-10-22

Family

ID=25307772

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1986/001331 WO1987006348A1 (fr) 1986-04-10 1986-06-23 Detecteur de vitesse avec compensation de derive

Country Status (2)

Country Link
AU (1) AU6120586A (fr)
WO (1) WO1987006348A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2629536A1 (fr) * 1988-04-04 1989-10-06 Roulements Soc Nouvelle Roulement a capteur magnetique avec un circuit de detection autocompense
EP0440916A1 (fr) * 1990-01-29 1991-08-14 Knorr-Bremse Ag Circuit de traitement pour un capteur de vitesse d'une roue d'un véhicule
DE4133837A1 (de) * 1991-10-12 1993-04-15 Kostal Leopold Gmbh & Co Kg Sensoreinrichtung
US8624586B2 (en) 2008-10-10 2014-01-07 Continental Automotive France Hall effect measuring device
US9638548B2 (en) 2012-05-07 2017-05-02 Infineon Technologies Ag Output switching systems and methods for magnetic field sensors
US10102992B2 (en) 2014-02-25 2018-10-16 Infineon Technologies Ag Switching apparatus, switching system and switching method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01194844A (ja) * 1988-01-28 1989-08-04 Mitsubishi Electric Corp 速度発電機の保護装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1367279A (en) * 1972-04-28 1974-09-18 Cem Comp Electro Mec Detector apparatus
DE2722581A1 (de) * 1977-05-18 1978-11-23 Knorr Bremse Gmbh Schaltungsanordnung zur signalaufbereitung von ausgangssignalen eines feldplattengebers bei raddrehzahlgebern von fahrzeugen

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1367279A (en) * 1972-04-28 1974-09-18 Cem Comp Electro Mec Detector apparatus
DE2722581A1 (de) * 1977-05-18 1978-11-23 Knorr Bremse Gmbh Schaltungsanordnung zur signalaufbereitung von ausgangssignalen eines feldplattengebers bei raddrehzahlgebern von fahrzeugen

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2629536A1 (fr) * 1988-04-04 1989-10-06 Roulements Soc Nouvelle Roulement a capteur magnetique avec un circuit de detection autocompense
EP0337824A2 (fr) * 1988-04-04 1989-10-18 S.N.R. Roulements Roulement à capteur magnétique avec un circuit de détection autocompensé
EP0337824A3 (fr) * 1988-04-04 1989-11-02 S.N.R. Roulements Roulement à capteur magnétique avec un circuit de détection autocompensé
EP0440916A1 (fr) * 1990-01-29 1991-08-14 Knorr-Bremse Ag Circuit de traitement pour un capteur de vitesse d'une roue d'un véhicule
DE4133837A1 (de) * 1991-10-12 1993-04-15 Kostal Leopold Gmbh & Co Kg Sensoreinrichtung
US8624586B2 (en) 2008-10-10 2014-01-07 Continental Automotive France Hall effect measuring device
US9638548B2 (en) 2012-05-07 2017-05-02 Infineon Technologies Ag Output switching systems and methods for magnetic field sensors
US10102992B2 (en) 2014-02-25 2018-10-16 Infineon Technologies Ag Switching apparatus, switching system and switching method

Also Published As

Publication number Publication date
AU6120586A (en) 1987-11-09

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