WO2023037154A1 - Rotational sensor - Google Patents

Rotational sensor Download PDF

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Publication number
WO2023037154A1
WO2023037154A1 PCT/IB2021/058365 IB2021058365W WO2023037154A1 WO 2023037154 A1 WO2023037154 A1 WO 2023037154A1 IB 2021058365 W IB2021058365 W IB 2021058365W WO 2023037154 A1 WO2023037154 A1 WO 2023037154A1
Authority
WO
WIPO (PCT)
Prior art keywords
arrangement
stator coil
target
rotor
coils
Prior art date
Application number
PCT/IB2021/058365
Other languages
French (fr)
Inventor
Sina FELLA
Jorge Miguel NUNES DOS SANTOS CABRAL
Luís Alexandre MACHADO DA ROCHA
José António AZEVEDO GONÇALVES
Débora Cláudia SIMÕES PEREIRA
Carlos Daniel ARAÚJO FERREIRA
Original Assignee
Bosch Car Multimedia Portugal, S.A.
Universidade Do Minho
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 Bosch Car Multimedia Portugal, S.A., Universidade Do Minho filed Critical Bosch Car Multimedia Portugal, S.A.
Publication of WO2023037154A1 publication Critical patent/WO2023037154A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/22—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature differentially influencing two coils
    • G01D5/2208—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature differentially influencing two coils by influencing the self-induction of the coils
    • G01D5/2225—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature differentially influencing two coils by influencing the self-induction of the coils by a movable non-ferromagnetic conductive element

Definitions

  • the present application describes a rotational sensor that , due to its technical characteristics , features robustness against external disturbances .
  • the measuring signal is a frequency change of a resonant circuit (LC oscillator ) , whose measuring coil faces an electrically conductive target .
  • the electrically conductive target possesses several wings , meaning that the area covering the measuring coil with respect to the electrically conductive track changes periodically when the target rotates .
  • the measuring coil induces eddy currents in the conductive target , which, vice versa, leads to an inductance change of the measuring coil .
  • the coils can be planar coils , printed in one or more layers on a Printed Circuit Board .
  • each coil typically consists of two parts which face each other with respect to a plane passing through the rotational axis of the target .
  • Such sensors can be found, for example , in document WO2016055348A1 which discloses a sensor arrangement for the contactless sensing of angles of rotation on a rotating part , said rotating part being coupled to a disk-shaped target which includes at least one metal area and generates , in combination with a coil arrangement comprising at least one flat detection coil , at least one piece of information to determine the current angle of rotation of the rotating part .
  • the present invention describes a rotational sensor comprising a stator comprised of two rows of stator coi ls , an outer coil stator arrangement and an inner stator coil arrangement , both rows of stator coils radially disposed in a circular arrangement ; wherein an output di f ferential signal is obtained between the outer stator coil arrangement and the inner stator coil arrangement .
  • the rotational sensor comprises a rotor comprised of two rows of target rotors radially disposed in a circular arrangement over the two stator coils .
  • the outer stator coil arrangement comprises at least two coils and the inner stator coil arrangement comprises at least two coils .
  • the two rows of target rotors comprise an outer target rotor arrangement and inner target rotor arrangement .
  • the outer target rotor arrangement comprises at least one rotor target and the inner target rotor arrangement comprises at least one rotor target .
  • the inner stator coil arrangement outer diameter is smaller than the outer stator coil arrangement inner diameter .
  • the inner target rotor arrangement outer diameter is smaller than the outer target rotor arrangement inner diameter .
  • each coil of the outer stator coil arrangement and each coil of the inner stator coil arrangement comprises a central core , each of said central core being perfectly aligned .
  • each rotor target of the inner target rotor arrangement and the outer target rotor arrangement comprises a central core , each of said central core being mi saligned within a 45-degree angle
  • each coil of the outer stator coil arrangement and each coil of the inner stator coil arrangement comprises a central core , each of said central core being misaligned within a 45-degree angle .
  • each rotor target of the inner target rotor arrangement and the outer target rotor arrangement comprises a central core , each of said central core being perfectly aligned .
  • the coils of the inner stator coil arrangement placed in opposite sides of the circular arrangement are connected in series
  • the coils of the outer stator coil arrangement placed in opposite sides of the circular arrangement are connected in series .
  • the rotational sensor comprises a circuit arrangement , comprised of a microprocessor, an outer stator coil digital oscil lator and an inner stator coil digital oscillator, wherein the outer stator coil digital oscillator is connected to the outer stator coil arrangement and configured to output an outer stator coil output frequency; the inner stator coil digital oscillator is connected to the inner stator coil arrangement and configured to output an inner stator coil output frequency; and the microprocessor is configured to output a di f ferential frequency signal resulting from the subtraction of the inner stator coil frequency to the outer stator coil frequency .
  • the rotational sensor comprises a f lip- flop circuit configured to produce the di f ferential frequency, the outer stator coil output frequency is connected to one input of the flip- flop, and the inner stator coil output frequency is connected to another input of the flip- flop .
  • the present application describes a rotational sensor .
  • present disclosed arrangement aims to obtain a more robust rotor positioning sensor, which provides and ensures high robustness against external disturbances.
  • present invention allows to improve the overall robustness of the sensor against mechanical tolerances along the rotation axis, improve the robustness of the sensor against temperature variations, and also improve the robustness of the sensor with regard to the electromagnetic compatibility (EMC) .
  • EMC electromagnetic compatibility
  • Present invention proposes a coil layout with two design variants that produce similar results.
  • both coil sets, the internal (with smaller diameter) and the external (with higher diameter) are aligned one with each other, but the target (set of rotors) possesses two segments with different diameters, and which are misaligned in terms of angle, being rotated against each other (out of phase or lagged) along the rotational axis of the target.
  • the set of coils of the stator (internal and external) is misaligned with regard to their windings central core, being slightly rotated with regard to each other (out of phase or lagged) along the rotational axis of the target, but the target (rotor) can be made by two aligned segments along a radial direction of the sensor.
  • differential frequencies of inner and outer coils can be obtained, which can be assigned to a specific rotation angle.
  • the differential frequency can be used to determine the correct angular position of the sensor.
  • the difference of their inductances and frequencies gets maximal.
  • the shape of the output signal can be tuned very effectively to get sinusoidal (or nearly sinusoidal) shapes.
  • These (nearly) sinusoidal signals can be used to calculate a quasi-linear relationship between the actual rotational angle and the measured signal via the ATAN function.
  • a quasi-sinusoidal signal can be reached with very low content of higher harmonics.
  • the harmonics remain almost constant, meaning that the sensor is very robust against these mechanical tolerances;
  • the differential signal stays almost constant over a large temperature range.
  • the sensor can be used in temperature ranges typical for automotive applications comprising values between -40°C and 125°C; - Assuming the proposed design where all coils have separated frequencies (for example, by connecting the coils to different capacities inside the LC-oscillators ) : for external disturbances due to injection locking or pulling which affects one frequency and thus one coil, the other coils are unaffected. Thus, the error is reduced by building the differential frequency.
  • Further preferred designs can include differential frequencies of two coils built via an electric circuit using a D-type flip-flop. This has the advantage that the flipflop' s Q output frequency is lower, meaning that the requirements to the frequency-analysing element
  • Fig. 1 - illustrates an embodiment of present invention disclosure wherein:
  • 20 - rotational / positioning sensor comprising two rows of stator coils and two rows of target rotors
  • the core of the outer rotor (206) is misaligned with the core of the inner rotor (207) in a 45- degree deviation with regard to the central core of the overall sensor.
  • FIG. 2 - illustrates another possible embodiment for present invention disclosure wherein:
  • 20 - rotational / positioning sensor comprising two rows of stator coils and two rows of target rotors
  • the core of the outer coil (201) is misaligned with the core of the inner coil (202) in a 45- degree deviation with regard to the central core of the overall sensor.
  • always two opposing inner coils (202) are connected in series, as well as two opposing outer coils (201) .
  • Fig. 3 - illustrates the output signal provided by the stator coils, where the reference a) illustrates to the signals of the inner coil row (202) , reference b) illustrates the signals of the outer coil row (201) , and reference c) illustrates the differential signal between both coils (201, 202) .
  • Fig. 4 - illustrates a flip-flop circuit used for frequency mixing, between the inner the inner stator coil arrangement (202) and outer stator coil arrangement (201) , giving out directly the differential output signal (305) between inner and outer coils by hardware subtraction.
  • the reference numbers refer to:
  • present invention discloses a rotational / positioning sensor (20) comprising a rotor (205) and a stator (200) , each stator (200) comprising two rows of stator coils, and each rotor (205) comprising two rows of rotor targets.
  • the stator comprises an outside coil row arrangement (201) , comprising a set of outer coils aligned within the same radius with regard to the center of the sensor, and an inside coil row arrangement (202) , comprising a set of inner coils aligned within the same radius with regard to the center of the sensor.
  • Both core rows are positioned within the rotational axis of the rotational target also with two different diameters / radius.
  • the smaller diameter (203) row, and radius is associated with the inside coil (202) row, and the wider diameter (204) row, and radius, is associated with the outside coil (201) coil.
  • each of the disposed coils arranged in the inner and outer coils arrangements (201, 202) comprises a central core, which is perfectly aligned, i.e., the central core of the outer coil (201) is aligned with the central core of the inner coil (202) in relation to the central axis of the stator.
  • the rotational target (205) comprises two sets of rotors with different diameters, an outside target rotor (206) with a wider radius / diameter, and an inside target rotor (207) with a smaller radius / diameter.
  • the rotational target (205) can be connected to a rotational metal part.
  • the inside row outer diameter fits the outside row inner diameter, the first being smaller than the second, in order to be provide an adequate distance between both without overlapping both inner and outer rows .
  • the central core of the outer row target (206) is misaligned with central core of the inner row target (207) within a 45-degree angle in relation to the central axis of the rotor.
  • the rotational / positioning sensor (20) comprises two rows of stator coils, an outside coil row (201) , comprising a set of outer coils aligned within the same radius with regard to the center of the sensor, and an inside coil row (202) , comprising a set of inner coils aligned within the same radius.
  • Both core rows (201, 202) are positioned within the rotational axis of the rotational target (205) also with two different diameters / radius .
  • the smaller diameter (203) row, and radius, is associated with the inside coil row (202) row, and the wider diameter (204) row, and radius, is associated with the outside coil (201) .
  • the coils (201, 202) central core is misaligned, i.e., the central core of the outer coil (201) is misaligned with the central core of the inner coil (202) within a 45-degree angle in relation to the central axis of the stator.
  • the rotational target (205) also comprises two sets of rotors with different diameters, an outside target rotor (206) with a wider radius / diameter, and an inside target rotor (207) with a smaller radius / diameter .
  • the central core of the outer row target (206) is perfectly aligned with the central core of inner row target (207) in relation to the central axis of the rotor.
  • the inside row outer diameter fits the outside row inner diameter, the first being smaller than the second, in order to be provide an adequate distance between both without overlapping both rows.
  • each digital oscillator circuit varies with the coil (201, 202) inductances.
  • the D-type flip-flop is used to subtract the frequencies (301, 302) of the two oscillator circuits (2011, 2021) , thus the flip-flop output (305) results in a square wave whose frequency equals the subtraction of the two digital oscillators frequencies (301, 302) .

Abstract

The present application describes a rotational sensor (20) that, due to its technical characteristics, features robustness against external disturbances.The proposed rotational sensor (20) is composed of a rotor (205) and a stator (200), the stator (200) being comprised of two rows of stator coils radially disposed in a circular arrangement, and the rotor (205), using a similar matching arrangement, is also characterized by comprising at least one row of target rotors radially disposed in a circular arrangement over the two stator coils.

Description

DESCRIPTION
"Rotational sensor"
Technical Field
The present application describes a rotational sensor that , due to its technical characteristics , features robustness against external disturbances .
Background art
Presently it is known the existence of angular sensors based on the eddy current principle . Usually, the measuring signal is a frequency change of a resonant circuit ( LC oscillator ) , whose measuring coil faces an electrically conductive target . The electrically conductive target possesses several wings , meaning that the area covering the measuring coil with respect to the electrically conductive track changes periodically when the target rotates . The measuring coil induces eddy currents in the conductive target , which, vice versa, leads to an inductance change of the measuring coil . The coils can be planar coils , printed in one or more layers on a Printed Circuit Board .
For reducing mechanical tolerances of sensor movements perpendicular to the rotational axis , and improving the EMC robustness , each coil typically consists of two parts which face each other with respect to a plane passing through the rotational axis of the target .
Such sensors can be found, for example , in document WO2016055348A1 which discloses a sensor arrangement for the contactless sensing of angles of rotation on a rotating part , said rotating part being coupled to a disk-shaped target which includes at least one metal area and generates , in combination with a coil arrangement comprising at least one flat detection coil , at least one piece of information to determine the current angle of rotation of the rotating part .
Summary
The present invention describes a rotational sensor comprising a stator comprised of two rows of stator coi ls , an outer coil stator arrangement and an inner stator coil arrangement , both rows of stator coils radially disposed in a circular arrangement ; wherein an output di f ferential signal is obtained between the outer stator coil arrangement and the inner stator coil arrangement .
In a proposed embodiment of present invention, the rotational sensor comprises a rotor comprised of two rows of target rotors radially disposed in a circular arrangement over the two stator coils .
Yet in another proposed embodiment of present invention, the outer stator coil arrangement comprises at least two coils and the inner stator coil arrangement comprises at least two coils .
Yet in another proposed embodiment of present invention, the two rows of target rotors comprise an outer target rotor arrangement and inner target rotor arrangement .
Yet in another proposed embodiment of present invention, the outer target rotor arrangement comprises at least one rotor target and the inner target rotor arrangement comprises at least one rotor target . Yet in another proposed embodiment of present invention, the inner stator coil arrangement outer diameter is smaller than the outer stator coil arrangement inner diameter .
Yet in another proposed embodiment of present invention, the inner target rotor arrangement outer diameter is smaller than the outer target rotor arrangement inner diameter .
Yet in another proposed embodiment of present invention, each coil of the outer stator coil arrangement and each coil of the inner stator coil arrangement comprises a central core , each of said central core being perfectly aligned .
Yet in another proposed embodiment of present invention, each rotor target of the inner target rotor arrangement and the outer target rotor arrangement comprises a central core , each of said central core being mi saligned within a 45-degree angle
Yet in another proposed embodiment of present invention, each coil of the outer stator coil arrangement and each coil of the inner stator coil arrangement comprises a central core , each of said central core being misaligned within a 45-degree angle .
Yet in another proposed embodiment of present invention, each rotor target of the inner target rotor arrangement and the outer target rotor arrangement comprises a central core , each of said central core being perfectly aligned .
Yet in another proposed embodiment of present invention, the coils of the inner stator coil arrangement placed in opposite sides of the circular arrangement are connected in series , and the coils of the outer stator coil arrangement placed in opposite sides of the circular arrangement are connected in series .
Yet in another proposed embodiment of present invention, the rotational sensor comprises a circuit arrangement , comprised of a microprocessor, an outer stator coil digital oscil lator and an inner stator coil digital oscillator, wherein the outer stator coil digital oscillator is connected to the outer stator coil arrangement and configured to output an outer stator coil output frequency; the inner stator coil digital oscillator is connected to the inner stator coil arrangement and configured to output an inner stator coil output frequency; and the microprocessor is configured to output a di f ferential frequency signal resulting from the subtraction of the inner stator coil frequency to the outer stator coil frequency .
Yet in another proposed embodiment of present invention, the rotational sensor comprises a f lip- flop circuit configured to produce the di f ferential frequency, the outer stator coil output frequency is connected to one input of the flip- flop, and the inner stator coil output frequency is connected to another input of the flip- flop .
General Description
The present application describes a rotational sensor .
Current state-of-the-art angular sensors are based on one "row" of coils , defining the stator, which are placed at a certain diameter around the rotational axis of the target . On the proposed design of current disclosure, a set of two "rows" of coils, or stators, are placed at two different diameters around the rotational axis of the target.
With regard to previous known technologies, present disclosed arrangement aims to obtain a more robust rotor positioning sensor, which provides and ensures high robustness against external disturbances. With regard to known technologies, present invention allows to improve the overall robustness of the sensor against mechanical tolerances along the rotation axis, improve the robustness of the sensor against temperature variations, and also improve the robustness of the sensor with regard to the electromagnetic compatibility (EMC) .
Present invention proposes a coil layout with two design variants that produce similar results.
In one of the possible embodiments, both coil sets, the internal (with smaller diameter) and the external (with higher diameter) are aligned one with each other, but the target (set of rotors) possesses two segments with different diameters, and which are misaligned in terms of angle, being rotated against each other (out of phase or lagged) along the rotational axis of the target.
In the second possible embodiment of the proposed sensor, the set of coils of the stator (internal and external) is misaligned with regard to their windings central core, being slightly rotated with regard to each other (out of phase or lagged) along the rotational axis of the target, but the target (rotor) can be made by two aligned segments along a radial direction of the sensor. In both cases, differential frequencies of inner and outer coils can be obtained, which can be assigned to a specific rotation angle. Thus, the differential frequency can be used to determine the correct angular position of the sensor.
There are further preferred designs, when pairs of coils from different diameters can comprise the following behaviour: for maximum target coverage of one coil (i.e. lowest inductance = highest frequency) , the other coil is covered minimal (i.e. highest inductance = lowest frequency) . Thus, the difference of their inductances and frequencies gets maximal. In this case, the shape of the output signal can be tuned very effectively to get sinusoidal (or nearly sinusoidal) shapes. These (nearly) sinusoidal signals can be used to calculate a quasi-linear relationship between the actual rotational angle and the measured signal via the ATAN function.
The proposed design has the following advantages:
- A quasi-sinusoidal signal can be reached with very low content of higher harmonics. Moreover, when changing the distance between sensor (stator coils) and target (rotor) , the harmonics remain almost constant, meaning that the sensor is very robust against these mechanical tolerances;
- Temperature fluctuations and variations strongly affect the frequency behaviour of the individual stator coils, mainly due to the temperature dependence of electric components within the LC oscillator circuit. However, with the proposed sensor layout, the differential signal stays almost constant over a large temperature range. Thus, the sensor can be used in temperature ranges typical for automotive applications comprising values between -40°C and 125°C; - Assuming the proposed design where all coils have separated frequencies (for example, by connecting the coils to different capacities inside the LC-oscillators ) : for external disturbances due to injection locking or pulling which affects one frequency and thus one coil, the other coils are unaffected. Thus, the error is reduced by building the differential frequency.
Further preferred designs can include differential frequencies of two coils built via an electric circuit using a D-type flip-flop. This has the advantage that the flipflop' s Q output frequency is lower, meaning that the requirements to the frequency-analysing element
(microcontroller) are minimized.
Brief description of the drawings
For better understanding of the present application, figures representing preferred embodiments are herein attached which, however, are not intended to limit the technique disclosed herein.
Fig. 1 - illustrates an embodiment of present invention disclosure wherein:
20 - rotational / positioning sensor comprising two rows of stator coils and two rows of target rotors;
200 - stator coils;
201 - outside / outer stator coil arrangement;
202 - inside / inner stator coil arrangement;
203 - inner diameter / distance between the cores of inner coils;
204 - outer diameter / distance between the cores of the outer coils; 205 - rotational target / rotor;
206 - outer / outside target rotor arrangement;
207 - inner / inside target rotor arrangement.
In this embodiment, the core of the outer rotor (206) is misaligned with the core of the inner rotor (207) in a 45- degree deviation with regard to the central core of the overall sensor.
Fig. 2 - illustrates another possible embodiment for present invention disclosure wherein:
20 - rotational / positioning sensor comprising two rows of stator coils and two rows of target rotors;
200 - stator coils;
201 - outside / outer stator coil arrangement;
202 - inside / inner stator coil arrangement;
203 - inner diameter / distance between the cores of inner coils;
204 - outer diameter / distance between the cores of the outer coils;
205 - rotational target / rotor;
206 - outer / outside target rotor arrangement;
207 - inner / inside target rotor arrangement.
In this embodiment, the core of the outer coil (201) is misaligned with the core of the inner coil (202) in a 45- degree deviation with regard to the central core of the overall sensor. Always two opposing inner coils (202) are connected in series, as well as two opposing outer coils (201) .
Fig. 3 - illustrates the output signal provided by the stator coils, where the reference a) illustrates to the signals of the inner coil row (202) , reference b) illustrates the signals of the outer coil row (201) , and reference c) illustrates the differential signal between both coils (201, 202) .
Fig. 4 - illustrates a flip-flop circuit used for frequency mixing, between the inner the inner stator coil arrangement (202) and outer stator coil arrangement (201) , giving out directly the differential output signal (305) between inner and outer coils by hardware subtraction. The reference numbers refer to:
201 - outer stator coil arrangement;
2011 - outer stator coil digital oscillator;
202 - inner stator coil arrangement;
2021 - inner stator coil digital oscillator;
210 - D-type flip-flop;
301 - outer stator coil output frequency;
302 - inner stator coil output frequency;
303 - 1/ (outer coil output frequency) ;
305 - resulting output frequency, obtained subtracting the inner stator coil frequency (302) to the outer stator coil frequency (301) .
In the same Figure 4, it is also represented the resulting signal waveform (305) , based on the input waveforms (301, 302) . This suggested embodiment, you can resort to the use of a microprocessor properly configured for the purpose as an alternative to the flip-flop.
Description of Embodiments
With reference to the figures, some embodiments are now described in more detail, which are however not intended to limit the scope of the present application. With support on Figure 1, present invention discloses a rotational / positioning sensor (20) comprising a rotor (205) and a stator (200) , each stator (200) comprising two rows of stator coils, and each rotor (205) comprising two rows of rotor targets. The stator comprises an outside coil row arrangement (201) , comprising a set of outer coils aligned within the same radius with regard to the center of the sensor, and an inside coil row arrangement (202) , comprising a set of inner coils aligned within the same radius with regard to the center of the sensor.
Both core rows are positioned within the rotational axis of the rotational target also with two different diameters / radius. The smaller diameter (203) row, and radius, is associated with the inside coil (202) row, and the wider diameter (204) row, and radius, is associated with the outside coil (201) coil.
In this proposed embodiment, each of the disposed coils arranged in the inner and outer coils arrangements (201, 202) comprises a central core, which is perfectly aligned, i.e., the central core of the outer coil (201) is aligned with the central core of the inner coil (202) in relation to the central axis of the stator.
Maintaining the same line of thought, the rotational target (205) comprises two sets of rotors with different diameters, an outside target rotor (206) with a wider radius / diameter, and an inside target rotor (207) with a smaller radius / diameter. In a possible embodiment of the current invention, the rotational target (205) can be connected to a rotational metal part. To be noted that in both stator / rotor apparatus, the inside row outer diameter fits the outside row inner diameter, the first being smaller than the second, in order to be provide an adequate distance between both without overlapping both inner and outer rows .
Still with regard to the rotational target (205) , it should be noted that the central core of the outer row target (206) is misaligned with central core of the inner row target (207) within a 45-degree angle in relation to the central axis of the rotor.
With support on Figure 2, another possible embodiment for present invention is disclosed, wherein the rotational / positioning sensor (20) comprises two rows of stator coils, an outside coil row (201) , comprising a set of outer coils aligned within the same radius with regard to the center of the sensor, and an inside coil row (202) , comprising a set of inner coils aligned within the same radius. Both core rows (201, 202) are positioned within the rotational axis of the rotational target (205) also with two different diameters / radius .
The smaller diameter (203) row, and radius, is associated with the inside coil row (202) row, and the wider diameter (204) row, and radius, is associated with the outside coil (201) .
In the proposed embodiment of present figure, the coils (201, 202) central core is misaligned, i.e., the central core of the outer coil (201) is misaligned with the central core of the inner coil (202) within a 45-degree angle in relation to the central axis of the stator.
In this embodiment, the rotational target (205) also comprises two sets of rotors with different diameters, an outside target rotor (206) with a wider radius / diameter, and an inside target rotor (207) with a smaller radius / diameter .
The central core of the outer row target (206) is perfectly aligned with the central core of inner row target (207) in relation to the central axis of the rotor.
As in previous embodiment, in both stator / rotor apparatus, the inside row outer diameter fits the outside row inner diameter, the first being smaller than the second, in order to be provide an adequate distance between both without overlapping both rows.
With regard to Figure 3, in particular in the a) representation, it is illustrated the signals of the inner coil row, being visible the effect that the mismatch in the coil cores alignment introduces in the graphic deviation. In the b) representation, it is illustrated the signals of the outer coil row, and in the c) representation, it is illustrated the differential signal between coils.
With regard to Figure 4, the output frequency (301, 302) of each digital oscillator circuit (2011, 2021) varies with the coil (201, 202) inductances. There are two digital oscillators (2011, 2021) in the proposed circuit, one (2021) connected to an inner stator coil (202) and the other (2011) to an outer stator coil (201) . Therefore, for each set of inner stator coil (202) and outer stator coil (201) , a circuit arrangement like the one depicted is needed. For the particular case of the sensor described in Figure 1, it will require six oscillators and three flip-flops
The D-type flip-flop is used to subtract the frequencies (301, 302) of the two oscillator circuits (2011, 2021) , thus the flip-flop output (305) results in a square wave whose frequency equals the subtraction of the two digital oscillators frequencies (301, 302) .

Claims

1. Rotational sensor (20) comprising a stator (200) comprised of two rows of stator coils, an outer coil stator arrangement (201) and an inner stator coil arrangement (202) , both rows of stator coils radially disposed in a circular arrangement; wherein an output differential signal (305) is obtained between the outer stator coil arrangement (201) and the inner stator coil arrangement (202) .
2. Rotational sensor (20) according to the previous claim, comprising a rotor (205) comprised of two rows of target rotors radially disposed in a circular arrangement over the two stator coils.
3. Rotational sensor (20) according to any of the previous claims, wherein the outer stator coil arrangement (201) comprises at least two coils and the inner stator coil arrangement (202) comprises at least two coils.
4. Rotational sensor (20) according to any of the previous claims, wherein the two rows of target rotors comprise an outer target rotor arrangement (206) and inner target rotor arrangement (207) .
5. Rotational sensor (20) according to any of the previous claims, wherein the outer target rotor arrangement (206) comprises at least one rotor target and the inner target rotor arrangement (207) comprises at least one rotor target.
6. Rotational sensor (20) according to any of the previous claims, wherein the inner stator coil arrangement (202) outer diameter is smaller than the outer stator coil arrangement (201) inner diameter.
7. Rotational sensor (20) according to any of the previous claims, wherein the inner target rotor arrangement (207) outer diameter is smaller than the outer target rotor arrangement (206) inner diameter.
8. Rotational sensor (20) according to any of the previous claims, wherein each coil of the outer stator coil arrangement (201) and each coil of the inner stator coil arrangement (202) comprises a central core, each of said central core being perfectly aligned.
9. Rotational sensor (20) according to any of the previous claims, wherein each rotor target of the inner target rotor arrangement (207) and the outer target rotor arrangement (206) comprises a central core, each of said central core being misaligned within a 45-degree angle.
10. Rotational sensor (20) according to any of the previous claims, wherein each coil of the outer stator coil arrangement (201) and each coil of the inner stator coil arrangement (202) comprises a central core, each of said central core being misaligned within a 45-degree angle.
11. Rotational sensor (20) according to any of the previous claims, wherein each rotor target of the inner target rotor arrangement (207) and the outer target rotor arrangement (206) comprises a central core, each of said central core being perfectly aligned. 16
12. Rotational sensor (20) according to any of the previous claims, wherein the coils of the inner stator coil arrangement (202) placed in opposite sides of the circular arrangement are connected in series, and the coils of the outer stator coil arrangement (201) placed in opposite sides of the circular arrangement are connected in series.
13. Rotational sensor (20) according to any of the previous claims, comprising a circuit arrangement, comprised of a microprocessor, an outer stator coil digital oscillator (2011) and an inner stator coil digital oscillator (2021) , wherein the outer stator coil digital oscillator (2011) is connected to the outer stator coil arrangement (201) and configured to output an outer stator coil output frequency (301) ; the inner stator coil digital oscillator (2021) is connected to the inner stator coil arrangement (202) and configured to output an inner stator coil output frequency (302) ; and the microprocessor is configured to output a differential frequency signal (305) resulting from the subtraction of the inner stator coil frequency (302) to the outer stator coil frequency (301) .
14. Rotational sensor (20) according to any of the previous claims, comprising a flip-flop (210) circuit configured to produce the differential frequency, the outer stator coil output frequency (301) is connected to one input of the flip- 17 flop (210) , and the inner stator coil output frequency (302) is connected to another input of the flip-flop (210) .
PCT/IB2021/058365 2021-09-10 2021-09-14 Rotational sensor WO2023037154A1 (en)

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Citations (5)

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US20050253576A1 (en) * 2004-05-17 2005-11-17 Nyce David S Simplified inductive position sensor and circuit configuration
US20140203800A1 (en) * 2013-01-18 2014-07-24 Mitutoyo Corporation Inductive detection type rotary encoder
WO2016055348A1 (en) 2014-10-09 2016-04-14 Robert Bosch Gmbh Sensor arrangement for the contactless sensing of angles of rotation on a rotating part
US20170292857A1 (en) * 2014-10-09 2017-10-12 Robert Bosch Gmbh Sensor Arrangement for the Contactless Sensing of Angles of Rotation on a Rotating Part
US20190170539A1 (en) * 2016-06-28 2019-06-06 Zettlex (Uk) Limited Inductive position detector

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050253576A1 (en) * 2004-05-17 2005-11-17 Nyce David S Simplified inductive position sensor and circuit configuration
US20140203800A1 (en) * 2013-01-18 2014-07-24 Mitutoyo Corporation Inductive detection type rotary encoder
WO2016055348A1 (en) 2014-10-09 2016-04-14 Robert Bosch Gmbh Sensor arrangement for the contactless sensing of angles of rotation on a rotating part
US20170292857A1 (en) * 2014-10-09 2017-10-12 Robert Bosch Gmbh Sensor Arrangement for the Contactless Sensing of Angles of Rotation on a Rotating Part
US20190170539A1 (en) * 2016-06-28 2019-06-06 Zettlex (Uk) Limited Inductive position detector

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