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
  • G01D5/142—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 using Hall-effect devices
  • G01D5/145—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 using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F13/00—Apparatus or processes for magnetising or demagnetising
  • H01F13/003—Methods and devices for magnetising permanent magnets
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F7/00—Magnets
  • H01F7/02—Permanent magnets [PM]
  • H01F7/0205—Magnetic circuits with PM in general
  • H01F7/021—Construction of PM
• • 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
  • G01D2205/00—Indexing scheme relating to details of means for transferring or converting the output of a sensing member
  • G01D2205/80—Manufacturing details of magnetic targets for magnetic encoders

Definitions

• the invention relates to a sensor for determining a relative angular position of a first part with respect to a second part around an axis of rotation. It also relates to a method for determining a relative angular position, implementing such a sensor. It also relates to a method of manufacturing a magnetic body for a system for determining such a relative angular position.
• magnetic sensor systems are well known. They can be produced at relatively low cost, they are not subject to significant mechanical wear, and they are insensitive to moisture and non-magnetic dirt (dust, oil, etc.). Thanks to these advantages, magnetic sensor systems are often used in automotive applications.
• a magnetic angular position sensor system comprises at least one permanent magnet and magnetic field measurement elements, the sensor system being provided to measure the relative angular position of the measurement measurement element(s) with respect to the magnetic body , around the axis of rotation.
• the mechanism to be monitored comprises a first part and a second part which are rotatable with respect to each other.
• the magnetized body is made integral with the first part, or integrated into it, while the measuring elements are made integral with the second part of the mechanism, and the sensor system makes it possible to determine the relative angular position of the two parts of the mechanism .
• the invention is intended to solve problems related to the practical implementation of sensor systems, which are often intended to be integrated into a constrained space, with a limited available volume. More particularly, the invention is intended to solve the problems related to the presence of ferromagnetic parts or other sources of disturbance of the magnetic field near the sensor system, which can reduce the accuracy of the determination of the angular position.
• the document WO-2014/029885 describes a sensor system having a permanent magnet having an axial magnetization having at least two pairs of poles (north-south), with magnetic field measurement elements which are in a perpendicular plane. to the axis of rotation, axially opposite the magnet.
• the angular position of the magnet is obtained from the differences in magnetic field in the positions spaced by 180° magnetic, thus making it possible to overcome the external magnetic field.
• the disadvantage of this solution is the lack of robustness with respect to the assembly tolerances and the dynamic play of the mechanical parts, in particular due to the decrease in the magnetic field along the axial dimension.
• the object of the invention is therefore to propose a new design of a magnetic body and of a sensor system using such a magnetic body which make it possible to obtain an accurate and reliable determination of a relative angular position.
• This determination must be able to be very insensitive to the presence of an external magnetic field.
• This determination must present a good robustness vis-à-vis possible inaccuracies as to the relative position of the magnetic body and the measuring elements of the sensor system in the axial direction of the axis of rotation of the sensor system.
• the sensor system must be compact.
• the magnetic body and the sensor system must be able to be produced in large series under acceptable economic conditions for applications such as those envisaged in the field of motor vehicles.
• the invention relates to a sensor system for determining a relative angular position of a first part relative to a second part around an axis of rotation, the system comprising:
• a permanent magnet having a magnetized body having a magnetized body in the form of a symmetrical tubular section around a main axis of the magnetized body, the permanent magnet being:
• the magnetic body has a permanent magnetization such that, for any point of the magnetic body on a given circle around the main axis, each point of the magnetic body on this given circle having an angular position defined by the angle formed, around the main axis and with respect to a fixed reference axis of the permanent magnet, by a particular radial segment originating from the main axis and passing through this point, the magnetization vector at a given point of the circle presents, in projection orthogonal on a plane perpendicular to the main axis, a projected vector whose relative orientation with respect to the particular radial segment at this point is a continuously variable function according to a law of variation of relative orientation according to the angular position of the point of the magnetic body,
• the law of relative orientation variation of the magnetization vector implies a positive variation of the relative orientation of the projected vector, in orthogonal projection on a plane perpendicular to the main axis, of the magnetization vector at a point, with respect to the particular radial segment, depending on a positive variation of the angular position of the point of the magnetized body, the permanent magnet being arranged such that the main axis of the magnetized body coincides with the axis of rotation, arranged such that the main axis of the magnetized body coincides with the axis of rotation;
• a primary pair of measuring elements comprising a first primary measuring element making it possible to determine, at a first primary measuring point, a first primary component of the magnetic induction according to a primary measuring vector perpendicular to the axis of rotation , and comprising a second primary measurement element making it possible to determine, at a second primary measurement point, a second primary component of the magnetic induction according to the same primary measurement vector, the first primary measurement point and the second primary point of measurement being distinct points between them on the same primary diametral segment with respect to the axis of rotation and being located inside the internal volume delimited by the magnetized body, and the primary measurement vector forming, with respect to the diametral segment primary, a primary relative angle of measurement;
• a secondary pair of measuring elements comprising a first secondary measuring element making it possible to determine, at a first secondary measuring point, a first secondary component of the magnetic induction according to a secondary measuring vector perpendicular to the axis of rotation , and comprising a second secondary measurement element making it possible to determine, at a second secondary measurement point, a second secondary component of the magnetic induction according to the same secondary measurement vector, the first secondary measurement point and the second secondary point of measurement being distinct points between them on the same secondary diametral segment with respect to the axis of rotation and being located inside the internal volume delimited by the magnetized body, and the secondary measurement vector forming, with respect to the diametral segment secondary, a secondary relative angle of measurement;
• the system being arranged so that the sum of, on the one hand, the angular difference between the secondary relative angle of measurement and the relative primary angle of measurement, with on the other hand, the angular difference, multiplied by the number of periods of the law of relative orientation variation of the magnetization vector as a function of the angular position of the point of the magnetized body, between the secondary diametral segment and the primary diametral segment, is non-zero and different from a multiple of 180 degrees
• the sensor system comprising an electronic calculation unit programmed to calculate a value representative of the relative angular position of the first part with respect to the second part, on the basis of a calculation of the arc-tangent of a ratio between, on the one hand, a difference between the two primary components, and, on the other hand, a difference between the two secondary components, ratio in which each difference is weighted according to the distance, for the difference considered, between the corresponding measuring points and the axis of rotation.
• a sensor system according to the invention may further comprise one or more of the following optional features, taken alone or in combination.
• the sensor system is arranged so that the sum of, on the one hand, the difference between the secondary relative angle of measurement and the primary relative angle of measurement) with, of on the other hand, the angular difference, multiplied by the number of periods of the law of relative orientation variation of the magnetization vector as a function of the angular position of the point of the magnetized body, between the secondary diametral segment and the primary diametral segment is equal, modulo 360 degrees, to 90 degrees or to 270 degrees.
• the sensor system is arranged so that the secondary relative angle of measurement and the primary relative angle of measurement are equal, and the angular difference between the secondary diametral segment and the primary diametral segment is a quarter of an angular period of the law of variation of relative orientation of the magnetization vector, modulo the half angular period of the law of variation of relative orientation of the magnetization vector.
• the sensor system is arranged so that the primary diametral segment and the secondary diametral segment coincide and that the primary measurement vector and the secondary measurement vector are orthogonal.
• the first primary measurement point and the first secondary measurement point coincide.
• the second primary measurement point and the second secondary measurement point coincide.
• the first primary measurement point and the second primary measurement point are arranged at the same distance on each side of the axis of rotation.
• the first secondary measurement point and the second secondary measurement point are arranged at the same distance on each side of the axis of rotation.
• first primary measurement point and the second primary measurement point are arranged at the same first distance from the axis of rotation, and the first secondary measurement point and the second secondary measurement point are arranged at the same first distance from the axis of rotation.
• the two measurement points of the primary torque and/or of the secondary torque of measurement elements are arranged in the same plane perpendicular to the axis of rotation.
• the two measurement points of the primary torque and/or of the secondary torque of measurement elements are arranged in the same plane perpendicular to the axis of rotation which is equidistant from the axial ends of the magnetic body. .
• the magnetized body has a flat magnetization such that, at any point of the magnetized body, the magnetization vector at this point is parallel to a magnetization plane perpendicular to the main axis.
• the law of variation of relative orientation of the magnetization vector is a bijective law over an angular period of the law of variation of relative orientation of the magnetization vector.
• the law of relative orientation variation of the magnetization vector implies a variation of 360° in the relative orientation of the projected vector, in orthogonal projection on a plane perpendicular to the main axis, of the magnetization vector at a given point of the circle, for a variation of the angular position of the point of the magnetized body corresponding to an angular period of the law of variation of relative orientation of the magnetization vector.
• the relative orientation variation law of the magnetization vector is a linear variation law as a function of the angular position of the point of the magnetized body.
• the magnetized body is a continuous body over 360° around the main axis.
• the magnetic body is made up of elementary magnetic bodies juxtaposed over 360° around the principal axis.
• the magnetized body is a body in the form of a tubular section of revolution around the main axis.
• the magnetized body is a body in the form of a cylindrical tubular section around the main axis.
• the invention also relates to a method for determining a relative angular position of a first part with respect to a second part over an angular stroke around an axis of rotation, characterized in that:
• the first part is equipped with a permanent magnet having any of the characteristics listed above;
• such a method includes the calculation of the arc-tangent tangent of a ratio between, on the one hand, the difference between the two primary components, and, on the other hand, the difference between the two secondary components, ratio in which each difference is weighted as a function of the distance, for the difference considered, between the corresponding measurement points and the axis of rotation.
• such a method is implemented with a sensor system as presented above.
• the invention also relates to a method for manufacturing a magnetic body for a system for determining a relative angular position of a first part with respect to a second part around an axis of rotation, the method comprising providing a body of magnetizable material having a symmetric tubular section shape about a major axis of the body of magnetizable material, the body of magnetizable material thereby having an inner surface and a length in the direction of the axis main, characterized in that the method comprises:
• a method according to the invention may further comprise one or more of the following optional features, taken alone or in combination.
• the arrangement of the parallel electrical conductors in each beam is identical by means of a rotation, between two angularly consecutive beams, by an angle equal to 360 degrees of angle divided by the number of beams.
• the parallel electrical conductors of the bundle are angularly distributed uniformly around the main axis. In some cases, in a given bundle, the parallel electrical conductors of the bundle are distributed over an arc of a circle centered on the main axis or over several concentric arcs of a circle centered on the main axis.
• each parallel electrical conductor of the bundle has a length along the axis of rotation which is equal to at least 4 times the length of the body of magnetizable material.
• the parallel electrical conductors of the beams are formed by sections of at least one winding of a conductive wire along which successively follow one another, at least one conductor of a go beam, a section of link, and a conductor of a return beam, another link section and another conductor of a go beam.
• the body of magnetizable material is a body in the form of a tubular section of revolution around the main axis.
• the body of magnetizable material is a body in the form of a cylindrical tubular section around the main axis.
• Figure 1 is a perspective view illustrating a possible embodiment for the geometry of a permanent magnet according to the invention.
• FIG. 2 schematically illustrates a first embodiment of a sensor system according to the invention, comprising a permanent magnet as shown in Figs. 3 to 5, having a law of variation of relative orientation of the magnetization vector which presents 2 angular periods over the 360° of the magnetized body.
• FIG. 3 schematically represents, in top view, an embodiment of a permanent magnet as used in the sensor system of FIG. 2, with an illustration of the magnetization vector at different points of the magnetized body distributed at 360° on a circle of given radius around the main axis of the magnetized body, for a law of variation of the relative orientation of the magnetization vector having two periods angular on the 360° of the magnetic body around the main axis.
• FIG. 4 schematically illustrates an embodiment of a method of manufacturing the permanent magnet of FIG. 3.
• Figure 5 schematically illustrates the magnetic induction field Bm created by the permanent magnet of Fig. 3 outside the magnetic body, in particular in the internal volume delimited by the magnetic body.
• Figure 6 is a view similar to that of FIG. 4, for the production of a permanent magnet in which the law of variation of the relative orientation of the magnetization vector presents four angular periods over the 360° of the magnetized body.
• Figure 7 is a view similar to that of FIG. 5, schematically illustrating the magnetic induction field Bm created by a magnetized body manufactured according to FIG. 6 outside the magnetized body.
• FIG. 8 Figure 8 schematically illustrates another embodiment of a sensor system according to the invention.
• FIG. 9 Figure 9 schematically illustrates another embodiment of a sensor system according to the invention.
• FIG. 10 Figure 10 schematically illustrates another embodiment of a sensor system according to the invention.
• FIG. 11 Figure 11 schematically illustrates another embodiment of a sensor system according to the invention.
• FIG. 12 Figure 12 schematically illustrates another embodiment of a sensor system according to the invention.
• the figures illustrate different embodiments of a permanent magnet and different embodiments of a magnetic position sensor system 1 allowing the determination of a relative angular position Q(t) of a first part 14 with respect to a second part 16 around an axis of rotation A.
• the sensor system 1 is designed to determine the relative angular position Q(t) of two parts 14, 16 which are likely to move relative to each other on the one hand according to a rotational movement around the axis of rotation A.
• the two parts 14, 16 are illustrated symbolically.
• the sensor system 1 can thus for example be used to detect the angular position of a shaft of output of a rotary actuator.
• the sensor system 1 comprises on the one hand a permanent magnet having a magnetized body 10 with permanent magnetization, and measuring elements 12.11, 12.12, 12.21, 12.22 of the magnetic induction.
• the magnetized body 10 is intended to be fixed to a first part 14 of a mechanism, for example the rotary output shaft of an actuator for a transmission member of a motor vehicle, which is mobile relative to a second part 16 of the mechanism, for example a fixed part of the structure of the vehicle or a support part of the sensor system 1.
• the magnetized body 10 is arranged on a rotating shaft forming the first part 14 in a configuration in which the magnetized body is arranged at the end of the shaft, at one longitudinal end thereof.
• the sensor system 1 is provided to determine the relative angular position Q(t) of the magnetic body 10 with respect to the measuring elements 12.11, 12.12, 12.21, 12.22 around the axis of rotation A, the measuring elements 12.11, 12.12, 12.21, 12.22 having a fixed position with respect to each other and a fixed position with respect to the second part 16.
• the relative movement between the magnetized body 10 and the measuring elements 12.11, 12.12, 12.21, 12.22, which is a simple rotation in the example considered, can therefore be described in an orthogonal frame (O, Xo, Yo, Zo), the basis vectors Xo and Yo being contained in a plane perpendicular to the axis of rotation A, the point of origin 0 being a point on the axis of rotation A, and the directions of the base vectors Xo and Yo being arbitrary but mutually orthogonal, and fixed with respect to the second part 16, as illustrated for example in the Fig. 2. It follows that the base vector Zo is parallel to the axis of rotation A.
• This coordinate system (O, Xo, Yo, Zo) is therefore fixed by relative to the second part 16 and relative to the measuring elements 12.11, 12.12, 12.21, 12.22, and will hereinafter be referred to as a measuring mark.
• the first part 14 is mobile and the second part 16 is fixed, but this is arbitrary insofar as only relative movement between the two parts 14, 16 is considered.
• the magnetized body 10 has a geometry in the form of a symmetrical tubular section around a main axis A' of the magnetized body 10. It is therefore in the form of a volume formed between an internal surface 6 and an external surface 8 each of which is symmetrical about the main axis A'. The inner surface 6 is surrounded by the outer surface 8.
• the main axis A' of the magnetized body 10 is therefore an axis of symmetry for the magnetized body 10.
• the magnetized body 10 is preferably arranged so that its main axis A' coincides with the axis of rotation A of the relative movement between the first part 14 and the second part 16.
• the magnetized body 10 has a geometry in the form of a cylindrical tubular section around the main axis A', symmetrical with respect to the main axis A', that is to say a volume formed between two internal 6 and external 8 cylindrical surfaces, each of which is generated by a straight generatrix, parallel to the main axis A', following a closed curve which extends 360° around the main axis A'. More specifically, provision can be made, which is the case in the examples illustrated, for the magnetized body 10 to have a geometry in the form of a cylindrical tubular section of revolution around the main axis A'.
• the two internal 6 and external 8 cylindrical surfaces of the magnetized body 10 have a circular shape.
• the magnetic body 10 in section through a plane perpendicular to the main axis A', a symmetrical polygonal geometry around the main axis A', preferably with a greater number of sides or equal to 6, preferably greater than or equal to 8, and preferably with sides of equal dimensions between them.
• the magnetized body 10 in the form of a symmetrical tubular section around a main axis A' of the magnetized body delimits an internal volume V, which, as we will see, must be sized to accommodate the magnetic induction measuring elements. .
• This internal volume V should therefore preferably completely include, in the radial direction with respect to the main axis A', a cylindrical inscribed volume of revolution around the main axis A' having a minimum radius which will for example be included in the range from 5 to 10 millimeters.
• the internal cylindrical surface 6 of the magnetized body 10 therefore has a radius “ri” comprised in the range from 5 to 10 millimeters.
• ri a radius comprised in the range from 5 to 10 millimeters.
• the magnetized body 10 has a thickness in a radial direction with respect to the main axis A'.
• the radial thickness of the magnetized body 10 is constant over 360° around the main axis A'. In some applications, this thickness may be in the range from 2 to 10 millimeters, preferably in the range from 2 to 6 millimeters. A greater thickness could however make it possible to produce a magnetized body with a less efficient magnetic material, therefore less expensive, to obtain the desired values of magnetic induction.
• the magnetic body 10 can be inscribed in an external cylindrical envelope of revolution around the main axis A' which has an external radius "re" of less than 25 mm, or even in certain applications less than 15 mm, which makes it possible to have a particularly compact sensor system 1 in the radial direction.
• the magnetic body 10 can be inscribed in an external cylindrical envelope of revolution around the main axis A' which has an external radius “re” which can be in the range going from 8 millimeters to 20 millimeters. For other applications, a larger outer radius can be implemented.
• the outer cylindrical surface 8 of the magnetized body 10 can therefore have a radius “re” of less than 25 mm, or even in some applications less than 15 mm, for example included in the range from 8 to 20 millimeters.
• the magnetized body 10 is delimited axially by two opposite end faces 5, 7.
• the two opposite end faces 5, 7 of the magnetized body 10, upper 5 and lower 7, are flat surfaces each contained in a plane perpendicular to the main axis A', therefore, in the sensor system 1, perpendicular to the axis of rotation A.
• the axial dimension of the magnetized body 10, between its two opposite end faces 5, 7, is for example included in the range from 4 millimeters to 20 millimeters.
• the magnetized body 10 can be a continuous body over 360° around the axis of rotation, that is to say formed from a single piece.
• the magnetized body is formed of elementary magnetized bodies juxtaposed over 360° around the main axis A' of the magnetized body, the elementary magnetized bodies being distinct bodies.
• the elementary magnetized bodies can then be assembled to form the annular body, for example by being glued to one another and/or by being assembled on a support part.
• the magnetized body 10 has a permanent magnetization.
• Any point P of the magnetic body 10 can be considered as being located on a given circle Crp around the main axis A'.
• Each point P of the magnetized body 10 on this given circle Crp, whatever the given circle Crp, has an angular position which is defined by the angle Q(R) formed, around the main axis A', between an axis fixed mark Xa of the permanent magnet and a particular radial segment SRp originating from the main axis and passing through this point P.
• the reference axis Xa is perpendicular to the main axis A', and therefore secant with the main axis A'.
• the reference axis Xa can be one of the basic axes of an orthogonal reference (O', Xa, Ya, Za), hereinafter called the reference of the permanent magnet, the basic vectors Xa and Ya being contained in a plane perpendicular to the main axis A', the point of origin 0' being a point on the main axis A', which is for example located at mid-length of the magnetized body 10 in the direction of the main axis A '.
• the point of origin 0' of the permanent magnet frame can coincide with the point of origin 0 of the measurement frame.
• the directions of the base vectors Xa and Ya are orthogonal to each other, and fixed with respect to the magnetic body 10.
• the base vector Za is parallel to the main axis A'.
• the orientation of the radial base vector Xa can be arbitrary with respect to the magnetized body 10. In this frame of the permanent magnet, the first part 14 is fixed and the second part 16 is mobile, but this is arbitrary insofar as only a relative movement between the two parts 14, 16 is considered.
• a vector has a direction, a direction determined according to this direction, and a norm. Conversely, a given direction can be traversed in two opposite directions.
• each point P of the magnetized body 10 on this given circle Crp is located at a distance rp from the main axis A', distance rp which is identical for all the points on the given circle Crp, the value rp therefore being the radius of this given circle Crp.
• a point P can therefore be defined by its polar coordinates P (rp, Q(R)).
• the magnetization vector M(P) at such a point P of the given circle Crp presents, in orthogonal projection on a plane perpendicular to the main axis A', a projected vector whose relative orientation cp(P), with respect to the radial segment particular SRp at this point P, is a function which is continuously variable according to a law of variation cp(P), which is hereinafter called the law of variation of the relative orientation of the magnetization vector, and which is a function of the position angular Q(R) of the point P of the magnetized body 10.
• the law of relative orientation variation of the magnetization vector can also be a function of the distance rp from the point P to the main axis A' , distance rp which is identical for all points on the given circle Crp.
• the relative orientation variation law cp(P) of the magnetization vector is a function of the angular position Q(R) which can therefore be expressed in the form of cp(rp, Q(A)).
• the law of relative orientation variation cp(P) of the magnetization vector can therefore be expressed in the form of cprp(0(P)).
• the relative orientation cp(P) corresponds to the angle between, on the one hand, the projected vector, in orthogonal projection on a plane perpendicular to the main axis A', of the magnetization vector M(P), and, on the other hand, the particular radial segment SRp at this point P.
• the variation in relative orientation dcprp(0(P)) is defined as the variation in orientation made by the projected vector, in orthogonal projection on a plane perpendicular to the main axis A', of the magnetization vector M(P), when one shifts by an angular offset d0(P) on the given circle Crp around the main axis A'.
• the law of variation of the relative orientation cprp(0(P)) of the magnetization vector is a periodic function having an even number Np greater than or equal to 2 of angular periods T over the 360° of the magnetized body around the 'main axis A'.
• the magnetization vectors M(P) and M(P') at such points will not necessarily have the same absolute orientation with respect to the fixed reference axis Xa of the permanent magnet.
• the law of variation of the relative orientation cprp(0(P)) of the magnetization vector is a continuously variable function over an angular period T.
• the relative orientation cprp(0(P)) of the magnetization vector is a function which varies at any point over an angular period T such that "consecutive" points on the same given circle Crp around the main axis A', have a relative orientation cprp(0(P)) of the magnetization vector which is different.
• This law of variation has an odd number greater than or equal to 3 of angular periods over the 360° of the magnetic body around the main axis A'.
• the law of relative orientation variation cprp(0(P)) is a periodic function having an even number Np greater than or equal to 2 of angular periods T over the 360° of the magnetic body around the main axis A', for two points P and P' of the magnetized body 10 which are symmetrical to each other with respect to the main axis A', the magnetization vectors M(P) and M(P') have , in orthogonal projection on a plane perpendicular to the main axis A', the same direction but an opposite direction.
• the relative orientation variation law cprp(0(P)) of the magnetization vector has 2 angular periods over the 360° of the magnetized body 10 around the main axis A', each angular period T equaling therefore 180° of mechanical angle.
• the relative orientation variation law cprp(0(P)) of the magnetization vector has 4 angular periods over the 360° of the body magnetélO around the main axis A', each angular period T therefore being equal to 90° mechanical angle.
• the law of relative orientation variation cprp(0(P)) of the magnetization vector implies a 360° variation of the relative orientation cprp(0(P)) of the projected vector, in orthogonal projection on a plane perpendicular to the main axis, of the magnetization vector with respect to the particular radial segment corresponding to the point considered, for a variation of the angular position of the considered point of the magnetized body 10 corresponding to an angular period T of the relative orientation variation law cprp(0(P)) of the magnetization vector.
• the magnetization vectors M(P) and M(P′) have the same norm. Indeed, during the magnetization of the magnetized body, care will generally be taken to magnetize the magnetized body until magnetic saturation. That implies in particular to neglect the variation of magnetization as a function of the magnetic field in the magnet, which is generally true in the normal operating range of the magnet.
• the norm of the magnetization vector M(P) is identical for any point P of the magnetized body 10, in particular for any point P belonging to the same given circle around the main axis A'.
• the magnetization vectors M(P) and M(P') present, in projection on a plane perpendicular to the main axis A', parallel projections, of opposite directions, and of the same norm.
• the relative orientation of the magnetization vector can vary slightly according to the radius “rp” at which the point P considered. This variation is in particular due to the magnetization device which, in practice, often creates a magnetic field having an imperfect "rotation", but also to the boundary conditions at the level of the internal and external surfaces 6 and 8 of the magnetized body 10 during the magnetization.
• the law of relative orientation variation of the magnetization vector implies a positive variation of the relative orientation cprp(0(P)) of the projected vector, in projection orthogonal on a plane perpendicular to the main axis, of the magnetization vector M(P) at a considered point P, with respect to the particular radial segment SRp passing through this considered point P, as a function of a positive variation of the angular position of the considered point of the magnetized body around the main axis A'.
• positive variation of the angular position of the point of the magnetized body around the main axis a variation according to an arbitrary direction around the main axis A'.
• the law of relative orientation variation of the magnetization vector implies a non-zero positive variation of the relative orientation cprp(0(P)) of the vector projected, in orthogonal projection on a plane perpendicular to the main axis, of the magnetization vector M(P) at a considered point P, with respect to the particular radial segment SRp passing through this considered point P, as a function of a positive variation not zero of the angular position of the considered point of the magnetized body around the main axis A'.
• the magnetized body 10 has a flat magnetization, that is to say such that, at any point of the magnetized body, the magnetization vector at this point is parallel to a magnetization plane perpendicular to the main axis A'.
• the projected vector, in orthogonal projection on a plane perpendicular to the main axis A', of the magnetization vector M(P) coincides with the magnetization vector M(P).
• the magnetization vector M(P) and its vector projected in orthogonal projection on a plane perpendicular to the main axis A' are identical.
• the norm of the magnetization vector M(P) is almost constant for any point P of the magnetized body, then, for points P and P' symmetrical to each other with respect to the main axis A', the magnetization vectors M(P) and M(P') are parallel, of opposite directions, and of the same norm, therefore symmetrical vectors.
• the magnetization plane is therefore a theoretical plane.
• the magnetization is subject to edge effects which can locally modify the magnetization near the external surfaces of the magnetized body. At these points, there may not be strict parallelism of the magnetization vector with the magnetization plane which is a theoretical plane.
• defects in the homogeneity of the magnetic material can locally affect the magnetization.
• the magnetization plane must therefore be understood as representative of the magnetization at each point of the magnetized body, taken as a whole, taking into account mainly the points which are not affected either by the edge effects or by the defects. of homogeneity clearly not sought, therefore in particular the points at the heart of the magnetic body.
• the magnetization plane is strictly perpendicular to the main axis A'. It is understood that the notion of strict perpendicularity of the magnetization plane with respect to the main axis A 'must be assessed there also with regard to the usual technique in the field of magnetic fields and in particular the magnetization of magnetized bodies . It must still be assessed with regard to the advantages and benefits of the invention, in particular the robustness of the measurement delivered by a sensor system made with such a magnetic body to relative positioning defects, between the magnetic body and the measuring elements. , in the direction of the main axis A'.
• the magnetization plane is strictly perpendicular to the main axis A' if it forms with the axis considered an axis less than 5 degrees. It will be considered that the magnetization plane is perpendicular to the main axis A' if it forms with the axis considered an angle of inclination of less than 30 degrees, preferably less than 20 degrees.
• the law of relative orientation variation cprp(0(P)) of the magnetization vector is a one-to-one law over an angular period T of the law of relative orientation variation cprp(0(P)) of the magnetization vector.
• This bijection relation favors the obtaining, in the internal volume V delimited by the magnetic body 10, of a magnetic induction field Bm such that one can obtain a relation between on the one hand at least 4 measurements of the magnetic induction in this internal volume V, and on the other hand the relative angular position Q(t) in rotation between the magnet and the measurement points, which is also a one-to-one relationship over an angular period T.
• We can thus associate within an angular period T, a single relative angular position Q(t) in rotation between the permanent magnet and the measurement points.
• the magnetized body 10 is a continuous body over 360° around the main axis A′, therefore made in a single piece with continuity of material.
• the magnetic body could be formed of elementary magnetic bodies juxtaposed over 360° around the main axis.
• the magnetization could be carried out either after the assembly of the elementary magnetized bodies, in a manner similar to what is proposed for a continuous body over 360°, or before the assembly of the elementary magnetized bodies.
• a method for manufacturing a magnetized body having the above properties is also proposed.
• a body of magnetizable material 10 having a shape as defined above is provided.
• the magnetizable material is in particular a ferromagnetic material, in particular hard ferromagnetic, ferrimagnetic, or antiferromagnetic, capable of forming, after controlled magnetization, a permanent magnet.
• Such materials include alloys, for example of neodymium, iron and boron (Nd2Fe14B) of Samarium and Cobalt (SmCo5 and Sm2Co17), and ferrites, as well as AlNiCo.
• a magnetization conductor 22 preferably consists of a wire or a bar of conductive material, for example copper, elongated along the orientation of the main axis A'.
• the magnetization conductors 22 are arranged so as to cross, in the direction of the main axis A′, the internal volume V delimited by the magnetized body 10.
• the magnetization conductors 22 are preferably arranged close to the inner surface 6 of the magnetized body 10.
• bundle 24 of magnetization conductors 22 refers to a group of magnetization conductors in which, at a given instant, the current flows in the same direction and in which the magnetization conductors 22 are not separated by a magnetization conductor 22 in which the current flows in another direction, in the marker linked to the magnet.
• a beam 24 can comprise a single magnetization conductor 22, or, preferably, several magnetization conductors 22, for example in the range from 4 to 40 magnetization conductors 22 for a beam 24. Different beams 24 can comprise a different number of magnetization conductors 22.
• Each beam 24 is included in space in a distinct angular sector around the main axis A', the angular measure of which is less than or equal to half of an angular period T of the orientation variation law.
• relative cprp(0(P)) of the magnetization vector that we want to create in the magnet permanent, preferably over an angular range around the main axis A' which is as close as possible to half an angular period of the law of relative orientation variation cprp(0(P)) of the magnetization vector.
• the angular measure of the angular sector in which each beam is included is equal to 360 degrees of angle divided by the number of beams.
• the beams 24 are angularly offset from each other around the main axis A'.
• two consecutive beams 24 are directly juxtaposed to each other angularly around the main axis A'.
• two consecutive beams 24 are arranged, one with magnetization conductors 22 in which, at a given instant , the current flows in the same direction and the other in which the current flows in another direction in the magnetization conductors 22.
• a beam 24 some of the magnetization conductors 22 or all of the magnetization conductors 22 can be attached to each other. In this case, provision can be made for the magnetization conductors 22 to be electrically insulated from each other, for example by an insulating sheath. On the other hand, one or more magnetization conductors 22 of a bundle 24 can be separated transversely from the other magnetization conductors of the same bundle 24, or all the magnetization conductors 22 can be separated from each other.
• a beam 24 can comprise an outer casing, for example made of electrically insulating material, surrounding the magnetization conductors 22 of the beam.
• the number of bundles 24 of parallel electrical conductors 22 is a non-zero multiple of 4. More precisely, a bundle 24 of parallel electrical conductors will advantageously be provided for each half-period T/2 of the orientation variation law relative cprp(0(P)) of the desired magnetization vector in the magnetized body that one seeks to manufacture.
• a bundle 24 of parallel electrical conductors will advantageously be provided for each half-period T/2 of the orientation variation law relative cprp(0(P)) of the desired magnetization vector in the magnetized body that one seeks to manufacture.
• T/2 of the orientation variation law relative cprp(0(P)) of the desired magnetization vector in the magnetized body that one seeks to manufacture.
• to produce a magnetized body 10 having two angular periods of the relative orientation variation law cprp(0(P)) of the magnetization vector over the 360° of the magnetized body 10 there are thus four beams 24, each of which s 'extends, in the internal
• the current flows in a first direction according to the orientation of the magnetization conductors, while in the two other beams, offset from each other by 180° around this axis main A' and interposed between the other two, the current flows in a second direction, opposite to the first.
• eight beams 24 are thus arranged, each of which s extends, in the internal volume V delimited by the magnet body 10, over 45°.
• the current flows in a first direction depending on the orientation of the magnetization conductors, while in the other four beams, offset from each other by 90° around the main axis A' and interposed between the other four, the current flows in a second direction, opposite to the first.
• the bundles 24 are arranged, for their magnetization conductors 22 closest to the internal surface 6 of the body of magnetizable material 10, less than 10 mm from the internal surface 6 or even less than 5 mm from inner surface 6.
• the method of course involves the circulation of an electric current in the bundles of magnetization conductors 22, the direction of circulation of the current being, at a given instant, for example an instant for which the intensity of the current is maximum, identical in all the magnetization conductors 22 of the same beam 24, and being inverse in two beams 24 immediately adjacent around the main axis A'.
• the electric current flowing in the beams 24 is able to generate, around the network 20 and therefore in the body of magnetizable material 24, a magnetizing magnetic field suitable for magnetizing the body of magnetizable material.
• this electric current must have a maximum value of sufficient intensity.
• the magnetic field created by the network of magnetizing conductors is preferably capable of magnetically saturating the magnetizable material, at all points thereof.
• the body of magnetizable material can serve as a body of magnetic material 10 in a method and in a sensor system 1 according to the invention.
• different bundles 24 do not necessarily have the same number of conductors.
• the arrangement of the conductors in each beam 24 is identical from one beam to another, subject to a rotation, between two angularly consecutive beams, by an angle equal to the measurement of the angular sector in which a beam, i.e. 360 degrees of angle divided by the number of beams.
• the beams 24 will therefore preferably be identical to each other, in particular in number, dimensions and arrangement of the magnetization conductors with only an angular offset of a half-period between two consecutive beams 24.
• the magnetization conductors 22 of the beam 24 are preferably angularly distributed in a uniform manner around the main axis A'.
• the magnetization conductors 22 of the beam 24 are distributed over an arc of a circle centered on the main axis or, as in the examples illustrated in Figs. 4 and 6, on several concentric circular arcs centered on the main axis A'.
• the magnetization conductors 22 of the beam 24 are contained inside an envelope surface whose section, in a plane perpendicular to the main axis A', is a sector of a ring around the main axis A'.
• provision will be made for several beams 24, or even all of the beams 24, including forward beams and return beams, to be electrically connected in series. Provision may be made for several magnetization conductors 22, or even all of the magnetization conductors 22, including outward magnetization conductors and return magnetization conductors, to be electrically connected in series to form one or more magnetization coils .
• the magnetization conductors 22 of the beams are formed by sections of at least one winding of a winding of a conductive wire along which successively follow one another, at least one conductor of magnetization 22 of a go beam, a link section, and a magnetization conductor 22 of a return beam, another link section and another a magnetization conductor 22 of a go beam.
• all the magnetization conductors 22 can be grouped together in a single coil winding, in two coil windings or in more than two coil windings.
• a network of conductors could be formed of a grid comprising, on one side of the body made of magnetizable material, a first bar or plate for connecting to a first electrical potential, and, on the other side of the body of magnetizable material, a second bar or plate for connecting to a second electric potential.
• Each conductor of the network could then take the form of a rectilinear segment whose length would correspond to the distance between the bars or plates, each conductor extending between the two bars or plates, and being connected by its two ends respectively to the first and to the second connecting bar or plate.
• the magnetization conductors 22 have a length according to their orientation which extends between two supply heads which can for example each be constituted by the connecting section within the framework of a coil, or by a bar or connecting plate as part of a beam formed by a grid.
• the electric current can flow in a transverse or substantially transverse direction with respect to the orientation of the conductors. It is desirable to limit the magnetic influence of these currents, to limit the disturbances on the magnetization of the body of magnetizable material, and it is therefore desirable that the magnetization conductors have a sufficient length to achieve this goal.
• the magnetization conductors 22 will thus have an axial length greater than the axial extent of the body of magnetizable material 10, preferably an axial length greater than or equal to 4 times the axial extent of the body of magnetizable material 10.
• a permanent magnet as described above generates, outside the magnetized body 10, a magnetic induction field Bm as shown in FIG. 5 or in FIG. 7 for the two embodiments described above.
• This magnetic induction field created by the permanent magnet has, in the internal volume V delimited by the internal surface 6 of the magnetized body 10, a property similar to that described above with regard to the magnetization vector in the body. magnetized 10.
• Any point E of the internal volume V delimited by the internal surface 6 of the magnetized body 10 can be considered as being on a given circle around the main axis A'.
• Each point E of the internal volume V on this given circle has an angular position defined by the angle formed, around the main axis, between the fixed reference axis of the permanent magnet described above, and a particular radial segment coming from the main axis and passing through this point E.
• the magnetic induction Bm generated by the permanent magnet at this point of the given circle presents, in orthogonal projection on a plane perpendicular to the main axis A', a projected vector whose relative orientation with respect to the particular radial segment at this point is a continuously variable function according to a law of variation of relative orientation, with respect to the particular radial segment from the main axis and passing through this point E, as a function of the angular position of the point E of the internal volume V.
• the law of variation of relative orientation of the magnetic induction generated by the loved nt permanent at a point E of the given circle is a periodic function presenting the same even whole number Np greater than or equal to 2 angular periods over the 360° of the internal volume V around the main axis A'.
• the relative orientation variation law of the magnetic induction Bm generated by the permanent magnet therefore has the same number Np of angular periods as the relative orientation variation law of the magnetization vector in the magnetized body 10.
• the norm of the vector of the magnetic induction Bm induced by the magnetized body varies according to the distance at which the considered point E is located with respect to the main axis A'.
• the magnetic induction is zero at the center of the magnet and its intensity increases according to the distance at which the point E under consideration is located with respect to the main axis A up to a maximum value near the internal surface of the magnet. 'magnet. This maximum value depends on the material and dimensions of the magnet.
• a sensor system 1 for determining a relative angular position Q(t) of a first part 14 with respect to a second part 16 around an axis of rotation A will advantageously be designed in the manner next.
• the sensor system 1 naturally comprises a permanent magnet having a magnetized body 10 having the above characteristics.
• care will be taken to ensure that the permanent magnet is arranged in such a way that the main axis A' of the magnetized body 10 coincides with the axis of rotation A of the relative rotation between the first part 14 and the second room 16.
• the sensor system 1 comprises a main set of 4 measuring elements 12.11, 12.12, 12.21, 12.22 of the magnetic induction B, which will be arranged in the internal volume V delimited by the inner surface 6 of the magnetized body 10. Different positioning and orientation possibilities are possible for these measuring elements 12.11, 12.12, 12.21, 12.22.
• a general case of layout is shown in Fig. 8 which therefore illustrates an embodiment of a sensor system 1. More particular embodiments are described in Figs. 9 to 12.
• the sensor system 1 comprises a primary pair of measuring elements 12.11, 12.12 comprising a first primary measuring element 12.11 and a second primary measuring element 12.12.
• the first primary measurement element 12.11 is arranged at a first primary measurement point E11 fixed with respect to the second part 16. This first primary measurement element 12.11 makes it possible to determine, at this first primary measurement point E11, a first primary component B11 of the magnetic induction at this point El 1, according to a primary measurement vector D1 perpendicular to the axis of rotation A.
• the second primary measurement element 12.12 is arranged at a second primary measurement point E12 which is also fixed relative to the second part 16.
• This second primary measurement element 12.12 makes it possible to determine, at this second primary measurement point E12, a second primary component B12 of the magnetic induction B according to the same primary measurement vector D1 as that of the first primary measurement element 12.11.
• the second primary measurement element 12.12 makes it possible to determine, at this second primary measurement point E12, a second primary component B12 of the magnetic induction B according to the same primary measurement vector D1 as that of the first primary measurement element 12.11 even if it is mounted in the opposite direction relative to the first primary measuring element 12.11.
• the second primary measuring element 12.12 delivers a second raw primary component which it suffices to multiply by the factor (-1) to obtain the second primary component B12 of the magnetic induction B according to the same primary measurement vector D1.
• the first primary measurement point E11 and the second primary measurement point E12 are separate points between them on the same primary diametral segment SD1 with respect to the axis of rotation A. These two points E11 and E12 are fixed by relative to the second part 16, and fixed to each other. These two points E11 and E12 are located inside the internal volume V delimited by the magnetic body 10. It will be seen that there are preferential positions for these two points E11 and E12 on the primary diametral segment SD1. Indeed, provision will advantageously be made for these two primary measurement points E11 and E12 to be preferably symmetrical to each other with respect to the axis of rotation A. However, this condition is not mandatory.
• the primary measurement vector D1 forms, with respect to the primary diametral segment SD1, a relative primary measurement angle m1.
• this relative primary measurement angle m1 can be arbitrary, but will preferably be equal to 0° or 90°, so that the “primary measurement ctor D1 will in such a case be respectively parallel or perpendicular to the primary diametral segment SD1.
• the primary measurement vector D1 is contained in a plane perpendicular to the axis of rotation A.
• the two primary measurement elements each measure a primary component of the magnetic induction according to the same primary measurement vector D1.
• the two primary elements for measuring the primary couple of measuring elements and taking into account the symmetrical character of the magnetic induction field Bm created by the permanent magnet in the internal volume V, it is ensured that the two elements of the same pair measure, according to the same measurement vector D1, the magnetic induction at two points at which the magnetic induction Bm created by the permanent magnet is vectorially different.
• the sensor system 1 also comprises a secondary pair of measuring elements 12.21, 12.22, comprising a first secondary measuring element 12.21 and a second secondary measuring point 12.22.
• the first secondary measurement element 12.21 is arranged at a first secondary measurement point E21 fixed relative to the second part 16. This first secondary measurement element 12.21 makes it possible to determine, at this first secondary measurement point E21, a first secondary component B21 of the magnetic induction B, according to a secondary measurement vector D2 perpendicular to the axis of rotation A.
• the second secondary measurement element 12.22 is arranged at a second secondary measurement point E22 which is also fixed relative to the second part 16.
• the second secondary measurement element 12.22 makes it possible to determine, at this second secondary measurement point , a second secondary component B22 of the magnetic induction B, according to the same secondary measurement vector D2 as that of the first secondary measurement element 12.21.
• the second secondary measurement element 12.22 makes it possible to determine, at this second secondary measurement point E22, a second secondary component B22 of the magnetic induction B according to the same secondary measurement vector D2 than that of the first secondary measuring element 12.21 even if it is mounted in the opposite direction relative to the first secondary measuring element 12.21.
• the second secondary measuring element 12.22 delivers a second gross secondary component which it suffices to multiply by the factor (-1) to obtain the second secondary component B22 of the magnetic induction B according to the same secondary measurement vector D2.
• the first secondary measurement point E21 and the second secondary measurement point E22 are distinct points between them on the same secondary diametral segment SD2 with respect to the axis of rotation A. These two points E21 and E22 are fixed by relative to the second part 16, and fixed to each other. These two points E21 and E2 are located inside the internal volume V delimited by the magnetic body 10. Just as for the primary measurement points E11 and E12, it will be seen that there are preferential positions for these two secondary measurement points. measure E21 and E22 on the secondary diametral segment SD2. In fact, provision can advantageously be made for these two secondary measurement points E21 and E22 to be preferably symmetrical to each other with respect to the axis of rotation A. However, this condition is not mandatory.
• the secondary measurement vector D2 forms, with respect to the secondary diametral segment SD2, a relative secondary measurement angle m2.
• this relative secondary measurement angle m2 can be arbitrary, but will preferably be equal to 0° or 90°, so that the secondary measurement vector D2 will in such a case be respectively parallel or perpendicular to the secondary diametral segment SD2.
• Each measuring element comprises at least one magneto-sensitive component, for example Hall effect, which delivers at least one electrical signal, for digital and/or analog example, representative of the corresponding component of the vector representative of the magnetic induction B at the measurement point of the measurement element considered, with respect to the measurement vector of this sensitive element.
• This component can be positive or negative depending on whether the vector representative of the magnetic induction B, at the measurement point of the measurement element considered, is, in projection on the measurement vector, of the same direction as the measurement vector of this sensitive element, or in the opposite direction.
• MLX90372 - Triaxis® Position Processor marketed by the company Melexis NV, Rozendaalstraat 12, B-8900 leper, Belgium, in particular a component of the "Angular Rotary Strayfield Immune” subfamily, as described in the document "MLX90372 - Triaxis® Position Processor Datasheet - REVISION 8 - 08 MAR 2019”.
• the different particular embodiments of the invention which are illustrated in the figures can be separated into two main families.
• a first family of embodiments such as those of Figs. 8, 9 and 12
• the primary diametral segment SD1 and the secondary diametral segment SD2 are distinct and it is then possible to determine an angular difference 512 between the two around the axis of rotation A.
• a second family of embodiments such than those of Figs. 10 and 11
• the primary diametral segment SD1 and the secondary diametral segment SD2 are combined, so that the four measuring elements are all four located on the same diametral segment with respect to the axis of rotation.
• the angular difference 512 between the primary diametral segment SD1 and the secondary diametral segment SD2 is zero.
• the angular difference 512 between the primary diametral segment SD1 and the secondary diametral segment SD2 is equal to the angular position of the secondary diametral segment SD2 from which the angular position of the primary diametral segment SD1 is subtracted.
• the sensor system 1 is advantageously arranged so that the sum [(m2 - m1) + Np x 512] of, on the one hand, the angular difference (m2 - m1) between the secondary relative angle of measurement m2 and the primary relative angle of measurement m1, with, on the other hand, the angular deviation 512, multiplied by the number Np of periods of the relative orientation variation law cprp(0(P)) of the magnetization vector as a function of the angular position of the point of the magnetized body, between the secondary diametral segment SD2 and the primary diametral segment SD1 , is non-zero and different from a multiple of 180°.
• This condition makes it possible to obtain two primary component measurements, i.e. two measurements according to the primary measurement vector, and two secondary component measurements, i.e. two measurements according to the secondary measurement vector, under conditions such as the measurements of the primary components are linearly independent of the measurements of the secondary component, or can be projected onto orthogonal vectors so as to give projected primary components which are linearly independent of projected secondary components.
• the sensor system is arranged so that the sum [(m2 - m1) + Np x 512] of, on the one hand, the angular difference (m2 - m1) between the angle secondary relative measurement angle m2 and the primary relative measurement angle m1, with, on the other hand, the angular deviation 512, multiplied by the number of periods of the relative orientation variation law cprp(0(P) ) of the magnetization vector as a function of the angular position of the point of the magnetized body, between the secondary diametral segment SD2 and the primary diametral segment SD1 is equal, modulo 360 degrees, to 90 degrees or to 270 degrees.
• This condition makes it possible on the one hand to be able to determine two primary component measurements, i.e. two measurements according to the primary measurement vector, and two secondary component measurements, i.e. two measurements according to the secondary measurement vector, under conditions such that the measurements of the primary component are linearly independent of the measurements of the secondary component, which facilitates the calculation of the angle of the magnetic induction. We then speak of measurements out of phase by 90 degrees in the magnetic domain.
• the sensor system 1 is arranged so that the relative secondary measurement angle m2 and the primary relative angle measurement angle m1 are equal, and such that the angular difference 512 between the secondary diametral segment SD2 and the primary diametral segment SD1 is a quarter of an angular period T/4 of the relative orientation variation law cprp(0(P)) of the magnetization vector, modulo the half angular period T/2 of the variation law d relative orientation cprp(0(P)) of the magnetization vector.
• This configuration also makes it possible to obtain measurements out of phase by 90 degrees in the magnetic domain, as mentioned above.
• the fact that the secondary relative angle of measurement m2 and the primary relative angle of measurement m1 are equal results in the fact that the primary measurement vector D1 and the secondary measurement vector D2 are both oriented according to radial directions with respect to their respective measurement point.
• the primary measurement vector D1 is oriented in a radial direction, with respect to the axis of rotation A, which passes through the first primary measurement point E11 and through the second primary measurement point E12
• the secondary vector of measurement D2 is oriented in a radial direction, with respect to the axis of rotation A, which passes through the first secondary measurement point E21 and through the second secondary measurement point E22.
• the angular difference 512 between the secondary diametral segment SD2 and the primary diametral segment SD1 is a quarter of an angular period T/4 of the relative orientation variation law cprp(0(P)) of the vector magnetization.
• this angular deviation 512 could be 3/4, 5/4 or 7/4 of the angular period, whatever the even integer number Np of angular period the law of relative orientation variation cprp(0 (P)) of the magnetization vector over 360° around the main a>e of the magnetized body 10.
• the angular deviation 512 could be 9/4, 11/4; etc... of the angular period.
• the sensor system 1 is arranged so that the primary diametral segment SD1 and the secondary diametral segment SD2 coincide and that the primary measurement vector D1 and the secondary measurement vector D2 are mutually orthogonal. This configuration also makes it possible to obtain measurements out of phase by 90 degrees in the magnetic domain, as mentioned above.
• the second primary point and the second secondary point coincide at the same point E2.
• the first primary measurement element 12.11 and the first secondary measurement element 12.21 can be arranged at the same point, and/or the second primary measurement element 12.12 and the second secondary measuring element 12.22 can be arranged at the same point.
• the two measurement elements which are arranged in a single point, or arranged very close to each other can be combined in the same measuring cell.
• the concept of measurement at a single point is assessed according to the spatial resolution of the position measurement delivered by the sensor. For example, two measurement elements may be considered at the same point if their respective measurement points are less than 0.25 millimeters apart.
• the four measuring elements 12.11, 12.12, 12.21, 12.22 therefore each deliver a value of a component of the magnetic induction B11, B12, B21, B22 in one measuring point.
• each component of the magnetic induction B11, B12, B21, B22 which is thus measured differs from the three others, taken one by one, either by the point at which it is measured or by the measurement vector according to which the component is measured.
• the first primary measurement point E11, E1 and the second primary measurement point E21, E2 are arranged at the same distance on each side of the axis of rotation A.
• E1 and the second secondary measurement point E22, E2 are also arranged at the same distance on each side of the axis of rotation. In both cases, this allows the two measuring elements of the same pair to measure the magnetic induction created by the permanent magnet at two points where the respective vectors of the magnetic induction are opposite each other but have the same standard.
• the first primary measurement point and the second primary measurement point are arranged at the same first distance from the axis of rotation, and the first secondary measurement point and the second secondary measurement point are arranged at the same first distance from the axis of rotation.
• the four measuring elements are all at the same distance from the axis of rotation A. In these embodiments, this allows the four measuring elements to measure the magnetic induction Bm created by the permanent magnet at points where the respective vectors of the magnetic induction Bm have the same norm.
• each magnetic induction measuring element it will be sought to arrange each magnetic induction measuring element as close as possible to the internal surface 6 of the magnetized body 10. This makes it possible, by limiting the so-called "air gap" distance » to benefit, at the point of measurement of the measuring element, from an intensity of the magnetic induction Bm created by the magnet which will be maximum.
• the magnetization of the magnetized body 10 is such that, as seen above, one obtains in the internal volume V levels of intensity of the magnetic induction Bm created by the magnetized body which are significant. for a given value of the intensity of the magnetization vector M(P) in the magnetized body 10.
• This can be taken advantage of to implement a less bulky magnetized body or made of less efficient and less expensive magnetic material, and/or for allow a distance called "air gap" greater than that usually implemented.
• this last possibility can be used more particularly, as in the example of Fig. 12.
• the so-called “air gap” distance will preferably be between 0.5 and 8 millimeters.
• the measuring elements are arranged in the internal volume V delimited by the internal surface 6 of the magnetized body. This contributes to good compactness of the sensor system, in particular along the axial direction of the axis of rotation A. This also contributes to good robustness of the angular position determination delivered by the sensor system, with respect to possible inaccuracies as to the relative position of the magnetic body and the measuring elements of the sensor system in the axial direction of the axis of rotation of the sensor system.
• the two measuring points El 1 , E21, E1, E2 of the primary pair of measuring elements 12.11, 12.21 and/or the two measuring points E21, E22, E1, E2 of the secondary pair of measuring elements 12.21, 12.22 are arranged in the same plane perpendicular to the axis of rotation A.
• this same plane perpendicular to the axis of rotation is at equal distance from the axial ends of the magnetized body 10, this in order to limit the influence of the inevitable edge effects at the axial ends of the magnetized body 10.
• FIG. 12 there is the same arrangement as in that of FIG. 9, but multiplying the measurement points.
• the particular example of Fig. 12 first presents a main set of 4 measuring elements 12.11, 12.12, 12.21, 12.22 of the magnetic induction B having the same characteristics as those described for that of FIG. 9, but, in one of the possible variants, one could have started with a main set of 4 measurement elements having the same characteristics as those described for that of FIG. 11.
• FIG. 12 is an example in which there is, in addition to the main set of 4 measuring elements 12.11, 12.12, 12.21, 12.22 of magnetic induction B, an additional set of 4 additional measuring elements 12.31, 12.32, 12.41, 12.42 of the magnetic induction B, which are arranged in the internal volume V delimited by the internal surface 6 of the magnetic body 10.
• This additional assembly comprises a tertiary pair of measuring elements 12.31, 12.32 comprising a first tertiary measuring element 12.31 and a second tertiary measurement element 12.32, respectively arranged at a first tertiary measurement point E31 fixed relative to the second part 16 to determine a first tertiary component B31 of the magnetic induction at this point E31, according to a tertiary measurement vector D3 perpendicular to the axis of rotation A, and at a second tertiary measurement point E32 fixed relative to the second part 16 to determine, at this second tertiary measurement point E32, a second tertiary component B32 of the magnetic induction B according to the same tertiary measurement vector D3 as that of the first tertiary measurement element 12.31.
• the first tertiary measurement point E31 and the second tertiary measurement point E32 are distinct points between them on the same tertiary diametral segment SD3 with respect to the axis of rotation A. Furthermore, the two tertiary measurement elements each measure a tertiary component of the magnetic induction according to the same tertiary vector of measurement D3.
• the additional assembly also comprises a quaternary pair of measuring elements 12.41, 12.42, comprising a first quaternary measuring element 12.41 and a second quaternary measuring point 12.42 respectively disposed at a first quaternary measuring point E41 fixed by relative to the second part 16 to determine, at this first quaternary measurement point E41, a first quaternary component B41 of the magnetic induction B, according to a quaternary measurement vector D4 perpendicular to the axis of rotation A, and at a second quaternary measurement point E42 which is also fixed relative to the second part 16 to determine, at this second quaternary measurement point, a second quaternary component B42 of the magnetic induction B, according to the same quaternary measurement vector D4 as that of the first quaternary element of measure 12.41.
• the first quaternary measurement point E41 and the second quaternary measurement point E42 are points distinct from each other on the same quaternary diametral segment SD4 with respect to the
• the main set of 4 measuring elements and the additional set are separate sets in the sense that a measuring element of the additional set is arranged at a separate point with respect to any measuring element of the main assembly or determines, at its measurement point, a component of the magnetic induction B according to a vector not parallel to the measurement vector of any other measurement element which would be arranged at the same point.
• the tertiary diametral segment SD3 and the diametral segment quaternary SD4 are each distinct from both the primary diametral segment SD1 and the secondary diametral segment SD2.
• the presence of an additional set of 4 additional measuring elements 12.31, 12.32, 12.41, 12.42 of the magnetic induction can be used to implement measurement redundancy, and/or, as will be explained below, to increase the measured magnetic induction intensity, in order to increase the signal / noise ratio of the sensor,
• the tertiary diametral segment SD3 and the quaternary diametral segment SD4 are each angularly offset respectively from the primary diametral segment SD1 and from the secondary diametral segment SD2.
• this angle could be arbitrary.
• the tertiary diametral segment SD3 and the quaternary diametral segment SD4 are each angularly offset by 90° respectively from the diametral segment primary SD1 and the secondary diametral segment SD2.
• the angular difference 512 between the secondary diametral segment SD2 and the primary diametral segment SD1 is a quarter of an angular period T/4 of the relative orientation variation law cprp(0(P)) of the magnetization vector , so here 45 degrees
• the four diametral segments primary SD1, secondary SD2, tertiary SD3 and quaternary SD4 are arranged, in this order, at 45 degrees of angle from each other around the axis of rotation A .
• the tertiary measurement vector D3 forms, with respect to the tertiary diametral segment SD3, a relative primary measurement angle which can be arbitrary, but which will preferably be equal to 0° or 90°, so that the tertiary measurement vector D3 will in such a case be respectively parallel or perpendicular to the tertiary diametral segment SD3.
• the tertiary measurement vector D3 is contained in a plane perpendicular to the axis of rotation A.
• the quaternary measurement vector D4 forms, with respect to the quaternary diametral segment SD4, a relative quaternary measurement angle which can be arbitrary, but which will preferably be equal to 0° or 90°, so that the quaternary measurement vector D4 will in such a case be respectively parallel or perpendicular to the quaternary diametral segment SD4.
• all the measurement vectors D1, D2, D3, D4 form, with respect to the quaternary diametral segment SD4, the same relative measurement angle.
• all the measurement vectors D1, D2, D3, D4 are all oriented along radial directions with respect to their respective measurement point.
• the relative angle of primary measurement and the relative angle of tertiary measurement are equal, and on the other hand the tertiary diametral segment SD3 and the primary diametral segment SD1 are shifted by one angle which is equal to an angular half-period T.
• the first tertiary component B31 and the first primary component B11 are components which vary in phase opposition with each other as a function of the relative rotation between the magnetized body and the measuring elements. In this way, the first tertiary component B31 and the first primary component B11 are not linearly independent.
• the same phase opposition is found for the variations of the second tertiary component B32 and the second primary component B12.
• the relative secondary measurement angle and the relative quaternary measurement angle are equal, and the quaternary diametral segment SD4 and the secondary diametral segment SD2 are offset by an angle which is equal to one half angular period T, so that the first quaternary component B41 and the first secondary component B21 are components which vary in phase opposition with each other as a function of the relative rotation between the magnetized body and the measuring elements.
• the same phase opposition is found for the variations of the second quaternary component B42 and the second secondary component B22.
• all the measurement points are arranged are arranged at the same first distance from the axis of rotation A. It is noted that, in this embodiment, the measurement points are arranged closer to the axis of rotation A than of the inner surface 6 of the magnetized body 10. All the measurement points can thus be arranged within a circle centered on the axis of rotation, the radius of which can be less than half, or even less than a quarter of the inner radius " ri” of the internal surface 6 of the magnetic body 10. This arrangement makes it possible to combine all the measuring elements on the same component, to the benefit of the cost, the size and the ease of production of the sensor system 1.
• the sensor system comprises an electronic calculation unit 100 programmed to calculate a value representative of the relative angular position Q(t) of the first part 14 compared to the second part 16.
• the electronic calculation unit 100 can be integrated into the sensor system 1, or be remote from the sensor system 1, for example in an electronic control unit or a computer.
• the electronic computing unit 100 typically comprises one or more memory modules, at least one processor, a data input/output module, and possibly a communication module.
• the calculation steps of a method are typically implemented by a computer program containing the corresponding instructions and stored in the memory module.
• one or more measuring elements and the electronic calculation unit are part of the same electronic component, which makes it possible to reduce the cost and increase the reliability of the sensor system 1.
• the four or more measuring elements 12.11, 12.12, 12.21, 12.22 are integrated in the same electronic component, which may comprise an electronic calculation unit 100 common to the four measuring elements.
• ECU control unit electronics
• the electronic calculation unit 100 is therefore programmed to implement a method for determining the relative angular position Q(t) of the first part 14 with respect to a second part 16 over an angular travel around the axis of rotation a.
• This method is based on the fact that the first part 14 is equipped with a permanent magnet as described above, which therefore generates, in the internal volume V delimited by the internal surface 6 of the magnetic body 10, a magnetic induction field Bm having the above characteristics.
• a first primary component B11 of the magnetic induction B is determined according to a primary measurement vector D1 perpendicular to the axis of rotation A, and, in a second primary measurement point E12, E2 a second primary component B12 of the magnetic induction according to the same primary measurement vector D1.
• the first primary measurement point El 1 , E1 and the second primary measurement point E12, E2 are distinct points between them on the same primary diametral segment SD1 with respect to the axis of rotation A, and they are located inside the internal volume V delimited by the magnetic body 10.
• the primary measurement vector D1 forms, with respect to the primary diametral segment SD1, a relative primary measurement angle m1.
• a first secondary component B21 of the magnetic induction B is determined according to a secondary measurement vector D2 perpendicular to the axis of rotation A, and, in a second secondary measurement point E22, E2, a second secondary component B22 of the magnetic induction B according to the same secondary measurement vector D2, the first secondary measurement point and the second secondary measurement point being distinct points between them on the same secondary diametral segment SD2 with respect to the axis of rotation A and being located inside the internal volume V delimited by the magnetic body 10, and the secondary measurement vector D2 forming, with respect to the secondary diametral segment SD2 , a secondary relative angle of measure m2.
• a value representative of the relative angular position Q(t) of the first part 14 with respect to the second part 16 is calculated, on the basis of a calculation comprising on the one hand , a difference (B12 - B11 ) or (B11 - B12) between the two primary components, and, on the other hand, a difference (B22 - B21) or (B21 - B22) between the two secondary components.
• a representative value of the relative angular position Q(t) of the first part 14 with respect to the second part 16 can be calculated on the basis of the calculation of the arc-tangent of a ratio between, of a on the one hand, a difference (B12 — B11 ) between the two primary components and, on the other hand, a difference (B22 - B21 ) between the two secondary components, a ratio in which each difference of components is weighted according to the distance, for the considered difference between the corresponding measurement points and the axis of rotation A.
• This value can be considered as a primary differential component, depending on the primary measurement vector.
• this difference value can be written as a function:
• DB1 f1 (B11 - B12) for example a linear or affine function:
• DB1 a1 x (B11 - B12) + k1
• a value DB2 representative of the difference between the first secondary component B21 and the second secondary component B22 is calculated.
• This value can be considered as a secondary differential component, depending on the measurement secondary vector.
• this difference value can be written as a function,
• DB2 f2 (B21 - B22) for example a linear or affine function:
• DB2 a2 x (B21 - B22) + k2
• the coefficients a1, k1 on the one hand, and a2, k2 on the other hand are corrective coefficients which may be determined by calculation or by calibration.
• the coefficients a1, a2, k1 and k2 are coefficients whose main role is to weight the values measured for B11, B12, B21 and B22 according to the differences between, on the one hand, the respective average position of the first primary point E11 and of the second primary point E12 with respect to the axis of rotation A, and on the other hand the respective mean position of the first secondary point E12 and of the second secondary point E22 with respect to the axis of rotation A.
• C ' is so that the differences DB1 and DB2 are weighted according to the distance, for the difference considered, between the corresponding measurement points and the axis of rotation A.
• the coefficients a1 and a2 may be equal or substantially equal, or even equal or substantially equal to 1.
• the coefficients a1 , a2, k1 and k2 may be used to weight the values measured for B11 , B12, B21 and B22 as a function, additionally or alternatively, for example, of the geometric defects present, such as eccentricity or misalignment of the measurement axes, or of the respective sensitivity of the various measurement elements.
• the coefficients a1, a2, k1 and k2 will for example be chosen so that, over an angular period T complete with the law of variation of the relative orientation cprp(0(P)) of the magnetization vector, the quantities DB1 and DB2 as a function of the angle of mechanical rotation have the same amplitude and a zero mean value.
• DB1 a1 x (B11 - B12) - a’1 (B31 - B32) + k1 which, in a simplified form can become, in particular with measurement points at the same distance from the axis of rotation:
• DB1 (B11 - B12) - (B31 - B32) and, as representative values of the difference between the first secondary component and the second secondary component, a difference value in the form of
• DB2 a2 x (B21 - B22) - a’2 (B41 - B42) + k2 which, in a simplified form can become, in particular with measurement points at the same distance from the axis of rotation:
• a value representative of the relative angular position Q(t) of the first part 14 with respect to the second part 16 can be calculated in the form of a gross angle b, this gross angle b being the arc whose tangent is representative of the relationship mentioned above between, on the one hand, a difference between the two primary components and, on the other hand, a difference between the two secondary components.
• each difference is weighted as a function, for the difference considered, of the distance between the corresponding measurement points and the axis of rotation.
• the function F can be considered as a correction function for the measured values.
• K12 is a value in order to compensate for the difference in amplitude between the signals on the two measurement vectors, for example because of the position of the measuring elements.
• the gross angle b is a function of the orientation of the magnetic induction field Bm created by the permanent magnet at each of the measurement points, or is representative thereof.
• the magnetization of the magnetized body has a variable orientation depending on the angular position over an angular period T, as explained above, the magnetic induction field created by the magnetized body, in the internal volume delimited by the magnetized body 10, also has a variable orientation over an angular period, which is also symmetrical. It is possible to determine a relationship between the gross angle b and the relative angular position Q(t) between the two parts 14, 16.
• this relationship can be determined for example by calculation, by simulation, or by learning.
• this relationship can be determined for example by calculation, by simulation, or by learning.
• this external magnetic field Bext will be imposed by elements relatively far from the measurement elements, so that it will most often be possible to consider that this external magnetic field Bext is constant in direction and in intensity in the internal volume V delimited by the magnetic body 10.
• the magnetic induction Bm created by the permanent magnet in the internal volume V delimited by the magnetized body 10 is symmetrical with respect to the axis of rotation A.
• the vector of the magnetic induction Bm created by the permanent magnet in the internal volume V delimited by the magnetized body 10 has an orientation substantially constant.
• a sensor system 1 which is insensitive to the presence of an external magnetic field Bext which is constant in direction and in intensity.

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• 2021
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