Position sensor, in particular for detecting torsion of a steering column

Abstract

The invention relates to an angular sensor consisting of a magnetised rotor magnetic structure, a stator structure comprising two stator parts having teeth, a planar transverse stator extension, and a collector structure consisting of two flux-collection parts which define at least one air gap in which at least one magnetosensitive element is arranged, each collection part comprising: - at least one primary collector for contactless collection of the useful flux transmitted by the stator structure from the magnet and transferred via the stator extension; - - a secondary collector formed by one or more planar surfaces, located outside the zones of influence of the magnetised rotor magnetic structure; - a measurement zone formed by one or more planar surfaces and defining, together with the measurement zone of the complementary collection part, the one or more measurement air gaps in which the one or more magnetosensitive probes are accommodated, wherein these zones are connected to one another by extensions in order to ensure the transfer of the magnetic flux from the primary and secondary collectors to the measurement zone; - and wherein the collection parts are configured in such a way that, in the presence of a disturbing magnetic field, the axial flux captured by the secondary collectors is transferred to the measurement air gap in a direction opposite to that of the axial flux captured by the primary collectors and the stator structure, characterised in that the primary collectors interact magnetically in a contactless manner with the corresponding stator parts via an air gap defined by two planar surfaces belonging to the primary collector or to the stator part, wherein a planar extension of the stator part or a planar surface of the primary collector is respectively positioned.

Description

POSITION SENSOR, IN PARTICULAR FOR DETECTING THE TORSION OF A STEERING COLUMN Field of invention

[0001] The present invention relates to the field of position sensors for small angular travels, typically a few degrees. Such sensors are in particular associated with a torsion bar to measure the torsional torque. An example of application is the measurement of the torsion of a steering column, without this application being exclusive.

[0002] These position sensors are known to consist of a magnetic ring magnetized, preferably in the axial direction or in the radial direction, and in alternating directions, and of an assembly called a stator comprising two crowns provided with disc yokes extended by teeth. These teeth are either radially oriented and superimposed, or axially oriented and nested.

[0003] The flux from the magnet ring is collected by the two disc yokes and transmitted to a collector interacting without contact with an extension of the stator rings. This collector consists of two flux collection parts, two flat parts of which define at least one air gap in which at least one magnetosensitive element is placed.

[0004] An improved version of this type of short-stroke angular sensor provides secondary collectors intended to capture stray magnetic fluxes in an area not subject to the influence of the magnet. The axial component of this stray magnetic flux is also added to (or subtracted from, depending on its direction) the flux generated by the sensor magnet. To reduce sensitivity to external magnetic and electromagnetic fields disturbing the useful field detected by the Hall probe, these improved sensors provide for each flux collector structure two zones for collecting this disturbing field, respectively called the primary collection zone and the secondary collection zone, arranged in a particular way in relation to the measurement gap. The principle of these sensors consists of bringing the collected field into the measurement gap but in two different directions of circulation allowing the global component of the disturbing field to be cancelled. State of the art

[0005] The European patent EP3931065 is known in the state of the art, describing a sensor whose general principle consists in bringing the collected field into the measurement gap but in two different directions of circulation, ultimately making it possible to cancel the overall component of the disturbing field. With this in mind, it is sought, preferably but not limited to, to collect as much disturbing field with the primary collection zone as with the secondary collection zone and to reverse the two fields at the level of the gap, relatively to each other, thanks to the relative positioning of these two zones while maximizing the useful flux in this gap.

[0006] More particularly, by positioning a primary collection zone on one side of the transverse median plane defining the air gap and the secondary collection zone on the other side of the transverse median plane defining the air gap, there is created, by combining two flux collecting structures, a magnetic field reversal zone reversing the direction of the collected magnetic field crossing the air gap. The flux collected by the primary and secondary collection zones of the first collecting structure is canceled or minimized in cooperation with the flux collected by the primary and secondary collection zones of the second structure, as will be better appreciated in the various figures. This prior art solution relates to a position sensor, in particular intended for detecting the torsion of a steering column, consisting of a first rotor magnetized magnetic structure comprising a plurality of magnets,of a second stator structure comprising two extended crowns of axially oriented and nested teeth, and of a third fixed collector structure consisting of two flux collection parts which define at least one air gap in which at least one magnetosensitive element is placed, said flux collection parts and said toothed crowns defining between them a magnetic permeance independent of the relative radial and angular position of said second stator structure with respect to said third collector structure, said collection parts each comprising an angular collection sector characterized in that each collection part has at least one primary collection zone continued by at least one extension having at least one secondary collection zone,in that said secondary collection zones are terminated by flat expansions forming the two poles of said air gap and in that the transverse median plane of said air gap intersects at least one of said extensions.,

[0007] Patent application WO2020174171 is also known, proposing to create on each flux collector structure two zones for collecting this disturbing field, respectively called primary collection zones and secondary collection zones, arranged in a particular manner in relation to the measurement gap to bring the collected field into the measurement gap but in two different circulation directions, ultimately making it possible to cancel the overall component of the disturbing field. This solution proposes to collect as much disturbing field with the primary collection zone as with the secondary collection zone and to reverse the two fields at the level of the air gap, relatively to each other, thanks to the relative positioning of these two zones while maximizing the useful flux in this air gap.

[0008] Patent EP1464935 describes another known solution where the magnetic flux concentrator surrounds the magnetic flux rings. Fixed magnetic flux concentrators are designed so that the collecting surfaces are present on both sides of the rings. A single magnetic flux concentrator thus surrounds the adjacent ring, both inside and outside, instead of sweeping only one side.

[0009] Patent CN117581079 relates to a detection device comprising: a rotor; a stator arranged corresponding to the rotor; a first commutator arranged on a surface of the stator; and a second commutator arranged under the first commutator. The stator comprises a stator tooth comprising a body and a tooth, the first commutator comprises a first body and a first leg, the second commutator comprises a second body and a second leg, the first body and the second body are separable from each other, the body of the stator tooth is arranged between the first body and the second body, and the first leg and the second leg do not overlap each other in an axial direction. Therefore, the plurality of commutators, the magnetic resistances of which are differently formed, compensates for the variation in the output value due to the external magnetic flux, thereby enabling the detection device to achieve sufficient performance.

[0010] Disadvantage of the prior art

[0011] This solution known from the prior art has the disadvantage of sensitivity to the precision of the axial positioning of the sensor elements. When the two stators are not perfectly positioned, whether axially or transversely, the flows captured by the primary collectors are altered and the precision of the angular measurement suffers, especially since these sensors are intended to measure very small angular variations, resulting from the torsion of a column for example; and any loss of precision results in an error in the measurement of the torque applied to the column in this case.

[0012] Solution provided by the invention

[0013] In order to overcome this drawback, the present invention relates to an angular sensor consisting of a magnetized rotor magnetic structure, a stator structure comprising two stator parts having teeth, a plane transverse stator extension, and a collector structure consisting of two flux collection parts which define at least one air gap in which at least one magnetosensitive element is placed, each collection part having:

[0014] a) at least one primary collector for collecting without contact the useful flux transmitted by the stator structure from the magnet and transferred via said stator extension,

[0015] b) a secondary collector formed by one or more flat surfaces, located outside the zones of influence of said rotor magnetized magnetic structure,

[0016] (c) a measuring area formed by one or more flat surfaces and defining, with the measuring area of ​​the complementary collection part, the measuring air gap(s) in which the magneto-sensitive probe(s) are housed,

[0017] d) these zones being connected to each other by extensions to ensure the transfer of the magnetic flux from the primary and secondary collectors to the measurement zone,

[0018] e) said collecting parts being configured in such a way that in the presence of a disturbing magnetic field, the axial flux captured by the secondary collectors is transferred to the measuring air gap in a direction opposite to that of the axial flux captured by the primary collectors and the stator structure,

[0019] characterized in that said primary collectors interact magnetically without contact with the corresponding stator parts by an air gap defined by two flat surfaces belonging to said primary collector or to said stator part, and in which is positioned respectively a flat extension of said stator part or a flat surface of said primary collector.

[0020] In particular, it relates to a sensor having all or part of the following characteristics.

[0021] The outer flat surfaces have a smaller surface area than the associated inner flat surfaces.

[0022] Each of the two collection zones defines between them an air gap in which said transverse flat stator extension is positioned.

[0023] The extension of each of the two stator parts has a peripheral groove formed of two transverse flat surfaces separated by said air gap, a flat surface of the primary collector being positioned in said groove.

[0024] Each of the two collectors further comprises a secondary collection zone formed by one or more flat surfaces, located outside the zones of influence of said rotor magnetized magnetic structure, said zones being connected to each other by extensions to ensure the transfer of the magnetic flux from the primary and secondary collectors to the measurement zone, said zones being configured such that in the presence of a disturbing magnetic field, the disturbing field captured by the first collector is transferred to the measurement gap in a direction opposite to that of the disturbing field captured by the second collector.

[0025] Said two outer primary collection planar surfaces have a collection area less than the area of ​​said two inner primary collection planar surfaces.

[0026] The said teeth are axially oriented and nested.

[0027] Said teeth are oriented radially and positioned in two axially offset planes.

[0028] Said teeth are oriented radially and positioned in the same axial plane.

[0029] The said collection pieces are made from cut and folded sheet metal.

[0030] The said collection pieces are identical but arranged relatively according to a central symmetry.

[0031] All the magnetosensitive elements are arranged on the same electronic card perforated at the level of the probes to accommodate one of the flat surfaces forming the air gap.

[0032] The invention also relates to a system for measuring the torque and angle of a part in rotary motion, integrating an angular sensor as stated above to measure the torsion between two ends of said part in relative motion, and all or part of the following characteristics: it further comprises two mobiles driven in rotation by said part in relative motion through a reduction of movement, the measurement of the position of the two mobiles making it possible to obtain the absolute position, over several revolutions, of the part in rotary motion, it further comprises a mobile driven in rotation by said part in relative motion through a reduction of movement, the measurement of the angular position of the mobile and of the part in rotary motion making it possible to obtain the absolute position, over several revolutions,of the rotating part, the position measurement of the two moving parts is carried out by means of magneto-sensitive probes arranged on the electronic card supporting the at least one magneto-sensitive element allowing the measurement of the torque. Detailed description of a non-limiting example of embodiment,

[0033] The present invention will be better understood on reading the following description, concerning non-limiting examples of embodiment illustrated by the appended drawings where:

[0034] Larepresents a schematic view of an embodiment of a sensor according to the invention,

[0035] It represents a detail view of the,

[0036] The figure represents a perspective view of a first variant embodiment of a sensor according to the invention with axial collection by the toothed structure of the magnet flux stator,

[0037] La represents a schematic view of an alternative embodiment of the primary collection zone of a sensor according to the invention,

[0038] The represents a perspective view of an alternative embodiment of a sensor according to the invention with radial collection of the magnet flux by the toothed structure of the stator,

[0039] The figure represents a schematic view of an alternative embodiment of a sensor according to the invention with unilateral axial collection of the magnet flux by the toothed structure of the stator,

[0040] The figure represents a schematic view of a sixth variant embodiment of a sensor according to the invention with an asymmetrical primary collection zone.

[0041] General principle of the invention

[0042] The angular position sensor according to the invention is intended for measuring low amplitude angular variation. Such a sensor is in particular intended to measure the angular displacement of two parts of a torsion bar, for example on a steering column, allowing angular measurement on a column which can rotate several turns.

[0043] Such sensors are known and provide flux collection parts interacting magnetically with a magnet magnetized in a direction perpendicular to the plane of the collection parts; these collection parts forming a magnetic path for transferring the flux to an air gap in which a magneto-sensitive sensor is arranged. The invention provides a solution to the problem of sensitivity to positioning defects, resulting in an alteration of the flux transmitted between the stator parts and the collection parts.

[0044] The solution proposed by the invention consists of symmetrizing the collection surfaces with respect to a reference positioning. For this, each flux exchange zone between the stator parts and the collection parts has a configuration where the surface of one part is sandwiched in the air gap formed by a pair of surfaces of the complementary part. Thus, in the event of a positioning error leading one of the collection parts to be offset with respect to the complementary stator part, compensation is automatically made between the abnormally close surfaces and the abnormally spaced surfaces.For this purpose, each collection zone comprises two complementary intertwined parts having ferromagnetic parts located in parallel surfaces, preferably flat surfaces, these parallel surfaces being perpendicular to the direction of the flux to be transmitted, one of the two parts having two parallel surfaces defining between them an air gap in which the collection surface of the complementary part is arranged, itself parallel to the two parallel surfaces defining the air gap. These surfaces are generally flat, but in cylindrical configurations, they can also be semi-cylindrical and, of course, parallel.

[0045] The sum of the fluxes collected by the surface inserted in the air gap will therefore always be identical, whatever its position (in the direction perpendicular to the collection surface) inside the air gap. This solution makes it possible to neutralize the positioning defects of the different components of the sensor.

[0046] The magnetization is orthogonal for the magnetic interaction between the magnet and a surface of the so-called "stator" parts (210, 220) facing each other. Compared to the collection parts (300, 400) perpendicularity is not necessary, it can be imagined that there is an angle return within the stators which implies that the exchange of flux between the stator and the collection part is not carried out in a manner collinear with the magnetization direction. It is the air gap between the stator parts (210, 220) and the collection parts which is necessary so that the stator parts can transfer the flux without contact with the collection parts which can be in relative motion with respect to the stator parts.

[0047] The general schematic principle of such a sensor is represented in figures 1 and 2. The diagram shows a radial section of the sensor at the level of a probe, the magnets and the stators collecting the magnet flux being parts of revolution. The diagram shows a detailed view of the air gap between a part of the stator and a part for collecting the flux to convey it to the detection probe. The sensor comprises in a known manner a magnetized ring (100) having, for example, an alternation of magnets magnetized axially, in opposite directions.

[0048] This magnetic ring (100) is integral with one of the parts of the torsion bar; the other part is integral with a stator (200) formed of two interdigitated toothed stator parts (210, 220) (the teeth of which are not visible in, but are illustrated in subsequent embodiments).

[0049] Eventually, the column containing the torsion bar is itself rotating, over several turns, the advantage of this sensor being that the driven elements are only the magnetic ring and the stator, while the measuring probes remain fixed, which avoids any wiring problems.

[0050] For other applications, the magnetic ring (100) is integral with a part in relative rotation with respect to a second coaxial part integral with at least one of the stator parts, the collectors, the probe(s), and the electrical connections being integral with a fixed frame, which allows a relative rotation of the two coaxial parts with respect to this fixed frame.

[0051] The measurement of the angular displacement of the magnetized ring (100) relative to the stator (200) is done by measuring the variation of the flux passing through the two stator parts (210, 220), by means of two complementary collection parts (300, 400), one of the collection parts (300) interacting magnetically without contact with a plane extension (211) of one of the stator parts (210), and the other collection part (400) interacting magnetically without contact with a plane extension (221) of the other stator part (220).

[0052] The collection parts (300, 400) are provided with flat extensions (330, 430) forming between them a measuring gap (500) in which a magneto-sensitive probe (600) is housed. Said flat extensions (330, 430) are respectively magnetically and mechanically connected to the primary collection zones (310, 410) by means of flux conductors (360, 460).The magnetic interaction between the collection part (300; 400) and the associated stator part (210; 220) is achieved via an annular air gap (510; 520) defined by two axially separated transverse planar surfaces (311, 312; 411, 412), these surfaces being formed either on the stator parts (210; 220), in the form of a peripheral groove in which one end of the primary collection parts (300; 400) is engaged, called the primary collection zone (310; 410); or on the primary collection zones (310; 410), in the form of axially offset surfaces to define an air gap (510; 520) inside which the stator extension (211; 221) is positioned. This configuration of transmission of the magnetic flux between the stator structure (200) and the collection parts (300; 400) with multiple air gaps makes it possible to inhibit the effects of poor axial or oblique positioning of the stator relative to the flux collector.In fact, we define the distance. between a first transverse flat surface (311) of the primary collection zone (310) and the stator extension (211) and the distance between the axially offset transverse flat surface (312) of the primary collection area (310) and the stator extension (211). In an ideal case, the distances And are identical, but they may differ depending on manufacturing tolerances, one may be increased at the expense of the other, respecting the relationship , being a constant. The invention has the effect that, when these distances vary, one of the surfaces (311, 312) collects more flux because the distance decreases, while the other collects less flux because the distance increases, on the other hand the total flux collected by the two surfaces together remains identical. The same advantage applies when there is a lack of parallelism between the stator extension (211) and the transverse flat surfaces (311, 312). This overall reasoning applies identically to the second collection part (400).

[0053] This configuration provides an improvement to angular sensors having magnetic flux guides in general, and is of particular interest for improved angular sensors where the collector is configured to have secondary collectors to overcome external magnetic disturbances.

[0054] General principle of the invention improved

[0055] In a preferred version and as seen in, the collection parts (300, 400) are also provided with secondary collection areas (340, 440) intended to collect a disturbing magnetic flux (150). These secondary collection areas (340, 440) are respectively magnetically and mechanically connected to the planar extensions (330, 430) via flux conductors (365, 465). The primary collection zones (310, 410), as well as the stator structure (200), are also capable of collecting disturbing magnetic flux (150), the secondary collection zones (340, 440) being arranged, relative to the primary collection zones (310, 410), such that the disturbing flux (115) conveyed by one collection part (300) through the probe (600), opposes the disturbing flux (116) conveyed by the other collection part (400) through said probe (600).It is important to note that only a portion of the disturbing flows is exchanged between the two collection parts, a large portion remains in the collector and is routed between the primary collection zone and the secondary collection zone of the same collector. The essential thing to benefit from the invention is that the disturbing flows exchanged between the two structures compensate each other.

[0056] In other words, the secondary collection zones (340, 440) capture the parasitic flows and bring them towards the measurement gap (500) in a direction opposite to that of the flow captured by the primary collection zones (310, 410).

[0057] The invention is particularly interesting in this case, in fact, an axial positioning defect induces, in the solutions described in patent EP3931065, an alteration of the compensation of the parasitic magnetic fields. If the positioning of the primary collectors is offset from the nominal positioning, the compensation of the parasitic fluxes captured by the secondary collectors is distorted and the insensitivity with respect to the disturbing fields is no longer respected. The invention therefore makes it possible to judiciously overcome this problem and more particularly with regard to disturbing magnetic fields not collinear with the axial direction.

[0058] The invention relates to the fact that the magnetic flux coming from each of the stator parts (210, 220) and collected by the corresponding primary collector (310, 410) via a double air gap (510; 520)

[0059] a) in the first embodiment, corresponding to the diagram of the, the primary collector (310; 410) defining an air gap delimited by two parallel flat surfaces (311, 312; 411; 412) between which the flat extension (211, 221) of the corresponding stator part (210, 220) is positioned, and

[0060] b) in another embodiment, illustrated by the diagram of the, the stator part (210, 220) having a peripheral groove with rectangular section, at its extension (211, 221) of which the two transverse flat surfaces (213, 214; 223, 224) define an air gap (510; 520), the primary collector (310; 410) then appearing in the form of a flat surface (311) positioned between these two transverse flat surfaces (213, 214; 223, 224).

[0061] Generally speaking, the two collection parts (300, 400), like the stator parts (210; 220), are each made from the same cut and folded ferromagnetic sheet, the different parts constituting these elements are therefore arranged to minimize the sheet surface lost during the cutting process, this making it possible to minimize the number of parts to be assembled while minimizing the production cost. Nevertheless, the person skilled in the art could choose to use other known production methods, such as machining or three-dimensional printing, but also to produce the collection parts in multiple sub-parts which are assembled, by welding, riveting, screwing, or any other known means, to form the collector.

[0062] Typically, manufacturing and assembly tolerances for such a sensor are, for axial and lateral positioning, 0.2 millimeters, and for the air gap height, 0.7 millimeters.

[0063] The invention makes it possible to avoid degradations in the measurement of the main field of the magnet (100) caused by a disturbing field (150) in all directions of incidence.

[0064] Detailed description of a first embodiment

[0065] Illustrates a first embodiment according to the invention. In this first embodiment, the magnet (100) has a disc shape and is axially surrounded by the stator parts (210, 220) having the shape of crowns from which teeth (230, 240) extend on the internal periphery, which extend axially in the direction of the magnet (100) and then radially in the direction of the center of the magnet, to provide trapezoidal surfaces collecting the flux of the magnet. The magnet has a multiplicity of axially magnetized poles to promote the coupling of the flux in the teeth (230, 240) of the two stator parts (210, 220). Each stator part carries a number of teeth equal to the number of pairs of poles of the magnet, these teeth being equally distributed angularly on the periphery of the magnet.The teeth of one stator part (210) are out of phase with the teeth of the other stator structure (220) such that when the teeth of one structure face north poles of the magnet (100) the teeth of the other structure face south poles.

[0066] Each collection part (300, 400) is formed by a cut and folded ferromagnetic sheet or by an assembly of cut and folded ferromagnetic sheets, ensuring the routing of the flux, emanating from the magnet (100) and then conducted by an extension (211, 221) of one of the stator parts (210, 220), to the measuring gap (500) where the magnetosensitive probe (600) is located, or to a plurality of measuring gaps (500) in which a probe (600) is each arranged, if it is desired to improve the robustness of the measurement by a redundant measurement (the probe arranged in one of the gaps (500) having been removed to improve readability).

[0067] The sensor comprises two collection parts (300, 400), one for each of the stator parts (210, 220). They are arranged to together form the air gap(s) (500) where the magnetosensitive probe(s) (600) are positioned.

[0068] Each of these collection parts (300, 400) has two imperative areas of interest, namely a primary collection area (310, 410) and the measurement area, and optionally an additional area of ​​interest consisting of a secondary collection area (340, 440), making it possible to reduce or even cancel out the disturbances produced by sources of parasitic fields comprising an axial component. These areas of interest are:

[0069] - The first collection zone (310; 410), also called "primary collector", which is formed by an inner flat surface (312; 412) and an outer flat surface (311; 411), these inner (312; 412) and outer (311; 411) surfaces being flat collection surfaces, preferably parallel, defining between them an air gap (510; 520) in which is positioned a flat stator extension (211; 221) of one of the stator parts (210; 220) to collect without contact the useful flux transmitted by the stator (200) from the magnet (100) and transferred via this stator extension (211; 221), this insertion of a stator extension (211; 221) leads to separating the air gap (510; 520) into two air gaps (511, 512; 521, 522), we thus speak of a double air gap (510; 520)

[0070] - A second collection zone (340; 440) – specific to the “improved” variants, also called “secondary collector” and which is formed by one or more flat surfaces, located outside the magnetic influence zones of the magnet (100), preferably parallel to the flat surfaces of the primary collection zone (310; 410)

[0071] - A third zone (330; 430), also called “measuring zone”, formed by several flat surfaces and defining with the third zone of the complementary collection part (400; 300) the measuring air gap(s) (500) in which the magneto-sensitive probe(s) (600, 610) are housed.

[0072] These three zones (310, 330, 340; 410, 430, 440) are connected by extensions (360, 365; 460, 465) ensuring the transfer of the magnetic flux from the primary (310; 410) and secondary (340; 440) collection zones to the measurement zone (330; 430).

[0073] These collection parts (300, 400) are configured such that in the presence of an axial magnetic field, the axial flux captured by the secondary collection zones (340, 440) is transferred to the measuring air gap in a direction opposite to that of the axial flux captured by the primary collection zones (310, 410) and by the stator (200).

[0074] The compensation of the disturbing fluxes is obtained by the fact that the primary collectors (310, 410) mainly collect the flux emanating from the magnet (100), and corresponding to the useful signal, but also collect “parasitic” flux, whereas the secondary collectors (340, 440) collect only “parasitic” fluxes. The “parasitic” fluxes captured by the primary collectors (310, 410) and secondary collectors (340, 440) are, due to the reversal of direction, compensated or even cancelled, whereas the flux emanating from the magnet (100), which is not captured by the secondary collectors, is measured in full by the magneto-sensitive probe(s) (600).

[0075] Note that in this embodiment, the multiple flat surfaces of the measurement zone (330; 340) of each of the collectors (300; 400) are located at the ends of multiple extensions (360, 361; 460, 461) extending from the inner surface (312; 412) of the first collection zone (310; 410). Thus, the extension (365; 465) does not directly connect the second collection zone (340; 440) to the measurement zone (330; 340), as shown in, but does so via the extensions (360, 361; 460, 461). This embodiment is however not specific to multiple air gaps (500) and the person skilled in the art could easily imagine adapting the configuration of the, where the extension (365; 465) directly connects the second collection zone (340; 440) to multiple air gaps, or only providing a single air gap (500) in the embodiment presented in.

[0076] It can also be noted that preferably the surface area of ​​the outer collecting surfaces (311, 411) of the primary collectors (300, 400) is less than the surface area of ​​the inner collecting surfaces (312, 412), this leads to better compensation of the radial disturbing field while avoiding impacting the compensation of the axial disturbing field.

[0077] In this variant, the collection parts (300, 400) have mechanical and magnetic continuity between the primary collection zones (310, 410) and the secondary collection zones (340, 440), however the person skilled in the art could easily envisage that the secondary collection zones are made in an additional part which is mechanically and magnetically coupled, or even only magnetically coupled, to the primary collection zone of the associated collector. The mechanical coupling could be done by welding or any other fixing means known to the person skilled in the art. The absence of mechanical coupling between these parts can be favorable from an industrialization perspective where it is necessary to meet different specifications, and for example avoid introducing the part comprising the secondary collection zones (340, 440), when the robustness of the sensor to disturbing fields is not necessary.

[0078] Description of an alternative embodiment

[0079] Illustrates an alternative embodiment according to the invention. This embodiment differs from the first detailed embodiment visible in that the magnet (100) has a ring shape, the teeth of the stator parts (210, 220) erecting axially at the periphery of this magnet and in the direction of the other stator part (220, 210). The teeth of the two stator parts (210, 220) interlock to form an interdigitated structure. This embodiment makes it possible to clear a cylindrical space in the center of the ring magnet to, for example, mount the sensor on an axis such as that of a steering column.

[0080] This embodiment also differs in that the outer planar surface (311) of the first collection area (310) is divided into two segments (316, 317). The second collection part (400) is also concerned, although the segments of the outer planar surface of the first collection area are not visible. This embodiment is particularly well suited to producing the collection parts (300, 400) from a cut and folded ferromagnetic sheet. Indeed, the arrangement in two segments allows more space to be left in the central area of ​​the sheet for the planar extensions (330, 340) creating the air gap and for the flux conductors (360, 460) for conveying the magnetic flux from the first collection area (310, 410) to the associated planar extension (330, 340). The outer flat surface (311) can be adjusted to the desired size by increasing the extent of the segments (316, 317) in the circumferential direction as desired.

[0081] Preferably, and as presented in, the collection parts (300, 400) have an identical geometry and are only oriented in opposite directions to form the collector structure. This has the effect of simplifying the industrial tooling and reducing production costs, nevertheless this embodiment is not limiting of the invention in that the gain is only economic and the use of two non-identical collectors (300, 400) can make it possible to improve the size of the device.

[0082] Description of an alternative embodiment

[0083] Illustrates an alternative embodiment with axial collection of the flux of the magnet (100). This embodiment differs from the embodiment presented in that the teeth (230, 240) of the two stator parts extend radially from the same side of the magnet (100), so that these teeth (230, 240) are nested when the stator is assembled. This embodiment makes it possible to minimize the axial size at the center of the structure by freeing up one entire side of the magnet, this space can then advantageously be used to house another component, such as a sensor, or for a support part to fix the magnet (100) on its axial surface.

[0084] It can also be noted that this embodiment shows two probes (600, 610) each housed in a measuring gap (500) produced by two sets of flat surfaces (330, 430).

[0085] As with the embodiment shown in, the outer planar surface (311, 411) of each of the collectors (300, 400) is mechanically and magnetically bonded to the inner planar surface (312; 412) by an extension (368; 468) extending from the space between the extensions (360, 361; 460, 461). The inner planar surface (312; 412) flares over an angular extent limited by the extension (365; 465) bonding the inner planar surface (312; 412) to the secondary collection area (340; 440). The length of the extension (368; 468) is chosen relative to that of the extensions (360, 361; 460, 461) so that these elements can be cut from the same piece before being folded, the outer surface extending beyond the extensions (360, 361; 460, 461).

[0086] Description of an alternative embodiment

[0087] Illustrates an alternative embodiment of the collector parts (300; 400) for which the outer flat surface (311; 411) is produced in a single segment, the latter not being centered relative to the inner flat surface (312; 412).

[0088] Other embodiments not shown are possible and the person skilled in the art would easily be able to adapt the configuration of other known structures to obtain the effects of compensation of the transverse field as beneficial to the invention. For example, he could imagine orienting the measuring air gap (500) in the axial direction, as presented in international patent application WO2020174170 rather than in the radial direction presented in this document. He could also imagine other variations of primary collectors (310, 410) by drawing inspiration from the variants proposed in international patent application WO2020174171, the whole being to be able to propose a double collection air gap at the level of the primary collector so as to compensate for poor positioning as taught in this document.

[0089] Furthermore, in a manner usually known to those skilled in the art, the at least one magnetosensitive element (600, 610) arranged in the measuring air gap(s) (500) are preferably arranged on an electronic card, this electronic card being advantageously perforated below the magnetosensitive elements to house one of the flat surfaces (330, 430) forming the magnetic air gap. This makes it possible to minimize the thickness of the magnetic air gap to the strict minimum, i.e. the thickness of the magnetosensitive element. The magnetosensitive element is usually mechanically and electrically connected to the electronic card via its connection pins, which extend transversely on either side of the magnetosensitive element, the area of ​​the electronic card located under the electronic chips therefore generally does not provide a mechanical support role and is potentially only used to route the electrical signals of said chips.The opening of the electronic card is therefore not a critical operation.

[0090] Integration of an absolute position sensor

[0091] As we have stipulated, the invention relates to the measurement of relative angular position between a magnetized ring and a so-called stator structure and is perfectly suited to small relative angular displacements between these two structures. This sensor is therefore used in particular in the context of the measurement of torque applied to parts in rotary motion, such as steering column shafts, and likely to undergo an angular deformation proportional to the torque between its ends. The securing of the magnetized ring at one end and the securing of the structure at the other end therefore makes it possible, by measuring the displacement, to know the applied torque. It is also sometimes necessary to know the absolute angular position of the part in rotary motion, and this over several revolutions. For this, known solutions, as for example described by the applicant's international patent application WO2012025683A1, exist.They consist of using two additional position sensors measuring the angular displacement of two mobiles set in rotation by the rotating element through a mechanical reduction or by direct drive. The two additional position sensors are capable of measuring the complete revolution of each of the mobiles in an absolute manner. By opting for different reduction sets for each of the mobiles, the desired information can be obtained using different strategies.For example, one of the two mobiles can rotate synchronously with the rotating part, the torque of which is measured, and therefore obtain the absolute angular position within a revolution, while the other mobile can have a reduction in movement to perform a single revolution when the rotating part performs several, the knowledge of the reduction allowing, with the measurement of the absolute value of the second mobile, to know the number of revolutions performed by the rotating part. We then speak of the use of a fine sensor and a coarse sensor. The precision of the measurement can be improved within a revolution using a technique described in the previously cited patent application.The first angular position sensor is associated with a multipolar magnetic ring directly supported by the rotating part and makes it possible to measure the absolute position within a magnetic period and therefore a portion of the revolution of said rotating part. The second sensor is associated with a mobile driven by a reduction of movement and is capable of discriminating the increment of these magnetic periods over several revolutions.

[0092] Another strategy consists of using a different reduction for the second mobile, close to 1 but different from 1, so that the two position signals have an increasingly large difference depending on the number of revolutions made. The first mobile therefore always makes it possible to obtain the absolute position within a revolution and the number of revolutions made is obtained by a recomposition of the signals from the two probes making it possible to obtain their rotation difference. The capture of these additional signals can be done in an integrated manner with the object of the invention, in particular by proposing to use the same electronic card to support all the position probes, but also by taking advantage of the peripheral space around the collectors of the stator structure to integrate the movement reduction systems and the mobiles in a restricted space.

[0093] Sizing and positioning of the useful flow collecting surfaces

[0094] This is a detailed view of an isolated collector (300), according to a particular embodiment. The relative dimensioning of the different collecting surfaces of these collectors (300), namely the inner flat surface (312), the outer flat surface (311) and the secondary collection zone (340), meets two objectives: Maximizing the collection of the magnet magnetic flux, useful for measurement, by the primary collection zone (310) and more particularly by the inner flat surface (312) and the outer flat surface (311), Minimizing the disturbing field at the measurement gap.

[0095] Maximizing the collection of magnetic flux useful for measurement is obtained by maximizing the surface area of ​​the primary collection zone (310) opposite the stator extension (210), namely the inner flat surface (312) and the outer flat surface (311).

[0096] The minimization of the disturbing field in the measuring gap is achieved by two effects: Compensation of the disturbing field of axial incidence, which is mainly collected by the outer flat surface (311) on the one hand and by the secondary collection area (340) on the other hand. The minimization of the disturbing field at the probe is achieved as a compromise between the surface area of ​​these two surfaces and their joint minimization makes it possible to optimize the size. In second order, the disturbing field collected by the stator parts (210, 220) and the inner flat surface (312) can also have an effect and be integrated into a finer optimization level.The compensation of the radial incidence disturbing field, and more particularly that in the x direction, which is mainly collected by the stator parts (210, 220) and by the secondary collection zone (340), is directly linked to the permeance between the primary collection zone (310) and the stator extension (211) and therefore depends on the facing surfaces and the air gap between these surfaces. An optimization of the compensation aims to cancel the disturbing field at the probe and makes it possible to minimize the sensitivity to variations in the positioning of the collectors (300, 400) relative to the stator parts (210, 220). This optimization is obtained either by a play of the surfaces of the inner (312) and outer (311) flat surfaces, or by a voluntary imbalance of the air gaps (511, 512). This imbalance, for example by having. makes it possible to promote the magnetic coupling of the stator extension (211) with the outer flat surface (311) and makes it possible to compensate for the imbalance between the surface areas of the inner (312) and outer (311) flat surfaces.

[0097] The relative dimensions between the outer planar surface (311), the inner planar surface (312) and the secondary collection area surface (340) depend on the geometry used, but providing a smaller area of ​​the outer planar surface (311) than that of the inner planar surface (312) is a generic sizing rule to improve the linearity of the sensor and its signal-to-noise ratio.

[0098] This principle is also valid when the outer flat surface (311) is composed of multiple segments (316, 317), as presented in, the surface area to be considered is then that of the sum of the surface areas of the segments. This teaching is also valid in the case where the inner and outer flat surfaces are produced by the plane extension of a stator part, as presented in.

[0099] Integration of a sensor according to the invention for measuring the torsion of a shaft

[0100]

[0101]

[0102] Figures 9 to 11 illustrate an example of integration of a torque sensor according to the invention. Lpresenting an exploded perspective view of the components of the stator assembly before assembly, lpresenting also a perspective view in another orientation with an additional explosion of the collectors, and lpresents a perspective view from below of the stator assembly in the final state and integrated into a torsion shaft (1).

[0103] More specifically, the sensor comes in the form of multiple sub-parts with easy assembly; these sub-parts can be independently produced on different manufacturing lines and assembled at the end of a dedicated assembly line.

[0104] A first subassembly consists of a main support part (700), preferably made of plastic, for receiving the electronic card (650) and for assembling the other parts. The main support part also allows the stator structure (200) to be received. More particularly, it allows a stator support (550) to be guided. The stator support (550) has a tubular part that is inserted with very slight play into a cylindrical cavity (710) of the main support part (700) so as to form a plain bearing to obtain free rotation of the stators relative to the main support part (700). The tubular part of the stator support has slots opening alternately at one axial end or the other so as to receive the teeth of the stator parts (210, 220) during their axial insertion. Note that in the, only the upper stator part (210) is visible.The angular positioning of the stator parts is obtained thanks to the cooperation of pairs of pins (565) defining between them a housing capable of receiving tabs (219) of the stator part. The precise axial positioning is obtained by the abutment of the extension (211) of the stator part (210) against multiple shoulders (560) forming the base of the pins (565). The securing of the stator part (210) is obtained by a process of riveting the pins (565) after positioning. Note that the second stator part (220) (not visible) is positioned in a second step in the opposite direction and secured using completely similar means. Thus the stator support ensures the precise relative angular and axial positioning of the two stator parts (210, 220). The main support part (700) comprises a housing (720) for accommodating the electronic card (650) supporting the magneto-sensitive probe (600).The assembly of the stators consists first of all in inserting a stator (210) on the stator support (550), inserting the whole thing into the main support part (700) until the stator support (550) is axially stopped against the main support part (700). Finally the second stator is inserted into the stator support (550), axially stopped against the latter and secured using the previously mentioned riveting process.

[0105] A second collector subassembly consists of a collector support (800), preferably made of plastic, allowing the positioning and holding of the collection parts (300, 400). In this exemplary embodiment, and as shown in the, where this second subassembly is in exploded view before assembly, it is provided that the assembly of the collection parts (300, 400) on the collector support (800) is done in orthogonal directions. Grooves (830, 840) are thus provided to allow the passage of the extensions (360, 460) to their final position in which they form the measuring gap (500). The collector support (800) also offers flat support surfaces (850), cooperating with flat surfaces of the collectors, such as, for example, the second collection zones (340, 440), to allow the precise relative positioning of the collection parts (300, 400).The collection parts are held in place by pins (880, 890) provided on the external radial face of the collector, which cooperate with notches (380, 480) in the collection parts, said pins (860, 865) being deformed by punching after assembly to eliminate any freedom of movement of the collection parts (300, 400).

[0106] The first and second sub-assemblies are relatively positioned during their assembly by means of centering pins (760, 770) provided in the main support part (700) and cooperating with holes (860, 870) of the collector support (800), a groove (780) of the main support part (700) cooperating with a rib (810) making it possible to ensure long guidance, these two means making it possible to obtain precise axial positioning and rough radial guidance. Precise centering is ensured by the support of a "V"-shaped protuberance (820) providing two flat supports (821, 822) with a cylindrical surface (750) of the main support part (700). The good axial guidance of the collector support with the main support part makes it possible to minimize the air gap (500) between the extensions (360, 460) while ensuring the good insertion of the magnetosensitive probe (600) in said air gap during this operation.It can also be noted that the electronic card (650) is perforated under the magnetosensitive probe (600) to reduce the air gap to a minimum.

[0107] The first and second subassemblies are held in place after their positioning by using a cover (900), an upper cover (950) and a lower cover (980), preferably made of plastic. The upper cover (950) and the lower cover (980) are first inserted axially and secured. The upper cover (950) is secured by embedding studs (735) of the main support part (700) in barrels (951) of the upper cover (950), making it possible in particular to press the electronic card (650) and to seal the housing (720) of the electronic card (650). The upper cover (950) is secured by means of clips (985) of the lower cover (980) cooperating with complementary means (736) of the main support part (700).The cover (900) is then slid laterally by means of guide rails (910) cooperating with complementary rails (955) provided in the main support part (700) (not visible) and the upper cover (950). The cover (900) also has clips (930) cooperating with complementary means (730, 956, 986) of the main support part (700), the upper cover (950), and the lower cover (980) to obtain a firm anchoring on the latter. The cover (900) also has, on an internal face, flexible blades (920) coming to bear on a flat surface (825) of the collector support (800) so as to ensure its maintenance in position without overstressing the assembly.

[0108] Adding an angular position sensor

[0109] Illustrates the addition of a multi-turn absolute angular position sensor to the torque sensor shown in Figures 9 to 11. The lower part of the main support part (700) for two toothed sensor wheels (781, 782) meshing with a toothed wheel (785) secured to the sleeve (10) secured to the torsion shaft (not visible), the two toothed sensor wheels (781, 782) have a different number of teeth to present a different angular displacement during rotation of the torsion shaft. Each of said sensor wheels is provided with a magnet with a pair of poles, for example of diametrical magnetization, each facing a magneto-sensitive probe (not visible) secured to the lower part of the electronic card, capable of measuring in an absolute manner the rotation of the associated sensor wheel over one revolution. The lower cover (980) has an interior space to accommodate the various gear wheels (781, 782, 785)

[0110] The angular information obtained by each of the magneto-sensitive probes allows, by combining the signals and by knowing the reduction ratio between the sensor wheels and the torsion shaft, to know in an absolute manner the angular position of the torsion shaft and this potentially over several revolutions.

Claims

Angular sensor consisting of a rotor magnetized magnetic structure (100), a stator structure (200) comprising two stator parts (210, 220) having teeth (230, 240), a planar transverse stator extension (211, 221), and a collector structure consisting of two flux collection parts (300, 400) which define at least one air gap (500) in which at least one magnetosensitive element (600, 610) is placed, each collection part (300, 400) havinga) at least one primary collector (310, 410) for collecting without contact the useful flux transmitted by the stator structure (200) from the magnet (100) and transferred via said stator extension,b) a secondary collector (340, 440) formed by one or more planar surfaces, located outside the zones influence of said rotor magnetized magnetic structure,c) a measurement zone formed by one or more flat surfaces (330, 430) and defining,with the measurement zone of the complementary collection part (400, 300), the measurement air gap(s) (500) in which the magnetosensitive probe(s) (600, 610) are housed,d) These zones being connected to each other by extensions (360, 365, 460, 465) to ensure the transfer of the magnetic flux from the primary (310, 410) and secondary (340, 440) collectors to the measurement zone,e) Said collection parts (300, 400) being configured such that in the presence of a disturbing magnetic field (150), the axial flux captured by the secondary collectors is transferred to the measurement air gap (500) in a direction opposite to that of the axial flux captured by the primary collectors (310, 410) and the stator structure (200),characterized in that that said primary collectors (310, 410) interact magnetically without contact with the stator parts (210,220) corresponding by an air gap (510; 520) defined by two flat surfaces respectively external (311; 411; 213; 223) and internal (312; 412; 214; 224) belonging to said primary collector (310; 410) or to said stator part (210; 220), and in which is positioned respectively a flat extension (211; 221) of said stator part (210; 220) or a flat surface (311; 411) of said primary collector (310; 410)., Angular sensor according to claim 1 characterized in that the external flat surfaces (311; 411; 213; 223) have a smaller surface area than the associated internal flat surfaces (312; 412; 214; 224). Angular sensor according to claim 1 characterized in that each of two collection zones (311, 312; 411, 412) define between them an air gap (510, 520) in which said transverse plane stator extension (211, 221) is positioned. Angular sensor according to claim 1 characterized in that the extension (211, 221) of each of the two stator parts (210, 220) has a peripheral groove formed of two transverse flat surfaces (213, 214; 223, 224) separated by said air gap (510, 520), a flat surface (311, 411) of the primary collector (310, 410) being positioned in said groove. Angular sensor according to claim 1 characterized in that each of the two collectors (300, 400) further comprises a secondary collection zone (340, 440) formed by one or more flat surfaces, located outside the zones of influence of said rotor magnetized magnetic structure, - said zones being connected to each other by extensions (365, 465) to ensure the transfer of the magnetic flux from the primary and secondary collectors to the measurement zone (330, 430), - said zones being configured such that in the presence of a disturbing magnetic field (150), the disturbing field (115) captured by the first collector (300) is transferred to the measurement air gap in a direction opposite to that of the disturbing field (116) captured by the second collector (400). Angular sensor according to claim 1 characterized in that said two outer primary collection plane surfaces (311, 411) have a collection area smaller than the area of ​​said two inner primary collection plane surfaces (312, 412). Angular sensor according to claim 1 characterized in that said teeth (230, 240) are axially oriented and nested. Angular sensor according to claim 1 characterized in that said teeth (230, 240) are oriented radially and positioned in two axially offset planes. Angular sensor according to claim 1 characterized in that said teeth (230, 240) are oriented radially and positioned in the same axial plane. Angular sensor according to claim 1 characterized in that said collection parts (300, 400) are made from a cut and folded sheet metal. Angular sensor according to the preceding claim in that said collection parts (300, 400) are identical but arranged relatively according to a central symmetry. Angular sensor according to claim 1 characterized in that all of the magnetosensitive elements (600, 610) are arranged on the same electronic card perforated at the level of the probes to accommodate one of the flat surfaces (330, 430) forming the air gap. System for measuring the torque and angle of a part in rotary motion, integrating an angular sensor according to claim 1 for measuring the torsion between two ends of said part in relative motion, characterized in that it further comprises two mobiles driven in rotation by said part in relative motion through a reduction of movement, the measurement of the position of the two mobiles making it possible to obtain the absolute position, over several revolutions, of the part in rotary motion. System for measuring the torque and angle of a part in rotary motion, integrating an angular sensor according to claim 1 for measuring the torsion between two ends of said part in relative motion, characterized in that it further comprises a mobile driven in rotation by said part in relative motion through a reduction of movement, the measurement of the angular position of the mobile and of the part in rotary motion making it possible to obtain the absolute position, over several revolutions, of the part in rotary motion. System for measuring the torque and angle of a rotating part according to claim 13, characterized in that the measurement of the position of the two moving parts is carried out by means of magneto-sensitive probes arranged on the electronic card supporting the at least one magneto-sensitive element (600, 610) allowing the measurement of the torque.

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