Rotation sensor for a steering system, and steering system for a motor vehicle
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- THYSSENKRUPP PRESTA AG
- Filing Date
- 2024-06-20
- Publication Date
- 2026-07-01
Smart Images
Figure EP2024067290_06032025_PF_FP_ABST
Abstract
Description
[0001] Rotation sensor for a steering system and steering system for a motor vehicle
[0002] State of the art
[0003] The invention relates to a rotation sensor for a steering system of a motor vehicle, comprising a magnetic element that can be mounted on a steering shaft and rotated about an axis, and two stator elements that are arranged coaxially and fixed relative to the magnetic element and axially spaced from one another. The stator elements are operatively connected to at least one sensor element via two flux conductors. Each flux conductor has a collecting section connected to a stator element, a coupling section connected thereto, and a compensator section. The sensor element is arranged between the two axially opposite coupling sections. A steering system with such a rotation sensor is also the subject of the invention.
[0004] In an electromechanical power steering system or a steer-by-wire steering system of a motor vehicle, a generic rotation sensor is used to detect a manual steering command. The rotation sensor detects the rotation of a steering shaft caused by manual actuation of a steering handle, and additionally or alternatively, the manual steering torque applied to the steering shaft. This sensor generates electrical control signals to actuate an electric steering drive, which causes the steered wheels to turn accordingly.
[0005] For detecting a rotational movement, rotation sensors with a magnetic sensor device are known. These can be designed as a torque sensor or rotation angle sensor, or as a combined torque and rotation angle sensor, as described, for example, in EP 4 163 599 A1. This comprises two stator elements and a magnetic element that is arranged to be rotatable relative to the stator elements and is designed such that it couples a magnetic flux into the stator elements that depends on the relative angular orientation. By measuring this coupled magnetic flux, the rotation of a component having the magnet relative to the rotationally fixed stator elements can be determined. By arranging such a rotation sensor in a steering column, it is possible to determine the angle of rotation of a steering shaft having the magnetic element, which can be rotated relative to the stator elements, by non-rotatably fixing the stator elements.A torque introduced into the steering shaft can be determined by the relative rotation of two steering shaft parts coupled via a torsionally elastic element, for example a torsion bar.
[0006] The two stator elements are ring-shaped and made of magnetically conductive material and surround the magnetic element coaxially with the axis of rotation. The stator elements have radially outer, circular disk-shaped connecting sections that are coupled to a magnetoelectric sensor element via magnetic flux conductors, thus creating a magnetic connection. The sensor element comprises, for example, a Hall or magnetoresistive (GMR) sensor, in which the magnetic flux introduced via the flux conductors is converted into an electrical signal.
[0007] The flux guides each have a collecting section that extends over a collecting surface and is connected to a connecting section of a stator element. At least one coupling section with a coupling surface is connected to the collecting section. The coupling sections of the two flux guides are designed and arranged such that the coupling surfaces are axially opposite one another on either side of an air gap. At least one sensor element is arranged between the coupling surfaces. The angle-dependent magnetic flux generated by the magnetic element is coupled into the stator elements and guided to the sensor element via the flux guides.
[0008] The measurement can be impaired by external magnetic interference fields, which are also coupled into the stator element from the outside and generate a magnetic interference flux that superimposes the measurement flux. To counteract such interference, the cited prior art proposes that the flux guides each have at least one compensator section that is magnetically connected to the collecting section and spaced apart from the stator elements. As a result, essentially only the interference field is coupled into the compensator section. The interference flux absorbed by this field is superimposed, with the opposite sign, on the measurement flux coupled into the collecting section and superimposed on the interference flux, for example by an axially swapped arrangement of the collecting and compensator sections, in which the compensator section of one flux guide is arranged axially in the region of the collecting section of the other flux guide, and vice versa.
[0009] The compensator sections improve the measurement of rotary movements, even under interference. However, due to the nested arrangement of the collecting, coupling, and compensator sections, the production of the rotary sensor is relatively complex. In view of the problems explained above, it is an object of the present invention to enable an optimized design and reduce manufacturing costs.
[0010] Description of the invention
[0011] This object is achieved according to the invention by the rotation sensor having the features of claim 1 and the steering system according to claim 12. Advantageous further developments emerge from the subclaims.
[0012] In a rotation sensor for a steering system of a motor vehicle, comprising a magnetic element which can be attached to a steering shaft and is rotatable about an axis, and two stator elements which are arranged coaxially and fixed relative thereto and are axially spaced from one another and which are operatively connected to at least one sensor element via two flux conductors, wherein a flux conductor in each case has a collecting section connected to a stator element, a coupling section connected thereto and a compensator section, wherein the sensor element is arranged between the two axially opposite coupling sections, it is provided according to the invention that the compensator sections of the two flux conductors are arranged without overlap in the axial direction.
[0013] The coupling sections of the two flux guides have parallel, spaced-apart coupling surfaces, which can preferably be perpendicular to the axis, and between which at least one sensor element is arranged. The coupling section is connected to the collector section so that the measuring magnetic flux collected there can be coupled into the sensor element via the coupling surfaces. At least one coupling section is connected to a compensator section, via which an interference magnetic field generated by an external interference field can be absorbed, and the resulting interference magnetic flux can be superimposed on the measuring magnetic flux to compensate for the measurement error.
[0014] In the generic design, the surface of the collecting section, the so-called collecting surface, and the surface of the compensator section, the so-called compensator surface, are aligned parallel to each other, or at least essentially parallel. Preferably, the surfaces are perpendicular to the axis.
[0015] The coupling surfaces are preferably also arranged parallel to the collector and compensator surfaces. The coupling surfaces of the two flux guides then lie axially opposite one another. The non-overlapping arrangement according to the invention means that the compensator surfaces do not touch or overlap, viewed transversely to their normal direction. As a result, the two stator elements can be moved axially relative to one another in a straight-line, pure axial movement in a rotational orientation corresponding to the installation position in the operating position with respect to the axis in which the axial coupling surfaces of the coupling sections lie axially opposite one another, until the final assembly position is reached, in which the coupling sections have a defined axial distance from one another. The compensator sections, which are arranged axially spaced relative to the collector sections, can be moved past one another in the axial direction without any problems.In other words, the compensator sections are arranged collision-free with respect to a straight axial movement in the direction of the shaft axis. This represents a significant advantage over the prior art, in which the compensator sections, which axially overlap in the installed position, must be threaded into the nested arrangement through a defined sequence of axial, radial and rotational movements. The fact that in the invention the stator elements including flux guides can be brought into their operating position through a simple axial linear movement simplifies the manufacturing process. A further advantage is that the axial air gap between the coupling surfaces of the two flux guides can be freely set and adjusted simply by a relative axial positioning of the flux guides, for example to adapt to different types of sensor elements, which is not possible with the known flux guides.This allows for more flexible use.
[0016] The overlap-free arrangement can also be characterized by the fact that the two flux guides have profile contours that correspond to each other in the axial direction without undercuts, with sections that are exclusively convex in the axial direction and correspondingly concave. This allows them to be joined in the axial direction to achieve a kind of loose form fit, at least in the area of the coupling sections.
[0017] In an advantageous embodiment, it can be provided that the flux guides cross between the compensator sections and the collecting sections, so that the compensator sections and the collecting sections are axially opposite one another. The axial positions of the compensator and collecting sections of the two flux guides are interchanged. This means that the collecting section of one flux guide and the compensator section of the other flux guide are axially located on one side, and the collecting section of the other flux guide and the compensator section of one flux guide are axially opposite one another on the other side. This forms an arrangement that is mirror-symmetrical with respect to a mirror plane perpendicular to the axis. Viewed in the circumferential direction, the connecting lines between the collecting and compensation sections form an X-shaped configuration.This enables effective compensation of external magnetic interference.
[0018] It is advantageous for the compensator surfaces and the collecting surfaces of the flux guides to be predominantly parallel to each other and to the connecting sections of the stator elements to which the collecting sections are connected. The connecting surfaces of the stator elements are preferably circular disk-shaped or annular with axial surfaces perpendicular to the axis, which are connected to corresponding axial sections of the collecting sections. "Predominantly" means that at least 75% of the compensator surfaces and the collecting surfaces are aligned parallel to each other.
[0019] A practical implementation can be achieved by arranging the compensator sections of the two flux guides tangentially offset from one another with respect to the axis. This means that the compensator sections of the two flux guides are arranged next to one another in a tangential direction, i.e. in the circumferential direction. The compensator sections are arranged at a radial distance from the axis that is greater than the outer radius of the stator elements coaxially enclosing the magnetic element. They therefore protrude radially outwards beyond the stator elements. The compensator sections of the two flux guides are preferably arranged at a distance from one another in the circumferential direction, i.e. tangentially in the region of said outer radius. This allows them to be moved freely past one another in the axial direction for mounting the rotary sensor.
[0020] It is preferred that the two stator elements be movable relative to each other in a purely axially directed relative movement in order to couple the coupling sections to the sensor element. A purely axial relative movement refers to a linear, rectilinear movement with preferably only one axial directional component. Accordingly, the two stator elements, which are coaxially aligned in the operating position, can be brought into operative engagement with each other and with the sensor element by means of a rectilinear axial assembly movement.
[0021] Preferably, it can be provided that a coupling section on a flux guide is axially and / or radially spaced from the collecting section. It is also possible for the compensator section on a flux guide to be axially and / or radially spaced from the coupling section. The collecting sections have an axial distance predetermined by the design of the stator elements, which is greater than the air gap between the coupling surfaces in which the sensor element is arranged. The compensator section can be connected to a coupling cut, preferably in the region of the axial position of the collecting section of the other flux guide. By appropriate shaping, the coupling cuts can be positioned such that the sensor element can be mounted axially centrally between the stator elements and with a defined radial position, preferably radially between the collecting and compensator sections.
[0022] The aforementioned arrangement can be realized by constructing a flux guide in a stepped manner. This means that the cross-section is formed in a stepped manner, as seen in the circumferential direction, and is angled multiple times. A first stepped surface can be located in the plane of the collecting surface, a second stepped surface can be offset axially therefrom in the plane of a coupling section, and a third stepped surface can be offset axially therefrom in the plane of a compensator surface.
[0023] It can be provided that a compensator section is connected to a collecting section and / or a compensator section via a connecting section. A connecting section is preferably implemented by a magnetically conductive mechanical connection and can thus ensure the coupling of the interference magnetic flux for compensation, as well as the spatial positioning of the compensator, coupling, and connecting sections. To implement the above-mentioned crossed arrangement (x-configuration) of the flux conductors, the connecting sections can be arranged crosswise. The connecting sections can also be angled in a step-like manner. A coupling section can be arranged on a stepped surface between the collecting and compensator sections.
[0024] Preferably, it can be provided that the compensator surfaces and the collecting surfaces of the flux guides are predominantly parallel to one another and to connection sections of the stator elements to which the collecting sections are connected. The connection surfaces of the stator elements are preferably circular disk-shaped or annular with axial surfaces that are connected to corresponding axial sections of the collecting sections. In any case, "predominantly" means that at least 75% of the compensator surfaces and the collecting surfaces are aligned parallel to one another. It is advantageous for the flux guides to be designed as one-piece sheet metal parts. The sheet metal parts can preferably be made from a material with good magnetic conductivity, for example an iron sheet with defined magnetic properties. Production can be carried out efficiently by pressing, punching, fine blanking, bending, embossing, or the like.The flux guide can thus have a substantially uniform material thickness throughout, which essentially corresponds to the sheet thickness. In a design with collector and compensator surfaces aligned transversely to the axis, the sheet thickness corresponds to the axial thickness of the collector and compensator sections.
[0025] A preferred value for the sheet thickness is between 0.6 mm and 1 mm, particularly preferably 0.8 mm.
[0026] Preferably, the flux guides can be designed as identical parts, meaning both flux guides have the same shape. This allows for more efficient production.
[0027] It is advantageous that the coupling surfaces of the coupling sections are arranged axially opposite one another. This means that the coupling sections overlap, so that they cannot be moved past one another in the axial direction - in contrast to the design of the compensator sections according to the invention. This makes it possible to move the two flux guides towards one another in a purely axial movement during assembly, with the non-overlapping compensator sections being moved past one another in the axial direction until the coupling surfaces are opposite one another at a defined axial distance. The sensor element is arranged between the coupling surfaces at this axial distance. The advantage of this design is particularly simple assembly, with the two flux guides being able to be brought into their final assembly position in a simple, straight axial relative movement, i.e. in the direction of the shaft axis.
[0028] The sensor element is arranged between the coupling surfaces, so that a sandwich-like arrangement is realized.
[0029] It is preferably provided that an axial spacer is inserted between the flux guides. This spacer rests against the two flux guides in the axial direction, i.e., in the direction of the shaft axis, and ensures that they are spaced a defined axially apart. For assembly, the two flux guides are moved toward each other, with the coupling sections according to the invention being moved past each other in the axial direction until the flux guides contact the spacer and the final assembly position is reached. The spacer is dimensioned in the axial direction such that the two coupling surfaces are spaced a defined axially apart, which is adapted to the sensor element(s).
[0030] Preferably, the spacer is arranged in the peripheral area of the coupling sections and compensator sections. This ensures precise maintenance of the distance. The spacer can preferably be fixed to the two flux conductors. For this purpose, a permanent connection can be provided, for example, by gluing or riveting.
[0031] The spacer may preferably comprise a plastic molded part, for example an injection molded part.
[0032] The sensor element(s) can preferably be arranged on a circuit board, which can preferably extend perpendicular to the shaft axis. The circuit board can be designed as a flat, preferably rigid electrical circuit board. The circuit board is preferably fixed to the flux guide(s).
[0033] An advantageous further development can provide that the compensator section has a compensator area which is smaller than or equal to a collecting area of the collecting section.
[0034] The preferably flat surface extension of a collecting section corresponds by definition to the collecting surface, and accordingly, the preferably flat surface extension of a compensator section corresponds by definition to the compensator surface. Each collecting section is magnetically connected to one of these axial surfaces, whereby the collecting surface can fully or partially contact an axial surface of a connecting section. The compensator sections are arranged radially outside the stator elements, and the compensator surfaces preferably extend outside the connecting sections.
[0035] Preferably, the inner and outer sides of the connecting sections of the stator elements, the collecting surfaces and the compensator surfaces can be formed flat at least in sections and aligned transversely to the axis, ie have axial surfaces that are parallel to one another at least in some areas.
[0036] Preferably, the surface area of the compensator section is smaller than or at most equal to the surface area of the collector section. This ensures that the portion of a magnetic interference field used to compensate for the measurement signal, which is captured by the compensator sections and can also be referred to as compensation flux, is kept at an optimal level. In particular, overcompensation can be prevented, which could otherwise lead to a falsification of the measurement result. This results in the advantage of higher measurement accuracy for the angle of rotation measurement, which leads to greater operational reliability. This is particularly advantageous for a motor vehicle steering system, which is highly safety-relevant for its operation.
[0037] To calculate the area ratio, the magnitudes of the area projections in a given direction can be used, for example, the collector and compensator areas projected in the axial direction. This ensures that an external magnetic interference field penetrating the collector and interference areas can be better compensated.
[0038] It is advantageous that the area ratio of the collecting area to the compensator area is between 1 and 4, i.e., the collecting area is between one and four times the compensator area. Further optimization may provide for the area ratio to be between 1 and 2. Advantageous refinements may provide an area ratio between 1.5 and 2, or in a narrower range between 1.5 and 1.75.
[0039] It can be particularly advantageous if the area ratio of the collecting area and the compensator area is 1.75.
[0040] The optimized effect in the aforementioned ratio ranges, and especially for the aforementioned specific ratio, can be explained by the fact that external interference fields impinge unhindered on the externally exposed compensator surfaces, while the collecting surfaces are at least partially shielded from external interference fields by the stator elements or the connecting sections of the stator elements. Accordingly, the size ratios proposed by the invention represent a favorable configuration for installation in a motor vehicle steering system.
[0041] A further practical advantage is that the compensator sections protrude less far outwards beyond the stator elements, which means that less space is required within the steering column.
[0042] In a steering system for a motor vehicle comprising a steering shaft rotatable about an axis, with a rotation sensor which has a magnetic element attached to the steering shaft and two stator elements which are arranged coaxially and fixed relative thereto and are axially spaced from one another and which are operatively connected to at least one sensor element via two flux conductors, wherein a flux conductor has a collecting section connected to a stator element, a coupling section connected thereto and a compensator section, wherein the sensor element is arranged between the two axially opposite coupling sections, it is provided according to the invention that the rotation sensor is designed according to one of the embodiments described above or combinations thereof.
[0043] The invention further relates to a method for producing a rotation sensor for a steering system of a motor vehicle, comprising a magnetic element which can be attached to a steering shaft and is rotatable about an axis, and two stator elements which are arranged coaxially and fixed relative thereto and are axially spaced from one another and which are operatively connected to at least one sensor element (6) via two flux conductors, wherein a flux conductor has a collecting section connected to a stator element, a coupling section connected thereto and a compensator section, wherein the sensor element is arranged between the two axially opposite coupling sections, in which the two stator elements are provided and positioned relative to one another in such a way that the sensor element is arranged axially between axially opposite coupling surfaces, which comprises the steps:
[0044] - Positioning the first stator element with the flux conductor relative to the shaft axis,
[0045] - Positioning the sensor element axially relative to the coupling surface of the first flux guide,
[0046] - Positioning the second stator element with the flux guide relative to the shaft axis, and moving it axially towards the first flux guide until a defined axial distance between the coupling surfaces of the collecting sections is reached,
[0047] - Fixing the flux conductors relative to each other.
[0048] The method according to the invention is made possible by the inventive design of the stator elements, with the above-mentioned features or combinations thereof.
[0049] First, the first flux guide is positioned axially relative to the shaft axis so that the compensator section and the coupling section are aligned perpendicular to the shaft axis. This can be done together with the stator element, to which the flux guide can be attached. Then, the sensor element(s) is(are) positioned in the assembly position relative to the coupling surface of the coupling section, for example by placing on a circuit board which extends transversely to the shaft axis and carries the sensor element(s). This positioning can be done by a purely axial assembly movement directed in the direction of the shaft axis. In the next step, the second flux guide, if necessary together with the second stator element, is also positioned axially on the shaft axis in such a way that its coupling surface lying transversely to the shaft axis is axially opposite the coupling surface of the first coupling section. Then, the second coupling section, if necessary.together with the second stator element, in a purely axially directed assembly movement toward the first stator element, whereby the compensator elements of the two coupling sections are moved past each other in the axial direction until a defined axial distance between the opposing coupling surfaces is reached. In this final assembly position, the two coupling sections, optionally together with the stator elements, and the sensor element(s) are fixed relative to each other, preferably by a permanent connection using adhesive or welding.
[0050] The coupling sections can be connected to the stator elements before assembly. Alternatively, the assembled coupling elements can be connected to the stator elements.
[0051] It is advantageous that the sensor element(s) are arranged on a circuit board which is fixed axially between the stator elements.
[0052] It is also advantageous to arrange at least one spacer axially between the coupling elements or between the stator elements. This allows the two stator elements to be moved toward each other until they axially abut the spacer, i.e., they rest against it in a defined axial position.
[0053] Assembly is significantly simplified compared to the prior art because the two coupling elements, possibly together with the stator elements, can be joined in a straight, purely axial assembly movement. The assembly of the circuit board with the sensor element(s) can also preferably be carried out in a purely axial assembly movement.
[0054] Description of the drawings
[0055] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail:
[0056] Fig. 1 shows a motor vehicle steering system in a schematic perspective view, Fig. 2 shows an enlarged detailed view of the rotation sensor of the steering system according to Fig. 1 in a cut-out schematic view,
[0057] Fig. 3 is an enlarged detailed view of the rotation sensor according to Fig. 2,
[0058] Fig. 4 the stator elements and the flux guides isolated in a schematic perspective view,
[0059] Fig. 5 shows the flux guide arrangement of the rotary sensor according to Fig. 3 in a schematic perspective view,
[0060] Fig. 6 the flux guide arrangement according to Fig. 5 in a further perspective view,
[0061] Fig. 7 shows the flux guide arrangement according to Figs. 4 and 5 in an axial plan view,
[0062] Fig. 8 shows a partial radial section through the rotary sensor according to Fig. 4 in the area of the flux guides according to the invention,
[0063] Fig. 9 is a schematic representation of the assembly, exploded axially in the direction of the shaft axis.
[0064] Embodiments of the invention
[0065] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.
[0066] Fig. 1 schematically illustrates a motor vehicle steering system 1 designed as an electromechanical power steering system. This system comprises a steering column 2 with a support unit 21 that can be attached to a motor vehicle body (not shown).
[0067] In the steering column 2, a first, upper steering shaft part 10 of a steering shaft is rotatably mounted about a longitudinal axis L. At the rear end of the steering shaft part 10, relative to the direction of travel, a steering wheel 12 is non-rotatably mounted, via which a driver can apply a steering torque (manual torque) as a steering command to the upper steering shaft part 10. The upper steering shaft part 10 is connected to a second, lower steering shaft part 11 via a torsionally elastic torsion bar (not shown here).
[0068] The steering torque is transmitted via the steering shaft parts 10 and 11 via intermediate universal joints 13 to a steering pinion 14, which engages a longitudinally displaceable rack 15. This converts a rotation of the steering shaft 10 during a steering intervention into a displacement of tie rods 16, as indicated by the double arrow, which transmit the specified steering intervention as a steering angle to the steerable wheels 17 of the motor vehicle.
[0069] An electric power assist system can comprise an auxiliary drive 3 mounted on the steering column 2 and coupled to the steering shaft 10, or an auxiliary drive 31 coupled to the pinion 14 with the steering shaft part 11, whereby the auxiliary drives 3 and 31 can be constructed similarly. The auxiliary drive 3 or 31 can couple an auxiliary torque into the lower steering shaft 11 and / or the steering pinion 14 to assist the driver in steering.
[0070] An auxiliary power drive 32 may also be provided to introduce an auxiliary power into the rack 15 to support the steering.
[0071] Typically, an auxiliary drive 3, 31, or 32 is provided at only one of the three positions shown. The auxiliary torque or auxiliary force to be applied to assist the driver by means of the respective auxiliary drive 3, 31, or 32 is determined taking into account a steering torque manually applied by the driver, determined by a rotation sensor 4. For this purpose, the rotation sensor 4 has a torque sensor that detects the relative rotation of the steering shaft parts 10 and 11, which depends on the magnitude of the manually applied steering torque. Furthermore, a rotation angle sensor is preferably provided for detecting the angular position of the steering shaft part 10 and / or 11.
[0072] The rotation sensor 4 is mounted between the upper steering shaft part 10 and the lower steering shaft part 11, as can be seen in the enlarged illustration of Fig. 2, which shows an enlarged schematic perspective view of the steering column 2 from Fig. 1.
[0073] A magnet 41 is coaxially mounted on the steering shaft part 10. It can be designed as a ring magnet and is arranged within two ring-shaped stator elements 42a, b, which are coaxially mounted on the second steering shaft part 11. The stator elements 42a, b have connecting sections 43a, b that are circular disk-shaped and project radially outward. The connecting sections 43a, b have axial surfaces perpendicular to the axis L on their axially opposing inner sides and their axially displaced outer sides.
[0074] The two stator elements 42a, b are magnetically coupled to two flux conductors 5a, b.
[0075] In Figs. 5 and 6, the two flux guides 5a and 5b are shown schematically in their installed positions in various perspective views, with the axis L drawn at a radial distance not to scale for orientation purposes only. Fig. 7 shows an axial plan view.
[0076] The flux guides 5a, b are formed as one-piece sheet metal parts and each have a collecting section 51a, b and a compensator section 52a, b, which are connected to one another via a web-shaped connecting section 53a, b. The collecting sections 51a, b and the compensator sections 52a, b extend parallel to an axial surface perpendicular to the axis, perpendicular to the axis L, with the collecting sections 51a, b each extending over a collecting surface, and the compensator sections 52a, b each correspondingly extending over a compensator surface.
[0077] In the example shown, the flux guides 5a, b are designed as identical parts, ie they are identically shaped and arranged in a mirror image of each other.
[0078] The collecting area is preferably greater than or equal to the compensator area, preferably in one of the area ratios according to the invention specified above.
[0079] Flux fingers 54a, b are attached to the collecting sections 51a, b. A coupling section 58a, b is formed in the projecting end region of each flux finger 54a, b, which coupling section has an axial coupling surface 580a, b directed toward the respective other flux conductor 5b, a. The coupling section 58a, b is spaced radially and axially from the collecting section 51a, b and the compensator section 52a, b.
[0080] Corresponding coupling sections 58a, b are formed on connecting sections 53a, b, which have coupling surfaces 580a, b axially opposite the coupling sections 58a, b on the flux fingers 54a, b. An axial air gap remains free between these, in which a sensor element 6, for example a Hall or GMR element, is arranged. This is shown schematically in Fig. 6 and Fig. 8. Fig. 7 shows an axial view from above of the flux guides 5a, b shown in Fig. 5 and 6 in the operating or installed position. This clearly shows how the two compensator sections 52a and 52b are arranged side by side without overlap in the tangential direction, which runs vertically from top to bottom in the view of Fig. 7. In this tangential direction, which can also be referred to as the circumferential direction, the compensator sections 52a and 52b are spaced apart by a distance D. This makes it possible to first connect one flux conductor 5b as shown in Fig.5, 6, and 7, and then move the other flux guide 5a through a purely axially directed assembly movement—in Figs. 5 and 6 from top to bottom, and in Fig. 7, away from the viewer, perpendicularly into the plane of the drawing—until the operating position shown in Figs. 5 and 6 is reached. The compensator section 52a can be freely moved past the compensator section 52b in the axial direction.
[0081] Fig. 8 shows a radial section through the arrangement of the two flux guides 5a, b. This clearly shows the stepped configuration, with the coupling sections 58a, b arranged axially and radially between the collecting sections 51a, b and the compensator sections 52a, b.
[0082] As can be seen in Figures 3, 4 and 8, the collecting sections 51a,b are attached to the inner sides of the connecting sections 43a,b.
[0083] The flux guides 5a, b are crossed between the compensator sections 52a, b and the collector sections 51a, b in the region of the connecting sections 53a, b, so that they are axially opposite one another. The axial positions are reversed, so that the collector section 51a of one flux guide 5a and the compensator section 52b of the other flux guide 5b are axially located on the side where the connecting section 43a of one stator element 42a is arranged, and the collector section 51b of the other flux guide 5b and the compensator section 52a of one flux guide 5a are axially opposite one another on the other side. This creates an arrangement that is mirror-symmetrical with respect to a mirror plane perpendicular to the axis L.Viewed in the circumferential direction, the connecting lines along the connecting sections 53a, b between the collecting sections 51a and the compensator sections 52b form an X-shaped configuration, as can be clearly seen in Figures 6 and 8. In Figures 3 and 4, the magnetic flux coupled by the magnet 41 into one stator element 42a is designated as measuring flux M1, and the magnetic flux coupled into the other stator element 42b is designated as measuring flux M2. The measuring fluxes M1 and M2 are indicated by filled arrows.
[0084] External interference fields are shown in Fig. 1, 3, and 4 as unfilled arrows, these generate magnetic interference fluxes S1 and S2.
[0085] The measuring flux M1 coupled by the magnet 41 into the stator element 42a is guided via the connecting section 43a into the collecting section 51a of the flux conductor 5a, and via the connecting element 53a and the compensator element 51a, through the flux finger 54a, and via the coupling section 58a into the sensor element 6. Accordingly, the measuring flux M2 passes through the collecting section 51b of the flux conductor 5b, via the connecting element 53b and the compensator element 51b, and via the coupling section 58b to the axially opposite side of the sensor element 6. This is illustrated in Figures 3 and 4.
[0086] The external magnetic interference fields are coupled as interference fluxes S1 and S2, at least partially, into the stator elements 42a, b, the connecting sections 43a, b, and the collecting sections 51, and into the compensator sections 52a, b. As schematically shown in the sectional view of Figure 6, in the coupling section of the flux finger 54a, which is axially coupled to the sensor element 6, the measuring flux M1 is superimposed by the interference fluxes S1 and S2. Analogously, in the coupling section of the other flux finger 54b, the other measuring flux M2 is also superimposed by the interference fluxes S1 and S2.
[0087] The interference fluxes S1 and S2 coming from the collecting sections 51a, b and from the compensator sections 52a, b are coupled into the sensor element 6 with opposite signs. As a result, they are compensated and, ideally, cancel each other out, so that only the measuring fluxes M1 and M2 are measured by the sensor element 6.
[0088] The collecting area, ie the axial area of a collecting section 51a, b may be larger than the compensator area, ie the axial area of a compensator section 52a, b.
[0089] The stator elements 42a, b, including the connecting sections 43a, b, can be formed from sheet metal with a sheet thickness BS, which can be, for example, 0.8 mm. The flux guides 5a, b can be formed as one-piece sheet metal parts with a sheet thickness BF, which can be, for example, 0.8 mm.
[0090] The compensator sections 52a, b can have an axial height difference relative to the collecting sections 51a, b which approximately corresponds to the sheet thickness BF or BS, so that the compensator sections 52a, b are substantially flush with the connecting sections 43a, b, as schematically indicated in Figure 8.
[0091] The collecting sections 51a, b may have an axial distance As that is smaller than the axial distance Ak of the compensator sections 52a, b.
[0092] The compensator sections 52a, b may have a radial distance Ra relative to the collecting sections 51a, b, which is related to the radial width Rs of the collecting sections 51a, b (measured in the direction of the distance Ra), as defined above in the description of the invention.
[0093] In the region of the sensor element 6, the flux fingers 54a, b are spaced apart by an axial distance Lu of the air gap, which can preferably be in a ratio to the sheet thickness BF according to the ranges defined above in the description of the invention. It is advantageous for the axial height distance between the flux fingers 54a, b and the sensor element 6 to be smaller than the sheet thickness BF.
[0094] The axial distance Ab of the connecting sections 43a, b can preferably be approximately 15 times the sheet thickness BS.
[0095] In Fig.9, the method according to the invention is explained using a schematic axial view, exploded in the direction of the shaft axis L.
[0096] The first flux guide 5a is aligned as the first flux guide relative to the axis L, in such a way that the compensator section 51b and the coupling section(s) 58a with the coupling surfaces 580a are aligned perpendicular to the axis L.
[0097] The first flux guide 5a can be mounted and fixed in a first housing part 81, shown at the bottom in Fig. 9, for example, by interlocking form-fitting elements and / or other suitable detachable and / or non-detachable connecting means. The sensor element(s) 6 are mounted on a printed circuit board 61 (circuit board), which is flat and extends perpendicular to the axis L.
[0098] The sensors 6 are moved together with the circuit board 61 axially, in the mounting direction E (= insertion direction) parallel to the axis L, towards the first flux guide until the sensor 6 is positioned in the measuring position axially adjacent to the coupling surface 580a.
[0099] Subsequently, or alternatively before mounting the printed circuit board 61, a spacer 9 is fixed in the mounting direction E (= insertion direction) relative to the first flux guide 5a. It can be connected directly to the flux guide 5a, or additionally or alternatively to the housing part 81.
[0100] In the next step, the second flux guide 5b is positioned at an axial distance relative to the first flux guide 5a, in such a way that its coupling surfaces 580b are directed axially against the coupling surfaces 580a of the first flux guide 5a.
[0101] Subsequently, the second flux guide 5b, possibly together with the stator element 42b (not shown in Fig. 9), is moved axially toward the first flux guide 5a in a purely axial movement in the insertion direction E until the collecting section 51b axially abuts the spacer 9. In this process, the compensator section 52 is moved past the compensator section 52 of the first flux guide 5a in the axial direction. This is made possible by the inventive design of the stator elements 42a, b and the flux guides 5a, b.
[0102] The spacer 9 is axially dimensioned such that a defined measuring distance is created between the coupling surfaces 580a, b, in which the sensor 6 is arranged when the collecting sections 51a,b rest against the spacer 9.
[0103] Subsequently, a second housing part 82 is placed in the assembly direction E onto the first housing part 81 and connected thereto to form the housing 8, and fixed, preferably in a non-detachable manner.
[0104] The assembly of the stator elements 42a, b according to the invention, which have an inventive, overlap-free arrangement of the compensator sections 52a, b, can be carried out according to the inventive method by joining in a purely axially directed assembly direction E, which significantly simplifies production and which is not possible with the stator elements known in the prior art.
[0105] 1 steering system
[0106] 10 Steering shaft part
[0107] 11 Steering shaft part
[0108] 12 Steering wheel
[0109] 13 universal joint
[0110] 14 pinions
[0111] 15 rack
[0112] 16 Tie rod
[0113] 17 wheels
[0114] 2 steering column
[0115] 21 Support unit
[0116] 3.31 Auxiliary drive
[0117] 4 rotation sensor
[0118] 41 Magnet (ring magnet)
[0119] 42a, b Stator element
[0120] 43a, b connecting section
[0121] 5a, b flow conductor
[0122] 51a, b collection section
[0123] 52a, b compensator section
[0124] 53a, b connecting section
[0125] 54a, b River Finger
[0126] 58a, b coupling section
[0127] 580a, b coupling area
[0128] 6 Sensor element
[0129] 61 circuit board
[0130] 8 housings
[0131] 81 Housing part
[0132] 82 Housing part
[0133] L axis
[0134] D Distance between 52a and 52b
[0135] M1 measuring flow
[0136] M2 measuring flow
[0137] S1 disturbance flow
[0138] S2 disturbance flow
[0139] BF sheet thickness BS sheet thickness
[0140] From axial distance
[0141] As axial distance
[0142] Ak axial distance Ra radial distance
[0143] Rs radial width
[0144] Lu axial distance (air gap)
[0145] E Mounting direction (insertion direction)
Claims
PATENT CLAIMS 1. A rotation sensor (4) for a steering system (1) of a motor vehicle, comprising a magnetic element (41) which can be attached to a steering shaft (10) and is rotatable about an axis (L), and two stator elements (42a, b) which are arranged coaxially and fixed relative thereto and are axially spaced from one another and which are operatively connected to at least one sensor element (6) via two flux conductors (5a, b), wherein a flux conductor (5a, b) each has a collecting section (51a, b) connected to a stator element (42a, b), a coupling section (58a, b) connected thereto, and a compensator section (52a, b), wherein the sensor element (6) is arranged between the two axially opposite coupling sections (58a, b), characterized in that the compensator sections (52a, b) of the two flux conductors (5a, b) are arranged without overlap in the axial direction.
2. Rotation sensor according to claim 1, characterized in that the flux conductors (5a, b) are crossed between the compensator sections (52a, b) and the collecting sections (51a, b) so that the compensator sections (52a, b) and the collecting sections (51a, b) are axially opposite one another.
3. Rotation sensor according to one of the preceding claims, characterized in that the compensator sections (52a, b) of the two flux guides (5a, b) are arranged tangentially offset from one another with respect to the axis (L).
4. Rotary sensor according to one of the preceding claims, characterized in that the two stator elements (42a, b) are movable relative to one another in a purely axially directed relative movement in order to couple the coupling sections (58a, b) to the sensor element (6).
5. Rotary sensor according to one of the preceding claims, characterized in that on a flux conductor (5a, b) a coupling section (58a, b) is axially and / or radially spaced from the collecting section (51a, b).
6. Rotation sensor according to one of the preceding claims, characterized in that on a flux guide (42a, b) the compensator section (52a, b) is axially and / or radially spaced from the coupling section (58a, b).
7. Rotation sensor according to one of the preceding claims, characterized in that a flux conductor (5a, b) is designed in a stepped manner.
8. Rotation sensor according to one of the preceding claims, characterized in that a compensator section (52a, b) is connected to a collecting section (51a, b) and / or a compensator section (52a, b) via a connecting section (53a, b).
9. Rotary sensor according to one of the preceding claims, characterized in that the compensator surfaces and the collecting surfaces of the flux conductors (5a, b) are predominantly parallel to one another and to connecting sections (43a, b) of the stator elements (42a, b) to which the collecting sections (51a, b) are connected.
10. Rotation sensor according to one of the preceding claims, characterized in that the flux guides (5a, b) are designed as one-piece sheet metal parts.
11. Rotation sensor according to one of the preceding claims, characterized in that the flux conductors (5a, b) are designed as identical parts.
12. Rotary sensor according to one of the preceding claims, characterized in that the coupling surfaces (580a, b) of the coupling sections (58a, b) are arranged axially opposite one another.
13. Rotation sensor according to one of the preceding claims, characterized in that the compensator section (52a, b) has a compensator area which is smaller than or equal to a collecting area of the collecting section (51a, b).
14. Steering system (1) for a motor vehicle comprising a steering shaft (10) rotatable about an axis (L), with a rotation sensor (4) which has a magnetic element (41) attached to the steering shaft (10) and two stator elements (42a, b) which are arranged coaxially and spaced apart from one another and are fixed relative thereto and which are operatively connected to at least one sensor element (6) via two flux conductors (5a, b), wherein a flux conductor (5a, b) a collecting section (51a, b) connected to a stator element (42a, b), a coupling section (58a, b) connected thereto, and a compensator section (52a, b), wherein the sensor element (6) is arranged between the two axially opposite coupling sections (58a, b), characterized in that the rotation sensor (4) is designed according to one of the preceding claims 1 to 13.
15. A method for producing a rotation sensor (4) for a steering system (1) of a motor vehicle, comprising a magnetic element (41) which can be attached to a steering shaft (10) and is rotatable about an axis (L), and two stator elements (42a, b) which are arranged coaxially and fixed relative thereto and are axially spaced from one another and which are operatively connected to at least one sensor element (6) via two flux conductors (5a, b), wherein a flux conductor (5a, b) has a collecting section (51a, b) connected to a stator element (42a, b), a coupling section (58a, b) connected thereto, and a compensator section (52a, b), wherein the sensor element (6) is arranged between the two axially opposite coupling sections (58a, b), in which the two stator elements (42a, b) are provided and positioned relative to one another in such a way that the sensor element (6) is axially arranged between axially oppositely directed coupling surfaces (580a, b), characterized by the steps: - positioning the first stator element (42a) with the flux conductor (5a) relative to the shaft axis (L), - Positioning the sensor element (6) axially relative to the coupling surface (580a) of the first flux conductor (5a), - positioning the second stator element (42) with the flux guide (5b) relative to the shaft axis (L), and axially moving it towards the first flux guide (5b) until a defined axial distance between the coupling surfaces (580a, b) of the collecting sections (52a, b) is reached, - Fixing the flux conductors (5a, b) relative to each other.