Position measuring system

Abstract

Position measuring system (10) comprising a permanent magnet (12) and a magnetic field sensor (16) movably arranged along a measuring section (14) running laterally next to the permanent magnet (12) in order to be able to determine a position of the magnetic field sensor (16) along the measuring section (14) on the basis of a direction of the magnetic field determined by means of the magnetic field sensor (16), characterized in that the position measuring system (10) further comprises at least one ferromagnetic flux guide piece (20-1, 20-2) which extends below or above the measuring section (14) in a plate-like manner on the one hand in the direction of the measuring section (14) and at least a part of the measuring section (14) and on the other hand in a lateral direction, wherein the at least one flux guide piece (20-1, 20-2) has the form of a flat plate,whose plate plane extends below or above the measuring section (14) at least approximately parallel to the measuring section (14) on the one hand and in a lateral direction on the other.

Description

[0001] The present invention relates to a position measuring system comprising a permanent magnet and a magnetic field sensor arranged movably along a measuring section running laterally next to the permanent magnet, in order to be able to determine a position of the magnetic field sensor along the measuring section based on a direction of the magnetic field determined by means of the magnetic field sensor.

[0002] In such a position measurement system, the determination of the position of the magnetic field sensor or a component equipped with the magnetic field sensor can, for example, be carried out along a straight measuring path. Alternatively, such a measurement can also be carried out over a curved measuring path, e.g., a circular arc.

[0003] The function of such a "magnetic" position measuring system is based on the exploitation of the fact that the magnetic field of a permanent magnet is location-dependent. Therefore, a direction of the magnetic field determined for a specific location by means of a magnetic field sensor represents a quantity representative of the corresponding position (of the magnetic field sensor relative to the permanent magnet), or, alternatively, this position can be deduced from the result of a measurement of the magnetic field direction. It is understood that the position, mobility, and movement of the magnetic field sensor along the measuring path are to be understood here, and also within the scope of the invention, as relative position, relative mobility, and relative movement of the magnetic field sensor relative to the permanent magnet.

[0004] Such generic position measuring systems are known in various designs from the prior art. For example, reference is made to publications EP 0 979 988 B1, DE 199 10 636 A1, EP 1 989 505 B1 and WO 2011 / 135 063 A2.

[0005] DE 10 2012 000 939 A1 relates to a sensor unit with a magnetic field generation element which is arranged to generate a magnetic field with different magnetic field directions at different positions along a movement range of a sensor element.

[0006] US 2010 / 0 231 205 A1 describes a position sensor with variable magnetic field direction.

[0007] A stroke sensor and a rotation angle sensor are known from DE 10 2010 001 308 A1.

[0008] DE 691 07 873 T2 discloses a helical permanent magnet.

[0009] A disadvantage of position measurement systems known from the prior art is their greater or lesser susceptibility to interference from magnetic fields present in the system's installation environment. Furthermore, a common drawback of known systems is that, due to the inherent properties of a magnetic field, the dependence of the permanent magnet's magnetic field on the position of the magnetic field sensor along the measuring path can be influenced by the design (e.g., by the shape and magnetization of the permanent magnet, and the path of the measuring path relative to the permanent magnet), but cannot be completely predetermined. Another disadvantage of known systems lies in the measurement's sensitivity to mechanical tolerances such as manufacturing and assembly tolerances, as well as mechanical play.In particular, changes in the position of the magnetic field sensor due to play, perpendicular to the direction of the magnetic field to be measured, cause a significant measurement uncertainty.

[0010] It is an object of the present invention to eliminate or at least mitigate the disadvantages described above in a position measuring system of the type mentioned at the outset. In particular, the invention is intended to enable a position measuring system of the type mentioned at the outset that is less susceptible to interference and in which the dependence of the magnetic field on the position along the measuring path can be specified more flexibly.

[0011] According to the invention, this problem is solved by a position measuring system according to claim 1. The dependent claims relate to advantageous embodiments of the invention.

[0012] The position measuring system according to the invention is characterized in that it further comprises (at least) one ferromagnetic flux guide element which extends in a plate-like form below or above the measuring section, on the one hand in the direction of the measuring section and following at least a part of the measuring section, and on the other hand in a lateral direction. The at least one flux guide element has the form of a flat plate, the plane of which extends below or above the measuring section at least approximately parallel to the measuring section and on the other hand in a lateral direction.

[0013] Advantageously, the invention allows for the at least partial shielding of any magnetic interference fields that may occur, thanks to the (at least one) ferromagnetic flux guide. Therefore, the influence of interference fields on the measurement result is reduced. The shielding effect depends on the spatial arrangement and extent of the ferromagnetic material and can thus be advantageously adapted to the specific application through the design. The shielding effect proves particularly beneficial when ferromagnetic flux guides extending both above and below the measuring section are installed.

[0014] The terms used here in the description of the position measuring system to define relative spatial arrangements and directions, such as "below," "down," "above," "above," "vertical," "sideways," "lateral," and "horizontal," serve only to simplify the description of the position measuring system. These terms define, in a sense, a spatial coordinate system for the position measuring system itself, but were chosen arbitrarily insofar as the precise location of "up" and "down" is ultimately determined only in the context of the system's use.

[0015] A further advantage of the invention is that the (at least one) ferromagnetic flux guide allows for targeted control and thus modification of the dependence of the direction of the permanent magnet's magnetic field on the position of the magnetic field sensor along the measuring path. In the invention, the dependence of the magnetic field on the position of the magnetic field sensor can be influenced not only by the shape and magnetization of the permanent magnet and the course of the measuring path relative to the permanent magnet, but also advantageously by the specific arrangement and shape of the flux guide(s).

[0016] It has proven advantageous that many arrangements and designs of the flux guide pieces exist and can therefore be used, with which both a large shielding effect against interference fields and an advantageous modification of the dependence of the direction of the magnetic field on the position of the magnetic field sensor, which determines the measurement system characteristic, can be achieved.

[0017] In particular, any type of linearization of the aforementioned dependency or measurement system characteristic can represent such an advantageous modification. Linearization here means that the relationship between, on the one hand, the direction of the magnetic field (or the corresponding sensor signal), and, on the other hand, the position to be determined, can be described more precisely by a relatively simple mathematical function, in particular a linear function, than would be the case without the use of one or more flux guides according to the invention.

[0018] A further advantage of the invention is that a dependence of the direction of the magnetic field on the position of the magnetic field sensor can be achieved that is relatively insensitive to any tolerances. For example, by homogenizing the magnetic field in the area of ​​the measuring section, the invention can advantageously compensate for, e.g., mechanical play of the magnetic field sensor with regard to its arrangement on the measuring section and / or its guidance along the measuring section.

[0019] The measuring section runs laterally alongside the (at least one) permanent magnet. In one embodiment, the measuring section is designed to run in a straight line. Alternatively, however, a non-straight measuring section can also be provided, in particular, for example, a curved measuring section, e.g., a circular arc. A curved measuring section can, for example, correspond to an arc angle of at least 20°, in particular at least 40°, and / or a maximum of 180°, in particular a maximum of 120°. The course of the measuring section can, in particular, for example, be parallel (i.e., at a predetermined uniform distance in the lateral direction of the position measuring system) to the course of a permanent magnet, in particular, for example, an elongated shape. In a preferred embodiment, the magnetic field sensor maintains its position as it moves along the measuring section (i.e.,relative to the permanent magnet) its orientation with respect to the (local) orientation of the measuring section.

[0020] In a further embodiment of the invention, described in more detail below, the permanent magnet is designed as a ring-shaped, closed body. In this case, the measuring section can also run in a ring-shaped, closed form laterally alongside the permanent magnet. In particular, the permanent magnet and the measuring section can be provided with circular arc-shaped, closed, concentric profiles, such that the profile of the measuring section corresponds to an arc angle of 360°.

[0021] Within the scope of the invention, it is not excluded that several permanent magnets are provided, in particular, for example, at least two permanent magnets, wherein the magnetic field sensor can be arranged, for example, to be movable along a measuring section running laterally next to both permanent magnets (i.e., viewed in the lateral direction between the two permanent magnets) along both permanent magnets.

[0022] Within the scope of the invention, it is not excluded that several magnetic field sensors are provided, in particular, for example, at least two magnetic field sensors, both of which are movably arranged along the measuring section running laterally next to the (at least one) permanent magnet, but offset from each other along the measuring section. In this case, a position along the measuring section can be determined using the multiple magnetic fields (measured by several magnetic field sensors).

[0023] In one embodiment of the invention, the permanent magnet is formed from a single piece of a hard magnetic material, in particular, for example, an alloy containing iron (e.g., ferrite) and, for example, cobalt and / or nickel. Alternatively, the permanent magnet can be formed, for example, from a composite material, such as a plastic matrix with embedded particles of magnetic material. These latter magnets can be produced, for example, by pressing or injection molding.

[0024] In one embodiment of the invention, the permanent magnet is designed as an elongated profile.

[0025] In this case, the permanent magnet has a uniform cross-section (profile cross-section) along its entire length (path). The profile cross-section can, in particular, be rectangular, approximately square, or approximately trapezoidal in shape.

[0026] In one embodiment, a profile axis of the profile is provided to be straight. In this case, the permanent magnet can therefore have, for example, a prismatic or cuboid shape.

[0027] In another embodiment, one profile axis of the profile is curved. For example, a profile axis curved in a circular arc may be provided.

[0028] In one embodiment of the invention, the permanent magnet is designed as an elongated profile and the measuring section running laterally alongside the permanent magnet runs parallel to a profile axis of the profile.

[0029] In this context, the term "parallel" should be understood as independent of whether the profile axis and the measuring section both run in a straight line or are both curved.

[0030] In particular, it can be provided that the profile axis and the measuring section both run parallel to each other in a straight line, spaced laterally apart, or that the profile axis and the measuring section run parallel to each other, e.g. with respective curves, spaced laterally apart (for example on respective arcs of two concentric circles).

[0031] In one embodiment of the invention, the permanent magnet is designed as an elongated body with a cross-section that varies along its length (path).

[0032] The term "cross-section" is to be understood as being determined by both its shape (cross-sectional shape) and its size (cross-sectional area). Therefore, a cross-section that varies along the length of the permanent magnet can result from a variation in the cross-sectional shape and / or a variation in the cross-sectional area.

[0033] In one embodiment of the invention, the permanent magnet is designed as an elongated body with a uniform (non-varying) cross-sectional area along its length.

[0034] In one embodiment of the invention, the permanent magnet is designed as an elongated body with a cross-sectional shape that varies along its length. For this purpose, it can be provided, for example, that the cross-section has the shape of a quadrilateral (e.g., a trapezoid), in which the orientation of one side of the quadrilateral facing the measuring section varies along the length of the permanent magnet.

[0035] In a further development of this embodiment, it is provided that the said side of the quadrilateral runs vertically at a central point along the length of the permanent magnet (and the cross-section there is, for example, at least approximately rectangular), but runs increasingly obliquely (with respect to the vertical) with increasing distance from the central point.

[0036] Alternatively or additionally, it can be provided that the aforementioned side of the quadrilateral extends at an angle to the vertical, which varies monotonically, and in particular strictly monotonically, and especially proportionally to its position along the length of the permanent magnet. In a preferred embodiment, the angle to the vertical varies by a total angle of at least 10°, and in particular at least 30° or at least 60°, over the entire length of the permanent magnet. On the other hand, it is advantageous in many cases if this angle is a maximum of 120°, and in particular at most 90°. In particular, it can also be provided that the cross-section of the permanent magnet has a uniform (non-varying) cross-sectional area over its length.In one embodiment, the quadrilateral mentioned is a trapezoid in which two parallel trapezoidal sides run at least approximately in the lateral direction of the position measuring system and one trapezoidal side facing away from the measuring distance runs at least approximately in the vertical direction of the position measuring system.

[0037] In one embodiment, the permanent magnet is designed as a ring-shaped (e.g., circular) closed body, wherein the measuring section can also run radially outside the permanent magnet in a ring-shaped (e.g., circular) closed form.

[0038] In this case, too, the permanent magnet configurations described above can be advantageously employed, although the following distinctions must be noted regarding the terminology: "along the length (of the permanent magnet)" then means "along the circumference," and "a full length (of the permanent magnet)" then means "a full 360° circumference / circumference." Furthermore, the following restriction must be observed: A cross-section at a specific point must be reproduced (at the latest) every 360° as one progresses along the circumference. While this is always the case when the permanent magnet is designed as a single profile, it represents a restriction when the cross-section varies along the length (path, i.e., here, a 360° rotation).

[0039] Taking this restriction into account, the above-described configuration, in which "the aforementioned side of the quadrilateral runs vertically at a central point along the length of the permanent magnet (and the cross-section there is, for example, at least approximately rectangular), but becomes increasingly oblique (with respect to the vertical) with increasing distance from the central point," requires a modification for a ring-shaped, closed permanent magnet. In a modified configuration with a cross-section varying over a 360° rotation, the aforementioned side of the quadrilateral is provided to run vertically at (at least) one specific initial point along the length of the permanent magnet (and the cross-section there is, for example, approximately rectangular).(at least approximately rectangular) and with increasing distance from this first point up to (at least) a second point, it runs increasingly obliquely (with respect to the vertical), but after passing each such second point, the side of the quadrilateral again runs less obliquely (with respect to the vertical).

[0040] Furthermore, taking into account the restriction of a ring-shaped closed permanent magnet, the above-described embodiment requires a modification in which "the said side of the quadrilateral runs at an angle with respect to the vertical which varies monotonically, in particular strictly monotonically, in particular proportionally to the position in the course of this length" along the length of the permanent magnet, wherein in a preferred embodiment "the angle with respect to the vertical varies overall (over the full length of the permanent magnet) by an angular amount of at least 10°, in particular at least 30° or at least 60°".In a modified embodiment with a cross-section varying over a 360° rotation, the aforementioned side of the quadrilateral is provided to run at an angle to the vertical which varies monotonically, in particular strictly monotonically, and in particular proportionally to the position along the circumference of the permanent magnet, wherein at least one section of the circumference is provided with monotonous increase and at least one section of the circumference with monotonous decrease, wherein in a preferred embodiment the angle to the vertical varies over the entire circumference of the permanent magnet and / or each of the aforementioned sections by an angular amount of at least 10°, in particular at least 30° or at least 60° (and varies, for example, by a maximum of 120°, in particular by a maximum of 90°).

[0041] There are various possibilities regarding the magnetization of the permanent magnet.

[0042] In one embodiment of the invention, it is provided that the permanent magnet is homogeneously magnetized, in which case the permanent magnet may, for example, be designed as an elongated profile and may in particular be magnetized orthogonally to a profile axis of the profile (e.g. vertically).

[0043] In the case of homogeneous magnetization of the permanent magnet, a magnetization direction oriented at least approximately orthogonal to a course of the permanent magnet is preferably provided, in particular, for example, a magnetization direction oriented at least approximately vertically.

[0044] However, homogeneous magnetization in the direction of the profile axis of the profile, or generally in the direction of the length of the permanent magnet, is not excluded within the scope of the invention.

[0045] In a particularly advantageous further development of the embodiment with homogeneous magnetization, the arrangement and / or shape of the flux guide(s) is so non-uniform along the length of the permanent magnet that the dependence of the magnetic field on the position of the magnetic field sensor along the measuring path, and thus the measuring system characteristics, are significantly modified, or that this dependence is even caused in the first place. Two exemplary embodiments are given here: Example 1: In the case of a permanent magnet designed as an elongated (e.g., straight) profile and homogeneously magnetized along its profile axis, the magnetic field exhibits a qualitatively complex and quantitatively weak dependence on the position along a measuring section parallel to the profile axis. However, by using one or more flux guides with non-uniformity along the length of the permanent magnet, this dependence can be advantageously modified or improved both qualitatively (e.g., linearization) and quantitatively (e.g., increasing the "stroke" of the quantity(ies) measured by the magnetic field sensor). Example 2: For a permanent magnet designed as an elongated (e.g., straight) profile and homogeneously magnetized orthogonally to its profile axis (e.g., vertically), there is no dependence of the magnetic field on the position along a measuring section running laterally alongside the permanent magnet parallel to its profile axis (apart from "edge effects" at the ends of a measuring section extending to both ends of the permanent magnet). However, by using one or more flux guides with non-uniformity along the length of the permanent magnet, such a dependence can be advantageously created and even qualitatively adjusted to a certain extent as desired.

[0046] According to a more specific embodiment, the permanent magnet is homogeneously magnetized with a magnetization direction oriented substantially orthogonal to the path of the permanent magnet, in particular with a substantially vertically oriented magnetization direction, wherein a lower and an upper flux guide are provided, which, viewed laterally, extend along the entire length of the measuring section to the permanent magnet and each bear against the permanent magnet (and, for example, terminate flush with the permanent magnet), and which, viewed laterally, each extend at a point along the length of the measuring section to or beyond the measuring section and have a varying lateral extent over at least a portion of the measuring section. The contours (viewed from above or below) of the two flux guides can, in particular, for example, be...The lines run as mirror images of each other, relative to a mirror plane extending vertically in a central region of the measuring distance. The longitudinal center line of the permanent magnet can be straight or curved.

[0047] In another embodiment of the invention, it is provided that the permanent magnet is inhomogeneously magnetized, wherein in this case the permanent magnet can also be designed, for example, as an elongated profile, and wherein, in particular, for example, a magnetization varying in a helical manner along a profile axis of the profile, or more generally along the length of the permanent magnet, can be provided.

[0048] Such a helical variation can be provided in such a way that a (local) magnetization direction depends essentially exclusively on the position along the profile axis of the profile (generally: along the length of the permanent magnet).

[0049] In the case of an inhomogeneous magnetization of the permanent magnet, a magnetization direction that is oriented at least approximately orthogonally to the course of the permanent magnet and varies along the course of the permanent magnet is preferably provided.

[0050] In a further development of the embodiment with inhomogeneous magnetization, the arrangement and shape of the flux guide(s) are uniform along the length of the permanent magnet. For this purpose, the at least one flux guide, or, for example, each of two flux guides arranged below or above the measuring section, can be shaped as a plate. This plate extends below or above the measuring section, on the one hand, in the direction of the measuring section, following its entire length, and on the other hand, laterally with a constant extent (e.g., plate width). In this case, there is no significant qualitative change in the measuring system characteristics, which can essentially already be determined by the inhomogeneous (e.g., helical) magnetization.However, a high shielding effect with regard to interference fields is advantageously achieved, and furthermore, a certain quantitative modification of the measurement system characteristics can be advantageously achieved by amplifying and homogenizing the magnetic field in the area of ​​the measuring section.

[0051] In another further development of the embodiment with inhomogeneous magnetization, it is provided that the arrangement and / or shape of the flux guide piece(s) is non-uniform when viewed over the length of the permanent magnet, in order to modify the measurement system characteristic in a desired way (e.g. linearization) by thereby modifying the dependence of the magnetic field on the position of the magnetic field sensor along the measuring path.

[0052] Here is an exemplary embodiment: In the case of a permanent magnet designed as an elongated (e.g., straight) profile and inhomogeneously magnetized in a helical pattern orthogonal to its profile axis, a qualitatively simple and quantitatively relatively strong dependence of the magnetic field on the position along a measuring section parallel to the profile axis already arises. The use of one or more flux guides according to the invention can then primarily serve, for example, to shield against interference fields. Nevertheless, even in this example, the measuring system characteristics can be advantageously modified (e.g., linearized) by deliberately introducing a non-uniformity in the arrangement and / or shape of the flux guide(s) along the length of the permanent magnet.

[0053] For this purpose, at least one flow control piece or, for example, each of two flow control pieces arranged below or above the measuring section can be designed as a plate which extends below or above the measuring section on the one hand in the direction of the measuring section and, in doing so, follows the measuring section, for example, over its entire length, and on the other hand in a lateral direction with uneven extent (e.g., plate width).

[0054] According to a more specific embodiment, the permanent magnet is inhomogeneously magnetized with a magnetization direction that is oriented essentially orthogonally to the direction of the permanent magnet and varies along its length. A lower and an upper flux guide are provided, each extending laterally along the entire length of the measuring section, on the one hand, up to and in contact with the permanent magnet, and on the other hand, each extending to or beyond the measuring section. The permanent magnet can, for example, be designed as an elongated body with a cross-section that varies along its length, particularly in that the cross-section has the shape of a quadrilateral, where the orientation of one side of the quadrilateral facing the measuring section varies along the length of the permanent magnet.In particular, the magnetization direction, which varies along the length of the permanent magnet, can be designed as a (helical) twist of the magnetization direction, resulting in a twist angle of at least 10°, and in particular at least 20°, over the entire length of the permanent magnet. On the other hand, in many cases it is sufficient if this twist angle is a maximum of 120°, and in particular a maximum of 90°. The longitudinal centerline of the permanent magnet can be straight or curved.

[0055] As already mentioned, the permanent magnet within the scope of the invention can be designed as a ring-shaped, closed body (e.g., a profile). In this case, too, the embodiments described above with homogeneous or inhomogeneous magnetization can advantageously be provided, provided that, with regard to the terminology, it is noted that "along the length (of the permanent magnet)" then means "along the circumference," and "a full length (of the permanent magnet)" can then mean, for example, "a full 360° circumference / circumference," and the restriction is observed that a magnetization (in magnitude and direction) at a specific point must be reproduced (at least) every 360° after progressing along the circumference. The term "in the lateral direction" is then to be understood as "in the radial direction."In one embodiment, a periodically changing magnetization direction is provided along the circumference, whereby, when viewed over the entire circumference (360°), only one period or several periods (e.g. 2, 3, 4 or more periods) of a circumferential angle-dependent magnetization direction may be provided.

[0056] In one embodiment of the invention, the position measuring system has (at least) a lower ferromagnetic flux guide piece which extends below the measuring section in a plate-like shape on the one hand in the direction of the measuring section and following at least a part of the measuring section and on the other hand in a lateral direction, and the position measuring system has (at least) an upper ferromagnetic flux guide piece which extends above the measuring section in a plate-like shape on the one hand in the direction of the measuring section and following at least a part of the measuring section and on the other hand in a lateral direction.

[0057] When describing special details or embodiments concerning the design of a flow guide piece, this description may, in the case of the presence of several flow guide pieces, for example a lower and an upper flow guide piece as mentioned above, refer to one or more or all of these existing flow guide pieces.

[0058] In one embodiment, the at least one flux guide piece is formed from a soft magnetic material, in particular a metal or a metal alloy.

[0059] The material of at least one river conduit can be, in particular, iron or a metal alloy containing iron (e.g., iron-nickel alloy).

[0060] In one embodiment, the at least one flow guide is designed as a solid sheet ("flow guide plate"), in particular as a sheet with a uniform thickness. Suitable sheets can, for example, be designed or manufactured as stamped sheet metal.

[0061] In an advantageous embodiment, the thickness (or a thickness averaged over a sheet area) is at least 0.05 times, in particular at least 0.1 times, a (possibly maximum) extent of the permanent magnet in the vertical direction, and / or this thickness is at most 0.5 times, in particular at most 0.4 times, this extent.

[0062] In one embodiment, it is provided that the at least one flow guide piece has the form of a flat plate, wherein a plate plane can extend on the one hand at least approximately parallel to the measuring section (below or above it) and on the other hand in a lateral direction, in particular at least approximately in a horizontal direction.

[0063] In one embodiment, the at least one flux guide extends at least once along the measuring section in a lateral direction up to the permanent magnet (e.g., horizontally), and in particular abuts the permanent magnet. For example, a flux guide arranged below the measuring section can abut the permanent magnet with an end face or with part of its upper flat surface, whereas a flux guide arranged above the measuring section can abut the permanent magnet with an end face or with part of its lower flat surface.

[0064] Preferably, the (plate-shaped) at least one flux guide piece is provided in a planar position against a corresponding contact surface of the permanent magnet. The contact surface can, for example, be designed as a flat surface. The contact surface can, for example, represent a lower or an upper end face of the permanent magnet, in which case it is preferred that the flux guide piece in question rests against this contact surface over its entire area. The contact surface can, for example, be horizontally oriented.

[0065] In one embodiment of the invention, it is provided that the at least one flow guide section extends at least at one point along the measuring section in a lateral direction up to or beyond the measuring section.

[0066] In a further development of this embodiment, the at least one flow guide section extends laterally along the entire length of the measuring section, either up to or beyond the measuring section. For example, in the case of a straight measuring section, a flow guide section with a rectangular contour can be provided. For example, in the case of a closed, ring-shaped (e.g., circular) measuring section, a flow guide section with a uniformly wide, ring-shaped or circular contour can be provided.

[0067] In one embodiment of the invention, it is provided that the at least one flux guide piece extends, on the one hand, to the permanent magnet and rests against the permanent magnet, and on the other hand, extends to the measuring section or beyond the measuring section, as viewed laterally along the entire length of the measuring section.

[0068] In one embodiment of the invention, the at least one flux guide piece has a varying lateral extent over at least part of the measuring section. Preferably, only the lateral extent of the part of the at least one flux guide piece facing away from the permanent magnet varies, whereas the part of the at least one flux guide piece facing the permanent magnet has a uniform lateral extent and, for example, rests against the permanent magnet with an end face or (preferably) a part of its flat side.

[0069] In a further development of this embodiment, the at least one flux guide piece has a varying lateral extent over the entire length of the measuring section. In this case as well, preferably only the lateral extent of the part of the at least one flux guide piece facing away from the permanent magnet varies. In the case of a straight measuring section, a flux guide piece with a trapezoidal contour can be provided for this purpose, for example.

[0070] As already mentioned, the permanent magnet within the scope of the invention can be designed as a ring-shaped (e.g., circular) closed body (e.g., profile). Even then, the embodiments of the at least one flux guide described above can advantageously be provided, in particular, for example, with (at least) one ring-shaped closed flux guide. It should be noted that the cross-section of the flux guide must be reproduced at a certain point along the circumference (at least) every 360°. The term "in the lateral direction" is then to be understood as "in the radial direction." The restriction is fulfilled, for example, if the flux guide or guides have a uniform cross-section along the circumference. However, embodiments are also possible in which the at least one flux guide has a non-uniform cross-section along the circumference (in particular, for example, if...).a non-uniform lateral or radial extent, e.g., on its radially outer side facing the measuring section. In one embodiment, a periodically changing radial extent of the at least one flow guide piece is provided along the circumference, wherein, viewed over the full circumference (360°) of the system, only one period or several periods (e.g., 2, 3, 4 or more periods) of a circumferential angle-dependent progression of this radial extent may be provided.

[0071] With the (at least one) magnetic field sensor used in the invention, the magnetic field at the location of the magnetic field sensor is measured to determine a direction of the magnetic field, in order to determine the position of the magnetic field sensor along the measuring path running next to the permanent magnet based on the determination of this direction of the magnetic field.

[0072] In one embodiment, the magnetic field sensor is designed to provide (at least) an analog sensor signal (e.g., a voltage signal).

[0073] In one embodiment, the magnetic field sensor is designed to provide (at least) one digital sensor signal (data signal).

[0074] The term "magnetic field sensor" is to be understood broadly within the meaning of the invention insofar as it is generally neither necessary nor expedient in this measurement to measure the magnetic field vector completely at the location of the magnetic field sensor, i.e. with regard to magnitude and direction.

[0075] In a preferred embodiment, the magnetic field sensor is used to measure, for example, (at least) two different magnetic field components and to determine the direction of the magnetic field from these measurements.

[0076] In one embodiment of the invention, the magnetic field sensor is configured to measure at least two components of the magnetic field and to provide a sensor signal that depends on the direction of the magnetic field. This sensor signal can, in particular, represent an angle or angle of rotation by which the direction of the magnetic field deviates from or is rotated from a direction defined by the magnetic field sensor. Such magnetic field sensors are commercially available in a wide variety of designs and can be advantageously used in the invention.

[0077] In one embodiment, the magnetic field sensor is designed as a magnetoresistive sensor, e.g., as a so-called XMR sensor, such as an AMR (anisotropic magnetoresistive), GMR (giant magnetoresistive), or TMR (tunneling magnetoresistive) sensor. Alternatively, the magnetic field sensor can be designed, for example, as a Hall sensor, such as a 2D Hall sensor or a 3D Hall sensor.

[0078] In a more specific embodiment of the invention, the magnetic field sensor is designed to provide a sensor signal (e.g., an analog voltage signal or a digital data signal) representative of an angle of rotation by which the direction of the magnetic field is rotated from a direction defined by the magnetic field sensor and its arrangement in the position measuring system.

[0079] The direction defined in this way can in particular be a lateral direction of the position measuring system, i.e. a horizontal direction orthogonal to the direction of the measuring distance, where the angle of rotation to be measured can in particular be, for example, the angle of rotation resulting in a plane orthogonal to the direction of the measuring distance.

[0080] In one embodiment of a magnetic field sensor that measures the rotation angle of the magnetic field, it is designed to measure the rotation angle within a range of at least 10°, in particular at least 20° (e.g., + / -10°). On the other hand, in many cases it is sufficient if the measurable rotation angle range is a maximum of 90° (e.g., + / - 45°).

[0081] In one embodiment, it is provided that the position dependence of a rotation angle of the magnetic field, determined by the measurement of the magnetic field sensor, along the measuring section can be described, at least section by section, by an at least approximately linear function or by an at least approximately sinusoidal function. For a non-circular measuring section, an at least approximately linear function is preferred in many cases, whereas for a circular measuring section, an at least approximately sinusoidal function is preferred in many cases.

[0082] In one embodiment of the invention, the measuring system includes a characteristic curve compensation device configured to modify (at least) a measurement signal generated by the magnetic field sensor as a function of the magnetic field in a predetermined manner, thus providing a modified sensor signal (for further use or processing).

[0083] In one embodiment, the characteristic curve compensation device is formed by a signal processing circuit arrangement that is an integral part of the magnetic field sensor. Alternatively or additionally, the characteristic curve compensation device, or at least part of the signal processing circuit arrangement forming it, can also be provided separately from the magnetic field sensor. For example, the position measuring system can have an evaluation unit (e.g., a program-controlled electronic evaluation unit) to which a sensor signal generated by the magnetic field sensor is supplied, and which is configured to perform the characteristic curve compensation (or at least part thereof) in order to provide the modified sensor signal.

[0084] In one embodiment, the characteristic curve compensation device is designed as a digital signal processing device to which (at least) a sensor signal generated by the magnetic field sensor in the form of a digital data signal is supplied. Alternatively, it can be provided, for example, that (at least) a digital data signal is supplied to the digital data processing device, which was obtained by analog-to-digital conversion from a sensor signal provided by the magnetic field sensor in analog form.

[0085] In one embodiment, the characteristic curve compensation device is designed to implement a modification of the measurement system characteristic in such a way that the relationship between, on the one hand, the value (analog or digital) of a signal provided by the magnetic field sensor, such as a sensor signal representative of a rotation angle of the magnetic field, and, on the other hand, the position (along the measuring path) can be described more precisely by a relatively simple mathematical function, in particular a linear function ("linearization"), than would be the case without the use of characteristic curve compensation.

[0086] In one embodiment, the characteristic curve compensation device is designed to perform a so-called "multipoint calibration," in which the relevant sensor signal is calibrated (modified) within the relevant value range (e.g., + / - 45%) using a compensation curve, where this compensation curve is defined for this value range by several support points. For example, the support points (or the data representing them) can be stored in the characteristic curve compensation device. During operation of the position measuring system, the device can perform the corresponding compensation based on the support points or a compensation curve determined therewith (e.g., by multiplying the value represented by the sensor signal by a correction factor derived from the compensation curve for that value).

[0087] Although, as already mentioned, a certain adjustment of the measuring system characteristic can already be advantageously achieved in the invention by suitable arrangement and design of one or more flow guide pieces, an additional use of the described characteristic curve compensation can advantageously further improve this adjustment with regard to its accuracy and / or enable further degrees of freedom of adjustability.

[0088] In a particularly advantageous embodiment, the measuring section is tilted relative to the (horizontal) path of the permanent magnet and / or one or more flux guides, such that the (vertical) positions of the two ends of the measuring section differ significantly from one another. This tilting occurs between the two ends of the measuring section, where the section is inclined (relative to the path of the permanent magnet or flux guide, or relative to the horizontal). In particular, a uniform angle of inclination of the inclined measuring section relative to the path of the permanent magnet and / or flux guide can be provided along the entire length of the measuring section.

[0089] Equivalently, one could also speak of a tilting of the arrangement formed from the permanent magnet and flux guide(s) with respect to a (horizontal) path of the measuring section. The relative tilting of the aforementioned components to each other is essential for this embodiment.

[0090] The tilting leads to a corresponding modification of the measurement system characteristics. It has proven particularly advantageous that the defined tilt allows the magnetic field sensor to be guided along the measuring path in a more homogeneous field, thus reducing the sensitivity of the measurement system characteristics and / or measurement accuracy to mechanical tolerances (e.g., play in the horizontal and / or vertical direction, as well as manufacturing and / or assembly tolerances).

[0091] In one embodiment, the aforementioned angle of inclination (or, in the case of a non-uniform angle of inclination, its value averaged over the measuring distance) is at least 1°, in particular at least 2°. On the other hand, in many cases a value of a maximum of 10°, in particular a maximum of 5°, is expedient.

[0092] According to a further aspect of the invention, the use of a position measuring system of the type described herein as a linear position measuring device or an angular position measuring device on a linearly adjustable component or a rotatable component of a vehicle is proposed. A turbocharger flap or a valve flap of a motor vehicle could be considered a rotatable component, for example.

[0093] The invention is further described below with reference to exemplary embodiments and the accompanying drawings. These depict: Fig. 1 a position measuring system according to a first embodiment, Fig. 2. A diagram illustrating an ideal and a real position dependence of the magnetic field using the example of the in Fig. 1 position measuring system shown, Fig. 3 a magnetic field sensor that can be used in a position measuring system, Fig. 4 a position measuring system according to a further embodiment, Fig. 5. A representation illustrating the magnetic field for the in Fig. 4 position measuring systems shown, Fig. 6 a position measuring system according to a further embodiment, Fig. 7 a position measuring system according to a further embodiment, Fig. 8 a position measuring system according to a further embodiment, Fig. 9. A representation illustrating characteristic curve compensation in a position measuring system. Fig. 10 a block diagram of a magnetic field sensor of a position measuring system according to an exemplary embodiment, Fig. 11 a position measuring system according to a further embodiment, in a top view, Fig. 12 the position measuring system of Fig. 11 in several cross-sectional views, Fig. 13 a position measuring system according to a further embodiment, in a top view, Fig. 14 the position measuring system of Fig. 11 in several cross-sectional views, Fig. 15 a position measuring system according to a further embodiment, in a top view, and Fig. 16 and Fig. 17 exemplary curves of positions measured using magnetic field sensors in the position measurement system of Fig. 15 specific magnetic field angles.

[0094] Fig. Figure 1 shows a first embodiment of a position measuring system 10, comprising a permanent magnet 12 and a magnetic field sensor 16 which is movably arranged along a measuring section 14 running laterally next to the permanent magnet 12.

[0095] With this position measuring system 10, the position of the magnetic field sensor 16 along the measuring path 14 can be determined based on the direction of the magnetic field determined by the magnetic field sensor 16. It is irrelevant whether, in practical use of the position measuring system in a specific installation environment (technical equipment, such as a vehicle), the permanent magnet is fixed and the magnetic field sensor is moved within this installation environment, or whether, conversely, the magnetic field sensor is fixed and the permanent magnet (including the flux guides described below) is moved. Therefore, the measurement depends solely on the relative position or relative movement of the magnetic field sensor relative to the permanent magnet. The in Fig. The three arrows 18 shown in Figure 1 illustrate the direction of the magnetic field present at each of three different positions along the measuring section 14.

[0096] In the example shown, the permanent magnet 12 is made of a hard magnetic metal alloy and is designed as an elongated profile. The permanent magnet 12 has a uniform rectangular cross-section (profile cross-section) along its length and has a straight profile axis.

[0097] The measuring section 14, which runs laterally alongside the permanent magnet 12, is also designed to be straight in the illustrated example and runs parallel to the profile axis of the profile of the permanent magnet 12. Thus, the measuring section 14 runs parallel to the permanent magnet 12 or its profile axis at a certain distance in a lateral direction of the position measuring system 10.

[0098] The position measuring system 10 is therefore particularly suitable for linear position detection on a component (e.g. plunger of an electromechanical actuator or the like) which is arranged to be displaceable in a technical device (e.g. vehicle).

[0099] In the example shown, the permanent magnet 12 is homogeneously magnetized, with one magnetization direction being vertically oriented, i.e. orthogonal to the profile axis and orthogonal to the lateral direction of the position measuring system 10.

[0100] In the example shown, the position measuring system 10 further comprises two ferromagnetic flux guide pieces 20-1, 20-2, namely a lower ferromagnetic flux guide piece 20-1, which extends below the measuring section 14 in a plate-like manner on the one hand in the direction of the measuring section 14 and the measuring section 14 and on the other hand in a lateral direction, and an upper ferromagnetic flux guide piece 20-2, which extends above the measuring section 14 in a plate-like manner on the one hand in the direction of the measuring section 14 and the measuring section 14 and on the other hand in a lateral direction.

[0101] In the example shown, the river guide sections 20-1 and 20-2 extend, viewed laterally, on the one hand (in Fig. 1 left) each up to the permanent magnet 12 and lie against it, so that the respective side edges of the flux guide pieces 20-1, 20-2 are flush with the permanent magnet 12. On the other hand (in Fig. 1 right) the flux guide pieces 20-1, 20-2, viewed laterally, extend significantly beyond the measuring section 14 at one of their longitudinal ends, but each has a lateral extension that decreases continuously along the measuring section 14, so that the flux guide pieces 20-1, 20-2 end at their other longitudinal end in the area of ​​the permanent magnet 12 and thus do not project beyond the permanent magnet 12 in the lateral direction.

[0102] The contours of the two river guide pieces 20-1, 20-2 (viewed from above or below) are mirror images of each other with respect to a mirror plane extending vertically in the middle of the measuring section 14.

[0103] In this embodiment, in addition to the shielding effect against potential interference fields achieved by the flux guide pieces 20-1, 20-2, the fact that the non-uniform shape of the flux guide pieces 20-1, 20-2 over the length of the permanent magnet 12 results in a dependence of the magnetic field (see arrows 18 in Fig. 1) is caused by the position of the magnetic field sensor 16 along the measuring section 14. It should be noted that without such flux guide pieces 20-1, 20-2, there would be no dependence of the magnetic field on the position along the measuring section 14 at all for the permanent magnet 12 (apart from "edge effects" at the ends of the measuring section 14, which in the illustrated example extends to both ends of the permanent magnet 12).

[0104] However, the use of the irregularly shaped flow guide pieces 20-1, 20-2 allows the aforementioned dependency to be advantageously created and even qualitatively adjusted to a certain extent as desired. This would allow for deviations from the straight courses provided in the example shown. Fig. 1. The right side edges of the flow guide pieces 20-1, 20-2, for example, are provided with curved and / or angled profiles such that the dependence of the magnetic field on the position along the measuring section 14 is modified accordingly.

[0105] Fig. Figure 2 shows an exemplary embodiment, here for the embodiment of Fig. 1. Dependence of the direction of the magnetic field on the position shown.

[0106] The direction of the magnetic field is determined by Fig. 2 is represented by an angle “ang” of the magnetic field direction with respect to the vertical direction, and the position along the measuring section 14 is represented by a normalized position parameter “pos” (pos=0% at the beginning of the measuring section, pos=50% in the middle of the measuring section, pos=100% at the end of the measuring section).

[0107] When the magnetic field sensor 16 is moved along the measuring section 14 ( Fig. 1) The angle “ang” varies between the values ​​a1 (at pos=0%) and α2 (at pos=100%). In the example of Fig. 1 α2 = -α1.

[0108] The solid line in Fig. Figure 2 shows the actual position dependence of the angle "ang", whereas the dashed line in Fig. 2 represents a dependency that is usually preferred in practice, in which the angle “ang” changes linearly with the position “pos”.

[0109] By appropriately selecting the arrangement and shape of one or more flux guide pieces (stationary relative to the permanent magnet, and in particular, for example, connected to or adjacent to it), the position dependence of the magnetic field can be advantageously influenced in the invention, for example, to achieve or at least approximate the ideal dependence described above.

[0110] Fig. Figure 3 shows again, in isolation, the embodiment of Fig. 1 a magnetic field sensor 16 is used, which provides a sensor signal dependent on the direction of the magnetic field, which is representative of the angle or rotation angle “ang” by which the direction of the magnetic field is rotated from a direction defined by the magnetic field sensor.

[0111] Fig. Figure 3 also illustrates the angle measuring range of the magnetic field sensor 16, which in this example extends over a range of + / - 45°. When used in the position measuring system 10 of Fig. 1. The rotation angle “ang” to be measured lies in a plane orthogonal to the direction of the measuring section 14.

[0112] In the following description of further embodiments, the same reference numbers are used for identically functioning components, each supplemented by a lowercase letter to distinguish the embodiment. Essentially, only the differences from the embodiment(s) already described are addressed, and otherwise, reference is expressly made to the description of the preceding embodiments.

[0113] Fig. Figure 4 shows a further embodiment of a position measuring system 10a, which, as can be seen from the following explanation, differs in two aspects from the example of Fig. 1 distinguishes: On the one hand, the position measuring system 10a has an inhomogeneously magnetized permanent magnet, and on the other hand, uniformly shaped flux guide pieces are used.

[0114] The in Fig. The position measuring system 10a shown in section 4 exhibits, as in the example of Fig. 1 a permanent magnet 12a designed as an elongated profile with a rectangular profile cross-section and a straight profile axis, to which a measuring section 14a runs laterally offset, along which a magnetic field sensor 16a can be moved.

[0115] However, the permanent magnet 12a is inhomogeneously magnetized, with the illustrated example featuring a magnetization pattern that is oriented everywhere orthogonally to the profile axis of the permanent magnet 12a and varies helically along the profile axis. A (local) direction of magnetization depends only on the position along the profile axis of the permanent magnet 12a.

[0116] The position measuring system 10a comprises, as in the example of Fig. 1 furthermore a lower ferromagnetic flux guide piece 20-1, which extends below a measuring section 14a in a plate-like manner on the one hand in the direction of the measuring section 14a and following it and on the other hand in a lateral direction, as well as an upper ferromagnetic flux guide piece 20a-2, which extends above the measuring section 14a in a plate-like manner on the one hand in the direction of the measuring section 14a and following it and on the other hand in a lateral direction.

[0117] However, in the position measuring system 10a, the arrangement and shape of the flux guide pieces 20a-1, 20a-2 are uniform over the length of the permanent magnet 12a insofar as the flux guide pieces 20a-1, 20a-2 extend laterally with a constant extent (plate width). Therefore, there is no significant qualitative change in the position dependence of the magnetic field (see arrows 18 in Fig. 4), which is already achieved here by the inhomogeneous helical magnetization. However, a high shielding effect with regard to interference fields is advantageously obtained, and furthermore, a certain amplification of the magnetic field in the area of ​​the measuring section 14a is advantageously achieved.

[0118] In the example shown, the river guide pieces 20a-1 and 20a-2 each have a rectangular contour.

[0119] In contrast, the arrangement and / or shape of the flux guide pieces 20a-1, 20a-2 along the length of the permanent magnet 12a could be modified to modify the dependence of the magnetic field on the position of the magnetic field sensor 16a along the measuring section 14a. For this purpose, the straight paths of the Fig. The 4 right-hand side edges of the river guide pieces 20-1, 20-2 are replaced by curved and / or angled courses.

[0120] Even in the case of such a modification, it is usually advantageous if the contours of the two flow guide sections, relative to a mirror plane extending vertically in a central region of the measuring section 14a, continue to be mirror images of each other. It is also usually advantageous if the modified side edges continue to project beyond the measuring section 14a when viewed laterally.

[0121] Fig. Figure 5 shows three different cross-sections of the in Fig. 4 position measuring system 10a shown, for positions with pos=0%, pos=50% and pos=100% along the measuring section 14a, magnetic field lines of the magnetic field determined by corresponding simulation calculations.

[0122] Furthermore, it illustrates Fig. 5. An example compared to the examples of the Fig. 1 and Fig. 4. Modified embodiment, which consists in the fact that the measuring section is tilted with respect to a horizontal course of one or more flow guide pieces, such that the vertical positions of the two ends of the measuring section differ significantly from each other. This modification is described in Fig. As can be seen in Figure 5. While in the middle of the measuring section (pos=50%) the magnetic field sensor 16a (and thus the measuring section) is located vertically in the middle between the flow guide pieces 20a-1 and 20a-2, the magnetic field sensor 16a and the corresponding sections of the measuring section are offset vertically upwards (for pos=0%) and downwards (for pos=100%) at both ends of the measuring section (pos=0% and pos=100%). In particular, a uniform inclination angle of the inclined section with respect to the horizontal direction, in the range of, for example, approximately 1° to 5°, can be provided over the length of the measuring section.This modification advantageously reduces the sensitivity of the measuring system characteristic and thus the measuring accuracy to mechanical play as well as mechanical manufacturing and assembly tolerances, since the magnetic field sensor 16a is moved in an area where a more homogeneous magnetic field prevails.

[0123] Fig. Figure 6 shows a further embodiment of a position measuring system 10b, which differs from the one shown in Fig. The position measuring system 10a shown in section 4 differs in that a profile axis of a permanent magnet 12b and, accordingly, a measuring section 14b running parallel to it, do not run in a straight line but are curved in a circular arc. The Fig. The arc angle α shown in the diagram is approximately 45°, but can be adjusted to other values ​​depending on the specific application. In particular, it could deviate from... Fig. 6. An arc angle α of 360° may also be provided. In this case, the permanent magnet would be designed as a closed, annular profile, in which the measuring section can also run in a closed, annular shape around the permanent magnet (radially outside it), whereby a magnetization varying helically along the profile axis must be reproduced (at the latest) every 360° as one progresses along the circumference (examples of this are given below with reference to the Fig. 11 and Fig. 12 as well Fig. 13 and Fig. 14 explained).

[0124] The position measuring system 10b is therefore suitable, for example, for measuring the angle of rotation on a rotatably mounted component (e.g., a rotating shaft on a turbocharger flap or a valve flap) of a technical device (e.g., a vehicle). In such an application, the arrangement formed from permanent magnet 12b and flux guide pieces 20b-1, 20b-2 can be attached to the rotating shaft in question, so that it rotates with the shaft, while a magnetic field sensor 16b can be stationary at the appropriate lateral distance. When the rotating shaft rotates, the magnetic field sensor 16b then moves relative to the permanent magnet 12b along the measuring section 14b.

[0125] Apart from the curved, here circular arc-shaped design of the position measuring system 10b and thus measurement along a circular arc, this system functions like the one with reference to Fig. 4 systems described.

[0126] This also refers to Fig. The position measuring system 10 described in section 1 can be designed in a curved form, in particular a circular arc, either with an arc angle of less than 360° or with an arc angle of 360° (i.e., closed in a ring). The possible details and configurations described for the position measuring system 10 (or 10a) with reference to the length of the permanent magnet or the measuring section, and with reference to the lateral direction, can also be used for curved versions. It should be noted that the length is then curved and therefore there is no longer a uniform lateral direction of the system, but rather the lateral direction varies along the length (the lateral direction is then orthogonal to the orientation of the longitudinal direction at every point and can then also be referred to as the radial direction).

[0127] Fig. Figure 7 shows a further embodiment of a position measuring system 10c, which differs from the one shown in Fig. The position measuring system 10a shown in Figure 4 differs in that a permanent magnet 12c is designed as an elongated body with a cross-section that varies over its length (path).

[0128] In the illustrated embodiment, the permanent magnet 12c has a uniform (non-varying) cross-sectional area along its length. However, the cross-sectional shape varies. The cross-section has the form of a quadrilateral, in which the orientation of one side of the quadrilateral facing the measuring section 14c varies along the length of the permanent magnet 12c. This side of the quadrilateral runs vertically along the midpoint of the permanent magnet's length, and the cross-section is rectangular there. However, with increasing distance from the midpoint, this side becomes increasingly oblique to the vertical.

[0129] In the example shown, the side of the quadrilateral runs at an angle to the vertical, which varies strictly monotonically along the length of the permanent magnet and, in particular, is proportional to the position along this length.

[0130] In the example shown, the angle with respect to the vertical varies overall (over the full length of the permanent magnet 12c) by an angle of 90°.

[0131] The permanent magnet 12c is like the one in the example of Fig. 4 inhomogeneously magnetized, wherein a magnetization oriented everywhere orthogonally to the profile axis of the permanent magnet 12c, varying in a helical manner along the profile axis, is provided.

[0132] In many cases, it is preferred that the angle by which the magnetization rotates along the course of the permanent magnet 12c is at least approximately equal to the angle (e.g., with a deviation of a maximum of 20°, in particular a maximum of 10°) by which the orientation of the aforementioned quadrilateral side rotates along the course of the permanent magnet 12c. This is the case in the example of Fig. 7 the case in which the direction of magnetization changes by 90° in the course of the permanent magnet 12c.

[0133] Fig. Figure 8 shows a further embodiment of a position measuring system 10d, which differs from the one shown in Fig. The position measuring system 10c shown in section 7 differs in that the path (e.g., longitudinal center axis) of a permanent magnet 12d and, accordingly, a measuring section 14d running parallel to it, are not straight but curved in a circular arc. Otherwise, the example corresponds to Fig. 8 in structure and function, using the example of Fig. 7.

[0134] The 10d position measuring system is therefore suitable (as is, for example, the one in Fig. 6 Position measuring system 10b) shown, for example, for measuring the angle of rotation on a rotatably mounted component of a technical device (e.g. vehicle).

[0135] That with reference to Fig. The position measuring system 10d described in section 8 can be implemented in a closed, ring-shaped (e.g., circular) form according to one modification. To reproduce the cross-section and magnetization every 360°, a possible modification would be, for example, to... Fig. 8. The variation of the cross-section and magnetization shown is to be provided for a first 180° partial circumference and inverted for a subsequent second 180° partial circumference (so that the cross-section and magnetization at the end of the second 180° partial circumference correspond to those at the beginning of the first 180° partial circumference). More generally, a variation of the cross-section and magnetization (such as that shown in 8) could be used to achieve the following results: Fig. The variation of the cross-section and magnetization shown in Figure 8 and its inverted variation are provided alternately for an even number "n" of more than two consecutive partial circumferences that complement each other to form a full 360° circumference. For n=4, this would be, for example, four 90° partial circumferences, for n=6 six 60° partial circumferences, for n=8 eight 45° partial circumferences, and so on.

[0136] Fig. Figure 9 illustrates a characteristic curve compensation that can be optionally used in any position measurement system of the type described here, which serves to modify (at least) one measurement signal generated by the (at least one) magnetic field sensor depending on the magnetic field in a predetermined way and thus to provide a modified sensor signal (for further use or further processing).

[0137] Fig. Figure 9 shows in the upper part an example plot of a relative error “err” of the sensor signal generated by the magnetic field sensor as a function of the position or here the normalized position parameter “pos” (pos=0% at the beginning of the measuring distance, pos=50% in the middle of the measuring distance, pos=100% at the end of the measuring distance).

[0138] If the measuring section has a ring-shaped (e.g., circular) closed path, then 0% and 100% denote the same point on the measuring section, and pos=0% can be interpreted, for example, as an angular position of 0° and pos=100% as an angular position of 360°.

[0139] The relative error "err" to be eliminated or at least reduced by means of characteristic curve compensation can, in principle, be defined arbitrarily as the ratio between the "real" value (e.g., digital value) represented by the sensor signal and an (arbitrarily) predefined "ideal" value. In practice, a value that varies linearly with position (linearization) is usually desirable as the ideal value. However, in a specific application, another mathematical function might be desirable to describe an "ideal" measurement system characteristic.

[0140] The relative error "err" or its position-dependent curve "err(pos)" can be determined empirically, for example. A digital representation of this curve can then be stored in a characteristic curve compensation device, such as a (particularly program-controlled) digital signal processing device, especially as an error curve defined by several data points (see...). Fig. 9 above), which can then be used in the operation of the position measuring system in question as a compensation curve (or to determine a compensation curve).

[0141] During operation of the position measurement system, each measured value generated by the magnetic field sensor during its magnetic field measurement can be modified (corrected) using pre-stored reference points or a resulting compensation curve so that the modified value corresponds more or less exactly to the "ideal" value. For example, each value represented by the original sensor signal can be multiplied by a correction factor derived from a compensation curve for that value.

[0142] Fig. Figure 9 shows an example plot of the relative error “err” for a sensor signal modified (corrected) in this way as a function of the normalized position parameter “pos”. As can be seen, the relative error has been drastically and advantageously reduced.

[0143] In one embodiment, the characteristic curve compensation is performed wholly or at least partially by the magnetic field sensor, which in this case must be equipped with appropriate electronics, in particular, for example, digital signal processing electronics. Alternatively, the characteristic curve compensation can also be performed in a separate (e.g., program-controlled electronic) evaluation unit, to which (at least) a sensor signal generated by the magnetic field sensor (and, for example, representative of an angle of the magnetic field direction) is supplied, and which generates the correspondingly modified sensor signal from this and, if necessary, further evaluates it (depending on the purpose of the position measurement).

[0144] Fig. Figure 10 shows a block diagram illustrating an embodiment of a magnetic field sensor 16 that can be used for a position measuring system of the type described here. The magnetic field sensor 16 shown can thus be used, in particular, for example, in each of the above-mentioned applications with reference to the Fig. 1, Fig. 4, Fig. 6, Fig. 7 and Fig. The 8 systems described are used.

[0145] The magnetic field sensor 16 has two magnetoresistive sensor units 30-1 and 30-2, which are configured to measure two magnetic field components of the magnetic field associated with directions orthogonally oriented to each other, i.e. to provide two analog electrical signals “x” and “y” each representing one of these components.

[0146] In the example shown, the signals x and y are each amplified by one of two amplifiers 32-1 and 32-2 and converted into digital signals by means of a respective A / D converter 34-1 or 34-2.

[0147] The digital signals are fed to an angle calculation unit 36, in which the direction (angle) of the magnetic field is calculated from the two component signals.

[0148] The angle of the magnetic field calculated by the angle calculation unit 36 ​​is corrected by means of a characteristic curve compensation unit 38, and the corrected angle is output via an interface unit 40.

[0149] The angle calculation unit 36 ​​and the characteristic curve compensation unit 38 can, in particular, be implemented as functional parts of a calculation unit, which is designed in the form of a program-controlled electronic computer device (e.g., a microcontroller). Data required for characteristic curve compensation can be stored in advance in a memory unit 42, which the characteristic curve compensation unit 38 accesses when correcting the angle.

[0150] In summary, the Fig. 10 The magnetic field sensor 16 shown is designed to measure two magnetic field components of the magnetic field and to provide a sensor signal that depends on the direction of the magnetic field, but is advantageously linearized.

[0151] The Fig. Figures 11 to 17 show exemplary embodiments of position measuring systems 10e ( Fig. 11 and Fig. 12), 10f ( Fig. 13 and Fig. 14) and 10g ( Fig. 15 to 17) to illustrate the embodiment of interest for certain applications within the scope of the invention, in which a ring-shaped, here circularly closed course of a measuring section is provided radially outside a permanent magnet 12e, 12f or 12g running parallel to it and here also circularly closed.

[0152] Another advantageous feature of these embodiments is that both a lower (first) flux guide piece 20e-1, 20f-1 or 20g-1 extending below the measuring section and an upper (second) flux guide piece 20e-2, 20f-2 or 20g-2 extending above the measuring section are provided, wherein these flux guide pieces terminate radially inside flush with an inner circumference of the permanent magnet.

[0153] The Fig. 11 and Fig. Figure 12 shows a embodiment in which the flow guide pieces 20e-1, 20e-2 have a uniform lateral (radial) extent over the entire length (circumference) of the measuring section, and, as shown, can extend slightly radially outwards beyond the measuring section in this radial direction. Thus, the flow guide pieces 20e-1, 20e-2 are each annular in shape with a uniform width.

[0154] A dependence of the direction of the magnetic field of the permanent magnet 12e on the position (circumferential position or circumferential angle position) of a magnetic field sensor 16e required for position measurement ( Fig. 12) along the measuring section is realized by an inhomogeneous magnetization, here a helical magnetization varying along the length (circumference) of the permanent magnet 12e.

[0155] The Fig. 12A to 12D are cross-sections at the in Fig. The 11 circumferential positions “A” (circumferential angle position = 0°) to “D” (circumferential angle position = 270°) are shown and illustrate the magnetization varying helically along the circumference.

[0156] In the example shown, the magnetization direction varies over a full circumference (360°), for example, at least approximately sinusoidally within a range of + / - 15° (deviation from the vertical). As can be seen from the Fig. Figures 12A to 12D show that, when viewed over the entire circumference (360°), one period of a circumferential angle-dependent magnetization direction is provided. However, in contrast to this example, multiple periods (e.g., 2, 3, 4 or more) could also be provided.

[0157] The Fig. 13 and Fig. Figure 14 shows a design in which the flow guide pieces 20f-1, 20f-2 have a non-uniform lateral (radial) extent when viewed over the course (circumference) of the measuring section, and in this radial direction, as shown, they extend, for example, slightly beyond the measuring section over part of their circumference and less far than the measuring section over another part of their circumference.

[0158] The dependence of the direction of the magnetic field of the permanent magnet 12f on the position (circumferential position or circumferential angle position) of a magnetic field sensor 16f required for position measurement ( Fig. 14) along the measuring section is realized in this example by an inhomogeneous magnetization, here a helical magnetization varying along the length (circumference) of the permanent magnet 12f, and is further enhanced to a certain extent by the non-uniform lateral (radial) extension of the flux guide pieces 20f-1, 20f-2.

[0159] The Fig. 14A to 14D are cross-sections at the in Fig. The 13 marked circumferential positions “A” (circumferential angle position = 0°) to “D” (circumferential angle position = 270°) illustrate the helically varying magnetization along the circumference, which is thus just like in the example of the Fig. 11 and Fig. 12 can be provided for, i.e., when viewed along the circumference, it can vary at least approximately sinusoidally and / or when viewed over the full circumference (360°) can perform one or more periods (e.g. sine periods) of a circumferential angle-dependent course.

[0160] According to a modification of the one in the Fig. 13 and Fig. In the example shown in 14, the permanent magnet (12f) could be homogeneously magnetized, in particular with a magnetization direction oriented at least approximately vertically.

[0161] The Fig. Figure 15 shows a design in which a permanent magnet 12g and flux guide pieces 20g-1, 20g-2, as well as, for the example of the Fig. 11 and Fig. The components described in section 12 are designed as described. However, the permanent magnet 12g and the flux guide pieces 20g-1, 20g-2 could also be designed differently.

[0162] It becomes advantageous in the Fig. In the example shown in Figure 15, two magnetic field sensors, 16g-1 and 16g-2, are used. These sensors are movably arranged along the measuring section running laterally (radially) next to the permanent magnet 12g, but are offset from each other by 90° along the measuring section. Thus, the position along the measuring section can advantageously be determined using the magnetic fields measured by both magnetic field sensors, 16g-1 and 16g-2.

[0163] The Fig. 16 and Fig. Figure 17 shows exemplary progressions of the angles “ang1” and “ang2” of the magnetic field direction with respect to the vertical determined by means of the magnetic field sensors 16g-1 and 16g-2 as a function of a position (circumferential angle position) along the measuring distance.

[0164] When the magnetic field sensor 16g-1 is moved along the measuring path, the angle “ang1” varies in the example shown as shown. Fig. 16 evidently at least approximately sinusoidal, whereas the angle “ang2” appears as from Fig. 17. The variation is evidently at least approximately cosine-shaped. In the example, the position (circumference position) can be advantageously and uniquely determined from the two simultaneously determined values ​​of "ang1" and "ang2".

[0165] The actual position dependence of the angles "ang1" and "ang2" can be modified by a suitably adapted shape design of the flow guide pieces and / or by using a characteristic curve compensation (as described above) so that the position dependence is described more precisely by a desired mathematical function, here e.g. a sine or cosine function, than would be the case without characteristic curve compensation.

Claims

[1] Position measuring system (10) comprising a permanent magnet (12) and a magnetic field sensor (16) movably arranged along a measuring section (14) running laterally next to the permanent magnet (12) in order to be able to determine a position of the magnetic field sensor (16) along the measuring section (14) on the basis of a direction of the magnetic field determined by means of the magnetic field sensor (16), characterized by, that the position measuring system (10) further comprises at least one ferromagnetic flux guide piece (20-1, 20-2) which extends below or above the measuring section (14) in a plate-like form on the one hand in the direction of the measuring section (14) and following at least a part of the measuring section (14) and on the other hand in a lateral direction, wherein the at least one flux guide piece (20-1, 20-2) has the form of a flat plate, the plane of which extends below or above the measuring section (14) on the one hand at least approximately parallel to the measuring section (14) and on the other hand in a lateral direction. [2] Position measuring system (10) according to claim 1, wherein the permanent magnet (12) is designed as an elongated profile. [3] Position measuring system (10) according to claim 1, wherein the permanent magnet (12) is designed as an elongated body with a cross-section varying over its length. [4] Position measuring system (10) according to claim 1 or 2, wherein the permanent magnet (12) is homogeneously magnetized. [5] Position measuring system (10) according to claim 4, wherein the permanent magnet (12) is designed as an elongated profile and is magnetized orthogonally to a profile axis of the profile. [6] Position measuring system (10) according to one of claims 1 to 3, wherein the permanent magnet (12) is inhomogeneously magnetized. [7] Position measuring system (10) according to one of the preceding claims, comprising: - a lower ferromagnetic flux guide piece (20-1) which extends below the measuring section (14) in a plate-like manner on the one hand in the direction of the measuring section (14) and following at least a part of the measuring section (14) and on the other hand in a lateral direction, and - an upper ferromagnetic flux guide piece (20-2) which extends above the measuring section (14) in a plate-like manner on the one hand in the direction of the measuring section (14) and following at least a part of the measuring section (14) and on the other hand in a lateral direction. [8] Position measuring system (10) according to one of the preceding claims, wherein the at least one flux guide piece (20-1, 20-2) extends at least one point in the course of the measuring section (14) in a lateral direction up to the permanent magnet (12), in particular in contact with the permanent magnet (12). [9] Position measuring system (10) according to one of the preceding claims, wherein the at least one flow guide piece (20-1, 20-2) extends at least one point in the course of the measuring section (14) in a lateral direction up to or beyond the measuring section (14). [10] Position measuring system (10) according to one of the preceding claims, wherein the at least one flow guide piece (20-1, 20-2) has a varying lateral extent over at least part of the course of the measuring section (14). [11] Position measuring system (10) according to one of the preceding claims, wherein a tilting of a path of the measuring section (14) with respect to a path of the permanent magnet (12) and / or the at least one flux guide piece (20-1, 20-2) is provided such that the vertical positions of the two ends of the measuring section (14) differ from each other, so that the measuring section (14) between these two ends is inclined with respect to the path of the permanent magnet (12) or of the at least one flux guide piece (20-1, 20-2) from one end to the other end. [12] Position measuring system (10) according to claim 1 or according to one of claims 4 and 6 to 9, insofar as they refer exclusively to claim 1, wherein the permanent magnet (12) is designed as a ring-shaped closed body. [13] Position measuring system (10) according to one of the preceding claims, wherein the magnetic field sensor (16) is configured to measure at least two magnetic field components of the magnetic field and to provide a sensor signal that depends on the direction of the magnetic field. [14] Position measuring system (10) according to claim 1, in particular wherein the permanent magnet (12) is homogeneously magnetized, in particular with a magnetization direction oriented substantially orthogonal to a course of the permanent magnet (12), in particular with a magnetization direction oriented substantially vertically, wherein the at least one flux guide piece (20-1, 20-2) extends laterally along the entire length of the measuring section (14) up to the permanent magnet (12) and is in contact with the permanent magnet (12), extends laterally along the measuring section (14) at at least one point up to or beyond the measuring section (14) and has a varying lateral extent over at least part of the length of the measuring section (14). [15] Position measuring system (10) according to claim 1, wherein the permanent magnet (12) is inhomogeneously magnetized, in particular with a magnetization direction that is oriented substantially orthogonally to a course of the permanent magnet (12) and varies along the course of the permanent magnet (12), wherein at least one flux guide piece (20-1, 20-2) extends laterally along the entire length of the measuring section (14) on the one hand to the permanent magnet (12) and is in contact with the permanent magnet (12) and on the other hand extends to the measuring section (14) or beyond the measuring section (14). [16] Position measuring system (10) according to claim 15, wherein the permanent magnet (12) is designed as an elongated body with a cross-section varying over its length, in particular wherein the cross-section has the shape of a quadrilateral in which the orientation of one side of the quadrilateral facing the measuring section (14) varies over the length of the permanent magnet (12). [17] Position measuring system (10) according to claim 1 or 15 or according to one of claims 4, 6 to 9 and 13, insofar as it refers exclusively to claim 1, wherein the permanent magnet (12) is designed as a ring-shaped closed body and the measuring section (14) is, for example, also ring-shaped closed laterally next to the permanent magnet (12) along the permanent magnet (12).

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