DE102015104795B4 - Axially multi-pole magnetized magnet, device with magnetically multipole magnetized magnet, use of the device for detecting the rotation angle and use of the device for electrical commutation in electric motors - Google Patents

Abstract

Axial multi-pole magnetized magnet (10, 40, 100) having at least in a radial region a thickness D (φ) varying over the angle of rotation (φ), the thickness D (φ) resulting from the addition of a constant D and the magnitude a sum of cosine functions having a fundamental and its odd harmonics, comprising at least terms up to the fifth harmonic, where N is a predetermined positive integer, DNull or a positive, the quotient D / your is negative, and the quotient D / is your positive value, ABS ( D) ≥ABS (D) ≥ABS (D) and where ABS [] and ABS () respectively denote the respective amount of the number enclosed by the bracket.

Description

The invention relates to an axially multi-pole magnetized magnet, as it is particularly useful for non-contact rotation angle detection, and a device for angle detection using such a magnet.

Such non-contact devices have gained widespread use in many areas of vehicle technology and automation technology. The detection of the rotational angle of a component, such as a shaft, can be realized in that a donor magnet is attached to the rotating component and the magnetic field generated by the donor magnet formed as a permanent magnet or a magnetic field gradient by means of one or more axially before or laterally next to the Encoder magnet arranged sensor elements is detected. In contrast to the co-rotating transmitter magnet while the sensor elements can be fixedly attached to the device, such as a housing part. Depending on the specific application, various sensor elements, for example Hall sensors, sensors based on the AMR effect (anisotropic magnetoresistive effect) or sensors based on the GMR effect (giant magnetoresistance effect) can be used to detect the magnetic field or a magnetic field gradient ,

For the accuracy and the speed of the rotation angle detection, in addition to the quality and the response behavior of the sensor elements, the magnetic field generated by the transmitter magnet at the respective sensor location are decisive variables. In particular, axially multi-pole magnetized magnets, which are often formed as a round magnet and which are magnetized parallel to the axis of rotation, so that north and south poles or a plurality of north and south poles are arranged on a respective end face, have in relation to the generated at the sensor site axial Magnetic field, ie with respect to the magnetic field component generated in the direction of the rotation axis, a complex behavior. This complex behavior in the change of the magnetic field component considered in the rotation of the magnet makes i.d.R. Complex calculations to minimize the error in the rotation angle detection required.

6 shows a schematic representation of a conventional device using a conventionally designed ring magnet 80 for determining the rotational position of a shaft 70 , The shaft extends 70 through a center hole of the ring magnet 80 , which is firmly fixed to the shaft and thus turns with this. In contrast, two are in relation to the axis of rotation 70 by 90 ° circumferentially spaced and arranged at the same radial distance from the shaft magnetic field sensors in the form of Hall sensors 90 . 91 provided, which fixed over a face 83 of the magnet are mounted, for example, fixed to a housing, not shown. As a result of the movement of the shaft, the ring magnet rotates relative to the stationary sensors 90 . 91 , As shown in the figure, the sensors are pointing 90 . 91 a predetermined distance in the axial direction of the shaft and detect the respective, existing at the location of the sensors magnetic field which varies with the rotation of the shaft at each location. The conventionally designed magnet 80 has two mutually parallel planar end faces 83 . 82 on and is designed here as an axially two-pole magnetized magnet which is magnetized parallel to the axis of rotation, so that north or south pole are arranged on a respective end face. Because the magnet 80 is formed axially two-pole, this has a parting plane, not shown in the figure with respect to the magnetization in the magnet, which by the dividing line between the north and south pole at one end face and the axis of the magnet or the axis of rotation of the shaft 70 is set so that this plane is centered to the magnet.

At the rotation of the shaft 70 or the magnet 80 this varies at the location of a sensor 90 . 91 prevailing magnetic field as a function of the angle of rotation of the shaft 70 , A typical course of the measured field at one of the two sensors is in 7 specified as a function of the angle of rotation. The two sensors detect this field profile due to their circumferential spacing phase-shifted, if they are arranged at the same axial height and also constructed and oriented identically. How out 7 As can be seen, the field pattern, which repeats after a full rotation of 360 °, is comparatively complex with the consequences described above with respect to the accuracy and the response behavior of the rotation angle detection device.

The publication DE 102 32 559 A1 relates to an axially multi-pole magnetized magnet in the form of a magnetic code disc, which consists of two joined similar basic bodies, each of these base body having in the measuring direction successively arranged magnetic elements in a plurality of radially spaced tracks. The code disk has a constant thickness over its extension, wherein the magnetic elements of each of a base body are molded plastic-bonded magnets and laterally to a non-magnetizable carrier. The publication DE 100 12 202 A1 relates to a device for detecting movement quantities of a device part on the basis of the detection of measured values of a magnetic and / or induction interaction effect which occurs between an information pattern arranged on the device part and at least one measuring device sensitive to the interaction effect. During the movement of the device part, the information pattern passes the measuring device, so that the information contained in the information pattern as a modulation of the magnitude of the interaction effect is detected by the measuring device as a signal voltage. The information pattern has a period of a periodic function for a predetermined length in the direction of movement, wherein a respective amplitude of this function is contained in a component of the information pattern to be detected by measurement. The publication DE 10 2014 213 846 A1 relates to a magnetic encoder assembly comprising a support plate and a magnetic rubber having a ring shape and fixed to a rear surface of the support plate, the magnetic rubber having a plurality of projecting portions and recessed portions between the projecting portions. The protruding portions and the recessed portions are repeatedly arranged in a rotational direction of the magnetic rubber, the protruding portions being magnetized as the north pole and the recessed portions being magnetized as the south pole. The publication JP 2005-308 559 A relates to a magnetic ring encoder having a plurality of circumferentially spaced ribs for forming an axial multi-pole magnetized magnet. The publication DE 44 423 71 A1 relates to a magnetic encoder ring with magnetic elements arranged in the measuring direction, the encoder ring comprising two assembled base bodies and all magnetic elements of a base body being magnetized in the same direction in a single common direction. The assembled from two basic bodies encoder ring has in the measuring direction alternately a magnetic element of the first base body and the second base body, wherein the magnetic field of the magnetic elements of the one base body in the assembled state is directed opposite to the magnetic field of the magnetic elements of the second base body. The publication DE 10 2009 039 574 A1 relates to an angle measuring system having a magnet coupled to a rotary member and adapted to provide a magnetic field rotating with the rotary member about an axis of the rotary member, comprising an angle sensor disposed in the magnetic field at a radially off-center position the axis of rotation is arranged. The axially multipolar magnetized magnet is designed as a ring magnet with a constant thickness over its extent. The publication DE 10 2005 019 515 A1 relates to a method for measuring the rotational speed of an electronically commutated electric motor having a primary part with a winding and a secondary part with circumferentially offset, magnetized in opposite directions alternately magnetized magnet segments. The publication DE 10 2005 021 300 A1 relates to a rotary encoder with at least one rotatable object and a sensor element, wherein the sensor element outputs an analog signal in dependence on the rotational position of the rotatable object relative to the sensor element and wherein a detected by the sensor element size by a magnetic and / or inductive interaction between the sensor element and a peripheral surface of the rotatable object changes.

The invention has the object of developing a conventional magnetically multipolar magnetized magnet with respect to the magnetic field generated by this in the direction of a rotation axis so that when using such a magnet in particular a position or angle determination simplifies. This object is achieved by the present invention with an axially multipolarly magnetized magnet having the features of claim 1. The inventively embodied magnet has a non-constant thickness with respect to an axis such that at least over a radial region, in particular over the entire radial extent of the magnet, with the rotation angle φ around this axis a varying thickness D ( φ ), the thickness D ( φ ) on the associated circumferential circle, in particular on the entire circumference circle, by adding a constant D ₀ and the amount of a sum of cosine functions with a fundamental ( 1 , Harmonics) and their odd harmonics greater than one (harmonics) is set. According to the invention, this sum comprises at least members up to the fifth harmonic according to D (φ) = D ₀ + ABS [D ₁ * cos (2 ^N-1 * φ) + D ₂ * cos (2 ^N-1 * 3φ) + D ₃ * cos (2 ^N-1 * 5φ)], where N is a given positive integer, D ₀ Is zero or a positive value, the quotient D ₂ / D ₁ a negative and the quotient D ₃ / D ₁ is a positive value and ABS (D ₁ ) ≥ABS (D ₂ ) ≥ABS ( D ₃ ) and wherein ABS [] or ABS () denotes the respective amount of the number enclosed by the bracket. The term "positive value" or "positive integer" may have the meaning "greater than zero" or "whole number greater than zero", where D ₁ * cos (2 ^N-1 * φ) represents the component of the fundamental. The angle ( φ ) can assume values in the range of 0 ° and 360 ° and also as rotation angle or polar angle φ in relation to the axis. The coefficient D ₁ can be a positive or a negative value.

The specified geometric design of the inventively designed, axially multi-pole magnetized magnet has the advantage that from this during its rotation about its axis from a stationary sensor element arranged a field component can be scanned parallel to the axis of rotation, which has a course over the rotation angle, depending extremely close to distance and measuring radius a sinusoidal course is approximated with a very small proportion of harmonics, ie low harmonic distortion.

This symmetrization of the course of the magnetic field component makes it possible, in particular, to perform a rotation angle detection with extremely high accuracy using such a magnet. In addition, calculation time can be saved in the calculation of the rotation angle on the basis of the measured magnetic fields compared to the use of conventional magnets, since otherwise necessary error considerations omitted or must be performed only reduced so that response times of a corresponding measuring device can be significantly reduced. For example, if two sensors on one end side of a magnet according to the invention, which is axially double-pole magnetized, placed circumferentially offset by 90 ° to the magnet, both sensors detect the sinusoidally changing magnetic field in the axial direction with a phase shift of 90 °. For this reason, a value which is equal to the arctangent of the desired rotation angle can be calculated by a simple and quickly feasible quotient formation of the sine wave output signal of the one sensor with the cosine wave output signal of the other sensor.

The inventively embodied magnet may in particular have a ring, disc, or cylindrical shape, but other geometrical configurations are possible. A magnet according to the invention can be designed as a round magnet, but its shape does not have to have ideal rotational or cylindrical symmetry.

The axis of the magnet according to the invention can indicate an excellent direction of the magnet, in particular the orientation of its magnetization and / or with respect to its geometry, although in the latter case no ideal rotational symmetry or cylinder symmetry must be present. In particular, the magnet according to the invention may be designed as a ring magnet having a center hole, for example for receiving a rotary shaft. It should be noted that to implement the invention, the above-defined thickness of the magnet as extension in the z-direction or in the axial direction as a function of the angle of rotation does not have to submit over a complete circumferential circle to the axis, instead the thickness can only partially on a Circumference circle, ie follow the specified sum representation over a rotation angle range.

It is possible according to the invention that the angle of rotation φ changing thickness is not given over the entire radial extent of the magnet according to the summation, but only over a predetermined radial portion, for example over a range bounded by an inner radius and an outer radius. In a further embodiment it can also be provided that the over the rotation angle φ changing thickness only over a range of rotation angle (ie circumferential circle area) and at the same time there over a radius range, or over the entire radial extent of the magnet, the specified sum representation follows.

Further inventive features are given in the general description, the specific description of the figures and the subclaims.

The quality of the sinusoidal profile of the field component can be determined by the measuring radius, ie the radial distance of the sensor to the axis, the measuring distance over the end face, the material homogeneity of the magnet, the homogeneity of the magnetization in the magnet and depending on the number of summation elements in the given Sum display for the variation of the thickness of the magnet over the rotation angle φ depend. Preferably, all of these parameters can be optimized in the design of a magnet according to the invention and graduated according to their influence on the magnetic field generated by the magnet spaced therefrom.

Conveniently, the magnet according to the invention is designed as an axial P-pole, wherein the number of poles P is set by P = 2 ^N , and where N as stated above, is a given positive integer. In this respect, the inventive, axially magnetized magnet can have a plurality of pole changes between south and north poles at a predetermined end face, that is, depending on the design of the magnet 2 . 4 . 8th . 16 . 32 . 64 or 128 or even more pole changes. At the opposite end side, the magnet may have the same number of pole changes.

On one end side of the magnet according to the invention, a dividing line between the north and south poles can be determined by a radius vector perpendicular to the axis to φ (n) = ((180 / P) + n * (360 / P)) Set of natural numbers including zero {0; 1; 2; .... (P-1)}.

An axially 2-pole magnetized magnet corresponding to P = 2 has insofar radial separating lines at φ (n = 0) = 90 ° and φ (n = 1) = (90 + 180) ° = 270 °, so that a separation plane between May result in north and south pole on an end face or the magnetization of the magnet, which is defined by this parting line and its axis, wherein the axis may correspond to the rotation axis in the use of the magnet for detecting the rotation angle.

und $$\phi \left(n=3\right)=\left(45+270\right)°=315°$$

auf.An axially 4-pole magnetized magnet according to the invention corresponding to P = 4 has radially extending separating lines between different pole regions at φ (n = 0) = 45 °, $$\phi \left(n=1\right)=\left(45+90\right)°=135°.\phi \left(n=2\right)=\left(45+180\right)°=225°$$

and $$\phi \left(n=3\right)=\left(45+270\right)°=315°$$

on.

Preferably, one of the end faces of the magnet according to the invention can be made substantially planar, wherein the axis of the magnet can extend perpendicular thereto. In such an embodiment, the variable thickness D ( φ ) as a function of the angle of rotation φ refer to said flat face.

Conveniently, the quotient D ₂ / D ₁ from the two development coefficients D ₂ and D ₁ in the interval from -0.2 to -0.05 and the quotient D ₃ / D ₁ the two development coefficients D ₃ and D ₁ in the interval 0.1 to 0.01. Particularly advantageous is a design of an axial two-pole magnetized magnet according to the invention has been found in which the thickness varies so that the quotients D ₂ / D ₁ = -0.12 and D ₃ / D ₁ = 0.04.

In order to provide an even more symmetrical course of the field component in the axial direction, the thickness D depending on the rotation angle φ be adjusted in consideration of other odd-numbered harmonic development members. This applies, for example, the term D ₄ * cos (2 ^N-1 * 7φ) and optionally D ₅ * cos (2 ^N-1 * 9φ). These terms are added to determine the sum of the other sum members given above, from the sum of the magnitude value and then to the constant D ₀ added.

Conveniently, the coefficient D ₄ negative and the coefficient D ₅ Be zero or positive.

Conveniently, the quotient D ₄ / D ₁ in the range between -0.005 and -0.05 and the quotient D ₅ / D ₁ in the range of 0 to 0.02. Particularly useful may be the quotient D ₄ / D ₁ -0.02 and the quotient D ₅ / D ₁ 0.01.

Preferably, the coefficients D ₁ . D ₂ . D ₃ and optionally D ₄ and D ₅ be chosen so that the course of the axial magnetic field of the magnet according to the invention, ie the course of the magnetic field parallel to the axis at the measuring location over the magnet over a circle circle with constant radius harmonic distortion, ie a harmonic content of less than 2%, in particular less than 1 % or even less than 0.5% with respect to an ideal sinusoidal course. In this case, with high homogeneity of the magnet and complete magnetization by taking into account further summation elements or related coefficients, the symmetrization of the field strength as a function of the rotation angle φ be further improved.

In particular, by adjusting the development coefficients D ₀ . D ₁ . D ₂ . D ₃ and optionally D ₄ and D ₅ Within the specified ranges at the set measuring radius and the measuring distance, the axial magnetic field generated by the magnet at the location of the sensor can be optimally approximated to the desired sinusoidal course.

In principle, the magnet according to the invention can be implemented in a large number of configurations adapted to the respective application. In particular, in disc, ring or cylindrical magnets, the quotient of the outer radius R _a and the thickness D (0 °) accordingly D _max between 1 and 10, especially between 2 and 6. Similarly, the absolute value of the quotient may be the outer radius R _a and the coefficient D ₁ are between about 1 and 10, in particular between about 2 and 6.

Conveniently, the coefficient can be provided D ₀ , ie the thickness D (90 °) = D (270 °) in an axially 2-pole magnetized magnet according to the invention to adjust so that when handling the magnet, in particular during assembly there is no risk of breakage, but that the magnet as a one-piece coherent part is manufactured and processable.

In such cases, in which D ₀ in the development of D ( φ ) is small, so there is a risk of breakage, it may be expediently provided that the thickness D of the magnet does not fall below a certain minimum, ie does not follow in certain angular ranges of said sum or development formula.

It can be provided in such rotation angle ranges, in which D ( φ ) is calculated smaller than a predetermined minimum thickness Dmin according to the development formula, the thickness D to a value> Dmin down limit. Thus, the magnet thickness in these rotation angle ranges, ie in the case of an axially 2-pole magnetized magnet in areas around the angle φ = 90 ° and φ = 270 °, a deviation from the series development. This can be done in part by adjusting the parameters D0 . D1 . D3 . D5 etc. can be compensated within the above-specified parameter ranges according to the invention, without accepting a significant restriction with regard to the accuracy in the position or angle determination. The compensation is especially effective when the thickness D depending on the angle of rotation over a small part of the angular interval of 360 ° does not correspond to the specified series development, for example in the case of an axially 2-pole magnetized magnet in the range of 70 ° to 110 ° and 250 ° to 290 °, especially in the areas between 80 ° and 100 ° and 260 ° and 280 °. Axially higher pole magnetized magnets according to the invention can be designed accordingly in this regard.

The described inventive design of a multi-pole, in particular two-pole magnetized magnet can basically be realized with all magnetic materials. Particularly useful is the use of a plastic-bonded magnetic material such as a hard ferrite material, which is processable into a very homogeneous material body. The processing of the magnetic material can be carried out in particular by means of an injection molding or injection compression molding process for producing a magnet designed according to the invention.

Magnets designed according to the invention can be used in a large number of applications, in particular applications for detecting the rotation angle of parts such as shafts or for generating a purely sinusoidal field profile in electric motors for providing a uniform torque curve and thus for example for noise reduction or minimization of cogging torques, due to their described magnetic field properties.

For example, a device for eccentric angle detection comprise at least one mounted on a rotary shaft, axially multipolar, in particular two-pole magnetized magnet according to the present invention, the axial magnetic field is detected by several front end sensor elements, with their measurement signals, the rotational position of the rotary shaft can be determined, wherein the magnet as described for providing one over the angle of rotation φ variable magnetic field strength is formed. Conveniently, the magnet may be connected as a ring magnet with a carrier, for example made of plastic or metal, for example by spraying or gluing, which holds the magnet axially and possibly in partial areas on the circumference, wherein the carrier is fixed to the rotating shaft material or non-positively. In this case, the sensor elements may be stationary, for example, fixed to the housing and spaced from one end face of the magnet, so that the magnet rotates below or above the sensor elements.

The carrier and / or the rotary shaft can also comprise a ferromagnetic metal, in particular consist of, when adjusting the parameters D0 . D1 . D3 . D4 . D5 etc. within the parameter ranges according to the invention.

Such an angle detection device equipped with a magnet according to the invention can be used in many fields of engineering such as automotive engineering or automation technology. For example, such a device for detecting the rotation angle of crankshafts or camshafts can be used in an engine for motor vehicles. A further application may relate, for example, to the provision of sensor-controlled electrical commutation in electric motors, in particular in electric motors which are operated at high rotational speeds.

As a result of the described extremely short response behavior of such a device due to the special design of the magnet according to the invention also such electric motors can be commuted electrically, which are operated well over 5000 or even 10,000 revolutions, which was previously not possible using conventional encoder magnets. In this case, the magnet according to the invention as described can be used for fast and accurate detection of the rotational position of a rotor of the electric motor, the commutation can be done by means of fast electronic switch.

• 1 einen erfindungsgemäß gestalteten axial zweipolig magnetisierten Magneten in einer perspektivischen Ansicht,
• 2 eine Anordnung zur Verwendung des in 1 dargestellten erfindungsgemäßen Magneten zur Drehwinkelerfassung an einer Welle in einer Prinzipdarstellung,
• 3 den Verlauf des Magnetfeldes am Ort eines Sensors bei der Drehwinkelerfassung gemäß 2,
• 4 entsprechend 2 eine Anordnung zur Drehwinkelerfassung an einer Welle mittels eines erfindungsgemäß, in einer zweiten Ausführungsform ausgebildeten Magneten in einer Prinzipdarstellung,
• 5 eine Ausführungsform eines axial 4-polig magnetisierten erfindungsgemäßen Magneten in einer Aufsicht,
• 6 in einer Prinzipdarstellung eine herkömmliche Anordnung zur Drehwinkelerfassung einer Welle unter Verwendung eines gemäß dem Stand der Technik ausgebildeten axial zweipolig magnetisierten Magneten und
• 7 den Verlauf des Magnetfeldes am Ort eines Sensors bei einer Drehwinkelermessung an einer Welle nach 5

zeigt.The invention will be explained in the following by describing some embodiments with reference to the attached figures, wherein

• 1 an inventively designed axially two-pole magnetized magnet in a perspective view,
• 2 an arrangement for using the in 1 illustrated magnets according to the invention for detecting the rotation angle on a shaft in a schematic representation,
• 3 the course of the magnetic field at the location of a sensor in the rotation angle detection according to 2 .
• 4 corresponding 2 an arrangement for detecting the rotation angle on a shaft by means of a magnet according to the invention, formed in a second embodiment in a schematic representation,
• 5 an embodiment of an axially 4-pole magnetized magnet according to the invention in a plan view,
• 6 in a schematic representation of a conventional arrangement for detecting the rotation angle of a shaft using a trained according to the prior art axially two-pole magnetized magnet and
• 7 the course of the magnetic field at the location of a sensor at a rotational angle measurement on a shaft after 5

shows.

The in 1 illustrated magnet 10 is made of a plastic-bonded Hartferritwerkstoff and has a ring-like basic shape with a center hole 11 on. The design of the magnet according to the invention will be described below with reference to the indicated coordinate system.

The body of the magnet 10 has a center hole and extends between the inner radius r1 and the outer radius r2 , wherein the ratio in the example given is about 2: 1.

A front page 12 The magnet is flat and lies in the representation of 1 in the XY plane of the specified coordinate system. The front side 12 opposite end face of the magnet 10 represents a curved surface 13 and is dependent on the angle of rotation φ structured so the thickness D of the magnet 10 , ie the extension in the z-direction, with the rotation angle φ varied. This is the angle φ Measured in the xy plane and thus describes the angle of rotation about the z-axis, see the example given radius vector r in 1 , The thickness structuring of the magnet 10 is symmetrical in the described embodiment in the radial direction, that is, the magnet has - apart from the center hole - in any radial direction, ie for φ = constant, always the same thickness, regardless of the distance to the center.

The inventively designed magnet 10 is axially double-pole magnetized, ie the magnetization in the interior of the magnet is parallel to the z-axis, each of the two end faces in each case provides half a magnetic north pole and a magnetic south pole. These two poles on one end face are naturally offset by 180 degrees to the two poles of the other end face.

The thickness of the magnet as a function of the angle of rotation φ can be described by: $$D\left(\phi \right)=D_0+ABS\left[D_1*\text{cos}\left(\phi \right)+D_2*\text{cos}\left(3\phi \right)+D_3*\text{cos}\left(5\phi \right)+D4*\text{cos}\left(7\phi \right)\right],$$

In the example shown the 1 The parameters are r1 = 8mm, r2 = 15mm, D0 = 0.5mm, D1 = 6mm, D2 / D1 = -0.133, D3 / D1 = + 0.055, D4 / D1 = -0.0267, with the magnetic field passing through the two Sensors measured is at a radius r = 12 mm to the axis and a height of 1 mm above the highest elevation on the undulating structure on the front side facing the sensor 13 ,

In the illustrated orientation of the magnet, the dividing line between north and south poles on the radius vectors is φ = 0 ° and φ = 270 °. The dividing plane between the two poles of the two-pole magnet is formed by this dividing line and the axis z. There is the thickness D ₀ while the largest thickness D _max is set at φ = 0 ° and φ = 180 °.

In an embodiment, not shown, the thickness D of the magnet according to the invention also in the radial direction, ie with a radial distance to the center, vary. By way of example, such a magnet can in turn be of annular construction, the thickness being distributed over a radial section deltaR, the dependency D (according to the invention). φ ) and radially outside of this section is different, eg constant or another development according to the invention D ( φ ) with different D ₀ follows.

2 shows a schematic representation of the use of a magnet according to 1 , herewith D ₀ = 0, for detecting the rotational position of a shaft 30 , In the described embodiment, the magnet is 40 on a carrier 50 arranged, which may for example consist of a ferromagnetic or magnetic material depending on the embodiment. The carrier 50 is annular with two flat faces 52 . 53 , where on the latter the magnet 40 with its flat face 42 rests. Depending on the application, the use of the carrier may have the advantage that the handling of the magnet, in particular during assembly on the shaft, is simplified. Furthermore, in this design, the zeroth member D ₀ on 0 which may be advantageous in certain applications. The carrier 50 is with the magnet 40 firmly connected and, for example by gluing on the shaft 30 attached. carrier 50 and magnet 40 become so with the wave 30 moved.

Over the curved surface 43 of the magnet are circumferentially spaced by 90 ° two magnetic field sensitive sensors 20 . 21 attached to a stationary to the shaft component such as a housing. The sensors can detect the magnetic field, for example by means of the Hall effect or magnetoresistive. In the described embodiment, both sensors are at the same axial height to the shaft 30 placed and identically constructed and oriented, the magnet does not touch the two sensors during its movement.

3 shows the variation of the on a sensor 20 . 21 measured magnetic field during the rotation of the magnet 40 over a full circle, determined for a magnet made of plastic-bonded anisotropic hard ferrite and the measuring distance as well as the dimensions according to the parameter data for 1 , Recognizable corresponds to the course of the magnetic field component in the z-direction, ie in the axial direction, over the rotation angle in a very good approximation a sinusoidal course, which is the subsequent signal processing for determining the rotation angle of the shaft 30 much easier. Because the signals of both sensors 20 . 21 phase-shifted by 90 °, the angle of rotation results φ in a simple way by arctangent forming the ratio of the sine wave signal through the cosine wave signal.

4 shows a second embodiment of an arrangement for determining the rotational angle of a shaft using a magnet, as in relation to 1 has been described. In this embodiment, the magnet 10 even on the wave 30 attached, for example by an adhesive method. Here D ₀ ≠ 0, the magnet can be handled without a carrier. This magnet also generates on each of the sensors 20 . 21 but out of phase, a substantially sinusoidal signal having an extremely small amount of harmonics with the described advantages in accuracy in determining the angle of rotation and the temporal response of such a device.

The above-described further embodiment of a magnet designed according to the invention, in which the thickness is limited only over a radial section deltaR of a dependency D (FIG. φ ), but may be different in other radial regions, such as constant, or some other development D ( φ ), eg with different ones D ₀ ≠ 0 follows, in an application according to the 2 and 4 on the one hand as described used for detecting the rotation angle of a shaft. In addition, it can also be detected when the shaft moves from a predetermined position in the transverse direction to the axis.

The referring to the 2 and 4 rotation angle detectors described are particularly useful in the field of automotive technology, for example in the detection of internal combustion engine or drive components and the electric drive technology. For example, you can capture the rotation of a Crankshaft or camshaft used in a motor or for sensor-controlled electrical commutation in electric motors.

As stated above, the invention is not limited to an axially 2-pole magnetized embodiment of the magnet, but instead the magnet can also have more than two poles on one end face. 5 shows in a plan view an axially 4-pole magnetized ring magnet 100 with a center hole 110 and two South Pole and two North Pole sections ( S . N ) on the visible end face, wherein the Z axis and thus axis of rotation perpendicular to the plane of the drawing. Also the magnetization inside the magnet 100 in turn runs parallel to the axis of rotation, ie in the figure perpendicular to the plane of the drawing.

In the described embodiment, the magnet is 100 constructed in the radial direction, ie D ( φ ) does not depend on the distance to the center of the magnet, but solely on the angle ( φ ). The in the 5 visible front side opposite end face is like that of the magnet of the 1 just. With P = 4 and thus N = 2, the thickness structuring D ( φ ) in the z direction, taking into account summing elements up to the fifth harmonic $$D\left(\phi \right)=D_0+ABS\left[D_1*\text{cos}\left(2*\phi \right)+D_2*\text{cos}\left(2*3\phi \right)+D_3*\text{cos}\left(2*5\phi \right)\right],$$

How out 5 can be seen, the axially 4-pole magnetized magnet according to the invention 100 corresponding to P = 4 and N = 2 radially extending separating lines between different pole regions at φ (n = 0) = 45 °, φ (n = 1) = (45 + 90) ° = 135 °, φ (n = 2) = ( 45 + 180) ° = 225 ° and φ (n = 3) = (45 + 270) ° = 315 °. At these angles 45 °, 135 °, 225 ° and 315 °, the thickness of the magnet D (φ) = D ₀ . Correspondingly, at the angles 0 °, 90 °, 180 ° and 270 °, the thickness of the magnet D (φ) = D _max , where D _max indicates the largest thickness of the magnet, ie its largest extension in the z-direction. As the person skilled in the art realizes, the higher-pole magnets according to the invention can also advantageously be used on the basis of their purely sinusoidal magnetic field component in the z-direction for the applications described above with respect to axially two-pole magnetized magnets.

LIST OF REFERENCE NUMBERS

10

magnet

11

center hole

12

Plain front side

13

Curved surface

20, 21

magnetic field-sensitive sensor

30

wave

40

magnet

42

Plane end face

43

Curved surface

50

carrier

52, 53

Carrier faces

70

wave

80

ring magnet

82, 83

face

90, 91

Hall sensor

100

magnet

110

center hole

D

thickness

D ₀

Summation coefficient, minimum thickness

D ₁ , D ₂ , D ₃ D ₄ , D ₅

Summation coefficient

D _max

maximum thickness

φ

Rotation angle, rotation angle

N

North Pole

S

South Pole

r1

inner radius

r2, R _a

outer radius

Claims (14)

Axial multi-pole magnetized magnet (10, 40, 100) which has a thickness D (φ) varying over the angle of rotation (φ) at least in a radial region, the thickness D (φ) resulting from the addition of a constant D ₀ and the magnitude of a sum of cosine functions having a fundamental and its odd-numbered harmonics, comprising at least members up to the fifth harmonic according to $$D\left(\phi \right)=D_0+ABS\left[D_1*\text{cos}\left(2^{N-1}*\phi \right)+D_2*\text{cos}\left(2^{N-1}*3\phi \right)+D_3*\text{cos}\left({\text{2}}^{N-1}*5\phi \right)\right].$$

where N is a predetermined positive integer, D _{0 is} zero or a positive, the quotient D ₂ / D _{1 is} a negative, and the quotient D ₃ / D _{1 is} a positive value, ABS (D ₁ ) ≥ABS (D ₂ ) ≥ABS (D ₃ ) and where ABS [] or ABS () denotes the respective amount of the number enclosed by the bracket. Magnet (10, 40, 100) after Claim 1 , characterized in that the magnet is formed axially P-pole, wherein the pole number P is defined by P = 2 ^N , and in each case a dividing line between the north and south poles by a radius vector to φ (n) = ((180 / P) + n * (360 / P)) ° where n is over a set of natural numbers including zero {0; 1; 2; .... (P-1)}. Magnet (10, 40, 100) after Claim 1 or 2 , characterized in that an end face of the magnet is flat. Magnet (10, 40, 100) after Claim 1 . 2 or 3 , characterized in that the quotient D ₂ / D ₁ in the interval -0.2 to -0.05 and the quotient D ₃ / D ₁ in the interval 0.1 to 0.01. Magnet (10, 40, 100) according to one of the preceding claims, characterized in that the thickness D (φ) by taking into account further summing elements D ₄ and D ₅ according to the formula $$D\left(\phi \right)=D_0+ABS\left[\begin{array}{l}{D}_1*\text{cos}\left(2^{N-1}*\phi \right)+D_2*\text{cos}\left(2^{N-1}*3\phi \right)+D_3*\text{cos}\left(2^{N-1}*5\phi \right)\hfill \\ +D_4*\text{cos}\left(2^{N-1}*7\phi \right)+D_5*\text{cos}\left(2^{N-1}*9\phi \right)\hfill \end{array}\right]$$

where D _{3 is} negative and D _{5 is} zero or positive. Magnet (10, 40, 100) according to one of the preceding claims, characterized in that D ₄ / D ₁ in the range between -0.005 and -0.05 and D ₅ / D ₁ in the range of 0 to 0.02. Magnet (10, 40, 100) according to one of the preceding claims, characterized in that coefficients D ₁ , D ₂ , D ₃ , and optionally D ₄ and D ₅ are selected so that the course of the axial magnetic field of the magnet according to the invention over the Magnet over a circumferential circle with a constant radius has a harmonic distortion of less than 2%, in particular less than 1% with respect to an ideal sinusoidal course. Magnet (10, 40, 100) according to one of the preceding claims, characterized in that s is the quotient of outer radius R _a and thickness D (φ) at φ = 0 ° between 2 and 6. Magnet (10, 40, 100) according to one of the preceding claims, characterized in that the magnet is made as a one-piece continuous part, and the thickness D of the magnet in such Rotation angle ranges in which D (φ) calculated smaller than a predetermined minimum thickness Dmin of the magnet remains limited to a value ≥ Dmin down. Magnet (10, 40, 100) according to one of the preceding claims, characterized in that the magnet consists of a plastic-bonded magnetic material, preferably hard ferrite material. Device for angle detection with at least one mounted in a mounting position on a rotary shaft (30) axially multipolar magnetized magnet (10, 40), over the angle of rotation (φ) variable magnetic field in the axial direction or a related magnetic field gradient frontally by several magnetic field sensitive and in mounting position off-axis and stationary to the rotary shaft and mutually circumferentially spaced arranged sensor elements (20, 21) is detected, and a means for determining the rotational position of the rotary shaft on the basis of the measurement signals of the sensor elements (20, 21), characterized in that the magnet (10, 40, 100) according to one of Claims 1 to 10 is trained. Device after Claim 11 , characterized in that the magnet (40) is sprayed as a ring magnet on a support (50) which holds this axially and in some areas on the outer circumference, and with which it is fixed to the rotating shaft (30) material or non-positively. Use of a device according to one of Claims 11 or 12 for detecting the rotation angle of crankshafts or camshafts in the engine of motor vehicles. Use of a device according to one of Claims 11 or 12 for providing sensor-controlled electrical commutation in electric motors.

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