Inductive position sensor

Abstract

The invention relates to an inductive position sensor, comprising a first stator element having a first excitation coil to which a periodic alternating voltage is applied and having a first receiving system into which the signal of the first excitation coil is inductively coupled, comprising a first rotor element which influences the strength of the inductive coupling between the first excitation coil and the first receiving system as a function of its angular position relative to the first stator element, comprising a metal element which is arranged on a shaft in a torsionally fixed manner with the first rotor element, comprising an evaluation circuit for determining the angular position of the first rotor element relative to the first stator element from the voltage signal induced in the first receiving system, characterized in that the first rotor element and the metal element are each configured as a conductor loop having a periodic geometry, and the periodicity of the first rotor element and the metal element is in a predetermined integer ratio.

Description

Technical Field

[0001] This invention relates to an inductive position sensor, particularly an inductive position sensor for motor vehicles, the inductive position sensor comprising a first stator element having a first excitation coil to which a periodic alternating voltage is applied and a first receiving system, wherein a signal from the first excitation coil is inductively coupled into the first receiving system; the inductive position sensor further comprising a first rotor element, the first rotor element influencing the strength of the inductive coupling between the first excitation coil and the first receiving system according to its angular position relative to the first stator element; the inductive position sensor further comprising a metal element that can influence the inductive coupling between the first excitation coil and the first receiving system, wherein the metal element is torsionally connected to the first rotor element on a common shaft; and the inductive position sensor comprising an evaluation circuit for determining the angular position of the first rotor element relative to the first stator element from a voltage signal induced in the first receiving system. Background Technology

[0002] Inductive position sensors are used in modern motor vehicles in a variety of applications with numerous boundary conditions. In particular, inductive position sensors are used where the angular position of the rotor must be detected for precise control. This may be necessary, for example, in the steering column, braking system, or drive unit of motor vehicles, especially electric and hybrid vehicles.

[0003] When designing an inductive position sensor and integrating it into an existing vehicle system, the surrounding environment of the sensor must be considered, because metal components, in particular, located near the inductive position sensor, may affect the inductive coupling between the first excitation coil and the first receiving system, which may affect the voltage signal induced in the receiving system.

[0004] However, in order to use inductive position sensors in such environments, appropriate measures need to be taken to minimize the influence of metal components.

[0005] Existing technology provides known inductive position sensors that incorporate shielding to reduce interference from metallic components. A significant drawback of this approach is its high cost, as the shielding of the sensor against the metallic components increases the sensor's overall cost. This shielding must be designed individually for each application, typically achieved through empirical research. Such shielding can be formed, for example, from a metal layer, metal grid, or metal mesh within a circuit board. It is commonly implemented as an additional layer on a multilayer circuit board on which the first stator element is arranged. The possibilities for these measures are limited. While such shielding can reduce interference, it is impossible to completely eliminate it. Summary of the Invention

[0006] This invention is based on this premise.

[0007] The problem upon which this invention is based is to improve known position sensors, particularly those for motor vehicles, so as to minimize the influence of metal components while simultaneously enabling cost-effective manufacturing of the sensors.

[0008] According to the present invention, the above objective is achieved in the following manner: the first rotor element and the metal element are respectively constructed as conductor circuits with periodic geometric structures, and the period of the first rotor element and the period of the metal element are in a predetermined integer ratio.

[0009] Here, the influence of the metal element on the voltage signal induced in the first receiving system can be minimized by the geometry of the first rotor element and the metal element and the period ratio.

[0010] In the inductive position sensor according to the invention, the influence of the metal element on the induced voltage signal can be canceled out by implementing the first rotor element and the metal element as a conductor loop and by passing through a predetermined integer period. This eliminates the need for a shield.

[0011] The following feasible solution exists: the first stator element is arranged on a circuit board, wherein the circuit board is mounted in the intermediate space between the first rotor element and the metal element and is spaced apart from the first rotor element and the metal element, and the circuit board is permeable to electric fields and / or magnetic fields and / or electromagnetic waves because no shielding is provided in the circuit board.

[0012] Additional layers can be eliminated by omitting the shielding within the circuit board. Since each additional layer incurs cost, it is desirable to implement the circuit board as compactly as possible.

[0013] It can be specified that the geometry of the conductor circuit of the first rotor element and the metal element can be described by two circular trajectories with different radii around the midpoint of a common axis, wherein the first radius of the first circular trajectory is smaller than the second radius of the second circular trajectory, and a corresponding segment of the conductor circuit extends alternately and periodically on the first or second circular trajectory, and the end of each segment is connected to a segment on the corresponding other circular trajectory via a radial connection between the circular trajectories.

[0014] The resulting geometry of the first rotor element and the metal element corresponds to the outer contour of the rotor having multiple wings and gaps. Therefore, it can be stipulated that corresponding segments of the conductor loop on a circular trajectory with a second radius form wings, and corresponding segments of the conductor loop on a circular trajectory with a first radius form gaps, wherein a wing and a gap respectively determine the period of the first rotor element and the metal element.

[0015] In order to minimize the influence of the metal element on the first receiving system, it is advantageous to have a period ratio of 1:2 or 2:1 between the first rotor element and the metal element.

[0016] This means that the period of the first rotor element is half or twice the period of the metal element. Here, the combination of geometry and period minimizes the impact.

[0017] A feasible solution exists as follows: the first receiving system has at least two, preferably three, first conductor loops. Furthermore, it can be specified that each of the first conductor loops forms a periodically repeating loop structure. Particularly advantageously, it can be specified that the winding direction of the first conductor loop of the periodically repeating loop structure changes, wherein a surface is opened by the change in winding direction. By changing the winding direction, the integral path of the surface periodically opened by the first conductor loop changes. The magnetic field coupled into the first receiving system by the first rotor element induces a signal voltage amplitude on the conductor loop, which is related to the expression... Proportional (B) r : The magnetic field strength in the first conductor loop caused by the rotor element; A: The surface opened by the first conductor loop). By changing the winding direction, the orientation of the surface normal dA changes, which makes the sign of the calculated integral alternate between positive and negative.

[0018] It can be stipulated here that the period of the loop structure corresponding to the first conductor loop is consistent with the period of the geometry of the first rotor element. In this case, the sign of the coupled magnetic field changes with the sign of the first conductor loop at the same period. If the signals coupled in the periodically opening surface are the same, the signal components cancel each other out.

[0019] The following feasible solutions exist: the first rotor element and / or metal element is implemented as a stamped part and / or a laser-laid part. In particular, the manufacturing process for stamped parts allows for mass production, which optimizes costs. Implementing it as a laser-laid part offers high flexibility in production and can accommodate special specifications.

[0020] It can be specified that the metal element is implemented as a second rotor element. With this configuration of the inductive position sensor, for example, two rotational angles can be measured on a shaft to determine the torque of the shaft (e.g., the steering column of a motor vehicle).

[0021] Advantageously, the second stator element can be configured to have a second excitation coil and a second receiving system, the second receiving system comprising at least two, preferably three, second conductor loops, wherein a signal from the second excitation coil is coupled into the second receiving system, and wherein the strength of the signal is determined by the second rotor element. In this case, a value for the second rotor element can be determined and associated with the first rotor element.

[0022] Alternatively, the second stator element can be specified to have a second receiving system, which has at least two, preferably three, second conductor loops, wherein the signal from the first excitation coil is coupled into the second receiving system, and the strength of the signal is affected by the second rotor element. In this case, the first excitation coil generates a signal not only for the first receiving system but also for the second receiving system. Alternatively, the second excitation coil can be omitted in this scenario.

[0023] One feasible solution is to arrange the second stator element on a circuit board. This allows for a space-saving configuration of the inductive position sensor. Attached Figure Description

[0024] The invention will now be described in more detail with reference to the accompanying drawings. In the drawings:

[0025] Figure 1 A schematic side view of an inductive position sensor according to a preferred embodiment of the present invention is shown;

[0026] Figure 2 A schematic diagram of rotor elements and / or metal elements is shown;

[0027] Figure 3 The first periodic ratio shows a schematic diagram of the structure of the rotor element, the metal element, and the first receiving system, along with the relevant orientation of the magnetic field and the surface normal dA;

[0028] Figure 4 The second periodic diagram shows the structure of the rotor elements, metal elements, and the first receiving system, along with the orientation of the magnetic field and the surface normal dA. Detailed Implementation

[0029] An inductive position sensor 1 constructed according to a preferred embodiment of the present invention includes a circuit board 103 on which a first stator element is arranged.

[0030] The inductive position sensor 1 also includes a first rotor element 200 and a metal element 201, wherein a circuit board 103 is disposed between and spaced apart from the first rotor element 200 and the metal element 201. The rotor element 200 and the metal element 201 are coaxially mounted on a common shaft 300. The first rotor element 200 and the metal element 201 are arranged to be rotatable relative to each other and rotatable relative to the circuit board 103.

[0031] The circuit board 103 has a first stator element on its side facing the first rotor element 200. The first stator element includes a first excitation coil 101 and a first receiving system 100. The first receiving system 100 includes two, preferably three, first conductor loops. The first conductor loops form a periodically repeating loop structure, and the first conductor loops open a face by changing the winding direction.

[0032] The inductive position sensor 1 has an oscillator circuit (not explicitly shown here) that generates a periodic alternating voltage signal during operation of the inductive position sensor 1 and couples it into a first excitation coil 101. The first rotor element 200, during its rotation, affects the strength of the inductive coupling between the first excitation coil 101 and the first receiving system 100.

[0033] The angle between the first rotor element 200 and the first receiving system 100 can be determined by how the angular position of the first rotor element 200 relative to the first stator element affects the strength of the inductive coupling between the first excitation coil 101 and the first receiving system 100. This angle is becoming increasingly important for many applications, particularly in motor vehicles. The inductive position sensor 1 has an evaluation circuit (not explicitly shown) for determining the angular position of the first rotor element 200 relative to the stator element from the signal coupled into the first receiving system 100.

[0034] The metal element 201 disposed on the other side of the circuit board 103 can affect the inductive coupling between the first excitation coil 101 and the first receiving system 100. This effect is undesirable because it is superimposed on the effect of the first rotor element 200 and makes it difficult to accurately determine the angular position between the first rotor element 200 and the first receiving system 100.

[0035] To minimize the influence of the metal element 201, the inductive position sensor 1 has a first rotor element 200 and a metal element 201, which are respectively configured as conductor loops with periodic geometries, and the periods of the first rotor element 200 and the metal element 201 are in a predetermined integer ratio to each other. It has been shown to be particularly advantageous that the ratio of the periods is 1:2 or 2:1.

[0036] Furthermore, the period of the first rotor element 200 is consistent with the period of the loop structure of a corresponding conductor loop of the first receiving system 100.

[0037] Figure 2 A schematic configuration of a first rotor element 200 and / or a metal element 201 is shown, wherein the metal element 201 substantially corresponds to the geometry of the first rotor element 200 and the two may have different periods.

[0038] like Figure 2 As can be seen, the conductor loop mimics the outer contour of the first rotor element 200 or the metal element 201. The sections of the conductor loop on the outer diameter of the element are visible. These sections can be presented as wings. The sections of the conductor loop on the inner diameter can be presented as gaps. Here, a corresponding wing and a gap define a period.

[0039] Due to the integer ratio of the periods between the first rotor element 200 and the metal element 201, and the geometry of these two elements, the influence of the metal element 201 on the voltage signal induced in the first receiving system 100 can be minimized. This influence can be almost completely eliminated. To further illustrate, Figure 3 A schematic diagram showing the structure of the first rotor element 200, the metal element 201, and the first receiving system 100 for two cycles, along with the associated orientation of the magnetic field and the surface normal dA.

[0040] Basically, with the desired cycle ratio of 1:2 or 2:1, there are two application scenarios. Figure 3 and Figure 4 The two applications with different cycles can be seen in the diagram. Figure 3 and Figure 4 Possible structures 400, 402 for the first rotor element 200 and / or metal element 201, and two different possible structures 401, 403 for the first receiving system 100 are shown. Here, the arrows drawn in structures 400, 401, 402, 403 correspond to integration paths, or assumed current directions. The view is taken along the rotation angle φ.

[0041] Here, feasible first receiving systems 401 and 403 consist of the periodic repetition of two face halves 401.1 and 401.2 or 403.1 and 403.2, wherein the corresponding halves have different face normals dA due to changes in the winding direction. The effect of the metal element 201 on the first receiving system 100 should now be addressed in Figure 3 and Figure 4 The structures 400, 401, 402, 403 of the rotor element 200 and metal element 201 shown are observed in combination with the first receiving system 100.

[0042] Figure 3 This illustrates an application scenario where the cycle ratio of the first rotor element 200 to the metal element 201 is 1:2. Figure 3 In this diagram, the first receiving system 100 corresponds to structure 401, and the first rotor element 200 corresponds to rotor structure 400. The metal element 201 is shown in structure 402. It can be seen that the period of the metal element 402 is less than the period of the first receiving system 100.

[0043] Figure 4 This illustrates an application scenario where the cycle ratio of the first rotor element 200 to the metal element 201 is 2:1. Figure 4 In this configuration, the metal element 201 is implemented using structure 400, the first rotor element 200 is implemented using rotor structure 402, and the first receiving system 100 is implemented using structure 403. It can be seen that in this second case, the period of the metal element 201 is greater than the period of the first receiving system 100.

[0044] In both cases, the periods of the metal element 201 and the first rotor element 200 are integer ratios of each other. In both cases considered, the first rotor element and the first receiving system 100 have the same period. Therefore, the period of the metal element 201 is... Figure 3 The middle is half the cycle of the first receiving system 100, while... Figure 4 The cycle of the middle receiver is twice that of the first receiving system.

[0045] Depend on Figure 3 It can be seen that the period of the metal element 201 with structure 402 corresponds to half of the structure width 401.1. Therefore, in the corresponding halves 401.1 and 401.2, the effect of the metal element 201 is numerically the same for any angular relationship between the metal element 201 and the first receiving system 100. However, due to the different orientations of the surface normal dA, which has opposite signs, the two quantities exactly cancel each other out. It can also be seen that not only the geometrical changes in the first receiving system 401 (e.g., caused by the additional distance between the forward and reverse windings) but also the geometrical changes in the rotor structure 402 (e.g., caused by the change in the wing width) are substantially balanced.

[0046] Depend on Figure 4It can be seen that the period of the metal element 201 with structure 400 corresponds to twice the structure width 403.1. Here, the influence of the metal element 201 is numerically the same in the two halves 403.1 and 403.2. Due to the different orientations of the surface normal dA, these two quantities have opposite signs. However, it can be seen that even a small deviation (e.g., a larger width of the wing 500 in the rotor structure 400) will cause these two quantities to change numerically and no longer be the same. Therefore, the metal element 201 with structure 400 will affect the first receiving system 100 with structure 403. Since the first receiving system 100 is essentially implemented on a circuit board 103 with multiple layers, this influence must be taken into account. By adjusting the periodicity in the metal element 400, the minimum value of the influence can be determined. Here, the minimum value can be found essentially by means of simulation or measurement. Therefore, by appropriately selecting the period, the direct coupling between the metal element 201 and the first receiving system 100 can be substantially compensated.

[0047] However, additional coupling may occur between the first rotor element 200 and the metal element 201 in both cases, and such additional coupling must also be taken into account.

[0048] If requirements are specified for the geometry of the first rotor element 200 and the metal element 201, and if such requirements are used... Figure 2 The geometry shown can minimize the influence between the first rotor element 200 and the metal element 201.

[0049] As the current changes over time, induction occurs from the first rotor element 200 to the metal element 201 and from the metal element to the first rotor element. Here, the magnetic field of the first rotor element 200 changes due to the metal element 201, which affects the voltage signal induced in the first receiving system 100. This effect depends primarily on the geometry and period of the first rotor element 200 and the metal element 201.

[0050] In use Figure 2 When considering the geometry shown, the following situation can be observed: For Figure 3 In the application scenario shown, where the period of metal element 201 is twice the period of the first rotor element 200, metal element 102 exerts an effect on the first rotor element 100 and thus on the first receiving system 100, independent of the rotation angle. For Figure 4 In the application shown, the magnetic field change of the first rotor element 200 caused by the metal element 201 acts uniformly on the two receiving structure halves 403.1 and 403.2. Correspondingly, the effect of the metal element 201 is not observed. Therefore, by using... Figure 2The geometric structure shown can eliminate the influence of the metal element 201 on the voltage signal induced in the first receiving system 100.

[0051] List of reference numerals

[0052] 1. Inductive position sensor

[0053] 100 First Receiving System

[0054] 101 First excitation coil

[0055] 103 Circuit Board

[0056] 200 First rotor element

[0057] 201 Metal Components

[0058] 300 common axis

[0059] 400, 402 Views of the structure of the first rotor element and / or metal element

[0060] 401, 403 Views of the structure of the first receiving system

[0061] 401.1, 401.2, 403.1, 403.2 Receiving structure halves

[0062] 500 Wings of the first rotor element and / or metal element

[0063] 501 Gap between the first rotor element and / or metal element

[0064] dA plane normal

[0065] Magnetic fields B11, B12, B21, and B22

Claims

1. An inductive position sensor (1), - The inductive position sensor includes a first stator element having a first excitation coil (101) to which a periodic alternating voltage is applied and a first receiving system (100), wherein the signal from the first excitation coil (101) is inductively coupled into the first receiving system (100). - The inductive position sensor includes a first rotor element (200), which affects the strength of the inductive coupling between the first excitation coil (101) and the first receiving system (100) according to its angular position relative to the first stator element. - The inductive position sensor includes a metal element (201), which and the first rotor element (200) are arranged torsionally on a shaft (300). - The inductive position sensor includes an evaluation circuit for determining the angular position of the first rotor element (200) relative to the first stator element from a voltage signal induced in the first receiving system. Its features are, The first rotor element (200) and the metal element (201) are respectively constructed as conductor loops with periodic geometric structures, and the periods of the first rotor element (200) and the metal element (201) are in a predetermined integer ratio to reduce the influence of the metal element on the induced voltage signal. The first stator element is arranged on a circuit board (103), which is mounted in the intermediate space between the first rotor element and the metal element and spaced apart from them. The circuit board (103) is permeable to electric and / or magnetic fields and / or electromagnetic waves. The first receiving system has at least two first conductor loops, and the at least two first conductor loops respectively form a periodically repeating loop structure. The winding direction of the first conductor loop of the periodically repeating loop structure changes, thereby opening a surface. The first receiving system is composed of the periodic repetition of two surface halves, and the corresponding surface halves have different surface normals due to the change in winding direction, so as to reduce the influence of metal elements on the induced voltage signal.

2. The inductive position sensor (1) according to claim 1, characterized in that, The geometry of the conductor circuits of the first rotor element (200) and the metal element (201) can be described by two corresponding circular trajectories with different radii around the midpoint located on the axis, wherein the first radius of the first circular trajectory is smaller than the second radius of the second circular trajectory, and a corresponding segment of the conductor circuit extends alternately and periodically on the first or second circular trajectory, and the ends of each segment are connected to adjacent segments on the other circular trajectory via radial connections between the circular trajectories.

3. The inductive position sensor (1) according to claim 2, characterized in that, The conductor circuit forms a wing (500) on a corresponding segment of a circular trajectory with a second radius, and a gap (501) is formed on a corresponding segment of a circular trajectory with a first radius, wherein a wing (500) and a gap (501) respectively determine the period of the first rotor element (200) and the metal element (201).

4. The inductive position sensor (1) according to any one of claims 1 to 3, characterized in that, The period ratio of the first rotor element (200) to the metal element (201) is 1:2 or 2:

1.

5. The inductive position sensor (1) according to any one of claims 1 to 3, characterized in that, The inductive position sensor is an inductive position sensor used in motor vehicles.

6. The inductive position sensor (1) according to any one of claims 1 to 3, characterized in that, The first receiving system has three first conductor loops.

7. The inductive position sensor (1) according to any one of claims 1 to 3, characterized in that, The period of the loop structure of the corresponding first conductor loop is consistent with the period of the geometry of the first rotor element (200).

8. The inductive position sensor (1) according to any one of claims 1 to 3, characterized in that, The first rotor element (200) and / or the metal element (201) are implemented as stamped parts and / or laser parts.

9. The inductive position sensor (1) according to any one of claims 1 to 3, characterized in that, The metal element (201) is the second rotor element.

10. The inductive position sensor (1) according to claim 9, characterized in that, The second stator element has a second excitation coil and a second receiving system. The second receiving system has at least two second conductor loops. The signal from the second excitation coil is coupled into the second receiving system, and the strength of the signal from the second excitation coil is affected by the second rotor element.

11. The inductive position sensor (1) according to claim 10, characterized in that, The second receiving system has three second conductor loops.

12. The inductive position sensor (1) according to claim 9, characterized in that, The second stator element has a second receiving system having at least two second conductor loops, the signal from the first excitation coil is coupled into the second receiving system, and the strength of the signal from the first excitation coil is affected by the second rotor element.

13. The inductive position sensor (1) according to claim 12, characterized in that, The second receiving system has three second conductor loops.

14. The inductive position sensor (1) according to any one of claims 10 to 13, characterized in that, The second stator element is arranged on the circuit board (103).

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