Inductive position sensor device and brake system having an inductive position sensor device

Abstract

The present invention relates to an inductive position sensor device (1) for detecting the position of a position transducer element (3) having a position receiving device (2), the position receiving device (2) comprising a multilayer printed circuit board (9) having a coil assembly (4), the coil assembly (4) comprising at least one excitation coil (5) and at least a first receiving coil (6) and a second receiving coil (7), the first receiving coil (6) and the second receiving coil (7) each comprising a number of windings (8, 10, 11, 12, 13, 14) at least partially surrounded by the excitation coil (5), the first receiving coil (6) comprising a compensation winding (8) arranged at least in an upper and / or lower portion of a portion (24) of the excitation coil (5).

Description

[Technical field]

[0001] The invention relates to an inductive position sensor arrangement according to the preamble of claim 1 and to a braking system comprising such an inductive position sensor arrangement according to the preamble of claim 9. [Background technology]

[0002] Inductive position sensors are widely used in the automotive field. Such position sensors are used, for example, to detect the linear or rotational angular position of a moving element. For example, a coil system is used as a position receiving device, which indicates the position of a moving position encoder element via mutual coupling (electric field and voltage). At least one excitation coil and at least two receiving coils are used. Such coils are known to be printed / applied on a printed circuit board, as is known, for example, from the literature, US2020400465A1.

[0003] A position encoder element is typically a moving component made from an electrically conductive, usually non-ferromagnetic material. It may be, for example, a cylinder piston of a master brake cylinder of a brake actuator, or an impeller of a drive shaft of an electric motor.

[0004] Such sensors work according to the inductive principle: in this case, the fact that both conductive and ferromagnetic materials affect the properties of the electromagnetic coil is utilized. A change in the coupling between the excitation coil and at least two receiving coils caused by a metallic element leads to a change in voltage, which is registered and evaluated by the evaluation unit.

[0005] For angle sensors, currently, a 360° wrap-around coil assembly is usually used. In the case of a C-shaped coil structure, the surface area can be significantly reduced with a “Pos1 / 2<>Neg1 / 2 and Pos1 / 4<>Neg1 / 2<>Pos1 / 4” receiver coil structure. The C-shaped coil structure (or C-shaped printed circuit board) offers a much more cost-effective alternative to the 360° variant. However, the maximum compression of the available surface area required by the “Pos1 / 2<>Neg1 / 2 and Pos1 / 4<>Neg1 / 2<>Pos1 / 4” receiver coil structure leads to an imbalance in the generated signals. One of the two signals from the two receiver coils is asymmetrically loaded to such an extent that a large offset occurs. Therefore, the signal average value of the asymmetrically loaded receiver coil is no longer optimally adapted to the signal evaluation electronics system, for example an analog-to-digital converter. The offset voltages of the first and second output signals are therefore different, which does not allow both signals to be amplified to optimally utilize the available voltage range. As a result, the robustness of the signal is reduced.

[0006] The present invention therefore aims to reduce the offset voltage of the cosine signal of the motor position sensor in order to allow maximum amplitude gain of both received signals (sine and cosine), thus making the sensor more robust to mechanical tolerances in the installed sensor's printed circuit board and in the sensor object (e.g. impeller), resulting in less waste in production and robustness with respect to safety-critical conditions in the event of position drift.

[0007] An object of the present invention is to provide an inductive position sensor device that generates a small offset between signals output from at least two receiving coils. Summary of the Invention [Means for solving the problem]

[0008] The present invention provides an inductive position sensor device for detecting the positional location of a position encoder element having a position receiving device, the position receiving device comprising a printed circuit board of multi-layer design and comprising a coil assembly, the coil assembly comprising at least one excitation coil and at least a first receiving coil and a second receiving coil, the first receiving coil and the second receiving coil each comprising a plurality of windings at least partially surrounded by the excitation coil, the first receiving coil comprising a compensation winding arranged in a specific area above and / or below at least a subsection of the excitation coil.

[0009] By inserting a compensation winding in the receive coil affected by the offset, an additional magnetic field (or voltage) is induced in the receive coil from the excitation coil, thus shifting the voltage offset in the desired direction of the second receive coil signal.

[0010] Depending on the position of the compensation winding relative to the excitation coil on the printed circuit board, the coupling of the excitation field is influenced by the position of the position encoder element on the compensation winding. This leads to perturbations to the compensation field depending on the position of the position encoder element. The proposed compensation winding also overcomes these adversities by the fact that the compensation winding is explicitly positioned in the area of ​​the sensor object above it.

[0011] Nevertheless, to achieve offset compensation that is independent of the position encoder element, the length of the compensation winding (or angle opening in the case of an angle sensor) is selected such that the total surface area of ​​the position encoder element and the clearance of the position encoder element (e.g. non-blades in an angle sensor) always exceeds the compensation winding, and thus the position effect of the position encoder is offset.

[0012] This has the advantage of providing a high degree of robustness against mechanical position changes. In addition, the absence of constraints makes the circuit design on the printed circuit board independent. As a result, the space requirements on the printed circuit board are significantly reduced, leading to cost savings.

[0013] The compensation winding assembly according to the invention also has the advantage that the position sensor device delivers good measurement results without regular calibration.

[0014] The multi-layered printed circuit board preferably comprises a first layer, a second layer and at least one intermediate layer arranged between the first and second layers, the excitation coil comprises a number of windings applied to the first and second layers, and a compensation winding of a first receiving coil is applied to the first intermediate layer, the compensation winding being arranged in a specific area in the vertical region between the winding of the excitation coil of the first layer and the winding of the excitation coil of the second layer.

[0015] In addition, the compensation winding is integrated between the excitation coil in the printed circuit board layer, so that only the part of the excitation field required for compensation is coupled to the compensation winding, and therefore the additional surface area required for the compensation winding relative to the overall printed circuit board is also virtually nonexistent.

[0016] According to a preferred embodiment, the first receiving coil is applied by its winding to the first and second intermediate layers. According to another preferred embodiment, the second receiving coil is applied by its winding to the first and second intermediate layers, the second intermediate layer being arranged between the first and second layers.

[0017] The windings of the first and second receive coils preferably each comprise a plurality of positive and negative windings, which are diametrically surrounded by the windings of the excitation coil.

[0018] The first receive coil is preferably a cosine receive coil, and the second receive coil is preferably a sine receive coil.

[0019] Furthermore, the excitation coil, the first receiving coil and the second receiving coil each comprise a connection to an evaluation unit.

[0020] The inductive position sensor device according to the invention is used in the braking system of a motor vehicle, where it is used to determine the movement of a brake cylinder piston or to determine the rotor position of a drive shaft with an impeller of an electric motor, where the brake cylinder piston or the impeller represents the position encoder element of the position sensor device.

[0021] Further preferred embodiments of the invention become apparent from the following description of exemplary embodiments based on the following drawings, in which: [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 illustrates a first exemplary inductive position sensor device. [Diagram 2] FIG. 2 illustrates a detailed view of a first exemplary inductive position sensor device. [Diagram 3] FIG. 2 illustrates a second exemplary inductive position sensor device. [Figure 4] FIG. 2 illustrates a coil assembly of the first exemplary inductive position sensor apparatus from FIG. [Diagram 5] FIG. 3 illustrates a coil assembly of the second exemplary inductive position sensor apparatus from FIG. 2. [Figure 6] FIG. 1 illustrates an exemplary location receiving device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] FIG. 1 shows a first exemplary inductive position sensor device 1, comprising a position receiving device 2 and a position encoder element 3. The position receiving device 2 comprises a printed circuit board (not shown) with a coil assembly 4 including at least three coils. In the example shown, the position encoder element 3 is in the form of an impeller 26. The impeller 26 is designed to be fixed on a drive shaft (not shown) of an electric motor via its fastening ring 27. The position receiving device 2 and the position encoder element 3 are arranged on top of or next to each other with a small spatial interval. The impeller 26 is made of a metallic material. The impeller 26 is made of a non-ferromagnetic material. The impeller 26 is electrically conductive.

[0024] FIG. 2 shows this position sensor device 1 in more detail. The impeller 26 is shown slightly transparent in order to illustrate the coil assembly 4 underneath. The exact design of the coil assembly 4 is explained in more detail in FIGS. 4 to 6. The coil assembly 4 comprises at least one excitation coil 5 and at least one first receiving coil 6. The first receiving coil 6 comprises a number of windings, including a compensation winding 8. The impeller 26 comprises at least one blade 22 and at least one blade recess 23. The impeller 26 may be provided with a number of blades and blade recesses, alternating in the direction of rotation. The impeller 26 is made, for example, of an aluminum material and rotates by its blades 22 when the drive shaft of an electric motor is driven by its coil assembly 4 via a printed circuit board, not shown. The blades 22 slip repeatedly over the coil assembly 4 and in the process affect the induced voltages in the first receiving coil 6 and in the second receiving coil. The rotational position of the drive shaft of the electric motor is determined by changing the coupling of the excitation magnetic field from the excitation coil 5 to the first and second receiving coils resulting from slipping of the blade 22 and the trailing blade recess 23.

[0025] The compensation winding 8 of the first receive coil 6 is arranged in a specific area above or below at least a subsection of the excitation coil 5. The compensation winding 8 in this case follows the curved shape of the excitation coil 5 subsection.

[0026] Furthermore, the compensation winding 8 is arranged such that the fastening ring 28 of the impeller 26 is not located above it. The compensation winding 8 is arranged such that the blades 22 and the blade recesses 23 move over it.

[0027] In an embodiment, the position receiving device 2 is C-shaped according to figures 1 and 2. This means that the printed circuit board, not shown, and the coil assembly 4 are also C-shaped. Such a C-shape requires less installation space but imposes higher demands on good signal quality.

[0028] FIG. 3 shows a second exemplary inductive position sensor device 1, comprising a position receiving device 2 and a position encoder element 3. The position receiving device 2 likewise comprises a printed circuit board (not shown) with a coil assembly 4 including at least three coils. In the example shown, the position encoder element 3 is a cylinder piston 27. The cylinder piston 27 belongs, for example, to a master brake cylinder of a brake actuator. When the brake actuator is actuated, the cylinder piston 27 moves parallel to the position receiving device 2. As a result, the position or the movement distance of the cylinder piston 27 can be detected by the position receiving device 2. This movement distance represents, for example, a braking request of the driver. The position receiving device 2 is, for example, mounted in or on a cylinder housing of the brake actuator, in which the cylinder piston 27 moves linearly.

[0029] The coil assembly 4 also comprises an excitation coil 5 and a first receiving coil 6 with a compensation winding 8. The compensation winding 8 of the first receiving coil 6 is arranged in a specific area above or below at least a subsection of the excitation coil 5. The compensation winding 8 in this case follows the linear shape of the subsection of the excitation coil 5. In the shown example, the position receiving device 2 is rectangular.

[0030] FIG. 4 shows the coil assembly 4 of the position receiving device 2 in the first exemplary inductive position sensor device 1 from FIG. 1 in more detail.

[0031] The coil assembly 4 comprises an excitation coil 5 with a connection 15, a first receiving coil 6 with a connection 16 and a second receiving coil 7 with a connection 17. The first receiving coil 6 comprises a number of windings. At the connection 16, a first positive winding 10 is provided, which transitions to a negative winding 11, which in turn transitions to a second positive winding 12. A compensation winding 8 branches off from the second positive winding 12. The compensation winding 8 extends over a subsection 24 of the excitation coil 5. In this case, the compensation winding 8 is located above or below the subsection 24 of the excitation coil 5. The receiving coil 6 is a so-called cosine receiving coil.

[0032] The second receive coil 7 comprises a positive winding 13 which transitions to a negative winding 14 at a connection 17 .

[0033] The windings 10, 11, and 12 of the first receiving coil 6 and the windings 13 and 14 of the second receiving coil 6 are diametrically surrounded by the excitation coil 5. Thus, the excitation magnetic field of the excitation coil 5 induces voltages in the windings 10-14 of the first receiving coil 6 and the second receiving coil 7.

[0034] In this case, the compensation winding 8 of the first receiving coil 6 is exposed to the excitation magnetic field of the excitation coil 5 in such a way that the part of the excitation magnetic field passing up to the compensation winding 8 induces a defined additional voltage in the compensation winding 8. This voltage corresponds to the part necessary to compensate for the shifted offset.

[0035] 5 shows a similar structure of the coil assembly 4, showing the coil assembly 4 of the second exemplary inductive position sensor device 1 from FIG. 3. In this case, the coil assembly 4 is rectangular. The first receiving coil 6 and the second receiving coil 7 comprise the same number and type of windings 8, 10-14 as described in the above embodiment.

[0036] Again, the compensation winding 8 extends from the first receiving coil 6 across a subsection of the excitation coil 5 .

[0037] 6 shows in cross section a position receiving device 2 having a multi-layer printed circuit board 9. The printed circuit board 9 comprises a first (upper) layer 18 and a second (lower) layer 19. In between are provided a first intermediate layer 20 and a second intermediate layer 25. The first intermediate layer 20 faces the second layer 19. The second intermediate layer 25 faces the first layer 18.

[0038] By way of example, the excitation coil 5 comprises several windings 29. These windings 29 are applied simultaneously to the first layer 18 and the second layer 19. At several connection points, the excitation coil passes from the first layer 18 to the second layer 19 and back again. By passing an alternating current through the excitation coil 5, an excitation magnetic field 21 is generated. The excitation magnetic field 21 acts on the windings of the first receiving coil 6 and the second receiving coil 7. The excitation magnetic field 21 acts in particular on the compensation winding 8 from the first receiving coil 6.

[0039] The positive and negative windings of the first and second receiving coils 6 and 7 are located on the sides of the winding 29 of the excitation coil 5. The positive and negative windings are surrounded by the excitation coil 5 and are located slightly away from those windings 29. As a result, a weak excitation magnetic field 21 is applied to the positive and negative windings. The positive and negative windings of the first and second receiving coils 6 and 7 are located on the intermediate layers 20 and 25 of the printed circuit board 9. The positive and negative windings of each receiving coil 6 and 7 can pass from the first intermediate layer 20 to the second intermediate layer 25 at the corresponding connection points and back again. As a result, the positive and negative windings of the receiving coils 6, 7 extend vertically through the printed circuit board 9. The positive and negative windings of the receiving coils 6, 7 run horizontally as shown in Figures 3 to 5.

[0040] By way of example, the compensation winding 8 of the first excitation coil 5 is applied to the first intermediate layer 20. By way of example, a sub-area of ​​the compensation winding 8 is located in the vertical area between the excitation coils 5, which are applied to the first layer 18 and to the second layer 19 of the printed circuit board 9. This means that the compensation winding 8 is in a strong effective range of the excitation magnetic field 21.

[0041] As a result, the excitation magnetic field 21 induces voltages not only in the positive and negative windings of the first receiving coil 6 but also in the compensation winding 8. Thus, the signal offset of the first receiving coil 6 changes such that the signal from the first receiving coil 6 approximates the signal from the second receiving coil 7. [Explanation of symbols]

[0042] 1 Position sensor device 2. Position receiving device 3 Position Encoder Elements 4 Coil Assembly 5 Excitation coil 6 First receiving coil 7 Second receiving coil 8 Compensation Winding 9 Printed Circuit Board 10 First positive winding of first receiving coil 11 Negative winding of first receiving coil 12 Second positive winding of the first receiving coil 13 Positive winding of second receiving coil 14 Negative winding of second receiving coil 15 Excitation coil connection 16 Connection of first receiving coil 17 Connection for second receiving coil 18 First Layer 19 Second Layer 20 The first middle class 21 Excitation magnetic field 22 Blade 23 Blade recess 24 Subsections 25 The second middle class 26 Impeller 27 Cylinder piston 28 Fastening ring 29 Windings

Claims

1. An inductive position sensor device (1) for detecting the positional location of a position encoder element (3) having a position receiving device (2), said position receiving device (2) comprising a printed circuit board (9) of multi-layer design and comprising a coil assembly (4) comprising at least one excitation coil (5) and at least a first receiving coil (6) and a second receiving coil (7), said first receiving coil (6) and second receiving coil (7) each comprising a number of windings (8, 10, 11, 12, 13, 14) at least partially surrounded by said excitation coil (5), 1. An inductive position sensor device (1), characterized in that the first receiving coil (6) comprises a compensation winding (8) arranged in a specific region above and / or below at least a subsection (24) of the excitation coil (5).

2. 2. The inductive position sensor device (1) according to claim 1, characterized in that the multi-layered design of the printed circuit board (9) comprises a first layer (18), a second layer (19) and at least one intermediate layer (20) arranged between the first layer (18) and the second layer (19), the excitation coil (5) comprises a plurality of windings (29) applied to the first layer (18) and to the second layer (19), the compensation winding (8) of the first receiving coil (6) is applied to the first intermediate layer (20), the compensation winding (8) being arranged in a specific area in the vertical area between the winding (29) of the excitation coil (5) of the first layer (18) and the winding (29) of the excitation coil (5) of the second layer (19).

3. 3. An inductive position sensor device (1) according to claim 1 or 2, characterized in that the first receiving coil (6) is applied by its windings (8, 10, 11, 12) to the first intermediate layer (20) and to the second intermediate layer (25).

4. The inductive position sensor device (1) according to any one of claims 1 to 3, characterized in that the second receiving coil (6) is applied by its windings (13, 14) to the first intermediate layer (20) and to the second intermediate layer (25), the second intermediate layer (25) being arranged between the first layer (18) and the second layer (19).

5. 5. The inductive position sensor device (1) according to claim 2, characterized in that the windings (8, 10, 11, 12, 13, 14) of the first receiving coil (6) and the second receiving coil (7) each comprise a plurality of positive and negative windings (10, 11, 12; 13, 14), which are diametrically surrounded by the winding (29) of the excitation coil (5).

6. Inductive position sensor arrangement (1) according to any one of claims 1 to 5, characterised in that the first receiving coil (6) is a cosine receiving coil.

7. Inductive position sensor arrangement (1) according to any one of claims 1 to 6, characterised in that the second receiving coil (7) is a sine receiving coil.

8. The inductive position sensor arrangement (1) according to any one of claims 1 to 7, characterized in that the excitation coil (5), the first receiving coil (6) and the second receiving coil (7) each comprise a connection (15; 16; 17) to an evaluation unit.

9. A brake system for a motor vehicle, comprising a brake actuator having a movable brake cylinder piston (27) and / or an electric motor having a drive shaft and an impeller (26), wherein the position encoder element (3) of the position sensor device (1) according to any one of claims 1 to 8 is represented by the brake cylinder piston (27) or the impeller (26).

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