Contactless inductive multi-channel rotational angle sensor

Abstract

The invention relates to a contactless inductive multi-channel rotational angle sensor having two channels, a stator (S) and a rotor (R), the stator (S) having: a printed circuit board (2) having at least a first layer (21), a second layer (22) and a third layer (23); each channel is provided with a transmitting coil; each channel is provided with at least three receiving coils; and at least one electronic circuit per channel for generating a transmit signal to be emitted by the transmit coil and / or for analyzing a receive signal to be received by the receive coil.

Description

Technical Field

[0001] The present invention relates to a contactless inductive multi-channel rotation angle sensor, wherein the multi-channel rotation angle sensor has a pair of channels, a stator and a rotor.

[0002] Wherein, the stator has:

[0003] - a circuit board, the circuit board having at least a first layer, a second layer and a third layer,

[0004] - One transmitting coil per channel,

[0005] - at least two receive coils per channel, and

[0006] - at least one electronic circuit per channel for generating a transmission signal to be emitted by the transmission coil and / or for evaluating a reception signal to be received by the reception coil,

[0007] in,

[0008] - the first layer has a conductive structure, in particular a copper structure, the second layer is a layer made of an insulator and the third layer has a conductive structure, in particular a copper structure,

[0009] - the receiving coils of the individual channels are designed as conductive structures in a first layer and a third layer of the printed circuit board, the first layer and the third layer being separated from one another by a second layer made of an insulator,

[0010] - the electronic circuit is arranged on a circuit board, and

[0011] Therein, the rotor has a closed conductor loop. Background Art

[0012] Such a contactless inductive rotation angle sensor with two channels is known from the document EP 0 900 997 B1. The sensor technology disclosed in the document is used in particular in motor vehicles and in accelerator pedals and in steering angle and rotation angle sensors, which are used, for example, in motor controllers. The document DE 10 2004 027 954 B4 discloses this contactless inductive rotation angle sensor as a further development of a sensor for measuring a torsion angle, with which a torque can be detected.

[0013] Due to the continuously increasing safety requirements for automotive electronics, the requirements for sensors in terms of error recognition and error avoidance or reaction have also increased. Thus, in an x-by-wire system, for example, it is no longer reliable that the sensor is shut down due to a simple error (e.g., a voltage supply failure). For this reason, two identical sensors are used redundantly, which are supplied by different onboard power grids or batteries and connected to different controllers. In order to further ensure high signal integrity (up to ASIL D for erroneous signals according to ISO26262), synchronous monitoring between the at least two sensors is also required. For synchronous monitoring, it is necessary that each of the two sensors is connected to two controllers, and the two controllers perform synchronous monitoring redundantly. Because the paths of the signals on different controllers lead to excessively high signal timeliness (Signalalter), it is in accordance with the purpose that each controller also uses at least two sensors to operate, which increases the number of sensors to at least four. The problem to be solved now requires that these four sensors be functionally, cost-effectively and with high performance integrated into one system.

[0014] In addition to the contactless inductive rotation angle sensor of the type described at the beginning, Hall sensors are known in which two sensor channels (each a chip) are constructed / combined in one ASIC. These sensor channels are mostly stacked side by side or stacked one above the other with a small distance. When using more than the two channels, a new ASIC must be developed or an ASIC must be placed on the circuit board and an ASIC must be placed under the circuit board, but this leads to an excessively high difference in the air gap between the magnet and the Hall-sensitive surface and therefore brings problems in signal processing (signal strength and sensor errors). In addition, the two ASICs or their Hall-sensitive surfaces are not placed close enough to the rotation axis on the side of the circuit board at the same time, so that the increased sensor errors (Sensorfehler) must also be considered, which make the sensor unusable for accuracy requirements. Therefore, Hall sensors seem to be unsuitable for the research and development of functional, cost-effective and high-performance integrated systems. Summary of the invention

[0015] The inventors therefore set themselves the task of developing a multi-channel rotational angle sensor based on the contactless, inductive rotational angle sensor described in the introduction.

[0016] According to the invention, this object is achieved in that the multi-channel rotational angle sensor has at least two further channels, wherein the stator has

[0017] - one transmitting coil for each additional channel,

[0018] - at least two receiving coils per additional channel,

[0019] - at least one further electronic circuit per further channel for generating a transmission signal to be emitted by the further transmission coil and / or for evaluating a reception signal to be received by the further reception coil,

[0020] in,

[0021] - the printed circuit board has at least a further first layer, a further second layer and a further third layer for the two further channels,

[0022] - the further first layer has a conductive structure, in particular a copper structure, the further second layer is a layer made of an insulator and the further third layer has a conductive structure, in particular a copper structure,

[0023] the receiving coil of the further channel is designed as a conducting structure in the further first layer and the further third layer of the printed circuit board, the further first layer and the further third layer being separated from one another by the further second layer made of an insulator,

[0024] - The further electronic circuit is arranged on a printed circuit board.

[0025] With this pair of additional channels, it is possible to integrate a total of four sensors or channels in a system functionally, cost-effectively and with high performance. The multi-channel rotation angle sensor according to the present invention can also have more than one pair of additional channels, for example two to five pairs of additional channels, so that the multi-channel rotation angle sensor according to the present invention can have up to twelve channels, for example. The layers of the circuit board that are provided for different pairs of additional channels can be laid flat on top of each other, wherein two adjacent layers of different pairs with conductive structures are separated from each other by layers made of insulators. Here, the different pairs of additional first layers are adjacent and separated from each other by layers made of insulators. But it is also possible that the different pairs of additional first layers and additional third layers are adjacent and separated from each other by layers made of insulators.

[0026] The transmitting coil of the channel can

[0027] is formed as a conductive structure in the first or third layer, or

[0028] is formed as a conductive structure in a fifth layer of the circuit board, the fifth layer being separated from the third layer by a fourth layer made of an insulator, or

[0029] - is formed as a conductive structure in a fifth and a seventh layer of the printed circuit board, wherein the fifth layer is separated from the third layer by a fourth layer of the printed circuit board made of an insulator, and the seventh layer is separated from the fifth layer by a sixth layer of the printed circuit board made of an insulator.

[0030] Accordingly, the transmitting coil of the other channel may

[0031] is formed as a conductive structure in the further first layer or the further third layer, or

[0032] as a conductive structure in a fifth layer of the printed circuit board, said fifth layer being separated from the further third layer by a further fourth layer made of an insulator, or

[0033] The conductive structure is formed in a fifth and a seventh layer of the printed circuit board, wherein the seventh layer is separated from the further third layer by a further fourth layer of the printed circuit board made of an insulator.

[0034] The conducting structures for the transmitting coil of the channel can therefore be formed together with the conducting structures for the transmitting coil of the further channel on the fifth layer or on the fifth layer and the seventh layer. However, the transmitting coils can also be arranged in different layers.

[0035] The conductive structures of the first and third layers can be connected to one another via microvias in the second layer, and the conductive structures of the further first and third layers can be connected to one another via microvias in the further second layer. The microvias can be redundant, in particular double, in order to improve failsafety.

[0036] Furthermore, the electronic circuit can be connected to the conductive structure of the third, fifth or seventh layer, which forms the transmitting coil, via microvias, and the further electronic circuit can be connected to the conductive structure of the further third, fifth or seventh layer, which forms the further transmitting coil, via microvias. These microvias can also be implemented redundantly, in particular in duplicate, in order to improve the failsafety.

[0037] The use of microvias (which can also be buried microvias) is particularly advantageous for the separation of transmitting and receiving coils, since otherwise a high number of through-hole metallizations would greatly complicate the routing of lines on the corresponding layer or other layers with the conductive structure and would make the symmetry of the circuit board difficult. Moreover, the use of microvias (µVias) limits the number of possible short circuits between different receiving and transmitting coils, especially in n-channel sensors (n>2), since short circuits can occur at a small number of locations on the circuit board and the channels or sensors can be spatially separated from one another and therefore there is no possibility for some short circuits.

[0038] The circuit board of the multi-channel rotation angle sensor according to the present invention can have a thickness of 1 mm or more. A thickness of 1 mm ensures sufficient strength of the circuit board. Otherwise, there is an increased risk of damage due to mechanical influences (such as assembly forces).

[0039] Preferably, the layers of the circuit board are arranged symmetrically with respect to a plane between the front side and the back side of the circuit board. This makes it possible to avoid bending under the influence of temperature. In order to achieve symmetry or the best possible symmetry, the thickness of the second layer and the further second layer is the same, more preferably 300 to 400 μm. For the same reason, the thickness of the fourth layer and the further fourth layer is the same, more preferably 300 to 400 μm.

[0040] In the multi-channel rotational angle sensor according to the invention, the transmitting coils and receiving coils of different channels have different distances from the rotor. Since the field strength decreases with the distance from the rotor, there is the problem that the receiving coils close to the rotor receive signals with higher signal strengths than the receiving coils far from the rotor. Since typical sensors are switched off both when the signal strength is too low and when the signal strength is too high, it may be sensible to adapt the diameter of the receiving coils so that the signal strengths of the received signals are within the same range, since otherwise the individual channels respond differently to external influences, which has a negative effect on the overall performance of the multi-channel rotational angle sensor.

[0041] However, the variation between the signal strengths of the signals received by the different channels is much smaller due to the much lower distances than in solutions in which, for example, the Hall sensors are placed on both sides of the circuit board. The distance between the Hall sensors can be approximately 2 to 3 mm in the described case, whereas this is <1 mm in the inductive solution shown. Moreover, the solution based on Hall sensors is limited to 4-channel sensors in the current configuration. The solution according to the invention is essentially limited by the minimum thickness of the layers made of the insulator, which is determined by manufacturing, so that a multi-channel rotation angle sensor according to the invention with six to twelve channels can also be created based on this.

[0042] According to the present invention, the electronic circuit for the receiving coil close to the rotor can be placed on the side facing the rotor, and the electronic circuit for the receiving coil far from the rotor can be placed on the side of the circuit board facing away from the rotor. This can reduce short circuits between the electronic circuits as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The structure of the multi-channel rotation angle sensor according to the invention having four channels is described with reference to the accompanying drawings. In the drawings:

[0044] Figure 1 A side view of a multi-channel sensor is schematically shown. DETAILED DESCRIPTION

[0045] The schematic drawing shows a rotor R and a stator S. The rotor R comprises a closed conductor loop. The stator comprises a circuit board 2 and electronic circuits 1, 1' arranged on the front and rear sides, said electronic circuits comprising resistors, diodes, capacitors and / or ICs, such as FPGAs, ASICs or other ICs.

[0046] The circuit board 2 is a multi-layer circuit board, which includes a layer made of an insulator and a layer having a conductive structure, preferably a copper structure. In detail, the circuit board is from the front side to the back side. It is a first layer 21 with a copper structure, a second layer 22 made of an insulator, a third layer 23 with a copper structure, a fourth layer 24 made of an insulator, a fifth layer 25 with a copper structure, a sixth layer 26 made of an insulator, a seventh layer 27 with a copper structure, another fourth layer 24' made of an insulator, another third layer 23' with a copper structure, another second layer 22' made of an insulator, and another first layer 21' with a copper structure.

[0047] The copper structures of the first layer 21 and the third layer 23 or the further first layer 21 ′ and the further third layer 23 ′ are connected to one another via microvias and form receiving coils, to be more precise three for each of the four channels. In this case, six receiving coils for two of the channels are formed in the first layer 21 and the third layer 23, and six receiving coils for two of the channels are formed in the further first layer 21 ′ and the further third layer 23 ′.

[0048] The electronic circuit is electrically connected to the receiving coil, more precisely, the electronic circuit 1 on the front side is electrically connected to the receiving coil in the first layer 21 and the third layer 23, and the other electronic circuit on the back side of the circuit board 2 is electrically connected to the receiving coil in the other first layer 21' and the other third layer 23'.

[0049] A copper structure is provided in the fifth layer 25, which forms a transmitting coil for one of the two channels together with a receiving coil in the first layer 21 and the third layer 23. A copper structure is provided in the seventh layer 27, which forms a transmitting coil for the other of the two channels together with a receiving coil in the first layer 21 and the third layer 23. The two receiving coils are connected to the electronic circuit 1 on the front side of the circuit board 2 via microvias.

[0050] Furthermore, a copper structure is provided in the fifth layer 25, which forms a transmitting coil for one of the two channels together with a receiving coil in the further first layer 21' and the further third layer 23'. A copper structure is provided in the seventh layer 27, which forms a transmitting coil for the other of the two channels together with a receiving coil in the further first layer 21' and the further third layer 23'. The two receiving coils are connected to the further electronic circuit 1' on the front side of the printed circuit board 2 via microvias.

[0051] An electromagnetic field is generated by the transmitting coil, in which the rotor is moved. As a result, a current is induced in the closed conductor loop, which is changed, in particular weakened, by the field generated by the transmitting coil. This change changes the current through the receiving coil, which is detected by the electronic circuit 1, 1'. In a known manner, the position of the rotor relative to the stator can thus be detected with each of the four channels of the multi-channel sensor. The electronic circuits are independent of each other and are connected to interfaces with each control unit, which are supplied with electrical energy from different batteries of the motor vehicle.

[0052] Reference numerals list

[0053] S-Stator

[0054] R-Rotor

[0055] 1 Electronic Circuit

[0056] 1'Other electronic circuits

[0057] 2 Circuit Board

[0058] 21 First layer (with copper structure)

[0059] 22 Second layer (insulator)

[0060] 23Third layer (with copper structure)

[0061] 24 Fourth layer (insulator)

[0062] 25 Fifth layer (with copper structure)

[0063] 26 Sixth layer (insulator)

[0064] 27 Seventh layer (with copper structure)

[0065] 21' additional first layer (with copper structure)

[0066] 22' additional second layer (insulation)

[0067] 23' Additional third floor (with copper structure)

[0068] 24' Additional 4th layer (insulation)

Claims

1. Non-contact inductive multi-channel rotation angle sensor - has two channels, - has a stator (S) and has a rotor (R), in, The stator (S) has - a circuit board (2), the circuit board having at least a first layer (21), a second layer (22) and a third layer (23), - One transmitting coil per channel and - at least two receiving coils per channel, - at least one electronic circuit per channel for generating a transmission signal to be emitted by the transmission coil and / or for evaluating a reception signal to be received by the reception coil, in, The first layer (21) has a conductive structure, in particular a copper structure, the second layer (22) is a layer made of an insulator, and the third layer (23) has a conductive structure, in particular a copper structure, The receiving coils of the channel are designed as conductive structures, in particular copper structures, in a first layer (21) and a third layer (23) of the printed circuit board (2), the first layer and the third layer being separated from each other by a second layer (22) made of an insulator. The electronic circuit (1) is arranged on a circuit board (2), and The rotor (R) has a closed conductor loop, It is characterized in that The multi-channel rotation angle sensor has at least two further channels, wherein the stator (S) has: - one transmitting coil for each additional channel, - at least two receiving coils per additional channel, - at least one further electronic circuit (1') per further channel for generating a transmission signal to be emitted by the further transmission coil and / or for evaluating a reception signal to be received by the further reception coil, in, The circuit board (2) has at least a further first layer (21'), a further second layer (22') and a further third layer (23') for the two further channels, The further first layer (21') has a conductive structure, in particular a copper structure, the further second layer (22') is a layer made of an insulator and the further third layer (23') has a conductive structure, in particular a copper structure, The receiving coil of the further channel is designed as a conductive structure in the further first layer (21') and the further third layer (23') of the printed circuit board (2), the further first layer and the further third layer being separated from each other by the further second layer (22') made of an insulator, The further electronic circuit (1') is arranged on a printed circuit board (2).

2. The multi-channel rotation angle sensor according to claim 1, characterized in that: The transmitting coil of the channel is formed as a conductive structure, in particular a copper structure, in the first layer (21) or the third layer (23), or A conductive structure, in particular a copper structure, is formed in a fifth layer (25) of a printed circuit board (2), said fifth layer being separated from the third layer (23) by a fourth layer (24) made of an insulator, or Conductive structures, in particular copper structures, are formed in a fifth layer (25) and a seventh layer (27) of a printed circuit board (2), wherein the fifth layer (25) is separated from the third layer (23) by a fourth layer (24) of the printed circuit board (2) made of an insulator, and the seventh layer (27) is separated from the fifth layer (25) by a sixth layer (26) of the printed circuit board (2) made of an insulator.

3. The multi-channel rotation angle sensor according to claim 1 or 2, characterized in that: The transmitting coil of the other channel is formed as a conductive structure, in particular a copper structure, in the further first layer (21') or the further third layer (23'), or A conductive structure, in particular a copper structure, is formed in a fifth layer (25) of the printed circuit board, the fifth layer being separated from the further third layer (23') by a further fourth layer (24') made of an insulator, or Conductive structures, in particular copper structures, are formed in a fifth layer (25) and a seventh layer (27) of a printed circuit board, wherein the seventh layer (27) is separated from the further third layer (23') by a further fourth layer (24') made of an insulator.

4. The multi-channel rotation angle sensor according to any one of claims 1 to 3, characterized in that: The conductive structures of the first layer (21) and the third layer (23) are interconnected via micropores in the second layer (22), and the conductive structures of the further first layer (21') and the further third layer (23') are interconnected via micropores in the further second layer (22').

5. The multi-channel rotation angle sensor according to any one of claims 1 to 3, characterized in that: The electronic circuit (1) is connected to the conductive structure forming the transmitting coil of the third layer (23), the fifth layer (25) or the seventh layer (27) via a microvia, and the further electronic circuit (1') is connected to the further conductive structure forming the transmitting coil of the further third layer (3), the fifth layer (5) or the seventh layer (7) via a microvia.

6. The multi-channel rotation angle sensor according to claim 4 or 5, characterized in that: The micropores or some of the micropores are designed to be double.

7. The multi-channel rotation angle sensor according to any one of claims 1 to 6, characterized in that: The circuit board has a thickness of 1 mm and more.

8. The multi-channel rotation angle sensor according to any one of claims 1 to 7, characterized in that: The layers (21, 22, 23, 24, 25, 26, 27, 24', 23', 22', 21') of the printed circuit board (2) are arranged symmetrically with respect to a plane between a front side and a rear side of the printed circuit board (2).

9. The multi-channel rotation angle sensor according to any one of claims 1 to 8, characterized in that: The thickness of the second layer (22) and the further second layer (22') is the same, more preferably 300 to 400 μm.

10. The multi-channel rotation angle sensor according to any one of claims 1 to 8, characterized in that: The thickness of the fourth layer ( 24 ) and the further fourth layer ( 24 ′) is the same, more preferably 300 to 400 μm.

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