Electromagnetic shielding arrangement and thermal management module for a vehicle with an electromagnetic shielding arrangement

Abstract

The present invention relates to an electromagnetic shielding arrangement (01) for an inductive position sensor, wherein the shielding arrangement (01) comprises a circuit board (02) having multiple conductor levels and connection contacts, a sensor arranged on the circuit board (02), a low-pass filter (06), and an electromagnetic shielding means (07). At least three input lines are connected to the circuit board (02). The sensor comprises a sensor circuit (03), a transmitting coil (04), a capacitor, a target (26) for influencing the transmitted signal, and at least two receiving coils (05). The transmitting coil (04) and the capacitor are arranged on the circuit board (02) and serve to generate a magnetic transmitted signal.The receiving coils (05) are arranged on the circuit board (02) and serve to receive the transmitted signal, wherein the first of the two receiving coils has a sine winding and the second of the two receiving coils has a cosine winding, so that the position of a target (26) can be determined from the received signals by means of a control unit. The low-pass filter (06) is connected to the receiving coils (05) in order to filter out interference signals. At least three input lines, on which several attenuation beads are arranged, are connected to the connection contacts of the circuit board (02). The electromagnetic shielding means (07) comprises a plurality of conductor tracks running on the circuit board, at least one of which is designed as a short-circuit loop (13). The conductor tracks of the electromagnetic shielding means (07) are arranged on the circuit board (02) in such a way that they partially cover the receiving coils (05).Furthermore, the present invention relates to a thermal management module for a vehicle (16) with an electromagnetic shielding arrangement (01) with a sensor.

Description

[0001] The present invention relates to an electromagnetic shielding arrangement for an inductive position sensor. Furthermore, the invention relates to a thermal management module for a vehicle with an electromagnetic shielding arrangement with a sensor.

[0002] It is known that thermal management modules are used to control cooling circuits in vehicles. The control system must be designed specifically for the vehicle and its operation, depending on environmental influences, application situation, etc. Generally, the coolant supply is controlled by at least one valve, with the valve position values ​​specified by the respective manufacturer and transmitted to the thermal management module via a bus system. At least one electric motor or valve drive is used to adjust the valve. A sensor device is used to detect the respective valve position, which transmits the values ​​for the respective valve position to a higher-level control unit via the bus system.

[0003] It is also known that automotive applications are subject to strict requirements regarding electromagnetic compatibility (EMC), particularly immunity. Care must be taken to ensure that a particular device is not disturbed by unwanted electrical or electromagnetic effects or by other devices. Shielding, of which various types are known, is often used for this purpose.

[0004] A shield for a position sensor is known from DE 11 2019 003 906 T5. This document describes a position detection device, in particular an inductive position sensor, which detects a relative position between a first and a second element. A transmitting antenna with at least one transmitting winding is arranged on the first element. The transmitting antenna is part of the position sensor. Furthermore, a receiving antenna of the position sensor can be arranged on the first element. The inductive position sensor further comprises a coupling element, which can be arranged on the second element, and a processing circuit configured to provide signals. The signals indicate the position of the first element relative to the second element and are based on a current induced in one or more windings of the receiving antenna.The inductive position sensor comprises at least one electromagnetic shield comprising a plurality of conductor tracks. The conductor tracks are arranged such that no closed current loops are formed in the shield. The electrostatic shield serves to reduce interference. Furthermore, the shield is grounded. The shield comprises a first linear conductor track and a plurality of second conductor tracks and / or third conductor tracks extending away from the first conductor track. The second and third conductor tracks extend in different directions. The first conductor track of the shield can surround the conductor tracks of the receiving winding (sine winding and cosine winding); the second conductor tracks can extend between a sine winding and a cosine winding. A plurality of third conductor tracks can, in turn, extend from the second conductor track in any direction.

[0005] An object of the present invention, based on the prior art, is to provide an arrangement or a thermal management module for a vehicle which has improved interference immunity and at the same time can be produced cost-effectively.

[0006] The stated object is achieved by an electromagnetic shielding arrangement according to the appended claim 1 and by a thermal management module for a vehicle with an electromagnetic shielding arrangement with a sensor according to the appended independent claim 10.

[0007] The electromagnetic shielding arrangement according to the invention is provided for an inductive position sensor or angle sensor in order to improve its immunity to interference. The electromagnetic shielding arrangement according to the invention comprises a circuit board with multiple conductor levels and connection contacts. At least three input lines are connected to the connection contacts of the circuit board. Furthermore, the electromagnetic shielding arrangement comprises a sensor arranged on the circuit board, which has at least one transmitting coil, a capacitor, a target, and at least two receiving coils. The transmitting coil and the capacitor together form an oscillating circuit with a magnetic field, so that a magnetic transmission signal is generated, which can be influenced by the target. The target is preferably a rotatable target. In a preferred embodiment, the oscillating circuit has two capacitors.A first receiving coil has a sine winding, and a second receiving coil has a cosine winding. The at least two receiving coils are configured to receive the transmitted signal and generate received signals. Using the received signals, a control unit can determine a position, in particular an angular position. To improve the electromagnetic compatibility, also known as immunity to interference, of the sensor, the electromagnetic shielding arrangement according to the invention comprises several shielding measures, which, when combined, lead to improved shielding and thus increased operational reliability.

[0008] First, the shielding arrangement comprises a low-pass filter connected to the receiving coils. AC signals are known to couple into coil structures. Using the selected low-pass filter, the useful signal, i.e., the received signal, can be advantageously separated from the interference signal, i.e., filtered out. As a further shielding measure, the electromagnetic shielding arrangement comprises several attenuation beads arranged on the input lines of the circuit board. The attenuation beads (ferrite beads) have the advantage of attenuating conducted interference components, thus ensuring conducted interference immunity. As a further shielding measure, the electromagnetic shielding arrangement comprises an electromagnetic shielding means. The electromagnetic shielding means comprises a plurality of conductor tracks running along the circuit board.At least one of the conductor tracks of the electromagnetic shielding means is designed as a short-circuit loop, i.e., the at least one conductor track is arranged such that a current loop is formed in the shielding means. The electromagnetic shielding means is arranged on the circuit board such that it at least partially covers the receiving coils. This means that the conductor tracks of the electromagnetic shielding means partially cover the receiving coils or the conductor tracks forming the receiving coils.

[0009] Preferably, the electromagnetic shielding means is arranged on the circuit board such that it is located within the interior of the transmitting coil. This arrangement of the electromagnetic shielding means relative to the transmitting coil and the receiving coil has the advantage that the circuit board only needs to be constructed with four layers. If the shielding structure were to be constructed to completely cover the receiving coils, two additional layers would be added to the four-layer circuit board. Thus, the circuit board has only four conductor track levels. This also has the advantage that the shielding arrangement is cost-effective and designed with the best possible EMC requirements.

[0010] The circuit board is preferably a printed circuit board (PCB).

[0011] The electromagnetic shielding means has a disc shape. Preferably, the electromagnetic shielding means is simultaneously radially formed within the disc shape, so that it can also be referred to as a shielding flower. The shape of the electromagnetic shielding means is fundamentally known from DE 11 2019 003 906 T5, but the electromagnetic shielding means used in the shielding arrangement according to the invention explicitly has the short-circuit loop, so that it does not correspond mechanically and electrically to the previously known shielding means in this detail. The short-circuit loop can also be referred to as a short-circuit winding. The electromagnetic shielding means advantageously serves to reduce interference, e.g., in the form of electromagnetic interference radiation. Furthermore, the electromagnetic shielding means is grounded.The electromagnetic shielding means preferably comprises a first linear or curved conductor track and a plurality of second conductor tracks and / or third conductor tracks extending from the first conductor track. A hole is advantageously provided in the circuit board in the center of the short-circuit loop, which serves to mechanically connect the circuit board to the housing.

[0012] In order to cover a broad frequency range in which the interference signals can occur, the low-pass filter is preferably an RCRC low-pass filter, which has an attenuation effect over a wide frequency range. The RCRC low-pass filter comprises two RC low-pass filters. The values ​​R and C are selected such that two different cutoff frequencies are created, above which the low-pass filter has an attenuation effect. The RCRC low-pass filter has the advantage that it covers a wider frequency range than a single RC low-pass filter. A single RC low-pass filter can also have a limited filtering effect due to parasitic effects of the components R and C, which can be eliminated by an RCRC low-pass filter. The lowest cutoff frequency should preferably be at least a factor of 10 higher than the useful signal so that the useful signal is not attenuated by the low-pass filter.For example, for interference up to the GHz range, a lower cutoff frequency of 160 MHz can be selected for the first RC low-pass filter, and the second RC low-pass filter can consequently have a cutoff frequency 10 times higher. The low-pass filter, specifically the RCRC low-pass filter, is arranged on the circuit board at a distance from the sensor.

[0013] In one embodiment, the sensor includes a FIR filter, which can advantageously filter out residual RF interference from the measurement signal. The FIR filter can be activated by setting a register in an EEPROM to which the sensor is connected (setting bit 1 or 0). To filter out the interference from the measurement signal, an average is calculated from several measured values, thus generating a low-pass characteristic.

[0014] The board's input lines can be selected as SENT, VCC, and Ground. Ferrite beads are preferred for the input lines. The ferrites should be selected according to the shielding configuration. The desired frequency of the SENT signal should not be attenuated, so attenuation should only be applied at higher frequencies. Ferrites are known to attenuate both common-mode and differential-mode noise components.

[0015] The electromagnetic shielding arrangement preferably comprises a bus system for data transmission, wherein the bus system preferably uses a SENT bus. As a further shielding measure, a filter for the bus system can be used, whereby the filter is selected according to the bus system. For example, a CRC filter is used for the SENT bus.

[0016] The aforementioned active, controllable components, which are arranged on the circuit board, can be controlled by a control unit.

[0017] The thermal management module for a vehicle according to the invention comprises an electromagnetic shielding arrangement, which corresponds to the previously described shielding arrangement with possible embodiments. The thermal management module further comprises a valve for controlling a cooling fluid in the vehicle and at least one motor that is controlled by the controller and can adjust the valve.

[0018] Further advantages, details, and modifications of the invention will become apparent from the following description of a preferred embodiment, with reference to the drawings. They show: Fig. 1: a schematic block diagram of an electromagnetic shielding arrangement according to the invention; Fig. 2: a plan view of a partial view of a circuit board with an electromagnetic shielding means; and Fig. 3: a schematic sketch of the electromagnetic shielding arrangement in its installation environment in a vehicle.

[0019] Fig. 1 shows a schematic sketch of an electromagnetic shielding arrangement 01 according to the invention for an inductive position sensor. The electromagnetic shielding arrangement 01 comprises a circuit board 02 in the form of a PCB, which has several conductor track levels. The circuit board 02 has connection contacts to which input lines are connected, which are protected against line-borne interference components by attenuation beads (not shown). Parts of a sensor are arranged on the circuit board 02, including an APS sensor circuit 03. The sensor also comprises a transmitting coil 04, e.g. a TX transmitting coil, a capacitor (not shown) and at least two receiving coils 05. Furthermore, a target 26 (see Fig. 3) can be expected to influence the transmitted signal. The transmitting coil 04 and the capacitor interact in the resonant circuit, so that the transmitting coil emits a magnetic transmission signal that can be influenced by the target. The receiving coils 05 serve to receive the transmitted signal. The first of the two receiving coils 05 has a sine winding, and the second of the two receiving coils 05 has a cosine winding.

[0020] By evaluating the sensor signal, a control unit can determine a position, in particular a valve position. According to the invention, the electromagnetic shielding arrangement 01 comprises several shielding measures, a first of which is a low-pass filter 06, which is arranged on the circuit board 02 and connected to the receiving coils. The low-pass filter serves to filter out interference signals and is an RCRC low-pass filter. As a further shielding measure, the electromagnetic shielding arrangement comprises the previously described damping beads (ferrite beads), which are arranged on the input lines.

[0021] A further shielding measure is formed by an electromagnetic shielding means 07, which is a component of the electromagnetic shielding arrangement 01 and is arranged on the circuit board 02 such that it preferably only partially covers the receiving coils 05. Further details of the electromagnetic shielding means 07 are described in relation to Fig. 2 described.

[0022] The electromagnetic shielding arrangement 01 further comprises an FIR filter 08, which is arranged on the sensor and serves to filter RF interference signals from the measurement signal. Furthermore, the electromagnetic shielding arrangement comprises a bus filter 09, which removes interference signals from a bus system used for data transmission. For example, the bus filter in a SENT bus can be a CRC filter. Furthermore, the electromagnetic shielding arrangement comprises an interface 11, which is electrically connected to the sensor. The interface 11 comprises a communication interface 11a and a power interface 11b.

[0023] Fig. 2 shows a top view of a partial section of the circuit board 02 with the electromagnetic shielding means 07, which partially covers the receiving coils 05. The electromagnetic shielding means 07 is disc-shaped in plan view and comprises numerous radially extending conductor tracks 12 on the circuit board. At least one conductor track is designed as a short-circuit loop 13, which is located in the center of the electromagnetic shielding means 07 and from which the radially extending conductor tracks 12 originate. The electromagnetic shielding means 07 is grounded, i.e., has a ground connection 14. The electromagnetic shielding means 07 serves to reduce the coupling of electromagnetic interference radiation into the receiving coil.

[0024] Through the Fig. 1 and Fig. The shielding measures described in section 2 provide an EMC concept that advantageously improves the interference immunity of the sensor and the shielding arrangement 01 while being cost-effective.

[0025] Fig. 3 shows a schematic sketch of the electromagnetic shielding arrangement 01 in its installation environment in a vehicle 16. The vehicle 16 includes a vehicle cooling system 17, whose cooling circuits are controlled by a thermal management module 18. The thermal management module 18 includes the Fig.1, a valve 21 for controlling a coolant in the vehicle 16, and at least one motor 22 that can adjust the valve. A power supply 23, a higher-level communication interface 24, and a control unit 19 are also provided, although these are not part of the thermal management module. At least one motor 22 is used to adjust the valve 21. The motor 22 acts on a gear 25 to adjust the valve 21. A target 26 is arranged on the gear 25 to detect the setting position. The electromagnetic shielding arrangement 01 with a sensor is used to detect the respective valve position; the sensor transmits the detected values ​​of the valve position to the higher-level control unit 19 via a bus system. List of reference symbols 01 Electromagnetic shielding arrangement 02 assembled circuit board 03 Sensor circuit 04 Transmitting coil 05 Receiving coil 06 Low-pass filter 07 Electromagnetic shielding agent 08 FIR filter 09 Bus filter 10 - 11 Interface 11a Communication interface 11b Supply interface 12 radial conductor tracks 13 Short-circuit loop 14 Ground connection 15 - 16 vehicles 17 Vehicle cooling system 18 Thermal management module 19 Control unit 20 - 21 Valve 22 Engine 23 Power supply 24 higher-level communication interface 25 gearboxes 26 Target

Claims

[1] Electromagnetic shielding arrangement (01) for an inductive position sensor, the shielding arrangement (01) comprising: - a circuit board (02) having several conductor track levels with connection contacts to which at least three input lines are connected; - a sensor arranged on the circuit board (02), which comprises a sensor circuit (03), a transmitting coil (04), a capacitor, a target (26) for influencing the transmitted signal and at least two receiving coils (05), wherein the transmitting coil (04) and the capacitor are arranged on the circuit board (02) and serve to generate a magnetic transmitted signal, wherein the receiving coils (05) are arranged on the circuit board (02) and serve to receive the transmitted signal, wherein the first of the two receiving coils has a sine winding and the second of the two receiving coils has a cosine winding, so that a position of the target (26) can be determined from the received signals by means of a control unit; - a low-pass filter (06) connected to the receiving coils (05) to filter out interference signals; - several damping beads arranged on the input lines; - an electromagnetic shielding means (07) which comprises a plurality of conductor tracks running on the circuit board, at least one of which is designed as a short-circuit loop (13), wherein the conductor tracks of the electromagnetic shielding means (07) are arranged on the circuit board (02) in such a way that they partially cover the receiving coils (05). [2] Electromagnetic shielding arrangement (01) according to claim 1, characterized by that the electromagnetic shielding means (07) is disc-shaped with numerous radially extending conductor tracks (12). [3] Electromagnetic shielding arrangement (01) according to claim 2, characterized by that the short-circuit loop (13) is arranged in the center of the electromagnetic shielding means (07) and electrically short-circuits the radially extending conductor tracks (12) emanating from there. [4] Electromagnetic shielding arrangement (01) according to one of claims 1 to 3, characterized by that the low-pass filter (06) is an RCRC low-pass. [5] Electromagnetic shielding arrangement (01) according to one of claims 1 to 4, characterized by that the sensor includes an FIR filter. [6] Electromagnetic shielding arrangement (01) according to one of claims 1 to 5, characterized by that the damping beads are ferrite beads. [7] Electromagnetic shielding arrangement (01) according to one of claims 1 to 6, characterized by that the board (02) is a printed circuit board that has exactly four conductor track levels. [8] Electromagnetic shielding arrangement (01) according to one of claims 1 to 7, characterized by that it comprises a bus system for data transmission, wherein the bus system uses a SENT bus. [9] Electromagnetic shielding arrangement (01) according to claim 8, characterized by that the SENT bus is coupled with a CRC filter. [10] Thermal management module for a vehicle (16) with an electromagnetic shielding arrangement (01) with a sensor according to one of claims 1 to 9, further comprising a valve (21) for controlling a cooling liquid and at least one motor (22) which serves to adjust the valve (21).

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