Sensor arrangement for measuring the temperature of a disc

Abstract

Sensor arrangement (1) for measuring the temperature of a disk (10), wherein the sensor arrangement (1) comprises a circuit carrier (2) with a temperature sensor (3) arranged thereon, wherein an electrical connection (5) to the circuit carrier (2) is brought out of a housing (4), and wherein the sensor arrangement (1) comprises a rigid pin (6) which has a thermal and a mechanical connection with the circuit carrier (2) and is suitable for establishing a thermal contact (11) with the disk (10), characterized in that the housing (4) is designed for its arrangement adjacent to the disk (10), and that the rigid pin (6) is a heat-conducting element brought out of the housing (4), which is provided and designed for this purpose.to establish a thermal connection between the disk (10) and the circuit carrier (2) arranged in the housing (4) with the temperature sensor (3) through the housing (4) via its thermal contact (11) with the disk (10), and that the circuit carrier (2) has at least two layers (7, 8) and one layer (8) is designed as a thermal guide plate (9).

Description

[0001] The invention relates to a sensor arrangement for measuring the temperature of a disk, wherein the sensor arrangement comprises a circuit carrier with a temperature sensor arranged thereon.

[0002] Sensor arrangements are known from DE 10 2010 026 563 A1 and DE 10 2006 060 548 A1. In each of these applications, a flexible printed circuit board is extended from a housing and brought into contact with a windshield. The flexible printed circuit board thus serves as a thermal interface material. A temperature sensor is then arranged directly on the flexible printed circuit board, which can be used to determine the temperature of the windshield.

[0003] Another sensor arrangement with a flexible heat-conducting element is known from DE 10 2005 038 466 B4.

[0004] DE 103 25 971 A1 discloses a generic sensor arrangement in which a carrier element designed as a printed circuit board with a temperature sensor is arranged on the front of a housing. To attach the housing to the carrier element, the carrier element is either welded to the housing via a pin or bonded to the housing. Due to its exposed position on the front of the housing, the carrier element can be positioned adjacent to the windshield, allowing the temperature sensor to measure the temperature there.

[0005] US 2010 / 0231155A1 discloses a control unit with an integrated temperature sensor. A heat-sensitive element is mounted on a circuit board, and a hole for a pin is provided in the circuit board. An electrical conductor connects the edge of the hole to the heat-sensitive element.

[0006] From JP 2000- 91 884 A a multilayer printed circuit board is known which is screwed onto a metal plate.

[0007] DE 40 06 420 A1 discloses a device for optically detecting foreign bodies by means of a sensor which is arranged on the inside of the disc, separated from the disc by an optically non-transparent film.

[0008] In the subsequently published DE 10 2018 113 230 A1, a sensor module comprising a printed circuit board and a thermal interface element is disclosed, the thermal interface element having a heat-conducting section projecting from the surface of the printed circuit board. A thermal contact is established via the thermal interface element from a mounting section of the sensor module, which rests against a windshield, to a temperature sensor located on the printed circuit board in the immediate vicinity of the thermal interface element.

[0009] The invention is based on the objective of creating a sensor arrangement with a protected circuit carrier that is particularly inexpensive to manufacture.

[0010] This problem is solved starting from DE 103 25 971 A1 with a sensor arrangement having the features of claim 1. Preferred embodiments of the invention are specified in the dependent claims.

[0011] In a sensor arrangement for measuring the temperature of a disk, wherein the sensor arrangement comprises a circuit carrier with a temperature sensor arranged thereon, wherein an electrical connection to the circuit carrier is brought out of a housing, and wherein the sensor arrangement has a rigid pin which has a thermal and a mechanical connection with the circuit carrier and is suitable for establishing thermal contact with the disk, it is essential to the invention that the housing for its arrangement is designed adjacent to the disk and that the rigid pin is a heat-conducting element brought out of the housing, which is designed and configured to establish a thermal connection between the disk and the circuit carrier arranged in the housing with the temperature sensor through the housing via its thermal contact with the disk.and that the circuit carrier has at least two layers and one layer is designed as a thermal conductor plate.

[0012] Thermal contact with the disc can be established either directly or indirectly, i.e., directly or via connecting elements. Overall, this sensor arrangement results in a particularly simple and effective sensor configuration, which also eliminates the need for a flexible circuit board and thus significantly simplifies the overall design.

[0013] In a particularly preferred embodiment of the invention, the rigid pin is part of the electrical connection of the sensor assembly. This allows the rigid pin to perform two functions: providing an electrical contact and simultaneously providing a thermal contact. This significantly simplifies the sensor assembly and makes it cost-effective to manufacture.

[0014] One layer of the circuit carrier is designed as a thermal interface material. The circuit carrier is, in particular, a multi-layered printed circuit board. Preferably, the thermal interface material is the second layer as viewed from the temperature sensor. The temperature sensor is preferably located on the windshield side, so that the thermal interface material is also the second layer as viewed from the windshield. Compared to the other layers of the circuit carrier or the printed circuit board, the thermal interface material is thicker and / or has fewer openings and interruptions, thus enabling particularly good thermal heat transfer.In contrast, the first or lowest layer of the circuit carrier, through which the primary electrical connection to the sensors arranged on the circuit carrier is made, is more delicate and equipped with more interruptions and electrical contact possibilities, so that this layer primarily serves for electrical contacting.

[0015] In another preferred embodiment of the invention, the sensor arrangement additionally includes a sensor for measuring the internal humidity and a sensor for measuring the internal temperature. From the measurement of these three values ​​in total—namely, the measurement of the internal humidity, the measurement of the internal temperature, and the measurement of the windshield temperature—the difference between the dew point of the windshield and the internal temperature can be calculated, and thus the tendency of the windshield to fog up can be calculated.

[0016] In a further preferred embodiment of the invention, the sensor arrangement is integrated into an optoelectronic rain sensor unit for motor vehicles. This unit also includes additional optical sensors that allow for reflection from the windshield to be performed and evaluated, determining whether the light incident on the windshield is fully or only partially reflected. The reflection behavior depends on whether water droplets are present on the windshield. This enables the implementation of a rain sensor.

[0017] In another embodiment of the invention, the rigid pin is thermally connected to a surface element that establishes greater thermal contact with the windshield than the rigid pin itself. This is an indirect thermal contact between the rigid pin and the windshield, which is also possible within the scope of the invention. Preferably, the surface element is part of the electrical connection and, in particular, part of a connector element.

[0018] In another further development of the invention, the temperature sensor is connected to the thermal interface material by means of a thermally conductive but electrically insulating material. This results in a particularly good thermal connection between the temperature sensor and the thermal interface material. The thermal contact between the pin and the circuit board is preferably created by metallizing the borehole.

[0019] In another development, thermal contact with the windshield occurs in the area of ​​a black film. This is frequently used in connection with such sensor arrangements and optically conceals the sensors and contacts on the windshield.

[0020] Overall, the design according to the invention achieves coupling to the disk via the rigid pin itself or via the surface element, thereby enabling fast and accurate temperature measurement. Pressing the rigid pin into the layers of the circuit carrier allows for rapid and accurate temperature measurement. The thin plastic layer between the layers of the circuit carrier and the solder joints of the temperature sensor causes only a small static / thermal measurement error. This is particularly easy because the thermal contact between the rigid pin and the circuit carrier can be established by the metallization of the borehole. No additional component is required.

[0021] The invention will now be explained in more detail with reference to an embodiment illustrated in the drawing. Specifically, the schematic representations in: Fig. 1: a schematic view of a sensor arrangement according to the invention, Fig. 2: a perspective view of a sensor arrangement according to the invention showing the connection of the electrical contact to a connector basket.

[0022] In Fig. Figure 1 shows a schematic view of a sensor arrangement 1 according to the invention. A circuit carrier 2, typically a printed circuit board, is housed in a housing 4. The circuit carrier 2 has several metallic layers 7, 8 and insulating layers located between them. The housing 4 is arranged adjacent to a disk 10, in particular a windshield. An electrical connection 5 and a thermal conducting element, which here is designed as a rigid pin 6, extend from the housing 4. The rigid pin 6 forms a thermal contact 11 with the disk 10.The rigid pin 6 is pressed into the housing 4, which is preferably a plastic housing, and the circuit board 2 preferably has a correspondingly prepared metallized bore 15 into which the rigid pin 6 is pressed, thus establishing electrical and thermal contact between the rigid pin 6 and the various layers 7, 8 of the circuit carrier 2. Layer 8, which faces away from the disk 10 and is also away from or further away from a temperature sensor 3 arranged on the circuit carrier 2, is designed as a thermal interface material 9. The thermal interface material 9 is a layer of the circuit carrier 2 that is thickened and / or has fewer interruptions, thus providing particularly good thermal conductivity.This transfers the temperature measured via the rigid pin 6 to the area of ​​the temperature sensor 3, enabling the temperature sensor 3 to detect the temperature of the disk 10 particularly quickly and accurately. Additionally, an electrically insulating, yet thermally conductive material can be introduced here, connecting the temperature sensor 3 to the thermal interface material 9. Furthermore, the housing 4 contains a sensor for measuring the internal humidity 12, which is also electrically connected via the first layer 7 of the circuit carrier 2. The sensor element 3 is also electrically connected to the first layer 7 of the circuit carrier 2 and is controlled via this layer. It can be a two-pole or three-pole temperature measuring element, in which case one terminal is a separate thermal connection.

[0023] In Fig.Figure 2 shows an overall assembly with an outer housing 17 in which the sensor assembly 1 with the circuit carrier 2 is accommodated. The rigid pin 6 is connected here to a surface element 13, which is in contact with the disk 10 on the outside of the outer housing 17. This ensures particularly good thermal contact. The surface element 13 is part of the electrical connection 5, which extends into a connector housing 18 of the outer housing 17. The electrical connection 5 also simultaneously provides the electrical connection via the rigid pin 6 to the circuit carrier 2.

[0024] All features mentioned in the foregoing description and in the claims can be combined in any selection with the features of the independent claim. The disclosure of the invention is therefore not limited to the described or claimed combinations of features; rather, all combinations of features meaningful within the scope of the invention are to be considered disclosed.

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