Pressure sensor assembly

Abstract

Pressure sensor arrangement (10) with a sensor element (1) and a hermetic housing (2) for the sensor element (1), - wherein the housing (2) comprises a first housing part (15) with a housing base (17) and at least one further housing part (16), - wherein the sensor element (1) is mounted on the housing base (17) and the pressure supply is provided via an opening (3) in the housing base (17), - wherein at least one further housing part (16) is arranged above the sensor element (1) and is connected to the first housing part (15), and - wherein connection pins (5) are provided for electrical contacting the sensor element (1); wherein the connection pins (5) are guided through the further housing part (16), and wherein a circuit carrier (4) is arranged in the housing (2) such that the electrical connections of the sensor element (1) are guided onto the circuit carrier (4) and that connecting means for establishing an electrical connection between the connection pins (5) and the circuit carrier (4) are provided, and wherein a flexible film (19) is guided as a connecting means from the circuit carrier (4) to the connection pins (5).

Description

State of the art

[0001] The invention relates to a pressure sensor assembly comprising a sensor element and a hermetic housing for the sensor element. The housing of this pressure sensor assembly includes a first housing part with a housing base and at least one further housing part. The sensor element is mounted on the housing base, and the pressure is supplied via an opening in the housing base. The at least one further housing part is arranged above the sensor element and connected to the first housing part. The pressure sensor assembly also includes connection pins for electrically contacting the sensor element.

[0002] Such sensor arrangements are used for pressure measurement in liquid and gaseous media, and are often exposed to aggressive environmental conditions.

[0003] A pressure sensor arrangement of the type mentioned above is known from practical experience. The sensor element is housed in a hermetically sealed steel casing consisting of a relatively thick-walled base and a relatively thin-walled cap. The base and cap are welded together. An opening is formed in the base, over which the sensor element is mounted. This opening, together with a pipe fitting on the outside of the casing, forms the hydraulic connection of the sensor arrangement. The electrical connections are implemented as connection pins, which also pass through the casing base and are connected to the sensor element via bond wires. Accordingly, the electrical connection of the known pressure sensor arrangement is located on the same side of the casing as the hydraulic connection.

[0004] This concept requires special precautions to prevent the electrical connections from coming into contact with the measuring medium and thus being chemically attacked. In practice, this is achieved by extending the hydraulic connection with a tube or similar component, which is relatively complex in design and requires additional parts.

[0005] Further pressure sensor devices are known in the patent applications DE 100 14 992 A1, US 2003 / 0107491 A1, US 2002 / 0029639 A1 and EP 0 949 494 A2. Disclosure of the invention

[0006] The present invention proposes a pressure sensor arrangement of the type mentioned above, which is characterized by a particularly uncomplicated installation, especially under aggressive environmental conditions.

[0007] According to the invention, the connection pins are guided through the further housing part of the pressure sensor arrangement, while the pressure is applied via an opening in the housing base.

[0008] This arrangement of the connection pins ensures that the hydraulic and electrical connections of the pressure sensor assembly are located on different sides of the housing. Therefore, the pressure sensor assembly according to the invention is equipped with a hydraulic connection side and a separate electrical connection side. Consequently, further design elements for spatially separating the hydraulic and electrical connections, such as a pressure connection tube, are not required.

[0009] To assemble a pressure sensor arrangement of the type mentioned above, the sensor element is first mounted on the housing base, specifically above the pressure connection opening. Then, the remaining housing parts are arranged over the sensor element like a cap and connected to the first housing part to hermetically seal the housing. If, according to the invention, the connection pins are guided through the housing cap, special measures are required to establish an electrical connection between the sensor element and the connection pins.

[0010] According to the invention, the pressure sensor arrangement comprises a circuit carrier, for example in the form of a printed circuit board, which is arranged in the housing together with the sensor element. The electrical connections of the sensor element are routed to the circuit carrier. If the circuit carrier is mounted on the housing base together with the sensor element, the electrical connections can be easily routed to the circuit carrier using bond wires before the housing is closed. Additional connecting means are provided according to the invention for the electrical connection between the circuit carrier and the connection pins in the housing cap.

[0011] Basically, there are various ways to implement an electrical connection between the connection pins and such a circuit carrier, whereby it should be noted that this connection only comes about when the housing parts are joined together or when it receives its final design.

[0012] According to the invention, a flexible film is used as a connecting element from the circuit carrier to the connection pins. The electrical connection between the circuit carrier and the connection pins is established, i.e., the flexible film is mounted, before the housing parts are assembled and mechanically connected. The flexible film is then folded into the housing.

[0013] Besides being used for re-contacting, the circuit carrier can also advantageously be used to arrange further circuit components or elements, in particular an EMC capacitor, within the housing. Furthermore, contact surfaces, such as needle contact pads, can be provided on the circuit carrier for sensor calibration. In this case, sensor calibration can be performed before the housing is assembled or closed, i.e., at a lower value-added stage, thereby reducing the number of connection pins.

[0014] The use of a metallic housing, particularly made of steel, for the pressure sensor arrangement according to the invention proves advantageous in several respects. For example, the metallic surface of the housing base allows the sensor element to be mounted by soldering or welding. The resulting high-strength connection withstands the tensile loads that typically occur under pressure. Furthermore, a reliable, tight connection between the individual housing parts can be easily created by soldering or welding. A defined reference pressure, such as a vacuum, can be contained within the housing. Brief description of the drawings

[0015] As discussed above, there are various ways to advantageously elaborate and further develop the teaching of the present invention. For this purpose, reference is made, on the one hand, to the claims subordinate to the independent claim and, on the other hand, to the following description of an embodiment of the invention with reference to the drawing. Fig. 1 referred. Fig. Figure 1 shows a schematic sectional view of an embodiment of a pressure sensor arrangement 10 according to the invention. Fig. Figure 2 shows a schematic sectional view of a pressure sensor arrangement 20 not belonging to the invention, and Fig. Figure 3 shows a schematic sectional view of a pressure sensor arrangement 30 not belonging to the invention. Embodiments of the invention

[0016] The in Fig. The pressure sensor assembly 10, as illustrated in Figure 1, comprises a sensor element 1 in the form of a sensor chip 11 with a glass base 12. A diaphragm 13 is formed in the sensor chip 11 and is pressurized via a pressure supply opening 14 in the glass base 12. The sensor element 1 is arranged in a hermetically sealed steel housing 2, which, in the embodiment shown here, consists of a housing base 15 and a cap 16 as a further housing part. A recess 17 is formed in the housing base 15 as a mounting surface for the sensor element 1. An opening 3 is located in the base of the recess 17. The glass base 12 of the sensor element 1 is arranged in this recess 17 and soldered in place, so that the pressure supply opening 14 is located above the opening 3 in the housing base 15. Accordingly, the housing base 15 forms the hydraulic connection side of the pressure sensor assembly 10.However, the interior of the housing 2 is hermetically sealed due to the pressure-resistant mounting of the sensor element 1 above the opening 3.

[0017] A circuit board 4 is also arranged on the housing base 15, which serves for the re-contacting of the sensor element 1. The electrical connections of the sensor element 1 are led to the circuit board 4 by means of bond wires 18. The cap 16 of the housing 2 is arranged over the sensor element 1 and the circuit board 4 and is welded to the housing base 15.

[0018] According to the invention, the connection pins 5 for electrical contacting the sensor element 1 are led outwards through the cap 16. For this purpose, the connection pins 5 were encased in pressure-resistant glass. The electrical connection between the connection pins 5 and the circuit board 4 is established here by means of a flexible film 19, which is guided from the circuit board 4 to the connection pins 5. This flexible film 19 was connected to the circuit board 4 on one side and to the connection pins 5 on the other side before the assembly of the two housing parts 15 and 16, and folded inside the housing 2 when the two housing parts 15 and 16 were joined, which is achieved by Fig. 1 is illustrated.

[0019] The in Fig. The pressure sensor arrangement 20 shown in Figure 2 also comprises a sensor element 1 with a pressure sensor chip 11 on a glass base 12, which is arranged in a hermetically sealed steel housing 2. This housing 2 consists of two housing parts 21 and 22. The base 211 of the first housing part 21 is designed as a mounting surface for the sensor element 1 and has an opening 3 for pressurizing the sensor membrane 13. The glass base 12 of the sensor element 1 is pressure-tightly connected to the mounting surface 211 via a soldered connection 23, so that the sensor membrane 13 can be pressurized via the opening 3 in the first housing part 21 and via the pressure supply opening 14 of the glass base 12.

[0020] The first housing part 21 also includes a mounting surface 212 for a printed circuit board 4. The electrical connections of the sensor element 1 are led to the printed circuit board 4 via bond wires 18, where they can also be connected to other circuit elements. In the embodiment shown here, the printed circuit board 4 thus serves as a carrier for an EMC 24. Furthermore, a contact surface 25 is provided on the printed circuit board 4.

[0021] The second housing part 22 forms a cover that is positioned over the sensor element 1 and the circuit board 4 and is welded to the first housing part 21. Through-holes are formed in this cover 22, into which the connection pins 5 for electrical contacting the sensor element 1 are inserted. A leaf spring 26 is soldered to the end of one connection pin 5 that projects into the interior of the housing. When the two housing parts 21 and 22 are assembled, this leaf spring 26 is pressed against the contact surface 25 on the circuit board 4, which in Fig. Figure 2 shows that this creates an electrical connection between the connection pin 5 and the circuit board 4, through which the sensor element 1 is electrically contacted.

[0022] Fig. Figure 2 shows and illustrates the pressure sensor arrangement 20 in an application as a transmission pressure sensor. The pressure sensor arrangement 20 is installed between the base plate 41 and the hydraulic plate 42 of a transmission. The hydraulic connection side of the pressure sensor arrangement 20 is pressure-tightly mounted to the hydraulic plate 42, where the measuring pressure or the measuring medium is present, by means of a high-pressure seal 43. Due to the design concept according to the invention, the electrical connection side of the pressure sensor arrangement 20 faces the opposite base plate 41. Accordingly, the connection pins 5 are only accessible from the base plate 41 in the installed state, where they cannot come into contact with the measuring medium. The design concept thus enables a simple spatial separation between the hydraulic and electrical connection sides in the application.

[0023] The structure of the in Fig. The pressure sensor arrangement 30 shown in 3 largely corresponds to that of the pressure sensor arrangement 20 in Fig.2, except for the contacting of the connecting pins 5. In the case of the pressure sensor arrangement 30, a contact surface 25 is also formed on the circuit board 4 arranged in the housing 2. However, the electrical connection between the connecting pin 5 and the circuit board 4 is established here by means of a coil spring 31, which is pushed onto the connecting pin 5 and is press-fitted to the connecting pin 5 at its upper end. A contact area 32 is formed at the lower free spring end of the coil spring 31, which is pressed against the contact surface 25 on the circuit board 4 when the two housing parts 21 and 22 are assembled. This establishes an electrical connection between the connecting pin 5 and the circuit board 4, via which the sensor element 1 is ultimately contacted.In this variant, the connecting pin 5 also serves as a holder and guide for the spiral spring 31 by fixing the spiral spring 31 and absorbing the lateral force occurring when it is compressed, in order to prevent buckling.

Claims

[1] Pressure sensor arrangement (10) with a sensor element (1) and a hermetic housing (2) for the sensor element (1), - wherein the housing (2) comprises a first housing part (15) with a housing base (17) and at least one further housing part (16), - wherein the sensor element (1) is mounted on the housing base (17) and the pressure supply is provided via an opening (3) in the housing base (17), - wherein at least one further housing part (16) is arranged above the sensor element (1) and is connected to the first housing part (15), and - wherein connection pins (5) are provided for electrical contacting the sensor element (1); wherein the connection pins (5) are guided through the further housing part (16), and wherein a circuit carrier (4) is arranged in the housing (2) such that the electrical connections of the sensor element (1) are guided onto the circuit carrier (4) and that connecting means for establishing an electrical connection between the connection pins (5) and the circuit carrier (4) are provided, and wherein a flexible film (19) is guided as a connecting means from the circuit carrier (4) to the connection pins (5). [2] Pressure sensor arrangement (10) according to claim 1, characterized by , that at least one additional circuit element, in particular an EMC capacitor, is arranged on the circuit carrier (4). [3] Pressure sensor arrangement (10) according to one of claims 1 or 2, characterized by , that contact surfaces for sensor calibration are arranged on the circuit carrier (4). [4] Pressure sensor arrangement (10) according to one of claims 1 to 3, characterized by , that the first housing part (15) with the housing base (17) and the at least one further housing part (16) are made of steel and are soldered or welded together. [5] Pressure sensor arrangement (10) according to one of claims 1 to 4, characterized by , that a defined reference pressure prevails in the housing (2).

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