Assembly for a sensor

Abstract

Assembly for a sensor, comprising - a cap (30) which is essentially hollow cylindrical and closed at a first end, - a coil (20) arranged at the first end in the cap (30), and - an essentially hollow cylindrical insert (10) which is inserted into the cap (30) such that its first end faces the coil (20) and its second end protrudes from the cap (30), wherein the insert (10) has at least one locking hook (11) in its interior which is resiliently designed orthogonal to the longitudinal axis of the insert (10), characterized in that the insert (10) has a first positioning element (12) in the form of a projection which engages with the coil (20) and a second positioning element (13) in the form of a rail which is arranged to receive a printed circuit board (50) pushed through the second end of the insert (10).

Description

[0001] The present invention relates to an assembly for a sensor and a sensor comprising this assembly. State of the art

[0002] Sensors, such as inductive proximity sensors, contain a coil that acts as a transmitting and / or receiving coil. This coil is installed in a housing along with a circuit board and electrically connected to it via a soldered connection. To protect against moisture ingress, the interior of the housing is filled with a filler material. This can be, for example, polyurethane foam or a casting resin. This material also prevents movement of the circuit board within the housing relative to the coil, which could cause the soldered connection to break. However, a disadvantage of using such foams or resins is that they are environmentally hazardous substances.

[0003] US 2011 / 0018529A1 describes an angle sensor. This sensor has a cap containing a coil. An insert is fitted into the cap and has a spring-loaded locking tab inside.

[0004] One object of the present invention is to provide a sensor that does not require its interior to be filled with foam or resin. A further object of the present invention is to provide an assembly that enables quick and cost-effective mounting of such a sensor. Disclosure of the invention

[0005] This problem is solved in a first aspect of the invention by an assembly for a sensor. This assembly comprises a cap that is essentially hollow cylindrical, preferably hollow circular cylindrical. The cap has a first end and a second end and is closed at the first end. A coil is arranged at the first end in the cap. The coil can, in particular, be arranged on or in a substrate material. It is especially designed as a printed circuit board coil. Furthermore, the coil can, in particular, be arranged together with one or more other coils on or in the substrate material. The coil can be designed as a transmitting coil, a receiving coil, or a transmitting and receiving coil. The assembly also comprises an essentially hollow cylindrical insert, which is preferably hollow circular cylindrical. This insert has a first end and a second end.It is inserted into the cap in such a way that its first end faces the coil and its second end protrudes from the cap. The insert has at least one, preferably two, locking hooks inside. Each locking hook is spring-loaded and perpendicular to the longitudinal axis of the insert.

[0006] The locking hook allows a printed circuit board (PCB) to be fixed in a defined position within the assembly. When it engages a recess in the PCB, it holds the board securely in place within the assembly, eliminating the need for foam or resin as a filler material to prevent subsequent positional changes of the PCB relative to the assembly and thus to the coil. Furthermore, integrating the cap, coil, and insert into a single assembly offers the advantage of using it as a stocked pre-assembly unit for subsequent quick and flexible final assembly of various sensor types. The sensor type is determined by the type of PCB that is inserted into the assembly and connected to the coil.

[0007] It is preferred that the insert, in its area arranged within the cap, comprises at least three sub-areas. A first sub-area adjoins a second sub-area, the second sub-area adjoins a third sub-area, and the third sub-area adjoins the second end of the cap and may extend beyond it. The outer diameter of the first sub-area is larger than the outer diameter of the second sub-area. The outer diameter of the second sub-area is larger than the outer diameter of the third sub-area. This means that the outer diameters of the sub-areas increase from the open second end of the cap towards its closed first end.

[0008] This design of the sub-sections can be advantageously used to fix the insert in the cap. For this purpose, a space between an inner wall of the cap and the second sub-section, as well as the third sub-section of the insert, is preferably filled with an adhesive. Due to its relatively large distance from the inner wall of the cap, the third sub-section can be used as a dispensing chamber for the adhesive. In the second sub-section, where the distance between the inner wall of the cap and the outer wall of the insert is smaller than in the third sub-section, the insert and the cap are bonded using a small volume of adhesive. The first sub-section lies particularly close to the inner wall of the cap in such a way that it acts as an adhesive barrier, preventing the adhesive dispensed in the third sub-section from spreading beyond the third and second sub-sections.

[0009] Furthermore, it is preferred that the insert outside the cap has a fourth section. The outer diameter of the fourth section is smaller than the outer diameter of the third section. A first seal is arranged on the outer surface of the fourth section. This seal is particularly preferably designed as an O-ring surrounding the fourth section. When the assembly is inserted into a sensor housing, the first seal prevents moisture that creeps between the cap and the inner wall of the sensor housing from spreading further into the interior of the sensor housing at this end. The adhesive prevents moisture from penetrating the cap. Thus, the sensor is sealed against liquid and gaseous media without the need to fill the interior of the sensor housing with foam or resin.In this way, a sensor can be obtained that meets the IP68 protection class according to the ISO 20653 standard.

[0010] During final assembly of the sensor, its circuit board must be positioned precisely relative to the coil. To ensure this, the insert is designed with a first positioning element in the form of a projection that engages with the coil. Specifically, it engages with a recess in a support material of the coil. In this way, the coil is positioned precisely relative to the insert. Furthermore, the insert is designed with a second positioning element in the form of a rail. This rail is designed to accommodate a circuit board inserted through the other end of the insert. This also positions the circuit board precisely relative to the insert. Because the coil and circuit board are fixed relative to the insert, a defined relative position of the circuit board to the coil can be achieved.

[0011] However, there is still the possibility of mispositioning the circuit board by rotating it 180° relative to its intended position. To eliminate this risk, it is preferable for the insert to have a third positioning element at its other end. This element is designed to align a light source on the circuit board. Circuit boards used in sensors often have a light source, such as an LED, on one side. The third positioning element, which might be a recess in the insert, can serve as an optical positioning aid to ensure that the correct orientation is selected from the two possible orientations of the circuit board in the rail. This prevents mispositioning.

[0012] In another aspect of the invention, the problem is solved by a sensor, in particular an inductive sensor, which comprises the assembly. Furthermore, the sensor includes a printed circuit board. This extends through the second end of the insert into the assembly and is locked in place by a locking hook. For this purpose, the printed circuit board has, in particular, a recess into which the locking hook engages. The printed circuit board is fixed in position within the sensor relative to the assembly and thus relative to the coil.

[0013] It is preferred that the sensor has at least one spring element that electrically contacts the coil and the printed circuit board. In this way, the printed circuit board and the coil are electrically connected without the need for soldering. In different embodiments of the sensor, the spring element can be arranged either on the printed circuit board or on the coil. This arrangement is particularly feasible using surface-mount technology (SMT). When the printed circuit board is inserted into the assembly during final assembly of the sensor, the printed circuit board and the coil approach each other, so that either the spring element arranged on the printed circuit board comes into contact with the coil or the spring element arranged on the coil comes into contact with the printed circuit board.In this process, it is deflected, partially overcoming its spring force, so that it rests firmly against the circuit board or the coil and establishes a secure electrical connection between the circuit board and the coil.

[0014] Particularly suitable embodiments of the spring element for the sensor are selected from the group consisting of a spring contact, an edge connector and a cable clamp.

[0015] A spring contact can be designed differently in various embodiments. For example, it can be bent once or multiple times. In embodiments where the spring contact is arranged on the printed circuit board (PCB), its contact point with the coil can be located in the plane of the PCB or above it. It can extend from the end of the PCB facing the coil towards the coil, or it can initially run above the PCB before contacting the coil. Furthermore, it is possible for the spring contact to encircle the PCB by being located on one side of the PCB, projecting from there towards the coil to a point where it contacts the coil, and then extending from there to the opposite side of the PCB.

[0016] If the spring element is designed as an edge connector, it is in particular arranged on a carrier material of the coil so that the end of the circuit board can be pushed into the edge connector.

[0017] If the spring element is designed as a cable clamp, which can also be called a cable clip, it is specifically arranged on a support material of the coil. It can simultaneously contact the circuit board inserted into the cable clamp from both its top and bottom surfaces and establish an electrical connection to the circuit board in the area of ​​surface metallization.

[0018] The assembly and the printed circuit board are preferably arranged in a housing, which is particularly cylindrical. One end of the housing is closed off by the assembly. A tube end cap is arranged at the other end of the housing. The tube end cap has a connector insert that is electrically connected to the printed circuit board. A second seal is arranged between the tube end cap and an inner wall of the housing. This seal is preferably designed as an O-ring. In this way, the end of the housing opposite the assembly can also be reliably sealed against the ingress of fluids. It is therefore not necessary to fill the interior of the housing with a foam or resin. Instead, it is preferred that the printed circuit board is surrounded by a gas, particularly air. Brief description of the drawings

[0019] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. Fig. Figure 1a shows an isometric representation of an insertion of a sensor according to an embodiment of the invention. Fig. Figure 1b shows another isometric representation of the insert according to Fig. 1a. Fig. Figure 1c shows another isometric representation of the insertion according to Fig. 1a. Fig. Figure 1d shows a sectioned isometric view of the insert according to Fig. 1a. Fig. Figure 2 shows a sectional view of a sensor assembly according to an embodiment of the invention. Fig. Figure 3 shows a sectional view of an insert and an adhesive arranged therein of the assembly according to Fig. 2. Fig. Figure 4 shows an isometric representation of a coil in an embodiment of the sensor according to the invention. Fig. Figure 5 shows a sectional view of a sensor according to an embodiment of the invention. Fig. Figure 6 shows an isometric sectional view of how, in an embodiment of the sensor according to the invention, a guide plate is inserted into an insert. Fig. Figure 7 shows in an isometric sectional view the arrangement of a printed circuit board in an assembly of a sensor according to an embodiment of the invention. Fig. Figure 8a shows an isometric representation of a spring contact of a sensor according to an embodiment of the invention. Fig. Figure 8b shows an isometric representation of another spring contact of a sensor according to an embodiment of the invention. Fig. Figure 8c shows an isometric representation of yet another spring contact of a sensor according to an embodiment of the invention. Fig. Figure 8d shows an isometric representation of yet another spring contact of a sensor according to an embodiment of the invention. Fig. Figure 8e shows an isometric representation of yet another spring contact of a sensor according to an embodiment of the invention. Fig. Figure 8f shows an isometric representation of yet another spring contact of a sensor according to an embodiment of the invention. Fig. Figure 8g shows an isometric representation of yet another spring contact of a sensor according to an embodiment of the invention. Fig. Figure 9 shows an isometric representation of an edge connector of a sensor according to an embodiment of the invention. Fig. Figure 10 shows an isometric representation of a cable clamp of a sensor according to an embodiment of the invention. Fig. Figure 11 shows a side view of how a circuit board is arranged in a cable clamp in a sensor according to an embodiment of the invention. Fig. Figure 12 shows in an isometric sectional view the arrangement of a printed circuit board in an assembly according to an embodiment of the invention. Exemplary embodiments of the invention

[0020] To manufacture a sensor according to an embodiment of the invention, which is designed, for example, as an inductive sensor, an assembly is first produced that serves as a pre-assembly group for the subsequent final assembly of the sensor. This assembly has an insert 10 which is located in the Fig. Figures 1a to 1d illustrate the insert 10. It is essentially in the form of a hollow circular cylinder. Inside, it has two locking hooks 11, which are integrally formed with the insert. The locking hooks 11 are spring-loaded and perpendicular to the longitudinal axis of the insert 10. At one end, the insert 10 has a first positioning element 12 in the form of a projection. At its opposite end, the opening of the hollow cylinder is narrowed, and a second positioning element 13, in the form of a rail, is formed within this narrowing. Viewed from its second end, the insert 10 has a circular opening that is enlarged at two opposite points by the second positioning element. If a plane is drawn through this rail, the two locking hooks 11 also lie in this plane. The circular opening is further enlarged by a third positioning element 14.This extension is orthogonal to the plane.

[0021] In addition to the insert 10, the assembly comprises a coil 20 and a cap 30. The insert 10 is made of plastic. The coil 20 is a printed circuit board coil embedded in a printed circuit board substrate. This substrate has a circular cross-section. The cap 30 is also made of plastic. It has a substantially cylindrical outer contour and is closed at one end. The coil 20 is inserted into the cap 30 such that it contacts the end of the first end. The insert 10 is inserted into the cap 30 such that it rests on the coil 20 and protrudes partially from the cap 30. The insert 10 has four sections 15-19 with different outer diameters. A base section 15 contacts the coil 20. This section borders a first section 16, which has the largest outer diameter of all the sections.This section also engages in an annular recess in the cap 30 and thus secures the insert 10 in its position. The first section 16 is followed by a second section 17, a third section 18, and a fourth section 19. The outer diameter of these sections decreases from the first section 16 to the fourth section 19. The base section 15, the first section 16, and the second section 17 are located entirely within the cap 30. The third section 18 is located partially inside and partially outside the cap 30. The fourth section 19 is located entirely outside the cap 30.

[0022] To permanently bond the insert 10 to the cap 30, an adhesive is injected into the cap 30 through the gap between the inner wall of the cap 30 and the outer wall of the insert 10. As shown in Fig. As shown in Figure 3, it first fills the space between the cap 30 and the second section 18, which functions as a dosing chamber and has, for example, a volume of 22.7 mm³. 3 It may have this. Below this area of ​​adhesive 41, it continues to flow into the space between the cap 30 and the first section 17. Here, a smaller volume of, for example, 4.8 mm² is formed. 3 The space is filled with adhesive 42, resulting in a firm bond between the insert 10 and the cap 30. The first section 16 then acts as an adhesive barrier, preventing the adhesive 41, 42 from flowing further into the cap 30.

[0023] In Fig. Figure 4 shows that the printed circuit board substrate of the coil 20 has a recess 21 on its outer surface. The first positioning element 12 of the insert 10 engages in this recess 21, so that the coil 20 is positioned in the cap 30 in a defined manner relative to the insert 10.

[0024] Fig. Figure 5 shows a representation of a fully assembled sensor according to an embodiment of the invention. A printed circuit board 50 was inserted into the assembly, which consists of the coil 20 insert 10 and the cap 30. The assembly and the printed circuit board 50 were arranged together in a cylindrical housing 60, which is made, for example, of plastic, such that the cap 30 closes the housing 60 at one end. A tube end cap 70 was inserted into the housing 60 from the other end, closing the housing 60 at its other end. A connector insert 71 is arranged in the tube end cap, which electrically contacts the printed circuit board 50. The sensor's printed circuit board 50 can be connected to external devices via the plug contacts of the connector insert 71. The sensor has a first seal 81 and a second seal 82, each designed as an O-ring.The first seal 81 wraps around the fourth section 19 of the insert 10, so that this section 19 acts as a collar for the first seal 81. The second seal 82 wraps around the pipe end 70. The two seals 81 and 82 form a fluid-tight seal around the interior of the housing 60. This interior is filled with air.

[0025] Fig. Figure 6 shows how the circuit board 50 is inserted into the insert 10. It was inserted into the insert 10 from the end of the assembly furthest from the coil 20, through the rail 13, until the two locking hooks 11 of the insert 10 engaged in two recesses on the edges of the circuit board 50, preventing it from moving any further forward or backward. On the in Fig. On the non-visible side of the circuit board, a light source in the form of an LED is arranged, which protrudes from that surface of the circuit board 50. The circuit board 50 was inserted into the insert 10 such that the third positioning element 14 is located on the same side of the circuit board 50 as the light source. The LED can emit light through a window (not shown) in the housing 60 of the sensor into its surroundings, thus providing information about the function of the sensor.

[0026] Fig. Figure 7 shows that a spring element in the form of a spring contact 90 is arranged on the circuit board 50 at the end of the circuit board 50 that faces the coil 20. This is pressed against the coil 20 when the circuit board 50 is inserted into the assembly and forms an electrical connection between the circuit board 50 and the coil 20.

[0027] In the Fig. Figures 8a to 8g show different embodiments of the spring contact 90. In each case, this contact is arranged on a metallization 52 of the circuit board 50 and contacts the coil 20. According to Fig. 8a the spring element is designed as a spring contact 90, which is bent three times and projects from the end of the circuit board 50 towards the coil 20. According to Fig. 8b, however, has the spring contact 90 bent four times. According to Fig. In 8c, it is even bent five times. According to Fig. 8d The spring contact 90 initially springs forward from the circuit board 50 in the opposite direction to the coil 20, is then bent so that it runs parallel to the circuit board 50 towards the coil 20, and is finally bent twice more to contact the coil 20 in the plane of the circuit board 50. According to Fig. In a similar configuration, coil 20 is provided to be contacted above the plane of the printed circuit board 50. Fig. 8f A spring contact 90, bent four times, runs from the end of the circuit board 50 towards the coil 20 and also surrounds the circuit board 50. According to Fig. 4g the spring contact 90 initially extends away from the coil 20, then runs parallel to the circuit board 50 towards the coil 20 and is subsequently bent several times in order to contact the coil 20 on the one hand and to grip the circuit board 50 on the other and run away from the coil 20 again under the metallization 52 parallel to the circuit board 50.

[0028] Fig. Figure 9 shows an embodiment in which a spring element is arranged not on the printed circuit board 50, but instead on the printed circuit board substrate of the coil 20. It is designed as an edge connector 91. When the printed circuit board 50 is inserted into the assembly, the edge of the printed circuit board 50 is inserted into the edge connector 91.

[0029] In another embodiment, a spring element is provided, which is designed as a cable clamp 92. As in Fig. As shown in Figure 11, this is arranged on the surface of the printed circuit board substrate of the coil 20. The printed circuit board 50 has a metallization 52 on both its top and bottom surfaces. It is inserted into the cable clamp 92 in such a way that the clamp makes contact with both metallizations 52.

[0030] Another embodiment of the sensor, which is in Fig. The embodiment shown in 12 differs from the embodiment shown in Fig.5 in that the insert 10 is not bonded to the cap 30. Instead, a third seal 83 is provided, which surrounds the insert 10 and is located between it and the cap 30. In this embodiment of the sensor, both the first seal 81 and the third seal 83 are injection-molded onto the insert 10. The insert 10 is secured in the cap 30 by the third seal 83 and by compression of the first region 16 of the insert 10.

Claims

[1] Assembly for a sensor, comprising - a cap (30) which is essentially hollow cylindrical and closed at a first end, - a coil (20) arranged at the first end in the cap (30), and - an essentially hollow cylindrical insert (10) which is inserted into the cap (30) such that its first end faces the coil (20) and its second end protrudes from the cap (30), wherein the insert (10) has in its interior at least one locking hook (11) which is resiliently designed orthogonal to the longitudinal axis of the insert (10), characterized by , that the insert (10) has a first positioning element (12) in the form of a projection which engages with the coil (20) and has a second positioning element (13) in the form of a rail which is designed to receive a printed circuit board (50) which is pushed through the second end of the insert (10). [2] Assembly according to claim 1, characterized by , that the insert (10) in its area arranged in the cap (30) has at least three sub-areas (16-18), wherein a first sub-area (16) adjoins a second sub-area (17), the second sub-area (17) adjoins a third sub-area (18) and the third sub-area (18) adjoins the second end of the cap (30), and wherein an outer diameter of the first sub-area (16) is larger than an outer diameter of the second sub-area (17) and the outer diameter of the second sub-area (17) is larger than an outer diameter of the third sub-area (18). [3] Assembly according to claim 2, characterized by , that a space between an inner wall of the cap (30) and the second sub-area (17) and third sub-area (18) of the insert (10) is filled with an adhesive (41, 42). [4] Assembly according to claim 2 or 3, characterized by, that the insert (10) outside the cap (30) has a fourth sub-area (19) whose outer diameter is smaller than the outer diameter of the third sub-area (18), wherein a first seal (81) is arranged on an outer side of the fourth sub-area (19). [5] Assembly according to any one of claims 1 to 4, characterized by , that the insert (10) has a third positioning element (14) at its second end, which is set up to align a light source of the circuit board (50). [6] Sensor comprising an assembly according to one of claims 1 to 5 and a printed circuit board (50) which extends through the second end of the insert (10) into the assembly and is locked with the latch hook (11). [7] Sensor according to claim 6, characterized by that it has at least one spring element that electrically contacts the coil (20) and the circuit board (50). [8] Sensor according to claim 7, characterized by, that the spring element is selected from the group consisting of a spring contact (90), an edge connector (91) and a cable clamp (92). [9] Sensor according to any one of claims 6 to 8, characterized by , that the assembly and the printed circuit board (50) are arranged in a housing (60), wherein a tube end (70) having a plug insert (71) is arranged at one end of the printed circuit board (50) in the housing (60) and a second seal (82) is arranged between the tube end (70) and an inner wall of the housing (60). [10] Sensor according to claim 9, characterized by , that the circuit board (50) is surrounded by a gas.

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