capacitive sensor

Abstract

The utility model relates to a capacitor sensor, this capacitor sensor includes the base plate (1) containing in the cover shell (2), the base plate (1) is electrically connected to the terminal (5) of external connector (3) by means of spring (4), wherein, the connecting spring (4) for connecting the base plate (1) to the terminal (5) is arranged in spring holder (6), the spring holder (6) establishes guided coupling with the base plate (1), and the spring holder (6) has fastening device, which establishes first interlock in preassembly position with the connecting spring (4) in repose in the base plate (1), and establishes second interlock with the connecting spring (4) compressed inside the spring holder (6) by pushing external connector (3) so that it closes on the cover shell (2) in final operating fastening position.

Description

Technical Field

[0001] This invention relates to sensors for applications such as controlling liquid levels in containers or tanks, and more specifically to sensors used in systems for measuring liquid levels in tanks in the automotive sector, where higher accuracy is required for the measurement standards. A capacitive sensor for these applications is proposed, characterized by ease of assembly and improved structural conditions to avoid potential errors in the functional behavior of measurements performed during sensor application. Background Technology

[0002] Capacitive sensors made of laminated materials are currently known on the market, and they consist of a substrate electrically connected to an external connector and housed inside a cover. The substrate includes electronic components by means of which liquid level can be detected based on the capacitance between electrodes, depending on whether they are in air or immersed in the liquid to be measured.

[0003] It is also known that the sensor connects the terminals of the external connector to the substrate by means of springs, which must be compressed during the assembly process to ensure electrical contact.

[0004] For assembly connection springs, the springs are typically arranged to be initially stretched so that they can be compressed during assembly. This causes the springs to fall out during the assembly process, the coils of the springs to get stuck during compression, or the springs to warp, and their ends to be outside the contact area with the terminals of the external connector. In any of these cases, defective assembly is caused.

[0005] Therefore, during the assembly of the capacitive sensor, in order to connect the terminals of the external connector to the substrate, the positioning and fixing of the connecting springs need to be properly centered and tightened to prevent the springs from falling out of their pre-assembly positions or warping during their compression into the assembly position.

[0006] Furthermore, the substrate of a capacitive sensor made of laminated material has a high coefficient of thermal expansion and may warp during thermal expansion, affecting sensor calibration and potentially even causing structural components to detach from the sensor. Therefore, to avoid this problem, a longitudinal gap must be present between the substrate and the cover to allow the substrate to expand within the housing during the assembly of the sensor assembly.

[0007] Therefore, there is a clear need for a capacitive sensor that allows for rapid and safe assembly of components and provides structural conditions to avoid problems that may affect the sensor's functional behavior. Utility Model Content

[0008] According to this utility model, a capacitive sensor developed according to an embodiment is proposed, which provides advantageous construction and functional features for both construction and assembly and for avoiding problems that may affect the proper functioning of the sensor.

[0009] As in conventional embodiments, the capacitive sensor of this invention includes a substrate incorporating electronic components capable of measuring the capacitance between electrodes based on a medium in which the electrodes are located. The substrate is disposed inside a cover and connected to terminals of an external connector by means of a spring.

[0010] According to this invention, connecting springs for connecting the terminals of a substrate and an external connector are arranged in a spring retainer that defines a housing in which the springs are inserted, thereby allowing them to be secured in a predetermined assembly position. The spring retainer further establishes a guided connection with the substrate and includes a fastening device that, in a pre-assembly position, establishes a first interlock with the stationary connecting springs within the substrate, and in a final operational fastened position, establishes a second interlock with the connecting springs compressed within the spring retainer by pushing the external connector to close it against a cover.

[0011] This ensures the connecting springs remain fixed during assembly, facilitating the assembly process, as the spring retainer engages with the substrate in a guided manner and, by establishing a first pre-assembled position, prevents the springs from falling out or shifting from their positions due to handling during assembly. The springs are guided within the spring retainer's housing, preventing them from warping or their coils from jamming when compressed longitudinally, thus preventing poor positioning during assembly, and establishing the final position once the connector is secured by pushing it until it closes against the housing. In this way, easy and safe assembly of the capacitive sensor is achieved, with the connecting spring compressed between the substrate and the terminals of the external connector, such that the spring's movement ensures electrical continuity while the substrate remains in a floating arrangement that absorbs dimensional changes due to temperature-induced expansion, and maintains the relative position of the substrates within the housing, preventing contact between them.

[0012] Preferably, to guide the connection of the spring retainer on the substrate, the spring retainer includes a groove having a geometry corresponding to the substrate, which facilitates positioning during assembly to reach a pre-assembly position and subsequently a final assembly position.

[0013] To allow the spring retainer to transition between a pre-assembled position where the connecting spring is stretched and a final assembled position where the connecting spring is compressed, the fastening device is at least one flexible pin, preferably two pins, one on each side of the spring retainer, and includes a protrusion at the distal end. The substrate has recesses at two different distances from the end of the substrate on its sides, having geometry corresponding to the protrusions of the pins of the spring retainer. Thus, to secure the spring retainer in the pre-assembled position by pushing it onto the substrate, the flexible pin engages with its protrusion in the recess closest to the end of the substrate, and to secure it in the final position, the connector is pressed until it closes, such that the protrusion engages in the recess furthest from the end of the substrate.

[0014] This feature results in a first temporary mating interlock in the pre-assembly position and a second holding interlock in the final assembly position, between which the external connector can be displaced by a simple push, during which the external connector pushes against the connecting spring to longitudinally compress them to the final assembly position.

[0015] To ensure the assembly of the capacitive sensor component, with the connecting spring between the substrate and the compression terminal positioned to ensure electrical contact at the terminals of the external connector, the housing accommodating the substrate and the external connector has reversible formations. The external connector includes at least two openings, and the housing includes at least one projecting flange reversible to each opening, thereby establishing an assembly retaining fit between the external connector and the housing. It is also envisioned that, provided the desired elastic fit is achieved, the openings will be located within the housing and the corresponding flanges will be located on the external connector.

[0016] This configuration establishes the closure of the capacitive sensor by pressing it against the stop, thereby ensuring the retention assembly resists the push of the compressed connecting spring, i.e., retention is established in the longitudinal direction of the sensor.

[0017] Because of the clearance required for proper fit, this longitudinal retaining fit sometimes allows for a certain amount of rotation between the housing and the external connector, where the walls of the openings are preferably thin and there is a risk that they may break, and the corresponding rotation may also affect the sensing capability of the sensor. Therefore, it is envisioned that the external connector includes at least one recess or protrusion on the inner surface of the outer edge of the external connector, which interacts with a reciprocating protrusion or recess on the outer surface of the housing to serve as an anti-rotation retaining fit for the assembly.

[0018] Preferably, the connector includes two recesses with opposite diameters corresponding to two protrusions of the housing, the recesses having different dimensions to define a single fastening position (mistake-proofing) to ensure correct assembly.

[0019] Furthermore, the sensor of this invention includes a lateral centering device for laterally centering the substrate relative to the shell. The device is a formation at the bottom of the shell corresponding to a formation at the end of the substrate, which causes the substrate to be laterally centered when inserted into the shell.

[0020] This design centers the substrate, allowing for a gap between the side edges of the substrate and the shell. This is because if the side is to be touched, the substrate will bend and warp into a cylindrical shape when touched due to expansion, which will affect the measurement accuracy of the sensor.

[0021] Preferably, the geometry corresponding to the two formations will be V-shaped. In this way, accurate and stable centering of the substrate relative to the shell is achieved during substrate insertion, such that in its final position, the lateral distance between the plate and the shell, which can be adjusted for sensor calibration, is maintained, and precise vertical movement is achieved, allowing the spring to properly absorb any possible expansion.

[0022] Furthermore, the housing preferably includes at least one longitudinal rib on its inner surface, configured to position the sensitive surface of the substrate in contact with the housing in the final assembly position. In other words, the longitudinal rib should be arranged opposite to the sensitive portion of the sensor housing, such that the electrodes are arranged as close as possible to the housing in the final assembly.

[0023] This construction achieves higher measurement accuracy because the thickness of the shell is controlled to account for the dielectric, given that the plastic of the shell is used as a dielectric, and the measurement accuracy is affected if there is a separation between the shell and the electrode, and the air between the two elements will also act as a dielectric.

[0024] In view of the foregoing, the capacitive sensor of this invention has advantageous features for its assembly and functional behavior, enabling it to function independently, and is preferred over known capacitive sensors used in the same applications. Attached Figure Description

[0025] Figure 1 An exploded perspective view showing the component assembly of an exemplary capacitive sensor according to the purpose of this utility model.

[0026] Figure 2 This is a cross-sectional front view of the substrate of the capacitive sensor, with a spring for connecting to the external connector of the sensor arranged in a pre-assembled position relative to the substrate.

[0027] Figure 3 In the final assembly position Figure 1 A front view of the cross-section of a capacitive sensor.

[0028] Figure 4 This is a cross-sectional side view of the assembled capacitive sensor.

[0029] Figure 5 This is a perspective view of the spring retainer of this utility model.

[0030] Figure 6 This is an enlarged perspective view of the connection between the external connector and the housing that houses the substrate on the capacitive sensor.

[0031] Figure 7 Showing a perspective view of the shell without a substrate.

[0032] Figure 8 Showing a top view of the shell, in which the longitudinal ribs are visible.

[0033] Figure 9 Showing a bottom view of the external connector.

[0034] Figure 10 This is a cross-sectional detail of the bottom of the assembled component. Detailed Implementation

[0035] The subject of this invention relates to a capacitive sensor, which is used, for example, as a gauge for measuring the liquid level in a container or tank, without excluding other possible applications.

[0036] The disclosed capacitive sensor includes a substrate (1) formed of a multilayer laminated material, which incorporates electronic components capable of detecting the capacitance between electrodes based on a medium (such as air or a liquid whose level is to be measured) in which electrodes (not shown) are located.

[0037] The substrate (1) is arranged inside the cover (2) and is electrically connected to the terminal (5) of the external connector (3) by means of a connecting spring (4). The external connector (3) is attached as a closure cap to the interface of the cover (2). A lateral centering device is included for laterally centering the substrate 1 relative to the cover 2 by means of a formation at the bottom of the cover 2 corresponding to a formation at the free end of the substrate 1, which causes the substrate 1 to be laterally centered in the cover 2 when inserted. The formation at the bottom of the cover 2 has a V-shaped structure corresponding to the V-shaped structure of the substrate 1, which establishes a centering fit in the final assembled position.

[0038] Specifically, according to this utility model, before assembly, if... Figure 1 As seen in the image, the connecting spring (4) for electrically connecting the substrate (1) and the external connector (3) is arranged via a spring retainer (6). For example, it can be seen that... Figure 5As seen in the image, the spring retainer (6) longitudinally defines a cylindrical housing (6.4) in which the spring (4) is included, such that, for assembling the capacitive sensor, the spring (4) is positioned through the spring retainer (6), with one end contacting a metallized surface on the edge of the substrate (1) and the other end protruding relative to the spring retainer (6) so that when the external connector (3) is placed in the coupling assembly on the interface of the cover (2), it is compressed by pushing the external connector (3), so that the spring (4) is thus longitudinally compressed inside the spring retainer (6) without warping or misalignment, pressing with the necessary force against the terminals (5) of the external connector (3) to establish good electrical contact.

[0039] For assembling the connecting spring (4), the spring retainer (6) has a flexible pin (6.2) with a protrusion (6.3) at its distal end, while the substrate (1) has recesses (1.1, 1.2) at two different distances from the end of the substrate (1) in the end region. For assembling the connecting spring (4), the spring retainer (6) is first positioned by engaging the protrusion (6.3) of its side flexible pin (6.2) into the recess (1.1) closest to the end of the substrate (1), in which the spring (4) is attached to the substrate (1) by the spring retainer (6), reaching a first pre-assembly position, as can be... Figure 2 As seen in the image. When the external connector (3) is engaged, it compresses the spring (4) on the inside of the spring retainer (6) and simultaneously pushes the spring retainer (6), causing the protrusion (6.3) of its flexible pin (6.2) to interlock in the recess (1.2) furthest from the end of the substrate (1), pushing the external connector (3) into the locked position, and as... Figure 3 As shown, the spring retainer (6) is secured in the final assembly position. This facilitates the process of assembling the spring (4) in the correct position without warping, allowing the substrate (1) to remain in a floating position inside the housing (2), which allows for the absorption of expansion without warping the substrate (1).

[0040] In order to position the spring (4) more precisely in contact with the substrate (1), the end of the substrate (1) includes angled protrusions (1.4) on its edge, into which the spring (4) fits, and for better electrical contact, the end of the substrate (1) includes a metallized edge.

[0041] To ensure closure between the external connector (3) and the housing (2), the external connector (3) includes openings (3.1) distributed along its periphery, preferably evenly spaced. The housing (2) then includes flanges (2.1) in the form of protrusions corresponding to the openings (3.1), establishing a snap-fit ​​engagement between these flanges, which ensures the external connector (3) is held relative to the housing (2) in the longitudinal direction of assembly in the connection between the two. This is a practical exemplary embodiment of the closure; however, the flanges (2.1) may not be prominently visible on the external connector (3) and the housing (2) without altering the concept of holding the external connector (3) assembled on the housing (2), such as... Figure 6 As shown in the image.

[0042] According to the actual embodiment shown in the figure, the connector (3) also has two recesses (3.2) (preferably opposite in diameter) on the inner surface of the outer edge of the connector (3), which interact with protrusions (2.2) having a geometry corresponding to the recesses (3.2). Therefore, when the connector (3) is fitted onto the housing (2), the flanges (2.1) engage with the openings (3.1) to prevent relative longitudinal movement, and simultaneously, by engaging the protrusions (2.2) with the recesses (3.2), an anti-rotation device is formed to prevent angular displacement between the connector and the housing. Preferably, the recesses (3.2) will have different sizes or geometries such that there is only one fastening position between the connector (3) and the housing (2), which ensures proper contact between the substrate (1) and the terminal (5).

[0043] According to a practical embodiment, in order to maintain the position of the substrate (1) with constant dielectric separation (because the proper function of the capacitive sensor depends on it) inside the cover (2), the substrate (1) has a formation (1.3) at its end facing the bottom of the cover (2) that fits into a corresponding formation (2.3) formed at the bottom of the cover (2). For example, it can be... Figure 3 and Figure 4 What we see in and in Figure 10 As seen in more detail, the end formation (1.3) of the substrate (1) consists of two recesses that form an inverted V-shaped, centered central protrusion, while the bottom formation (2.3) of the shell (2) consists of two protrusions that form a V-shaped notch corresponding to the central protrusion of the substrate (1). Therefore, during the assembly process, when the substrate (1) is inserted into the shell (2), the corresponding formations (1.3, 2.3) guide the substrate (1) into a centered position, leaving a gap between the side edges of the substrate (1) and the shell (2). In this way, a retaining mechanism is established to prevent lateral displacement of the substrate (1) and to keep it centered, so as to maintain it in a spaced position relative to the cover (2).

[0044] If available Figure 4 As seen in the image, the cover (2) defines the widened portion (9), and the electronic components of the substrate (1) are housed in the widened portion (9).

[0045] Furthermore, according to the preferred embodiment shown in the figure, the shell (2) includes longitudinal ribs (2.4) after the aforementioned widened portion (9) of the shell (2) (in other words, on the inner side of the shell (2) opposite to the sensitive surface of the sensor), and preferably two longitudinal ribs (2.4). The longitudinal ribs (2.4) have an initially angled geometry to guide the substrate (1) during insertion into the shell (2). Therefore, as can be seen... Figure 7 As seen in the image, the shell has a guide groove (2.5) that positions the substrate (1) for its proper insertion, and subsequently, by means of a... Figure 8 The longitudinal ribs seen in the image show that the substrate (1) is oriented transversely to the shell (2) so that the measuring electrode contacts the shell (2) in order to minimize the air between the shell (2) and the electrode, which may affect the measurement accuracy.

[0046] If available Figure 9 As seen in the preferred embodiment, the external connector (3) includes an inclined flange (3.3) on its lower portion, which facilitates the mating of the substrate (1) for its retention.

[0047] By preventing warping of the substrate (1) and minimizing air gaps between the sensor surface and the housing, each of the aforementioned features provides greater robustness to the sensor assembly (once assembled) and contributes to improved measurement accuracy.

[0048] In addition, to ensure the sealing of the assembled capacitive sensor assembly, a first sealing gasket (7) exists between the external connector (3) and the housing (2) housing the substrate (1). This sealing gasket protects the interior from external elements, such as... Figure 3 and Figure 4 As shown, for the capacitive sensor sealed within the application component, a second sealing gasket (8) is present around the housing (2) in the connection area of ​​the application component. Furthermore, for assembling the housing onto the can it is intended for, the housing (2) includes flaps (2.6) that allow bayonet mounting corresponding to the geometry of the can's component openings. The connector (3) also has flaps (3.4) that engage during bayonet rotation assembly to secure its position. A first sealing gasket 7 is arranged in the connection between the external connector 3 and the housing 2. A second sealing gasket 8 is arranged around the housing 2 in the connection area of ​​the application component.

Claims

1. A capacitive sensor comprising a substrate (1) housed in a cover (2), the substrate (1) being electrically connected by means of a spring (4) to a terminal (5) of an external connector (3), characterized in that, A connecting spring (4) for connecting the substrate (1) to the terminal (5) is arranged in a spring retainer (6), the spring retainer (6) establishing a guided connection with the substrate (1), and the spring retainer (6) having a fastening device that establishes a first interlock with the connecting spring (4) in the substrate (1) in a pre-assembled position, and establishes a second interlock with the connecting spring (4) compressed inside the spring retainer (6) by pushing the external connector (3) to close it on the cover (2) in the final operational fastening position.

2. The capacitive sensor according to claim 1, characterized in that, The connection guide on the substrate (1) is established by means of a groove (6.1) of the spring retainer (6) that corresponds to the geometry of the substrate (1).

3. The capacitive sensor according to claim 1, characterized in that, The fastening device is at least one flexible pin (6.2) of the spring retainer (6), the at least one flexible pin (6.2) including a protrusion at the distal end, and the substrate (1) having a recess at at least one of its sides at two different distances from the end of the substrate (1) and having a geometry corresponding to the protrusion, such that in order to be fastened in the pre-assembled position, the flexible pin (6.2) engages in the recess closest to the end of the substrate (1), and in order to be fastened in the final position, the connector (3) is pressed until it is closed, such that the protrusion engages in the recess furthest from the end of the substrate (1).

4. The capacitive sensor according to any one of claims 1 to 3, characterized in that, To close the external connector (3) and the housing (2), the external connector (3) includes at least two openings (3.1) that are substantially opposite in diameter, and the housing includes at least one protruding flange (2.1) opposite to each opening (3.1), by means of the at least one protruding flange (2.1) to establish an assembly retention fit between the external connector (3) and the housing (2).

5. The capacitive sensor according to any one of claims 1 to 3, characterized in that, The external connector (3) includes at least one recess / protrusion on the inner surface of the outer edge of the external connector (3), which interacts with a reciprocating protrusion / recess on the outer surface of the cover (2) to serve as an anti-rotation retaining fit for the assembly.

6. The capacitive sensor according to any one of claims 1 to 3, characterized in that, It includes a lateral centering device for laterally centering the substrate (1) relative to the shell (2) by means of a formation at the bottom of the shell (2) corresponding to a formation at the free end of the substrate (1), which causes the substrate (1) to be laterally centered in the shell (2) when the substrate (1) is inserted.

7. The capacitive sensor according to claim 6, characterized in that, The bottom of the shell (2) has a V-shaped structure corresponding to the V-shaped structure of the substrate (1), which establishes a centered fit in the final assembly position.

8. The capacitive sensor according to any one of claims 1 to 3, characterized in that, The shell (2) includes at least one longitudinal rib (2.4) on its inner surface, the at least one longitudinal rib (2.4) being configured to position the sensitive surface of the substrate (1) in contact with the shell (2) in the final assembly position.

9. The capacitive sensor according to any one of claims 1 to 3, characterized in that, The first sealing gasket (7) is arranged in the connection between the external connector (3) and the cover (2).

10. The capacitive sensor according to any one of claims 1 to 3, characterized in that, The second sealing gasket (8) is arranged around the cover (2) in the connection area of ​​the application component.

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