Sensor for measuring at least one electrical property of a fluid

Abstract

A sensor device (1) for measuring at least one electrical property of a fluid comprises a device body (2) having a sensing conduit (4) for the fluid, within which a sensitive element (10) for detecting at least one electrical property is arranged. The sensitive element (10) comprises a first electrode (11) and a second electrode (12) which extends partially within a tubular wall (11a) of the first electrode (11) and is spaced apart therefrom. The first electrode (11) has a through slit (14) which extends at least a portion of the tubular wall (11a) in a length direction (L) from a first longitudinal end (11b) towards a second longitudinal end (11c). The sensitive element (10) comprises a positioning element (15) of the second electrode (12) which is fixed at the through slit (14) of the tubular wall (11a) and is at least partially formed of an electrically insulating material.

Description

Technical Field

[0001] This invention generally relates to sensors for measuring the amount of fluid substances, and particularly to sensors designed to measure the content or concentration of components of a fluid itself in the presence of fluid flow. The invention is preferably used for measuring the percentage of alcohol in fuels (e.g., the percentage of ethanol in gasoline). Background Technology

[0002] Sensors of the type shown are used, for example, in a specific category of vehicles defined as flexible fuel vehicles (or Fuel Flex), i.e., vehicles equipped with engines that can operate using different fuels or fuel mixtures (typically alcohol and gasoline). In such applications, the sensor (called a Flex Fuel) measures the concentration of alcohol (typically vegetable-based ethanol) in the fuel relative to the gasoline.

[0003] Gasoline and alcohol have different stoichiometric ratios. To achieve optimal combustion, the engine control unit (ECU) must therefore adjust the ignition advance angle and the amount of fuel injected based on the type of fuel present. For this purpose, the Flex Fuel sensor measures the alcohol concentration and transmits this information to the ECU, allowing the ECU to adjust operating parameters in real time. For faster and more efficient response, the Flex Fuel sensor is an inline sensor, meaning it is installed along the fuel supply line leading to the engine.

[0004] The operation of these sensors is generally based on the different properties of the liquids that make up the fuel mixture. Among the physical properties of gasoline and alcohol, the most distinguishing physical property between the two substances is the dielectric constant, or permittivity εr. The dielectric constant of gasoline (εr≈2) is significantly different from that of ethanol (εr≈24.3) and water (εr≈78.0). In fact, measuring the dielectric constant is reduced to measuring the capacitance.

[0005] Since capacitance measurements alone are insufficient to quantify the water content in ethanol (natural or as a contaminant), especially when it is conductive water, it is usually necessary to measure additional electrical quantities, particularly conductivity (or resistance, since conductivity is the reciprocal of resistance). The operating principle of this type of Flex Fuel sensor is well known in all cases and does not need to be described in detail herein.

[0006] In sensor devices of the type shown, it is known to use a sensitive element to detect one or more electrical quantities of interest, the sensitive element comprising at least two electrodes. In various known solutions, the two electrodes are arranged concentrically or coaxially, i.e., by providing a first tubular electrode and a second electrode extending inside the first electrode.

[0007] This type of solution is known, for example, from US2014 / 069187A1, in which both electrodes of the sensing element have a tubular shape, and in which the outer electrode of metallic material is configured to also obtain a conduit for fluid, which is directly exposed to the environment and equipped with a hydraulic connection element for connection in the fluid channel line.

[0008] Known solutions of this type have generally proven to be complex in terms of device assembly. Further complexity arises from the need to adequately insulate the two electrodes from each other and to counteract potential leakage of the detected fluid toward the electronic control section of the sensor device. The fact that the outer electrode of the sensing element forms part of a conduit for the fluid channel, which is directly exposed to the environment and configured to connect along the associated supply line, can introduce potential additional disadvantages regarding the reliability and measurement accuracy of the device. Summary of the Invention

[0009] In summary, the present invention aims to provide a sensor device of the type described at the beginning for measuring at least one electrical property of a fluid, having an improved, economical, and reliable construction, distinguished by significant simplicity of assembly. Another object of the invention is to provide a sensor device in which precise insulation is ensured between two electrodes arranged at least partially coaxially, as well as precise insulation or protection of these electrodes from the external environment. Yet another object of the invention is to obtain a sensor device in which the risk of leakage of the measured fluid toward the corresponding electronic control components is reduced.

[0010] According to the invention, one or more of the above-mentioned objectives are achieved by a sensor device for measuring at least one electrical property of a fluid and by a method for producing a sensor device for measuring at least one electrical property of a fluid, the sensor device and the method having the features indicated in the appended claims. The claims form part of the technical teachings provided herein in conjunction with the invention. Attached Figure Description

[0011] Further features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings, which are provided by way of non-limiting example only, in which:

[0012] - Figure 1 This is a schematic perspective view of a sensor device according to a possible embodiment of the present invention;

[0013] - Figure 2 and Figure 3 This is a schematic perspective view of a partial cross-section of a sensor device according to a possible embodiment of the present invention;

[0014] - Figure 4This is a schematic perspective view showing a partial cross-section of the sensitive element of a sensor device according to a possible embodiment of the present invention;

[0015] - Figure 5 and Figure 6 yes Figure 3 Schematic perspective views of the external electrodes of the sensitive element from different angles, including the corresponding electrical connection elements;

[0016] - Figure 7 and Figure 8 yes Figure 3 A schematic perspective view of the internal electrodes of the sensitive element from different angles, including the associated positioning element;

[0017] - Figure 9 and Figure 10 Through assembly Figures 5-6 and Figures 7-8 The schematic perspective view of the sensitive element obtained from the component shown from different angles;

[0018] - Figure 11 and Figure 12 These are schematic diagrams of the sensor body of a sensor device according to a possible embodiment of the present invention, showing a perspective view and a top view, integrating... Figures 9-10 Sensitive elements of the type shown;

[0019] - Figure 13 and Figure 14 yes Figures 11-12 The schematic diagrams of the main body of the sensor are a perspective view and a top view, with other components added.

[0020] - Figure 15 and Figure 16 yes Figures 13-14 The schematic diagrams of the main body of the sensor are a perspective view and a top view, with other components added.

[0021] - Figure 17 , Figure 18 and Figure 19 These are schematic perspective views of two parts of the mold in their respective open positions, illustrating how the mold can be used to... under three different corresponding conditions. Figures 11-12 The main body of the device of the type shown is formed by injection molding. Figures 9-10 Sensitive elements of the type shown;

[0022] - Figure 20 yes Figures 17-19 A schematic cross-sectional view of two mold parts in their respective closed positions;

[0023] - Figure 21 and Figure 22 It is based on relative to Figures 7-8The schematic cross-sectional views of the inner electrode and corresponding positioning element in the possible variations of the embodiment are exploded views and assembled together;

[0024] - Figure 23 Another possible variant embodiment is with Figure 22 A schematic cross-sectional view similar to the schematic cross-sectional view;

[0025] - Figure 24 This is a schematic partial cross-sectional view of a sensor device according to a possible variant embodiment of the present invention; and

[0026] - Figure 25 This is a schematic cross-sectional view of a sensor device according to another possible variant embodiment of the present invention. Detailed Implementation

[0027] References to "embodiment" in this specification indicate that a particular configuration, structure, or feature described with respect to that embodiment is included in at least one embodiment. Therefore, phrases such as "in one embodiment," "in various embodiments," etc., which may appear in different places throughout this specification, do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, a particular configuration, structure, or feature described or illustrated may be combined in any suitable manner, even if it differs from what is depicted. Certain configurations, structures, or features described or illustrated by reference to "one embodiment" or "in various embodiments" may be at least partially present or absent in other embodiments.

[0028] The reference numerals used herein are for convenience only and therefore do not limit the scope of protection or the scope of embodiments. Spatial references (such as "upper", "lower", "top", "bottom", etc.) used herein are for convenience only and refer to the examples shown in the figures.

[0029] exist Figures 1-3 In the figures, reference numeral 1 indicates a sensor device according to the invention. Hereinafter, it is assumed that sensor 1 is a sensor configured to detect characteristics of a fuel or fuel mixture, such as a Flex Fuel sensor, designed to detect the concentration of alcohol (particularly ethanol) in the fuel relative to gasoline.

[0030] The device has a device body 2, which includes a body portion 3 defining at least one detection conduit 4 (preferably a conduit with a circular cross-section). The body portion 3 is preferably made of an electrically insulating polymer or plastic material. Preferably, the device body 2 also has at least one cavity 5 for accommodating a circuit arrangement, in this example, including a circuit support or PCB 6 on which electrical / electronic components for connection and / or control of the device 1 are mounted. In a preferred embodiment, the body portion 3 is shaped to define the conduit 4 and the cavity 5 in a single workpiece (or a generally box-shaped body portion, indicated by 3', defining the cavity).

[0031] In an alternative embodiment, the body portion 3 may include at least two parts made of polymer and welded or fixed together, such as a first part shaped to define the conduit 4 as a single workpiece and a second part shaped to define the cavity 5 (i.e., body portion 3'). The device body 2 may also include a cap 7 for closing the cavity 5.

[0032] In one embodiment, the body portion 3 also integrally defines one or more flanges 3a for securing the device 1 in place. Each flange 3a may include a metal bushing 3b at one of its through openings. In this example, two flanges 3a are defined in a lateral position relative to the cavity 5, i.e., defined on opposite sides of the box-shaped portion 3' of the body portion 3.

[0033] Device 1 has an electrical connector for connection to an external unit (such as the engine control unit of a Fuel Flex vehicle). In a preferred embodiment, the connector includes a connector housing 8 that is at least partially tubular in shape, and a plurality of electrical connection terminals (in... Figures 1-3 It is not visible in the middle, but for example in Figures 11-18 One end portion (indicated by 8a) extends inside the connector housing, while the other end portion extends inside the cavity 5 for electrical connection to the circuit carried by the circuit support 6.

[0034] In one possible embodiment, the body portion 3 is shaped to define at least the conduit 4 and the box-shaped portion 3' defining the cavity 5 as a single workpiece. In another possible embodiment, the body portion 3 is shaped to define at least the conduit 4 and the connector housing 8 as a single workpiece. In a preferred embodiment, the body portion 3 is shaped to define the conduit 4, the box-shaped portion 3' defining the cavity 5, and the connector housing 8 as a single workpiece.

[0035] The detection catheter 4 extends axially along the corresponding axis A. Figures 2-3It has an inlet 4a and an outlet 4b (or an inlet 4b and an outlet 4a) so that fluid can flow therein. Therefore, preferably, the sensor device 1 is inline, that is, it is configured to be directly installed in the supply line of the fluid to be detected (preferably a line for supplying fuel to the engine).

[0036] For this purpose, preferably, the detection conduit 4 is shaped to integrally define connecting or fixing elements in its outer portion, particularly corresponding connecting elements for the hydraulic circuit it serves; these connecting or fixing elements indicated by 4c are preferably obtained in the form of protrusions or flanges projecting radially from the conduit 4.

[0037] In various embodiments, each connecting element 4c obtains a fixing device and / or coupling device for a corresponding female hydraulic connector (not shown) for the fluid delivery line; in this case, the end portion of the conduit 4 provided with the corresponding connecting element 4c (indicated by 4d) essentially obtains the corresponding male hydraulic connector. Figure 1 and Figure 3 The HC is used to represent (see also HC) Figure 25 Therefore, in various preferred embodiments, these hydraulic end connectors HC of the conduit 4 are made entirely of polymer, i.e., they consist of a single workpiece comprising an annular protrusion or flange 4c and a corresponding end segment 4d of the conduit 4, both of which are made of polymer. Thus, the hydraulic connectors HC can be easily and cost-effectively and advantageously integrated into the detection conduit 4 made of polymer material.

[0038] At the two opposite end portions 4d of the conduit 4, i.e., at the hydraulic connectors HC corresponding to the inlet 4a and outlet 4b, the outlet end of the first pipe and the inlet end of the second pipe can be connected respectively, or corresponding female hydraulic connectors can be connected respectively to allow fluid (here, fuel supplied to the engine) to flow through. When secured by a pipe without a female hydraulic connector, the flange 4c can in any case define the maximum engagement position of the corresponding portion of the end of the respective pipe on the corresponding portion of the end portion 4d of the conduit 4.

[0039] According to an important aspect, a sensitive element is provided inside the detection conduit for detecting at least one electrical property of the fluid.

[0040] In the following text, it is assumed that device 1 is configured to detect at least one of the capacitance (representing dielectric constant) and resistance of the fluid, preferably both of which are electrical quantities as explained in the introduction.

[0041] exist Figures 2-4The sensitive element represented by 10 includes at least one first electrode 11 and a second electrode 12, the second electrode 12 extending at least partially within the first electrode 11.

[0042] For example, especially from Figure 4 As can be seen, the first electrode 11 (also defined hereinafter as the outer electrode for simplicity) extends along the corresponding length direction L and preferably has a substantially tubular wall 11a with a first longitudinal end 11b and a second longitudinal end 11c opposite each other. The two ends 11b and 11c of the tubular wall 11a are open to allow fluid to pass through the electrode 11. As mentioned, the wall 11a has a substantially tubular shape and preferably has a circular cross-section, i.e., the wall preferably has a substantially cylindrical shape; however, the outer electrode 11 and / or its wall 11a may have other shapes suitable for this purpose.

[0043] The second electrode 12 (hereinafter also referred to as the inner electrode for simplicity) is shaped such that at least a portion thereof extends within the tubular wall 11a along the same length direction L as the outer electrode 11, at a distance from the tubular wall. In a preferred embodiment, the inner electrode 12 is formed as a single body or an integral body, which is bent to define different portions, for example, as described below.

[0044] In a preferred embodiment, the electrode 12 is substantially filamentous (wire-like) and preferably has a circular cross-section, i.e., a substantially cylindrical shape; however, the inner electrode 12 may have other shapes or cross-sections suitable for this purpose.

[0045] In a preferred embodiment, at least a portion of electrodes 11 and 12 are arranged concentrically with respect to each other, i.e., coaxially. For example, see reference... Figures 3-4 At least one detection portion (identified as 12a) of electrode 11 and electrode 12 may be coaxial with each other and with respect to catheter 4, sharing its axis A.

[0046] In various embodiments, the external electrode includes an electrical connection element or portion. Figure 4 In the accompanying drawings, reference numeral 13 denotes an electrical connection element that is in electrical contact with at least one region of the outer surface of the tubular wall 11a, for example. Element 13 is also preferably filamentous. Element 13 can be substantially shaped or bent into an L-shape, as in the example shown, where 13a and 13b denote the base portion and upright portion of element 13, respectively (see also...). Figures 2-3), wherein portion 13b is essentially the portion for electrical connection to the circuit support 6. Element 13 is preferably shaped to contact at least two regions of the outer surface of the tubular wall 11a. As will be shown later, element 13 (e.g., welded to the tubular wall 11a) allows the external electrode 11 to be connected to a circuit arrangement disposed on the circuit support 6.

[0047] The two electrodes 11 and 12 are formed of conductive material, but it is not excluded that one or both electrodes may be formed of conductively treated insulating material (e.g., conductive polymer). The inner surface of the tubular wall 11a formed of insulating polymer and / or the outer surface of the electrode 12 formed of insulating polymer may also be covered with a layer of conductive material. In such cases, an electrical connection element technically equivalent to element 13 may be made as a single workpiece with the outer electrode 11 and is also coated with a layer of conductive material, contacting the conductive layer covering the interior of the tubular wall.

[0048] In a preferred embodiment, electrodes 12 and 11, and their connecting element 13, are formed of a metallic material. The preferred material is AISI (stainless steel). In the case of AISI steel, the inner electrode 12 may be surface-treated with nickel, while the outer electrode 11 may not be surface-treated. The connecting element 13 may also be made of stainless steel, preferably surface-treated with nickel.

[0049] As mentioned, the outer electrode 11 (i.e., its tubular wall 11a) is preferably cylindrical, while the inner electrode 12 is preferably formed as a wire with a circular cross-section. The element 13 may also be a filament with a circular cross-section, for example, having the same diameter as the filamentary body of the electrode 12.

[0050] For example, electrode 11 may have an outer diameter between 6 and 10 mm (e.g., 8.6 mm) and an inner diameter between 4 and 8 mm (e.g., 6 mm); electrode 12 may have an outer diameter between 1 and 3 mm (e.g., 1.6 mm). Again, for example, electrode 11 (i.e., its tubular wall 11a) may be 20 to 24 mm long, for example, 22 mm. A portion of electrode 12 extending coaxially with respect to the outer electrode 11 (i.e., Figure 4 The detection portion (marked as 12a) may be slightly shorter in length than the tubular wall 11a, preferably between 18 and 22 mm, for example, 19 mm. Again, for example, the conduit 4 may have an inner diameter that is slightly smaller than the outer diameter of the tubular wall 11a and slightly larger than the inner diameter of the tubular wall 11a, preferably between 5 and 9 mm, for example, 7.05 mm.

[0051] In any case, from Figure 2 and Figure 3It can be seen that, preferably, the length of the outer electrode 11 is equal to a portion of the length of the conduit 4, the outer electrode 11 is positioned in the middle region of the conduit 4, and the detection portion 12a of the inner electrode 12 is substantially centered in the length direction L relative to the two ends 11b, 11c of the tubular wall.

[0052] Figure 5 and Figure 6 Only the outer electrode 11 and its connecting element 13 are shown. As can be seen in these figures, according to an important aspect, the electrode 11 has a through slit or through groove 14 that extends at least a portion of the length of the tubular wall 11a from a first longitudinal end 11a toward a second longitudinal end 11b. In this example, the bottom 14a of the slit 14 (opposite to the end 11b of the tubular wall 11a) has a generally curved or circular profile, although this is not a necessary feature.

[0053] According to another important aspect, a positioning element for the inner electrode is fixedly attached at the aforementioned through slot or through groove, the positioning element being configured to support the inner electrode in its working position. For example, in Figure 4 In the above example of positioning element, the whole is represented by 15.

[0054] The positioning element 15 functions to support the electrode 12, allowing it to be assembled on the electrode 11 in a substantially predetermined position under electrically insulating conditions; for this purpose, the element 15 is at least partially formed of an electrically insulating material.

[0055] The positioning element 15 is fixed to the outer electrode 11 or to the tubular wall 11a of the outer electrode, and is in a fixed position.

[0056] In a preferred embodiment, the electrically insulating material of element 15 is overmolded onto the inner electrode 12, which has been pre-formed for this purpose, for example, as in... Figure 7 and Figure 8 As can be seen, for this purpose, the body of a pre-formed electrode 12 is inserted into a mold having a cavity or hollow space suitable for receiving the electrode 12 and defining the outer contour of the element 15. After the mold is closed, an electrically insulating plastic material for positioning the element 15 is introduced into the mold in a fluid state, and after the aforementioned plastic material has cured, the electrode 12 (including the element 15) can be removed from the mold. In this way, at least the connecting portion of the electrode 12 is surrounded by the electrically insulating material of the element 15, particularly embedded in the electrically insulating material (as will be seen, in other possible embodiments, the body of the element 15 is mounted on the body of the electrode 12, in any case at least partially surrounding its connecting portion, even in the absence of overmolding).

[0057] Then, the inner electrode 12, equipped with the positioning element 15, is connected to the outer electrode 11, specifically by engaging the element 15 inside a slit 14 defined in the tubular wall 11a of the electrode 11. This can be achieved, for example, by pushing the element 15 into the slit 14 from above, or by laterally pushing the element 15 into the slit 14 from its open end. The result of this connection is, for example, in… Figure 9 and Figure 10 As you can see.

[0058] Preferably, the positioning element 15 is received in the through slit 14, thereby substantially completely occupying the through slit; this is advantageous, as in a preferred embodiment of the invention, when a portion of the defining detection conduit 4 of the body of the device is overmolded onto the sensing element 10.

[0059] The main body of the positioning element 15 and the forming body of the inner electrode 12 are configured such that, in the connection position between the element 15 and the through slit 14, the detection portion 12a of the electrode 12 is in the correct position within the tubular wall 11a, substantially coaxial with the tubular wall.

[0060] Regardless of the specific shape, and especially as Figure 4 As can be seen, in the preferred embodiment, the body of the inner electrode 12 is bent into defining a plurality of portions, including at least:

[0061] a. The aforementioned detection portion 12a extends substantially along the length direction L, at least partially, inside the electrode 11.

[0062] b. An electrical connection portion 12b, which preferably extends at least partially outside the electrode 11 in a transverse direction relative to the length direction L, and

[0063] c. A connecting portion 12c having a supporting and / or positioning function, which is at least partially surrounded by the electrically insulating material of element 15, wherein, in the assembled state, the connecting portion 12c is preferably in a position substantially corresponding to the position of the through slit 14.

[0064] In one or more embodiments, the filamentary body of the inner electrode 12 has multiple bends or curved portions. In the specific example depicted, three portions are provided that are substantially bent at 90°. Figure 4 The numbers are represented by 12', 12'', and 12'''.

[0065] In various embodiments, such as those illustrated in the accompanying drawings, the filamentary body of the inner electrode 12 is bent such that the electrical connection portion 12b or at least a portion thereof is substantially orthogonal to or transverse to the detection portion 12a or at least a portion thereof.

[0066] In various embodiments, such as those illustrated in the accompanying drawings, the filamentary body of the inner electrode 12 is bent such that the electrical connection portion 12b or at least a portion thereof is substantially orthogonal to or transverse to the connection portion 12c or at least a portion thereof.

[0067] In various embodiments, such as those illustrated in the accompanying drawings, the filamentary body of the inner electrode 12 is bent such that at least a portion of the connecting portion 12c is arranged substantially parallel or side-by-side with respect to at least a portion of the detection portion 12a.

[0068] In a preferred embodiment, the fact that the connecting portion 12c, or at least a portion thereof, extends substantially along the length direction of the outer electrode 11 can help maintain coaxiality between the detection portions 12a of the same outer electrode and inner electrode 12; this may be particularly useful when the electrode 11 and element 15 are assembled parts, such as in Figures 21-22 In the case of a variant embodiment.

[0069] However, it should be noted that the connection portion of the sensitive element may have a shape different from that shown, or may be obtained by utilizing a portion of a different part of the internal electrode: for example, in the case where the internal electrode has a substantially L-shaped shape (as in...). Figure 23 and Figure 25 In a variant embodiment, the connection portion can be obtained by a section of the electrical connection portion 12b passing through the positioning element 15.

[0070] In the example, and with reference Figure 4 A portion of the filamentary body of electrode 12 is bent in a substantially U-shape, thereby defining at least a portion of the detection portion 12a and the connecting portion 12c, which are substantially side-by-side or parallel to each other and connected by an intermediate portion 12c', which may be at least partially bent, wherein the bent portion 12' connects the detection portion 12a to one end of the intermediate portion 12c' and the bent portion 12'' connects the other end of the intermediate portion 12c' to the connecting portion 12c; however, the detection portion 12a and the connecting portion 12c may be connected in another way, for example by means of the U-shaped bent intermediate portion, or they may be folded in a V-shape without having a substantial intermediate portion.

[0071] The bend 12'' itself can be considered as part of the connecting portion 12c because it is partially embedded (or inserted, in possible variant embodiments discussed below) into the body of the positioning element 15; the same applies to the bend 12''', which is here fully embedded into the body of the element 15 (but may also be inserted therein, in possible variant embodiments discussed below).

[0072] Referring again to the illustrative case, another portion of the filamentary body of electrode 12 is bent at an angle (generally 90° here) relative to the connecting portion 12c to obtain an electrical connection portion 12b having a bend 12''' connecting the two portions 12c and 12b. The initial segment of the electrical connection portion 12b (immediately downstream of the bend 12''') can also be considered as part of the connecting portion 12c, as it is partially embedded (or inserted, in possible variant embodiments) into the body of the positioning element 15; the same applies to the bend 12'', which is here fully embedded (or inserted, in possible variant embodiments) into the body of the element 15.

[0073] Generally, it is preferred that the connecting element 13 of the outer electrode 11 has a body shaped such that at least a portion of its electrical connection portion 13b extends substantially parallel to at least a portion of the electrical connection portion 12b of the body of the inner electrode 11. As will be seen below, this is advantageous for the assembly and electrical connection of the sensing element 10 with the circuit support 6.

[0074] Considering the simple and cost-effective construction, all parts of the filamentary body of electrode 12 and / or connecting element 13 have the same size and / or cross-section, preferably circular in shape, with a diameter between 1 mm and 2 mm (preferably 1.6 mm); for the reasons explained below, this size also allows the inner electrode 12 to have greater mechanical stability and / or the heat of the fluid to be easily transferred to the control circuit.

[0075] However, the aforementioned portions and / or bends of the filamentary bodies of the electrodes 12 and / or connecting elements 13 may have at least slightly different shapes or sizes, for example, by wear or partial deformation of the length of the constitutive filaments (e.g., a narrowing or shaped form of at least one of the electrical connection portions 12b and / or 13b in the final length to facilitate brazing or fixing to the circuit support 6).

[0076] For the purpose of measuring the electrical properties of interest of the fluid, the sensing element 10 is encapsulated in a body made of a non-conductive material (here represented by the plastic or polymeric material of the detection conduit 4). For this purpose, in a preferred embodiment, at least a portion of the device body defining the detection conduit is overmolded to the sensing element.

[0077] The aforementioned main body (which in this example also defines the cavity 5 (or the portion 3' defining the cavity) and the connector housing 8) essentially functions to deliver the fluid of interest and allow it to pass through the sensing element 10, while allowing the sensor device 1 to be easily inserted into the loop in which the fluid flows (particularly via the connector HC), ensuring the fixation of the concentric electrodes 11, 12 assembled together by means of the positioning element 15, and electrically insulating the two electrodes 11, 12 from each other.

[0078] At least the main body of the detection catheter, in Example 3, is preferably made of a plastic material by means of an injection molding process, wherein, in particular, the plastic material is overmolded onto the sensing element 10. Overmolding allows the sensing element 10 to be integrated into the plastic material that at least forms the sensing catheter 4, and the sensing element 10 is completely contained within the catheter and thus exposed only to the fluid being detected. For example, as in Figure 2 and Figure 3 As can be clearly seen, the overmolded material of the opposite end portion 4d of the catheter extends beyond the two longitudinal ends of the sensing element 10.

[0079] In the example where the main body 3 defines the connector housing 8 and the fixing flange 3a, the overmolding allows the metal bushing 3b and the electrical terminals (in) to be bonded together. Figures 11-18 It is advantageous to integrate (as indicated by 8a) into the same main body 3 for external electrical connection of device 1.

[0080] A possible method for manufacturing a sensor device 1, the sensor device having a device body including a detection conduit made of an electrically insulating material, the method comprising the following steps:

[0081] i) Provide an external electrode (11) having a substantially tubular wall (11a), to which an electrical connection element (13) is preferably connected.

[0082] ii) Provide an internal electrode (12) comprising at least one detection portion (12a) and an electrical connection portion (12b).

[0083] iii) By connecting the inner electrode (12) to the outer electrode (11), preferably by means of a positioning element (15), the sensitive element (10) of the sensor device (1) is provided, such that

[0084] The aforementioned detection portion (12a) extends at least partially and substantially along the length direction (L) of the outer electrode (11), is located inside and spaced apart from the substantially tubular wall (11a) of the outer electrode.

[0085] The aforementioned electrical connection portion (12b) extends at least partially outside the outer electrode (11), particularly laterally relative to the length direction (L) of the outer electrode (11), and

[0086] iv) The sensitive element (10) is constrained within the detection conduit (4) of the main body (2) of the device (1).

[0087] Step iii) as indicated above preferably includes the operation of fixing the positioning element (15) to the inner electrode (12) and the operation of connecting the positioning element (15) to the outer electrode (11), the positioning element being at least partially formed of an electrically insulating material and configured to support the inner electrode (12).

[0088] Preferably, the positioning element (15) is molded on the connecting portion (12c) of the inner electrode (12), which is substantially located between the corresponding detection portion (12a) and the electrical connection portion (12cb).

[0089] Step iv) as indicated above preferably includes the operation of a portion (3) of the body (2) of the molding device (1), which at least defines a detection conduit (4) on the sensitive element (10).

[0090] In a specific case of the example of the preferred embodiment shown in the figure:

[0091] - Step i) includes the operation of pre-defining a longitudinal through slit or through groove (14) in the tubular wall (11a) of the outer electrode (11);

[0092] - Step ii) includes the following operation: bending the body of the inner electrode (12) to present the detection part (12a), the electrical connection part (12b) and the connection part (12c).

[0093] - Step iii) includes the following operation: fixing the positioning element (15) in a through slit or through groove (14) of the substantially tubular wall (11a) of the outer electrode (11) such that the connecting portion (12c) is at least partially surrounded by the electrically insulating material of the positioning element (15) at the through slit (14) of the tubular wall (11a) of the outer electrode (11).

[0094] More generally, a possible method for producing a sensor device (1) having a device body overmolded to define at least one detection conduit made of an electrically insulating material, the method comprising the following steps:

[0095] a) Provide an external electrode (11) comprising a substantially tubular wall (11a) extending along the length direction (L) and having a corresponding electrical connection portion (13b).

[0096] b) Provide an internal electrode (12) comprising a detection portion (12a) extending at least partially substantially along the length direction (L), the internal electrode (12) having a corresponding electrical connection portion (12b).

[0097] c) The sensitive element (10) of the sensor device (1) is obtained by connecting the outer electrode (11) and the inner electrode (12), wherein the inner electrode (12) extends at least partially within the outer electrode (11) and is electrically insulated from the outer electrode.

[0098] d) The body (2) of the device (1) is obtained by overmolding the sensing element (10) with an electrically insulating polymer or plastic material, the body defining at least one sensing conduit (4) in which the sensing element (10) is integrated.

[0099] Preferably, step d) indicated above includes the following operation: overmolding an electrically insulating polymer or plastic material to integrally define a connecting element or fixing element (4c) on the outside of the detection conduit (4), in particular in the form of a radially projecting flange for connecting the detection conduit (4) to a pipeline along the fluid channel.

[0100] exist Figure 11 and Figure 12 In a non-limiting example, the main body portion 3 is visible, which integrates the portion 3' defining the cavity 5, the conduit 4, the flange 3a, and the connector housing 8, and is molded on the sensitive element 10 (including the connecting element 13). As can be seen, the terminals 8a, the bushing 3b, and the sensitive element are partially integrated or embedded in the electrical insulating material forming the main body portion 3, wherein only the terminal lengths of the portion 12b of the inner electrode 12 and the terminal lengths of the portion 13b of the connecting element 13 of the outer electrode 11 are visible.

[0101] As will be seen, the cavity 5 preferably has a bottom through which the corresponding portions 13b of the electrical connection element 13 and 12b of the inner electrode 12 extend. In this perspective view, from Figure 11 and Figure 12 It can be seen that, preferably, the substantially cylindrical forming structures 3c and 3d rise from the bottom of the cavity 5, and the corresponding portions of the connecting portion 12b of the inner electrode 12 and the connecting portion 13b of the connecting element 13 extend axially in each of the forming structures; these bushing-like forming structures (in Figures 2-3 The part that is also visible and has a larger diameter than the aforementioned connecting portions 12b and 13b functions to accommodate at least one sealing element associated with the aforementioned electrical connecting portions 12b and 13b, as will be explained below. Figure 11 and Figure 12It can also be seen that within the cavity 5, one or more support elements 3e and / or one or more positioning elements 3f for the circuit support 5 can be integrally defined.

[0102] Figure 13 and Figure 14 It further demonstrates how it is possible to Figures 11-12 The aforementioned molded structures 3c and 3d are topped with corresponding plugs 21 and 22, which are made of, for example, plastic or elastomer material, and in any case, electrically insulating material. These plugs 21 and 22 (in...) Figures 2-3 (As can also be seen in the image) Each has a central channel to allow the terminal length of the electrical connection portion 12b of electrode 12 and the terminal length of the upright portion 13b of the connecting element 13 of electrode 11 to protrude inward into the cavity 5 for the purpose of connecting to the circuit carried by the support or PCB 6.

[0103] Figure 15 and Figure 16 The circuit support 6 is further illustrated when it is inserted inside the cavity 5. The circuit support 6 has a first hole (not shown) through which a corresponding portion of the terminal 8a passes, and these portions are configured to be conductive with corresponding conductive traces or pads of the circuit disposed on the support 6 (for this purpose, the aforementioned first hole could also be a metallized hole). Similarly, the circuit support 6 has a second hole (not shown, but...). Figure 3 As can be seen in the image), the corresponding terminal segments of the inner terminal 12 portion 12b and the connecting element 13 portion 13b respectively pass through the second hole (see also see...). Figure 2 (For reference). Similarly, in this case, the aforementioned terminal sections of portions 12b and 13b are configured to be conductive with the corresponding conductive traces or pads of the circuit provided on the support 6 (for this purpose, the aforementioned second hole may be a metallized hole). As mentioned, in a preferred embodiment, the inner electrode 12 and the connecting element 13 are made of stainless steel coated with nickel on their surfaces, and this coating facilitates soldering the end sections of portions 12b and 13b to the aforementioned traces, pads, or metallized holes.

[0104] In various preferred embodiments, the operation of molding a portion (3) of the device body (2) onto the sensitive element (10) includes:

[0105] - Place the sensitive element (10) in the mold,

[0106] - The two ends (11b and 11c) of the tubular wall (11a) of the outer electrode (11) are sealed by means of the corresponding movable mold element.

[0107] - Injecting an electrically insulating plastic material in a fluid state into a mold is necessary for forming at least the portion (3) defining the detection conduit (4) of the device body (2).

[0108] - Waiting for the electrically insulating plastic material to cure, and

[0109] - Remove part (3) of the main body (2) of the device from the mold, which at least defines the detection conduit (4) integrated with the sensitive element (10).

[0110] Preferably, the aforementioned mold is configured such that connecting or fixing elements (4c), in particular radially projecting flanges, are defined on the outside of the detection conduit (4) for connecting the detection conduit (4) along the fluid channel line.

[0111] Figure 17 The illustration schematically depicts a possible mold that can be used for overmolding operations. In this example, the mold comprises two mold parts that can close one on top of the other (e.g., Figure 20 (As shown): For clarity, in Figure 17 In and below Figure 18 and Figure 19 In the image, two mold sections are shown side by side to make the sections more clearly visible.

[0112] The two mold parts are in Figure 17 The cavities 30' and 30'' are denoted by 30' and each defines a corresponding cavity 31' and 31''. When the cavities 30' and 30'' are closed on top of each other, the corresponding cavities define a mold cavity into which the plastic or polymer material required to form the main body part 3 is injected (some portions of the mold cavity may also be defined by movable mold portions described below). In general, cavity 31' can be understood as a male cavity designed to define most of the internal surface of the main body part 3 (e.g., cavity 5 and connector housing 8), while cavity 31'' can be understood as a female cavity designed to define most of the external surface of the main body part 3. The corresponding portions of cavities 31' and 31'' (e.g., in...) Figure 20 The portions indicated by 30b' and 31b' are configured for positioning the sensitive element 10, which is provided with the connecting element 13. In this specific example, other portions of the cavity 30' are configured for positioning the terminal 8a and the bushing 3b.

[0113] On the mold portion (here, portion 30'), a movable mold portion 32' is mounted, which is linearly displaceable and configured such that the corresponding forming portion 32a' seals the two open ends (11b, 11c) of the tubular wall 11a of the outer electrode 11. Figures 1-3The positioning element 15 is mounted together with the inner electrode 12 on the wall of the tubular structure. Figures 3-4 Preferably, the inner electrode 12 is also fixed in a suitable position (e.g., Figure 20 (What the lieutenant general saw).

[0114] On the same mold portion 30', another movable mold portion 33' is mounted, which is linearly displaceable and configured such that the corresponding forming portion 33a' defines the connector housing 8. Figures 1-3 The inner surface and bottom of the connector housing are designed so that terminal 8a extends through the connector housing. The die portion 30' is configured such that movable portions 32' and 33' can extend from... Figure 17 The corresponding rest position shown slides to Figure 18 The corresponding working positions are shown. Similarly, the mold portion 30'' is configured such that the movable portions 32'' and 33'' can be displaced, for example, through appropriate sliding channels 32'' and 33''.

[0115] As mentioned, in Figure 18 In the diagram, the movable portions 32' and 33' of the mold portion 30' are shown in their respective working positions, i.e., relative to... Figure 17 The position is in the forward position. Therefore, it can be noted that the shaped portion 32a' of the movable portion 32' blocks the two open ends of the tubular wall 11a of the outer electrode 11. Figures 3-4 Furthermore, the shaped portion 33a' of the movable portion 33' receives the end portion of the terminal 8a internally.

[0116] Figure 19 The result of the overmolding is shown, wherein the main body portion 3 has now been formed, and therefore the main body portion includes a defining cavity 5 ( Figures 11-16 The main body 3 consists of part 3', a conduit 4 integrating a sensitive element 10, a connector housing 8 integrating a terminal 8a, and a flange 3a integrating a bushing 3b. After the overmolded material has cured, the two mold parts 30' and 30'' can be opened, the movable parts 32' and 33' can be moved back to their initial positions, and the main body 3 can be removed.

[0117] Figure 20 This is a schematic diagram of the mold based on the vertical cutting plane located at the position corresponding to the sensitive element 10.

[0118] It can be seen how the mold portions 30' and 30'', or the corresponding cavities, have their respective forming areas 30b', 31b' for positioning and supporting the sensitive element 10 in the mold, and how the forming portion 32a' of the movable mold portion 32' can be configured within the tubular wall (11a, ...) of the sensitive element 10. Figures 3-4 The tubular walls of the sensitive element are sealed at both ends to prevent the diffusion of the encapsulated fluid material inside the walls. Figure 20 It is also shown how the aforementioned shaped portion 32a' can be advantageously configured with the inner electrode (12, Figures 3-4 ) and / or the corresponding positioning elements (15, Figures 3-4 The corresponding parts of the electrodes (11 and 12) interact to ensure that the electrodes (11 and 12) interact. Figures 3-4 The correct mutual positioning between them.

[0119] Again from Figure 20 As can be seen, in the preferred embodiment, the movable portion 32'' of the mold can conveniently define the corresponding cavity 32a'' for forming the detection conduit (4, Figures 1-3 ) has a corresponding fixed forming structure or flange (4c, Figures 1-3 The relative end portions (4d, Figures 1-3 Alternatively, it can be used to form a hydraulic connector HC. The cavity portion required to form the above-described fixed forming structure or flange is defined here between the movable portion 32' and the corresponding opposing surfaces of the forming areas 30b', 31b' for positioning and supporting the sensitive element 10.

[0120] The molded portion 32a' of the movable portion 32' is firmly pressed against the two opposing longitudinal ends of the sensing element 10, thereby isolating the interior of the tubular wall 11a from the injection cavity. The aforementioned molded portion 32a' presses against the substantially flat surfaces at the two ends 11b and 11c of the tubular wall 11a; it should be understood that on one side of the sensing element 10 (where the positioning element 15 is located), one of the molded portions 32a' will also press against the slit of the element 15 (where this end is located). Figure 10 (represented by B) on the opposite end surface.

[0121] As mentioned, during the molding of the main body 3, it is necessary to prevent the injected material from escaping from the mold cavity and diffusing inside the sensitive element 10, thereby posing a risk of blocking the space between the concentric electrodes and thus closing the channels for fluid.

[0122] For this reason, in addition to configuring the mold such that the two open ends of the sensitive element 10 are blocked during molding, it is preferable that the positioning element 15 of the inner electrode 12 is received into the through slit 14, thereby substantially completely occupying the slit.

[0123] To further reduce the risk of some injected material potentially diffusing between the positioning element 15 and the slit 14, the positioning element 15 can be advantageously shaped to have a connecting portion received in the through slit 14. Preferably, the connecting portion is provided with at least one sealing protrusion on its surface, the at least one sealing protrusion being configured to interact with the surface of the tubular wall 11a defining the through slit 14 (e.g., on the surface of the tubular wall 11a). Figures 5-6 (represented by 11d) Collaboration. Such a connection portion of element 15, for example, in... Figures 7-8 The middle part is represented by 15a.

[0124] One or more sealing protrusions may extend along the peripheral portion of the connecting portion 15a, the one or more sealing protrusions facing the surface 11d that defines the through slit 14.

[0125] In the illustrated case, the connecting portion 15a defines two sealing protrusions (in) Figures 7-8 (Represented by 15a' in the middle), these two sealing protrusions are generally parallel and extend over the entire contour of the outer electrode 11 (i.e., the portion of part 15 inserted into slit 14). In this example, protrusion 15a' essentially obtains a sealing joint with a substantially triangular profile, which, when the positioning element 15 is engaged with slit 14, interferes with surface 11d and thus deforms at the contact area.

[0126] In various embodiments, the positioning element 15 has a receiving portion having a lateral dimension larger than that of the through slit 14, for at least partial support on the exterior of the tubular wall 11a of the outer electrode 11. One of these upper receiving portions (e.g., for example, in...) Figures 7-8 The portion represented by 15b further helps to reduce the possibility that material injected into the mold may seep into the interior of the sensitive element 10.

[0127] The fact that the receiving portion 15b has a larger overall size relative to the slit 14 also has the effect of counteracting the thrust exerted on the positioning element 15 by the plastic material during the overmolding step (that is, preventing the positioning element from shifting toward the interior of the sensing element 10 under the pressure of the polymer material injected into the mold in a fluid state).

[0128] Given that the molding pressure may be relatively high, in various embodiments, the receiving portion 15b is configured to provide additional mechanical elements to counteract the thrust of material injected into the mold. In a preferred embodiment, these mechanical elements may include at least one of a pair of opposing lateral protrusions and longitudinal protrusions of the receiving portion 15b.

[0129] refer to Figure 7 and Figure 8In the example, the receiving portion 15b may have a pair of opposing protrusions 6a, each located on a corresponding longitudinal side of the portion 15b, and the lower surfaces of the pair of opposing protrusions may rest on a corresponding area of ​​the outer surface of the tubular wall 11a at the edge of the through slit 14.

[0130] Refer again Figure 7 and Figure 8 In the example, in addition to or as an alternative to the protrusion 16a, the receiving portion 15a may have a longitudinal protrusion or a front protrusion 16b, the lower surface of which may rest on the corresponding area of ​​the outer surface of the tubular wall outside the through slit 14 in the direction toward the end 11c of the tubular wall 11a.

[0131] By providing at least one upper rib, the positioning element 15 or its receiving portion 15b can be further reinforced, for example, to resist its possible bending. Again in Figures 7-8 In the example, the case of upper ribs 17a-17b extending most of the length of the accommodating portion 15b is shown.

[0132] The main body of the positioning element 15 may have an upper bushing-shaped forming structure at its receiving portion 15b, through which the corresponding length of the vertical portion of the inner electrode extends. This bushing-shaped forming structure, indicated by 18 (defined in the middle of the upper ribs 17a-17b in this example), can be used for sealing purposes.

[0133] By using a sensitive element 10 with the previously illustrated dimensions, such as Figures 7-8 Regarding the positioning element 15 shown, the applicant found that even with minimal overall contact area between the receiving portion 15b and the outer surface of the tubular wall 11a (here, the contact surface area is 0.023 ± 0.003 cm²), the overall contact area is minimized. 2 In the case of high pressure (e.g., 300 ± 50 bar), the material required for the main body 3 can also be obtained by injection without causing displacement or compression of the positioning element 15.

[0134] The sensor device 1 is designed to measure the electrical properties of interest of a fluid, such as capacitance and conductivity (resistance), as mentioned above, according to methods known independently of the invention itself. For this purpose, portions of electrodes 11 and 12 are arranged in the fluid-wetted area (i.e., inside the detection conduit 4), and the circuitry (including the circuit support 6, configured to perform the necessary detection and processing) is arranged in the dry area. Therefore, an important function for the proper operation of the sensor device is its hydraulic seal to prevent damage to the electronic components implemented on the support 6 and to prevent the detected fluid from spreading into the environment.

[0135] The primary sealing function relative to the fluid is achieved by means of an electrically insulating material overmolded into the sensitive element 10, which significantly fills the gap between the components present between the wet and dry areas of the device 1.

[0136] The sealing function can be further enhanced by associating suitable seals with the electrical connection portion 12b of the inner electrode 12 and the electrical connection portion 13b of the connecting element 13, respectively.

[0137] As already mentioned, in the preferred embodiment, columnar forming structures 3c and 3d are defined at the bottom of cavity 5. Figures 2-3 and Figures 11-12 The aforementioned electrical connection portions 12b and 13b extend through the column-shaped forming structure. Advantageously, on the portion of each of these portions 12b or 13b extending through the aforementioned forming structure 3c or 3d, a suitable seal (e.g., an O-ring seal) can be fitted, designed to ensure a seal (primarily radial seal) between the portion itself and the internal surface of the corresponding forming structure 3c or 3d. This concept is illustrated, for example, in... Figures 2-3 As shown in (see also) Figure 25 As can be seen, the O-ring seal 19 is mounted on portion 12b of the inner electrode 12, and this O-ring seal provides a sealing function relative to the internal surface of the columnar forming structure 3d. Additionally, in Figures 2-3 In the case shown, the top region of the bushing-shaped forming structure 18 of the positioning element 15 also protrudes within the forming structure 3d.

[0138] The operation of overmolding the main body 15 and / or the main body 3 onto the electrical connection portions 12b and 13b respectively may result in some leakage of polymer from the mold cavity to the portions 12b and 13b or the generation of "burrs". The presence of these burrs will lead to some uneven surfaces, especially at the top of the bushing-shaped molding structure 18 of the positioning element 15 and in the lower region of the column molding structure 3c.

[0139] To prevent the aforementioned O-ring seal 19 from operating in this potentially abnormal area, a plastic spacer 20 (e.g., a gasket) is preferably provided within the formed structure 3d, the plastic spacer being made, for example, of Teflon. The spacer 20 has a thickness suitable for positioning its upper surface higher than the aforementioned burr, so that the seal 19 will be securely held in the burr-free area of ​​the connection portion 12b.

[0140] For portion 13b of the connecting element 13 used for the external electrode 11, in Figures 2-3A similar sealing arrangement is provided in the column-shaped forming structure 3c; of course, in the case of the forming structure 3c, since the connecting element 13 does not require a positioning element (and therefore does not require a bushing-shaped forming structure of the type indicated by 18), a lower support step for the corresponding spacer 20 can be provided on the inner surface of the forming structure 3c.

[0141] In various embodiments, after the circuit support 6 is positioned and electrically connected, the insulation between the wet and dry portions of the sensor device 1 can be further enhanced by depositing resin (not shown) inside the cavity 5, which is embedded in the components present in the cavity 5.

[0142] Before the circuit support 6 is inserted into the cavity 5 and the circuit support is electrically connected, and therefore before the resin deposition process, the aforementioned plugs 21 and 22 are assembled (see...). Figures 2-3 The cylindrical seat portions 3c and 3d for sealing member 19 are closed; the presence of plugs 22 and 22 prevents the aforementioned resin from contacting sealing member 19 (the resin may interfere with proper compression and thus interfere with the sealing effect of the seal).

[0143] In various embodiments, the sensor device according to the invention includes a sensor for detecting the temperature of the fluid passing through the detection conduit 4 (particularly for indirect temperature detection). Such temperature values ​​can be used to compensate for one or more electrical quantities detected via the sensing element 10, such as for compensating for a measurement of the percentage of ethanol in the fluid, and / or such temperature values ​​can be used as independent information (fuel temperature measurement).

[0144] In some known solutions, a temperature sensor with a “droplet-shaped” sensitive element is provided for this purpose. This element is typically inserted into the space of the device body so that it can be positioned to contact the external electrode of the receiving conduit, or in any case, to be positioned near the fluid, and is used to indirectly measure the temperature of the fluid.

[0145] Such known temperature sensors (typically negative temperature coefficient thermistors (NTCs)) typically have leads that are inserted through corresponding holes in the circuit support of the device and soldered into those holes (this assembly is known as THT: through-hole technology), while the droplet sensing element is located at a distance from the circuit support, essentially near a fluid conduit defined by a corresponding external electrode; the sensing element does not come into direct contact with the fluid, but is typically placed as close as possible to the external electrode of the metal conduit from which the fluid is obtained.

[0146] In a preferred embodiment of the invention, a temperature sensor is provided, configured to be mounted on a circuit support or PCB, such as an NTC-type sensor. This type of temperature sensor is preferably surface-mount (SMD). The sensor can be directly mounted on the circuit support 6, particularly directly connected above corresponding conductive traces on the same support, without the intervention of leads or holes in the support, and the sensor can be placed near at least one of the electrical connection portions of the outer and inner electrodes (here represented by portion 13b of connecting element 13 and portion 12b of electrode 12). However, the aforementioned temperature sensor can be another type suitable for this purpose, such as a sensor without a housing or a bare die chip, with the connection between the chip and the support 6 achieved by means of fine solder wires (wire bonding), or the aforementioned temperature sensor can be a conventional "droplet" type temperature sensor with leads, but made to be adhered to the circuit support by means of adhesive designed to transmit temperature.

[0147] For this purpose, it is preferable to provide an electrical connection portion with a sufficient diameter (indicating a diameter greater than 1 mm, particularly greater than 1.5 mm) between the electrode and the circuit support 6. This relatively large diameter allows the temperature of the fluid (in direct contact with the metal electrodes 11, 12) to be rapidly brought to the circuit implemented on the support 6. In other words, by positioning the temperature sensor on the circuit support 6, sufficiently close to at least one of the electrical connection portions 13b and / or 12b, the temperature sensor is able to rapidly detect the temperature of the fluid of interest (and therefore does not need to use conventional NTC sensors with leads, which have corresponding droplet-shaped sensitive parts located near or in contact with the external tubular electrode that directly defines the detection conduit, as is done in the known art).

[0148] According to the solution of this preferred aspect Figure 3 As shown, TS, as an example, represents an SMD-type NTC temperature sensor, which is mounted on the lower surface of the circuit support 6 (i.e., the side facing the sensing element 10). In this example, the temperature sensor TS is located in a position adjacent to the connection portion 12b of the inner electrode 12, for example, at a distance of 0 to 10 mm, preferably between 4 and 6 mm.

[0149] In the figure, W represents the mass of the welding material used to mechanically constrain and electrically connect the electrical connection portion 12b of electrode 12 to the circuit support 6. This mass helps to transfer heat from the portion 12b to the circuit support 6, and thus to the sensor TS. As mentioned, the output signal of the sensor TS represents the temperature of the portion 12b, which in turn represents the temperature of the fluid.

[0150] Preferably, the sensor TS is placed immediately adjacent to the connection portion 12b of the electrode 12, since the electrode is preferably formed as a single shaped workpiece and is therefore more suitable for heat transfer; however, alternatively or additionally, the sensor TS may be placed immediately adjacent to the portion 13b of the connection element 13 of the electrode 11.

[0151] The SMD-type sensor TS solution is characterized by a significantly lower cost compared to droplet-shaped sensors with leads; known temperature sensors as THT-type components require specific soldering techniques (hot soldering irons) compared to classic SMD soldering for other electronic components implemented on the support 6. The solution of the preferred version of the invention described herein avoids the aforementioned specific soldering, thereby allowing for optimized manufacturing processes. Furthermore, the structure of droplet-shaped NTC sensors typically requires a plastic superstructure (NTC holder), which itself may include terminals for soldering to the circuit support: this is not easily managed during manufacturing, thus complicating circuit design, its material list, and the overall manufacturing process when using the droplet-shaped version.

[0152] The features and advantages of the present invention are clear from the given description.

[0153] The sensor device according to the invention is characterized by its remarkable simplicity of construction, which translates into low production costs. According to one aspect, the specific construction of the sensing element (with positioning elements for the inner electrode) not only contributes to ease of assembly but also avoids the risk of contact between electrodes. The inner electrode can be entirely or largely obtained by bending simple conductive wire in a suitable manner.

[0154] On the other hand, since the sensing conduit can be formed from a polymer material molded onto the sensing element, the sensing element has a relatively reduced longitudinal dimension compared to known solutions, increasing the simplicity of construction. The related advantages in protecting the sensing element from environmental influences are evident: the risks of metal corrosion and abnormal electrical contact are avoided (e.g., corrosion of the external electrode may be exacerbated by electrolysis or galvanic phenomena and the presence of dirt and / or chemical reagents (such as oil or salt) inside the engine compartment where the sensor unit is mounted). Integrating the sensing element into a conduit made of electrically insulating material also reduces the risk of abnormal electrical contact (such as the risk of contact with high voltage); it also avoids the need to connect the external electrode to the negative terminal of the power supply (i.e., to the metal frame of the vehicle) as is typical in known solutions, and avoids the corresponding limitations in the control circuitry of known devices (grounding connections do not allow measurements to be performed using electrodes connected to voltages or potentials not referenced to the negative terminal of the battery or ground).

[0155] Other advantages associated with overmolding are related to the possibility of easily integrating the necessary connectors / fixtures into the detection conduit; in the known solutions cited, where the same external electrode defines the detection conduit, the connectors / fixtures must be obtained by mechanical deformation of the electrode or by machining the same electrode.

[0156] According to another approach, providing a temperature sensor, particularly a surface-mount sensor, on a circuit support, which uses heat transfer via a connecting element of one of the electrodes of the sensing element for detection purposes, further simplifies the manufacture of the device and increases detection reliability. Regarding this last point, it should also be noted that in conventional solutions, the droplet-shaped sensing element of the temperature sensor must be housed in a seat within the device body to be as close as possible to the fluid, said seat having a thin wall relative to the metal sensing conduit obtained from the external electrode (the aforementioned wall must be thin to facilitate heat transfer to the sensing element of the temperature sensor). In the preferred embodiment of the invention described herein, where the sensing conduit is made of polymer, providing a thin-walled seat for the droplet-shaped temperature sensor may imply a risk of rupture (high fluid pressure could cause wall failure), resulting in fluid leakage into the cavity housing the control circuitry of the sensor device. On the other hand, the preferred positioning of the temperature sensor (on the circuit support 6, in a position close to at least one of the electrical connection portions of electrodes 11, 12) allows the high thickness of the wall of the detection conduit 4 made of polymer to withstand the working pressure of the fluid without jeopardizing temperature detection (on the other hand, if a known droplet sensor were adjacent to the thick wall of the polymer detection conduit, correct temperature detection would not be allowed; the detection would be attenuated, or in any case affected by propagation delay, resulting in detection delay and corresponding abnormalities in device operation).

[0157] It will be apparent to those skilled in the art that various modifications can be made to the apparatus described by way of example without departing from the scope of the invention as defined in the appended claims.

[0158] In possible variations, the body of the positioning element 15 can be formed separately, for example by injection molding, by providing a through opening in the same element into which the corresponding connecting portion of the electrode 12 is driven, blocked by mechanical interference, or glued. Such cases are... Figure 21 and Figure 22 It is shown schematically in the middle.

[0159] Figure 21The electrode 12 and element 15 are shown in their unassembled state. In this example, the electrode 12 has a shape similar to that already shown, while the element 15 is molded separately, thus having a seat 15c at the bottom (refer to the drawing) adapted to receive at least a portion of the intermediate connecting portion 12c of the electrode 12. In this example, the seat 15c is shaped to also receive bends 12'' and 12'''.

[0160] Figure 22 It shows Figure 21 The result of the connection between the two parts is that the connecting portion 12b of the electrode 12 is inserted through the through opening of the bushing forming structure 18 until the connecting portion 12c is fully inserted into the seat portion 15c. As already mentioned, the maintenance of the relative position between the two parts can be achieved by mechanical interference or bonding or even by the connection or deformation of the element 15.

[0161] It should be understood that, in this case, the material of the positioning element 15 also surrounds most of the connecting portion 12c of the electrode 12, ensuring electrical insulation relative to the outer electrode 11, although the connecting portion is not fully embedded or bonded in the material as in the case where the element 15 is overmolded into the electrode 11 as previously described.

[0162] As already mentioned, the shape of electrode 12 can be different from the shape illustrated in the figure, for example, it can have an L-shaped shape, such as... Figure 23 As illustrated in the example. In such cases, the length of the vertical portion of L (i.e., the electrical connection portion 12b of electrode 11) is such that a connection portion 12c is surrounded by the electrically insulating material of the positioning element 15; depending on the specific case, in the case of overmolding of element 15, this portion will be embedded in the aforementioned material, or inserted in an interference fit and / or glued to a through hole in the body of element 15, which was previously obtained separately by molding. The positioning element 15 (which has a reduced length in this document compared to the case previously shown) is fixed to the corresponding slit 14 of the tubular wall 11a of the outer electrode 11 in a manner similar to that described above (in different configurations, such as...). Figure 25 As shown, element 15 can be fixed in a through hole in the tubular wall.

[0163] In possible variations, the body of the internal electrode may be formed of several parts connected (e.g., welded) together; even in these embodiments, at least one of the parts connected to form the internal electrode may be bent in order to define different functional parts (e.g., electrical connection parts and connection parts).

[0164] This type of example is in Figure 24As shown, reference numerals from the previous figures are used to indicate elements that are technically equivalent to those already described. In this example, at least the detection portion of the inner electrode 12 (indicated by 12a') has a tubular structure, allowing fluid to also pass through this tubular mechanism. In this example, only portion 12a' is tubular and can be welded to the remainder of the electrode obtained by bending wire to define electrode portions 12b and 12c having corresponding bends 12'' and 12'''.

[0165] The solution for providing an overmolded detection conduit (which extends beyond the longitudinal end of a sensing element having an external tubular electrode and an internal electrode) is independent of the specific method of constructing the sensing element.

[0166] For example, in Figure 25 In the embodiment described above, the sensing element, indicated by 10', has a tubular wall 11a' of an outer tubular electrode 11', wherein the through slit of the aforementioned embodiment is replaced by a through hole located approximately midway between the two longitudinal ends of the same tubular wall 11a'. This through hole is occupied by a positioning element 15' that supports an L-shaped inner electrode 12'. In this case, by tilting the electrode itself, the sensing portion 12a of the electrode 12' can be inserted through the hole until the connecting portion of the positioning element 15' engages in the hole in question. Also in this case, the element 15' may be equipped with the bushing-shaped structure 18 already discussed.

[0167] As can be seen, even in this embodiment, the sensitive element 10' is completely located inside the conduit 4, which completely defines the connecting element or fixing element 4c.

[0168] In a possible embodiment (such as the illustrated embodiment), the detection conduit 4 is further overlaid with a tubular wall extending beyond at least a portion of the detection region, where the detection portion 12a of the inner electrode 12' is located. In this particular case, the tubular wall 11a' has two opposing longitudinal extensions (denoted by 11e), which in this example have an outer diameter smaller than that of the central portion of the wall (i.e., the portion of the wall corresponding to the detection region) (although this is not strictly necessary). The aforementioned longitudinal extensions 4e can serve as reinforcements for the detection conduit 4 formed of a polymer material.

[0169] In possible variations, the detection conduit 4 can also be overmolded onto other components (such as at least one separate tubular element located at the corresponding hydraulic connector HC). Figure 25 A variation of this type is also shown, in which two such tubular elements (denoted by 4e) are provided. Element 4e may be made of metal or other materials suitable for reinforcing the corresponding portion 4d of the conduit 4 and / or the corresponding hydraulic connector HC.

[0170] It should be understood that, despite the differences in specific designs, Figure 25 The sensor device 1 can be referenced Figures 17-20 The method described is used to obtain it.

[0171] The through slit of the outer electrode can extend the entire length of the tubular wall. In this case, the positioning element for the inner electrode will have a corresponding length and will be received into the slit itself so as to substantially completely occupy the slit.

[0172] In other embodiments, the through slit of the outer electrode may extend into at least a portion of the middle region of the circumference of the tubular wall, in which case the positioning element will have a corresponding curved shape and will be received into the slit itself so as to substantially completely occupy the slit.

[0173] The tubular wall of the outer electrode can be two parts, i.e., cut in the middle region, thereby forming two essentially longitudinally aligned outer tubular electrodes, and equipped with corresponding elements for electrical connection to each other (without affecting the provision of connection elements toward the circuit support 6, such as connection elements indicated by 13 that are in electrical contact with at least one of the aforementioned two outer tubular electrodes). In such embodiments, the positioning element for the inner electrode will have a substantially annular or tubular shape, and will be substantially configured to form a hydraulic connector between the two outer tubular electrodes (i.e., located in the middle of the two outer tubular electrodes and configured for connection to the opposite ends of the two outer tubular electrodes) to keep them fixed to each other and longitudinally aligned along the same axis to define a channel for fluid in which the detection portion of the inner electrode extends; such a positioning element may be associated with one or more inner electrodes.

Claims

1. A sensor device (1) for measuring at least one electrical property of a fluid, the sensor device comprising a device body (2) having a detection conduit (4) having an inlet (4a) and an outlet (4b) for the fluid, and a sensitive element (10) for detecting the at least one electrical property being arranged within the detection conduit (4). in, The sensing element (10) includes a first electrode (11) and a second electrode (12), the second electrode extending partially within the first electrode (11). The first electrode (11) extends in the length direction (L) and has a substantially tubular wall (11a) having a first longitudinal end (11b) and a second longitudinal end (11c) opposite to each other. The first longitudinal end (11b) and the second longitudinal end (11c) of the tubular wall (11a) are open to allow fluid to pass through the first electrode (11), and the second electrode (12) extends partially inside the tubular wall (11a) and is spaced apart from the tubular wall. The first electrode (11) has a through slit (14) that extends along the length direction (L) from the first longitudinal end (11b) to the second longitudinal end (11c) and covers at least a portion of the tubular wall (11a). The sensitive element (10) includes a positioning element (15) for the second electrode (12), the positioning element being fixed to a through slit (14) in the tubular wall (11a), the positioning element (15) being at least partially formed of an electrically insulating material and configured to support the second electrode (12).

2. The sensor device according to claim 1, wherein, The second electrode (12) has a body, which is shaped to have: The detection portion (12a) extends at least partially and substantially in the length direction (L) of the first electrode (11) within the first electrode (11). The electrical connection portion (11b) extends at least partially outside the first electrode (11), particularly laterally relative to the length direction (L) of the first electrode (11). The connecting portion (12c), which is at least partially surrounded by the electrically insulating material of the positioning element (15) at the through slit (14), Preferably, the main body of the second electrode (12) is: - Bend such that at least a portion of the electrical connection portion (12b) is substantially orthogonal to at least a portion of the detection portion (12a), and / or - Bend such that at least a portion of the connecting portion (12c) is substantially parallel to at least a portion of the detection portion (12a), and / or - It is bent into having at least three bends (12', 12'', 12''').

3. The sensor device according to claim 1 or 2, wherein, The positioning element (15) is an element that is overmolded into a part of the body of the second electrode (12).

4. The sensor device according to any one of claims 1-3, wherein, At least a portion (3) of the device body (2) defining the detection conduit (4) is overmolded into a portion of the sensitive element (10).

5. The sensor device according to claim 4, wherein, The detection conduit (4) is integrally formed to define at least one hydraulic connector (HC).

6. The sensor device according to any one of claims 1-5, wherein, The positioning element (15) is received into the through slit (14) so ​​as to substantially completely occupy the through slit.

7. The sensor device according to any one of claims 1-6, wherein, The positioning element (15) has at least one of the following: - A connecting portion (15a), which is received in the through slit (14), and which is provided with at least one sealing protrusion (15a') on its surface, the at least one sealing protrusion being configured to cooperate with the surface (11d) of the tubular wall (11a) that defines the through slit (14). - A receiving portion (15b), which has a larger lateral overall size relative to the through slit (14), is used to rest at least partially on the edge or outer surface of the tubular wall (11a).

8. The sensor device according to any one of claims 1-6, wherein, The positioning element (15) has a receiving portion (15b) defining at least one of a pair of opposing lateral protrusions (16a), a longitudinal protrusion (16b), an upper reinforcing rib (17a-17b), and an upper bushing-shaped structure (18), the corresponding portion of the second electrode (12) extending through the upper bushing-shaped structure.

9. The sensor device according to any one of claims 1-8, comprising an electrical connection element (13) that is in electrical contact with the outer surface of the tubular wall (11a).

10. The sensor device according to claim 9, wherein, The electrical connection element (13) has a body that is shaped such that at least a portion of its electrical connection portion (13b) extends substantially parallel to at least a portion of the electrical connection portion (12b) of the body of the second electrode (12), wherein, preferably: - The main body (2) of the device has a housing cavity (5) for the circuit arrangement (6), and the electrical connection portion (13b) of the main body of the electrical connection element (13) and the electrical connection portion (12b) of the main body of the second electrode body (12) are electrically connected to the circuit arrangement. - The housing cavity (5) has a bottom through which the electrical connection portion (13b) of the body of the electrical connection element (13) and the corresponding portions of the electrical connection portion (12b) of the body of the second electrode (12) pass, and at least one sealing element (19) is associated with each of the corresponding portions of the electrical connection portions (12b, 13b).

11. A sensor device (1) for measuring at least one electrical property of a fluid, the sensor device comprising a device body (2) having a detection conduit (4) having an inlet (4a) and an outlet (4b) for the fluid, and a sensing element (10; 10') disposed within the detection conduit (4) for detecting the at least one electrical property, in, The sensing element (10; 10') includes a first electrode (11; 11') and a second electrode (12; 12'), the second electrode extending partially within the first electrode (11; 11'). The first electrode (11; 11') extends in the longitudinal direction (L) and has a substantially tubular wall (11a; 11a') having a first longitudinal end (11b) and a second longitudinal end (11c) opposite each other. The tubular wall (11a; 11a') has a first longitudinal end (11b) and a second longitudinal end (11c) that are open to allow fluid to pass through at least the first electrode (11; 11'), and the second electrode (12; 12') is associated with the first electrode (11; 11') and extends partially within the tubular wall (11a; 11a'), spaced apart from the tubular wall. Wherein, the portion (3) of the main body (2) of the device that at least defines the detection conduit (4) is a portion overmolded to the sensitive element (10; 10'), particularly a polymer overmolded portion, and the overmolded portion of the detection conduit (4) preferably integrally defines at least one hydraulic connector (HC) and / or fixing element (4c).

12. A sensor device (1) for measuring at least one electrical property of a fluid, the sensor device comprising a device body (2) having a detection conduit (4) having an inlet (4a) and an outlet (4b) for the fluid, and a sensing element (10; 10') disposed within the sensing conduit (4) for detecting the at least one electrical property, in, The sensing element (10; 10') includes a first electrode (11; 11') and a second electrode (12; 12'), the second electrode extending partially within the first electrode (11; 11'). The first electrode (11; 11') extends in the longitudinal direction (L) and has a substantially tubular wall (11a; 11a') having a first longitudinal end (11b) and a second longitudinal end (11c) opposite each other. The tubular wall (11a; 11a') has a first longitudinal end (11b) and a second longitudinal end (11c) that are open to allow fluid to pass through at least the first electrode (11; 11'), and the second electrode (12; 12') is associated with the first electrode (11; 11') and extends partially within the tubular wall (11a; 11a'), spaced apart from the tubular wall. The device body (2) includes a main body portion (3), which defines a housing cavity (5) for a circuit support member (6) and a control circuit supporting the sensor device (1). The electrical connection portion (13b) of the first electrode (11; 11') and the electrical connection portion (12b) of the second electrode (12; 12') are electrically connected to the control circuit. Preferably, a temperature sensor (TS) is mounted on the side of the circuit support (6) facing the sensitive element (10; 10'), the temperature sensor preferably being of the SMD type, and is configured to indirectly detect the temperature of the fluid transmitted via the electrical connection portion (13b) of the first electrode (11; 11') and / or via the electrical connection portion (12b) of the second electrode (12; 12').

13. A method for manufacturing a sensor device (1) for measuring at least one electrical property of a fluid, the method comprising the steps of: a) Provide an external electrode (11; 11') comprising a substantially tubular wall (11a; 11a') extending in the longitudinal direction (L), the external electrode (12; 12') having an electrical connection portion (13b). b) Provide an inner electrode (12; 12') including a detection portion (12a) extending at least partially substantially in the length direction (L), and the outer electrode (11; 11') having an electrical connection portion (12b). c) The sensitive element (10; 10') of the sensor device (1) is obtained by associating the outer electrode (11; 11') with the inner electrode (12; 12'), wherein the inner electrode (12; 12') extends at least partially within the outer electrode (11; 11') and is electrically isolated from the outer electrode. d) Overmolding an electrically insulating polymer or plastic material onto the sensing element (10; 10') to obtain a portion (3) of the device body (1) of the sensor device (1), the portion defining at least a portion of the detection conduit (4), the sensing element (10; 10') is integrated into the detection catheter.

14. The method according to claim 13, wherein, Step d) includes the following operation: overmolding the electrically insulating polymer or plastic material to integrally define a connecting element or fixing element (4c) on the outside of the detection conduit (4), the connecting element or fixing element being specifically shaped as a radially projecting flange for connecting the detection conduit (4) along a fluid-supplying conduit.

15. The method according to claim 13, wherein: - Step a) includes the following operation: providing a tubular wall (11a) having a through slit (14), the through slit extending in the length direction (L) from a first longitudinal end (11b) toward a second longitudinal end (11c) of the tubular wall (11a), at least a portion of the tubular wall (11a). - Step b) includes the following operation: shaping the body of the inner electrode (12) to have at least a detection portion (12a), an electrical connection portion (12b) and a connection portion (12c). - Step c) includes the following operations: fixing a positioning element (15) to the inner electrode (12), the positioning element being at least partially formed of an electrically insulating material and configured to support the inner electrode (12); and connecting the positioning element (15) to a through slit (14) of the tubular wall (11a) of the outer electrode (11), such that The detection portion (12a) of the main body of the inner electrode (12) extends substantially along the length direction (L) of the outer electrode (11), is located within the tubular wall (11a) of the outer electrode (11), and is spaced apart from the tubular wall. The electrical connection portion (12b) of the main body of the inner electrode (12) extends at least partially outside the outer electrode (11), particularly laterally relative to the length direction (L) of the outer electrode (11), and The connecting portion (12c) of the main body of the inner electrode (12) is at least partially surrounded by the electrically insulating material of the positioning element (15) at the through slit (14). Specifically, step c) includes the following operation: overmolding the positioning element (15) onto a region of the inner electrode (12), the region being substantially located between the detection portion (12a) and the electrical connection portion (12c), and the region including at least a portion of the connection portion (12c).

16. The method according to claim 13, wherein, The overmolding operation in step d) includes: - Position the sensitive element (10; 10'') in the mold (30', 30''). - The first longitudinal end (11b) and the second longitudinal end (11c) of the tubular wall (11a; 11a') of the outer electrode (11; 11') are sealed by means of the corresponding movable mold element (32'). - Injecting an electrically insulating plastic material in a fluid state into the mold (30', 30''), which is required for forming at least a portion (3) of the device body (2) that defines the detection conduit (4), - Wait for the electrically insulating plastic material to cure, and - Remove a portion (3) of the device body (2) from the mold (30', 30''), the portion defining a part of the detection conduit (4) incorporating the sensitive element (10; 11').

17. A sensor device (1) for measuring at least one electrical property of a fluid, the sensor device comprising a device body (2) having a detection conduit (4) having an inlet (4a) and an outlet (4b) for the fluid, and a sensing element (10) disposed within the sensing conduit (4) for detecting the at least one electrical property. in, The sensing element (10) includes at least one first electrode (11) and at least one second electrode (12), wherein the at least one second electrode preferably has at least one positioning element (15) associated with at least one of the first electrode (11) and the second electrode (12), the positioning element (15) being at least partially formed of an electrically insulating material. In this embodiment, at least one portion (3, 4) of the main body (2) of the device is made of a polymer overmolded onto the sensitive element (10; 10').

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