In particular, a pressure sensor device for gaseous fluids

Abstract

The pressure sensor device comprises a support and a detection arrangement. The detection arrangement has a pressure-sensitive element (3) having a detection membrane and a circuit arrangement (3e, 8, 11, 30) including a control circuit (30) having a circuit support (30a) and an electrical connection element (3e). The pressure-sensitive element (3) is associated with the support such that a substantial portion of the detection membrane is directly exposed outside the support and is reachable by a fluid. The support (2) has an engagement portion (4) configured in particular to be inserted into the passage of a fluid duct. The engagement portion (4) has a distal end portion (5b) by which the pressure-sensitive element (3) is constrained. The circuit support (30a) is associated with a positioning body (20). The positioning body (20) is associated with the pressure-sensitive element (3). The electrical connection element (3e) forms a detection unit (10) by constraining the circuit support (30a) to the pressure-sensitive element (3) with the positioning body (20) at least partially sandwiched between the circuit support (30a) and the pressure-sensitive element (3). The detection unit (10) is fixed to the distal end portion (5b) of the engagement portion (4) by at least one fixing element (6).

Description

Technical Field

[0001] The present invention relates to a pressure sensor device, and more particularly to a sensor device for detecting the pressure of a gaseous fluid, such as a fluid that is at least partially affected by freezing, in particular a gas (vapor) fluid containing moisture or water vapor, or a suspension that is prone to freezing.

Background Art

[0002] Pressure sensor devices for fluid media are widely known. Such devices generally include a pressure-sensitive element having a substrate that defines or has an elastically deformable detection membrane associated therewith. On one side of the membrane that is not exposed to the fluid, there are associated elements for detecting the deformation or deflection of the membrane itself, which are typically capacitive, resistive, or piezoresistive elements, whereby information indicating the degree of deformation or deflection is obtained, which in turn indicates the pressure value of the fluid to which the membrane is exposed.

[0003] Small-sized sensitive elements formed of semiconductor materials, typically starting from silicon dies, are known, but generally, for applications where higher robustness is required, the sensitive elements are larger and are generally formed of ceramic materials, such as alumina, or metal materials, such as stainless steel.

[0004] A pressure sensor device equipped with these sensing elements generally includes a housing body configured to obtain electrical and hydraulic connections, within which the sensing elements and any associated control electronics are mounted. For electrical connection, the casing body generally defines a connector body with electrical connection terminals. For hydraulic connection, the casing body defines a port made of plastic or metal and is configured to interface with a circuit in which the fluid whose pressure must be measured is present. The port is generally tubular in shape and thus defines a channel through which the fluid can reach a chamber defined inside the casing body, which chamber is partially delimited by the membrane of the sensing element and can thus be reached by the same fluid.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Even after the circulation of the fluid in the corresponding circuit is interrupted, there is a possibility that the fluid accumulates in the inlet channel and the detection chamber. The possibility of such liquid accumulation is potentially dangerous in relation to the reliability of operation and the integrity of the sensing element when the sensor device is operating under conditions of low ambient temperature. In such a situation, in fact, the liquid residue may freeze, and as a result, its volume increases, imposing a significant mechanical stress on the sensing element.

[0006] To solve this problem, a solution has been proposed in which a protective element formed with an elastically compressible material is arranged inside the fluid inlet channel and / or inside the detection chamber. In these solutions, the volume increase caused by the freezing of the fluid residue is offset by the volume decrease of the protective element. These solutions are relatively simple, but the related sensor devices have the disadvantage that they require a relatively long waiting time for the device itself to return to normal operation (that is, the device cannot measure the pressure in the circuit unless the fluid is completely thawed). This disadvantage is particularly problematic when the fluid to be pressure-detected is a gas containing moisture or water vapor, or a fluid that may freeze.

[0007] A typical example in this sense is a fuel cell, where hydrogen and air existing on the anode side and the cathode side respectively may have a certain moisture content. Even in such cases, the moisture present in the gas may accumulate in the inlet channel and the detection chamber over a long period of time, especially when the operating temperature drops below the dew point. In such cases, when the temperature drops below the freezing point, the trapped moisture may freeze, which may prevent or change the operation of the detection membrane and may prevent the sensor device from accurately measuring the pressure of the fluid inside the channel through which the fluid flows.

[0008] To solve the drawbacks associated with the potential freezing of the fluid or moisture residue, solutions have also been proposed to fill the inlet channel with an incompressible fluid. In these solutions, the pressure of the fluid to be measured by the pressure measurement causes stress on the incompressible fluid, and the stress is transmitted to the sensing membrane. In this way, since there is no duct or chamber in the sensor device where liquid or moisture accumulates, the aforementioned drawbacks are avoided. On the other hand, these solutions complicate the manufacturing process of the sensor device and thus become very expensive. The related drawbacks of these solutions are related to the fact that, unless the realization of the device itself requires a great deal of complexity, means for detecting the temperature of the fluid cannot be equipped in the device either.

[0009] A simpler solution to the problem shown is known from KR20190059433A, on which the preamble of claim 1 is based. In this solution, the pressure sensor device is designed such that the detection membrane of the sensing element is directly exposed to the fluid of the gas inside the duct through which the same gas circulates.

[0010] The attached Figures 1 and 2 correspond to Figures 5 and 6 of the cited prior art documents respectively. In these figures, 700 indicates the sensor body or cover, inside which a circuit support 400 is arranged to support the control electronics of the device.

[0011] The substrate 200 is directly attached to the lower side of the circuit support 400 and is fixed to the lower end of the substrate detection film 300 by a fixing material 220. The substrate 200 and the film 300 are made of ceramic material, and the fixing material 220 can be glass frit. The sensing element composed of the substrate 200 and the related film 300 is equipped with terminals or pins 500 for connecting to the circuit support 400, and the latter also has electrical connection terminals 710 attached to the cover 700.

[0012] Particularly as shown in FIG. 2, in the assembled state, the sensing element composed of the substrate 200 and the film 300 protrudes downward beyond the cover 700 and is fixed by an epoxy resin layer 600 using the circuit support 400.

[0013] To fix the substrate 200 and the corresponding circuit support 400 to the cover 700 and ensure the airtightness of the sensor against the external environment, epoxy resin 600 is injected into one end of the cover 700. To improve the assemblability, the substrate 200 is provided with an upper annular throat 210 that can hold the resin 600. In such an assembled state, the substrate 200 and the film 300 protrude with respect to the cover 700. The substrate 200 also has a lower groove for obtaining a seat for an annular gasket 220, which is intended to obtain a seal against the surface of the radial passage into which the sensing element 200 - 300 is inserted. Particularly as shown in FIG. 2, in the operating state, the sensing element composed of the substrate 200 and the film 300 is inserted into the radial passage of the duct 110 through which gas flows, and as a result, the film 300 is directly exposed to the gas.

[0014] Therefore, as can be seen, in the assembled state, the film 300 is directly exposed to the gas flowing into the duct 110, and the location where moisture that inevitably exists in the gas may accumulate can be removed or otherwise minimized.

[0015] The type of structure envisaged in the prior art documents mentioned is complex and expensive, also in relation to the method of installing the device, where the sensitive part has to be placed directly inside the corresponding passage of the gas circulation duct. Furthermore, the fact that a radial seal is obtained directly between the substrate 200 of the sensitive part and the duct passage determines a high risk of friction and / or torsion during insertion, which results, subsequently, in abnormal mechanical stresses, which can also be due to operating conditions (such as vibrations), and which can, as a result, damage the sensitive part and / or the circuit support. This risk is also partially increased by the fact that the sensitive element is connected to the circuit support via thin terminals and the fixing is only carried out by means of a thin layer of epoxy resin.

Means for Solving the Problem

[0016] Generally speaking, the present invention aims to create a pressure sensor device that is particularly intended for use in combination with gaseous fluids, has a simple and economical structure, is easy to install and highly reliable. This aim and other aims that will become apparent later are achieved, in accordance with the present invention, by a pressure sensor device having the features of the appended claims. The claims form an essential part of the technical teaching provided herein in relation to the present invention.

Brief Description of the Drawings

[0017] Further aims, features and advantages of the present invention will become apparent from the following detailed description made with reference to the accompanying schematic drawings, provided purely by way of non-limiting example.

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DETAILED DESCRIPTION OF THE INVENTION

[0018] References to "one embodiment" in this specification indicate that the particular configuration, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, phrases such as "in one embodiment" may occur in different places in this specification but do not necessarily refer to the same embodiment. Further, the particular forms, structures, or characteristics described or illustrated may be combined in any suitable way in one or more embodiments, even if they differ from those illustrated. The reference numerals used in this specification are for convenience only and thus do not define the scope of protection or the scope of embodiments. The spatial references used in this specification (such as "upper", "lower", "top", "bottom", etc.) are for convenience only and refer to the examples shown in the figures. In the figures, the overlap of some of the elements shown (such as seal elements or electrical contact elements) is for emphasizing the original shape of the elements themselves before elastic deformation after compression.

[0019] Referring initially to FIGS. 3 to 6, reference numeral 1 generally denotes a pressure sensor device according to a possible embodiment, particularly for use in combination with a fuel cell. The device 1 includes a support 2, to which a pressure detection arrangement is associated. For example, the support 2 may be made of molded plastic, although it does not exclude a metal material or a combination of the materials shown. The detection arrangement described above includes a pressure-sensitive element 3 having an elastically deformable detection membrane 3a and a circuit arrangement to be described later. As can be seen, for example, in FIG. 3, the sensitive element 3 is associated with the support 2 such that, as will be described below, a substantial portion of the detection membrane 3a is directly exposed outside the support 2 so that the fluid can reach it. For this purpose, in various embodiments, the sensitive element 3 is preferably protected by the body 2 or by a protective element applied to the body, but is associated with the body 2 so as to be located outside the body itself. Hereinafter, it is assumed that the fluid in question is a gaseous fluid.

[0020] In various embodiments, the support 2 has an engagement portion 4, which is configured to be inserted into the passage of a duct for a fluid for which the pressure has to be detected, as will be described below. In a non-limiting example, the body 2 has an upper portion with a larger cross-sectional dimension with respect to the engagement portion 4, the latter extending from the upper portion. However, in a possible operating variant, the body 2 extends only axially (it can have, for example, a substantially cylindrical cross-section), in which case only the lower part of the axially extending body obtains the engagement portion 4.

[0021] The engaging portion 4 preferably has a substantially cylindrical shape and is close to the portion of the body 2 that must remain outside the fluid duct, for example the proximal end portion shown at 5a in FIGS. 3 - 4, and a distal end portion that is far from the portion of the body 2 that must remain outside the fluid duct, for example shown at 5b in FIGS. 5 - 6. The pressure - sensitive element 3 is constrained at the distal end portion 5b by at least one fixing element, for example the element shown at 6. In various embodiments, this fixing element serves to partially protect the sensing element 3. The engaging portion 4 preferably has sealing means on the outside. In this example, the engaging portion 4 defines an intermediate sheet 4a for arranging an elastomeric sealing ring 7 for this purpose. The sheet 4a is located at an intermediate position between the proximal end 5a and the distal end 5ba of the engaging portion 4.

[0022] The detection arrangement includes a plurality of electrical terminals, for example three terminals, for connecting the device 1, and one of them is shown at 8 in FIG. 4. As can be seen from this figure, the terminal 8 has a proximal end portion 8a that protrudes inside the tubular portion 2a of the body 2 to obtain a multi - pole electrical connector. The distal end portion 8b of the terminal 8 extends inside the body 2, preferably inside the engaging portion 4. In this example, the proximal end portion and the distal end portion of the terminal 8 are essentially flat and parallel and are joined by a straight intermediate portion 8c. The terminal 8 can still have a different shape and position than the illustrated case without impairing its function.

[0023] When the body 2 is formed of a plastic material, it can be directly molded over the terminal 8 and, in some cases, can define an internal cavity shown at C in FIGS. 4 - 5. In such a case, the body 2 may include a cover 2b for closing the cavity. The cavity C can function to make the body 2 lighter and / or can be useful for holding the terminal 8 in a predetermined position during the over - molding step of the body 2.

[0024] As will become apparent later, the sensing element 3 is part of a detection unit generally designated 10 in the figures, is attached to the distal end portion 5b of the engagement portion 4 of the body 2, and this portion 5b is configured to be inserted into the passage of a duct, particularly for a fluid duct, in which pressure must be detected. For this purpose, in various embodiments, this distal end portion 5b defines a housing indicated at C' in FIG. 6, which housing opens downwardly (with reference to the figure), i.e., towards the outside of the body 2, and in which the above-described unit 10 is at least partially received.

[0025] From FIGS. 4 and 6, in a possible embodiment, the engagement portion 4 has a transverse wall 2c that defines the bottom of the housing C', and in this transverse wall 2c, through seats (not shown), preferably axial through seats, are defined for the respective contact elements 11. For this purpose, the above-described seats are defined in the wall 2c, for example, in formations or bosses of this wall. In various embodiments, the contact elements 11 are preferably electrically conductive elastic contact elements, such as compression contact elements, that do not require welding, as will be described below. In the non-limiting example shown, the element 11 is basically in the form of a helical spring, and alternatively, the contact element 11 can have other shapes, for example, at least partially arcuate, such as substantially in an "S" or "C" shape.

[0026] FIGS. 7 and 8 show a possible implementation of the above-described detection unit 10 with a corresponding annular seal element 12.

[0027] In addition to the above-described sensing element 3, the unit 10 includes a control circuit 30 that is part of the circuit arrangement of the device, and this arrangement also includes electrical connection elements that electrically connect the sensing element 3 to the control circuit 30. In various embodiments, the unit 10 also preferably includes a positioning body 20 configured as a separate part with respect to both the circuit 30 and the sensing element 3 (however, it may also be in a shape that can be coupled or fixed to at least one of the control circuit 30 and the sensing element 3).

[0028] The sealing element 12 is preferably configured to achieve an axial seal and surrounds at least partially the unit 10, in particular substantially surrounding the positioning body 20 when the positioning body 20 is present. In various embodiments, a boss or radial projection 12a (FIG. 8) is provided on the inner diameter of the sealing element 12, whereby the element itself can be attached to the unit 10 at the central position and / or with a slight elastic interference. There may also be no projection 12a, in which case the inner diameter of the element 12 is such that it can be attached to the unit 10 at the central position and / or with a slight elastic interference.

[0029] FIG. 9 schematically shows in an exploded view the feasibility of realizing a sensing element 3, which is preferably a non-miniaturized element (meaning that the element 3 is not of the type obtained from a die of a semiconductor material such as silicon). In various embodiments, the element 3 includes a substrate 3b to which a film is attached by a suitable fixing material 3c. For example, when the film 3a and the substrate 3b are made of a ceramic material (e.g., alumina), the fixing material 3c may be a glass frit or an adhesive. The material 3c is arranged in an annular form in the radially outermost region of the opposing surfaces of the film and the substrate and has a thickness (see reference numeral 3f in FIGS. 28 and 30) such that a chamber is defined between the film and the substrate, or in any case has sufficient space to allow elastic deflection of the film. Preferably, the material 3c realizes an airtight seal between the film 3a and the substrate 3b.

[0030] The sensing element 3 is provided with means for detecting elastic deformation or deflection of the membrane 3a. In various embodiments, on the inner surface side of the membrane 3a (i.e., the surface facing the substrate 3b), a sensing element 3d is arranged according to well-known techniques, for example, a piezoelectric element or a resistive element arranged in a bridge configuration (especially a Wheatstone bridge) is arranged. By means of conductive tracks (not shown), the detection element 3d is connected in signal communication with the connection terminals or pins 3e of the sensing element 3 according to techniques well-known per se. In the embodiment, the pins 3e are fixed by passing through corresponding holes defined in the substrate 3b and are arranged in the radially outermost annular region on the upper surface of the substrate 3b so as not to interfere with the deformation of the membrane 3a. In various preferred embodiments, the pins 3e are used to electrically connect the sensing element 3 to the circuit 30 and mechanically restrain it, obtain connection elements, and a positioning body 20 is set between them.

[0031] Figures 10 and 11 show possible embodiments of the detection unit 10 including the sensing element 3, the positioning body 20, and the control circuit 30. The latter includes a printed circuit support (or PCB board - printed substrate) 30a made of an electrically insulating material, or electrically insulated, for example, by deposition of an insulating layer, on which tracks of a conductive material (not highlighted) for connecting electrical and electronic components 31, which are part of the control circuit 30 of the sensor device according to well-known techniques, are deposited. The cited components preferably include integrated circuits 31a such as a microcontroller or an ASIC (application-specific integrated circuit) and / or memory means. The circuit support 30a has through-holes provided with a conductive coating 32 to which a part of the above-mentioned tracks is connected. The coating 32 has a surface metallization of the through-hole formed to define pads corresponding to at least one of the two opposite surfaces of the substrate 30a, and a part of the above-mentioned conductive tracks is connected to these pads. The pins 3e of the sensing element 3 are inserted into the above-mentioned holes (see, for example, Figures 8 - 9), and they are electrically and mechanically connected to the coating or pads 32, for example, by welding or tin plating.

[0032] In various preferred embodiments, on one surface of the circuit support 30a, which is referred to herein as the upper surface, contact pads 33 are provided, and a part of the above-described conductive tracks is connected to the contact pads 33 with the intention of connection to the contact elements 11, as will be described below.

[0033] In various embodiments, the positioning body 20 and the circuit support 30a each have respective coupling elements configured to specify the mounting position of the circuit support 30a on the positioning body 20. In the case illustrated in the figure, the circuit support 30a has a peripheral seat or recess 34, preferably a radial seat or recess, for this purpose. In the illustrated example, when the circuit support 30a has a substantially circular peripheral shape, three radial recesses 34 are present substantially 120° apart from each other. The circuit support being circular is not an essential feature.

[0034] The positioning body 20 is shown independently in FIGS. 12 and 13. In this example, the general peripheral shape of the body 20 is substantially circular in accordance with the peripheral shapes of the sensing element 3 and the circuit support 30a. However, in other embodiments, the above shape may be different from that illustrated, for example, substantially square (square or rectangular) or polygonal with four or more sides (e.g., hexagonal).

[0035] The body 20 is preferably made of an electrically insulating material such as a molded plastic material and has an annular peripheral wall 21 defining a central passage 22, which has, for example, a substantially polygonal shape or a shape obtained by linear and / or curvilinear extensions.

[0036] The body 20 defines a support element 23 for the circuit support 30, which in the present specification consists of a radially protruding portion inside the peripheral wall 21, i.e., a radially protruding portion of the wall of the central passage 22. The protruding portion 23 has first positioning means for specifying the axial position between the two parts and has an upper surface 23a that specifies a support plane for the circuit support 30a. The body 20 preferably has, on its upper surface, a second positioning element, preferably in the form of an axially protruding portion 24, which, as will be described later, has an element for coupling with the circuit support 30a to specify the relative angular position between the two parts in question.

[0037] In various preferred embodiments, the distal end portion 5b of the positioning body 20 and the engagement portion 4 have respective coupling elements configured to specify a unique mounting position of the detection unit 10 with respect to the distal end portion 5b. In the illustrated example, one of the axially protruding portions of the body 20 (designated 24' in the figure) defines a seat or recess 25 intended for coupling with a corresponding positioning element 13 (see, for example, FIG. 6) defined inside the housing C', in particular the distal end portion 5b described above.

[0038] The radial protrusion 23 is preferably in a position corresponding to the radial protrusion 24, but may differ in number and / or position and / or shape.

[0039] To obtain the unit 10, the control circuit 30, i.e., the support 30a, is arranged on the positioning body 20 such that the former positioning recess 34 engages with the latter positioning protrusion 24, as shown, for example, in FIG. 8. Of course, the coupling means exemplified herein by the protrusion 24 and the recess 34 may be of different types or shapes.

[0040] The circuit support 30a is arranged such that the surface supporting the contact pads 33 (FIG. 10) faces upward. Subsequently, the lower surface of the positioning body 20 shown in FIG. 12 is placed on the upper surface of the sensing element 3, from which the pin 3e projects and passes through the central passage 22 of the main body 20 (FIGS. 12 - 13), and thus can be inserted into the corresponding holes provided in the conductive coating 32 on the support 30a.

[0041] The pin 3e is fixed to the coating or pad 32 by welding or other means (e.g., by paste or conductive adhesive) in order to obtain an electrical and mechanical connection between the circuit 30 and the sensing element 3. In this way, the circuit support 30a is attached to the positioning body 20, which is supported by the sensing element 3, and the electrical connection element is represented by the pin 3e that constrains the support 30a to the sensing element 3 with the positioning body 20 interposed therebetween, forming the detection unit 10. Thus, preferably, the sensing element 3 indirectly supports the circuit 30 via the main body 20.

[0042] In this way, the unit 10 can be pre - assembled, easily manipulated at the production stage, and in some cases, an assembly already equipped with the sealing element 12 can be obtained. It is understood that there are clear advantages, for example, in terms of handling pre - assembled parts and warehouse management for automated production and / or subsequent production, in the form of different types of final pressure sensors.

[0043] It should be noted that the connection element, i.e., the pin 3e, can also be replaced by terminals surface - mounted (surface - mounting technology) on the upper surface of the substrate 3b of the sensing element 3, in which case it is electrically connected to the circuit holder 30a (e.g., by tin plating) in the same way as the pin 3e.

[0044] Another possibility consists of replacing pin 3e with connection pads on the upper surface of substrate 3b and obtaining the connection between these pads and the pads of the same type on circuit support 30a by means of elastic contact elements (e.g., of the type shown at 11). In this case, the above-described elastic contact elements can be soldered by surface mounting technology at their first end to the pads on the upper surface of substrate 3b and can be tin-plated at their opposite end to the corresponding pads of circuit support 30a.

[0045] For example, from FIGS. 8, 10-11 and 15, it will be understood that in the assembled state of unit 10, circuit support 30a extends substantially parallel to sensor element 3 or its film 3a. From the same figures, it can be seen that preferably, circuit support 30a has a smaller cross-sectional area (i.e., overall lateral dimensions) than sensor element 30, and preferably, positioning body 20 also has a smaller cross-sectional area (i.e., the overall lateral dimension) than sensor element 30. Also, as a preferential measurement, circuit support 30a and / or positioning body 20 and / or sensor element 30 do not have a cross-sectional area (i.e., overall lateral dimension) greater than the cross-sectional area of distal end portion 5b.

[0046] The distal end portion 5b of the engagement portion 4 of support 2 is preferably shaped to be received inside a portion that includes at least a part of detection unit 10, in particular at least a part of circuit support 30a and / or positioning body 20.

[0047] As already shown, in various preferential embodiments, distal end portion 5b defines housing C' (see also FIG. 6), where detection unit 10 is at least partially received. FIGS. 14 and 15 show that in the assembled state of the sensor device, a part of positioning body 20 and circuit support 30a are inside housing C'.

[0048] Preferably, the distal end portion 5b also defines one or more axial stationary surfaces or positioning surfaces for at least one of the positioning element 20 and the sensing element 3, particularly within the cavity C'. In the example shown in FIGS. 14-15, 5a' represents an axial positioning surface against which the tops of the axial elements 24 and 24' (see also FIGS. 8 and 13) can abut (note that, for example, from the perspective of elastic attachment, the axial element 24 may abut against the surface 5a' only as a result of an external stress).

[0049] Preferably, within the housing C', as seen in FIG. 15, a seat for the contact element 11 defined by the formation 2d of the wall 2c is also open.

[0050] In various embodiments, the distal end portion 5b of the detection unit 10 and the engagement portion are configured such that the unit 10 can be attached to the portion 5b from the bottom (with reference to the figure) from the outside thereof. Such a solution, for example, makes it possible to simplify the assembly of the device.

[0051] FIGS. 14 and 15 are intended to illustrate a first possible method of attaching the assembled detection unit 10, using the fixing element shown previously at 6. As also shown in FIG. 5, in this embodiment, the fixing element 6 has an annular or tubular body with a peripheral wall 6a having a flange 6b projecting radially inwardly at the lower end to define a passage 6c having a diameter or cross-sectional size smaller than the maximum diameter or cross-sectional size of the sensing element 3, essentially obtaining a support for the sensing element 3 or the pre-assembled detection unit 10.

[0052] The elastic contact element 11 is attached to the associated seat (see also FIG. 6) so as to be in compressive contact with the distal end portion 8b of the corresponding terminal 8. These portions 8b of the terminal can have holes or positioning reliefs for the upper end of the element 11 at positions corresponding to the seat for the element 11. (In this example, since the contact element is essentially in the form of a helical spring, its upper end is shown in its original extended form in order to give an idea of how this end is elastically compressed during assembly and abuts against the portion 8b - see FIG. 15). Then, the pre-assembled unit 10 provided with the sealing element 12 is brought from the bottom against the lower end portion of the portion 5b of the engaging portion 4, such that at least a part of the unit 10 (here the circuit support 30a and preferably a part of the positioning body 20) extends into the housing C'. As described above, the unique positioning of the unit 10 is ensured by the coupling means consisting of the seat 25 of the body 20 and the corresponding element 13 of the distal end portion 5b. By this positioning, the lower end of the contact element 11 comes into electrical contact with the corresponding pad 33 (FIG. 10) of the circuit support 30a. In this assembled state, the upper part of the sealing element 12 lies on the end flat surface of the distal portion 5b. (The sealing element 12 is shown in a non-elastically compressed state, as mentioned in the corresponding details of FIGS. 4 and 15 for example).

[0053] And the annular fixing element 6 is placed over the distal end portion 5b provided with the detection unit 10 from below. In various preferred embodiments, compensation means and / or sealing means are provided between the fixing element 6 and the sensing element 3, and are designed in particular to achieve axial compensation and / or sealing with respect to the peripheral annular portion of the membrane of the sensing element 3. In the illustrated case, a compensation ring and / or a sealing ring 14 is provided for this purpose (see also FIG. 5), preferably a flat annular element made of, for example, Teflon®, which is pre-inserted into the element 6 and located on the flange 6b.

[0054] Note that since the airtightness is guaranteed by element 12 in any case, element 4 may be absent or may be replaced by a technically equivalent element. The presence of element 14 is desirable to avoid the possibility of damage to the membrane 3a by directly bonding to the metal of the tubular element 6 (e.g., as a result of deformation or the possibility of thermal expansion).

[0055] The peripheral wall 6a of the fixing element 6 surrounds the sensing element 3 and at least a part of the distal end portion 5b. And this peripheral wall 6a is fixed to the distal end portion 5b. As shown in FIG. 15, the flange 6b of the element 6 holds the detection unit 10 in a predetermined position with respect to the distal end portion 5b, and the sealing element 14 is set therebetween.

[0056] For fixing, in various embodiments, the engaging portion 4 defines outwardly a seating portion 4b to which the corresponding upper part of the peripheral wall 6a of the element 6 is coupled. In various embodiments, the element 6 is made of a metallic material, and the fixing to the seating portion 4b is performed by mechanical deformation such as clinching or rolling. For this purpose, the seating portion 4b preferably has a surface that generally flares upward. Preferably, the operation of fixing the element 6 is performed while slightly compressing the element 14 in order to obtain or improve the airtightness or elastic compensation function.

[0057] As can be seen in FIG. 15, following the fixing of the element 6, the sealing element 12 mainly acts as an axial seal between the upper surface of the sensing element 3 and the above-described end flat surface of the portion 5b. On the other hand, the ring 14 also achieves an essentially axial seal between the flange 6b of the element 6 and the peripheral portion of the membrane of the sensing element 3 (not emphasized in FIG. 15), preventing the possibility of fluid ingress in this region. It will be understood that due to the presence of element 12 and / or element 14, the attachment of the unit 10 is essentially elastic. The use of the elastic contact element 11 also contributes to this elastic attachment.

[0058] In addition to ensuring the seal, the above-described elastic type of attachment enables compensation for mechanical stresses that may damage the sensor, such as vibrations during use and / or mechanical stresses due to the attachment operation of the sensor in the user device, and these risks are increased in the case of the sensitive element located at the distal end of the engagement portion that must be inserted into the duct. This elastic attachment can also correct for possible different thermal expansions of the related components when directly exposed to the fluid, which may be more pronounced in the distal end region of the engagement portion as needed.

[0059] In the assembled state, the upper ends of one or more protrusions 24, 24' of the positioning body may abut against the corresponding surface 5a' of the distal end portion 5b (and may be slightly spaced therefrom to enable the above-described elastic attachment, in which case they function as stops in the event of excessive stress).

[0060] Figs. 16 and 17 schematically show two possible attachment forms of the device 1 in a duct of a user device, such as a fuel cell system. In these figures, reference numeral 50 denotes a general fluid duct F in which pressure must be detected, and reference numeral 51 denotes a lateral or radial tubular passage of the duct 50 for installing the device 1.

[0061] In the case of Fig. 16, the tubular passage 51 has a smaller axial extent (length) than the engagement portion 4 of the device 1, but can still receive the external seal element 7. In this way, at least the distal end portion of the component 4 provided with the associated detection unit 10 projects into the duct 50. In this form, the membrane of the sensitive element is maximally exposed to the fluid, except for its peripheral annular region (which does not deform for detection purposes), and is covered and thus protected by the flange 6b of the fixing element and the possible compensation and / or seal element 14. It will be understood that in such a form, there is no location where moisture can accumulate, or at least it is limited, so that possible icing will not affect the correct operation of the device 1.

[0062] FIG. 17 relates to a different mounting form in which the tubular passage 51 has a greater axial extent (length) than the engaging portion 4 of the device 1. In this case, the engaging portion 4 provided with the associated detection unit 10 is in a position recessed (not protruding) with respect to the duct 50. However, even with such a configuration, the same effect as described above can be obtained with respect to the reduction of the locations where moisture present in the fluid F may accumulate.

[0063] The installation forms of FIGS. 16 and 17 can also be used in the case of the modified embodiments described below.

[0064] It should be noted that in the installation forms of FIGS. 16 and 17, at least a part of the sensing element 3 or the detection unit 10 is protected by the tubular passage 51, in particular by the annular element 6.

[0065] FIG. 18 shows a possible modified embodiment in which the flange 6b of the element 6 is replaced by a plurality of holding elements 6b' protruding radially inward, i.e., essentially L-shaped, and nevertheless performing the functions shown above for the said flange 6b. The small size of the holding elements 6b', i.e., the presence of free space between these elements 6b', reduces the area where condensed water may accumulate on the membrane 3a, and as a result, further reduces the risk of ice formation on the membrane.

[0066] The fact that the unit 10 forms an operable assembly pre-assembled by itself allows for various alternative forms of corresponding fixing means.

[0067] FIGS. 19 to 21 illustrate the case where the unit 10 is adhered to the distal end portion 5b of the engaging portion 4. As can be seen in particular from FIGS. 20 and 21, many of the concepts already described above also apply in this case, but preferably, in this case, the distal end portion 5b is configured to present a lower annular wall 5b'' or a tubular portion that at least partially surrounds the sensing element 3 as well.

[0068] In this case, in order to ensure both mechanical fixation and airtight sealing, a layer of annular adhesive 40 may be disposed between the relevant opposing surface of the part 5b and the sensing element 3. Therefore, the elements 12 and 14 in the previous figures are not indispensable in this case. The fixing element or unit 10 is represented here by the adhesive 40.

[0069] In various embodiments, the adhesive 40 is elastic and creates a sealing element that is substantially similar in functional terms to that shown previously at 12, enabling elastic compensation if necessary or even allowing for a minimum movement of the unit 10 relative to the end 5b.

[0070] Figures 22 to 24 illustrate the case where the unit 10 is fixed to the distal end portion 5b of the engagement portion 4 by a fixing element 6' having a structure similar to the element 6 described previously, and thus has an annular body having a peripheral wall 6a and a lower flange 6b protruding radially inward. Also in this case, the peripheral wall 6a preferably has a shape that surrounds at least a part of the unit 10, in particular at least its sensing element 3, and a part of the distal end portion 5b.

[0071] In the illustrated case, the engagement portion 4 and the fixing element 6' are formed of a plastic material and are preferably welded or adhered on the opposing surfaces of the engagement portion 4 and the fixing element 6, for example welded or adhered along an annular fixing path, with the detection unit 10 interposed and fixed together.

[0072] In this case, a mechanical fixing requirement is obtained by welding or adhesion while ensuring an airtight seal. Therefore, the additional elements as shown previously at 12 and 14 are not necessarily required, but may be present.

[0073] Figures 25 to 27 illustrate a further possible way of fixing the unit 10 to the distal end portion 5b of the engagement portion 4 according to an approach similar to that of the embodiments of Figures 19 to 21. Also in this case, the distal end portion 5b includes a peripheral wall or a lower tubular portion 5b’’ designed to surround at least a part of the sensing element 3. Further, the portion 5b has on the outside an undercut 5c in which a passage is defined that is in fluid communication with the interior of the cavity C’.

[0074] After positioning the unit 10 with respect to the lower end of the portion 5b and the corresponding cavity C’, a mass of fixing material 45 is poured or injected into the cavity through the hole 5d, and this mass results in a fixing element, such as an electrically insulating seal and an adhesive resin, that fills the gap between the inner surface of the portion 5b, i.e., the inner surface of the cavity C’, and a part of the detection unit 10.

[0075] Preferably, the fixing material 45 is introduced in such an amount that it penetrates between the tubular portion 5b’’ and the outer peripheral surface of the sensing element 3, as can be seen, for example, in Figure 27, and at least a part of the positioning body 20 and the circuit support 30a is enveloped by this material 45. Also in this case, polymerization of the material 45 ensures both mechanical fixation and an airtight seal and does not require additional sealing elements.

[0076] In various embodiments, the pressure sensing element 3 can comprise sensor means for detecting the temperature of the fluid F. Temperature detection can be useful, for example, for correcting pressure measurement values or for implementing corrective measures when the fluid tends to reach a potentially harmful temperature (for example, if an excessive decrease in temperature that could lead to the freezing of possible accumulated moisture is detected, a heating element can be activated).

[0077] Figures 28 to 29 relate to the case where a temperature sensor 60, for example a positive temperature coefficient (PTC) thermistor, is provided inside the membrane 3a. The sensor 60 can be advantageously realized by a thick film deposition process such as screen printing technology, for example, which is also a technology that can be used for the definition of the detection element 3d in FIG. 9 and the corresponding conductive tracks (these elements are inside the membrane 3a). From FIG. 28, it can be seen that the thickness of the temperature sensor 60 is smaller than the height of the chamber 3f defined between the substrate 3b and the membrane 3a, and thus the temperature sensor does not prevent the elastic deformation of the membrane. In this case, inside the membrane 3a, there is a conductive track for transmitting the signal from the sensor 60, which is connected to at least two pins 3e in a manner known per se.

[0078] Considering that the realization of the temperature sensor 60 obtained by the shown process can use the same process for both obtaining the temperature sensor and obtaining the element 3d (FIG. 9) for detecting the deformation of the membrane, it is particularly convenient and effective because the sensor 60 is in direct contact with the membrane 3a and its outside is directly exposed to the fluid (see, for example, FIGS. 16 to 17). In this regard, it should be noted that the membrane 3a is directly exposed to the fluid flow and is directly surrounded by the fluid. The membrane 3a is thin and preferably made of a material distinguished by good thermal conductivity (for example, a ceramic material such as alumina). In this way, the membrane 3a can quickly transmit temperature changes to the sensor 60 even when the latter is in a protected position inside the same membrane.

[0079] By the way, the temperature sensor can be obtained in various ways, for example, as illustrated in FIGS. 30 to 31. In this solution, the temperature sensor 60 is also arranged inside the membrane 3a, but in this case, it is composed of surface mount components (or SMDs). In this case, the thickness of the sensor 60 can be larger than the height of the chamber 3f, and a space or recess 61 is defined so that the upper part of the sensor 60 can be accommodated in the substrate 3b of the sensing element 3 without preventing the bending of the membrane 3a.

[0080] In various embodiments, the pressure sensing element 3 may comprise heating means to prevent or eliminate the possibility of freezing by residual moisture in the case of gaseous fluids or by liquid in the case of liquid fluids.

[0081] FIG. 32 shows a case where a heater 62, such as a resistor screen-printed, is provided inside the membrane 3a. Also in this case, if necessary, the substrate 3b may be provided with a space or recess 63 for accommodating the upper part of the heater 62 so as not to prevent the bending of the membrane 3a. Also in this case, inside the membrane 3a, a conductive track for supplying the heater 62 connected to at least two pins 3e is provided. Also in this case, the membrane 3a is thin and preferably formed of a material (such as alumina described above) distinguished by good thermal conductivity, whereby the membrane itself can rapidly transfer the heat generated by the heater 62, and the problem of freezing can be avoided or solved. The operation of the heater 62 can be managed by the internal electronics of the device 1 or by external electronics to which the device 1 is interfaced via connectors (2a, 8).

[0082] As can be seen, in a possible variant embodiment, the control circuit 30 can be obtained directly on the upper surface of the substrate 3b, in which case the circuit support 30a and the body 20 are unnecessary.

[0083] The fixing of the device 1 to the duct 50 (FIGS. 16 to 17) into which the fluid to be detected flows may be achieved by using various fixing means such as screws or similar screw members, or by using a bayonet coupling, or by welding, or by the thread on at least a part of the outer surface of the engaging portion 4. In the latter case, the thread described above is illustrated in FIG. 33 indicated by 4C.

[0084] To avoid the presence of the external seal element 7, i.e., to use a threaded coupling of the type shown having the same thread 4c that performs the function of the seal element, in such a case, the thread 4c may extend further, outside the engaging portion 4, i.e., up to the region where the distal end portion 5b extends. Such a case is shown in FIG. 34.

[0085] FIG. 35 schematically shows a further fixing case where the external seal element 7 is not necessarily present. In this embodiment, the body 2, i.e., its engaging portion 4, is relatively fixed to the passage 51 of the duct 50 by fixing means made of a fixing material 65 such as resin. In such a case, the resin performs both the mechanical fastening function and the sealing function.

[0086] When providing the external seal element 7, it can have a circular cross-section as in the previous embodiment, or can have a square cross-section, or can be a lip seal ring.

[0087] Regardless of the design type, the seal element 7 (or the means replacing it) is preferably located between the two ends 5a and 5b of the engaging portion 4, upstream of the detection unit 10 (thus upstream of the sensitive element 3) with respect to the insertion direction of the engaging portion 4 into a corresponding passage such as the distal end portion 5b or the passage 51 of the duct 50, and also upstream of the means used to fix the unit 10 to the distal end portion 5b.

[0088] From the given description, the features and advantages of the present invention are clear.

[0089] The proposed solution is structurally simple, economical, and highly reliable because the detection unit, which includes at least a pressure-sensitive element and the control electronics of the device, is pre-assembled, especially with the help of a positioning body, and can then be easily and quickly attached to the support, even in a fully automated manner. The preferred design that enables the use of elastic contact elements further simplifies the assembly of the device and reduces the possibility of stress on the detection unit. Considering that the engagement part supporting the detection unit can simply be inserted into the corresponding passage, the installation of the device at the operating position is also simplified, and at this time, the sensitive element is protected from the surroundings in any case and does not contact the surface of the above passage, and there is no risk of possible mechanical stress being applied to the detection unit.

[0090] It is obvious to a person skilled in the art that numerous modifications are possible for the pressure sensor device described as an example without departing from the scope of the present invention defined by the following claims.

[0091] A surface-mounted temperature sensor (or SMD) may also be provided outside the membrane 3a with a possible protective layer (for example, a glassy type). Similarly, for example, a temperature sensor of the PTC type can also be screen-printed outside the membrane 3a together with a corresponding protective layer (for example, a glassy type). In such cases, it is schematically illustrated in FIGS. 36 to 38. The above-described temperature sensor outside the membrane 3 is indicated by 60’, and the above-described protective layer is indicated by 66. In this type of embodiment, the sensitive element 3 is provided with appropriate connection elements (such as conductive tracks and / or metallized holes, etc.) in a known manner to transmit signals corresponding to the two pins 3e. Obviously, this type of modification can be used in all the embodiments described in this specification.

[0092] Figures 39 to 41 show, by way of example, the case of the sensitive element 3 in which the membrane 3a is smaller than the diameter (or cross-sectional dimension) of the corresponding substrate 3b, and in particular the material layer 3c does not prevent the former from being fixed to the latter, and an annular seal element and / or a compensating element 14 is arranged between the flange 6b of the element 6 and the annular region on the lower surface of the substrate 3b radially outside the membrane 3a. In this case, the membrane 3a is preferably smaller than the diameter (or cross-sectional dimension) of the passage 6c defined by the same flange, but this is not an essential feature. This type of embodiment can prevent possible assembly or mounting stresses or thermal deformations from being transmitted to the membrane 3a.

[0093] As described above, the control circuit 30 can also be obtained on the upper surface of the substrate 3b of the sensitive element 3. In such an embodiment, the functions of the circuit support 30a and the positioning element 20 described above can be obtained by such a substrate 3b. Thus, in these embodiments, the pre-assembled detection unit has a sensitive element that supports the control circuit directly, that is, without passing through the positioning element 20.

[0094] An example of this type is shown in FIGS. 42 and 43, the detection unit is generally designated 10', and the sensitive element is generally designated 3'. In such an embodiment, the substrate 3b may include at least two different parts, in particular an upper part having a diameter or cross-sectional dimension smaller than that of the lower part. In the non-limiting example shown, the substrate 3b has a lower part 3b' having a diameter substantially similar to the diameter of the membrane 3a and an upper part 3b'' with a reduced diameter (without prejudice to the possibility of a variant of the type shown in FIGS. 40 to 41).

[0095] On the upper surface of the substrate 3b, here on the upper surface of the portion 3b'', the control circuit 30 is obtained and comprises corresponding elements - for example, the elements previously indicated by 31, 31a, 33 - and corresponding conductive connection tracks not shown (as an alternative, part of the electronics or control circuit of the device may be on the circuit support 30 and part on the upper surface of the portion 3b'' of the substrate 3b). In this case, the upper part of the pin 3e of the sensing element 3 projects only slightly from the substrate 3b and / or can be replaced by pads on which the corresponding conductive tracks of the circuit 30 extend.

[0096] The upper part 3b'' of the substrate is at least partially received within the cavity C' of the distal end portion 5b and shaped to enable the positioning of the axial seal element 12, as shown in FIG. 43. Further, the portion 3b'' can be configured such that one or more zones of its upper surface abut one or more corresponding axial positioning surfaces 5a' of the type described above.

[0097] Advantageously, the body of the substrate 3b can also define a seat or recess (here indicated by 25') for coupling with the corresponding element 13 of the distal end portion 5b, for example on the outer peripheral surface of its upper part 3b'', in order to specify an unambiguous positioning for the unit 10'.

[0098] If necessary, the printed circuit board 30a for the circuit 30 can be provided in any manner in the embodiments of FIGS. 42 - 43, for example adhered to the upper surface of the substrate 3' or otherwise constrained.

[0099] It will be understood that the concepts illustrated with reference to FIGS. 42 - 43 can also be used in all the embodiments described previously.

Claims

1. A pressure sensor device for fluids, particularly gaseous fluids, comprising a support (2) and a detection arrangement associated with the support (2), The aforementioned detection arrangement is A pressure-sensitive element (3) having a detection film (3a), A circuit arrangement (3e, 8, 11, 30) includes a control circuit (30) having a printed circuit support (30a) and an electrical connection element (3e) that electrically connects the pressure-sensitive element (3) to the printed circuit support (30a). It is equipped with, The pressure-sensitive element (3) is associated with the support (2) such that a substantial portion of the detection film (3a) is directly exposed to the outside of the support (2) and can be reached by the fluid (F). The support (2) has an engaging portion (4) configured for insertion into the passage (51) of the fluid duct (50), the engaging portion (4) has a distal end portion (5b) to which the pressure-sensitive element (3) is restrained. The printed circuit support (30a) is associated with a positioning body (20) associated with the pressure-sensitive element (3), and the electrical connection element (3e) restrains the printed circuit support (30a) to the pressure-sensitive element (3) while the positioning body (20) is at least partially set between the printed circuit support (30a) and the pressure-sensitive element (3), thereby forming a detection unit (10). The apparatus wherein the detection unit (10) is fixed to the distal end portion (5b) of the engagement portion (4) by at least one fixing element (6; 6'; 40, 45).

2. The distal end portion (5b) of the engaging portion (4) is shaped to house at least a portion of the detection unit (10), which includes at least a part of the printed circuit support (30a) and / or at least a part of the positioning body (20). The apparatus according to claim 1.

3. The distal end portion (5b) of the engaging portion (4) defines one or more stationary or axial positioning surfaces (5a) for at least one of the positioning body (20) and the pressure-sensitive element (3). The apparatus according to claim 1.

4. The detection arrangement has an electrical connection terminal (8) having each end portion (8b) extending into the engagement portion (4), and an elastic contact element (11) is interposed between the end portion (8b) of the electrical connection terminal (8) and the printed circuit support (30a). The apparatus according to any one of claims 1 to 3.

5. The at least one fixed element (6, 6') comprises an annular body having a peripheral wall (6a) that at least partially surrounds the pressure-sensitive element (3) and surrounds at least a portion of the distal end portion (5b) of the engaging portion (4), The peripheral wall (6a) has at its lower end either a flange (6b) that protrudes radially inward or a plurality of retaining elements (6b') that protrude radially inward. The peripheral wall (6a) is fixed to the distal end portion (5b) of the engaging portion (4), thereby holding the detection unit (10) in a predetermined position relative to the distal end portion (5b) of the engaging portion (4) with respect to the flange (6) or the plurality of retaining elements (6b'), which preferably allows for the interposition of a compensating element and / or a sealing element (14). Preferably, The annular body of the at least one fixing element (6) is made of metal, and the engaging portion (4) defines an external seat portion (4b) to which the corresponding upper part of the peripheral wall (6a) is joined, particularly by mechanical deformation, or The annular body of the at least one fixing element (6) is made of a plastic material, and the peripheral wall (6a) is fixed or welded to a part of the distal end portion (5b) of the engaging portion (4). The apparatus according to any one of claims 1 to 3.

6. The distal end portion (5b) of the engaging portion (4) is shaped to house a part of the detection unit (10), which also includes at least a part of the pressure-sensitive element (3). The apparatus according to any one of claims 1 to 3.

7. The distal end portion (5b) of the engaging portion (4) has a tubular portion (5b) that surrounds at least a part of the outer circumferential surface of the pressure-sensitive element (3). The apparatus according to claim 6.

8. A fixing material (40; 45) is installed between at least one of the circumferential surface and the upper surface of the pressure-sensitive element (3) and the corresponding surface of the distal end portion (5b) of the engaging portion (4), and the fixing material provides at least one fixing element. The apparatus according to claim 6.

9. The engaging portion (4) is externally provided with sealing means (7; 4c; 65), and the sealing means is located at the position of the engaging portion (4), particularly upstream of the detection unit (10), preferably upstream of at least one fixing element (6; 6'; 40; 45), with respect to the distal end portion (5b) of the engaging portion (4). The apparatus according to any one of claims 1 to 3.

10. The support (2) is equipped with position fixing means (4c, 65), and the position fixing means is located at the position of the engaging portion (4), which is in particular upstream of the detection unit (10), preferably upstream of at least one fixing element (6; 6'; 40; 45), with reference to the distal end portion (5b) of the graft portion (4). The apparatus according to any one of claims 1 to 3.

11. The positioning body (20) and the distal end portion (5b) of the engaging portion (4) each have connectable elements (13, 25) configured to identify a specific mounting position of the detection unit (10) relative to the distal end portion (5b) of the engaging portion (4). The apparatus according to any one of claims 1 to 3.

12. The positioning body (20) and the printed circuit support (30a) each have coupling elements (24, 34) configured to specify the mounting position of the printed circuit support (30a) on the positioning body (20), The apparatus according to any one of claims 1 to 3.

13. The engagement portion (4) is provided with at least one shaft seal ring (12) positioned between the distal end portion (5b) and the detection unit (10), The apparatus according to any one of claims 1 to 3.

14. At least one of the temperature sensor (60) and the heating resistor (62) is associated with the detection film (3a), particularly its inner surface, and / or the pressure-sensitive element (3') includes a substrate (3b) on which the detection film (3a) is fixed by a fixing material (3c), and the circuit support and positioning body obtained by the substrate (3b) are provided. The apparatus according to any one of claims 1 to 3.

15. A pressure sensor device for fluids, particularly gaseous fluids, comprising a support (2) and a detection arrangement associated with the support (2), The aforementioned detection arrangement is A pressure-sensitive element (3;3') having a detection film (3a), A circuit configuration (3e, 8, 11, 30) including a control circuit (30) and a connecting element for electrically connecting the pressure-sensitive element (3; 3') to the control circuit (30) and It is equipped with, The pressure-sensitive element (3; 3') and / or the control circuit (30) are configured to be fixed to the distal end portion (5b) of the engaging portion (4) of the support (2), preferably by a fixing and protective element (6), or preferably by a distal end portion (5b) shaped for this purpose. The pressure-sensitive element (3') includes a substrate (3b) on which the detection film (3a) is fixed via a fixing material (3c), The control circuit (30) is obtained on the upper surface of the substrate (3b) and / or on a printed circuit support constrained to the upper surface of the substrate (3b) of the pressure-sensitive element (3'), forming a detection unit (10) in the apparatus.

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