Method for manufacturing a tire sensing device
By having the component surface points in the mold design contact or closely approach the spacer, the problem of poor positioning of the tire sensing device during the molding process is solved, and the uniformity of the package and stress reduction are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PIRELLI TYRE SPA
- Filing Date
- 2024-12-17
- Publication Date
- 2026-07-14
AI Technical Summary
In the manufacturing of tire sensing devices, poor positioning of components in the mold during existing technology causes the geometry of the package to deviate from the expected value, resulting in mechanical and thermal stress on the device and the inner surface of the tire.
The mold design ensures that at least three surface points of the component are in contact with or close to the free ends of at least two spacers. By using the coordinated action of protruding elements and spacers during the molding process, the precise positioning and uniform encapsulation of the component are ensured.
It enables precise positioning of components, reduces the non-uniformity of package thickness, and lowers the mechanical and thermal stress on the inner surface of the device and tire.
Smart Images
Figure CN122396598A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing a tire sensing device. Background Technology
[0002] Sensing devices that are fixed to the inner surface of a tire to detect one or more physical parameters of the tire, such as temperature, pressure, acceleration of the inner surface, deformation of the inner surface, etc., are known.
[0003] Document WO2019 / 123118A1 describes a tire sensing device comprising an electronic unit enclosed in an encapsulation material. The encapsulation material comprises: an upper portion in which the electronic unit is enclosed; and a lower portion including a base surface designed to secure the device to the inner surface of the tire.
[0004] Document US2004094251A1 describes a transponder mounted on a tire. Summary of the Invention
[0005] The term "power supply" refers to a component configured to supply electricity, whether the supplied energy is pre-stored, for example, pre-stored in a storage unit (e.g., a battery or capacitor), or the energy is generated and / or received in real time on-site, for example, in an energy recovery or "energy harvesting" device, which may or may not be combined with an energy accumulator.
[0006] The term "internal chamber" refers to the space defined by the inner surface of the tire and the surface of the mounting rim facing the inner surface of the tire during installation.
[0007] The term “precursor material” generally refers to any material suitable for deformation to fill a molded cavity (e.g., liquid, fluid, gel, viscoelastic material, etc.) and said material can be transformed into a polymer material of the encapsulation by curing (e.g., through chemical reaction, change of physical state, crosslinking, etc.).
[0008] The term "surface point" refers to a finitely extended portion of a surface.
[0009] In the case of tire sensing devices, the applicant has noted the need to fully encapsulate the electronic components of the device, as well as the power supply, thereby sealing them in an airtight, liquid-tight, and vapor-tight manner to avoid damage or deterioration of the electronic components.
[0010] For this purpose, the applicant believes that, because it is simple and fast, a method of producing a device that encapsulates in a single molding step is industrially convenient, thereby producing a single-piece and homogeneous package in terms of structure and constituent materials, and essentially entirely surrounding the components including electronic parts and supplies.
[0011] In this context, the applicant found that, in order to achieve the aforementioned complete encapsulation in a single molding step, it is convenient to maintain a predetermined distance between the component and the molding surface, thereby reducing the surface area of the component resting in the mold. This, in turn, can lead to poor positioning of the component in the mold, resulting in deviations in the geometry of the package (e.g., the thickness of the package, especially at the connection surface of the package positioned below the component, such as below the supply / battery) from desired values. This non-uniformity in the thickness of the package below the component results in high mechanical and / or thermal stresses on the inner surface of the device and / or tire.
[0012] Therefore, the applicant has solved the following problem: producing a sensing device in which the components (including electronic units and power supplies) are essentially, i.e., completely sealed by a single package except for any adjacent through openings (such as through openings required for pressure and / or temperature sensors), while limiting or eliminating the mechanical and / or thermal stresses experienced by the device and / or tire during use.
[0013] In summary, the applicant found that bringing at least three surface points of the component into contact or close proximity with corresponding three surface points of at least two spacers of the mold during molding solved one or more of the aforementioned problems.
[0014] According to a first aspect, the present invention relates to a method for manufacturing a tire sensing device.
[0015] Preferably, the method includes: providing a mold having a molding surface defining a molding chamber, wherein the mold includes at least two distinct and separated spacers located in the molding chamber, each spacer having a corresponding free end located at a distance from a corresponding base of the spacer.
[0016] Preferably, the method includes providing a component having an unfolded plane and comprising: - Electronic unit, which includes: -sensor, - Processing unit, and - Transceiver; and - A power supply electrically connected to the electronic unit.
[0017] Preferably, the method includes placing the component into the molding chamber.
[0018] Preferably, the method includes filling the molded cavity with a precursor material of polymeric material, wherein the precursor material also flows at the spacer.
[0019] Preferably, the method includes hardening the precursor material to form an encapsulation of the polymer material, wherein the encapsulation is one-piece and contacts the component, and wherein the encapsulation includes a coupling surface for attaching the sensing device to a tire, the coupling surface being located on a reference plane forming a portion of the molded surface.
[0020] Preferably, during the curing process, at least three surface points of the component remain in contact with or close to corresponding surface points on the free ends of the at least two spacers, wherein the surface points on the free ends of the spacers are positioned to have a predetermined spatial relationship with the reference plane of the molding surface, and wherein the three surface points of the component are positioned to have a predetermined spatial relationship with the unfolding plane of the component to satisfy a predetermined parallelism requirement between the unfolding plane and the connecting surface of the package.
[0021] Preferably, the method includes extracting the sensing device, comprising the package and the components, from the molding chamber.
[0022] According to another aspect, the present invention relates to a sensing device manufactured according to a first aspect of the invention.
[0023] According to a further aspect, the present invention relates to a tire comprising at least one sensing device according to the foregoing aspects of the invention.
[0024] The applicant believes that, because three surface points of the component are in contact or close proximity to corresponding surface points of the free ends of at least two spacers, the positioning of the component in molding can be precisely controlled, while achieving the desired spacing required to obtain the package. In other words, in the event of undesirable mispositioning of the component, the spacers act as endpoints of the travel, thereby achieving precise positioning of the component relative to the molding surface, particularly the desired parallelism between the component and the mating surfaces. This, in turn, allows for a high uniformity of package thickness below the component, at the molding surface. This, in turn, reduces the mechanical and / or thermal stresses experienced on the inner surfaces of the device and / or tire.
[0025] According to at least one of the above aspects, the present invention may have one or more of the following preferred features.
[0026] Preferably, the mold includes protruding elements that project from the molding surface.
[0027] Preferably, it is conceivable that the component is positioned within the molded cavity such that the sensor contacts the protruding element. Additionally, the protruding element can also function as a spacer, in addition to the spacer itself.
[0028] Preferably, during the filling and hardening processes, the method includes keeping the protruding element and the sensor pressed against each other, wherein the precursor material also flows around the protruding element.
[0029] Preferably, the extraction includes separating the protruding element from the sensor to obtain a through opening at the sensor within the package.
[0030] In applications where sensors must be in fluid communication with the internal chambers of a tire, such as pressure and / or temperature sensors, the indentation left by the protruding element within the package creates a through-hole for the sensor. Pressing the sensor and protruding element against each other achieves a sealed contact between them, preventing precursor material from seeping between them, even in cases where low-viscosity liquid precursors are used for molding, which could potentially block the sensor's through-hole.
[0031] Furthermore, the contact between the sensor and the protruding element allows for a defined distance between the component and the molding surface, facilitating subsequent component encapsulation. The applicant believes that pressing the sensor and protruding element against each other during the molding process helps to properly position the component within the mold, even in cases where undesirable thrusts may be exerted on the component by the precursor material, including hydrostatic thrust in the case of liquid precursors. Such contact points constitute constraint points around which the component might potentially tilt, causing the package thickness to deviate from the desired value. The maximum tilt of the component around the contact points is limited due to the contact or proximity of the component's surface points to corresponding surface points on the free ends of the spacers. In other words, the protruding element and spacer work together to provide a precise positioning of the component relative to the molding surface, even in the event of undesirable tilting of the component around the contact point with the protruding element, with the spacer acting as a stroke endpoint.
[0032] Preferably, the protruding element applies an attractive force to the sensor to keep the protruding element and the sensor pressed against each other. In this way, pressure can be applied using the contact between the protruding element and the sensor (which is necessary if the sensor has a through hole), eliminating the need for additional thrust elements and / or contact points during the molding process.
[0033] Preferably, the attractive force is magnetic.
[0034] Preferably, the protruding element comprises a magnet, more preferably a permanent magnet; the sensor comprises a ferromagnetic free surface (e.g., made of ferrous metal). In this way, the aforementioned attractive force is generated simply and effectively.
[0035] In one embodiment, the attraction is pneumatic, for example, by means of a vacuum or depressurization. Preferably, the mold includes an air suction system comprising a duct and a fan, the duct extending inside the protruding element and opening at the sensor, the fan being in fluid communication with the duct. In this way, the protruding element attracts the sensor due to the depressurization created by the fan in the duct.
[0036] Preferably, the transceiver includes an antenna, and is based, for example, on Bluetooth. TM technology.
[0037] Preferably, the component further includes a rigid printed circuit board having a first side and a second side facing each other, wherein the electronic unit is mounted on the rigid board, for example, at least partially mounted on the first side of the rigid board.
[0038] Preferably, the rigid plate (e.g., the first and second surfaces) has a generally circular or elliptical shape.
[0039] Preferably, the sensor is fixed to the first surface.
[0040] Preferably, the rigid plate comprises one or more substrates, such as sheets based on cellulose (e.g., paper), glass fibers (with or without cross-fibers), etc., impregnated with resin (e.g., phenolic resin, epoxy resin, polyamide, or BT / epoxy resin). For example, the rigid plate is made of epoxy glass (e.g., a composite material based on glass fibers orthogonally arranged between two layers made of an epoxy resin matrix). In this way, the desired stiffness and / or electrical insulation are obtained.
[0041] Preferably, the sensor is configured to sense at least one or at least two of the following physical parameters: temperature, pressure, acceleration, and deformation. Preferably, the acceleration has one or more components (axial, radial, and / or tangential). In this way, the sensing device provides particularly useful data for obtaining the condition and / or function of the tire, and / or the condition and / or function of the vehicle on which it is mounted.
[0042] Preferably, the sensor is adapted to sense pressure and / or temperature and is provided with an aperture to allow fluid communication between the sensor and the external environment. Preferably, the aperture corresponds to a through opening in the protruding element and the package. In this way, fluid communication is achieved between the sensor and the internal chamber of the tire.
[0043] Preferably, the power supply includes a power accumulator, and more preferably includes one or more batteries, such as button batteries.
[0044] Preferably, the power supply is fixed to the rigid plate and arranged on the same side as the second side of the rigid plate, more preferably facing and close to the second side, and even more preferably, the power supply and the rigid plate are stacked on top of each other.
[0045] Preferably, the connecting surface has peripheral edges without corners, sharp points, and / or small radii of curvature, for example, it has a five-lobed shape.
[0046] Preferably, the device has an axis perpendicular to the connecting surface.
[0047] Preferably, the package has a free surface located on the side opposite to the coupling surface, and has a surface extension much smaller than that of the coupling surface, for example, at least three or five times smaller.
[0048] Preferably, the through opening faces the free surface.
[0049] Preferably, the package has a side surface that substantially continuously connects the coupling surface and the free surface.
[0050] Preferably, the side surface has a substantially cylindrical symmetry about the axis of the device.
[0051] Preferably, the portion of the side surface near the free surface has a substantially cylindrical or truncated conical shape around the axis of the device.
[0052] Preferably, the side surface tapers away from the connecting surface until it reaches the free surface. In this way, it facilitates extraction from the mold.
[0053] Preferably, the mold has an axis of the mold and a reference plane orthogonal to the axis of the mold.
[0054] Preferably, the mold includes a first half-mold and, more preferably, a second half-mold movable relative to the first half-mold, and even more preferably movable along the axis of the mold, the axis of the mold coinciding with the axis of the device during molding.
[0055] Preferably, it is conceivable to close the mold before the hardening, more preferably by bringing the first and second half of the mold close to each other, and even more preferably after filling the cavity. In this way, a closed cavity can be formed.
[0056] Preferably, the mold, more preferably the first half-mold, includes an insert movable relative to the rest of the mold along the mold's axis, the movable insert including a molding surface forming part of the molding surface. This facilitates the extraction device.
[0057] Preferably, the movable insert includes the protruding element.
[0058] Preferably, the free surface of the package is located at the molded surface.
[0059] Preferably, the distance is taken along the axis of the mold, or along a direction orthogonal to the reference plane.
[0060] Preferably, the reference plane belongs to the second half-mode.
[0061] Preferably, during the filling of the molded cavity, the precursor material also flows at the side surface of the spacer.
[0062] Preferably, the unfolding plane of the component is the main unfolding plane of a rigid plate or a power supply.
[0063] Preferably, the predetermined parallelism requirement is constituted by the angle between the unfolded plane of the component and the connecting surface, the absolute value of which is less than or equal to 3°, preferably less than or equal to 2°, and even more preferably less than or equal to 1°.
[0064] Preferably, the spacer is at least three independent and separate spacers.
[0065] Preferably, the spacer and / or the surface point are at least four, more preferably four in number.
[0066] Preferably, the number of the at least three surface points of the component is equal to the number of the spacers, and each surface point of the component is in contact with or near the free end of the corresponding spacer.
[0067] Preferably, the at least three surface points of the component and / or the spacers are angularly distributed around the axis of the mold, more preferably in a radially distal position away from the axis of the mold.
[0068] Preferably, the at least three surface points of the component are separated from each other; more preferably, they are distributed on the surface of the component; and even more preferably, they are distributed on the first surface of the rigid plate.
[0069] Preferably, the at least three surface points of the component are located at the peripheral edge of the rigid plate. This is to position them at the maximum possible distance and to effectively hold the component in place.
[0070] Preferably, the end of the spacer faces the first surface of the rigid plate.
[0071] Preferably, the rigid plate has a planar shape orthogonal to the axis of the device, including a plurality of radial protrusions distributed along the peripheral edge of the rigid plate to obtain at least two through openings in a mold section orthogonal to the axis of the mold, between corresponding portions of the molding surface and the edge of the rigid plate between each pair of protrusions. In this way, liquid precursors can flow through at least one through opening across the outside of the rigid plate, while air is simultaneously released in the opposite direction through at least one other through opening.
[0072] Preferably, each through opening is located at the midpoint between two adjacent spacers of the at least two spacers. In this way, the precursor material can easily flow from one side of the rigid plate to the other.
[0073] Preferably, each of the at least three surface points of the component is located on a corresponding radial protrusion on the first surface of the rigid plate. In this way, the protrusion also performs the task of achieving the correct positioning of the component.
[0074] Preferably, the rigid plate (including the protrusions) is a single homogeneous body in the constitutive material. In other words, the protrusions are made of the same material as the rest of the rigid plate. This simplifies the manufacture of the protrusions, for example, since the rigid plates are manufactured and supplied in batches from plates attached to each other to form a matrix. When each plate is separated, the four bridging members connecting the plates to four adjacent plates are broken, thus creating four protrusions. In other words, not only can the four existing protrusions be utilized, as they are part of the production process of the rigid plate, but they also do not need to be removed, for example, by milling, as is usually the case. In one embodiment, the rigid plate has a plurality of through openings parallel to the axis of the device and arranged inside the peripheral edge of the rigid plate.
[0075] Preferably, the protruding element and / or the spacer form part of the molded surface of the movable insert.
[0076] Preferably, the side surface of the component, more preferably the side surface of the rigid plate, is located entirely at a non-zero distance from the molding surface. The side surface refers to the side surface relative to the axis of the device. In other words, the component is completely separated from the molding surface except at one or more of the free ends of the possible protruding elements and / or the spacers (these elements, in various combinations, constitute the sole support points of the component in the mold). Preferably, the non-zero distance is less than or equal to 3 mm or 2 mm. In this way, the precursor material can occupy the gap between the molding surface and the side surface of the component, where there are no uncovered points.
[0077] Preferably, the precursor material is a liquid precursor.
[0078] Preferably, the polymer material is a thermosetting polyurethane material (e.g., elastomer PU) or polyurea.
[0079] Preferably, the liquid precursor is a mixture of polyol and isocyanate.
[0080] Preferably, the hardening includes chemically reacting the mixture in the mold.
[0081] Preferably, the filling of the chamber comprises injecting the liquid precursor into the molding chamber by gravity. In this way, molding occurs under ambient pressure, and the forces acting on the component are limited.
[0082] Preferably, the protruding element protrudes upward from the bottom of the molding chamber.
[0083] Preferably, the spacer protrudes upward from the bottom of the molded cavity.
[0084] Preferably, the molded surface of the movable insert faces upward.
[0085] Preferably, the connecting surface faces upwards.
[0086] Preferably, the component is inserted such that the electronic unit is positioned below the power supply. In this way, molding occurs on the thinnest portion of the package facing upwards (the thickness may be less than 1 mm at the periphery of the bonding surface). This arrangement, especially when a closed mold is envisioned, facilitates a uniform distribution of the precursor material across the entire bonding surface of the package. Conversely, where the bonding surface is positioned downwards during molding and the mold must be closed, filling such a thin portion would be much more difficult, particularly in the absence of means to vent air from the molding chamber.
[0087] In one embodiment, the filling comprises low-pressure injection molding of a liquid precursor, and more preferably, the polymer material is a polyamide or polyester material.
[0088] Preferably, the sensing device can be fixed to the inner surface of the tire.
[0089] Preferably, the sensing device is fixed to the inner surface of the tire, more preferably in the crown portion of the tire (i.e., the tire portion at the tread band), for example by an adhesive placed between the connecting surface and the inner surface.
[0090] Preferably, the adhesive is a pressure-sensitive adhesive (PSA). In this way, the device is adhered to the inner surface of the tire through an extremely simple and rapid process. Attached Figure Description
[0091] Figure 1 A schematic partial perspective view of a tire portion including a sensing device manufactured according to the method of the present invention is shown; Figure 2 and Figure 3 Exploded views and cross-sections of a sensing device manufactured according to the method of the present invention are shown schematically, respectively. Figure 4 An exploded view of the mold in the steps of the method according to the invention is shown schematically and in part. Figure 5 A cross-section of the mold during a step of the method according to the invention is shown schematically and partially. Figure 6 and Figure 7 The cross-sections of the mold in the steps of the method according to the invention are shown schematically and partially on two mutually orthogonal cross-sectional planes. Detailed Implementation
[0092] The features and advantages of the invention will become more apparent from the following detailed description of several embodiments presented by way of non-limiting examples of the invention, with reference to the accompanying drawings.
[0093] exist Figure 1 In the figure, reference numeral 10 shows a tire (partial perspective section) which includes a sensing device 1 manufactured according to the present invention.
[0094] As an example, the sensing device 1 is fixed to the inner surface 15 of the tire 10 at the crown portion 16 of the tire 10, i.e., at the tread strip portion of the tire, by an invisible adhesive (e.g., pressure-sensitive adhesive), which is placed between the connecting surface 11 and the inner surface 15 of the device 1.
[0095] Device 1 includes component 2, which includes electronic unit 3 (schematically shown in the figure), which includes sensor 4, processing unit, and transceiver, such as 2.4GHz Bluetooth. TMA transceiver for the technology. As an example, the sensor is adapted to sense pressure and / or temperature and is provided with an aperture (in...). Figure 2 (as can be seen in the image), so that the sensor is in fluid communication with the internal cavity of the tire.
[0096] The assembly also includes a power supply 5, which is electrically connected to the electronic unit by means of two contacts visible in the figure. As an example, the power supply consists of one and only one energy storage device (e.g., a circular planar button cell).
[0097] Preferably, the assembly further includes a rigid printed circuit board 6, such as a rigid printed circuit board made of epoxy glass, having a first side 7 and a second side 8 facing each other. Electronic units 3 are mounted on the rigid plate, for example, partially mounted on the second side and partially mounted on the first side. Preferably, the antennas of the sensors and transceivers are fixed to the first side to allow for effective operation. Preferably, the rigid plate (e.g., the first and second sides) is shown in a plan view orthogonal to the axis 12 of the device. Figure 7 The rigid plate 6 has a generally circular shape and more preferably includes four radial protrusions 16, which are distributed along the peripheral edge of the rigid plate 6 in a uniform manner (i.e., 90°) around the axis 12. Preferably, the protrusions 16 are made of the same material as the rest of the rigid plate.
[0098] Component 2 has a predetermined unfolding plane 32, for example, the mid-emergence unfolding plane of rigid plate 6, such as... Figure 6 As shown.
[0099] Preferably, the power supply 5 is fixed to the rigid plate 6 on one side of the second surface of the rigid plate and at a short but non-zero distance from the second surface (e.g., by means of an electrical contact), and is stacked vertically on the rigid plate.
[0100] Preferably, the device 1 includes a polymer encapsulation 9, which is a one-piece assembly and substantially contacts the entire component, i.e., completely surrounding the component except for a limited area where the component may remain exposed, such as at the sensor aperture and / or any contact points with multiple spacers, as described in more detail below. Preferably, the encapsulation 9 is provided with a flat engagement surface 11, which is intended for securing the sensing device 1 to the inner surface 15 of the tire 10. Preferably, the engagement surface 11 has a five-lobed peripheral edge ( Figure 2 ).
[0101] Preferably, the device has an axis 12 perpendicular to the connecting surface 11.
[0102] Preferably, the package 9 is provided with a free surface 13 on the side opposite to the connecting surface 11, and has a surface extension much smaller than that of the connecting surface 11 (e.g., about seven times smaller). Preferably, the package 9 is provided at the sensor 4, and more particularly at the hole of the sensor 4, wherein the through opening 14 faces the free surface 13.
[0103] Preferably, the package 9 has a side surface 17 that substantially continuously connects the coupling surface 11 and the free surface 13. Preferably, the side surface 17 has a substantially cylindrical symmetry about the axis 12 of the device. Preferably, the entire side surface 17 tapers away from the coupling surface 11. Figure 3 Up to the free surface 13, the portion of the side surface near the free surface is a truncated cone with quasi-axial walls, that is, almost cylindrical, but slightly tapered.
[0104] Figure 3 It shows crossing Figure 2 The vertical cross-section of the device shown is the cross-sectional plane 50.
[0105] Preferably, the mold 20 has a mold axis 21 and a reference plane 22 orthogonal to the mold axis 21, which coincides with the axis 12 of the device 1 during molding.
[0106] Preferably, the mold includes a first half-mold 23 and a second half-mold 24, the second half-mold being movable relative to the first half-mold 23 along the mold axis 21. Preferably, the mold has a molding surface 26 defining a molding chamber 25. Preferably, a portion 29 of the molding surface 26 belonging to the second half-mold 24 lies on a reference plane 22.
[0107] Preferably, the mold 20, more preferably the first half mold 23, includes an insert 27 movable relative to the rest of the mold along the mold axis 21, for example by means of a threaded member arranged below, wherein the movable insert 27 includes a molding surface 28 forming part of the molding surface 26.
[0108] Preferably, the movable insert 27 includes a protruding element 30 projecting from the molded surface 28. Preferably, the protruding element 30 includes or is made of a permanent magnet, and the sensor 4 (e.g., the body of the sensor 4) includes a ferromagnetic free surface, for example, made of an iron-containing metal.
[0109] Preferably, the mold, particularly the insert 27, includes four spacers 31 located in the molding chamber 25, which are separated and independent of each other. Each spacer has a corresponding free end positioned at a distance from its respective base along the mold axis 21. The free ends of the spacers are positioned in a predetermined spatial relationship with a reference plane 22 of the mold. Preferably, the spacers are angularly distributed at equal intervals around the mold axis 21 at the peripheral edge of the insert 27.
[0110] The mold 20 is suitable for use in the manufacturing method of the device 1 according to the invention.
[0111] Preferably, the mold is positioned such that the molded surface 28 of the movable insert 27 is positioned on the bottom of the molding chamber 25 and faces upward (the protruding element 30 protrudes upward from the bottom of the molding chamber 25), while the portion 29 of the molded surface faces downward.
[0112] Preferably, the method includes: positioning component 2 in the molding chamber 25, and positioning sensor 4 (e.g., the hole of sensor 4) in contact with the protruding element 30. Figure 6 Preferably, the insertion component 2 is arranged such that the electronic unit 3 and the rigid plate 6 are arranged below the power supply 5, with the free surface of the sensor 4 facing downwards.
[0113] Preferably, the magnet of the protruding element 30 applies a magnetic attraction to the sensor 4 to keep them pressed against each other throughout the molding process.
[0114] Preferably, the component 2 is positioned by contacting or approaching the corresponding surface points on the free ends of the four spacers 31, respectively, and keeping them in contact or merely in contact during the molding process, wherein the four surface points of the component are positioned to have a predetermined spatial relationship with the unfolded plane 32 of the component 2. For example, the distance between the surface points of the component and the opposite surface points on the spacers is less than or equal to about 1 mm or 0.5 mm, for example, less than or equal to one-tenth of a millimeter. Preferably, each of the four surface points of the component is located on a corresponding protrusion 16 on the first surface of the rigid plate, and thus the end of the spacer 31 faces the first surface of the rigid plate.
[0115] It should be noted that different numbers of spacers 31 may exist, for example, two or three, provided that their dimensions allow at least three surface points of component 2 to rest separately from each other. In the example shown, there are four spacers, the same as the surface points of the component; however, the invention also contemplates embodiments in which the number of spacers is less than the number of surface points, for example, two spacers and three or four surface points. In this case, at least two surface points of the component are in contact with or close to corresponding surface points at the free ends of the same spacers.
[0116] It can be observed that the presence of the permanent magnet facilitates a firm contact between the sensor 4 and the protruding element 30. Under optimal conditions (e.g., the assembly is perfectly aligned with the mold and there is no deformation, such as no deformation of the rigid plate), the four surface points of the rigid plate do not contact the corresponding free ends of the spacers 31, but remain close together. On the other hand, if the plate 6 has a shape slightly different from the nominal shape due to manufacturing and / or process tolerances and / or undergoes a slight tilt with the sensor 4 as the fulcrum, then contact may exist between one or more surface points on the protrusion 16 and the corresponding spacers 31. These contact points act as the end point of travel by limiting the tilt of the assembly 2 and thus satisfying the predetermined parallelism requirement between the unfolded plane 32 of the assembly 2 and the reference plane 22, where the connecting surface 11 is located on the reference plane during molding.
[0117] Preferably, the molded chamber 25 is completely filled with a precursor material of the polymer material, such as a liquid mixture of polyol and isocyanate.
[0118] Preferably, due to the shape of the mold and the positioning of the components within the mold, the liquid mixture is injected into the molding chamber by gravity.
[0119] In order to fully encapsulate the assembly on all its parts, the precursor material flows from top to bottom, from one side of the first surface 7 of the rigid plate 6 across the rigid plate 6 to the area of the molding chamber, and also flows around the protruding element 30 and along the spacer 31 until it reaches the molding surface 28 of the insert 27.
[0120] To this end, the protrusion 16 creates a suitable through-opening 32 between each pair of protrusions 16 and the molding surface 26 in a mold cross section orthogonal to the mold axis 21, through which the liquid precursor flows, such as Figure 7 As shown, the cross-sectional plane coincides with the predefined unfolding plane 32 of component 2.
[0121] Alternatively or additionally, the rigid plate 6 may have multiple through openings (not shown) parallel to the axis 21 of the device and arranged inside the peripheral edge of the plate.
[0122] As an example, such as Figure 7 As shown, the entire side surface of the rigid plate (relative to the axis of the device), especially at the protrusion 16, is located at a (smaller) distance from the molding surface to allow the precursor material to flow into the gap formed between the side surface of the molding surface and the protrusion, thereby binding the entire side surface of the assembly together.
[0123] After closing the mold (e.g., by bringing the second half of the mold into contact with the first half of the mold, such as...) Figure 5As shown (where components and precursor materials have been omitted), it is conceivable to harden the precursor material to obtain encapsulation 9. As an example, hardening occurs by subjecting the aforementioned mixture held in the mold to a chemical range of approximately 2-3 minutes at approximately 50-60°C until a polymer material is formed, which in this case is an elastomeric polyurethane (e.g., BASF). ® Elasturan ® series).
[0124] During molding, the connecting surface 11 corresponds to or is formed by the portion 29 of the molding surface located on the reference plane 22, and the free surface 13 of the package 9 corresponds to the molding surface 28.
[0125] Finally, the device 1 is removed from the molding chamber 25, for example, as the insert 27 moves upward, thereby separating the protruding element 30 from the sensor 4 to obtain a through opening 14 in the package 9.
[0126] As shown in the figure, in addition to the marks left by the protruding element 30, the package 9 also shows marks left by the spacer 31, where, in the case of contact between the protrusion and the spacer 31, the rigid plate 6 (especially at the surface point of the protrusion 16) may be exposed to air. Nevertheless, a seal is still achieved for the electronic unit 3 and the supply 5 in this case, which is due both to the high compatibility and therefore adhesion between the material of the package (e.g., PU) and the rigid plate (e.g., glass fiber epoxy laminate (Vetronite)), and to the fact that there are no electronic components at the protrusion 16.
Claims
1. A method for manufacturing a tire sensing device (1), the method comprising: - Provide a mold (20) having a molding surface (26) defining a molding chamber (25), wherein the mold includes at least two independent and separate spacers (31) located in the molding chamber (25), each spacer having a corresponding free end located at a distance from a corresponding base of the spacer. - Provide a component (2), the component having an unfolded plane (32) and comprising: - Electronic unit (3), the electronic unit includes: - Sensor (4) - Processing unit, and - Transceiver; and - Power supply (5), which is electrically connected to the electronic unit (3); - Place the component into the molding chamber; - The molded cavity is filled with a precursor material of polymer material, wherein the precursor material also flows at the spacer (31); - The precursor material is hardened to form an encapsulation (9) of the polymer material, wherein the encapsulation is one-piece and contacts the component, and wherein the encapsulation (9) includes a coupling surface (11) for attaching the sensing device to the tire, the coupling surface (11) being located on a reference plane (22) forming a portion of the molded surface. During the curing process, at least three surface points of the component remain in contact with or close to corresponding surface points on the free ends of the at least two spacers (31), wherein the surface points on the free ends of the spacers are positioned to have a predetermined spatial relationship with the reference plane (22) of the molding surface, and wherein the three surface points of the component are positioned to have a predetermined spatial relationship with the unfolding plane (32) of the component to satisfy a predetermined parallelism requirement between the unfolding plane (32) and the connecting surface (11) of the package; and - Extract the sensing device (1), which includes the package (9) and the component (2), from the molding chamber (25).
2. The method according to claim 1, wherein, The mold includes a protruding element (30) protruding from the molded surface (26), wherein the sensor (4) contacts the protruding element, wherein during the filling and the hardening, the method includes holding the protruding element (30) and the sensor (4) pressed against each other, wherein the precursor material also flows around the protruding element (30), and wherein during the extraction, the protruding element (30) separates from the sensor (4) to obtain a through opening (14) at the sensor (4) in the package (9).
3. The method according to claim 2, wherein, The protruding element (30) applies a magnetic attraction to the sensor (4) to keep the protruding element (30) and the sensor (4) pressed against each other, wherein the protruding element (30) includes a permanent magnet and the sensor (4) includes a ferromagnetic free surface.
4. The method according to any one of the preceding claims, wherein, The component (2) further includes a rigid printed circuit board (6) having a first side (7) and a second side (8) facing each other, wherein the electronic unit (3) is mounted on the rigid board, wherein the rigid board includes one or more layers of substrate impregnated with resin, wherein the power supply includes one or more batteries, and wherein the power supply is attached to the rigid board and faces and is close to the second side of the rigid board.
5. The method according to claims 2 and 4, wherein, The sensor (4) is fixed on the first surface, wherein the sensor is configured to sense pressure and / or temperature and is provided with a hole for fluid communication between the sensor (4) and the external environment, and wherein the hole corresponds to the through opening (14) of the protruding element (30) and the package (9).
6. The method according to any one of the preceding claims, wherein, The mold (20) includes a first half-mold (23) and a second half-mold (24), the second half-mold being movable relative to the first half-mold along the axis (21) of the mold, and wherein the method includes closing the mold by bringing the first half-mold (23) and the second half-mold (24) closer to each other before the hardening and after filling the cavity, the side surface of the component (2) being entirely located at a non-zero distance from the molding surface (26).
7. The method according to any one of the preceding claims, wherein the predetermined parallelism requirement is constituted by the angle between the unfolding plane (32) of the component and the connecting surface (11), the absolute value of the angle being less than or equal to 3°.
8. The method according to any one of the preceding claims, wherein, The number of the at least three surface points of the component is equal to the number of the spacers (31), and each surface point of the component is in contact with or near the free end of the corresponding spacer.
9. The method according to any one of the preceding claims, wherein, The spacer is at least three independent and distinct spacers, wherein the spacers (31) are angularly distributed around the axis (21) of the mold at locations away from the axis of the mold, wherein the at least three surface points of the assembly are located at the peripheral edge of the rigid plate, and wherein the ends of the spacers face the first surface of the rigid plate.
10. The method according to any one of the preceding claims, wherein, The rigid plate (6) has a planar shape orthogonal to the axis (12) of the device, the planar shape including a plurality of radial protrusions (16) distributed along the peripheral edge of the rigid plate to realize at least two through openings (32) in a section of the mold orthogonal to the axis (21) of the mold, between the molding surface and the edge of the rigid plate (6) including the respective portions between each pair of protrusions (16), wherein each through opening is located in a position between two adjacent spacers of the at least two spacers, and wherein each of the at least three surface points of the assembly is located on the corresponding radial protrusion (16) at the first surface of the rigid plate.
11. The method according to any one of the preceding claims, wherein, The mold includes an insert (27) movable relative to the rest of the mold along the mold axis (21), the movable insert including a molding surface (28) forming part of the molding surface, wherein the movable insert includes the spacer (31).
12. The method according to any one of the preceding claims, wherein, The precursor material is a liquid precursor, wherein the polymer material is a thermosetting polyurethane or polyurea, and wherein the liquid precursor is a mixture of a polyol and an isocyanate, and wherein the curing comprises chemically reacting the mixture in the mold.
13. The method according to any one of the preceding claims, wherein, The spacer (31) protrudes upward from the bottom of the molded chamber (25), wherein the connecting surface (11) faces upward, wherein the component is inserted such that the electronic unit is arranged below the power supply, and wherein filling the molded chamber includes injecting the liquid precursor into the molded chamber by gravity.