MANUFACTURING METHOD AND ELECTRONIC SYSTEM FOR PNEUMATICS

Abstract

The invention relates to a manufacturing method and an electronic system (1) for pneumatics (100) comprising: An electronic board (6) including a printed circuit board (5) on which are fixed: A battery (4); A microcontroller (3); At least one sensor (2) for measuring a physical parameter of the fluid; The electronic board (6) being encapsulated in a cylindrical plastic encapsulation (20) about an axis of revolution (21) normal to the printed circuit board (5). Characterized in that the minimum distance between the external surface (22) of the plastic encapsulation (20) and the electronic board (6) is between 0.5 millimeters and 3 millimeters and in that the plastic encapsulation (20) has an opening (25) on the external surface (22) extending into the material to at least one measuring sensor (2). Fig. 3

Description

Title of the invention: Manufacturing process and electronic system for pneumatics. Field of the invention

[0001] The present invention relates to the field of electronic systems embedded on a mounted assembly having as their purpose the measurement of the parameters of the pressurized fluidic cavity of a mounted assembly delimited by at least one tire and one wheel, and particularly the field of electronic systems positioned on the tire. Technological background

[0002] In the transportation sector, vehicles are often required to monitor the inflation pressure of their tire assemblies when these are pressurized by a fluid at a pressure higher than atmospheric pressure. This is to ensure proper tire performance and, consequently, vehicle performance, thereby guaranteeing the safety of vehicle passengers and other road users. Beyond simply issuing an alert in the event of a significant pressure loss that immobilizes the vehicle, it is also necessary to be able to detect incorrect inflation pressure due to the natural and continuous porosity of tires in order to optimize the operation of the tire assembly. This second function of electronic tire pressure monitoring systems requires increased precision in their measurement chain.However, electronic systems mounted on the wheel rim are often subjected to temperature fluctuations due to their proximity to potentially hot components such as brake discs, calipers, or drums. These thermal changes also affect the accuracy of measurements of the physical parameters of the fluidic cavity within the assembled system.

[0003] Furthermore, for vehicles carrying heavy loads, such as trucks or buses, the inflation pressures of the mounted assemblies are increased, to around 9 bar instead of the 2 to 3 bar inflation pressure for passenger vehicles. This increased pressure tends to exert thermo-mechanical stress on conventional electronic systems, sometimes causing mechanical deformations of the electronic systems at the level of their encapsulation system. This can alter the measurement chain by modifying the measured pressure, for example, by changing the cross-section exposed to the fluidic cavity or by reducing the sealing of the electronic system, subjecting the electronic components to pressures that damage their operation. These deformations Mechanical factors can lead to malfunctions in the electronic system's measurement chain, resulting in a loss of measurement accuracy. Furthermore, impurities or moisture present in the fluidic cavity of the assembled unit can damage the electronic components when they are in contact with the environment; therefore, a sealed electronic system is essential. Typically, electronic component encapsulation devices consist of a permanent, sealed assembly of two compartments. At least one of these compartments has an opening for communication with the external environment at the level of the sensors measuring the fluid's physical parameters. The sealing system of the encapsulation device involves positioning a gasket, usually silicone, at the opening.The compression of the seal between the compartment containing the orifice and the measuring sensor, outside the sensor's active area, ensures the electronic system's watertightness. While solutions exist to mechanically resize the encapsulation device or redesign its sealing, these alternatives result in an increased cost of the electronic system and / or an increase in the mass of the electronic system mounted on the tire. These consequences make the use of such improved electronic systems economically unfeasible in the field of pressurized tire transport, particularly for heavy goods vehicles. Furthermore, the encapsulation device has a certain thickness that provides its structural rigidity, and the volume it offers is not reduced to the bare minimum. Thus, the overall size of current electronic systems remains considerable.

[0004] The object of the following invention aims to propose an economical technical solution for sealing the electronic system for pneumatics, allowing on the one hand an optimized use of the space of the electronic system and on the other hand an optimized operation of the electronic system, particularly when these are used in environments of high inflation pressure and / or high thermal gradient. Description of the invention

[0005] The invention relates to a method for manufacturing an electronic system for pneumatics comprising the following steps: • Construction of an electronic board comprising a printed circuit board on which are fixed at least one sensor for measuring a physical parameter of a fluid, a battery, a microcontroller; • Coating the outer surface of the electronic board with an adhesion primer; • Placement inside a mold, the geometric volume of which presents an axis of revolution, of the entire electronic board arranged so that the electronic board is located in the central area of ​​the mold volume along the direction of the axis of revolution, and such that at least one injection nozzle of the mold has an injector in the plane of the printed circuit board capable of injecting a plastic compatible with the adhesion primer towards the electronic board; • Installation of an insert supported by the active part of at least one measuring sensor, one end of which is located outside the geometric volume of the mold, • Carrying out a first plastic injection at a pressure between 10 and 20 bars and under a temperature between 150 and 250 degrees on a part of the geometric volume of the mold, preferably at a pressure of 15 bars and under a temperature of 230 degrees; • Performing a second plastic injection at a pressure between 20 and 40 bar and at a temperature between 150 and 250 degrees, preferably at a pressure of 30 bar and a temperature of 235 degrees • Cooling of the plastic in the mold for a duration T; • Extraction of the insert and opening of the mold.

[0006] Embedding electronic components in plastic is generally not feasible due to the temperature and pressure levels required for plastic curing. This induces excessive stress and deformation of the circuit board, particularly the battery, leading to degraded circuit board geometry or unsatisfactory mechanical connections. Here, the low-pressure, low-temperature process for the initial injection avoids subjecting the circuit board to excessive stress by using a plastic specifically designed for curing under these thermomechanical conditions.The second injection is solely intended to fill the remaining empty space in the mold volume located away from the sensitive components of the circuit board. Ultimately, a geometrically stable volume is obtained, allowing for easy handling of the assembly without mechanical damage to the board. However, to ensure a seal between the circuit board and the plastic, chemical cohesion between these components is necessary. This is achieved by applying an adhesion primer to the circuit board beforehand. This primer first establishes a chemical bond between itself and the circuit board components. Then, during the injection of the plastic within the specified ranges, chemical adhesion between the plastic and the primer is ensured.The plastic is such that under certain pressure and temperature levels, it acquires a viscosity suitable for migrating across the entire electronic board, occupying all the available space. is made available without creating mechanical stresses on the electronic board that could be detrimental to its components. To ensure the electronic board is sealed, the first injection is performed at low pressure and low temperature. This allows the electronic board to be encapsulated under thermomechanical stresses adapted to its specific characteristics. Then, since the second injection is no longer in direct contact with the sensitive elements of the already encapsulated electronic board, it is carried out at higher pressures and temperatures. This is a rapid filling phase of the periphery of the first encapsulation of the electronic board to define the external geometry of the encapsulation of the electronic system. The choice of encapsulation plastic lies in its rapid crosslinking under low thermomechanical stresses, since the temperature and pressure of the first plastic injection are low.It takes place over a period of between 10 and 60 seconds, preferably between 10 and 30 seconds, through natural conduction of the mold's matrix. To ensure the presence of plastic at the electronic board level for sealing, the injection nozzle is positioned at the printed circuit board, which is the area to be sealed first. The fluid plastic then migrates towards the mold walls, where vents are naturally located to expel the air contained within the closed mold volume. Beyond the thermomechanical conditions of plastic injection, this process of managing the flow of the viscous plastic ensures the electronic board's seal. The successive injection phases can be carried out in two separate molds or in a slide mold.

[0007] However, it is necessary to create a fluid channel between the sensor measuring the fluid's physical parameter and the outside of the electronic system. This can be achieved, firstly, by not applying the adhesion primer to the active part of the measuring sensor so that the fluid can act directly on this area. This involves positioning a removable device on the electronic board to block the active part of the measuring sensor while the primer is being applied. This application takes place outside the mold, which does not reduce the mold's utilization rate and ensures that no chemical bonding occurs between the injected plastic and the mold walls, which can cause demolding problems during the mold opening phase at the end of the injection process.Furthermore, at the mold level, an insert must be placed, resting on the active area of ​​the measuring sensor and extending beyond the volume of the mold in order to create a fluidic channel from the active area of ​​the measuring sensor to the outside of the electronic system produced at the end of the process.

[0008] Such a process makes it possible to encapsulate electronic components in a small volume, which protects them from the thermomechanical stresses they will undergo during use in an assembly. This encapsulation also allows for easy handling of the electronic components and Mechanically reliable, this ensures the proper functioning of the electronic system.

[0009] Advantageously, the electronic board is located at a thickness of at least 0.5 millimeters from the inner surface of the mold in a direction normal to the inner surface of the mold.

[0010] This is an ideal compromise that minimizes the encapsulation device for electronic components compared to conventional hollow casing encapsulations. It also allows for larger electronic components while maintaining a fixed overall volume for the encapsulation device. In this second aspect, it allows, in particular, for larger battery sizes, ensuring greater autonomy for the electronic system with the same functionalities. Indeed, the capacity of a battery using the same technology is governed by its size. Finally, with the same autonomy for the electronic system, the increased battery size allows for the implementation of additional functionalities, thus enhancing the relevance of the electronic system.

[0011] The minimum thickness between the exterior of the electronic system and the electronic board, and especially the filling of the internal volume of the electronic system, ensure the structural dimensioning of the encapsulation device, which guarantees a certain rigidity of the electronic system. Thus, the volume occupied by the electronic system does not fluctuate despite the thermomechanical stresses experienced by the electronic system in operation within a pneumatic tube, due to its structural rigidity.

[0012] Preferably, the insert is coated with a chemically inert material along with the injected plastic.

[0013] The purpose of the insert is to create a fluidic communication channel between the active part of the measuring sensor and the environment external to the electronic system. This channel must have a small cross-section to avoid creating a structural weakness in the encapsulation device, which could then deteriorate under high thermomechanical stresses. Furthermore, this channel must not alter the variations in physical parameters observed in the external environment and measured at the active part of the measuring sensor. Thus, the surface area of ​​the fluidic channel, particularly its surface roughness, defines the dimension of the fluid boundary layer where an evolving fluidic regime appears. Therefore, the dimension of the boundary layer must be small compared to the cross-section of the fluidic channel and constant to avoid creating further instability in the fluidic regime along the axis of the channel.Therefore, to improve the surface roughness of this conduit, which is constructed on the insert surface by cross-linking the injection-molded plastic, it is desirable that the insert's surface coating be chemically inert to the injection-molded plastic. This prevents any chemical bonding between the injected plastic and the insert, thus limiting conduit deformation. fluidic at the time of extraction of the insert from the fluidic conduit or even prevent local tearing of the injection plastic.

[0014] Most preferably, the mold comprising two dies, at least one injection nozzle is located near the contact surface between the two dies.

[0015] The nozzle into which the viscous plastic is injected opens onto the inner surface of the mold. The nozzle, and in particular the injector, is located close to the printed circuit board plane, which ensures that the injected plastic adheres to the outer surface of the board during the first injection. This ensures the sealing of the board. Optionally, one or more holes may form on the outer surface of the plastic created by the first injection due to thermal shrinkage of the plastic, but this does not compromise the sealing of the board or the structural rigidity of the encapsulated electronic system, provided that the volume and arrangement of the holes are judiciously chosen, which is not detrimental to the integrity of the encapsulation device.The conditions of the first plastic injection help to prevent these orifices, in particular the cooling time of the injected plastic and the maintenance of pressure at the end of injection.

[0016] According to a first particular embodiment, during the first injection, the electronic board rests on at least one support located on the internal surface of a mold matrix placed radially internally at the radial end of the electronic board.

[0017] Generally, the electronic board element with a portion radially outside the mold's axis of revolution is the printed circuit board. To hold the electronic board in the mold before the first injection, the board's peripheral outline rests on one or more supports. These supports, located on the mold's internal surface, ensure axial and radial positioning of the electronic board relative to the mold's axis of revolution during the first plastic injection. These supports are generally removed during the second plastic injection, since the plastic from the first injection has begun to cool and, bearing against a portion of the slide mold surface, ensures the positioning of the embedded electronic board within the mold.In the case of a mold change between the two injections, the orifice within the injected plastic at the active part of the measuring sensor ensures the positioning of the electronic board via the mold insert used to generate this orifice.

[0018] According to a second particular embodiment, during the first injection, the electronic board rests on at least one support located on the internal surface of a mold matrix placed axially externally to the axial end of the electronic board.

[0019] Still to position the electronic board in the mold before the first In plastic injection molding, supports, called reinforcements, can be used, extending from the internal surface of the mold, for example, from the bottom of at least one mold die. The electronic board then rests on these reinforcements at its axial ends relative to the mold's axis of rotation. It is preferable that these axial ends of the electronic board not be sensitive electronic components. Generally, they are protrusions of the printed circuit board that are not conductive parts of the board.

[0020] The invention also relates to an electronic system for pneumatics comprising an electronic card including a printed circuit on which are fixed: • A battery; • A microcontroller; • At least one sensor for measuring a physical parameter of a fluid, comprising an active part sensitive to the physical parameter; The electronic board is encased in a cylindrical encapsulating plastic around an axis of revolution normal to the printed circuit board. The electronic system is characterized in that the minimum distance, along the normal to the external surface of the encapsulating plastic, between the external surface of the encapsulating plastic and the electronic board is between 0.5 millimeters and 3 millimeters, and in that the encapsulating plastic has an opening on its external surface extending into the material to the active part of at least one measuring sensor.

[0021] This electronic system can be obtained by a molding process by fully positioning the electronic board in a mold before injecting the plastic in its liquid state. Prior to plastic injection, a metal insert is positioned in the mold between the active part of the measuring sensor and the outside of the mold's filling volume to form the orifice extending from the outer surface of the injected plastic to the active part of the measuring sensor. The plastic thickness from the outer surface is at least 0.5 millimeters, which ensures a certain rigidity to the electronic system, allowing for easy gripping and handling of the electronic system compatible with an automated handling process.

[0022] Advantageously, the encapsulating plastic material is included in the group comprising polyamides and polyamide hot melt adhesives.

[0023] These materials allow the plastic to change state through a small variation in temperature and pressure. These conditions allow the plastic to be injected into the mold in liquid form, resulting in cross-linking and low mechanical stress. These manufacturing conditions are ideal for electronic boards whose components are sensitive to high temperatures and high pressures of a standard molding process. It allows for encapsulation of the electronic board with minimal stress, which is favorable to the physical integrity of the electronic board and guarantees the functionality of the various electronic components of the electronic system.

[0024] Preferably, the opening of the encapsulating plastic is a frustoconical cylinder with a diameter of at least 0.8 millimeters

[0025] The cylindrical, preferably conical, shape ensures the rigidity of the orifice against significant pressures that will not pass through it, thus guaranteeing the shape of the orifice and consequently a homogeneous pressure along its cross-section. The orifice diameter ensures that the portion of the orifice subjected to edge effects by the fluid circulation within the orifice, i.e., the boundary layer, is small compared to the total cross-section of the orifice. Therefore, the active part of the measuring sensor primarily observes the general fluid flow, which guarantees a reliable and minimally altered measurement of the fluid's physical parameter observed through the measuring sensor.

[0026] Most preferably, the surface roughness of the encapsulating plastic orifice is less than 3.2 micrometers, preferably less than 2.0 micrometers

[0027] To minimize the size of the boundary layer, the surface roughness of the orifice should be minimized. The lower this surface roughness, the smaller the boundary layer thickness, and consequently, the smaller the proportion of the boundary layer in the total orifice cross-section, which improves the reliability of the measurement at the sensor. Here, a roughness of 1.12 micrometers is industrially feasible at a lower cost.

[0028] The invention also relates to a tire comprising an electronic system in which the tire having an axis of rotation, being delimited by an external surface radially external to the tire with respect to the axis of rotation and an internal surface located radially internal to the tire, and comprising a top adapted to be in contact with the ground, two sidewalls located on either side of the top and two ridges located at each other end of each sidewall adapted to be in contact with a wheel rim, the electronic system is fixed on the internal surface of the tire, preferably at the top.

[0029] This is one of the destinations of the electronic system when it is equipped with a pressure sensor and / or a temperature sensor in order to monitor the physical parameters of the pressurized internal cavity of the assembly mounted when the tire is mounted, inflated on a wheel.

[0030] Yes, the electronic system includes other sensors such as an accelerometer, a flexometer used to observe the deformation of the tire and no longer just the physical parameters of the fluidic cavity, especially for example at the moment of its contact with the ground, the location of the electronic system is preferentially at the level of the top of the tire.

[0031] Preferably, the electronic system is fixed to the inner surface of the tire by means of an elastic fixing device comprising a sole whose outer surface is in contact with the tire and whose inner surface forms with a lateral retaining wall a cavity suitable for receiving the electronic system, the electronic system being arranged so that the opening of the plastic encapsulating the electronic system is open.

[0032] When a tire is equipped with an electronic system, it is common practice for this system to be housed in an elastic mounting device due to the chemical incompatibility between the material of the electronic system's encapsulation device and the tire's inner wall. This mounting device also ensures easy removal or insertion of the electronic system, which is particularly useful when the electronic system fails, for example, due to the depletion of its power source. This device ensures adhesion to the tire's inner surface using conventional, state-of-the-art techniques via the outer surface of a tread. The inner surface of the tread and the retaining wall define a cavity suitable for housing the electronic system.The electronic system is held securely in the cavity by compression due to the elasticity of the retaining wall, which facilitates movement at its free end. These retaining devices are generally made of elastomer for this purpose. The electronic system is inserted into this retaining device in such a way that the opening in the encapsulating plastic exposes it to the fluid surrounding the tire.

[0033] The invention also relates to an assembly comprising a tire, having an axis of rotation, being delimited by an external surface radially external to the tire with respect to the axis of rotation and an internal surface located radially internal to the tire, and comprising a top adapted to be in contact with the ground, two sidewalls located on either side of the top and two beads located at the other end of each sidewall, and a wheel, the wheel comprising an axisymmetric rim around the axis of rotation of the tire and a wheel disc, the internal surface of the tire and the external surface of the rim delimit a fluidic cavity of the assembly in fluidic communication with an electronic system, the electronic system being arranged so that the orifice of the plastic encapsulating the electronic system opens into the fluidic cavity.

[0034] According to a first embodiment, the electronic system is fixed on the wheel, preferably on the wheel rim, most preferably at the level of the wheel valve.

[0035] This is another application of the electronic system when it is equipped with a pressure sensor and / or a temperature sensor to monitor the physical parameters of the pressurized internal cavity of the assembly when the tire is mounted and inflated on a wheel. Positioning on the wheel results in lower mechanical stresses due to the wheel's rigidity compared to that of the tire, and lower centrifugal or centripetal forces due to the proximity to the tire's axis of rotation compared to a tire-mounted attachment. At this point, the electronic system does not observe tire deformation, but it can still measure the physical parameters of the fluidic cavity of the assembly.

[0036] According to a second embodiment, the electronic system is fixed to the inner surface of the tire by means of an elastic fixing device comprising a sole whose outer surface is in contact with the tire and whose inner surface forms with a lateral retaining wall a cavity suitable for receiving the electronic system, preferably at the top.

[0037] As already mentioned regarding the casing, positioning is ideal when the electronic system also includes deformation sensors such as a flexometer or an accelerometer, allowing observation of tire deformation and thus the correlation of common physical quantities related to the tire, such as the applied load, wear level, or tire grip on the ground. The fastening device also helps to dampen the vibrations and shocks generated by contact with the ground with each wheel rotation. Brief description of the drawings

[0038] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying figures in which the same reference numbers designate identical parts throughout and in which: • Fig. 1 presents a cross-sectional view of the first injection mold for manufacturing the electronic system according to the invention. • Fig. 2 presents a cross-sectional view of the mold for the second injection for manufacturing the electronic system according to the invention. • Fig. 3 presents a cross-sectional view of the electronic system according to the invention; • Fig. 4 presents a three-dimensional view of a tire equipped with an electronic system according to one embodiment of the invention. Detailed description of the implementation methods

[0039] Figure 1 illustrates the first phase of the process for implementing the electrical system. tronic, that is to say the first injection for the coating of the electronic board 6 of the electronic system according to the invention.

[0040] The mold 400 for the first injection is shown here. It has an axis of revolution 401 and defines a molding volume 402 when the two dies of the mold 400 are closed. Here, this molding volume 402 corresponds to that of the first injection and does not exactly correspond to the final volume occupied by the electronic system at the end of the second injection.

[0041] During this first injection, an electronic board 6 is positioned within the mold 400. The electronic board 6 comprises a printed circuit board 5 on which electronic components are mounted, including a battery 4 consisting of a cell electrically connected to the conductive tracks of the printed circuit board by a system of conductive arms. These arms ensure the geometric stability of the battery relative to the printed circuit board 5 and electrical conduction between the printed circuit board 5 and the battery. The circuit also includes, although not shown in the figure, a microprocessor and a sensor for measuring a fluid physical parameter. The microprocessor processes the electrical signals emitted by the measuring sensor at the level of the electronic board 6. The electronic board 6 also generally includes a radio frequency communication system for communicating with the external environment, at least to transmit the measurement result obtained by the measuring sensor.

[0042] Here, the positioning of the electronic board 6 in the mold 400 is achieved, according to a first embodiment, by means of at least one support 420 located on the internal surface 410 of the mold 400. This support 420 allows the electronic board 6 to be held in place by gravity at its radially outer end 8 relative to the axis of revolution 401 of the mold. Of course, several supports can be distributed around the radially outer contour of the electronic board 6, often on the printed circuit board 5 in its non-conductive part. This support 420 allows the electronic board 6 to be positioned axially and radially within the mold 400 in order to achieve complete encapsulation of the electronic board 6, which is sensitive to thermomechanical stresses, particularly at the level of its electronic components such as the battery. These supports 420 can slide within the mold 400 to be withdrawn after the first injection.At this point, the support of the electronic board 6 is restored by the encapsulation plastic injected during the first injection and cooled to obtain the rigidity necessary to hold the electronic board 6 in place.

[0043] Prior to the introduction of the electronic board 6 into the mold 400, the electronic board 6 was coated with an adhesion primer enabling the injection-molded plastic to adhere to the electronic board 6 and facilitating the cross-linking of the injection-molded plastic. Indeed, as mentioned above, the injection is carried out at low pressure between 10 and 20 bar and at a reasonable temperature for the electronic components. Ironically. This avoids excessive thermomechanical stress on the electronic board 6, both at the component and conductive connection levels, thus improving the mechanical endurance of the electronic board 6 in the electronic system.

[0044] Once the first injection has been completed and the injected plastic has cooled, the supports 420 located on the internal surface 410 of the mold 400 are removed to free the electronic system, which consists of the electronic board 6 partially encased in plastic, except for the support areas on the printed circuit board 5, which are preferably non-conductive, and potentially protected areas such as the active area of ​​the measuring sensor. At the active area of ​​the sensor, an insert has been installed in the mold 400 to block the active area of ​​the measuring sensor so that it is not covered with plastic during the first injection. This insert is coated with a chemically inert material along with the injected plastic to facilitate its removal and ensure a surface finish of the resulting orifice in the encapsulating plastic that is compatible with reliable measurement of the fluid's physical parameters.

[0045] Fig. 2 illustrates the second injection of the process for making the electronic system, i.e. the final coating of the electronic board 6 of the electronic system according to the invention.

[0046] Several options are possible for the second injection depending on the position of the support areas of the electronic board 6 in the mold 400 during the first injection. Thus, in [Fig.2], the electronic board 6 underwent a first plastic injection when the electronic board 6 was positioned on vertical pads using inserts bearing on the non-thermomechanically sensitive elements of the electronic board such as non-conductive areas of the printed circuit 5. These inserts were then removed, revealing cavities opening onto the side walls of the coating resulting from the first injection.

[0047] Here, the result of the first injection, consisting of the coating of the electronic board 6 delimited by the dotted line, has been positioned in the mold 400.

[0048] The electronic board 6 here comprises a printed circuit board 5 having a plane 7 onto which various electronic components are soldered on either side of the plane 7, including a measuring sensor 2, a microcontroller 3, and a battery 4. The electronic board 6 has been partially encapsulated by a plastic 20. A straight opening leading out of this plastic 20 extends to the active part of the measuring sensor 2. The size of this opening allows for the easy insertion of an insert 405 from the mold 400 into the active part of the measuring sensor 2. Due to the initial injection molding, the plastic-encapsulated electronic board 6 has an axis of revolution 21. The radial ends 8 of the electronic board 6 are located on the radially outer edge of the printed circuit board 5. Conversely, the axial end 9 of the electronic board 6 is located in a plane slightly offset from the active part of the measuring sensor 2 but not at the level of the measuring sensor 2. The end 9 is an axial protrusion of the printed circuit board 5 terminating from the plane 7 at a height slightly greater than the active part of the measuring sensor 2

[0049] The mold 400 comprises two dies, shown here in the closed position, defining a molding volume 402 delimited by an internal surface 410 of the mold 400. This mold has an axis of revolution 401 which will coincide with the axis of revolution 21 of the coated electronic board 6 produced by the first injection. This mold has an insert 405 extending to the active part of the measuring sensor by fitting into the opening of the coated electronic board 6. This mold 400 has an injection nozzle 407 located at the contact area between the two dies of the mold 400 so that the plastic injection takes place at the level of the plane 7 of the printed circuit board 5.

[0050] The fact that the electronic components and sensitive parts of the printed circuit board 5 of the electronic board 6 are already encapsulated or protected by an insert 405 allows for a higher injection pressure of the plastic to fill the empty spaces in the volume 402 of the mold 400. Thus, the injection time is improved without compromising the durability of the electronic system ultimately generated by this second injection. Consequently, the electronic board 6 is encapsulated in an injection-molded plastic 20, having undergone thermomechanical stresses that are reasonable compared to those that the electronic components of the electronic board 6 can withstand.

[0051] Fig. 3 presents a cross-sectional view of the electronic system 1. This system can be generated by the process described above.

[0052] This electronic system 1 is contained within a cylinder with axis of revolution 21 having a monolithic external surface 22. This electronic system 1 comprises an electronic board 6. This board includes a printed circuit board 5 on which electronic components are mounted, including a microcontroller 3, a fluid physical parameter measurement sensor 2, and a battery 4. This battery 4 consists of a cell and conductive arms. The conductive arms are connected to the conductive elements of the printed circuit board 5 to supply electrical energy to the cell, which flows through the conductive arms. The electronic board 6 is encased in a plastic 20 having an opening 25 on the external surface 22 extending to the active part of the measurement sensor 2. This opening 25 is preferably cylindrical and has a surface finish with an apparent roughness of approximately 1.2 micrometers.This electronic system 1 is rigid due to the absence of voids, which allows for thin walls at the level of the elements on the periphery of the electronic board without compromising the endurance of the electronic system 1. Thus, the maximum thickness. The thin layer of plastic between the exterior of electronic system 1 and the electronic board 6 is approximately 0.5 millimeters. This reduction in thickness, due to the complete encapsulation of the electronic board 6, allows the use of larger electronic components within the same volume occupied by electronic system 1. This improves the energy efficiency of electronic system 1 by using, for example, a larger diameter battery with a higher power output, thus extending the battery life of electronic system 1 while maintaining the same functions.

[0053] Figure 4 shows a cross-section of a tire 100 according to the invention, comprising a top S extended by two sides F and terminating in two ribs B. In this case, the tire 100 is intended to be mounted on a wheel, which is not shown in this figure, at the level of the two ribs B. This defines a closed cavity, containing at least one pressurized fluid, delimited both by the radially inner surface 130 of the tire 100 and by the outer surface of the wheel. The tire 100 also includes a surface 140 radially external to the tire 100.

[0054] The reference axis 201, corresponding to the reference axis or natural axis of rotation of the tire 100, and the median plane 211, perpendicular to the reference axis 201 and equidistant from the two bead ribs B, shall be noted. The intersection of the reference axis 201 by the median plane 211 determines the center of the tire 200. A Cartesian coordinate system shall be defined at the center of the tire 200 consisting of the reference axis 201, a vertical axis 203 perpendicular to the ground and a longitudinal axis 202 perpendicular to the other two axes. And, we will define the axial plane 212 passing through the reference axis 201 and the longitudinal axis 202, parallel to the ground plane and perpendicular to the median plane 211. Finally, we will call the vertical plane 213 the plane perpendicular to both the median plane 211 and the axial plane 212 passing through the vertical axis 203.

[0055] Every material point of the tire 100 is uniquely defined by its cylindrical coordinates (Y, R, 0). The scalar Y represents the axial distance to the center of the tire 200 in the direction of the reference axis 201, defined by the orthogonal projection of the material point of the tire 100 onto the reference axis 201. A radial plane 214 is defined, making an angle of 0 with respect to the vertical plane 213 around the reference axis 201. The material point of the tire 100 is located in this radial plane 214 by the distance R to the center of the tire 200 in the direction perpendicular to the reference axis 201, identified by the orthogonal projection of this material point onto the radial axis 204. The unit vector perpendicular to the radial plane 214 and forming a right-handed trihedron with the unit vectors of the axial direction 201 and the radial direction 204 represents the circumferential direction of the tire 100.

[0056] This tire 100 has on its radially inner surface 130 a device The fastening device 50 is fixed to the surface 130 by bonding according to conventional prior art techniques when the fastening device 50 is made of elastomeric material. The fastening device 50 is fixed directly above the apex S of the tire 100, which improves its durability since the fastening device, thus positioned, causes fewer problems during the mounting or dismounting of the wheel on the tire 100. Indeed, the fastening device 50 is located in an area away from the bead B of the tire 100. Here, the fastening device 50 is equipped with an electronic system 1 within its open volume, which constitutes a housing adapted to receive the electronic system. Consequently, the tire 100 is now ready to be mounted on a wheel to form a complete assembly.The electronic system 1 can deliver various functions such as the identification of certain components like the electronic organ itself, the pneumatic system.

[0057] But the electronic system 1 can also be equipped with a pressure and / or temperature sensor to evaluate the inflation pressure of the assembled tire. Finally, it can also be equipped with a sensor that directly measures the curvature of the tire, such as an accelerometer or a flexometer, allowing for the determination of tire usage parameters such as angular velocity, mileage, and applied static load. All or some of these parameters make it possible to identify tire performance characteristics such as wear, grip, or intrinsic properties of the surface on which the tire travels.

Claims

Demands

1. A method for manufacturing an electronic system (1) for pneumatics (100) comprising the following steps: - Construction of an electronic card (6) comprising a printed circuit board (5) on which are fixed at least one sensor for measuring the physical parameter of a fluid, a battery (3), a microcontroller (4); - Coating of the outer surface of the electronic board (6) with an adhesion primer; - Placement inside a mold (400), whose geometric volume (402) has an axis of revolution (401), of the entire electronic board (6) arranged so that the electronic board (6) is located in the central area of ​​the volume (402) of the mold along the direction of the axis of revolution (401), and so that at least one injection nozzle (407) of the mold (400) has an injector in the plane (7) of the printed circuit (5) capable of injecting a plastic compatible with the adhesion primer in the direction of the electronic board (6); - Installation of an insert (405) bearing on the active part of at least one measuring sensor (2) one end of which is located outside the geometric volume of the mold, - Carrying out a first plastic injection at a pressure between 10 and 20 bars and under a temperature between 150 and 250 degrees on a part of the geometric volume (402) of the mold, preferably at a pressure of 15 bars and under a temperature of 230 degrees; - Carrying out a second plastic injection at a pressure between 20 and 40 bars and under a temperature between 150 and 250 degrees, preferably a pressure of 30 bars and under a temperature of 235 degrees. - Cooling of the plastic in the mold (400) for a duration T; - Extraction of the insert (405) and opening of the mold (400).

2. Method of manufacturing an electronic system (1) for pneumatics (100) according to claim 1 wherein the electronic board (6) is located at a thickness of at least 0.5 millimeters from the inner surface (410) of the mold (400) in a direction normal to the inner surface of the mold.

3. Method of manufacturing an electronic system (1) for pneumatic (100) according to any one of claims 1 to 2 in which the insert (405) is coated with a chemically inert material with the injected plastic.

4. Method of manufacturing an electronic system (1) for pneumatics (100) according to any one of claims 1 to 4 wherein during the first injection, the electronic board (6) rests on at least one support (420) located on the internal surface (410) of a die of the mold (400) placed radially internally at the radial end (8) of the electronic board (6).

5. Method of manufacturing an electronic system (1) for pneumatics (100) according to any one of claims 1 to 3 wherein during the first injection, the electronic board (6) rests on at least one support located on the internal surface (410) of a die of the mold (400) placed axially external to the axial end (9) of the electronic board (6).

6. Electronic system (1) for pneumatics (100) comprising: - An electronic board (6) comprising a printed circuit board (5) on which are fixed: • A battery (4); • A microcontroller (3); • At least one sensor for measuring a physical parameter of fluid having an active part sensitive to the physical parameter; - The electronic board (6) being enclosed in an encapsulating plastic (20) of cylindrical shape around an axis of revolution (21) normal to the printed circuit board (5); Characterized in that the minimum distance, along the normal to the external surface (22) of the encapsulating plastic (20), between the external surface (22) of the encapsulating plastic (20) and the electronic board (6) is between 0.5 millimeters and 3 millimeters, and in that the encapsulating plastic (20) has an opening (25) on the external surface (22) extending into the material to the active part of at least one measurement sensor (2).

7. Electronic system (1) for pneumatic (100) according to claim 6 wherein the encapsulating plastic material (20) is included in the group comprising polyamides and polyamide hot melt adhesives

8. Electronic system (1) for pneumatics (100) according to any one of claims 6 to 7 wherein the orifice (25) of the encapsulating plastic (20) is a frustoconical cylinder having a diameter of at least 0.8 millimeters

9. Electronic system (1) for pneumatic (100) according to any one of claims 6 to 8 wherein the surface roughness of the orifice (25) of the encapsulating plastic (20) is less than 3.2 micrometers, preferably less than 2.0 micrometers.

10. A tire (100) comprising an electronic system (1) according to any one of claims 6 to 9 in which the tire (100) having an axis of rotation (201), being delimited by an external surface (140) radially external to the tire (100) with respect to the axis of rotation (201) and an internal surface (130) located radially internal to the tire (100), and comprising a top (S) adapted to be in contact with the ground, two sidewalls (F) located on either side of the top (S) and two beads (B) each located at the other end of each sidewall (F) adapted to be in contact with a wheel rim, the electronic system (1) is fixed on the internal surface (130) of the tire (100), preferably at the top (S).

11. Tire (100) according to claim 10 wherein the attachment to the internal surface (130) of the electronic system (1) is achieved by means of an elastic attachment device (50) comprising a sole whose external surface is in contact with the tire (100) and whose internal surface forms with a lateral retaining wall a cavity suitable for receiving the electronic system (1), the electronic system (1) being arranged so that the orifice (25) of the encapsulating plastic (20) of the electronic system (1) is open.

12. Assembled assembly comprising a tire (100), having an axis of rotation (201), being delimited by an external surface (140) radially external to the tire (100) with respect to the axis of rotation (201) and an internal surface (130) located radially internal to the tire (100), and comprising a vertex (S) adapted to be in contact with the ground, two sidewalls (F) situated on either side of the summit (S) and two ridges (B) located each at the other end of each sidewall (F), and a wheel, the wheel comprising an axisymmetric rim around the axis of rotation (201) of the tire (100) and a wheel disc, the internal surface (130) of the tire (100) and the external surface of the rim delimit a fluidic cavity of the assembly mounted in fluidic communication with an electronic system (1) according to any one of claims 6 to 9, the electronic system (1) being arranged so that the orifice (25) of the encapsulating plastic (20) of the electronic system (1) opens into the fluidic cavity.

13. Assembly mounted according to claim 12 in which the electronic system (1) is fixed on the wheel, preferably on the wheel rim, most preferably at the wheel valve.

14. Assembly according to claim 12 in which the electronic system (1) is fixed to the inner surface (130) of the tire (100) by means of an elastic fixing device (50) comprising a sole whose outer surface is in contact with the tire (100) and whose inner surface forms with a lateral retaining wall a cavity suitable for receiving the electronic system (1), preferably at the top (S).

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