MANUFACTURING METHOD AND ELECTRONIC SYSTEM FOR TIRES

Abstract

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

Description

Title of the invention: MANUFACTURING METHOD AND electronic SYSTEM for TYRES Field of the invention

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

[0002] In the field of transport, vehicles often have an obligation to control the inflation pressure of the mounted assemblies when these are pressurized by a fluid under a pressure higher than atmospheric pressure in order to guarantee the correct behavior of the tire and consequently that of the vehicle, which ensures the safety of the vehicle's passengers or other road users. Beyond the alert to be issued in the event of a significant loss of pressure leading to the immobilization of the vehicle, it is also necessary to be able to detect incorrect inflation pressure due to the natural and continuous porosity of the tires in order to optimize the operation of the mounted assembly. This second functionality of electronic systems for controlling inflation conditions requires increased precision of their measurement chain.However, electronic systems embedded in the wheel rim are often subject to temperature jumps due to their proximity to sometimes hot components such as those in the braking system such as brake discs, shoes or brake drums. Thermal changes also affect the accuracy of the measurement of the physical parameters of the fluid cavity of the mounted assembly.

[0003] In addition, for vehicles carrying heavy loads such as heavy goods vehicles or buses, the inflation pressures of the mounted assemblies are increased, of the order of 9 bars instead of an inflation pressure of 2 to 3 bars for private vehicles. This increased pressure tends to thermo-mechanically constrain conventional electronic systems which can sometimes cause mechanical deformations of the electronic systems at the level of their encapsulation system leading to altering the measurement chain by modifying the measured pressure by modifying, for example, the open section on the fluid cavity or a lesser sealing of the electronic system subjecting the electronic elements to pressures damaging their operation. These deformations mechanical causes a malfunction of the measuring chain of the electronic system which then loses measurement accuracy. In addition, impurities or humidity present in the fluid cavity of the assembled assembly can alter the electronic components of the electronic system when they are in communication with the environment, which is why sealing of the electronic system is desired. Conventionally, the encapsulation devices of the electronic components consist of the definitive and sealed assembly of two compartments. At least one of the compartments is provided with an orifice for communication with the external environment at the level of the sensors measuring the physical parameters of the fluid. The sealing system of the encapsulation device consists of positioning a seal, generally silicone, at the level of the orifice.The crushing of the seal between the compartment provided with the orifice and the measuring sensor outside the active zone of the sensor ensures the sealing of the electronic system. If solutions aiming to mechanically resize the encapsulation device or redesign its sealing exist, these alternative solutions result in an increase in the cost price of the electronic system and / or an increase in the mass of the electronic system embedded in the tire. These consequences make the use of such improved electronic systems in the field of transport on pressurized tires, particularly for heavy goods vehicles, economically unreliable. In addition, the encapsulation device has a certain thickness which gives it its structural rigidity and the volume offered by this encapsulation device is not reduced to the strict minimum. Thus, the spatial footprint of current electronic systems remains bulky.

[0004] The object of the invention which follows aims to propose an economical technical solution in order to achieve sealing of the electronic system for tires allowing on the one hand an optimized occupation of the space of the electronic system and on the other hand an optimized operation of the electronic system, in particular 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 of manufacturing an electronic system for a tire comprising the following steps: • Composition of an electronic card comprising a printed circuit on which are fixed at least one sensor for measuring the physical parameter of a fluid, a battery, a microcontroller; • Coating of the outer surface of the electronic card with an adhesion primer; • Placement inside a mold, the geometric volume of which presents an axis of revolution, of the entire electronic card arranged so that the electronic card is located in the central zone of the volume of the mold in the direction of the axis of revolution, and so that at least one injection nozzle of the mold has an injector in the plane of the printed circuit capable of injecting a plastic compatible with the adhesion primer in the direction of the electronic card; • Installation of an insert resting on 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 at 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 at a temperature of 230 degrees; • Carrying out a second plastic injection at a pressure between 20 and 40 bars and at a temperature between 150 and 250 degrees, preferably at a pressure of 30 bars and at a temperature of 235 degrees • Cooling of the plastic in the mold for a period T; • Extraction of the insert and opening of the mold.

[0006] The coating of electronic components in a plastic is generally not feasible due to the temperature and pressure levels required for crosslinking the plastic, which induces excessive stresses and deformations of the electronic card, in particular the battery, leading to a degraded geometry of the electronic card or unsatisfactory mechanical connections of the electronic card. Here, the low pressure and low temperature process for the first injection makes it possible not to subject the electronic card to excessive stresses due to the use of a plastic suitable for crosslinking under these thermomechanical conditions.The second injection only aims to fill the still empty space of the mold volume located far from the sensitive elements of the electronic card. Finally, a geometrically stable volume is obtained which allows easy handling of the assembly without mechanical damage to the card. However, to ensure the seal between the electronic card and the plastic, it is necessary to ensure chemical cohesion between these elements. This is achieved by applying an adhesion primer beforehand to the electronic card. This primer first creates a chemical bond between this primer and the elements of the electronic card. Then, during the injection of the plastic in the claimed ranges, chemical adhesion is ensured between the plastic and the primer.The plastic is such that under the pressure and temperature levels, it ends up with a viscosity suitable for migrating over the entire electronic card, occupying all the free space that... is made available to it without creating mechanical constraints on the electronic card that are harmful to its components. In order to ensure the sealing of the electronic card, the first injection is low pressure and low temperature. This allows coating of the electronic card under thermomechanical constraints adapted to the electronic card. Then, the second injection is no longer in direct contact with the sensitive elements of the electronic card already encapsulated, is done at higher pressures and under higher temperatures, it is a phase of rapid filling of the periphery of the first encapsulation of the electronic card to define the external geometry of the encapsulation of the electronic system. And the choice of the encapsulation plastic lies in its rapid crosslinking but at low thermomechanical constraints since the temperature and pressure of the first injection of the plastic are low.It takes place over a period of between 10 and 60 seconds, preferably between 10 and 30 seconds, by natural conduction of the mold dies. In order to ensure the presence of plastic at the level of the electronic card to ensure the sealing function, the injection nozzle is located at the level of the printed circuit which is the area to be sealed as a priority. Then, the fluid plastic migrates towards the walls of the mold where vents are naturally located to evacuate the air contained in the volume of the closed mold. Beyond the thermomechanical conditions of plastic injection, this work on the path of the viscous plastic ensures the sealing of the electronic card. The successive injection phases can be carried out in two separate molds or in a drawer mold.

[0007] However, it is appropriate to create a fluidic channel between the physical fluid parameter measurement sensor and the exterior of the electronic system. This can firstly involve not applying the adhesion primer to the active part of the measurement sensor so that the fluid can act on this area directly. This involves positioning a removable device on the electronic card to obstruct the active part of the measurement sensor while the primer is being applied. This application takes place outside the mold, which does not affect the mold utilization rate and ensures that no chemical bond is created between the injected plastic and the walls of the mold, which can cause moldability problems during the mold opening phase at the end of the injection.In addition, at the mold level, it is necessary to place an insert resting on the active zone of the measurement sensor and extending beyond the volume of the mold in order to create a fluidic channel from the active zone of the measurement sensor to the outside of the electronic system produced at the end of the process.

[0008] Such a method makes it possible to encapsulate the electronic components in a reduced volume which allows them to be protected from the thermomechanical stresses that they will undergo during use on a mounted assembly. This encapsulation also makes it possible to handle the electronic components easily and mechanically reliable, this ensures the proper functioning of the electronic system.

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

[0010] This is an ideal compromise which minimizes the encapsulation device of the electronic components for given electronic components compared to conventional encapsulations in the form of a hollow casing. This also allows a more substantial dimensioning of the electronic components with a fixed overall volume of the encapsulation device. In this second aspect, this allows in particular to increase the dimensions of the battery, which ensures greater autonomy of the electronic system for the same functionalities. Indeed, the capacity of a battery with iso technology is governed by the size of the battery. Finally, with iso autonomy of the electronic system, the increased dimensioning of the battery allows the implementation of additional functionalities, which increases the relevance of the electronic system.

[0011] The minimum thickness between the exterior of the electronic system and the electronic card and especially the filling of the volume internal to 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 undergone by the electronic system in service in a tire due to its structural rigidity.

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

[0013] The purpose of the insert is to create a conduit in fluid communication between the active part of the measurement sensor and the environment external to the electronic system. This conduit must have a small cross-section so as not to create a structural weakness at the level of the encapsulation device which could then deteriorate under strong thermomechanical stresses. In addition, this conduit must not modify the variations in the physical parameter observed in the external environment and measured at the level of the active part of the measurement sensor. Thus, the surface of the fluid conduit, in particular its surface roughness, defines the boundary layer dimension of the fluid where an evolving fluid regime appears. Thus, the dimension of the boundary layer must be small compared to the cross-section of the fluid conduit and constant so as not to create another instability of the fluid regime along the axis of the conduit.Thus, to improve the surface roughness of this duct built on the surface of the insert by crosslinking the injection plastic, it is desirable that the surface coating of the insert is chemically inert with the injection plastic. As a result, no chemical bond is created between the injected plastic and the insert, this will limit the deformation of the duct. fluidic at the time of extraction of the insert from the fluidic conduit or even prevent local tearing of the injection plastic.

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

[0015] The nozzle where the plastic is injected in the viscous state opens onto the inner surface of the mold. The nozzle, and in particular the injector, is not far from the plane of the printed circuit of the electronic card, which ensures that the injected plastic attaches to the external surface of the electronic card during the first injection. This ensures the sealing of the electronic card. Eventually, one or more orifices form on the external surface of the plastic formed by the first injection due to the thermal shrinkage of the plastic, but this does not compromise the sealing of the card or the structural rigidity of the encapsulated electronic system as long as the volume and arrangement of the orifices is judiciously chosen, which is not detrimental to the integrity of the encapsulation device.The conditions of the first plastic injection make it possible to protect against these orifices, in particular the duration of cooling 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 card rests on at least one support located on the internal surface of a die of the mold placed radially internally at the radial end of the electronic card.

[0017] Generally, the element of the electronic card having a radially external part relative to the axis of revolution of the mold is the printed circuit of the electronic card. To hold the electronic card in the mold before the first injection, the peripheral contour of the electronic card rests on one or more supports. These supports located on the internal surface of the mold guarantee axial and radial positioning of the electronic card relative to the axis of revolution of the mold during the first plastic injection. These supports are generally removed during the second plastic injection since the plastic of the first injection having started to cool and resting on a part of the surface of the drawer mold ensures the positioning of the coated electronic card in the mold.In the case of a mold change between the two injections, the orifice within the injected plastic at the level of the active part of the measuring sensor ensures the positioning of the electronic card via the mold insert used to generate this orifice.

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

[0019] Always to position the electronic card in the mold before the first plastic injection, it is possible to use supports, called reinforcements, starting from the internal surface of the mold, for example from the bottom of at least one die of the mold. The electronic card then comes to rest on these reinforcements at the axial ends of the electronic card relative to the axis of revolution of the mold. It is desirable that these axial ends of the electronic card are not sensitive electronic components. Generally these are protrusions of the printed circuit which are not conductive parts of the printed circuit.

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

[0021] This electronic system can be obtained by a molding process by positioning the electronic card entirely in a mold before injecting the plastic in the liquid state. Prior to plastic injection, a metal insert is positioned in the mold between the active part of the measurement sensor and the outside of the mold filling volume in order to constitute the orifice extending from the external surface of the injection plastic to the active part of the measurement sensor. The thickness of plastic from the external surface is at least 0.5 millimeters which guarantees a certain rigidity to the electronic system allowing easy gripping and handling of the electronic system compatible with an automated handling process of the electronic system.

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

[0023] These materials allow a change in state of the plastic by a small variation in temperature and a small variation in pressure. These conditions allow for an injection in liquid form of the plastic inside the mold and a crosslinking of the latter which generates low mechanical constraints. These manufacturing conditions are ideal for the electronic card whose components are sensitive to high temperatures and high pressures of a standard molding process. It allows for encapsulation of the electronic board in a low-constraint manner, 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 orifice of the encapsulating plastic is a truncated cone-shaped cylinder whose diameter is at least 0.8 millimeters.

[0025] The cylindrical, preferably conical, shape ensures rigidity of the orifice with respect to high pressures which will not pass through the orifice, which guarantees the shape of this orifice and therefore a homogeneous pressure along the section of the orifice. The diameter of the orifice ensures that the part of the orifice subjected to edge effects by the fluid circulation within the orifice, i.e. the boundary layer, is small compared to the complete section of the orifice. Thus, the active part of the measurement sensor mainly sees the general regime of the fluid, which guarantees a reliable and little altered measurement of the physical parameter of the fluid which is observed through the measurement sensor.

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

[0027] In order to minimize the dimension of the boundary layer, it is appropriate to minimize the surface roughness of the orifice. The lower this surface roughness, the smaller the thickness of the boundary layer and therefore the share of the boundary layer in the total section of the orifice is small, which improves the reliability of the measurement at the measurement sensor. Here, a roughness of 1.12 micrometers is industrially feasible at 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 relative to the axis of rotation and an internal surface situated radially internal to the tire, and comprising a crown capable of being in contact with the ground, two sidewalls situated on either side of the crown and two beads each situated at the other end of each sidewall capable of being in contact with a wheel rim, the electronic system is fixed on the internal surface of the tire, preferably at the level of the crown.

[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 mounted assembly 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 not just the physical parameters of the fluid 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 fixing of the electronic system on the internal surface of the tire is carried out by means of an elastic fixing device comprising a sole whose external surface is in contact with the tire and whose internal surface forms with a lateral retaining wall a cavity capable of accommodating the electronic system, the electronic system being arranged so that the orifice of the plastic encapsulating the electronic system is open.

[0032] When the tire is equipped with an electronic system, it is conventional for the latter to be housed in an elastic fixing device due to the chemical incompatibility between the material of the device for encapsulating the electronic system and the internal wall of the tire. This fixing device also guarantees easy extraction or insertion of the electronic system, which is appreciable when the electronic system becomes faulty due to exhaustion of its energy source for example. This device ensures adhesion to the internal surface of the tire using conventional state-of-the-art techniques via the external surface of a sole. The internal surface of the sole and the retaining wall delimit a cavity capable of accommodating the electronic system.The retention of the latter in the cavity is ensured by compression of the electronic system due to the elasticity of the retaining wall, the movement of which at its free end is facilitated. These fixing devices are generally made of elastomer for this purpose. The insertion of the electronic system in this fixing device is such that the orifice of the encapsulating plastic is open to the fluid surrounding the tire.

[0033] The invention also relates to a mounted assembly comprising a tire, having an axis of rotation, being delimited by an external surface radially external to the tire relative to the axis of rotation and an internal surface located radially internal to the tire, and comprising a crown capable of being in contact with the ground, two sidewalls located on either side of the crown and two beads each 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 fluid cavity of the mounted assembly in fluid communication with an electronic system, the electronic system being arranged so that the orifice of the encapsulating plastic of the electronic system opens into the fluid cavity.

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

[0035] This is another 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 mounted assembly when the tire is mounted, inflated on a wheel. The positioning on the wheel generates lower mechanical constraints due to the rigidity of the wheel compared to that of the tire and lower centrifugal or centripetal forces due to the proximity to the axis of rotation of the tire compared to a fixing on the tire. At this time, the electronic system does not observe the deformation of the tire but it can quite measure the physical parameters of the fluidic cavity of the mounted assembly

[0036] According to a second embodiment, the electronic system is fixed to the internal surface of the tire by means of an elastic fixing device comprising a sole whose external surface is in contact with the tire and whose internal surface forms with a lateral retaining wall a cavity capable of accommodating the electronic system, preferably at the crown.

[0037] As already mentioned at the envelope level, the positioning is ideal when the electronic system also includes deformation sensors such as a flexometer or an accelerometer making it possible to observe the deformation of the tire and thereby to go back to usual physical quantities linked to the tire such as the load applied, the level of wear or adhesion of the tire on the ground. The fixing device also makes it possible to dampen the vibrations and shocks generated by contact with the ground at each wheel revolution. Brief description of the drawings

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

[0039] [Fig.l] illustrates the first phase of the process for producing the electrical system electronics, that is to say the first injection for the coating of the electronic card 6 of the electronic system according to the invention.

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

[0041] During this first injection, an electronic card 6 is positioned within the mold 400. The electronic card 6 comprises a printed circuit 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 by a system of conductive arms. These arms ensure the geometrical maintenance of the cell relative to the printed circuit 5 and the electrical conduction between the printed circuit 5 and the cell. The circuit also comprises, although not shown in the figure, a microprocessor and a sensor for measuring the physical parameter of the fluid. The microprocessor makes it possible to process, at the level of the electronic card 6, the electrical signals emitted by the measurement sensor. The electronic card 6 generally also comprises a radiofrequency communication system for communicating with the external environment at least to emit the result of the measurement made by the measurement sensor.

[0042] Here, the positioning of the electronic card 6 in the mold 400 occurs according to a first embodiment here by means of at least one support 420 located on the internal surface 410 of the mold 400. This support 420 allows the electronic card 6 to bear 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 over the radially outer contour of the electronic card 6, often at the level of the printed circuit 5 on its non-conductive part. This support 420 makes it possible to position the electronic card 6 axially and radially in the mold 400 in order to achieve a complete coating of the electronic card 6 which is sensitive to thermomechanical constraints, in particular at the level of these electronic components such as the battery. These supports 420 can slide in the mold 400 to be removed after the first injection.At this time, the support of the electronic card 6 is resumed by the encapsulation plastic injected during the first injection and cooled to obtain the rigidity necessary to maintain the electronic card 6.

[0043] Prior to the introduction of the electronic card 6 into the mold 400, the electronic card 6 has been coated with an adhesion primer allowing the fixing of the injection plastic relative to the electronic card 6 and facilitating the crosslinking of the injection plastic. Indeed, as mentioned above, the injection is carried out at low pressure between 10 and 20 bars and at a reasonable temperature for the electronic components. Ironic. This allows the electronic board 6 not to be overly thermomechanically stressed, both in terms of the components and the conductive connections, which improves the mechanical endurance of the electronic board 6 of the electronic system.

[0044] Once the first injection has been made and the injected plastic has cooled, the supports 420 located on the internal surface 410 of the mold 400 are removed to release the electronic system which is made up of the electronic card 6 partially coated with plastic with the exception of the support zones at the level of the printed circuit 5, preferably non-conductive, and the potentially protected zones such as the active zone of the measurement sensor. At the level of the active zone of the sensor, an insert has been installed in the mold 400 in order to obstruct the active zone of the measurement sensor so that it is not covered with plastic during the first injection. This insert is covered with a chemically inert material with the injected plastic in order to facilitate the extraction of the insert and ensure a surface condition of the orifice thus formed in the encapsulating plastic which is compatible with a reliable measurement of the physical parameter of the fluid.

[0045] [Fig.2] illustrates the second injection of the method for producing the electronic system, i.e. the final coating of the electronic card 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 zones of the electronic card 6 in the mold 400 during the first injection. Thus, in [Fig.2], the electronic card 6 underwent a first plastic injection when the electronic card 6 was positioned on vertical pads using inserts bearing on the thermomechanically non-sensitive elements of the electronic card such as non-conductive zones 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 card 6 delimited by the dotted line has been positioned in the mold 400.

[0048] The electronic card 6 here comprises a printed circuit 5 having a plane 7 on which various electronic components are soldered on either side of the plane 7, including a measurement sensor 2, a microcontroller 3 and a battery 4. The electronic card 6 has been partially coated with a plastic 20. A rectilinear orifice opening out of this plastic 20 extends to the active part of the measurement sensor 2. The size of this orifice allows easy insertion of an insert 405 of the mold 400 to the active part of the measurement sensor 2. Due to the first injection, the electronic card 6 coated with plastic has an axis of revolution 21. The radial ends 8 of the electronic card 6 are located on the radially outer edge of the printed circuit 5. On the other hand, the axial end 9 of the electronic card 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 outgrowth of the printed circuit 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 closing mode, delimiting a molding volume 402 delimited by an internal surface 410 of the mold 400. This mold has an axis of revolution 401 which will be made to coincide with the axis of revolution 21 of the coated electronic card 6 resulting from the first injection. This mold has an insert 405 extending to the active part of the measurement sensor by fitting into the opening of the coated electronic card 6. This mold 400 has an injection nozzle 407 located at the contact zone 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 5.

[0050] The fact that the electronic components and the sensitive parts of the printed circuit 5 of the electronic card 6 are already coated or protected by an insert 405 allows a higher injection pressure of the plastic to fill the empty spaces of the volume 402 of the mold 400. Thus, the duration of the injection is improved without fear on the endurance of the electronic system finally generated by this second injection. Thus, the electronic card 6 is coated in an injection plastic 20 having undergone reasonable thermomechanical constraints compared to those that the electronic components of the electronic card 6 can endure.

[0051] [Fig.3] shows a sectional view of the electronic system 1. This system can be generated by the method previously described.

[0052] This electronic system 1 is circumscribed in a cylinder of axis of revolution 21 having a monolithic external surface 22. This electronic system 1 comprises an electronic card 6. This comprises a printed circuit 5 on which are fixed electronic components among which there is a microcontroller 3, a sensor 2 for measuring the physical parameter of fluid and a battery 4. This battery 4 is the arrangement of a battery and conductive arms. The conductive arms are connected to the conductive elements of the printed circuit 5 to provide the electrical energy of the battery which passes through the conductive arms. The electronic card 6 is coated in a plastic 20 having an orifice 25 opening onto the external surface 22 and extending to the active part of the measurement sensor 2. This orifice 25 is preferably cylindrical and has a surface condition whose apparent roughness is of the order of 1.2 micrometers.This electronic system 1 is rigid due to the absence of vacuum which allows for thin walls at the level of the elements on the periphery of the electronic card without harming the endurance of the electronic system 1. Thus, the most thickness. thin plastic between the exterior of the electronic system 1 and the electronic card 6 is of the order of 0.5 millimeters. This gain in thickness due to the complete coating of the electronic card 6 allows the use of larger electronic components at iso volume occupied by the electronic system 1. This makes it possible to improve the energy performance of the electronic system 1 by using for example a battery of larger diameter and therefore of higher power, which improves the autonomy of the electronic system 1 at iso functions.

[0053] [Fig.4] shows a section of a tire 100 according to the invention comprising a crown S extended by two sidewalls F and ending in two beads 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 beads B. A closed cavity is thus delimited, containing at least one fluid under pressure, delimited both by the radially inner surface 130 of the tire 100 and by the outer surface of the wheel. The tire 100 also comprises a surface 140 radially external to the tire 100.

[0054] The reference axis 201 will be noted 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 beads B. The intersection of the reference axis 201 by the median plane 211 determines the center of the tire 200. A Cartesian reference will 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 vertical plane 213, the plane perpendicular to both the median plane 211 and the axial plane 212 passing through the vertical axis 203.

[0055] Any 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 will be defined making an angle 0 relative to the vertical plane 213 around the reference axis 201. The material point of the tire 100 is identified 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 direct trihedron with the unit vectors of the axial 201 and radial 204 directions represents the circumferential direction of the tire casing 100.

[0056] This tire 100 has on the radially inner surface 130 a device fixing device 50 which is fixed to the surface 130 by gluing according to the usual techniques of the state of the art when the fixing device 50 is made of elastomer material. The fixing device 50 is fixed at the top S of the tire casing 100, which improves its endurance since the fixing device thus positioned provides less worry during the operations of mounting or dismounting the wheel on the tire casing 100. Indeed, the fixing device 50 is located in an area remote from the beads B of the tire casing 100. Here, the fixing device 50 is equipped with an electronic system 1 within its open volume which constitutes a housing suitable for receiving the electronic system. As a result, the tire casing 100 is here ready to be mounted on a wheel to constitute a mounted assembly.The electronic system 1 can deliver various functions such as the identification of certain components such as the electronic unit itself, the tire.

[0057] But the electronic system 1 can also be equipped with a pressure and / or temperature sensor in order to evaluate the inflation pressure of the mounted assembly. Finally, it can also be equipped with a sensor directly measuring the curvature of the tire casing such as an accelerometer or a flexometer making it possible to trace back to tire usage graders such as the angular speed, the mileage traveled, the static load applied. All or part of these quantities makes it possible to identify the performance of the tire such as, for example, its wear, its grip or quantities intrinsic to the ground on which the tire rolls.

Claims

Claims

1. Method of manufacturing an electronic system (1) for a tire (100) comprising the following steps: - Constitution of an electronic card (6) comprising a printed circuit (5) on which are fixed at least one sensor (2) for measuring the physical parameter of a fluid, a battery (3), a microcontroller (4); - Coating the outer surface of the electronic card (6) with an adhesion primer; - Placement inside a mold (400), the geometric volume (402) of which has an axis of revolution (401), of the entire electronic card (6) arranged so that the electronic card (6) is located in the central zone of the volume (402) of the mold in 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 card (6); - Installation of an insert (405) resting 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 of between 10 and 20 bars and at a temperature of between 150 and 250 degrees on a part of the geometric volume (402) of the mold, preferably at a pressure of 15 bars and at a temperature of 230 degrees; - Carrying out a second plastic injection at a pressure between 20 and 40 bars and at a temperature between 150 and 250 degrees, preferably at a pressure of 30 bars and at 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 a tire (100) according to claim 1 wherein the electronic card (6) is located at a thickness of at least 0.5 millimeters from the interior surface (410) of the mold (400) in a direction normal to the interior surface of the mold.

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

4. Method for manufacturing an electronic system (1) for a tire (100) according to one of claims 1 to 4 wherein during the first injection, the electronic card (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 card (6).

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

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

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

8. Electronic system (1) for a tire (100) according to one of claims 6 to 7 in which the orifice (25) of the encapsulating plastic (20) is a frustoconical cylinder whose diameter is at least 0.8 millimeters.

9. Electronic system (1) for a tire (100) according to one of claims 6 to 8 in which 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 one of claims 6 to 9, wherein the tire (100) has an axis of rotation (201), being delimited by an external surface (140) radially external to the tire (100) relative to the axis of rotation (201) and an internal surface (130) located radially internal to the tire (100), and comprising a crown (S) capable of being in contact with the ground, two sidewalls (F) located on either side of the crown (S) and two beads (B) each located at the other end of each sidewall (F) capable of being in contact with a wheel rim, the electronic system (1) is fixed to the internal surface (130) of the tire (100), preferably at the crown (S).

11. Tire (100) according to claim 10 wherein the attachment to the internal surface (130) of the electronic system (1) is carried out 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 capable of 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. Mounted assembly comprising a tire (100), having an axis of rotation (201), being delimited by an external surface (140) radially external to the tire (100) relative to the axis of rotation (201) and an internal surface (130) located radially internal to the tire (100), and comprising a crown (S) capable of being in contact with the ground, two sidewalls (F) located on either side of the apex (S) and two beads (B) each located 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 fluid cavity of the assembly mounted in fluid communication with an electronic system (1) according to 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 fluid cavity.

13. Mounted assembly according to claim 12 in which the electronic system (1) is fixed on the wheel, preferably on the wheel rim, very preferably at the level of the wheel valve.

14. Mounted assembly according to claim 12 in which the electronic system (1) is fixed to the internal surface (130) of the tire (100) by means of an elastic fixing device (50) comprising a sole whose external surface is in contact with the tire (100) and the internal surface forms with a lateral retaining wall a cavity capable of accommodating the electronic system (1), preferably at the level of the crown (S).

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