manufacturing method and device for encapsulating electronic components of an electronic system for tires

Abstract

The invention relates to an encapsulation component (120) of an electronic system (1) comprising: A rigid casing (300) comprising: A first and a second surface (311, 321) separated by a thickness E; Said rigid casing (300) comprises a cylindrical through-hole (350); An elastic seal (150) inserted into the through-hole (350) of the rigid casing (300) and extending perpendicular to the second surface (321) of the rigid casing (300) over a distance H3; Characterized in that the orifice (350) has a first (320) and a second shoulder (330), in that the orifice (350) extends from this second shoulder (330) over a height H2, in that the elastic seal (150) comprises a cylindrical orifice (151) coaxial with the axis of rotation (351) of the orifice (350) and in that the elastic seal (150) is in direct contact with the rigid casing (300) over the entire orifice (350). Fig. 2

Description

Title of the invention: manufacturing method and device for encapsulating the electronic components of an electronic system for tires Field of invention

[0001] The present invention relates to the field of electronic systems on board tires for 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 thermomechanically 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 elements electronic components to pressures that damage their operation. These mechanical deformations cause the measuring chain of the electronic system to malfunction, which then loses measurement accuracy. Conventionally, the encapsulation device for electronic components consists of the definitive and sealed assembly of two compartments. At least one of the compartments is equipped with a communication orifice 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 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.

[0004] The object of the invention which follows is to propose an economical technical solution in order to achieve sealing of the electronic system for tires allowing optimized operation of the electronic system, in particular when these are used in environments with high inflation pressure. Description of the invention

[0005] The invention relates to a method for manufacturing a sub-component of a device for encapsulating the electronic elements of an electronic system for a tire, comprising the following steps: • During a first phase: Production of a rigid casing by heating then injection of a thermoplastic into a first mold comprising at least two matrices: • The first matrix comprising a first surface, defining a first surface SI of the rigid casing, having a first cylindrical element of diameter DI projecting along a first axis of revolution; • The second die comprising a second surface, defining a second surface S2 of the rigid casing, having a second projecting cylindrical element, with an axis of revolution which can be coaxial with the first axis of revolution when the first mold is closed, with a diameter D2 greater than the diameter DI of the first cylindrical element and the second cylindrical element extends axially over a height H2; • At least one of the two projecting elements extending axially in the form of a cylinder coaxial with the axis of revolution of the cylindrical element over a diameter D3 smaller than the two diameters DI and D2 of the cylindrical elements over a length greater than or equal to the distance between the first two cylindrical elements when the mold is closed, preferably the other projecting element having a cylindrical hollow coaxial with the cylindrical element with a diameter adjusted to the diameter D3; and • During a second phase: Production of a sub-component by injection via a nozzle then cooling of a thermoelastic elastomer in a second mold capable of accommodating the rigid casing, the second mold comprising at least two dies: • The at least one third matrix comprising a third surface bearing on the first surface of the rigid casing and obstructing the cylindrical orifice of the rigid casing; • The at least one fourth matrix comprising a fourth surface bearing on the second surface of the rigid casing, this second face having a non-opening cylindrical orifice whose axis of revolution is coaxial with the axis of revolution of the cylindrical orifice of the rigid casing and whose diameter is greater than or equal to the diameter of the orifice of the rigid casing and extending along the axis of revolution (304) over a height H3; • The at least one third die or the at least one fourth die comprising a rectilinear insert coaxial with the axis of rotation of the orifice of the rigid casing, extending at least to the bottom of the cylindrical orifice of the at least fourth die or at least to the first face of the fourth die; and The insert (502) is covered with a material chemically inert with respect to the thermoelastic elastomer.

[0006] Such a method makes it possible to produce a rigid casing which can withstand the stresses exerted by the inflation pressure without deforming too much, which guarantees the geometry of the casing when it contributes to the encapsulation device. Thus, the sealing of the electronic system will be ensured.

[0007] This rigid casing has an orifice passing through the rigid casing which will put the two physical environments separated by the rigid casing into fluid communication. This orifice has a shoulder system. The shoulder over a radial thickness El, corresponding to the difference in diameters DI and D3, will ensure mechanical anchoring of the elastic sub-component at the rigid casing during the forces generated by the inflation pressure on the electronic system. The force absorption by the shoulder then limits the elastic deformation of the sub-component. This will ensure, for example, that the fluid conduit of the elastic sub-component will not be reduced, which guarantees improved measurement accuracy at the sensor of the physical parameters of the fluid at the electronic system. The second shoulder of the orifice on a radial thickness E2, corresponding to the difference in diameters D2 and D3 greater than the first radial thickness El, ensures mechanical anchoring of the elastic sub-component at the rigid casing during compression of the elastic sub-component during assembly of the encapsulation device.Indeed, the assembly of the encapsulation device reduces the distance between the free edge of the elastic sub-component and the surface S2 of the rigid casing by compressing the elastic sub-component onto the measuring sensor which will be located in the electronic system. It is this compression which ensures the fluidic sealing of the electronic system. For this compression to be axial at the level of the elastic sub-component, the latter is guided by the orifice of the rigid casing over a thickness H2. The cylindrical shape of the orifice of the rigid casing as well as that of the elastic sub-component ensure a radially homogeneous deformation of the elastic sub-component, which guarantees a section of the fluidic channel of the elastic sub-component without unanticipated reduction of its dimension, which improves the accuracy of the sensor measurement.In addition, the thickness H2 of the cylindrical orifice of the rigid casing and the mechanical anchoring of this sub-component in the rigid casing also ensures positioning of the elastic sub-component relative to the geometry of the rigid casing. Thus, despite the geometric dispersions of the production of the rigid casing, the encapsulation device and the positioning of the electronic components in the encapsulation device, it is ensured that the sealing function is performed by the elastic sub-component by better controlling its geometric positioning and its dimension. For this, it is necessary that the elastic sub-component and in particular the internal fluidic channel through it be geometrically positioned relative to the measurement sensor of the electronic system.In addition, the compression ratio of the elastic sub-component at the cylinder between the free end and the surface of the second shoulder of the rigid casing, i.e. the cylinder over the height corresponding to the sum of the heights H2 and H3, must be at least twenty percent and less than forty percent of this height. Finally, in order to constitute a controlled through-orifice geometry of the elastic sub-component with a surface condition that does not present too much roughness, the insert in contact with the thermoelastic elastomer is of rectilinear shape and has an external coating that will not create . adhesion with the thermoelastic elastomer. This ensures that the extraction of the second mold during the production of the elastic sub-component will not generate deformation of the thermoelastic elastomer in contact with the insert, which ensures an adequate and homogeneous surface condition and increased demolding of the sub-component of the encapsulation device consisting of the assembly of the rigid casing equipped with the elastic sub-component.

[0008] The proposed two-phase process, whether it is actually carried out on two mold stations or carried out on one station with a so-called drawer mold to modify the dies, actually requires little attention to detail. Indeed, unlike a conventional process where a prefabricated elastic sub-component is positioned on a rigid casing. Here, the manufacture of the elastic sub-component is carried out directly on the rigid casing. This avoids the step of positioning the elastic sub-component relative to the rigid casing, the step of fixing the elastic sub-component relative to the rigid casing. As a result, the dispersion on the dimension chain is reduced, which makes it possible to improve the miniaturization of the elements of the electronic system. Thus, the electronic system is ultimately more compact with an improved scrap rate, which reduces its cost price for the same sealing function.

[0009] Preferably, the external diameter of the insert is less than a third of the diameter D3, preferably, the insert is cylindrical in shape.

[0010] The insert is rectilinear and the orifice created by the insert in the elastic sub-component takes on the general external shape of the insert. By dimensioning the external diameter of the insert, the diameter of the through orifice of the elastic sub-component is thus dimensioned. The external diameter D3 of the elastic sub-component at the level of the constriction of the elastic sub-component, being radially constrained by the rigid casing, if the external diameter of the insert is less than a third of the external diameter D3 of the constriction, an elastic sub-component is formed of which the smallest part, the constriction, has a section at least proportional to two-thirds of the diameter D3. In addition, the cylindrical shape of the orifice ensures a homogeneous radial distribution of the stresses on the orifice, which ensures a homogeneous and minimal deformation of the orifice of the elastic sub-component.

[0011] Preferably, the radial thickness El of the first element, corresponding to the difference between the diameter DI and the diameter D3, is greater than 0.2 millimeters, preferably the thickness El is greater than or equal to 0.3 millimeters.

[0012] The contact area between the rigid casing and the elastic sub-component under axial stress generated by the pressure of the fluid cavity of the mounted assembly is dimensioned by this quantity. Such a thickness E1 guarantees that the rigid casing will have a reasonable deformation under an inflation pressure of 10 bars and that, moreover, it will not be subject to the start of crack propagation up to a inflation pressure of 12 bars.

[0013] Advantageously, the radial thickness E2 of the second element, corresponding to the difference between the diameter D2 and the diameter D3, is greater than 0.5 millimeters, preferably the thickness E2 is greater than or equal to 0.85 millimeters.

[0014] The contact area between the rigid casing and the elastic sub-component under an axial stress generated by the compression of the elastic sub-component is dimensioned by this quantity. Such a thickness E2 guarantees that the rigid casing will have a reasonable deformation for a compression of the elastic sub-component of the order of 50% and that, moreover, it will not be subject to crack initiation at the level of the rigid casing on the contact surface.

[0015] In a particular embodiment, the axial height H2 of the second element is greater than 0.5 millimeters, preferably greater than or equal to 0.8 millimeters.

[0016] The purpose of the axial height H2 is to define the anchoring height of the elastic sub-component in the rigid casing. This anchoring is useful during the compression phase of the elastic sub-component during the assembly of the electronic system, i.e. the final closing of the encapsulation device. In the case where, due to the manufacturing dispersion of the various elements of the electronic system, the compression of the elastic sub-component is found to be inclined in a non-axial manner, this anchoring height compensates for part of the inclination defect, which guarantees a minimum functionality of the sealing of the electronic system and a correct operation of the measurement of the physical parameters of the fluid in communication with the measurement sensor through the opening orifice of the elastic sub-component.In particular, despite the lack of inclination during compression, the stresses are distributed over the entire rigid casing so that it retains sufficient mechanical endurance in pneumatics.

[0017] Preferably, the axial height H3 of the non-opening orifice of the at least one fourth matrix is ​​between 0.8 and 1.3 millimeters.

[0018] The elastic sub-component is intended to undergo, as a first stress during its use in an electronic system, an axial compression generated by the reduction in the distance between the two components of the encapsulation device.

[0019] The area of ​​the elastic sub-component of height H3 from the second phase of the process is not radially constrained unlike the area of ​​the elastic sub-component of axial height H2. In fact, this area of ​​height H2 is constrained by the rigid casing. As a result, the area of ​​height H3 will undergo the highest compression rate of the elastic sub-component at the time of assembly of the electronic system which will be closed by the final closure of the encapsulation device. The height H3 therefore controls both the closure of the encapsulation device, its spatial size and its sealing by the compression rate of the elastic sub-component. The proposed height range meets these three constraints by taking into account the dispersion of the elements in the chain of dimensions.

[0020] The invention also relates to a sub-component of a device for encapsulating the electronic elements of an electronic system for tires comprising: • A rigid casing comprising: • A first surface and a second surface separated by a thickness E of material; • Said rigid casing comprises at least one cylindrical through-orifice around an axis of revolution from the first surface to the second surface; • An elastic seal of cylindrical shape around an axis of revolution, inserted in the through-hole of the rigid casing and extending perpendicularly away from the second surface of the rigid casing over a distance H3; • Characterized in that the orifice of the rigid casing has a first shoulder from the first surface SI over a radial thickness E1, in that the orifice of the rigid casing has a second shoulder from the second surface S2 over a radial thickness E2, in that the orifice extends away outwardly from this second shoulder over a height H2, in that the elastic seal comprises a cylindrical orifice coaxial with the axis of revolution and coaxial with the axis of rotation of the through orifice of the rigid casing and in that the elastic seal is in direct contact with the rigid casing over the entire through orifice of the rigid casing.

[0021] Preferably, the rigid casing being made of polyamide, the elastic seal is made of a thermoelastic elastomer included in the group comprising thermoplastic elastomers, vulcanized thermoplastic elastomers.

[0022] If the mechanical anchoring does not necessarily require adhesion between the rigid casing and the elastic sub-component, it is preferable to reinforce this anchoring by chemical compatibility between the materials of the two components making it possible to create chemical bonds between them which will create cohesive forces limiting the movements between the two components. Polyamide having good geometrical strength and good behavior at high temperatures is an ideal candidate for producing the rigid casing by molding, it is necessary that the material of the elastic joint can have a certain level of chemical affinity with the polyamide to guarantee adhesion performance between the two structural components. The proposed lists are materials having this level of chemical affinity with the polyamide.

[0023] Advantageously, the opening of the elastic seal is cylindrical in shape and with a diameter between 0.8 millimeters and 1.5 millimeters, preferably between 1 millimeter and 1.3 millimeters.

[0024] By default the elastic seal is cylindrical, it is preferable that the through orifice of this seal is also cylindrical before keeping an axisymmetric structure of the elastic seal which will not create mechanical singularity at the seal and especially at the through orifice. This axisymmetry of the orifice then ensures a continuous section of the through orifice which does not disturb either the pressure within the orifice or the thermomechanical stresses of the elastic seal during its use. Respecting the diameter range ensures a correct measurement of the pressure of the external environment compared to that of the through orifice by keeping a useful section for the fluid greater than the boundary layer applied to the internal surface of the through orifice. This allows for precision in the measurement of the physical parameters of the fluid coming from the external environment and passing through the through orifice.

[0025] The invention also relates to an electronic system for tires comprising: • An encapsulation device comprising • A sub-component according to the object of the first invention; • A second rigid casing impermeably linked to the sub-component on a closed contour; • Electronic components contained in the encapsulation device comprising at least one sensor for measuring the physical parameter of a fluid. The electronic system is characterized in that the at least one measuring sensor is in contact with the elastic seal of the sub-component arranged so that the active part of the at least one measuring sensor is in fluid communication with a medium external to the electronic system via the orifice of the elastic seal.

[0026] Such an electronic system is both impermeable to impurities present in the fluid of the external environment due to the closure between the sub-component and the second rigid casing and the presence of the elastic seal at the sub-component. Thus, the components sensitive to impurities in the electronic system are protected from them by the encapsulation device. In particular, the electronic components such as the microcontroller, the battery and the connectors of the printed circuit are protected from water, in particular in the event of condensation thereof by cooling after use of the tire for example.

[0027] The invention also relates to a tire comprising an electronic system in which the tire, having an axis of rotation, is delimited by an external surface located radially outside the tire relative to the axis of rotation and an internal surface located radially inside 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. able to be in contact with a wheel rim, the electronic system is fixed on the internal surface of the tire, preferably at the crown, arranged so that the orifice of the elastic seal is free.

[0028] This is the case where the electronic system is installed on the tire in order to measure the physical parameters of the fluid trapped in the fluid cavity formed by the tire when it is mounted on a wheel to form a mounted assembly. Before forming a mounted assembly, the tire after manufacture and possibly stored in a warehouse whose aerological conditions are not those of a premises for a tertiary type human activity. As a result, impurities and in particular liquid water or other fluids may be brought into contact with the tire during this storage or during its handling. The sealing ensured by the encapsulation device and in particular the elastic seal preserves the proper functioning and non-deterioration of the electronic components of the electronic system even in the absence of pressurization of the fluid in the fluid cavity of the mounted assembly.In fact, the sealing is ensured by the closure of the encapsulation device which compresses the elastic seal in a suitable manner.

[0029] Preferably, the fixing on the internal surface of the electronic system is carried out by means of a fixing device comprising a sole whose external surface is in contact with the tire and the internal surface forms with at least one lateral retaining wall a cavity capable of accommodating the electronic system.

[0030] This is a particular embodiment where the fixing of the electronic system on the internal wall of the tire is carried out by a specific part. This specific part, the fixing device, is generally made of elastomer compatible with fixing techniques usually used in the tire industry for fixing elastomer components together even if they are chemically incompatible. In addition, this fixing device being elastic tends to dampen the levels of displacement and / or forces undergone by the electronic system during use of the mounted assembly. In addition, the fixing of the electronic system in the fixing device is not definitive in order to change the electronic system in the event of failure thereof such as a discharge of the battery.Therefore, the attachment of the electronic system in the fixing device is achieved by mechanical anchoring by means of the formation of a cavity capable of accommodating the electronic system. The mechanical anchoring then corresponds to an elastic holding of the electronic system by a deformation under stress of the holding wall forming the cavity which allows an elastic modification of the volume of the cavity. Necessarily, it is necessary that the free end of the hollow orifice of the elastic seal of the encapsulation device opens into the opening of the cavity of the fixing device serving. to the insertion or extraction of the electronic system from the fixing device.

[0031] Finally, 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 the electronic system, arranged so that the orifice of the elastic seal opens into the fluid cavity.

[0032] This is the purpose of the final destination of the electronic system comprising an encapsulation device made watertight by the presence of a hollow seal inserted into the sub-component of the encapsulation device. The compression of the seal, guided by its insertion into the sub-component, during the final and watertight closing of the encapsulation device on a closed contour, due to the positioning of the sub-component on the rigid casing, ensures the sealing of the compartment of the encapsulation device. It is just necessary to ensure that the hollow opens directly onto the fluidic cavity whose physical parameters are to be measured.

[0033] According to a first embodiment, the electronic system is fixed on the wheel, preferably on the wheel rim.

[0034] According to another embodiment, the electronic system is fixed on the internal surface of the tire, preferably at the crown.

[0035] These are two locations in the mounted assembly where the attachment of the electronic system is easily conceivable. On the wheel, and in particular the wheel rim, the mass of the electronic system is low compared to the wheel, taking into account this mass, possibly off-centered compared to the natural axis of rotation of the wheel, does not significantly modify the behavior of the mounted assembly. This is a perfect position for measuring the physical parameters of the fluid cavity of the mounted assembly in steady state. On the tire, and in particular opposite the crown, it is ideally located for measuring deformations of the tire while rolling. Indeed, the electronic system is then capable of measuring the periodic deformation, that is to say at the wheel revolution, of the tire at the level of contact with the ground. Here too, the mass of the electronic system is low compared to that of the crown, which does not modify the mechanical behavior of the tire.Brief description of the drawings.

[0036] 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 appended figures in which the same reference numbers designate identical parts throughout and in which: • [Fig.l] shows a sectional view of the first mold for manufacturing the rigid casing according to the invention; • [Fig.2] shows a sectional view of the second mold for manufacturing the elastic seal of the sub-component of the encapsulation device according to the invention; • [Fig.3] shows a sectional view of the sub-component in a median plane of the elastic joint according to the invention; • [Fig.4] shows a sectional view of the electronic system in a median plane of the elastic joint according to the invention; • [Fig.5] is a three-dimensional view of a tire equipped with an electronic system according to the invention; Detailed description of the embodiments

[0037] [Fig.l] illustrates the first phase of the method for producing the sub-component of the device for encapsulating electronic components according to a preferred embodiment, i.e. producing the rigid casing with a specific arrangement of the mold dies.

[0038] Here we see in section the dies 601 and 602 of the first mold 600 during the closing of the mold. As a result, the dies 601 and 602 are in contact.

[0039] The matrix 601 has a first surface 611 defining the external surface of the rigid casing. On this surface 611 appears a first cylindrical element 612 of diameter DI projecting around an axis of revolution 614. This cylindrical element will make it possible to produce the first shoulder of the rigid casing. In this particular case, this first cylindrical element 612 extends axially using a cylindrical extension 632 around the same axis of revolution 614 on a smaller diameter D3. This element of the matrix makes it possible to define the constriction of the orifice of the rigid casing.

[0040] The second matrix 602 comprises a second surface 621 defining the internal surface of the rigid casing. This second surface 621 has on the one hand a second cylindrical element 622 around an axis of revolution 624, of diameter D2 around an axis of revolution 624. The diameter D2 is larger than the diameter DI due to the greater stresses that the casing will undergo during the constitution of the electronic system compared to the stresses that it will undergo in use on a tire for example. And, this second cylindrical element 622 extends over a height H2 in order to define a radial support for the elastic sub-component which will be produced after the production of the rigid casing. On the other hand, this second cylindrical element 622 has a non-opening cylindrical orifice 642 around the same axis of revolution 624 on a diameter D3 adjusted so that, when the mold 600 is closed, the cylindrical extension 632 of the first cylindrical element 612 can be easily housed in this cylindrical orifice 642. The combination of the extension 632 and the orifice 642 ensures coaxiality of the dies at the level of the projecting elements, which is preferable for defining an axisymmetric geometry of the orifice of the rigid casing which will accommodate the elastic seal of the sub-component of the encapsulation device. Of course, for the demolding of the rigid casing, the elements, and in particular the cylindrical elements, have suitable draft angles. Of course, although not shown in this figure, at least one orifice passing through at least one die allows the injection of the thermoplastic into the closed mold to produce the part.

[0041] [Fig.2] illustrates the second phase of the method for producing the sub-component of the device for encapsulating electronic components according to one embodiment, i.e. producing the elastic sub-component at the orifice of the rigid casing 300.

[0042] Here we see in section the dies 401 and 402 of the second mold 400 during the closing of the second mold. As a result, the dies 401 and 402 are in contact. This second mold can be a mold different from that of the first phase. It can also be the same with a so-called “slider” mold allowing certain geometry of the part to be modified locally according to the phase of the process. At this time, no manipulation of the rigid casing 300 is carried out between the first and second phases of the process.

[0043] The matrix 401 has a third surface 411 bearing on the external surface of the rigid casing 300. This surface 411 obstructs the cylindrical orifice 301 around the axis 304 passing through the rigid casing 300. Here, this matrix 401 comprises a through orifice 501 from the outside of the matrix to the third surface 411 and opening at the level of the orifice 301 of the rigid casing 300 to fill the space of the mold allowing the elastic sub-component to be produced.

[0044] The matrix 402 comprises a fourth surface 421 bearing on the internal surface of the rigid casing 300. This matrix 402 has on the one hand a second hollow cylindrical element 422 starting from the fourth surface 421 around an axis of revolution 424, of diameter here D2, it could have been different. The diameter D2 is larger than the diameter DI because of the greater stresses that the casing will undergo during the constitution of the electronic system compared to the stresses that it will undergo in use on a tire for example. And, this cylindrical hollow 422 extends over a height H3 in order to define a compression height and a contact between the elastic sub-component which will be produced and the sensor for measuring the physical parameter of the electronic system. On the other hand, this second cylindrical element 422 has a insert, here cylindrical 502 around the same axis of revolution 424 and extending axially over a length at least equal to the spacing between the bottom e of the cylindrical hollow 422 and the surface 411 of the third die 401 when the mold is closed. Ideally, the third surface 411 of the die 401 has a cylindrical orifice with a diameter adjusted to that of the element 502 centered on the axis of revolution 304 of the orifice 301 of the rigid casing 300, to allow the penetration of the element 502 into this orifice when the mold 400 is closed. Thus, the coaxiality of the insert 502 with the axis of revolution 304 of the through orifice 301 of the rigid casing 300 is ensured. This insert 501 has a chemically inert surface coating with the thermoelastic elastomer injected into this second mold.This also allows easy demolding of the elastic sub-component at the level of this insert 501 and ensures a suitable surface condition of the through-orifice of the elastic sub-component generated by this insert 501 at the end of the manufacturing process.

[0045] Of course, for the demouldability of the sub-component of the encapsulation device, the elements, and in particular the cylindrical elements, have suitable draft angles.

[0046] [Fig. 3] shows a sectional view of the sub-component 120 of an encapsulation device of an electronic system.

[0047] This sub-component 120 may, preferably, have been produced using the method described above. It is composed of two elements; a rigid casing 300 and an elastic seal 150.

[0048] The rigid casing 300 has a first surface 311 which will be oriented externally to the electronic elements in the encapsulation device and a second surface 321 oriented internally.

[0049] The surface 321 will have a continuous shoulder located laterally outside the surface 321 which will serve to connect the sub-component 120 with the other elements of the encapsulation device to constitute a closed and sealed contour by connecting this shoulder with the other elements of the encapsulation device.

[0050] This rigid casing 300 has a through orifice 350 of cylindrical shape around an axis of revolution 351. This cylindrical orifice 350 has a first shoulder 320 starting from the surface 311 over a radial thickness EL. The orifice 350 has a second shoulder 330 this time starting from the surface 321 over a radial thickness E2 greater than EL. In addition, this second shoulder extends axially over a height H2 towards the surface 321. This height H2 ensures positioning of the elastic seal in the casing and axial guidance thereof during compression of the elastic seal during closing of the encapsulation device.

[0051] In this orifice 350 is housed an elastic seal 150 of cylindrical shape around an axis of revolution 154 coaxial with the axis of revolution 354 of the through orifice 150. This cylindrical seal 150 is in direct contact with the rigid casing 300 over the entire through-orifice 350. The shoulders 320 and 330 of the orifice 350 ensure mechanical anchoring of the seal 150 in the rigid casing 300. In addition, it is possible by acting on the material properties of the rigid casing 300, and in particular on the surface coating of the through-orifice 350, on the one hand and of the elastic seal 150 on the other hand to create chemical bonds between the two components which reinforce the rigidity of implantation of the elastic seal within the rigid casing by preventing, for example, the rotation of the rigid casing relative to the elastic seal. This elastic seal 150 extends axially towards the interior of the encapsulation device over a length H3 in order to come into contact with the electronic elements of the electronic system and in particular the sensor for measuring the physical parameters of the fluid.This height H3 is also dimensioned so that the elastic seal 150 is axially compressed during assembly of the electronic system so that this seal provides a sealing function. A compression of at least 20 percent of the length H3 is necessary for this sealing function for an electronic system for pneumatics.

[0052] Finally, this seal 150 has an orifice 151 centered on the axis of revolution 154 in order to connect the two media initially separated by the encapsulation device. This orifice 151 is generally cylindrical in shape around the axis of revolution 154, here on a diameter of the order of a millimeter, in order to respect the axisymmetry of the elastic seal, which will ensure a homogeneous distribution of the stresses and deformations at the level of the elastic seal 150. In addition, the internal surface of this orifice 150 has a roughness adapted so that the boundary layer which will operate on the internal surface of the orifice 151 is insignificant compared to the useful section of the orifice 151 to improve the measurement accuracy of the physical parameters of the fluid circulating through this orifice 151. Finally, the orifice 151 is dimensioned so that its diameter is less than a third of the diameter of the constriction zone of the elastic seal 150.This constriction zone is generated by the two shoulders 320 and 330 of the rigid casing 300. It corresponds to the minimum material zone which can undergo the highest stresses during the use in service of the elastic seal. The dimension of the orifice 151 ensures a sufficient quantity of material at the constriction so that the elastic seal 150 has sufficient mechanical endurance during its use in an electronic system for pneumatics.

[0053] [Fig.4] shows a section of an electronic system 1 for tires.

[0054] This electronic system 1 is composed here of an encapsulation device comprising a sub-component 120 and a rigid casing 101, and of electronic elements constituting the electronic card, the latter comprising a printed circuit 5 on which are positioned a sensor 2 for measuring the physical parameter of the fluid, a microprocessor 3 and a battery 4.

[0055] The electronic elements are located inside the encapsulation device, being previously positioned on the rigid casing 101 by means of a system of ribs of the rigid casing 101. If the microprocessor 3 and the measurement sensor 2 are soldered to the printed circuit 5 by usual state-of-the-art techniques, a battery is fixed on the printed circuit by a system of conductive arms soldered to the printed circuit / . These arms grip the battery to form the battery 4.

[0056] The sub-component 120 corresponds to that which was described in [Fig.3]., it therefore comprises a rigid casing 300 and an elastic seal 150. This sub-component 120 is arranged relative to the rigid casing 101 having previously received the electronic card so that the free surface of the elastic seal 150 is opposite the active part of the measurement sensor 2 of the electronic card. Then, a compressive force is exerted on the sub-component 120 axially in the direction of the rigid casing 101. This force compresses the elastic seal which has the lowest rigidity of the assembly so as to ensure a compression of at least 20% of the radially free height of the seal 150. This compression ratio ensures a seal of the seal relative to the measurement sensor 2 and therefore of the entire electronic card relative to the through-orifice of the elastic seal 150.

[0057] Finally, a continuous weld 160 is produced on the complete periphery of the encapsulation device while maintaining the compressive force between the sub-component 120 and the rigid casing 101 at the contour delimited by the shoulder laterally external to the rigid casing 300. This weld 160 also ensures the sealing of the electronic system 1 with respect to the external environment. In addition, it ensures the inviolability of the electronic components contained in the electronic system 1. Only the destruction of the weld 160 and thereby of the encapsulation device allows the extraction of the electronic components.

[0058] [Fig. 5] 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.

[0059] 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, of a vertical axis 203 perpendicular to the ground and of 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.

[0060] 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.

[0061] This tire 100 has on the radially inner surface 130 a 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 elastomeric 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 adapted to receive 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.

[0062] 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 parameters such as angular speed, mileage traveled, and the static load applied. All or part of these parameters makes it possible to identify tire performance such as, for example, its wear, its grip or intrinsic quantities of the ground on which the tire rolls.

Claims

1. Claims Method (1000) for manufacturing a sub-component (120) of a device for encapsulating the electronic elements of an electronic system (1) for a tire (100) comprising the following steps: - Production of a rigid casing (300) by heating then injecting a thermoplastic into a first mold (600) comprising at least two dies (601, 602): • The first matrix (601) comprising a first surface (611), defining a first surface S 1 (311) of the rigid casing (300), having a first cylindrical element (612) of diameter DI projecting along a first axis of revolution (614); • The second die (602) comprising a second surface (621), defining a second surface S2 (321) of the rigid casing (300), having a second projecting cylindrical element (622), with an axis of revolution (624) which can be coaxial with the first axis of revolution (614) when closing the first mold, with a diameter D2 greater than the diameter DI of the first cylindrical element (612) and the second cylindrical element (622) extends axially over a height H2; • At least one of the two projecting elements (612) extending axially in the form of a cylinder (632) coaxial with the axis of revolution (614) of the cylindrical element (612) over a diameter D3 smaller than the two diameters DI and D2 of the cylindrical elements (612, 622) over a length greater than or equal to the distance between the first two cylindrical elements (612, 622) when the mold is closed, preferably the other projecting element (622) having a cylindrical hollow (642) coaxial with the cylindrical element (622) with a diameter adjusted to the diameter D3; and Production of the sub-component (150) by injection by through a nozzle then cooling of a thermoelastic elastomer in a second mold (400) capable of receiving the rigid casing (300), the second mold (400) comprising at least two dies (401, 402): • The at least one third die (401) comprising a third surface (411) bearing on the first surface (311) of the rigid casing (300) and obstructing the cylindrical orifice (301) of the rigid casing (300); • The at least one fourth matrix (402) comprising a fourth surface (421) bearing on the second surface (321) of the rigid casing (300), this second face (421) having a non-opening cylindrical orifice (422) whose axis of revolution (424) is coaxial with the axis of revolution (304) of the cylindrical orifice (301) of the rigid casing (300) and whose diameter is greater than or equal to the diameter of the orifice (301) of the rigid casing (300) and extending along the axis of revolution (304) over a height H3;• The at least one third die (401) or the at least one fourth die (402) comprising a rectilinear insert (502) coaxial with the axis of rotation (304) of the orifice (301) of the rigid casing (300), extending at least to the bottom of the cylindrical orifice (422) of the at least fourth die (402) or at least to the first face (411) of the fourth die; and - The insert (502) is covered with a material that is chemically inert with respect to the thermoelastic elastomer.;

2. Method of manufacturing a sub-component of a device for encapsulating the electronic elements of an electronic system for a tire according to claim 1 in which the external diameter of the insert (502) is less than a third of the diameter D3, preferably, the insert (502) is of cylindrical shape.

3. Method of manufacturing a sub-component of a device for encapsulating the electronic elements of an electronic system for tire according to one of claims 1 to 2 wherein the axial height H2 of the second element (622) is greater than 0.5 millimeters, preferably greater than or equal to 0.8 millimeters.

4. Method of manufacturing a sub-component of a device for encapsulating the electronic elements of an electronic system for a tire according to one of claims 1 to 3 in which the axial height H3 of the non-opening orifice (422) of the at least one fourth matrix is ​​between 0.8 and 1.3 millimeters.

5. Sub-component (120) of a device for encapsulating the electronic elements of an electronic system (1) for a tire (100) comprising: - A rigid casing (300) comprising: • A first surface (311) and a second surface (321) separated by a thickness E of material; • Said rigid casing (300) comprises at least one cylindrical through-orifice (350) around an axis of revolution (351) from the first surface (311) to the second surface (321); - An elastic seal (150) of cylindrical shape around an axis of revolution (154), inserted into the through-orifice (350) of the rigid casing (300) and extending away perpendicularly from the second surface (321) of the rigid casing (300) over a distance H3;Characterized in that the orifice (350) of the rigid casing (300) has a first shoulder (320) from the first surface SI (311) over a radial thickness E1, in that the orifice (350) of the rigid casing (300) has a second shoulder (330) from the second surface S2 (321) over a radial thickness E2, in that the orifice (350) extends away outwardly from this second shoulder (330) over a height H2, in that the elastic seal (150) comprises a cylindrical orifice (151) coaxial with the axis of revolution (154) is coaxial with the axis of rotation (351) of the orifice (350) passing through the rigid casing (300) and in that the elastic seal (150) is in direct contact with the rigid casing (300) over the entire orifice (350) passing through the rigid casing (300).;

6. Sub-component (120) of a device for encapsulating the electronic elements of an electronic system (1) according to claim 5 wherein the rigid casing (300) being made of polyamide, the elastic seal (150) is made of a thermoelastic elastomer included in the group comprising thermoplastic elastomers, vulcanized thermoplastic elastomers.

7. Sub-component (120) of a device for encapsulating the electronic elements of an electronic system (1) according to one of claims 5 to 6 in which the opening orifice of the elastic seal (150) is cylindrical in shape and has a diameter of between 0.8 millimeters and 1.5 millimeters, preferably between 1 millimeter and 1.3 millimeters.

8. Electronic system (1) for a tire comprising: • An encapsulation device comprising: • A sub-component (120) according to one of claims 5 to 7 • A second rigid casing (101) impermeably connected to the sub-component (120) on a closed contour (160); • Electronic components contained in the encapsulation device comprising at least one measuring sensor (2) of a physical parameter of a fluid; Characterized in that the at least one measuring sensor (2) is in contact with the elastic seal (150) of the sub-component (120) arranged so that the active part of the at least one measuring sensor (2) is in fluid communication with a medium external to the electronic system (1) via the orifice (151) of the elastic seal (150).

9. A tire (100) comprising an electronic system (1) according to claim 8, 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 initially at the level of the top (S), arranged so that the orifice (151) of the elastic seal (150) is free.

10. Tire (100) according to claim 9 wherein the fixing on the internal surface (130) of the electronic system (1) is carried out by means of a fixing device (50) comprising a sole whose external surface is in contact with the tire (100) and the internal surface forms with at least one lateral retaining wall a cavity capable of accommodating the electronic system (1).

11. 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 crown (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 mounted assembly in fluid communication with the electronic system (1) according to claim 10, arranged so that the orifice (151) of the elastic seal (150) opens into the fluid cavity.

12. Mounted assembly according to claim 11 in which the electronic system (1) is fixed on the wheel, preferably on the wheel rim.

13. Mounted assembly according to claim 11 in which the electronic system (1) is fixed on the internal surface (130) of the tire (100), preferably at the level of the crown (S).

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