D e s c r i p t i o n

The present invention relates to a method of installing a detecting unit within a pneumatic tyre and to a pneumatic tyre equipped with said unit.

On some types of vehicles the necessity is felt to monitor the operating conditions of the tyres and to possibly keep traces of the evolution in time of some parameters representative of this operation.

In particular, when vehicles using tyres of the run flat type are concerned, i.e. tyres capable of ensuring some kilometres of distance covered even in case of tyre deflation, provided some characteristic parameters are complied with such as maximum speed, temperature and maximum distance to be travelled over, the above requirement becomes of the greatest importance for safe use of said types of tyres.

For example, the parameters that are generally considered may be identification code, temperature, pressure, distance run by the tyre, as well as parameters originating from mathematical calculations that can be carried out within the tyre.

To this aim, within the tyre a detecting system can be mounted which may comprise at least one detecting unit, a data control and/or storage unit (such as a microprocessor) and an antenna; said antenna has the task of enabling exchange of radio-frequency signals

with the devices mounted on board the vehicle.

In addition, the antenna can allow the system present within the tyre to be suitably powered without using an independent powering unit (e.g. batteries within the tyre) .

Therefore, the apparatuses mounted on board the vehicle are provided to generate an electromagnetic field with which the antenna located in the tyre can be coupled and from which the antenna may receive the necessary energy to be transmitted to the detecting unit and sensor.

EP 1 454 771 Al shows a system in which an antenna and a radio device are connected with each other by means of a layer of electrically insulating material, into which the radio device and the antenna ends are buried; this layer is fastened to the inner surface of the tyre.

EP 1 049 196 discloses a monitoring device in which the antenna is connected to a sensor through a portion thereof disposed at right angles to the outer surface of the sensor itself. The antenna is housed in a fastening element in turn irremovably mounted on the inner surface of the tyre.

The Applicant has verified that the constraints present in' the above described systems between the ends of an antenna and a detecting unit cannot be easily and readily obtained; these constraints are also ^' of difficult elimination when the detecting unit is to be replaced, due to malfunction of the detecting unit itself for example.

The Applicant has perceived that, in order to obtain a constraint between the antenna and detecting unit, which is at the same time reliable, of quick achievement and easy elimination (when required) , use of an element of heat-shrinkable material, a sleeve for example, is advantageous, said element being applied to the outer surface of the detecting unit, at the connection with the antenna ends.

More specifically, the Applicant has found that in .the step of coupling the antenna with the detecting unit, use of a sleeve of heat-shrinkable material, fitted on the outer surface of the detecting unit-antenna . end assembly, enables the previously discussed problems to be solved. Indeed this sleeve, once fitted on the detecting unit, following a suitable heating action is able to offer a safe and reliable constraint between the detecting unit and antenna.

The thus obtained constraint in any case can be easily removed and obtained again through a different sleeve, in case of replacement of the detecting unit.

The sleeve in fact can be cut with a suitable tool and, after replacement of the detecting unit, a new sleeve of heat-shrinkable material can be easily fitted on the device, so as to obtain a new constraint between the detecting unit and the antenna ends.

Use of the sleeve of heat-shrinkable material therefore enables accomplishment of a constraint between the antenna and the detecting unit that is durable and reliable and at the same time can be easily obtained and removed.

In particular, in a first aspect the present invention relates to a ^• method of installing a detecting unit within a pneumatic tyre, said method comprising the following steps: arranging a pneumatic tyre having a radially internal surface of substantially toroidal conformation; mounting an antenna having a first and a second ends on said radially internal surface; setting a detecting unit; coupling each of said first and second ends of said antenna with said detecting unit; applying an element of heat-shrinkable material onto said detecting unit; heating said element to define a constraint between said detecting unit and the ends of said antenna, and associating said detecting unit with the radially internal surface of said tyre.

In a further aspect the present invention relates to a pneumatic tyre for vehicle wheels having a radially internal surface of a substantially toroidal conformation, comprising: an antenna mounted on said radially internal surface and having a first and a second ends; a detecting unit associated with the radially internal surface of said tyre, each of said antenna ends being electrically connected to said detecting unit; an element of heat-shrinkable material applied externally of the detecting unit to maintain a constraint between said detecting unit and the ends of said antenna.

Further features and advantages will become more apparent from the detailed description of a preferred but not exclusive embodiment of a method of installing a detecting unit within a pneumatic tyre, as well as of a pneumatic tyre for vehicle wheels in accordance with the present invention.

This description will be set out hereinafter with reference to the accompanying drawings, given by way of non-limiting example, in which:

- Fig. 1 is a partial perspective view of a pneumatic tyre in accordance with the invention;

- Fig. 2a is an exploded perspective view of a step of the method of the invention;

- Figs . 2b and 2c show diagrammatic front views of steps following the one in Fig. 2a; - Fig. 2d is a perspective view corresponding to the step in Fig. 2c;

- Fig. 3a is an exploded perspective view of a step of the method of the invention applied to an alternative embodiment of the detecting unit; - Figs. 3b and 3c show diagrammatic front views of steps following the one seen in Fig. 3a;

- Fig. 3d is a perspective view corresponding to the step in Fig. 3c;

- Fig. 4a is an exploded perspective view of a step of the method of the invention applied to another embodiment of the detecting unit;

- Fig. 4b is a diagrammatic front view of the elements shown in Fig. 4a;

- Fig. 4c is a diagrammatic front view of a step following the one shown in Fig. 4a;

- Fig. 4d is a plan view corresponding to the step seen in Fig. 4c;

- Fig. 5a shows an exploded perspective view of a step of the method of the invention applied to a further embodiment of the detecting unit;

- Fig. 5b is a diagrammatic front view of the step seen in Fig. 5a;

- Fig. 5c is a diagrammatic front view of a step following the one shown in Fig. 5b; - Fig. 5d shows a perspective view corresponding to the

step in Fig. 5c;

- Figs . 6a and 6b are diagrammatic front view of two embodiments of a detail shown in Fig. 1;

Figs. Ia-Iq diagrammatically show possible connections between the detecting unit and antenna that are present in the tyre according to the invention.

With reference to the drawings, a pneumatic tyre for vehicle wheels in accordance with the invention has been generally identified by reference numeral 1.

Tyre 1 can be mounted on any type of vehicle such as motor vehicles or motorcycles; more particularly tyre 1 is set to be used on vehicles that are provided on board with the necessary electronics for co-operating and interacting with the devices housed in the tyre itself and described in the following.

Tyre 1 has a radially internal surface 20 of substantially toroidal conformation; this internal surface 20 can be defined by a layer of elastomeric material that is substantially airtight and is usually referred to as "liner".

Mounted on the radially internal surface 20 is a detecting unit 10 set to detect operating parameters relating to tyre 1 and the operating -conditions of the tyre itself.

The detecting unit 10 may comprise one or more sensors to detect said operating parameters which for example, can be the tyre temperature, inner pressure and/or distance covered, possibly calculated in co-operation with the devices located on board. .

The detecting unit 10 can be associated with a microprocessor connected to said sensors to manage operation thereof, and with a storage unit to contain the data detected by the sensors.

Preferably stored in the storage unit are tyre identification data, to be able to unequivocally identify the tyre during processing and evaluation of the operating parameters mentioned above.

Preferably, the microprocessor is arranged to talk to an electronic device positioned on board the vehicle. To enable communication between the detecting unit 10 and electronic device on board, an antenna 4 is provided to be operatively associated with the detecting unit 10. The antenna 4 is preferably mounted on the radially internal surface 20 of tyre 1.

In addition to the above, the antenna 4 can be also utilised to power the detecting unit 10 and the devices associated therewith, so as to avoid use of independent powering units within the tyre 1.

To this aim, the antenna 4 has a coil-shaped conformation (or more exactly it is of the "closed" type as defined in the following) , so as to be coupled with an electromagnetic field generated by ^' the device present on board the vehicle and to absorb the energy necessary to feed the detecting unit 10.

Data exchange between the detecting unit ^' 10 and said electronic device takes place through transmission and reception of radio-frequency signals (RF signals) the frequency of which can. be included between about 100 kHz and about 50 MHz, and preferably can correspond to

about 125 kHz. In particular, this frequency range can be used if feeding of the detecting unit 10 is wished to take place through the antenna 4 itself that in this case would have a configuration of the "closed" type. If on the contrary the antenna is preferably wished to be used for data transmission/reception, also frequencies included between about 300 MHz and about 2.5 GHz can be employed, in which case antennas of a configuration of the "open" type are utilised.

In the present context and in the following claims, an antenna with a configuration of the "open" type means an antenna the configuration of which defines an electrically open circuit. For instance, the antenna body can have one or more ends electrically connected to the detecting unit and one or more "free" ends.

By the expression an antenna with a configuration of the "closed" type it is intended an antenna the conformation of which defines an electrically closed circuit, in which case the antenna body has two ends that are both electrically connected to said detecting unit. Co-operation between the on board devices, antenna 4 and detecting unit 10 therefore constitutes a detecting system enabling the detecting unit 10 to also operate without the presence of batteries or similar powering units mounted within the tyre 1.

For installation of the detecting unit 10 within tyre 1, a first and a second ends 2, 3 of the antenna 4 are coupled with the detecting unit 10 itself.

Preferably, an electrically conductive termination 2a,

3a of each of these ends 2, 3 is put in a condition of mutual contact with a respective electric-contact

region 11, 12 present in the detecting unit 10.

In more detail, each electrically conductive termination 2a, 3a is inserted into a .respective housing seat lla, 12a the shape of which matches that of the corresponding electrically conductive termination 2a, 3a.

Practically, in order to enable the detecting unit 10 to be connected to antenna 4, said detecting unit has at least two electric-contact regions 11, 12 each of which defines a housing seat lla, 12a of a respective termination 2a, 3a of the antenna 4.

The terminations 2a, 3a of the antenna 4 can for example have an L-shaped conformation (as shown in Figs. 2a and 3a) or, more generally, have a protrusion adapted to be mechanically engaged with the respective housing seat lla, 12a of the detecting unit 10 (Figs. 4d and 5a) .

As shown in Fig. 4a, the detecting unit 10 can also be provided with side grooves 18 for better association with the end portions of the antenna 4.

In the embodiment shown in Figs. 5a-5d, the detecting unit 10 comprises a first and a second portions 10a, 10b that can be coupled by precise fitting; the ends 2, 3 of the antenna 4 in this case are interposed between the first and second portions 10a, 10b of the detecting unit 10 to create a constraint with the latter.

In more detail, the conductive terminations 2a, 3a of antenna 4 are caused to bear on the second portion 10b; fastening pins 10c provided with wings and integral

with the second portion 10b are then fitted into corresponding through holes 1Od present in the first portion 10a, so as to obtain an irreversible mechanical constraint between the two. portions 10a, 10b. The lower surface of the first portion 10a has the electric- contact regions 11, 12 that, due to mutual engagement between the first and second portions 10a, 10b, are in contact with the conductive terminations 2, 3a of the antenna 4.

To keep the antenna ends 2, 3 in contact with the detecting unit 10, an auxiliary insert 5 can be used which is disposed externally of the detecting unit 10 after the housing seats 11a, 12a of the latter have been brought into contact with the respective electrically conductive terminations 2a, 3a.

The auxiliary insert 5 is preferably made of thermoplastic or thermosetting materials such as styrene resins (acrylonitryle/butadiene/styrene - ABS terpolymers for example) , polyethylene, high-density polyethylene - HDPE, for example) , polyamides (nylon, for example) , copolymers of an ethylene and an ester containing an ethylene unsaturation (ethylene- vinylacetate copolymer - EVA, for example) , polypropylene. These materials can contain' additives known in the art, such as reinforcing fillers, plasticizers, antiagers, stabilisers and the like.

Thickness of the auxiliary insert 5 can be included between about ^" 0.5 mm and about 3 mm, preferably being of 1 mm.

It is further provided that, in order to make the constraint between the antenna 4 and detecting unit

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10 more reliable, an element made of a heat-shrinkable material should be used.

This element is applied onto the detecting unit 10 and is subsequently heated to define a constraint between the detecting unit 10 and the ends 2, 3 of antenna 4.

In the present context and in the following claims, by "heat-shrinkable" material it is intended a material that, within a given temperature range, reduces its sizes, at least in a predetermined direction, in an irreversible manner.

Preferably, the element of heat-shrinkable material is in the form of a sleeve 6 having a substantially tubular conformation, a predetermined longitudinal length and a right section, a circular one for example, of a given diameter. Alternatively, said element can have a polygonal right section, in which case the maximum transverse size of said right section will be intended as the diameter.

Sleeve 6 initially has such sizes that an easy and immediate insertion of the detecting unit 10 into the tubular extension of the sleeve itself is allowed.

Following a heating action carried out on the heat- shrinkable element, said element shrinks on the detecting unit 10 and the ends 2, 3 of the antenna 4, thus binding the electrical terminations 2a, 2a to the housing seats 11a, 12a in a reliable manner.

It is to be noted that sleeve 6 is such made that, when submitted to a heating action, it at least reduces its inner diameter, so as to obtain the above described

constraint .

If also said auxiliary insert 5 is used, sleeve 6 is set externally thereof after the detecting unit 10 and the ends 2, 3 of antenna 4 have been fitted in said auxiliary insert 5.

Vice versa, should not the auxiliary insert 5 be used, sleeve 6 can be directly arranged on the detecting unit 10. Preferably, one of the ends 2, 3 of antenna 4 is inserted into the sleeve 6 before both of said ends are brought into contact with the detecting unit 10; subsequently the conductive terminations 2a, 3a are coupled with the respective housing seats 11a, 12a. Then, sleeve 6 is axially positioned close to the detecting unit 10 and is suitably heated.

In case of use of the auxiliary insert 5, the latter is preferably fitted around the detecting unit 10 before sleeve 6 is brought to an axially correct position and heated for creation of the constraint.

It is also to be pointed out that the antenna end that is not initially inserted in the sleeve 6 can be indifferently brought into contact with the detecting unit 10 either before or after the other end is introduced into the sleeve 6.

Preferably, following said heating step, the element of heat-shrinkable material reduces at least one dimension thereof by a. factor included between about 2 and about 4, and in particular equal to about 3.

Preferably, as above mentioned, the ratio between the inner diameter of the sleeve 6 before and after the

heating step is included between about 2:1 and about 4:1, and in particular it can be of about 3:1.

It is to be noted that the heat-shrinkable material can have shrinkage features that are substantially identical in all directions or different from each other in each direction. For example, in a preferential embodiment, the material can have such features that the ratio between the diameter of sleeve 6 before and after the heating step keeps within the above stated ranges, while the ratio between the maximum longitudinal dimension (i.e. the sleeve length) before and after the heating step is included between about 1.1:1 and 3:1, preferably being equal to about 2:1.

Heating is currently carried out through a hot air flow on the sleeve.

The heat-shrinkable material can be a material based on polyamides (6.6-Nylon, for example), polyolefins

(polyethylene, polypropylene, for example) , polyvinylchloride (PVC) , polysthyrene (PS) , polyesters

(polyethylene terephthalate (PET) , for example) .

The electric-contact regions 11, 12 and related housing seats 11a, 12a have such positions that the deformations to which the antenna 4 is submitted at the connection with the detecting unit 10 are minimised.

In fact, the antenna 4 is bound to the radially internal surface 20 of tyre 1 according to a predetermined longitudinal extension, such as a substantially sinusoidal profile.

In any .case, the presence of the detecting unit 10

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along said extension constitutes an break of said extension and must therefore be connected in such a manner as to minimise generation of asymmetries and lack of homogeneity along the antenna 4 profile.

Therefore the detecting unit 10 is preferably positioned on the radially internal surface 20 of tyre 1 at an equatorial plane E of the latter.

In more detail, the electric-contact regions 11, 12 can be positioned on opposite sides relative to this equatorial plane E. In addition or as an alternative to the above, the electric-contact regions 11, 12 can be positioned on opposite sides relative to a median axis M of the detecting unit 10; the median axis M identifies a major extension direction D of the detecting unit 10. In addition, the detecting unit 10 can be such disposed that the major extension direction D is transverse, and preferably perpendicular to the above mentioned equatorial plane E of tyre 1.

By way of example, the detecting unit 10 can have a parallelepiped conformation; the electric-contact regions 11, 12 can be located on opposite side faces, at the opposite axial ends of the parallelepiped (Fig. 2a) .

Alternatively, the electric-contact regions 11, 12 can be located on the same side face, .at axially opposite and preferably substantially symmetric positions (Fig. 3a) .

A further possibility is shown in Fig. 7a, in which the electric-contact regions 11, 12 are on opposite side faces and at substantially central positions of the

detecting unit 10.

Figs. Ib-Ie and 7g on the contrary show embodiments in which the electric-contact regions 11, 12 are on ^• opposite bases of the parallelepiped defining the detecting unit 10, at substantially central positions, or at axially symmetric positions.

The antenna 4 preferably has a thread-like conformation and in particular, with the detecting unit 10 it can form a closed-loop.

The antenna 4 can be mounted on the radially internal surface 20 of tyre 1 by means of a plurality of discrete engagement elements 21.

Should the antenna 4 have a sinusoidal extension along the radially internal surface 20 of tyre 1, the engagement elements 21 will preferably be at the inflexion points of this sinusoidal extension.

After binding of the detecting unit 10 to the ends 2, 3 of antenna 4, the detecting unit 10 itself is associated with the radially internal surface 20 of tyre 1. Preferably this associating step is performed by fitting at least the detecting unit 10 into a housing element 7, through which the constraint with the radially internal surface 20 of tyre 1 is obtained.

It is to be pointed out that, should the above mentioned auxiliary insert 5 be used, the latter will be inserted into the housing element 7 as well; in fact, during this process step, the detecting unit 10, the possible auxiliary, insert 5 and sleeve 6 are already mutually in engagement and ready for mounting on liner 20. ^'

The housing element 7 can be integrally made with the radially internal surface 20 of tyre 1, during the manufacturing process of the tyre itself.

Alternatively, the housing element 7 can be made separately from tyre 1 and is then fastened to the inner surface 20 at a subsequent moment. The housing element 7 is preferably made of elastomeric material.

Shown in Fig. 6a is a first embodiment of the housing element 7; axially inserted into a fitting portion 7a is the detecting unit 10 together with sleeve 6 and possibly the auxiliary insert 5, while a base 7b allows fastening to the radially internal surface 20 of tyre 1.

Shown in Fig. 6b is a second embodiment of the housing element 7; in addition to a fitting portion 7a and a base 7b, the housing element 7 also has an opening 7c for forced fitting of the detecting unit 10 in a radial direction.

It is finally to be pointed out that in a preferred embodiment the antenna 4 end can be integrated into the detecting unit 10. More specifically an end of the antenna 4 can be fastened to the detected unit through welding or other equivalent constraint, so that the sleeve 6 - and possibly the auxiliary insert 7 - substantially have the only task of ensuring mutual engagement between the detecting unit 10 and the other end of the antenna 4.