Field of application of the invention

The invention regards the road haulage field, and in particular it refers to a particular anti-slip device for the wheels of vehicles for transporting people and goods. More specifically, the invention regards an anti-slip device for tires, adapted for every tire size, independent of the size thereof, and provided with a coupling and adjustment device for the length thereof.

State of the art and related drawbacks

When one speaks of an anti-slip device for tires, one refers to a safety device to be applied on the tread of the tire in order to allow the traction on roads covered with snow and/or ice, so as to allow the driver to drive the vehicle in question without slipping or skidding on the road surface, with ensuing dangerous loss of control of the vehicle.

In this field, there are essentially two types of snow chains: a first type which consists of a series of metal links connected together in longitudinal direction, which is circumferentially wound around the tired wheel, and a second type which consists of a plurality of separate traction elements, generally metallic chain segments, which are arranged in transverse direction on the tire and locked in this position by a tensioning element. Such tensioning element is gen- erally a fabric belt which connects the opposite ends of said traction elements crossing through the diameter plane of the wheel at the rim lightening windows, provided for the ventilation and cooling of the wheel brake devices. The present invention specifically regards said second type of anti-slip device.

Many models of this device are present on the market, made of different materials and types but above all of different size, given that each model must be adapted to a particular tire and wheel size and therefore to a particular vehicle type. In this manner, any one tire change with a different size model, or the substitution of the vehicle, requires the acquisition of a new device model explicitly designed for the specific tire/vehicle type.

In addition, this device type is negatively affected by a further drawback. Indeed, the vehicle does not always begin travel with the device already mounted on the wheels; often, during the trip there arises the need to mount the device, and when this occurs the driver might not be able to mount the device in a correct manner, for example due to the fact that the tire is deflated, though slightly but enough for its transverse dimension to be changed with respect to the nominal value as a function of which the device model has been selected. Or, the driver might not be able to correctly mount the device due to the fact that, with use, the traction belt is worn in the zone where the clasp must lock it, making the right traction of the device on the tire difficult if not impossible.

Object of the invention

Object of the present invention is therefore a particular model of anti-slip device, whose longitudinal dimension is adjustable with respect to its maximum extension such that it can be adapted to the size of a plurality of vehicle tires and wheels; simultaneously, it can also recover the small variations of longitudinal extension following the above-mentioned drawbacks.

Summary of the invention

Object of the present invention is therefore an anti-slip device for wheels of vehicles comprising a traction element provided with at least one metallic chain segment, with a pair of metal brackets of which the first bracket comprises one end provided with a first device for permanent coupling with one end of said traction element and the opposite end provided with a second device for per- manent coupling to a tensioning element for said metallic chain segment, the second bracket comprises one end provided with a coupling device for the other end of said traction element and it is provided with a seal element for locking and unlocking said tensioning element for said anti-slip device. According to the invention, said coupling device provided on said second bracket for said traction element is a coupling and release device for said opposite end of said metallic chain segment. Preferably, said coupling and release device comprises a slot whose dimensions prevent the exit of the chain ring inserted in said slot.

Description of the figures

In any case, the present invention will be better understood on the basis of the following description and with reference to the enclosed figures, provided only for exemplifying and non-limiting purposes, given that other embodiments are still possible, of which:

figure 1 illustrates the invention device, in a preferred embodiment, in its constituent elements,

figure 2 illustrates the clasp for the locking of the tensioning element of the invention device of figure 1 , in its constituent elements,

figure 3 illustrates the invention device of figure 1 , in use conformation, even if not mounted on the wheel of the vehicle,

figure 4 illustrates a plurality of devices according to the invention, mounted on the wheel of a vehicle and connected to each other by a common tensioning element.

Description of the invention

With reference to figure 1 , the anti-slip device for vehicle wheels according to the invention comprises a traction element on snowy or icy ground, e.g. comprising at least one metallic chain segment 1 , preferably a pair of segments 1 and 2. Naturally, in particular cases or for tires of considerable size, there can be more than two segments although, preferably, there will never be more than four segments.

The aforesaid device further comprises a first bracket 3, preferably with trapezoidal shape. One end of said bracket is provided with a first device 31 for permanent coupling with one end of said traction element. The opposite end is pro- vided with a second device 32 for permanent coupling to a tensioning element 4 for said traction element. In a convenient embodiment, said first bracket 3 is made with a metallic round bar, for the purpose of lightening the weight of the bracket with respect to an analogous plate-shaped bracket. The opposite ends of the aforesaid trapezium both have a closed ring 31 within which one end of said traction element is housed, e.g. the terminal ring of one of said chain segments. One end of said tensioning element preferably comprises a strip or band 4 made of fabric of suitable natural or synthetic textile material, e.g. nylon is wound around the smaller base 32 of the trapezium. The end of said band folded on itself around the smaller base 32 of the trapezium is preferably locked by at least one metallic boss 41 or by any other equivalent means. Preferably, there will be at least two or three of such bosses. On the opposite end of said belt, a second bracket 5 is fit, axially slidable along the band. Said bracket comprises a coupling device 51 for the other terminal of said traction element and a seal element, i.e. a clasp for locking and unlocking said tensioning element for said anti-slip device. In a convenient embodiment, said second bracket is obtained with a metallic plate 5, it too being trapezoid-shaped. At the ends of the greater base of said trapezium (figure 2), the plate is provided with a pair of axial extensions 51 , radially folded on themselves. Each of such extensions delimit a substantially semicircular seat, i.e. a slot, externally open, with the concavity turned towards the smaller base of the trapezium. According to the invention, the depth "h" of such slot is comprised between two and three times the size of the diameter "d" of the metallic wire with which the rings are produced, or at least the terminal ring of the chain segment that will be inserted in said slot. Preferably, "h" will be equal to 2.5"d". Still more preferably, the side of the trapezium that connects the slot with the smaller base of the trapezium will be tilted by an angle "w" comprised between 10° and 20° with respect to the longitu- dinal axis of the plate. The slots presently described constitute a coupling and release device for the opposite end of said traction element, provided on said second bracket.

At the smaller base of the trapezium, the plate 5 has a slit 52, preferably with rectangular shape, with width Ί" at least equal to but preferably greater than the width of the band 4. Between the slit 52 and the greater base of the trapezoid, through holes 53 are obtained, aligned in longitudinal direction on two separate rows, separated from each other by a distance "b" preferably not less than the width "I" of the slit. Preferably, there are at least four of such holes, which are rectangular-shaped.

The aforesaid holes serve to fix on the plate, in an integral manner, a pair of small plates 54 arranged (figure 3) orthogonally with respect to the plate pro- vided with teeth on one side - equivalent in number and shape - with respect to the holes 53 for the fit-coupling in said holes and - on the opposite side - with a through hole 58 and a protuberance 59 extended in a direction parallel to the plate 5, towards the facing small plate. The locking clasp of the tensioning belt is completed by an L-shaped lamina 55 with the greater length portion (tab of the clasp) arranged parallel to the surface of the plate 5, that of smaller length (blade of the clasp 55') perpendicular to the aforesaid plate and turned towards the same.

The border of said lamina is laterally provided with two pins 56, placed in proximity to the angular bend of the L, which are housed in the holes 58 of the two small plates 54, and with two recesses 59' at the two protuberances 59. In such a manner, the lamina can rotate with respect to the plate 5 around the rotation axis passing through the holes 58, in a manner so as to press (as will be described below) the tensioning band between the blade of the clasp and the surface of the plate 5. Preferably, the tab of the clasp is provided with a through hole 57 on the end opposite the pins 56.

Now that the structure of the anti-slip device of the invention is known, it will be easy to understand the functioning thereof, also with particular reference to figures 3 and 4.

If required, a certain number of anti-slip devices will have to be mounted on the wheel of the vehicle, ranging from three to eight and preferably four. Each device will be mounted by arranging the traction elements transversely on the tread of the tire, leaving the free terminals hanging on the external side of the wheel. One now grasps the free end of the tensioning band and brings it outside the wheel by making it pass through the windows present on the disc of the rim on which the tire is mounted. This end of the band bears the bracket provided with the coupling and release device, such that it is easy to fit the end of the traction element in the corresponding slots of the device. Traction is now exerted on the free end of the band, which is made to pass into the slit 52, being brought from the external surface (with respect to the wheel) of the plate 5 onto the internal surface of said plate; the free end runs along said surface in order to be bent around the greater base of the trapezium and con- tinues along the external surface of the plate by passing between the surface of the plate and the blade of the clasp. During this movement, the band 4 moves the blade 55' according to the direction of the movement by making the tab 55 rotate around the pins 58, with consequent movement of the tab 55 towards the outside. Once the maximum possible traction is obtained on the band, the tab 55 is pressed against the plate 5 in a manner such that the blade 55' interferes with the surface of the band, exerting on the same a pressure capable of locking it in the attained position. The anti-slip device is thus locked on the wheel, with the traction element on the tread of the tire, equipping the latter with an optimal traction and seal capacity on snowy and/or icy ground. During the move- ment of the wheel on the road, in particular as a consequence of the deflection of the tread on the track area, the tension force of the traction element can vary in intensity; nevertheless, it has decreasing value due to the depth "h" of the slot for containing the end of the traction element, also facilitated by the specific tilt angle of the side of the slot turned towards the smaller base of the trapezium, such end prevented from exiting from the aforesaid slot and thus maintaining the anti-slip device firmly anchored on the wheel of the vehicle. Preferably, in order to prevent the anti-slip device from rotating around the straight section of the tire due to these cyclic variations of tension on the traction element, by moving said element with respect to the tread all the devices mounted on the same wheel of the vehicle (figure 4) are connected to each other by an elastic means, e.g. an elastic ring 6 coupled to the tabs 55, by means of the hole 57 present on each lamina.

Advantages of the invention

The present invention provides important advantages from an economical as well as qualitative standpoint. From the economical standpoint, the driver is no longer required to purchase new snow chains each time the size of the tires installed on his car change, or even each time he changes vehicle; should a user have two or more vehicles, he will be able to use the same anti-slip device on any of one of said vehicles. Indeed, the device of the invention can be sold with traction elements adapted for the maximum size of tires available in the market; if a device with smaller length of the traction element is required, it will suffice to couple the plate 5 to an intermediate point between the two ends of the traction element, in such a manner reducing the element to the desired length. The free portion of the traction element will be conveniently fixed to the tensioning band or directly to the rim in any convenient manner that prevents the free oscillation thereof with respect to the device.

With respect to the qualitative aspect, it is clear that the device of the invention allows easily resolving the drawbacks mentioned at the beginning of the present description. Indeed, it is assumed that the user, at the time the device is mounted on the wheel of the vehicle, perceives that due to a slight deflation of the tire (that cannot be eliminated on site) the length of the traction element is greater than that necessary for a correct tensioning of the device. The problem will be easily resolved by coupling the traction element to a point immediately preceding the terminal point, in such a manner recovering the slight decrease of length following the aforesaid deflating.

Analogously, it is assumed that, due to an extended use of the device, the por- tion of the tensioning band on which the blade of the clamping hook acts is ruined, e.g. overly crushed so that it is no longer able to ensure the correct tensioning of the traction element over time during use. Once again, by selecting a different point for coupling the segment to the plate 5, it will be possible to move the zone of the band on which the blade of the hook acts into a different, new position, thus restoring the correct functioning of the anti-slip device of the invention. Finally, from the above-provided descriptions, it will be understood just how easy and rapid the assembly and adaptation of the snow chains according to the invention are on the vehicle wheels, even by non-expert people.

In the present description, not all of the possible structural and size alternatives to the specifically-described embodiments of the invention were illustrated: indeed, it did not seem necessary to go into further detail on the structural details of the system of the invention, since the man skilled in the art, after the instruc- tions given herein, will have no difficulty to design the most advantageous solution, suitably selecting materials and dimensions. Nevertheless, these variations are also included in the protective scope of the present patent, such alternative embodiments being per se easily derivable from the description made herein of the relationship that links each embodiment with the intended outcome of the invention.