PIASENZOTTO, Marco (Via Pirona 27, Udine, I-33100, IT)
RAGONESE, Maurizio (Via Verdi 19, Tarvisio, I-33018, IT)
PIASENZOTTO, Marco (Via Pirona 27, Udine, I-33100, IT)
| Claims. 1). An anti-skid chain for wheels, comprising a special chain configuration (2), predisposed to be positioned contactingly against a tread of a tyre, and means for fastening (3a, 3b), predisposed to enable fastening the chain configuration (2) on the tyre tread, characterised in that the chain configuration (2) comprises a plurality of closed geometrical figures (4, 5) arranged in succession, defined by main tracts of chain (4a, 4b, 4c, 5a, 5b, 5c, 5d), which are connected to the means for fastening by connecting tracts (6a, 6b, 6c, 6d), the closed geometrical figures (4, 5) being formed by at least three sides, each of which sides is inclined with respect to a mean circumference (2M) of the chain configuration (2). 2). The anti-skid chain of claim 1 , wherein the closed geometrical figures are triangles (4). 3). The anti-skid chain of claim 2, wherein the triangles (4) exhibit vertices (4V) facing in a same direction. 4). The anti-skid chain of claim 2, wherein the triangles (4) consecutively exhibit vertices (4V) facing in opposite directions. 5). The anti-skid chain of claim 3 or 4, wherein the triangles (4) are symmetrical with respect to the mean circumference (2M) of the chain configuration (2). 6). The anti-skid chain of claim 3 or 5, wherein the triangles (4) are connected to the means for fastening (3a, 3b) via a first connecting tract (6a), connected to a base vertex (41), a second connecting tract (6b), connected to a second base vertex (42), a third and a fourth connecting tract (6c, 6d) connected to the vertex (4V). 7). The anti-skid chain of claim 1 , wherein the closed geometrical figures are quadrangular figures (5). 8). The anti-skid chain of claim 7, wherein the quadrangular figures (5) are rectangles. 9). The chain of claim 8, wherein the rectangles (5) exhibit a mean longitudinal axis (5M) and are arranged such that the mean longitudinal axis (5M) is inclined with respect to the mean circumference (2M) of the chain configuration (2). 10). The anti-skid chain of claim 9, wherein the inclination of the mean longitudinal axis (5M) is the same for all the rectangles (5). 1 1 ). The anti-skid chain of claim 9, wherein the inclination of the mean longitudinal axis (5M) is symmetrical for two consecutive rectangles (5). 12). The anti-skid chain of claims from 7 to 1 1 , wherein the quadrangular figures (5) exhibit four corners, each of which is connected to the means for fastening (3a, 3b) by means of a connecting tract (6a, 6b, 6c, 6d). 13). The anti-skid chain of the preceding claims, wherein the elongate element (3a) destined to be positioned on an external side of the wheel is sub-divided into two portions which, for mounting the chain on a wheel, are connectable to one another by means of two automatic tensioning devices. |
Technical Field
The invention relates to an anti-skid chain for wheels. Background Art
The present tendency of motor vehicle constructors is to use tyres in which the breadth of the tread is decidedly greater than that of tyres used up to some time ago, and to arrange on the tread one or more continuous circumferential grooves. The increase in breadth of the tread and the number of circumferential channels is very accentuated in higher-power vehicles with greater cubic capacity. Obviously, anti-skid chains for wheels must be adapted to the present tendency of increasing the width of the tyre treads.
Traditional anti-skid chains comprise a road contact configuration formed by tracts of chain, which is predisposed to be positioned in contact with the tread of a wheel. Fastening means 3a, 3b are predisposed to enable fastening the chain road contact surface onto the tyre tread. In traditional chains, the fastening means comprise at least two elongate elements, typically in the form of a steel cable or chain, which are predisposed to ring-close in contact with a flank of the wheel. The chain road contact surface is constrained, directly or by means of tracts of connecting chain, to the two elongate elements. The tread of traditional chains is substantially formed by portions of the connecting tracts, which are transversally arranged in oblique directions on the wheel tread, and by tracts of longitudinal chains which connect the connecting tracts in pairs. The number of chain tracts making up the road contact surface is thus relatively small, such as to guarantee the wheel neither an acceptable traction in acceleration and in braking nor a sufficient lateral hold, especially if the wheel tread exhibits considerable width such as in the case of modern high-powered vehicles.
The aim of the present invention is thus to provide an anti-skid chain which increase coverage of the tyre tread by increasing the number of tracts of chain that make up the chain road contact surface, such as to increase the traction capacity of the anti-skid chain. Disclosure of Invention
Characteristics and advantages of the invention will better emerge from the detailed description that follows, made with reference to the accompanying figures of the drawings, given by way of non-limiting example, in which: figure 1 is a plan view of a tract of the chain of the present invention in a first embodiment thereof; figure 2 is a plan view of a tract of the chain according to the present invention in a second embodiment thereof; figure 3 is a plan view of a tract of the chain of the present invention in a third embodiment thereof; figure 4 is a plan view of a tract of the chain of the present invention in a fourth embodiment thereof.
The anti-skid chain 1 for wheels of the present invention comprises a road contact configuration 2, provided with a mean circumference 2M and predisposed to be positioned in contact with the tread of a wheel with the mean circumference 2M substantially parallel to the mean circumference CM of the tyre tread, and fastening means 3a, 3b predisposed to enable blocking of the chain contact configuration 2 on the tyre tread. In traditional chains, the fastening means comprise at least two elongate elements 3a, 3b (schematically represented with a dot-and-dash line), typically in the form of a steel cable or a chain, which are predisposed to ring-close and be each arranged in contact with a flank of the wheel. One of the two elongate elements, the one which is positioned on the internal side of the wheel, has a substantially fixed length. The road contact configuration 2 of the chain is constrained to the two elongate elements 3a, 3b. The figures further illustrate, in a schematic flat development, two continuous circumferential grooves A, B of the tyre tread which are typical of tyres of modern manufacture. The tyre tread 2 comprises a plurality of closed geometric figures 4, 5 arranged in succession. These closed geometric figures 4, 5 are defined by main tracts of chain 4a, 4b, 4c, 5a, 5b, 5c, 5d which are connected to fastening means by connecting tracts 6a, 6b, 6c, 6d. The closed geometric figures 4, 5 are formed by at least three sides, each of which is inclined with respect to a mean circumference 2M of the tread 2. The presence of closed geometric figures on the road contact configuration of the chain considerably increases the traction capacity of the chain. The inclination of the sides of the geometric figures 4, 5 excludes the possibility that one or more tracts of chain can engage, incorrectly, in the continuous circumferential grooves of the wheel tread.
In a first embodiment of the chain, the closed geometric figures are triangles 4. Each triangle 4 exhibits a vertex 40 and two base corners 41, 42. The triangles 4 can be arranged with the vertices 40 facing in the same direction (figure 1), or the consecutive triangles can be arranged with the vertices 40 facing in opposite directions (figure T). In the first case the chain exhibits different traction characteristics according to the rolling direction of the wheel, in particular the characteristics are greater in one direction than in another. In the second case the traction characteristics are the same in both wheel-rolling directions. Preferably the triangles 4 are symmetrical with respect to a mean circumference 2M of the tread 2. As can be seen in figures 1 and 2, the triangles 4 are connected to blocking means by a first connecting tract 6a which connects a base vertex 41 to a first elongate element 3a, a second connecting tract 6b, which connects a second base vertex 42 to the second elongate element 3b, a third and a fourth connecting tract 6c, 6d which connect the vertex 40 with both the elongate elements 3a, 3b. The connecting tracts also obviously contribute to the traction which can be exerted by the chain. In a second embodiment of the chain, the closed geometric figures are quadrangular 5, preferably rectangles. The rectangles 5 exhibit four corners 50, 51 , 52, 53 and a mean longitudinal axis 5M. As can be seen in figures 3 and 4, the rectangles 5 are arranged such that the mean longitudinal axis 5M is inclined with respect to the mean circumference 2M of the tread 2. In this way none of the sides of the rectangles 5 can engage anomalously in the continuous circumferential grooves present on the tread of the tyre. The inclination of the longitudinal axis 5M can be the same for all the rectangles 5, as illustrated in figure 3, or can be symmetrical in two consecutive rectangles 5, as illustrated in figure 4. In the second case the rectangles 5 are positioned substantially in a zig-zag fashion with respect to the mean circumference of the tread 2.
The quadrangular geometrical figures 5 exhibit four corners 51 , 52, 53, 54, each of which is connected to blocking means 3a, 3b by means of a connecting tract 6a, 6b, 6c, 6d. In particular two corners 51 , 54 are connected to a first elongate element 3a, while the other two corners are connected to the other elongate element 3b.
As already mentioned, the elongate element 3a which is positioned on the external side of the wheel has a variable length in order to enable, after mounting, a correct tensioning of the chain on the wheel. With this aim in mind the applicant has developed an automatic tensioning device, described in European Patent no. 896557 (in particular from page 17 to page 34 of the filed Italian translation), which enables the chain to be stretched on the tyre during the rotation of the wheel. The chains which use this type of device, as can be seen in figure 6 of the above-mentioned patent, exhibit the elongate external element 3a subdivided into two portions which are connectable to one another by means of two automatic tensioning devices. The devices are constrained at an end of one of the portions of the elongate element 3a and comprise a hooking cable predisposed to hook up to the end of the other portion of the elongate element. The hooking cable is wound on a drum provided with elastic rotating means which rotate the drum in the direction of winding the cable. A retaining mechanism is activatable by the user between a first configuration, in which the drum can rotate in both directions, a second configuration, in which the drum can rotate in the direction of winding the cable and not in the opposite direction, and a third configuration, in which the drum cannot rotate. In order to mount the chain, the user activates the retaining mechanism of the two tensioning devices in the first configuration and extracts the cable to the maximum possible length thereof. Then each cable is blocked by activating the retaining mechanism of the third configuration and the cable is hooked to the portion of elongate element 3a. At this point each retaining mechanism is activated in the second configuration. The action of the elastic rotation means is such that the cable is constantly pulled in the winding direction onto the drum, such as to transmit a constant traction to the portion of elongate element 3a to which it is hooked. This means that the anti-skid chain is well-tensioned on the wheel. The anti-skid chain of the present invention functions extremely effectively in combination with two automatic tensioning devices of the type described in European Patent no. 896557. The anti-skid chain of the present invention offers important advantages. The presence of closed geometrical figures on the road contact configuration of the chain considerably increases the chain traction capacity. Further, the fact that the sides of the geometrical figures are inclined with respect to the mean circumference of the tyre tread means that one or more tracts of chain can engage internally of the continuous circumferential grooves of the tyre tread, such that the traction conditions are always optimal. This further means that there are no tracts of chain which project differently with respect to the tyre tread, such that the risks that the chain can wear non-uniformly are limited.