Connecting hook for joining elements of snow chains

Abstract: A connecting hook (10) for joining elements of snow chains, comprising a first end part (11) destined to engage in at least one link (15) of a chain portion (5) creating the friction on the tread and a second end part (13) destined to engage in a part of a ring element (3, 4) which is disposed on an outer or inner side of a tyre (2), the second end part (13) of the hook (10) having a lesser thickness than that of the first end part (11).

Description: The present invention refers to a connecting hook for joining elements of snow chains. When a vehicle is on a road surface covered with snow, sleet or ice, its tyres do not have a good grip and dangerous swerving or skidding of the vehicle can occur. To avoid these problems it is customary to use anti-skid devices, commonly called snow chains. Snow chains, normally mounted on the driving wheels of the vehicle, bite into the snow and/or ice deposited on the road surface, increasing the friction on the tread and allowing the vehicle tyres to achieve a good grip. As it is known, a snow chain generally consists of two side elements (chains, flexible cables, steel wires, ropes or the like), which during use are closed in a ring on the inner side and the outer side of the wheel, respectively. These side elements, henceforth called inner ring and outer ring according to their position on the wheel, are connected by a series of chain portions variously disposed to achieve the friction on the tread, the whole completed by a device for tensioning said elements, known as a tensioner. The chain portions that generate the friction on the tread are joined to the inner ring and to the outer ring by means of connecting hooks. Said hooks are obtained from a metal bar having a circular cross section. Said bar is bent in a U-shape in the central area to form a first loop and then it is bent in a U-shape at the two ends to form two second loops. In this manner the first loop of the hook can engage in a link of the chain portion that generates the friction on the tread and the two second loops can engage in the inner ring or in the outer ring. The hooks according to the prior art have the drawback of being excessively bulky. Said hooks, in fact, having a circular cross section, have an excessive thickness, thus they protrude excessively from the wheel with the risk of interfering with the mechanical members of the vehicle. This problem is all the more acute for hooks destined to be applied to the inner ring. In fact said hooks can interfere with the shock absorbers or the suspensions of the vehicle or parts of the body. In order to partially solve this problem due to the excessive bulk of the connecting hooks, connecting hooks with a reduced thickness have been made from a bar having a substantially flattened rectangular section. This type of hook is disclosed, for example, by document DE-A-19823075 which refers to a connecting hook, made of a wire having a flattened oval cross section. This type of hook has solved the problem of the bulk, but presents problems of structural yielding and rapid wear. In fact the first loop of the hook is in close contact with a link of the portion of chain that creates the friction on the tread. Since the hook is flattened a high friction is generated between the first loop and the link of the chain portion. Consequently said contact part is subject to rubbing friction and mechanical stress which lead to rapid wear and consequent structural yielding of the hook. Apart from this, the entire structure of the hook is weakened because of the total flattening thereof. The object of the present invention is to eliminate said drawbacks by providing a connecting hook for joining the elements of snow chains that is not bulky and at the same time is reliable, safe and has a good resistance to stress and wear. Another object of the present invention is to provide such a hook that is practical, economical and simple to make. These objects are achieved according to the invention with the characteristics listed in appended independent claim 1. Advantageous embodiments of the invention are apparent from the dependent claims. The connecting hook for joining the elements of snow chains according to the invention has a reduced thickness in the area of contact with the inner ring or the outer ring of the snow chains. In the part in contact with the link of the chain portion that creates the friction on the tread, the hook according to the invention has a round section to increase its structural strength and minimise rubbing friction. The decrease in thickness in the areas destined to come into contact with the inner or outer ring is obtained by flattening of the end parts of the bar destined to form the hook according to the invention. In this manner the thickness of the protruding part of the hook which is in contact with the inner or outer ring is considerably reduced. Thus the hook according to the invention has a limited bulk and consequently, by using said hook, the risk that it might knock against mechanical members of the vehicle is avoided. Furthermore, the part with a round cross section and a greater thickness gives the hook a greater resistance to stress and less rubbing friction with the link of chain with which it is in contact. Consequently in this point of contact there are fewer problems of wear and breaking of the hook. Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplary and therefore non-limiting embodiment thereof, illustrated in the appended drawings, in which: Figure 1 is a front view of a self-tensioning device, taken from the outer side of the wheel, in which the outer ring is a chain; Figure 1a is an enlarged view of the detail enclosed in the circle a of Figure 1, showing the connecting hook according to the invention and two cross sections taken in two parts of the hook; Figure 2 is a front view of a self-tensioning device, taken from the inner part of the wheel, in which the inner ring is a flexible cable; Figure 2b is an enlarged view of the detail enclosed in the circle b of Figure 2, showing the connecting hook according to the invention; Figure 3 is a perspective view showing the connecting hook according to the invention; Figure 4 is a side view of the connecting hook of Figure 2b, in which the chain portions have not been shown. Figures 1 and 2 show a snow chain, indicated as a whole with reference numeral 1 and applied to a tyre 2 of a vehicle. The snow chain 1 comprises a ring element 3 disposed in the outer part of the tyre 2 and a ring element 4 disposed in the inner part of the tyre 2. The outer ring element 3 consists of a link chain, whereas the inner ring element 4 consists of a flexible cable. The outer ring element 3 and the inner ring element 4 are connected by means of chain portions 5 that generate the friction on the tread. The outer ring element 3 has a self-tensioning device 6 that serves to tension the chain of the outer ring element 3. The self-tensioning device 6 has a hook 7 that engages in a link of the terminal portion 8 of chain of the outer ring element to pull it in a tensioning direction. A non-return block 9, through which the terminal portion of the chain 8 passes, is provided in the outer ring. The non-return block 9 allows the terminal portion of chain 8 to slide only in the tensioning direction and not in the slackening direction. The chain portions 5 that create the friction on the tread are joined to the inner ring 3 and to the outer ring 4 by means of connecting hooks 10. As shown in Figure 3, the connecting hook 10 comprises a first end 11 with a first U-shaped loop 12 and a second end 13 with two second U-shaped loops 14, 14' disposed on substantially parallel planes and substantially at right angles to the plane of the first loop 12. The second two loops 14, 14' end respectively in two feet 16, 16' which constitute the two terminal parts of the hook 10. As shown in Figure 1a, two links 15 of the chain portion 5 engage in the first loop 12 of the first end 11 of the hook 10 and a chain link 26 of the outer ring 3 engages in the second loops 14, 14' of the second end 13 of the hook 10. As shown in Figure 2b, two links 15 of chain portion 5 engage in the first loop 12 of the first end 11 of hook 10, and the flexible cable of inner ring 4 engages into second loops 14, 14' of second end 13 of hook 10. As shown in Figure 1a the cross sectional shape of the hook 10 in the area of the first loop 12 is substantially circular. In this manner a good strength is given to the hook part 10 which engages with the links 15 of the chain portions 5 that confer the friction on the tread, and furthermore the rubbing friction between the first loop 12 of the hook 10 and the links 15 of chain portions 5 is limited. As shown in Figure 1a, on the other hand, the cross sectional shape of the hook 10 is substantially rectangular in proximity to the areas of the second loops 14 and 14'. In this manner there is a flattening of the two end feet 16, 16' provided in the second end 13 of the hook 10. The fact that the terminal feet 16, 16' are flattened gives the hook 10 a minimal bulk in the part that protrudes from the outer ring 3 or from the inner ring 4, thus avoiding interference of the protruding parts of the feet 16 with the mechanical parts of the vehicle. Production of the hook 10 according to the invention is extremely simple. In fact it starts from a metal bar with a circular section. The metal used can be steel or iron or spring steel. This metal bar is flattened at the two ends and then bent in the central area so as to form the U-shaped loop 12. The end areas are then bent in turn so as to form the two U-shaped loops 14, 14' which end in the end feet 16, 16', respectively, which are flattened and therefore have a smaller thickness with respect to the hook part around the loop 12. As shown in Figure 4, after the cable 4 of the inner ring is housed in the two U-shaped loops 14, 14' of the second end 13 of the hook, the end feet 16, 16' are bent inwards, so as to prevent the cable 4 from coming out Various changes and modifications of detail within the reach of a person skilled in the art can be made to the present embodiment of the invention while still remaining within the scope of the invention expressed by the appended claims.

Claims: A connecting hook for joining elements of a snow chain, comprising a first end part (11) destined to engage in at least one link (15) of a chain portion (5) creating the friction on the tread and a second end part (13) destined to engage in a part of a ring element (3, 4) that is disposed on the outer or inner side of a tyre (2), characterised in that , in a direction perpendicular to the plane defined by said first end part (11), the thickness of said second end part (13) of the hook (10) is smaller than that of said first end part (11). A hook according to claim 1, characterised in that said first end part (11) has a substantially circular cross section and said second end part (13) has a substantially rectangular cross section with the shorter side perpendicular to said plane defined by said first end part (11) the length of said shorter side of said second end part (13) being smaller than the diameter of said circular cross section of said first end part (11). A hook according to claim 1 or 2, characterised in that said first end part (11) has a first loop (12) having a substantially U-shaped configuration and said second end part (13) has two loops (14, 14') having a substantially U-shaped configuration. A hook according to claim 3, characterised in that said second loops (14, 14') are situated on substantially parallel planes, spaced apart and substantially at right angles to the plane on which said first loop (12) is situated. A hook according to any one of the preceding claims, characterised in that it is obtained from a metal bar with a substantially circular cross section whose ends (16, 16') are flattened to have a smaller thickness than the central part. A hook according to claim 5, characterised in that said bar is made of steel, or spring steel or iron. A hook according to claim 5 or 6, characterised in that said first loop (12) is made by bending into a U-shape of said bar in the central area and said second loops (14, 14') are made by bending into a U-shape of the ends (16) of said bar. A hook according to any one of the preceding claims, characterised in that said ring element (3) disposed on the outer side of the tyre (2) is a link chain and said second end part (13) of said hook engages in a link (26) of said ring element. A hook according to any one of claims 1 to 8, characterised in that said ring element (4) disposed on the inner side of the tyre is a flexible cable that engages in said second end part (13) of the hook. A snow chain comprising a first ring element (3) destined to be disposed on the outer side of a tyre (2), a second ring element (4) destined to be disposed on the inner side of a tyre and portions of chain (5) creating the friction on the tread connected to said outer ring element (3) and to said inner ring element (4), characterized in that said chain portions are connected to said inner ring element (4) and/or to said outer ring element (3) by means of at least one of said connecting hooks according to any one of the preceding claims.

Inventors: AIROLDI ROMOLO, AIROLDI, ROMOLO
Applicants: KOENIG SPA, KOENIG S.P.A.
Application year: 2000
Main classification: B60C27
IPC codes: B60C27