Abstract:
A releasing device for snow chains comprising an inner side portion ( 2 ) closable as a ring, suitable to be placed on an inner part of a tire ( 3 ), an outer side portion ( 4 ) suitable to be placed on an outer part of the tire ( 3 ), said portions being joined by variously composed elements ( 5 ) creating the tread traction, the releasing device comprising a closing device ( 8 ), for closure as a ring of the inner side portion ( 2 ) and an operating device ( 50 ), that can be operated by the user from the outside of the tire to open the closing device ( 8 ), the operating device ( 50 ) comprising protective members ( 53, 55 ) suitable to make it more stable and the closing device ( 8 ) being able to be opened manually even without the aid of the operating device.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a releasing device for snow chains or anti-skid devices intended for mounting on the tires of vehicles. 
     When a vehicle travels on a road surface covered with snow, sleet or ice, its tires 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 tread traction and allowing the vehicle tires to achieve a good grip. 
     As is known, a snow chain generally consists of two side members (chains, flexible cables, steel wires, ropes or the like) which during use are closed in a ring on the inner face and the outer face of the wheel, respectively. These side members are connected by a series of chain portions variously disposed to achieve tread traction, the whole being completed by a tensioning device for said members, known as a tensioner. 
     Types of snow chains widely available on the market have an inner side portion consisting of an inner flexible ring that can be opened to allow widening thereof during the mounting operation, so that it can be applied to the inner face of the vehicle wheel. Said inner ring normally consists of a metal cable covered with a continuous or interrupted sheath. 
     Said known chains provide an inner fastening closure according to which one end of the cable of the inner ring is provided with a hollow elongated engaging means in which a portion thereof is able to receive a head provided at the other end of the cable, while another portion thereof is able to retain said head, a channel being provided which permits shifting of the cable along said engagement means, so that the head comes to be locked inside the locking portion. 
     This type of inner closure, though allowing easy locking of the ring portion, nevertheless presents some problems during removal. 
     The user, in order to remove the chains, is obliged to work from the inner side of the wheel. In fact he must find the closing device of the inner ring in the inner side of the wheel and manually carry out release of said device. This operation proves quite awkward, tiresome and complex. In fact the user must work in an uncomfortable position, is obliged to dirty his hands which inevitably come into contact with the tire and in addition has difficulty in finding the inner ring closing device which remains hidden on the inner side of the wheel. Consequently, said operation of removal of the chains proves excessively slow and tiresome. 
     Releasing devices are also known which provide operating means that can be operated from the outer side of the wheel to bring about release of the closing member of the inner ring. Said releasing devices have drawbacks due to the complexity of the closing member. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to eliminate the drawbacks of the prior art, providing a releasing device for snow chains that is safe, practical, easy to use, inexpensive and simple to make. 
     This object is achieved in accordance with the invention having the characteristics listed in appended independent claim 1. 
     Preferred embodiments of the invention will become apparent from the dependent claims. 
     The releasing device for snow chains according to the invention provides a closing device able to close the inner side portion of the chains as a ring and an operating device that acts on the closing device. The operating device can be operated from the outside of the tire by the user and provides a cable that acts on the closing device. Said cable is protected by means of two chains disposed alongside and parallel thereto and by means of crosspieces disposed transversally with respect to the cable and fixed to the links of the chain. 
     In this manner better stabilization and better functioning of the operating device are achieved. 
     Moreover the closing device has at one end of the cable of the inner ring a block containing a first tooth urged by elastic means to protrude externally on a seat so as to block a second tooth, fixed at the other end of the cable of the inner ring, and housed in the seat of the closing device. The cable of the operating device acts on a lever pivoted inside the closing device that makes the first tooth retract, so as to release the second tooth which can be extracted from the seat. 
     Such a device proves extremely simple and effective and allows perfect operation, reducing the risks of jamming. 
     Moreover, in the event of jamming of the operating device the possibility of releasing the snow chains is still ensured. In fact the shape of the second tooth and of the seat that receives it are such as to allow a rotation of the second tooth inside said seat so that the second tooth can be extracted from the seat even when the first tooth is not retracted inside the closing device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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: 
     FIG. 1 a  is an axonometric view illustrating a wheel, taken from the inward facing side, on which is mounted a snow chain with the releasing device according to the invention; 
     FIG. 1 b  is an axonometric view illustrating a wheel, taken from the outward facing side, on which is mounted a snow chain with the releasing device according to the invention; 
     FIG. 2 is a front view, enlarged and inverted, of the releasing device in FIG. 1, shown it an open position; 
     FIG. 3 a front view, enlarged and inverted, of the releasing device of FIG. 1, shown in a closed position; 
     FIG. 4 is part-sectional a view of the releasing device as shown in FIG. 2; 
     FIG. 5 a part sectional view of the releasing device as shown in FIG. 3; 
     FIG. 6 is an exploded view of the releasing device according to the invention, in which the inner members are shown in perspective and enlarged and the half-shells are shown in a plan view; 
     FIG. 7 is a plan view of the operating device of the releasing device according to the invention; 
     FIG. 8 is a front view of a cross piece of the operating device in FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The releasing device for snow chains according to the invention is described with the aid of the figures. 
     With reference to FIG. 1, an anti-skid device, denoted as a whole by reference numeral  1 , comprises an inner side portion  2 , which is able to be disposed on the inner part of the tire  3  and an outer side portion  4 . The outer side portion  4  of the anti-skid device  1  is made in a known manner by means of a closed ring of chain. These two inner and outer portions  2  and  4  are connected by various portions of anti-skid chain  5  variously disposed on the tread of the tire, in this case in a diamond shape. 
     The inner side portion  2  consists of an openable ring, made from a steel cable  6  coated with a suitable sheath  7 , preferably not continuous. The cable  6  can be deformed to adapt to the curve of the wheel. The ring  2  is equipped at its two opening ends with a closing and locking device  8 . 
     As shown in FIGS. 2-6, the locking device  8  comprises a body consisting of two substantially symmetrical half-shells  9  which can be joined together. The half-shell  9  (FIG. 6) has a substantially rectangular central seat  10  which houses a substantially triangular lever member  11 , hinged by means of a pivot  12  in a hole  13  in the seat  10 . A through hole  14  is provided at one end of the lever member  11  to receive a cable  15  forming part of an operating device  50  described below. The cable  15  is locked in the hole  14  by means of a cylindrical block  16  with a diameter larger than the diameter of the hole  14 . The cable  15  extends from the half-shell  9  through an opening  35  in the seat  10 . The cable  15  is covered by a sheath  37  disposed outside the shell  9 . The lever  11 , at the opposite end to that in which the hole  14  is situated, has a substantially rounded surface  30 . 
     Beneath the rectangular seat  10  of the half-shell  9  a longitudinal seat  17  is provided which receives a helicoidal spring  18  and a pawl member  19 . The spring  18  is located between the rear surface  20  of the seat  17  and the rear surface  21  of the pawl member  19 . The pawl member  19  is is shaped as a substantially parallelepiped block, having at the front a tooth  22  beneath which is provided an abutment surface  24  that abuts against the forward end  25  of the longitudinal seat  17  of the half-shell  9 . On the upper surface of the pawl member  19  a concave seat  23  is provided, apt to house the rounded end  30  of the lever member  11 . 
     At the front end of the half-shell  9  is a seat  31  separated from the longitudinal seat  17  by the abutment surface  25  for the pawl member  19 . In this manner the tooth  22  partially protrudes over the seat  31 . The seat  31  has a substantially rounded lower surface  80  and a front abutment surface  81  substantially at right angles with respect to the lower surface  80 . 
     The half-shell  9  further provides a square aperture  32  connected to an opening  33  toward the outside. The end of the cable  6  which must be fixed to the locking device  8  has a rectangular block  34  that engages inside aperture  32 , whilst the cable  6  extends out from opening  33 . 
     In the upper part of the half-shell  9  two substantially semicircular seats ( 36 ) are made with a respective through hole  38  disposed in a central position. As shown in FIGS. 2 and 3, each seat  36  of the half-shell  9  receives a respective end link  52  of a chain portion  53  forming part of the operating device  50 . The end links  52  are blocked in the respective seats  36  by means of pins  39  which engage in the holes  38 . 
     As shown also in FIG. 7, the operating device  50  comprises the two chain portions  53  fixed to the closing device  8  and the cable  15  fixed to the lever  11  of the closing device  8  is covered by a sheath  37 . In order to maintain the chain portions  53  symmetrically spaced with respect to the cable  15 , cross-pieces  55 , shown better in FIG. 8, are disposed transversally with respect to the chain portions  53  and to the cable  15  with sheath  37 . 
     The cross piece  55  has a central hole through which the sheath  37  of the cable  15  extends and two side apertures which are fixed to two links of the respective chain portions  53 . Between two cross pieces, on the sheath  31 , two cylindrical blocks  58  are provided with a greater diameter than that of the hole  56  so as to be able to abut against the cross-pieces  55 , avoiding sliding of the sheath  37 , whilst the cable  17  is free to slide inside the sheath  37 . The cylindrical blocks  58  further act as protective elements and prevent wear on the sheath  37 . At its end, the cable  15  has a hook  59  suitable to be gripped by the user in order to be pulled. 
     The two ends of chain portions  53  end in a chain link  60  which has a hook so as to be fixed to a chain link of the outer ring member  4  (FIG.  1 ). In this manner the end hook  59  of the cable  15  appears on the outward facing side of the wheel. Thus the user can pull the hook  59  of the cable  15  working from the outward facing side of the wheel. 
     The other end of the cable  6  of the inner ring  3  which has remained free is fixed to a head  65  able to engage with the closing device  8 . The head  65  has two symmetrical half-shells  66  which can be fixed to one another. The half-shell  66  has a first aperture  67  to receive a block  68  fixed to the end of the cable  6  and a second aperture  69  to receive the head  70  of a hook fixed to a link of a transverse chain portion  10 . 
     The half-shell  66  has a tooth  72  with a shape substantially symmetrical to that of the tooth  22  of the pawl member  19 . The front surface  75  of the tooth  72  is substantially inclined with the same inclination as that of the tooth  22 . The underside  73  of the tooth  72  is substantially rounded like the underside  80  of the seat  31  of the half-shell  9 . The rear surface  74  of the tooth  72  is substantially at right angles with respect to the lower surface  73 . 
     Operation of the releasing device according to the invention will now be described. When the inner ring  2  is in the open position the closing device  8  and the head  65  are spaced apart, as in FIGS. 2 and 4. The user, when he wants to close the inner ring  4 , pushes the front surface  75  of the tooth  72  of the head  65  on to the front surface of the tooth  22  of the releasing device. Consequently a retraction of the pawl member  19  which compresses the spring  18  is effected and the tooth  72  is accommodated in the seat  31 . Thus, when the tooth  72  is accommodated in the seat  31 , the pawl member  19 , urged by the spring returns to its initial position, in which the abutment surface  24  thereof abuts against the stopping surface  25  of the half-shell  9 . 
     In this situation, as shown in FIGS. 3 and 5, the tooth  22  of the releasing device is situated above the tooth  72  of the head  65 . Consequently traction on the cable  6  of the inner ring  2  cannot bring about disengagement of the head  65  from the closing device  8 . In fact, the rear surface  74  of the tooth  72  abuts against the front surface  81  of the seat  31  and the tooth  22  prevents the tooth  72  from jumping out of the seat  31 . 
     In order to open the closing device  8 , the user exerts traction on the cable  15 , pulling the hook  59 . Consequently the block  16  fixed at the end of the thread  15  inside the closing device  8 , raises the arm of the lever member  11  which turns around the pivot  12 . The end  30  of the lever member then pushes the pawl member  19  rearward, compressing the spring  18 . As a consequence of this the tooth  22  retracts inside the half-shell  9  freeing the seat  31  thus the tooth  72  of the head  65  can be extracted from the seat  31 . 
     Furthermore, in the event of jamming of the operating device  50 , the particular curved shape of the lower surface  73  of the tooth  72  and of the lower surface  80  of the seat  31  allows extraction of the tooth  72  from the seat  31  by means of rotation of the head  65  even when the tooth  22  is in the extracted position on the seat  31 . 
     Numerous variations and changes of detail within the reach of a person skilled in the art can be made to the present embodiment of the invention, without thereby departing from the scope of the invention expressed by the appended claims.