Patent Publication Number: US-7712497-B2

Title: Anti-slipping device for dual tires

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an anti-slipping device for dual tires, and more particularly, to an anti-slipping device for dual tires used as a rear wheel of a large car, in which a plurality of spike members connected by a belt are inserted between the dual tires at regular intervals, and opposite ends of the belt are tightly fastened together by a fastener, thereby stably providing running performance and braking power to minimize a risk of a slipping accident. 
   2. Description of the Related Art 
   In general, a chain, an integral chain that cables or urethane blocks are interconnected, a snow-tread tire, a spike tire, etc. are prepared for a snowy or icy road. 
   In the case of the chain or integral chain, they damage the road surface and make a pothole on the road, so that use of the chain or integral chain is restricted on expressways to prevent an accident due to the pothole from happening. 
   Further, a mounting work of the chain or integral chain is very complicated and difficult, for example, the wheel should be rotated forward and backward for mounting them thereon. It is difficult for even a burly man to normally and tightly mount the chain on the wheel on a cold winter&#39;s day. Thus, the chain may be broken away from the wheel or lost while running, thereby causing an accident. Also, the chain may be so damaged that it cannot be reused. 
   Meanwhile, if the chain or integral chain is mounted on an inside tire of dual tires, the mounting work is allowed under the condition that the dual tires are all taken out from a vehicle or the vehicle is jacked up. Further, the chain should be intertwined on the whole surface of the tire, so that it takes at least 30 minutes to 1 hour to mount the chain on the wheel. The chain itself tips the scales at 50 kg×2=100 kg, and the trip distance cannot exceed 100 km. 
   In the case of the snow tire or spike tire, it is difficult to quickly replace a normal tire with the snow or spike tire on the road according to sudden weather changes, so that a user has to drive the vehicle dangerously in order to take the vehicle to a garage. Also, the snow and spike tires are relatively expensive and decrease fuel efficiency, so that they are not economical. 
   To solve these problems, an idea such as a pad-type snow chain which is connected in a straight line has been proposed, but there are many problems to apply it to a practical vehicle. If the straight-line connection pad is applied to the vehicle, it increases a risk of an accident in comparison the existing chain. 
   For example, abrasion resistance of a saw-tooth provided in the pad is bad, so that the saw-tooth is easily abraded by running of about 20˜30 km. Thus, this pad cannot be used as the snow chain. Further, a contact rate between the saw-tooth spike and the road is so high that it runs afoul of the law. 
   Further, a curved angle of the pad closely-attached between the dual tires is so large that the close-contact between the pad and the tire is inferior if a space between the dual tires is narrow, thereby damaging the tires or breaking the chain. 
   Also, when the chain is fastened at the last stage of the mounting work, a fastener is unstable and causes the chain to be easily loosed or broken during running. Due to such problems, the straight-line connection pad requires a lot of complements so as to be applied to the practical vehicle. 
   SUMMARY OF THE INVENTION 
   First, the present invention is directed to an anti-slipping device for dual tires, in which double spikes that are different in height protrude from an outer surface of a spike member, i.e., a contact surface in contact with a road surface, so that the double spikes are prevented from abrasion and thus semipermanently usable, thereby minimizing road damage and increasing friction between the tire and the road surface to enhance braking power. 
   Second, the present invention is directed to an anti-slipping device for dual tires, in which a close-contact plate of a spike member is inclined at a predetermined angle to closely contact each surface of the dual tires, so that close-contact between the device and the tire increases to thereby prevent the wheel from idling and enhance driving comfort. 
   Third, the present invention is directed to an anti-slipping device for dual tires, in which an outer surface of a spike member, i.e., a contact surface in contact with a road surface is formed with at least one curved part, so that contact between a circumferential area of the spike member and the road surface is minimized while the tire rolls, thereby effectively preventing the spike member from bending at high speed running. 
   Fourth, the present invention is directed to an anti-slipping device for dual tires, in which a plurality of spike members are coupled to a synthetic resin belt at regular intervals, thereby preventing noise and lessening impact while running; effectively preventing the spike member from tangling; and decreasing weight to enhance convenience of mounting and portability. 
   Fifth, the present invention is directed to an anti-slipping device for dual tires, in which opposite ends of a belt having a plurality of spike members fixed thereto are detachably coupled with a length-adjustable fastener, so that it is convenient for a user to mount/remove the device on/from the tire and to more tightly fasten the device. 
   According to an aspect of the present invention, an anti-slipping device for dual tires includes: a plurality of spike members  100  which includes an insertion plate  110  bent in a trapezoidal shape to be inserted between the dual tires, and close-contact plates  120  integrally extending from opposite sides of the insertion plate  110  to closely contact each surface of the dual tires; a belt  200  for connecting the insertion plates  110  of the plurality of spike members  100  to each other; and a fastener  300  detachably coupled to opposite ends of the belt  200  to adjust tension of the belt, wherein the fastener  300  includes first and second connection rings  330   a  and  330   b  each inserted into insertion space parts  210   a  and  210   b  formed at both ends of the belt  200 , and a belt fastener  340  detachably coupled to the first and second connection rings  330   a  and  330   b  to adjust tension of the belt  200 . 
   The outer surface of the close-contact plate  120  of the spike member  100  may be provided with at least one first recessed part  112  having a straight shape to prevent the spike member  100  from bending. 
   A plurality of first and second spikes  121  and  122  may protrude from an outer surface of each close-contact plate  120  of the plurality of spike members  100  at regular intervals to be different in height from each other to prevent friction with a road surface and slipping. 
   The plurality of first spikes  121  may be lengthwise arranged on a middle of the close-contact plate  120  at regular intervals, and include a hole  121   a  penetrating the close-contact plate  120  and a cylindrical projection  121   b  integrally protruding from an outer circumference of the hole  121   a.    
   A top surface of the projection  121   b  may be formed with an uneven part  121   c  having a regular or irregular saw-tooth for increasing friction with the road surface. 
   The plurality of second spikes  122  may be arranged in a zigzag pattern or a W-shape between the plurality of first spikes  121 . 
   A protrusion  123  may protrude from an outer periphery of the close-contact plate  120 . 
   The outer surface of the close-contact plate  120  of the spike member  100  may be provided with at least one second recessed part  124  having a straight shape to prevent the spike member  100  from bending. 
   A pair of third recessed parts  125  each having a V-shape may protrude from opposite positions where the insertion plate  110  and the close-contact plates  120  of the spike member  100  are connected, to prevent the spike member  100  from bending. 
   A fourth recessed part  126  having an embossed shape may project from an outer surface of the close-contact plate  120  adjacent to a connection part of the insertion plate  110  and the close-contact plate  120  of each spike member  100  to prevent damage to the spike member  100 . 
   An auxiliary plate  130  may be further fixed to an inner surface of each spike member  100 , the auxiliary plate including an insertion plate  110 ′ having the same shape as the spike member  100 , and close-contact plates  120 ′ integrally extending from opposite sides of the insertion plate  110 ′ to closely contact each surface of the dual tires. 
   The belt fastener  340  may include a length adjustment part  341  having a first fastening ring  341 - 1  detachably coupled to the first connection ring  330   a  at its one end, and a plurality of length adjustment holes  341 - 2  formed in a longitudinal direction thereof at predetermined intervals; and a tensioning member  342  having a second fastening ring  342 - 2  coupled to the second connection ring  330   b  at its one end, such that the other end of the length adjustment part  341  is slidably inserted into the second fastening ring to sequentially lock or release the length adjustment holes  341 - 2  using a predetermined resilient force to maintain tension of the belt  200 . 
   The length adjustment part  341  may have a predetermined radius of curvature. 
   The length adjustment part  341  may include a plurality of separated length adjustment members and a connection wire connected to the length adjustment members, wherein each length adjustment member has a plurality of length adjustment holes  341 - 2  formed in a longitudinal direction thereof at predetermined intervals, and the connection wire is inserted into outer peripheries of the length adjustment members such that ends of the length adjustment members are in contact with each other. 
   Preferably, a first length adjustment member installed at one end of the length adjustment part has a pair of first protrusions protruding from both long side surfaces thereof, first connection holes are formed in the pair of first protrusions in a longitudinal direction thereof to insert or extract the connection wire into or from the connection holes, a first fastening ring  341 - 1  is formed at one end of thereof to be coupled to the first connection ring  330   a , a second length adjustment member installed at the other end of the length adjustment part has a second protrusion protruding from an outer periphery of thereof, and a second connection hole is formed in the second protrusion in a longitudinal direction thereof to insert or extract the connection wire into or from the second connection hole. 
   At least one third length adjustment member may be further installed between the first and second length adjustment members, wherein a pair of third protrusions project from both long side surfaces of the third length adjustment member, and third connection holes are formed in the pair of third protrusions in a longitudinal direction thereof to insert or extract the connection wire into or from the third connection holes. 
   The tensioning member  342  may include a mounting plate  342 - 1  in which the length adjustment part  341  is inserted and mounted; a second locking ring  342 - 2  fixedly formed at one end of the mounting plate  342 - 1  to be detachably coupled to the second ring  330   b ; a pair of first and second support plates  342 - 3  and  342 - 30  vertically bent from both sides of the mounting plate  342 - 1  and parallelly aligned with each other; an insertion guide shaft  342 - 4  disposed under one ends of the first and second support plates  342 - 3  and  342 - 3 ′ at its both ends and fixed at a predetermined height such that the other end of the length adjustment part  341  is slidably inserted; a first hinge shaft  342 - 5  fixedly coupled to one upper sides of the first and second support plates  342 - 3  and  342 - 3 ′ at its both ends; a locking pivot pin  342 - 6  pivotally coupled to a center part of the first hinge shaft  342 - 5 , and having a locking fixing piece  342 - 6   a  and a locking release piece  342 - 6   b  formed at its both ends to lock and release the length adjustment holes  341 - 2  when the length adjustment part  341  is inserted; a second hinge shaft  342 - 7  fixedly coupled to the other upper sides of the first and second support plates  342 - 3  and  342 - 3 ′ at its both ends; and a spring  342 - 8  having a predetermined resilient force, pivotally coupled to one side of the second hinge shaft  342 - 7 , one end of which is fixedly coupled to an outer side of the other end of the first support plate  342 - 3 , and the other end of which resiliently supports an upper surface of the locking fixing piece  342 - 6   a  to resiliently maintain a state in which the locking fixing pin  342 - 6   a  is locked by the length adjustment hole  341 - 2 . 
   The tensioning member may further include a cover  342 - 9  fixedly coupled to upper surfaces of the pair of first and second support plates  342 - 3  and  342 - 3 ′, and a locking bolt  342 - 10  threadedly fastened to a threaded hole  342 - 9   a  formed at a center of the cover  342 - 9  to be in contact with an upper surface of the locking fixing piece  342 - 6   a  at its tip to prevent pivotal movement of the locking pivot pin  342 - 6  due to an external force. 
   The tensioning member may further include a locking piece  342 - 11  formed at the tip of the locking bolt  342 - 10  to prevent separation of the locking bolt  342 - 10  from the threaded hole  342 - 9   a.    

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  is a perspective view of an anti-slipping device for dual tires, which is rolled out in a lengthwise direction by separating a spike member and a fastener; 
       FIGS. 2 through 4  are enlarged perspective views of “A”, “B” and “C” in  FIG. 1 , respectively; 
       FIGS. 5 and 6  are perspective views and a cross-sectional view of a first example of a spike member according to an embodiment of the present invention; 
       FIG. 7  is a cross-sectional view of a second example of a spike member according to an embodiment of the present invention; 
       FIG. 8  is perspective view of a third example of a spike member according to an embodiment of the present invention; 
       FIGS. 9A and 9B  are exploded and coupled perspective views of a fourth example of a spike member according to an embodiment of the present invention; 
       FIG. 10  is exploded perspective view of a fifth example of a spike member according to an embodiment of the present invention; 
       FIG. 11  is an exploded perspective view illustrating the connection between a spike member and a belt according to an embodiment of the present invention; 
       FIGS. 12 and 13  are perspective views illustrating coupling between a fastener and a belt according to an embodiment of the present invention; 
       FIGS. 14 through 16  are cross-sectional views illustrating coupling between a fastener and a belt according to an embodiment of the present invention; 
       FIGS. 17A and 17B  are exploded and coupled perspective views of an example of a length adjustment part according to an embodiment of the present invention; 
       FIGS. 18A and 18B  are a perspective view and a cross-sectional view taken along line A-A′ showing another exemplary structure of a length adjustment part applied to the embodiment of the present invention; 
       FIGS. 19A and 19B  are a perspective view and a cross-sectional view taken along line B-B′ showing still another exemplary structure of a length adjustment part applied to the embodiment of the present invention; and 
       FIGS. 20A and 20B  are exploded and assembled perspective views showing yet another exemplary structure of a length adjustment part applied to the embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
   Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
   Referring to  FIGS. 1 to 20 , an anti-slipping device for dual tires according to an embodiment of the present invention includes a plurality of spike members  100 , a belt  200  connecting the spike members  100 , and a fastener  300  coupled to opposite ends of the belt  200  and adjusting tension of the belt  200 . 
   Here, the plurality of spike members  100  are shaped like a metal plate, and include an insertion plate  110  bent in a trapezoidal ( ) shape in the middle thereof to be inserted between the dual tires (not shown in the drawings, which are used as a rear wheel of a large truck or the like), and close-contact plates  120  integrally and flatly extending from opposite sides of the insertion plate  110  and closely contacting each surface of the dual tires. 
   At this time, a top surface of the insertion plate  110  of the spike member  100  is formed with at least one through hole  111  to be coupled with the belt  200  by a coupling unit such as a bolt, a nut, etc. 
   In addition, at least one first recessed part  112  may further project from the insertion plate  110  in a straight shape to prevent the spike member  100  from bending during high speed running. 
   Meanwhile, a lateral gap between both surfaces of the insertion plate  110  gradually narrows toward its center part to form a trapezoidal shape to thereby effectively prevent damage to the insertion plate  110  during high speed running. 
   Further, a plurality of double spikes, i.e., first and second spikes  121  and  122  protrude from an outer surface (in contact with a road surface) of the close-contact plate  120  of the spike member  100  at regular intervals so as to be different in height, thereby enhancing friction with the road surface and preventing slipping. 
   In more detail, the plurality of first spikes  121  are arranged at regular intervals on the middle of the close-contact plate  120  in a lengthwise direction. The first spike  121  includes a hole  121   a  penetrating the close-contact plate  120 , a projection  121   b  integrally protruding from a circumference of the hole  121   a  and having a cylindrical shape, and an uneven part  121   c  formed on a top surface (in contact with the road surface) of the projection  121   b  and shaped like a regular or irregular saw-tooth to increase friction with the road surface. 
   The plurality of second spikes  122  are fixedly coupled to the opposite sides of the close-contact plate  120  by a rivet between the first spikes  121 . For example, the second spike  122  is formed of metal materials such as tungsten or the like, which has high stiffness and good abrasion resistance. 
   The plurality of second spikes  122  are stuck into snow or ice on the road, so that the friction between the road and the anti-slipping device increases, thereby effectively preventing the vehicle from slipping and consulting safety running of the vehicle. 
   Further, the plurality of second spike  122  are shaped like a cone, so that a contact rate between the road and the anti-slipping device is minimized, thereby rarely damaging the road surface to satisfy regulations of various countries (e.g., United States and so on). 
   Also, the second spike  122  protrudes higher than the first spike  121  by a predetermined height (preferably, about 1 mm˜3 mm), so that the first spike  121  for anti-slipping on the snowy road is effectively prevented from abrasion on the way of running. 
   Additionally, the plurality of second spikes  122  are arranged not in a straight-line but in a zigzag pattern or a W-shape along a width direction of the close-contact plate  120 , so that a scratch area becomes larger on the icy road, thereby maximizing the braking power. 
   Additionally, a protrusion  123  may further protrude from an outer periphery of the close-contact plate  120  (a portion in contact with a road surface), and regular or irregular teeth shaped uneven parts (see  121   c  of  FIG. 6 ) may be further formed at an upper surface over the protrusion  123 , that is, a portion in contact with a road surface, to increase a friction force to the road surface. 
   The protrusion  123  may be bent from an outer periphery of the close-contact plate  120 , i.e., a contact surface with the road surface, at a predetermined angle (preferably, about 0° to 90°). 
   In addition, at least one second recessed part  124  protruding from an outer surface of the close-contact plate  120 , i.e., a contact surface with the road surface, to form a longitudinally straight shape to minimize a contact surface of the close-contact plate  120  of the spike member  100  to the road surface during rotation of the tire, thereby effectively preventing the spike member  100  from bending during high speed running. 
   Also, for example, a pair of third recessed parts  125  each having a V-shape additionally protrude from opposite positions where the insertion plate  110  and the close-contact plates  120  of the spike member  100  are connected, thereby further effectively preventing the spike member  100  from bending at the high speed running. 
   Further, a fourth recessed part  126  having an embossed shape may further protrude from an outer surface of the close-contact plate  120  adjacent to a connection part of the insertion plate  110  and the close-contact plate  120 , i.e., a contact surface with the road surface, to effectively prevent damage to the spike member  100  during high speed running. 
   Meanwhile, the close-contact plate  120  may be bent from both sides of the insertion plate  110  at a predetermined angle θ corresponding to a lateral radius of curvature of each tire of dual tires to be more closely contacted with a surface of each tire (see  FIG. 7 ). At this time, the predetermined angle θ may be about 3° to 7° (preferably, about 5°). 
   As shown in  FIG. 8 , the first recessed part  112  and the third recessed parts  125  of the spike member  100  are removed, the second recessed parts  124  is changed into embossing pattern, the connection part of the insertion plate  110  and the close-contact plate  120  is curved. 
   Moreover, as shown in  FIGS. 9A and 9B , an auxiliary plate  130  may be further installed at an inner surface of the spike member  100  (a portion in close contact with the surface of the tire) to effectively prevent separation of the spike member  100  upon breakage of the spike member  100  during high speed running, prevent the spike member  100  from bending, and effectively reinforce strength of the spike member  100 . 
   The auxiliary plate  130  is formed of a thin steel plate having the same shape as the spike member  100 . Similar to the spike member  100 , the auxiliary plate  130  includes an insertion plate  110 ′ and close-contact plates  120 ′ extending from both sides thereof in parallel. At least one through hole  111 ′ is formed in the upper surface of the insertion plate  110 ′ at the same position and size as the at least one through hole  111  of the insertion plate  110  of the spike member  100  in order to fix the auxiliary plate  130  to the spike member  100  and the belt  200  using a fixing means such as a bolt and a nut BN. 
   In addition, a plurality of coupling holes  135  are formed in the close-contact plates  120 ′ of the auxiliary plate  130  at the same positions as the second spikes  122  such that the second spikes  122  are inserted into the coupling holes  135  to securely fix the close-contact plates  120  of the spike member  100  to the auxiliary plate  130  through the same method as the second spikes  122  fixed to the close-contact plates  120  of the spike member  100 , i.e., a conventional riveting method. 
   Meanwhile, As shown in  FIG. 10 , the auxiliary plate  130  is formed with only the close-contact plates  120 ′ without the insertion plate  110 ′. 
   With this configuration, the plurality of spike members  100  can be conveniently replaced piece by piece, so that it is semipermanently usable. 
   In the meantime, the belt  200  is made of a synthetic resin material. To increase tension, the belt  200  can be formed by stacking at least one synthetic resin material. It is preferable but not necessary, like a general flat belt, that the belt  200  includes a polyimid interior and a Nitrile-Butadiene Rubber (NBR) surface resistant to friction and abrasion. 
   As shown in  FIGS. 2 and 3 , the opposite ends of the belt  200  are formed with insertion spaces  210   a  and  210   b  in which first and second locking rings of the fastener  300  to be described are later coupled. 
   The insertion spaces  210   a  and  210   b  may be formed by folding the end of the belt  200  by a predetermined length onto the belt  200  to cross over at least one spike member  100 , and then fixedly fastening it with a bolt, a nut N, or the like. 
   The plurality of spike members  100  are coupled to the belt  200  having this configuration at regular intervals, thereby preventing noise and lessening impact while running; effectively preventing the spike member from tangling; and decreasing weight to enhance convenience of mounting and portability. 
   With regard to the coupling between the spike member  100  and the belt  200 , as shown in  FIG. 11 , the belt  200  is coupled to the top surface of the insertion plate  110  of the spike member  100  by inserting at least one bolt, at least one nut N and at least one washer W into the through hole  111  formed on the insertion plate  110  of the spike member  100 . 
   In this embodiment, the spike member  100  and the belt  200  are coupled by the bolt and the nut N, but not limited thereto. Alternatively, the spike member and the belt may be coupled by a typical rivet. 
   In addition, as shown in  FIGS. 1 , and  12  to  16 , the fastener  300  includes first and second connection rings  330   a  and  330   b  inserted into insertion space parts  210   a  and  210   b  formed at both ends of the belt  200 , and a belt fastener  340  coupled to the first and second connection rings  330   a  and  330   b  to adjust tension of the belt  200 . 
   Here, the belt fastener  340  may include a length adjustment part  341  having a first fastening ring  341 - 1  coupled to the first connection ring  330   a  at its one end, and a plurality of length adjustment holes  341 - 2  formed in a longitudinal direction thereof at predetermined intervals; and a tensioning member  342  having a second fastening ring  342 - 2  coupled to the second connection ring  330   b  at its one end, such that the other end of the length adjustment part  341  is slidably inserted inside the second fastening ring to sequentially lock or release the length adjustment holes  341 - 2  using a predetermined resilient force to maintain tension of the belt  200 . 
   Specifically describing, the length adjustment part  341  is formed of a rectangular steel plate, for example, a 30 cm steel scale. A first fastening ring  341 - 1  is formed at one end of the length adjustment part  341  to be coupled to the first connection ring  330   a , and a plurality of length adjustment holes  341 - 2  are formed in a longitudinal direction of the length adjustment part  341  at predetermined intervals. 
   The length adjustment part  341  may have a predetermined radius of curvature to correspond to a radius of curvature when the anti-slipping device in accordance with the present invention is coupled to each tire of the dual tires. 
   Meanwhile, as shown in  FIGS. 17A and 17B , another embodiment of the length adjustment part  341  includes first to fourth length adjustment members  341   a  to  341   d , separated from each other, and a connection wire L fixed thereto, rather than the length adjustment part  341  of the above embodiment, which is integrally formed. 
   The length adjustment part  341  has the same function and shape as the length adjustment part  341  of the above embodiment when the first to fourth length adjustment members  341   a  to  341   d  are connected to each other by the connection wire L. 
   The first to fourth length adjustment members  341   a  to  341   d  each is formed of a rectangular steel plate, and each has a plurality of length adjustment holes  341 - 2  formed in a longitudinal direction thereof at predetermined intervals. 
   Here, a pair of first protrusions  341   a - 1  and  341   a - 1 ′ protrude from both long side surfaces of the first length adjustment member  341   a  installed at one end of the length adjustment part  341 , and first connection holes H 1  and H 1 ′ are formed in the pair of first protrusions  341   a - 1  and  341   a - 1 ′ in a longitudinal direction thereof to insert or extract the connection wire L into or from the first connection holes H 1  and H 1 ′. In addition, a first fastening ring  341 - 1  is formed at one end of the first length adjustment member  341   a  to be coupled to the first connection ring  330   a.    
   Further, a fourth protrusion  341   d - 1  protrudes from an outer periphery of the fourth length adjustment member  341   d  installed at the other end of the length adjustment part  341 , and a fourth connection hole H 4  is formed in the fourth protrusion  341   d - 1  to insert or extract the connection wire L into or from the fourth connection hole H 4 . 
   Furthermore, a pair of second protrusions  341   b - 1  and  341   b - 1 ′ protrude from both long side surfaces of the second length adjustment member  341   b  installed between the first and fourth length adjustment members  341   a  and  341   d , and second connection holes H 2  and H 2 ′ are formed in the pair of second protrusions  341   b - 1  and  341   b - 1 ′ in a longitudinal direction thereof to insert or extract the connection wire L into or from the connection holes H 2  and H 2 ′. 
   In addition, a pair of third protrusions  341   c - 1  and  341   c - 1 ′ protrude from both long side surfaces of the third length adjustment member  341   c  installed between the first and fourth length adjustment members  341   a  and  341   d , and third connection holes H 3  and H 3 ′ are formed in the pair of third protrusions  341   c - 1  and  341   c - 1 ′ in a longitudinal direction thereof to insert or extract the connection wire L into or from the connection holes H 3  and H 3 ′. 
   While the connection wire L is formed of a steel wire in which a plurality of steel cores are twisted, but not limited thereto, the connection wire L may be formed of a metal or synthetic resin wire, which is not readily broken. 
   Coupling of the first to fourth length adjustment member  341   a  to  341   d  is performed by inserting one end of the connection wire L having a certain length through the first connection hole H 1 , the second connection hole H 2 , the third connection hole H 3 , the fourth connection hole H 4 , the third connection hole H 3 ′, the second connection hole H 2 ′, and the first connection hole H 1 ′, and then, the one end and the other end of the connection wire L are securely fixed to a conventional fixing means such as a clip, a punch, welding, or the like, to closely contact ends of the first to fourth length adjust members  341   a  to  341   d  with each other to form the same shape as the length adjustment part  341  of the one embodiment. 
   While the length adjustment part  341  of another embodiment is described to include four length adjustment members (see  FIGS. 17A and 17B ), but not limited thereto, the length adjustment part may include at least two separated members. 
   Since the length adjustment part  341  of another embodiment includes the first to fourth length adjustment members  341   a  to  341   d , it is possible to effectively reduce probability of damaging to the length adjustment part  341  of the one embodiment. 
     FIGS. 18A and 18B  are a perspective view and an A-A′ cross-sectional view showing another exemplary structure of a length adjustment part applied to the embodiment of the present invention, showing the length adjustment part  341 ′ in which the first to fourth length adjustment members  341   a  to  341   d , the first to fourth protrusions  341   a - 1  and  341   a - 1 ′ to  341   c - 1 , and the first to fourth connection holes H 1  to H 4 , shown in  FIGS. 17A and 17B , are integrally formed with each other. 
   That is, the length adjustment part  341 ′ is formed of a rectangular steel plate, for example, a 30 cm steel scale. A fifth protrusion  341   e  protrudes from an outer periphery of the length adjustment part  341 ′, and a fifth connection hole H 5  is formed in a longitudinal direction of the fifth protrusion  341   e  to insert or extract the connection wire L into or from the connection hole H 5 . In addition, the connection wire L is fixedly inserted into the fifth connection hole H 5 . 
     FIGS. 19A and 19B  are a perspective view and a B-B′ cross-sectional view showing still another exemplary structure of a length adjustment part applied to the embodiment of the present invention. The fifth connection hole H 5  and the connection wire L provided in the integrated length adjustment part  341 ′ shown in  FIGS. 18A and 18B  are removed, and the fifth protrusion  341   e  is inwardly folded at a lower surface of the length adjustment part  341 ′ to opposite each other, thereby improving tensile strength of the length adjustment part  341 ′ to effectively prevent crack and breakage thereof during running. 
   In addition, a reinforcement rib R projects around the length adjustment holes formed in the length adjustment part  341 ′ to improve strength thereof. 
     FIGS. 20A and 20B  are exploded and assembled perspective views showing yet another exemplary structure of a length adjustment part applied to the embodiment of the present invention, showing constitution in which an auxiliary length adjustment part  341 ″ is dually coupled to the length adjustment part  341  shown in  FIGS. 12 to 16 . 
   That is, the auxiliary length adjustment part  341 ″ is formed of a thin steel plate having the same shape as the length adjustment part  341 . A auxiliary fastening ring  341 - 1 ′ is formed at one end of the auxiliary length adjustment part  341 ″ to be coupled to the first connection ring  330   a , and a plurality of length adjustment holes  341 - 2 ′ are formed in a longitudinal direction of the auxiliary length adjustment part  341 ″ at predetermined intervals. 
   The auxiliary length adjustment part  341 ″ is securely fixed to an upper or lower surface of the length adjustment part  341  using a conventional fixing means (for example, a bolt and nut, welding, and so on) to effectively prevent the length adjustment part  341  from being broken and separated therefrom during high speed running and effectively reinforce strength of the length adjustment part  341 . 
   In addition, the tensioning member  342  may include a mounting plate  342 - 1  in which the length adjustment part  341  is inserted and mounted; a second locking ring  342 - 2  fixedly formed at one end of the mounting plate  342 - 1  to be coupled to the second ring  330   b ; a pair of first and second support plates  342 - 3  and  342 - 3 ′ vertically bent from both sides of the mounting plate  342 - 1  and parallelly aligned with each other; an insertion guide shaft  342 - 4  disposed under one ends of the first and second support plates  342 - 3  and  342 - 3 ′ at its both ends and fixed at a predetermined height such that the other end of the length adjustment part  341  is slidably inserted; a first hinge shaft  342 - 5  fixedly coupled to one upper sides of the first and second support plates  342 - 3  and  342 - 3 ′ at its both ends; a locking pivot pin  342 - 6  pivotally coupled to a center part of the first hinge shaft  342 - 5 , and having a locking fixing piece  342 - 6   a  and a locking release piece  342 - 6   b  formed at its both ends to lock and release the length adjustment holes  341 - 2  when the length adjustment part  341  is inserted; a second hinge shaft  342 - 7  fixedly coupled to the other upper sides of the first and second support plates  342 - 3  and  342 - 3 ′ at its both ends; and a spring  342 - 8  having a predetermined resilient force, pivotally coupled to one side of the second hinge shaft  342 - 7 , one end of which is fixedly coupled to an outer side of the other end of the first support plate  342 - 3 , and the other end of which resiliently supports an upper surface of the locking fixing piece  342 - 6   a  to resiliently maintain a state that the locking fixing pin  342 - 6   a  is locked by the length adjustment hole  341 - 2 . 
   Additionally, the tensioning member may further include a cover  342 - 9  fixedly coupled to upper surfaces of the pair of first and second support plates  342 - 3  and  342 - 3 ′, and a locking bolt  342 - 10  threadedly fastened to a threaded hole  342 - 9   a  formed at a center of the cover  342 - 9  to be in contact with an upper surface of the locking fixing piece  342 - 6   a  at its tip to prevent pivotal movement of the locking pivot pin  342 - 6  due to an external force (for example, pressure, vibrations, or the like). 
   In addition, a nut  342 - 12  may be further coupled to the locking bolt  342 - 10 , and handle parts  342 - 12   a  project from an outer periphery of the nut  342 - 12  to allow a user to readily couple the nut to the locking bolt. The handle parts  342 - 12   a  may be formed at the outer periphery of the nut  342 - 12  to oppose each other. 
   Therefore, both the locking bolt  342 - 10  and the nut  342 - 12  are securely fixed to a threaded hole  342 - 9   a  formed at a center part of the cover  342 - 9  to effectively prevent the locking bolt  342 - 10  from loosening due to high speed running. 
   Here, the pair of first and second support plates  342 - 3  and  342 - 3 ′ may be integrally coupled to the cover  342 - 9 , but not limited thereto, may be securely coupled to the cover by a conventional fixing means (for example, adhesive, a screw, welding, or the like). 
   Moreover, the tensioning member may further include a locking piece  342 - 11  formed at a tip of the locking bolt  342 - 10  to prevent separation of the locking bolt  342 - 10  from the threaded hole  342 - 9   a.    
   The fastener  300  applied to the embodiment of the present invention can be more conveniently attached and detached to/from the belt  200  to effectively adjust tension of the belt  200 . 
   As shown in  FIGS. 12 to 16 , coupling between the fastener  300  and the belt  200  in accordance with an exemplary embodiment of the present invention is performed as follows. The first and second connection rings  330   a  and  330   b  are inserted into the insertion space parts  210   a  and  210   b  formed at both ends of the belt  200 , and the first fastening ring  341 - 1  of the length adjustment part  341  and the second fastening ring  342 - 2  of the tensioning member  342  are coupled to the first and the second connection rings  330   a  and  330   b . In this state, when the other end of the length adjustment part  341  is slidably inserted into a space between the mounting plate  342 - 1  and the insertion guide shaft  34204 , the locking fixing piece  342 - 6   a  of the locking pivot pin  342 - 6  resiliently supported by the spring  342 - 8  is pushed by the other end of the length adjustment part  341  to be vertically moved with reference to the first hinge shaft  342 - 5  like a seesaw such that the plurality of length adjustment holes  341 - 2  are sequentially locked and released. 
   In addition, when the tension of the belt  200  is somewhat tightened, the locking fixing piece  342 - 6  is locked by the length adjustment hole  341 - 2  most adjacent to the locking fixing piece  342 - 6  to maintain tension of the belt  200 . 
   Then, the locking bolt  342 - 10  fastened to the threaded hole  342 - 9   a  of the cover  342 - 9  is rotated in one direction (clockwise) such that the tip of the lock bolt  342 - 10  is in contact with an upper surface of the locking fixing piece  342 - 6   a  to lock the locking pivot pin  342 - 6 , thereby effectively preventing the length adjustment part  341  from being separated from the tensioning member  342  during high speed running. 
   Meanwhile, when the fastener  340  is disassembled, first, the locking bolt  342 - 10  is rotated in the other direction (counterclockwise) such that the tip is spaced a certain gap from the upper surface of the locking fixing piece  342 - 6   a  to release the locking state of the locking pivot pin  342 - 6 , and then, the locking release piece  342 - 6   b  of the locking pivot pin  342 - 6  is pushed by a predetermined pressure to release the locking fixing piece  342 - 6  from the length adjustment hole  341 - 2 . In this state, the length adjustment part  341  is pulled to be entirely separated from the tensioning member  342 . 
   When the anti-slipping device for dual tires in accordance with the present invention is installed to the dual tires, the insertion plate  110  of each spike member  100  is inserted into a space between the dual tires, and at the same time, the close-contact plates  120  are in close contact with surfaces of the dual tires  10 . In this state, the first and second connection rings  330   a  and  330   b  of the fastener  300  are coupled to the insertion space parts  210   a  and  210   b  formed at both ends of the belt  200 , and then, the length adjustment part  341  of the belt fastener  340  is inserted inside the tensioning member  342  to tightly maintain the tension of the belt  200 . 
   In more detail, as shown in  FIG. 1 , in the state that the spike members  100  connected by the belt  200  are lengthwise rolled out on the road surface, one end of the belt  200  is put from the lower rear to the front of the dual tires, and then the insertion plate  110  of the spike member  100  is inserted between the dual tires and the close-contact plates  120  closely-contact the surfaces of the tires while the dual tires are wrapped with the spike members  100 . 
   Next, the first and second connection rings  330   a  and  330   b  of the fastener  300  are coupled to the insertion space parts  210   a  and  210   b  of the belt  200 , and then, the length adjustment part  341  of the belt fastener  340  is inserted inside the tensioning member  342  to tightly maintain the tension of the belt  200 . 
   While the present invention has been described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications in form and detail may be made therein without departing from the scope of the present invention as defined by the following claims.