Abstract:
A traction device in a system comprises a tread member and a retaining member assembled to the tread member to form an interactive system. The retaining member holds the tread member in substantially complete surface contact with the tire tread in order to maintain a maximum coefficient of friction between a lower surface of the tread member and an outer surface of the tire tread. The retaining member comprises first and second ends comprising a hook and loop fastener system. The retaining member comprises a section for closely gripping tire sidewalls and a wheel. A hook and loop fastener is shaped to provide a locked assembly resistant to forces that would tend to disassemble the lock.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims priority from Provisional Patent Application Ser. No. 62/015,381 entitled TIRE TRACTION DEVICE, filed on Jun. 20, 2014. The contents of this provisional patent application are fully incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present subject matter relates to wheels for land vehicles, and more particularly to devices for increasing traction having a traction member removably secured to a tire tread. 
       BACKGROUND 
       [0003]    In climates in which roads become covered with snow, the use of traction-increasing devices may be essential for maintaining sufficient traction to allow a vehicle to move in the snow. Traction-increasing devices may aid in decelerating a vehicle in order to avoid collisions or running off the road. 
         [0004]    An early form of a traction device was tire chains. This device was and still is inconvenient to install. Tire chains damage road surfaces. A next generation of traction devices comprised studded tires. Studs comprising small cylindrical bodies projected radially from a tire tread. Carbide or other strong materials have been used to make the studs. Carbide is harder than concrete or asphalt road surfaces. Due to destructive effects of traction-increasing devices on road surfaces, many jurisdictions have banned the use of devices such as studs. 
         [0005]    In response, the industry has provided devices which may be removably attached to a tire. A device may comprise a traction member held against a tire&#39;s outer diameter. A significant problem is providing a convenient and reliable means for supporting the traction member in engagement with the tire. Prior devices have each presented different drawbacks. 
         [0006]    U.S. Pat. No. 7,426,949 discloses a traction device for maintaining a bar against a tire. A first end of a radially extending support member is bolted to a wheel. A second end of the support member projects radially from the first support member past the tire tread. A traction bar is cantilevered from the second end of the support member in an axial direction and rests against the tire. This structure requires a specially made wheel to cooperate with the support member. It is not suitable for use with conventional wheels. The cantilevered mounting can have limited reliability. 
         [0007]    U.S. Patent Application Publication Number 2009/00396 discloses a releasably attached traction device. The traction device has a first end hooked into an eye of a first fixing device. A second end has a second fixing device. The traction device extends around the tire to a point radially inward and goes around the wheel. The second fixing device interlocks with the first fixing device. The first and second fixing devices comprise a complex mechanism which can become ice bound. This can prevent removal of the device. If ice forms in the fixing members prior to attachment, it may be impossible to install the device when needed. 
         [0008]    U.S. Pat. No. 3,937,262 discloses a traction device in which an arcuate segment of a larger tire is placed over a smaller tire. The segment is secured to the tire by radially extending studs. The device may be for attachment to one or both of the rear wheels of a vehicle. This device does not comprise a fully interactive traction system. Reliability is not assured. 
         [0009]    U.S. Pat. No. 4,747,438 discloses a traction device in which radially extending arms are secured to a wheel. Each arm receives a traction device. The traction device is J-shaped. The long arm of the J is received in a radially extending arm. The remainder of the J shape extends across the tire tread and hooks onto an inner side of the tire. This is a complex construction designed to poke into sand and earth as well as snow. The rigid components do not allow for close interfacing of the traction device and a tire. Radially extending cleats are not suited for continued traversing of highways. A rough ride is provided and highway damage is produced. 
       SUMMARY 
       [0010]    Briefly stated, in accordance with the present subject matter, an apparatus and method are provided in which a traction device comprises a tread member and a retaining member. The retaining member is assembled to the tread member. The tread member is maintained in a manner to resist forces on a fastening area over a radially extending portion of a tire. The tread member and the retaining member form an interactive system. The retaining member holds the tread member in substantially complete surface contact with the tire tread in order to maintain a maximum coefficient of friction between a lower surface of the tread member and an outer surface of the tire tread. The material of the tread member is selected to satisfy many needs. It must be elastomeric so as to conform to the tire but must also be composed to withstand the forces applied to between the road and the tire. The tread member and the retaining member comprise an assembly. When one member wears out, it is not necessary to discard the other. The retaining member is also constructed to meet a number of needs. The retaining member must be sufficiently flexible to be able to go around an irregular perimeter comprising an outer tire sidewall, tire tread, inner tire sidewall, and portions of the wheel radially inwardly of the tire. In accordance with the present subject matter, flexible reusable fastening means are provided. A hook and loop fastener is utilized in a manner to provide convenience in assembly and disassembly while being formed to comprise a lock assembly resistant to forces that would tend to disassemble the lock. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a traction device system comprising a plurality of traction devices mounted to a tire; 
           [0012]      FIG. 2  is an elevation of the tire and system of  FIG. 1 ; 
           [0013]      FIG. 3  is a plan view of a tread member; 
           [0014]      FIG. 4  is a side elevation of the tread member; 
           [0015]      FIG. 5  is a front elevation of the tread member; 
           [0016]      FIG. 6  is a bottom plan view of the tread member; 
           [0017]      FIG. 7  is a perspective view of alignment of a retaining member and a tread member prior to assembly; 
           [0018]      FIG. 8  is an illustration of the retaining member; 
           [0019]      FIG. 9  is a partial detailed front elevation showing a retaining member assembled to a tread member; 
           [0020]      FIG. 10  is a perspective view of a traction device showing opposite ends of the retaining member aligned for engagement; 
           [0021]      FIG. 11  is a perspective view of a traction device showing opposite ends of the retaining member fastened to one another; 
           [0022]      FIG. 12  is a cross-section taken across lines  12 - 12  of  FIG. 2   
           [0023]      FIG. 13  is a partial detailed view of  FIG. 12 ; and 
           [0024]      FIG. 14  is a diagram illustrating responses of the retaining member to outside forces. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  is a perspective view of a traction device system comprising a plurality of traction devices mounted to a tire.  FIG. 2  is an elevation of the tire and system of  FIG. 1 .  FIGS. 1 and 2  taken together illustrate the spatial relationship which yields the interactivity of the tire  10 , wheel  12 , and the traction device system  100 . In each of the figures, the same reference numerals are used to denote the same elements. A tire  10  is mounted on a wheel  12  mounted for rotation by an axle  14 . Lug nuts  16  retain the wheel  12  to the axle  14 . In the present illustration, the wheel  12  surrounds a disc brake assembly  18 . The wheel  12  comprises a rim  20 . The rim  20  retains edges of the tire  10  at an annular inner rim portion  24  ( FIG. 12 ). The wheel  12  has axially extended open areas  22  through which securing means may pass. The tire  10  has a tread  30  axially extending around an outer diameter of the tire  10 . An outer sidewall  36  and an inner sidewall  39  ( FIG. 2 ) of the tire can extend from the outer diameter to a bead  38  ( FIG. 12 ) which is received in the rim  20  at an inner diameter of the tire  10 . 
         [0026]    A traction device system  100  comprises a plurality of traction devices  120 . Each traction device  120  comprises a tread member  130  extending axially across the entire tread  30  at a selected angular position. A retaining member  220 , further described beginning at  FIG. 7  retains the tread member  130  to the tire  10 . A number of traction devices  120  are provided spaced around the tire tread  30 . The number of traction devices  120  utilized represents an optimization of complexity of the traction device system  100  and level of effort required to mount the traction device system  100  versus the amount of traction that is provided. In the present illustration, five traction devices  120  are provided, each angularly spaced from a next traction device  120  by 72°. It is desirable to have at least one traction device  120  in contact with the road at all times. Five traction devices  120  will generally be sufficient for mounting on 14 inch to 18 inch wheels. Tires for large trucks will normally require a greater number of traction devices  120 . 
         [0027]      FIG. 2  illustrates the interaction of the traction devices  120  with the surface of the tire tread  30 . In accordance with one aspect of the present subject matter, gaps between the surface of the traction device  120  and the tread  30  are minimized. This is illustrated particularly at an interface  126 . 
         [0028]      FIGS. 3, 4, 5, and 6  taken together illustrate a tread member  130 .  FIG. 3  is a plan view of a tread member  130 ,  FIG. 4  is a side elevation of the tread member  130 ,  FIG. 5  is a front elevation of the tread member  130 , and  FIG. 6  is a bottom plan view of the tread member  130 . 
         [0029]    The material selected is one that remains pliable in subfreezing operating temperatures. One preferred material for the tread member  130  is ethylene-vinyl acetate (EVA), also known as poly(ethylene-vinyl acetate) (PEVA). EVA is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10% to 40%, with the remainder being ethylene. EVA has properties approximating softness and flexibility of elastomers. Other advantages of EVA are the ability to use general thermoplastic processing techniques, stress-crack resistance, resistance to brittleness at low temperatures, and resistance to UV radiation. A high durometer elastomer is an alternative. 
         [0030]    The tread member  130  is shaped to interlock with the tread  30  of the tire  10  ( FIG. 1 ) and have a surface in contact with the tread  30 . The tread member  130  comprises a central support member  160 . The central support member  160  has an upper surface  166  and a lower surface  168  ( FIG. 6 ). In one preferred form, the central support member  160  has a rectangular cross-section in a radial degree of freedom. The central support member  160  is disposed straight across the tire tread  30 . The central support member  160  has a curved cross-section in an axial degree of freedom, i.e., the central support member  160  may be curved to approximate the curvature of the outer diameter of the tire  10 . 
         [0031]    An axial row  176  of teeth  180  ( FIG. 4 ) extends radially outwardly from the central support member  160 . The teeth  180  are each shaped to grip a snowy road surface and to define channels  182  from which snow and mud may be expelled as the tire  10  rotates. The teeth  180  have axially aligned apertures  184 , preferably disposed radially in the vicinity of the central support member  160 . The aligned apertures  184  collectively form a channel  186 . A retaining member  220  ( FIG. 7 ), further described below, is threaded through the apertures  184  to provide for holding the tread member  130  against the tire tread  30  ( FIG. 2 ) when the traction device  120  is fastened to the tire tread  30 . 
         [0032]    A plurality of cleats  190  ( FIG. 6 ) are formed projecting radially inwardly from the lower surface  168  of the central support member  160 . The cleats  190  are positioned to engage recesses in the tire tread  30 . The cleats  190  may be arranged to mesh with the tread pattern of a specific tire  10 . Alternatively, the cleats may be arranged in an order that will provide a less precise fit across a wider range of tread patterns. 
         [0033]      FIG. 7  is a perspective view of alignment of a retaining member  220  and a tread member  130  prior to assembly. A user will generally thread the retaining member  220  through the channel  186  prior to placing the tread member  130  on the tire tread  30 . The width of the retaining member  220  is preferably dimensioned to have a small clearance with the channel  186 . A preferable clearance is ±0.01 inches for the height (radial) dimension and ±0.06 inches for the width. It is desirable to minimize possible movement of the retaining member  220  with respect to the tread member  130 . 
         [0034]      FIG. 8  is an illustration of the retaining member  220 . Opposite end sections  222  and  224  of the retaining member  220 , or tip and tail sections, comprise a fastening means  228  ( FIG. 10 ). The fastening means  228  comprises a hook and loop fastener. Hook and loop fasteners are often referred to by the trademark Velcro®. The retaining member  220  may be provided to a user in a length exceeding many foreseeable applications. The user may then install the traction device  120  and cut off excess length of the retaining member  220 . End sections  222  and  224  may be defined by their overlapping areas when installed. 
         [0035]    Various forms of hook and loop fasteners are available in different levels of size and sturdiness. Weaker fasteners may be used to retain traction devices  120  on a tire, with maximum speed allowable being determined by trial and error. However, it is preferable to provide reliable fastening for highway speeds. One form of fastener suitable for normal driving applications is “military grade” hook and loop fastener material. For purposes of the present specification, “military grade” means a suitable material defined by GSA standard A-A-55126B promulgated by the United States General Services Administration, Sep. 7, 2006. A reliable form of fastener comprises a hook portion made up of 75% aramid and 25% nylon with a loop portion made up of 100% aramid. Less expensive materials may be used providing that a manufacturer has tested them. It is desirable to use materials with higher density for mechanical adhesion. It is also desirable to provide a high level tear point. 
         [0036]    In a preferred form, the entire retaining member  220  comprises a hook and loop fastener having a hook surface  226  and a loop surface  227 . It is preferable to have the loop surface  227  facing outwardly from the tire and engaging a road surface. 
         [0037]      FIG. 9  is a side elevation in cross-section showing a retaining member  220  assembled to a tread member  130 . The retaining member  220  projects through the channel  186 . The retaining member  220  retains the tread member  130  against the tread  30 . This is illustrated in a complete system below in  FIG. 12 . The engagement of the cleats  190  with the tread  30  occurs at the interface  126 . The cleats  190  may fit into open areas  240  of the tread  10  or may press into flat surfaces of the tread  10  at points  244  in registration with other cleats  190 . 
         [0038]      FIG. 10  is a view of a traction device  120  showing opposite ends of the retaining member aligned for engagement. A first end section  222  is disposed with a loop field  230  facing radially outwardly from the tire  10 . The second end section  224  contains a hook field  232 . Opposite end sections  222  and  224  of the retaining member  220  comprise the fastening means  228 . 
         [0039]      FIG. 11  is a perspective view of a traction device showing opposite first end section  222  and second end section  224  of the retaining member  220  fastened to one another. The fastened ends comprise a lock assembly  238 . The lock assembly  238  comprises the completely mating portions of the hook and loop fastening means  228 . The loop field  230  and the hook field  232  are covered. They are largely protected from snow and mud. They also provide a solid assembly so that the traction device  120  will remain fastened to the tire  10  even if a driver might brush a curb. The upward facing end of the retaining member  220  should be on the outside of the lock assembly  238 . 
         [0040]      FIG. 12  is a cross-section taken across lines  12 - 12  of  FIG. 2 , and  FIG. 13  is a partial detailed view of  FIG. 12 . In order to mount the traction devices  120  across the tire  10 , the retaining member  220  is threaded through the tread member  130 . A first end section  222  of the retaining member  220  is held against outer sidewall  36  of the tire  10 . The retaining member is threaded through the tread member  130  and extends around the tire  10  across an inner sidewall  39  and through one open area  22  and brought back around to be in alignment with the first end section  222 . The ends are pressed together to form the lock assembly  238 . 
         [0041]    The occurrence of gaps between the retaining member  220  and surfaces of the wheel  12  are more easily seen in  FIG. 13 . The retaining member  220  may bear against a rim  20  at an inner side of the wheel  12  and extend across a portion of the wheel adjacent the outer side of the wheel  12 . Since the outer side of the wheel  12  may have a different inner diameter from the inner diameter on the inner side of the wheel  12 , a gap  260  will be present. The retaining member  220  will be subject to flexion and extension in the portion extending across the gap  260 . 
         [0042]      FIG. 14  is a diagram illustrating responses of the retaining member to outside forces at the lock assembly  238 . Force x represents forces applied from engagement of the traction device  120  with the road. Force y represents the reaction force exerted by the hook and loop lock assembly  238 . Both forces x and y react in a radial direction. This is a direction in which strength of the hook and loop fastening is maximized. Unfastening of a hook and loop joint generally requires forces that provide a resultant at an angle to the radial direction. 
         [0043]    As a car sits in a stationary position, the retaining member  220  retains the tread member  130 . The first end section  222  ( FIG. 11 ) is overlapped by the second end section  224  on the outside. The lock assembly  238  gains centrifugal force from radial acceleration. The lock assembly  238  bears against the outer sidewall  36  of the tire  10  in a radial direction, maximizing the overlapping bond of the hook and loop system. 
         [0044]    As the car accelerates the outside or tip of the fastener will gain centrifugal force, that will increase its bond with the tail of the fastener, because of the orientation of these tip and tail ends of the retaining member  220 . The tail end  224  must be oriented on the outside of the tail in order to take advantage of centrifugal forces that will improve its mechanical bond. 
         [0045]    Centrifugal force is an outward force apparent in a rotating reference frame; it does not exist when measurements are made in an inertial frame of reference. This type of force, associated with describing motion in a non-inertial reference frame is referred to as a fictitious or inertial force; a description that must be understood as a technical usage of these words that means only that the force is not present in a stationary or inertial frame. 
         [0046]    In a rotating reference frame, all objects appear to be under the influence of a radially outward force that is proportional to their mass, the distance from the axis of rotation of the frame, and to the square of the angular velocity of the frame. The center of rotating reference is the center of the vehicle tire. 
         [0047]    Motion relative to a rotating frame results in another fictitious force, the Coriolis force; and if the rate of rotation of the frame is changing, a third fictitious force, the Euler force is experienced. Together, these three fictitious forces are necessary for the formulation of correct equations of motion in a rotating reference frame. 
         [0048]    The present subject matter provides for many advantages. The hook and loop fastening system along with the novel retaining member provide for strong and reliable fastening. The present retaining members are superior to zip ties in that they provide for selectable characteristics such as resiliency, resistance to brittleness, less breakage, and being proportional to the retaining channel in the tread member in order to provide options in modes of assembly and in engagement of the tread member to a tire. Modularity of the tread member and the retaining member provides for selection of cooperative characteristics. For example, a tread member designed for maximum hardness may require a retaining member with additional resiliency. Retaining members may also be designed as custom matches for selected wheels. 
         [0049]    While the foregoing written description of the present subject matter enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The present subject matter should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the present subject matter.