Abstract:
Footwear having retractable studs that provide enhanced traction on slippery surfaces when engaged. A pull cord attached to a plate within the sole of the shoe allows the studs to engage. The working parts of the shoe can be easily taken apart for cleaning or de-icing. An alternative embodiment of the shoe has a mechanism similar to that of a conventional ball point pen which is used to effectively engage or retract the studs.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates in general to footwear for use on slippery surfaces such as ice and snow, and more particularly to footwear having retractable studs that provide enhanced traction on slippery surfaces when engaged.  
         [0003]     2. Description of the Prior Art  
         [0004]     In climates that experience ice and snow, especially during the winter season, many accidents occur when an unsuspecting person falls on an icy sidewalk or street resulting in injury due to an unrecognized danger. For example, in many cities a sidewalk may be bare and wet in places, but still have icy patches in the same block which are hazardous to pedestrians. Falls on icy sidewalks or streets can result in serious injury and even death. These injuries tend to occur with more frequency to middle-aged and older people. To address this situation, there are many well-known prior art devices, ranging from overshoes with enhanced traction to special inclement weather boots. Generally speaking, the well known winter footwear tends to have some value, if used. Many situations in the urban environment, however, occur in winter which require a “normal” shoe for indoor wear and a shoe with enhanced traction for navigating the outdoor walkways. Overshoes and conventional winter boots, even if used, are somewhat limited in value, especially on icy surfaces. The solution to the above mentioned problem, perhaps, is best met by footwear which can have an “upper” of any conventional design but yet have a sole which could adapt itself by extending studs to slippery outside conditions.  
         [0005]     A preliminary search of the prior art has turned up three U.S. patents which address “retractable spikes” and their use, each in different ways, and are a typical sampling of the retractable spike art. These patents are: U.S. Pat. No. 4,825,562 issued to Chuang, U.S. Pat. No. 4,821,434 issued to Chein, and U.S. Pat. No. 6,058,627 issued to Violette et al. Both the Chuang and Chein patents are quite different in structure, function, and result with respect to the present invention. Chuang has a sole which can allow two sets of nails to project therefrom when a key is used. To accomplish this extension of nails, a box is provided between the insole and sole. The particular structure appears to be somewhat complex and further could reduce the durability of the sole and insole due to accumulate water and dirt in spaces between the box, sole, and insole. The Chein patent also has this drawback, as it would appear that the structure of the sole would make walking on it rather stiff and unusual when compared to a normal shoe. Also to deploy the spikes, kicking the toe of the shoe on an object such as a wall seems to be somewhat less than ideal, as this structure requires a “driving member 5” located in the toe of the shoe, extending the toe somewhat compared to a normal shoe, increasing the chance of tripping. The Violette et al patent has a retractable spike structure in its sole. Violette et al also has kick points on the toe and heel of his shoe for retraction and extension of traction spikes. A plate device  32  runs nearly the entire length and width of the shoe within the sole which is split into an upper portion  16  and lower portion  18 . Several problems arise from this structure. The upper and lower portion of the sole must be sealed together with the plate device therein. It would appear that the durability of this shoe would be limited by the strength of the lamination on the periphery of the shoe. There is also significant “dead space” between the two layers which would tend to accumulate dirt and water, which could comprise the functioning of the plate device. Violette et al would also seem to present a significant tripping hazard. In contrast to the above patents, the present invention provides a simple, yet efficient, way to retract or extend traction studs and a mechanism which is easily serviceable and/or replaceable.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention comprises footwear for use on slippery surfaces such as ice, snow, or the like which has retractable studs allowing enhanced traction on these surfaces. The footwear can be of any design with respect to its upper portion. The footwear would have a sole that was specially configured. The sole is adapted to receive a plurality of treads with the treads preferably threaded to the sole. The treads have a retractable stud mounted and retained therein. The studs have a top portion which is somewhat rounded and a bottom portion which extends from the sole of the footwear when the retractable studs are extended. The sole also has a cavity within it which holds a plate. The plate has two tracks which have holes therein. The holes in the plate receive the top portion of the retractable studs when the studs are in a retracted position and are slightly smaller in diameter than the greatest diameter of the studs. This configuration means that the top portion of the studs do not fully fit within the holes. The retainer for each stud within the tread is a spring which prevents the bottom portion of the stud from extending from the sole when the top portion of the studs fit within the holes of the plate. The plate can slide within the cavity such that movement of the plate in a rearward direction relative to the sole allows the plate to contact the top portion of the retractable stud. As the plate pushes over the top portion of the stud, the bottom portion of the stud is extended beyond the sole against the force of the retainer or spring to an engaged portion. Preferably the plate has small recesses which are located above the top portion of each stud when the studs are extended. The studs can be disengaged or retracted by a forward motion of the plate relative to the sole which will once again center the holes over the top portion of the studs allowing the studs to retract and be retained in the tread. The rearward movement of the plate can be facilitated by a pull cord attached to the rear of the plate. The pull cord can be pulled in a rearward direction relative to the footwear resulting in the plate sliding rearwardly and the studs engaging. The forward movement of the plate can be accomplished by the wearer of the footwear by tapping the rear portion of the plate against an object such as the toe of the opposite shoe.  
         [0007]     To limit the movement of the plate within the cavity in the sole, a retaining tread is provided. This retaining tread is connected to the sole of the footwear, preferably by a threaded connection. The retaining tread can be similar to the other treads which are used, but without a stud dispersed therein. The retaining tread fits through a slot within the plate, providing a limit to the forward and rearward movement of the plate.  
         [0008]     The pull cord, which is connected to the rear of the plate, can be stored in the following manner. The cord can be attached to the back of the footwear using a hook and loop connection. To accomplish this connection, a strip is provided on the back of the footwear. Both the strip and cord can be hook and loop material. This connection is relatively simple and prevents the cord from becoming a nuisance when using the footwear. As an alternative to the pull cord to initiate rearward movement of the plate and engagement of the studs, a cylindrical mechanism like that used in a conventional ballpoint pen can be employed. To briefly describe this mechanism, a cylindrical portion is added to the plate of the present invention. The cylinder has a piston within it and the piston engages a wheel. The wheel has a series of projection on its circumference and is retained in the cylinder of the plate such that a forward movement of the piston allows the piston to disengage temporarily from projection of the wheel. The wheel can then rotate and, by rotating, lock the piston in a fixed position. The plate, therefore, moves rearwardly relative the sole thereby allowing the plate to contact the top portion of the retractable studs engaging the studs in a deployed position. The movement of the piston can be initiated by a tap on a central projection connected to the piston. The “tap” can be a strike against an object, i.e. the toe of the opposite shoe. To disengage the studs, another tap on the central projection would allow the piston to disengage from wheel projection and allow the wheel to rotate and lock the piston in a forward position, just as the point of a ballpoint pen is engaged or retracted.  
         [0009]     It is, therefore, an object of this invention to provide footwear with retractable studs for enhanced traction on slippery surfaces.  
         [0010]     Another object of the present invention is to provide a footwear with retractable studs that is easy to operate.  
         [0011]     A further object of the present invention is to provide footwear with enhanced traction on icy surfaces which will not damage conventional flooring or carpeting.  
         [0012]     Yet another object of the present invention is to provide footwear with deployable studs for use on icy surfaces which has easily removable and replaceable parts.  
         [0013]     Still another object of the present invention is to provide footwear with retractable studs which has an operating mechanism that minimizes “jamming.” 
         [0014]     These and other objects and advantages will become more apparent from the following detailed description when taken in conjunction with the attached drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is an exploded pictorial view of a shoe in accordance with the present invention.  
         [0016]      FIG. 2  is a side view of a shoe partially in cross section (along line  2 - 2  of  FIG. 6 ) showing the studs of the present invention in a retracted position.  
         [0017]      FIG. 3  is a side view of a shoe partially in cross section (along line  3 - 3  of  FIG. 7 ) showing the slide plate and the studs in an extended position.  
         [0018]      FIG. 4  is a detail view partially in cross section showing the stud of the present invention in a retracted position.  
         [0019]      FIG. 5  is a detail view partially in cross section showing the studs of the present invention in an extended position.  
         [0020]      FIG. 6  is a bottom view in cross section of the shoe in  FIG. 2  showing the slide plate and the studs in a retracted position.  
         [0021]      FIG. 7  is a bottom view in cross section of the shoe in  FIG. 3  showing the studs of the present invention in an extended position.  
         [0022]      FIG. 8  is a bottom view in cross section of a shoe (studs retracted) similar to  FIG. 1  showing an alternative mechanism to initiate extension of the studs.  
         [0023]      FIG. 9  is a bottom view in cross section of a shoe (studs extended) similar to  FIG. 6  showing an alternative mechanism to initiate extension of the studs.  
         [0024]      FIG. 10  is an exploded view of the alternative mechanism to initiate extension of the studs.  
         [0025]      FIG. 11  is an exploded elevation view showing part of the alternative mechanism for extending the studs.  
         [0026]      FIG. 12  is a cross sectional view taken through line  12 - 12  of  FIG. 11 .  
         [0027]      FIG. 13  is a cross sectional view taken through line  13 - 13  of  FIG. 11 .  
         [0028]      FIGS. 14, 15 , and  16  are elevation views of part of the alternative mechanism to extend the studs showing three successive stages in its operation.  
         [0029]      FIG. 17  is a detail view showing the cylindrical wheel almost fully disposed in the outer cylinder (studs retracted).  
         [0030]      FIG. 18  is a detail view showing the cylindrical wheel extending from the outer cylinder (studs extended).  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]     Referring to the figures, and especially  FIGS. 1 through 4  initially, the present invention can be described.  FIG. 1  shows an article of footwear  10  and for ease of description will be referred to as shoe  10 . It is understood that the upper portion of the footwear can be in any well known configuration such as a conventional shoe, boot, athletic shoe, or any equivalent. The shoe  10  has an upper portion  12  with a lower portion or sole  14 . Sole  14  runs the length of the shoe  10  on its bottom and has a narrow cavity  16  therein. Cavity  16  has a slide plate  18  fitted therein and the slide plate  18  is substantially U-shaped as best shown in  FIGS. 2 and 4 . Sole  14  also has a plurality of treads  20  fitted therein, preferably threadably connected to the sole as shown in  FIGS. 1 and 3 . Treads  20  fit with sole  14  such that they are neither extended nor retracted relative to the sole  14  when the shoe  10  is in use, but actually form part of the walking surface of the shoe  10 . Contained within the treads  20  are studs  22 . Studs  22  have an upper portion  24  and a lower portion  26 , as best seen in  FIG. 5 . The upper portion  24  of studs  22  have a rounded shape and fit within holes  28  in slide plate  16  when the studs  22  are in a retracted position. Plate  18  is provided with a plurality of recessed portions  30  which partially receive the upper portions  24  of studs  22  when the studs  22  are engaged. The studs  22  are retained in the treads  20  by a spring retainer  32  in each tread  20 .  
         [0032]     To limit the movement of slide plate  18  within the cavity  16 , at least one retaining tread  34  is provided. Retaining treads  34  are similar to treads  20 , but are studless and threadably connect to sole  14 . Retaining treads  34  fit within a slot  36  within the slide plate, which is substantially elliptical and allows limited movement of the slide plate  18  relative to the sole  14  as best seen in  FIGS. 2 and 4 . A pull cord  38  is provided, which attaches to the rear of the slide plate  18 . The pull cord  38 , when not being used to move the slide plate  18 , is attached to a strip  40  of material on the back of the upper portion  12  of the shoe  10 . This attachment can be readily accomplished by having the strip  40  and pull cord being made of a conventional hook and loop material.  
         [0033]     The operation of the shoe  10  to engage or retract the studs  22  can be described as follows. Initially, it is assumed that the shoe  10  is being worn with the studs in a retracted state. The “retracted” state is shown in  FIGS. 1 and 2 . In this state, the studs  22  have their lower portions  26  retained in the treads  20  by the springs  32 . The top portion  24  of the studs  22  are at least partially fitted within the holes  28  of the slide plate  18 . In the preferred embodiment, the top portions  24  of the studs  22  are not fully contained within the holes  28  of the plate  18 . This feature is best accomplished by having the holes  28  slightly smaller than the greatest width of the top portion  24  of stud  22  and having that top portion rounded. In this manner, the “jamming” of the mechanism can be minimized and allows for use of a thinner slide plate  18  can be used. With the slide plate  18  relatively thinner, the sole  14  of the shoe  10  will be more flexible and have less weight, resulting in it feeling similar to the sole of a conventional shoe to the wearer. In the retracted state, the retaining tread  34  is in a rearmost position with respect to slot  36  as shown in  FIG. 2 . Also, the slide plate  18  is substantially contained within the cavity  16 .  
         [0034]     To engage the studs  22  when desired, the wearer of the shoe  10  would grab the pull cord  38  and detach it from the strip  40 . A rearward tug on the pull cord  38  would move slide plate  18  within cavity  16  to a position shown in  FIGS. 3 and 4 . Retaining tread  34  would in a foremost position relative to slot  36  (see  FIG. 4 ), and the slide plate  18  would have worked against the top portion  24  of the studs  22  so that the bottom portion  26  of the studs  22  are extended from the sole  14 . The recessed portions  30  in the slide plate  18  are now above the top portion  24  of the studs  22 . The slide plate  18  is slightly extended from the rear of the cavity  16  (see  FIG. 3 ) and the pull cord  38  can once again be fastened against strip  40 .  
         [0035]     Referring now to the Figures (especially  FIGS. 7 through 17 ), an alternative embodiment of the invention can be described which uses a different mechanism to engage and disengage the studs.  FIG. 7  shows a cylindrical track  42  included as part of plate  18 . Cylindrical track  42  has an external sheath  44 , which contains within the working mechanism of the embodiment. Disposed in external sheath  44  is an outer cylinder  46  having channels  47   a  and  47   b  ( FIG. 12 ) on its interior surface as best seen in  FIG. 9  formed by linear beveled portions  49 . Outer cylinder  46  holds a notched cylinder  48  and receives partially a cylindrical wheel  50  at its forward end and a plunger  52  at its posterior end. Notched cylinder  48  has four tabs, collectively designated as  54 , towards its forward end and tooth-like protrusions, collectively designated as  56 , on its front edge. Cylindrical wheel has linear projection  58  along its length. These linear projections  58  contact the protrusions  56  of notched cylinder  48  when the mechanism is in place. A spring  60  fits in external sheath  44  and contacts the front surface of the cylindrical wheel, exerting a rearward force on the cylindrical wheel  50 , notched cylinder  48 , outer cylinder  46 , and plunger  52 .  
         [0036]     The operation of this alternative mechanism can now be described especially with reference to  FIGS. 10 through 17 . Initially, it should be made clear that tabs  54  of notched cylinder  48  are disposed within channels  47   a  of outer cylinder  46 . Also, channels  47   b  are adapted to receive linear projections  58  of cylindrical wheel  50  when the studs are retracted, as will be described shortly. For purposes of this description, it will be assumed that the studs are in an engaged state as shown in  FIG. 8 . It should be noted that cylindrical wheel  50  protrudes from the front of outer cylinder  46 . This configuration corresponds to the configuration shown in  FIG. 13  where the linear projections  58  of cylindrical wheel  50  are contacting the protrusions  56  of notched cylinder  48 . Beveled portion  49  of outer cylinder  46  engages the linear projections  58  and prevent the cylindrical wheel  50  from rotation, holding it in a forward position as shown in  FIG. 13 . When the plunger  52  is depressed (as shown in  FIG. 14 ), a force is exerted forwardly on notched cylinder  48 . This forward force moves the notched cylinder  48  within outer cylinder  46  to a more forward position, and thereby moves the linear projections  58  of cylindrical wheel  50  clear of the beveled portion  49  temporarily, as depicted in  FIG. 14 . At this point, the bevel at the ends of the linear projections  58  co-operates with the bevel at the end of the beveled portion  49  and produces a rotation in the cylindrical wheel. After rotation, the linear projections  58  are disposed in the channels  47   b  which compresses spring  60  and forces plate  18  forward, thereby retracting the studs.  FIGS. 16 and 17  show the relationship of the cylindrical wheel  50  and outer cylinder  46  upon retraction of the studs ( FIG. 16 ) and engagement of the studs ( FIG. 17 ).  
         [0037]     To extend the studs, the plunger  52  is depressed again. This forces notched cylinder  48  forward against the spring tension to a position shown in  FIG. 13  where the ends of linear projections are engaged and held in the position shown by beveled portion  49  of outer cylinder  46 .