Abstract:
Footwear, such as a boot, having a vacuum release tube attached at the back of the boot along the lower part of the boot extending from the sole of the boot to approximately 10-30 inches above the sole of the boot. The vacuum release tube may be rigid, semi-rigid, or flexible, and the length of the vacuum release tube may be chosen based upon the intended use of the boot. The vacuum release mechanism can be electro-mechanically or pneumatically enhanced.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims priority from provisional application No. 60/546,955, filed Feb. 24, 2004, the entire contents of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention is directed to footwear that enables the wearer to walk smoothly through mud or other thixotropic media such as mud flats of tide land, marshes, and soft arctic tundra without being stuck therein.  
       BACKGROUND OF THE INVENTION  
       [0003]     When wearing waders, boot, or hip-boots, a person often desires to traverse areas in which the bottom or soil is composed mostly of mud or other thixotropic medium. The mud can make walking very difficult, because with each step the boot sinks into the mud and then, because of the cohesive and/or adhesive properties of mud, it is very difficult to remove the boot from the mod.  
         [0004]     Previous means to solve this problem used increased surface area (the snowshoe principle) to distribute the wearer&#39;s weight so that the wearer does not sink into the mud. In some areas, however, the boot may still penetrate the mud, particularly if the wearer stands still in one place for any length of time, such as when hunting or fishing. Then, extraction becomes more difficult because the increased surface area requires even more effort to extract the boot from the mud. In addition, the larger area makes walking more awkward, as do snowshoes.  
         [0005]     Another method for overcoming the problems of walking in mud or the like is to provide a mud resistant elastomer, such as that disclosed in Sidles, U.S. Pat. No. 3,961,428. In this method shoes or boots are equipped with a resilient planar body with a plurality of spaced thin fins extending transversely across the body. All of the fins are inclined relative to a horizontal plane such that any weight applied to the sole compresses the fins to trap air between adjacent fins to minimize mud build-up.  
         [0006]     Ruth, Jr., in U.S. Pat. No. 4,525,941, discloses a mud walker comprising a platform supported around the periphery of this under surface by a pneumatic tube cushion secured to the platform by strap loops. Vent holes in mid portions of the platform prevent suction effects under the platform when the foot is lifted.  
         [0007]     Japanese Patent No. 52-20152 discloses a boot to be worn in rice paddies. This boot has a tube running up the side of the boot.  
         [0008]     There is a need for constructing footwear, such as a wader, boot, or hip-boot, that will reduce the cohesion of the mud around the footwear without significantly increasing the size of the footwear. This type of footwear is needed by fishermen, duck hunters, clam harvesters, oyster gatherers, fishermen in Alaska, and for gathering shrimp and mud clams.  
       SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to overcome the aforesaid disadvantages of the prior art.  
         [0010]     It is another object of the present invention to provide footwear which permits the wearer to reduce the cohesion and/or adhesion of mud around the footwear of one who traverses the mud.  
         [0011]     For purposes of the present invention, the term “boot”, can refer to any type of footwear that can be equipped with vacuum release tubes.  
         [0012]     The present invention is a standard article of footwear, such as a boot, with a vacuum release tube attached at the back of the boot along the lower part of the boot extending from the sole of the boot to approximately 18 inches above the sole of the boot. The vacuum release tube may be rigid, semi-rigid, or flexible, and the length of the vacuum release tube may be chosen based upon the intended use of the boot. Boots intended for use by hunters, hikers, and people who intend to traverse a body of water without standing in one place could use shorter tubes since the boot would not sink as deeply into the bottom as for a wearer standing for a long time in one place. Fishermen and some duck hunters would want boots or waders with longer tubes since they often stand in one spot allowing the feet to sink much deeper into the bottom. It is important that the top of the tubes remain above the bottom.  
         [0013]     When the wearer wades through water, as the boot enters the mud, some mud will enter the tube at the base of the boot. Because of the relatively small size of the vacuum release tube with respect to the boot and the cohesive and/or adhesive nature of mud, the quantity of mud entering the vacuum release tube is small. As the mud enters the vacuum release tube, it will mix with water in the tube, forming a slurry. When the wearer begins to extract the boot from the mud, a suction will form on the bottom of the boot and the vacuum release tube. Water will be drawn down the vacuum release tube by suction and will begin to fill the void under the boot, releasing the sole from the mud by destroying the cohesive and/or adhesive effect between the mud and the sole. At the same time, the water flushes any mud in the vacuum release tube, and the vacuum release tube is unobstructed until the boot again re-enters the mud at the completion of the step. This same mechanisms makes it possible for a wearer to traverse any non-solid medium without becoming stuck therein.  
         [0014]     The footwear of the present invention performs best when the top of the vacuum release tube is below water, but the footwear is still useful when there is little or no water present. When there is no water present, air is sufficient to fill the void in the vacuum release tube to reduce the cohesive and/or adhesive effect between the mud and the sole.  
         [0015]     While the present invention requires at least one tube at the back of the footwear, additional tubes may be located around the periphery of the footwear. The tube at the back of the footwear is critical to enable the footwear to be extracted from mud or other cohesive and/or adhesive medium. However, additional tubes may be provided which enhance the action of the tube at the back of the footwear. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a side view of a boot having one vacuum release tube at the back of the boot.  
         [0017]      FIG. 2  is a side view of a boot with a plurality of vacuum release tubes located around the periphery of the boot.  
         [0018]      FIG. 3  is a bottom view of the boot of  FIG. 2 .  
         [0019]      FIG. 4  is a bottom view of a boot wherein channels run from the bottom ends of the vacuum release tubes to approximately the center of the sole. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     The present invention provides footwear that can be used for walking through mud or swampy conditions. The footwear is provided with at least one vacuum release tube at the back of the footwear, the tube extending from the sole of the footwear to above the top of the footwear. Additional tubes may be provided to enhance the performance of the tube at the back of the footwear.  
         [0021]     Both the use of vacuum-release tubes and the location of the tubes are important to the present invention. A single tube is sufficient in some instances, particularly in situations in which the wearer is squatting with the heels raised. Footwear with more than one tube can be provided, in which less force is required to break the vacuum than if the footwear is equipped with only one tube.  
         [0022]     When additional tubes are provided on the footwear, tubes located around the heel are the most important to accommodate walking on mud or loose sand, since the heel of the footwear is the first part of the footwear to be lifted from the ground. If no water or air can flow into the area around the heel, then additional effort is required to lift the footwear to the point where a vacuum release tube located forward of the heel can come into play. Since the heel of the foot can easily slide upward in the footwear if there is too much resistance to movement of the footwear, it is important that release of the heel of the footwear be immediate to prevent extraction of the foot from the footwear. As the back of the footwear rises, any additional vacuum release tubes will come into play, facilitating a smooth release of the footwear from the bottom until finally the vacuum release tube at the toe of the footwear comes into play, allowing the final release of the boot from the ground. As the viscosity of the mud or sand decreases, or if the wearer pauses, then a multi-tube design becomes much more important because the footwear sinks more deeply into the mud, making extraction more difficult.  
         [0023]     In another embodiment of this invention, a plurality of vacuum release tubes are arranged around the periphery of the boot, with one of the vacuum release tubes being located at the back of the boot. The sole of the boot contains channels in the sole running from the bottom end of the vacuum release tubes to or towards the center of the sole. This makes it possible for water to travel easily over the entire surface of the sole, thus releasing the sole from the mud. If the bottom end of the vacuum release tubes are made of a flexible material, they can be hooked under the edge of the sole and/or the heel, exiting in a horizontal direction. This type of vacuum release tube collapses under the weight of the wearer when the boot is pressed down on the mud, but would open up as water flowed down into the vacuum release tube into a small void formed when the boot is lifted. This type of vacuum release tube would have very little intrusion of mud into the tube.  
         [0024]     In the figures the tubes of the footwear are external to the footwear. However, footwear can be designed to locate the vacuum release tubes entirely within the wall of the footwear.  
         [0025]     The vacuum release tubes can be made of any material which is water resistant, such as polyvinyl chloride or neoprene. The material for the vacuum release tube can be chosen to reduce the coefficient of friction between the inner wall of the tube and the mud, thus ensuring that the vacuum release tubes remain clear under all conditions.  
         [0026]     The vacuum release tubes perform best when the top of the tube is below water. However, the vacuum release tubes still reduce extraction force when they are in air.  
         [0027]     In another embodiment, a horizontal manifold connects the tops of the vacuum release tubes to form a single opening in the top of the tubes. This makes it easy to flush the vacuum release tubes with a garden hose, or to modify the footwear to improve performance in extreme conditions.  
         [0028]     One modification is to mount a small submersible pump near the top of the tubes, with the output connected to the top of the tubes through a manifold. The pump, an electromechanical means for aiding in removing the boot from a cohesive and/or adhesive medium, is used to force water through the tubes, thus further reducing the cohesive and/or adhesive force of the mud. A battery pack placed in a backpack or other container that remains out of the water to power such a device. Switches in each boot are optionally pressure-activated switches in the insole of the boot and complete the circuit when weight is removed from the insole, as when the wearer stands to lift a foot. This activates the pump on the boot and assist removal of the boot from the bottom. An additional hand operated switch can be located with the power source in a position that would permit the wearer to deactivate the device easily when the device is not needed, or to activate both pumps simultaneously when the wearer is assisted by others in removing both boots from the mud simultaneously.  
         [0029]     Alternatively, a carbon dioxide (CO 2 ) or other similar cartridge can be used to assist removal of the footwear from the cohesive and/or adhesive medium. This comprises one example of pneumatic enhancement of extricating the footwear from an adhesive and/or cohesive medium.  
         [0030]      FIG. 1  is a side view of a boot  10  which has one vacuum release tube  12  located at the back of the boot. The vacuum release tube  12  ends at the sole of the boot  14 .  
         [0031]     The boot or other type of footwear  12  can be a standard construction wader made of cloth and neoprene rubber. The top  16  of the vacuum release tube is for entrance of water or air. The bottom of the tube  18  is for exit of water or air as the water or air is drawn down the tube, breaking the suction formed by mud.  
         [0032]      FIG. 2  is a side view of a boot  20  having a plurality of vacuum release tubes  22 . As noted above, there must be one vacuum release tube located at the back of the boot  24 . The vacuum release tubes can be rigid or flexible. In this embodiment the straight tubes  22  are made of rigid one inch PVC pie, and the curved tubes  26  are ¾ inch rubber tubing. The size, number, and construction of the vacuum release tubes can be varied, depending upon the planned application. The top of the vacuum release tubes  21  is the entrance for water or air, which passes through the tubes to the sole area. The exit of the tube is shown at  28 , where water drawn down the tube is discharged, breaking suction formed by mud.  
         [0033]      FIG. 3  is a bottom view of the boot  20  shown in  FIG. 2 , with the exits for the water shown at  28 .  
         [0034]      FIG. 4  shows the bottom of another embodiment of the present invention. The sole  40  of the boot has channels  44  running from the bottom of the vacuum release tubes  42  towards the center of the sole of the boot.  
         [0035]     It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. The means and materials for carrying out disclosed functions may take a variety of alternative forms without departing from the invention. Thus, the expressions “means to . . . ” and “means for . . . ” as may be found in the specification above, and/or in the claims below, followed by a functional statement, are intended to define and cover whatever structural, physical, chemical, or electrical element or structures which may now or in the future exist for carrying out the recited function, whether or not precisely equivalent to the embodiment or embodiments disclosed in the specification above, and it is intended that such expressions be given their broadest interpretation.