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BACKGROUND 
     The following background information may present examples of specific aspects of the prior art (e.g., without limitation, approaches, facts, or common wisdom) that, while expected to be helpful to further educate the reader as to additional aspects of the prior art, is not to be construed as limiting the present invention, or any embodiments thereof, to anything stated or implied therein or inferred thereupon. 
     The present invention is directed to a portable barrier for a door sill that fills a gap between the flooring and the bottom of a respective door to inhibit passage of water, air, and pests through the gap and onto the flooring inside the respective building. 
     The inventor noticed that often, water, air, and pests would pass beneath the threshold of the door, even when the door was closed. The inventor realized that this was often an undesirable invitation to damage to the floor and interior of the building. 
     The inventor realized that with increasing heating costs, it was becoming more and more important to reduce as much as possible the infiltration of air through doors and windows. The inventor quickly saw that the major sources of air infiltration is through the bottom of the doors of dwellings. The inventor decided that the threshold should provide a good thermal barrier in order to prevent condensation and icing on the portion of the threshold within the building interior. Additionally, the inventor knew that flooding from outside the building would seep through the door, and thereby cause damage to the carpet and furniture inside. And finally, the inventor knew that ants, termites, cockroaches, and even small mice could squeeze between the door sill and the bottom of the door. 
     Through additional research, the inventor learned that since thresholds are installed in door openings, they are disposed in high pedestrian traffic area of the respective building and subjected to substantial stresses as people often step on the respective threshold. Often such pedestrian traffic can cause the cantilevered toe portion to bend downward, thereby deforming the respective door sill. Furthermore, although known thresholds generally prevent rain water from passing though the gap between the bottom of the door and the flooring onto the flooring inside the respective building, known door sills often allow rain water to flow under the threshold itself 
     The inventor decided that an additional barrier had to be combined with the traditional door sill to provide greater protection against water, air, and pests. The inventor noted that, generally all exterior door openings, or doorways, include a threshold, commonly referred to as a door threshold. Such door thresholds generally provide a transition between the exterior building structure and the flooring inside the respective door opening, and provide a means for preventing water and air from easily passing between the bottom of a door hung in the respective door opening and the respective flooring. 
     The inventor decided to install a barrier in the space that forms in the door sill, between the heel and toe portions. This fixed barrier that the inventor attached did well to prevent the water, air, and pests from entering through the threshold. However, when a wheeled vehicle needed to pass over the barrier, it was restricted from doing so and had to be lifted. 
     Through trial and error, the inventor learned that a spring could be combined with the barrier. The spring occupied a space that enabled the barrier to remain extended to block the passageway beneath the door, yet also enabled the barrier to compress into the door sill when a wheeled vehicle passed through. However, after noticing the wheeled vehicle could not always clear the barrier easily, the inventor made one of the edges tapered, so that the wheel could more easily roll over the barrier. 
     The inventor realized that the barrier could have more uses to work with variously sized door sills and thresholds if it was portable and height adjustable. The inventor added a bolt that detachably anchored the barrier into the floor. The bolt also adjusted the height of the barrier in the natural extended position. 
     For the foregoing reasons, there is a portable barrier for a door sill that fills a gap between the flooring and the bottom of a respective door to inhibit passage of water, air, and pests through the gap and onto the flooring inside the respective building. 
     Delivery systems and methods have been utilized in the past; yet none with the characteristics of the present invention. See U.S. Pat. Nos. 5,010,690; 6,484,446; and 8,966,823. 
     For the foregoing reasons, there is a need for a portable barrier for a door sill that fills a gap between the flooring and the bottom of a respective door to inhibit passage of water, air, and pests through the gap and onto the flooring inside the respective building. 
     SUMMARY 
     The present invention describes a portable barrier for a door sill that fills a gap between the flooring and the bottom of a respective door to inhibit passage of water, air, and pests through the gap and onto the flooring inside the respective building. The portable door sill barrier, hereafter, “barrier”, detachably attaches to a door sill that is disposed on an exterior side of the door. The door sill may include a horizontal piece of wood, stone or metal at the threshold of a doorway or doorstep. In one embodiment, the door sill comprises an elongated triangular structure having a top surface, a heel portion, and a toe portion; wherein the top surface is angled and declines in height to form a slope. A space forms between the heel portion and the toe portion of the door sill. The barrier detachably positions inside the space. 
     The barrier is height adjustable, so as to enable the dual function of inhibiting passage through the gap beneath the door, and enabling passage of a wheeled vehicle over the barrier and through the threshold of the door. The barrier utilizes a spring-tensioned mechanism that biases towards an extended position for expanding the barrier above the space in the door sill, and thereby inhibiting passage through the threshold of the door. In this manner, the door sill inhibits passage up to a first height; and the barrier, in essence, extends the height capacity of the door sill by filling the gap beneath the floor and the door. In addition to the extended position, the spring-tensioned mechanism of the barrier is configured to compress flush with the top surface of the door sill when a pressure is applied thereon. The pressure that is exerted on the barrier may include a wheel from a vehicle that presses down on the barrier as it passes through the threshold of the door. The barrier is tapered at the top surface, so as to help the wheel smoothly pass over the barrier. 
     In some embodiments, the barrier may include a restriction bar having at least one tapered edge and at least one aperture. The restriction bar is configured to provide the chief restriction against water, air, and pests above the door sill. The barrier may further include a mount bar. The mount bar comprises at least one mount hole. The mount bar is rests in a parallel, spaced-apart relationship to the restriction bar. The mount bar enables the barrier to be anchored to the floor. The restriction bar moves in relation to the anchored mount bar. 
     The barrier further comprises a connecting tube that joins the restriction bar with the mount bar. The connecting tube is disposed in alignment with the at least one aperture and the at least one mount hole. The barrier further includes a mounting tube. The mounting tube includes a threaded inner surface and a cavity. The mounting tube remains in alignment with the connecting tube and the at least one mount hole. The mounting tube extend from the mount bar, towards the floor. The mounting tube may penetrate the floor for anchoring the barrier. 
     In some embodiments, the barrier may further include a bolt. The bolt has a head end and a mount end. The mount end may include threads that are configured to rotatably engage the threaded inner surface of the mounting tube. The bolt is configured to pass through the at least one aperture, the connecting tube, the at least one mount hole, and the mounting tube. In this manner, the bolt may be displaced cross-length to the barrier, passing through the connecting tube and the mounting tube. The threaded interaction between the threads of the bolt and the threaded inner surface of the mounting tube enables the bolt to rotate in a first direction. This works to urge the restriction bar towards the mount bar. Conversely, the bolt can be rotated in a second direction to urge the restriction bar away from the mount bar. In this manner, the restriction bar can be fixed at a desired height while in the natural extended position. 
     The barrier further comprises a spring that displaces the restriction barrier above the top surface of the door sill from a natural position. The spring may also be forcibly compressed to enable the restriction barrier to move towards the mount barrier, towards the mount bar. The spring is disposed between the bolt and the mounting tube. The spring rests in the cavity that forms inside the mount tube. Specifically, the spring wraps around the bolt. 
     The spring is configured to position in a natural extended position from around the bolt. The extended position of the spring urges the restriction bar away from the mount bar, as the tension of the spring presses against the restriction bar. The spring is further configured to be urged into a compressed position by applying a downward force on the restriction bar. The compressed position of the spring enables the restriction bar to be displaced towards the mount bar. In this manner, the restriction bar remains extended to serve as a barrier against water, air, and pests; yet the weight of a wheeled vehicle can press the restriction bar into the space formed by the door sill so for passing over the barrier and through the threshold of the door. 
     One objective of the present invention is to prevent water, air, and pests from penetrating a joint formed between a bottom of the threshold and a floor structure to which the threshold is mounted. 
     Another objective of the present invention is to provide a portable barrier that mounts into a door sill, yet can be easily unmounted for portability to a different door sill. 
     Another objective of the present invention is to enable a wheeled vehicle to roll over the barrier. 
     Yet another objective of the present invention is to provide a portable barrier that adjusts to fit different door sills. 
     Yet another objective is to provide a portable barrier that is height adjustable for restricting passage through variously sized gaps between the threshold and the door. 
     Yet another objective is to provide a bolt that retains the restriction bar at a fixed distance from the mount bar. 
     Yet another objective is to provide a portable barrier that is inexpensive to manufacture and adaptable to variously sized door sills. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and drawings where: 
         FIGS. 1A, 1B, and 1C  are perspective views of an exemplary portable barrier moving from an extended position to a compressed position relative to an exemplary door sill, where  FIG. 1A  shows a perspective exploded view of an exemplary portable barrier,  FIG. 1B  shows a perspective view of the portable barrier shown in  FIG. 1A  with an exemplary restriction bar detached from an exemplary mount bar; and  FIG. 1C  shows a perspective view of the portable barrier shown in  FIG. 1A  with the restriction bar engaged with the mount bar; 
         FIGS. 2A and 2B  are sectioned side views of the portable barrier extended and compressed into door sill, where  FIG. 2A  shows the extended position, and  FIG. 2B  shows the compressed position; 
         FIGS. 3A and 3B  are close up sectioned views of the portable barrier extended and compressed into door sill, where  FIG. 3A  shows an exemplary spring in the extended position, and  FIG. 3B  shows the spring in the compressed position; 
         FIGS. 4A and 4B  are perspective views of the portable barrier extended from the door sill in front of an open threshold of a door, where  FIG. 4A  shows the door opened, and  FIG. 4B  shows a close up of the sill in relation to the opened door; and 
         FIGS. 5A and 5B  are perspective views of the portable barrier compressed into the door sill in front of a closed threshold of a door, where  FIG. 5A  shows the door closed, and  FIG. 5B  shows a close up of the sill in relation to the closed door. 
     
    
    
     DESCRIPTION 
     The present invention is directed to a portable barrier  100  for a door sill  200  that fills a gap between the flooring and the bottom of a respective door  210  to inhibit passage of water, air, and pests through the gap and onto the flooring inside the respective building. The portable barrier  100 , hereafter, “barrier  100 ”, is portable to be operational with variously sized and dimensioned door sills  200 . The barrier  100  may be used with different styles and sizes of doors  210  to restrict passage through the gap that forms beneath the door  210  at the threshold. 
     The barrier  100  detachably attaches to a door sill  200  that rests on an exterior side of the door  210 . The door sill  200  may include a horizontal piece of wood, stone or metal at the threshold of a doorway or doorstep. In one embodiment, the door sill  200  comprises an elongated triangular structure having a top surface  202 , a heel portion  206 , and a toe portion  204 ; wherein the top surface  202  is angled and declines in height to form a slope. A space  208  is disposed between the heel portion  206  and the toe portion  202  of the door sill  200 . In one embodiment, the barrier  100  detachably positions inside the space  208 , extending along the length of the door sill  200 . 
     The barrier  100  detachably attaches to a door sill  200  that rests on an exterior side of the door  210 . The door sill  200  may include a horizontal piece of wood, stone or metal at the threshold of a doorway or doorstep. In one embodiment, the door sill  200  comprises an elongated triangular structure having a top surface  202 , a heel portion  206 , and a toe portion  204 ; wherein the top surface  202  is angled and declines in height to form a slope. A space  208  forms between the heel portion  206  and the toe portion  204  of the door sill  200 . In one embodiment, the barrier  100  detachably positions inside the space  208 , extending along the length of the door sill  200 . 
     Looking now at  FIGS. 1B and 1C , in addition to the extended position  124 , the spring  116  is configured to compress, so that the barrier  100  remains flush with the top surface  202  of the door sill  200  when a pressure is applied thereon, as shown in  FIGS. 2A and 2B . The pressure that is exerted on the barrier  100  may include a wheel from a vehicle that presses down on the barrier  100  as it passes through the threshold of the door  210 . Though, any mobile object may easily pass over the barrier  100 . The barrier  100  is tapered at the top surface  202 , so as to help the wheel smoothly pass over the barrier  100 . 
     Turning now to  FIG. 3A , the barrier  100  may include a restriction bar  102 . The restriction bar  102  is configured to provide the chief blockage against water, air, and pests between the door  210  and the door sill  200 . The restriction bar  102  is elongated and has a generally cubicle cross section, so as to fit into the space of the door sill  200 . The restriction bar  102  may include at least one aperture  104 . Two apertures are sized and dimensioned to receive a threaded member and are formed on the restriction bar  102 . 
     As shown in  FIG. 3B , the restriction bar  102  may include at least one tapered edge  106 . The tapered edge  106  is configured to enable a wheel to cross the barrier  100 . Those skilled in the art will recognize that a tapered edge  106  forms a fulcrum that provides leverage for a wheel to more easily roll over the restriction bar  102 . Suitable materials for the restriction bar  102  may include, without limitation, metal, wood, and a rigid polymer. 
     The barrier  100  may further include a mount bar  108 . The mount bar  108  is rests in a parallel, spaced-apart relationship to the restriction bar  102 . The mount bar  108  is elongated and is generally flat. The mount bar  108  enables the barrier  100  to be anchored to the floor. The restriction bar  102  moves in relation to the anchored mount bar  108 . The mount bar  108  comprises at least one mount hole  110 . In one embodiment, two mount holes  110  that are sized and dimensioned to receive the bolt  118  pass through the mount bar  108 . Suitable materials for the mount bar  108  may include, without limitation, metal, wood, and a rigid polymer. 
     Looking back at  FIG. 1A , the barrier  100  comprises a connecting tube  112  that joins the restriction bar  102  with the mount bar  108 . The connecting tube  112  is disposed in alignment with the at least one aperture  104  and the at least one mount hole  110 . The connecting tube  112  ensures that the restriction bar  102  and the mount bar  108  remain aligned. 
     The barrier  100  further includes a mounting tube  114 . The mounting tube  114  includes a threaded inner surface and a cavity. The mounting tube  114  remains in alignment with the connecting tube  112  and the at least one mount hole  110 . The mounting tube  114  extends from the mount bar  108 , and towards the floor. The mounting tube  114  may penetrate the floor to enable the barrier to be anchored into the floor from the space  208  in the door sill  200 . In one embodiment, multiple mounting tubes extend in a spaced-apart relationship across the mount bar  108 . 
     In some embodiments, the barrier  100  may further include a bolt  118 . The bolt serves to tie the components of the barrier  100  together. The bolt  118  also penetrates the floor for detachably anchoring the barrier  100  into the door sill  200 . The bolt  118  has a head end  120  and a mount end  122 . The head end  120  may include a slot for receiving a screwdriver. A washer (not shown) may be positioned between the head end  120  of the bolt  118  and the connecting tube  112 . The mount end  122  of the bolt  118  may include threads that are configured to rotatably engage the threaded inner surface of the mounting tube  114 . The bolt  118  may include, without limitation, a screw, a through bolt  118 , and an anchor bolt  118 . 
     The bolt  118  is configured to pass through the at least one aperture  104 , the connecting tube  112 , the at least one mount hole  110 , and the mounting tube  114 . In this manner, the bolt  118  may be displaced cross-length to the barrier  100 , passing through the connecting tube  112  and the mounting tube  114 . The threaded interaction between the threads of the bolt  118  and the threaded inner surface of the mounting tube  114  enables the bolt  118  to rotate in a first direction. This works to urge the restriction bar  102  towards the mount bar  108 . The first direction may include a clockwise direction. Conversely, the bolt  118  can be rotated in a second direction to urge the restriction bar  102  away from the mount bar  108 . The second direction may include a counterclockwise direction. In this manner, the natural height of the restriction bar  102  can be adjusted, depending on the door sill  200  and the door  210 . 
     The barrier  100  further comprises a spring  116  that displaces the restriction bar  102  above the top surface  202  of the door sill  200  from a natural position. The spring  116  may also be forcibly compressed to enable the restriction bar  102  to move towards the mount bar  108 . The spring  116  is disposed between the bolt  118  and the mounting tube  114 . The spring  116  rests in the cavity that forms inside the mounting tube  114 . Specifically, the spring  116  wraps around the bolt  118 , abutting against the sidewalls of the cavity to compress and expand, depending on the forces applied thereon. In one embodiment, the spring  116  is a coil spring that naturally expands, yet is also adapted to be compressed, so as to store energy that can be used to push against the restriction bar  102 . 
     As illustrated in  FIG. 4A , the spring  116  is configured to position in a natural extended position  124  while wrapped around the bolt  118 . The extended position  124  of the spring  116  urges the restriction bar  102  away from the mount bar  108 , as the tension of the spring  116  presses against the restriction bar  102 .  FIG. 4B  shows a close up view of the restriction bar  102  extended in front of an open threshold of a door  210 . 
     Looking now at  FIG. 5A , the spring  116  is further configured to be urged into a compressed position  126  by applying a downward force on the restriction bar  102 . The force may include the weight of a wheeled vehicle. The compressed position  126  of the spring  116  enables the restriction bar  102  to be displaced towards the mount bar  108 . 
     Because of the spring  116 , the restriction bar  102  remains in a natural extended position  124  to block water, air, and pests; yet the spring  116  allows the weight of a wheeled vehicle to press the restriction bar  102  into the space  208  formed by the door sill  200  for passing over the barrier  100  and through the threshold of the door  210 .  FIG. 5B  shows a close up view of the restriction bar  102  compressed into the space  208  of the door sill  200  in front of a closed threshold of a door  210 . 
     While the inventor&#39;s above description contains many specificities, these should not be construed as limitations on the scope, but rather as an exemplification of several preferred embodiments thereof. Many other variations are possible. For example, the barrier may be used without a door sill, anchoring directly into the flooring. Accordingly, the scope should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

Summary:
A portable barrier for a door sill that comprises of a restriction bar, a mount bar that is disposed on the restriction bar, a connection tube that joins the restriction bar with the mount bar, and an adjustable spring mechanism that allows the mount bar to be adjusted upward or downward. The adjustable mechanism comprises springs and screws that can be manually adjusted.