Abstract:
A removable plug adapted to seal lifting holes in tubular conduits. The plug includes a cap member having top surface and a bottom surface, the top surface having a cavity therein to facilitate removal, the bottom surface having and a longitudinally extending shaft portion wherein radially extending fins form a generally cruciform cross section.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. provisional patent application Ser. No. 60/921,393 filed 2 Apr. 2007. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]    The present invention relates to plugs used to close openings in concrete pipes and other large tubular conduit structures. Specifically, the plug of the present invention is to be used to close lift holes in such structures. 
         [0003]    Concrete pipes and other large conduit structures used as drain pipe and the like, are typically transported in sections. The sections are then lifted from the transport means and placed in an operational location, such as a trench for example, where final assembly of multiple section lengths is done. Individual heavy sections are lifted from the transport means by way of conventional lifting means, such as a crane. The lifting means typically includes a cable or chain that passes through lift holes in the conduit wall. The lift holes further facilitate positioning during coupling of individual conduit sections, with lifting means engaging the lifting holes. 
         [0004]    After the conduit is properly positioned in its operational condition, it is necessary to fill the lifting holes to thereby prevent dirt, debris and the like from entering the structure. 
         [0005]    Presently, workers plug the holes with rocks and mortar. This procedure is inefficient and time-consuming, since the worker must spend time searching for suitably sized rocks and debris to fill the hole and must further wait for the mortar to set. In addition, a patch formed in this manner is often dislodged by certain environmental forces such as moisture, resulting in further problems requiring re-excavation. 
         [0006]    An alternative known means of filling lifting holes is by way of a stopper device marketed under the POPIT trademark and described in U.S. Pat. Nos. 6,360,779, D456,880, and D458,350. Although the POPIT device solves some of the problems associated with rock and mortar patching, certain inefficiencies persist. Specifically, the particular arrangement of the POPIT device causes difficulty should removal of the device be necessary. For example, the POPIT device includes a cap member with a stem projecting from the cap member; the stem member further includes radially extending web means for anchoring the device to the lifting hole. During removal, the web means is prone to catch on the inner wire mesh structure of a concrete conduit, and in some instances, may necessitate a worker to crawl inside the conduit to force removal. A POPIT device removed in this manner is usually damaged and unable to be reused. 
         [0007]    The present invention contemplates an improvement of stopper-type devices, by providing a device that is both easy to put in place and, if necessary, to remove. 
       SUMMARY OF THE INVENTION  
       [0008]    The present invention provides a simple and low cost plug for filling the lift holes in tubular conduits prior to covering the worksite, such as a trench, with earth or other back fill. The invention accomplishes this purpose by providing a stopper device or plug having a cap member in the form of a substantially planar disc, preferably made of plastic, and provided with a stem member laterally extending endwise from one side of the cap member. The stem member preferably has a generally cruciform cross section formed by a plurality of laterally extending fin members. The cap member further preferably includes a releasably attachable access cavity to facilitate removal. 
         [0009]    The particular arrangement of the present stem member allows for secure friction fit, but also allows the device facile removal and reuse, if required. The size of the device may be adapted for use with variously sized lift holes, without departing from the spirit of the invention. 
         [0010]    The invention generally includes a cap member and a stem member. The cap member preferably includes a top side and a bottom side, with the stem member extending from the bottom side of the cap member. The stem member is preferably of a generally cruciform cross section which thereby provides at least four fins extending from a central axis. The fins are preferably disposed substantially at 90 degrees relative one another to thereby form the aforementioned cruciform cross section. Although this arrangement is preferred, it is to be understood that it is within the scope of the present invention to arrange the fins in other arrangements, including at various angles of relative placement and various total number of fins. 
         [0011]    The present device may be composed of any durable material that is capable of being inserted in the lift hole and effectively remaining in place after construction and placement of the conduit, including plastic materials. The cap member and stem member may be integrally molded as a one-piece construction, as by injection molding. 
         [0012]    As seen in the drawings, the cap member preferably includes means for removing the plug. The means for removing, such as a releasably attachable means, allows the user to remove the plug from the lifting hole as may be necessary from time to time. Such means may include providing the top surface of the cap member with at least one upright or upstanding rib member. The upright preferably includes an access cavity. The user may engage the access cavity to remove the plug. Alternatively, the top surface itself may provide means for removing by way of an incised cavity, which may be engaged by a tool such as a screwdriver head to lift the plug from its installed position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]      FIG. 1  is a perspective view of an embodiment of the invention. 
           [0014]      FIG. 2  is a front elevation view of the embodiment illustrated in  FIG. 1 , the back elevation view being identical thereto. 
           [0015]      FIG. 3  is a top plan view of the embodiment illustrated in  FIGS. 1 and 2 , and showing an access cavity to facilitate removal. 
           [0016]      FIG. 4  is a bottom plan view of the plug shown in  FIGS. 1-3 , and showing the generally cruciform cross section of the stem member. 
           [0017]      FIG. 5  is a cross sectional view of the present invention, taken along lines  5 - 5  of  FIG. 6 , and showing the device in operational condition in a generally circular conduit lift hole, with a fragmentary view of the conduit. 
           [0018]      FIG. 6  is a bottom view of the plug shown in  FIG. 5 , and illustrating deflection of the fin members while in place in a generally circular lift hole, with a fragmentary view of the conduit. 
           [0019]      FIG. 7  is a cross sectional view of the present invention, taken along lines  7 - 7  of  FIG. 8 , and showing the device in operational condition in a lift hole having an irregular diameter with a fragmentary view of the conduit. 
           [0020]      FIG. 8  is a bottom view of the plug shown in  FIG. 7 , and illustrating deflection of the fin members while in place in an irregularly configured lift hole, with a fragmentary view of the conduit 
           [0021]      FIG. 9  is a view of a tubular conduit having lifting holes therein of the type to be fitted with the plug of the present invention. 
           [0022]      FIG. 10A  is a perspective view of an alternative plug and showing a cap member with incised cavity. 
           [0023]      FIG. 10B  is a fragmentary cross sectional view of the embodiment shown in  FIG. 10A  and taken along lines  10 B- 10 B thereof. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
         [0025]    As mentioned above, typical poured concrete conduit, or other tubular conduit is conventionally made in predetermined lengths as dictated by ultimate use and transportation limitations. The conduit is transported by conventional means, such as flat bed truck to an installation site where the individual conduit lengths are assembled, end to end, for their predetermined purpose. 
         [0026]    As illustrated in  FIG. 9 , since the individual conduit lengths  200  are typically heavy and unwieldy, a lift hole  100  is conventionally provided through the side wall of the conduit length  200 . As seen in the view of  FIG. 9 , the lift hole  100  has as its purpose to provide access for lifting means, such as the lift hook(s)  104  shown. The means for lifting preferably further includes the use of a crane (not shown) or other conventional means, which is used to both move the conduit  200  from transport means, and to align the conduit  200  during installation. 
         [0027]    If the conduit  200  is to be installed in a trench or other earthen environment, the lift hole  100  must be filled to prevent infiltration of moisture or other damaging material. As mentioned previously, the present conventional method of filling the lift hole includes inserting a brick or stone into the hole and covering with mortar. 
         [0028]    Referring now to  FIGS. 1 and 2 , a plug  10  according to the present invention is illustrated. The plug  10  preferably includes a cap member  12  in the form of a substantially planar disc  14  and having a top surface  16  and an opposed bottom surface  18 . Although illustrated as being generally circular, it is to be understood that the cap member  12  may be of any appropriate shape, such as oval. Further, the plug  10  may be modified to fit lift holes of varying sizes without departing from the spirit of the invention. As seen, a stem member  20  laterally extends endwise from the bottom surface  18  of the cap member  12 . The stem member  20  preferably has a generally cruciform cross section formed by a plurality of laterally extending fin members  22 . The cap member  12  and stem member  20  may be integrally molded as a one piece construction, as by injection molding. 
         [0029]    Further referring to  FIGS. 1 and 2 , it may be seen that the top surface  16  of the cap member  12  preferably includes releasable attachment means, such as the access cavity  24  shown, to thereby facilitate removal of the plug from a lift hole (not seen in these views). Means for removing the plug  10  allows the user to remove the plug  10  from the lifting hole  100 , as may be necessary from time to time. As observed in  FIG. 1 , such means may include providing the top surface  16  of the cap member  12  with at least one upstanding rib member  17 . When provided with an upstanding rib member  17 , the rib member preferably includes an access cavity  24 . The user may then engage the access cavity  24  to remove the plug  10  as needed. Alternatively, and as viewed in  FIGS. 10A and 10B , the top surface  16  may be provided with means for removing by way of an incised cavity  28 , which may be engaged by a tool such as a screwdriver head (not shown) to lift the plug  10  from its installed position. 
         [0030]    The plug  10  according to the present invention may be composed of any acceptable durable material that is capable of being inserted in a lift hole and effectively remaining in place after construction and placement of the conduit. Preferably, any injection molded plastic may be used, however the choice of material is dictated only by convenience, availability and low cost of materials. 
         [0031]    With particular reference to  FIG. 2 , configuration of the stem member  20  and laterally extending fins  22  may be seen. Specifically, the fins  22  of the present invention extend laterally from the axis  26  of the stem member  20 . As may be observed, each respective fin member  22  extends laterally from the stem axis  26  to form a preferred marginal edge profile  30 . The preferred fin marginal edge profile  30  includes a bottom marginal edge portion  32  extending laterally from the stem member axis  26 . The bottom edge portion  32  intersects with a second marginal edge portion  34  which extends angularly outwardly relative to the stem member axis  26 . The second marginal edge portion  34  intersects with a third marginal edge portion  36  which is essentially parallel to the stem member axis  26 . The third marginal edge portion  36  intersects with a fourth marginal edge portion  38 . The fourth marginal edge portion  38  extends laterally inwardly from the third marginal edge portion  36 . As seen the fourth marginal edge portion  38  preferably extends inwardly relative to the stem member axis  26 . The fourth marginal edge portion  38  intersects a fifth, terminal edge portion  40  which intersects with the bottom surface  18  of the cap member  12 . The specific fin profile  30  allows the plug  10  to be inserted into lift holes  100  of various dimensions, while effectively sealing the hole  100 . 
         [0032]    It may be noted that at least a portion of each fin profile  30  is flexible. For example, as seen in  FIG. 2 , the area noted generally as  42 , which includes the second, third and fourth marginal edge portions,  34 ,  36 ,  38 , respectively, is preferably relatively flexible as compared to the other elements of the stem  20  and fin profile  30 . The flexibility is offered primarily due to the nature of the fin profile  30 . That is, since the third and fourth marginal edge portions,  36 ,  38 , are not directly connected to the bottom surface  18  of the cap member  12 , as is the fifth marginal edge portion  40 , as long as each fin member  22  is manufactured from a relatively thin, flexible material, that portion of each fin member  22  is free to bend and deflect as it comes in contact with the inside surface  102  of a lifting hole  100 . The flexible portion  42  of a respective fin member  22  enables the plug  10  to be secured in a selected lift hole  100 . It is to be further noted that while not shown, it is within the scope of the present invention to provide the fin members  22  with additional flexibility by tapering the thickness of any of the aforementioned marginal edge portions  32 ,  34 ,  36 ,  38 ,  40 . 
         [0033]    As may be observed in  FIGS. 5-8 , the aforementioned preferred profile  30  of the fin members  22  allows respective fin members  22  to deflect relative the stem member axis  26  to thereby adapt to a specific lift hole  100  contour. For example, and as viewed in  FIGS. 5 and 6 , since the fin profile  30  includes the aforementioned flexible portion  42 , the fin members  20  are able to deflect to the degree needed to effectively hold the plug  10  in a lift hole  100 , regardless of any dimensional variation in the contour of the inside surface  102 . A comparison of  FIGS. 5 and 6  with  FIGS. 7 and 8  reveals that the specific fin profile  30  permits the fin members  22  to deflect in a manner appropriate for the irregularly contoured lift hole  100  illustrated- in  FIGS. 7 and 8 . The adaptability afforded by the specific fin profile  30  enhances the practicality of the plug  10  according to the present invention. 
         [0034]    As mentioned previously, the stem member  20  and extending fins  22  is of a generally cruciform cross section provided by at least four fin members  22  extending from the stem member central axis  26 . As best viewed in  FIG. 4 , the fin members  22  are preferably disposed substantially at 90 degrees relative one another to thereby form the aforementioned cruciform cross section. Although this arrangement is preferred, it is to be understood that it is within the scope of the present invention to arrange the fin members  22  in other arrangements, including various angles of relative placement and various total number of fin members  22 . 
         [0035]    The particular arrangement of the present stem member  20  allows for secure friction fit, but also allows facile removal and re-use, if required. The size of the device may be adapted for use with variously sized lift holes, without departing from the spirit of the invention. 
         [0036]    The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.