Abstract:
A door jamb is formed having a vertical jamb member which defines a jamb opening. A replaceable jamb member is sized to be removably secured in the jamb opening by a connection element, preferably shear screws. The shear screws are formed to break or shear apart so as to release the replaceable jamb member when an effective amount of force is applied. When the shear screws break, the replaceable jamb member is free to slide out of jamb opening and release a door which is latched thereto, thus saving the surrounding jamb elements and the door itself from damage. The effective amount of force is generally the force needed to break down a conventional door.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from U.S. Provisional Application Ser. No. 61/323,504, filed Apr. 13, 2010, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates generally to door construction. More particularly, the present invention relates to a replaceable door jamb system for a door. Specifically, the present invention relates to a vertical jamb member defining a jamb opening, whereby a replaceable jamb member is removably secured therein by a connection element, and whereby the connection element releases the replaceable jamb member from the jamb opening when an effective amount of force is applied to the door. 
         [0004]    2. Background Information 
         [0005]    A common way for criminals or law enforcement to gain access to a locked building is to kick or strike an external door so hard that the door lock splits the wood of the door jamb and allows entry into the formerly locked building. This type of forced entry results in physical damage which must be repaired at substantial cost. Not only does physical damage occur in the door jamb, but damage also occurs to the door itself, adding to the complexity and cost of repair. Furthermore, it is commonly known in the art that once a door and door jamb is damaged through forced entry, it rarely provides the same structural integrity and often results in gaps around the periphery of the door. As such, both a damaged door and the door jamb are often entirely replaced, at substantial cost to the owner. When the building is a complex of apartment units located in a high crime area, which is common with public housing, several doors per week may be forced open by either law enforcement or criminals. This results in a dramatic ongoing cost to the building owner which may substantially reduce the return on the real estate investment, or in the case of public housing, cost taxpayers millions every year. 
         [0006]    Therefore, there is strong need in the art for an improved doorjamb system which provides the same level of security as a conventional door jamb system, yet prevents substantial damage to the door and door jamb in the event of a forced entry through the door. It is desirable to facilitate a forced entry which preserves the integrity of the door jamb and door by providing a replaceable jamb member which slides out of a vertical jamb member in response to the force. Thus, only the replaceable jamb member requires replacement. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present invention relates to a doorjamb having a vertical jamb member defining a jamb opening whereby a replaceable jamb member is removably secured therein by a connection element, preferably in the form of a plurality of shear screws. The shear screws release the replaceable jamb member from the jamb opening when an effective amount of force is applied to a door secured to the door jamb, typically by a criminal or law enforcement forcing entry into a building. The shear screws include an effective force threshold, such that the shear screws purposely break into two portions or shear away threads when the force threshold is reached, to disengage the replaceable jamb member from the vertical jamb member. The effective force threshold is generally equal to the amount of force required to break down a conventional door. Thus, the present invention provides the same amount of protection as a conventional door. 
         [0008]    The replaceable jamb member thereafter slides out of the jamb opening, allowing the door to open without splitting or breaking the door jamb. This saves the vertical jamb member and the door itself from damage cause by the forced entry. The building owner or a maintenance person then simply places a new replaceable jamb member in jamb opening and secures it thereto with new shear screws. Replacing the replaceable jamb member and shear screws represents a fraction of the cost of a replacing the entire door jamb or door. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0009]    A preferred embodiment of the invention, illustrated of the best mode in which Applicant contemplates applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. 
           [0010]      FIG. 1  is a front elevational view of a building having a door disposed in a wall; 
           [0011]      FIG. 2  is a front elevational view of a door frame in a wall having part of the wall cutaway; 
           [0012]      FIG. 3  is a front elevational view of the door frame in  FIG. 2  having a door disposed in the door frame; 
           [0013]      FIG. 4  is an exploded perspective view of the door jamb of the present invention showing the vertical jamb member and replaceable jamb member exploded from the door frame; 
           [0014]      FIG. 5  is a side elevational view of  FIG. 4 ; 
           [0015]      FIG. 6  is a partially exploded perspective view showing the vertical jamb member secured to the door frame, and the replaceable jamb member, shear screws, weather strip, and interior casing exploded therefrom; 
           [0016]      FIG. 7  is a perspective view of the vertical door jamb member secured to the door frame and with the weather strip and interior casing secured thereto; 
           [0017]      FIG. 8  is an enlarged cross-sectional view taken along line  8 - 8  of  FIG. 7 ; 
           [0018]      FIG. 9  is an exploded cross-sectional view similar to  FIG. 8  after the door is forced open in the direction of Arrow A, and having shear screws with releasable threads; 
           [0019]      FIG. 10  is a cross-sectional view similar to  FIG. 8  after having the door forced open in the direction of Arrow A, and having shear screws with a breakable shaft; and 
           [0020]      FIG. 11  is an exploded perspective view of a second embodiment of the present invention having the vertical jamb member separated into two portions. 
       
    
    
       [0021]    Similar numbers refer to similar parts throughout the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    A replaceable door jamb system of the present invention is represented generally at  1 , and shown in  FIGS. 1-11 . As shown particularly in  FIGS. 1-3 , replaceable door jamb system  1  is incorporated in a door  3  having a door knob  4 , a dead bolt latch  8 , and hinges  6 , which is disposed in a wall  5  of a building  7 . Wall  5  is shown in  FIG. 1  as an exterior wall of a single-family residential building  7 . However, wall  5  of the present invention may be an interior wall and building  7  may be a commercial building, multi-unit, or multi-family structure. 
         [0023]    As shown in  FIGS. 1-4 , wall  3  includes an exterior wall surface  9  formed by a material  11 , referred to hereafter as plywood  11 . Similarly, wall  3  further includes an interior wall surface  13  formed by a material  15 , referred to hereafter as drywall  15 . Plywood  11  and drywall  15  are flat plate-like structures disposed in a spaced apart and general vertical direction, extending parallel to one another. As shown in  FIG. 2 , disposed between plywood  11  and drywall  15  are a plurality of vertical wall studs  17  extending from a floor board  19  and a floor stud  20  to a ceiling (not shown) along the length of wall  3  to provide reinforcement. A door opening  21  in wall  3  is defined by a door frame  23  having a horizontal frame member  25  and a pair of vertical frame members  27 A and  27 B extending vertically therefrom. As shown in  FIG. 4 , vertical frame member  27 A includes a first stud  29  having an outer face  31  and a second stud  33  adjacent thereto. 
         [0024]    As shown in  FIGS. 3 and 4 , a door jamb  35  is secured to door frame  23  and includes a horizontal jamb member  37  and a pair of vertical jamb members  39 A and  39 B extending vertically therefrom. Vertical jamb member  39 A includes a pair of projections  40 A and  40 B, an integrally formed doorstop  41  area, and a side surface  43  having a groove  44  formed therein. Vertical jamb member  39 A is formed with a jamb opening  45  and in accordance with the main feature of the invention, includes a replaceable jamb member  47 . 
         [0025]    As shown in  FIG. 5 , vertical jamb member  39 A includes a back surface  49 , a front surface  51 , an interior surface  52 , an exterior surface  54 , a pair of surfaces  53 A and  53 B, a pair of surfaces  55 A and  55 B, and a pair of surfaces  57 A and  57 B. Replaceable jamb member  47  includes a pair of projections  59 A and  59 B, a front surface  61 , a back surface  63 , an interior surface  56 , an exterior surface  58 , a pair of surfaces  65 A and  65 B, a pair of surfaces  67 A and  67 B, and a pair of surfaces  69 A and  69 B. 
         [0026]    As shown in  FIGS. 6 and 7 , a weather strip gasket  71  having a projection  73  is fitted into groove  44  in doorstop  41 . An interior casing  75  having an inner side  76  and an outer side  77  is secured to wall  3 . Similarly, an exterior casing  79  having an inner side  80  and an outer side  81  is secured to wall  3 . A plurality of shear screws  83  secure replaceable jamb member  47  in jamb opening  45 , wherein a deadbolt strike plate  85  and a knob bolt strike plate  86  are secured by a plurality of screws  87 . Each shear screw  83  includes a head  84 , a shaft  82 , and a plurality of threads  78  disposed on shaft  82 . Deadbolt strike plate  85  includes a bolt aperture  90  for passing a deadbolt (not shown) therethrough into a recess  91  formed in removable jamb member  47 . Similarly, knob bolt strike plate  86  includes a bolt aperture  93  for passing a knob bolt  88  ( FIG. 9 ) therethrough into a recess  94  formed in removable jamb member  47 . 
         [0027]    In operation, vertical jamb member  39 A is secured to vertical frame member  27 A with back surface  49  abutting outer surface  31  and jamb opening  45  is proximate drywall  15 . It is common to build and ship an entire door system having a door jamb in a pre-assembled manner, including an attached door. In such a system formed with vertical jamb member  39 A, it is desirable to hold replaceable jamb member  47  within jamb opening  45  during transit and installation to add stability to the door system and vertical jamb member  39 A in particular as it is moved about. This may be done by any manner common in the art, including staples, heavy duty tape, or any form of an anchor. 
         [0028]    As shown in  FIG. 6 , after vertical jamb member  39 A is secured to vertical frame member  27 A, replaceable jamb member  47  is secured in jamb opening  45  by extending shear screws  83  through front surface  61  into replaceable jamb member  47 , and out of replaceable jamb member  47  through back surface  63 . Shear screws  83  then enter first stud  29  through outer surface  31 , and securely hold replaceable jamb member  47  in jamb opening  45 . Thus, it is a primary feature of the present invention that replaceable jamb member  47  is not secured or connected to vertical jamb member  39 A. This configuration facilitates replaceable jamb member  47  moving out of jamb opening  45  without damaging vertical jamb member  39 A. 
         [0029]    Once replaceable jamb member  47  is secured in jamb opening  45 , the user finishes hanging door  3  using typical methods commonly know in the art, which includes drilling recess  91  and recess  94  into replaceable jamb member  47  and securing deadbolt strike plate  85  and knob bolt strike plate  86  thereon. Projection  73  of weather strip gasket  71  is then secured in groove  44 , and interior casing  75  and exterior casing  79  are secured to drywall  15  and plywood  11 , respectively. When replaceable door jamb system  1  is assembled, door  3  horizontally pivots about hinges  6  whereby door stop area  41  and side surface  43  faces towards the interior of building  7 . 
         [0030]    As shown in  FIGS. 5 and 6 , jamb opening  45  is complementarily formed by vertical jamb member  39 A such that replaceable jamb member  47  is fittably received in jamb opening  45  by horizontal jamb member  37 A. Projections  59 A and  59 B are shaped to fittably abut projections  40 A and  40 B, respectively, on vertical jamb member  39 A. More particularly, front surface  51  and front surface  61  form a continuous vertical surface along door jamb  35  when replaceable jamb member  47  is secured in jamb opening  45 . Surfaces  65 A,  67 A, and  69 A, on replaceable jamb member  47  abut surfaces  53 A,  55 A, and  57 A, on vertical jamb member  39 A, respectively. Likewise, surfaces  65 B,  67 B, and  69 B, on replaceable jamb member  47  abut surfaces  53 B,  55 B, and  57 B, on vertical jamb member  39 A, respectively. 
         [0031]    Door jamb  35  acts as a conventional door jamb when replaceable jamb member  47  is secured in jamb opening  45 . However, it is a primary feature of the present invention that when an effective amount of force is applied to door  3 , generally directed from the exterior of building  7  towards the interior, replaceable jamb member  47  is released from jamb opening  45 . Replaceable jamb member  47  is designed to receive the majority of the force, sliding out of jamb opening  45  to prevent the remaining door elements, in particular vertical jamb member  39 A, from incurring damage. 
         [0032]    Replaceable jamb member  47  is shown in an attached position in  FIG. 8 , and is shown in a breakaway position in  FIGS. 9 and 10 . In the attached position, replaceable jamb member  47  is fittably secured in jamb opening  45 , abutting first stud  29  of vertical frame member  27 A. Shear screws  83  extend through replaceable jamb member  47  and into first stud  29 . Optionally, shear screws  83  may further extend into second stud  33  (not shown). It is well known in the art that force is typically applied from the exterior of building  7  towards the interior, when attempting to break through a locked door. When a force is applied to door  3  from the exterior of building  7  towards the interior in the direction of Arrow A ( FIG. 9 ), the force is transferred through door  3  and knob bolt  88  into replaceable jamb member  47 . If the force is sufficient to overcome the resistance strength of shear screws  83 , shear screws  83  release replaceable jamb member  47  from first stud  29 . As replaceable jamb member  47  is no longer secured to first stud  29 , replaceable jamb member  47  slidably moves out of jamb opening  45  in response to the continuing force from knob bolt  88  as door  3  is forced open. Replaceable jamb member  47  thereby slidably moves out of jamb opening  45  and into the breakaway position separated from jamb opening  45  and vertical jamb member  39 A, as shown in  FIGS. 9 and 10 . 
         [0033]    As shown in  FIG. 9 , when a force is applied to door  3  in the direction of Arrow A, knob bolt  88  transfers this force into replaceable jamb member  47 , prying replaceable jamb member  47  out of jamb opening  45  in the direction of Arrow A. It is a primary feature of the present invention that shear screws  83  only extend through replaceable jamb member  47  and into first stud  29 , and optionally second stud  33 . Shear screws  83  do not extend through any part of vertical jamb member  39 A. This allows shear screws  83  to break or pull away from first stud  29  without causing damage to vertical jamb member  39 A as replaceable jamb member  47  is not secured to vertical jamb member  39 A. There exists only a simple surface to surface abutment relationship between replaceable jamb member  47  and vertical jamb member  39 A while replaceable jamb member  47  is in jamb opening  45 . Surfaces  65 A,  65 B,  67 A,  67 B,  69 A, and  69 B of replaceable jamb member  47  slide along surfaces  53 A,  53 B,  55 A,  55 B,  57 A, and  57 B, respectively, in the direction of Arrow A to allow replaceable jamb member  47  to slide out of jamb opening  45  after shear screws  83  break. Although replaceable jamb member  47  is shown having a general cross-sectional “T” shape, the present invention encompasses a replaceable jamb member having any shape that facilitates the sliding movement required to remove replaceable jamb member  47  from opening  45  without damaging the underlying elements of door jamb  35 . 
         [0034]    As shown in  FIG. 9 , replaceable jamb member  47  slides away from vertical jamb member  39 A, leaving the surfaces of vertical jamb member  39 A generally undamaged. Interior casing  75  is in the path of replaceable door jamb  47  as it moves in the direction of Arrow A. However, it is commonly known in the art to use finishing nails through interior casing  75  to secure interior casing  75  to vertical jamb member  39 A and drywall  15  such that when force is applied in the direction of Arrow A to door  3 , interior casing  75  is simply knocked off door jamb  35  and may be re-secured thereto when vertical jamb member  39 A is replaced. Interior casing  75  is typically undamaged in conventional door jamb systems when the door is broken in, and thus remains so in the present invention. 
         [0035]    It is a primary feature of the present invention to use a connection element to releasable secure replaceable jamb member  47  to vertical frame member  27 A within jamb opening  45 . In the preferred embodiment, this connection element is provided by shear screws  83  to secure replaceable jamb member  47  to vertical frame member  27 A. Shear screws  83  are hereby defined as breakable or releasable screws, bolts, or nails, having a particular resistance strength or force threshold, such that when the force threshold is overcome, shear screws  83  release their secure hold on the underlying element. One skilled in the art would immediately recognize that the force threshold in shear screws  83  should be generally equal to the resistance strength of a conventional door jamb system to provide a similar level of security. For example, if a conventional door jamb system requires at least one-hundred pounds per square inch of force on the door to break and splinter the doorjamb, thus opening the door, shear screws  83  would similarly require at least one-hundred pounds per square inch of force on door  3  to break shear screws  83  and release replaceable jamb member  47  from jamb opening  45 . An effective amount of force is hereby defined as the amount of force necessary to break down a conventional door generally formed having the same type of door jamb. Therefore, the effective force threshold of the shear screws is reached generally when a conventional door would splinter and give way, allowing entry into the building. 
         [0036]    Shear screws  83  are shown in  FIG. 9  shedding threads  78  when the effective force threshold is overcome. Threads  78  are secured to shaft  82  such that when a force having a sufficient magnitude is applied to shear screw  83 , threads  78  shear off shaft  82 , thereby allowing shaft  82  to slidingly disengage with first stud  29 . Similarly, shear screws  83  are shown in  FIG. 10  breaking into a first portion  89  and a second portion  92  when the force threshold is overcome. Although shear screws  83  are shown in  FIGS. 9 and 10  as having shedable threads or breakable portions, any method or mechanical element that facilitates releasing the secure connection between replaceable jamb member  47  and vertical frame member  27 A in response to the desired force threshold being overcome is encompassed by the present invention, including nails, bolts, or adhesive. 
         [0037]    As described above, shear screws  83  release replaceable jamb member  47  from jamb opening  45  and vertical frame member  27 A only when the desired force threshold is overcome. As such, replaceable door jamb system  1  provides the same level of security as conventional door systems. However, the time and financial cost of replacing a broken door is dramatically reduced. A maintenance person may keep multiple replacement jamb members  47  on hand, and even pre-drill the holes for deadbolt strike plate  85  and knob bolt strike plate  86 . When a door is broken, the old replaceable jamb member  47  and shear screws  83  are discarded, and a new replaceable jamb member  47  is simply inserted into jamb opening  45  and secured with a new set of shear screws  83 . 
         [0038]    Vertical jamb member  39  and replaceable jamb member  47  may be formed having any complementary shapes that facilitate the break-away novel aspect of replaceable door jamb system  1  as described herein above. As shown in  FIG. 11 , a second embodiment of the invention, namely a replaceable jamb system  101 , includes a vertical jamb member  39 A comprising two separate pieces, namely, a portion  138  and a portion  139 , wherein a jamb opening  145  extends entirely between portion  138  and portion  139 . A replaceable jamb member  147  is shaped to be fittably inserted into jamb opening  145 . In replaceable jamb member  147 , side surface  43  is eliminated and surfaces  53 ,  55 , and  57  extend fully to exterior surface  54 , thus jamb opening  145  is extended entirely through vertical jamb member  39 A. As discussed previously in the preferred embodiment, replaceable jamb member  147  moves out of jamb member  39 A in response to an effective amount of force on door  3 . 
         [0039]    It is also within the scope of replaceable door jamb system  1  that replaceable jamb member  47  may extend the entire vertical length of door frame  23 , generally from floor board  19  to horizontal frame member  25 . As such, it is a feature of the replaceable door jamb system  1  that replaceable jamb member  47  may be formed in any vertical length which fits within door opening  21 . Furthermore, as discussed above with respect to replaceable jamb system  101 , replaceable jamb member  147  may be formed in any horizontal width which fits within door opening  21 . As such, any feasible length and width of forming a replaceable jamb member is encompassed by the present invention. 
         [0040]    Replaceable door jamb system  1  is universally adaptable for use with substantially any door frame or door system, as replaceable jamb member  47  may receive any size or type of bolts or strike plates. The installer simply installs any locks, deadbolts, and plates which are desired or required by the door system, and thereby subsequently drills shear screws  83  through any unobstructed portion of replaceable jamb member  47  into first stud  29 . This allows the installer to customize replaceable door jamb system  1  for any door frame or system. 
         [0041]    Furthermore, the present invention encompasses retrofitting an existing door jamb to include replaceable jamb member  47 . To accomplish this, a building owner may simply cut out a replaceable jamb member from a standard vertical jamb member and then secure it through the door frame with shear screws  83  or any connection element encompassed by the present invention. To form a replaceable jamb member out of an existing vertical jamb member, a vertical cut may be applied along the door backstop area and intersected with two horizontal cuts, such that a replaceable jamb member and jamb opening is formed. 
         [0042]    Replacing replaceable jamb member  47  and a connection element such as shear screws  83  represent a fraction of the time and money cost of replacing an entire splinted door  3  or vertical jamb member  39 . Unlike conventional door systems, door  3  and vertical jamb member  39  are not splinted or broken by the breaking forces applied to door  3 . Thus, replaceable jamb member  47  is a sacrificial part, an analogue of the electric fuse, which prevents the more expensive and difficult to replace parts of replaceable door jamb system  1  from being damaged. 
         [0043]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0044]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.