Abstract:
A bolt seal provides a slidable sleeve surrounding a solid bolt body having a bolt head affixed at one end. The sleeve is held in abutting contact with the bolt head at one end of the sleeve and a shoulder comprising an enlarged diameter portion of the solid bolt body at the other end of the sleeve. The bolt head can therefore be pressed snug against a seal housing, thereby eliminating a mode of jimmying the seal, while simultaneously providing a means for opening the seal with bolt cutters when the seal must be opened.

Description:
This application claims the benefit of provisional application Ser. No. 60/215,327, filed Jul. 3, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of bolts seals and, more particularly, to a sleeved bolt and seal construction which avoids some modes of defeating the seal function without detection. 
     BACKGROUND OF THE INVENTION 
     Door closures and locks are often provided with a bolt and seal mechanism to stop intruders from jimmying the lock. Such a closure may comprise a hasp on a cargo door of a truck, for example, or other application. When a such a closure is jimmied, the intruder frequently will try to find a way of opening the closure without leaving evidence of the intrusion. Such mechanisms typically include a body, larger in diameter than the bolt, which attaches to or is integrally formed with the bolt on the end of the bolt opposite the bolt head. The bolt attaches to the interior of the body with a snap ring to provide an enlarged region on either side of the closure hasp to lock the closure. Other bolt seals may include a grip mechanism to prevent retraction of the bolt from the device in the direction opposite its insertion, such as that shown and described in U.S. Pat. No. 4,681,356 directed to cables, but equally adaptable to bolts. 
     To open the closure, the bolt must be cut with bolt cutters. Consequently, the length of the bolt between the bolt head and the body of the seal means must be longer than the thickness of the hasp in order to provide room for the bolt cutters to access and sever the bolt. And, if there is enough room for bolt cutters to gain access, then there is enough room for a jimmying tool to defeat the mechanism inside the body and thereby open the seal without leaving any evidence of intrusion. The jimmying tool is inserted between the bolt and the hasp and further into the wedge mechanism holding the bolt so that the body slides easily off the bolt, leaving no evidence that the mechanism has been defeated. 
     Thus, there remains a need for a bolt seal which eliminates the space between the bolt head and the hasp or closure, to prevent tampering with the seal mechanism. Such a bolt seal should be simple and inexpensive to manufacture, yet defeat the previously described modes of opening the closure without leaving evidence that the closure has been opened. 
     SUMMARY OF THE INVENTION 
     The present invention addresses these and other needs in the art by providing a bolt seal and lock mechanism equipped with a bolt gripping mechanism that is not easily defeated. The bolt seal provides a slidable sleeve surrounding a solid bolt body having a bolt head affixed at one end. The sleeve is held in abutting contact with the bolt head at one end of the sleeve and a shoulder comprising an enlarged diameter portion of the solid bolt body at the other end of the sleeve. In this first preferred embodiment, the bolt and seal form a polygon in cross-section to prevent rotation. The bolt head can therefore be pressed snug against a seal housing, thereby eliminating a mode of jimmying the seal, while simultaneously providing a means for opening the seal with bolt cutters when the seal must be opened. 
     The bolt body and sleeve, which make up the bolt, penetrate the housing in one direction, but a jam lock mechanism prevents motion of the bolt in the other direction. The jam lock mechanism includes a roller which rides on a ramp liner and is biased with a spring. The materials of the ramp liner, roller, sleeve, and bolt body are selected of various hardnesses to prevent opening the lock seal under force, as with a crow bar. 
     In another preferred embodiment of the lock seal, the bolt penetrates a rotatable body within the housing, and the bolt is preferably circular in cross section. The rotatable body includes a pair of jam lock mechanisms to hold the bolt stationary relative to the rotatable body and the housing. 
     These and other features of the present invention will be apparent to those skilled in the art from a review of the following detailed description along with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features, advantages, and objects of the present invention are attained and can be understood in detail, more particular description of the invention maybe had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may add to other equally effective embodiments. 
     FIG. 1 is a side view in partial section of a prior art bolt seal. 
     FIG. 2 is a side view in partial section of a prior art cable seal. 
     FIG. 3 is a side section view of the bolt seal of the present invention. 
     FIG. 4 is a front section view of the bolt seal of the invention. 
     FIG. 5 is a top view of the bolt seal of the invention taken along view lines  5 — 5  of FIG.  3 . 
     FIG. 6 is a top section view of the bolt seal of the invention taken along view ones  6 — 6  of FIG.  3 . 
     FIG. 7 is a bottom view of the bolt seal of the invention taken along view lines  7 — 7  of FIG.  3 . 
     FIG. 8 is a bottom view of the bolt seal of the invention taken along view lines  8 — 8  of FIG.  3 . 
     FIG. 9 is a side section view of the bolt seal of the invention, illustrating the bolt head snug against the hasp which it is locking. 
     FIG. 10 is a side section view of the bolt seal of the invention, illustrating the first step in removing the bolt seal. 
     FIG. 11 is a side section view of the bolt seal of the invention, illustrating the second step in removing the bolt seal with the bolt being removed and the bolt sleeve still in place. 
     FIG. 12 is a side section view showing the step of removing the bolt sleeve. 
     FIG. 13 is a side section view of an alternative preferred embodiment of the bolt lock of the present invention. 
     FIG. 14 is a top section view of the alternative preferred embodiment taken along section lines  14 — 14  of FIG.  13 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Structure of a First Preferred Embodiment of the Invention 
     FIG. 1 depicts a known bolt lock  10 . The bolt lock  10  comprises a bolt  12  of predetermined length and a seal body or housing  14  joined to the bolt  12  with a snap ring  16 . The bolt  12  is fitted through a hasp  18 , shown in phantom in FIG. 1, which defines a thickness T. Thus, the predetermined length of the bolt leaves a distance D between hasp  18  and a bolt head  22 . The distance D is necessary to provide access for the blades  20  of a bolt cutter when the lock  10  must be removed. Unfortunately, the distance D also provides plenty of room for the insertion of a “slim jim” tool, if someone should try to defeat the lock without leaving evidence of such intrusion. 
     FIG. 2 depicts a known cable lock  30  which serves the same purpose as the bolt lock  10 . In the case of the cable lock  30 , the length of exposed cable between a lock housing  32  and a cable head  34  is adjustable according to the total thickness of the door hasp  18 . However, ample space D once again must be left for the blades for the bolt cutter (FIG.  1 ), when the lock must be removed, providing the same opportunity for the insertion of a defeating “slim jim” tool. 
     FIG. 3 depicts a bolt lock  40  of the present invention which addresses these and other drawbacks in the known locks just described. As shown in FIG. 3, a bolt  42  extends through a lock housing  44 . The bolt  42  comprises three principal components, an inner polygonal and preferably hexagonal solid bolt body  46 , an outer bolt sleeve  48 , and a bolt head  50 . The bolt body  46 , preferably made of steel, is slidably held inside the sleeve  48 , which is preferably made of aluminum. The sleeve is also polygonal and preferably hexagonal and is prevented from sliding off the bolt by a widened head  52  of the bolt outside the lock housing  44 . At the other end of the bolt  42 , the sleeve  48  and the head  50  are in abutting contact at an abutment  54 . 
     As previously described, the bolt body  46  is hexagonal in cross section, which makes twisting the bolt relative to the housing  44  impossible. This feature is provided because twisting the bolt within the housing is the first thing an intruder would try when attempting to get the bolt out of the housing. The bolt body  46  at its lower end defines a head  56  which connects the bolt body  46  to the head  50 , which is preferably made of a soft material such as zinc. The housing  44  is preferably a zinc injection part with a hexagonal passage  58  to receive the bolt. 
     The housing  44  further includes an angled ramp  60  which is lined with a liner  62 . Between the liner  62  and the sleeve  48  is a suspended roller  64  which is urged downward by a spring  66 . The roller  64  is preferably made of hardened steel. It is therefore possible to move the bolt  42  upward into the housing  44  but any attempted movement retracting the bolt downward out of the housing jams the disc  64  ever tighter between the liner  62  and the bolt sleeve  48 , thus preventing the removal of the bolt from the housing. If an intruder tries to open the lock by force, for example by applying a crow bar, the roller  64  will be forced to bite through the aluminum sleeve  48  and into the steel bolt body  46 . Therefore, the roller  64  must be harder than the bolt body  46 , or the roller  64  would be deformed by such action before it could make an indentation in the bolt body  46  and the entire bolt would start to slip, eventually all the way out of the housing  44 . It is also important that the roller not indent the ramp, which is preferably made of zinc, which is softer than the steel of the roller. Thus, the ramp is lined with the liner  62 , which is made of a material which is at least as hard as the roller. If the roller  64  digs into the ramp or the liner, the bolt  42  may slip through the housing under high load, thus defeating the lock. 
     FIG. 4 provide a side view of the bolt lock  40 . The spring  66  extends to a hook  68  which penetrates a central hole  70  in the roller  64 . This holds the roller suspended in approximately the middle of a slot  72  formed in the housing  44 . Thus, the spring  66  is held in place by a cap  74  which is joined to the housing  44  and forms a portion of the housing. The spring  66  is retained by the cap  74  by an extension  76  which fits into a hole or pocket  78  in the housing. This prevents the roller from falling down to the bottom of the slot  72  and out the passage  58  before the bolt is inserted through the housing. The roller might fall through the passage  58  because the roller is small in diameter relative to the diameter of bolt  42 . The spring  66  also includes a vertical arm  80  to extend between the coiled portion of the spring and the hook  68 , and the housing thus defines a cavity  82  to accommodate the vertical arm  80 . As shown in FIG. 6, the cavity  82  may be formed in circular cross section. 
     FIG. 3 includes section symbols  5 — 5 ,  6 — 6 ,  7 — 7 , and  8 — 8 , corresponding to FIGS. 5,  6 ,  7 , and  8 , respectively. As shown in FIG. 5, the cap  74  covers the top of the housing  44 , to seal the housing and form a portion thereof. The bolt, comprising the bolt body  46  and sleeve  48 , penetrates the passage  58 , which extends through te cap. The bolt body and sleeve are preferably hexagonal, but any appropriate polygonal shape will do, so long as a flat side of the sleeve provides adequate surface area for the roller to ride upon. 
     FIG. 6 provides a section view through the roller  64 . The hook  68  extends into the roller, which is positioned between the ramp liner  62  and the sleeve  48 . FIG. 7 shows the bolt body and sleeve extending through the passage  58  in the housing. FIG. 8 shows the bolt head  50  which is fixedly joined to the head  58  extending below the housing. The head  56  is preferably made as an integral part of the bolt body  46  and is thus made of steel, and the bolt head  50  is preferably formed of zinc. Note that in each of FIGS. 5-8, the housing  44  is shown having a racetrack sectional configuration, but any appropriate sectional configuration will suffice. 
     Operation of the Invention 
     FIGS. 9 through 12 inclusive illustrate the steps of the operation of the invention. FIG. 9 shows the lock  40  installed on a typical container door hasp  18  or the like. The bolt head  50  is positioned snug against one side of the hasp  18 , and the housing  44  is positioned snug against the opposite side of the hasp. Thus, there is no space between the bolt head and the hasp for the insertion of the jimmying tool, which otherwise could be inserted through the hasp along the bolt and up into the housing, thereby forcing the roller up and out of contact with the bolt, thereby permitting the bolt to be slipped from the housing. 
     When it is time to open the lock  40 , the bolt  42  may be severed with a bolt cutter anywhere above the housing  44  and below the widened head  52  of the bolt, as shown in FIG.  10 . Then, as shown in FIG. 11, the bolt body  46  slides out of the sleeve  48  since the widened head of the bolt has been removed. The sleeve and housing combination is then removed from the hasp  18 , and the sleeve is removed from the housing  44 , as shown in FIG.  11 . The bolt body and sleeve are then discarded, since they are cheap, expendable items and have been severed, but the more expensive housing and internal mechanism can be reused. 
     Structure of Another Preferred Embodiment of the Invention 
     FIGS. 13 and 14 depict an alternative design of a bolt lock  90  of the invention. The bolt lock  90  includes a bolt  92  comprising a bolt body  94  and a sleeve  96 , in this embodiment of circular cross section. These components can thus be made of less expensive stock material than the embodiment of FIGS. 3-12. The bolt body  94  is fixedly joined to the bolt head  50  as previously described. The bolt lock  90  further comprises a housing  98  sealed with a housing cover  100 . Inside the housing  98  is a freely rotatable lock body  102 , and the housing  98  and lock body  102  are also preferably circular in cross section, as shown in FIG.  14 . The lock body  102  is provided with a pair of slots  72 , identical in all respects to the slot  72  of FIG.  3 . The slots  72  are covered over with a lock body cap  104 , which also retains a pair of springs  66 . The housing  98  includes a conical opening  106  at the bottom and a conical opening  108  at the top. Similarly, the lock body  102  includes a conical opening  110  at the bottom, and the lock body cap  104  includes a conical opening  112 . The conical openings are provided for the ease of insertion of the bolt  92 . 
     As previously described, the lock body  102  freely rotates with the housing  98 . This prevents the rotation of the bolt relative to the lock body, which may serve to defeat the seal lock. This design finds inspiration in my U.S. Pat. No. 6,155,617. The dual roller design enhances the load carrying capability of the lock, thus making the design more resistant to being forced, as by a crow bar. The materials of construction and the mode of opening the lock as the same as previously described. 
     Returning briefly to FIG. 3, as previously described, the bolt body  42  includes an enlarged bolt head  52 . In the embodiment of FIG. 3, the enlarged bolt head  52  is preferably made by machining a cylindrical groove  120  into the bolt body, which is made of a polygonal stock material of uniform diameter. A hole  122  is drilled or otherwise formed in the end of the bolt body, and an enlarging tool (not shown) is forced down into the hole  122 . This enlarges the diameter of the bolt body, thus forming the enlarged bolt head  52 , and further develops a shoulder  124  for abutting contact with the sleeve  48 . The enlarging tool is then removed. 
     In the embodiment of FIG. 13, the enlarged head  52  is formed in a slightly different way. In this case, a steel ball  126  is jammed down into the hole  122  and left there, thus forming the enlarged bolt head  52  and the shoulder  124 . The techniques for forming the enlarged bolt head  52  were developed because in assembling the bolt body and sleeve combination, the sleeve is slid around the bolt body down to abutting contact at the abutment  54 , and then the enlarged head  52  is formed to hold the sleeve in place on the bolt body. 
     It is worth noting that the enlarged head is formed because the outer sleeve is preferably aluminum and the bolt body is preferably steel, and these dissimilar metals are difficult to join together. If the outer sleeve and bolt body are made of materials which can be welded, soldered, or brazed together, then the enlarged head can be eliminated. 
     The principles, preferred embodiments, and mode of operation of the present invention have been described in the foregoing specification. This invention is not to be construed as limited to the particular forms disclosed, since these are regarded as illustrative rather than restrictive. Moreover, variations and changes may be made by those skilled in the art without departing from the spirit of the invention.