Abstract:
A self-locking wire seal includes a body in which one end of a wire is fixedly secured. The free end of the wire can be inserted through the hasp of a lock. The free end of the wire is then inserted through a channel in the body of the seal. The wire contacts a locking mechanism which automatically prevents the retraction of the wire out of the channel defined in the body. The locking mechanism may comprise a spring which engages notches defined on the wire. The notches may be defined by using a concentrically laid spiral wound wire. The spring flexes out of the way of these notches when inserted, but grips the wire when attempts are made to retract the wire from the body of the seal.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to tamper-evident seals, and more particularly to wire seals. 
     Prior art locking seals generally come in two types: strap seals and wire seals. Strap seals generally include a flat, typically plastic or metal strap which is inserted through the hasp of a lock. The strap end is then inserted into the seal body where it cannot be removed. An example of such a strap seal is disclosed in U.S. Pat. No. 5,513,421 issued to Wells. One of the disadvantages of strap seals is that the strap has a relatively large dimension, as compared to a wire. The strap typically is flat and includes a pair of broadly planar surfaces. Such seals cannot be used in locks having hasps of a relatively narrow aperture. Such locks require the use of a seal having a wire or other relatively narrow, elongated member. 
     Prior art wire seals, however, have suffered from the disadvantage that they require multiple steps to use. For example, one prior art wire seal is disclosed in U.S. Pat. No. 5,402,958 issued to Mahaney. The wire seal disclosed therein first requires the wire to be inserted into an aperture defined in the seal. After this a plug must be rotated in the seal. The use of the seal thus requires two steps: insertion and rotation. Another such example is U.S. Pat. No. 5,762,386 issued to Fuehrer. This patent discloses a tamper resistant seal in which a wire must first be wrapped around an insert. The insert is then inserted into a receptacle from which it cannot be removed. Not only does this require multiple steps, but maintaining the wire around the insert while simultaneously inserting it into the receptacle requires a certain amount of dexterity and coordination. 
     The desirability can therefore be seen of a self-locking wire seal which is simple to use and which eliminates the multi-step requirements of prior art wire seals. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a self-locking wire seal which can be operated with only a single step. The seal is both easy to use and economical to manufacture and provides all the benefits associated with prior art wire seals. 
     A self-locking wire seal according to one aspect of the present invention includes a body and a spiral wound wire which has a first end secured to the body. A channel is defined in the body and is sufficiently large to receive a second end of the spiral wound wire. A lock is positioned inside of the body adjacent the channel and is adapted to contact the spiral wound wire when it is inserted in the channel. The lock allows the wire to be inserted but not retracted from the channel. 
     According to another aspect of the present invention, a self-locking seal includes a body, a flexible, elongated member, and a channel defined in the body. An interior space is also defined in the body and in communication with the channel. A spring is housed in the interior space of the body. The spring includes a sidewall, a base wall, and a flexible arm. The sidewall is oriented generally parallel to the channel while the base wall is oriented generally perpendicular to the channel. The flexible arm is oriented at an angle with respect to the base wall and extends partially into the channel. The base wall includes an aperture in alignment with the channel. When the flexible, elongated member is inserted through the channel and the aperture, it is prevented from being removed from the channel by the flexible arm of the spring. 
     According to another aspect of the present invention, a self-locking seal includes a body having a plurality of sides. The body includes a first channel and a second channel. The first channel extends out of one of the plurality of sides of the body while the second channel extends through said body from one side to an opposite side of the body. A chamber is also defined in the body and is in communication with the first channel. A slug is provided and is dimensioned to fit within the chamber. A wire is secured to the slug and extends out of the body through the first channel. A spring is housed within the body and extends at least partially into the second channel. The spring is flexible enough to be pushed out of the channel when the wire is inserted into the second channel in a first direction. The spring is also oriented at an angle in the second channel such that the spring grips the wire when the wire is retracted in the second channel in a second direction opposite the first direction. 
     According to yet another aspect of the invention, a method of sealing an object having an opening includes providing a seal body having a metal wire secured thereto. The metal wire has a free end which is unsecured to the seal body. A channel is defined within the body and a flexible spring is provided within the body. The flexible spring extends at least partially into the channel and is oriented to grip the metal wire when the metal wire moves through the channel in a first direction. The flexible spring flexes out of the way of the metal wire when the wire is moved through a channel in a second direction opposite said first direction. The free end of the metal wire is inserted through the opening in the object and subsequently inserted until the free end moves past the flexible spring. 
    
    
     In use, the self-locking wire seal of the present invention involves only the single step of inserting the wire into a channel in the body. The insertion of the wire self locks the wire in the channel of the body. No extra steps of twisting or inserting are required. These and other benefits, results and objects of the present invention will be apparent to one skilled in the art, in light of the following specification when read in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded, perspective view of a self-locking wire seal according to a first embodiment of the present invention; 
     FIG. 2 is a plan view of the first embodiment of the self-locking wire seal shown with a first half of the body removed and the wire inserted into the seal; 
     FIG. 3 is a perspective view of the first half of the self-locking wire seal; 
     FIG. 4 is a plan view of the first half depicted in FIG. 3; 
     FIG. 5 is a sectional view of the first half of the seal taken along the line V—V of FIG. 4; 
     FIG. 6 is a sectional view taken along the line VI—VI of FIG. 4; 
     FIG. 7 is a perspective view of a second half of the first embodiment of the wire seal; 
     FIG. 8 is a plan view of the second half of the wire seal of FIG. 7; 
     FIG. 9 is a sectional view taken along the line IX—IX of FIG. 8; 
     FIG. 10 is a sectional view taken along the line X—X of FIG. 8; 
     FIG. 11 is a perspective view of a spring; 
     FIG. 12 is an elevational view of the spring of FIG. 11; 
     FIG. 13 is a perspective view of a slug; 
     FIG. 14 is an elevational, sectional view of the slug of FIG. 13; 
     FIG. 15 is a perspective view of a concentrically laid, spiral wound wire; 
     FIG. 16 is a perspective view of the assembled first embodiment of the wire seal; and 
     FIG. 17 is a first half of a wire seal according to a second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described with reference to the accompanying drawings wherein like reference numerals correspond to like elements in the several drawings. A self-locking wire seal  20  is depicted in FIG. 1 in unassembled form. Self-locking wire seal  20  includes a body  22  having a first and second half  24  and  26 , respectively. A lock  28 , which in this case comprises a spring  30 , is housed between first and second halves  24  and  26  of body  22 . A spiral wound wire  32  is secured at a first end  34  to a slug  36 . Slug  36  is sandwiched between first and second halves  24  and  26  of body  22 . Slug  36  retains first end  34  of spiral wound wire  32  in body  22 . When seal  20  is to be used, a second, free end  38  of wire  32  is inserted into a channel  40  defined in body  22 . Channel  40  intersects a portion of spring  30  and is generally aligned with an aperture  42  defined in spring  30 . During the manufacturing process, first and second halves  24  and  26  are secured together and enclose spring  30  and slug  36 . In order to operate self-locking wire seal  20 , second end  38  of wire  32  is inserted into channel  40  past spring  30 . When wire  32  first contacts a flexible arm  44  of spring  30 , flexible arm  44  is moved out of the way of wire  32 . Wire  32  can therefore be inserted past flexible arm  44 . Wire  32 , however, cannot be retracted out of channel  40  because of the gripping of wire  32  by flexible arm  44 . Specifically, flexible arm  44  fits under an edge of the spiral windings of spiral wound wire  32 . The spiral winding contacts flexible arm  44  and prevents wire  32  from being retracted. In this way, seal  20  is self-locking and only requires the insertion of wire  32  into channel  40 . 
     First half  24  of body  22  is preferably made of plastic, although other materials could be used. First half  24  includes a first side  46  and second side  48 . First half  24  further includes three channel-defining protrusions (FIGS.  1 - 6 ). The first and second channel protrusions  50  partially define first channel  40  in body  22  (see FIGS.  1  and  2 ). A third channel protrusion  54  partially defines a second channel  56  in body  22  and is, in the current embodiment, oriented generally parallel to first channel  40 . As can be seen, first channel  40  extends from first side  46  to second side  48  of first half  24 . Second channel  56  extends into the interior of first half  24 , but does not extend completely through first half  24 . Protrusions  50  and  54  include a generally semi-circular surface  58  which is positioned along corresponding semi-circular surfaces on second half  26  to thereby define first and second channels  40  and  56 . Wire  32  fits through first and second channels  40  and  56 . As shown in FIG. 3, first channel protrusion  50  includes a sloped surface  60 . When spiral wound wire is inserted into first channel  40 , it is inserted through first side  46  of body  22 . It passes through the portion of first channel  40  defined by second channel protrusion  50 . It then passes through a trapezoidal space  82  where lock  28  is positioned. Finally, it passes into the portion of first channel  40  defined by first channel protrusion  50 . Sloped surface  60  helps ensure that wire  32  is properly guided into the portion of first channel  40  defined by first channel protrusion  50 . Thereafter, wire  32  exits out of second side  48  of body  22 . 
     First half  24  further includes a trapezoidal block  64  which is defined generally between first and second channel protrusions  50 . Trapezoidal block  64  fits into the interior space  66  of spring  30  (see FIGS.  11 - 12 ). Trapezoidal block is dimensioned somewhat smaller than interior space  66  to allow a certain degree of flexing of flexible arm  44  of spring  30 . Trapezoidal block  64 , however, limits the flexing of flexible arm  44  toward a base wall  68  of spring  30 . Trapezoidal block  64  locates base wall  68  of spring  30 , and prevents base wall  68  from moving upon insertion of wire  32 . A block extension  70  is defined adjacent trapezoidal block  64  and helps guide wire  32  through first channel  40 . 
     First half  24  further includes six circular bonding areas  72 . Bonding areas  72  project outwardly from first half  24  body  22 . Bonding area  72  are used in securing first half  24  to second half  26  of body  22 . While a wide variety of different methods can be used to secure these two halves together, in the current embodiment, first and second halves  24  and  26  are ultrasonically welded together. 
     FIGS. 7-10 depict second half  26  of body  22 . As can be seen in FIGS. 7 and 8, second half  26  includes six bonding depressions  74  which receive the bonding protrusions  72  on first half  24 . Second half  26  further includes recesses  76  and  78  which receive first, second, and third channel protrusions  50  and  54  from first half  24 . Recesses  76  and  78  include a semicircular surface  80  which aligns with semicircular surface  58  when first and second halves  24  and  26  are secured together. When semicircular surfaces  80  and  58  abut each other, they define first and second channels  40  and  56 . Second half  26  further includes a trapezoidal recess  82  which accommodates spring  30 . An angled portion  52  (FIGS. 8 and 10) of semicircular surface  80  is located adjacent trapezoidal recess  82  and helps guide wire  32  into channel  40  after it is threaded past spring  30 . Trapezoidal recess  82  includes an angled wall  84  which has a greater angle than the unflexed angle of flexible arm  44  of spring  30 . When spring  30  is inserted into trapezoidal recess  82 , a space is therefore created between angled wall  84  and flexible arm  44 . The space allows flexible arm  44  to flex out of the way of wire  32  when it is inserted into first channel  40 . 
     Second half  26  further includes a slug recess  86  positioned toward the end of second channel  56 . Slug recess  86  is dimensioned to accommodate slug  36  (FIGS. 1,  13 , and  14 ) that is fixedly secured to first end  34  of spiral wound wire  32 . Slug  36  secures first end  34  of wire  32  internally in body  22  of seal  20 . 
     Spring  30  includes, in addition to flexible arm  44 , base wall  68  and sidewall  92 . Base wall  68  and sidewall  92  are oriented generally perpendicular to each other (FIGS.  11  and  12 ). Flexible arm  44  extends at an angle from base wall  68  toward sidewall  92 . Flexible arm  44 , however, does not reach entirely to sidewall  92 , but instead terminates adjacent thereto and defines a gap  94  between sidewall  92  and flexible arm  44 . Gap  94  is where wire  32  fits when inserted into seal  20 . 
     Slug  36  is depicted in FIGS. 13 and 14 and is attached by any conventional means to first end  34  of wire  32 . Slug  36  is made of metal in the current embodiment, but could be made of any suitable material. Slug  36  prevents first end  34  of wire  32  from being removed from the body  22  of wire seal  20 . 
     A section of spiral wound wire  32  is depicted in FIG.  15 . Spiral wound wire  32  is a conventional wire that is commercially available from a variety of sources. In the current embodiment, spiral wound wire is a concentrically laid stainless steel wire that has eight wrappings per inch of wire. Of course it will be understood that different numbers of wrappings per inch can be used within the scope of the invention. The spiral wrapping on wire  32  provides a series of notches which engage an edge  96  of spring  30  and thereby prevent wire  32  from being retracted out of seal  20 . In the current embodiment, the main wire of spiral wound wire  32  has a diameter of 0.019 inches, while the spiral wire has a diameter of 0.016 inches. Wires with other dimensions can of course be used. During the course of manufacture, the ends the wire are fused together, i.e., welded. This welding of the two wire elements allows a rounded finish which eases insertion and serves to keep the assembly together under physical stress. The terminal weld also serves to indicate that the seal is as it came from the factory. A cut, sharp end would indicate the possibility of tampering. 
     FIG. 16 depicts an assembled self-locking wire seal  20  according to one embodiment of the current invention. Prior to use, second end  38  of wire  32  is not inserted into second channel  56  of body  22 . When used, second end  38  of wire  32  is first inserted through the hasp of the lock, or other looping structure, which is desired to be secured. Second end  38  of wire  32  is then inserted into second channel  56  past spring  30 . Once wire  32  is inserted past spring  32 , the spiral wound nature of wire  32 , in combination with edge  96  of flexible arm  44 , prevents wire  32  from being retracted out of the body of the seal. Typically wire  32  is inserted fully into second channel  56  until the loop formed by wire  32  is as small as possible. In this manner, any tampering with the lock secured by seal  20  is detectable. If the loop is left too large, then it is possible to cut wire  32  and reinsert the cut end into second channel  56  and thereby avoid detection of tampering. 
     FIG. 17 depicts a first half  24 ′ according to a second embodiment of the present invention. First half  24 ′ differs from the first embodiment in that it includes an elongated section or tag  98 . First half  24 ′ is joined to a second half that is the same as second half  26  of the first embodiment. When joined together, the seal  20 ′ operates in the same manner as seal  20  of the first embodiment. Tag  98  of first half  24 ′ provides a highly visible area for stamping a unique serial number associated with the particular seal. In this way, a seal cannot simply be cut and replaced with another seal without being detected. Such a serial number can also be stamped onto first half  24 , although it does not have as highly a visible section as elongated section  98 . 
     While the present invention has been described in terms of the preferred embodiments discussed in the above specification, it will be understood by one skilled in the art that the present invention is not limited to these particular preferred embodiments, but includes any and all such modifications which are in the spirit and scope of the present invention as defined in the appended claims.