Locking cap system

Abstract

A locking cap assembly is selectively locked into place within a tubular opening, such as the open end of a fire department connection. The locking cap assembly has an expandable element and a spreader element that is operatively connected to a locking bolt. As the locking bolt is rotated by a key, the spreader element is translated longitudinally through a tapered longitudinal bore in the expandable element, and the translation of the spreader element respectively expands and contracts the extendable element as the spreader element moves in the bore between first and second positions. The locking bolt includes a pair of cooperating lock washers having opposed cam surfaces, and a pair of opposed Bellville compression washers that apply axial pressure to the lock washers, allowing the locking bolt to be self locking during use for increased reliability and security.

What is claimed is:  
     
         1 . A locking cap assembly for an open pipe end having an interior wall surface, the assembly comprising: 
 an expandable plug element having a front surface, a rear surface and a peripheral surface, the expandable plug element having an unexpanded outside diameter that is sized to fit into the open pipe end;    a faceplate attached to the plug element and covering the front surface of the plug element, the faceplate having an exposed front surface;    a longitudinal bore extending through the expandable plug element;    a locking bolt having a bolt head exposed through the front surface of the faceplate, and a shank extending through the faceplate and through the bore;    a spreader element operatively connected to the shank of the locking bolt within the bore, whereby the rotation of the locking bolt in a first direction translates the spreader element longitudinally within the bore from a first position to a second position, and whereby the translation of the spreader element in the bore from the first position to the second position expands the expandable plug element into a locking engagement against the interior wall surface of the open pipe end;    a pressure plate carried on the locking bolt between the bolt head and the front surface of the plug element;    pair of co-engaged complementary lock washers carried on the locking bolt between the pressure plate and the bolt head; and    a compression element carried on the locking bolt between the pressure plate and the front surface of the plug element, the compression element being configured and located so as to apply axial pressure against the lock washers and the bolt head through the pressure plate.    
     
     
         2 . The locking cap assembly of  claim 1 , wherein the compression element comprises a pair of compression washers.  
     
     
         3 . The locking cap assembly of  claim 1 , wherein the shank of the locking bolt is threaded, and wherein the spreader element includes a taper nut threaded onto the shank.  
     
     
         4 . The locking cap assembly of  claim 1 , wherein the plug element includes an expansion slot extending longitudinally through the plug element, and radially inwardly from the periphery of the plug element so as to intersect the bore.  
     
     
         5 . The locking cap assembly of  claim 1 , wherein the spreader element is constrained from rotation with the bolt.  
     
     
         6 . The locking cap assembly of  claim 1 , wherein the plug element cooperatively engages the spreader element so as to constrain the spreader element from rotation with the bolt.  
     
     
         7 . The locking cap assembly of  claim 4 , wherein the shank of the locking bolt is threaded, and wherein the spreader element comprises: 
 a taper nut that is threaded onto the shank of the bolt; and    a lateral extension on the taper nut that is captured in the expansion slot.    
     
     
         8 . The locking cap assembly of  claim 1 , comprising a cap member having internal threads, wherein the cap member is held between the rear face of the faceplate and the front surface of the expandable plug element.  
     
     
         9 . The locking cap assembly of  claim 2 , wherein the pair of compression washers comprises an opposing pair of Bellville washers.  
     
     
         10 . The locking cap assembly of  claim 1 , wherein the expandable plug element includes a peripheral surface with a knurled portion, and wherein the knurled portion includes a pattern of saw tooth-shaped teeth that are configured to dig into the interior wall surface of the open pipe end when the expandable plug element is expanded to bring the knurled portion into contact with the interior wall surface of the pipe end.  
     
     
         11 . The locking cap assembly of  claim 10 , further comprising a cap member having internal threads; the cap member being held between the rear face of the face plate and the front surface of the expandable plug element.  
     
     
         12 . The locking cap of  claim 1 , wherein the rear face of the faceplate and the front surface of the expandable plug element are secured together, and wherein the plug element includes a peripheral surface with external threads formed therein.  
     
     
         13 . A locking cap assembly for an open pipe end having an interior wall surface, comprising: 
 a faceplate having a front face, a rear face and a peripheral edge;    an expandable plug element dimensioned for insertion into the open pipe end, the plug element having a front surface, a rear surface and a peripheral surface;    a slot formed in the expandable plug element and extending longitudinally between the front surface and the rear surface, and radially inwardly from the peripheral surface;    a tapered bore formed in the expandable plug element extending longitudinally between the front surface and the rear surface and intersecting the slot;    a taper nut held in the tapered bore and including a threaded opening and a lateral extension captured in the slot;    wherein the faceplate and the expandable plug element are secured together with a cylindrical cap member held between the rear face of the faceplate and the front surface of the plug element; and    wherein the cylindrical cap member has a side wall surrounding an end plate, and threads formed in the side wall;    a locking bolt having a head and a threaded shank; the head being seated in an opening formed through the faceplate and the threaded shank extending through the cylindrical cap member and the tapered bore and into the threaded opening of the taper nut for longitudinal translation of the taper nut between the front surface and the rear surface upon rotation of the locking bolt; and    a compression mechanism carried on the locking bolt in the opening in the faceplate, between the head of the locking bolt and the end plate, for self-locking of the locking bolt.    
     
     
         14 . The locking cap assembly of  claim 13  wherein the compression mechanism comprises: 
 a pair of co-engaged complementary lock washers having adjacent the bolt head; and  
 a pair of opposing compression washers between the lock washers and the end plate.  
 
     
     
         15 . The locking cap assembly of  claim 14 , further comprising a pressure plate carried on the bolt shank between the pair of lock washers and the opposing pair of compression washers.  
     
     
         16 . The locking cap assembly of  claim 15 , wherein the pressure plate is constrained from rotation relative to the bolt shank.  
     
     
         17 . The locking cap assembly of  claim 13 , wherein the plug element includes a knurled portion formed on the peripheral surface, whereby, when the plug element is expanded by translation of the taper nut in the bore, the knurled portion is brought into contact with the interior wall surface of the pipe end.  
     
     
         18 . The locking cap assembly of  claim 17  wherein the knurled portion includes a plurality of saw tooth-shaped teeth configured for digging into the interior wall surface of the pipe end.  
     
     
         19 . A locking cap assembly for an open pipe end having an interior wall surface, comprising: 
 a faceplate having a front face, a rear face and a peripheral edge;    an expandable plug element dimensioned for insertion into the open pipe end having a front surface, a rear surface and a peripheral surface;    a slot formed in the expandable plug element and extending longitudinally between the front surface and the rear surface, and radially inwardly from the peripheral surface;    a tapered longitudinal bore formed through the expandable plug, the bore extending longitudinally between the front surface and the rear surface and intersecting the slot;    a taper nut held in the bore for longitudinal translation therein between first and second positions, and including a threaded opening and a lateral extension captured in the slot;    the faceplate and the expandable plug element being secured together with the rear face of the faceplate and the front surface of the expandable plug element being held together;    a locking bolt having a head and a threaded shank; the head being held in an opening formed between the front face and the rear face of the faceplate, and the threaded shank extending through the tapered bore into the threaded opening of the taper nut for longitudinal translation of the taper nut between the front surface and the rear surface of the plug element in response to rotation of the locking bolt;    a pair of co-engaged complementary lock washers carried on the locking bolt shank in the opening in the faceplate, one of the lock washers being in contact with the head of the locking bolt; and    a compression element carried on the shank of the locking bolt between the lock washers and the front surface of the plug element, the compression element being located and configured to apply axial pressure against the lock washers.    
     
     
         20 . The locking cap assembly of  claim 19  wherein the each of the lock washers has a first surface with a circumferential array of inclined cams, and a second surface with an array of radial teeth, wherein the lock washers are arranged on the shank of the locking bolt with the cams on their respective first surfaces co-engaged.  
     
     
         21 . The locking cap assembly of  claim 19 , wherein the compression element comprises an opposed pair of compression washers arranged between the lock washers and the front surface of the plug element.  
     
     
         22 . The locking cap assembly of  claim 20 , further comprising a pressure plate held on the shank of the locking bolt between the pair of lock washers and the opposed pair of compression washers.  
     
     
         23 . The locking cap assembly of  claim 21 , wherein the compression washers are Bellville washers.