Patent Publication Number: US-7219519-B1

Title: Cylinder housing for auxiliary lock

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a cylinder housing for an auxiliary lock. More particularly, the present invention relates to a cylinder housing for a cylinder of an auxiliary lock. The present invention also relates to an auxiliary lock with such a cylinder housing. 
   2. Description of the Related Art 
   U.S. Pat. No. 5,906,125 discloses an auxiliary lock comprising a ring having a central opening and a first flange received in a door bore-hole, a cylinder housing having a shoulder abutting the ring and a hollow protrusion extending into the central opening of the ring, the hollow protrusion having a flat outer wall, a trim enclosing over the cylinder housing, and a cylinder having a rear end received within the hollow protrusion of the cylinder housing and a shoulder abutting the trim, the flat outer wall of the protrusion being intimately interposed between the ring and the rear end of the cylinder. The cylinder housing and the trim are retained in a fixed relationship with respect to the door. The ring further includes a second flange, and a free end of the trim adjacent to the shoulder of the cylinder housing is situated between the shoulder of the cylinder housing and the second flange of the ring. The trim, when rotated by an external force, will rotate with respect to the ring but not drive the cylinder housing to rotate, therefore the auxiliary lock will not be damaged. 
   However, an intruder can still destroy the auxiliary lock by breaking the coupling section between the elements, such as the coupling section between the ring and the trim. The ring would no longer protect the cylinder after the elements are separated from one another after destruction. Further, the auxiliary lock of this type is complicated in structure and, thus, has a higher cost due to troublesome assembling. 
   SUMMARY OF THE INVENTION 
   In accordance with an aspect of the present invention, a cylinder housing is provided for a cylinder of an auxiliary lock. The cylinder housing comprises a longitudinal hole adapted for receiving a cylinder of an auxiliary lock. An annular flange is formed on an end of an outer circumference of the cylinder housing, leaving an annular end portion on the end of the cylinder housing. The cylinder housing is adapted to be mounted to an outer surface of a door having a bore-hole, with the end portion being in intimate contact with a circumferential surface delimiting the bore-hole of the door and with the annular flange intimately abutting against the outer surface of the door. 
   In accordance with another aspect of the invention, an auxiliary lock comprises a cylinder and a cylinder housing rotatably mounted around the cylinder, an annular flange being formed on an end of an outer circumference of the cylinder housing, leaving an annular end portion on the end of the cylinder housing. The cylinder housing is adapted to be mounted to an outer surface of a door having a bore-hole, with the end portion being in intimate contact with a circumferential surface delimiting the bore-hole of the door and with the annular flange intimately abutting against the outer surface of the door. 
   Preferably, the cylinder housing further comprises two annular stepped portions respectively formed on two ends of a circumferential wall delimiting the longitudinal hole of the cylinder housing. The cylinder further comprises two annular shoulders respectively abutting against the annular stepped portions of the cylinder housing. 
   Preferably, the cylinder is completely received in the cylinder housing. 
   Preferably, the end portion of the cylinder housing is tightly sandwiched between the end of the outer circumference of the cylinder and the circumferential surface delimiting the bore-hole of the door, enhancing anti-destruction effect. 
   After mounting the auxiliary lock on the door, damage to the cylinder would not be easy to achieve, as the cylinder is fittingly received in the cylinder housing. Further, it is not easy to clamp the cylinder housing with a pair of pliers or the like, as the end portion of the cylinder housing is received in the bore-hole of the door and as the cylinder housing is rotatably mounted around the cylinder. In a case that an intruder is intended to destroy the auxiliary lock by hammering the cylinder housing with a hammer or the like, the impact to the cylinder housing can be evenly released to the door, thereby reducing the destructive force. Further, since the first annular shoulder of the cylinder abuts against the annular first stepped portion of the cylinder housing and the second annular shoulder of the cylinder abuts against the annular second stepped portion of the cylinder housing, the cylinder housing is capable of withstanding outward pulling force applied by an intruder. 
   Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a portion of a door and an auxiliary lock in accordance with the present invention. 
       FIG. 2  is a perspective view of a cylinder housing of the auxiliary lock in accordance with the present invention. 
       FIG. 3  is a sectional view of the door and the auxiliary lock in accordance with the present invention after assembly. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1 through 3 , an auxiliary lock in accordance with the present invention comprises a cylinder  1  and a cylinder housing  8 . The cylinder  1  comprises a tailpiece  11  and mounted on an outer surface  93  of the door  9 . The cylinder housing  8  is also mounted on an outer surface  93  of the door  9  and receives the cylinder  1 . 
   The cylinder  1  includes a lock core  10  mounted therein. A first annular shoulder  12  is formed on an end of the circumference of the cylinder  1  that is distal to the door  9  after assembly. Further, a second annular shoulder  13  is formed on the other end of the circumference of the cylinder  1  that is adjacent to the door  9  after assembly. 
   In this example, the auxiliary lock further comprises a first engaging plate  5  fixed to an inner side  94  of the door  9 , a second engaging plate  6 , and a bolt mechanism  91 . The first engaging plate  5  and the second engaging plate  6  are securely fixed together and then securely fixed to the cylinder  1  by, e.g., extending two screws  7  through holes  62 ,  52 , and  15  respectively in the second engaging plate  6 , the first engaging plate  5 , and the cylinder  1 . A knob  61  is pivotally mounted to the second engaging plate  6  to allow manual locking or unlocking. 
   The bolt mechanism  91  comprises a retractor  911  mounted in an opening  92  in an edge face of the door  9  and a bolt  912  connected to the retractor  911 . The tailpiece  11  of the cylinder  1  is extended through a hole  913  in the retractor  911  and coupled to the knob  61 . When the knob  61  is turned or a key (not shown) is inserted into the lock core  10  and turned to actuate the tailpiece  11 , the retractor  911  is moved to retract or extend the bolt  912 , which is conventional. 
   Referring to  FIG. 2 , the cylinder housing  8  comprises a longitudinal hole  81  for receiving the cylinder  1 . Preferably, the cylinder  1  is completely received in the cylinder housing  8 . An annular, first, stepped portion  82  and an annular, second, stepped portion  83  are respectively formed on a first, front end and a rear, second end of a circumference wall delimiting the longitudinal hole  81 . When the cylinder  1  is mounted into the longitudinal hole  81  of the cylinder housing  8 , the first annular shoulder  12  of the cylinder  1  abuts against the annular, first, stepped portion  82  of the cylinder housing  8  and the second annular shoulder  13  of the cylinder  1  abuts against the annular, second, stepped portion  83  of the cylinder housing  8 , as shown in  FIG. 3 . The cylinder  1  is, thus, fittingly received in the cylinder housing  8 . 
   The cylinder housing  8  further comprises an annular flange  84  on a front end of an outer circumference of the cylinder housing  8 , leaving an annular end portion  85  on the front end of the cylinder housing  8 . The end portion  85  has an outer diameter substantially the same as or slightly smaller than a diameter of the bore-hole  90  of the door  9 . Thus, when the end portion  85  of the cylinder housing  8  is inserted into the bore-hole  90  of the door  9  for installation purposes, the end portion  85  is in intimate contact with a circumferential surface delimiting the bore-hole  90 , with the annular flange  84  abutting against the outer surface  93  of the door  9 . 
   Referring to  FIG. 3 , after mounting the auxiliary lock on the door  9 , the cylinder  1  is fittingly received in the cylinder housing  8  and fixedly engaged with the first and second engaging plates  5  and  6  by the screws  7 . Damage to the cylinder  1  would not be easy to achieve. Since the end portion  85  of the cylinder housing  8  is annular and received in the bore-hole  90  of the door  9 , the cylinder housing  8  is rotatably mounted around the cylinder  1 . Hence, it is not easy to clamp the cylinder housing  8  with a pair of pliers or the like. In a case that an intruder is intended to destroy the auxiliary lock by hammering the cylinder housing  8  with a hammer or the like, the impact to the cylinder housing  8  can be evenly released to the door  9 , thereby reducing the destructive force. Further, since the first annular shoulder  12  of the cylinder  1  abuts against the annular, first, stepped portion  82  of the cylinder housing  8  and the second annular shoulder  13  of the cylinder  1  abuts against the annular, second, stepped portion  83  of the cylinder housing  8 , the cylinder housing  8  is capable of withstanding outward pulling force applied by an intruder. 
   The end portion  85  of the cylinder housing  8  can be as long as possible without adversely affecting assembling/mounting of the bolt mechanism  91  of the auxiliary lock. As a result, the cylinder housing  8  can be firmly engaged on the outer surface  93  of the door  9 , with the cylinder  1  fittingly received in the cylinder housing  8  and with the end portion  85  tightly sandwiched between the front end of the outer circumference of the cylinder  1  and the circumferential surface delimiting the bore-hole  90  of the door  9 . The anti-destruction effect is enhanced. 
   It is noted that the first and second engaging plates  5  and  6  can be replaced with other structures, such as another set of cylinder  1  and cylinder housing  8  in accordance with the present invention. 
   Although specific embodiments have been illustrated and described, numerous modifications and variations are still possible without departing from the essence of the invention. The scope of the invention is limited by the accompanying claims.