Patent Publication Number: US-7708177-B2

Title: Powder-actuated fastener-driving tool

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority of Taiwanese Application No. 096149889, filed on Dec. 25, 2007. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a fastener-driving tool, more particularly to a powder-actuated fastener-driving tool. 
   2. Description of the Related Art 
   Referring to  FIGS. 1 to 3 , a conventional powder-actuated fastener-driving gun  1  is shown to include a housing  11 , a barrel unit  12 , a piston assembly  14 , a sleeve  13 , a holder  15 , a spring-loaded firing pin  16 , an L-shaped trigger plate  18 , and an operating member  19 . 
   The housing  11  has a front open end  111  and a rear end  112  opposite to each other in a direction (A). 
   The barrel unit  12  is inserted movably into the housing  11  via the front open end  111  of the housing  11 . 
   The piston assembly  14  is disposed movably in the barrel unit  12 . The sleeve  13  is coupled to a rear end of the barrel unit  12 , and defines a chamber  131  for receiving gunpowder in the form of a load  9  therein. The holder  15  is disposed in the housing  11 , abuts against the sleeve  13 , and has a through hole  151 . 
   The spring-loaded firing pin  16  is disposed in the housing  11  between the holder  15  and the rear end  112  of the housing  11 , and has a thinner free end portion  161  extending into the through hole  151  in the holder  15 , a thicker end portion  163  opposite to the free end portion  161  in the direction (A) and having a diameter larger than that of the free end portion  161 , and an outer annular shoulder surface  162  disposed between the thinner free end portion  161  and the thicker end portion  163 . The firing pin  16  is movable between a standby position, where a front tip of the thinner free end portion  161  of the firing pin  16  is spaced apart from the gunpowder in the chamber  131  in the sleeve  13 , and a firing position, where the front tip of the thinner free end portion  161  of the firing pin  16  contacts and ignites the gunpowder in the chamber  131  in the sleeve  13 , as shown in  FIG. 3 . 
   The trigger plate  18  is disposed in the housing  11  and adjacent to the holder  15 , has a first plate portion  181  perpendicular to the direction (A) and formed with a through hole  180  permitting extension of the firing pin  16  therethrough, and a second plate portion  182  connected to one end of the first plate portion  181  and parallel to the direction (A). It is noted that, as shown in  FIG. 2 , the through hole  180  has a circular first hole portion  1801  having a diameter larger than that of the thicker end portion  163  of the firing pin  16 , and a second hole portion  1802  having a diameter smaller than that of the thicker end portion  163  of the firing pin  16  and slightly larger than the thinner free end portion  161  of the firing pin  16 . The trigger plate  18  is movable between a non-triggering position, where a part of the thinner free end portion  161  extends through the second hole portion  1802  of the through hole  180  in the first plate portion  181  and where the outer annular shoulder surface  162  abuts against an upper end of the first plate portion  181  of the trigger plate  18 , as shown  FIG. 1 , and a triggering position, where the firing pin  16  extends through the first hole portion  1801  of the through hole  180  in the first plate portion  181  of the trigger plate  18 , as shown in  FIG. 3 . As a result, when the trigger plate  18  is moved from the non-triggering position to the triggering position, the firing pin  16  is thus moved from the standby position to the firing position. 
   The operating member  19  is mounted pivotally on the housing  11 , and is operable so as to drive the trigger plate  18  to move from the non-triggering position to the triggering position. 
   In use, prior to operation of the operating member  19 , the firing pin  16  is maintained in the standby position since the outer annular shoulder surface  162  of the firing pin  16  abuts against the upper end of the first plate portion  181  of the trigger plate  18 . 
   However, it is desired to design a power-actuated fastener-driving tool having a configuration different from that of the aforesaid conventional powder-actuated fastener-driving gun  1 . 
   SUMMARY OF THE INVENTION 
   Therefore, an object of the present invention is to provide a powder-actuated fastener-driving tool with safety protection. 
   According to one aspect of the present invention, a powder-actuated fastener-driving tool comprises: 
   a housing having a front open end and a rear end opposite to each other in an axis; 
   a barrel unit inserted movably into the housing through the front open end and having a rear end portion that is disposed in the housing and that defines a chamber adapted for accommodating gunpowder therein; 
   a holder disposed movably in the housing, abutting against the rear end portion of the barrel unit, and having a through hole defined by an inner annular surface that has an inwardly extending shoulder portion; and 
   a spring-loaded firing pin disposed in the housing and between the rear end of the housing and the holder, and having a free end portion that extends into the through hole in the holder, the firing pin being movable among a normal position, a standby position and a firing position, wherein
         when the firing pin is disposed in the normal position, the firing pin is inclined relative to the axis so that the free end portion of the firing pin engages the shoulder portion of the inner annular surface of the holder and is spaced apart from the gunpowder,   when the firing pin is moved from the normal position to the standby position, an assembly of the barrel unit, the holder and the firing pin is moved toward the rear end of the housing, and   when the firing pin is moved from the standby position to the firing position, the free end portion of the firing pin disengages the shoulder portion of the inner annular surface of the holder to move along the axis toward the rear end portion of the barrel unit to thereby contact and ignite the gunpowder in the chamber in the rear end portion of the barrel unit; and       

   a trigger unit mounted on the housing and operable so as to enable the firing pin to switch from the standby position to the firing position. 
   According to another aspect of the present invention, there is provided a triggering device for a powder-actuated fastener-driving tool. The powder-actuated fastener-driving tool includes 
   a housing having a front open end and a rear end opposite to each other in an axis, and 
   a barrel unit inserted movably into the housing through the front open end and having a rear end portion that is disposed in the housing and that defines a chamber for accommodating gunpowder therein. 
   The triggering device comprises: 
   a holder adapted to be disposed movably in the housing, adapted to abut against the rear end portion of the barrel unit, and having a through hole defined by an inner annular surface that has an inwardly extending shoulder portion; and 
   a spring-loaded firing pin adapted to be disposed in the housing and between the rear end of the housing and the holder, and having a free end portion that extends into the through hole in the holder, the firing pin being movable among a normal position, a standby position and a firing position, wherein
         when the firing pin is disposed in the normal position, the firing pin is inclined relative to the axis so that the free end portion of the firing pin engages the shoulder portion of the inner annular surface of the holder and is spaced apart from the gunpowder,   when the firing pin is moved from the normal position to the standby position, an assembly of the barrel unit, the holder and the firing pin is moved toward the rear end of the housing, and   when the firing pin is moved from the standby position to the firing position, the free end portion of the firing pin disengages the shoulder portion of the inner annular surface of the holder to move along the axis toward the rear end portion of the barrel unit to thereby contact and ignite the gunpowder in the chamber in the rear end portion of the barrel unit; and       

   a trigger unit adapted to be mounted on the housing and operable so as to enable the firing pin to switch from the standby position to the firing position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which: 
       FIG. 1  is a schematic sectional view showing a conventional powder-actuated fastener-driving gun when in a standby state; 
       FIG. 2  is a perspective view of a trigger plate of the conventional powder-actuated fastener-driving gun; 
       FIG. 3  is a schematic sectional view showing the conventional powder-actuated fastener-driving tool when in a firing state; 
       FIG. 4  is a perspective view showing the preferred embodiment of a powder-actuated fastener-driving tool; 
       FIG. 5  is an exploded perspective view showing the preferred embodiment; 
       FIG. 6  is a schematic sectional view showing the preferred embodiment when in a normal state; 
       FIG. 7  is a schematic sectional view showing the preferred embodiment when in a standby state; and 
       FIG. 8  is a schematic sectional view showing the preferred embodiment when in a firing state. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 4 to 6 , the preferred embodiment of a powder-actuated fastener-driving tool  2  according to the present invention is shown to include a housing  21 , a barrel unit  22 , a holder  3 , a spring-loaded firing pin  4 , a trigger unit  6 , and a biasing unit  7 . 
   The housing  21  has a front open end  211  and a rear end  212  opposite to each other in an axis (X). 
   The barrel unit  22  is inserted movably into the housing  21  through the front open end  211  for receiving a piston assembly  24  therein. In this embodiment, the barrel unit  22  includes a thinner first barrel  221 , a thicker second barrel  222  connected threadedly to a rear end of the first barrel  221 , and a sleeve  223  serving as a rear end portion of the barrel unit  22 , and inserted into and connected threadedly to a rear end of the second barrel  222 . The sleeve  223  defines a chamber  2231  adapted for accommodating gunpowder (not shown) therein. 
   The holder  3  is disposed movably in the housing  21 , abuts against the sleeve  223  of the barrel unit  22 , and has a through hole  30  defined by an inner annular surface  31  that has an inwardly extending shoulder portion  312 . 
   The spring-loaded firing pin  4  is disposed in the housing  21  and between the rear end  212  of the housing  21  and the holder  3 , and has a free end portion  41  extending into the through hole  30  in the holder  3  and having a front tip  411 . The firing pin  4  is movable among a normal position, a standby position and a firing position. When the firing pin  4  is disposed in the normal position, the firing pin  4  is inclined relative to the axis (X) so that the free end portion  41  of the firing pin  4  engages the shoulder portion  312  of the inner annular surface  31  of the holder  3 , and is spaced apart from the gunpowder in the chamber  2231  in the sleeve  223 , as shown in  FIG. 6 . 
   Referring further to  FIGS. 7 and 8 , when the firing pin  4  is moved from the normal position to the standby position, an assembly of the barrel unit  22 , the holder  3  and the firing pin  4  is moved toward the rear end  212  of the housing  21  such that a coiled spring  42  of the firing pin  4  is compressed, as shown in  FIG. 7 . When the firing pin  4  is moved from the standby position to the firing position, the free end portion  41  of the firing pin  4  disengages the shoulder portion  312  of the inner annular surface  31  of the holder  3  to move along the axis (X) toward the sleeve  223  of the barrel unit  22  by virtue of the restoration force of the coiled spring  42 . As a result, the front tip  411  of the free end portion  41  of the firing pin  4  contacts and ignites the gunpowder in the chamber  2231  in the sleeve  223  of the barrel unit  22 , as shown in  FIG. 8 . 
   The trigger unit  6  is mounted on the housing  21 , and is operable so as to enable the firing pin  4  to switch from the standby position to the firing position. In this embodiment, the trigger unit  6  includes an operating member  62 , a trigger plate  61 , and a biasing member  63 . The operating member  62  has a pivot end  621  connected pivotally to the housing  21  by a pivot pin, and a driving end  622  opposite to the pivot end  621 . The trigger plate  61  is driven by the driving end  622  of the operating member  62  to move in the housing  21 , and is formed with a through hole  611  permitting extension of the firing pin  4  therethrough. It is noted that the through hole  611  has a diameter slightly greater than that of the firing pin  4 . The operating member  62  is operable so as to enable the trigger plate  61  to move between a triggering position and a non-triggering position. As shown in  FIGS. 6 and 7 , when the trigger plate  61  is disposed at the non-triggering position, the firing pin  4  is held by the trigger plate  61  to maintain engagement between the free end portion  41  of the firing pin  4  and the shoulder portion  312  of the inner annular surface  31  of the holder  3 . When the trigger plate  61  is moved from the non-triggering position to the triggering position by virtue of movement of the driving end  622  of the operating member  62  toward the housing  21 , the free end portion  41  of the firing pin  4  is pushed by the trigger plate  61  to disengage the shoulder portion  312  of the inner annular surface  31  of the holder  3  so that the firing pin  4  is moved from the standby position to the firing position. The biasing member  63 , such as a coiled spring, is disposed between the operating member  62  and the housing  21  for biasing the trigger plate  61  to the non-triggering position. 
   The biasing unit  7  is disposed in the housing  21  for biasing an assembly of the holder  3  and the barrel unit  22  to move along the axis (X) toward the front open end  211  of the housing  21 . In this embodiment, the biasing unit  7  includes a pushing member  71  abutting against a rear end of the holder  3 , and a coiled spring  72  disposed between the pushing member  71  and the rear end  212  of the housing  21 . 
   In use, after a fastener, for example a nail as indicated by imaginary lines in  FIG. 7 , is disposed in the first barrel  221  of the barrel unit  22 , the first barrel  221  of the barrel unit  22  abuts against an article  8  to be fastened while the housing  21  is pushed forcedly toward the article  8  so that the assembly of the barrel unit  22 , the holder  3  and the firing pin  4  is moved toward the rear end  212  of the housing  21 . As a result, the firing pin  4  is moved from the normal position to the standby position. Subsequently, the trigger plate  61  is moved from the non-triggering position to the triggering position by pressing the driving end  622  of the operating member  62  so that the firing pin  4  is moved from the standby position to the firing position. Thus, the gunpowder in the chamber  2231  is ignited by the front tip  411  of the firing pin  4  to generate kinetic energy for driving the fastener to move into the article  8  by the piston assembly  24 . 
   Thereafter, while the first barrel  221  of the barrel unit  22  is removed from the article  8 , an assembly of the barrel unit  22  and the holder  3  is pushed by the pushing member  71  of the biasing unit  7  to move frontwardly as a result of a restoration force of the coiled spring  72 , and the trigger plate  61  is moved from the trigger position to the non-triggering position as a result of a restoration force of the biasing member  63  such that the free end portion  41  of the firing pin  4  engages the shoulder portion  312  of the inner annular surface  31  of the holder  3  and that the firing pin  4  is inclined relative to the axis (X) again, i.e., the firing pin  4  is moved from the firing position to the normal position. 
   It is noted that, during use, the firing pin  4  cannot remain in the standby position unless the housing  21  is continuously pushed toward the article  8  prior to operation of the trigger unit  6 . In other words, once pushing of the housing  21  toward the article  8  is terminated, the firing pin  4  is immediately moved from the standby position back to the normal position. On the other hand, when the firing pin  4  is disposed in the normal position, the gunpowder in the chamber  2231  cannot be ignited even if the trigger plate  61  is moved from the non-triggering position to the triggering position. Therefore, the powder-actuated fastener-driving tool  2  of the present invention can effectively prevent unintentional ignition of the gunpowder, thereby ensuring safety during use. 
   While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.