Abstract:
A nail-driving gun includes a safety rod disposed movably on a front end of a barrel, and a trigger member disposed movably on a handle. Upon actuation of the safety rod and the trigger member, the barrel shoots a nail therefrom. When the safety rod is pressed against a wall prior to actuation of the trigger member, the gun can be operated in a single shot mode, in which the safety rod is prevented from returning to its original position due to a positioning pin that is attached movably to the trigger member. When the safety rod is pressed against the wall after actuation of the trigger member, the gun can be operated in a continuous shooting mode. The safety rod and the trigger member are actuated by one hand that holds the handle.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a nail-driving gun, more particularly to a nail-driving gun, which can be operated pneumatically in a single shot mode or a continuous shooting mode that can be selected by controlling the actuation order of a safety rod and a trigger member. 
     2. Description of the Related Art 
     The improvement of this invention is directed to a conventional nail-driving gun, which can be operated pneumatically by reciprocating a valve rod in a single shot mode or a continuous shooting mode that are selected by actuating a switching member. When such a nail-driving gun is in use, because a handle of the gun is held with one hand, it is necessary to actuate the switching member with the other hand, thereby resulting in difficulties during operation of the gun. Furthermore, the trigger member is disposed adjacent to the valve rod so that the setback force of the gun may move untimely the valve rod. As such, it is possible to form two consecutive shots even if the switching member is set at the single shot mode. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide a nail-driving gun for performing a single shot operation and a continuous shooting operation, which can be selected by controlling the actuation order of two members, the members being capable of being actuated easily using one hand that holds a handle of the gun. 
     Another object of this invention is to provide a nail-driving gun, which can prevent formation of two consecutive shots when the gun is operated in a single shot mode. 
     According to this invention, a nail-driving gun includes a safety rod disposed movably on a front end of a barrel, and a trigger member disposed movably on a handle. Upon actuation of the safety rod and the trigger member, the barrel shoots a nail therefrom. When the safety rod is pressed against a wall prior to actuation of the trigger member, the gun can be operated in a single shot mode, in which the safety rod is prevented from returning to its original position due to a positioning pin that is attached movably to the trigger member. When the safety rod is pressed against the wall after actuation of the trigger member, the gun can be operated in a continuous shooting mode. The safety rod and the trigger member are actuated by one hand that holds the handle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of this invention will become apparent in the following detailed description of a preferred embodiment of this invention, with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic partly sectional view of the preferred embodiment of a nail-driving gun according to this invention; 
     FIG. 2 is an exploded perspective view of a portion of the preferred embodiment; 
     FIG. 3 is a fragmentary sectional view of the preferred embodiment, in which a press member, a trigger member and a valve rod are disposed at their normal positions; 
     FIG. 4 is a fragmentary sectional view of the preferred embodiment, in which the press member moves to a rear limit position during a single shot operation; 
     FIG. 5 is a fragmentary sectional view of the preferred embodiment, in which the trigger member moves to an actuated position after the press member moves to the rear limit position during the single shot operation; 
     FIG. 6 is a fragmentary sectional view of the preferred embodiment, in which the trigger member moves to the actuated position during a continuous shooting operation; 
     FIG. 7 is a fragmentary sectional view of the preferred embodiment, in which the press member moves to the rear limit position after the trigger member moves to the actuated position during the continuous shooting operation; and 
     FIG. 8 is a fragmentary sectional view of the preferred embodiment, illustrating how the press member is urged from the position shown in FIG. 7 to its normal position upon the release of a forward pushing force on a safety rod during the continuous shooting operation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1,  2  and  3 , the preferred embodiment of a nail-driving gun according to this invention is shown to include a gun body  10 , a safety rod  20 , a press member  30 , a positioning seat  40  and a trigger assembly  50 . 
     The gun body  10  includes a handle  11  and a horizontal barrel  12 . The handle  11  is provided with a spring-biased valve rod  11  that is biased to a non-compressing position shown in FIG.  3  and that is movable to a compressing position shown in FIG.  5 . The barrel  12  has a rear portion that is attached to the handle  11 , and a front portion with a nail-shooting seat  121  that is operably associated with the valve rod  111  in a known manner. When the valve rod  111  moves from the non-compressing position shown in FIG. 3 to the compressing position shown in FIG. 5, a nail is shot from the nail-shooting seat  121 , and is driven into a wall  60 . To perform a subsequent nail shooting operation, it is necessary to return the valve rod  111  to the non-compressing position and to move the same from the non-compressing position to the compressing position one more time. 
     The safety rod  20  is disposed movably on a front end of the barrel  12 , and has a wall-pressing rod portion  21  that abuts against the wall  60  at a front end  211 , and a connecting rod portion  22  that is connected fixedly to the wall-pressing rod portion  21  at a front end  221  and that is connected fixedly to a front end of the press member  30  at a rear end  222 . 
     The positioning seat  40  includes two parallel vertical side plates  41 , a horizontal bottom plate  42 , and a limiting member  43 . The side plates  41  are disposed fixedly on the barrel  12 , and are formed respectively with a pair of aligned slide slots  411  that receive slidably a slide rod  45  therein. The bottom plate  42  is connected fixedly to and is perpendicular to the side plates  41 . The limiting member  43  interconnects the side plates  41  fixedly, and is spaced apart from the bottom plate  42 . 
     The press member  30  includes a front casing element  31  and a rear pressing section  32 , which is shaped as a horizontal plate that is superimposed on the bottom plate  42  of the positioning seat  40  and that is received fittingly and movably within a space  44  between the bottom plate  42  and the limiting member  43 . The rear pressing section  32  has a top surface  322 , which is formed with an upwardly extending integral rear projection  321  that is disposed behind the slide rod  45 , thereby preventing forward removal of the press member  30  from the positioning seat  40 . 
     The limiting member  43  of the positioning seat  40  has a front surface, which is formed with a recess  431 . A biasing unit is configured as a coiled compression spring  432 , which has a front end that is sleeved fixedly on a rearwardly extending integral front projection  311  of the front casing element  31  of the press member  30 , and a rear end that is confined within the recess  431  in the limiting member  43  so as to bias the press member  30  forward and away from the positioning seat  40 . Accordingly, the press member  30  is biased to a front limit position (A) shown in FIG.  3 . When the front end  211  of the safety rod  20  is pressed forcibly against the wall  60 , the press member  30  moves relative to the barrel  12  to a rear limit position (B) shown in FIG. 4, where the front casing element  31  of the press member  30  abuts against the limiting member  43  of the positioning seat  40  so as to prevent further rearward movement of the press member  30 . 
     The trigger assembly  50  includes an inverted U-shaped pivot member  51 , a trigger member  52 , a gap  53  that is defined within the pivot member  51  for passage of the rear pressing section  32  of the press member  30 , a positioning pin  54 , a pushing plate  55 , and a spring  56 . The pivot member  51  is mounted pivotally on the side plates  41  of the positioning seat  40  by a pivot pin  57 . The trigger member  52  is biased to a non-actuated position (C) shown in FIG. 3, and can be pressed so as to rotate to an actuated position (D) shown in FIG. 5, which is located behind the non-actuated position (C). The pivot member  51  has an upper portion  511  which is formed with a straight guide slot unit  512  that has closed front and rear ends  5121 ,  5122 . The trigger member  52  is formed integrally with a lower portion of the pivot member  51 . The positioning pin  54  is received slidably within the guide slot unit  512  in the pivot member  51 . When the press member  30  is located at the front limit position and when the trigger member  52  is located at the non-actuated position, the positioning pin  54  is disposed at a rear portion of the guide slot unit  512  behind the rear projection  321  of the press member  30 . The pushing plate  55  is formed with two integral lugs  551  that are disposed pivotally on the pivot member  51 , and is located in front of the valve rod  111 . A free end  552  of the pushing plate  55  is biased by a spring  56  forward and away from the valve rod  111  to abut against the rear pressing section  32  of the press member  30 . In addition, the spring  56  biases the trigger member  52  to the non-actuated position (C). 
     When it is desired to perform a single shot operation, the safety rod  20  is pressed against the wall  60  so as to move the press member  30  to the rear limit position (B), as shown in FIG. 4, where the free end  552  of the pushing plate  55  rotates clockwise to a position adjacent to the valve rod  111 . Subsequently, the trigger member  52  is pressed rearward to the actuated position (D), as shown in FIG. 5, so that the pushing plate  55  contacts and pushes the valve rod  111  rearward to the compressing position, thereby shooting the nail from the seat  121 . Referring to FIG. 5, when the trigger member  52  moves from the non-actuated position (C) to the actuated position (D), the pivot member  51  rotates counterclockwise so that the positioning pin  54  moves to the front end  5121  of the guide slot unit  512 . As such, the positioning pin  54  is adjacent to and is located in front of the rear projection  321 , thereby preventing forward movement of the valve rod  111  back to the non-compressing position. At this time, because the valve rod  111  cannot return to the non-compressing position, unintentional subsequent nail shooting resulting from a setback force of the gun after a previous nail shooting operation can be prevented as long as the trigger member  52  is retained at the actuated position (D). Accordingly, two consecutive shots can be avoided during a single shot operation. When the trigger member  52  is released so as to return to the non-actuated position (C), the positioning pin  54  moves to the position shown in FIG. 4, where the press member  30  will be biased by the spring  432  to the position shown in FIG. 3, thereby permitting a-subsequent single shot operation. 
     When it is desired to perform a continuous shooting operation, the trigger member  52  is pressed so as to move from the non-actuated position (C) shown in FIG. 3 to the actuated position (D) shown in FIG.  6 . Referring to FIGS. 1 and 7, subsequently, the safety rod  20  is pressed against the wall  60 , thereby permitting movement of the press member  30  from the front limit position (A) to the rear limit position (B), during which the rear projection  321  contacts and pushes the positioning pin  54  rearward to the rear end  5122  of the guide slot unit  512 . When the press member  30  moves to the rear limit position (B), the free end  552  of the pushing plate  55  turns rearward so as to move the valve rod  111  to the compressing position, thereby permitting a nail shooting operation. Thereafter, a forward pushing force applied on the safety rod  20  is released so that the safety rod  20  is removed from the wall  60  such that the press member  30  is biased to the front limit position (A) shown in FIG. 8, after which the safety rod  20  can be pressed against the wall  60  so as to once again move the press member  30  to the rear limit position (B) shown in FIG.  7 . In this way, the valve rod  111  can reciprocate between the non-compressing position and the compressing position, thereby shooting nails continuously from the seat  121 . 
     When performing the single shot or continuous shooting operation, the safety rod  20  and the trigger member  52  can be actuated using only one hand that holds the handle  11 . Accordingly, the gun of this invention can be operated with ease. 
     With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated by the appended claims.