Patent Abstract:
A single/continuous dual firing mode trigger_structure used in an air nailing gun for single/continuous firing control in which a switching mechanism is provided in the trigger and adapted to selectively control the operation of the trigger between a single firing mode and a continuous firing mode.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an air nailing gun and, more specifically, to a single/continuous dual firing mode trigger structure for air nailing gun. 
     2. Description of the Related Art 
     A regular air nailing gun generally comprises a gun body having muzzle, a firing valve for firing the air nailing gun, a trigger for driving the firing valve to fire the air nailing gun, a supplementary trigger pivoted to the trigger, and a safety link axially slidably mounted in the muzzle. When pressed the trigger accidentally, the supplementary trigger is received inside the trigger without triggering the firing valve. When pressing the safety link against the workpiece after the trigger pressed, the supplementary trigger is forced to trigger the firing valve, thereby causing the firing valve to fire the air nailing gun. This structure of air nailing gun is functional, however the user must repeat the triggering action to fire the air nailing gun when wishing to drive a second nail into the workpiece. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a single/continuous dual firing mode trigger structure for air nailing gun, which provides a single firing mode and a continuous firing mode for selection. To achieve these and other objects of the present invention, the single/continuous dual firing mode trigger structure installed in an air nailing gun and adapted to fire said nailing gun, comprising: a gun body having a handle; a firing valve installed in the handle, the firing valve being of a two-step firing design that does not fire said air nailing gun when forced to a first step position, and achieves a firing action when forced further to a second step position; a trigger holder fixedly provided in the handle, the trigger holder having a pivot hole; a safety link axially slidably mounted in muzzle of the gun body, the safety link having a curved rear end extended to the inside of the trigger holder; and a trigger assembly pivoted to the pivot hole of the trigger holder and controlled by the safety link to drive the firing valve to fire the air nailing gun. The trigger assembly comprises a main trigger member pivoted to the pivot hole of the trigger holder, a pivot shaft, which pivots he main trigger member to the pivot hole of the trigger holder, the pivot shaft having a longitudinal cut plane, and a supplementary trigger member, the supplementary trigger member having a tail movably pivoted to the inside of the main trigger member and a head to be stopped at the pivot shaft. The pivot shaft can be rotated to move the longitudinal cut plane between two positions within 90° angle relative to the supplementary trigger member to control the air nailing gun between the single firing mode and the continuous firing mode. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is plain view of an air nailing gun constructed according to the first embodiment of the present invention. 
     FIG. 2 is an exploded view of a part of the single/continuous dual firing mode trigger structure according to the present invention. 
     FIG. 3 is an assembly view of FIG.  2 . 
     FIG. 4 is a cross-sectional view of the trigger holder showing the relation between the pivot hole and the locating notches according to the first embodiment of the present invention. 
     FIG. 5 is a cross-sectional view of the switching mechanism according to the first embodiment of the present invention. 
     FIG. 6A is a schematic drawing showing the single firing operation of the present invention (I). 
     FIG. 6B is a schematic drawing showing the single firing operation of the present invention (II). 
     FIG. 6C is a schematic drawing showing the single firing operation of the present invention (III). 
     FIG. 7 is a schematic drawing showing the continuous firing operation of the present invention. 
     FIG. 8 is a cross-sectional view of the trigger holder showing the relation between the pivot hole and the locating notches according to the second embodiment of the present invention. 
     FIG. 9 is a cross-sectional view of the switching mechanism according to the second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a single/continuous dual firing mode trigger structure in accordance with the present invention the first embodiment of the present invention is shown comprised of a gun body  10 , a safety link  20 , a switching mechanism, and a trigger assembly  40 . 
     Referring to FIGS. from  2  through  6 A and FIG. 1 again, the gun body  10  comprises a forwardly extended front muzzle  11 , a downwardly extended bottom handle  12 , a firing valve  13  disposed in the front top side of the bottom handle  12 , a trigger holder  14  provided at a front upper side relative to the firing valve  13 , a pivot hole  141  transversely extended through the trigger holder  14 , and two locating notches  142  provided in the trigger holder  14  and respectively radially extended from the pivot hole  141  at right angles (see FIG.  4 ). The safety link  20  is axially slidably mounted in the front side of the front muzzle  11  of the gun body  10 , having a curved rear end  21  extended to the inside of the trigger holder  14  (see also FIG.  6 A). The aforesaid switching mechanism comprises a pivot axle  31 , and a knob  32  fixedly located on one end of the pivot axle  31 . The knob  32  has a protruded engagement portion  321  disposed in the connecting area between the pivot axle  31  and the knob  32 . The pivot axle  31  has a longitudinal cut plane  311  in the periphery. The remote end of the pivot axle  31  (the end remote from the knob  32 ) is mounted with a spring washer  312 . The trigger assembly  40  comprises a main trigger member  41  pivoted to the pivot axle  31 , a supplementary trigger member  42  pivoted to the inside of the main trigger member  41  by a pivot pin, and a torsional spring  43  mounted on the pivot pin. The torsional spring  43  has a middle saddle  431  coupled to the firing valve  13 . The two distal ends of the torsional spring  43  are stopped against the inside wall of the main trigger member  41 . When the trigger assembly  40  triggered, the torsional spring  43  imparts a spring force to return the trigger assembly  40  to its former position. The firing valve  13  is of a two-step firing design that does not fire the nailing gun when forced to the first step position, and achieves a firing action when forced further to the second step position. When fired, the firing valve  13  must be fully released so that air pressure can be charged again for a next firing operation. 
     The user can pull the knob  32  and the pivot axle  31  outwards at a distance and then rotate the knob  32  and the pivot axle  31 , enabling the protruded engagement portion  321  to be aimed at one locating notch  142  of the trigger holder  14 . When the user released the hand from the knob  32  at this time, the spring washer  312  imparts a spring force to return the axle knob  31 , thereby causing the protruded engagement portion  321  to be engaged into the selected locating notch  142  of the trigger holder  14 . 
     Before pressing the safety link  20  on the surface of the workpiece, the top end of the supplementary trigger member  42  is forced into contact with the periphery of the pivot axle  32 . When triggering the main trigger member  41  at this time, the firing valve  13  is moved to the first step position without firing the nailing gun. When the user pressed the safety link  20  on the surface of the workpiece, the curved rear end  21  of the safety link  20  pushed the top end of the supplementary trigger member  42  inwards toward the firing valve  13  to move the firing valve  13  from the first step position to the second step position to fire the nailing gun. 
     Referring to FIGS. 6A,  6 B, and  6 C, when the user turned the switching mechanism (the knob  32 ) to the single firing position to engage the protruded engagement portion  321  into the first locating notch  142  (the position referenced by “a” in FIG. 4) of the trigger holder  14 , the pivot axle  31  is turned to the first position where the longitudinal cut plane  311  is kept perpendicular to the supplementary trigger member  42 . When the user released the safety link  20  from the workpiece after fired, the supplementary trigger member  42  is forced by the spring force of the torsional spring  43  against the pivot shaft  31  and prohibited from releasing the firing valve  13 . At this time, the user must release the main trigger member  41  so that the firing valve  13  can be released for enabling the nailing gun to be charged with air again for a next firing operation. 
     Referring to FIG. 7, when the when the user turned the switching mechanism (the knob  32 ) to the continuous firing position to engage the protruded engagement portion  321  into the second locating notch  142  (the position referenced by “b” in FIG. 4) of the trigger holder  14 , the supplementary trigger member  42  is forced over the longitudinal cut plane  311  of the pivot shaft  31  to release the wiring valve  13 , enabling the nailing gun to be charged with air again for a next firing operation. When the user holding the main trigger member  42  in the triggering position and repeatedly pressing the safety link  20  against the workpiece, the nailing gun drives nails into the workpiece continuously. 
     By means of the effect of the longitudinal cut plane  311  of the pivot shaft  31 , the user can selectively control the operation of the air nailing gun between the single firing mode and the continuous firing mode. 
     FIGS. 8 and 9 show a part of the second embodiment of the present invention. According to this embodiment, there are four locating notches  142 ′ equiangularly spaced around the pivot hole  141 ′ of the trigger holder  14 , and the pivot axle  31 ′ has two longitudinal cut plane  311 ′ at two opposite sides. This alternate form enables the switching mechanism to be turned between the single firing position and the continuous firing position either in the clockwise direction or the counter-clockwise direction. 
     A prototype of single/continuous dual firing mode trigger structure for air nailing gun has been constructed with the features of FIGS.  1 ˜ 9 . The single/continuous dual firing mode trigger structure for air nailing gun functions smoothly to provide all of the features discussed earlier. 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.

Technology Classification (CPC): 1