Patent Publication Number: US-9833889-B2

Title: Nail-driving gun trigger assembly with safety latch

Description:
FIELD OF THE INVENTION 
     This invention relates to a nail-driving gun trigger assembly, more particular to a nail-driving gun trigger assembly with a safety latch and a release button which are mounted movably to a trigger piece. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 4,565,312 discloses a conventional powder actuated tool with safety. The conventional powder actuated tool includes a housing, a barrel, and a firing mechanism. The housing has a breech portion, a cradle portion telescopically connected to the breech portion, and a grip part extending from the breech portion. The barrel is mounted movably in the cradle portion, has an insert formed with a firing chamber for receiving an explosive powder cartridge, and defines a bore for receiving a fastener-driving ram. The firing mechanism includes a breech block, a firing pin and a trigger. A firing pin pawl is mounted in a blind hole in the firing pin, and is biased by a spring into a slot in the breech block. The slot has a searing surface that engages the firing pin pawl. A stop member is pivoted to the cradle portion, and has a tongue urged by a spring to protrude into a bore in the cradle portion to abut against the barrel, thereby preventing movement of the barrel relative to the cradle portion toward the breech block for positioning the explosive powder cartridge at a ready-to-fire position. Hence, the stop member can reduce the incidence of accidental drop fire. 
     In order to cock the tool and fire it, an operator must use one hand to depress the stop member to move the tongue out of the bore in the cradle portion to permit positioning of the explosive powder cartridge at the ready-to-fire position, and use the other hand to grasp the grip part to enable finger actuation of the trigger. Pulling the trigger causes the firing pin pawl to move into the blind bore and to disengage the searing surface, thereby releasing the firing pin from the searing surface and permitting movement of the firing pin, which is urged by a spring, toward the explosive powder cartridge. 
     Although the purpose of using both hands to cock and fire the tool is for safety considerations, it also causes inconvenience. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a nail-driving gun trigger assembly that can overcome the aforesaid drawback associated with the prior art. 
     According to the present invention, there is provided a nail-driving gun trigger assembly that comprises: a gun housing including a hand-grip that defines an inner space and a window opening which is in spatial communication with the inner space; a trigger mechanism including a trigger piece, a safety latch, and a release button, the trigger piece extending through the window opening into the inner space and being movable relative to the hand-grip between a non-actuating position and an actuating position, the safety latch being mounted movably on the trigger piece and being movable relative to the trigger piece between locked and unlocked positions, the release button being mounted movably on the trigger piece and being movable relative to the trigger piece between first and second positions, the release button and the safety latch being co-movable with the trigger piece relative to the hand-grip when the trigger piece is moved between the non-actuating and actuating positions; and an urging unit for restoring the trigger piece to the non-actuating position, the safety latch to the locked position, and the release button to the first position. The trigger piece is stopped from moving from the non-actuating position to the actuating position by engagement between the safety latch and the hand-grip when the safety latch is disposed at the locked position. The release button is in sliding contact with the safety latch so as to push the safety latch to move from the locked position to the unlocked position when the release button is pushed to move from the first position to the second position, thereby disengaging the safety latch from the hand-grip and permitting movement of the trigger piece together with the safety latch and the release button from the non-actuating position to the actuating position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a perspective view of the embodiment of a nail-driving gun trigger assembly according to the present invention; 
         FIG. 2  is a sectional view of the embodiment; 
         FIG. 3  is a fragmentary exploded perspective view of the embodiment; 
         FIG. 4  is a fragmentary schematic front view of the embodiment; 
         FIG. 5  is a perspective view of a trigger piece of the embodiment; 
         FIG. 6  is a fragmentary sectional view of the embodiment to illustrate a first state where a release button is disposed at a first position, a safety latch is disposed at a locked position, and the trigger piece is disposed at a non-actuating position; 
         FIG. 7  is a fragmentary sectional view of the embodiment to illustrate a second state where the release button is disposed at a second position, the safety latch is disposed at a unlocked position, and the trigger piece is disposed at the non-actuating position; and 
         FIG. 8  is a fragmentary sectional view of the embodiment to illustrate a third state where the release button is disposed at the second position, the safety latch is disposed at the locked position, and the trigger piece together with the release button and the safety latch is disposed at an actuating position. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT 
       FIGS. 1 to 6  illustrate the embodiment of a nail-driving gun trigger assembly according to the present invention. 
     The nail-driving gun trigger assembly includes a gun housing  2 , a trigger mechanism, and an urging unit  6 . The gun housing  2  includes a hand-grip  21  that defines an inner space  20  and a window opening  22  which is in spatial communication with the inner space  20 . The trigger mechanism includes a trigger piece  3 , a safety latch  4 , and a release button  5 . The trigger piece  3  extends through the window opening  22  into the inner space  20 , and is movable relative to the hand-grip  21  between a non-actuating position (see  FIG. 7 ) and an actuating position (see  FIG. 8 ). The safety latch  4  is mounted movably on the trigger piece  3 , and is movable relative to the trigger piece  3  between locked and unlocked positions (see  FIGS. 6 and 7 ). The release button  5  is mounted movably on the trigger piece  3 , and is movable relative to the trigger piece  3  between first and second positions (see  FIGS. 6 and 7 ). The release button  5  and the safety latch  4  are co-movable with the trigger piece  3  relative to the hand-grip  21  when the trigger piece  3  is moved between the non-actuating and actuating positions. The urging unit  6  includes a latch spring  61  and a trigger spring  62  for restoring the trigger piece  3  to the non-actuating position, the safety latch  4  to the locked position, and the release button  5  to the first position. 
     The trigger piece  3  is stopped from moving from the non-actuating position to the actuating position by engagement between the safety latch  4  and the hand-grip  21  when the safety latch  4  is disposed at the locked position. The release button  5  is in sliding contact with the safety latch  4  so as to push the safety latch  4  to move from the locked position to the unlocked position when the release button  5  is pushed to move from the first position to the second position, thereby disengaging the safety latch  4  from the hand-grip  21  and permitting movement of the trigger piece  3  together with the safety latch  4  and the release button  5  from the non-actuating position to the actuating position. 
     In this embodiment, the trigger piece  3  has an operating protrusion  31  that protrudes frontwardly and outwardly of the window opening  22  and that has a trigger-front wall  311 . The release button  5  is disposed adjacent to the trigger-front wall  311 , and has a button-front wall  51  that is disposed frontwardly of the trigger-front wall  311 , so that a user can place two fingers of one hand one behind the other respectively on the trigger-front wall  311  and the button-front wall  51  for pressing thereon. 
     The safety latch  4  is movable relative to the trigger piece  3  between the locked and unlocked positions along a first direction (X). The release button  5  is movable relative to the trigger piece  3  between the first and second positions along a second direction (Y) transverse to the first direction (X). The arrangement of the safety latch  4  and the release button  5  on the trigger piece  3  and of the moving directions of the safety latch  4  and the release button  5  relative to the trigger piece  3  facilitate prevention of the incidence of drop fire. 
     The trigger piece  3  is pivoted to the hand-grip  21  so as to be rotatable relative to the hand-grip  21  about an axis (Z) between the non-actuating and actuating positions. The axis (Z) is transverse to the first and second directions (X, Y). 
     The operating protrusion  31  is hollow, defines a chamber  30 , and further has two opposite side walls  312  that extend rearwardly from the trigger-front wall  311  and that are spaced apart from each other, and a bottom wall  313  (see  FIG. 8 ) that is connected to the trigger-front wall  311  and the side walls  312  and that is formed with a bottom hole  314 . The trigger-front wall  311  is formed with a front hole  3110 . The release button  5  extends through the front hole  3110  and into the chamber  30  in the operating protrusion  31 , protrudes outwardly and frontwardly of the front hole  3110 , and cooperates with the trigger-front wall  311  to define a step  52  therebetween so that the trigger-front wall  311  is one step below and behind the button-front wall  51 . As such, when the user places his or her two fingers of one hand respectively on the trigger-front wall  311  and the button-front wall  51 , one of the two fingers which is placed on the button-front wall  51  is disposed in front of and one step above the other of the two fingers which is placed on the trigger-front wall  311 . 
     The hand-grip  21  is formed with a stopper  212  that is disposed above the bottom hole  314  in the bottom wall  313  of the operating protrusion  31 , and that is disposed adjacent to a lower end of the window opening  22 . The safety latch  4  is disposed in the operating protrusion  31 , and has a bottom end portion  41  that is disposed adjacent to the stopper  212 . The bottom end portion  41  of the safety latch  4  may contact and be blocked by the stopper  212  when the safety latch  4  is disposed at the locked position and when the trigger piece  3  is disposed at the non-actuating position or may be brought into contact with the stopper  212  when the safety latch  4  is disposed at the locked position and is moved together with the trigger piece  3 , thereby preventing movement of the trigger piece  3  from the non-actuating position to the actuating position, and is disposed above and released from the stopper  212  when the safety latch  4  is disposed at the unlocked position, thereby permitting movement of the trigger piece  3  from the non-actuating position to the actuating position. The bottom end portion  41  extends into the bottom hole  314  when the safety latch  4  is disposed at the locked position, and is disposed above the bottom hole  314  and the stopper  212  when the safety latch  4  is disposed at the unlocked position. 
     The release button  5  has a cam surface  53  that is inclined to the first and second directions (X, Y). The safety latch  4  has a cam follower surface  42  that is inclined to the first and second directions (X, Y). The cam surface  53  is in sliding contact with the cam follower surface  42  for driving movement of the safety latch  4  relative to the trigger piece  3 . 
     The safety latch  4  is formed with a notch  43 , and has an upper end portion  44  that is received in the chamber  30  and that confines a top side of the notch  43 . The release button  5  has a hook-shaped arm portion  54  that extends through the notch  43  and that defines a groove  540 . The upper end portion  44  of the safety latch  4  extends into the groove  540 , and defines the cam follower surface  42 . The arm portion  54  defines the cam surface  53  that confines one side of the groove  540 . 
     The safety latch  4  together with the trigger piece  3  is released from the stopper  212  and the step  52  ceases to exist when the button-front wall  51  is moved to flush substantially with the trigger-front wall  311 . The one-step-behind arrangement between the trigger-front wall  311  and the button-front wall  51  facilitates unlocking and pulling operations of the trigger piece  3 . In addition, the requirement of using two fingers for operating the trigger piece  3  also provides a safety feature for preventing accidental firing due to accidental touching of the trigger-front wall  311  of the trigger piece  3 . 
     The upper end portion  44  of the safety latch  4  is formed with an upper stud  45 . The latch spring  61  is in the form of a coil spring, is mounted on the upper stud  45 , and abuts against the upper end portion  44  and the trigger piece  3 . The trigger spring  62  is in the form of a torsion spring, is mounted on the trigger piece  3 , and abuts against the trigger piece  3  and the hand-grip  21 . 
     By movably mounting the safety latch  4  and the release button  5  on the trigger piece  3  of the nail-driving gun trigger assembly, the aforesaid drawback associated with the prior art can be alleviated. 
     While the present invention has been described in connection with that is considered the most practical 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.