Patent Publication Number: US-6659324-B1

Title: Single-firing trigger mechanism for a nailing machine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an improved structure of a trigger of a nailing machine, and more particularly, for exactly reaching the single-firing effect. 
     2. Description of the Related Art 
     Nailing machines can be very dangerous tools. The operation thereof must be very careful in order not to injure persons around the working place. As shown in FIGS. 7 and 8, the trigger mechanism  20  of a conventional nailing machine  10  includes a trigger  21 , a torsion spring  22 , a slide piece  23  and a spring  24 . Under normal operation, a safety lever  12  at the front end of gun mouth  11  has to be compressed against a workpiece (not shown) for shifting the safety lever  12  inwardly and, therefore, the other end  13  thereof is pressed against the torsion spring  22  to be shifted backwards. At that time, the other end  221  of the torsion spring  22  presses the slide piece  23  to be shifted downwardly (see FIG.  9 ). When the slide piece  23  is moved downwards, a position difference is created between a deep hole  231  adjacent to the middle part of the slide piece  23  and a firing pin  14 . By pressing down the trigger  21 , a single-firing effect is reached. Under the precondition that the safety lever  12  is not moved inwardly, the firing pin  14  can extend into the deep hole  231  of the slide piece  23  (see FIG. 11) when the operator presses down the trigger  21 . Therefore, the safety effect to prevent from firing is reached. 
     Referring to FIG. 10, the trigger is in a compressed state after firing. If the operator unintentionally cause the safety lever  12  to be in contact with any object, an unexpected nailing effect is also created since the slide piece  23  is situated in the compressed state, too. In other words, the spring  24  can&#39;t move the slide piece  23  upwardly to the safety position due to the continuous frictional relationship between the slide piece  23  and the firing pin  14 , thereby leading to tremendous operational danger. 
     SUMMARY OF THE INVENTION 
     It is a primary object of the present invention to remove the above-mentioned drawbacks and to provide a safer trigger mechanism. After completion of an expected single firing operation, the contact piece touching the firing pin can be automatically removed from or spring away from the safety level. Under the precondition that the trigger is not released in place, the next firing operation is disabled no matter which object the safety lever touches, unless the trigger is released in place according to standard operational procedure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accomplishment of this and other objects of the invention will become apparent from the following description and its accompanying drawings of which: 
     FIG. 1 is a perspective exploded view of a trigger mechanism in accordance with the invention; 
     FIG. 2 is a sectional view of the assembled trigger mechanism in accordance with FIG. 1, which is attached to the nailing machine; 
     FIG. 3 is a sectional view of the assembled trigger mechanism in accordance with FIG. 2, wherein a safety lever touches a contact piece while the trigger is not pressed down; 
     FIG. 4 is a sectional view of the assembled trigger mechanism in accordance with FIG. 3, wherein the trigger is compressed for performing the firing operation; 
     FIG. 5 is a sectional view of the assembled trigger mechanism in accordance with FIG. 4, wherein the contact piece is removed from the safety lever and the trigger is situated in a compressed state; 
     FIG. 6 is a sectional view of the assembled trigger mechanism in accordance with FIG. 2, wherein the trigger is compressed without obedience to the standard operational procedure; 
     FIG. 7 is a side view of a conventional single-firing nailing machine with a trigger mechanism in a sectional view; 
     FIG. 8 is a sectional view of the trigger mechanism in accordance with FIG. 7, wherein the safety lever touches the torsion spring while the trigger is still not compressed; 
     FIG. 9 is a sectional view of the trigger mechanism in accordance with FIG. 8, wherein the trigger is compressed for performing the firing operation; 
     FIG. 10 is a sectional view of the trigger mechanism in accordance with FIG. 9, wherein the trigger is situated in the compressed state and an unexpected firing action is performed; and 
     FIG. 11 is a sectional view of the trigger mechanism in accordance with FIG. 7, wherein the trigger is compressed without obedience to the standard operational procedure. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     First of all, referring to FIGS. 1 and 2, the trigger mechanism  40  of the nailing machine  30  in accordance with the invention includes a trigger  41 , a swiveling element  45  and a contact element  44 . 
     The trigger  41  is positioned in front of the firing pin  31  and pivotally connected by a positioning shaft  42  to the nailing machine  30 . Moreover, the trigger  41  has a receptacle  43  facing the firing pin  31  for receiving the contact element  44  and the swiveling element  45 . An annular slot  46  and a borehole  47  are formed at each side of the trigger  41 . 
     The swiveling element  45  is pivotably connected within the receptacle  43  of the trigger  41  by means that a second positioning shaft  48  passes through the boreholes  47  and two first holes  451  at both side plates of the swiveling element  45 . An annular member  452  in contact with a vertical surface of the nailing machine  30  is formed at one end of each side plate of the swiveling element  45  while two second holes  453  are formed adjacent to the first holes  451  and aligned with the annular slot  46  of the trigger  41 . 
     The contact element  44  is pivotally connected to the second holes  453  of the swiveling element  45  through a third positioning shaft  49  and a torsion spring  50  in a manner that the top end  441  of the contact element  44  is located at a height in contact with a safety lever  32 . The third positioning shaft  49  is movably disposed within the annular slot  46  of the trigger  41 . 
     After assembly of the above-mentioned members, as shown in FIGS. 2,  3  and  4 , and after execution of the standard operational procedure, the safety lever  32  is extended into the inside of the trigger  41  and pressed against the contact element  44  so as to be shifted in the direction of the firing pin  31 . Thereafter, the user can press down the trigger  41  again, thereby causing the contact element  44  to be in contact of the firing pin  31  for the next single-firing operation. 
     Now, referring to FIG. 5, the contact element  44  is removed from the safety lever  32  due to the downward movement of the whole trigger mechanism  40 . Furthermore, it springs away by means of the resilient force of the torsion spring  50 . Therefore, the expected effect of the single-firing operation can be reached. Moreover, the safety in use can be ensured. 
     If the operator compresses the trigger without obedience to the standard operational procedure, the trigger mechanism  40  will be shifted downward. Besides, the safety lever  32  can&#39;t touch the top end  441  of the contact element  44  so that the nailing operation fails. 
     Many changes and modifications in the above-described embodiment of the invention can, of course, be carried out without departing from the scope thereof accordingly, to promote the progress in science and the useful arts, the invention is disclosed and is intended to be limited only by the scope of the appended claim.