Patent Publication Number: US-8109425-B2

Title: Shooting mode switch control mechanism for nail gun

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to nail guns and more particularly, to a shooting mode switch control mechanism for use in a nail gun. 
     2. Description of the Related Art 
     To fit different working requirements, a nail gun is generally equipped with a shooting mode switch control mechanism for allowing switching between a single-shooting mode and a continuous-shooting mode. 
     When the shooting mode control switch mechanism is switched to the single-shooting mode, the operator must stop the safety bar of the nail gun against the workpiece and then press the trigger to activate an air-valve switch for firing a nail. For firing a next nail, the operator must release the trigger and then press the trigger again. When the shooting mode control switch mechanism is switched to the continuous-shooting mode, the operator must keep the trigger in the pressed position and then continuously strike the safety bar against the workpiece, causing the air-valve switch to be triggered to fire nails continuously. 
     However, the shooting mode control switch mechanism is normally set adjacent to the trigger to facilitate switching by the operator. However, the design of a shooting mode control switch mechanism in a nail gun must consider the factors of manipulation, linkage and installation position. In consequence, regular shooting mode control switch mechanisms commonly have the drawbacks of large size and complicated structure. 
     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 shooting mode switch control mechanism for use in a nail gun, which has the characteristic of compact structure. 
     To achieve this and other objects of the present invention, a shooting mode switch control mechanism comprises a trigger, a stop member, a spring member and a switch. The trigger is pivotally mounted in the gun body of a nail gun. The stop member is pivotally mounted in the trigger of the nail gun, having a first end portion and a second end portion disposed at two opposite sides relative to the pivoted area between the stop member and the trigger. The spring member is mounted in the gun body at the side of the second end portion of the stop member. The spring member is stopped against the second end portion of the stop member to impart a spring force to the trigger through the stop member for biasing the trigger in direction away from the air-valve switch. The switch is pivotally mounted in the trigger at the side of the first end portion of the stop member and switchable between a single-shooting position and a continuous-shooting position. When the switch is in the single-shooting position and the trigger is pressed, the second end portion of the stop member is kept beyond the moving path of the safety bar. When the switch is in the single-shooting position and the trigger is released, the second end portion of the stop member is forced by the spring member into the moving path of the safety bar and pushable by the safety bar for enabling the stop member to activate the air-valve switch once each time the trigger is pressed. When the switch is in the continuous-shooting position, the first end portion of the stop member is stopped against the switch for enabling the second end portion of the stop member to be continuously pushed by the safety bar to activate the air-valve switch continuously. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of a part of a nail gun, illustrating a shooting mode control switch mechanism installed in the gun body in accordance with the present invention. 
         FIG. 2  is an exploded view of the shooting mode control switch mechanism in accordance with the present invention. 
         FIG. 3  is a sectional view of the present invention, illustrating the switch in the single-shooting position and the safety bar kept away from the workpiece. 
         FIG. 4  is similar to  FIG. 3 , illustrating the stop member pushed by the safety bar. 
         FIG. 5  is similar to  FIG. 4 , illustrating the status after press of the trigger. 
         FIG. 6  is similar to  FIG. 5 , illustrating the status after release of the trigger. 
         FIG. 7  is similar to  FIG. 3 , illustrating the status after the switch moved to the continuous-shooting position. 
         FIG. 8  is similar to  FIG. 7 , illustrating the trigger held in the pressed position before movement of the second end portion of the stop member by the safety bar. 
         FIG. 9  is similar to  FIG. 8 , illustrating the second end portion of the stop member pushed by the safety bar. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1˜3 , a shooting mode switch control mechanism  20  used in a nail gun  10  in accordance with the present invention is shown comprising a trigger  30 , a stop member  40 , a spring member  50  and a switch  60 . 
     The trigger  30  has a bottom wall  32 , two opposing sidewalls  34 , and two stop flanges  322  respectively protruded from the sidewalls  34 . A pivot pin  36  is inserted through the two sidewalls  34  to pivotally connect the trigger  30  to the gun body  12  of the nail gun  10 . Further, each sidewall  34  has a first hole  342  and a second hole  344 . 
     The stop member  40  is pivotally connected between the two sidewalls  34  of the trigger  30  by a pivot pin  42 , i.e., the stop member  40  has a first end portion  44  disposed at the left side relative to the pivot pin  42  and a second end portion  46  disposed at the right side relative to the pivot pin  42 . 
     The spring member  50  is a torsional spring wound round an axle  52  in the gun body  12  and secured thereto. The spring member  50  is disposed at the right side relative to the stop member  40 , having the two distal ends thereof respectively stopped against the gun body  12  and the middle part thereof stopped against the second end portion  46  of the stop member  40  to impart a spring force to the stop member  40 , causing the stop member  40  to bias the trigger  30  in direction toward an air-valve switch  16  far from the nail gun  10 , i.e., the stop member  40  and the trigger  30  use the common spring member  30  to achieve a pivot function. 
     The switch  60  is pivotally connected between the two sidewalls  34  of the trigger  30  by a pivot pin  62  and disposed at the left side relative to the stop member  40 , having a retaining portion  64 , a first lever  66  and a second lever  68  radially extended from its center of rotation. The retaining portion  64  has two notches  642  and is divided by the two notches  642  into one first block  644  and two second blocks  646 . Subject to the design of the notches  642 , each second block  646  is elastically deformable when compressed. Further, each second block  646  has a raised spot  648  located from the end face thereof. By means of deforming the second blocks  646 , the raised spots  648  can be selectively engaged into the respective first holes  342  or second holes  344  of the trigger  30 . When the raised spots  648  are engaged into the first holes  342  of the trigger  340 , the switch  60  is kept in a single-shooting position P 1 , as shown in  FIG. 3 , where one side of the first lever  66  of the switch  60  is stopped against the stop flanges  322  of the trigger  30 , assuring positive engagement between the raised spots  648  and the first holes  342 . At this time, the second end portion  46  of the stop member  40  is stopped at the bottom wall  32  of the trigger  30  and the first end portion  44  of the stop member  40  is spaced from the switch  60  by a gap, avoiding accidental triggering of the switch  60 . In another word, the stop design of the said stop flanges  322  or the said bottom wall  32  prohibits the switch  60  from being forced by the first end portion  44  of the stop member  40  to switch the position accidentally. When the raised spots  648  are engaged into the second holes  344  of the trigger  340 , the switch  60  is kept in a continuous-shooting position P 2 , as shown in  FIG. 7 , where one side of the retaining portion  64  of the switch  60  is stopped against the stop flanges  322  of the trigger  30 , assuring positive engagement between the raised spots  648  and the second holes  344 . At this time, the first end portion  44  of the stop member  40  is stopped against the switch  60 , and the action force thus produced from stopping the first end portion  44  against the switch  60  goes through the center of rotation of the switch  60 , prohibiting the switch  60  from being forced by the first end portion  44  of the stop member  40  to switch the position accidentally. At this time, the second end portion  46  of the stop member  40  is spaced from the bottom wall  32  of the trigger  30  by a gap. Further, the first lever  66  extends out of the trigger  30  when the switch  60  is kept in the continuous-shooting position P 2 , allowing operation by an external force to switch the switch  60  from the continuous-shooting position P 2  to the single-shooting position P 1 . The second lever  68  extends out of the trigger  30  when the switch  60  is kept in the single-shooting position P 1 , allowing operation by an external force to switch the switch  60  from the single-shooting position P 1  to the continuous-shooting position P 2 . 
     After understanding of the structural details of the shooting mode switch control mechanism  20 , the operation and features of the invention are outlined hereinafter. 
     When the operator wishes to drive nails into the workpiece by means of the single-shooting mode, operate the first lever  66  of the switch  60  to switch the switch to the single-shooting position P 1 , as shown in  FIG. 3 , and then stop the safety bar  14  of the nail gun  10  against the workpiece, causing the safety bar  14  to be moved upwards. Thereafter, push the second end portion  46  of the stop member  40  during upward movement of the safety bar  14 , as shown in  FIG. 4 , and then operate the trigger  30  to force the stop member  40  against the air-valve switch  16 , firing a nail, as shown in  FIG. 5 . Upon finish of one shooting action, the gun body  12  is lifted due to the impact of the nail against the workpiece, and the safety bar  14  is moved away from the workpiece to the initial position. At this time, the push force is released from the second end portion  46  of the stop member  40 , and the stop member  40  is returned to its former position by the spring member  50 . Under this condition, even if the operator presses the trigger  30  and stops the safety bar  14  against another location of the workpiece, the second end portion  46  of the stop member  40  will not be pushed by the safety bar  14 , as shown in  FIG. 6 , and the air-valve switch  16  will not be activated by the stop member  40 , avoiding accidental triggering. In another word, the operator must remove the safety bar  14  from the workpiece and release the trigger  30  and then repeat the aforesaid procedure for allowing firing of a nail again. 
     On the other hand, when the user swishes to drive nails into the workpiece by means of the continuous-shooting mode, operate the second lever  68  of the switch  60  to switch the switch to the continuous-shooting position P 2 , as shown in  FIG. 8 . At this time, the first end portion  44  of the stop member  40  is stopped by the switch  60 , the biasing angle of the stop member  40  is limited, and the second end portion  46  of the stop member  40  is kept in the moving path of the safety bar  14 . Thereafter, the operator can continuously strike the safety bar  14  against the workpiece at other locations. Each time the operator strikes the safety bar  14  against the workpiece, the second end portion  46  of the stop member  40  is pushed by the safety bar  14  once, and therefore the stop member  40  can activate the air-valve switch  16  continuously to achieve continuous shooting of nails, as shown in  FIG. 9 . 
     In conclusion, the shooting mode switch control mechanism of the invention uses a lever function stop member to match with the position change of a switch at the left side relative to the stop member for controlling the biasing angle of the stop member to achieve switching between a single-shooting mode and a continuous-shooting mode. The use of one single spring member at the right side relative to the stop member is sufficient to provide the necessary return force for returning the stop member and the trigger. Therefore, the invention has the characteristics of compact structure and accurate action. 
     Although a particular embodiment of the invention has 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.