Patent Publication Number: US-2006016844-A1

Title: Fastener driving tool

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a technology of protecting a periphery of an exhaust cover of a fastener driving tool utilizing compressed air or combustion gas.  
      2. Description of the Related Art  
      An exhaust cover is, along a fastener driving direction, projected rearward from a handle portion and therefore, when operation is carried out in a narrow place, the exhaust cover and a top cover attached to the exhaust cover frequently collides with a surrounding. Therefore, it is requested to ensure durability of the exhaust cover and the top cover and reduce a total height of the fastener driving tool by thinning the top cover. A technology of a background art with regard to the exhaust cover and the top cover will be explained as follows.  
      As shown by  FIG. 8 , there is a fastener driving tool provided with a top cover  2  formed by a thin plate made of iron to be flush with an exhaust cover  3  such that an exhaust port  8  is projected.  
      JP-A-11-129167 is described as follows. A main body and an exhaust cover can be protected by providing a top cover comprising hard rubber or the like to cover substantially a total periphery of the exhaust cover.  
      Japanese Patent No. 3397040 is described as follows. By providing a protection cover made of rubber to cover a total of an exhaust cover, a main body can be prevented from being impaired.  
     SUMMARY OF THE INVENTION  
      According to the constitution of  FIG. 8 , the projected exhaust port  8  is liable to be caught by a surrounding and there is a case in which a root portion of the top cover is concentrated with a bending load to be destructed. Further, when the top cover  2  collides with the surrounding, an impact stress is generated between the top cover  2  and the exhaust cover  3 . Further, in fastening operation, there is a case in which in accordance with rapidly displacing the fastener driving tool by reaction, the top cover  2  is deformed by an inertia force, strong chattering (repetition of impact) is brought about between the top cover  2  and the exhaust cover  3  to destruct the exhaust cover  3 . Further, according to the constitution of  FIG. 8 , there is a case in which a gap other than the exhaust port  8  is produced between the top cover  2  and the exhaust cover  3  and compressed air is leaked from the gap.  
      According to the constitutions of JP-A-11-129167 and Japanese Patent No. 3397040, there is a case in which when the exhaust cover comprising rubber (or protection cover) collides with, for example, a sharp member, the exhaust cover is bored with a hole or cut. Further, a total height of the fastener driving tool is increased by setting the thickness to be large in order to ensure strength.  
      It is an object of the invention to provide a fastener driving tool resolving the above-described drawbacks of the background art, having high durability, and having a thin protection cover without leaking exhaust compressed air from other than an exhaust port.  
      In a fastener driving tool including a barrel portion substantially in a cylindrical shape extended in an up and down direction, an nose portion extended from the barrel portion to a lower side, a handle portion extended from the barrel portion substantially in a side direction, an exhaust path which is an exhaust path provided at an upper portion of the barrel portion for communicating inside of the barrel portion and the atmosphere, and a top cover for covering the exhaust path, the fastener driving tool is constituted such that the top cover is made of a metal and is provided with substantially a bowl-like shape extended from an upper side of the barrel portion in a side direction. When constituted in this way, since the top cover is made of a metal, even when the top cover is thin, strength thereof can be ensured. Further, since the top cover is substantially constituted by the bowl-like shape, an edge thereof is not projected in a side direction and therefore, even when the top cover collides with a surrounding, the top cover is not caught thereby, stresses are not concentrated and the top cover is difficult to be destructed. Therefore, durability of the top cover can be promoted and a thickness thereof can be thinned.  
      Further, the fastener driving tool is constituted to include a damping member comprising an elastic member between the top cover and the barrel portion. When constituted in this way, the top cover and an outer frame portion can be prevented from colliding with each other. Therefore, durability of the top cover can be promoted.  
      Further, an expansion chamber constituting a space for communicating with the exhaust path and the exhaust port communicating with the atmosphere from the expansion chamber are provided between the barrel portion and the top cover, and the damping member is provided to be pinched with an exposed thread at a surrounding of the expansion chamber. When constituted in this way, a gap is not produced at other than the exhaust port between the top cover and the barrel portion. Therefore, exhaust compressed air can be prevented from being leaked from other than the exhaust port.  
      Further, the damping member is constituted to include a first hole portion penetrated at a portion thereof opposed to the expansion chamber. When constituted in this way, a pressure difference between upper surface and lower surface of the damping member is reduced and the damping member can be prevented from being deformed excessively.  
      Further, the top cover is constituted such that the top cover includes an attaching seat portion brought into contact with the barrel portion and the top cover and the barrel portion are connected by a bolt at the attaching seat portion. When constituted in this way, the top cover can firmly be fixed while maintaining the exposed thread of the damping member constant.  
      Further, the damping member is constituted to include a second hole portion engaged with the attaching seat portion. When constituted in this way, the top cover is firmly positioned.  
      According to the invention, there can be provided the fastener driving tool having high durability, and including a protection cover having a thin thickness without leaking exhaust compressed air from other than the exhaust port. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a sectional view of a total structure of a fastener driving tool according to an embodiment of the invention;  
       FIG. 2  is a front view of an essential portion of the fastener driving tool according to the embodiment of the invention;  
       FIG. 3  is a left side view of an essential portion viewed from B direction of  FIG. 1 ;  
       FIG. 4  is a view enlarging portion A of  FIG. 1 ;  
       FIG. 5  is a view showing a state of deforming a protection cover to an upper side in  FIG. 4 ;  
       FIG. 6  is a view showing a state of deforming the protection cover to a lower side in  FIG. 4 ;  
       FIG. 7  is a disassembled perspective view of an essential portion of the fastener driving tool according to the embodiment of the invention; and  
       FIG. 8  is a sectional view of a structure of an essential portion showing an example of a fastener driving tool of a background art. 
    
    
     DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENTS  
      A fastener driving tool according to an embodiment of the invention will be explained in reference to  FIG. 1  through  FIG. 7 .  
      An top cover  25  will be explained in reference to  FIG. 2 ,  FIG. 4  and  FIG. 7 .  
      As shown by  FIG. 7 , the top cover  25  is formed substantially in a bowl-like shape by pressing a stainless steel plate having a thickness of 1.2 mm. As shown by  FIG. 4 , the top cover  25  is projected with an attaching seat portion  25   a  brought into contact with the exhaust cover  3 . Also a side of the exhaust cover  3  is projected with an attaching seat portion  3   b  at a position in correspondence with the attaching seat portion  25   a , and the attaching seat portion  3   b  is provided with a screw hole  3   c . By inserting a bolt  4  through the bolt hole  25   b  to be screwed with the screw hole  3   c , the top cover  25  is attached to the exhaust cover  3  such that the attaching seat portion  25   a  and the attaching seat portion  3   b  are brought into contact with each other. As shown by  FIG. 2 , the top cover  25  is extended to cover from an upper face to a side face of the exhaust cover  3 , and covers four pieces of bolts  30  for fastening the exhaust cover  3  and a barrel portion  26   a  of a body  26  constituting an outer frame portion.  
      The top cover  25  is made of a metal and therefore, even when the top cover  25  is thinned more than that made of rubber, strength thereof can be ensured. The top cover is constituted substantially by the bowl-like shape, an end portion thereof is formed to be in line with the exhaust cover  3 , there is not a portion considerably projected to an outer side and therefore, when the top cover  25  interferes with a surrounding, the top cover  25  is not caught thereby. The end portion of the top cover is extended to cover the bolts  30  and therefore, the bolt  30  is not seen from outside and an outlook of the fastener driving tool  1  is promoted.  
      A damping member  27  is pinched between the exhaust cover  3  and the top cover  25 . The damping member  27  is constituted by rubber having a thickness of 1 mm and is pinched therebetween with an exposed thread of 0.4 mm. Further, a portion of the damping member  27  in correspondence with the attaching seat portion  3   b  is provided with a locking hole  27   a  constituting a second hole portion to be engaged with the attaching seat portion  3   b . A vicinity of the locking hole  27   a  is provided with a vent hole  27   b  constituting a first hole portion for communicating a face of the damping member  27  on a side of the exhaust cover  3  and a face thereof on a side of the top cover  25 .  
      An upper end face  3   a  of the exhaust cover  3  is recessed with an expansion chamber  7  for gradually lowering pressure of compressed air to be exhausted. Inside of the expansion chamber  7  is provided with an air path  6  for communicating inside of the fastener driving tool  1  and the expansion chamber  7 . A portion in a peripheral direction of the expansion chamber  7  is recessed with an exhaust port  8  for communicating inside of the expansion chamber  7  and the atmosphere. A plurality of ribs  3   d  are projected from a bottom portion to an upper side of the expansion chamber  7  to extend to a height substantially the same as that of the upper end face  3   a . The damping member  27  is pinched between the upper end face  3   a  of the exhaust cover  3  and the ribs  3   d  and the top cover  25  with an exposed thread such that a gap is not produced at other than the exhaust port  8 .  
      Operation of the fastener driving tool  1  will be explained in reference to  FIG. 1 .  
      There is shown a state in which a main body of the fastener driving tool  1  is connected with an air hose, not illustrated, to store compressed air. Compressed air is stored in a pressure accumulating chamber  12 .  
      When a trigger valve  15  is made ON by executing both of operation of pulling a trigger  13  and operation of pressing a push lever  14  to wood  11 , a main valve  16  is moved to an upper side, and the pressure accumulating chamber  12  and an upper side of a piston  18  are communicated with each other. Further, the pressure accumulating chamber  12  and the air path  6  are blocked from each other.  
      The piston  18  strikes a nail  19  to the wood  11  while rapidly moving to a side of a lower dead center by compressed air flowing from the pressure accumulating chamber  12  to an upper side of the piston  18  in the cylinder  17 . Air on a lower side of the piston  18  in the cylinder  17  flows into a returning chamber  21  via an air path  20 , and when the piston  18  passes through an air path  22 , a portion of compressed air on the upper side of the piston  18  flows into the returning chamber  21  via the air path  22 . The piston  18  collides with a piston bumper  23  at the lower dead center, and extra energy of the piston  18  is absorbed by deforming the piston bumper  23 .  
      A state of the top cover  25  and the damping member  27  in striking operation will be explained in reference to  FIG. 1 ,  FIG. 4  and  FIG. 6 .  
      As shown by  FIG. 1 , when the piston  18  collides with the piston bumper  23 , the fastener driving tool  1  is rapidly displaced to pivot in an arrow mark E direction centering on a point D of a handle portion  26   b . At this occasion, the top cover  25  is operated with an inertia force, and as shown by an arrow mark in  FIG. 5 , a surrounding of the attaching seat portion  25   a  is rapidly displaced to an upper side. Thereafter, the fastener driving tool  1  is going to be back to original state by a force of the hand holding the handle portion  16   b . At this occasion, the top cover  25  is operated with an inertia force again, and as shown by an arrow mark in  FIG. 6 , the surrounding of the attaching seat portion  25   a  is displaced to the lower side. Although according to the fastener driving tool of the background art, repetition of the rapid displacements brings about chattering (repetition of impact) between the top cover  25  and the exhaust cover  3 , according to the embodiment, the damping member  27  prevents the top cover  25  and the exhaust cover from colliding with each other and damps vibration of the top cover  25 . Further, the damping member  27  is pinched between the top cover  25  and the exhaust cover  3  with an exposed thread and therefore, even in a state in which a portion of the top cover  25  is displaced in a direction of being remote from the exhaust cover  3 , contact between the damping member  27  and the top cover  25  is maintained, and the damping member  27  can effectively damp the vibration. Further, the damping member  27  can damp an impact force exerted to the top cover  25  not only in the striking operation but also when the top cover  25  collides with a surrounding.  
      When the trigger valve  15  is made OFF by returning the trigger  13  or stopping operation of pressing the push lever  14  to the wood  11 , the main valve  16  is moved to a lower side.  
      The main valve  16  is closed, the pressure accumulating chamber  12  and the upper side of the piston  18  in the cylinder  17  are blocked from each other, and the upper side of the piston  18  in the cylinder  17  communicates with the atmosphere by disengagement of the main valve  16  and an exhaust rubber  24 . The lower side of the piston  18  is pressed by compressed air accumulated in the returning chamber  21  and the piston  18  is moved rapidly to a side of an upper dead center. Compressed air on the upper side of the piston  18  is exhausted to the atmosphere from the exhaust port  8  by way of the air path  6  and the expansion chamber  7  to return to an initial state.  
      Although at this occasion, compressed air on the upper side of the piston  18  in the cylinder  17  after striking the nail  19  flows into the expansion chamber  7  by way of the air path  6  and thereafter exhausted to the atmosphere from the exhaust port  8 , the damping member  27  is pinched therebetween such that the gap is not produced at other than the exhaust port  8  and therefore, compressed air is not leaked from a gap. Further, compressed air flowing to the expansion chamber  7  also flows to between the top cover  25  and the damping member  27  by way of the vent hole  27   b  and therefore, a pressure difference is not produced between upper surface and lower surface of the damping member  27 . Therefore, a large force is not exerted to the damping member  27 , and the damping member  27  is not vibrated to destruct, or strange sound is not emitted by vibration.  
      The above-described is a stroke of striking a single piece of the nail  19  to the wood  11 .