Abstract:
A pneumatic nailer for use with a high pressure fluid source is disclosed. The pneumatic nailer includes a housing defining a storage chamber positionable in fluid communication with the high pressure fluid source, a cylinder positioned within said housing, a piston having a piston head, said piston head being movable within said cylinder, said cylinder and said piston head defining a return chamber on side of said piston head, a sleeve movable with respect to said cylinder between a first sleeve position and a second sleeve position, said sleeve and said cylinder defining a sleeve space therebetween, wherein, when said sleeve is positioned in said first sleeve position, said sleeve space is isolated from fluid communication with said return chamber, and wherein, when said sleeve is positioned in said second sleeve position, said sleeve space is positioned in fluid communication with said return chamber.

Description:
FIELD 
       [0001]    The present invention generally relates to pneumatic tools and more particularly to a pneumatic nailer. 
       BACKGROUND 
       [0002]    Pneumatic tools are commonly used in the construction industry. In particular, pneumatic nailers are regularly used in roofing and framing projects. In a standard setting, a pneumatic nailer is coupled to a source of high pressure air, e.g., a portable compressor, to supply the pneumatic nailer with a source of pressure regulated compressed air. The pneumatic nailer is usually equipped with an elongated magazine that holds a plurality of nails. The nails are usually available in strips, whereby the nails are uniformly spaced apart from each other and are loosely connected to each other by a clip made from a thin layer of plastic or paper, or are simply connected to each other by a resin-type material. In another form, the nails are provided in a coil that is insertable into a round magazine. Once a worker at the construction site places a strip of nails into the magazine and couples the nailer to the high pressure source, the nailer is ready for operation. 
         [0003]    The pneumatic nailer is equipped with an ejector assembly which includes a spring loaded safety tip. A nail from the strip of nails that is placed inside the magazine is internally situated adjacent to the tip of the ejector assembly. The operator places the tip of the ejector assembly against a workpiece to depress the tip. Once the tip is depressed, the nailer becomes responsive to force applied to a trigger. When force is applied to the trigger by the operator, the nailer activates a pneumatic actuating mechanism inside the nailer. The pneumatic actuating mechanism includes a ramming member which is plunged at a high velocity toward the nail from a ready position. The ramming member strikes the nail causing the nail to disengage from the strip of nails, exit through the ejector assembly, and drive into the workpiece. Once the operator releases the trigger, the pneumatic actuating mechanism quickly returns the ramming member to the ready position, and remains there until force is again applied to the trigger by the operator. 
         [0004]    During the above operation, the nailers of the prior art provide compressed air to several chambers in order to activate the actuating mechanism as well as to return the actuating mechanism to its ready position. The compressed air is often released to atmosphere after it has performed its intended purpose, e.g., activate the actuating mechanism or return the ramming member. Therefore, several volumes of compressed air perform mechanical work in respective chambers, before being released to atmosphere. As a result, the compressed air leads to power cycling of the compressor, which not only uses power but also shortens the life of the compressor. In addition, some prior art nailers include return mechanisms which are relatively slow to return the ramming member to its ready position. This results in slower tool speed. 
         [0005]    Therefore, there is a need for a pneumatic nailer that can recycle compressed air for performing some of its functions during activation of its actuating mechanism and returning the actuating mechanism to the ready position responsive to the worker pulling and releasing the trigger. There is also a need to improve the speed at which the ramming member is returned to the ready position, which would result in faster tool speed. 
       SUMMARY 
       [0006]    In accordance with one embodiment of the present disclosure there is provided a pneumatic nailer for use with a high pressure fluid source. The pneumatic nailer includes a housing defining a storage chamber positionable in fluid communication with the high pressure fluid source, a cylinder positioned within said housing. The pneumatic nailer further includes a piston having a piston head and a driver member extending from said piston head, said piston head being movable within said cylinder, said cylinder and said piston head defining (i) a displacement chamber on a first side of said piston head, and (ii) a return chamber on an opposite second side of said piston head. The pneumatic nailer also includes a sleeve movable with respect to said cylinder between a first sleeve position and a second sleeve position, said sleeve and said cylinder defining a sleeve space therebetween, wherein, when said sleeve is positioned in said first sleeve position, (i) said sleeve space is isolated from fluid communication with said return chamber, and (ii) said return chamber is positioned in fluid communication with atmosphere, and wherein, when said sleeve is positioned in said second sleeve position, (i) said sleeve space is positioned in fluid communication with said return chamber via, and (ii) said return chamber is isolated from fluid communication with atmosphere. Furthermore, the pneumatic nailer includes a valve movable between (i) a first valve state in which said displacement chamber is isolated from fluid communication with said storage chamber and positioned in fluid communication with atmosphere, and (ii) a second valve state in which said displacement chamber is positioned in fluid communication with said storage chamber and isolated from fluid communication with atmosphere. The pneumatic nailer also includes an actuator positionable between an actuated position and a deactuated position, wherein (i) when said actuator is positioned in said actuated position, said valve is caused to move to said first valve state and said sleeve is caused to move to said first sleeve position, and (ii) when said actuator is positioned in said deactuated position, said valve is caused to move to said second valve state and said sleeve is caused to move to said second sleeve position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings. 
           [0008]      FIG. 1  depicts a cross sectional view of a pneumatic nailer of the present disclosure shown in a deactuated position; 
           [0009]      FIG. 2  is a view similar to  FIG. 1 , but showing the pneumatic nailer in a transitional state immediately after the pneumatic nailer has been placed in an actuated position; 
           [0010]      FIG. 3  is a view similar to  FIG. 2 , but showing the pneumatic nailer in a steady-state of the actuated position; 
           [0011]      FIG. 4  is a view similar to  FIG. 3 , but showing the pneumatic nailer in an initial transitional state immediately after the pneumatic nailer has been placed in the deactuated position after having been in the actuated position; and 
           [0012]      FIG. 5  is a view similar to  FIG. 4 , but showing the pneumatic nailer in another transitional state at a short time after the pneumatic nailer has been placed in the deactuated position after having been in the actuated position. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one of ordinary skill in the art to which this invention pertains. 
         [0014]    Referring to  FIG. 1 , a pneumatic nailer  100  according to the present disclosure is depicted. The pneumatic nailer  100  includes a housing  102 , a compressed air coupling member  103 , a trigger  104 , a trigger valve  106 , a cylinder  108 , a piston  110 , a main valve  112 , a sleeve  114 , and a biasing member  116 . The pneumatic nailer  100  also includes several chambers including a sleeve chamber  118 , a main valve chamber  120 , a storage chamber  122 , a sleeve space  124 , a return chamber  126 , and a displacement chamber  128 . The pneumatic nailer  100  also includes several air passages including fluid passages  129 , vent ports  132 , bidirectional ports  134 , and a fluid passage  136 . The pneumatic nailer  100  also includes a flexible bumper  138 . The housing  102  includes a handle  105 . 
         [0015]    A high pressure fluid source FS, such as a portable air compressor, includes a coupling member (not shown) that cooperates with the coupling member  103  so as to place the high pressure fluid source FS in fluid communication with the pneumatic nailer  100 . The compressed air coupling member  103  is disposed at an end of the handle  105  and is in continuous fluid communication with the storage chamber  122 . The storage chamber  122  internally extends from a cavity in the handle  105  to a cavity adjacent to the cylinder  108 . The trigger  104  is positionable in two positions. The first position is referred to as an actuated position and the second position is referred to as a deactuated position. The trigger valve  106  is also positionable in an actuated position and in a deactuated position. The trigger  104  is biased by a spring  107  to urge toward the deactuated position. Movement of the trigger  104  from its deactuated position to its actuated position causes the trigger valve  106  to move from its deactuated position to its actuated position. 
         [0016]    The trigger valve  106  is in fluid communication with the sleeve chamber  118  and the main valve chamber  120 . The sleeve chamber  118  and the main valve chamber  120  are in continuous fluid communication with each other. In the actuated position of the trigger valve  106 , the trigger valve  106  is positioned to place the combination of sleeve chamber  118  and the main valve chamber  120  in fluid communication with atmosphere, i.e., allows fluid that is held in these chambers to escape to atmosphere thereby equalizing the pressure in these chambers with atmospheric pressure. In contrast, in the deactuated position, the trigger valve  106  is positioned to place the combination of sleeve chamber  118  and the main valve chamber  120  in fluid communication with the storage chamber  122 . The piston  110  includes a piston head  111  and a drive member  113  that is coupled to the piston head  111 . The main valve  112  includes the fluid passage  136  which is centrally located in the main valve  112 . The main valve also includes sealing members  150  and  152 . 
         [0017]    The cylinder  108  is fixedly disposed inside the housing  102 . The piston head  111  is moveably disposed inside the cylinder  108 . The main valve  112  is moveably disposed inside a back portion of the housing  102 . The sealing member  152  is disposed around the main valve  112  and seals the valve against the housing  102 . 
         [0018]    The main valve  112  is configured to move from a first position to a second position. In the first position, referred to as a deactuated position, the main valve  112  is in contact with the cylinder  108 , and thereby seals the cylinder from fluid communication with the storage chamber  122  with the sealing member  150 . The deactuated position of the main valve  112  is depicted in  FIG. 1 . The fluid passage  136  couples the piston side of the main valve  112  to atmosphere when the main valve  112  is in the deactuated position. The second position, referred to as an actuated position, is defined by the main valve  112  having moved out of contact with the cylinder  108  in a direction designated by an arrow B. In this position, the main valve  112  is positioned to place the cylinder in fluid communication with the storage chamber. Also, in the actuated position the fluid passage  136  is not in fluid communication with atmosphere. 
         [0019]    The main valve  112  has two opposing activation surfaces  112 A and  112 B. The activation surface  112 A is in continuous fluid communication with the main valve chamber  120 . The activation surface  112 B is in continuous fluid communication with the storage chamber  122 . The activation surface  112 A is larger in area than the activation surface  112 B. When the main valve chamber  120  is in fluid communication with atmosphere, i.e., when the trigger valve  106  is in the actuated position, a negligible force is acting on the activation surface  112 A. Meanwhile, a force F 112B , i.e., pressure inside the storage chamber multiplied by the area of the activation surface  112 B, is acting on the activation surface  112 B in a direction of the arrow B. The force F 112B  causes the main valve  112  to move in the direction of the arrow B. When the main valve chamber  120  is in fluid communication with the storage chamber  122 , i.e., when the trigger valve  106  is in the deactuated position, a force F 112A , i.e., pressure inside the main valve chamber  120  multiplied by the area of the activation surface  112 A, is acting on the activation surface  112 A in the direction of an arrow A. The same force F 112B  is continuing to act on the activation surface  112 B in the direction of the arrow B. However, since the activation surface  112 A is larger than the activation surface  112 B, the force F 112A  is also larger than the force F 112B . The difference between the two forces F 112A  and F 112B  results in a net force F 112N  with a magnitude of F 112A -F 112B  and a direction in the direction of the arrow A. Therefore, the net force F 112N  causes the main valve  112  to move in the direction of the arrow A. 
         [0020]    In addition, a biasing member (not shown) is also disposed between the main valve  112  (contacting the activation surface  112 A) and the end portion of the housing. The main valve biasing member is configured to provide an additional force F 112S  in the direction of the arrow A to add to the force F 112A . The force F 112S  is significantly smaller than the force F 112B , thereby the compressed air in the storage chamber can easily overcome the force F 112S  when the force F 112A  is negligible. In addition, the main valve biasing member biases the main valve  112  into contact with the cylinder to prevent rattling of the main valve  112  when there is no pressure applied to the pneumatic nailer  100 , e.g., during shipping of the nailer. 
         [0021]    The displacement chamber  128  is a space defined between the piston head  111  and the main valve  112 . In  FIG. 1 , the displacement  128  has a negligible volume, i.e., the piston head  111  is positioned in close or actual contact with the main valve  112 . The return chamber is a space defined below the piston head  111 , i.e., between the piston head and the bumper  138 . The bumper  138  is located at a distal end of the cylinder  108  and is configured to cushion and stop the high velocity moving piston head  111 , described in greater detail below. 
         [0022]    The sleeve  114  is moveably disposed outside of the cylinder  108  and is configured to form a sleeve space  124  between the sleeve  114  and the cylinder  108 . The sleeve  114  includes sealing members  154 ,  156 , and  158  to seal the sleeve chamber  118  from the sleeve space  124  as well as from the vent ports  132 . The sleeve is biased in the direction of the arrow B by the biasing member  116 . The sleeve  114  is configured to move from a first position to a second position. 
         [0023]    In the first position, referred to as a deactuated position, the sleeve  114  is at a distal end of the housing  102 . The deactuated position of the sleeve  114  is depicted in  FIG. 1 . In the deactuated position, the sleeve chamber  118  is in fluid communication with the storage chamber  122 . The pressure of the sleeve chamber  118  acts on an activation surface  114 A of the sleeve  114 , thereby generating a force F 114A  which equals to the area of the activation surface  114  multiplied by the pressure in the sleeve chamber  118 . The force F 114A  is larger than a biasing force F 114S  that is generated by the biasing member  116 . Thus, a net force F 114N  is generated that causes movement of the sleeve in the direction of the arrow A to the deactuated position. In the deactuated position, the sleeve space  124  is in fluid communication with the return chamber  126  via the bidirectional ports  134 . 
         [0024]    The second position, referred to as an actuated position, is defined by the sleeve  114  after it is moved in the direction of the arrow B. In the actuated position, the sleeve chamber  118  is no longer in fluid communication with the storage chamber  122 . Instead, the sleeve chamber  118  is in fluid communication with atmosphere. The biasing force F 114S  is larger than the Force F 114A , which is negligible in the actuated position. Therefore, the sleeve  114  moves from its deactuated position to its actuated position in the direction of the arrow B. In the actuated position, the sleeve space  124  is in fluid communication with the displacement chamber  128  via check valves  130 , as discussed below in more detail. 
         [0025]    In operation, the main valve biasing member (not shown) biases the main valve  112  against the cylinder  108 . An operator couples the pneumatic nailer  100  to a high pressure source, e.g., a compressor, by connecting the compressed air coupling member  103  to the coupling member (not shown) of the high pressure fluid source FS. So coupled, compressed air advances into the storage chamber  122 . With the trigger  104  being in the deactuated position, the trigger valve  106  is positioned to place the main valve chamber  120  in fluid communication with the storage chamber  122 . The pressure in the main valve chamber  120  generates the force F 112A  on the activation surface  112 A of the main valve  112 . Also, the pressure in the storage chamber  122  generates the force F 112B  on the activation surface  112 A of the main valve  112 . The force F 112A  and the force F 112S , i.e., the force generated by the main valve biasing member (not shown), counteract the force F 112B  to generate the net force F 112N  which causes the main valve  112  to forcefully remain against the cylinder  108 . 
         [0026]    Also, with the trigger being in the deactuated position, the trigger valve  106  is positioned to place the sleeve chamber  118  in fluid communication with the storage chamber  122 . The pressure in the sleeve chamber  118  generates the force F 114A  on the activation surface  114 A of the sleeve  114 . The force F 114A  counteracts the force F 114S  to generate the net force F 114N  which causes the sleeve  114  to assume the position shown in  FIG. 1 . 
         [0027]    The operator then presses on the trigger  104  to move it to the actuated position.  FIG. 2  depicts the pneumatic nailer  100  in a transitional state immediately after the trigger  104  has been placed in the actuated position. With the trigger  104  being in the actuated position, the trigger valve  106  is positioned to place the main valve chamber  120  in fluid communication with atmosphere. The force F 112A  on the activation surface  112 A of the main valve  112  is thereby negligible. The pressure in the storage chamber  122  continues to generate the force F 112B  on the activation surface  112 B of the main valve  112 . The force F 112S  counteracts the force F 112B  to generate the net force F 112N  which causes the main valve  112  to move in the direction of the arrow B, thereby unsealing from the cylinder  108 , as depicted in  FIG. 2 . 
         [0028]    Once the main valve  112  no longer seals the cylinder  108  from the storage chamber  122 , high pressure fluid from the storage chamber  122  is advanced into the displacement chamber  128 . In turn, the piston  110  moves in the direction of the arrow A. 
         [0029]    With the trigger being in the actuated position, the trigger valve  106  is positioned to place the sleeve chamber  118  also in fluid communication with atmosphere. Thereafter, the force F 114A  on the activation surface  114 A of the sleeve  114  is negligible. The essentially unimpeded force F 114S  causes the sleeve  114  to move in the direction of the arrow B to its actuated position, as shown in  FIG. 2 . 
         [0030]    In the actuated position of the sleeve  114 , the bidirectional ports  134  are in fluid communication with atmosphere via the vent ports  132 . It should be appreciated that while two vent ports  132  and two bidirectional ports  134  are depicted in the figures of the present disclosure, additional bidirectional ports and vent ports can be provided to improve fluid communication. 
         [0031]    With the bidirectional ports  134  being in fluid communication with atmosphere via the vent ports  132 , the fluid present in the return chamber  126  is exhausted to atmosphere, as the piston  110  moves in the direction of the arrow A. The fluid transfer between the return chamber  126  and atmosphere is indicated by dotted arrows showing the direction of flow of the fluid. Since the return chamber  126  is in fluid communication with atmosphere, the piston  110  moves in an essentially unimpeded manner thereby improving the operational efficiency of the pneumatic nailer  100 . 
         [0032]    Also depicted in  FIG. 2 , is the impact of the nail by the drive member  113  of the piston  110 . The piston  110  moves at a high rate of speed in the direction of the arrow A. Upon impacting the nail, the nail is driven out of the pneumatic nailer at a high rate of speed. While not shown, it should be appreciated that the pneumatic nailer  100  is equipped with standard safety features available on pneumatic nailers of the prior art. For example, the nail is located inside an ejector that includes a moveambletip. The trigger is locked in the deactuated position, until the tip of the ejector has been urged against a workpiece so as to be in a depressed state. 
         [0033]    With the trigger in the actuated position, the piston  110  continues to move in the direction of the arrow A from its position shown in  FIG. 2  until the piston  110  comes in contact with the bumper  138 .  FIG. 3  depicts the pneumatic nailer  100  in a steady-state after the trigger  104  has been placed in the actuated position. In  FIG. 3 , the piston  110  is in contact with the bumper  138 . The bumper  138  is resilient and thus provides a shock absorber function for the piston  110 . In addition, the bumper  138  prevents a metal-to-metal contact between the piston head  111  and the distal end of the cylinder  108 . The high pressure fluid in the displacement chamber  128  advantageously minimizes bouncing of the piston  110  off of the bumper  138 . Also depicted in  FIG. 3  is the complete ejection of the nail out of the pneumatic nailer  100 . The pneumatic nailer remains in the steady-state that is depicted in  FIG. 3 , until the operator of the pneumatic nailer releases the trigger  104 , so that the trigger moves from the actuated position to the deactuated position. 
         [0034]    Also depicted in  FIG. 3 , is a one-directional fluid flow between the displacement chamber  128  and the sleeve space  124 , via the fluid passages  129  defined in a wall of the cylinder  108  and the check valves  130 , according to the direction of the dashed arrows. Such fluid flow causes the sleeve space to be charged so as to assume a high pressure condition. This fluid transfer occurs only after a sealing member  160  of the piston head  111  has cleared the check valves  130  in its path of travel. 
         [0035]      FIG. 4  depicts the pneumatic nailer  100  in an initial transitional state immediately after the trigger  104  has been placed in the deactuated position after having been in the actuated position. With the trigger  104  being in the deactuated position, the trigger valve  106  is positioned to place the main valve chamber  120  in fluid communication with the storage chamber  122 . The force F 112A  on the activation surface  112 A added to the force F 112S  from the main valve biasing member counteract the force F 112B  applied to the activation surface  112 B by the pressure in the storage chamber  122 , to generate the net force F 112N  which causes the main valve  112  to move in the direction of the arrow A, thereby sealing the cylinder  108  from the storage chamber  122 , as depicted in  FIG. 4 . 
         [0036]    Once the main valve  112  seals the cylinder  108  from the storage chamber  122 , the displacement chamber  128  is placed in fluid communication with atmosphere via the fluid passage  136  located centrally in the main valve  112 . In other words, with the main valve  112  placed in the position depicted in  FIG. 4 , i.e., against the cylinder  108 , the fluid passage  136  opens to atmosphere. 
         [0037]    With the trigger placed in the deactuated position, the trigger valve  106  is positioned to place the sleeve chamber  118  also in fluid communication with the storage chamber  122 . Therefore, the force F 114A  on the activation surface  114 A of the sleeve  114  overcomes the force F 114S  and causes the sleeve to move in the direction of the arrow A, to its position depicted in  FIG. 4 . 
         [0038]    In the deactuated position of the sleeve  114 , the bidirectional ports  134  are in fluid communication with the sleeve space  124 . Therefore, the return chamber  126 , depicted as collapsed in  FIG. 4 , is placed in fluid communication with the sleeve space  124  via the bidirectional ports  134 . The sealing member  158  prevents fluid communication of the sleeve space  124  or the return chamber  126  with atmosphere via the vent ports  132 . 
         [0039]    With the return chamber  126  being in fluid communication with the sleeve space  124 , and with the displacement chamber  128  being in fluid communication with atmosphere via the fluid passage  136 , the high pressure fluid present in the sleeve space  124  causes the piston to move in the direction of the arrow B. 
         [0040]      FIG. 5  depicts the pneumatic nailer  100  in another transitional state at a short time after the trigger has been placed in the deactuated position after having been in the actuated position. Depicted in  FIG. 5  are two sets of arrows indicating flow of fluid. The first set of arrows, dashed arrows, indicate fluid transfer from the sleeve space  124  into the return chamber  126 . The fluid in the sleeve space  124  has a high pressure, since high pressure fluid was introduced into the sleeve space  124  from the displacement chamber  128  through the fluid passages  129  and the check valves  130  during the latter part of the piston movement that was depicted in  FIG. 3 . The high pressure fluid introduced into the return chamber  126  acts on the lower side of the piston head  111  and thereby causes the piston  110  to move in the direction of the arrow B. The second set of arrows, the dotted arrows, indicate fluid flow from the displacement chamber  128  to atmosphere via the fluid passage  136  of the main valve  112 . 
         [0041]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.