Patent Publication Number: US-8978950-B2

Title: Fuel container holding structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fuel container holding structure which can protect a fuel container against impacts. 
     2. Related Art 
     Generally, in a gas combustion type driving tool, a fuel container with liquefied fuel gas filled therein is mounted into a tool, the fuel gas supplied from the fuel container is charged into a sealed combustion chamber, the fuel gas and air are mixed within the combustion chamber to produce a mixture gas, and a fastening member is driven by a combustion pressure produced by a combustion of the mixture gas. 
     The fuel container is detachably stored in a fuel container storing portion in a housing of a main body of the tool. When the fuel in the fuel container runs out, the fuel container is replaced. 
     A conventional gas combustion type driving tool has a problem that impacts produced in its driving time are transmitted to the fuel container and the fuel container may be broken. For example, in the case that the fuel container is a gas can including an aluminum-made inner bag filled with fuel gas, there is a problem that the inner bag can be creased by the impacts occurring in the tool driving time, thereby producing cracks and holes in the inner bag of the gas can (a pinhole phenomenon). When such holes are formed in the inner bag of the gas can, the fuel gas within the inner bag and compressed gas (nitrogen or the like) outside the inner bag are mixed together, thereby causing a poor injection of the fuel gas. In the case that the fuel gas cannot be ignited due the poor injection thereof, even when the fuel remains in the fuel container, the fuel container is unusable. 
     To avoid such problem, a structure to buffer the impacts transmitted to the fuel container is considered. For example, DE102006000233A1 discloses a structure in which an elastic force is applied through a spring to a connecting element for connecting the fuel container. In this structure, the impacts to be transmitted to the fuel container can be absorbed by the spring. 
     However, in the structure of the DE102006000233A1, there is a problem that, since the connecting element is held by the spring, a space for disposing the spring is necessary. 
     SUMMARY OF THE INVENTION 
     Embodiments of the invention relate to a fuel container holding structure which can buffer impacts to be transmitted to the fuel container, and can eliminate a space for disposing a spring for holding a connecting element, thereby being able to realize a spacing saving thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external view of a gas combustion type driving tool. 
         FIG. 2  is a section view of a fuel container storing portion, showing a state where a fuel container is being mounted therein. 
         FIG. 3  is a partially enlarged section view of the fuel container storing portion, showing a state where a fuel container is being mounted therein. 
         FIG. 4  is a section view of the fuel container storing portion, showing a state after the fuel container is mounted. 
         FIG. 5  is a partially enlarged section view of the fuel container storing portion, showing a state after the fuel container is mounted. 
         FIGS. 6A and 6B  are explanatory views to show how the fuel container moves within the fuel container storing portion. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Description will be given below of an exemplary embodiment of a fuel container holding structure with reference to the accompanying drawings, while taking a gas combustion type driving tool  10  as an example. 
     In the gas combustion type driving tool  10  of the exemplary embodiment, as shown in  FIG. 1 , a grip housing  12  is provided backwardly of a body housing  11  continuously therewith. On a lower portion of the body housing  11 , there is mounted a nose portion  13  for driving and guiding a nail into a driven work-piece. A magazine  14  with a large number of nails accommodated therein is provided laterally of the nose portion  13  continuously therewith. The nails within the magazine  14  are supplied sequentially to the nose portion  13 , and the nails supplied to the nose portion  13  are struck by a striking mechanism (not shown) within the body housing  11  and are driven out from the injection port of a leading end of the nose portion  13  into the driven work-piece. 
     In the striking mechanism, fuel gas and air are mixed together in a combustion chamber formed within the body housing  11  to generate a mixture gas, the pressure of a combustion gas produced by a combustion of the mixture gas is applied to a striking piston, and the nails are struck by the striking piston. 
     The supply of the fuel gas into the combustion chamber is carried out through a supply port facing an inside of the combustion chamber. A gas supply pipe is connected to the supply port, whereby the fuel gas injected from an electromagnetic valve device is guided to the combustion chamber. The electromagnetic valve device is connected to a fuel container  40  with liquefied fuel gas filled therein. The electromagnetic valve device measures the fuel to be supplied from the fuel container  40  and injects a given amount of fuel gas into the combustion chamber. 
     The fuel container  40  of the exemplary embodiment is a tubular (cylindrical) gas can. As shown in  FIGS. 3 and 4 , the fuel container  40  includes a fuel filling portion  46  for filling the fuel gas therein, a cap member  41  fitted and fixed to the front end of the fuel filling portion  46 , a slide member  42  slidable out of and into the cap member  41  along its inside, and a nozzle  44  movable out of and into a nozzle hole  42  formed in the center of the slide member  42 . The slide member  42  is energized in its projecting direction by a coil spring  43 . 
     The fuel filling portion  46  has a dual structure constituted of an outer can and an inner bag disposed within the outer can. Liquefied fuel gas is filled within the inner bag. In a space between the outer can and inner bag, there is filled compressed gas having a higher pressure than a pressure of the fuel gas. The compressed gas presses a surface of the inner bag to compress it, whereby the fuel gas is injected from the nozzle  44 . 
     A role of a valve for adjusting the injection of the fuel gas is played by the slide member  42 . The nozzle  44  is used to inject the fuel gas and is energized in the projecting direction by a nozzle energizing member  45 . 
     According to the exemplary embodiment, the fuel container  40 , as shown in  FIG. 1 , is stored in a fuel container storing portion  20  formed substantially parallel to a nail drive-out direction. The fuel container storing portion  20  includes a lid  21  mounted such that it can be opened and closed through a hinge. By rotating the lid  21 , the fuel container storing portion  20  can be opened and closed. When the lid  21  is opened, as shown in  FIG. 1 , an upper surface of the fuel container storing portion  20  is opened, whereby the fuel container  40  stored in the fuel container storing portion  20  can be taken out or the fuel container  40  can be inserted into the fuel container storing portion  20 . 
     The fuel container  40  is inserted and stored into the fuel container storing portion  20  from a front end portion  40   a  with the nozzle  44  formed therein. The fuel container storing portion  20 , as shown in  FIG. 2 , includes a front end holding portion  22  for holding the front end portion  40   a  of the fuel container  40  and a rear end holding portion  28  for holding the rear end portion  40   b  of the fuel container  40 . The hold portions  22  and  28  hold therebetween the fuel container  40  from both sides. 
     The front end holding portion  22 , as shown in  FIG. 2 , includes a connecting unit  23 . The connecting unit  23  is used to connect the nozzle  44  of the fuel container  40  and is removably fixed to the grip housing  12 . 
     Specifically, the connecting unit  23  includes a connecting unit main body  23 A which is immovable relative to the main body of the driving tool  10 . The connecting unit main body  23 A includes an internal space  23 B (see  FIG. 5 ). The connecting unit  23  includes a valve  25  for opening and closing a fuel supply passage extending from the fuel container  40  to the electromagnetic valve device. The valve  25  includes a valve body  26  to be pressed in the opening direction when the nozzle  44  of the fuel container  40  is connected, and a valve body energizing member  27  made of a compression spring for energizing the valve body  26  in the closing direction. The valve body  26  and valve body energizing member  27  are stored within the internal space  23 B. 
     As shown in  FIG. 5 , when the fuel container  40  is mounted in the fuel container storing portion  20 , the nozzle  44  of the fuel container  40  is inserted from the upper opening of the internal space  23 B of the connecting unit  23  into the internal space  23 B. Also, a seal  23 B made of an O ring is provided on the inner periphery of the upper opening of the internal space  23 B of the connecting unit  23 . When the fuel container  40  is mounted in the fuel container storing portion  20  and the nozzle  44  of the fuel container  40  is inserted in the internal space  23 B, this seal is contacted with the outer periphery of the nozzle  44  to seal between the inside and outside of the internal space  23 B. The internal space  23 B is connected to the electromagnetic valve device. When the fuel container  40  is connected to the connecting unit  23 , the fuel within the fuel container  40  is supplied to the electromagnetic valve device through the internal space  23 B. 
     As shown in  FIG. 3 , before the fuel container  40  is mounted, the valve body  26  is energized by the valve body energizing member  27  in the closing direction (a direction where the nozzle  44  is connected; namely, in the upper direction in  FIG. 3 ) and thus the valve  25  closes the fuel supply passage, thereby preventing the fuel from being supplied from the fuel container  40  to the electromagnetic valve device. After the fuel container  40  is mounted, as shown in  FIG. 5 , the nozzle  44  pushes the valve body  26  inwardly against the energizing force of the valve body energizing member  27  to open the valve  25 , whereby the fuel is supplied from the fuel container  40  to the electromagnetic valve device. 
     Here, to supply the fuel from the fuel container  40  to the electromagnetic valve device, in addition to the opening of the valve  25  of the connecting unit, it is necessary to inject the fuel from the nozzle  44  of the fuel container  40 . Before the fuel container  40  is connected to the connecting unit  23 , as shown in  FIG. 3 , an injection port  44   a  formed in the leading end of the nozzle  44  is buried in the slide member  42  and is thereby closed to prevent the gas from leaking to the outside. Therefore, to supply the fuel from the fuel container  40  to the electromagnetic valve device, it is necessary to expose the injection port  44   a  and inject the fuel from the nozzle  44 . 
     According to the exemplary embodiment, by connecting the fuel container  40  to the connecting unit  23 , the fuel is injected from the nozzle  44  of the fuel container  40 . That is, when the fuel container  40  is connected to the connecting unit  23 , the projecting end portion  23   a  of the connecting unit  23  is fitted into a peripheral groove portion  42   b  formed in the periphery of the nozzle hole  42   a  of the slide member  42 , thereby pressing the slide member  42  inwardly. Accordingly, the slide member  42  is moved inwardly against the energizing force of a coil spring  43  and, as shown in  FIG. 5 , the leading end of the nozzle  44  is projected to the outside of the slide member  42  to expose the injection port  44   a . This enables the fuel to be injected from the fuel container  40 . Thus, by applying a load to the front end portion  40   a  (slide member  42 ) of the fuel container  40 , the fuel can be injected from the nozzle  44  of the fuel container  40 . 
     According to the exemplary embodiment, the valve body  26  for elastically receiving the nozzle  44  of the fuel container  40  serves as a buffer member and supports the front end portion  40   a  of the fuel container  40 . The valve  25  including the valve body  26  and valve body energizing member  27  functions as a buffer mechanism interposed between the connecting unit  23  and fuel container  40 . In other words, the bottom dead center of the fuel container  40  is determined by the nozzle  44  elastically supported by the buffer mechanism. 
     Also, the slide member  42  for elastically receiving the projecting end portion  23   a  of the connecting unit  23  also functions as a buffer mechanism interposed between the connecting unit  23  and fuel container  40 . 
     Therefore, as shown in  FIG. 5 , any buffer mechanism always intervenes between the fuel filling portion  46  of the fuel container  40  and connecting unit  23 , while other portion than the buffer mechanism is prevented from touching the front end portion  40   a  of the fuel container  40 . Accordingly, even when impacts are applied to the front end holding portion  22  of the fuel container storing portion  20 , such impacts are not applied directly to the fuel filling portion  46 . This can prevent the fuel filling portion  46  against damage (a pinhole phenomenon in which the inner bag is creased to cause cracks or holes therein). 
     The rear end holding portion  28 , as shown in  FIG. 2 , includes a rear end buffer member  29  made of a compression spring for buffering impacts applied to the rear end portion  40   b  of the fuel container  40 . The rear end buffer member  29  is provided on the back surface of the lid  21 . When the lid  21  with the fuel container  40  stored is closed, the rear end buffer member  29  presses the fuel container  40  in the direction of the connecting unit  23 , whereby the fuel container  40  is fixed within the fuel container storing portion  20 ; and, when the impacts are applied, the rear end buffer member  29  is elastically deformed to buffer impacts applied to the fuel container  40 . 
       FIGS. 6A and 6B  are explanatory views to show how the fuel container  40  moves within the fuel container storing portion  20 . As shown in  FIGS. 6A and 6B , in the case that impacts are applied to the fuel container  40  when nails are driven by the gas combustion type driving tool  10 , the valve body energizing member  27 , rear end buffer member  29  and coil spring  43  are respectively expanded and contracted to move the fuel container  40  in the longitudinal direction, thereby buffering the impacts to be applied to the fuel container  40 . 
     The energizing load of the rear end buffer member  29  is set larger than that of the valve body energizing member  27 . This aims to avoid a problem that the rear end buffer member  29  absorbs the energizing load of the valve body energizing member  27  to thereby prevent the valve body  26  from opening. 
     A load obtained by subtracting the energizing load of the valve body energizing member  27  from that of the rear end buffer member  29  is larger than the energizing load of the coil spring  43 . This aims to avoid a problem that the load obtained by subtracting the energizing load of the valve body energizing member  27  from that of the rear end buffer member  29  is too small to push the slide member  42  inwardly against the energizing force of the coil spring  43 , is thereby failing to inject the fuel from the fuel container  40 . 
     Here, the buffer mechanism is not limited to the above structure. For example, such a clearance may be formed as to prevent direct contact between the connecting unit  23  and fuel container  40 , and a buffer member such as a spring or rubber may be disposed in this clearance. In this case, the buffer member may be provided in the connecting unit  23 , or may be provided inside the grip housing  12  (inside the fuel container storing portion  20 ). 
     In the above embodiment, the fuel container  40  is stored in the fuel container storing portion  20  substantially parallel to the nail drive-out direction. However, this is not limitative. For example, a fuel container storing portion for containing a fuel container may be formed substantially perpendicularly to the drive-out direction of the grip or magazine, and a buffer mechanism may be provided in this fuel container storing portion. 
     In the above embodiment, a compression spring is used as the rear end buffer member  29 . However, this is not limitative. For example, the rear end buffer member  29  may also be made of high polymer material such as soft plastic. When the rear end buffer member  29  is made of high polymer material, when compared with a spring, the impact can be absorbed quickly without damaging the fuel container  40 . 
     As described above, in accordance with the exemplary embodiment and its modification, the fuel container holding structure for detachably holding the fuel container  40  including the nozzle  44  in its front end portion may include a front end holding portion  22  for holding the front end portion of the fuel container  40  and a rear end holding portion  28  for holding the rear end portion thereof. The front end holding portion  22  may include a connecting portion  23  with the nozzle  44  connectable thereto, and buffer mechanism  25 ,  42  to be disposed between the connecting portion  23  and fuel container  40 . The fuel container  40  may be supported by the butter mechanism  25 ,  42 . 
     According to this structure, the buffer mechanism is interposed between the connecting unit  23  and fuel container  40  and the fuel container  40  itself is received by the buffer mechanism, thereby being able to realize space saving. 
     The buffer mechanism  25  may include a buffer member  26  for receiving the nozzle  44  elastically. 
     According to this structure, since the buffer mechanism can be provided within the connecting unit  23 , space saving can be realized and standardized design or model development can be facilitated. Also, since the connecting unit  23  is removable, maintenance such as cleaning can also be facilitated. 
     Within the connecting portion  23 , there may be provided a valve  25  for opening and closing the fuel supply passage. The valve  25  may include a valve body  26  to be pressed in the opening direction when the nozzle  44  is connected, and a valve body energizing member  27  for energizing the valve body  26  in the closing direction. The buffer mechanism may receive the nozzle  44  elastically due to the energizing force of the valve body energizing member  27 . 
     According to this structure, since the buffer mechanism can be provided within the connecting unit  23 , space saving can be realized and standardized design or model development can be facilitated. Also, when the connecting unit  23  is removable, maintenance such as cleaning can also be facilitated. And, since the valve  25  functions also as the buffer mechanism, this structure can be manufactured without increasing the number of conventional parts. 
     The connecting portion  23  may include a connecting unit main body  23 A immovable relative to the main body of the driving tool  10 , while an internal space  23 B may also be formed within the connecting unit main body  23 A. The valve body  26  and valve body energizing member  27  may be stored in the internal space  23 B. This space  23 B may be structured such that, while the fuel container  40  is mounted in the fuel container storing portion  20  of the driving tool  10 , the nozzle  44  of the fuel container  40  is moved into this space  23 B. This space  23 B may be connected to the combustion chamber side of the driving tool  10 . 
     The rear end holding portion  28  may include a rear end buffer member  29  for buffering impacts applied to the rear end portion of the fuel container  40 . 
     According to this structure, the front end portion  40   a  of the fuel container  40  is held by the buffer mechanism and the rear end portion  40   b  thereof is held by the rear end buffer member  29 . Thus, impacts can be absorbed the moment they are applied to the tool and also when the fuel container  40  is moved due to its reaction, thereby being able to further buffer impacts applied to the fuel container  40 . 
     The energizing load of the rear end buffer member  28  may be larger than that of the valve body energizing member  27 . This structure can avoid the problem that the rear end buffer member absorbs the load to prevent the valve body from opening. 
     A load obtained by subtracting the energizing load of the valve body energizing member  27  from that of the rear end buffer member  28  may be larger than a load which must be applied to the front end portion of the fuel container  40  in order to inject the fuel from the nozzle  40 . 
     This structure can avoid the problem that the load obtained by subtracting the energizing load of the valve body energizing member from that of the rear end buffer member is too small to open the valve of the fuel container, thereby failing to inject fuel gas. 
     The buffer mechanism may include a slide member  42  which is connected to the fuel container  40 , is energized toward the connecting portion  23  by the spring  43 , and, while the fuel container  40  is mounted in the fuel container storing portion  20  of the driving tool  10 , can be elastically contacted with the projecting end portion  23   a  of the connecting portion  23 . 
     The rear end holding portion  28  may include a rear end buffer member  29  made of high polymer material for buffering impacts applied to the rear end portion of the fuel container  40 . 
     According to this structure, the front end portion of the fuel container is held by the buffer mechanism and the rear end portion thereof is held by the rear end buffer member. Thus, impacts can be absorbed the moment they are applied to the tool and also when the fuel container is moved due to its reaction. This can further buffer impacts applied to the fuel container. Also, since the is rear end buffer member made of high polymer material, when compared with a spring, the impacts can be absorbed quickly without damaging the fuel container. 
     DESCRIPTION OF REFERENCE NUMERALS AND SIGNS 
     
         
           10 : Gas combustion type driving tool 
           11 : Body housing 
           12 : Grip housing 
           13 : Nose portion 
           14 : Magazine 
           20 : Fuel container storing portion 
           21 : Lid 
           22 : Front end holding portion 
           23 : Connecting unit (connecting portion) 
           23   a : Projecting end portion 
           25 : Valve 
           26 : Valve body (buffer member) 
           27 : Valve body energizing member 
           28 : Rear end holding portion 
           29 : Rear end buffer member 
           40 : Fuel container 
           40   a : Front end portion 
           40   b : Rear end portion 
           41 : Cap member  42 : Slide member 
           42   a : Nozzle hole 
           42   b : Peripheral groove portion 
           43 : Coil spring 
           44 : Nozzle 
           44   a : Injection port 
           45 : Nozzle energizing member 
           46 : Fuel filling portion