Patent Publication Number: US-6220496-B1

Title: Nailing machine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a nailing machine for driving in fasteners such as nails. 
     2. Description of the Related Art 
     FIGS. 14 and 15 show a conventional nailing machine. FIG. 14 shows an initial state of the nailing machine and FIG. 15 shows the nailing machine in operation. 
     As shown in FIG. 14, a machine body  1  includes an accumulator chamber  2  for accumulating compressed air, a cylinder  4 , a piston  8  vertically movably supported in the cylinder  4 , a drive bit  7  integrally formed with the piston  8 , the lower end of which is used to drive in nails  6  positioned in an ejection portion  12 , a return air chamber  3  that is provided on the lower outer periphery of the cylinder  4  and communicates with the interior of the cylinder  4  via an air passage  11  having a check valve, a main valve  5  vertically movably provided above the cylinder  4 , a trigger valve  14  for providing and withholding the communication between a main valve upper chamber  15  and the accumulator chamber  2  via an air passage  9  and the like. Further, the accumulator chamber  2  is formed at the rear end of the body  1  and there is provided a handle portion  13  having an air intake  16  to which an air hose  50  connected to an air compressor (not shown) is connected. A trigger  17  for controlling a trigger valve  14  is also provided near the handle portion  13 . 
     The air hose  50  connected to the air compressor is connected to the air intake  16  at the rear end of the handle portion  13 , so that the compressed air is accumulated in the accumulator chamber  2 . 
     FIG. 14 shows the nailing machine in the initial state in which compressed air is accumulated in the accumulator chamber  2  before the nailing operation is performed, the trigger valve  14  making the accumulator chamber  2  communicate with the main valve upper chamber  15  via the air passage  9 . 
     While the main valve  5  stays in the lower position as shown in the drawing, the communication between the inside of the cylinder  4  and the accumulator chamber  2  is shut off and an exhaust vent  10  in the upper position of the cylinder  4  is opened. Thus, the upper portion of the piston  8  in the cylinder  4  communicates with the atmosphere and the piston  8  as well as the drive bit  7  in the cylinder  4  is in the elevated position. 
     When the trigger valve  14  is operated after the trigger  17  is actuated as shown in FIG. 15, the communication between the main valve upper chamber  15  and the accumulator chamber  2  is shut off. Then the compressed air in the accumulator chamber  2  causes the main valve  5  to ascend, which makes the inside of the cylinder  4  communicate with the accumulator chamber  2  and shuts the exhaust vent  10 . The compressed air that has flowed into the upper portion of the piston  8  in the cylinder  4  causes the piston  8  and the drive bit  7  to descend rapidly within the cylinder  4 , whereby the nail  6  positioned in the ejection portion  12  is hit before being driven into a workpiece  19 . 
     At this time, the compressed air flows into the return air chamber  3  via the air passage  11  provided in the cylinder  4 . 
     When the operation of the trigger  17  is released so as to make the main valve upper chamber  15  and the accumulator chamber  2  communicate with each other after the trigger valve  14  is returned to the initial state, the main valve  5  descends and the compressed air above the piston  8  in the cylinder  4  is discharged from the exhaust vent  10  into the atmosphere. The piston  8  and the drive bit  7  are caused to ascend by the compressed air in the return air chamber  3 , and the nailing machine returns to the initial state shown in FIG.  14 . 
     The conventional nailing machine operates as mentioned above and since the compressed air in the accumulator chamber  2  flows into the cylinder  4  and the return air chamber  3  during the nailing operation and since the compressed air that has flowed therein is discharged into the atmosphere, the pressure in the accumulator chamber  2  is reduced as the nailing operation continues. However, as the accumulator chamber  2  is communicating with the air compressor via the air intake  16  and the air hose  50  provided at the rear end of the handle portion  13 , the compressed air is supplied from the air compressor when the pressure in the accumulator chamber  2  is reduced. Consequently, the accumulator chamber  2  always holds the air pressure needed to perform the nailing operation and this makes it possible for the nailing machine to perform the nailing operation. 
     The nailing operation is made possible by the compressed air supplied from the air compressor as long as the aforementioned conventional nailing machine is concerned; in other words, the nailing operation cannot be performed unless the nailing machine is connected to the air compressor. Consequently, the air hose  50  is indispensable to connecting the air compressor to the nailing machine, which results in poor workability because the nailing machine is limited by the length of the air hose  50 , the installation place of the air compressor and so forth. 
     When the nailing work is done in a small place, for example, the disadvantage is that the air hose  50  becomes obstructive. 
     One of the ways of obviating the above disadvantage is as disclosed in Japanese Utility Model Publication 13499/1973 to provide a nailing machine using liquified gas within a detachable liquified gas storage tank in its body as a power source. Although restrictions depending on the length of the air hose and the installation place of the air compressor and so forth are not imposed, many storage tanks will have to be prepared beforehand if the amount of work is large because it is difficult to refill the used storage tank with the liquified gas. 
     Another way of solving the above problem is to provide a nailing machine using a secondary battery as a power source but its power output is smaller than what is available from the compressed air as a power source, moreover, it takes much time to charge the secondary battery. 
     SUMMARY OF THE INVENTION 
     An object of the present invention intended to obviate the aforementioned shortcomings is to provide a nailing machine which is usable while an air compressor is not connected thereto, offers excellent workability and can easily be filled up with compressed air. 
     The object above is accomplished by providing a nailing machine with a second accumulator chamber capable of accumulating compressed air having a pressure higher than air pressure usable by the machine body, an air intake connectable to an air compressor via an air hose, a valve for control of the communication between the second accumulator chamber and the air intake, and a pressure reducing valve for reducing the compressed air pressure in the second accumulator chamber and supplying the pressure-reduced compressed air into the first accumulator chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional side view of a nailing machine embodying the present invention; 
     FIG. 2 is an enlarged view of the principal part of FIG.  1 ; 
     FIG. 3 is an enlarged view of the principal part of FIG. 1; 
     FIG. 4 is an enlarged view of the principal part, showing the operating condition of the pressure reducing valve shown in FIG. 3; 
     FIG. 5 is an enlarged view of the principal part of FIG. 1; 
     FIG. 6 is a sectional side view of another nailing machine embodying the present invention; 
     FIG. 7 is a sectional side view of still another nailing machine embodying the present invention; 
     FIG. 8 is a sectional side view of still another nailing machine embodying the present invention; 
     FIG. 9 is an enlarged sectional view of the principal part of still another nailing machine embodying the present invention; 
     FIG. 10 is an enlarged sectional view of the principal part of still another nailing machine embodying the present invention; 
     FIG. 11 is an enlarged sectional view of the principal part of still another nailing machine embodying the present invention; 
     FIG. 12 is an enlarged sectional view of the principal part of still another nailing machine embodying the present invention; 
     FIG. 13 is an enlarged sectional view of the principal part of still another nailing machine embodying the present invention; 
     FIG. 14 is a sectional side view of an example of a conventional nailing machine; and 
     FIG. 15 is an enlarged side view of the principal part, showing the nailing condition of the nailing machine shown in FIG.  14 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A nailing machine embodying the present invention will now be described with reference to FIGS. 1-5. As the nailing machine according to this embodiment of the invention performs a nailing operation similar to what is performed by the conventional nailing machine, like elements are given like reference characters and the description thereof will be omitted. Moreover, an accumulator chamber  2  provided in a handle portion  13  as in the conventional nailing machine is hereinafter called a first accumulator chamber  2 . 
     As shown in the drawings, a second accumulator chamber  20  communicating with the first accumulator chamber  2 , and an air intake  16  connectable to an air compressor via an air hose  50  are provided at the rear end of the handle portion  13  of a machine body  1 . A pressure reducing valve  21  is provided between the first and second accumulator chambers  2  and  20 , and a check valve  22  is provided between the second accumulator chamber  20  and the air intake  16 . 
     The first accumulator chamber  2  used to accumulate compressed air to be consumed when nails are driven in has a pressure resistance strength equal to that of conventional nailing machines in general, the pressure resistance strength being sufficient to accumulate compressed air having a set pressure of about 8 Kgf/cm 2  according to this embodiment of the invention. On the other hand, the second accumulator chamber  20  used to accumulate the high-pressure compressed air supplied from the air compressor has not only a pressure resistance strength greater than that of the first accumulator chamber  2  but a volume capacity of one liter, the pressure resistance strength being sufficient to accumulate compressed air having a pressure of about 30 Kgf/cm 2  according to this embodiment of the invention. The two accumulator chambers  2  and  20  are coupled via a pressure reducing valve  21 , so that the compressed air in the second accumulator chamber  20  is reduced in pressure and then introduced into the first accumulator chamber  2 . 
     The check valve  22  provided between the second accumulator chamber  20  and the air intake  16  is essentially formed of an urethane ball  27  as a valve element, and a spring  33  for urging the urethane ball  27  so that the check valve  22  may always stay in the closed position. In a case where the pressure on the side of the air intake  16  is higher than that on the side of the second accumulator chamber  20 , the urethane ball  27  moves toward the second accumulator chamber  20  against the urging force of the spring  33 . The check valve  22  is then opened to have the compressed air from the air compressor supplied into the second accumulator chamber  20  via the air intake  16  and the check valve  22 . In a case where the pressure on the side of the second accumulator chamber  20  is higher or substantially equal to that on the side of the air intake  16 , the check valve  22  is shut to prevent the compressed air in the second accumulator chamber  20  from flowing toward the air intake  16 . 
     A description will be given of a case when the air hose  50  connected to the air compressor is connected to the air intake  16 . 
     The aforementioned operation of the check valve  22  causes the compressed air to be supplied from the air compressor into the second accumulator chamber  20  until the pressure in the second accumulator chamber  20  becomes substantially equal to the pressure on the side of the air intake  16 . The compressed air accumulated in the second accumulator chamber  20  is supplied into the first accumulator chamber  2  via the pressure reducing valve  21  provided between the first accumulator chamber  2  and the second accumulator chamber  20 . 
     As shown in FIGS. 3 and 4, the pressure reducing valve  21  includes an urethane ball  28  for providing and withholding the communication between the first and second accumulator chambers  2  and  20 , a spring  31  for usually urging the urethane ball  28  to make the urethane ball  28  shut off the communication between the first and second accumulator chambers  2  and  20 , a regulator piston  29  for controlling the slidable urethane ball  28 , and a spring  30  for urging the regulator piston  29 . The regulator piston  29  is usually urged by the spring  30  to move toward the urethane ball  28  and to move away, that is, to the left as shown in the drawings from the urethane ball  28  by the compressed air in the first accumulator chamber  2 . 
     The regulator piston  29  in the pressure reducing valve  21  shown in FIG. 3 becomes located on the left-hand side therein against the urging force of the spring  30 , and the communication between the first and second accumulator chambers  2  and  20  is shut off. At this time, the set pressure (8 Kgf/cm 2  according to this embodiment of the invention) is maintained in the first accumulator chamber  2  and when the pressure in the first accumulator chamber  2  is maintained in the neighborhood of the set pressure, the regulator piston  29  slides away from the urethane ball  28  against the urging force of the spring  30 . 
     When the pressure in the first accumulator chamber  2  is reduced as the nailing machine performs the nailing operation, the urging force applied to the regulator piston  29  because of the compressed air in the first accumulator chamber  2  becomes weaker than the urging force of the spring  30 . The regulator piston  29  slides toward the urethane ball  28  and the end portion of the regulator piston  29  abuts against the urethane ball  28  as shown in FIG.  4 . Then the regulator piston  29  makes the urethane ball  28  move against the urging force of the spring  31 , so that the first and second accumulator chambers  2  and  20  communicate with each other. 
     When the compressed air in the second accumulator chamber  20  is supplied via the pressure reducing valve  21  into the first accumulator chamber  2  and when the pressure in the first accumulator chamber  2  rises to the set pressure, the regulator piston  29  remains in the state shown in FIG. 3, so that the communication between the first and second accumulator chambers  2  and  20  is shut off. 
     In other words, the pressure in the first accumulator chamber  2  is usually set at the set pressure through the operation of the pressure reducing valve  21  when the pressure in the second accumulator chamber  20  as the compressed air supply source of the first accumulator chamber  2  becomes higher than the set pressure in the first accumulator chamber  2 . 
     When the air hose  50  is connected to the air intake  16 , the compressed air having different predetermined pressure is accumulated in the second and first accumulator chambers  20  and  2 , respectively. When the pressure in the first accumulator chamber  2  is reduced as the nailing machine operates, the compressed air in the second accumulator chamber  20  is supplied via the pressure reducing valve  21  into the first accumulator chamber  2 . When the pressure in the second accumulator chamber  20  is reduced, the compressed air is supplied from the air compressor into the second accumulator chamber  20  via the air hose  50 , the air intake  16  and the check valve  22 , so that the different predetermined pressure is usually maintained in the first and second accumulator chambers  2  and  20 , respectively. 
     As shown in FIGS. 1 and 5, a relief valve  24  for controlling the communication between the first accumulator chamber  2  and the atmosphere is provided for the body  1 . The relief valve  24  includes an urethane ball  34  and a spring  35  for usually urging the urethane ball  34  downward in FIG. 5 so as to shut off the communication between the atmosphere and the first accumulator chamber  2 . While the pressure in the first accumulator chamber  2  is within the set pressure range, the urging force of the spring  35  causes the urethane ball  34  to shut off the communication between the atmosphere and the first accumulator chamber  2 . When the pressure in the first accumulator chamber  2  exceeds the set pressure, the urethane ball  34  rises against the urging force of the spring  35  as shown in FIG.  5  and the first accumulator chamber  2  communicates with the atmosphere. 
     The relief valve  24  prevents the pressure in the first accumulator chamber  2  from exceeding the set pressure because the pressure reducing valve  21  provided between the first and second accumulator chambers  2  and  20  malfunctions, whereby to prevent the first accumulator chamber  2 , and the cylinder  4 , the piston  8  and the like in the following stage from being damaged. 
     The conditions under which the relief valve  24  operates are determined by the urging force of the spring  35  and the pressure receiving area of the urethane ball  34 . 
     A case where the air compressor is disconnected from the nailing machine by detaching the air hose  50  from the air intake  16  will now be described. Incidentally, the pressure in the first and second accumulator chambers  2  and  20  is set at the different predetermined pressure by the compressed air supplied from the air compressor, respectively. 
     As the pressure in the second accumulator chamber  20  is higher than that in the first accumulator chamber  2 , the compressed air in the second accumulator chamber  20  is supplied via the pressure reducing valve  21  into the first accumulator chamber  2  when the pressure in the first accumulator chamber  2  is reduced during the operation of the nailing machine. 
     Given that the set pressure in the first accumulator chamber  2  is 8 Kgf/cm 2  and that the pressure in the second accumulator chamber  20  is 30 Kgf/cm 2  with a capacity of one liter, the amount of the compressed air supplied into the first accumulator chamber  2  until the pressure in the second accumulator chamber  20  is reduced to the set pressure in the first accumulator chamber  2  when the air compressor is disconnected from the nailing machine will come to the following in terms of the atmospheric pressure. 
     
       
         (30−8)×1=22 (liters) 
       
     
     Given that the amount of the compressed air consumed when the nailing machine drives in one nail is about 0.5 liter in terms of the atmospheric pressure, about 44 nails may be driven in. 
     When the pressure in the second accumulator chamber  20  is reduced to the set pressure or lower in the first accumulator chamber  2  after the nailing operation is repeated, the pressure reducing valve  21  opens to make both the accumulator chambers  2  and  20  communicate with each other. If the nailing operation is continued in this state, the pressures in both the accumulator chambers  2  and  20  are reduced simultaneously and sufficient output becomes unavailable ultimately and this makes it impossible to drive in nails. 
     In this case, the air hose  50  is connected to the air intake  16  again in order to refill the first and second accumulator chambers  2  and  20  with compressed air. 
     According to the above-described embodiment of the invention, the nailing operation is made performable without using the air hose and also usable in any given place with the effect of improving workability because the nailing operation range is not restricted by the length of the air hose  50  and a power source cord, the installation place of the air compressor and so forth. Workability is made improvable further as many nails can be driven in by the use of the small-capacity second accumulator chamber  20 . Moreover, any ordinary air compressor is usable for the supply of air compressor into the second accumulator chamber  20 , which obviates difficulties concerning the filling up of liquefied gas. As the accumulator chamber can be filled up with compressed air in a short time, it is unnecessary to prepare a plurality of liquified gas storage tanks beforehand, whereby workability becomes further improvable. 
     FIGS. 6-8 show other examples of nailing machines according to the present invention. 
     As shown in FIG. 6, the second accumulator chamber  20  is attachable to the machine body  1  of a nailing machine having the air intake  16 , the pressure reducing valve  21  and the check valve  22 . Further, an air passage  61  is provided between the pressure reducing valve  21  and the check valve  22 , and a loading-unloading device  60   a  for communicating with the air passage  61  is also provided. 
     The second accumulator chamber  20  is provided with an air intake  60   b  capable of engaging with the loading-unloading device  60   a  and by engaging the loading-unloading device  60   a  with the air intake  60   b,  the compressed air supplied from an air compressor via the air intake  16  and the check valve  22  is made to flow into the second accumulator chamber  20 . 
     The second accumulator chamber  20  is capable of accumulating compressed air whose pressure is higher than the pressure in the first accumulator chamber  2  as in the aforementioned embodiment of the invention and when the second accumulator chamber  20  is disconnected from the air compressor, the compressed air in the second accumulator chamber  20  is reduced in pressure by the pressure reducing valve  21  before being supplied into the first accumulator chamber  2 . Moreover, it is necessary to make such an arrangement that the loading-unloading device  60   a  provided for the body  1  is shut while it is not engaging with the air intake  60   b  of the second accumulator chamber  20  or when the pressure in the air passage  61  is higher than the pressure on the connection side of the air intake  60   b.    
     The second accumulator chamber  20  may be disconnected from the body  1  of the nailing machine when work is done by connecting the air compressor thereto and as the second accumulator chamber  20  can thus be disconnected therefrom voluntarily, nonconformity arising from the presence of such a relatively large second accumulator chamber  20  can be obviated during the operation with the air compressor connected thereto. 
     FIG. 7 refers to an arrangement wherein the second accumulator chamber  20  is attachable to a nailing machine having the pressure reducing valve  21  within its body  1 . The second accumulator chamber  20  is provided with a loading-unloading device  60  capable of engaging with the air intake  16 , an air intake  63  similar in shape to the air intake  16  provided for the body  1 , and the check valve  22 , so that this arrangement is also proved effective in accomplishing the same operation/working effect as what has been described with reference to FIG.  6 . 
     FIG. 8 refers to an example of making the second accumulator chamber  20  attachable to the prior art nailing machine, wherein the second accumulator chamber  20  is as shown in FIG. 8 provided with the air intake  63 , the pressure reducing valve  21 , and the loading-unloading device  60 . 
     In this mode, the invention shown in FIG. 8 is applicable to the prior art nailing machine and the embodiment thereof is proved effective in accomplishing the same operation/working effect as what has been described with reference to FIG.  6 . 
     FIGS. 9-13 show still other examples of nailing machines according to the present invention, wherein the compressed air in the second accumulator chamber  20  can be discharged into the atmosphere through the operation from the outside. 
     FIG. 9 refers to an example of providing an operating element  44  for opening the check valve  22  so that the compressed air in the second accumulator chamber  20  can be discharged into the atmosphere via the check valve  22  and the air intake  16  by operating the element  44  after the termination of the work. 
     FIG. 10 refers to an example of providing a discharge valve  23  having an operating lever  26  operable from the outside, in place of the aforementioned check valve  22 . While the air hose  50  connected to the air compressor is connected to the air intake  16 , compressed air is made to flow into the second accumulator chamber  20  by opening the discharge valve  23  by operating the operating lever  26 . When the discharge valve  23  is opened while the air hose  50  is disconnected from the air intake  16 , the compressed air in the second accumulator chamber  20  can be discharged into the atmosphere. 
     FIG. 11 refers to an example of providing the discharge valve  23  that has the operating lever  26  operable from the outside and is capable of controlling providing and withholding the communication between the second accumulator chamber  20  and the atmosphere, the discharge valve  23  being installed in a place having no relation to the check valve  22 . When the discharge valve  23  is opened by operating the operating lever  26 , the compressed air in the second accumulator chamber  20  can be discharged into the atmosphere. 
     FIG. 12 refers to an example of providing the discharge valve  23  that has the operating element  44  operable from the outside and is capable of controlling providing and withholding the communication between the second accumulator chamber  20  and the atmosphere, the discharge valve  23  being installed in a place having no relation to the check valve  22 . When the discharge valve  23  is opened by operating the operating element  44 , the compressed air in the second accumulator chamber  20  can be discharged into the atmosphere. 
     FIG. 13 refers to an example of providing the discharge valve  23 , in addition to the check valve  22 , that has the operating lever  26  operable from the outside between the second accumulator chamber  20  and the air intake  16 . When the discharge valve  23  is opened by operating the operating lever  26 , the compressed air in the second accumulator chamber  20  can be discharged into the atmosphere via the air intake  16 . 
     Although the inside of the second accumulator chamber  20  is made to communicate with the atmosphere in the examples shown in FIGS. 9-13 above, an arrangement may be made so as to make the inside of the first accumulator chamber  2  communicate with the atmosphere by providing the discharge valve  23  and the operating lever  26  or the operating element  44  shown in FIGS. 11 and 12 for the handle portion  13  of the body  1 , for example. When the inside of the first accumulator chamber  2  is made to communicate with the atmosphere by operating the operating lever  26  or the operating element  44  in such an arrangement, the compressed air in the first accumulator chamber  2  is discharged into the atmosphere. However, the pressure in the first accumulator chamber  2  is reduced thereby and the compressed air in the second accumulator chamber  20  is caused to flow into the first accumulator chamber  2  via the pressure reducing valve  21  then. Consequently, the whole compressed air in the second accumulator chamber  20  will be discharged into the atmosphere ultimately via the pressure reducing valve  21  and the first accumulator chamber  2  if the inside of the first accumulator chamber  2  is made to communicate with the atmosphere by operating the operating lever  26  or the operating element  44 . With this arrangement, the exhaust sound is reduced in comparison with a case where the compressed air in the high-pressure second accumulator chamber  20  is discharged into the atmosphere because the pressure of the compressed air that is discharged into the atmosphere is within the set pressure in the first accumulator chamber  2 . 
     The nailing machine according to the present invention is provided with the second accumulator chamber capable of accumulating compressed air having a pressure higher than air pressure usable by the machine body, the air intake connectable to the air compressor via the air hose, the valve for control of the communication between the second accumulator chamber and the air intake, and the pressure reducing valve for reducing the compressed air pressure in the second accumulator chamber and supplying the pressure-reduced compressed air into the first accumulator chamber. Consequently, the nailing work can be done in such a state that the nailing machine has been connected to the air compressor and that it has been disconnected from the air compressor. It is thus possible to provide a nailing machine offering excellent workability as the nailing machine is usable while it is not connected to the air compressor with the air hose or the like and making the refilling of compressed air easier. Moreover, workability becomes improvable further because many nails  6  can be driven in by means of the small-capacity second accumulator chamber  20 .