Patent Abstract:
A powered hand tool comprising a pneumatic motor including a cylinder, a main body formed as a hollow tube member, a main body rear end being formed with a fluid inlet and a fluid outlet, said main body being axially disposed for engagement with said pneumatic motor, a main body front end with an interior surface fitted for engagement with a lock nut, said pneumatic motor having a rotary shaft axially extending out of said main body front end wherein the diameter of said pneumatic motor is smaller than the diameter of said hollow tube member, an internal isolation layer composed of a vibration isolation material placed in said hollow tube member so that said vibration isolation material is engaged with and adjacent said ends of said hollow tube member and said pneumatic motor.

Full Description:
FIELD OF INVENTION 
       [0001]    The invention relates to vibration isolation and damping in hand tools. The embodiments shown and described herein are more particularly for isolating vibrations transferred to the user from the tool when using a pneumatic powered hand tool. 
       CROSS REFERENCE TO RELATED APPLICATIONS 
       [0002]    None 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0003]    No federal funds were used to develop or create the invention disclosed and described in the patent application. 
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX 
       [0004]    Not Applicable 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  shows an axial cross-sectional view of one embodiment of the present invention. 
           [0006]      FIG. 2  shows a blow-up of one embodiment of the present invention. 
           [0007]      FIG. 3  shows a blow-up of the pneumatic motor in one embodiment. 
           [0008]      FIGS. 4A ,  4 B and  4 C show three views of the front cap of the internal isolation layer fashioned for front end exhaust. 
           [0009]      FIGS. 5A ,  5 B and  5 C show three views of the rear cap of the internal isolation layer fashioned for front end exhaust. 
           [0010]      FIGS. 6A ,  6 B and  6 C show three views of the front cap of the internal isolation layer fashioned for rear end exhaust. 
           [0011]      FIGS. 7A ,  7 B, and  7 C show three views of the rear cap of the internal isolation layer fashioned for rear end exhaust. 
           [0012]      FIG. 8  shows a radial cross-sectional view of the main body rear end of one embodiment of the present invention. 
           [0013]      FIG. 9  shows one embodiment of the lock nut fashioned for front end exhaust. 
           [0014]      FIG. 10  shows one embodiment of the lock ring fashioned for front end exhaust 
       
    
    
     DETAILED DESCRIPTION—LISTING OF ELEMENTS 
       [0015]      
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Element Description 
                 Element Number 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Main Body 
                 1 
               
               
                   
                 Main Body Front End 
                 2 
               
               
                   
                 Main Body Rear End 
                 3 
               
               
                   
                 Fluid Passage 
                 4 
               
               
                   
                 Rotary Shaft 
                 5 
               
               
                   
                 Pneumatic Motor 
                 6 
               
               
                   
                 Throttle Mechanism 
                 7 
               
               
                   
                 Intentionally blank 
                 8 
               
               
                   
                 Pneumatic Hand Tool 
                 9 
               
               
                   
                 Lock Nut 
                 10 
               
               
                   
                 Hollow Tube Member 
                 11 
               
               
                   
                 Annular Space 
                 12 
               
               
                   
                 Throttle Lever 
                 13 
               
               
                   
                 Inlet Bushing 
                 14 
               
               
                   
                 External Isolation Layer 
                 15 
               
               
                   
                 Lock Ring 
                 16 
               
               
                   
                 Collet Assembly 
                 17 
               
               
                   
                 Stay Pin 
                 18 
               
               
                   
                 Rear Thrust Plate 
                 19 
               
               
                   
                 Front Thrust Plate 
                 20 
               
               
                   
                 Front Bearing Support Plate 
                 21 
               
               
                   
                 Cylinder 
                 22 
               
               
                   
                 Intentionally blank 
                 23 
               
               
                   
                 Internal Isolation Layer 
                 24 
               
               
                   
                 Front Cap 
                 25 
               
               
                   
                 Rear Cap 
                 26 
               
               
                   
                 Pneumatic Motor Front End 
                 27 
               
               
                   
                 Pneumatic Motor Rear End 
                 28 
               
               
                   
                 Fluid Inlet Hole 
                 29 
               
               
                   
                 Fluid Outlet Hole 
                 30 
               
               
                   
                 Intentionally blank 
                 31 
               
               
                   
                 Rear Bearing 
                 32 
               
               
                   
                 Front Bearing 
                 33 
               
               
                   
                 Machined Recess 
                 34 
               
               
                   
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,  FIG. 1  discloses and describes a vibration isolated pneumatic hand tool  9 . When referring to  FIGS. 1 ,  2 ,  3 ,  4 B,  5 B,  6 B and  7 B, the left side of the pneumatic hand tool  9  will be referred to as the rear of the pneumatic hand tool  9  and the right side of the pneumatic hand tool  9  will be referred to as the front of the pneumatic hand tool  9 ; additionally, the left side of elements axially disposed with the main body  1  will be referred to as the rear of the element while the right side of the element will be referred to as the front of the element. The pneumatic hand tool  9  in the embodiment shown in  FIG. 1  includes a main body  1  formed as a hollow tube member  11 . The main body rear end  3  includes a fluid passage  4  to allow fluid to move into and power the pneumatic motor  6 . In addition to compressed air, the power source may also be selected from the group consisting of electricity or other compressed fluids, such as steam or nitrogen. 
         [0017]    The pneumatic motor  6  is of the type well known to those skilled in the art, and may be of 0.3, 0.6 or 1.0 horsepower, depending on the embodiment. Accordingly, the present invention is not limited by the power rating of the pneumatic motor  6 . The fluid flow to the pneumatic motor  6  is controlled via the throttle mechanism  7 , for which the throttle lever  13  provides the user interface. The throttle mechanism  7  and throttle lever  13  are one type of work control means for controlling the work generating means as recited in the claims. 
         [0018]    In the embodiment shown in  FIGS. 1 ,  2  and  3 , the pneumatic motor rear end  28  is comprised of a rear thrust plate  19  and a rear bearing  32 , of the type well known to those skilled in the art, engaged with the rear end of a cylinder  22 . The pneumatic motor front end  27  is comprised of a front thrust plate  20 , a front bearing support plate  21  and a front bearing  33 , of the type well known to those skilled in the art, engaged with the front end of said cylinder  22 . The rear bearing  32  has a smaller outer diameter than the inner diameter of the rear thrust plate  19 , and in the embodiment shown in  FIG. 3 , the axial dimension of the rear bearing  32  is less than or equal to the axial dimension of the rear thrust plate  19  so that the rear bearing  32  completely seats within the rear thrust plate  19 . The rear bearing  32  engages both the rear end outer surface of the rotary shaft  5  and the inward surface of the rear thrust plate  19  so that the rear thrust plate  19  does not rotate with respect to the rotary shaft  5 . The front bearing  33  has a smaller outer diameter than the inner diameter of the front bearing support plate  21 , and in the embodiment shown in  FIG. 3 , the axial dimension of the front bearing  33  is less than or equal to the axial dimension of the front bearing support plate  21  so that the front bearing  33  completely seats within the front bearing support plate  21 . The front thrust plate  20  emulates the outward circumferential shape and size of the front bearing support plate  21 , and in the embodiment shown in  FIG. 3 , is axially positioned between and held stationary by the cylinder  22  and the front bearing support plate  21 . The front bearing  33  engages both the front end outer surface of the rotary shaft  5  and the inward surface of the front bearing support plate  21  so that neither the front bearing support plate  21  nor the front thrust plate  20  rotate with respect to the rotary shaft  5 . 
         [0019]    The main body  1  is axially disposed with the pneumatic motor  6 . The rotary shaft  5  of the pneumatic motor  6  extends axially from the main body front end  2 . A collet assembly  17  is engaged with the rotary shaft  5  on the rear end of the collet assembly  17  (as shown in  FIG. 2 ). The collet assembly  17  is able to engage a plurality of rotational tools such as a bit, a grinding wheel or a cutter on its front end, as is known to those skilled in the art. The collet assembly  17  is one means of coupling a tool to the rotary shaft  5  as recited in the claims. A lock nut  10  is fashioned, most commonly with threads on the circumferentially outward surface, to engage both the circumferentially inward surface of the main body front end  2  and to engage a portion of the pneumatic motor front end  27  in such a way as to fix the axial position of the pneumatic motor  6  with respect to the main body front end  2 . This is most commonly achieved via threads on a portion of the pneumatic motor front end  27  that engage threads on the lock nut  10 , but other means may be used by those skilled in the art. In one embodiment, a lock ring  16  is fitted with threads on the circumferentially inward surface for engagement with a portion of the circumferentially outward threads on the lock nut  10  so that when the lock ring  16  is tightened against the main body front end  2 , the lock nut  10  is held in place by the lock ring  16 . 
         [0020]    In the present invention an internal isolation layer  24  is placed between the pneumatic motor  6  and the main body  1  in order to minimize the number and magnitude of vibrations transferred from the pneumatic motor  6  to the main body  1 . Additionally, the internal isolation layer  24  provides noise reduction associated with vibrations caused by operation of the pneumatic hand tool  9 . The internal isolation layer  24  may be fashioned to eliminate any metal on metal contact between the main body  1  and the pneumatic motor  6 . In the embodiment shown in  FIG. 1 , an external isolation layer  15  is placed on the external surface of the main body  1  in order to minimize the number and magnitude of vibrations transferred from the main body  1  to the user. The external isolation layer  15  also serves to provide comfort to the user&#39;s hand and a better grip on the pneumatic hand tool  9 . Further benefits of the external isolation layer  15  are that it serves to reduce sound generated by operation of the pneumatic hand tool  9  and acts as a temperature insulator between the main body  1  and the user&#39;s hand. The internal isolation layer  24  is one means of reducing the number and magnitude of vibrations transferred from the work generating means to the main body  1  as recited in the claims. 
         [0021]    In the embodiment shown in  FIGS. 1 and 2 , the internal isolation layer  24  consists of two caps, a front cap  25  and a rear cap  26 , with an annular space  12  disposed axially between the front cap  25  and the rear cap  26 . The front cap  25  is formed so as to fully engage both the pneumatic motor front end  27  circumferentially outward surface  6  and the circumferentially inward surface of the main body front end  2  so that the front cap  25  and the circumferentially inward surface of the main body front end  2  fix the radial position of pneumatic motor front end  27  with respect to the main body front end  2 . In the embodiment shown in  FIG. 1 , the front cap  25  extends axially over the front thrust plate  20 , front bearing support plate  21  and the small portion at the front of the cylinder  22  that has an outer circumferential shape that emulates the outer circumferential shape of the front thrust plate  20 . When the pneumatic hand tool  9  in the embodiment shown in  FIG. 1  is fully assembled, the rear surface of the lock nut  10  is engaged with the front surface of the front cap  25 , preventing movement towards the main body front end  2  within the hollow tube member  11 . 
         [0022]    The rear cap  26  is formed so as to fully engage both the pneumatic motor rear end  28  circumferentially outward surface and the circumferentially inward surface of the main body rear end  3  so that the rear cap  26  and the circumferentially inward surface of the main body rear end  3  fix the radial position of the pneumatic motor rear end  28  with respect to the main body rear end  3 . In one embodiment, the rear cap  26  extends axially over the rear thrust plate  19  and the small portion at the rear of the cylinder  22  that has an outer circumferential shape that emulates the outer circumferential shape of the rear thrust plate  19 . The rear cap  26  is also formed with a stay pin  18  that engages a machined recess  34  in the main body rear end  3  to ensure that only the rotary shaft  5  rotates with respect to the main body  1  when the pneumatic motor  6  is energized, preventing the pneumatic motor  6  from rotating with respect to the main body  1 . When the pneumatic hand tool  9  in the embodiment shown in  FIG. 1  is fully assembled, the portion of the main body rear end  3  that is transverse with respect to the rotary shaft (that portion in which the machined recess  34  is located and shown in  FIG. 8 ) is engaged with the rear surface of the rear cap  26  so that any corresponding fluid inlet holes  29  and/or fluid outlet holes  30  in the rear cap  26  and the main body rear end  3  are properly aligned for communication. This engagement also prevents any element within the hollow tube member  11  from moving towards the main body rear end  3 . Additionally, this engagement, in conjunction with the front cap  25  and the lock nut  11 , fixes the axial position of the pneumatic motor  6  within the main body  1 . 
         [0023]    The front cap  25  and rear cap  26  are composed of a vibration isolating material, such as an elastomeric ether or ester based polyurethane, or an elastomeric vinyl, suitable for the specific pneumatic hand tool  9  the front cap  25  and rear cap  26  are to be used with. The material of the internal isolation layer  24  is chosen depending on the frequency of vibrations the pneumatic hand tool  9  generates and the typical operating temperatures of the pneumatic hand tool  9 . In the embodiment shown in  FIG. 1 , a material with a shore A hardness between 45 and 70 is most effective for minimizing the vibrations transferred from the pneumatic motor  6  to the main body  1  at ambient temperature. The internal isolation layer  24  acts as a shock absorber between the pneumatic motor  6  and the main body  1  to minimize the number and magnitude of vibrations transferred from the pneumatic motor  6  to the main body  1 . In the embodiment shown in  FIGS. 1 and 2 , the internal isolation layer  24  ensures that there is no metal to metal contact between the main body  1  and pneumatic motor  6 , which also reduces the amount of sound generated during operation of a pneumatic hand tool  9 . In the embodiment shown in  FIG. 1 , the front cap  25  and rear cap  26  are of such an axial dimension as to allow for a predetermined amount of annular space  12  between the axial portions of the front cap  25  and rear cap  26 . The annular space  12  provides an area for exhaust fluid to be discharged from the pneumatic motor  6 . The front cap  25  and rear cap  26  may be slightly compressed in the embodiment shown in  FIG. 1  depending on the degree of axial force used to secure the lock nut  10  and/or lock ring  16  within the main body  1 . 
         [0024]    The invention allows pneumatic hand tools  9  to be specified as rear end exhaust or front end exhaust. The internal isolation layer  24  is ported to communicate with different fluid inlet holes  29  and fluid outlet holes  30  in the main body  1 , lock nut  10  or lock ring  16 , depending on the specified exhaust location. In a rear end exhaust pneumatic hand tool  9  (for which one embodiment of the front cap  25  is shown in  FIGS. 6A ,  6 B and  6 C; and for which one embodiment of the rear cap  26  is shown in  FIGS. 7A ,  7 B and  7 C), the rear cap  26  is formed with fluid inlet holes  29  that correspond to fluid inlet holes  29  in the main body rear end  3 . The rear cap  26  is further formed with fluid outlet holes  30  that correspond to fluid outlet holes  30  machined into the main body rear end  3  (see  FIG. 8 ). The fluid outlet holes  30  machined in the main body rear end  3  communicate with corresponding fluid passages (not shown) in the inlet bushing  14  to exhaust spent fluid to the atmosphere as in designs currently available and well known to those skilled in the art. In a rear end exhaust embodiment, the exhaust passes from the pneumatic motor  6  to the annular space  12 , through the outlet holes  30  in the rear cap  26  and through the outlet holes  30  in the main body rear end  3  to the fluid passages (not shown) in the inlet bushing  14 , from where the exhaust is discharged to the atmosphere. In a front end exhaust pneumatic hand tool  9  (for which one embodiment of the front cap  25  is shown in  FIGS. 4A ,  4 B and  4 C; and for which one embodiment of the rear cap  26  is shown in  FIGS. 5A ,  5 B and  5 C), the rear cap  26  is formed with fluid inlet holes  29  that correspond to fluid inlet holes  29  machined in the main body rear end  3 , but the rear cap  26  has no fluid outlet holes  30  in this embodiment (see  FIGS. 5A and 5C ). The front cap  25 , lock nut  10  and lock ring  16  are formed with corresponding fluid outlet holes  30  (see  FIGS. 4A ,  4 C,  9  and  10 ), so that spent fluid exhausted into the annular space  12  passes through the fluid outlet holes  30  in the front cap  25  and the corresponding fluid outlet holes  30  in the lock nut  10  and lock ring  16 , from where the exhaust is discharged to the atmosphere. 
         [0025]    The present invention allows for the front cap  25  and rear cap  26  of the internal isolation layer  24  to be easily disengaged from a pneumatic motor  6  if the pneumatic motor  6  becomes dysfunctional. The front cap  25  and rear cap  26  may then subsequently be easily engaged with a properly functioning pneumatic motor  6 . The front cap  25 , rear cap  26  and the properly functioning pneumatic motor  6  may easily be fitted inside the original main body  1 . Consequently, the main body  1 , front cap  25  and rear cap  26  may be used with a plurality of pneumatic motors  6 . Using the present invention, the pneumatic motor  6  of a pneumatic hand tool  9  may easily be removed and replaced or serviced without refitting the main body  1  with new or additional components to the internal isolation layer  24  or external isolation layer  15 . This allows for easily servicing the pneumatic motor  6  of a pneumatic hand tool  9  employing the disclosed internal isolation layer  24  and/or external isolation layer  15 . Embodiments of the present invention include, but are not limited to, pneumatic hand tools  9  using a 0.3, 0.6 or 1.0 horsepower pneumatic motor  6 . The pneumatic motor  6  as shown is one type or means of generating work, as recited in the claims, which may also be connected to other power sources such as an internal combustion system as recited in the claims. 
         [0026]    In the embodiment shown in  FIG. 1 , the external isolation layer  15  is engaged with the circumferentially outward portion of the main body  1  and occupies the surface of the main body  1  that is in contact with the user when the pneumatic hand tool  9  is in operation. The external isolation layer  15  need not engage the entire circumferentially outward surface of the main body  1 , but may be fashioned to engage such area of the circumferentially outward surface of the main body  1  that provides the user interface without interfering with the operation of the throttle lever  13 . The external isolation layer  15  may be affixed to the main body  1  by any means known to those skilled in the art, or it may be molded to the shape of the main body  1  for an interference fit between the main body  1  and the external isolation layer  15 . In the embodiment shown in  FIG. 1 , the external isolation layer  15  is fashioned of a thickness between one-eighth of an inch and three-sixteenths of an inch to minimize vibrations associated with a specific type or style of pneumatic hand tool  9  or to alleviate the symptoms associated with hand fatigue of a specific physical ailment. In this way, the external isolation layer  15  acts as a shock absorber between the main body  1  and the user to minimize the number and magnitude of vibrations transferred from the main body  1  to the user. The external isolation layer  15  also minimizes the hand fatigue experienced by the user during operation of the pneumatic hand tool  9  while simultaneously providing for a better grip. The external isolation layer  15  also reduces the amount of sound generated during operation of a pneumatic hand tool  9  and acts as a temperature insulator between the main body  1  and the user during operation. The material for the external isolation layer  15  is chosen in the same manner as the material for the internal isolation layer  24 . In some embodiments, such as the one disclosed in  FIG. 1 , the external isolation layer  15  and the internal isolation layer  24  are constructed of a similar material. In the embodiment shown in  FIG. 1 , the main body  1  is formed in an ergonomic wave contour and the external isolation layer  15  follows that same ergonomic wave contour so that the user&#39;s fingers may engage the trough of the wave contour, thereby further reducing the resulting amount of fatigue in the user&#39;s hand after operation of the pneumatic hand tool  9 . The external isolation layer  15  and ergonomic wave contour as shown are one means of surrounding the main body  1 , as recited in the claims. 
         [0027]    It should be noted that the present invention is not limited to the specific embodiments pictured and described herein, but is intended to apply to all similar apparatuses for minimizing the number and magnitude of vibrations transferred from a pneumatic hand tool  9  to the user during operation. Accordingly, modifications and alterations from the described embodiments will occur to those skilled in the art without departure from the spirit and scope of the present invention.

Technology Classification (CPC): 1