Abstract:
A forward/reverse mechanism and a pneumatic pressure operated power tool incorporating the mechanism are provided. The mechanism includes a rocker button having two lever portions and an actuator disposed next to one lever portion or a pair of actuators disposed next to both lever portions for engaging and rotating opposite sides of a periphery of a rotary valve spool for effecting rotation of the rotary spool in response to movement of the rocker button.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates generally to reversing valves for power tools and more particularly to a reversing valve for a pneumatically operated hand held power tool.  
           [0002]    In the past, reversing valves for power tools have been complicated in structure or difficult or inconvenient to operate. An improved rotary spool reversing valve is described in commonly assigned U.S. Pat. No. 5,199,460 to Geiger, the disclosure of which is incorporated herein by reference. The reversing valve described in the &#39;460 patent is operated in rotation by two parallel opposed push buttons. The spool is positioned in line with the incoming air passage permitting incoming air to flow axially through the spool directly to forward or reverse motor ports with a minimum of pressure loss. Thumb operation of the push buttons in a pistol grip tool permits convenient one hand operation with simple molded mechanisms providing economy and ease of operation. Although effective, the push buttons generally require a user to lift the thumb when switching between push buttons in order to change direction of the motor ports.  
           [0003]    The foregoing illustrates limitations known to exist in present reversing valves for power tools. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.  
         SUMMARY OF THE INVENTION  
         [0004]    A forward/reverse mechanism and a pneumatic pressure operated power tool incorporating the mechanism are provided. The mechanism includes a rocker button having two lever portions and an actuator disposed next to one lever portion or a pair of actuators disposed next to both lever portions for engaging and rotating opposite sides of a periphery of a rotary valve spool for effecting rotation of the rotary spool in response to movement of the rocker button.  
           [0005]    The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a partially sectioned elevation view of a rocker button activated forward/reverse mechanism for a power tool according to the present invention installed in a pneumatic operated power tool;  
         [0007]    [0007]FIG. 2 is an end elevation view showing the convenient location of the rocker button according to the present invention;  
         [0008]    [0008]FIG. 3 is a cross sectional view taken at Section  3 - 3  of FIG. 1 showing the rocker button and actuators according to the present invention;  
         [0009]    [0009]FIG. 4 is a distributor face plate of a conventional pneumatic tool;  
         [0010]    [0010]FIG. 5 is an end view of a distributor of a conventional rotary valve spool;  
         [0011]    [0011]FIG. 6 is a sectioned side elevation of the rotary valve spool taken at Section  6 - 6  of FIG. 5;  
         [0012]    [0012]FIG. 7 is the cross-sectional view of FIG. 3 showing a lever portion of the rocker button depressed in a first direction;  
         [0013]    [0013]FIG. 8 is the cross-sectional view of FIG. 3 showing a lever portion of the rocker button depressed in a second direction;  
         [0014]    [0014]FIG. 9 is a planar view showing the assembly of a rocker button activated forward/reverse mechanism for a power tool according to the present invention;  
         [0015]    [0015]FIG. 10 is an planar view showing an assembled rocker button activated forward/reverse mechanism for a power tool according to the present invention;  
         [0016]    [0016]FIG. 11 is an planar view showing an assembled rocker button activated forward/reverse mechanism having a single actuator according to the present invention; and  
         [0017]    [0017]FIG. 12 is a planar view showing an alternate actuator configuration for use with a rocker button according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    The invention is best understood by reference to the accompanying drawings in which like reference numbers refer to like parts. It is emphasized that, according to common practice, the various dimensions of the diaphragms and the associated component parts as shown in the drawings are not to scale and have been enlarged for clarity.  
         [0019]    Referring now to the drawings, shown in FIG. 1, a partial power tool  1  is shown in partial section. The power tool  1  is provided with a handle  2  having a pneumatic fluid or air inlet  3  for providing motive fluid to a pneumatic operated motor or air motor  13 . Air is supplied to the air motor through air inlet passageway  4 . A tilt valve  5  is operated by means of a trigger  6  to admit pressure fluid to a chamber  9 . valve for selectively distributing pressure fluid to a forward supply port  20  or optionally a reverse supply port  21  (shown hidden behind the forward supply port  20 ) at a position of approximately  180  degrees opposite the forward port in a planar plate  12  from the circular end of chamber  9 .  
         [0020]    The rotary valve spool  10  is provided with a planar segmented end (shown in a top view of the rotary valve spool in FIG. 5) which slidingly cooperates with the planar surface of planar plate  12  (shown in a bottom view of the planar plate  12  in FIG. 4). As shown in FIG. 3, which is a cross section taken at Section  3 - 3  of FIG. 1, the rotary valve spool  10  is formed with a plurality of pinion gear teeth  35  about its approximate midsection. As shown in FIG. 5, rotary valve spool  10  contains forward and reverse passageways  22  and  23 , and a notched area  29  which handles secondary exhaust, as will be described later in greater detail.  
         [0021]    Forward and reverse passageways  22  and  23  are located approximately 90 degrees apart and forward and reverse supply ports  20 ,  21  are located approximately 180 degrees apart, such that by rotating the rotary valve spool  10  approximately 90 degrees will bring one or the other passageways  22 ,  23  in contact with one of the supply ports  20 ,  21  leading to either the forward or reverse chambers of the motor.  
         [0022]    In operation, air entering the forward supply port  20  or reverse supply port  21  selectively proceeds to drive the air motor  13  in forward or reverse direction as the air is expanded against motor vanes  14  in the motor cylinder  15 . The motor rotates on bearings  16  and  16 ′ to drive an output shaft  17  which in turn drives a rotating shaft  18  of the working output device.  
         [0023]    Returning now to the cooperating face between the rotary valve spool  10  and the planar plate  12 , air passing the rotary valve spool  10  from air inlet passageway  4  in chamber  9  is directed to two face termination passageways  22 ,  23 . Partition  24  which forms the face seal of the rotary reversing valve is in the form of a semicircular circle having the two pie-shaped passageways  22  and  23  extending to the cooperating valve surface. The passageways  22 ,  23  selectively register with either forward port  20  or the reverse supply port  21  in the planar plate  12 . The notched area  29  registers with corresponding forward supply port  20  or reverse supply port  21  to bleed secondary exhaust which prevents recompression. The notched area  29  allows the secondary exhaust to enter main exhaust cavity  7 .  
         [0024]    It may now be appreciated by one skilled in the art that rotating the rotary valve spool  10  will accomplish direction of motive fluid to either forward or reverse the motor.  
         [0025]    According to the present invention, shown in FIGS.  1 - 3  and  7 - 11  is a rocker button  50  having two lever portions  52  and  54  located on either side of a post receiving slot  51  configured for attachment to a cylindrical post  36  located in power tool  1 . Located within each lever portion  52 ,  54  are posts  53 ,  55  as shown in FIGS. 3 and 7- 9 .  
         [0026]    Associated with each lever portion  52 ,  54  are actuators in the form of rack portions  63 ,  73  having rack teeth  64 , 74 , respectively, which cooperate with pinion teeth  35  on rotary valve spool  10 . Preferably, rack portions  63 ,  73  are attached to posts  53 ,  55  of lever portions  52 ,  54  via integrally provided clips  61 ,  71 . As shown in FIG. 9, rack portion  63  is attached to rocker button  50  by snapping clip  61  over post  53  and clip  71  over post  55  to form a double pinion-rack assembly shown in FIG. 10. Completed assembly is achieved by inserting rack portions  63 ,  73  into pneumatic tool  1  and snapping post receiving slot  51  over cylindrical post  36 .  
         [0027]    Switching of power tool  1  between a forward and reverse direction will now be explained. Upon depressing lever portion  52  to move rack portion  63  to the left with rack teeth  64  as shown in FIG. 8, rotates the rotary valve spool  10  in a counter-clockwise direction to align forward passageway  22  with forward supply port  20 . Conversely, upon depressing lever portion  54  to move rack portion  73  to the left with rack teeth  74  as shown in FIG. 7, rotates the rotary valve spool  10  in a clockwise direction to align reverse passageway  23  with reverse supply port  21 . The length of the rack and pinion cooperating teeth and their spacing cooperate to limit the depression excursion of the lever portions  52  and  54 .  
         [0028]    Referring to FIG. 6, rotary valve spool  10  is preferably provided with an “O” ring  26  in each of two “O” ring grooves  37  for the purposes of sealing the rack portions against intrusion of pressure fluid thereby preventing leakage to the operating rocker button.  
         [0029]    Thus, responsive to the movement of rocker button  50 , rack portions  63  and  73  move axially in a substantially perpendicular fashion to the axial rotation of the rotary valve spool  10  as it pivots about a fixed point. Due to the pivoting of rocker button  50 , the point where the rocker button comes in contact with the racks changes because the shafts are moving on a fixed axes. Thus, elongated grooves  62 ,  72  are shaped to allow free side-to side motion of posts  53 ,  55  (seen best in FIGS. 3, 7, and  8 ) while maintaining a positive connection to permit rocker button  50  to freely move pivotally about cylindrical post  36 .  
         [0030]    Most preferably, clips  61 ,  71  are “C”-shaped to facilitate assembly of power tool  1 . Alternatively, as shown in FIG. 12, rack portions  83  having a closed loop portions  84  with an elongated groove  82  may be utilized with a rocker button  50  comprised of two mating halves that snap-together or are otherwise attached together to form posts  53  and  55  through the closed loop portions.  
         [0031]    In yet another embodiment, shown in FIG. 11 is a single pinion-rack assembly in which only a single-actuator rack portion  63  is attached to rocker button  50  by snapping clip  61  over post  53 . Alternatively, a closed loop portion, as described above, may be used to attach the single-actuator portion to rocker button  50 . These single-actuator embodiments are particularly useful in facilitating the assembly of pneumatic tool  1  while reducing the number of parts required.  
         [0032]    Thus, a particular feature of the present invention is the control of the rotation of rotary valve spool using a single rocker button that can be easily operated with the thumb of one hand while operating the tool. Moreover, the rocker button according to the present invention may be easily manufactured using a molding operation and easily assembled to provide for economical tool manufacture.  
         [0033]    While embodiments and applications of this invention have been shown and described, it will be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein described. For example, although the rack portions and the rotary valve spool are shown and described having mating gear teeth, it is envisioned that alternate engaging mechanism such as a threaded worm-gear arrangement may be utilized.  
         [0034]    It is understood, therefore, that the invention is capable of modification and therefore is not to be limited to the precise details set forth. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims without departing from the spirit of the invention.