Abstract:
A pneumatic motor trigger actuator includes a trigger housing adapted to engage a pneumatic motor trigger of a pneumatic tool. A top plate is coupled to the trigger housing. A primary valve is coupled to the top plate and has an open configuration and a closed configuration. The primary valve is pneumatically coupled to the trigger housing such that air flow through the primary valve, when the primary valve is in the open configuration, enters the trigger housing and causes a plug to physically engage the motor trigger with sufficient force to move it to is fully engaged position. The primary valve includes a primary switch and an automatic stop switch. The primary switch is engagable by an operator to configure the primary valve in the open configuration. The automatic switch is engagable by an object to move the primary valve to the closed configuration when a predetermined condition is met.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to pneumatic tools, and more particularly to a pneumatic motor trigger actuator for a pneumatic tool.  
       BACKGROUND OF THE INVENTION  
       [0002]     Pneumatic tools are common throughout industry and are used in a wide variety of manufacturing settings. For example, pneumatic tools are prelevant in the aircraft manufacturing industry. One typical pneumatic tool used in the aircraft manufacturing industry is a hand held drilling unit. When drilling through an aircraft structure using a hand held drilling unit, an operator must maintain positive finger pressure against the start trigger of the drilling unit throughout the entire drilling cycle. While not necessarily significant under some conditions, when drilling through materials often used in the aerospace industry, it may take as long as six minutes to complete a single drilling cycle in this manner. Upon releasing the trigger, the trigger returns to its rest position and the pneumatic motor stops. The constant pressure maintained by the operator throughout a long drilling cycle may potentially cause hand and wrist fatigue.  
         [0003]     Prior solutions to hand and wrist fatigue have involved either rotating attachments or engagement buttons that require cumbersome movement of the operator&#39;s hand. While these solutions may reduce the length of time required to maintain pressure on the trigger, the operator is still required to initially depress the trigger and then perform additional operations. Accordingly, significant hand and wrist fatigue still occur during repetitive and cyclical use of a hand held drilling unit. Moreover, with these prior solutions, the operator is required to disengage the rotating attachment or engagement buttons at the end of each use.  
       SUMMARY OF THE INVENTION  
       [0004]     A pneumatic motor trigger actuator includes a trigger housing adapted to engage a pneumatic motor trigger. A top plate is coupled to the trigger housing. A primary valve is coupled to the top plate and has an open configuration and a closed configuration. The primary valve is pneumatically coupled to the trigger housing such that air flow through the primary valve when the primary valve is in the open configuration enters the trigger housing and engages the pneumatic motor trigger. The primary valve includes a primary switch and an automatic stop switch. The primary switch is engagable by an operator to configure the primary valve in the open configuration. The automatic switch is engagable by an object to configure the primary valve to the closed configuration when certain conditions are met. When the primary valve is in the closed configuration, air does not pass therethrough to the trigger housing and the pneumatic motor trigger is not engaged.  
         [0005]     By eliminating the need for an operator to continuously hold down the pneumatic motor trigger throughout a drilling operation, operator fatigue is greatly reduced. Additionally, automatic shutoff and emergency shutoff of the drilling cycle greatly increased safety and efficiency.  
         [0006]     The features, functions, and advantages can be achieved independently in various embodiments of the present inventions or may be combined in yet other embodiments. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]      FIG. 1  is a side view of a pneumatic motor trigger actuator constructed according to the principles of the present invention shown in operative association with an exemplary pneumatic drill;  
         [0009]      FIG. 2  is a top view of the pneumatic motor trigger actuator and exemplary pneumatic drill of  FIG. 1 ;  
         [0010]      FIG. 3  is a side view of the pneumatic motor trigger actuator and exemplary pneumatic drill shown in an automatic shutoff condition;  
         [0011]      FIG. 4A  is a perspective view of a trigger housing used in the pneumatic motor trigger actuator of the present invention;  
         [0012]      FIG. 4B  is a perspective view of a top plate used in the pneumatic motor trigger actuator of the present invention;  
         [0013]      FIG. 4C  is a perspective view of a trigger plug used with the pneumatic motor trigger actuator of the present invention;  
         [0014]      FIG. 4D  is a perspective view of a preset spring stop used with the pneumatic motor trigger actuator of the present invention;  
         [0015]      FIG. 5A  is a partial cross-sectional view of the pneumatic motor trigger actuator in a unengaged condition;  
         [0016]      FIG. 5B  is a partial cross-sectional view of the pneumatic motor trigger actuator in an engaged condition;  
         [0017]      FIG. 6A  is a side view of an alternate pneumatic motor trigger actuator having a modified motor trigger shown in operative associated with an exemplary pneumatic tool; and  
         [0018]      FIG. 6B  is an isometric disassembled view of the modified motor trigger shown in  FIG. 6A . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0020]     With reference to  FIG. 1 , a preferred embodiment of a pneumatic motor trigger actuator (hereinafter “trigger actuator”)  10  constructed according to the principles of the present invention is shown in operative association with an exemplary pneumatic drill  12 . The pneumatic drill  12  generally includes a motor housing  14  with a handle  16  extending therefrom. The motor housing  14  contains a pneumatic motor (not shown) located therein. An air input tube  18  is coupled to the pneumatic drill  12  at the handle  16 . The air input tube  18  provides compressed air flow to the pneumatic motor (not shown) of the pneumatic drill  12  from a compressed air source (not shown).  
         [0021]     The pneumatic drill  12  further includes a drill bit  20  extending out from the motor housing  14 . The drill bit  20  is rotationally driven by the pneumatic motor (not shown) using the compressed air flow. A drill cap  22  is slidably coupled to the motor housing  14  and extends around the drill bit  20 . The drill cap  22  prevents debris from being ejected from the drill bit  20  as it is driven into a surface.  
         [0022]     A trigger  24  is mounted within the handle  16  beneath the motor housing  14 . When the trigger  24  is depressed by an operator of the pneumatic drill  12 , the pneumatic motor (not shown) is activated which in turn rotates the drill bit  20 . As the drill bit  20  is drilled into a work surface (not shown), the drill cap  22  slides relative to the drill bit  20  and the motor housing  14  towards the motor housing  14 . The drill cap  22  thereby completely encompasses the drill  22  as it is drilled into a work piece and protects the operator or bystanders from flying debris throughout the drilling cycle. While in the particular example provided, a pneumatic drill  12  has been described, it should be appreciated that any pneumatic tool may be employed with the trigger actuator  10 .  
         [0023]     With continued reference to  FIG. 1 , the trigger actuator  10  generally includes a trigger housing  26 , a top plate  28 , and a valve assembly  30 . Turning briefly to  FIG. 4A , the trigger housing  26  includes a body  32  having a trigger retention portion  34  and a flange portion  36 . The trigger retention portion  34  is preferably opened at an end thereof and defines a cavity  38 . The cavity  38  is sized to receive at least a portion of the trigger  24  ( FIG. 1 ) of the pneumatic drill  12  therein. An aperture  40  extends from the cavity  38  into the flange portion  36 . The aperture  40  is sized to receive a cylindrical piston  42  ( FIG. 4C ) therein. As will be described in greater detail below, compressed air is channeled into the aperture  40  from an opening  44 , as best seen in  FIG. 1 , formed on the outside of the body  32 . The flange portion  36  includes an upper surface  46  having a contour matching that of the motor housing  14  ( FIG. 1 ) of the pneumatic drill  12 . Additionally, a pair of bolt holes  48  ( FIG. 4A ) extend through the flange portion  36  and are used in coupling the trigger housing  26  to the top plate  28 , as will also be described below.  
         [0024]     With reference to  FIG. 4B , the top plate  28  includes a top surface  50  and a bottom surface  52 . The top surface  50  is substantially flat and is adapted to receive the valve assembly  30  ( FIG. 1 ) thereon as will be described below. The bottom surface  52  is contoured to match the shape of the motor housing  14  ( FIG. 1 ) of the pneumatic drill  12 . The top plate  28  further includes a pair of bolt holes  54  extending from the top surface  50  to the bottom surface  52 .  
         [0025]     Turning back to  FIG. 1 , the trigger housing  26  is coupled to the pneumatic drill  12  such that the trigger  24  extends within the cavity  38  ( FIG. 4A ) of the trigger housing. The motor housing  14  sits within the contour top surface  46  ( FIG. 4A ) of the trigger housing  26 . The flange portion  36  extends to either side of the motor housing  14 . The top plate  28  sits atop the motor housing  14  such that the contour bottom surface  52  of the top plate  28  rests atop the motor housing  14 . The top plate  28  and the trigger housing  26  are then coupled together using bolts  56  that extend through the bolt holes  54  ( FIG. 4B ) of the top plate  28  and through the bolt holes  48  ( FIG. 4A ) of the trigger housing  26 . The valve assembly  30  is then coupled to the top surface  50  of the top plate  28 .  
         [0026]     Turning now to  FIG. 2 , the valve assembly  30  preferably includes a primary air valve  58  and an emergency stop air valve  60 . The primary air valve  58  is preferably a one way valve that when in an opened position allows compressed air to travel therethrough and when in a closed position prevents compressed air from traveling therethrough. The primary air valve  58  is normally in a closed position until actuated. The primary air valve  58  includes a start up button  62  extending therefrom. Engaging the start up button  62  urges the primary air valve into an opened position. An adjustable feed depth controller  64  extends from an opposite side of the primary air valve  58  such that the adjustable feed depth controller  64  extends toward the drill cap  22 . With brief reference to  FIG. 3D , the adjustable feed depth controller  64  includes a body  66  having a spring stop  68  extending from an end thereof. The spring stop  68  is biased such that it extends out from the body  66 . However, the spring stop  68  may move relative to the body  66  against the biasing force.  
         [0027]     The emergency stop air valve  60  likewise is a one way air valve having an opened position and a closed position similar to that of the primary air valve  58 . The emergency stop air valve  60  is normally in an open position until actuated. The emergency stop air valve  60  includes an emergency stop button  70  extending therefrom. Engagement of the emergency stop button  70  urges the emergency stop air valve  60  to its closed position.  
         [0028]     Turning to  FIG. 3 , the automatic shutoff of the pneumatic drill  12  after the end of a drilling cycle will be described. As the pneumatic drill  12  drills into a work piece, the drill cap  22  moves relative to the motor housing  14  until it engages the spring stop  68 , as shown. The adjustable feed depth controller  64  is coupled to the primary air valve  58  such that when the spring stop  68  is urged towards the primary air valve  58  by the drill cap  22 , the spring stop  68  urges the primary air valve  58  to its closed position. By adjusting the length to which the body  66  of the adjustable feed depth controller  64  extends from the primary air valve  58  the depth to which the pneumatic drill  12  may drill may be automatically set. In other words, the distance between the spring stop  68  and the drill cap  22  defines the depth to which the pneumatic drill  12  may drill. This is because as the drill cap  22  engages the spring stop  68 , the spring stop  68  will urge the primary air valve  58  to its closed position, thereby disengaging the pneumatic motor (not shown) as will be described below. In the particular example provided, the body  66  is extendable by unscrewing a first portion  67  relative to a second portion  69  to adjust the length that the spring stop  68  extends from the body  66 . It should be appreciated, however, that various other devices or means may be employed for automatically adjusting the drill depth or drill cycle such as, for example, a timed cycle.  
         [0029]     With reference to  FIGS. 1 and 2 , the air flow of the trigger actuator  10  will now be described. First, a portion of compressed air being supplied through air input tube  18  is used to pressurize a first conduit  80 . The first conduit  80  is then coupled to both the primary air valve  58  and the emergency air valve  60  via sections  80   a  and  80   b  and T-section  80   c . A second conduit  82  provides a flow path for the compressed air from the emergency stop air valve  60  to the primary air valve  58 . This links the primary air valve  58  and the emergency stop air valve  60  in series. A third conduit  84  then directs the compressed air to the aperture  40  ( FIG. 4A ) of the trigger housing  26 .  
         [0030]     When a user engages the start up button  62  to open the primary air valve  58 , this allows compressed air to flow from the first conduit  80  and section  80   a  into primary air valve  58 , and through the emergency stop air valve  60 , through the second conduit  82 , through the third conduit  84 , and on into the trigger housing  26 . In an alternate preferred embodiment, the emergency stop air valve  60  is in a normally “closed” configuration. Compressed air flows from the first conduit  80  and through sections  80   a  and  80   b  into both the primary air valve  58  and the emergency stop air valve  60 . Engagement of the emergency stop air valve  60  to its “open” position allows compressed air to flow through the second conduit  82  into the primary air valve  58  such that this compressed air flow urges the primary valve  58  back into its “closed” configuration, thereby shutting off air flow to the trigger housing  26  and accordingly shutting off the pneumatic drill  12 .  
         [0031]     As can be seen in  FIG. 5A , the normal bias of the motor trigger  24  urges the piston  42  into the aperture  40  and accordingly keeps the pneumatic drill  12  in an “off” condition. However, as can be seen in  FIG. 5B , as the compressed air from the third conduit  84  urges the cylindrical piston  42  out of the aperture  40  it engages the motor trigger  24  of the pneumatic drill  12 . This in turn starts the pneumatic drill  12 . A continuous source of compressed air will in turn maintain the motor of the pneumatic drill  12  in an “on” condition until such time as either the adjustable feed depth control  64  moves the primary air valve  58  to its closed position or an operator engages the emergency stop button  70  to urge the emergency stop air valve  60  to its closed position (or alternatively its open position according to the alternate preferred embodiment). At that time the compressed air flow to the trigger housing  26  will cease and the trigger  24  will move to its unengaged position as shown in  FIG. 5A , thereby interrupting the flow of compressed air to the motor and thus turning off the pneumatic drill  12 .  
         [0032]     With reference to  FIGS. 6A and 6B , an alternative preferred motor trigger assembly  100  is shown in operative association with the trigger actuator  10  and exemplary drill  12 . The modified motor trigger assembly  100  replaces the trigger housing  26  ( FIGS. 1 through 5 ) and the motor trigger  24  ( FIG. 1 ) of the pneumatic drill  12 . The modified motor trigger assembly  100  includes a motor trigger  102  inserted into a trigger retainer  104 . The trigger retainer  104  has a shape that is adapted to fit within a conventional pilot actuator  106 , such as, for example, a Clippard pilot actuator. A standard fitting  108  couples the third tube  84  with the pilot actuator  106 . Operation of the trigger actuator  10  with the motor trigger assembly  100  is substantially similar to that of the trigger housing  26  and motor trigger  24  in  FIGS. 1 through 5  in that compressed air flow through the valve assembly  30  urges the pilot actuator  106  to engage the modified motor trigger  102  in order to engage the pneumatic motor (not shown).  
         [0033]     By eliminating the need for an operator to continuously hold down the motor trigger  24  throughout a drilling operation, operator fatigue is greatly reduced. Furthermore, the pneumatic motor trigger actuator  10  may be installed on any pneumatic tool simply by adjusting the contour surfaces of the trigger housing  26  and the top plate  28  (e.g., modifying the top surface  46  and the bottom surface  52 ). In addition, the motor trigger actuator, in its preferred embodiments described herein, does not unnecessarily complicate the construction of a pneumatic drilling tool or add significantly to its cost of construction.  
         [0034]     While various preferred embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the inventive concept. The examples illustrate the invention and are not intended to limit it. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.