Patent Publication Number: US-7588093-B2

Title: Impact mechanism

Description:
This application is a non-provisional application claiming priority to U.S. provisional patent application Ser. No. 60/970,259 filed on Sep. 5, 2007 now abandoned, which is herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to impact mechanisms, and more particularly to impact mechanisms that are selectively mountable on an electric drill or the like. 
     BACKGROUND OF THE INVENTION 
     It is known to use a series of impacts of a hammer member on an anvil member to provide a significant force and highly effective rotational force in an impact driver. However, it is not known in the prior art to provide a portable assembly that is operatively engageable with the chuck of an electric drill or the like, which assembly provides a high impact rotational force, for turning a threaded fastener into a receiving article, such as a piece of wood, or removing a threaded fastener from a co-operating threaded shaft, and so on. It is also not known in the prior art to be able to readily adjust the impact rotational force of the impact driver. 
     It is an object of the present invention to provide a portable impact driver that is operatively engageable with the chuck of an electric drill or the like, which impact driver provides a high impact rotational force. 
     It is another object of the present invention to provide a portable impact driver that is operatively engageable with the chuck of an electric drill or the like, wherein it is possible to readily adjust the impact rotational force of the impact driver. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention there is disclosed a novel impact mechanism for use with a drive motor. The impact mechanism comprises a drive engaging member for engaging a rotatable output of a drive motor for rotation therewith about a longitudinal axis. A tool bit retaining member is operatively inter-connected with the drive engaging member for rotation with respect to the drive engaging member about the longitudinal axis. The tool bit retaining member has a main body portion, an anvil portion securely attached thereto for co-rotation with the main body portion, and a tool bit retaining means securely attached thereto for co-rotation with the main body portion. A hammer member is mounted on one of the drive engaging member and the tool bit retaining member for movement between an anvil contact position whereat force is transmitted from the hammer member to the anvil portion so as to create a moment about the longitudinal axis, and a release position whereat the hammer member is temporarily removed from the anvil portion. There is a guide means for moving the hammer member between the anvil contact position and the release position when the drive engaging member is rotated with respect to the tool bit retaining member. A spring means is operatively interconnected between the drive engaging member and the hammer member for biasing the hammer member to the anvil contact position. In use, rotation of the drive engaging member about the longitudinal axis causes the hammer member to move from its anvil contact position towards its release position, thereby storing potential energy in the spring means. When the hammer member reaches the release position, the hammer member is forcefully propelled by the spring means and the rotation of the drive engaging member to impact on the anvil portion, thus urging the tool bit retaining member to forcefully rotate about the longitudinal axis. 
     Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter of which is briefly described herein below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features which are believed to be characteristic of the impact mechanism according to the present invention, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred embodiment of the invention will now be illustrated by way of example. It is expressly understood, however, that the drawings are for the purpose of illustration and description only, and are not intended as a definition of the limits of the invention. In the accompanying drawings: 
         FIG. 1  is an exploded perspective view from the front of the first preferred embodiment of the impact mechanism according to the present invention; 
         FIG. 2  is a side elevational view of the first preferred embodiment of the impact mechanism of  FIG. 1 ; 
         FIG. 3  is front end view of the first preferred embodiment of the impact mechanism of  FIG. 1 ; 
         FIG. 4  is a sectional side elevational view of the first preferred embodiment of the impact mechanism of  FIG. 1 , taken along section line  4 - 4  of  FIG. 3 , and with the hammer member in its anvil contact position; 
         FIG. 5  is a sectional side elevational view similar to  FIG. 4 , but with the hammer member travelling from its anvil contact position towards its release position; 
         FIG. 6  is a sectional side elevational view similar to  FIG. 5 , but with the hammer member having reached its release position; 
         FIG. 7  is a sectional side elevational view similar to  FIG. 6 , but with the hammer member moving forwardly and rotationally to its anvil contact position, on the next anvil; 
         FIG. 8  is a perspective view of the tool bit retaining member of the first preferred embodiment of the impact mechanism of  FIG. 1 ; 
         FIG. 9  is a side elevational view of the drive engaging member of the first preferred embodiment of the impact mechanism of  FIG. 1 ; 
         FIG. 10  is a perspective view of the hammer member of the first preferred embodiment of the impact mechanism of  FIG. 1 ; 
         FIG. 11  is a perspective view of the first preferred embodiment of the impact mechanism of  FIG. 1 , with the housing removed for the sake of clarity, and with the hammer member in its anvil contact position; 
         FIG. 12  is a perspective view similar to  FIG. 11 , but with the hammer member travelling from its anvil contact position towards its release position; 
         FIG. 13  is a perspective view similar to  FIG. 12 , but with the hammer member having just reached its release position; 
         FIG. 14  is a perspective view similar to  FIG. 13 , but with the hammer member moving rotationally over the anvil portion, and towards its anvil contact position on the next anvil; 
         FIG. 15  is a perspective view similar to  FIG. 14 , but with the hammer member having moved rotationally off the anvil portion, and towards its anvil contact position on the next anvil; 
         FIG. 16  is a perspective view similar to  FIG. 15 , but with the hammer member moving forwardly and rotationally to its anvil contact position on the next anvil; 
         FIG. 17  is a perspective view from the front of the second preferred embodiment of the impact mechanism according to the present invention; 
         FIG. 18  is a sectional side elevational view of the second preferred embodiment of the impact mechanism of  FIG. 17 , taken along section line  18 - 18 ; and, 
         FIG. 19  is a sectional side elevational view similar to  FIG. 18 , but with the coil spring having been further compressed by the spring compression mechanism. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 through 19  of the drawings, it will be noted that  FIGS. 1 through 16  illustrate a first preferred embodiment of the impact mechanism of the present invention, and  FIGS. 17 through 19  illustrate a second preferred embodiment of the impact mechanism of the present invention. 
     Reference will now be made to  FIGS. 1 through 16 , which show a first preferred embodiment of the impact mechanism of the present invention, as indicated by general reference numeral  20 . The impact mechanism  20  is for use with a drive motor  22 . The impact mechanism  20  comprises a drive engaging member  30  for engaging a rotatable output, such as a chuck  24 , of a drive motor  22 , such as an electric drill, for rotation therewith about a longitudinal axis “L” about which the drive engaging member  30  rotates. 
     In the first preferred embodiment as illustrated, the drive engaging member  30  comprises a chuck-engageable portion  32  for engagement into the chuck of a drill (not shown). The chuck-engageable portion  32  is preferably hexagonally shaped, or of any other suitable shape, for secure engagement into the chuck of a drill for rotation therewith. 
     The drive engaging member  30  further comprises a forward shaft portion  34  and a cylindrical protrusion  33  that extends forwardly from the forward shaft portion  34  such that the forward shaft portion  34  is disposed immediately rearwardly of the front cylindrical protrusion  33 . The forward shaft portion  34  is preferably substantially cylindrical. The drive engaging member  30  further comprises an intermediate shaft portion  36  disposed between the forward shaft portion  34  and the chuck-engageable portion  32 , and is also preferably substantially cylindrical. As can be seen in the drawings, the intermediate shaft portion  36  has a larger diameter than the forward shaft portion  34 . 
     There is also a tool bit retaining member  40  operatively inter-connected with the drive engaging member  30  for rotation with respect to the drive engaging member  30  about the longitudinal axis. As can be seen in the Figures, the drive engaging member  30  is disposed immediately rearwardly of the tool bit retaining member  40 . The tool bit retaining member  40  has a main body portion  42 , an anvil portion  44  securely attached thereto for co-rotation with the main body portion  42 , and a tool bit retaining means  46  securely attached thereto for co-rotation with the main body portion  42 . 
     The tool bit retaining member  40  has a rear recess  48  therein at the longitudinal axis “L”. The front cylindrical protrusion  33  of the drive engaging member  30  is shaped and dimensioned for free rotational engagement in the rear recess  48  of the tool bit retaining member  40 . In this manner, the drive engaging member  30  and the tool bit retaining member  40  can rotate each with respect to the other about the longitudinal axis “L”, and also remain axially aligned. 
     As can be best seen in  FIGS. 1 and 8 , the anvil portion  44  is integrally formed with the tool bit retaining member  40 . Preferably, the anvil portion  44  comprises first and second squared anvils  44   a , 44   b  disposed at the back end of the tool bit retaining member  40 . Each of the first and second squared anvils  44   a , 44   b  projects radially outwardly from the main body portion  42  of the tool bit retaining member  40 . 
     A hammer member  50  is mounted on one of the drive engaging member  30  and the tool bit retaining member  40  for movement between an anvil contact position, as can be best seen in  FIGS. 4 and 11 , and a release position, as can be best seen in  FIGS. 6 and 13 . In the anvil contact position, force is transmitted from the hammer member  50  to the anvil portion  44  so as to create a moment about the longitudinal axis. In the release position, the hammer member  50  is temporarily removed from the anvil portion  44 . 
     The hammer member  50  preferably comprises an annular main body  52  and at least one hammer head portion  54  projecting forwardly from the annular main body  52 . In the first preferred embodiment, as illustrated, the at least one hammer head portion  54  comprises first and second hammer head portions  54   a , 54   b  projecting forwardly from the annular main body  52 . The annular main body  52  and the first and second hammer head portions  54   a , 54   b  are integrally formed one with the others for reasons of ease of manufacturing and structural strength and rigidity. Preferably, the hammer member  50  is more massive than the anvil portion  44  of the tool bit retaining member  40 , in order to be able to impart sufficient energy to the anvil portion  44  when the hammer member  50  impacts the anvil portion  44 . 
     There is also a guide means  60  for moving the hammer member  50  between the anvil contact position and the release position when the drive engaging member  30  is rotated with respect to the tool bit retaining member  40 . The guide means  60  is disposed on the forward shaft portion  34  and comprises first and second “V”-shaped grooves  62   a , 62   b  in the outer surface  31  of the forward shaft portion  34 , a co-operating first and second races  51   a , 51   b  in an interior surface  53  of the hammer member  50 . A first ball bearing  64   a  is operatively engaged in the first “V”-shaped groove  62   a  and the first race  51   a.  Similarly, a second ball bearing  64   b  is operatively engaged in the second “V”-shaped groove  62   b  and the second race  51   b.  As can be seen in  FIGS. 4 through 7 , the hammer member  50  surrounds the drive engaging member  30  and is retained in space relation from the drive engaging member  30  by the first and second ball bearings  64   a , 64   b.    
     There is a spring means  70  operatively interconnected between the drive engaging member  30  and the hammer member  50  for biasing the hammer member  50  to the anvil contact position. The spring means  70  preferably comprises a coil spring, but may alternatively comprising the other suitable type of spring. The coil spring  70  fits in close relation around the intermediate shaft portion  36 . 
     The drive engaging member  30  further comprises a spring retaining disk portion  39  projecting radially outwardly from the intermediate shaft portion  36 . The spring means  70  is received and retained between the spring retaining disk portion  39  and a co-operating annular recess  58  in the hammer member  50 . Preferably, the spring means  70  is in compression when the impact mechanism  20  is at rest, so as to increase the amount of potential energy that is temporarily gained by the coil spring  70  when the hammer member  50  moves from its anvil contact position to its release position. 
     The impact mechanism  20  further comprises a housing  80  substantially surrounding the drive engaging member  30  forwardly of the chuck-engageable portion  32 , the anvil portion  44  of the tool bit retaining member  40 , the hammer member  50 , and the spring means  70 . The housing  80  comprises an outer annular portion  82 , a front end portion  84 , and a back end portion  85 . The front end portion  84  comprises a removable and replaceable end cap  84  having an annular main body portion  86  and a forwardly disposed annular flange portion  88 . The annular main body portion  86  resides within the interior of the outer annular portion  82  of the housing  80 . The front surface  82   a  of the outer annular portion  82  of the housing  80  abuts against the rearwardly facing surface  88   a  of the annular flange portion  88 . The end cap  84  is retained in place by threaded fasteners (not specifically shown) that extend through apertures  82   b  in the front end of the outer annular portion  82  of the housing  80  and threadibly engage co-operating apertures  52   b  in the annular main body  52  of the end cap  84 . 
     As can be seen in  FIG. 4 , the front end portion  84  bears against a forwardly facing surface  41  on the tool bit retaining member  40  and the back end portion  85  bears against a rearwardly facing surface  30   a  on the drive engaging member  30 , to thereby retain the housing  80  in place and to keep the tool bit retaining member  40  operatively inter-connected with the drive engaging member  30 . 
     Reference will now be made to  FIGS. 11 through 16 , which show the impact mechanism  20  in use, with the housing  80  removed for the sake of clarity. In use, rotation of the drive engaging member  30  about the longitudinal axis “L” causes the hammer member  50  to move from its anvil contact position, as can be best seen in  FIG. 11 , towards its release position, as indicated by arrow “A” in  FIG. 12 . Accordingly, potential energy is stored in the spring means  70 , until the hammer member  50  reaches its release position, as is shown in  FIG. 13 . 
     When the hammer member  50  reaches the release position, the hammer member  50  is forcefully propelled, as indicated by arrow “B” in  FIG. 14 , by the rotation of the drive engaging member  30 , across the anvil portion  44 . When the hammer member  50  fully passed as the present anvil portion  44 , as can be seen in  FIG. 15 , the hammer member  50  is forcefully propelled by the spring means  70  and the rotation of the drive engaging member  30 , as indicated by arrow “C” in  FIG. 16 , to impact on the next anvil portion  44  (identical to  FIG. 11 ), thus urging the tool bit retaining member  40  to forcefully rotate about the longitudinal axis. 
     Reference will now be made to  FIGS. 17 through 19 , which show a second preferred embodiment of the impact mechanism of the present invention, as indicated by general reference numeral  220 . The second preferred embodiment impact mechanism  220  is similar to the first preferred embodiment impact mechanism  20  except that the second preferred embodiment impact mechanism  220  further comprises a somewhat modified housing  280  substantially surrounding the drive engaging member  230  forwardly of the chuck-engageable portion  232 , the anvil portion  244  of the tool bit retaining member  240 , the hammer member  250 , and the spring means  270 . The housing  280  comprises an outer annular portion  282 , a front end portion  284 , and a back end portion  286 . The front end portion  284  bears against a forward facing surface  241  on the tool bit retaining member  240  and the back end portion  286  bears against a rearwardly facing surface  230   a  on the drive engaging member  230 , to thereby retain the housing  280  in place and to keep the tool bit retaining member  240  operatively inter-connected with the drive engaging member  230 . 
     The second preferred embodiment impact mechanism  220  further comprises a selectively adjustable spring compression mechanism  290 , for permitting selective compression of the spring means  270 . The selectively adjustable spring compression mechanism  290  comprises an externally threaded annular main body member  291  threadibly engaged in a co-operating threaded aperture  286   a  in the back end portion  286  of the housing  280 , and a manually manipulable handle  292  secured to the externally threaded annular main body member  291  so as to be disposed exteriorly to the housing  280 . The externally threaded annular main body member  291  operatively engages the spring means  270 , to thereby permit selective compression of the spring means  270  through rotation of the manually manipulable handle  292 . 
     The impact mechanism  220  further comprising a spring receiving plate  294  disposed between the externally threaded annular main body member  291  and the spring means  270 . 
     In use, as the manually manipulable handle  292  is rotated clockwise, the spring means  270  is compressed, thus causing greater potential energy to be stored in the spring means  270 . Accordingly, when the spring means  270  is further compressed by the predetermined distance that is equal to the movement of the hammer member from its anvil contact position to its release position, it stores more potential energy than at a lesser spring compression. Resultingly, the hammer member  250  impacts against the anvil portion  244  with greater force. 
     Conversely, as the manually manipulable handle is rotated counter-clockwise, the spring means  270  is de-compressed. 
     In another alternative embodiment, it is contemplated that the adjustment of the compression of the spring means could be accomplished by a threaded fastener that is inset within the housing, and that the back end portion of the housing would need to be removed in order to adjust the compression of the spring means. In order to make this adjustment, it might be necessary to place the impact driver in a vise, and then use a screwdriver or Allen key, or the like, to adjust the threaded fastener. In this manner, the compression of the spring means would not be inadvertently altered. 
     It is also contemplated that the compression of the spring means could be adjusted through the use of a gearing system. 
     As can be understood from the above description and from the accompanying drawings, the present invention provides a portable impact driver that is operatively engageable with the chuck of an electric drill or the like, which portable impact driver provides a high impact rotational force, and wherein it is possible to readily adjust the impact rotational force of the portable impact driver, all of which features are unknown in the prior art. 
     Other variations of the above principles will be apparent to those who are knowledgeable in the field of the invention, and such variations are considered to be within the scope of the present invention. Further, other modifications and alterations may be used in the design and manufacture of the impact mechanism of the present invention without departing from the spirit and scope of the accompanying claims.