Patent Publication Number: US-2005120832-A1

Title: Ratchet wrench

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a ratchet wrench, and more particularly to a ratchet wrench having a solid driving mechanism for driving tools or fasteners.  
      2. Description of the Prior Art  
      Various kinds of typical ratchet wrenches have been developed and comprise a driving shank rotatably received in a head of a driving tool, and a ratchet mechanism or device disposed between the driving shank and the head of the driving tool, for allowing the driving shank to be rotated or driven in either a counterclockwise direction or a clockwise direction relative to the head of the driving tool.  
      For example, as shown in  FIGS. 1-3 , illustrated is a typical ratchet wrench comprising a handle  10 , a head  11  formed or provided on one end of the handle  10  and including a chamber  12  formed therein for rotatably receiving a follower  40  therein, and including a peripheral bulge  14  extended radially into the chamber  12  of the head  11 .  
      A ring or a washer  20  is secured to the lower portion of the head  11  with such as a retaining ring  15  which may be engaged into an inner peripheral recess  13  of the head  11 , such that the washer  20  may enclose the lower portion of the chamber  12  of the head  11 . The washer  20  includes a bore  21  formed therein. The washer  20  may be engaged with the peripheral bulge  14  of the head  11 , and may thus be solidly secured to the head  11 .  
      The follower  40  includes a driving shank  41  extended therefrom and rotatably received in the bore  21  of the washer  20  and having a peripheral groove  42  formed therein for receiving another retaining ring  23  which may be engaged with the washer  20 , to rotatably secure the follower  40  to the head  11  with the washer  20 . As shown in  FIGS. 3 and 4 , the follower  40  includes an outer diameter smaller than the inner diameter of the chamber  12  of the head  11 , such that an annular channel  17  may be formed between the follower  40  and the head  11 .  
      The follower  40  includes three or more, such as six recesses  43  formed in six sides  44  thereof, to form six pairs of flat actuating surfaces  45  thereon, best shown in  FIGS. 3 and 4 . The flat actuating surfaces  45  of flat follower  40  has an included angle “θ” with the inner peripheral surface of the head  11  ( FIG. 4 ). The follower  40  further includes three pairs of depressions  46 ,  47  formed in the upper portion thereof and arranged corresponding to the pairs of flat actuating surfaces  45  thereof.  
      A cap  30  rotatably received in the chamber  12  of the head  11 , and engaged with the peripheral bulge  14  of the head  11 , to position the cap  30  relative to the head  11 , and to prevent the cap  30  from being disengaged from the head  11 . The cap  30  includes an aperture  31  formed therein to rotatably receive a shaft  48  that is extended from the follower  40 , and that includes a peripheral groove  49  formed therein to receive another retaining ring  32  which may engage with the cap  30 , to rotatably secure the cap  30  to the follower  40 .  
      The cap  30  includes three or more, such as six actuator fingers  33  extended therefrom, to form three or more, such as six spaces  34  between the actuator fingers  33 , and to receive form three or more, such as six rollers  50  within the spaces  34  of the cap  30 . The rollers  50  may be caused to engage with either of the flat actuating surfaces  45  of the follower  40  by rotating the cap  30  relative to the head  11 . The actuator fingers  33  and the rollers  50  are received in the annular channel  17  formed between the follower  40  and the head  11 .  
      The cap  30  further includes three cavities  35  formed therein to receive three springs  60  and three balls or projections  70  that may be biased by the springs  60  to engage into either of the depressions  46 ,  47  of the follower  40 , and to position the follower  40  relative to the head  11 , and to maintain the rollers  50  in engagement with the respective flat actuating surfaces  45  of the follower  40 .  
      However, as shown in  FIG. 4 , due to the flat actuating surfaces  45  of the follower  40 , the rollers  50  may not be suitably or solidly engaged between the respective flat actuating surfaces  45  of the follower  40  and the inner peripheral surface of the head  11 . Particularly, when the follower  40  is slowly rotated relative to the head  11 , the rollers  50  may slip relative to the flat actuating surfaces  45  of the follower  40 , such that the follower may not be solidly driven or rotated by the head  11 .  
      The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional ratchet wrenches.  
     SUMMARY OF THE INVENTION  
      The primary objective of the present invention is to provide a ratchet wrench including a solid driving mechanism for solidly driving tools or fasteners.  
      In accordance with one aspect of the invention, there is provided a ratchet wrench comprising a head provided on a handle and including a chamber formed therein, and including a peripheral bulge extended radially into the chamber of the head, a follower rotatably received in the chamber of the head, and including an outer diameter smaller than an inner diameter of the chamber of the head, to form an annular channel between the follower and the head, the follower including six sides each having a recess formed therein, to form six pairs of curved actuating surfaces thereon, a cap rotatably received in the chamber of the head, and engaged with the peripheral bulge of the head, to position the cap relative to the head, the cap including at least three actuator fingers extended therefrom, to form at least three spaces between the actuator fingers, at least three rollers received within the spaces of the cap, the actuator fingers of the cap and the rollers being received in the annular channel formed between the follower and the head, the rollers being caused to be engaged between the curved actuating surfaces of the follower and the peripheral bulge of the head by rotating the cap relative to the head, and means for positioning the cap relative to the follower, to maintain engagements of the rollers with the respective curved actuating surfaces of the follower respectively. The curved actuating surfaces of the follower are arranged to allow the rollers to be solidly engaged between the curved actuating surfaces of the follower and the peripheral bulge of the head.  
      The head includes a washer secured thereto with a retaining ring and engaged with the peripheral bulge of the head, the washer includes a bore formed therein, the follower includes a driving shank extended therefrom and rotatably received in the bore of the washer and rotatably secured to the washer with a second retaining ring.  
      The cap includes an aperture formed therein, the follower includes a shaft extended therefrom, and rotatably engaged through the aperture of the cap, and rotatably secured to the cap with a retaining ring.  
      Further objectives and advantages of the present invention will become apparent from a careful reading of the detailed description provided hereinbelow, with appropriate reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exploded view of a typical ratchet wrench;  
       FIG. 2  is a partial cross sectional view of the typical ratchet wrench;  
       FIG. 3  is a partial top plan and partial cross sectional view of the typical ratchet wrench, in which a portion of the wrench has been cut off to show an inner structure of the typical ratchet wrench;  
       FIG. 4  is an enlarged partial top plan and partial cross sectional view of the typical ratchet wrench;  
       FIG. 5  is a perspective view of a ratchet wrench in accordance with the present invention;  
       FIG. 6  is an exploded view of the ratchet wrench;  
       FIG. 7  is a partial cross sectional view taken along lines  7 - 7  of  FIG. 5 ;  
       FIG. 8  is a partial top plan and partial cross sectional view of the ratchet wrench, in which a portion of the wrench has been cut off to show an inner structure of the ratchet wrench; and  
       FIG. 9  is an enlarged partial top plan and partial cross sectional view of the ratchet wrench, illustrating the operation of the ratchet wrench. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring to the drawings, and initially to  FIGS. 5-8 , a ratchet wrench in accordance with the present invention also comprises a handle  10 , a head  11  formed or provided on one end of the handle  10  and including a chamber  12  formed therein for rotatably receiving a follower  40  therein, and including a peripheral bulge  14  extended radially into the chamber  12  of the head  11 .  
      A ring or a washer  20  is secured to the lower portion of the head  11  with such as a retaining ring  15  which may be engaged into an inner peripheral recess  13  of the head  11 , such that the washer  20  may enclose the lower portion of the chamber  12  of the head  11 . The washer  20  includes a bore  21  formed therein. The washer  20  may be engaged with the peripheral bulge  14  of the head  11 , and may thus be solidly secured to the head  11 .  
      The follower  40  includes a driving shank  41  extended therefrom and rotatably received in the bore  21  of the washer  20  and having a peripheral groove  42  formed therein for receiving another retaining ring  23  which may be engaged with the washer  20 , to rotatably secure the follower  40  to the head  11  with the washer  20 . The driving shank  41  of the follower  40  may be used to rotate or drive various tools or fasteners.  
      As shown in  FIGS. 8 and 9 , the follower  40  includes an outer diameter smaller than the inner diameter of the chamber  12  of the head  11 , such that an annular channel  17  may be formed between the follower  40  and the head  11 . The follower  40  includes three or more, such as six recesses  43  formed in six sides  44  thereof, and includes three pairs of depressions  46 ,  47  formed in the upper portion thereof and arranged corresponding to the six sides  44  thereof.  
      A cap  30  rotatably received in the chamber  12  of the head  11 , and engaged with the peripheral bulge  14  of the head  11 , to position the cap  30  relative to the head  11 , and to prevent the cap  30  from being disengaged from the head  11 . The cap  30  includes an aperture  31  formed therein to rotatably receive a shaft  48  that is extended from the follower  40 , and that includes a peripheral groove  49  formed therein to receive another retaining ring  32  which may engage with the cap  30 , to rotatably secure the cap  30  to the follower  40 .  
      The cap  30  includes three or more, such as six actuator fingers  33  extended therefrom, to form three or more, such as six spaces  34  between the actuator fingers  33 , and to receive form three or more, such as six rollers  50  within the spaces  34  of the cap  30 . The actuator fingers  33  and the rollers  50  are received in the annular channel  17  formed between the follower  40  and the head  11 .  
      The cap  30  further includes three cavities  35  formed therein to receive three springs  60  and three balls or projections  70  that may be biased by the springs  60  to engage into either of the depressions  46 ,  47  of the follower  40 , and to position the follower  40  relative to the head  11 . The above-identified structure is typical and thus will not be described in further details.  
      As shown in  FIGS. 8 and 9 , the follower  40  includes the six recesses  43  formed in six sides  44  thereof, to form six pairs of curved actuating surfaces  451  thereon. The six pairs of curved actuating surfaces  451  of the follower  40  are curved toward the inner peripheral surface or the peripheral bulge  14  of the head  11 , and thus has a reduced or smaller included angle “θ” with the peripheral bulge  14  of the head  11 , as compared with the flat actuating surfaces of the typical ratchet wrenches.  
      In operation, as best shown in  FIGS. 8 and 9 , the rollers  50  may be caused to engage with either of the curved actuating surfaces  451  of the follower  40  by rotating the cap  30  relative to the head  11 , and may be solidly engaged between the curved actuating surfaces  451  of the follower  40  and the peripheral bulge  14  of the head  11 , to allow the follower  40  to be solidly or effectively driven by the head  11 , even when the handle  10  is rotated slowly or when the head  11  is rotated slowly relative to the follower  40 .  
      Accordingly, the ratchet wrench in accordance with the present invention includes a solid driving mechanism for solidly driving tools or fasteners.  
      Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only and that numerous changes in the detailed construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.