Patent Publication Number: US-7895922-B2

Title: Ratchet wrench

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to a ratchet wrench, and particularly to a ratchet wrench that contains simplified parts but is effectively in change of rotational direction. 
     DESCRIPTION OF THE PRIOR ART 
     A conventional ratchet wrench, designated at  1 , is illustrated in  FIG. 1  of the attached drawings, and generally comprises a body  11 , a ratchet wheel mounted inside an end of the body  11 , a detent block  13 , and a switching member  14 . The detent block  13  is engageable with the ratchet wheel  12 , and the switching member  14  is in operative coupling with the detent block  13 . An end  121  of the ratchet wheel  12  extends outside the end of the body  11  to rotatably couple to a control knob  16  through a retainer  15 . The control knob  16  is in operative coupling with the switching member  14  for controlling the switching member  14  to rotate the detent block  13  so as to effect direction change of the rotation of the ratchet wrench  1 . 
     The above described construction of the conventional ratchet wrench  1  is effective in realizing direction change, but is comprised of numerous parts, which needs elaborate and complicated handling and machining, making the expense for manufacturing and assembling very high and thus lowering market competitivity. In addition, since the wrench is composed numerous parts, the wrench becomes bulky and heavy, making the use thereof difficult and inconvenient. 
     Further, since the control knob  16  is rotatably coupled to an end  121  of the ratchet wheel  12 , to prevent the control knob  16  from being undesired moved due to the rotation of the ratchet wheel  12 , a sophisticated retention device  17  must be arranged to ensure proper positioning of the control knob  16 , and further, the control knob  16  must be elaborately structured in order to maintain good rotatable coupling with the ratchet wheel  12 . This certainly increases the manufacturing expense. Further, since the working environments for the ratchet wrench may be unorganized and dirty, often leading to dirt or contaminants entering and hiding in the coupling between the control knob  16  and the ratchet wheel  12 . This may deteriorate the coupling engagement between the control knob  16  and the ratchet wheel  12  and leads to improper operation of direction change in the use of the wrench. In addition, the conventional ratchet wrench  1  is not equipped with means for reciprocation of the detent block  13  and teeth formed on the detent block  13  may easily get jammed with teeth of the ratchet wheel  12 , leading to incapability of rotation in reversed direction. 
     In view of the above drawbacks of the conventional ratchet wrench  1 , the present invention aims to provide a ratchet wrench featuring simplification of parts but still maintaining proper operability of change of rotational direction. 
     SUMMARY OF THE INVENTION 
     The primary technical solution of the present invention is to provide a ratchet wrench, which comprises at least a body, a ratchet wheel, a control unit, and a rotary knob. The body has an end forming a ratchet wheel bore and a receiving hole, which respectively and rotatably receive the ratchet wheel and the rotary knob therein. A channel is defined in the body between the ratchet wheel bore and the receiving hole for receiving therein the control unit. The control unit includes two detent blocks and a spring. The detent blocks are biased by the spring to be alternately engageable with teeth formed in the ratchet wheel. The rotary knob retains a control bar and a positioning ball. The receiving hole has an inner circumferential wall in which two positioning notches are defined. The control bar is operated to selectively move the detent blocks to desired positions and the positioning ball is biased by a spring into selective engagement with a corresponding one of the positioning notches for proper positioning of the detent blocks. As such, the detent blocks can be properly positioned and convenience of use can be realized. 
     The secondary technical solution of the present invention is to provide a ratchet wrench, which comprises at least a body, a ratchet wheel, a control unit, and a rotary knob. The body has an end forming a ratchet wheel bore and a receiving hole, which respectively and rotatably receive the ratchet wheel and the rotary knob therein. The rotary knob forms rough knurled pattern by which an increased frictional force is provided for a user&#39;s operation of rotation and thus convenience of rotation of the rotary knob is realized. 
     The foregoing objective and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
     Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of a conventional ratchet wrench. 
         FIG. 2  is a perspective view of a ratchet wrench in accordance with the present invention. 
         FIG. 3  is an exploded view of the ratchet wrench in accordance with the present invention. 
         FIG. 4  is a cross-sectional view of the ratchet wrench in accordance with the present invention. 
         FIGS. 5 and 6  schematically illustrate direction change operation of the ratchet wrench in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
     The present invention will now be explained with reference to the drawings. 
     Initial reference is made to  FIGS. 2 and 3 . The present invention provides a ratchet wrench  2 , which comprises at least a body  21 , a ratchet wheel  22 , a control unit  23 , and a rotary knob  24 . 
     The body  21  has an end  211  forming a ratchet wheel bore  212  and a receiving hole  213 , both extending therethrough. Bottom parts of the ratchet wheel bore  212  and the receiving hole  213  each form an expanded opening  2121 ,  2131 . A channel  214  is defined in the body  21  between the ratchet wheel bore  212  and the receiving hole  213 . The receiving hole  213  has a circunmferential inner wall forming two positioning notches  2132 . 
     The ratchet wheel  22  is received in the ratchet wheel bore  212  of the body  21 . The ratchet wheel  22  has an upper portion forming circumferentially teeth  221  and a lower portion forming a working end  222 . The working end  222  comprises a steel ball  223  movably embedded therein. The ratchet wheel  22  forms, in a central portion thereof, a through hole  224  in which a push button  225  and a spring  226  are received. The ratchet wheel  22  is provided with a positioner ring  227  at the lower portion thereof and the positioner ring  227  is tightly fit into the expanded opening  2121  of the body  21  to position and retain the ratchet wheel  22  in the ratchet wheel bore  212 . 
     The control unit  23  comprises two detent blocks  231 ,  232  and a spring  233 . Each detent block  231 ,  232  forms at one end thereof a toothed face  2311 ,  2321  engageable with the teeth  221  of the ratchet wheel  22 . Each detent block  231 , 232  forms a peg  2312 ,  2322  at an opposite end thereof. A receiving space  2313 ,  2323  is formed between the toothed face  2311 ,  2321  and the peg  2312 ,  2322  of each detent block  231 , 232 . The detent blocks  231 ,  232  are structured and arranged to mutually fit to and mate each other and the spring  233  is received in the receiving spaces  2313 ,  2323  and is thus set between the two detent blocks  231 ,  232 . The spring  233  comprises a corrugated plate formed in a fan shape. The spring  233  provides an outward-directing resiliency due to the corrugated configuration thereof in order to maintain an outward expanded condition of the detent blocks  231 ,  232 . Further, the spring  233  comprises a flat section  2331  at a middle portion thereof and the flat section  2331  corresponds in position to the channel  214  formed in the end  211  of the body  21 . 
     The rotary knob  24  has an upper portion forming an expanded, diameter-increased head  241  having a circumferential surface that forms knurling  2411 . A stem  242  extends downward below the head  241 . The stem  242  forms two deep holes  2421 ,  2422 . The deep hole  2421  receives therein a control bar  243 , which is of such a length that is partially exposed outside the stem  242  after being fully inserted into the hole  2421 . The hole  2422  receives therein a spring  244  and a positioning ball  245 , which corresponds in position to the positioning notches  2132  of the body  21 . The rotary knob  24  is provided with a positioner ring  246  at a lower portion thereof and the positioner ring  246  is tightly fit into the expanded opening  2131  of the body  21  in order to position and retain the rotary knob  24  in the receiving hole  213  of the body  21 . 
     Referring to  FIG. 4 , to practice the present invention, the spring  244  and the positioning ball  245  of the rotary knob  24  are positioned into the deep hole  2422  of the stem  242 . The stem  242  of the rotary knob  24  is then fit into the receiving hole  213  of the body  21 . The control bar  243  is moved through the channel  214  to fit into the deep hole  2421  of the stem  242  of the rotary knob  24 . Thereafter, the positioner ring  246  is tightly fit into the expanded opening  2131  of the receiving hole  213 . Afterwards, the two detent blocks  231 ,  232  of the control unit  23  are fit to each other in a vertical direction and the spring  233  is set in the receiving spaces  2313 ,  2323  of the detent blocks  231 ,  232 , which are then all put into the channel  214  of the body  21 , whereby the control bar  243  is located between the pegs  2311  of the two detent blocks  231  and the flat section  2331  of the spring  233 . The flat section  2331  of the spring  233  provides a space for accommodation of the control bar  243  in order to prevent interference between the control bar  243  and the corrugation of the spring  233 . Finally, the push button  225  and the spring  226  are put into the through hole  224  of the ratchet wheel  22  and the ratchet wheel  22  is put into and retained in the ratchet wheel bore  212  of the body  21  by tightly fitting the positioner ring  227  into the expanded opening  2121  of the ratchet wheel bore  212 . This completes the assembling of the ratchet wrench. 
     Referring to  FIG. 5 , to operate the present invention, the head  241  of the rotary knob  24  is rotated to make the control bar  243  driving the peg  2312  of the detent block  231  for inducing movement of the detent block  231 , so that the toothed face  2311  is caused to disengage from the teeth  221  of the ratchet wheel  22 . In addition, the spring  233  also applies a force to the other detent block  232  to make the toothed face  2321  of the detent block  232  engaging the teeth  221  of the ratchet wheel  22 . The control bar  243  of the rotary knob  24  is properly set in position by the spring  244  biasing the positioning ball  245  into engagement with the corresponding positioning notch  2132 , which also makes the rotary knob  24  properly set in position. Under this condition, the body  21  of the ratchet wrench  2  can make rotation in a first direction, such as clockwise direction. 
     On the other hand, as shown in  FIG. 6 , to change the direction of rotation of the ratchet wheel  22 , the rotary knob  24  is rotated to the opposite direction, making the control bar  243  driving the peg  2322  of the detent block  232  for inducing movement of the detent block  232 , so that the toothed face  2321  disengages from the teeth  221  of the ratchet wheel  22 . The spring  233  also applies a force, in an opposite manner, to the detent block  231  to make the toothed face  2311  of the detent block  231  engaging the teeth  221  of the ratchet wheel  22 . The control bar  243  of the rotary knob  24  is properly set in position by the spring  244  biasing the positioning ball  245  into engagement with the corresponding positioning notch  2132 , which also makes the rotary knob  24  properly set in position. Under this condition, the body  21  of the ratchet wrench  2  can make rotation in an opposite second direction, such as counterclockwise direction. 
     The effectiveness of the present invention is that by providing a channel  214  between the ratchet wheel bore  212  and the receiving hole  213  for completely accommodating therein the control unit  23 , contaminants and other dirt are prevented from entering and being hiding in the control unit  23  to resist the operation of the detent blocks  231 ,  232  and the ratchet wheel  22 . Further, by providing the control bar  243  and the positioning ball  245  in the rotary knob  24  and forming two positioning notches  2132  in an inner circumferential wall of the receiving hole  213 , after the detent blocks  231 ,  232  are moved by the control bar  243 , the detent blocks  231 ,  232  can be properly set in position by the spring  244  biasing the positioning ball  245  into engagement with the corresponding positioning notch  2132 , so as to realize convenience of operation and use. Further, the head  241  of the rotary knob  24  is provided on the circumferential surface thereof, with knurling  2411 , which provides an effective frictional force when being rotated by a user so as to realize easy rotation of the rotary knob  24 . 
     While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.