Patent Publication Number: US-2012036968-A1

Title: Ratchet wrench with reversible mechanism

Description:
This application is a Continuation-in-Part of U.S. application Ser. No. 12/853,298, entitled “RATCHET WRENCH WITH REVERSIBLE MECHANISM”, naming Hong-Jen Lee as inventor, and filed on Aug. 10, 2010. 
    
    
     FIELD OF THE INVENTION 
     Background of the Invention 
     For a conventional ratchet wrench structure, such as U.S. Pat. No. 4,497,227, the lateral side of the driving head holds one or two pawls. The retaining teeth of the pawl engage with the ratchet teeth on the inner wall of the head portion of the main body, and an upper lid is disposed on the head portion, and connected with a spring. One end of the spring connects the pawl. The rotation of the upper lid controls the spring to rotate. Then, the spring pushes the pawl to swing and engage with the ratchet teeth of the head portion by retaining teeth on left side or right side, and further control the driving head having the ability of clockwise or counterclockwise drive. 
     However, the disadvantages of the above-mentioned US patent are as followings: 
     1. Controlling the ratchet wrench to make clockwise or counterclockwise turn relies on the upper lid to push the spring which makes the pawl to swing. During operation, the spring must bear a bigger reaction. It is easy to get elastic fatigue, and the retaining teeth of the pawl cannot properly engage with the ratchet teeth. 
     2. It is necessary to machine the upper lid to get a receiving chamber to hold the spring. However, the upper lid is not a circle. It requires milling. However, milling will increases the machining time and the cost of fabrication. 
     3. The actuation principle of the ratchet wrench requires a certain length of spring to fit an elastic action being produced when the retaining teeth of the pawl and the wretch gear are not relatively in mesh. The upper lid needs to receive a spring, and has a bigger diameter. Thus, the head portion of the wrench also needs a matching diameter. Therefore, one size of the upper lid and the pawl cannot fit different sizes of the wrench. 
     4. For assembling, if the two springs are firstly assembled with the pawl, and then the upper lid is assembled, it is not easy to align the two springs because the receiving chamber faces downward. It causes an assembling inconvenience. 
     There is another ratchet wrench disclosed in U.S. Pat. No. 6,769,330, whose operational end of the main body holds one driving head. The two lateral sides of the driving head hold two pawls. The retaining teeth of the pawl engage with the ratchet teeth on the inner wall of the main body. The two pawls are connected and positioned by two elastic elements. The advantage of the patent is that the elastic elements are wound around the periphery of the driving head. Thus, the elastic elements avoid the disadvantage that the spring mentioned in U.S. Pat. No. 4,497,127 occupies the space. However, the disadvantage of the aforementioned patent is: the elastic element is in form of wire, one end of the elastic element is disposed on the driving head and the other end is connected to the pawl, so that the ratchet wench is unable to make a clockwise or counterclockwise driving. In other words, the pawl cannot swing except one directional rotation. If the user wants to get another direction of rotation, he has to turn over the ratchet wrench to another side for use. Thus, the ratchet wrench of U.S. Pat. No. 6,769,330 is inconvenient in use. 
     Another prior art of a ratchet wrench disclosed in Taiwan Patent Application No. 096219094, the ratchet wrench is a hand tool that adopts a ratchet wheel as a driving device. On one side of the hand tool is an adjustable operation unit to be operated in accordance with its component-assembly, and on the other side is a driving unit which has a housing with ratchet teeth on its inner wall. There is a rotatable member located within the housing with a couple opening. The outer periphery of the rotatable member has a plurality of movable tangent planes equally arranged to be lain by limit members. At the outer portion of each limit member are retaining cogs relatively engaged with the ratchet teeth, and at the inner portion is a surface resting against a tangent plane of the rotatable member. There are two linkages extended from the top and the bottom of the limit member to link with both sides of the tangent plane respectively. Two annular cover pieces are applied on both sides of the housing to conceal the limit members and the rotatable member. Although the prior art has three sets of retaining cogs and, therefore, has stable rotary ability than the ratchet wrench with two sets of retaining cogs. Inasmuch as its linkage links the rotatable member at one side and the retaining cogs at the other side, it can only drive the cogs to move in single direction. If it requires to operate in the reverse direction, the wrench needs to be turned upside down. The disadvantage of the prior art is that it is inconvenient for users to operate the hand tool with single direction driving. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a ratchet wrench comprising three pawls, which are interacted for controlling its reversing mechanism, in order to evenly distribute the force exerted over the wrench. Generally described, a ratchet mechanism according to the present invention includes a main body, a driving head, three pawls, a knurled rotatable disc and a locking ring. The middle part of the driving head is a disc which has a polygonal columned couple portion extended from the bottom of the disc for a workpiece to be coupled and a columned limit portion extended from the top center of the disc. The periphery of the limit portion has three tangent planes with equal central angles. Each tangent plane and the top of the disc forms a recess cut, and each pawl is respectively located within a recess cut. When the knurled rotatable disc is turned against an annular head portion, it drives the pawls to be engaged with ratchet teeth. The limit portion has a cylinder penetrating the knurled rotatable disc to link with the locking ring. The limit portion is mounted by a mounting piece and the mounting piece has three first sliding slots and three rails bored on its top. Each pawl is guided by a relative rail and its top extends a rod upwards. Each rod is hooked by an elastic element which provides elasticity for the rod to move in radial direction. Therefore, the knurled rotatable disc is able to interact with the rod and to be turned against the limit portion. When the knurled rotatable disc is turned clockwise or counterclockwise, one side of each pawl or its retaining cogs on the other side are able to be engaged with the ratchet teeth by means of interaction between the rod and the pawl for the pawl to move laterally, clockwise or counterclockwise, along its relative rail and tangent plane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the present invention; 
         FIG. 2  is a partial assembled view of the present invention; 
         FIG. 3  is a partial assembled schematic view of the present invention; 
         FIG. 4  is a top view of the present invention; 
         FIG. 5  is a cross-sectional view taken along lines A-A of  FIG. 4 ; 
         FIG. 6  is a side view of the present invention; 
         FIG. 7  is a cross-sectional view taken along lines B-B of  FIG. 6  showing pawls at one side; 
         FIG. 8  is a cross-sectional view taken along lines C-C of  FIG. 6  showing the rotatable disc turning to a certain angle; 
         FIG. 9  is a cross-sectional view taken along lines B-B of  FIG. 6  showing pawls at the other side; and 
         FIG. 10  is a cross-sectional view taken along lines C-C of  FIG. 6  showing the rotatable disc turning to another angle. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1  to  FIG. 10 , in order to achieve the objects mentioned above, the basic structure of the ratchet wrench includes a main body  10 , a driving head  20 , three pawls  40 , a knurled rotatable disc  60  and a locking ring  70 . There is an annular head portion  11  vertically inserted in a circular housing  15 , whose inner wall has a plurality of ratchet teeth  12 , at one end of the main body  10 . The driving head  20  is rotatably located within the circular housing  15 , and its middle portion is a disc  21  which shares the same axis with the circular housing  15 . The periphery of the disc  21  is engaged with the bottom of the circular housing  15 . There is a polygonal columned couple portion  22  extended downwards from the center bottom of the disc  21  for a workpiece to be coupled, and there is also a columned limit portion  23  extended upwards from the top center of the disc  21 . The periphery of the limit portion  23  has three tangent planes  24  with equal central angles against the center axis of the limit portion  23 . Each tangent plane  24  and the top of the disc  21  form a recess cut  25 , and each pawl  40  is respectively located within a recess cut  25 . The knurled rotatable disc  60  is rotatably topped on the circular housing  15 . When the knurled rotatable disc  60  is turned against the annular head portion  11 , it drives the pawls  40  to be engaged with ratchet teeth  12 . The top center of the limit portion  23  is an extruded cylinder  26  whose outer periphery has an annular groove  260  and an outer screw-thread section  261  to couple with a C-clip  54  and the inner screw-thread section  71  of the locking ring  70  respectively. The cylinder  26  and the disc  21  share the same axis. The extruded cylinder  26  penetrates through a cylinder duct  55  in the center of the rotatable disc  50 , and its annular groove  260  is snapped by a C-clip  54  at the top of the rotatable disc  50  to limit the cylinder  26 . Furthermore, the end portion of the cylinder  26  penetrates the knurled rotatable disc  60  through the first linkage duct  61 , and the screw-thread section  261  is screwed by the locking ring  70  at the top of the knurled rotatable disc  60  to limit the cylinder  26 . 
     Features of the basic structure are: the limit portion  23  being mounted by a mounting piece  30  which also covers the top of the recess cut  25 , three first sliding slots  32  and three rails  33  being arranged with equal central angles against the center axis of the mounting piece  30 , each first sliding slot  32  being extended relative to a rail  33  in parallel and the direction to extend the rail  33  being in parallel with a tangent to the disc; each pawl  40  being guided by a relative rail  33  and having a front plane  43  and a back plane  44  opposite to each other, the front plane  43  having retaining cogs  41  on its two vertical sides and the back plane  44  being lain back against the tangent plane  24 , each pawl  40  also extending a rod  45  upwards on its top, the middle portion of the rod  45  penetrating a relative first sliding slot  32  and its top portion linking to one end of an elastic element  53  which provides elasticity for the rod  45  to move in radial direction, therefore, the knurled rotatable disc  60  being able to interact with the rod  45  and to be turned against the limit portion  23 ; shown as  FIG. 7  and  FIG. 8 , when the knurled rotatable disc  60  being turned clockwise to interact with the rod  45 , the rod  45  triggering the pawl  40  to laterally move clockwise as well along the rail  33  and the tangent plane  24 , and furthermore, the retaining cogs  41  on one side of the pawl  40  being engaged with the ratchet teeth  12 ; shown as  FIG. 9  and  FIG. 10 , when the knurled rotatable disc  60  being turned counterclockwise, the pawl  40  laterally move counterclockwise as well along the rail  33  and the tangent plane  24  to the opposite direction and its retaining cogs  41  on the other side being engaged with the ratchet teeth  12  then. 
     Referring to  FIG. 1 , in one embodiment of the present invention, there is a rotatable disc  50  located on the top of the mounting piece  30  which mounted over the limit portion  23 . The rotatable disc  50  and the mounting piece  30  share the same axis, and there are three second sliding slots  51  arranged with equal central angles against the center axis on the rotatable disc  50 . The second sliding slot  51  is extended along the radial direction of the center axis of the rotatable disc  50 , and each second sliding slot  51  is corresponding to one first sliding slot  32 . The top portion of the rod  45  penetrates through one side of one relative second sliding slot  51  and hooks onto one end of the elastic element  53 , and the other end of the elastic element  53  is against the inner wall of the other end of the second sliding slot  51 . Wherein, on the rotatable disc  50  is at least one round trough  52 , and on the bottom of the knurled rotatable disc  60  is at least one protrusion  63  which is inserted into the round trough  52  for the rotatable disc  50  and the knurled rotatable disc  60  to interlink together. Furthermore, at one end of the elastic element  53  is a loop  530  which is employed to snap in a groove  46  at the top portion of the rod  45 . 
     Referring to  FIG. 1  and  FIG. 2 , in one of the embodiments of the present invention, the mounting piece  30  includes a mounting opening  31  at its center and three edge slabs  34  arranged with equal central angles against the center axis. The mounting opening  31  is mounted over the limit portion  23  to be fixed in position. Each first sliding slot  32  is allocated corresponding to an edge slab  34  and each rail  33  is extended downwards from the edge slab  34 . Therefore, each recess cut  25  is embraced by the edge slab  34 , the disc  21 , the rail  33  and the tangent plane  24  as its top, bottom, front plane and back plane respectively. Meanwhile, two gaps  250 / 251  are formed at both vertical sides of the recess cut  25 . The front plane  43  of each pawl  40  is lain against the rail  33 . When the pawl  40  moves right side against the limit portion  23 , the retaining cogs  41  reaches out of the gap  250  from the recess cut  25  to engage with the ratchet teeth  12 . And when the pawl  40  moves left side against the limit portion  23 , the retaining cogs  41  reaches out of the other gap  251  from the recess cut  25  to engage with the ratchet teeth  12 . Wherein, four sides of each first sliding slot  32  are self-contained to form a long slot, and the bottom of each rail  33  rests on the top of the disc  21 . 
     Referring to  FIG. 1  and  FIG. 5 , there is a better embodiment of the present invention. A hollow duct  27  is bored downwards from the top center of the cylinder  26  and the limit portion  23 , and a spheroid hole  221  is bored on the periphery of the couple portion  22  to communicate with the hollow duct  27 . A control shaft  81  is vertically inserted through the hollow duct  27 , and its outer periphery at the bottom portion has a spheroid trough  811  corresponding to the spheroid hole  221  in the couple portion  22 . 
     The inner wall of the spheroid trough  811  is ladder-like. At the top portion of the control shaft  81  is a screw-thread section  812 . Inasmuch as the control shaft  81  protrudes from the top of the hollow duct  27 , the screw-thread section  812  exposes above the locking ring  70  and couples with the thread-couple element  82 . There is a spring  83  applied between the thread-couple element  82  and the locking ring  70 , and there is a spheroid  84  allocated between the spheroid hole  221  and the spheroid trough  811 . 
     Referring to  FIG. 1  and  FIG. 7 , in a better embodiment of the present invention, the limit portion  23  is designed as a triangular column with three tangent planes  24  in order to economize material cost and manufacture with convenience. 
     Referring to  FIG. 1  and  FIG. 2 , in a better embodiment of the present invention, there are one first annular trough  14  and one second annular trough  13 , which are extended outwards with diameters larger than the housing, on the top and the bottom of the circular housing  15  respectively. The first annular trough  14  allows the knurled rotatable disc  60  to be mounted and the second annular trough  13  provides a recess for the disc  21 . 
     Referring to  FIG. 1 , in a preferable embodiment of the present invention, the top of the locking ring  70  is provided a transverse groove  72  thereon, the groove  72  is provided for the drill of a screwdriver to engage and drive. 
     While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.