Patent Publication Number: US-2003230173-A1

Title: Wrench for selectively driving in one of two opposite directions

Description:
BACKGROUND OF INVENTION  
       [0001] 1. Field of Invention  
       [0002] The present invention is related to a wrench for selectively driving in one of two opposite directions.  
       [0003] 2. Related Prior Art  
       [0004] Taiwanese Patent Publication No. 370170 discloses a one-way rotational device with a core  1 , a spring  2 , a plurality of engagement elements  3  and a drum  4 . The core  1  includes a cylindrical periphery on and about which an annular ridge  12  is formed, thus dividing the cylindrical periphery to two sections  11 . Each of the engagement elements  3  includes two cams  31  and a shaft  32  formed between the cams  31  and a tunnel  33  transversely extending through the shaft  32 . The spring  2  is inserted in the tunnels  33 . The shafts  32  are mounted on the annular ridge  12 . The contact of the shafts  32  with the annular ridge  12  is retained by means of the spring  2 . The core  1  and the engagement elements  3  are received in the drum  4  so that the cams  31  are in slight contact with drum  4 . When the core  1  is rotated relative to the drum  4  in a first direction, the engagement elements  3  are rotated relative to the core  1  and the drum  4  by a small angle so that the contact between the cams  31  and the drum  4  becomes slighter. Thus, continuous rotation of the core  1  relative to the drum  4  in the first direction is allowed. When the core  1  is rotated relative to the drum  4  in a second direction opposite to the first direction, the engagement elements  3  are rotated relative to the core  1  and the drum  4  by a relatively large angle so that the contact between the cams  31  and the drum  4  becomes substantial. Thus, continuous rotation of the core  1  relative to the drum  4  in second direction is prohibited. Some problems have been encountered in making and use of this prior art one-way rotational device. Firstly, manufacturing of the engagement elements  3  is difficult and therefore entails a high cost. Secondly, assembling of the elements is complicated and therefore entails a high cost. Thirdly, the spring  2  that is made for extension instead of buckling can be damaged easily since it is buckled whenever rotation of the core  1  relative to the drum  4  in the second direction is attempted.  
       [0005] The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.  
       SUMMARY OF INVENTION  
       [0006] It is the primary objective of the present invention to provide a wrench that can be switched between a first mode for enhancing engagement of a bolt with a nut and a second mode for disengaging the bolt from the nut.  
       [0007] According to the present invention, a wrench includes a hollow head, a ring received in the hollow head for rotation, first and second brake shoes received in the hollow head for pivoting and a direction controller received in the hollow head between the brake shoes and pivoted between first and second positions. In the first position, the first brake shoe contacts the ring. When rotation of the hollow head relative to the ring in a first direction is attempted, pivoting of the first brake shoe is allowed, thus allowing rotation of the hollow head relative to the ring. When rotation of the hollow head relative to the ring in a second direction is attempted, the direction controller hinders pivoting of the first brake shoe so as to avoid rotation of the hollow head relative to the ring. In the second position, the second brake shoe contacts the ring. When rotation of the hollow head relative to the ring in the second direction is attempted, pivoting of the second brake shoe is allowed, thus allowing rotation of the hollow head relative to the ring. When rotation of the hollow head relative to the ring in the first direction is attempted, the direction controller hinders pivoting of the second brake shoe so as to avoid rotation of the hollow head relative to the ring.  
       [0008] Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the attached drawings. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
     [0009] The present invention will be described through detailed illustration of embodiments referring to the attached drawings wherein:  
     [0010]FIG. 1 is a perspective view of a wrench according to a first embodiment of the present invention;  
     [0011]FIG. 2 is an exploded view of the wrench shown in FIG. 1;  
     [0012]FIG. 3 is a cross-sectional view taken along a line  3 - 3  in FIG. 1 showing the wrench including a handle, an annular head and a ring;  
     [0013]FIG. 4 is a cross-sectional view taken along a line  4 - 4  in FIG. 1 showing the annular head allowed to rotate relative to the ring in a direction;  
     [0014]FIG. 5 is similar to FIG. 4 except for showing the ring in another position;  
     [0015]FIG. 6 is similar to FIG. 4 except for showing the annular head allowed to rotate relative to the ring in an opposite direction;  
     [0016]FIG. 7 is similar to FIG. 6 except for showing the ring in another position;  
     [0017]FIG. 8 is a perspective view of a wrench according to a second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
     [0018] Referring to FIGS. 1 and 2, according to a first embodiment of the present invention, a wrench  10  includes a head  11 . The head  11  includes a lower plate  13  formed thereon, an upper plate  16  formed thereon and a space  12  defined therein between the lower plate  13  and the upper plate  16 . The lower plate  13  defines a circular opening. A positioning aperture  131  and two locking apertures  132  are defined in the lower plate  13 . The upper plate  16  defines an opening including a first portion and a second portion with a diameter less than that of the first portion. The upper plate  16  defines a cutout  15  in communication with the second portion of the opening defined therein. Two apertures  161  are defined in the upper plate  16 . The space  12  includes a first portion and a second portion with a diameter less than that of the first portion. The first portion of the opening defined in the lower plate  13  is smaller than the first portion of the space  12 . The second portion of the opening defined in the upper plate  16  is smaller than the second portion of the space  12 .  
     [0019] A ring  20  is shaped like a pulley, i.e., it includes an external face  21  between two end plates (not numbered) and two rims  22  each formed on one of the end plates thereof. The ring  20  includes a toothed internal face  23  for engagement with a nut or a head of a bolt. The ring  20  is received in the first portion of the space  12 . One of the rims  22  is received in the opening defined in the lower plate  13 . Thus, the ring  20  is allowed to rotate relative to the head  11 .  
     [0020] The wrench  10  includes two brake shoes  30 . Each of the brake shoes  30  includes an end  33  for contact with the external face of the ring  20 , a bottom on which a boss  31  is formed, a first side on which a boss  32  is formed and a second side for contact with a direction controller  40  to be described. The brake shoes  30  are received in the second portion of the space  12 . The boss  31  of each of the brake shoes  30  is received in one of the positioning apertures  132 , thus allowing the brake shoes  30  to pivot relative to the lower plate  13 .  
     [0021] The wrench  11  includes two bent leaf springs  34  each including a first section and a second section defining an aperture  341 . The boss  32  of each of the brake shoes  30  is received in the aperture  341  defined in one of the bent leaf springs  34 . The bent leaf springs  34  are also received in the second portion of the space  12 . Each of the bent leaf springs  34  is compressed between one of the brake shoes  30  and an internal face of the ring  20 .  
     [0022] The direction controller  40  includes a top in which a non-circular recess  41  is defined, two sides and an end in which two recesses  42  are defined. The direction controller  40  is received in the second portion of the space  12  between the brake shoes  30 .  
     [0023] A direction retainer  50  includes a ball  51  and a spring  52 . The spring  52  is received in the cutout  15 . A ball  51  is partially received in the cutout  15  against the spring  52 , and is partially received one of the recesses  42  defined in the direction controller  40 .  
     [0024] A cover  60  defines an opening identical to the opening defined in the lower plate  13 , two apertures  61  and an aperture  62 . The cover  60  is mounted on the head  11  so that the remaining one of the rims  22  is received in the aperture  62 . Two bolts  63  are inserted through the apertures  61  and then driven into the apertures  161 , thus securing the cover  60  to the head  11 .  
     [0025] Referring to FIGS. 2 and 3, a switch  70  includes a lever  71  and a rod  72  projecting from the lever  71 . The rod  72  is inserted through the aperture  62  into the recess  41  defined in the direction controller  40 . Thus, the lever  71  can be operated in order to pivot the direction controller  40 .  
     [0026] FIGS.  4 ˜ 7  show how the wrench can be operated. Although not shown in these figures, it should be borne in mind that the ring  20  is engaged with a nut or a head of a bolt in operation.  
     [0027] Referring to FIG. 4, the lever  71  is operated so as to pivot the direction controller  40  clockwise. The direction controller  40  causes the brake shoes  30  to pivot clockwise so that the end  33  of the brake shoe  30  on the left contacts the external face of the ring  21 . The ball  51  biased by the spring  52  is partially received in the recess  42  on the right in order to retain the direction controller  40 . When counterclockwise rotation of the head  11  relative to the ring  20  is attempted, counterclockwise pivoting of the brake shoe  30  on the left is allowed due to the spring  34  on the left. Thus, friction between the end  33  of the brake shoe  30  on the left and the external face  22  of the ring  20  is reduced, and the end  33  of the brake shoe  30  on the left is allowed to slide on the external face  22  of the ring  20 . Therefore, the head  11  is allowed to rotate relative to the ring  20  counterclockwise.  
     [0028] Referring to FIG. 5, when clockwise rotation of the head  11  relative to the ring  20  is attempted, the brake shoe  30  on the left is pressed against the direction controller  40 . Thus, the friction between the end  33  of the brake shoe  30  and the external face  22  of the ring  20  is increased, and the end  33  of the brake shoe  30  on the left is not allowed to slide on the external face  22  of the ring  20 . Therefore, the head  11  is not allowed to rotate relative to the ring  20  clockwise. That is, the ring  20  is rotated together with the head  11 .  
     [0029] Referring to FIG. 6, the lever  71  is operated so as to pivot the direction controller  40  counterclockwise. The direction controller  40  causes the brake shoes  30  to pivot counterclockwise so that the end  33  of the brake shoe  30  on the right contacts the external face of the ring  21 . The ball  51  biased by the spring  52  is partially received in the recess  42  on the left in order to retain the direction controller  40 . When clockwise rotation of the head  11  relative to the ring  20  is attempted, clockwise pivoting of the brake shoe  30  on the right is allowed due to the spring on the right. Thus, friction between the end  33  of the brake shoe  30  on the right and the external face  22  of the ring  20  is reduced, and the end  33  of the brake shoe  30  on the right is allowed to slide on the external face  22  of the ring  20 . Therefore, the head  11  is allowed to rotate relative to the ring  20  clockwise.  
     [0030] Referring to FIG. 7, when counterclockwise rotation of the head  11  relative to the ring  20  is attempted, the brake shoe  30  on the right is pressed against the direction controller  40 . Thus, the friction between the end  33  of the brake shoe  30  on the right and the external face  22  of the ring  20  is not reduced. Thus, the end  33  of the brake shoe  30  on the left is not allowed to slide on the external face  22  of the ring  20 . Therefore, the head  11  is not allowed to rotate relative to the ring  20  clockwise. That is, the ring  20  is rotated together with the head  11 .  
     [0031]FIG. 8 shows a second embodiment of the present invention identical to the first embodiment except for some features. Firstly, the second embodiment does not include an upper plate  16 . Secondly, the second embodiment includes a block  17  defining a recess  172  for receiving the spring  52  and a part of the ball  50 . Thirdly, the head  11  defines a space  12 ′ including a larger second portion for receiving the block  17 . Fourthly, the leaf springs  34  are replaced with two helical springs  34 ′.  
     [0032] The resent invention has been described through detailed illustration of the preferred embodiment. Those skilled in the art can derive many variations from the preferred embodiment without departing from the scope of the present invention. Therefore, the preferred embodiment shall not limit the scope of the present invention. The scope of the present invention is defined in the attached claims.