Patent Publication Number: US-2007119281-A1

Title: One-way open-ended wrench

Description:
BACKGROUND OF INVENTION  
      1. Field of Invention  
      The present invention relates to a one-way open-ended wrench and, more particularly, to a one-way open-ended wrench that is made with a simple structure, operable conveniently, and assembled from inexpensive parts in an inexpensive process.  
      2. Related Prior Art  
      Typically, a nut or a head of a bolt is tightened or loosened by means of a wrench such as a ratchet wrench (or “selective one-way wrench”), a socket wrench, an adjustable wrench (or “coach wrench” or “monkey wrench”), a box-ended wrench and an open-ended wrench. The tightening and loosening are conducted through rotation. Where an entire revolution is impossible, a wrench must be disengaged from the nut or the head of the bolt after driving for an angle, returned, and engaged with the nut or the head of the bolt again so that the wrench can drive the nut or the head of the bolt for another angle. Thus, the tightening and loosening can be conducted to a desired extent. This procedure is however inconvenient. This is where the ratchet wrenches are introduced. Sometimes, a limited room renders it impossible to disengage a wrench from the nut or the head of the bolt axially. In such a limited room, only an open-ended wrench can be used. A conventional open-ended wrench is thin, and cannot include a ratchet mechanism (or “one-way mechanism”).  
      To solve the fore-going problem, there are devised open-ended wrenches equipped with ratchet mechanisms such as shown in  FIG. 6  (corresponding to Taiwanese Patent Publication M262313, “Open-Ended Wrench with Ratchet Functions”). The open-ended wrench includes a handle  50  and a head  51  formed at an end of the handle  50 . The head  51  includes first and second jaws  52  between which is a space. The first jaw  52  defines a hole and a tunnel. A spring  55  and a movable jaw  54  are positioned in the hole. The spring  55  is compressed between the bottom of the hole and the movable jaw  54 . The movable jaw  54  defines a groove  540 . A guiding rod  56  is positioned in the tunnel. An end of the guiding rod  56  is positioned in the groove  540 . A spring  57  is positioned in the tunnel. An opposite end of the guiding rod  56  is in contact with the spring  55 . The thread of a bolt is engaged with a thread formed on the wall of the tunnel. Thus, the spring  57  is compressed between the guiding rod  56  and the bolt. When the open-ended wrench is driven in a direction, the movable jaw  54 , restrained by means of the guiding rod  56 , cooperates with the second jaw  52  in order to clamp and drive a nut or a head of a bolt. When the open-ended wrench is driven in an opposite direction, the movable jaw  54 , not restrained by means of the guiding rod  56 , is pushed into the hole by means of the nut or the head of the bolt, thus leaving the nut or the head of the bolt where it is.  
      There are two problems with this open-ended wrench with ratchet functions. Firstly, it is made with a complicated structure from a lot of parts. The parts cannot be made easily. The open-ended wrench cannot be assembled from the parts easily. Therefore, the open-ended wrench is expensive. Secondly, the stroke of the movable jaw  54  must be limited by means of the guiding rod  56 . Hence, the movable jaw  54  must be positioned to the upper portion of the first jaw  52 , and the free end of the movable jaw  54  comes into contact with a portion upstream to the center of a facet of the nut or the head of the bolt. The nut or the head of the bolt may not receive an adequate torque from the movable jaw  54 . Moreover, the movable jaw  54  may be damaged so that its lifecycle is reduced.  
      As mentioned above, because of poor designs, existing open-ended wrenches with ratchet functions include complicated structures, involve high costs, transfer inadequate torques and last for short lifecycles.  
      The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.  
     SUMMARY OF INVENTION  
      The primary objective of the present invention is to provide a structurally simple one-way open-ended wrench in order to reduce the cost in manufacturing and assembling, thus improving its economic effectiveness.  
      According to the present invention, a one-way open-ended wrench includes a handle and a head. The head includes a first fixed jaw and a second fixed jaw. The first fixed jaw can contact a selective facet of a fastener. The second fixed jaw includes a tunnel and a stop on the wall of the tunnel. A movable jaw is movable in the tunnel. The movable jaw includes a normal abutment facet, a sliding facet near the normal abutment facet and a slant abutment facet near the sliding facet. The normal abutment facet can abut the stop. The sliding facet can slide on the opposite facet of the fastener so that movable jaw can be pushed into the tunnel by means of the fastener. The slant abutment facet can abut the opposite facet of the fastener so that the movable jaw and the first fixed jaw can clamp the fastener. In the tunnel is a spring for biasing the movable jaw.  
      Other objectives, advantages and novel features of the present invention will become more apparent from the following detailed description referring to the attached drawings.  
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
      The present invention will be described through illustration of the preferred embodiment referring to the drawings.  
       FIG. 1  is a perspective view of a one-way open-ended wrench according to the preferred embodiment of the present invention.  
       FIG. 2  is an exploded view of the one-way open-ended wrench shown in  FIG. 1 .  
       FIG. 3  is a cutaway view of the one-way open-ended wrench shown in  FIG. 1 .  
       FIG. 4  is an enlarged partial view of the one-way open-ended wrench shown in  FIG. 3  while driving a head of a bolt in a direction.  
       FIG. 5  is a view of the one-way open-ended wrench rotated in a direction opposite to that is shown in  FIG. 4 .  
       FIG. 6  is a cutaway partial view of a conventional one-way open-ended wrench. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT  
      Referring to  FIG. 1 , there is shown a one-way open-ended wrench including a handle  10  and at least one head  11  formed at one of two ends of the handle  10 . The head  11  includes a first fixed jaw  12  and a second fixed jaw  13 . There is a space  14  defined between the first fixed jaw  12  and the second fixed jaw  13 .  
      Referring to  FIGS. 1 through 4 , the first fixed jaw  12  includes a flat surface  120  for contact with a selective facet  21  of a nut or a head of a bolt  20 . The second fixed jaw  13  includes a concave surface  130  for allowing the rotation of the nut or the head of the bolt  20  in the space  14 . The second fixed jaw  13  defines a tunnel  15  with a first opening  150  in the concave surface  130  and a second opening opposite to the first opening  150 . A stop  151  is formed on the wall of the tunnel  15  near the first opening  150 . A thread  152  is formed on the wall of the tunnel  15  near the second opening. The thread of a bolt  16  is engaged with the thread  152 . The bolt  16  defines a central non-circular hole  160 . Preferably, the non-circular hole  160  is a square hole.  
      A movable jaw  17  is movable in the tunnel  15 . The movable jaw  17  includes a head and a tail  173  extending from the head. The head of the movable jaw  17  includes a normal abutment facet  170 , a sliding facet  171  near the normal abutment facet  170  and a slant abutment facet  172  near the sliding facet  171 . The tail  173  includes a non-circular cross-sectional profile. The non-circular cross-sectional profile is preferably square corresponding to the non-circular hole  160 .  
      The normal abutment facet  170  is used for abutment against the stop  151  formed on the wall of the tunnel  15 . Thus, the movement of the movable jaw  17  is confined between the bolt  16  and the stop  151 . The sliding facet  171  is used for smooth sliding on an opposite facet  22  of the nut or the head of the bolt  20  as shown in  FIG. 5 . The slant abutment facet  172  is used for abutment against a portion downstream to the center of the opposite facet  22  when the head of the movable jaw  17  is positioned at the opening  150 . The term “downstream” is used based on the intended driving direction of the one-way open-ended wrench.  
      The non-circular tail  173  is inserted into the non-circular hole  160  through a spring  18 . The spring  18  is preferably helical. The spring  18  is compressed between the head of the movable jaw  17  and the bolt  16 . The non-circular tail  173  can slide smoothly in the non-circular hole  160  so that the movable jaw  17  can move smoothly but cannot rotate.  
      As described above, the one-way open-ended wrench includes a simple structure and can transfer an adequate torque.  
      Referring to  FIG. 4 , when a user drives the one-way open-ended wrench in the intended driving direction as indicated by means of an arrowhead, the slant abutment facet  172  of the movable jaw  17  abuts the opposite facet  22 . The contact surface  120  of the first fixed jaw  12  abuts the selective facet  21 . Thus, the user can clamp the nut or the head of the bolt  20  by means of the movable jaw  17  and the first fixed jaw  12 , and then tighten the same.  
      Referring to  FIG. 5 , when the user drives the one-way open-ended wrench in a direction opposite to the intended driving direction as indicated by means of an arrowhead, the sliding facet  171  of the movable jaw  17  slides on the opposite facet  22 . The opposite facet  22  pushes the movable jaw  17  into the tunnel  15 . The movement of the movable jaw  17  causes the compression of the spring  18 . The opposite facet  22  sweeps over the concave surface  130 . The contact surface  120  of the first fixed jaw  12  abuts the selective facet  21 . Thus, the user will not rotate the nut or the head of the bolt  20  in the direction opposite to the intended driving direction. When the head of the movable jaw  17  is moved beyond the opposite facet  22 , the head of the movable jaw  17  is pushed from tunnel  15  by means of the spring  18 . Thus, the one-way open-ended wrench is ready for driving the nut or the head of the bolt  20  for another angle in the intended driving direction.  
      The present invention has been described through the illustration of the preferred embodiment. Those skilled in the art can derive 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 defined in the claims.