Abstract:
The present invention provides a wrench that may be simply manufactured at a lower defect rate, which prevents a foreign material from getting stuck in a gap between a ratchet and it&#39;s surrounding through hole, and which has a minimal extra space at an end of a first jaw or a second jaw to make it easier for a bolt or a nut to be inserted into the wrench.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application Nos. 10-2004-0030499 and 10-2008-0085267, filed on Apr. 8, 2009 and Aug. 29, 2008, respectively, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. This application also claims the benefit of International Application No. PCT/KR2008/007425, filed on Dec. 15, 2008, in the World Intellectual Property Organization, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a wrench, and more particularly, to a wrench that is continually turned to tighten a bolt or nut in a particular direction without having to be separated from the bolt or nut. 
         [0004]    2. Description of the Related Art 
         [0005]    A wrench is a tool that is commonly used to tighten or loosen a bolt or nut when assembling or disassembling mechanical parts. Wrenches, which are also called “spanners”, are classified into an open type and a closed type according to the shape of a head thereof. Open-type wrenches are further classified into a single-ended wrench and a double-ended wrench. In particular, a bolt or nut is tightened as a wrench is turned in one direction and is loosened as the wrench is turned in an opposite direction. 
         [0006]    In general, a wrench consists of a handle and a head. For example, as illustrated in  FIG. 1 , a handle  10  has a shape that can be held by a user. The head  20  includes a base portion  21  that extends from an end of the handle  10 , and a first jaw  22  and a second jaw  22 ′, which extend in parallel from opposite ends of the base portion  21  to face each other. 
         [0007]    However, when such a wrench is turned in a direction to tighten or loosen a bolt or a nut, several rotational strokes are needed unless there is a large enough space to allow full rotation of the handle  10  at 360 degrees. The wrench is detached from the bolt or the nut after each rotational stroke and then returned to the initial position so as to be able to apply an additional rotational stroke. This working process is inconvenient. 
         [0008]    In order to overcome the inconvenience of having to remove the wrench from the bolt or nut in order to repeatedly apply rotational strokes in a particular direction, a wrench having a flexible ratchet has been developed. 
         [0009]    Referring to  FIG. 2 , a conventional wrench having a extensible and contractable ratchet includes a handle  10   a,  and a head  20   a  that includes a base portion  21   a  extending from an end of the handle  10   a,  and a first jaw  22   a ′ and a second jaw  22   a  that extend in parallel from opposite ends of the base portion  21   a.  In particular, the wrench further includes a ratchet  24   a  that is flexibly fit to a slot formed in in the first jaw  22   a ′ and that is covered by a cover plate  22   a ″. The ratchet  24  protrudes towards the base portion  21   a  and compresses a coil spring that is fit into the slot. In addition, the ratchet  24   a  is flexibly inserted, for example, to be recessed, into the slot to which the coil spring is fit. The cover plate  22   a ″ is welded to the top and bottom of the slot. 
         [0010]    The conventional wrench having the flexible ratchet  24   a  constructed as described above works smoothly when being turned in a direction in which the ratchet  24   a  can prevent the bolt or nut from slipping off the wench. As the ratchet  24   a  that is flexibly fit to the slot tightens the bolt or nut while pushing the bolt or nut, a contact area between the bolt or nut is maximized. A large contact area may be secured even for a worn bolt or nut. As a result, worn bolts or nuts may be effectively tightened or loosened with the wrench. However, the conventional wrench has the following drawbacks. 
         [0011]    First, the first jaw  22   a ′ includes the slot and the cover plate  22   a ″. However, the dimensional accuracies of these elements may be low if the elements are separately manufactured. In this case, a gap may occur between the second jaw  22   a  and the cover plate  22   a ″, and foreign substances may get stuck in the gap. 
         [0012]    Second, it is inconvenient to perform an extra process of welding or binding the cover place  22   a ″ to the top and bottom of the slot. In addition, the external appearance of the wrench may not be aesthetically pleasing. 
         [0013]    Third, a minimum space for the cover plate  22   a ″ to be attached is required in the first jaw  22   a ′. As the end of the second jaw  22   a ′ lengthens, a bolt or a nut to be held by the wrench needs to be positioned deep inside the head  20   a.  However, this may cause the bolt or nut to interfere with the insides of the first jaw  22   a ′ and the second jaw  22   a,  thereby making it difficult for the bolt or nut to be positioned deep inside the head  20   a.    
         [0014]    Fourth, a crack may occur around an edge region of the slot, and the wrench is liable to be broken. 
         [0015]      FIG. 3  illustrates another example of a conventional wrench. A reception groove is formed in a first jaw  22   b ′ of the wrench, extending outwards from the inside of the first jaw  22   b ′. In addition, a through hole is formed in a second jaw  22   b,  passing through the second jaw  22   b  from the inside to the outside. Ratchets  24   b ′ and  24   b  are respectively inserted into the reception groove and the through hole in such a manner as to protrude inwards. The ratchets  24   b ′ and  24   b  are elastically supported by a spring  25   b  and a blocking plate  26   b.  The ratchet  24   b  inserted into the through hole of the second jaw  22   b  engages with the circumference of the bolt or nut and tightens the bolt or nut when the wrench holds the bolt or nut and is then turned in one direction. However, as the wrench is turned in an opposite direction, the ratchet  24   b  slides backwards into the through hole, so that only the wrench is turned while the bolt or nut remains in a fixed state. However, as the ratchet  24   b  slides backwards, an end of the ratchet  24   b  may externally protrude out of the through hole. 
         [0016]    However, the conventional wrench described above has the following drawbacks. 
         [0017]    First, in the conventional wrench, the first jaw  22   b ′ and the second jaw  22   b  have the respective ratchets  24   b ′ and  24   b.  As a result, the conventional wrench is liable to be broken. When the wrench is turned, a tensile force is exerted on either the first jaw  22   b ′ or the second jab  22   b  depending on the rotation direction of the wrench, whereas a compression force is exerted on the other one. In other words, when the wrench is turned clockwise, as illustrated in  FIG. 4 , a tensile force is exerted on the first jaw  22   b ′, while a compression force is exerted on the second jaw  22   b.  Apart from the second jaw  22   b  on which the compression force is exerted, the first jaw  22   b ′ is more likely to be broken by an external force. If the first jaw  22   b ′ has the reception groove, as described above, cracks may occur around the reception groove of the first jaw  22   b ′ as tightening is repeated. 
         [0018]    Second, as the ratchet  24   b  of the second jaw  22   b  is slidably pushed outwards by the bolt or nut, the end of the ratchet  24   b  protrudes outwards, as illustrated in  FIG. 4 . This may reduce the radius of rotation of the wrench. In other words, when a working space is limited and there is an obstacle around the head of the wrench, the protruding ratchet  24   b  may interfere with the obstacle, and thus interrupt the rotation of the wrench. 
       SUMMARY OF THE INVENTION 
       [0019]    The present invention provides a wrench that may be simply manufactured at a lower defect rate, which prevents a foreign material from getting stuck in a gap between a ratchet and it&#39;s surrounding through hole, and which has a minimal extra space at an end of a first jaw or a second jaw to make it easier for a bolt or a nut to be inserted into the wrench. 
         [0020]    The present invention provides a wrench that prevents cracking in a first jaw or a second jaw due to repeated tightening and that minimizes the interruption of rotation of the wrench by a surrounding obstacle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0022]      FIG. 1  is a perspective view of a conventional wrench; 
           [0023]      FIG. 2  is a perspective view of a conventional wrench including a ratchet; 
           [0024]      FIG. 3  is a cross-sectional view of a conventional wrench including a ratchet; 
           [0025]      FIG. 4  is a view for explaining the operational mechanism of the wrench of  FIG. 3 ; 
           [0026]      FIG. 5  is a cross-sectional view of a wrench according to an embodiment of the present invention; 
           [0027]      FIG. 6  is an exploded cross-sectional view of the wrench of  FIG. 4 ; 
           [0028]      FIG. 7  is an overall perspective view of the wrench of  FIG. 4 ; 
           [0029]      FIG. 8  is a cross-sectional view of a wrench according to another embodiment of the present invention; and 
           [0030]      FIG. 9  is a cross-sectional view of a wrench according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Hereinafter, embodiments of the present invention will be described in detail with reference to the appended drawings. 
         [0032]      FIGS. 5 through 7  illustrate a wrench having a flexible ratchet according to an embodiment of the present invention. 
         [0033]    The wrench according to the present embodiment refers to a tool that may be used to tighten a bolt or nut by being turned in one direction and to loosen the bolt or nut by being turned in the opposite direction. The wrench includes a handle  100 , a head  110 , a ratchet member  120 , an elastic pressure member  130 , and a blocking member  140 . 
         [0034]    The handle  100  has a shape that can be hand-held by a user. The handle  100  may have a bar shape extending in a particular direction. The handle  100  may be formed of a high-hardness, metallic material. However, the handle  100  is not limited to this, and may be formed of various materials. 
         [0035]    The head  110  is manufactured as a whole by casting. The head  110  is bound with the handle  100  in a single body, and contacts and holds the bolt or nut. The head  110  has a “C”-shape with an open end. The head  110  includes a base portion  110   c,  a first jaw  110   a,  and a second jaw  110   b.    
         [0036]    The base portion  110   c,  which is a portion opposite to the open end of the head  110 , extends from an end of the handle  100 . 
         [0037]    The first jaw  110   a  and the second jaw  110   b  extend in parallel from opposite ends of the base portion  110  to face each other. The first jaw  110   a  and the second jaw  110   b  may have, but are not limited to, symmetrical shapes. The first jaw  110   a  and the second jaw  110   b  may have different shapes if required. Together, the first jaw  110   a  and the second jaw  110   b  have a circular shape. The base portion  110   c,  the first jaw  110   a  and the second jaw  110   b  engage with a head portion of the bolt or nut as the head portion of the bolt or the nut is received in a space defined inside the base portion  110   c,  the first jaw  110   a,  and the second jaw  110   b  through the open end of the head  110 . 
         [0038]    A through hole  112   b  passing through the second jaw  110   b  from the outside of the second jaw  110   b  near the end of the second jaw  110   b  to the inside of the second jaw  110   b  near the base portion  110 c is formed in the second jaw  112   b.  In particular, the through hole  112   b  is elongated from the end of the second jaw  112   b  towards the base portion  110   c,  which may contact the bolt or nut. Due to the elongated direction of the through hole  112   b,  the ratchet member  120  may slide from the end of the second jaw  11   b  towards the base portion  110   c  as the ratchet member  120  is inserted into the through hole  112   b.  A stepped portion  111   b,  which protrudes inwards in the through hole  112   b,  is formed in a portion of the through hole  112   b  close to the base portion  110   c.  The stepped portion  111   b  has a function of stopping the ratchet member  120  from escaping out of the through hole  112   b,  which will be described later. 
         [0039]    In the present embodiment, the first jaw  110   a  refers to a portion on which a tensile force is exerted as the wrench is turned in a direction to tighten the bolt or nut, and the second jaw  110   b  refers to a portion on which a compression force is exerted. The positions of the first jaw  110   a  and the second jaw  110   b,  i.e., which one is above or below the other, may differ from the illustrations in  FIGS. 5 and 6 . In other words, although the first jaw  110   a  is illustrated to be in an upper position with respect to the second jaw  110   b  in  FIGS. 5 and 6 , the positions of the first jaw  110   a  and second jaw  110   b  may be switched. 
         [0040]    The ratchet member  120  is inserted into the through hole  112   b  to protrude out of the through hole  112   b  towards the base portion  110   c,  so that the ratchet member  120  contacts and engages with the bolt or nut, thereby tightening the bolt or nut. The ratchet member  120  may have a pillar shape with a rectangular cross-section, but is not limited to this, and may have various shapes. A portion of the ratchet member  120  that contacts the head portion of the bolt or nut may have a smooth surface, or may have a toothed surface if needed, in order to prevent slipping on the bolt or nut. 
         [0041]    A keeper  121  is formed on a portion of the ratchet member  120  opposite to the portion contacting the head portion of the bolt or nut. The keeper  121  may have a shape corresponding to the shape of the stepped portion  111   b  of the through hole  112   b  so that the keeper  121  is engaged with the stepped portion  111   b.  As the keeper  121  is engaged with the stepped portion  111   b,  the ratchet member  120  is prevented from escaping out of the through hole  112   b.  In other words, the ratchet member  120  may only slide within a particular distance range. 
         [0042]    The elastic pressure member  130  has a structure for elastically pressing the ratchet member  120  towards the base portion  110   c.  An end of the elastic pressure member  130  is supported by the blocking member  140 , whereas the other end of the elastic pressure member  130  contacts and elastically supports the ratchet member  120 . In particular, the elastic pressure member  130  is disposed between the ratchet member  120  and the blocking member  140  to elastically press the ratchet member  120 . The elastic pressure member  120  may be a coil spring. However, the elastic pressure member  120  may be any elastic element that is repeatedly compressible and extensible, such as elastic rubber. 
         [0043]    The blocking member  140 , which blocks an end of the through hole  112 , may be formed of various materials that can support an end of the elastic pressure member  130 , such as a metallic material or a synthetic resin. The blocking member  140  may be fixedly bound to the through hole  11   b  by, for example, welding. Alternatively, the blocking member  140  may be fixed to the through hole  112   b  by tight fitting. 
         [0044]    The wrench according to the current embodiment may be assembled as follows. Initially, the head  110  and the handle  100  are formed as a single body of the wrench by casting. Next, the ratchet member  120  is inserted into the through hole  112   b.  In particular, the ratchet member  120  is inserted into the through hole  112   b  from the end of the second jaw  110   b  towards the base portion  110   c.  Then, the elastic pressure member  130  is inserted into the through hole  112   b  to contact the ratchet member  120 . Finally, the blocking member  140  is tightly fit into the through hole  112   b.  As a result, the ratchet member  120  may slide towards the base member  110   c  while being elastically supported in the through hole  112   b.    
         [0045]    The wrench described above may operate as follows. 
         [0046]    When the wrench is turned in a direction in which the ratchet member  120  tightens the bolt or nut, the ratchet member  120  comes in contact with the bolt or nut, and a force driving the ratchet member  120  to move towards the base portion  110   c  is applied. Herein, the position of the keeper  121  of the ratchet member  120  is fixed by the stepped portion  111   b  in the through hole  112   b,  and the ratchet member  120  engages with and tightens the bolt or nut within the space inside the head  110 . Meanwhile, when the wrench is turned in the opposite direction, a force driving the ratchet member  120  to move towards the end of the second jaw  110   b  is applied. If the force is greater than the elastic repelling force of the elastic pressure member  130 , the ratchet member  120  may slide towards the end of the second jaw  110   b,  which allows the wrench to be turned with respect to the bolt or nut. When the wrench is turned again in the initial tightening direction, the bolt or nut is tightened as described above. Thus, while the wrench is turned alternately in opposite directions forwards and backwards, the relative position of the bolt or nut in the head  110  of the wrench may be fixed and the wrench does not have to be separated from the nut or bolt for each turn of alternate direction. 
         [0047]    Regarding the wrench according to the current embodiment, the first jaw  110   a  and the second jaw  110   b  including the through hole  110   b  may be manufactured all at the same time as a single body. Thus, it is straightforward to manufacture the wrench on a mass scale, and the manufacturing costs are lowered. Meanwhile, since a conventional method of manufacturing a wrench may involve forming an additional slot in a first jaw and binding a cover plate, which has been previously manufactured, to the slot, the overall manufacturing process is complicated. In addition, a gap may be formed in a portion where the cover plate and the slot are bound unless a skilled worker is involved. Furthermore, a foreign material may get stuck in the gap between the cover plate and the slot. In particular, it is difficult to automate the binding process, and thus to manufacture the wrench on a mass scale. 
         [0048]    Meanwhile, according to the current embodiment of the present invention, the ratchet member  120  is installed to slide toward the base portion  110   c.  This may contribute to miniaturization of the wrench and simplifies the manufacturing process compared to the conventional wrench in which an end of the ratchet  24   b  protudes out of the through hole towards the end of a jaw, as illustrated in  FIG. 4 . In addition, in the wretch according to the current embodiment of the present invention, the ratchet member  120  is installed only in the second jaw  110   b  on which the compression force is exerted. Thus, the wrench according to the current embodiment is more durable than the conventional wrench including a through hole or a groove in a jaw on which the tensile force is exerted. In addition, the wrench according to the current embodiment is designed such that the ratchet member  120  protrudes only towards the base portion  110   c,  unlike the conventional wrench in which the ratchet  24   b  protrudes towards the end of the second jaw  22   b.  Thus, the wrench according to the current embodiment may not interfere with any surrounding obstacles while being turned, and thus may be conveniently used in a working environment that has a limited amount of space. 
         [0049]    Unlike the conventional wrench, the wrench according to the current embodiment does not include a cover plate, but has a through hole. As a result, it is unlikely that the tensile strength of the second jaw is reduced and that the second jaw cracks. The appearance of the wrench according to the current embodiment may look fine since it does not include the cover plate. In addition, the wrench may be precisely manufactured by casting, and thus, a foreign material is less likely to get stuck in the gap between the ratchet member  120  and the through hole  112   b.    
         [0050]      FIG. 8  illustrates a wrench according to another embodiment of the present invention. The wrench according to the current embodiment differs from the previous embodiment in terms of the blocking member. The blocking member  140  of the wrench according to the previous embodiment is formed as a single body and is inserted into the through hole  112   b.  However, a blocking member  140  according to the current embodiment includes a metal plate  141  and a filler portion  142 . The metal plate  141 , which has a function to support the elastic pressure member  130 , is formed of a metallic steel sheet, such as stainless steel. The metal plate  141  may be fixedly installed within the through hole by tight fitting, welding, or the like. 
         [0051]    The filler portion  142 , which fills a space between a surface of the metal plate  141  and the end of the second jaw  110   b,  is formed by filling the space with high-strength polyurethane and curing the filling material. Alternatively, once the space has filled with liquid high-strength polyurethane, the filling material may be cured along with a predetermined metallic pattern such that the pattern appears on the surface of the filler portion  142 . As a result, the overall appearance of the wrench may be aesthetically pleasing. For example, the predetermined metallic pattern may be a logo of the manufacturing company. 
         [0052]      FIG. 9  illustrates a wrench according to another embodiment of the present invention. In the wrench according to the current embodiment, the first jaw  110   a  and the second jaw  110   b  are formed to be shorter than those of the previous embodiments. In particular, the wrench has a shape for keeping hold of a bolt or nut to be tightened within the head  110  of the wrench while being turned in a particular direction. Thus, a user may work more conveniently with the wrench. In particular, the wrench may have a shape such that the shortest distance (b) between a virtual line connecting the end of the first jaw  110   a  and the end of the second jab  110   b  and the center of rotation of a bolt or nut held in the head  110  is smaller than the shortest distance (a) between the center of rotation of the bolt or nut and the base portion  110   c.  Furthermore, the head  110  may have an oval shape. If the head  110  has an oval shape, the open end of the head  110  may be wider, and thus the bolt or nut to be tightened may be positioned deep inside the head  110  upon being inserted into the head  110 , in a single direction. In other words, if the lengths of the first jaw  110   a  and the second jaw  110   b  are large, as in the previous embodiments, a path to the bolt or nut&#39;s final position deep inside the head  110  is narrow and long. Thus, once the bolt or nut to be tightened has be placed within the head  110  in a particular direction, the bolt or nut needs to be further moved in upper and lower diagonal directions until the bolt or nut is in the final position, deep inside the head  110 . However, if the head  110  has an oval shape as in the current embodiment, the bolt or nut may be placed in the final position within the head  110  upon being inserted into the head  110  in a single direction. 
         [0053]    In addition, according to the current embodiment, the width of the first jaw  110   a  on which the tensile force is exerted is increased to reinforce the tensile strength of the first jaw  110   a.  Thus, even if the tensile force is repeatedly applied, the first jaw  110   a  may not crack, and a crack in the first jaw  110   a  may not further develop. 
         [0054]    Although the present invention is described above with reference to the exemplary embodiments, the present invention may be implemented in various forms as follows. 
         [0055]    While the through hole is described as being formed in the first or second jaw by casting in the embodiments described above, the present invention is not limited to the embodiments, and the through hole may be formed by drilling. 
         [0056]    In addition, while an end of the through hole receiving the ratchet member is described as being blocked by the stopping member in the embodiments described above, the present invention is not limited to the embodiments, and the end of the through hole may be partially open provided that the through hole is formed in either the first jaw or the second jaw. 
         [0057]    Furthermore, while the filler portion is described as being formed of high-strength polyurethane in the previous embodiment, the filler portion may be formed of various materials, such as epoxy resin, provided that it ensures a sufficient tensile strength after being cured. 
         [0058]    As described above, a wrench according to the present invention includes a through hole in a jaw passing through from an end of the jaw to an inner portion of the jaw close to the base portion. Thus, unlike the conventional wrench in which the edge portion of a slot formed in a jaw of the wrench may crack and is likely to break, cracking is less likely to occur in the wrench according to the present invention. 
         [0059]    In addition, the wrench according to the present invention may be manufactured on a mass scale by, for example, casting. In particular, the wrench may be simply assembled by inserting a ratchet member and an elastic pressure member into the through hole and blocking the through hole with a blocking member. 
         [0060]    The overall manufacturing process is simplified, and the accuracy in assembling the wrench is improved, compared to conventional wrenches. In addition, since the ratchet member is installed only in a jaw on which the compression force is exerted, the tensile strength is high, and cracking is less likely to occur. 
         [0061]    Furthermore, an end of the ratchet member inserted into the through hole of the wrench according to the present invention protrudes out of the through hole towards the base portion, whereas the opposite end of the ratchet member slides within the through hole. Thus, the ratchet member may not interrupt the rotation of the wrench even when used in a working environment that has a limited amount of space. 
         [0062]    Finally, the first jaw and the second jaw of the wrench according to the present invention are shorter than conventional ones, and thus a bolt or nut to be tightened may be positioned deep inside a head of the wrench upon being inserted into the head in a single direction. Thus, it is straightforward to work with the wrench, and the working span is small. Thus, the wrench may be used in various working environments. 
         [0063]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.