Abstract:
A wrench comprising two driving stems pivotally connected with each other. One of the driving stems has a main body and a flat portion, protruding from the main body with a hole at a center thereof. The other driving stem has the other main body and the other flat portion protruding from the other main body with at a center thereof. A pair of hinges having two holes aligned with the holes of the flat portions protruding from the main bodies of the driving stems, respectively, is used. Two sets of bolts and nuts are used to be threaded through the holes of the hinges, the flat portion protruding from main bodies of the first and the second driving stems, respectively.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to a wrench having two driving stems pivotally connected with each other. More particularly, this invention relates to a hex key type or Allen wrench having two individual driving stems pivotally connected with each other. 
     2. Description of the Related Art 
     A conventional wrench, for example, an Allen wrench, used for gripping and turning or twisting the head of a bolt, a nut, a pipe, or the like commonly typically comprises a one-piece L-shape metal with one end used as the driving stem and the other end used as a handle. 
     In U.S. Pat. No. 5,943,925, Huang discloses a tool having a foldable structure. The foldable structure disclosed by Huang comprises a coupler pivotally coupled between a driving stem and a handle. Applying the foldable structure to the Allen wrench, the driving stem can be folded in parallel with the handle, that is, with a zero angle relative to the handle. This results in a more compact space for storing the tool. In Huang, with respect to the handle, the driving stem can be rotated from an angle of zero degree to an angle of 180 degree. While turning a bolt in a limited space, for example, around the boundary of two perpendicularly adjoining planes, the handle of the Allen wrench adopting the foldable structure disclosed by Huang can only be turned between zero degree to 180 degrees along a surface perpendicular to the driving stem. When a half circle of the turning action is complete, the user has to disengage the wrench from the bolt. By repositioning the handle to the original point of the turning action, the turning action is repeated until the bolt is fastened as required. In other words, while tightening/untightening a screw, a bolt or a nut in a plane with a limited degree of freedom, a user may need to repeat engaging and disengaging the driving stem to reposition the handle. Moreover, using this conventional structure, there is only one end of the wrench that can be used as the driving tool while the other end is used as a handle only. When a different torque is required, or a screw, a bolt or a nut with different depth is to be driven thereby, a different driving stem has to be connected and reassembled. 
     SUMMARY OF THE INVENTION 
     The invention provides a wrench having two driving stems pivotally connected with each other. One of these two pivotally connected driving stems flips from an angle of about 90 degrees to an angle of about 270 degrees relative to the other. 
     Thus arranged, one of the driving stems used as a handle can flip with an angle from about 90 degrees to about 270 degrees with respect to the other of the driving stems used for driving a screw or a bolt. Therefore, when the rotation of the handle is obstructed, the handle can be lifted up or down to perform fastening or removing. The specific flipping angle of the handle actually depends on the distance between the adjoining ends of the driving stems. That is, with sufficient clearance between adjoining ends, the handle can also be flipped from an angle less than 90 degree to an angle larger than 270 degrees. 
     The applicability of the wrench structure provided by the invention is also applicable for driving a screw or a bolt in a space with limited degree of freedom, for example, in the situation that the rotation of the handle is obstructed by the presence of an object. As an example, while driving a bolt on a plane with a second plane protruding nearby, the bolt is engaged with the driving stem, and the handle is turned to drive the driving stem, so as to thread/unthread the bolt. Being obstructed by the protruding object, the rotating range of the handle is limited within a certain angle along a surface parallel to the first plane. When the rotating action of the handle is from one end to the other, that is, from an angle of zero degree to the certain degree along the surface, the user does not need to disengage the driving stem from the bolt. Instead, the user can simply flip the handle to the other end, that is, from the angle of 90 degree to 270 degree relative to the driving stem, and carry on driving the bolt. 
     In addition, with the structure of two driving stems pivotally connected together, one may choose either one of the driving stems as a handle, and the other driving stem to engage and drive an object, for example, a screw, a nut, a bolt or the like. With object with different depth to be engaged and driven, or when a different torque is required, one may interchange the functions of these two driving stems. 
     Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a wrench with one driving stem positioned perpendicularly to the other driving stem in accordance with the present invention; 
     FIG. 2 is a front view of a wrench with one driving stem in line with the other in accordance with the present invention; 
     FIG. 3 is a side view of a wrench with one driving stem in line with the t other in accordance with the present invention; 
     FIG. 4 is a front view of a wrench with one driving stem positioned perpendicularly to the other driving stem in accordance with the present invention; 
     FIG. 5 is a side view of one of the driving stems; 
     FIG. 6 is a front view of the driving stem as shown in FIG. 5; 
     FIG. 7 is a front view of the other driving stem; 
     FIG. 8 is a side view of the other driving stem as shown in FIG. 7; 
     FIG. 9 is a perspective view of a head of one of the bolts that couple two driving stems; 
     FIG. 10 is a plan view of a nut used to couple two driving stems; 
     FIG. 11 is a side view of the bolt used to couple two driving stems; 
     FIG. 12 is a top view of the hat of the bolt as shown as FIG. 11; 
     FIG. 13 is a plan view of a hinge used to couple the driving stems; 
     FIG. 14 is a side view of the hinge as shown in FIG. 13; 
     FIG. 15 shows the flipping range of one driving stem with respect to the other driving stem of the wrench provided by the invention; 
     FIG. 16 shows the operation of using the wrench to thread/unthread an object on a plane with the presence of an object protruding from the plane to obstruct operation; 
     FIG. 17 shows the rotating range and the flipping range of the handle of the wrench with the presence of an object obstructing operation; and 
     FIG. 18 shows another way of operating under the situation as shown in FIG. 17; and 
     FIG. 19 shows an exploded view of the wrench. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to  19  illustrate the present embodied by a hex-key type or Allen wrench with two driving stems pivotally connected with each other. Being pivotally connected, one of the driving stems is used as a handle to drive the other driving stem, an object such as a nut, a screw or a bolt can be threaded or unthreaded. When one is threading/unthreading the object, the handle can be flipped from an angle of about 90 degree to about 270 degree with respect to the driving stem used to thread/unthread the object. In this manner, even with the presence of an object that obstructing the threading/unthreading operation, the user does not need to disengage the object and rotate the handle to carry on threading/unthreading. Instead, one can simply flip over the handle and repeat rotating the handle to complete the threading/unthreading operation. In addition to the application of a hex-key or Allen wrench, it is appreciated that people of skill in the art may modify the disclosure of this embodiment and apply to other driving tool such as a box wrench, an open-end wrench, a socket wrench, or the like. 
     FIG. 1 shows a side view of the wrench comprising two driving stems pivotally connected with each other. In this embodiment, two sets of bolts and nuts are used to thread through each of the driving stems. As shown in FIG. 1, when a bolt  16  is threaded into the observed side of the lower driving stem  10 , a nut  14  is threaded from the same side of the upper driving stem  12 . The alternate usage of the bolts  16 ,  20  and nuts  14 ,  18  can be clearly observed from a front view as shown in FIG.  4 . FIGS. 1 and 4 both show the wrench with the driving stems  10 ,  12  positioned perpendicularly with each other. 
     FIGS. 2 and 3 shows both the side view and the front view of the wrench as shown in FIGS. 1 and 4, whereas, the driving stems  10  and  12  are in line with each other. In addition, two sets of bolts  16  and  20 , and nuts  14  and  18 , and a pair of washers or hinges  22 , are used to connect the driving stems  10  and  12 . Referring to FIGS. 1-4, the washers or hinges  22  are connected between the driving stems  10  and  12  with bolts  16  and  20  and nuts  14  and  18  threading through the washers or hinges  22  and the driving stems  10  and  12 . 
     FIG. 5 shows an exploded side view the lower driving stem  10 . As shown in this figure, at the top end of the driving stem  10 , a flat portion  10   a  protrudes from the center of the main body. In the example of a hex key, the width of the flat portion  10   a  is preferably equal to the width of one of the six sides. FIG. 6 is a front view of the lower driving stem  10 . The flat part  10   a  protrudes from center side of the observed three sides of the main body. 
     FIG. 7 and 8 show the front view and side view of the upper driving stem  12 . The structure of the upper driving stem  12  is similar to the structure of the lower driving stem  10  except that the protruding portion  12   a  has the rounded corners. 
     FIGS. 9-10 show the side view and top view of a dome shaped nut, and FIGS. 11-12 show the side view and the top view of a bolt. FIGS. 13-14 show the front view and the side view of the hinges. Preferably, the protruding portions of the lower and the upper driving stems are the same, and the length of the hinge connected between two driving stems is slightly larger than the length of the protruding portions to allow one of the driving stems to flip over the other one. However, the actual length of the hinge can be varied according to specific requirements. As a result, the specific flipping angle of the handle actually depends the distance between the driving stems, or the length of the hinge. That is, the handle can also be flipped from an angle less than 90 degree to an angle larger than 270 degree. 
     With the structure as shown in FIGS. 1-14, the wrench can be used to thread/unthread an object such as a nut, a bolt or a screw through a plane. During the operation, one of the driving stems is selected as a handle, and the other is selected as the object driving stem according to the specific dimension of the object to be threaded. For example, while threading/unthreading an object with a longer depth, a longer driving stem is selected as the object driving stem and the shorter driving stem is used as the handle rotated to drive the object driving stem. In contrast, when the object to be threaded/unthreaded has a shorter depth, a shorter driving stem is selected as the object driving stem, and a longer driving stem is selected as the handle to result in a large torque for operation. 
     Preferably, as shown in FIG. 15, the length of the hinge or washer is designed to allow one of the driving stem, for example, the upper driving stem to flip over the lower stem with a flipping range of about 180 degree. That is, the upper driving stem can be flipped from an angle of about 90 degree to an angle of about 270 degree with respect to the lower driving stem. Therefore, when the operation of driving an object is obstructed, the upper driving stem can be lifted up or down to a degree that allows the driving stem used as the handle to rotate continuously without being interrupted until the object is tightened or untightened as required. 
     FIG. 16 shows a condition for tighten/untighten a nut  24  from a bolt threaded into a plane  26 . A plane  28  perpendicularly protrudes from an edge of the plane  26  as shown in the figure. The wrench  50  with the structure as shown in FIGS. 1-14 is used to drive the nut  24  with the plane  28  protruding nearby. If the distance between the nut  24  and the plane  28  is negligible, the driving range of the nut  24 , that is, the rotating range of the handle of the wrench  50  is about 180 degree. It is thus difficult to make a full circle turn of the handle using a conventional wrench. As mentioned above, for a conventional wrench, the user has to disengage the nut  24  from the nut driving stem of the wrench first. The handle of the wrench can then be repositioned to repeat the rotation step. However, using the wrench in accordance with the invention, one can simply flip over the handle, so as to reposition the handle to a required position, the rotation of the handle, that is, the tightening/untightening step can be performed continuously. FIG. 17 shows the rotating range and the flipping range of the handle of the wrench provided by the invention. 
     FIG. 18 shows the operation of driving the nut with the handle in line with the nut driving stem. In this manner, even when the peripheral of the nut is completely obstructed, the tightening/untightening action for the nut can still be performed. 
     FIG. 19 shows an exploded view showing the connectivity between the upper driving stem  12  and the lower driving stem  10 . As shown in this figure, driving stems  10  and  12  are in line with each other. Two sets of bolts  16  and  20 , and nuts  14  and  18 , and a pair of washers or hinges  22 , are used to connect the driving stems  10  and  12 . The washers or hinges  22  are connected between the driving stems  10  and  12  with bolts  16  and  20  and nuts  14  and  18  threading through the washer or hinges  22  and the driving stems  10  and  12 . 
     Other embodiments of the invention will appear to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples to be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.