Abstract:
A wrench having two driving stems pivotally connected with each other. One of the driving stems has a main stem and a female joint protruding from a rectangular or cylindrical section of the main stem with a hole at a center thereof. The other driving stem has the other main stem and a male joint projecting out of the center of a rectangular or cylindrical section of the main stem. The male joint and the female joint are engaged with each other via a coupler such as a roll pin. Therefore, without using an additional hinge or other mechanical coupler, these two driving stems are pivotally connected with each other.

Description:
CROSS REFERENCE 
     This application is a continuation in part of the parent application Ser. No. 09/542,824 filed Apr. 4, 2000, now U.S. Pat. No. 6,314,844 the full disclosure of which is incorporated herein by reference. 
    
    
     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 cap screw, a nut, a pipe, or the like commonly 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 degrees to an angle of 180 degrees. While turning a bolt in a limited space, for example, around the boundary of two perpendicularly joint planes, the handle of the Allen wrench adopting the foldable structure disclosed by Huang can only be turned between zero degrees 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 the driving stems has a female fork joint protruding from the main stem with a hole at the center thereof. The other driving stem has a male connecting joint protruding form the axial center of the main stem. The male joint and the female joint are engaged with each other via a connector such as a roll pin. Therefore, without using an additional hinge or other mechanical coupler, these two driving stems are 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, a bolt or a nut. 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 driving stems. That is, the handle can also be flipped from an angle less than 90 degrees to an angle larger than 270 degrees. 
     The applicability of the wrench structure provided by the invention is also applicable for driving a socket head screw, bolt or nut 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. For example, while driving a socket head cap screw on a plane with a second plane protruding nearby, the screw is engaged with the driving stem, and the handle is turned to drive the driving stem, so as to thread/unthread the screw. 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 nut. Instead, the user can simply flip the handle to the other end, that is, from the angle of 90 degrees to 270 degrees relative to the driving stem, and carry on driving the screw. 
     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. When an object with a different depth is to be engaged and driven, or when a different torque is required, one may interchange the functions of these two driving stems. Further, in certain circumstances, the user may choose to align the two stems with each other (at zero degree angle) and drive the object by applying a socket wrench to the free end of the stem opposite the driving stem. 
     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 ( a ) to FIG.  1 ( g ) are side and front views of a wrench with one driving stem positioned perpendicularly to the other driving stem in accordance with the present invention; 
     FIG.  2 ( a ) to FIG.  2 ( d ) show different views of one of the driving stems with a female joint in accordance with the present invention; 
     FIG.  3 ( a ) to FIG.  3 ( d ) show different views of one of the driving stems with a male joint in accordance with the present invention; 
     FIG. 4 shows the method of assembling two driving stems in accordance with present invention; 
     FIG.  5 ( a ) to FIG.  5 ( d ) are different views of a driving stem with a male joint in another embodiment according to the invention (i.e. an alternative design with greater strength male joint); and 
     FIG.  6 ( a ) to FIG.  6 ( d ) are different views of a driving stem with a female joint in another embodiment according to the invention (i.e., an alternative design with greater strength female joint.) 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS.  1 ( a ) to  6 ( e ) illustrate the present invention 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 so that an object such as a socket head nut, screw or bolt can be threaded or unthreaded. When one is threading/unthreading the object, the handle can be flipped from an angle of about 90 degrees to about 270 degrees with respect to the driving stem used to unthread/unthread the object. In this manner, even with the presence of an object that obstructs 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 types of driving tools such as a box wrench, an open-end wrench, a socket wrench, or the like. 
     FIG.  1 ( a ) shows a side view of the wrench comprising two driving stems pivotally connected with each other. In this embodiment, a roll pin  14  is used to thread through each of the driving stems. It is appreciated that the roll pin  14  can also replaced with other similar coupler such as a set of bolt and nut. The usage of the roll pin  14  can be clearly observed from the partly exploded front views as shown in FIG.  1 ( a ) and FIG.  1 ( b ). FIGS.  1 ( a ) to  1 ( c ) all show the wrench with the driving stems  10 ,  12  positioned perpendicularly with each other. 
     As an alternative configuration, FIGS.  1 ( d ) and  1 ( e ) show the wrench having an end with cut away grove and rounded stem end corners  26  at one end of the driving stem  10 . Said rounded end is designed for ease of engaging the wrench with the fastening device such as a screw, a bolt, or a nut. As an alternative configuration, FIG.  1 ( f ) shows the cut away grove and rounded stem end corners  26  at one end of the driving stem  12 . As another alternative configuration, FIG.  1 ( g ) shows the cut away grove and rounded stem end corners  26  being at one end of the driving stem  10  and at one end of the driving stem  12 . 
     FIGS.  2 ( a ) and  2 ( b ) show both the side view and the front view of the driving stem  10  of the wrench. As shown in FIG.  2 ( a ), the driving stem  10  comprises a female joint at one end thereof. At the end of the driving stem  10 , a rectangular section extends from the driving stem, and two fillets  16  with equal dimensions stand out from two opposite edges of the rectangular section and leave a space in between. FIG.  2 ( c ) shows a cross sectional view of the driving stem  10  cutting along the line II—II. As shown in FIG.  2 ( c ), the cross section of the driving stem  10  is a hexagon with a width of d for each side. The cant of each side is about 60 degrees. 
     As illustrated in FIG.  2 ( d ), the width of the fillets  16  is equal to {square root over (3)}d, and the thickness of each plate is equal to half of the length of each side, that is, d/2. It is appreciated that the thickness and width are not limited only to such magnitudes and the wrench can still work properly while the thickness of the fillets vary. Referring to FIG.  2 ( b ), each of the fillets  16  has a hole in the center thereof. The holes of both fillets  16  align with each other such that a roll pin  14  as shown in FIG.  1 ( a ) can thread through both holes. 
     FIGS.  3 ( a ) to  3 ( c ) show the driving stem  12  with a male joint  22 . The male joint  22  includes a projection of rectangular cross section which protrudes from a central portion of one end from one side to the opposite side of the driving stem  12 . The male joint  22  has a thickness to be fitted into the space between two fillets  16  of the female joint of the driving stem  10 . Preferably, the thickness is approximately equal to the length d of one side of the driving stem  10 . The width of the projection  22  is about {square root over (3)}d. 
     FIG.  3 ( c ) shows a cross sectional view of the driving stem  12  along the cutting line III—III. It is clearly seen that the driving stem  12  has a hexagon cross section with each side having a width of d. A top view of the male joint on top of the driving stem  12  is shown as FIG.  3 ( d ). The male joint also has a hole in the center thereof to enable the roll pin  14  to thread through as shown in FIG.  3 ( b ). Referring to FIG.  3 ( b ), the male joint is a dome like structure having a width approximately the same as the width of the space between the fillets  16  in the driving stem  10 . Thus, these two stems  10  and  12  are pivotally coupled to each. One can thus flip one of the driving stems  10  and  12  from an angle of 90 degrees to an angle of 270 degrees with respect to the other driving stem. 
     FIG. 4 shows the assembly of the driving stems  10  and  12 . The length of both driving stems  10  and  12  can be varied according to specific requirement. Preferably, the driving stem  10  with a female joint is longer than the driving stem with a male joint. While assembling as shown in FIG. 4, for example, the driving stem  12  is approaching the driving stem  10  with the male joint towards the female joint along the direction of arrow  42 . Being engaged with the driving stem  10 , a roll pin  14  threads into the holes of the male and female joint to fasten the driving stems  10  and  12  to an extent that one of them can flip over the other. Radial compression of the roll pin while being inserted provides some rotational resistance to the rotating action. The direction to thread the roll pin  14  through both the driving stems  10  and  12  is illustrated as the arrow  41 . 
     FIG.  5 ( a ) to FIG.  6 ( e ) show another embodiment according to the invention. In FIG.  5 ( a ) to FIG.  5 ( e ), a driving stem with another type of male joint is illustrated, while in FIG.  6 ( a ) to FIG.  6 ( e ), a driving stem with another type of female joint is illustrated. In this embodiment, preferably, the driving stem with a male joint is shorter than the driving stem with a female joint. 
     FIG.  5 ( a ) and FIG.  5 ( b ) are a side view and front view of the driving stem with a male joint. In FIG.  5 ( a ), one end of the driving stem  52  comprises a male joint portion  54 . The male joint portion further comprises a base portion  54   a  extending from the main stem of the driving stem  52  with a curved bottom and a flat top. On top of the flat top of the base portion  54   a , there is a flat plate  54   b , and at the central portion of the flat plate  54   b , a fillet  54   c  stands out. The side view of such male joint portion  54  is shown in FIG.  5 ( b ). 
     A cross sectional view cutting along the line V—V is shown as FIG.  5 ( c ). The cross section of the main stem of the driving stem  52  is in a hexagonal shape with each side having a width of d and a cant of about 60 degrees. 
     A top view of the male joint portion  54  is shown as FIG.  5 ( d ). From the top view, the male joint portion  54  is like a circle that covers the whole cross section of the main stem. The thickness of the fillet  54   c  is approximately equal to d, and the width of the fillet  54   c , that is, the diameter of the male joint base portion  54   b  is substantially larger than {square root over (3)}d. 
     In addition, as shown in FIG.  5 ( e ), the edge  50  of the fillet  54   c  has been rounded. FIG.  6 ( a ) and FIG.  6 ( b ) are a side view and front view of the driving stem  62  with a female joint  64 . In FIG.  6 ( a ), one end of the driving stem  62  comprises a female joint portion  64 . The female joint portion further comprises a base portion  64   a  extending from the main stem of the driving stem  62  with a curve bottom and a flat top. Protruding from the cylindrical base portion  64 , there is a fork-like structure  64   b  that allows the fillet  54   c  of the driving stem  52  in FIG.  5 ( a ) to be engaged therein. The fork-like structure, as shown in FIG.  6 ( a ), comprises a slotted extension of the cylindrical base portion  64  with a rounded end as shown by FIG.  6 ( b ), thereby forming two prongs with flat machined interior faces and cylindrical curved outer surfaces as shown by FIGS.  6 ( a ) and  6 ( d ). 
     The side view of such female joint portion  64  is shown in FIG.  6 ( b ). A cross sectional view cutting along the line VI—VI is shown as FIG.  6 ( c ). The cross section of the main stem of the driving stem  62  is a hexagonal shape with each side having a width of d and a cant of about 60 degrees. A top view of the female joint portion  64  is shown as FIG.  6 ( d ). From the top view, space allowing the fillet  54   c  to be engaged therein has a thickness of approximately d, and the base section diameter of the female joint portion  64  is much larger than {square root over (3)}d with exact dimension based on strength calculations. 
     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.