Abstract:
A retractable open-end wrench has a handle defining a web at one end thereof. A stationary jaw projects from a first side of the web, and a first channel is formed at a second side of the web opposite the first side, the first channel being defined by a first arc. A moveable jaw is received by the first channel and moves linearly through the first channel, wherein the jaws form an open end therebetween. A second channel formed in the movable jaw is defined by a second arc, wherein a length of the first arc is greater than a length of the second arc. Moreover, a first radius of the first arc is smaller than a second radius of the second arc, and the first channel and the second channel form a receiving hole.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of Invention  
         [0002]     This invention relates to a wrench, particularly to a retractable open-end wrench allowing itself to recover to an orientation to facilitate further rotation without repeatedly drawing up and fitting itself onto a bolt or nut.  
         [0003]     2. Description of the Related Art  
         [0004]     Conventional wrenches for tightening or loosening bolts or nuts include locking and non-locking types in which the non-locking types allow for use with various sizes of bolts or nuts by adjusting an adjustment rack.  
         [0005]     Regardless of being a locking type or a non-locking type wrench, a user must remove the jaws of the wrench from the bolt after the bolt or nut is tightened or loosened upon rotating the wrench over a certain angle in a tightening or loosening direction, recovering the wrench to an orientation facilitating further rotation under a state that the jaws disengage from the bolt or nut, and then fitting the jaws onto the bolt or nut to perform a subsequently tightening or loosening operation. Such operations must be repeated until the bolt or nut is completely tightened or loosened.  
         [0006]     Removing and repositioning the wrench causes inconvenience for the user and requires additional space to accommodate the operation for removing the wrench from the bolt or nut for recovering the wrench to an orientation facilitating further rotation under a state that the jaws disengage from the bolt or nut.  
         [0007]     To resolve such problems, U.S. Pat. No. 4,437,364 discloses a wrench allowing linear movement of a movable jaw of the wrench with respect to the web to increase a gap of the wrench. However, in such a conventional wrench, because the receiving hole facilitating linear movement of the movable jaw is formed on the web, a driller or a lathe must be implemented to drill a hole in the web, followed by a milling machine to mill a slot along a lateral face of the web in communication with the drill hole. The above manufacturing process requires the use of several machining equipment and creates problems in tapping and deburring the hole, particularly for small-size wrenches.  
       SUMMARY OF THE INVENTION  
       [0008]     It is a primary objective of this invention to provide a retractable open-end wrench allowing easy manufacturing and deburring to reduce the manufacturing costs and lead-time.  
         [0009]     It is further objective of this invention to provide a retractable open-end wrench allowing quick retraction of the wrench to an orientation facilitating further rotation without repeatedly drawing up the wrench.  
         [0010]     It is further objective of this invention to provide a retractable open-end wrench allowing tightening or loosening a fastener without repeatedly fitting the wrench onto a bolt or nut.  
         [0011]     To achieve the above objectives, the invention provides a retractable open-end wrench having: a web, a stationary jaw projecting from a side of the web, a movable jaw provided at another side of the web and forming an open end of a predetermined gap with the stationary jaw. The web is formed with a lower channel in operative engagement with the movable jaw, the lower channel having a major arc cross-section. The movable jaw is formed with an upper channel proximate the web, the upper channel having a minor arc cross-section having a radius slightly greater than a radius of the major arc. The upper channel and the lower channel jointly construct a receiving hole. A post projects from the movable jaw proximate the upper channel, the post having a cross-section corresponding to the cross-section of the lower channel to allow linear movement along the lower channel. A resilient member such as a spring is received in the receiving hole, the spring subjecting the post of the movable jaw to normally urge against the web and allowing linear movement of the movable jaw with respect to the web to thereby increase the predetermined gap.  
         [0012]     According to another aspect of this invention, the retractable open-end wrench has a locking device such as a plug for retaining the spring in the receiving hole.  
         [0013]     According to another aspect of this invention, the lower channel is formed with a plurality of threads at a distant end thereof for retaining the plug in the receiving hole.  
         [0014]     According to another aspect of this invention, the spring is a compression spring provided between the post and the plug, or a tension spring provided between the post and the web.  
         [0015]     According to another aspect of this invention, the retractable open-end wrench has a plug that is press-fitted in the receiving hole.  
         [0016]     The structures and characteristics of this invention can be realized by referring to the appended drawings and explanations of the embodiments. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is an exploded, perspective view of a retractable open-end wrench according to an embodiment of this invention.  
         [0018]      FIG. 1 ( a ) is a cross-sectional view illustrating a receiving hole for receiving a post in the wrench of  FIG. 1 .  
         [0019]      FIG. 1 ( b ) is a cross-sectional view illustrating a locking device being inserted in the receiving hole of  FIG. 1 ( a ).  
         [0020]      FIG. 2  is an assembled, perspective view of the retractable open-end wrench of  FIG. 1 .  
         [0021]     FIGS.  3 ( a ) to  3 ( b ) are schematic views illustrating the operations for retracting the retractable open-end wrench of  FIG. 1  to an orientation facilitating tightening.  
         [0022]     FIGS.  3 ( c ) to  3 ( e ) are schematic views illustrating the operations for tightening a bolt.  
         [0023]     FIGS.  4 ( a ) to  4 ( c ) are schematic views illustrating the operations for retracting the retractable open-end wrench of  FIG. 1  to an orientation facilitating loosening.  
         [0024]     FIGS.  4 ( d ) to  4 ( e ) are schematic views illustrating the operations for loosening a bolt. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]      FIGS. 1 and 2  illustrate perspective views of a retractable open-end wrench  10  according to this invention. Wrench  10  comprises a web  12 , a stationary jaw  14  projecting from a side of web  12 , a movable jaw  16  provided at an opposite side of web  12  and forming an open end of a predetermined gap G with stationary jaw  14 . Gap G preferably adapts to a width of a head of bolt or nut flats to which wrench  10  is designed to apply. For example, if the fastener has a hexagonal head, gap G is about the distance formed by two opposing, parallel flats of the head.  
         [0026]     With reference to  FIG. 1 , web  12  is formed with a lower channel  122  at a location joining movable jaw  16  to allow for linear and resilient movement of movable jaw  16  with respect to web  12 . Movable jaw  16  is formed with an upper channel  161  at location where jaw  16  joins with web  12 . A post  162  projects from movable jaw  16  proximate upper channel  161 .  
         [0027]     With reference to  FIG. 1 ( a ), lower channel  122  has a major arc cross-section defined by an arc that exceeds a semi-circle (180 degrees), such as the ⅔ circle illustrated in  FIG. 1 ( a ).  
         [0028]     Upper channel  161  has a minor arc cross-section, such as the ⅓ circle illustrated in  FIG. 1 ( a ), and defines an arcuate shaped post  162  extending from the minor arc cross-section.  
         [0029]     Preferably, the minor arc has a radius slightly greater than a radius of the major arc. Upper channel  161  and lower channel  122  jointly construct a receiving hole H. Post  162  has a cross-section corresponding to the cross-section of lower channel  122 . Because post  162  has a cross-section corresponding to the cross-section of lower channel  122 , in installing movable jaw  16 , post  162  is slid along and inserted into lower channel  122 . Movable jaw  16  in this arrangement will not be separated from lower channel  122 , and such an arrangement allows linear movement of movable jaw  16  along lower channel  122 .  
         [0030]     A resilient member  18  is received in receiving hole H. Resilient member  18  biases moveable jaw post  162  away from web  12  to thereby increase predetermined gap G. To allow easy retention of resilient member  18  in receiving hole H, according to the embodiment illustrated in  FIGS. 1 and 2 , a locking device  19  may be used to retain resilient member  18  in receiving hole H. Locking device  19  may be a bolt, plug or any other suitable device for sealing resilient member  18  in hole H. According to one embodiment of this invention, locking device  19  is a plug that is press-fit and secured into receiving hole H.  
         [0031]     Lower channel  122  may alternatively be formed with a plurality of threads  123  at a distant end thereof for securing locking device  19  into receiving hole H, which is jointly constructed by upper channel  161  and lower channel  122 . In this embodiment, post  162  includes a diameter that is substantially equivalent to the crest diameter of threads  123  in lower channel  122  to allow linear movement of post  162  along lower channel  122 .  
         [0032]     According to another embodiment of this invention, locking device  19  may also be designed to be a plug including an indent at an end thereof (FIGS.  3 ( a )- 4 ( e )) for receiving resilient member  18  therein, which plug may then be press-fit into the receiving hole H. The resilient member  18  may alternatively be assembled to locking device  19  to construct a single unit prior to being press-fit rotated into receiving hole H.  
         [0033]     If resilient member  18  is provided between post  162  and locking device  19  ( FIG. 1 ), resilient member  18  may be a compression spring. If, however, resilient member  18  is alternatively provided between post  162  and web  12  (not shown), then resilient member  18  may be a tension spring. As such, post  162  is normally urged against web  12  by the resilience provided by resilient member  18 .  
         [0034]     The open end of wrench  10  may be designed to adapt to fasteners having heads of various configurations.  FIGS. 1 and 2  illustrate an example adapted to a hexagonal head. The open end may be designed to adapt to other fasteners having square, polygonal, star-shaped, or even smooth cylindrical configuration by modifying the profile of the open end. As exemplified by an open end adapted to a fastener having a hexagonal head, the profile of the open end may be a lower half of an equilateral hexagon, or a lower half of a configuration constructed by interlacing two or more concentric equilateral hexagons, such as that shown in  FIGS. 1 and 2 . The profile of the open end adapted to a fastener having a cylindrical head may be a lower half of a circle, that to a triangular head may be a lower half of an equilateral triangle or a lower half of a configuration constructed by interlacing two or more concentric equilateral triangles, and that to a square head may be a lower half of a square or a lower half of a configuration constructed by interlacing two or more concentric squares.  
         [0035]     The operations of the retractable open-end wrench  10  of this invention are illustrated in FIGS.  3 ( a )- 3 ( e ) and FIGS.  4 ( a )- 4 ( e ). FIGS.  3 ( a ) to  3 ( c ) are schematic views illustrating the operations for retracting the retractable open-end wrench to an orientation facilitating tightening.  FIG. 3 ( a ) illustrates a state in which a hexagonal bolt  50 , which fits in the open end of retractable open-end wrench  10 , has been tightened by a user to an orientation that is inconvenient for further rotation. At this point, the user may rotate web  12  of the wrench  10  in a reverse direction as shown in  FIG. 3 ( b ). Because the profile of the open end formed on movable jaw  16  is restrained by bolt  50  having a cooperative profile, post  162  projecting from movable jaw  16  is forced to move along an axis of receiving hole H jointly constructed by lower channel  122  and upper channel  161 , to thereby increase predetermined gap G due to resilient movement of movable jaw  16  with respect to stationary jaw  14 , so as to allow wrench  10  to rotate in a reverse direction under a state that wrench  10  is not removed from bolt  50 .  
         [0036]     Once wrench  10  reaches a position as shown in  FIG. 3 ( c ), wrench  10  begins to recover to an orientation facilitating further rotation and the user can at this time slightly release wrench  10  whereby movable jaw  16  approaches stationary jaw  14  due to resilient member  18  and returns to predetermined gap G, as shown in  FIG. 3 ( d ). At this time, the user can again rotate web  12  towards a direction for tightening bolt  50  to the position shown in  FIG. 3 ( e ).  
         [0037]     Because post  162  of movable jaw  16  happens to urge against web  12  at this time, movable jaw  16  and stationary jaw  14  can jointly drive bolt  50  to rotate towards the tightening direction. The operations illustrated in FIGS.  3 ( a ) to  3 ( d ) may be repeated until the bolt or nut is completely tightened.  
         [0038]     With reference to  FIG. 1 ( b ), because the radius of upper channel  161  is slightly greater than the radius of lower channel  122 , a slash S is formed between upper channel  161  and locking device  19 . As such, when post  162  slides along lower channel  122 , locking device  19  does not limit the movement of channel  161  or interferes with the linear movement of movable jaw  16 .  
         [0039]     FIGS.  4 ( a ) to  4 ( c ) are schematic views illustrating the operations for retracting the retractable open-end wrench to an orientation facilitating loosening.  FIG. 4 ( a ) illustrates a state in which hexagonal bolt  50  fits in the open end of retractable open-end wrench  10  and has been loosened by a user to an orientation that is inconvenient for further rotation. At this point, the user may rotate wrench web  12  in a reverse direction as shown in  FIG. 4 ( b ). Because the profile of the open end formed on movable jaw  16  is restrained by bolt  50  having a cooperative profile, movable jaw  16  is forced to move along an axis of the receiving hole H against the bias of resilient member  18  to thereby increase the predetermined gap G due to movement of movable jaw  16  with respect to stationary jaw  14 . Thus, wrench  10  rotates in a reverse direction under a state that wrench  10  is not removed from bolt  50 . The user continues rotating wrench web  12  in a reverse direction until reaching the position shown in  FIG. 4 ( c ). Once the configuration of bolt  50  happens to again adapt to the profile of the open end of wrench  10 , wrench  10  recovers to an orientation facilitating further rotation as shown in  FIG. 4 ( d ). In this position, the user can slightly release wrench  10  whereby movable jaw  16  approaches stationary jaw  14  due to resilient member  18  and returns to assume the predetermined gap G with stationary jaw  14 , as shown in  FIG. 4 ( d ). At this time, the user can again rotate web  12  towards a direction for loosening bolt  50  to the position shown in  FIG. 4 ( e ). Because moveable jaw post  162  is biased against web  12  in this position, movable jaw  16  and stationary jaw  14  can jointly drive bolt  50  in the loosening direction. The operations illustrated in FIGS.  4 ( a ) to  4 ( d ) may be repeated until the bolt or nut is completely loosened.  
         [0040]     Because receiving hole H is jointly constructed by (1) lower channel  122  formed in web  12  that has a major arc cross-section and (2) upper channel  161  formed on movable jaw  16  that has a minor arc cross-section, in manufacturing the wrench only a driller is required to drill partially circular holes along lateral faces of web  12  and movable jaw  16  without the need to use milling machines. Such open, partially circular holes also facilitate deburring of the upper  161  and lower  122  channels that are machined to wrenches of different sizes. Thus, the wrench design of the present invention allow for easy manufacturing and deburring procedures to reduce the manufacturing costs and lead time.  
         [0041]     Furthermore, in using retractable open-end wrench  10  of this invention, the user may quickly retract wrench  10  to an orientation facilitating further rotation without repeatedly removing the wrench. Thus, the present invention provides a retractable open-end wrench that allows for quick retraction of the wrench to an orientation facilitating further rotation and allowing tightening or loosening a fastener without repeatedly removing the wrench and fitting the wrench onto bolt  50 .  
         [0042]     This invention is related to a novel creation that makes a breakthrough in the art. Aforementioned explanations, however, are directed to the description of preferred embodiments according to this invention. Various changes and implementations can be made by persons skilled in the art without departing from the technical concept of this invention. Since this invention is not limited to the specific details described in connection with the preferred embodiments, changes to certain features of the preferred embodiments without altering the overall basic function of the invention are contemplated within the scope of the appended claims.