Abstract:
An adjustable hex wrench structure, in its basic embodiment, requires only two parts: a main body configured with a socket cavity having special modified hex cross-sectional shape, and a user operable clamping screw, traversing a wall of the main body and preferably captivated against loss, with a special pressure disc surface for securing a hex fastener workpiece in place in the modified hex cavity operationally without defacing the workpiece. The main body is made cylindrical in shape and configured with a square driver opening to engage the square end of a conventional socket wrench driver shaft. In a dual socket wrench version, two different-sized modified hex cavities, one in each end portion of the main body, can provide an overall size range greater that 2:1, a single square driver opening being shared, configured in a central bulkhead in the main body: to deploy either cavity, the square end of the driver shaft can be inserted through the opposite cavity to engage the square driver opening in the known detented manner.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the field of hand tools and more particularly the field of hand-operated wrenches for driving hexagonal nuts and bolt-heads of various sizes, which conventionally requires large sets of graduated fixed-size sockets or box-end wrenches. The present invention discloses improvements in an adjustable socket wrench, previously patented by the present inventor, that can be readily adjusted to accommodate a wide range of sizes of hex fasteners, thus enabling a single unit to avoid the need for a substantial quantity of different sized fixed sockets or box-end wrenches. The improvements include novel structure in the adjustment screw for facilitating manual or tool-driven adjustment, for protecting the clamped facet of a hex fastener object against defacement, and for captivating the adjustment screw against removal and loss thru misplacement. 
       BACKGROUND OF THE INVENTION 
       [0002]    Conventional fixed wrenches, whether of the spanner, box-end or the socket type that snap onto a square driver shaft, have the disadvantage that a large number of different sized wrenches or sockets are required to cover a working size range of hex fasteners. For example in the inch system, the range from ⅜ to ¾ inches (0.375″ to 0.750″) requires seven sockets in steps of 1/16″ or thirteen sockets in steps of 1/32″; and, in the numbered metric system, the range from 10 mm to 20 mm (0.394″ to 0.787″) requires eleven sockets in steps of 1 mm. 
         [0003]    As substitutes for single or dual fixed spanner wrenches, adjustable spanners, including “monkey wrenches”, “vice grips” and pipe wrenches, have been well known and widely used for many years. However such adjustable spanners effectively engage only two of the six facets of hex fasteners and thus tend to fail and/or damage the fastener when high torque is required and applied, whereas conventional box-end or socket wrenches engage all six facets of the hex fastener, distributing the torque and associated forces more evenly, and are thus capable of higher torque with less likelihood of failure or fastener damage. 
         [0004]    As substitutes for single or dual fixed box-end wrenches, which engage all six facets of hex fasteners, socket wrench systems, wherein any of an assortment of sockets can be snapped onto the square end of a drive shaft driven by a ratchet handle, have become highly popular, especially to professional mechanics, for their convenience and versatility and are readily available either in individual pieces or in sets of various sizes required to accommodate a desired size range. However, the large number of pieces required is a disadvantage to many occasional users such as typical homeowners who may have only occasional need for a wrench but the required size is unpredictable. 
       DISCUSSION OF KNOWN ART 
       [0005]    U.S. Pat. No. 6,923,096 to the present inventor, Ee Jig Kim, for an ADJUSTABLE SOCKET WRENCH, discloses an adjustable box wrench structure with only two parts in its basic embodiment: a main body configured with a socket cavity having special modified hex cross-sectional shape that is asymmetric about one axis, and a user-actuated clamping screw, traversing a wall of the main body, for securing a hex fastener in place in the socket cavity. The present disclosure is directed to further improvements applicable to the adjustable socket wrench disclosed in the &#39;096 patent. 
         [0006]    U.S. Pat. No. 4,798,108 to Wilson for an ADJUSTABLE SOCKET-FORMING DEVICE discloses a hex socket wrench structure having a cylindrical main body, configured at one end with four facets of a hexagon, in which a radially sliding jaw member is configured in one end region with the other two facets of the hexagon while the opposite end region of the jaw member is threadedly engaged by a screw, radially traversing an opposite side of the main body in a mid region thereof, by which the jaw member can be tightened onto a hex fastener that is to be driven. 
         [0007]    U.S. Pat. No. 4,967,625 to Kolari &amp; Kolari discloses an ADJUSTABLE JAW SOCKET having a fixed jaw configured to grip a first adjacent pair of hex faces of a fastener and a slidingly-constrained worm-driven jaw configured to grip a second and opposite adjacent pair of hex faces of the fastener. 
         [0008]    Both of the above described devices have the disadvantage of complexity: requiring at least three separate parts of which two demand high precision machining to form complementary channels for accurately constraining the sliding movement. 
         [0009]    U.S. design Pat. 338,146 to Gramera shows an EQUILATERAL TORQUE DRIVE DOUBLE ENDED SOCKET WRENCH FOR HEXAGONAL FASTENERS of generally tubular shape having a central bulkhead configured with a square opening for engagement by a driver from either end, and also configured externally with a central hex collar as an alternative driving means. Two different sized sockets are provided, one at each end, each of generally triangular shaped for engaging three of the six sides of a hex fastener. This approach offers the advantage of simple one-piece construction with no moving parts, however, in tradeoff, the range of hex fastener sizes accommodated, while not specified in this design patent, appears to be limited to two sizes or, at most, two very narrow ranges. 
       OBJECTS OF THE INVENTION 
       [0010]    It is a primary object of the present invention to provide a simple, strong, compact and economical adjustable hex wrench structure that accommodates a predetermined size range of hex fasteners such as nuts and bolt heads, as an alternative to a graduated set of multiple fixed hex box-end or socket wrenches. 
         [0011]    It is a further object to provide an adjustable socket wrench embodiment for use with a conventional ratchet or fixed handle driver with a shaft having a square end for engaging the socket, typically retained by a spring-loaded-ball/groove type detent configuration. 
         [0012]    It is a further object to provide a user-operable clamping-adjustment member with special protective structure at the working end to avoid facet defacement of a driven hex fastener workpiece. 
         [0013]    It is a further object to configure the clamping-adjustment member in a manner to provide optimal thumb/finger gripping for manual operation for adjustment as well as providing options of driving the clamping-adjustment member with conventional screwdriver type tools. 
         [0014]    It is a further object to provide a dual embodiment of the adjustable socket wrench that accommodates all sizes of hex fasteners within a designated ratio of overall size range. 
       SUMMARY OF THE INVENTION 
       [0015]    The foregoing objects have been met in the present invention of an adjustable socket wrench, for driving hex fastener workpieces, which, in its basic embodiment, consists of only two main components: (1) a main body configured with a square driver socket to be driven from a conventional square driver, combined with a working socket cavity having a special modified hex cross-sectional shape characterized by asymmetry with two oversized facets flanking an undersized facet and (2) a clamping screw, constituting the clamping-adjustment member, threadedly engaged in a radial bore traversing a wall of the main body diametrically opposite the undersized facet. At its outer end, the clamping screw is configured with an annular drive wheel portion featuring a knurled surface around the outer circumference to enhance finger-gripping. At its inner end, the clamping screw is configured with a special smooth pressure disc surface, made and arranged to distribute adequate working pressure applied to the clamped facet of a hex fastener workpiece in a protective manner that avoids defacing the facet. 
         [0016]    The clamping screw is further configured at its outer end with a recessed drive pattern that accepts optional engagement of either a regular slot type or Philips type screwdriver. 
         [0017]    The adjustable socket wrench can be dimensioned to provide a range of about 1.7:1 so that two wrenches can be dimensioned with complementary ranges that will accommodate all hex fasteners sizes in a total range covering at least 3:1 ratio: e.g. 5/16 to 1 inch. 
         [0018]    In a single socket wrench unit, the square driver opening is located at an end of the unit. In dual socket wrench unit, the square driver unit is located in a central bulkhead between the two modified hex cavities, so that, whichever one of these two cavities is selected to drive a hex fastener workpiece, the square end of a conventional socket driver shaft can be inserted through the other modified hex cavity at the opposite end region of the dual unit and engaged into the square driver opening in the bulkhead to drive the adjustable socket in essentially the same manner as a conventional single fixed-size socket. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The above and further objects, features and advantages of the present invention will be more fully understood from the following description taken with the accompanying drawings in which: 
           [0020]      FIG. 1  is an elevational side view of an adjustable socket wrench in a preferred embodiment of the present invention. 
           [0021]      FIG. 2  is a top view of the socket wrench of  FIG. 1 . 
           [0022]      FIG. 3  is a bottom view of the socket wrench of  FIG. 1 . 
           [0023]      FIG. 4  is a cross-section taken through axis F 4 -F 4  of  FIG. 2 . 
           [0024]      FIG. 5  is a cross-section taken through axis F 5 -F 5  of  FIG. 1 . 
           [0025]      FIG. 6  is a cross-section taken through axis F 6 -F 6  of  FIG. 1 . 
           [0026]      FIG. 7  is a cross-section as in  FIG. 4  showing the pre-assembly condition of the clamping screw and the pressure disc. 
           [0027]      FIG. 8  depicts the tool-driving pattern configured at the outer end of the clamping screw of  FIGS. 1-7 . 
           [0028]      FIG. 9  depicts the geometric shape of the modified hex cavity in  FIGS. 2 ,  3 ,  5  and  6 . 
           [0029]      FIGS. 10-12  show a bottom view of the adjustable socket wrench of the present invention as in  FIG. 3 , shown here deployed and engaging hex fastener workpieces of maximum, medium and minimum size, respectively. 
           [0030]      FIG. 13  is a side view of a dual embodiment of the adjustable socket wrench of the present invention. 
           [0031]      FIG. 14  is a cross-section taken through the drive bulkhead at axis F 14 -F 14  of  FIG. 13 . 
           [0032]      FIG. 15  is a cross-section of the dual socket wrench of  FIG. 13  taken through central axis F 15 -F 15  of  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION 
       [0033]      FIG. 1  is an elevational side view of an adjustable socket wrench representing a preferred embodiment of the present invention wherein there are essentially two component parts: a cylindrical main body  10  into which is threaded a radially oriented clamping screw  12  configured at its outer end with a grip knob  12 A having an outer circumference that is preferably knurled as shown or otherwise configured to facilitate manual adjustment of the clamping screw  12 . The main body  10  and the clamping screw  12  are machined preferably from high grade tool steel. 
         [0034]      FIG. 2  is a top view of the socket wrench of  FIG. 1  showing the clamping screw  12  and a square drive socket opening  14  that accepts a conventional socket wrench driver shaft. 
         [0035]      FIG. 3  is a bottom view of the socket wrench of  FIG. 1  showing clamping screw  12  located radially and traversing the center facet of the three adjacent equal-sized facets of the modified hex cavity  16  that is unique to the present invention. At the inner end of clamping screw  12 , at the left side of modified hex cavity  16 , a circular pressure disc  12 B of clamping screw  12  provides a lateral clamping surface. The square drive socket opening  14  appears in the background. 
         [0036]      FIG. 4  is a cross-section of  FIG. 1  taken at axis F 4 -F 4  of  FIG. 2  (center of clamping screw  12 ), showing, in the upper part of main body  10 , the square driver socket opening  14  configured with grooves  14 A that are provided across each of the four walls to engage a spring-loaded ball in the driver and thus provide the well-known detented retension of the socket wrench on the driver shaft. Pressure disc  12 B is seen configured with a central stud  12 B′ by which it is retained in a boring at the inner end of clamping screw  12 . 
         [0037]      FIG. 5  is a cross-section of  FIG. 3  taken through axis F 5 -F 5  of  FIG. 1 , showing the upper part of the main body  10  surrounding the square drive socket opening  14 , with clamping screw  12  showing in the background. 
         [0038]      FIG. 6  is a cross-section of  FIG. 3  taken through axis F 6 -F 6  of  FIG. 1  at the center of clamping screw  12 , shown traversing the main body  10  at the central one of three equal facets of the modified hex cavity  16 . The square drive socket opening  14  appears in the background. 
         [0039]      FIG. 7  is a cross-section as in  FIG. 4  showing the pre-assembly production condition of the clamping screw  12  threaded through main body  10  and entering the modified hex cavity  16 , where the pressure disc  12 B is positioned ready to be assembled together with clamping screw  12 . In this process, stud  12 B′ extending from the rear side of pressure disc  12 B is inserted into boring  12 D of the clamping screw  12  and pressed into place as shown in  FIGS. 4 and 6 , with optional bonding or adhesives. Once joined together, the two pieces are intended to remain assembled permanently and to function equivalent to a single integrated part. 
         [0040]    Pressure disc  12 B is made at least as large in diameter as the outside diameter of clamping screw  12  so to enhance the distribution of clamp pressure to avoid defacing the facet of a hex fastener being clamped in deployment of the socket wrench. Furthermore, such dimensioning of pressure disc  12 B serves to retain the clamping screw  12  captive in the main body  10 , preventing removal and possible misplacement/loss of clamping screw There is an option of forming the pressure disc  12 B integrally with clamping screw  12  and, at the outer end, making the grip knob small enough in diameter to clear the threads or else removably attached so that in manufacture the clamping screw  12 , with the disadvantages of having to be made sufficiently short and having to be installed from inside the modified hex cavity  16 . 
         [0041]      FIG. 8  depicts the tool-driving pattern  12 C configured at the outer end of the clamping screw  12  of  FIGS. 1-6 , provided as an option to manual clamping adjustment and enabling the use of either a regular blade screwdriver or a Philips driver. Another option is to provide a hex opening for an Allen type driver. As an option for manual operation instead of the knurled knob, the clamping screw could be configured with a transverse bar or other form of thumb-finger grip. 
         [0042]      FIG. 9  depicts the geometric shape of the modified hex cavity shown in  FIGS. 2 ,  3 ,  5  and  6  as the key feature of the adjustable hex socket wrench of the present invention. As in a regular equilateral hex pattern, all six angles a in the modified hex pattern are 120 degrees as indicated. However, in the pattern of the modified hex cavity  16 , in a departure from a regular equilateral hexagon with six equal-sized facets, the pattern of the modified hex cavity  16  is characterized by three of the six facets, marked A on the left hand side as shown, being made equal, having in common the regular standard dimension, while on the right hand side there are three non-standard-sized facets: two non-adjacent facets marked B that are larger than standard A, flanking the third facet marked C that is smaller than standard A. 
         [0043]    The standard facet width A sets the maximum size hex fastener that can be accommodated; the smallest facet width C sets the minimum size, at which the fastener may be engaged by a 3 facet constraint pattern in the main body. Thus the range of fastener sizes that can be accommodated in one modified hex socket cavity is the ratio A/C (&gt;1). 
         [0044]    From trigonometry, in a regular hex fastener of size D (distance between parallel facets) each facet width A=D/(2*cos 30) i.e. D*0.57735; in the modified hex shape of this invention, once C is designated to set the range, B can be calculated: B=2*A−C. 
         [0045]    In a particular embodiment that accommodates hex fasteners throughout a size range from 5/16″ to ⅝″, i.e. 2:1 ratio, the three equal facets A are made 0.478″ wide, and the small facet C is made 289″. The main body  10  is made 1.25″ in diameter and the clamping screw is made 0.5″ in outer diameter with 13 threads per inch. 
         [0046]      FIGS. 10-12  show a bottom view of main body  10  of the adjustable socket wrench of the present invention as in  FIG. 3 , showing how the modified hex cavity  16  and clamping screw  12  are deployed to accommodate hex fasteners  18 A,  18 B and  18 C of maximum, medium and minimum size, respectively. 
         [0047]      FIG. 13  is an elevational side view of a dual adjustable wrench  18  representing a particular embodiment of the present invention. A generally cylindrical main body  18  with a tapered central step contains two different sized adjustable wrenches: a larger upper portion  18 A and smaller lower portion  18 B, each with an associated clamping screw and a modified hex cavity, scaled in size accordingly, but otherwise configured as described above for a single unit adjustable wrench. 
         [0048]      FIG. 14  is a cross-section taken through the drive bulkhead  20  at axis F 14 -F 14  of  FIG. 13  in the tapered region, showing the bulkhead  20  traversed by the square socket drive opening  14  which is shared by the two adjustable wrench units. Whichever one of the two units is deployed, the socket drive shaft is inserted through the opposite modified hex cavity and into the square socket drive opening  14 . As described above for the single embodiment, a set of grooves configured centrally in the four walls of the square opening  14  serve to provide retention by engaging the well-known spring-loaded ball detent of the conventional socket drive shaft which can be inserted and operated from either direction, 
         [0049]      FIG. 15 , a cross-section of the dual socket wrench  18  of  FIG. 13  taken through central axis F 15 -F 15  of  FIG. 14 , shows the larger modified hex cavity region of the upper portion  18 A and the smaller modified hex cavity region of the lower portion  18 B, each equipped with a corresponding clamping screw as described above. The two cavity regions are separated by bulkhead  20  which is seen configured with the square drive opening  14  and its detent grooves. 
         [0050]    For dual adjustable wrench embodiments, the size ranges of the two modified hex cavities would normally be made complementary to maximize the continuous overall hex fastener size range: thus for a size range ratio D 1 /D 2  in the larger socket cavity, the size range ratio for the smaller socket cavity is made to be D 2 /D 3  for a total range ratio D 1 /D 3 . Size D 2  is termed the crossover size, being at the low end of the higher range and at the high end of the lower range. 
         [0051]    In an exemplary embodiment, the upper portion  18 A is made 1.5″ in diameter and the lower portion  18 B is made 1.1″ in diameter. The square drive opening  14  is typically made in either of two popular sizes: ½ inch or ⅜ inch per side, depending on the wrench size. 
         [0052]    Although the illustrative embodiment is arranged and dimensioned as described, the invention can be practiced in any size with dimensional variations as matters of design choice, by allowing acceptable amounts of variations in the cavity size ratio and the facet size ratios in each modified hex cavity. 
         [0053]    Optionally the taper in the exterior region between portions  18 A and  18   b  could be eliminated to make the outer surface fully cylindrical. 
         [0054]    The general proportions can be altered, for example the outer diameter can be increased to provide increased wall thickness around the cavities, which would increase the ultimate strength. 
         [0055]    The invention could be practiced with different types and sizes of driving system as alternative to the square drive opening  14 . The shape could be made rectangular, triangular, hex or other driving shape to match a complementary driver, as a matter of design choice. Instead of rotational drive via an internal driving opening as described, the adjustable socket wrench could be driven externally by a ratchet mechanism or a gripping device such as a pipe wrench or a self-clamping wrench of the type utilized for installing and removing cylindrical oil filters. Alternatively, the exterior could be configured with a square, hex or other pattern to be engaged for rotation by a corresponding wrench type. 
         [0056]    As alternatives to the shaft-driven socket wrench type embodiments described, the modified hex shape of the socket cavity and the clamping screw, as principles of the present invention, can be practiced in the form of a box-end style wrench by the addition of a driving handle extending radially from the cylindrical main body, forming in effect a box-end wrench style which may be implemented with one or two adjustable sockets. A double-ended version of the box-end wrench can be made by incorporating two cylindrical main bodies, one at each end of a handle. Each main body can be made with one or two adjustable sockets, thus a double-ended box-end wrench can be made with a total of two, three or four adjustable sockets of the present invention, providing expanded overall hex size ranges accordingly. 
         [0057]    The invention may be embodied and practiced in other specific forms without departing from the spirit and essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description; and all variations, substitutions and changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.