Patent Publication Number: US-8117948-B2

Title: Wrench

Description:
FIELD OF THE INVENTION 
     The invention relates to wrenches (known in the United Kingdom as spanners). 
     BACKGROUND TO THE INVENTION 
     A wrench is a tool for applying torque to fasteners, such as nuts and bolts, for the purpose of tightening or slackening the fastener. In general, wrenches are designed to be used on fasteners that have a polygonal drive receiving portion comprising a number of generally flat drive receiving surfaces. The head portion of an open ended wrench comprises an open-sided fastener receiving aperture having a pair of opposed fastener engaging surfaces that are spaced apart by a distance corresponding to the size of fastener they are designed to be used on. Ring wrenches have a generally circular head portion that defines a closed fastener receiving aperture. The internal surface defining the aperture is shaped to engage the type and size of fastener it is designed to be used on. 
     Particularly in cases in which high levels of torque need to be applied to a fastener, a ring wrench is the better tool. An open ended wrench only has two torque applying surfaces and, particularly when high levels of torque are being applied, they can easily slip off of the fastener. This usually results in damage to the fastener. Specifically, the corners formed where adjacent drive receiving surfaces meet are rounded off making it more difficult for the wrench to successfully apply high levels of torque to the fastener. Ultimately, the damage can effectively round off the fastener drive receiving surfaces to the extent a conventional wrench can no longer successfully operate the fastener. This is a particular problem where the fastener is in place and the user of the wrench is trying to loosen it. 
     Ring wrenches have the same number of fastener engaging surfaces as the fastener has drive receiving surfaces. With ring wrenches, because the fastener receiving aperture is closed there is no danger of the tool slipping off of the fastener and because the applied torque is distributed more evenly around the fastener, it is less likely high levels of applied torque will result in the corners of the fastener being rounded off. Unfortunately, there are many applications for which a ring wrench cannot be used. For example, where a nut is located on a pipe, it is not possible to fit a ring wrench over the pipe and so an open ended wrench has to be used. 
     The nut that secures a brake pipe to brake unit on an automobile is one example of a fastener that has to be worked on with an open ended wrench. Because of their position on the vehicle, these nuts are exposed to all of the adverse weather and other environmental conditions to which a vehicle is exposed. They are also relatively small in size and so in the circumferential direction of the nut, the drive receiving surfaces are relatively short. The result is that relatively high levels of torque are needed to release them. Often when such levels of torque are applied, the wrench head portion slips off rounding off the corners of the nut. This problem is often exacerbated by the location of the nut, which is typically such that only one or two pairs of drive receiving surfaces are accessible. Once the corners of those drive receiving surfaces have been wrung off, it is not usually possible to loosen the nut with a conventional open ended wrench. 
     SUMMARY OF THE INVENTION 
     The invention provides a wrench comprising a handle portion, a head portion releasably secured to the handle portion and a release device, the head portion having an inner surface that defines a fastener receiving aperture having a plurality of fastener engaging surfaces and a side entry to said fastener receiving aperture and being movable relative to the handle portion between a loading position in which the side entry is open to permit an elongate member attached to a fastener to be moved into said fastener receiving aperture to permit said fastener engaging surfaces to be moved into engagement with the fastener by relative movement of the head portion and fastener in a lengthways direction of the elongate member and an operating position in which said side entry is closed and the head portion is operable to close said fastener engaging surfaces around the fastener received in said fastener receiving aperture in response to a torque applied in a predetermined direction using said handle portion, and said release device bring arranged to at least assist in releasing the head portion from the handle portion to permit the head portion to be separated from the handle portion. 
     The invention includes a wrench comprising: 
     a handle; 
     a socket head having an inner surface that defines a fastener receiving aperture having a plurality of fastener engaging surfaces and a side entry to said fastener receiving aperture through which an elongate member attached to a fastener can be inserted into said fastener receiving aperture to permit said fastener engaging surfaces to be moved into engagement with the fastener by relative movement in a lengthways direction of the elongate member, said socket head being pivotably connected to said handle so as to be pivotable to positions in which it extends transversely to said handle to permit access to said side entry and a position generally in line with said handle in which entry to said side entry is blocked and being operable to close said fastener engaging surfaces around a fastener received in said fastener receiving aperture in response to a torque applied in a predetermined direction using said handle; and 
     a force applying device arranged to apply a force to the socket head to release the socket head from said pivotable connection to allow the socket head to be separated from the handle. 
     The invention also includes a method of operating a wrench for applying a torque to a fastener attached to an elongate member, the method comprising: 
     causing relative movement of a head portion of a wrench and the elongate member such that the elongate member passes through a side entry to a fastener receiving aperture defined by the head portion and is received in the fastener receiving aperture; 
     causing relative movement of the head portion and elongate member in a lengthways direction of the elongate member to bring the fastener into the fastener receiving aperture; 
     releasably connecting a handle portion of the wrench to the head portion; and applying a torque to said handle portion in a predetermined direction to close the fastener receiving aperture around the fastener so as to engage the fastener and apply a torque thereto. 
     The invention also includes a wrench comprising a handle portion and a head portion, the head portion being movably connected with said handle portion so as to be movable relative to the handle portion between a storage position in which it is at least partially received within said handle portion and use positions in which it projects from the handle portion, the head portion having an inner surface that defines a fastener receiving aperture having a plurality of fastener engaging surfaces and a side entry to said fastener receiving aperture through which an elongate member attached to a fastener can be inserted into said fastener receiving aperture to permit said fastener engaging surfaces to be moved into engagement with the fastener by a movement in a lengthways direction of the elongate member and being operable to close said fastener engaging surfaces around a fastener received in said fastener receiving aperture in response to a torque applied in a predetermined direction using said handle portion. 
     The invention also includes a wrench comprising a handle portion and a head portion, the head portion having an outer side surface and an inner surface that defines a fastener receiving aperture that has a plurality of fastener engaging surfaces and being operable to close said fastener engaging surfaces around a fastener received in said fastener receiving aperture in response to a torque applied in a predetermined direction using said handle portion, said outer side surface having a plurality of concave portions, each of which is disposed generally opposite a said fastener engaging surface. 
     The invention also includes a wrench comprising a handle portion and a head portion, the head portion having an inner surface that defines a fastener receiving aperture that has a plurality of fastener engaging surfaces and being operable to close said fastener engaging surfaces around a fastener received in said fastener receiving aperture in response to a torque applied in a predetermined direction using said handle portion, at least some of said fastener engaging surfaces being provided on a portion of said head portion that comprises a series of alternately oppositely facing generally C-shaped sections arranged end to end and forming an outer end of the head portion. 
     The invention also includes a method of operating a wrench for applying a torque to a fastener attached to an elongate member, the method comprising: 
     moving a head portion of the wrench relative to a handle portion of the wrench to a position at which a side entry to a fastener receiving aperture defined by the head portion is open; 
     causing relative movement of the wrench and the elongate member such that the elongate member passes through the side entry and into the fastener receiving aperture, 
     causing relative movement of the wrench and elongate member in a lengthways direction of the elongate member to bring the fastener into the fastener receiving aperture; and applying a torque to said handle portion in a predetermined direction to close the fastener receiving aperture around the fastener so as to engage the fastener and apply a torque thereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the invention may be well understood, an embodiment thereof, which is given by way of example only, will now be described with reference to the drawings in which: 
         FIG. 1  is a perspective view showing a wrench; 
         FIG. 2  shows the head portion of the wrench of  FIG. 1 ; 
         FIG. 3  shows the wrench engaging a nut and with a plate of the handle portion removed to show the layout of the interior of the handle; 
         FIG. 4  is a view corresponding to  FIG. 3  but showing the wrench in an open condition; 
         FIG. 5  is a perspective view showing the wrench in an open condition prior to engaging a nut on a brake line; and 
         FIG. 6  is a perspective view showing the wrench in position on the nut on the brake line. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
     Referring to  FIGS. 1 to 4 , a wrench  10  comprises a handle portion  12  and a removable head portion  14 . The handle portion  12  comprises a pair of elongate plate members  16 ,  18 . The plate members  16 ,  18  are secured to one another by rivets  20 - 28  that are arranged to maintain the plate members in parallel spaced apart relation such that there is a gap  30  defined between them. The plate members  16 ,  18  have a peripheral contour shaped to make the handle portion  12  easy to grip in the hand. Optionally, at least one of the plate members  16 ,  18  is provided with a polygonal aperture  32  shaped and sized to engage a standard size fastener head. The plate members  16 ,  18  may be provided with respective different sized apertures  32  or only one of the plate members may be provided with an aperture  32 . However, having the same size and shape of aperture in each plate member simplifies production. 
     The head portion  14  is a generally U-shaped member comprising elongate leg portions  34 ,  36  interconnected at one end by an arcuate portion  38 . The leg portion  34  is longer than the leg portion  36  and has a semi-circular recess  40  provided at its free end. The leg portion  36  has a notch  42  provided in the outer side  44  of its free end. As best seen in  FIGS. 2 and 4 , the inner side of the arcuate portion  38  defines five fastener engaging surfaces  46 . Adjacent ones of the fastener engaging surfaces  46  are interconnected by concave surface portions  48  such that they define a generally polygonal fastener receiving aperture  50  with the concave surface portions forming the corners of the aperture. The aperture  50  is shaped and sized to correspond to the fasteners the wrench is designed to be used on. The leg portions  34 ,  36  are spaced apart to define an elongate passage  52  that has an outer end  54  at the free ends of the leg portions and extends from the outer end to the aperture  50 . 
     The fastener engaging surfaces  46  are flat surfaces angled so as to be able to engage respective drive receiving flat surfaces of the size and shape of fastener the head portion  14  is intended to operate. As best seen in  FIG. 3 , the fastener engaging surfaces  46  and concave surface portions  48  are arranged such that the fastener engaging surfaces engage the leading ends of the respective fastener flats in the torque applying direction of the wrench (i.e. the anticlockwise direction as viewed in  FIG. 3 ) and the concave surface portions are located over the trailing end portion of the fastener flats at which the application of torque is not required. 
     The outer side surface of the arcuate portion  38  has a number of concave portions  56  that are disposed generally opposite a respective fastener engaging surface  46 . Specifically, there are concave portions  56  disposed generally opposite the three fastener engaging surfaces  46  at the end of the head portion  14 . There are also concavities  58  in the outside surface of each of the leg portions  34 ,  36  behind (i.e. generally opposite) the fastener engaging surfaces  46  immediately adjacent the passage  52 . The effect of the convex fastener engaging surfaces  46 , concave surface portions  48 , concave portions  56  and concavities  58  is to divide the part of the head portion  14  that defines the fastener receiving apertures  50  into a series of alternating oppositely facing generally C-shaped portions that provide a corrugated effect. It has been found that the structure resulting from this configuration provides flexibility in the fastener receiving aperture shape that can provide adjustability for adjusting to grip misshapen and damaged fasteners coupled with sufficient strength to operate tight fasteners. The concave surface portions  48  define the corners of the polygonal fastener receiving aperture  50  and act in the manner of a curved spring hinge. It will be appreciated that the curvature of the concave surface portions  48  allows the hinge-like action and avoids the problem of stress concentration that would arise if sharp corners were used. 
     The rivets  20 ,  22 ,  24 ,  26  are positioned and shaped such that they also serve as posts that in use of the wrench  10  are engaged by the head portion  14 . As shown in  FIGS. 3 and 4 , the semi-circular recess  40  of the leg portion  34  engages the rivet  24 , which serves as a mount on which the head portion  14  can pivot between the open and closed positions shown. When the handle portion  12  is pivoted anticlockwise from the position shown in  FIG. 4  to close the wrench (the position shown in  FIG. 3 ), the notch  42  in the end of the leg portion  36  engages the rivet  20 . As will be described in more detail below, continued anticlockwise rotation of the handle portion  12  drives the rivet  20  into the notch  42  such that a bending moment is applied to the leg portion  36  to cause the fastener engaging surfaces  46  to close around a fastener received in the fastener receiving aperture  50 . 
     The rivet  22  is positioned between the rivets  20 ,  24  such that it provides an abutment that limits movement of the free end of the leg portion  36  towards the leg portion  34 . This prevents excessive deformation of the head portion  14 . In some orientations of the head portion  14 , the rivet  22  also assists in keeping the recess  40  engaged with the rivet  24 . 
     As can be seen in  FIG. 4 , if the head portion  14  is pivoted far enough in the anticlockwise direction, the outer side surface  56  of the leg portion  34  engages the rivet  26  close to semi-circular recess  40 . If rotation of the head portion  14  is continued, the side surface  56  presses against the rivet  26 , causing the head portion to pivot about the rivet  26  and forcing the semi-circular recess  40  to disengage from the rivet  24 . This makes it easy to disengage and remove the head portion  14  from the handle portion  12 . 
     Use of the wrench  10  to release a nut  70  securing a brake pipe  72  to a brake unit  74  will now be described with particular reference to  FIGS. 3 to 6 . In order to bring the fastener engaging surfaces  46  into engagement with the drive receiving surfaces  76  of the nut  70 , the head portion  14  of the wrench  10  is first moved to an open position such as those shown in  FIGS. 4 and 5 . To put it in an open position, the head portion  14  is pivoted about the rivet  24  until the outer end  54  of the passage  52  is fully exposed. While it may not always be necessary to go so far, fitting the wrench  10  onto the nut  70  is most easily achieved if the head portion  14  is positioned such that its lengthways direction is disposed at approximately 90° or more to the lengthways direction of the handle portion  12 . With the outer end  54  of the passage  52  fully exposed, the head portion  14  is moved transversely to the brake pipe  72  such that the pipe passes through the passage towards the fastener receiving aperture  50 . Once the brake pipe  72  is received in the fastener receiving aperture  50 , the wrench is moved in a direction along the pipe that brings the head portion  14  onto the nut  70  with the fastener engaging surfaces  46  engaging the drive receiving surfaces  76  of the nut. 
     Once the nut  70  is engaged in the fastener receiving aperture  48 , the handle portion  12  is rotated towards the head portion  14  (in the anticlockwise direction as viewed in  FIGS. 4 and 5 ) to close the wrench  10  and bring the rivet  20  into engagement with the notch  42 . Where convenient, this closing process may take place before the wrench is moved along the pipe  72  to engage the nut  70 . Continued rotation of the handle portion  12  in the anticlockwise direction presses the rivet  20  against the notch  42  to apply a moment to the free end of the leg portion  36  that pushes that end towards the leg portion  34  and in the process narrows the passage  52 . This movement of the leg portion  36  causes the arcuate portion  38  to flex and stretch around the nut  70  until the fastener engaging surfaces  46  firmly grip the nut. Once the nut  70  is firmly gripped, continued anticlockwise rotation of the handle portion  12  causes a torque to be applied to the nut  70 , which is turned anticlockwise and so released from the brake unit  74 . 
     It will be understood that the process of using the wrench  10  to release a nut  70  securing a brake pipe as previously described could be modified by fitting the head portion  14  to the nut without the handle portion  12  and then connecting the handle portion to the head portion. This may be convenient when the wrench is used in confined spaces. 
     It will be appreciated that the gripping force applied by the fastener engaging surfaces  46  will increase as the torque applied to the handle portion  12  increases and so in cases in which high levels of torque are needed to move a tight fastener, the gripping force will be increased and the wrench should not slip on the fastener. 
     It will be appreciated that the concave outer side surface portions  56  of the head portion  14  improve the flexibility of the head portion making it better able to adjust its shape in response to the applied torque for gripping a fastener, even in cases in which due to damage to the fastener, the fastener&#39;s drive receiving surfaces are rounded off and undersize such as to be quite different to the design size. 
     It will be appreciated that as viewed in  FIGS. 3 to 6 , in order to tighten the nut  70 , the same process would be followed, but with the wrench  10  flipped over to allow operation in the clockwise direction. 
     It will be appreciated that by making the head portion  14  releasable from the handle portion  12 , it is possible to have just one handle portion for a range of sizes of head portion. The differences in the head portions may be the size and/or shape of the fastener receiving aperture and/or the length or angularity of the head portion. It will be appreciated that there is economic efficiency in having one handle portion that can accommodate multiple interchangeable head portions. 
     It will be understood that in embodiments having a releasable, detachable, head portion, it will often be desirable to make the releasable connection between the head portion and handle portion sufficiently secure to prevent the head portion from being accidentally disconnected when in use. For example, the head portion may be configured to take advantage of the resilience of the material from which it is made such that the recess  40  receives the rivet  24  by snap-fitting. Alternatively, or additionally, the head portion may be fitted to the handle portion via a circuitous path that makes it difficult for the head portion to be disengaged from the handle portion by accident regardless of the strength of the actual connection between the head portion and handle portion. For example and referring to  FIG. 3 , the end region of the leg portion  34  that connects with the handle portion and the rivets  22 ,  24  could be configured such that the leg portion needs to be threaded into the connected position shown and will not readily be released. It will be understood that in general it will often be desirable for a detachable head portion to be quick-fit releasable by, for example, a push-fit and/or snap-fit connection. 
     It will be understood that where a releasably securable head portion is provided, it may be desirable to provide a release device to at least assist in releasing the head portion from the handle portion. The release device may take the form of an abutment surface positioned to apply a force that helps to break the connection between the head portion and handle portion in similar fashion to the rivet  26  shown in  FIG. 3 . It will of course be understood that many other release devices, which may comprise more complex mechanisms, could be used. 
     It will be appreciated that the head portion  14  could be secured to the handle portion  12  such that it can be permanently connected and for practical purposes not releasable. For a permanent connection, the rivet  26  is not needed and can be removed, if desired, to allow the head portion to be rotated anticlockwise (as viewed in  FIGS. 3 to 6 ) such that it can be stored in the gap  30  between the plate members  16 ,  18  of the handle portion. In that case, the rivet  28  could be positioned to act as a detent that would hold the head portion  14  within the gap  30 . Alternatively, a separate detent or other form of retention device could be used. 
     It will be appreciated that it is convenient to give the rivets that hold the halves of the handle portion together a dual function. However, it is to be understood that the pivot mounting for the head portion and abutment surfaces may be provided by means other than the rivets. It will also be appreciated that other forms of fastener could be substituted for the rivets and still have a dual function as described. 
     The wrench is described in use operating a nut  70  on a brake pipe  72 . It will be appreciated that this is not to be taken as limiting and that the wrench can be used to operate fasteners generally. In particular, while the wrench is particularly suited to use on fasteners incorporated in elongate structures, such as pipes, that would not be accessible to a conventional ring wrench, it will be appreciated that the wrench can be used on fasteners that could, for example, be accessed by a conventional open ended and/or ring wrench. 
     While certain embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims.