Abstract:
A pivot joint includes a first component ( 12 ) having a projecting boss form ( 16 ) and a second component ( 11 ) having an opening ( 25 ) for receiving the boss form ( 16 ). A headed fastener ( 32 ) and washer ( 27 ) engage with the boss form ( 16 ), which includes engagement elements ( 17 ) that dig into the washer ( 27 ) when the joint is assembled.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a pivot joint and more particularly a pivot joint which is intended for providing the pivot coupling of two components of an item of building hardware especially a window fastener. 
       BACKGROUND TO THE INVENTION 
       [0002]    Items of building hardware are known where one component needs to be coupled by a pivot joint to another component. Such an item of hardware is a window fastener in which typically a handle is pivotally coupled to a mounting base. An example of such a window fastener is the so-called “wedgeless” fastener which is the subject of our New Zealand patent specifications 205102 and 500423. 
         [0003]    It is a requirement of such a pivot joint that it exhibits good longevity characteristics. The window fastener will be put through many operations during its serviceable life time. Consequently, it is necessary that the joint is able to maintain its operating characteristics over many operational cycles. Also there is a requirement to achieve, in the manufacturing of such joints, a consistency of level of friction in the joints. 
         [0004]    It is an object of the present invention to provide a pivot joint for pivot coupling of two components in an item of building hardware that exhibits enhanced endurance performance. 
         [0005]    Manufacturers of items of hardware, especially window hardware are always striving to achieve savings in the manufacturing costs, whether such savings arise from lower manufactured costs of componentry or cost of labour associated with manufacture/assembling of the hardware. This is especially so with window fasteners where a window fastener is expected to meet operational requirements and longevity, yet at the lowest possible cost. Window fasteners are often seen as low cost items. However, this does not lessen the user demands and expectations associated with such an item of hardware. 
         [0006]    It is therefore a further object of the present invention to provide a joint design which can contribute to lessening of the manufactured cost of an item of hardware incorporating the joint. Each object is to be read disjunctively with the object of at least providing the public with a useful choice. 
       SUMMARY OF THE INVENTION 
       [0007]    In a first aspect the invention provides a pivot joint for coupling first and second components of an item of building hardware, the joint including:
   a boss form projecting from the first component;   an opening in the second component in which the boss form is rotationally engaged;   a headed fastener engaged with the boss form; and   a first washer engaged between the head of the headed fastener and a surface of the second component adjacent the opening;   wherein the boss form includes one or more engagement elements that dig into the first washer upon assembly of the pivot joint to couple the washer to the boss form.   
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]    In the following more detailed description of the invention according to one broad embodiment of the invention, reference will be made to the accompanying drawings in which:— 
           [0014]      FIG. 1  is an exploded view of the pivot joint incorporating the invention and forming part of a window fastener, 
           [0015]      FIG. 2  is a perspective underside view of the handle of the window fastener together with an enlarged detail of the body end and associated boss of the handle, 
           [0016]      FIG. 3  is a perspective view of a “top-hat” washer incorporated in the joint, 
           [0017]      FIG. 4  is a perspective view of the mounting base of the fastener, 
           [0018]      FIG. 5  is a top plan view of the mounting base, 
           [0019]      FIG. 6  is a section view on line A-A of  FIG. 5 , 
           [0020]      FIG. 7  is a perspective view of a washer incorporated in the joint, 
           [0021]      FIG. 8  is a plan view of the washer, 
           [0022]      FIG. 9  is a section on line B-B of  FIG. 8 , 
           [0023]      FIG. 10  is a perspective of a screw incorporated in the joint, 
           [0024]      FIG. 11  is a top plan view of the screw, 
           [0025]      FIG. 12  is a section view line C-C of  FIG. 11 , and 
           [0026]      FIG. 13  is a cross-sectional assembly view, of enlarged scale, of the joint incorporating the components of  FIGS. 2-12 . 
       
    
    
     DETAILED DESCRIPTION  
       [0027]    Referring firstly to  FIG. 1 , there is shown a partial view of a window fastener which incorporates a mounting base  11  to which is pivotally coupled a handle  12 . The handle is more fully shown in  FIG. 2  and comprises a lever  13  and a nib  14 , each of which is coupled to a body  15 . The window fastener  10  can be of a design whereby the nib  14  is intended to engage with a wedge plate or it can be of a “wedgeless” version whereby a wedge flap is pivotally coupled to the mounting base  11  and is moved between latching and non-latching positions in response to movement of the handle  12 . 
         [0028]    The particular form of the window fastener is not important to the invention. 
         [0029]    Projecting from the body  15  (see  FIG. 2 ) is a boss form  16 . This has formed therein an axial bore  18 . An annular wall or turret  17   a  is located at the distal end of the boss form  16  and forms the mouth of the bore  18 . Spaced radially about the turret  17   a  are a series of spikes  17 . These spikes, as will hereinafter become apparent, are intended to grip a washer  27  (see  FIGS. 7 to 9 ), which forms one of the components of the pivot joint. 
         [0030]    A top-hat washer is shown in  FIG. 3  and essentially consists of an annular body  20  with a flange  21  at one end. As can be seen in  FIG. 13 , this top-hat washer  19  engages with the boss form  16  so that the flange  21  engages against the surface of the body  15 , with handle  12  and the annular wall  20  extends alongside and in the same direction as the boss form  16  projects beyond the end of the body  15 . This top-hat washer  19  is made of a wear resistant material (e.g. a plastic material such as acetal) and separates the moving surfaces of the body  15  and boss form  16  from the mounting base  11 . 
         [0031]    The mounting base  11  as illustrated in the drawings, more particularly FIGS.  1  and  4 - 6 , is a mounting base  11  intended for a wedgeless type window fastener. Therefore, on the upper surface of the mounting base  11  there are provided constructional details  22  which are designed to accommodate the hinged or pivotable wedge flap (not shown). As these do not form any part of the present invention they will not be further described herein. The purposes of details  22  can, however, be ascertained from our New Zealand patent specifications 205102 and 500423 as can also the stop element  23  which provides end stops for the handle  12 . 
         [0032]    In the upper surface  24  of the mounting base  11  there is formed an opening  25 . As can be seen from  FIG. 13 , the opening  25  is of a size sufficient to accommodate the boss form  16  and the associated annular wall  20  of top-hat washer  19 . 
         [0033]    As is apparent from  FIG. 6  there is within the mounting base  11  a counterbore  26  which is coaxial with the opening  25 . This accommodates the washer  27  illustrated in  FIGS. 7-9 . 
         [0034]    The washer  27  is of generally annular shape and, as can be seen from  FIG. 9 , is symmetrical both in the horizontal plane (which is transverse to the washer&#39;s axis) and the vertical plane (which contains the washer&#39;s axis). It is therefore non-handed and can, accordingly be incorporated in the pivot joint either way round. 
         [0035]    The washer  27  is made of a suitable plastic material. A suitable material is Tenac-Lubricomp, which is a composition of ⅔ acetal and ⅓ polytetrafluoroethylene. This is by way of example, as it will be evident to those skilled in the art that other suitable materials could equally be used. 
         [0036]    The washer  27  includes a central bore  28  which is sized to accommodate the diameter of the turret  17   a  at the distal end of the boss form  16 . This bore  28  communicates either side with an outwardly flared transition portion  29  which in turn opens into a counterbore  30 . As is evident from  FIG. 9 , the transition portion  29  has a sidewall which inclines outwardly from the bore  28 . 
         [0037]    As is more evident from  FIG. 13 , the transition of the end of the boss form  16  to the turret  17   a  includes an inclined surface  31 . The slope of this inclined surface  31  is substantially commensurate with the slope of the transition section  29 . 
         [0038]    The components of the pivot joint are coupled together by way of a trilobular fastener  32  (see  FIGS. 10-12 ). This trilobular fastener  32 , which will for convenience hereinafter will be referred to as screw  32 , has a large washer-type head  33 . This includes a conventional recess  34  for engagement with a suitably shaped tool. Extending from the head  34  is shank  35 . A transition  36  in the form of an inclined wall  36  extends between the underside of the head  33  and the shank  35 . The slope of this wall  36  is substantially commensurate with the slope of the transition  29  of washer  27 . 
         [0039]    It will be appreciated that, while not shown, the shank  35  is provided with a male thread form which is engageable in the bore  18 . The bore  18  may be formed with a female thread form, or alternatively the screw  32  may be a self-tapping screw. Thus with the boss form  16  and associated top-hat washer  19  engaged through opening  25  in the mounting base  11 , the screw  32  with washer  27  engaged thereon can be screwed into the bore  18 . As is evident from  FIG. 13 , the boss form  16  and top hat washer  19  are engaged through opening  25  from the upper side of the mounting base  11 , while screw  32  and associated washer  27  are engaged through from the underside of the mounting base  11 . The washer  27  thus becomes located in the counterbore  26 . 
         [0040]    Upon the screw  32  being screwed into the opening  18  the spikes  17  engage with and grip into the material of the washer  27 . This is evident from  FIG. 13 . 
         [0041]    The screw  32  is screwed into bore  18  sufficiently to apply the required level of mechanical force to the washer  27  to thereby compress the washer  27  onto the base and hence create a desired level of friction in the pivot joint. 
         [0042]    In the preferred form of the invention this level of friction is reached when the sloping transition wall  36  of the screw  32  comes into engagement with a correspondingly sloped mouth surface  37  in the turret  17   a . Thus, uniformity of friction level is achieved by screwing the screw  32  hard down onto the surface of the mouth  37 . As is indicated in  FIG. 13  this creates a tight fit between the surface  36  of the screw  32  and the transition  29  of the washer  27 , and contact between the surface of the washer  27  and the floor surface of the counterbore  26  in the mounting base  11 . 
         [0043]    The pivot joint according to the present invention thus, uses one completely symmetrical plastic washer in place of multiple components such as a zinc washer and flat plastic washer typically employed in known pivot joint design. Also, the screw  32  has a large head diameter in order to maintain strength. These features combined with the triangular spikes  17  digging into the plastic washer  27 , so as to prevent the washer  27  from rotating other than with the boss form  16 , provide a joint of significantly enhanced endurance performance over known joints used in window fasteners. 
         [0044]    With the joint design according to the present invention, there is no need to orientate the washer as it is non-handed i.e. upside down installation is not possible. This is of benefit in a manufacturing procedure as it is no longer necessary to determine the orientation of the washer prior to installation. 
         [0045]    With known joint designs for window fasteners it is common for a washer component to have an angular shaped part which interengages with a correspondingly angular shape feature of the boss form to ensure a mechanical coupling such that the washer component moves with the boss form. Also, it is common to use an adhesive such as Loctite® to lock the washer component in place on the boss form. Such features are not required in the present invention due to the feature of the spike  17  digging into the plastic washer  27  to achieve an automatic mechanical coupling during assembly. 
         [0046]    The pivot joint, according to the present invention, also has one less component compared to existing joint designs thereby resulting to further economics of manufacture due to the absence of the cost of the additional component and the need to assemble this into the joint. 
         [0047]    Finally, the present invention provides greater allowance for differences in stack height due to more elasticity in the washer  27 . This leads to improved endurance of the friction established in the joint by the washer. 
         [0048]    While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant&#39;s general inventive concept.